JP2009198483A - Sensor thin film, manufacturing method thereof and deformation sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a sensor thin film capable of detecting deformation of a member or a region or a load given thereto, from a sensor forming material made into coating, and a deformation sensor using the sensor thin film thus obtained. <P>SOLUTION: The sensor thin film 21 is manufactured by the method wherein the sensor coating prepared by dispersing a spherical electroconductive filler in a liquid resin material constituted mainly of a pre-cure resin of a thermosetting resin is applied on the surface of a base 20 and dried. The sensor thin film 21 thus manufactured includes the thermosetting resin and the electroconductive filler which is compounded in the thermosetting resin in a state of almost single particles and in a high filling rate. The thin film is elastically deformable and the electric resistance increases as the amount of elastic deformation increases. The deformation sensor 2 includes the base 20, the sensor thin film 21 disposed on the surface of the base 20 and electrodes 22a and 22b which are connected to the sensor thin film 21 and capable of outputting the electric resistance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sensor thin film used for a sensor capable of detecting deformation or the like of a member, a manufacturing method thereof, and a deformation sensor.

For example, sensors using pressure-sensitive conductive resins or pressure-sensitive conductive elastomers have been proposed as means for detecting deformation or deformation of members and the magnitude and distribution of loads acting on the members (for example, Patent Documents 1 to 3). reference). The pressure-sensitive conductive resin or the like is configured by dispersing a conductive filler in a resin or elastomer as a base material. A pressure-sensitive conductive resin or the like has a characteristic that electric resistance decreases when it is deformed. That is, before deformation, the electrical resistance is large because the conductive fillers are separated from each other. When deformed by compression or the like, the conductive fillers come into contact with each other to form a one-dimensional conductive path, so that the electric resistance is reduced.
Japanese Patent Laid-Open No. 5-9300 Japanese Patent Laid-Open No. 11-251112 Japanese Patent Laid-Open No. 2003-4552

  As described in the above-mentioned patent document, the conventional sensor detects the deformation by utilizing the fact that the conductive filler contacts and conducts at the time of deformation and the electric resistance decreases. Therefore, when the conductive filler is brought into a certain contact state due to compression or the like, the change in electric resistance becomes small. For this reason, the measurement range is narrow. Further, the sensitivity varies greatly depending on the blending ratio of the conductive filler and the like.

  On the other hand, the present inventor has developed a very specific sensor material that is elastically deformable and has an electrical resistance that increases as the amount of elastic deformation increases. The developed sensor material is formed by filling a base elastomer with a spherical conductive filler in a predetermined state. In this sensor material, a three-dimensional conductive path is formed by contact between conductive fillers in a state in which no load is applied (hereinafter referred to as “no-load state” as appropriate), in other words, in a natural state in which the sensor material is not deformed. Is formed. For this reason, it has high conductivity in a no-load state. On the other hand, when the sensor material is elastically deformed, the contact state between the conductive fillers changes. For this reason, electrical resistance increases as the amount of elastic deformation increases.

  Since the sensor material uses an elastomer as a base material, the sensor material is usually manufactured through three steps of kneading raw materials → molding → crosslinking. For this reason, the apparatus for performing each process and the energy for a heating are needed. In this regard, even when a thermoplastic resin that does not need to be cross-linked is used as a base material, a process of heating and melting and molding is required, and thus an apparatus and energy are required. In addition, when a thermoplastic resin is used, the usable temperature range is limited by the melting point. Further, when the sensor material is molded into a complicated shape, it is necessary to employ a special mold or molding method, which increases the manufacturing cost and labor. Furthermore, it is difficult to reduce the thickness of the sensor material by molding using a mold. Moreover, when producing a sensor from the molded sensor material, it is necessary to attach components, such as an electrode and a conducting wire, to the sensor material. It is troublesome to integrate the components. For example, when an adhesive is used for joining the components, reliability at the joining interface may be a problem.

  This invention is made | formed in view of such a situation, and makes it a subject to provide the method of manufacturing the sensor thin film which can detect a deformation | transformation and load of a member and a site | part from the sensor-forming material made into paint. . It is another object of the present invention to provide a deformation sensor using the obtained sensor thin film.

  (1) The sensor thin film of the present invention is obtained by applying a sensor coating material in which a spherical conductive filler is dispersed in a liquid resin material whose main component is a pre-curing resin of a thermosetting resin, and curing the coating material on a substrate surface. The resulting thermosetting resin, and the conductive filler blended in the thermosetting resin in a substantially single particle state and with a high filling rate, are elastically deformable, and are elastically deformed. The electrical resistance increases as the amount increases (corresponding to claim 1).

  In the present invention, the sensor coating material (liquid sensor forming material) uses a liquid resin material whose main component is a pre-curing resin of a thermosetting resin as a mother liquor. Here, “having a pre-curing resin of a thermosetting resin as a main component” means that the resin component as a base material of the sensor thin film includes only a pre-curing resin (prepolymer) of the thermosetting resin. To do. Therefore, the liquid resin material may contain a curing agent, a catalyst, a solvent, an additive, and the like as necessary in addition to the pre-curing resin.

  The sensor thin film of the present invention is obtained by applying and curing a sensor paint on the surface of a substrate. For this reason, it is possible to easily obtain sensor thin films having various shapes and sizes according to applications. Further, it is easy to make a thin film as compared with molding by a mold. Therefore, material costs, processing costs, etc. can be reduced accordingly, and a cheaper and smaller sensor can be realized.

  Further, according to the sensor thin film of the present invention, it is easy to integrate components necessary for the sensor. For example, a sensor element can be easily manufactured by printing an electrode, a conducting wire, etc. in advance on the surface of a base material, and applying a sensor paint thereon. In addition, a plurality of sensor elements can be stacked by thinning the sensor elements.

  The sensor thin film of the present invention uses a thermosetting resin obtained by curing a pre-curing resin as a base material. The thermosetting resin has a three-dimensional network structure. For this reason, compared with a thermoplastic resin, heat resistance is high and shape retention property is excellent. Further, for example, by changing the crosslinking density, the thermal expansion coefficient, Young's modulus, etc. can be easily adjusted, and desired thermal characteristics can be easily realized.

  In the sensor thin film of the present invention, the spherical conductive filler is blended in the thermosetting resin in a substantially single particle state with a high filling rate. The “substantially single particle state” means that 50% by weight or more when the total weight of the conductive filler is 100% by weight is present not in the form of aggregated secondary particles but in the form of single primary particles. Say. Further, “high filling rate” means that the conductive filler is blended in a state close to closest packing.

  In the sensor thin film of the present invention, a three-dimensional conductive path is formed by contact between conductive fillers as in the sensor material described above. Therefore, the sensor thin film of the present invention has high conductivity in a no-load state, and the electrical resistance increases as the amount of elastic deformation increases. Note that “elastic deformation” includes all deformation due to compression, extension, bending, and the like. This mechanism is considered as follows. 1 and 2 show changes in the conductive path of the sensor thin film of the present invention before and after the application of a load as a model. However, what is shown in FIG. 1 and FIG. 2 is an example of a sensor thin film, and does not limit the filling state and shape of the conductive filler at all.

  As shown in FIG. 1, in the sensor thin film 100, most of the conductive fillers 102 are present in the thermosetting resin 101 in a primary particle state (substantially single state). Moreover, the filling rate of the conductive filler 102 is high, and it is blended in a state close to closest packing. Thereby, in the no-load state, the sensor thin film 100 is formed with a three-dimensional conductive path P by the conductive filler 102. Therefore, in the no-load state, the electric resistance of the sensor thin film 100 is small. On the other hand, as shown in FIG. 2, when a load is applied to the sensor thin film 100, the sensor thin film 100 is elastically deformed (the dotted line frame in FIG. 2 indicates the no-load state in FIG. 1). Here, since the conductive filler 102 is blended in a state close to closest packing, there is almost no space where the conductive filler 102 can move. Therefore, when the sensor thin film 100 is elastically deformed, the conductive fillers 102 repel each other, and the contact state between the conductive fillers 102 changes. As a result, the three-dimensional conductive path P collapses and the electrical resistance increases.

  Therefore, according to the sensor using the sensor thin film of the present invention, it is possible to detect various deformations of the target member, the load acting on the part, and the member and the part based on the increase in electrical resistance.

  (2) The method for producing a sensor thin film of the present invention comprises a thermosetting resin, and a spherical conductive filler that is blended in the thermosetting resin in a substantially single particle state with a high filling rate. A method of manufacturing a sensor thin film that is elastically deformable and has an electrical resistance that increases as the amount of elastic deformation increases, wherein the conductive resin is added to a liquid resin material mainly composed of a resin before curing of the thermosetting resin. A sensor coating preparation step of preparing a sensor coating by mixing a functional filler, and a curing step of applying the sensor coating to the surface of the substrate and curing the formed coating film. 6).

  According to the manufacturing method of the present invention, the above-described sensor thin film of the present invention can be manufactured easily and at low cost. Moreover, the film thickness of a sensor thin film can be made more uniform by apply | coating a sensor coating material to the base-material surface, and making it harden | cure. Further, the film thickness of the sensor thin film can be made extremely thin by a coating method.

  (3) The deformation sensor of the present invention includes a base material, the sensor thin film of the present invention (1) disposed on the surface of the base material, an electrode connected to the sensor thin film and capable of outputting electrical resistance, (Corresponding to claim 8).

  The deformation sensor of the present invention provided with the sensor thin film of the present invention is based on the increase in the electrical resistance of the sensor thin film output from the electrode, and various deformations of the target member, the load acting on the part, and the member and part. Can be detected. Further, by using sensor thin films having various shapes and sizes, it is possible to detect loads and deformations in a wide region of members and parts. Further, by reducing the thickness of the sensor thin film, the deformation sensor can be reduced in size and stacked.

  In the deformation sensor of the present invention, by adjusting the type of thermosetting resin used for the sensor thin film, the crosslinking density, the particle diameter of the conductive filler, the filling rate, etc., the electric resistance value in the no-load state is kept within a predetermined range. Can be set. For this reason, the range of detectable load and elastic deformation amount, that is, the detection range can be increased. In addition, since the increase behavior of the electrical resistance with respect to the elastic deformation amount can be adjusted, a desired response sensitivity can be realized.

  Moreover, the deformation sensor of the present invention has high conductivity in a no-load state. That is, the deformation sensor of the present invention is in a conductive state in a no-load state. For this reason, in a no-load state, operation diagnosis is easier as compared with a sensor having low conductivity (for example, a sensor using a conventional pressure-sensitive conductive resin or the like). That is, in the case of a sensor having low conductivity in a no-load state, it is difficult to determine whether the sensor is normal or abnormal (for example, whether a circuit is disconnected) in the no-load state. For this reason, it is necessary to dare to apply a relatively high voltage to a sensor having low conductivity. Alternatively, it is necessary to check the energized state by operating the sensor on a trial basis. Therefore, the operation diagnosis is complicated. In contrast, the deformation sensor of the present invention has high conductivity in a no-load state. For this reason, it is easy to discriminate between normal and abnormal in a no-load state. Therefore, operation diagnosis is easy.

  Hereinafter, the sensor thin film, the manufacturing method thereof, and the deformation sensor of the present invention will be described in detail.

<Sensor thin film>
The sensor thin film of the present invention is obtained by applying and curing a sensor coating material in which a spherical conductive filler is dispersed in a liquid resin material on a substrate surface. The liquid resin material is mainly composed of a pre-curing resin of a thermosetting resin. When selecting a thermosetting resin, it is desirable to consider the ease of coating, heat resistance, dimensional stability, compatibility with the conductive filler described later, and the like. For example, if the compatibility between the conductive filler and the thermosetting resin is poor, the conductive filler tends to aggregate and form aggregates (secondary particles). Therefore, it is difficult to mix a large amount of the conductive filler in the thermosetting resin. That is, it is difficult to mix the conductive filler in a state close to closest packing.

  Moreover, it is desirable to select a glass transition temperature (Tg) higher than the upper limit of the temperature range to be used. The thermosetting resin activates molecular motion at a temperature exceeding Tg, so that the elastic modulus is lowered and the volume is easily expanded. That is, the increase behavior of the electrical resistance with respect to deformation changes at the boundary of Tg. Therefore, from the viewpoint of reducing the change in electrical resistance with respect to temperature, a thermosetting resin having a suitable Tg may be selected according to the use environment. For example, when the sensor thin film of the present invention is used as a sensor for an automobile at a relatively high temperature, those having a Tg of 120 ° C. or more are suitable. Furthermore, in consideration of workability such as mixing of the liquid resin material and the conductive filler, application of the sensor paint, and the like, it is preferable that the pot life is long and the curing reaction proceeds promptly by heating after application.

  Examples of the thermosetting resin include epoxy resin, alkyd resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, polyurethane, polyimide, and the like. Especially, an epoxy resin is suitable for the following reason. That is, i) epoxy resin before curing is often a liquid having a relatively low viscosity, and thus can be formed into a paint without using a solvent. ii) Compatibility with the conductive filler is good, and the conductive filler can be blended in a substantially single particle state with a high filling rate. iii) Adhesive strength to metal, porcelain, concrete, etc. is large, so that adhesion to a substrate is good and durability is excellent. iv) High heat resistance, mechanical strength, dimensional stability, abrasion resistance, chemical resistance, water resistance, moisture resistance and the like. v) High degree of freedom of modification with various modifiers (fillers, flexibility-imparting agents, diluents, etc.), making it easy to meet desired performance requirements. Examples of the epoxy resin include bisphenol type epoxy resins (A type, F type, AD type), alicyclic epoxy resins, novolac type epoxy resins, polyglycidyl ethers obtained by reacting polyhydric alcohols with epichlorohydrin, and the like. It is done.

  A liquid resin material contains a hardening | curing agent, a catalyst, a solvent, an additive, etc. as needed other than resin before hardening. Examples of the additive include an anti-aging agent, a plasticizer, a softener, and a colorant. For example, when an epoxy resin is employed as the thermosetting resin, the liquid resin material may be configured to include an epoxy resin pre-curing resin and a curing agent. In this case, as the curing agent, amines, polyamide resins, imidazoles, liquid polymercaptan, polysulfide resins, acid anhydrides, boron trifluoride-amine complexes, dicyandiamide, organic acid hydrazides, onium salts, etc. Examples thereof include a curing agent. Of these, amines are preferred in consideration of the viscosity, pot life, cost and the like of the liquid resin material.

The liquid resin material includes a mode in which the pre-curing resin is in a liquid state, a solid pre-curing resin is dissolved in a liquid curing agent, or a mode in which a solid pre-curing resin is dissolved in a solvent. Either may be sufficient. When a solvent is used, a suitable solvent may be selected as appropriate according to the type of thermosetting resin. Among these, those having a relatively low boiling point and being easily volatile are desirable. For example, it is good to use a thing whose boiling point is 250 degrees C or less. When an epoxy resin is used as the thermosetting resin, the SP value (solubility parameter) is 9 to 14 (cal / cm ³ ) ^0.5 from the viewpoint of compatibility, and the boiling point is lower than the curing temperature. Is desirable. Examples thereof include propylene glycol monoethyl ether and ethylene glycol monoethyl ether. In addition, when a solvent is not used, such as when the pre-curing resin is in a liquid state, it is not necessary to volatilize the solvent after applying the sensor paint. For this reason, it is not necessary to increase the film thickness of the coating film in consideration of the volatile content of the solvent when applying the sensor paint. That is, when a solvent is not used, a sensor thin film having substantially the same thickness as the formed coating film can be obtained. The preparation, application, and curing of the sensor paint will be described in the following method for producing a sensor thin film of the present invention.

  The sensor thin film of this invention has the thermosetting resin which the said resin before hardening hardened | cured, and this electroconductive filler mix | blended in this thermosetting resin in the substantially single particle state and high filling rate. The conductive filler is not particularly limited as long as it is a spherical particle having conductivity. Examples thereof include fine particles such as carbon materials and metals. Of these, one can be used alone, or two or more can be used in combination. In addition, “spherical” includes not only a true sphere and a substantially true sphere, but also an oval sphere, an oval sphere (a shape in which a pair of opposing hemispheres are connected by a cylinder), a partial sphere, a sphere having a different radius for each part, and a water droplet shape. Etc. are included. For example, the aspect ratio of the conductive filler (the ratio of the long side to the short side) is preferably in the range of 1 or more and 2 or less. This is because when the aspect ratio is larger than 2, a one-dimensional conductive path is easily formed by contact between the conductive fillers. In particular, from the viewpoint of bringing the filling state of the conductive filler in the thermosetting resin closer to the close-packed state, it adopts particles of a true sphere or a shape close to a true sphere (substantially true sphere) as the conductive filler. Good.

  The filling rate of the conductive filler is desirably 30 vol% or more when the entire volume of the sensor thin film is 100 vol%. In the case of less than 30 vol%, the conductive filler is hardly compounded in a state close to closest packing, and desired conductivity is not exhibited. In addition, the change in electric resistance with respect to elastic deformation of the sensor thin film becomes slow, and it becomes difficult to control the increase behavior of the electric resistance. It is more preferable that it is 35 vol% or more. On the contrary, it is desirable that the filling rate of the conductive filler is 65 vol% or less when the entire volume of the sensor thin film is 100 vol%. When it exceeds 65 vol%, it becomes difficult to mix and disperse in the liquid resin material, and it becomes difficult to form a coating film. In addition, the sensor thin film is hardly elastically deformed. It is more preferable that it is 55 vol% or less.

  In the thermosetting resin, it is desirable that the conductive filler is present in a primary particle state without being aggregated as much as possible. Therefore, when selecting the conductive filler, it is preferable to consider the average particle diameter, compatibility with the thermosetting resin, and the like. For example, the average particle diameter of the conductive filler existing in the state of primary particles is desirably 0.05 μm or more and 100 μm or less. If it is less than 0.05 μm, it tends to aggregate and form secondary particles. It is preferable that the thickness is 0.5 μm or more, further 1 μm or more. On the other hand, when the average particle diameter exceeds 100 μm, the translational movement (parallel movement) of the conductive filler due to elastic deformation becomes relatively smaller than the particle diameter, and the change in electric resistance against elastic deformation becomes slow. Moreover, it becomes difficult to reduce the film thickness of the sensor thin film. It is preferable that it is 60 μm or less, and further 30 μm or less. In addition, as an average particle diameter, the particle diameter (D50) from which an integrated weight will be 50% in the cumulative particle size curve of an electroconductive filler is employ | adopted.

  Further, it is desirable that the conductive filler has a narrow particle size distribution. For example, it is desirable that the value of D90 / D10 is 1 or more and 30 or less. When the value of D90 / D10 exceeds 30, since the particle size distribution becomes broad, the increase behavior of the electric resistance with respect to the elastic deformation amount tends to become unstable. It is more preferable that the value of D90 / D10 is 10 or less. Here, D90 is the particle diameter at which the cumulative weight is 90% in the cumulative particle size curve, and D10 is the particle diameter at which the cumulative weight is 10%.

  For example, carbon beads are suitable as the conductive filler. Specifically, Osaka Gas Chemical Co., Ltd. mesocarbon micro beads [MCMB6-28 (average particle size of about 6 μm), MCMB10-28 (average particle size of about 10 μm), MCMB25-28 (average particle size of about 25 μm)], Carbon micro beads manufactured by Nippon Carbon Co., Ltd .: Nika beads (registered trademark) ICB, Nika beads PC, Nika beads MC, Nika beads MSB [ICB 0320 (average particle size of about 3 μm), ICB 0520 (average particle size of about 5 μm), ICB 1020 (average particle size of about 10 μm) ), PC0720 (average particle diameter of about 7 μm), MC0520 (average particle diameter of about 5 μm)], Nisshinbo carbon beads (average particle diameter of about 10 μm), and the like.

  What is necessary is just to determine the film thickness of the sensor thin film of this invention suitably according to the use etc. of a sensor. For example, it is desirable that the film thickness be 10 μm or more and 500 μm or less from the viewpoint of miniaturization, thinning, and lamination of the sensor. 100 μm or less is more preferable.

<Method for manufacturing sensor thin film>
The method for producing a sensor thin film of the present invention includes a sensor paint preparation step and a curing step. Hereinafter, each process is demonstrated in order.

(1) Sensor paint preparation process This process is a process of preparing a sensor paint by mixing a conductive filler with a liquid resin material mainly composed of a pre-curing resin of a thermosetting resin. The liquid resin material and the conductive filler are as described above. A sensor paint may be prepared by adding a conductive filler to a liquid resin material and stirring and mixing. Moreover, what is necessary is just to adjust the compounding quantity of an electroconductive filler suitably so that it may become a desired filling rate.

(2) Curing step This step is a step of applying the prepared sensor paint to the substrate surface and curing the formed coating film. The material of the substrate is not particularly limited as long as it can form a coating film of the sensor paint. For example, a resin film such as polyimide, polyethylene, or polyethylene terephthalate (PET) having high insulating properties can be used.

  As a method for applying the sensor paint, various known methods can be employed. For example, in addition to printing methods such as inkjet printing, flexographic printing, gravure printing, screen printing, pad printing, and lithography, dipping, spraying, bar coating, and the like can be given. For example, when a printing method is employed, it is possible to easily separate the applied part and the non-applied part. Also, printing of large areas, thin lines, and complicated shapes is easy. Furthermore, since the sensor thin film, the electrode, and the conductive wire can be formed by the same method, the sensor parts can be easily integrated. Among the printing methods, a high-viscosity paint can also be used, and the screen printing method is preferred because the coating thickness can be easily adjusted.

  After applying the sensor paint, the formed coating film may be cured at room temperature or under heating. The curing conditions (temperature, time, etc.) may be appropriately determined according to the type of thermosetting resin, curing agent, and catalyst. Moreover, when making it harden | cure, temperature, hardening time, etc. can be adjusted and the crosslinking density of the sensor thin film obtained can be adjusted. Thereby, adjustment of a thermal expansion coefficient, a Young's modulus, etc. of a sensor thin film is attained. Thus, the sensor thin film of the present invention, that is, the spherical conductive filler is blended in a substantially single particle state with a high filling rate in the thermosetting resin, is elastically deformable, and is elastically deformed. Sensor thin films can be manufactured that increase in electrical resistance as the amount increases.

<Deformation sensor>
A deformation sensor can be configured using the sensor thin film of the present invention. Hereinafter, a deformation sensor using the sensor thin film of the present invention, that is, an embodiment of the deformation sensor of the present invention will be described.

(1) First Embodiment First, the configuration of the deformation sensor of this embodiment will be described. FIG. 3 shows a front view of the deformation sensor. FIG. 4 is a sectional view taken along the line IV-IV in FIG. For convenience of explanation, FIG. 3 shows the cover film with the right half removed. In FIG. 4, the conductive wire is omitted. As shown in FIGS. 3 and 4, the deformation sensor 2 includes a base material 20, a sensor thin film 21, electrodes 22 a and 22 b, an insulating film 23, and a cover film 24.

  The base material 20 is made of PET and has a strip shape extending in the left-right direction. A connector 25 is attached to the right end of the substrate 20. The insulating film 23 is made of acrylic resin and has a strip shape extending in the left-right direction. The insulating film 23 covers the surface of the substrate 20. In the center of the insulating film 23 in the width direction (vertical direction), a long hole 230 extending in the left-right direction and corresponding to the sensor thin film 21 is formed.

  The sensor thin film 21 has a strip shape extending in the left-right direction. The film thickness of the sensor thin film 21 is about 100 μm. The sensor thin film 21 is fixed to the surface of the base material 20 while being accommodated in the long hole 230 of the insulating film 23. The sensor thin film 21 is formed by mixing carbon beads (conductive filler) in an approximately single particle state with a high filling rate in an epoxy resin. The filling rate of the carbon beads is about 45 vol% when the volume of the sensor thin film 21 is 100 vol%.

  The electrode 22 a is attached to the left end of the sensor thin film 21, and the electrode 22 b is attached to the right end of the sensor thin film 21. More specifically, the electrodes 22a and 22b both have a strip shape extending vertically, and are interposed between the sensor thin film 21 and the base material 20 and between the insulating film 23 and the base material 20. Yes. The electrode 22a and the connector 25 are connected by a conducting wire 26a, and the electrode 22b and the connector 25 are connected by a conducting wire 26b.

  The cover film 24 is made of acrylic rubber and has a strip shape extending in the left-right direction. The cover film 24 covers the surfaces of the insulating film 23 and the sensor thin film 21.

  Next, the movement of the deformation sensor 2 will be described. When a load is applied from the back side (front side) in FIG. 3 to the vicinity of the center in the left-right direction of the deformation sensor 2, the sensor thin film 21 bends backward via the base material 20. That is, the sensor thin film 21 is curved and deformed into a C shape opening forward. In the no-load state, as shown in FIG. 1, the conductive filler 102 is filled in a state close to closest packing. For this reason, a large number of conductive paths P are formed. Therefore, the detected electrical resistance value between the electrodes 22a and 22b is relatively small. On the other hand, after the load is applied, the conductive fillers 102 repel each other as shown in FIG. For this reason, the conductive path P collapses. Therefore, the detected electrical resistance value between the electrodes 22a and 22b becomes larger than the unloaded state.

  Next, the effect of the deformation sensor 2 of this embodiment is demonstrated. In the deformation sensor 2 of the present embodiment, the electrical resistance increases when the sensor thin film 21 is elastically deformed. For this reason, based on the increase in the electrical resistance of the sensor thin film 21 output from the electrodes 22a and 22b, various deformations such as a load acting on the target member and part, and compression and bending of the target member and part are detected. Can do.

  The sensor thin film 21 is manufactured by applying a sensor coating material in which carbon beads are dispersed in a liquid resin material containing an epoxy resin before curing and a curing agent to the surface of the base material 20 and curing it. For this reason, the manufacturing process of the deformation sensor 2 is simplified, and the manufacturing cost can be reduced. Further, since the deformation sensor 2 can be elastically deformed, it can also be arranged on a member having a curved surface shape. Further, since the sensor thin film 21 is thin, the deformation sensor 2 can be laminated.

  Further, the electric resistance value in a no-load state is set to a predetermined range by adjusting the kind of base material (thermosetting resin) of the sensor thin film 21, the crosslinking density, the particle diameter of the conductive filler, the filling rate, and the like. be able to. For this reason, the range of detectable load and elastic deformation amount, that is, the detection range can be increased. In addition, since the increase behavior of the electrical resistance with respect to the elastic deformation amount can be adjusted, a desired response sensitivity can be realized.

  The deformation sensor 2 of the present embodiment is in a conductive state in a natural state that is not deformed. Therefore, a self-diagnosis as to whether or not the deformation sensor 2 is operable can be easily performed by passing a current through a circuit in which the deformation sensor 2 is incorporated.

(2) Second embodiment The difference between the deformation sensor of the present embodiment and the deformation sensor of the first embodiment is that the sensor thin film, electrode, conductor, connector, insulating film, and cover film are all formed by a printing method. It is. Therefore, the differences will be mainly described here.

  FIG. 5 shows a front view of the deformation sensor of the present embodiment. FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. Parts corresponding to those in FIGS. 3 and 4 are denoted by the same reference numerals. Further, in FIG. 5, for convenience of explanation, the right half of the cover film is removed and shown. As shown in FIGS. 5 and 6, the deformation sensor 2 includes a base material 20, a sensor thin film 21, electrodes 27 a and 27 b, an insulating film 28, a cover film 24, conductive wires 29 a and 29 b, and a connector 25. It is equipped with.

  The electrode 27 a is disposed at the left end of the sensor thin film 21, and the electrode 27 b is disposed at the right end of the sensor thin film 21. Specifically, the electrodes 27a and 27b both have a rectangular shape, and are interposed between the sensor thin film 21 and the base material 20 (shown by dotted lines in FIG. 5). The sensor thin film 21, the electrodes 27a and 27b, the insulating film 28, the cover film 24, the conductive wires 29a and 29b, and the connector 25 are all formed by screen printing. Hereinafter, a method for manufacturing the deformation sensor 2 will be described.

  First, the electrodes 27a and 27b, the conductors 29a and 29b, and the conductor paint for the connector 25 are screen-printed on the surface of the base material 20 and cured. Subsequently, the coating material for the insulating film 28 is printed and cured on portions other than the printed electrodes 27a and 27b, the conductive wires 29a and 29b, and the connector 25. Next, the sensor paint for the sensor thin film 21 is printed and cured. Finally, a coating material for the cover film 24 is printed and cured so as to cover the exposed conductive wires 29a and 29b, the connector 25, and the sensor thin film 21.

  The deformation sensor 2 of the present embodiment has the same operational effects as the deformation sensor of the first embodiment. Further, according to the deformation sensor 2 of the present embodiment, all sensor components such as the sensor thin film 21 and the electrodes 27a and 27b are formed by a printing method. For this reason, a manufacturing process can be simplified. Further, the manufacturing time can be shortened. Therefore, the deformation sensor 2 can be manufactured at a lower cost. Further, since the sensor parts can be easily integrated, mass production is easy. In addition, the sensor component can be easily thinned. For this reason, the deformation sensor 2 can be easily downsized and stacked. In addition, sensor parts having other functions such as a conductive film for removing electrical noise can be further laminated.

(3) Others The embodiment of the deformation sensor of the present invention has been described above. However, the embodiment is not particularly limited to the above embodiment. Various modifications and improvements that can be made by those skilled in the art are also possible.

  For example, the material of the base material, the insulating film, and the cover film is not particularly limited as long as it is an insulating material. Here, the base material may be a target member itself for detecting deformation. Moreover, it is not necessary to arrange an insulating film or a cover film. What is necessary is just to set suitably also about the number of electrodes and an arrangement place. Further, a load may be input from the sensor thin film side, that is, from the front side (rear side) in FIGS. 3 and 5. Also, in the deformation sensor of the present invention, it is desirable to adopt a preferred embodiment of the sensor thin film of the present invention.

  Sensor thin films each comprising a thermosetting resin and a thermoplastic resin as a base material were manufactured, and the responsiveness to deformation of the deformation sensor provided with each sensor thin film was evaluated. Hereinafter, it demonstrates in order.

<Example A>
(1) Manufacture of Sensor Thin Film and Deformation Sensor (1-1) Deformation Sensor of Examples First, 100 parts by weight of an epoxy resin before curing (“Pernox (registered trademark) ME-510” manufactured by Nippon Pernox Co., Ltd .; liquid) , 100 parts by weight of a curing agent (“Percure (registered trademark) HV-511; liquid) manufactured by Nippon Pernox Co., Ltd.” and carbon beads (“Nika Beads ICB0520” manufactured by Nippon Carbon Co., Ltd.), average particle size of about 5 μm, D90 / D10 in the particle size distribution = 3.2) 200 parts by weight were mixed with blade stirring to prepare a sensor paint. The prepared sensor paint was applied to the surface of a PET substrate (distance between electrodes: 70 mm) on which a pair of electrodes and conductors had been printed in advance by a screen printing method (the length of the coating film was about 80 mm, the width was about 5 mm, Thickness about 100 μm). The coating film was kept at 140 ° C. for 1 hour for primary curing, and then kept at 160 ° C. for 1 hour for secondary curing to obtain a sensor thin film. At the same time, a deformation sensor provided with the sensor thin film was obtained. The filling rate of carbon beads in the sensor thin film was 45.1 vol% when the volume of the sensor thin film was 100 vol%. The thickness of the sensor thin film was about 100 μm.

  Next, the type of the epoxy resin and the curing agent was changed, and a deformation sensor provided with a sensor thin film was obtained in the same manner as above except that. “Pernox ME-562” (liquid) manufactured by Nippon Pernox was used as the pre-curing resin for the epoxy resin, and “Percure HV-562” (liquid) manufactured by Nippon Pernox was used as the curing agent. The filling rate of carbon beads in the sensor thin film was 45.2 vol% when the volume of the sensor thin film was 100 vol%. The two types of manufactured deformation sensors were sequentially used as the deformation sensors of Examples A1 and A2. FIG. 7 shows a front view of the manufactured deformation sensor.

  As shown in FIG. 7, the deformation sensor 3 includes a base material 30, a sensor thin film 31, and a pair of electrodes 32a and 32b. The sensor thin film 31 is fixed to the surface of the base material 30. A pair of electrodes 32 a and 32 b are interposed between both longitudinal ends of the sensor thin film 31 and the base material 30. A connector 33 is attached to the right end of the substrate 30. The electrode 32a and the connector 33 are connected by a conducting wire 34a, and the electrode 32b and the connector 33 are connected by a conducting wire 34b.

(1-2) Reference Example Deformation Sensor About 100 parts by weight of thermoplastic resin polypropylene (“Sumitomo Nobren (registered trademark) H501” manufactured by Sumitomo Chemical Co., Ltd.) in a plast mill (“Lab plast mill” manufactured by Toyo Seiki Seisakusho) It was heated to 180 ° C. and melted. Thereafter, 120 parts by weight of carbon beads (same as above) were added and mixed for about 10 minutes. This was filled in a mold having a length of 80 mm, a width of 5 mm, and a thickness of 0.5 mm, and a pair of electrodes were disposed at both ends in the longitudinal direction (distance between electrodes: 70 mm), and press-molded at about 200 ° C. for 3 minutes. A sensor thin film with an electrode was taken out from the mold and attached to a PET film to obtain a deformation sensor. The filling rate of carbon beads in the obtained sensor thin film was about 49.4 vol% when the volume of the sensor thin film was 100 vol%. The thickness of the sensor thin film was about 500 μm. The manufactured deformation sensor was used as the deformation sensor of Reference Example A.

(2) Evaluation of deformation sensor response The deformation sensors of Examples A1 and A2 and Reference Example A were examined for changes in electrical resistance with respect to deformation. The electrical resistance was measured as follows. First, each deformation sensor was arranged with its longitudinal direction up and down. A pressing jig capable of reciprocating in the vertical direction is disposed above the deformation sensor. When the pressing jig is moved downward, the deformation sensor is bent and deformed. The pressing jig was moved downward by 1 mm every 30 seconds to curve the deformation sensor, and the change in electrical resistance was measured. The measurement was performed at room temperature, and the displacement amount of the pressing jig was 0 to 5 mm. The measurement result of the electrical resistance with respect to the deformation in each deformation sensor is shown in FIG. The resistance change rate on the vertical axis in FIG. 8 is the ratio of the change amount of the electric resistance value (R) at each displacement amount to the initial electric resistance value (R ₀ ) [resistance change rate (% ) = (R−R ₀ ) / R ₀ × 100].

  As shown in FIG. 8, in any of the deformation sensors, the resistance change rate increased as the displacement amount increased. That is, the electrical resistance increased as the deformation amount of the deformation sensor increased. Comparing the deformation sensors of Examples A1 and A2 with the deformation sensor of Reference Example A, the deformation sensors of Examples A1 and A2 have a higher rate of increase in resistance with respect to the displacement. In the deformation sensors of Examples A1 and A2, since the sensor thin film is thin, the conductive path easily collapses due to deformation. For this reason, it is considered that the resistance increase rate greatly increased with respect to the increase in the deformation amount. Thus, according to the manufacturing method of the present invention, it is possible to easily manufacture a thin film deformation sensor that is difficult to manufacture by press molding only by applying and curing the sensor paint.

<Example B>
(1) Manufacture of deformation sensor The deformation sensor of the second embodiment (see FIGS. 5 and 6) was manufactured as the first deformation sensor of this example. For the formation of the sensor thin film, the same sensor paint as in Example A2 was used. “Dotite (registered trademark) FA-312” manufactured by Fujikura Kasei Co., Ltd. was used as a conductive paint for electrodes, conductors, and connectors. “FC-HARD UVCF-535G” manufactured by Taiyo Ink Manufacturing Co., Ltd. was used for the insulating film paint. Moreover, the coating material for cover films was prepared as follows.

  100 parts by weight of an acrylic rubber polymer (“Nippol (registered trademark) AR51” manufactured by Nippon Zeon Co., Ltd.), 1 part by weight of stearic acid (“Lunac (registered trademark) S30” manufactured by Kao Corporation), and vulcanization acceleration 2.5 parts by weight of dimethyldithiocarbamate zinc (“Noxeller (registered trademark) PZ” manufactured by Ouchi Shinsei Kagaku), and ferric dimethyldithiocarbamate (“Noxeller TTFE” manufactured by Ouchi Shinsei Chemical) 0.5 Part by weight was mixed with a roll kneader to prepare an elastomer composition. The prepared elastomer composition was dissolved in 312 parts by weight of a printing solvent, ethylene glycol monobutyl ether acetate, to obtain a cover film paint.

  Each paint was screen-printed on the surface of a PET substrate (“Lumirror (registered trademark) S56” manufactured by Toray Industries, Inc., thickness 125 μm). A table slide type semi-automatic printing machine (“SSA-PC660IP” manufactured by Tokai Seiki Co., Ltd.) was used for screen printing.

  Specifically, first, a substrate and a plate were set on a printing machine. After the conductive paint was placed on the plate, a squeegee was scanned on the plate to print electrodes, conductors, and connectors on the surface of the substrate. Thereafter, the substrate was allowed to stand in a drying furnace at about 140 ° C. for about 30 minutes to cure the coating film. In this example, in order to prevent oxidation and corrosion of the electrode and the like, a carbon paint (“Dotite FC-404CA” manufactured by Fujikura Kasei Co., Ltd.) was printed on the surface of the printed electrode and the like in the same manner as described above. After printing, the substrate was allowed to stand in a drying furnace at about 150 ° C. for about 30 minutes to cure the coating film. Subsequently, a base material and a plate on which electrodes and the like were formed were set on a printing machine. After the insulating film paint was placed on the plate, the squeegee was scanned on the plate, and the insulating film was printed on the surface of the substrate excluding the printed electrodes and the like. Then, the base material was put into an ultraviolet (UV) dryer (“GUC-290M” manufactured by Gunsho Co., Ltd.), and the coating film was cured. Next, a base material and a plate on which electrodes and the like were formed were set in a printing machine. After placing the sensor paint on the plate, the squeegee was scanned on the plate, and the sensor thin film was printed on the surface of the printed electrode and insulating film (the length of the coating was about 80 mm, the width was about 5 mm, the thickness was about 100 μm). The substrate was placed in a drying oven and held at about 140 ° C. for 1 hour to primarily cure the coating, and then held at about 160 ° C. for 1 hour to secondarily cure the coating. Finally, the base material and the plate on which the sensor thin film and the like were formed were set on the printing machine. After the cover film paint was placed on the plate, the squeegee was scanned on the plate, and the cover film was printed on the surface of the printed sensor thin film or the like. Thereafter, the substrate was allowed to stand in a drying furnace at about 150 ° C. for about 30 minutes to cure the coating film. The manufactured first deformation sensor was used as the deformation sensor of Example B1.

  On the other hand, the same sensor paint as in Example A2 was screen-printed on a flexible printed circuit board (FPC board) on which electrodes and conductors had been formed in advance (the length of the coating film was about 80 mm, the width was about 5 mm, and the thickness was about 100 μm. ). The printing machine and printing method used are the same as those of the deformation sensor of Example B1. The printed FPC board was placed in a drying furnace and held at about 140 ° C. for 1 hour to primarily cure the coating film, and then held at about 160 ° C. for 1 hour to secondarily cure the coating film. Moreover, the cover film was screen-printed so that the printed sensor thin film might be covered. The printed FPC board was allowed to stand in a drying furnace at about 150 ° C. for about 30 minutes to cure the coating film. The manufactured second deformation sensor was used as the deformation sensor of Example B2.

(2) Evaluation of responsiveness of deformation sensor With respect to the deformation sensors of Examples B1 and B2, changes in electrical resistance with respect to deformation were examined. The electrical resistance was measured in the same manner as in Example A above. The measurement result of the electrical resistance with respect to the deformation in each deformation sensor is shown in FIG. The resistance change rate on the vertical axis in FIG. 9 is the same as the vertical axis in FIG. Moreover, the measurement result of the deformation sensor of the reference example A is also shown in FIG.

  As shown in FIG. 9, in the deformation sensors of Examples B1 and B2, the resistance change rate increased as the displacement amount increased. That is, the electrical resistance increased as the deformation amount of the deformation sensor increased.

  Thus, by forming all the sensor components by the printing method, it is possible to manufacture a deformation sensor that is thin and easy to integrate the sensor components. Further, according to the printing method, the manufacturing process is simplified, and the manufacturing time can be shortened. Therefore, the manufacturing cost can be reduced. Therefore, the printing method is suitable for mass production of deformation sensors.

It is a schematic diagram which shows the conductive path before the load application of the sensor thin film of this invention. It is a schematic diagram which shows the conductive path after the load application of the sensor thin film. It is a front view of the deformation sensor of the first embodiment of the present invention. It is IV-IV sectional drawing of FIG. It is a front view of the deformation sensor of the second embodiment of the present invention. It is VI-VI sectional drawing of FIG. It is a front view of the deformation sensor used in Example A. It is a graph which shows the measurement result of the electrical resistance with respect to a deformation | transformation in each deformation | transformation sensor (Example A). It is a graph which shows the measurement result of the electrical resistance with respect to a deformation | transformation in each deformation | transformation sensor (Example B).

Explanation of symbols

2: Deformation sensor 20: Base material 21: Sensor thin film 22a, 22b: Electrode 23: Insulating film 230: Long hole 24: Cover film 25: Connector 26a, 26b: Conductive wire 27a, 27b: Electrode 28: Insulating film 29a, 29b: Conductor 3: Deformation sensor 30: Base material 31: Sensor thin film 32a, 32b: Electrode 33: Connector 34a, 34b: Conductor 100: Sensor thin film 101: Thermosetting resin 102: Conductive filler P: Conductive path

Claims (9)

It is obtained by applying a sensor coating material in which spherical conductive fillers are dispersed in a liquid resin material whose main component is a pre-curing resin of a thermosetting resin, and curing the coating material on the surface of the substrate,
The thermosetting resin and the conductive filler blended in the thermosetting resin in a substantially single particle state and with a high filling rate, are elastically deformable, and increase the amount of elastic deformation A sensor thin film characterized in that the electrical resistance increases as the   2. The sensor thin film according to claim 1, wherein the thermosetting resin is at least one selected from an epoxy resin, an alkyd resin, a phenol resin, a urea resin, a melamine resin, an unsaturated polyester resin, polyurethane, and polyimide.   3. The sensor thin film according to claim 1, wherein a filling rate of the conductive filler is 30 vol% or more and 65 vol% or less when the entire volume of the sensor thin film is 100 vol%.   4. The sensor thin film according to claim 1, wherein the conductive filler has an average particle size of 0.05 μm to 100 μm.   The sensor thin film according to any one of claims 1 to 4, wherein the film thickness is 10 µm or more and 500 µm or less. It has a thermosetting resin and a spherical conductive filler blended in the thermosetting resin in a substantially single particle state with a high filling rate, is elastically deformable, and increases the amount of elastic deformation A method of manufacturing a sensor thin film in which the electrical resistance increases as
A sensor coating preparation step of preparing a sensor coating by mixing the conductive filler with a liquid resin material mainly composed of a resin before curing of the thermosetting resin;
A curing step of applying the sensor paint to the substrate surface and curing the formed coating film;
A method for producing a sensor thin film, comprising:   The method for producing a sensor thin film according to claim 6, wherein in the curing step, the sensor paint is applied by a printing method. A substrate;
The sensor thin film according to any one of claims 1 to 5 disposed on the surface of the substrate;
An electrode connected to the sensor thin film and capable of outputting electrical resistance;
A deformation sensor comprising: Furthermore, a conductive wire connected to the electrode is provided,
The deformation sensor according to claim 8, wherein the sensor thin film, the electrode, and the conductive wire are formed by a printing method.

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