JP2016153729A - Deformation amount measuring structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deformation amount measuring structure capable of repeatedly and accurately measuring deformation amounts of a measuring object when the same is extended or bent without interfering movement of the measuring object.SOLUTION: A deformation amount measuring structure comprises a base material 10 subject to extensional deformation or bending deformation and a sensor element 11. The sensor element 11: has a dielectric layer 12 which is arranged on a surface of the base material 10 and includes elastomer, a pair of electrode layers 13a and 13b which are arranged with the dielectric layer 12 placed in between and include the elastomer and an electrical conducting material, and a protection layer 14a or 14b which is arranged on a surface of at least one of the pair of electrode layers 13a and 13b and includes the elastomer; and extends or contracts according to deformation of the base material 10. In the deformation amount measuring structure, permanent tensile deformation of at least either the dielectric layer 12 or the protection layer 14a or 14b is not more than 10%; and a tensile or bending deformation amount of the base material 10 is measured on the basis of a change in capacitance output by the sensor element 11.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a deformation amount measuring structure that measures a deformation amount of a base material that undergoes deformation or bending deformation from a change in capacitance.

  Development of flexible sensors using elastomer as a means for detecting load distribution, deformation of members, and the like is in progress. For example, as described in Patent Documents 1 to 4, a capacitive sensor can be configured by arranging electrode layers so as to sandwich an elastomeric dielectric layer. In the capacitance type sensor, the capacitance increases as the thickness of the dielectric layer, that is, the distance between the electrode layers decreases due to compression or expansion. Further, as the area of the electrode layer increases, the capacitance increases. Therefore, according to the capacitance type sensor, it is possible to detect the amount of deformation such as the load applied to the measurement object and the amount of elongation of the measurement object based on the change in capacitance.

  In a capacitive sensor with an elastomeric dielectric layer, a flexible conductive material is used for the electrode layer so that the dielectric layer and the electrode layer can be deformed integrally following the deformation of the measurement object. Has been. For example, in the capacitance-type sensor described in Patent Document 4, in order to measure the amount of stretching strain of a soft object such as a cushion, carbon nanotubes are used as the material of the electrode layer, and the thickness of the electrode layer By reducing the thickness, the followability to the dielectric layer is improved.

JP 2011-2256 A JP 2009-20006 A JP 2010-43881 A JP 2014-81355 A

  Up to now, the materials of the dielectric layer and the electrode layer have been studied and the flexibility of the sensor has been improved so that the deformation of the measurement object can be followed without hindering the movement of the measurement object. As the dielectric layer, a flexible elastomer such as urethane rubber is used. However, a flexible elastomer is easy to sag after repeated expansion and contraction. That is, it becomes difficult for the dielectric layer to return to its original shape while repeating expansion and contraction. In a capacitance type sensor, if the relationship between the amount of elongation of the dielectric layer and the change in capacitance is prepared in advance, the amount of elongation of the measurement object can be measured from the output change in capacitance. . However, when the dielectric layer falls, the manner in which the dielectric layer expands and contracts changes, so that the preset capacitance value and output value differ depending on the deformation of the measurement object. For this reason, the amount of elongation of the measurement object cannot be accurately measured. In addition, by preparing a stress-strain (elongation) diagram in advance, it is possible to measure the stress generated in the measurement object based on the elongation calculated from the change in capacitance. However, if the dielectric layer is sunk, it is impossible to accurately measure the amount of elongation, and therefore stress cannot be measured accurately.

  In order to improve the sag resistance of the dielectric layer, for example, it is conceivable to increase the crosslink density of the elastomer. Increasing the crosslink density of the elastomer increases the elastic modulus, which is advantageous for sag resistance. However, when the elastic modulus of the dielectric layer increases, the followability to the deformation of the measurement object decreases. For this reason, it is difficult to achieve a level that satisfies both flexibility and sag resistance by simply changing the elastomer type of the dielectric layer or adjusting the cross-linking density of the elastomer.

  On the other hand, in order to improve the sensitivity of the sensor (S / N ratio (Signal-Noise Ratio)), it is desirable to increase the relative dielectric constant of the dielectric layer. For example, an elastomer having a large relative dielectric constant can be used, or dielectric particles such as barium titanate particles can be blended in the elastomer to increase the relative dielectric constant of the dielectric layer. However, as a result of investigation by the present inventor, it has been found that when dielectric particles are blended in the dielectric layer, the sag resistance is further lowered due to peeling of the dielectric particles and the elastomer. Therefore, it is difficult to increase the dielectric constant of the dielectric layer while ensuring sag resistance.

  The present invention has been made in view of such a situation, and the deformation amount measurement that can repeatedly and accurately measure the deformation amount due to elongation or bending of the measurement object without hindering the movement of the measurement object. It is an object to provide a structure.

  (1) A first deformation amount measuring structure of the present invention includes a base material that is stretched or bent, a dielectric layer that is disposed on the surface of the base material, and that includes an elastomer, and is sandwiched between the dielectric layers. A sensor element that includes a pair of electrode layers including an elastomer and a conductive material; and a protective layer including an elastomer that is disposed on at least one surface of the pair of electrode layers, and that expands and contracts following the deformation of the base material. The tensile permanent strain of at least one of the dielectric layer and the protective layer is 10% or less, and the substrate is deformed by stretching or bending based on a change in capacitance output from the sensor element. It is characterized by measuring quantity.

  The base material constituting the first deformation measurement structure of the present invention is a measurement object. The base material is not particularly limited as long as it undergoes elongation deformation or bending deformation. Examples of the material for the substrate include resin, elastomer, and cloth. The cloth includes woven fabrics, knitted fabrics, and nonwoven fabrics of natural fibers and synthetic fibers. As a base material, what processed into the state which can be expanded-contracted, such as clothes and a supporter, and what laminated | stacked these, etc. are mentioned, for example.

  The “deformation amount due to elongation or bending of the base material” measured by the first deformation amount measuring structure of the present invention includes the elongation amount of the base material, the bending angle, the stress of the base material, etc. The same applies to the second and third deformation measuring structures of the invention).

  The sensor element constituting the first deformation measurement structure of the present invention has a protective layer. The protective layer is disposed on the surface opposite to the dielectric layer in one or both of the pair of electrode layers. By disposing the protective layer, it is possible to suppress the destruction of the sensor element due to external mechanical stress, and to obtain an effect of making it difficult to transmit the external temperature change to the dielectric layer.

  In the sensor element, the tensile set of at least one of the dielectric layer and the protective layer is 10% or less. As the tensile permanent strain in this specification, a constant elongation tensile permanent strain test using a strip-shaped test piece defined in JIS K 6273: 2006 is given an elongation of 50%, a test temperature of 50 ° C., a test time of 20 The value measured under the condition of time is adopted.

  The dielectric layer and the protective layer are flexible because they contain an elastomer, but have excellent sag resistance when the tensile permanent strain is 10% or less. For example, when the tensile permanent strain of both the dielectric layer and the protective layer is 10% or less, the sag resistance of the entire sensor element is improved. Even if sag occurs in the electrode layer, the electrode layer can be pulled back to the original shape by being pulled by the dielectric layer and the protective layer. Thereby, a dielectric layer, an electrode, and a protective layer are expanded and contracted integrally. Therefore, the sensor element can output a capacitance according to the deformation of the base material even if the sensor element is repeatedly expanded and contracted.

  On the other hand, the tensile set of only the dielectric layer may be 10% or less. In this case, the dielectric layer serves to help the protective layer and the electrode layer return to their original shape. That is, even if sag occurs in the protective layer or the electrode layer, the protective layer or the electrode layer can be pulled back to the original shape by being pulled by the dielectric layer. Thereby, the protective layer and the electrode layer expand and contract together with the dielectric layer. Therefore, the sensor element can output a capacitance according to the deformation of the base material even if the sensor element is repeatedly expanded and contracted.

  On the other hand, the tensile permanent strain of only the protective layer may be 10% or less. In this case, the protective layer serves to help the dielectric layer and the electrode layer return to their original shape. That is, even if a sag occurs in the dielectric layer or the electrode layer, the dielectric layer or the electrode layer can be returned to the original shape by being pulled by the protective layer. As a result, the dielectric layer and the electrode layer expand and contract integrally with the protective layer. Therefore, the sensor element can output a capacitance according to the deformation of the base material even if the sensor element is repeatedly expanded and contracted.

  As described above, in the first deformation amount measuring structure of the present invention, (a) the sag resistance of the dielectric layer and the protective layer is improved, or (b) the protection, while ensuring the flexibility of the sensor element. The sag resistance of the entire sensor element is improved by supplementing the sag resistance of the layer with a dielectric layer, or (c) supplementing the sag resistance of the dielectric layer with a protective layer. Therefore, according to the first deformation amount measurement structure of the present invention, the deformation amount due to the elongation or bending of the base material can be repeatedly and accurately measured without hindering the movement of the base material.

  In addition, when the tensile permanent strain of only the protective layer is 10% or less, the protective layer can secure the sag resistance of the sensor element, and thus the dielectric layer is given characteristics different from the sag resistance. be able to. For example, the dielectric layer can be mixed with dielectric particles to increase the dielectric constant of the dielectric layer. Thus, by separating the functions of the protective layer and the dielectric layer, not only the durability but also the performance of the sensor element can be improved.

(2) Preferably, in the configuration of (1) above, the elastic modulus and the cross-sectional area of each of the dielectric layer, the electrode layer, and the protective layer in the sensor element are represented by the following formulas (I) and (II): , (III) may be satisfied.
(I) When the tensile set of only the protective layer of the dielectric layer and the protective layer is 10% or less (EeSe + EySy) <EcSc (I)
(Ii) When the tensile set of only the dielectric layer of the dielectric layer and the protective layer is 10% or less (EeSe + EcSc) <EySy (II)
(Iii) When the tensile set of the protective layer and the dielectric layer is 10% or less EeSe <(EcSc + EySy) (III)
[Ee: Elastic modulus of electrode layer, Se: Cross sectional area of electrode layer, Ey: Elastic modulus of dielectric layer, Sy: Cross sectional area of dielectric layer, Ec: Elastic modulus of protective layer, Sc: Cross sectional area of protective layer]
The cross-sectional areas of the electrode layer, the dielectric layer, and the protective layer are cross-sectional areas of laminated portions when the sensor elements are cut in the laminating direction in a natural state where the sensor elements are not deformed. The cross-sectional area of the electrode layer is the sum of the cross-sectional areas of the two electrode layers sandwiching the dielectric layer. When two protective layers are arranged, the cross-sectional area of the protective layer is the sum of the cross-sectional areas of the two protective layers. In addition, when the elastic modulus of two electrode layers differs, elastic modulus x cross-sectional area is calculated for each layer, and the sum thereof is used. The same applies to the protective layer. For example, when the elastic modulus of one electrode layer is Ee ₁ , the cross-sectional area is Se ₁ , the elastic modulus of the other electrode layer is Ee ₂ , and the cross-sectional area is Se ₂ , EeSe in the formula (I) is (Ee ₁ Se ₁ + Ee ₂ Se ₂ ).

  As the elastic modulus, a value calculated from a stress-elongation curve obtained by conducting a tensile test specified in JIS K 7127: 1999 is adopted. Specimen type 2 shall be used for the specimen.

  The sag resistance of the sensor element is greatly influenced by the sag resistance of the layer having a large spring constant. The spring constant in the expansion / contraction direction of the dielectric layer, the electrode layer, and the protective layer depends on the elastic modulus of the material constituting each layer and the cross-sectional area in the stacking direction (corresponding to the direction orthogonal to the expansion / contraction direction) of each layer. According to this configuration, in any of the cases (i) to (iii), the tensile permanent strain of the layer having a large spring constant is 10% or less. Thereby, the sensor element which is excellent in sag resistance can be constituted.

  (3) Preferably, in the configuration of the above (1) or (2), the elastomer of at least one of the dielectric layer and the protective layer penetrates the cyclic molecule and the opening of the cyclic molecule into the cyclic molecule. A crosslinked structure via a ring-moving molecule having a linear molecule to be included, and at least a part of the polymer chain of the elastomer is crosslinked with the cyclic molecule, and the cyclic molecule is the linear molecule The cross-linking point may be moved by moving along the molecule.

  In this configuration, as long as the elastomer has a cross-linked structure via a ring-moving molecule, its own polymer chain may or may not be cross-linked. The ring-moving molecule has a cyclic molecule and a linear molecule. Cyclic molecules can move along linear molecules. At least part of the polymer chain of the elastomer is cross-linked with the cyclic molecule. For this reason, a crosslinking point also moves with the movement of a cyclic molecule. In a normal cross-linked structure not involving a ring-moving molecule, the cross-linking point is fixed. For this reason, when expansion and contraction is repeated, stress concentrates on the cross-linking point, and the cross-linked chain or polymer chain is likely to be cut and sag occurs. On the other hand, in an elastomer in which a cross-linking point moves, stress is not concentrated on the cross-linking point even if the expansion and contraction is repeated, and is dispersed throughout the elastomer. Therefore, by using the elastomer, it is possible to realize a dielectric layer and a protective layer having excellent sag resistance while maintaining the flexibility (low elasticity) of the elastomer itself.

  For example, when an elastomer having a cross-linked structure via a ring-moving molecule is used as the dielectric layer elastomer, the dielectric layer may be blended with inorganic particles, organic particles, polymers, plasticizers, etc. having a high relative dielectric constant. The sag resistance is difficult to decrease. Since a component having a high relative dielectric constant can be blended to increase the relative dielectric constant of the dielectric layer, not only the durability but also the performance of the sensor element can be improved.

  (4) The second deformation amount measuring structure of the present invention is a base material that is stretched or bent, a dielectric layer that is disposed on the surface of the base material and includes an elastomer, and is sandwiched between the dielectric layers. A pair of electrode layers including an elastomer and a conductive material, and a sensor element that expands and contracts following the deformation of the base material. The elastomer of the dielectric layer includes a cyclic molecule, and A linear molecule penetrating through the opening and being included in the cyclic molecule, and having a cross-linked structure via a ring-moving molecule, and at least a part of the polymer chain of the elastomer is cross-linked with the cyclic molecule. The cyclic point moves along the linear molecule, and the cross-linking point moves. Based on the change in the capacitance output from the sensor element, the base material is stretched or bent. The deformation amount is measured.

  The base material constituting the second deformation amount measurement structure of the present invention is a measurement object. The base material is the same as the base material in the first deformation amount measurement structure of the present invention, and is not particularly limited as long as it undergoes elongation deformation or bending deformation.

  As the dielectric layer of the sensor element, an elastomer having a crosslinked structure via a ring-moving molecule is used. As long as the elastomer has a cross-linked structure via a ring-moving molecule, its own polymer chain may or may not be cross-linked. As described above, when an elastomer having a crosslinked structure via a ring-moving molecule is used, the sag resistance can be improved while maintaining the flexibility of the dielectric layer. By providing the sensor element with a dielectric layer having excellent sag resistance, even if sag occurs in the protective layer or the electrode layer, the protective layer or the electrode layer can be pulled back to the original shape by the dielectric layer. . Thereby, the protective layer and the electrode layer expand and contract together with the dielectric layer. Therefore, the sensor element can output a capacitance according to the deformation of the base material even if the sensor element is repeatedly expanded and contracted. Therefore, according to the second deformation amount measurement structure of the present invention, the deformation amount due to the elongation or bending of the base material can be repeatedly measured with high accuracy without hindering the movement of the base material that is the measurement object.

  In addition, as described in the configuration (3) above, even if the dielectric layer of this configuration is blended with inorganic particles, organic particles, polymers, plasticizers or the like having a high relative dielectric constant, the sag resistance is reduced. Hateful. Since a component having a high relative dielectric constant can be blended to increase the relative dielectric constant of the dielectric layer, not only the durability but also the performance of the sensor element can be improved.

  (5) The third deformation amount measuring structure of the present invention is a base material that is stretched or bent, a dielectric layer that is disposed on the surface of the base material and includes an elastomer, and is sandwiched between the dielectric layers. A pair of electrode layers including an elastomer and a conductive material, and a sensor element that expands and contracts following the deformation of the base material, the tensile permanent strain of the base material being 10% or less, When the material and the sensor element are stretched in the same direction in the plane direction, the spring constant of the base material is larger than the spring constant of the sensor element, and the capacitance output from the sensor element changes. Based on this, the amount of deformation due to elongation or bending of the substrate is measured.

  The base material constituting the third deformation measurement structure of the present invention is a measurement object. The substrate is limited in that the permanent set is 10% or less and the spring constant in the plane direction is larger than the spring constant of the sensor element. Same as wood. In the third deformation amount measuring structure of the present invention, the “plane direction” is a direction orthogonal to the stacking direction of the base material and the sensor element. In the third deformation amount measuring structure of the present invention, the “spring constant” is an inclination of 0 to 10% elongation in each load-displacement characteristic of the base material and the sensor element.

  In the third deformation amount measuring structure of the present invention, the tensile permanent strain of the substrate is 10% or less, and the spring constant in the surface direction of the substrate is larger than the spring constant in the surface direction of the sensor element. For this reason, a base material is harder to sag than a sensor element, and plays a role which helps that a sensor element returns to an original shape. Therefore, even if a sag occurs in the dielectric layer or the like of the sensor element, the sensor element can be pulled to the base material and return to its original shape. Thereby, the sensor element expands and contracts following the deformation of the base material. Therefore, the sensor element can output a capacitance according to the deformation of the base material even if the sensor element is repeatedly expanded and contracted.

  Thus, in the third deformation measurement structure of the present invention, the base material that is the object to be measured is limited to one having a tensile permanent strain of 10% or less and a spring constant larger than that of the sensor element. By doing so, the problem of sag resistance of the sensor element is solved. According to the third deformation amount measurement structure of the present invention, the deformation amount due to the elongation or bending of the base material can be repeatedly and accurately measured without hindering the movement of the base material. Of course, also in the third deformation amount measuring structure of the present invention, the form described in the above (1) to (4), that is, the form in which the tensile set of the dielectric layer is 10% or less, as the dielectric layer elastomer The form using what has a crosslinked structure via a ring-moving molecule is employable.

  (6) Preferably, in the configuration of (5), the sensor element further includes a protective layer that is disposed on at least one surface of the pair of electrode layers and includes an elastomer.

  The protective layer is disposed on the surface opposite to the dielectric layer in one or both of the pair of electrode layers. As described above, when the protective layer is disposed, it is possible to suppress the destruction of the sensor element due to the mechanical stress from the outside, and to obtain an effect of making it difficult to transmit the external temperature change to the dielectric layer. Further, when the tensile permanent strain of the protective layer is 10% or less, the sag resistance of the sensor element is improved.

  (7) Preferably, in any one of the configurations (1) to (6), the dielectric layer has a relative dielectric constant of 5 or more.

  According to this configuration, the capacitance value output from the sensor element is increased, and the sensitivity (S / N ratio) of the sensor element is improved.

  (8) Preferably, in any one of the configurations (1) to (7), the dielectric layer includes a dielectric particle.

  The dielectric particles include inorganic particles and organic particles having a large relative dielectric constant. The relative dielectric constant of the dielectric particles is preferably 10 or more, more preferably 200 or more. According to this configuration, the dielectric constant of the dielectric layer can be increased. Thereby, the value of the electrostatic capacitance with respect to the deformation of the base material is increased, and the sensitivity (S / N ratio) of the sensor element can be improved.

It is a top view of the deformation measurement structure of the first embodiment. It is II-II sectional drawing of FIG. It is a top view of the deformation measurement structure of the second embodiment. It is IV-IV sectional drawing of FIG. It is a top view of the deformation measuring structure of a third embodiment. It is VI-VI sectional drawing of FIG.

  Hereinafter, embodiments of the deformation measuring structure of the present invention will be described.

<First embodiment>
Embodiment of the 1st deformation measuring structure of this invention is shown. First, the configuration of the deformation measurement structure of the present embodiment will be described. FIG. 1 shows a top view of the deformation measuring structure. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. The II-II cross section in FIG. 1 is a cross section in the stacking direction orthogonal to the expansion and contraction direction of the sensor element. In FIG. 1, the electrode layer disposed below the uppermost protective layer is shown in a transparent manner. In FIG. 1, the front-rear and left-right directions correspond to the surface directions of the base material and the sensor element. In FIG. 2, the vertical direction corresponds to the stacking direction. As shown in FIGS. 1 and 2, the deformation amount measurement structure 1 includes a base material 10 and a sensor element 11.

  The base material 10 is made of a polyester net (manufactured by Mutual Chemical Glass Co., Ltd.). The base material 10 extends and deforms in the left-right direction, or bends and deforms into a C shape that opens downward. The sensor element 11 is disposed on the upper surface of the base material 10. The sensor element 11 includes a dielectric layer 12, a pair of electrode layers 13a and 13b, and a pair of protective layers 14a and 14b.

The dielectric layer 12 has a rectangular shape extending in the left-right direction. The length (width) of the dielectric layer 12 in the front-rear direction is 10 mm, the length in the left-right direction is 50 mm, and the thickness is 300 μm. The dielectric layer 12 includes urethane rubber and barium titanate particles. Urethane rubber is included in the concept of elastomer in the present invention. Barium titanate particles are included in the concept of dielectric particles in the present invention. The relative dielectric constant of the dielectric layer 12 is 12. The elastic modulus (Ey) of the dielectric layer 12 is 3 MPa, and the cross-sectional area (Sy) of the II-II cross section is 3 × 10 ⁻⁶ m ² .

Each of the pair of electrode layers 13a and 13b has a rectangular shape extending in the left-right direction. The electrode layer 13 a is disposed on the upper surface of the dielectric layer 12. The electrode layer 13 b is disposed on the lower surface of the dielectric layer 12. The electrode layers 13a and 13b have the same width and length in the left-right direction as the dielectric layer 12. The electrode layers 13a and 13b have a thickness of 50 μm. The electrode layers 13a and 13b contain acrylic rubber and carbon black. The elastic modulus (Ee) of the electrode layers 13a and 13b is 1 MPa, and the sectional area (Se) of the II-II section is 1 × 10 ⁻⁶ m ² in total. A wiring (not shown) is connected to the electrode layers 13a and 13b. The electrode layers 13a and 13b are connected to a control device (not shown) via wiring.

Each of the pair of protective layers 14a, 14b has a rectangular shape extending in the left-right direction. The protective layer 14a is disposed on the upper surface of the electrode layer 13a. The protective layer 14a covers the dielectric layer 12 and the electrode layers 13a and 13b. The protective layer 14b is disposed on the lower surface of the electrode layer 13b. The protective layers 14a and 14b are laminated on the dielectric layer 12 and the electrode layers 13a and 13b in a region having a width of 10 mm and a length in the left-right direction of 50 mm. The thickness of the protective layers 14a and 14b is 200 μm. The protective layers 14a and 14b contain urethane rubber and polyrotaxane. Urethane rubber has a crosslinked structure via a polyrotaxane. The cyclic molecule of polyrotaxane is α-cyclodextrin, the linear molecule is polyethylene glycol, and the blocking group is an adamantane group. The elastic modulus (Ec) of each of the protective layers 14a and 14b is 4 MPa, and the sectional area (Sc) of the II-II cross section is 4 × 10 ⁻⁶ m ² in total. The tensile permanent strain of the protective layers 14a and 14b is 1%.

  Next, the movement of the deformation amount measurement structure according to this embodiment will be described. A voltage is applied to the pair of electrode layers 13a and 13b from the control device. The sensor element 11 outputs a natural capacitance before the base material 10 is deformed. When the base material 10 extends in the left-right direction, the sensor element 11 also extends with the base material 10. At this time, the thickness of the dielectric layer 12 is reduced, and the areas of the electrode layers 13a and 13b are increased. Thereby, the electrostatic capacitance between electrode layers 13a and 13b becomes large. The control device stores in advance a map indicating the relationship between the change in capacitance and the amount of elongation of the sensor element 11, and a map indicating the relationship between the amount of elongation of the sensor element 11 and the stress. When the sensor element 11 outputs the electrostatic capacity when the base material 10 is extended, the extension amount of the base material 10 is calculated from the change amount of the electrostatic capacity before and after the extension. The stress is calculated from the elongation amount of the base material 10.

  Next, the effect of the deformation amount measurement structure of this embodiment will be described. In the deformation amount measuring structure 1, protective layers 14a and 14b are disposed so as to cover the dielectric layer 12 and the electrode layers 13a and 13b. Therefore, destruction of the sensor element 11 due to external mechanical stress is suppressed. In addition, external temperature changes are not easily transmitted to the dielectric layer 12. The protective layers 14a and 14b are made of urethane rubber having a crosslinked structure via a polyrotaxane. In the urethane rubber, since the cross-linking point is not fixed and slides at the time of deformation, stress is hardly concentrated at the cross-linking point even if the expansion and contraction is repeated. Moreover, the tensile permanent strain of the protective layers 14a and 14b is 10% or less. For this reason, the protective layers 14a and 14b are flexible (low elasticity) and excellent in sag resistance.

  Of the members constituting the sensor element 11, only the protective layers 14a and 14b have a tensile permanent strain of 10% or less. Here, the relationship between the elastic modulus and the cross-sectional area of each of the dielectric layer 12, the electrode layers 13a and 13b, and the protective layers 14a and 14b satisfies (EeSe + EySy) <EcSc in the formula (I). That is, in the sensor element 11, the protective layers 14a and 14b, which are considered to have the largest spring constant, are excellent in sag resistance. Therefore, even if the dielectric layer 12 and the electrodes 13a and 13b are sag, the dielectric layer 12 and the electrodes 13a and 13b can be pulled by the protective layers 14a and 14b to return to the original shape. For this reason, even if the sensor element 11 repeats expansion and contraction, the sensor element 11 can output a capacitance according to the deformation of the substrate 10. Therefore, according to the deformation amount measurement structure 1, the elongation amount and stress of the base material 10 can be repeatedly measured with high accuracy without hindering the movement of the base material 10.

  The urethane rubber contained in the dielectric layer 12 and the protective layers 14a and 14b has adhesiveness. For this reason, the interlayer adhesion of the dielectric layer 12, the electrode layers 13a and 13b, and the protective layers 14a and 14b is high. Moreover, the adhesiveness between the protective layer 14b and the base material 10 is also high. Therefore, even if the expansion and contraction is repeated, the constituent members of the sensor element 11 and the sensor element 11 and the base material 10 are hardly separated. Also in this point, the sensor element 21 is excellent in durability.

  The dielectric layer 12 contains barium titanate particles. For this reason, the dielectric constant of the dielectric layer 12 is large. In the deformation amount measuring structure 1, functional separation is performed such that the sag resistance is improved by the protective layers 14 a and 14 b and the relative dielectric constant is increased by the dielectric layer 12. Therefore, in the deformation amount measuring structure 1, not only the durability but also the sensitivity (S / N ratio) of the sensor element 11 is high.

<Second embodiment>
2 shows an embodiment of a second deformation measurement structure of the present invention. First, the configuration of the deformation measurement structure of the present embodiment will be described. FIG. 3 shows a top view of the deformation amount measuring structure. FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3 is a cross section in the stacking direction orthogonal to the expansion and contraction direction of the sensor element. In FIG. 3, the front-rear and left-right directions correspond to the surface directions of the base material and the sensor element. In FIG. 4, the vertical direction corresponds to the stacking direction. As shown in FIGS. 3 and 4, the deformation amount measurement structure 2 includes a base material 20 and a sensor element 21.

  The substrate 20 is made of a polyester net (manufactured by Mutual Chemical Glass Co., Ltd.). The base material 20 extends and deforms in the left-right direction or bends and deforms into a C-shape that opens downward. The sensor element 21 is disposed on the upper surface of the base material 20. The sensor element 21 includes a dielectric layer 22 and a pair of electrode layers 23a and 23b.

  The dielectric layer 22 has a rectangular shape extending in the left-right direction. The length (width) of the dielectric layer 22 in the front-rear direction is 10 mm, the length in the left-right direction is 50 mm, and the thickness is 300 μm. The dielectric layer 22 includes urethane rubber, polyrotaxane, and barium titanate particles. Urethane rubber has a crosslinked structure via a polyrotaxane. The cyclic molecule of polyrotaxane is α-cyclodextrin, the linear molecule is polyethylene glycol, and the blocking group is an adamantane group. The relative dielectric constant of the dielectric layer 22 is 12.

  Each of the pair of electrode layers 23a and 23b has a rectangular shape extending in the left-right direction. The electrode layer 23 a is disposed on the upper surface of the dielectric layer 22. The electrode layer 23 b is disposed on the lower surface of the dielectric layer 22. The lengths of the electrode layers 23 a and 23 b in the front-rear direction and the left-right direction are the same as those of the dielectric layer 22. The electrode layers 23a and 23b have a thickness of 50 μm. The electrode layers 23a and 23b contain acrylic rubber and carbon black. A wiring (not shown) is connected to the electrode layers 23a and 23b. The electrode layers 23a and 23b are connected to a control device (not shown) via wiring.

  Next, the movement of the deformation amount measurement structure according to this embodiment will be described. A voltage is applied from the control device to the pair of electrode layers 23a and 23b. The sensor element 21 outputs a natural capacitance before the base material 20 is deformed. When the base material 20 is bent and deformed into a C shape that opens downward, the sensor element 21 is also bent and deformed together with the base material 20. At this time, the thickness of the dielectric layer 22 is reduced, and the area of the electrode layer 23a is increased. Thereby, the electrostatic capacitance between electrode layers 23a and 23b becomes large. The control device stores in advance a map showing the relationship between the change in capacitance and the bending angle of the sensor element 21. When the capacitance at the time of bending deformation of the substrate 20 is output by the sensor element 21, the bending angle of the substrate 20 is calculated from the amount of change in capacitance before and after the deformation.

  Next, the effect of the deformation amount measurement structure of this embodiment will be described. In the deformation measurement structure 2, urethane rubber having a crosslinked structure via polyrotaxane is used as the material of the dielectric layer 22. In the urethane rubber, since the cross-linking point is not fixed and slides at the time of deformation, stress is hardly concentrated at the cross-linking point even if the expansion and contraction is repeated. Therefore, the dielectric layer 22 is flexible (low elasticity) and excellent in sag resistance. Therefore, the sensor element 21 can output a capacitance according to the deformation of the base material 20 even if the expansion and contraction is repeated. The urethane rubber has adhesiveness. For this reason, the adhesiveness of the dielectric layer 22 and electrode layer 23a, 23b is high. Therefore, even if the expansion and contraction is repeated, the dielectric layer 22 and the electrode layers 23a and 23b are hardly peeled off. Also in this point, the sensor element 21 is excellent in durability. Therefore, according to the deformation amount measurement structure 2, the elongation amount and stress of the base material 20 can be repeatedly measured with high accuracy without hindering the movement of the base material 20.

  The dielectric layer 22 contains barium titanate particles. For this reason, the dielectric constant of the dielectric layer 22 is large. Therefore, in the deformation measuring structure 2, not only the durability but also the sensitivity (S / N ratio) of the sensor element 21 is high.

<Third embodiment>
3 shows an embodiment of a third deformation measurement structure of the present invention. First, the configuration of the deformation measurement structure of the present embodiment will be described. FIG. 5 shows a top view of the deformation amount measuring structure. FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. The VI-VI cross section of FIG. 5 is a cross section in the stacking direction orthogonal to the expansion and contraction direction of the sensor element. In FIG. 5, the electrode layer disposed below the protective layer is shown in a transparent manner. In FIG. 5, the front-rear and left-right directions correspond to the surface directions of the base material and the sensor element. In FIG. 6, the vertical direction corresponds to the stacking direction. As shown in FIGS. 5 and 6, the deformation amount measurement structure 3 includes a base material 30 and a sensor element 31.

  The base material 30 is a product “One Supporter” sold by As One Co., Ltd. The base material 30 extends and deforms in the left-right direction. The tensile permanent strain of the base material 30 is 3%, and the spring constant in the left-right direction is 315N. The sensor element 31 is disposed on the upper surface of the base material 30. The sensor element 31 includes a dielectric layer 32, a pair of electrode layers 33a and 33b, and a protective layer 34a.

  The dielectric layer 32 has a rectangular shape extending in the left-right direction. The length (width) of the dielectric layer 32 in the front-rear direction is 10 mm, the length in the left-right direction is 50 mm, and the thickness is 300 μm. The dielectric layer 32 includes urethane rubber. The relative dielectric constant of the dielectric layer 32 is 8.

  Each of the pair of electrode layers 33a and 33b has a rectangular shape extending in the left-right direction. The electrode layer 33 a is disposed on the upper surface of the dielectric layer 32. The electrode layer 33 b is disposed on the lower surface of the dielectric layer 32. The electrode layers 33 a and 33 b have the same width and length in the left-right direction as the dielectric layer 32. The electrode layers 33a and 33b have a thickness of 50 μm. The electrode layers 33a and 33b contain acrylic rubber and carbon black. A wiring (not shown) is connected to the electrode layers 33a and 33b. The electrode layers 33a and 33b are connected to a control device (not shown) via wiring.

  The protective layer 34a has a rectangular shape extending in the left-right direction. The protective layer 34a is disposed on the upper surface of the electrode layer 33a. The protective layer 34a covers the dielectric layer 32 and the electrode layers 33a and 33b. The protective layer 34a is laminated on the dielectric layer 32 and the electrode layers 33a and 33b in a region having a width of 10 mm and a length in the left-right direction of 50 mm. The thickness of the protective layer 34a is 300 μm. The protective layer 34a contains urethane rubber.

  When the base material 30 and the sensor element 31 are each extended in the left-right direction, the spring constant of the base material 30 is larger than the spring constant of the sensor element 31. Specifically, the spring constant of the base material 30 is about 20 times the spring constant of the sensor element 31.

  Next, the movement of the deformation amount measurement structure according to this embodiment will be described. A voltage is applied to the pair of electrode layers 33a and 33b from the control device. The sensor element 31 outputs a natural capacitance before the base material 30 is deformed. When the base material 30 extends in the left-right direction, the sensor element 31 also extends with the base material 30. At this time, the thickness of the dielectric layer 32 is reduced, and the areas of the electrode layers 33a and 33b are increased. Thereby, the electrostatic capacitance between electrode layers 33a and 33b becomes large. The control device stores in advance a map showing the relationship between the change in capacitance and the amount of elongation of the sensor element 31. When the sensor element 31 outputs the electrostatic capacity when the base material 30 is extended, the extension amount of the base material 30 is calculated from the change amount of the electrostatic capacity before and after the extension.

  Next, the effect of the deformation amount measurement structure of this embodiment will be described. In the deformation amount measuring structure 3, the tensile permanent strain of the base material 30 is 10% or less, and the spring constant of the base material 30 in the extension direction is larger than the spring constant of the sensor element 31. That is, the base material 30 is less likely to sag than the sensor element 31. For this reason, even if a sag occurs in the dielectric layer 32, the dielectric layer 32 can be pulled back to the base material 30 to return to its original shape. Thereby, the sensor element 31 can output the electrostatic capacity according to the deformation of the base material 30 even if the expansion and contraction is repeated. Therefore, according to the deformation amount measurement structure 3, the elongation amount of the base material 30 can be repeatedly measured with high accuracy without inhibiting the movement of the base material 30.

<Others>
The embodiment of the deformation amount measuring structure of the present invention has been described above. However, the embodiment is not limited to the above embodiment. Various modifications and improvements that can be made by those skilled in the art are also possible.

  For example, in the first embodiment, the protective layer may be disposed only on one of the upper surface and the lower surface of the electrode layer. Moreover, not only the protective layer but also the elastomer of the dielectric layer may have a crosslinked structure via a polyrotaxane. Further, the permanent set of the dielectric layer may be 10% or less. On the other hand, if the tensile set of the dielectric layer is 10% or less, the tensile set of the protective layer is not necessarily 10% or less. If the tensile permanent strain of at least one of the dielectric layer and the protective layer is 10% or less, the configuration of the protective layer and the dielectric layer is not limited. The elastomer of the protective layer does not necessarily have a cross-linked structure via a polyrotaxane.

  In the third embodiment, the protective layer may not be disposed. On the other hand, you may arrange | position a protective layer further between a base material and an electrode layer. In addition, either or both of the dielectric layer and the protective layer may have a crosslinked structure via a polyrotaxane. The spring constant of the base material in the extension direction is only required to be larger than the spring constant of the sensor element, and for example, it is preferably 2 or more times the spring constant of the sensor element. The smaller the spring constant of the sensor element, the better from the viewpoint of not inhibiting the expansion and contraction of the base material. The spring constant of the sensor element is preferably 300N or less, 200N or less, and further 100N or less.

  In any of the embodiments, the amount of deformation of the base material to be measured may be appropriately determined according to the deformation mode of the base material, such as an elongation amount, a bending angle, and stress. The constituent materials of the substrate, the dielectric layer, the protective layer, and the electrode layer are not limited.

  As the elastomer of the dielectric layer, it is desirable to employ one having a relatively large relative dielectric constant. For example, those having a relative dielectric constant of 5 or more (measurement frequency 100 Hz) are suitable. Such elastomers include urethane rubber, silicone rubber, nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber, natural rubber, isoprene rubber, ethylene-propylene-diene rubber (EPDM), ethylene. -Vinyl acetate copolymer, ethylene-vinyl acetate-acrylic ester copolymer, butyl rubber, styrene-butadiene rubber, fluorine rubber, epichlorohydrin rubber, chloroprene rubber, chlorinated polyethylene, chlorosulfonated polyethylene and the like.

  From the viewpoint of increasing the relative dielectric constant of the dielectric layer, the dielectric layer may contain dielectric particles as in the first embodiment. The dielectric particles may be particles having a relative dielectric constant larger than that of the matrix elastomer. For example, inorganic particles such as barium titanate, lead zirconate titanate, lanthanum-doped lead zirconate titanate, strontium titanate, bismuth titanate, and barium titanate titanate are suitable. As the dielectric particles, one kind of these may be used alone, or two or more kinds may be mixed and used. Among these, ferroelectric particles such as barium titanate and lead zirconate titanate are suitable. By applying polarization treatment to the ferroelectric particles, piezoelectricity can be expressed. Thereby, not only the deformation amount of a base material but the acceleration at the time of a deformation | transformation can also be measured.

  The elastomer for the protective layer may be selected in consideration of flexibility, tensile set, and the like. For example, in addition to urethane rubber, silicone rubber, NBR, H-NBR, ethylene-propylene copolymer rubber, EPDM, natural rubber, styrene-butadiene rubber, acrylic rubber, epichlorohydrin rubber, chlorosulfonated polyethylene, chlorinated polyethylene, etc. Is mentioned.

The ring-moving molecule contained in the dielectric layer and the protective layer has a cyclic molecule and a linear molecule that penetrates the opening of the cyclic molecule and is included in the cyclic molecule. The kind of cyclic molecule is not particularly limited. For example, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin and the like can be mentioned. The cyclic molecule may have a reactive group such as an epoxy group, a glycidyl group, —OH, —SH, —NH ₂ , —COOH, —SO ₃ H, —PO ₄ H or the like in order to crosslink with the elastomer raw material polymer. desirable. For example, a part of —OH such as α-cyclodextrin may be substituted with another reactive group. Further, α-cyclodextrin and the like may be chemically modified. Examples of the chemical modification include acetyl group, propionyl group, hexanoyl group, methyl group, ethyl group, propyl group, 2-hydroxypropyl group, 1,2-dihydroxypropyl group, cyclohexyl group, butylcarbamoyl group, hexylcarbamoyl group, A reactive group such as a phenyl group, a caprolactone group, an alkoxysilane group, an acryloyl group, a methacryloyl group, or a cinnamoyl group may be bonded to the cyclic molecule. In addition, polymer chains such as polycaprolactone and polycarbonate may be bonded directly or via the reactive group.

  The kind of linear molecule is not particularly limited. For example, polyvinyl alcohol, polyvinyl pyrrolidone, poly (meth) acrylic acid, cellulose resin (carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, etc.), polyacrylamide, polyethylene oxide, polyethylene glycol, polypropylene glycol, polyvinyl acetal resin, polyvinyl methyl Examples include hydrophilic polymers such as ether, polyamine, polyethyleneimine, casein, gelatin, and starch. Of these, polyethylene glycol is preferred.

  A blocking group may be arranged at both ends of the linear molecule so that the cyclic molecule is not detached. Blocking groups include dinitrophenyl groups, cyclodextrins, adamantane groups, trityl groups, fluoresceins, silsesquioxanes, pyrenes, substituted benzenes, optionally substituted polynuclear aromatics, and Examples include steroids.

  The elastomer of the electrode layer may be selected in consideration of flexibility, adhesiveness to the dielectric layer, and the like. For example, in addition to acrylic rubber, silicone rubber, urethane rubber, urea rubber, fluororubber, H-NBR, and various thermoplastic elastomers can be used.

  The kind of conductive material for the electrode layer is not particularly limited. For example, metal particles made of silver, gold, copper, nickel, rhodium, palladium, chromium, titanium, platinum, iron, and alloys thereof, metal oxide particles made of zinc oxide, titanium oxide, etc., titanium carbonate, etc. What is necessary is just to select suitably from electroconductive carbon materials, such as metal nanowire which consists of metal carbide particle | grains, silver, gold | metal | money, copper, platinum, nickel, etc., carbon black, a carbon nanotube, graphite, and graphene. Alternatively, particles coated with a metal such as silver-coated copper particles may be used. As the conductive material, one of these can be used alone, or two or more can be mixed and used.

From the viewpoint of improving the sensitivity (S / N ratio) of the sensor, it is desirable that the electrode resistance of the electrode layer is small. Specifically, the volume resistivity of the electrode layer is 1 × 10 ¹ Ω · cm or less, preferably 1 × 10 ⁻¹ Ω · cm or less.

  From the viewpoint of improving the adhesion between the base material and the sensor element, it is desirable that the base material and the sensor element are pressure-bonded by heat, or bonded with a soft adhesive or adhesive. Moreover, you may sew the part which does not contribute to the sensing of a sensor element to a base material.

  Next, the present invention will be described more specifically with reference to examples.

<Manufacture of dielectric layer>
[Dielectric layer 1]
First, 30.0 parts by mass of polycarbonate diol (Asahi Kasei Chemicals Co., Ltd. “Duranol (registered trademark) T5650J”, molecular weight 800) was placed in a reaction vessel, and vacuum dehydration was carried out for 2 hours while stirring. Next, the inside of the reaction vessel was purged with nitrogen. Then, 46.6 parts by mass of hexamethylene diisocyanate (Asahi Kasei Chemicals Corporation “Duranate (registered trademark) D201) and 1,4-phenylene diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) 6.05 in the reaction vessel. A mass part was added dropwise and stirred for 4 hours at 100 ° C. under a nitrogen stream to synthesize an isocyanate-terminated prepolymer A. Subsequently, 20.0 parts by mass of a polycarbonate diol (same as above) and an isocyanate-terminated prepolymer A18.6 were synthesized. A urethane reaction liquid was prepared by blending, with stirring, 0.01 parts by mass of triethylenediamine, and degassing under reduced pressure after stirring.The prepared urethane reaction liquid was applied onto a PET substrate and dried. Thereafter, heating was performed at 150 ° C. for 3 hours to produce a strip-shaped dielectric layer 1 having a width of 25 mm and a length of 50 mm. The same is true in the following dielectric layer 2-5.

[Dielectric layer 2]
20.0 parts by mass of polycarbonate diol (same as above), 2.2 parts by mass of a modified polyrotaxane having a hydroxyl group (“SH3400P” manufactured by Advanced Soft Materials Co., Ltd.), 19.7 parts by mass of synthesized isocyanate-terminated prepolymer A, Then, 0.01 part by mass of triethylenediamine was blended, and after stirring, degassed under reduced pressure to prepare a urethane reaction solution. The cyclic molecule of the modified polyrotaxane having a hydroxyl group is α-cyclodextrin, the linear molecule is polyethylene glycol, and the blocking group is an adamantane group. The prepared urethane reaction liquid was applied onto a PET substrate, dried, and then heated at 150 ° C. for 3 hours to produce a strip-shaped dielectric layer 2.

[Dielectric layer 3]
20.0 parts by mass of a polycarbonate diol (same as above), 5.0 parts by mass of a modified polyrotaxane having a hydroxyl group (same as above), 21.0 parts by mass of the synthesized isocyanate-terminated prepolymer A, and 0.01 parts by mass of triethylenediamine. After mixing and stirring, vacuum degassing was performed to prepare a urethane reaction solution. The prepared urethane reaction solution was applied onto a PET substrate, dried, and then heated at 150 ° C. for 3 hours to produce a strip-shaped dielectric layer 3.

[Dielectric layer 4]
20 parts by mass of barium titanate powder (Sakai Chemical Industry Co., Ltd. “KZM50”) was added to 100 parts by mass of the urethane polymer in the urethane reaction liquid used for the production of the dielectric layer 3 and dispersed with three rolls. The reaction solution was applied onto a PET substrate, dried, and then heated at 150 ° C. for 3 hours to produce a strip-shaped dielectric layer 4.

[Dielectric layer 5]
First, carboxyl group-modified hydrogenated nitrile rubber (“Terban (registered trademark) XT8889” manufactured by LANXESS) was dissolved in acetylacetone to prepare a polymer solution having a solid concentration of 12% by mass. Next, 5 mass parts of tetrakis (2-ethylhexyloxy) titanium, an organometallic compound, was mixed with the prepared polymer solution as a crosslinking agent with respect to 100 mass parts of the polymer content. Subsequently, a dispersion of barium titanate powder was added to this solution to prepare a raw material solution. The dispersion of the barium titanate powder was added so that the barium titanate powder was 80 parts by mass with respect to 100 parts by mass of the polymer content. Then, the prepared raw material liquid was applied onto a PET substrate, dried, and then heated at 150 ° C. for 1 hour to produce a strip-shaped dielectric layer 5.

  A dispersion of barium titanate powder was produced as follows. First, barium titanate powder ("BT-TO-020RF" manufactured by Toda Kogyo Co., Ltd.) was added to acetylacetone as a solvent to prepare a preliminary dispersion. Next, the preliminary dispersion was subjected to mechanochemical treatment using a wet bead mill (“Research Lab” manufactured by Willy et Bacofen, media diameter: 0.1 mm). The liquid after the treatment was passed through a filter (“LPJ-MPX-006-N2” manufactured by Loki Techno Co., Ltd.) to obtain a dispersion.

  Table 1 shows the material and physical properties of the manufactured dielectric layer. In Table 1, methods for measuring the dielectric constant, elongation at break, tensile permanent strain, and elastic modulus are as follows. The measuring method of elongation at break, tensile set, and elastic modulus is the same for the electrode layer and protective layer described later.

[Relative permittivity]
The dielectric layer was placed on a sample holder (Solartron, type 12962A), and the dielectric constant was measured using a dielectric constant measurement interface (made by the company, type 1296) and a frequency response analyzer (made by the company, type 1255B). (Frequency 100 Hz).

[Elongation at cutting]
The tensile test prescribed | regulated to JISK6251: 2010 was done and elongation at break was computed. The shape of the test piece was dumbbell-shaped No. 5.

[Tensile permanent set]
A constant elongation tensile permanent strain test using a strip-shaped test piece specified in JIS K 6273: 2006 is performed under the conditions of an elongation of 50% applied to the test piece, a test temperature of 50 ° C., and a test time of 20 hours. Calculated.

[Elastic modulus]
The tensile test prescribed | regulated to JISK7127: 1999 was done, and the elasticity modulus was computed from the obtained stress-elongation curve. The shape of the test piece was test piece type 2.

<Manufacture of electrode layer>
[Electrode layer 1]
First, 100 parts by mass of an acrylic rubber polymer (“Nipol (registered trademark) AR42W” manufactured by Nippon Zeon Co., Ltd.) and 0.25 parts by mass of isophoronediamine as a crosslinking agent were mixed with a roll kneader to prepare a mixture. . Next, the mixture was dissolved in the solvent ethylene glycol monobutyl ether acetate to prepare a polymer solution. Subsequently, 35 parts by mass of carbon nanotubes (“VGCF (registered trademark)” manufactured by Showa Denko KK, fiber diameter: 150 nm, length: 10 μm) and conductive carbon black (manufactured by Ketjen Black International Co., Ltd.) 18 parts by mass of “Ketjen Black EC300J”) and 20 parts by mass of a polymer compound containing an amino group as a dispersant (“BYK-185” manufactured by Big Chemie Japan Co., Ltd.) A conductive paint was prepared by kneading. Then, the conductive paint was applied on a PET substrate by a bar coating method, dried, and then heated at 150 ° C. for 1 hour to produce a strip-shaped electrode layer 1 having a width of 15 mm and a length of 40 mm. The volume resistivity of the manufactured electrode layer 1 was 0.05 Ω · cm. About volume resistivity, it measured according to the parallel terminal electrode method prescribed | regulated to JISK6271: 2008. The measurement was performed by applying a DC voltage of 100V.

Table 2 shows the materials and physical properties of the manufactured electrodes.

<Manufacture of protective layer>
[Protective layer 1]
A liquid A and B liquid of silicone rubber (“KE1935” manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed at the same mass, degassed by vacuum to remove bubbles, and press molded at 150 ° C. for 30 minutes. This was heat-treated at 150 ° C. for 4 hours to produce a strip-shaped protective layer 1 having a width of 25 mm and a length of 50 mm. The width and length of the protective layer are the same in the following protective layers 2 to 7.

[Protective layer 2]
First, 30.0 parts by mass of polycarbonate diol (same as above) was placed in a reaction vessel, and dehydration under reduced pressure was carried out for 2 hours while stirring. Next, the inside of the reaction vessel was purged with nitrogen. Then, 21.9 parts by mass of hexamethylene diisocyanate (same as above) and 10.0 parts by mass of 1,4-phenylene diisocyanate (same as above) are dropped into the reaction vessel and stirred at 100 ° C. for 4 hours under a nitrogen stream. Thus, an isocyanate-terminated prepolymer B was synthesized. Subsequently, 20.0 parts by mass of polycarbonate diol (same as above), 18.6 parts by mass of isocyanate-terminated prepolymer B, and 0.01 parts by mass of triethylenediamine were blended, deaerated under reduced pressure after stirring, and urethane reaction liquid Was prepared. The prepared urethane reaction liquid was applied onto a substrate made of PET, dried, and then heated at 150 ° C. for 3 hours to produce a strip-shaped protective layer 2.

[Protective layer 3]
A protective layer 3 was produced in the same manner as the dielectric layer 2.

[Protective layer 4]
A protective layer 4 was produced in the same manner as the protective layer 1 except that the silicone rubber was changed to “KE1950-10” manufactured by Shin-Etsu Chemical Co., Ltd.

[Protective layer 5]
First, 30.0 parts by mass of polycarbonate diol (same as above) was placed in a reaction vessel, and dehydration under reduced pressure was carried out for 2 hours while stirring. Next, the inside of the reaction vessel was purged with nitrogen. Then, 85.0 parts by mass of hexamethylene diisocyanate (same as above) was dropped into the reaction vessel and stirred at 100 ° C. for 4 hours under a nitrogen stream to synthesize isocyanate-terminated prepolymer C. Subsequently, 20.0 parts by mass of polycarbonate diol (same as above), 2.2 parts by mass of a modified polyrotaxane having a hydroxyl group (same as above), 19.7 parts by mass of isocyanate-terminated prepolymer C, 0.01 parts by mass of triethylenediamine, Was mixed and deaerated under reduced pressure after stirring to prepare a urethane reaction solution. The prepared urethane reaction liquid was applied onto a substrate made of PET, dried, and then heated at 150 ° C. for 3 hours to produce a strip-shaped protective layer 5.

[Protective layer 6]
A protective layer 6 was produced in the same manner as the dielectric layer 3.

[Protective layer 7]
A protective layer 7 was produced in the same manner as the dielectric layer 1.

Table 3 shows the materials and physical properties of the manufactured protective layer.

<Manufacture of deformation measurement structure>
A sensor element was manufactured as follows by appropriately combining a dielectric layer, an electrode layer, and a protective layer. First, electrode layers were respectively arranged on two surfaces (upper surface and lower surface) in the thickness direction of the dielectric layer, and the dielectric layer and the electrode layer were pressure-bonded using a laminator (“LPD3223” manufactured by Fuji Plastics Co., Ltd.). Next, a protective layer was laminated on the electrode layer, and the protective layer and the electrode layer were pressure bonded using a laminator (same as above). In addition, when using the protective layer (protective layer 1, protective layer 4) made from a silicone rubber, after performing an excimer process as a pre-processing, it crimped | bonded with the electrode layer. For excimer treatment, an excimer lamp light source “FLAT EXCIMER” manufactured by Hamamatsu Photonics Co., Ltd. was used.

  The obtained sensor element and the substrate were bonded with an adhesive, and the periphery was further sewn to produce a deformation measuring structure. The sensor element provided with the protective layer has a configuration of protective layer / electrode layer / dielectric layer / electrode layer / protective layer in order from the base material side (see FIG. 2), and does not include the protective layer. Example 9 in Table 4 below has a configuration of electrode layer / dielectric layer / electrode layer (see FIG. 4 above) in order from the substrate side.

  The base materials used are as follows. The spring constant of the base material is an inclination from 0 to 10% in the load-displacement characteristic when the base material is extended in the same direction as the longitudinal direction of the sensor element.

[Substrate 1]
The product “One Supporter” (3% tensile set, spring constant 315N) sold by As One Co., Ltd.

[Substrate 2]
“Vescare elastic stockings” manufactured by Mitsuboshi Socks Co., Ltd. (6% tensile set, spring constant 580 N).

[Substrate 3]
Soft polyurethane foam “OY” manufactured by Achilles Co., Ltd. (18% tensile set, 30 N spring constant).

[Substrate 4]
The same urethane rubber as the protective layer 2 (tensile permanent strain 9%, spring constant 56N).

<Evaluation of deformation measurement structure>
About the manufactured deformation amount measurement structure, the initial capacitance before the substrate was deformed was measured. Then, the base material was repeatedly expanded and contracted in the longitudinal direction. Specifically, the cycle of 20% elongation-recovery was repeated 100,000 times. Thereafter, the capacitance was measured again, and the rate of change relative to the initial capacitance was calculated.

Tables 4 to 6 show the configuration of the manufactured deformation amount measurement structure and the measurement results of the capacitance. Tables 4 and 5 show the deformation measurement structures of the examples, and Table 6 shows the deformation measurement structures of the comparative examples. In Tables 4 to 6, the cross-sectional area of each layer is the cross-sectional area (width × thickness) in the lateral direction. The product (EeSe) of the elastic modulus and the cross-sectional area in the electrode layer is a value for two layers constituting the sensor element. The product (EcSc) of the elastic modulus and the cross-sectional area in the protective layer is also a value corresponding to two protective layers constituting the sensor element.

  In Table 4 and Table 5, the sensor element which comprises the deformation measuring structure of Examples 1-8 and 10-12 has a protective layer. Among these, in Examples 1 to 3, the tensile permanent strain of the dielectric layer exceeds 10%, but the tensile permanent strain of the protective layer is 10% or less. In addition, (EeSe + EySy) <EcSc is satisfied. For this reason, the sag resistance of the dielectric layer can be compensated by the protective layer, and the rate of change in capacitance is small even when the expansion and contraction are repeated, as compared with Comparative Examples 1 and 2 described later. In Example 12, although (EeSe + EySy) <EcSc is not satisfied, the tensile permanent strain of the protective layer is 10% or less. In addition, the tensile set of the substrate 1 is 10% or less, and the spring constant of the substrate 1 in the expansion / contraction direction is larger than the spring constant of the sensor element in the same direction. For this reason, compared with the comparative examples 1 and 2, even if expansion / contraction was repeated, the change rate of the electrostatic capacitance became small.

  As shown in Table 1 above, in the dielectric layers 2 to 4 including the elastomer having a crosslinked structure via a polyrotaxane, the tensile set was 10% or less. In the dielectric layer 4, even when dielectric particles were included, the tensile permanent set was 10% or less. Among these, in Examples 5 and 10 including the dielectric layer 3, the tensile permanent strain of the protective layer exceeds 10%, but the tensile permanent strain of the dielectric layer is 10% or less. In addition, (EeSe + EcSc) <EySy is satisfied. For this reason, the sag resistance of the protective layer can be compensated for by the dielectric layer, and the rate of change in capacitance is small even when the expansion and contraction are repeated, as compared with Comparative Examples 1 and 2. In Examples 4, 6, and 7, the tensile set of both the protective layer and the dielectric layer is 10% or less. In addition, EeSe <(EcSc + EySy) is satisfied. In this case, the change rate of the capacitance was smaller and became 5% or less. In Examples 7 and 8 including dielectric layers 4 and 5 including dielectric particles, the rate of change in capacitance is small because the dielectric layer and the protective layer or only the protective layer has high sag resistance. It was.

  In Example 11, both the permanent set of the dielectric layer and the protective layer exceed 10%. Further, the elastomer of the dielectric layer does not have a crosslinked structure via a polyrotaxane. However, the tensile permanent strain of the base material 1 is 10% or less, and the spring constant of the base material 1 in the expansion / contraction direction is larger than the spring constant of the sensor element in the same direction. For this reason, compared with the comparative examples 1 and 2, even if expansion / contraction was repeated, the change rate of the electrostatic capacitance became small.

  The sensor element constituting the deformation measurement structure of Example 9 does not have a protective layer. However, the elastomer of the dielectric layer 3 has a crosslinked structure via polyrotaxane. For this reason, the tensile set of the dielectric layer 3 is 10% or less, and the sag resistance of the dielectric layer 3 is high. Moreover, the spring constant of the base material in the expansion / contraction direction is larger than the spring constant of the sensor element in the same direction (about 3.8 times). Therefore, also in the deformation amount measurement structure of Example 9, the rate of change in capacitance was smaller than in Comparative Examples 1 and 2.

  On the other hand, as shown in Table 6, the deformation amount measurement structures of Comparative Examples 1 and 2 include the same sensor elements as the deformation amount measurement structure of Example 11. However, the tensile set of the base material 3 constituting the deformation amount measurement structure of Comparative Example 1 is greater than 10%. In addition, the spring constant of the base material 3 in the expansion / contraction direction is smaller than the spring constant of the sensor element in the same direction. For this reason, the rate of change in capacitance after repeated expansion and contraction was 17%. The tensile permanent strain of the base material 4 constituting the deformation amount measurement structure of Comparative Example 2 is 10% or less. However, the spring constant of the base material 4 in the expansion / contraction direction is smaller than the spring constant of the sensor element in the same direction. For this reason, the rate of change in capacitance after repeated expansion and contraction was 15%.

  If the rate of change in capacitance before and after deformation is small, the amount of deformation due to elongation or bending of the substrate can be measured repeatedly with high accuracy. The smaller the change rate of the capacitance, the higher the sensing accuracy can be used. For example, it is desirable that the capacitance change rate when 20% elongation-restoration is repeated 100,000 times is 12% or less. It is more preferable that it is 10% or less, further 5% or less.

  The deformation measurement structure of the present invention is suitable for wearable devices, powered suits, power assist devices, nursing care, industrial robots, and the like.

1: Deformation measurement structure, 10: base material, 11: sensor element, 12: dielectric layer, 13a, 13b: electrode layer, 14a, 14b: protective layer.
2: Deformation measurement structure, 20: base material, 21: sensor element, 22: dielectric layer, 23a, 23b: electrode layer.
3: Deformation measurement structure, 30: base material, 31: sensor element, 32: dielectric layer, 33a, 33b: electrode layer, 34a: protective layer.

Claims (8)

A base material that stretches or bends, and
A dielectric layer disposed on the surface of the substrate and containing an elastomer, a pair of electrode layers disposed between the dielectric layers and including an elastomer and a conductive material, and an elastomer disposed on at least one surface of the pair of electrode layers And a sensor layer that expands and contracts following the deformation of the base material.
The tensile set of at least one of the dielectric layer and the protective layer is 10% or less,
A deformation amount measuring structure, wherein the deformation amount due to elongation or bending of the base material is measured based on a change in capacitance output from the sensor element. The elastic modulus and cross-sectional area of each of the dielectric layer, the electrode layer, and the protective layer in the sensor element satisfy any one of the following formulas (I), (II), and (III). Deformation measurement structure.
(I) When the tensile set of only the protective layer of the dielectric layer and the protective layer is 10% or less (EeSe + EySy) <EcSc (I)
(Ii) When the tensile set of only the dielectric layer of the dielectric layer and the protective layer is 10% or less (EeSe + EcSc) <EySy (II)
(Iii) When the tensile set of the protective layer and the dielectric layer is 10% or less EeSe <(EcSc + EySy) (III)
[Ee: Elastic modulus of electrode layer, Se: Cross sectional area of electrode layer, Ey: Elastic modulus of dielectric layer, Sy: Cross sectional area of dielectric layer, Ec: Elastic modulus of protective layer, Sc: Cross sectional area of protective layer]   The elastomer of at least one of the dielectric layer and the protective layer is mediated by a ring molecule having a cyclic molecule and a linear molecule penetrating through the opening of the cyclic molecule and being included in the cyclic molecule. A cross-linked structure, wherein at least a part of the polymer chain of the elastomer is cross-linked with the cyclic molecule, and the cross-linking point moves by moving the cyclic molecule along the linear molecule. The deformation measuring structure according to claim 1 or 2. A base material that stretches or bends, and
A dielectric layer including an elastomer disposed on the surface of the substrate and a pair of electrode layers disposed between the dielectric layer and including an elastomer and a conductive material, and expanding and contracting following the deformation of the substrate And a sensor element
The elastomer of the dielectric layer has a crosslinked structure via a ring-moving molecule having a cyclic molecule and a linear molecule penetrating through the opening of the cyclic molecule and being included in the cyclic molecule, At least a part of the polymer chain of the elastomer is crosslinked with the cyclic molecule, and the crosslinking point moves when the cyclic molecule moves along the linear molecule,
A deformation amount measuring structure, wherein the deformation amount due to elongation or bending of the base material is measured based on a change in capacitance output from the sensor element. A base material that stretches or bends, and
A dielectric layer including an elastomer disposed on the surface of the substrate and a pair of electrode layers disposed between the dielectric layer and including an elastomer and a conductive material, and expanding and contracting following the deformation of the substrate And a sensor element
The tensile set of the substrate is 10% or less,
When the base material and the sensor element are each stretched in the same direction in the plane direction, the spring constant of the base material is larger than the spring constant of the sensor element,
A deformation amount measuring structure, wherein the deformation amount due to elongation or bending of the base material is measured based on a change in capacitance output from the sensor element.   The deformation amount measuring structure according to claim 5, wherein the sensor element further includes a protective layer disposed on at least one surface of the pair of electrode layers and containing an elastomer.   The deformation measuring structure according to claim 1, wherein the dielectric layer has a relative dielectric constant of 5 or more.   The deformation measurement structure according to claim 1, wherein the dielectric layer includes dielectric particles.

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