Polyurethane elastomer piezoelectric element, pressure- sensitive sensor and contact sensor

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a polyurethane elastomer piezoelectric element utilizing the piezoelectric effect of a furarenol-introduced polyurethane elastomer, a pressure sensitive sensor, and a contact sensor.

【0002】

[Conventional technology]

Conventionally, the polyurethane elastomer actuator by the electrolytic strain effect is not a driving method in a solvent, but is driven in the atmosphere by applying an electric field, and the driving voltage of the actuator using a ceramic or a polymer material is several. While a high voltage of about 10 kV is required, the polyurethane elastomer actuator is also characterized by having a large bending displacement at a relatively low voltage of several kV.

【0003】

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.

【0004】

However, such an actuator mechanism of the polyurethane elastomer is generated by an electrostrain effect based on voltage application, and so far, the piezoelectric effect that is two sides of the same coin with the electrostrain effect has not been exhibited in the polyurethane elastomer. It was. Therefore, a piezoelectric element made of polyurethane elastomer has not been developed.

【0005】

[Problems to be Solved by the Invention]

Therefore, an object of the present invention is to provide a piezoelectric element made 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 a polyurethane elastomer.

【0006】

[Means for solving problems]

As a result of diligent studies to solve the above problems, the present inventors have exhibited a piezoelectric effect in a film made of a polyurethane elastomer in which flarenol is used as a curing agent and introduced into a polyurethane elastomer that can be deformed by electric field orientation. The present invention has been completed by finding that a piezoelectric element made of a polyurethane elastomer can be effectively used as a piezoelectric element.

【0007】

That is, the present invention is a polyurethane elastomer piezoelectric element characterized in that it is composed of a polyurethane elastomer into which flarenol has been introduced. The polyurethane elastomer piezoelectric element may be a film or sheet made of a polyurethane elastomer into which flarenol has been introduced.

【0008】

Further, the present invention is a pressure-sensitive sensor and a contact sensor, characterized in that the 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 is formed of a furlenol-introduced polyurethane elastomer in which flarenol is introduced into a polyurethane elastomer that can be deformed by electric field orientation. Therefore, the polyurethane elastomer piezoelectric element can exert a piezoelectric effect by developing an electric potential on the surface by the action of pressure such as pressurization or stretching. This is because the flarenol has a star-shaped hydroxyl group, so that the polymer chains constituting the polyurethane elastomer are sterically (three-dimensionally) crosslinked by the star-shaped hydroxyl group. This is probably because the tensile strength is increasing. Specifically, the introduction of flarenol into the polyurethane elastomer promotes cross-linking of the polyurethane elastomer, increases the density of the three-dimensional network structure, and strengthens the interaction between the molecular chains of the polyurethane elastomer. It is considered that the conformational change of the molecular chain with respect to pressure causes an ordered orientation, and as a result, the piezoelectric effect is exhibited.

【0010】

Examples of the polyurethane elastomer into which flarenol is introduced include Patent No. 3026066, JP-A-7-240544, JP-A-8-335726, JP-A-2000-101159, and JP-A-2000-101160. Polyisocyanates (particularly organic polyisocyanates) and polyols (particularly polymer polyols) as raw materials for polyurethane elastomers described in JP-A-2000-49397 and the like are used, and if necessary, chain extenders and the like are used, and as a curing agent. It can be prepared using flarenol. Specifically, the polyurethane elastomer can be prepared by, for example, a method of reacting a polyisocyanate with a polyol by a conventionally known method and then reacting the polyisocyanate with a chain extender or the like, or the above-mentioned components (polyisocyanate, polyol, chain extension). It can be prepared by preparing a urethane prepolymer by a so-called one-shot method or the like in which agents and the like are reacted at the same time at a predetermined ratio, and then adding flarenol to carry out a reaction (particularly, a curing reaction).

【0011】

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

【0012】

(Polyisocyanate) The polyisocyanate may be any one having 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-cyclohexanediisocyanate, 1,4-cyclohexanediisocyanate, 4,4 ́-methylenebis (cyclohexyl) Isocyanate), 1-methyl-2,4-cyclohexane diisocyanate, 1-methyl-2,6-cyclohexane diisocyanate, 1,3-bis (isocyanate methyl) cyclohexane, 1,4-bis (isocyanate methyl) cyclohexane, m-phenylene Diisocyanate, p-phenylenediocyanate, 1,5-naphthalenediocyanate, 4,4 ́-diphenimethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4 ́-Toluene diisocyanate, dianisine diisocyanate, 4,4 ́-diphenyl ether diisocyanate, 1,3-xylylene diisocyanate, ω, ω ́-diisocyanate-1,4-diisocyanate, polymethylenepolyfernyl polyisocyanate, and their polys Examples thereof include isocyanurate-modified products, carbodiimide-modified products, and burette-modified products of isocyanates. Only one type of polyisocyanate may be used, or two or more types may be used in combination.

【0013】

As the (polyol) polyol, a polymer polyol such as a polyester-based polyol, a polyether-based polyol, a polycarbonate-based polyol, or a polybutadiene-based polyol can be preferably used. The polyols can be used alone or in combination of two or more. As the polymer polyol, those in which a polyolefin-based polyol is appropriately blended with these exemplified polymer polyols may be used. Only one kind of polyol may be used, or two or more kinds may be used in combination.

【0014】

Examples of the polyester-based polyol include a condensate of a polycarboxylic acid and a low-molecular-weight polyol having a weight average molecular weight of 500 to 10000. 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"), polyol consisting of 3-methyl-1,5-pentanediol and adipic acid, random copolymer of PEA and PDA , PEA and PPA random copolymer, PEA and PBA random copolymer, PHA and PNA random copolymer, or caprolactone polyol obtained by ring-opening polymerization of ε-caprolactone, β-methyl-δ-valero Examples thereof include polyols obtained by ring-opening the lactone with ethylene glycol (all of which preferably have a weight average molecular weight of 500 to 10000). Each component (polycarboxylic acid, low molecular weight polyol, etc.) for preparing a polyester-based polyol can be used alone or in combination of two or more. Further, examples of the polyester-based polyol include a copolymer consisting of at least one acid component among the acid components exemplified below and at least one glycol component among the glycol components.

【0015】

Acid components: terephthalic acid, isophthalic acid, phthalic anhydride, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecane diic acid, dimer acid (mixture), paraoxybenzoic acid, trimellitic anhydride, ε-caprolactone, β- Methyl-δ valerolactone.

【0016】

Glycol components: 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.

【0017】

As the polyether polyol, for example, alkylene oxide (for example, ethylene oxide, propylene oxide, etc.) can be obtained by ring-opening addition polymerization using a polyhydric alcohol (for example, diethylene glycol) as an active hydrogen compound as an initiator. Specifically, the polyether polyols include, for example, polytetramethylene glycol (PTMG), polypropylene glycol (PPG), polyethylene glycol (PEG), polyoxymethylene, propylene oxide and ethylene oxide. Copolymers and the like are included. Further, the polyether polyol may be prepared by cationic polymerization of tetrahydrofuran and have a weight average molecular weight of 500 to 5000. Specifically, polytetramethylene ether glycol (PTMG), which is a homopolymer of tetrahydrofuran, and tetrahydrofuran is a copolymer of alkylene oxide (for example, a copolymer of tetrahydrofuran and propylene oxide, tetrahydrofuran and ethylene oxide). (Copolymer with and etc.). All of these polyether polyols preferably have a weight average molecular weight of 500 to 10000. Each component (alkylene oxide or the like) for preparing a polyether polyol can be used alone or in combination of two or more.

【0018】

As the polycarbonate-based polyol, those obtained by condensation of a conventionally known polyol (polyhydric alcohol) with phosgene, chloroformic acid ester, dialkyl carbonate or diallyl carbonate, and having various molecular weights are known. Particularly preferable as such a polycarbonate-based polyol is a polyol using 1,6-hexanediol, 1,4-butanediol, 1,3-butanediol, neopentyl glycol, or 1,5-pentanediol. The weight average molecular weight is in the range of about 500 to 10000. Examples of the polycarbonate-based polyol include poly (hexanediol carbonate) and poly (nonanediol carbonate). Each component for preparing the polycarbonate-based polyol can be used alone or in combination of two or more.

【0019】

As the polybutadiene-based polyol, a hydroxyl group-containing liquid diene-based polymer can be used. The hydroxyl group-containing liquid diene polymer preferably has a weight average molecular weight of 600 to 3000 and an average number of hydroxyl groups (functional groups) of 1.7 to 3.0. For example, a polymer or a copolymer containing a diene component having 4 to 12 carbon atoms. The end of a butadiene polymer such as a polymer or a copolymer of these diene components (monomers) and a copolymerizable monomer (for example, an α-olefinic addition polymerizable monomer having 2 to 22 carbon atoms) is hydroxylated. Examples include those modified based on the basis. Specifically, examples of the polybutadiene-based polyol include butadiene homopolymer, isoprene homopolymer, butadiene-styrene copolymer, butadiene-isoprene copolymer, butadiene-acrylonitrile copolymer, butadiene-2-ethylhexyl acrylate copolymer, and butadiene-n-octadecyl acrylate copolymer. Can be exemplified by modifying the terminal of the butadiene-based copolymer of the above to a hydroxyl group. Among these hydroxyl group-containing liquid diene-based polymers, the liquid diene-based polymer can be produced, for example, by heating and reacting a conjugated diene monomer in the presence of hydrogen peroxide in a liquid reaction medium.

【0020】

As the polyol as a raw material of the polyurethane elastomer, a polyolefin-based polyol in which the above-mentioned hydroxyl group-containing liquid diene-based polymer is hydrogenated (double bond is saturated) can also be used.

【0021】

(Chain extender) As the chain extender, any one may be used as long as it is used as needed and is generally used for chain extension of urethane prepolymers. 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 a primary polyol, a secondary polyol, and a tertiary polyol may be used, but a diol is preferable. Specifically, low molecular weight polyol compounds include trimethylolpropane (TMP), ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 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 thereof include diols, 2,4-hexanediols, 2-ethyl-1,3-hexanediols, cyclohexanediols, 2-ethyl-2- (hydroxymethyl) -1,3-propanediols and the like. Further, as the polyamine compound, any of primary amine, secondary amine, tertiary amine and the like such as diamine, triamine and tetraamine can be used. Specifically, as the polyamine compound, an aliphatic amine such as hexamethylenediamine, an alicyclic amine 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) Examples include phenol. As the chain extender, a low molecular weight polyol compound (particularly, a diol) is suitable.

【0022】

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

【0023】

(Fullerenol) Fullerene is fullerene (C)₆₀), And the hydroxyl group is usually introduced into fullerene in a star-like form. The number of hydroxyl groups in flarenol is not particularly limited, but is preferably 2 or more (for example, 2 to 20) per molecule. In the present invention, flarenol preferably has 5 to 18 hydroxyl groups per molecule, and more preferably has 8 to 15 (particularly, 10 to 12) hydroxyl groups. Suitable. The site where the hydroxyl group is introduced in the fullerene is not particularly limited.

【0024】

Fullerenol can be used alone or in combination of two or more.

【0025】

Such fullerenes can be prepared, for example, by adding sulfuric acid (particularly fuming sulfuric acid) to fullerenes to carry out a sulfonate reaction to obtain sulfonated fullerenes, and further hydrolyzing the sulfonated fullerenes. Can be done. Specifically, in the sulfonate reaction, the ratio of fullerene to fuming sulfuric acid can be selected from the range of about 15 ml of fuming sulfuric acid with respect to 1 g of fullerene. The sulfonate 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 the range of 1 to 3 days.

【0026】

(Additives) The polyurethane elastomer may contain various additives and the like. Examples of such additives include plasticizers, flame retardants, fillers, stabilizers, colorants and the like. As the plasticizer, a nonionic plasticizer is preferable. Specifically, examples of the plasticizer include dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl adipate (DOA), triethylene glycol dibenzoate, and tricresyl phosphate. Dioctyl phthalate, fatty acid ester of pentaeristol, dioctyl sebacate, diisooctyl azelaate, dibutoxyethoxyethyl adipate and the like can be used.

【0027】

[Flarenol-introduced polyurethane elastomer] In the present invention, flarenol may be introduced into the polyurethane elastomer. For example, flarenol 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 flarenol to prepare a fulllarenol-introduced polyurethane elastomer. The ratio of flarenol can be selected from the range of 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. If the proportion of flarenol 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 flarenol-introduced polyurethane elastomer can be used alone or in combination of two or more.

【0029】

The method for producing the furlenol-introduced polyurethane elastomer by reacting the urethane prepolymer with flarenol is not particularly limited. For example, a mixture of the urethane prepolymer and flarenol is heated to obtain the urethane prepolymer and flarenol. Examples thereof include a method of preparing by reacting. The reaction temperature can be selected from, for example, a range of about 80 to 150 ° C (preferably 85 to 100 ° C). The reaction time can be selected from, for example, a range of about 30 minutes to 2 hours (preferably 1 hour 30 minutes to 2 hours).

【0030】

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

【0031】

[Method for manufacturing piezoelectric element] The method for producing the polyurethane elastomer piezoelectric element of the present invention (that is, the polyurethane elastomer piezoelectric element provided with the flarenol-introduced polyurethane elastomer) is not particularly limited, and for example, the polyurethane elastomer piezoelectric element is in the form of a film or When it has a sheet-like or thin-film form, it can be produced by molding the flarenol-introduced polyurethane elastomer into a film-like, sheet-like or thin-film form. That is, the polyurethane elastomer piezoelectric element composed of the furlenol-introduced polyurethane elastomer of the present invention (sometimes referred to as "flarenol-introduced polyurethane elastomer piezoelectric element") is in the form of a film, a sheet (particularly a film), or a thin film. It may be in the form.

【0032】

Specifically, when the flarenol-introduced polyurethane elastomer is molded into a film, sheet or thin film (for example, about 0.01 to 1 mm in thickness), when a mold release agent is used in this molding method, After molding, the release agent can be removed. Removal of the mold release agent of the molded polyurethane elastomer is sufficient by normal wet cleaning, but for example, as surface modification for electrode addition, ion ozone such as plasma treatment by glow discharge or corona discharge treatment -It is preferable to remove impurities such as a mold release agent by 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 flarenol-introduced polyurethane elastomer. The electrode material includes, for example, metal compounds such as gold, platinum, aluminum, metallic indium, indium oxide, stannous oxide, ITO, silver and other metals and alloys, as well as conductive resins such as polyaniline and elastomer rubber. Carbon or the like can be used. Further, a conductive resin or a 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 vapor deposition method, screen printing, an ion beam assist method, an ionization vapor deposition method and the like can be adopted.

【0034】

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

【0035】

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

【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, screen printing method) can be adopted. .. 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 full-lenol-introduced polyurethane elastomer, any method other than printing can be used as long as various patterns can be formed. Any method (for example, a vapor deposition method) can be adopted.

【0037】

Since the pressure-sensitive conductive layer 22 for the row electrode and the pressure-sensitive conductive layer 32 for the column electrode can be formed by printing the flarenol-introduced polyurethane elastomer in this way, it is not only flat but also three-dimensional. It can also be formed on a curved surface that is bent to the surface. Therefore, the pressure-sensitive sensor and the contact sensor of the present invention can be formed not only in a linear or planar shape but also in a shape having a three-dimensionally curved curved surface shape. Therefore, the pressure-sensitive sensor and the sensor of the contact sensor of the present invention can be used, for example, by being attached to a portion of a robot arm (arm) having a three-dimensionally bent curved surface shape.

【0038】

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

【0039】

[Effect of the invention]

According to the polyurethane elastomer piezoelectric element of the present invention, even if the 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]

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

【0041】

(Preparation example 1 of fullerene) 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 sulfonate reaction, and further, distilled water is added and the temperature is 85 ° C for 3 days. Fullerenol was prepared by stirring and performing a hydrolysis reaction.

【0042】

(Example 1) Poly-3methyl-1,5-pentaneadipate polyol (PMPA, manufactured by Kuraray Co., Ltd., trade name "Kurapol P3010") having an average molecular weight of 2,945 in 100 parts by weight of paraphenylene diisocyanate (PPDI, Dupont) 10.8 parts by weight was added, and the mixture was reacted at 85 ° C. for 2 hours under a nitrogen stream to obtain a urethane prepolymer having a terminal isocyanate group.

【0043】

To the urethane prepolymer, flarenol obtained in Preparation Example 1 of the flarenol is added at a ratio of 0.25% by weight based on the total amount of the urethane prepolymer (solid content), mixed, and preheated at 110 ° C. A flarenol-introduced polyurethane elastomer in which flarenol was introduced was prepared by pouring it into a mold having a thickness of 0.2 mm and allowing it to stand in an oven at 110 ° C. for 24 hours to carry out a curing reaction.

【0044】

The flarenol-introduced polyurethane elastomer was molded into a film having a thickness of 200 μm by a casting method to prepare a film-shaped flarenol-introduced polyurethane elastomer to prepare a fulllarenol-introduced polyurethane elastomer piezoelectric element.

【0045】

(Evaluation of Piezoelectric Characteristics) The furlenol-introduced polyurethane elastomer piezoelectric element produced in Example 1 is pressurized, the induced voltage generated when the pressure is applied is measured, the piezoelectricity at the time of pressurization is evaluated, and the measurement result is obtained. Is shown in Fig. 1.

【0046】

Specifically, a weight (weight 0 to 3 kg) is placed on a fullerenol-introduced polyurethane elastomer piezoelectric element (film) and pressurized, and the voltage (mV) generated on both surfaces of the piezoelectric element with respect to the load (g) during pressurization. Is measured, and the voltage (mV) generated on both surfaces of the piezoelectric element when the pressurization is released (released) is measured to pressurize the load (g) during pressurization or pressurize when pressurization is released. Figure 1 shows a graph of the relationship between the applied load (g) and the voltage (mV) generated on both surfaces of the piezoelectric element.

【0047】

As shown in FIG. 1, it was confirmed that when the film-like furlenol-introduced polyurethane elastomer according to Example 1 was pressurized, 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 pressurization was released.

【0048】

Further, the furalenol-introduced polyurethane elastomer piezoelectric element produced in Example 1 was stretched, the induced voltage generated when the stretch was stretched, the piezoelectricity at the time of stretching was evaluated, and the measurement result is shown in FIG. ..

【0049】

Specifically, the fullerenol-introduced polyurethane elastomer piezoelectric element (film) is stretched 1.5 times, and the time (second) change of the voltage (mV) generated on both surfaces of the piezoelectric element during stretching is measured, and the result is shown in the figure. Shown in 2.

【0050】

From FIG. 2, it was confirmed that even by stretching, 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.

【0051】

Therefore, by amplifying the voltage generated by pressurization and stretching and applying appropriate signal processing, the furalenol-introduced polyurethane elastomer piezoelectric element of the example can be subjected to various pressure-sensitive properties having flexibility and flexibility peculiar to polyurethane elastomer. It can be applied as a sensor or a 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 sulfonate reaction, and further, distilled water is added and stirred at 85 ° C for 3 days. By carrying out a hydrolysis reaction, three types of fullerenes introduced into the molecule having different numbers of hydroxyl groups were prepared.

【0053】

Using the three types of flarenols having different numbers of hydroxyl groups, flarenol-introduced polyurethane elastomers into which flarenol was introduced were prepared in the same manner as in Example 1, and further, the flarenol-introduced polyurethane elastomer was used in Examples. In the same manner as in 1, a film-shaped furlenol-introduced polyurethane elastomer piezoelectric element was produced.

【0054】

The piezoelectricity due to the difference in the number of hydroxyl groups contained in flarenol was evaluated by measuring the induced voltage generated when a constant (200 g) pressurization was applied to this furlenol-introduced polyurethane elastomer piezoelectric element (film form). The measurement results are shown in Fig. 3. Specifically, a weight (weight 200 g) is placed on a fullerenol-introduced polyurethane elastomer piezoelectric element (film) and pressurized, and the voltage (mV) generated on both surfaces of the piezoelectric element during the pressurization (load 200 g) is measured. FIG. 3 shows a graph of the relationship between the number of hydroxyl groups contained in flarenol and the voltage (mV) generated on both surfaces of the piezoelectric element by pressurization (200 g). In the graph shown in FIG. 3, the horizontal axis is shown as the transmittance (% T), but the one with the lower transmittance corresponds to the furalenol-introduced polyurethane elastomer piezoelectric element due to the one having a larger number of hydroxyl groups of the furalenol. On the contrary, the one with higher transmittance corresponds to the furalenol-introduced polyurethane elastomer piezoelectric element having a smaller number of hydroxyl groups of flarenol.

【0055】

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

[Simple explanation of drawings]

[Figure 1]

Relationship between the load (g) at the time of pressurization or the load (g) pressurized at the time of releasing the pressurization when the piezoelectric element according to the embodiment is pressurized and the voltage (mV) generated on both surfaces of the piezoelectric element. It is a figure which shows the graph.

[Figure 2]

It is a figure which shows the graph of the time (second) change of the voltage (mV) generated on both surfaces of a piezoelectric element when the piezoelectric element which concerns on an Example is stretched.

[Fig. 3]

It is a figure which shows the graph of the relationship between the number of hydroxyl groups contained in flarenol when the piezoelectric element which concerns on an Example is pressurized, and the voltage (mV) generated on both surfaces of a piezoelectric element by pressurization (200 g). ..

[Fig. 4]

It is the schematic sectional drawing which shows an example of the pressure-sensitive sensor of this invention partially.

[Explanation of symbols]

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