JP4063564B2 - Polyurethane elastomer piezoelectric element, pressure sensor and contact sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polyurethane elastomer piezoelectric element using a piezoelectric effect of a fullerenol-introduced polyurethane elastomer, a pressure-sensitive sensor, and a contact sensor.
[0002]
[Prior art]
Conventionally, polyurethane elastomer actuators based on electrostriction have the greatest feature of being driven in the atmosphere by applying an electric field, rather than being driven in a solvent, and there are several drive voltages for actuators using ceramics and polymer materials. Whereas a high pressure of about 10 kV is required, a polyurethane elastomer actuator is characterized by having a large bending displacement at a relatively low voltage of several kV.
[0003]
However, from the point of view 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.
[0004]
However, such an actuator mechanism of polyurethane elastomer is caused by an electrostrictive effect based on voltage application, and so far, the piezoelectric effect that is integrated with the electrostrictive effect has not been manifested in polyurethane elastomers. It was. Therefore, a piezoelectric element using a polyurethane elastomer has not been developed.
[0005]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a piezoelectric element composed of a polyurethane elastomer.
Another object of the present invention is to provide a pressure-sensitive sensor and a contact sensor having a piezoelectric element made of polyurethane elastomer.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have shown that a polyurethane elastomer film that is introduced by using fullerenol as a curing agent in a polyurethane elastomer that can be deformed by electric field orientation exhibits a piezoelectric effect. The present inventors have found that a piezoelectric element that can be made of a polyurethane elastomer can be effectively used as a piezoelectric element, and has completed the present invention.
[0007]
That is, the present invention Polyurethane elastomer composed of a polyurethane elastomer into which fullerenol obtained by adding fullerenol to a urethane prepolymer prepared by reacting a polyisocyanate, a polyol and, if necessary, a chain extender is introduced. A polyurethane elastomer piezoelectric element having a fullerenol introduction ratio of 0.05 to 2% by weight based on the total amount of urethane prepolymer. It is. The polyurethane elastomer piezoelectric element may be a film or sheet made of a polyurethane elastomer into which fullerenol has been introduced.
[0008]
The present invention also provides a pressure-sensitive sensor and a contact sensor, wherein the polyurethane elastomer piezoelectric element is used as the piezoelectric element.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
[Polyurethane elastomer piezoelectric element]
The polyurethane elastomer piezoelectric element of the present invention is formed of a fullerenol-introduced polyurethane elastomer in which fullerenol is introduced into a polyurethane elastomer that can be deformed by electric field orientation. Therefore, the polyurethane elastomer piezoelectric element exhibits a potential on the surface by the action of pressure such as pressurization and stretching, and can exhibit a piezoelectric effect. This is because the fullerenol has a hydroxyl group formed in a star shape, so that the polymer chain constituting the polyurethane elastomer is three-dimensionally (three-dimensionally) crosslinked by the star-like hydroxyl group. This is probably because the tensile strength is increased. Specifically, by introducing fullerenol into the polyurethane elastomer, crosslinking of the polyurethane elastomer is promoted to increase the density of the three-dimensional network structure, 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 the pressure, an orderly orientation occurs, and as a result, the piezoelectric effect is expressed.
[0010]
Examples of the polyurethane elastomer into which fullerenol has been introduced include, for example, Japanese Patent No. 3026066, Japanese Patent Application Laid-Open No. 7-240544, Japanese Patent Application Laid-Open No. 8-335726, Japanese Patent Application Laid-Open No. 2000-101159, Japanese Patent Application Laid-Open No. 2000-101160, As a curing agent, polyisocyanate (particularly organic polyisocyanate), polyol (particularly high molecular polyol) as a raw material of polyurethane elastomer described in JP-A-2000-49397 and the like, and chain extender as necessary are used. It can be prepared using fullerenol. Specifically, the polyurethane elastomer can be prepared by, for example, reacting a polyisocyanate and a polyol by a conventionally known method and then reacting it with a chain extender or the like, or the above components (polyisocyanate, polyol, chain extension). It can be prepared by preparing a urethane prepolymer by a so-called one-shot method in which an agent and the like are reacted at a predetermined ratio at the same time, and then adding fullerenol and performing a reaction (particularly a curing reaction).
[0011]
In the urethane prepolymer, the ratio of polyisocyanate to polyol (NCO / OH) is preferably in the range of 1.5 to 9 (molar ratio).
[0012]
(Polyisocyanate)
Any polyisocyanate may be used as long as it has two or more isocyanate groups in the molecule. For example, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 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 (isocyanate) Tomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, m-phenylene diisocyanate, p-phenylene diisocyanate, 1,5-naphthalene diisocyanate, 4,4′-diphenimethane 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, poly Examples include methylene polyfernyl polyisocyanate, isocyanurate-modified products, carbodiimidization-modified products, and burette-modified products of these polyisocyanates. Polyisocyanate may use only 1 type or may use 2 or more types together.
[0013]
(Polyol)
As the polyol, polymer polyols such as polyester polyols, polyether polyols, polycarbonate polyols, and polybutadiene polyols can be suitably used. A polyol can be used individually or in combination of 2 or more types. In addition, as a polymer polyol, you may use what blended polyolefin polyol suitably to these illustrated polymer polyols. A polyol may use only 1 type or may use 2 or more types together.
[0014]
Examples of the polyester-based polyol include a condensate of a polycarboxylic acid and a low-molecular polyol having 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 (neopentylene adipate) (“PNA”), a polyol composed of 3-methyl-1,5-pentanediol and adipic acid, a random copolymer of PEA and PDA A random copolymer of PEA and PPA, a random copolymer of PEA and PBA, a random copolymer of PHA and PNA, or caprolactone polyol obtained by ring-opening polymerization of ε-caprolactone, β-methyl-δ-valero Polyols obtained by ring opening of lactone with ethylene glycol, etc. The amount average molecular weight of 500 to 10,000 is preferred) and the like. Each component (polycarboxylic acid, low molecular polyol, etc.) for preparing the polyester polyol can be used alone or in combination. Furthermore, as a polyester-type polyol, the copolymer by the at least 1 sort (s) of glycol component among at least 1 sort (s) of an acid component and the glycol component illustrated below is mentioned, for example.
[0015]
Acid components: terephthalic acid, isophthalic acid, phthalic anhydride, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid (mixture), paraoxybenzoic acid, trimellitic anhydride, ε-caprolactone, β- Methyl-δ valerolactone.
[0016]
Glycol component: ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, 1,9-nonanediol, Methyl octanediol, neopentyl glycol, polyethylene glycol, polytetramethylene glycol, 1,4-cyclohexanedimethanol, pentaerythritol, 3-methyl-1,5-pentanediol.
[0017]
The polyether polyol can be obtained, for example, by ring-opening addition polymerization using an alkylene oxide (for example, ethylene oxide, propylene oxide, etc.) and a polyhydric alcohol (for example, diethylene glycol) which is an active hydrogen compound as an initiator. Specifically, the polyether polyol includes, for example, polytetramethylene glycol (“PTMG”), polypropylene glycol (“PPG”), polyethylene glycol (“PEG”), polyoxymethylene, propylene oxide and ethylene oxide. And the like. Further, the polyether polyol may be prepared by cationic polymerization of tetrahydrofuran and may have a weight average molecular weight of 500 to 5,000. Specifically, polytetramethylene ether glycol ("PTMG"), which is a homopolymer of tetrahydrofuran, tetrahydrofuran is a copolymer of alkylene oxide (for example, a copolymer of tetrahydrofuran and propylene oxide, tetrahydrofuran and ethylene oxide) And a copolymer thereof. All of these polyether-based polyols preferably have a weight average molecular weight of 500 to 10,000. Each component (alkylene oxide etc.) for preparing the polyether polyol can be used alone or in combination.
[0018]
Polycarbonate-based polyols obtained by condensation of conventionally known polyols (polyhydric alcohols) with phosgene, chloroformate esters, dialkyl carbonates or diallyl carbonates and having various molecular weights are known. Particularly preferred as such polycarbonate-based polyols are those using 1,6-hexanediol, 1,4-butanediol, 1,3-butanediol, neopentyl glycol, or 1,5-pentanediol as the polyol. The weight average molecular weight is in the range of about 500 to 10,000. Examples of the polycarbonate polyol include poly (hexanediol carbonate) and poly (nonanediol carbonate). Each component for preparing the polycarbonate polyol can be used alone or in combination.
[0019]
As the polybutadiene-based polyol, a hydroxyl group-containing liquid diene-based polymer can be used. As the hydroxyl group-containing liquid diene polymer, those having a weight average molecular weight of 600 to 3000 and an average hydroxyl group number (functional group number) of 1.7 to 3.0 are preferable, for example, depending on a diene component having 4 to 12 carbon atoms. Butadiene-based polymers such as polymers or copolymers, and copolymers of these diene components (monomers) and copolymerizable monomers (for example, α-olefinic addition polymerizable monomers having 2 to 22 carbon atoms). The terminal is modified with a hydroxyl group. Specifically, polybutadiene-based polyols include butadiene homopolymer, isoprene homopolymer, butadiene-styrene copolymer, butadiene-isoprene copolymer, butadiene-acrylonitrile copolymer, butadiene-2-ethylhexyl acrylate copolymer, butadiene-n-octadecyl acrylate copolymer, and the like. Examples are those in which the terminal of the butadiene-based polymer is modified with a hydroxyl group. In these hydroxyl group-containing liquid diene polymers, the liquid diene polymer can be produced, for example, by subjecting a conjugated diene monomer to a heat reaction in the presence of hydrogen peroxide in a liquid reaction medium.
[0020]
In addition, as a polyol as a raw material of a polyurethane elastomer, a polyolefin polyol in which the above hydroxyl group-containing liquid diene polymer is hydrogenated (a double bond is saturated) can also be used.
[0021]
(Chain extender)
As the chain extender, any chain extender may be used as long as it is used as needed and generally used when chain extending the urethane prepolymer. Examples of the chain extender include low molecular weight polyol compounds and polyamine compounds. Only one type of chain extender may be used, or a plurality of types may be used in combination. As the low molecular weight polyol compound as the chain extender, any of primary polyol, secondary polyol, and tertiary polyol may be used, but diol is preferred. Specifically, examples of the low molecular weight polyol compound 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 Examples include diol, 2,4-hexanediol, 2-ethyl-1,3-hexanediol, cyclohexanediol, and 2-ethyl-2- (hydroxymethyl) -1,3-propanediol. As the polyamine compound, any of primary amines, secondary amines, tertiary amines such as diamine, triamine, and tetraamine can be used. Specifically, examples of the polyamine compound include aliphatic amines such as hexamethylenediamine, alicyclic amines such as 3,3′-dimethyl-4,4′-diaminodicyclohexylmethane, and 4,4′-methylenebis-2- Aromatic amines such as chloroaniline, 2,2 ′, 3,3′-tetrachloro-4,4′-diaminophenylmethane, 4,4′-diaminodiphenyl, 2,4,6-tris (dimethylaminomethyl) Phenol etc. are mentioned. As the chain extender, a low molecular weight polyol compound (particularly, diol) is suitable.
[0022]
In the present invention, a urethane prepolymer and a chain extender are mixed, and the method for extending the urethane prepolymer includes a mixing ratio of the chain extender to the urethane prepolymer, a reaction temperature, a reaction time, and the like. It can carry out by a well-known method including.
[0023]
(Fullerenol)
Fullerenol is fullerene (C) ₆₀ ) In which a hydroxyl group is introduced, and the hydroxyl group is usually introduced into 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 preferably has 5 to 18 hydroxyl groups per molecule, and further has 8 to 15 (particularly 10 to 12) hydroxyl groups. Is preferred. In addition, the site | part in which the hydroxyl group in fullerene is introduce | transduced is not restrict | limited in particular.
[0024]
Fullerenol can be used alone or in combination of two or more.
[0025]
Such fullerenol is prepared by, for example, obtaining a sulfonated fullerene by adding a sulfuric acid (particularly fuming sulfuric acid) to fullerene to carry out a sulfonation reaction, and further hydrolyzing the sulfonated fullerene. Can do. Specifically, in the sulfonation reaction, the ratio of fullerene and fuming sulfuric acid can be selected from a range of about 15 ml of fuming sulfuric acid with respect to 1 g of fullerene. The sulfonation reaction time can be selected from the range of 1 to 4 weeks. On the other hand, the hydrolysis reaction time can be selected from a range of 1 to 3 days.
[0026]
(Additive)
The polyurethane elastomer may contain various additives. Examples of such additives include plasticizers, flame retardants, fillers, stabilizers, colorants, and the like. As the plasticizer, a nonionic plasticizer is preferable. Specifically, as the plasticizer, for example, dioctyl phthalate (“DOP”), dibutyl phthalate (“DBP”), dioctyl adipate (“DOA”), triethylene glycol dibenzoate, tricresyl phosphate, Dioctyl phthalate, fatty acid ester of pentaerythritol, dioctyl sebacate, diisooctyl azelate, dibutoxyethoxyethyl adipate, and the like can be used.
[0027]
[Fullerenol-introduced polyurethane elastomer]
In the present invention, it suffices if fullerenol is introduced into the polyurethane elastomer. For example, fullerenol can be introduced into the polyurethane elastomer as a curing agent. That is, as described above, a urethane prepolymer can be reacted with fullerenol to prepare a fullerenol-introduced polyurethane elastomer. The proportion of fullerenol is about 0.05 to 2% by weight (preferably 0.08 to 1% by weight, more preferably 0.1 to 0.5% by weight) with respect to the total amount (solid content) of the urethane prepolymer. You can choose from a range. When the ratio of fullerenol is less than 0.05% by weight or more than 2% by weight with respect to the total amount (solid content) of the urethane prepolymer, the piezoelectricity is lowered.
[0028]
The fullerenol-introduced polyurethane elastomer can be used alone or in combination of two or more.
[0029]
The method for producing the fullerenol-introduced polyurethane elastomer by reacting the urethane prepolymer with fullerenol is not particularly limited. For example, a mixture of the urethane prepolymer and fullerenol is heated to obtain a urethane prepolymer and fullerenol. The method of preparing by making this react is mentioned. As this reaction temperature, it can select from the range of about 80-150 degreeC (preferably 85-100 degreeC), for example. Moreover, as reaction time, it can select from the range of about 30 minutes-2 hours (preferably 1 hour 30 minutes-2 hours), for example.
[0030]
In addition, in this invention, well-known thru | or a usual hardening | curing agent can be used as a hardening | curing agent as a hardening | curing agent of a polyurethane or a polyurethane elastomer with the said fullerenol. As such known or commonly used curing agents, the low molecular weight polyol compounds and polyamine compounds exemplified in the section of the chain extender can be used.
[0031]
[Piezoelectric element fabrication method]
The method for producing the polyurethane elastomer piezoelectric element of the present invention (that is, the polyurethane elastomer piezoelectric element having a fullerenol-introduced polyurethane elastomer) is not particularly limited. For example, the polyurethane elastomer piezoelectric element is in the form of a film, sheet, or thin film Can be produced by molding a fullerenol-introduced polyurethane elastomer into a film, sheet or thin film. That is, the polyurethane elastomer piezoelectric element constituted by the fullerenol-introduced polyurethane elastomer of the present invention (sometimes referred to as “fullerenol-introduced polyurethane elastomer piezoelectric element”) is a film or sheet (particularly a film) as well as a thin film. Form may be sufficient.
[0032]
Specifically, when the fullerenol-introduced polyurethane elastomer is molded 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. In this case, the mold release agent can be removed after molding. For removal of the mold release agent of the molded polyurethane elastomer, removal by ordinary wet cleaning is sufficient. For example, ion / ozone such as plasma treatment by glow discharge or corona discharge treatment as surface modification for electrode application -It is preferable to remove impurities such as a release agent using electrons and ultraviolet rays.
[0033]
Electrodes (thickness of about 0.05 to 10 μm) may be formed on one side or both sides of the piezoelectric element made of the fullerenol-introduced polyurethane elastomer. Examples of the material of the electrode include metal compounds such as gold, platinum, aluminum, metal indium, indium oxide, stannic oxide, ITO, silver, and metal compounds such as alloys, and conductive resins such as polyaniline and elastomer rubber, Carbon or 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. As a method for forming the electrode, for example, an ion plating method, a plasma CVD method, an ion sputtering coating method, a vacuum deposition method, a screen printing, an ion beam assist method, an ionization deposition method, or the like can be employed.
[0034]
[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.
[0035]
As a pressure sensor or a contact sensor, for example, as shown in FIG. 4, a row electrode side sheet-like base material 2 having a row electrode 21 and a pressure sensitive conductive layer 22 for a row electrode, a column electrode 31 and a column electrode. The surface of the pressure-sensitive conductive layer (22, 32) formed on each sheet-like substrate (2, 3) is mutually connected to the column electrode side sheet-like substrate 3 having the pressure-sensitive conductive layer 32 for use. The layers may be stacked so as to face each other. Specifically, the row electrode side sheet-like substrate 2 having the row electrode 21 and the row electrode pressure-sensitive conductive layer 22 prints the row electrodes 21 on the row electrode side sheet-like substrate 2 at a constant pitch interval. It can be produced by coating the fullerenol-introduced polyurethane elastomer by printing or the like to form the pressure-sensitive conductive layer 22 for the row electrode so as to surround the row electrode 21. Moreover, the column electrode side sheet-like base material 3 having the column electrode 31 and the column electrode pressure-sensitive conductive layer 32 is printed on the column electrode side sheet-like base material 3 at a predetermined pitch interval, vapor deposition, or the like. And a fullerenol-introduced polyurethane elastomer is applied by printing or the like so as to surround the column electrode 31 to form the column electrode pressure-sensitive conductive layer 32.
[0036]
When the pressure sensitive conductive layer 22 for row electrodes and the pressure sensitive conductive layer 32 for column electrodes are formed by printing with a fullerenol-introduced polyurethane elastomer, various printing methods (for example, a screen printing method) can be employed. . Of course, when forming the pressure-sensitive conductive layer 22 for row electrodes and the pressure-sensitive conductive layer 32 for column electrodes with a fullerenol-introduced polyurethane elastomer, any method other than printing can be used as long as it can form various patterns. Any method (for example, vapor deposition method) can be adopted.
[0037]
In addition, since the pressure sensitive conductive layer 22 for row electrodes and the pressure sensitive conductive layer 32 for column electrodes can be formed by printing a fullerenol-introduced polyurethane elastomer in this way, not only a plane but also a three-dimensional shape can be formed. It can also be formed on a curved surface bent. Therefore, the pressure-sensitive sensor and the contact sensor of the present invention can be formed not only in a linear or planar form but also in a form having a curved shape that is three-dimensionally bent. Therefore, the sensor of the pressure sensor or the contact sensor of the present invention can be used by being attached to a portion having a curved surface shape that is three-dimensionally bent in an arm (arm) of a robot, for example.
[0038]
It should be noted that the pressure-sensitive sensor and contact sensor of the present invention can also be used as a pressure distribution sensor for sensing pressure distribution.
[0039]
【The invention's effect】
According to the polyurethane elastomer piezoelectric element of the present invention, even if a polyurethane elastomer is used, the piezoelectric effect can be effectively exhibited. Therefore, the polyurethane elastomer piezoelectric element is extremely useful as a piezoelectric element in a pressure-sensitive sensor and a contact sensor.
[0040]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited by these Examples.
[0041]
(Fullerenol Preparation Example 1)
3 g of fullerene 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. Thus, fullerenol was prepared.
[0042]
Example 1
100 parts by weight of poly-3methyl-1,5-pentaneadipate polyol (PMPA, manufactured by Kuraray Co., Ltd., trade name “Kurapol P3010”) having an average molecular weight of 2,945, paraphenylene diisocyanate (PPDI, manufactured by DuPont Co., Ltd., product) 10.8 parts by weight of the name “Hylen”) was added and reacted at 85 ° C. for 2 hours under a nitrogen stream to obtain a urethane prepolymer having a terminal isocyanate group.
[0043]
The fullerenol obtained in Preparation Example 1 of fullerenol is added to the urethane prepolymer at a ratio of 0.25% by weight with respect to the total amount of the urethane prepolymer (solid content), and the temperature is kept at 110 ° C. in advance. A fullerenol-introduced polyurethane elastomer into which fullerenol had been introduced was prepared by pouring into a mold having a thickness of 0.2 mm and leaving it in an oven at 110 ° C. for 24 hours to carry out a curing reaction.
[0044]
The fullerenol-introduced polyurethane elastomer was formed into a film having a thickness of 200 μm by casting to produce a film-like fullerenol-introduced polyurethane elastomer, and a fullerenol-introduced polyurethane elastomer piezoelectric element was fabricated.
[0045]
(Evaluation of piezoelectric characteristics)
The fullerenol-introduced polyurethane elastomer piezoelectric element produced in Example 1 was pressurized, the induced voltage generated when the pressure was applied was measured, the piezoelectricity at the time of pressurization was evaluated, and the measurement results are shown in FIG. .
[0046]
Specifically, a fullerenol-introduced polyurethane elastomer piezoelectric element (film) is pressed with a weight (0 to 3 kg in weight), and the voltage (mV) generated on both surfaces of the piezoelectric element with respect to the load (g) during pressing. When the pressure is removed (released), the voltage (mV) generated on both surfaces of the piezoelectric element is measured, and the pressure (g) during pressurization or pressurization is released A graph of the relationship between the applied load (g) and the voltage (mV) generated on both surfaces of the piezoelectric element is shown in FIG.
[0047]
As shown in FIG. 1, when the film-like fullerenol-introduced polyurethane elastomer according to Example 1 was pressurized, it was confirmed that 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.
[0048]
In addition, the fullerenol-introduced polyurethane elastomer piezoelectric element produced in Example 1 was stretched, the induced voltage generated during the stretching was measured, the piezoelectricity during stretching was evaluated, and the measurement results are shown in FIG. .
[0049]
Specifically, a fullerenol-introduced polyurethane elastomer piezoelectric element (film) was stretched 1.5 times, and the change in voltage (mV) generated on both surfaces of the piezoelectric element during stretching was measured. Is shown in FIG.
[0050]
From FIG. 2, it was confirmed that even by stretching, a potential with a quick response was regularly induced on the film surface as shown in FIG. 2, and a typical piezoelectric effect was exhibited.
[0051]
Therefore, by amplifying the voltage generated with pressurization and stretching and applying appropriate signal processing, the fullerenol-introduced polyurethane elastomer piezoelectric element of the example can be made into various flexible and flexible pressure characteristics unique to polyurethane elastomer. It can be applied as a sensor or contact sensor.
[0052]
(Example 2)
3 g of fullerene 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, and further distilled water is added and stirred at 85 ° C. for 3 days to carry out a hydrolysis reaction. Thus, three types of fullerenol having different numbers of hydroxyl groups introduced into the molecule were prepared.
[0053]
Using these three types of fullerenols having different numbers of hydroxyl groups, in the same manner as in Example 1, respectively, fullerenol-introduced polyurethane elastomers into which fullerenol had been introduced were prepared. In the same manner as in Example 1, a film-like fullerenol-introduced polyurethane elastomer piezoelectric element was produced.
[0054]
This fullerenol-introduced polyurethane elastomer piezoelectric element (in the form of a film) was measured for an induced voltage generated when a constant (200 g) pressure was applied, and the piezoelectricity due to the difference in the number of hydroxyl groups contained in fullerenol was evaluated. The measurement results are shown in FIG. Specifically, a fullerenol-introduced polyurethane elastomer piezoelectric element (film) is pressed with a weight (weight 200 g), and the voltage (mV) generated on both surfaces of the piezoelectric element when the pressure is applied (load 200 g) is measured. 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 by pressurization (200 g) is shown in FIG. In the graph shown in FIG. 3, the horizontal axis indicates the transmittance (% T), but the lower transmittance corresponds to a fullerenol-introduced polyurethane elastomer piezoelectric element having a larger number of hydroxyl groups of fullerenol, On the contrary, the higher transmittance corresponds to a fullerenol-introduced polyurethane elastomer piezoelectric element having a smaller number of hydroxyl groups of fullerenol.
[0055]
From FIG. 3, it was confirmed that the induced voltage increased as the number of hydroxyl groups contained in fullerenol increased.
[Brief description of the drawings]
FIG. 1 shows a load (g) at the time of pressurization when a piezoelectric element according to an embodiment is pressurized or a load (g) that is applied at the time of release of pressure and a voltage (mV) generated on both surfaces of the piezoelectric element. It is a figure which shows the graph of a relationship.
FIG. 2 is a graph showing a time (second) change in 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 by pressurization (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 a pressure-sensitive sensor of the present invention.
[Explanation of symbols]
1 Pressure sensor
Two-row electrode sheet base material
21 row electrode
22 Pressure-sensitive conductive layer for row electrodes
Three-row electrode-side sheet-like substrate
31 row electrode
32 pressure sensitive conductive layer for row electrode

Claims (4)

A polyurethane elastomer composed of a polyurethane elastomer into which a fullerenol obtained by adding a fullerenol to a urethane prepolymer prepared by a reaction of a polyisocyanate, a polyol, and a chain extender as required is introduced. A polyurethane elastomer piezoelectric element, wherein the introduction ratio of fullerenol is 0.05 to 2% by weight based on the total amount of the urethane prepolymer .   2. The polyurethane elastomer piezoelectric element according to claim 1, which is a film or sheet composed of a polyurethane elastomer into which fullerenol is introduced.   A pressure-sensitive sensor using the polyurethane elastomer piezoelectric element according to claim 1 or 2 as the piezoelectric element.   A contact sensor characterized in that the polyurethane elastomer piezoelectric element according to claim 1 or 2 is used as the piezoelectric element.

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