Electrostatic attraction body and robot hand equipped with same

Abstract

Provided is an electrostatic attractor that has excellent durablity and can more surely attract and hold an object to be attracted by means of electrostatic force.　An electrostatic attractor that has at least a layered sheet that is formed by layering, in order, a first soft high-molecular-weight organic substance, an electrode, and a second soft high-molecular-weight organic substance and a power supply device that applies voltage to the electrode, the electrostatic attractor using the electrostatic force generated by the application of voltage to the electrode to attract and hold an object to be attracted, the surface of contact being at one of the soft high-molecular-weight organic substances. The electrostatic attractor is characterized in that the first soft high-molecular-weight organic substance and / or the second soft high-molecular-weight organic substance has a tensile elasticity of at least 1 MPa but less than 100 MPa and a volume resistivity of 1×108–1013 Ω·cm and in that the electrode is a fibrous structure that has undergone a conduction treatment. A robot hand that comprises the electrostatic attractor.

Description

[Technical Field]

[0001] The present invention relates to an electrostatic attractor capable of attracting and grasping an object by utilizing electrostatic force (hereinafter referred to as "attraction and grasping"), and a robot hand equipped with the same. [Background technology]

[0002] In recent years, new wearable electronic devices have emerged, and there has been a growing trend toward collecting biometric data using various sensors. Furthermore, there is a growing trend toward devices that can be adapted to various objects, not just living bodies (e.g., human skin), but also flexible objects, allowing them to adhere to various targets. Conventional robot grippers use vacuum or mechanical actuators to attract, grasp, and transport objects. However, concerns remain about their susceptibility to damage and deformation, such as crushing, when handling soft objects. Therefore, pads with adhesives or pressure-sensitive adhesives have been considered, particularly for transporting soft objects. However, adhesives and pressure-sensitive adhesives are difficult to attach and detach, and have the disadvantage of being non-reusable. Therefore, electrostatic technologies are increasingly being adopted for their ease of attachment and detachment.

[0003] Electrostatic chucks have been used for adsorbing objects by electrostatic force. Specific dielectric layers (insulators) of electrostatic chucks are preferably made of polyimide film or polyethylene terephthalate (PET) film. However, when electrostatic chucks are used to adsorb soft objects such as living bodies (e.g., human skin), reverse charge is generated on the surface of the electrostatic chuck, which is thought to reduce the adsorption force, although the exact cause is unclear. It has been confirmed that this reverse charge and reduction in adsorption force are more pronounced than when a semiconductor substrate or the like is used.

[0004] Another reason is that conventional electrostatic chucks require a sufficient contact area between the object and the chuck to obtain a sufficient clamping force, and in order to increase the contact area, both the object and the chuck have traditionally been made flat and uniform. However, since the surfaces of soft objects such as living organisms are generally somewhat soft and curved, it has been found that conventional electrostatic chucks only contact a portion of the clamping surface, making it impossible to obtain a sufficient clamping force.

[0005] Furthermore, in addition to the problems of reverse charging and contact area, the so-called Coulomb force, which is the chucking principle of conventional electrostatic chucks, is fundamentally weak (several g / cm 2 ), it is not possible to obtain an effective force that can be used to adsorb to soft objects such as living bodies. Therefore, a different, stronger force, such as the Johnson-Rahbek effect, that occurs at the interface between the chuck surface and the living body is required. Many electrostatic chucks using the Johnson-Rahbek effect have traditionally used ceramics, but there have not been many reports of those using polymeric organic materials that can be expected to have the conformability to ensure a contact area with the object to be adsorbed.

[0006] In response to these conventional problems, the inventors of the present application have conducted extensive research into a means for using electrostatic force to attract soft objects that contain a certain amount of moisture or oil, particularly human skin, and have proposed an attraction pad that uses a resin film with a specific tensile modulus and a specific volume resistivity as its attracting surface for the object (Patent Document 1).Similarly, they have proposed an electrostatic attractor that uses a resin film with a specific tensile modulus and a specific volume resistivity as its attracting surface for highly insulating sheet-like objects such as cloth, and that employs electrodes in a specific arrangement and shape (Patent Document 2). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. WO2019 / 188341 [Patent Document 2] International Publication No. WO2020 / 027246 Summary of the Invention [Problem to be solved by the invention]

[0008] Meanwhile, as a result of further investigation by the inventors of the present application into the suction pad in Patent Document 1 and the electrostatic attractor in Patent Document 2, the following problems were identified with the metal foil specifically employed as the electrode in these suction pads and electrostatic attractors: According to the inventors' investigation, metal foil has a relatively high rigidity and is difficult to deform, and furthermore, has relatively poor bending resistance, which means that creases are easily formed, making it difficult for the foil to conform to the object and reducing the contact area, which raises concerns about a decrease in suction force.

[0009] As a result of further investigations by the present inventors into improvements to the suction pads and electrostatic attractors that had been previously developed, it was discovered that by using a specific fiber composition that had been treated to be conductive as the electrodes, it was possible to provide durability that would eliminate the above-mentioned concerns, and that an effective suction gripping force could be exerted on various soft objects to be attracted, including human skin, and the like, and this led to the completion of the present invention.

[0010] Therefore, an object of the present invention is to provide an electrostatic attractor that utilizes electrostatic force to achieve more durable and reliable attraction and holding of various soft objects, including human skin, than conventional ones, and that is particularly useful in the transportation and automation of fragile objects in the field of logistics. [Means for solving the problem]

[0011] That is, the gist of the present invention is as follows. [1] An electrostatic attractor having at least a laminated sheet in which a first soft organic polymer, an electrode, and a second soft organic polymer are laminated in this order, and a power supply device that applies a voltage to the electrodes, and which attracts and grips an object to be attracted using an electrostatic force generated by applying a voltage to the electrodes, with any one of the soft organic polymers as a contact surface, The first soft organic polymer and / or the second soft organic polymer have a tensile modulus of elasticity of 1 MPa or more and less than 100 MPa and a volume resistivity of 1×10 8 ~10 13 Ω cm, The electrostatic attraction body is characterized in that the electrode is a fiber structure that has been treated to be conductive. [2] The electrostatic adsorption body described in [1], characterized in that the electrode is a cloth made of fibers coated with metal ink or a cloth made of conductive fibers. [3] The electrostatically attracted body has a bending hardness (B) of 0.25 gf cm in pure bending properties measured with a KES-FB2-S testing machine. 2 / cm or more. [4] The electrostatically attracted body has a compression hardness (LC) of 0.16 or less and a compression energy (WC) of 0.03 gf cm / cm in a compression test performed using a KES-FB3-A testing machine. 2 The electrostatic adsorption member according to any one of [1] to [3], characterized in that: [5] An electrostatic adsorption body according to any one of [1] to [4], characterized in that the first soft polymer organic material and / or the second soft polymer organic material are soft polyvinyl chloride and / or polyurethane. [6] The electrostatic attractor according to any one of [1] to [5], characterized in that the object to be attracted is any one or a combination thereof selected from the group consisting of human skin, organs, animal skin, plants, meat and processed meat products, vegetables and processed vegetable products, fruits and processed fruit products, plastic containers, and paper materials. [7] The electrostatic adsorption body according to any one of [1] to [6], wherein the electrode comprises a bipolar electrode having a first electrode and a second electrode. [8] The electrostatic adsorption body according to any one of [1] to [6], wherein the electrode comprises a monopolar electrode. [9] A robot hand comprising the electrostatic adsorption body according to any one of [1] to [8]. [Effects of the Invention]

[0012] The present invention provides superior durability compared to conventional suction pads and electrostatic suction bodies, while further improving the electrostatic suction and holding force. Therefore, it is possible to achieve more reliable suction and holding of various soft objects, including human skin. Furthermore, because chemical adhesives such as glue or pressure-sensitive adhesives are not required, it can be reused. Furthermore, because release films and other adhesives used in these applications are also unnecessary, it is simple and cost-effective. Furthermore, it can be particularly useful in the transportation and automation of fragile objects in the logistics field. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram illustrating one embodiment of a laminate sheet for a positive electrode or a negative electrode, in which (i) is a plan view, (ii) is a cross-sectional explanatory view illustrating the state before lamination in the AA cross section, and (iii) is a cross-sectional explanatory view illustrating the state before lamination in the BB cross section. The white arrows in (ii) and (iii) indicate the adsorption surface for the adsorbate. [Figure 2] FIG. 2 is a cross-sectional view of each of the laminated sheets (electrostatic adsorption bodies) (I) to (III) used in the KES evaluation shown in the examples. [Figure 3] FIG. 3 is a graph showing the results of a pure bending test of each laminate sheet (electrostatically attracted body) shown in FIG. 2 using a KES-FB2-S testing machine. [Figure 4] FIG. 4 is a graph showing the results of a compression test of each laminate sheet (electrostatic attraction body) shown in FIG. 2 using a KES-FB3-A tester. [Figure 5]Figure 5 shows examples of analysis of bending and compression tests in KES evaluation (Source: Kato Tech Co., Ltd.). (i) is used in the KES-FB2-S pure bending test, and (ii) is used in the KES-FB3-A compression test. [Figure 6] 6 is an explanatory diagram for explaining the method for evaluating adsorptive properties shown in the examples. The white arrow in the figure indicates the pulling direction of the force gauge. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described in detail below. As shown in Fig. 1, the electrostatic attraction body of the present invention comprises at least a laminated sheet in which a first soft organic polymer, an electrode, and a second soft organic polymer are laminated in this order, with the electrode sandwiched between the soft organic polymers, and a power supply (not shown) that applies a voltage to the electrode. Each component will be described in detail below.

[0015] <Electrode> The electrodes used in the present invention may be bipolar or unipolar. For example, in the case of a bipolar electrode, multiple laminated sheets (electrostatic attractors) as shown in FIG. 1 are used. The electrodes are made of a conductive fiber structure. The term "fiber structure" here encompasses any thinly processed fiber, whether natural or chemical, and is preferably cloth. The term "cloth" here includes woven or nonwoven fabrics, as well as knitted fabrics and felt. Specifically, it is preferable for the material to conform to the definition of "cloth" in JIS Standard L 0206:1999 Textile Terminology (Textiles Section) No. 1283. As mentioned above, such fiber structures have lower rigidity than conventionally used metal foils and are therefore more easily deformed. However, they also have excellent bending resistance. Therefore, when used with a resin film (described later) to contact (adsorb) an object to be attracted, they are expected to conform to the shape of the object, have a large contact area, and exhibit good conformability.

[0016] Here, the fiber structure can be made conductive by known methods, such as coating a cloth with conductive ink, weaving conductive fibers into a cloth, forming a cloth from fibers of a material containing a conductive substance such as carbon, or weaving a metal thread into a cloth. By using an electrode with a conductively treated fiber structure on the fiber structure, the force of attracting and gripping an object can be improved compared to conventional methods using metal foil. In this case, the electrode's electrical conductivity preferably has a resistivity of 10 Ω·m or less.

[0017] The thickness of the electrode of the present invention having such a configuration is adjusted appropriately depending on the purpose and application of the electrostatic attractor, but is preferably 1 to 200 μm. If the thickness is less than 1 μm, the electrostatic attractor is likely to deform, which may cause the electrode to break or the conductivity to decrease. On the other hand, if the thickness exceeds 200 μm, the electrode tends to become too hard, which may impair the flexibility of the electrostatic attractor as a whole and reduce its ability to follow the object to be attracted.

[0018] Furthermore, since the electrode of the present invention has such a fiber structure, the softness (compression characteristics) and bending characteristics can be evaluated by the following method. That is, the KES system (Kawabata Evaluation System) has been known as a method for objectively evaluating the texture of fabric products, and is performed using a measuring device and a measuring method manufactured by Kato Tech Co., Ltd. Among these, in the present invention, as described in the Examples below, electrostatically attracted bodies using different electrodes are evaluated for the following 1) bending properties and 2) compression properties, and the differences therebetween are confirmed.

[0019] 1) Bending properties The bending properties are measured using a KES-FB2-S pure bending tester manufactured by Kato Tech Co., Ltd. This evaluation makes it possible to measure the hardness and recovery (such as so-called "resilience") of the electrode itself and the electrostatic attraction body of the present invention. As a specific example, a 20cm x 20cm electrode test piece is set in the tester and the maximum curvature is 2.5cm. -1 The relationship between curvature and bending moment is measured when the object is pressed and released under this condition. An example of a graph obtained from this measurement is shown in Figure 3, which is a hysteresis curve. A specific analysis method for this hysteresis curve is shown in Figure 5(i). The "bending stiffness" (B), defined by the slope of the curvature from 0.5 to 1.5 or -0.5 to -1.5, correlates with the softness or stiffness felt by humans when bending an object. The larger the B value, the stiffer the object is, and the smaller the B value, the softer the object is. Furthermore, the "bending recovery" (2HB), defined by the hysteresis (width) at curvatures of 1.0 or -1.0, is the size of the area enclosed by the lines. This correlates with the tactile sensation of recovery (elasticity), which is the force required for an object to return to its original shape after bending. The larger the 2HB value (wider the width), the less recoverable the object is, and the smaller the 2HB value (narrower the width), the more recoverable the object is.

[0020] From the hysteresis curve obtained by this method, it is found that the bending hardness (B) of the electrostatically attracted body using the specified electrode of the present invention is 0.25 gf cm on average (absolute value) for the above bending characteristics (B, 2HB). 2 It is also understood that the bending recovery (2HB) is preferably 0.25 gf·cm / cm or more on average (absolute value). On the other hand, there is no upper limit for B and 2HB, but based on the results of the examples described later, B is 0.40 gf cm on average (absolute value). 2 / cm or less is preferable, and 0.35gf·cm 2 The upper limit of 2HB is preferably 0.40 gf·cm / cm or less, more preferably 0.35 gf·cm / cm or less, on average (absolute value).

[0021] 2) Compression characteristics Compression properties are measured using a KES-FB3-A compression testing machine manufactured by Kato Tech Co., Ltd. This evaluation provides data on the compression stiffness, compression energy, and recovery of fabric products, making it possible to understand properties that affect texture such as "fullness," "slipperyness," and "tension." As a specific example, a 20cm x 20cm electrode test piece is used, and the test piece is placed in a tester with an area of ​​2cm 2 The specimen was sandwiched between steel plates with circular flat surfaces, and the compression speed was 50 sec / mm, with a maximum compression load (pressure) of 50 gf / cm. 2 At that time, the thickness between the steel plates (displacement) is x (mm), and the load (pressure) is y (gf / cm 2 ), and the position of the point where the load (pressure) was detected is set to x = 0, and measurements are taken in the direction of compression. The recovery process is also measured at the same speed. Figure 4 shows an example of a graph obtained from this measurement. A specific analysis method for this graph is shown in Figure 5(ii). Using the areas of the triangles ABC, a + b, and b shown in Figure 5, the characteristics of LC (compression hardness), WC (compression energy), and RC (compression recoverability) are defined by the following equations: The closer LC (compression hardness) is to 1, the harder the fabric is compressed; the smaller it is, the softer it becomes upon initial compression. Furthermore, the higher the WC (compression energy) value, the more easily the fabric is compressed. Furthermore, the closer RC (compression recoverability) is to 100%, the more recoverable it is. For example, regarding compression softness, as determined by sensory evaluation, LC and WC are observed. The softer the fabric is compressed, the easier it is to crush. When LC is small and WC is large, the fabric is softer upon compression. ·LC (compression hardness) = (area of ​​a + b) / (area of ​​triangle ABC) WC (compression energy) = area of ​​a + b RC (compression recovery) = (area of ​​b) / (area of ​​a + b)

[0022] Here, for the electrostatically attracted body of the present invention, it is important to increase the frictional force with the object, and the compression characteristics are also important, with LC (compression hardness) and WC (compression energy) being particularly important. It is believed that increasing flexibility in the compression direction increases the contact area with the object. Regarding the above-mentioned compression characteristics obtained by this method, it is understood that the electrostatically attracted body using the specified electrode of the present invention preferably has a compression hardness (LC) of 0.16 or less on average. A more preferable LC is 0.120 or more and 0.16 or less. Furthermore, it is also preferable that the compression energy (WC) be 0.030 gf·cm / cm on average. 2 It is also understood that it is preferable that the WC is less than 0.015 gf cm / cm. A more preferable WC is 0.015 gf cm / cm. 2 More than 0.030gf cm / cm 2 The following is the result.

[0023] That is, with regard to the compressive properties determined by this method, it was found that the electrostatically attracted body using the predetermined electrode of the present invention had the largest displacement and greatest flexibility in the vertical direction among the bodies evaluated in the Examples. That is, it was understood that the use of the predetermined electrode of the present invention resulted in unique properties, such as greater stiffness in the pure bending test and greater flexibility in the vertical direction, compared to the bodies using other electrodes such as copper foil.

[0024] <Soft polymeric organic matter> The first and second soft polymer organic materials used in the present invention are used so that one or both surfaces thereof are brought into contact with (adsorb onto) an adsorbate. Here, the "soft polymer organic material" may be, for example, a resin film or a cured product obtained by curing a jelly-like (gel-like) polymer organic material, but it is preferable to use a resin film.

[0025] The soft polymer organic material used at least on the contact surface with the object to be adsorbed (also referred to as the adsorption surface; the same applies hereinafter) has a volume resistivity of 1×10 8 ~10 13It is necessary to use a material with a volume resistivity of 1×10 Ω·cm. 13 If the volume resistivity exceeds Ω·cm, the attraction force to the object to be attracted will decrease, and for example, the electrostatic attraction body will be susceptible to the influence of its own weight, and it may not be able to hold the object by attraction, and may fall or peel off. 8 If the volume resistivity is less than Ω·cm, it is expected that the adsorptive force acting on the object to be attracted will be large, but small discharges will occur continuously between the electrostatic attractor and the object to be attracted, which may cause itching or pain when used on the human body, and may damage the skin (object to be attracted), making this undesirable. Preferably, from the standpoint of both the expression of adsorptive force and safety, the volume resistivity should be less than 1×10 10 ~10 12 It is better to have a resistance of Ω·cm. The volume resistivity of the soft organic polymer that is not used on the contact surface with the object to be adsorbed can be set as appropriate, but since there is a risk that the current that should flow between the object to be adsorbed and the soft organic polymer on the contact surface side will flow to the soft organic polymer on the opposite side of the contact surface, it is preferable that the volume resistivity of the soft organic polymer on the opposite side be the same as or greater than the volume resistivity of the soft organic polymer on the contact surface side.

[0026] Furthermore, the tensile modulus (Young's modulus) of at least the soft organic polymer on the contact surface with the object to be attracted must be 1 MPa or more but less than 100 MPa. In particular, when a relatively soft object such as human skin is used as the target, although the detailed principles are unclear, it is necessary to be able to adhere to the shape of the object and to maintain (grasp) the attracted state by minimizing the repulsive force (stress) generated within the electrostatic attractor when attracting the object. To achieve these required characteristics, the tensile modulus (Young's modulus) of at least the soft organic polymer on the contact surface must be within the above-mentioned range. The tensile modulus (Young's modulus) of the soft organic polymer on the opposite side from the contact surface with the object to be attracted can be set as appropriate, but it is preferable that it be within the same tensile modulus (Young's modulus) range or smaller to avoid impairing the flexibility of the entire electrostatic attractor.

[0027] The thickness of each of the first and second soft organic polymer materials can be adjusted appropriately to ensure insulation, adhesion to the object to be attracted, and adhesive force. Preferably, each thickness is 20 to 200 μm. More preferably, each thickness is 50 to 100 μm. If the thickness is less than 20 μm, dielectric breakdown is likely to occur, which may result in pinholes in the resin film, potentially preventing it from functioning as an electrostatic attractant. On the other hand, if the thickness exceeds 200 μm, adhesion to the object to be attracted may be poor, or the distance from the object may increase, potentially reducing adhesive force. Each soft organic polymer material may be used alone or in combination. When multiple materials are used, it is preferable that the total thickness be within the above-mentioned range.

[0028] Specific examples of the above-mentioned soft polymer organic materials when a resin film is used include the first and second resin films, which may be the same or different, and include polyimide, polyethylene terephthalate (PET), nylon, polypropylene, polyurethane, soft polyvinyl chloride, polyvinylidene chloride, etc., or those processed to adjust the conductivity (by mixing in a filler, etc.) In particular, the resin film used on the surface that comes into contact with the object to be adsorbed is preferably polyurethane or soft polyvinyl chloride, more preferably soft polyvinyl chloride, in order to keep the volume resistivity and tensile modulus within the above-mentioned predetermined ranges. Specific examples of cured products obtained by curing jelly-like (gel-like) polymeric organic materials include cured products of ultraviolet-curable liquid silicone rubber (for example, polydimethylsiloxane).

[0029] <Laminated sheet> Then, at least the first and second soft organic polymer materials and the electrodes are laminated to form a laminate sheet. The electrodes must be sandwiched between the soft organic polymer materials so as not to be exposed. A specific method for this is to sandwich the electrodes between the soft organic polymer materials and then apply heat and pressure to fuse them together. Alternatively, bonding may be performed using a bonding sheet, adhesive, or pressure-sensitive adhesive, as needed. However, if a different material is inserted as an adhesive layer when the electrostatically attracted body is deformed or expanded, this may hinder the deformation or expansion or cause peeling of the adhesive surface. Therefore, a more preferable method is to fuse the electrodes together by utilizing the thermoplasticity of the resin film.

[0030] Here, the laminated sheet may be formed by laminating a soft polymer organic material and an electrode, for example, into a flat plate shape, and used as is. Alternatively, the shape may be appropriately modified depending on the state of the object to be attracted. Specifically, if the object to be attracted is sheet-shaped, the electrostatic attractor may also be sheet-shaped or flat. On the other hand, if the object to be attracted has many rounded or angular features that do not provide a sufficient contact surface (contact point), it is preferable to form the electrostatic attractor in a hand-like shape so that it can grip or embrace the object to be attracted. This is thought to ensure a sufficient contact surface (contact point) and to effectively exert the attraction and holding force by utilizing the flexibility (shape-conforming ability) of the electrostatic attractor.

[0031] The overall thickness of the laminate sheet can be adjusted appropriately depending on the object to be attracted, but it is preferably about 40 μm to 1000 μm. If the laminate sheet is too thin, it is expected that flexibility and shape conformability will be improved, but there is a risk of it being damaged by excessive bending. Furthermore, if the thickness is too thick, it may affect the compression characteristics of the laminate sheet or increase its hardness (bending hardness), which may hinder the flexibility of the entire electrostatic attractor.

[0032] Furthermore, it is preferable that the laminated sheet have fine irregularities on the surface that comes into contact with the object to be adsorbed (the contact surface of the soft organic polymer). The soft organic polymer and the fiber structure serving as the electrode are both soft, and it has been confirmed that when they are laminated together, fine irregularities occur on the surface of the soft organic polymer. It is presumed that when the adsorption surface adheres to the object to be adsorbed, the adsorption surface deforms, providing an effect similar to that of multiple suction cups. To provide such fine irregularities on the soft organic polymer, the surface condition of the soft organic polymer itself can be changed (e.g., processed), but preferably, as described above, the contact surface of the soft organic polymer has fine irregularities in combination with the surface irregularities of the fiber structure used as the electrode.

[0033] <Power supply> After forming the laminated sheet as described above, a power supply is required to apply a voltage to the electrodes to generate an electrostatic force. The power supply can be connected to the electrodes of the laminated sheet via connection terminals and switches (neither of which is shown), and can be similar to those used in general electrostatic adsorption structures, as long as it can generate a high DC voltage. The potential difference to be generated can be about 500 to 5000 V, and if necessary, a booster circuit (high voltage generating circuit) that can boost the voltage to a desired voltage may be provided. In particular, in order to apply the electrostatic adsorption body of the present invention to human skin, it is preferable to design it taking into consideration the following (1) to (3). That is, (1) Apply as high a voltage as possible to generate sufficient adsorption force. (2) The potential of the human body should be kept as close to 0V as possible. If the potential on the human body is biased towards either positive or negative, static electricity will accumulate inside the body, causing a shock when it is discharged. (3) Ensure that no current flows that is dangerous to the human body.

[0034] Based on the design concepts (1) to (3), it is preferable to determine the voltage to be applied to the electrostatic attraction body, taking into consideration (2) and (3) in particular. To achieve (2), when a monopolar electrode layer is used, it is preferable to connect the object to be attracted (human skin) and the ground of the voltage source (e.g., a high-voltage generating circuit) in the power supply device to earth (ground). On the other hand, when a bipolar electrode layer is used, it is preferable to apply symmetrical positive and negative voltages to the first and second electrodes of the electrode layer, respectively, so that the human body is preferably at 0 V as much as possible. Furthermore, to achieve (3), it is preferable to limit the output current from the power supply to 0.5 mA or less. This is because a current of 0.5 mA or less is usually imperceptible to the human body. However, a large current may be generated if the current is stored in the electrostatic attraction body or the human body and then suddenly discharged. Therefore, it is preferable to set the capacitance of the electrostatic attraction body to 1000 pF or less, which is similar to that of the human body, specifically, 10 pF to 100 pF, and to set the voltage within ±5000 V, so that even if current is stored in the human body, it will be 5 μC or less.

[0035] The electrostatic attractor of the present invention is provided with the laminated sheet and a power supply device as described above. The electrostatic attractor of the present invention may be provided with a separate sensor or the like as needed, and the configuration may be appropriately modified or added within the scope of the object of the present invention, for example, by changing the electrode pattern.

[0036] In the present invention, the object to be attracted can be not only a conductor, but also paper, cloth, etc., which have poor electrical conductivity. In particular, it can be human skin or any object that has a softness comparable to that of human skin and has a certain surface that can be contacted and attracted by the electrostatic attractor, such as organs, animal skin, plants, meat and processed meat products, vegetables and processed vegetable products, fruits and processed fruit products, plastic containers such as packs, trays, bottles for food and packaging, and paper materials such as cardboard. Alternatively, combinations of these can also be targeted. The object to be attracted has a volume resistivity of 1012 ~10 14 It is particularly targeted at objects with a resistance of about Ω·cm. Although the detailed principle of this type of attraction is not clear, it is presumed that a minute current is generated between the attraction surface of the electrostatic attraction body (laminated sheet) and the object to be attracted, and that an attraction force due to the Johnsen-Rahbek effect is acting between the attraction surface of the electrostatic attraction body (laminated sheet) and the object to be attracted.

[0037] The electrostatic adsorption body and laminated sheet of the present invention can also be suitably used in the fields of logistics and transportation, and can be incorporated into, for example, robot hands and other devices and equipment for transportation and gripping. [Example]

[0038] Preferred embodiments of the present invention will be specifically described below based on examples and comparative examples, but the present invention should not be construed as being limited thereto.

[0039] <Preparation of electrostatically attracted body> [Example 1] First, an aluminum-coated fabric (product name: Alink, obtained from Alink Co., Ltd. (Address: #6401, 797 Changdaero, Seongsangu, Changwon, Gyeongnam, Korea; website: http: / / www.alink21.com), width: 35 mm, length: 119 mm, thickness: 130 μm) with the shape shown in Figure 1 was prepared as an electrode. Next, two adhesive layers (product name: MPD62, manufactured by Bikan Imaging Co., Ltd., width: 40 mm, length: 123 mm, thickness: 25 μm) with the same width and length as the electrode were prepared and placed on the top and bottom surfaces of the electrode. Then, two soft polyvinyl chloride resin films c and c' (both with a volume resistivity of 1 × 10) were placed on the top and bottom adhesive layers. 10 The laminated sheet a was prepared by sandwiching the two sheets of the laminated sheet a between layers of the same material (Ω·cm (measured using the method described below), tensile modulus (Young's modulus): 20-30 MPa, and film thickness: 100 μm) and pressing them together (Figure 1). Two laminated sheets a were prepared as the positive and negative electrodes.

[0040] A power supply device for applying voltage to the produced laminate sheet a was prepared as follows. First, a voltage-resistant cable with a connector (product name: 03-103723, manufactured by VONA) was soldered to a copper foil tape (not shown), and the copper foil tape was attached to the ends of the electrodes and insulated with insulating tape. Next, the connector parts were connected to the positive and negative electrodes of a power supply device (not shown) [a power supply device consisting of a high-voltage generator (±2000V output) and a 24V power supply cable] to form the electrostatically attracted bodies (positive and negative electrodes) of Example 1.

[0041] [Comparative Example 1] Two electrostatic attractors connected to a positive electrode and a negative electrode were produced in the same manner as in Example 1, except that copper foils (thickness: 18 μm) having approximately the same width and length as the electrodes in Example 1 were used as the electrodes (electrostatic attractors according to Comparative Example 1).

[0042] <Evaluation of the adsorptive properties of electrostatically adsorbed materials> The experiment was carried out using the configuration shown in FIG. 1. Two of each electrostatically attracted body (positive electrode, negative electrode) prepared above were attached and fixed to a PVC plate (contact insulation) measuring W 84 mm x L 135 mm. 2. Next, a 120 mm square silicon plate was fixed to a temperature control device, and the temperature was set to 25°C, and the humidity in the chamber (an acrylic box capable of controlling humidity and target temperature) was set to 50%. A PVC plate with an electrostatic attractor was hung on the hook of the force gauge, and the PVC plate was placed on top of the silicon plate so that the electrostatic attractor was in contact with the silicon plate (contact area W 70 mm × L 109 mm). The electrostatic attractant and the silicon plate were left as they were for a while until the temperature and humidity of the electrostatic attractant and the silicon plate became constant. 3. Set the force gauge to the MAX value (PEAK value) mode and reset it to "0". Start applying voltage from the power supply (±2kV), and after 10 seconds, pull the force gauge 30mm in the direction of the arrow in the figure at a speed of 1mm / s. 4. The maximum value was recorded. The same procedure was repeated 20 times. 5. The procedure of 3. was repeated without applying voltage (number of repetitions: 20 times).

[0043] The procedures 1 to 5 were carried out for the electrostatic adsorbent of Example 1 and the electrostatic adsorbent of Comparative Example 1, and the average value of the obtained measured values (average value of 20 times) was taken as the adsorption force of each electrostatic adsorbent. The results are shown in Table 1.

[0044]

Table 1

[0045] <Evaluation by KES system> Regarding the evaluation by the KES system, it was entrusted to an external testing institution [Kanagawa Prefectural Institute of Industrial Technology (KISTEC)], and 1) KES-FB2-S pure bending test and 2) KES-FB3-A compression test were carried out respectively. Samples (I) to (III) shown in Fig. 2 were used. (I) had a copper foil (thickness 18 μm) as the electrode, (II) had the same Alink as above as the electrode, and (III) had only a PVC tape without using an electrode. In Fig. 2, "PVC tape" was denoted as "PVC". "MPD62" and "PVC" (PVC tape) in Fig. 2 represent the above-mentioned adhesive layer MPD62 and the resin film made of soft polyvinyl chloride respectively.

[0046] [[ID=2३]] The obtained result graphs are shown in Figs. 3 and 4 respectively, and the analysis method is shown in Fig. 5. In Fig. 3, the horizontal axis (X) represents "curvature", and the vertical axis (Y) represents "bending moment". In Fig. 4, the horizontal axis (X) represents "thickness" (displacement), and the vertical axis (Y) represents "pressure". In Fig. 4, although the appearance positions of the graph lines (I) to (III) on the horizontal axis (X-axis) are different, this difference is due to the difference in the distance from the compression sensor to the sample surface and has no particular significance. It can be adjusted in the initial settings during measurement (for example, the height of the sensor, etc.). Table 2 also shows the B (bending hardness) and 2HB (bending recovery) in the KES-FB2-S pure bending test, and the LC (compression hardness), WC (compression energy), and RC (compression recovery) in the KES-FB3-A compression test. The test conditions for each are as follows: 1) KES-FB2-S pure bending test Sensitivity: Standard Direction: WARP Number of repetitions: 1 SENS: 2×1 Measurement cycle: 1 cycle Sample width: 20cm ·Maximum curvature: 2.5 1 / cm 2) KES-FB3-A compression test Sensitivity: Standard Number of repetitions: 1 SENS: 2×5 ·Speed: 50sec / mm Capture interval: Standard Sample width: 20cm Maximum load (pressure): 50gf / cm 2

[0047] [Table 2]

[0048] From the results in Table 2, the electrostatically attracted body of the present invention (II above) using the specified electrodes has a bending hardness (B) of 0.25 gf cm in the pure bending test of KES-FB2-S. 2 / cm or more, and the bending recovery (2HB) is 0.25 gf·cm / cm or more. In addition, in the KES-FB3-A compression test, the compression hardness (LC) is 0.16 or less, and the compression energy (WC) is 0.030 gf·cm / cm 2 It turns out that the following is true. [Explanation of symbols]

[0049] a...Laminated sheet, a'...Electrostatic attracting body, b...Electrode, c... 1a'...second soft polymer organic material, c'...insulating sealing tape, e...power cable, f...force gauge, g...PVC plate, h...silicon plate, i...temperature control device, j...forward path (direction), k...return path (direction).

Claims

1. An electrostatic attractor includes a laminated sheet in which at least a first soft organic polymer material, an electrode, and a second soft organic polymer material are laminated in this order, and a power supply device that applies a voltage to the electrodes, and attracts and grips an object to be attracted, with any one of the soft organic polymer materials as a contact surface, using an electrostatic force generated by applying a voltage to the electrodes, The first soft organic polymer and / or the second soft organic polymer have a tensile modulus of elasticity of 1 MPa or more and less than 100 MPa and a volume resistivity of 1×10 ８ ~10 １３ Ω cm, The electrostatic attractor is characterized in that the electrode is a cloth made of fibers coated with metal ink or a cloth made of conductive fibers.

2. The electrostatically attracted body has a bending hardness (B) of 0.25 gf cm in pure bending properties measured with a KES-FB2-S testing machine. ２ 2. The electrostatic attractant according to claim 1, wherein the surface roughness is 1 / cm or more.

3. The electrostatically attracted body has a compression hardness (LC) of 0.16 or less and a compression energy (WC) of 0.03 gf cm / cm in a compression test measured using a KES-FB3-A tester. ２ 3. The electrostatic attractor according to claim 1, wherein:

4. 4. The electrostatic adsorptive body according to claim 1, wherein the first soft organic polymer and / or the second soft organic polymer is soft polyvinyl chloride and / or polyurethane.

5. 5. The electrostatic attractor according to claim 1, wherein the object to be attracted is any one or a combination thereof selected from the group consisting of human skin, organs, animal skin, plants, meat and processed meat products, vegetables and processed vegetable products, fruits and processed fruit products, plastic containers, and paper materials.

6. 6. The electrostatic attractor according to claim 1, wherein the electrode comprises a bipolar electrode having a first electrode and a second electrode.

7. 6. The electrostatic attractor according to claim 1, wherein the electrode comprises a monopolar electrode.

8. A robot hand comprising the electrostatic attractor according to any one of claims 1 to 7.

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