Electrostatic adsorber and robot arm provided with the same

Abstract

This invention provides an electrostatic attractor with excellent durability and the ability to reliably attract and hold objects using electrostatic force. An electrostatic attractor and a robotic arm equipped with the attractor are also provided. The electrostatic attractor comprises a laminate containing at least a first soft polymer organic material, an electrode, and a second soft polymer organic material stacked sequentially, and a power supply device for applying voltage to the electrodes. The electrostatic force generated by applying voltage to the electrodes allows the soft polymer organic material to act as a contact surface for attracting and holding the object. The tensile elastic modulus of the first and / or second soft polymer organic materials is 1 MPa or more but less than 100 MPa, and the volume resistivity is 1 × 10⁻⁶. 8 Ω·cm~1×10 13 Ω·cm, the electrode is a conductive fiber structure.

Description

Technical Field

[0001] The present invention relates to an electrostatic attractor capable of attracting and holding (hereinafter sometimes referred to as "attracting and holding") an object by means of electrostatic force, and a robotic arm having said attractor. Background Technology

[0002] In recent years, new wearable electrical products have been continuously launched, increasing the opportunities to collect data from living organisms through various sensors. Furthermore, these products exhibit excellent tracking capabilities not only on living organisms (such as human skin) but also on soft objects, easily adapting to different objects and increasing the potential for unfolding the gripped object into various shapes. Previously, robotic grippers used vacuum or mechanical actuators to grip, hold, and transport objects, but these could easily damage soft objects, raising concerns about deformation such as flattening. Therefore, especially in applications involving the handling of soft objects, pads with adhesive or bonding components could be considered. However, using adhesives or bonding agents presents disadvantages such as time-consuming assembly and disassembly, and the inability to reuse them. Therefore, the adoption of electrostatic technologies is being promoted to improve ease of assembly and disassembly.

[0003] However, electrostatic chucks have always been used to attract objects by electrostatic force. Polyimide film or polyethylene terephthalate (PET) film is preferably used as the dielectric layer (insulator) of the electrostatic chuck. However, when attracting soft objects such as living organisms (e.g., human skin), although the exact reason is not determined, it is speculated that the attraction force is reduced due to the generation of back charge on the surface of the electrostatic chuck. It has been confirmed that compared to using semiconductor substrates, the generation of back charge and the attraction force are significantly reduced.

[0004] Furthermore, for other reasons, in previous electrostatic chucks, a sufficient contact area between the object and the chuck was required to obtain adequate attraction. To increase the contact area, both the object side and the chuck side have been made flat and uniform. In this regard, the surfaces of soft objects such as living organisms are usually somewhat soft and curved. Therefore, it is known that in existing electrostatic chucks, only a portion of the attraction surface is in contact, thus failing to obtain sufficient attraction.

[0005] Furthermore, not only are there issues with anti-charge or contact area, but the existing electrostatic chuck's adsorption principle, namely the so-called Coulomb force, is inherently weak (several g / cm²), making it impossible to obtain an effective force for adsorbing soft objects such as living organisms. Therefore, stronger forces, such as the Johnsen-Rahbek effect, generated at the interface between the chuck surface and the living organism, are needed. While ceramic chucks have historically been used for electrostatic chucks utilizing the Johnsen-Rahbek effect, there have been almost no reports to date of chucks made of polymeric organic materials that can ensure such a consistent contact area with the adsorbed object.

[0006] In response to previous issues, the inventors of this application have diligently researched methods for using electrostatic force to attract soft, moist, or oily materials, particularly human skin, and have proposed an attraction pad that uses a resin film with a specific tensile modulus and volume resistivity as the attraction surface (Patent Document 1). Similarly, for sheet-like materials with high insulation properties, such as cloth, a resin film with a specific tensile modulus and volume resistivity is also used as the attraction surface, and an electrostatic attractant employing an electrode configuration or shape is proposed (Patent Document 2).

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: International Publication No. WO2019 / 188341

[0010] Patent Document 2: International Publication No. WO2020 / 027246 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] However, regarding the adhesive pad in Patent Document 1 and the electrostatic attractant in Patent Document 2, the inventors of this application conducted further research and confirmed the following problems with the metal foil specifically used as the electrode in these adhesive pads or electrostatic attractants. Specifically, according to the inventors' verification, the metal foil has high rigidity, is difficult to deform, and has poor bending resistance, thus easily producing creases and making it difficult to adapt to the object, reducing the contact area and raising concerns about reduced adhesion.

[0013] Therefore, the inventors of this application conducted further research on improvements to this previously developed adhesive pad or electrostatic adhesive, and found that by using a specified fiber structure treated with conductivity as an electrode, it is possible to achieve durability that eliminates the aforementioned concerns, and to exert effective adhesive grip on various soft objects, including human skin, thereby completing the present invention.

[0014] Therefore, the object of the present invention is to provide an electrostatic attractor that utilizes electrostatic force to attract various soft objects, including human skin, with better durability than before, achieving more reliable attraction and retention, which is helpful for the transportation or automation of items that are easily damaged, especially in logistics areas.

[0015] Technical means to solve the problem

[0016] That is, the main idea of ​​this invention is as follows.

[0017] [1] An electrostatic attractor includes: a laminated sheet having at least a first soft polymer organic material, an electrode, and a second soft polymer organic material stacked sequentially; and a power supply device for applying a voltage to the electrode; and using the electrostatic force generated by applying the voltage to the electrode to make the soft polymer organic material serve as a contact surface to attract and hold an object, wherein...

[0018] The tensile elastic modulus of the first and / or second soft polymer organic materials is greater than 1 MPa and less than 100 MPa, and the volume resistivity is 1×10⁸ Ω·cm to 1×10¹³ Ω·cm.

[0019] The electrode is a conductive fiber structure.

[0020] [2] According to the electrostatic attractant of [1], wherein the electrode is a cloth containing fibers coated with metallic ink or a cloth containing conductive fibers.

[0021] [3] According to [1] or [2], wherein the bending hardness (B) of the pure bending characteristics of the electrostatic attractor, as measured by the KES-FB2-S tester, is 0.25 gf·cm2 / cm or more.

[0022] [4] An electrostatic attractor according to any one of [1] to [3], wherein, in a compression test measured by a KES-FB3-A testing machine, the compression hardness (LC) is 0.16 or less and the compression energy (WC) is 0.03 gf·cm / cm2 or less.

[0023] [5] The electrostatic attractant according to any one of [1] to [4], wherein the first soft polymer organic material and / or the second soft polymer organic material is soft polyvinyl chloride and / or polyurethane.

[0024] [6] An electrostatic attractant according to any one of [1] to [5], wherein the attractant is any one or a combination thereof selected from the group consisting of human skin, organs, animal skin, plants, meat and meat products, vegetables and vegetable products, fruits and fruit products, plastic containers and paper materials.

[0025] [7] The electrostatic attractant according to any one of [1] to [6], wherein the electrode comprises a bipolar electrode having a first electrode and a second electrode.

[0026] [8] An electrostatic attractor according to any one of [1] to [6], wherein the electrode comprises a unipolar electrode.

[0027] [9] A robotic arm comprising an electrostatic attractor according to any one of [1] to [8].

[0028] The effects of the invention

[0029] According to the present invention, compared with previous adhesive pads or electrostatic adhesives, the durability is superior, and the electrostatic-based adhesion and holding force can be further improved. Therefore, more reliable adhesion and holding can be achieved for various soft objects, including human skin. Moreover, since it can be reused without the need for chemical bonding components such as adhesives or bonding agents, and also without the need for release films or the like for these chemical bonding components, it is simple and cost-effective. Furthermore, it is particularly helpful for the handling or automation of fragile items in the logistics field. Attached Figure Description

[0030] Figure 1 This is a schematic diagram illustrating one configuration of a laminated sheet for a positive or negative electrode. Figure 1 (i) is a plan view. Figure 1 (ii) is a cross-sectional diagram illustrating the state before stacking on section AA. Figure 1 (iii) is a cross-sectional diagram illustrating the state before stacking on the BB section. Figure 1 (ii) and Figure 1 The white arrow in (iii) indicates the adsorption surface of the object being adsorbed.

[0031] Figure 2 This is a schematic cross-sectional view of each of the stacked sheets (electrostatic adsorbents) (I) to (III) used for KES evaluation as shown in the embodiment.

[0032] Figure 3 This indicates that the KES-FB2-S testing machine was used for... Figure 2 The chart shows the results of pure bending tests performed on each of the stacked layers (electrostatic attractants).

[0033] Figure 4 This indicates that the KES-FB3-A testing machine was used for... Figure 2 The chart shows the results of compression tests conducted on each of the stacked layers (electrostatic attractants).

[0034] Figure 5 This is a graph showing the analysis examples of each test in the bending and compression tests in the KES evaluation (Source: Kato-tech Co., Ltd.). Figure 5 (i) is used in the KES-FB2-S pure bending test. Figure 5 (ii) is used in the KES-FB3-A compression test.

[0035] Figure 6 This is an explanatory diagram illustrating the method for evaluating adhesion shown in the embodiments. The white arrows in the diagram indicate the stretching direction of the force gauge.

[0036] [Explanation of Symbols]

[0037] a: laminated sheet

[0038] a': Electrostatic attractant

[0039] b: Electrode

[0040] c: First soft polymer organic matter

[0041] c': Second soft high-molecular-weight organic compound

[0042] d: Insulating sealing tape

[0043] e: Power cable

[0044] f: Force gauge

[0045] g: PVC board

[0046] h: silicon plate

[0047] i: Temperature control device

[0048] j: route (direction)

[0049] k: Loop (direction) Detailed Implementation

[0050] The present invention will now be described in detail.

[0051] like Figure 1As shown, the electrostatic attractor of the present invention includes at least: a laminated sheet, wherein a first soft polymer organic material, an electrode, and a second soft polymer organic material are sequentially laminated, and the electrode is sandwiched within the soft polymer organic material; and a power supply device (not shown) for applying a voltage to the electrode layer. The structures are described in detail below.

[0052] <Electrode>

[0053] The electrodes used in this invention can be either bipolar or unipolar. For example, in the case of bipolar electrodes, multiple electrodes are used. Figure 1 The laminated sheet (electrostatic attractor) shown is used. Furthermore, the electrodes utilize a fibrous structure that imparts conductivity. Here, "fibrous structure" is not limited to natural or chemical fibers, but includes any type of fiber that has been thinned, and is preferably made of cloth. Here, "cloth" is not limited to woven or non-woven fabrics, and may also include woven fabrics, felt, etc. Specifically, it is preferably defined as "cloth" according to Japanese Industrial Standards (JIS) L 0206:1999, Fiber Terminology (Textiles Section) No. 1283. As described above, this type of fibrous structure has lower rigidity than previously used metal foils, making it easier to deform and exhibiting excellent flexibility. Therefore, it is presumed that when used in conjunction with the resin film described later to contact (adhere to) the object being attracted, it exhibits excellent conformability to the shape of the object being attracted, good contact area, and good adaptability.

[0054] Here, as a conductive treatment of the aforementioned fibrous structure, known methods can be employed. Examples include: coating a cloth with conductive ink; weaving conductive fibers into a cloth; forming a cloth by making a material containing conductive substances such as carbon into fibers; and weaving metal wires as fibers to form a cloth. By using electrodes with a structure that has undergone conductive treatment of the fibrous structure, the force for adsorbing and holding the object can be improved compared to the previous use of metal foils. Regarding the conductivity of the electrode in this case, the resistivity is preferably 10 Ω·m or less.

[0055] Regarding the thickness of the electrode of the present invention having this structure, it can be appropriately adjusted according to the purpose or application of using the electrostatic attractant, but it is preferably set to 1 μm to 200 μm. When the thickness is less than 1 μm, the electrostatic attractant is prone to deformation, which may cause electrode breakage or reduced conductivity. On the other hand, when the thickness exceeds 200 μm, the electrode tends to become harder, which may hinder the overall flexibility of the electrostatic attractant and result in a lack of followability to the attracted object.

[0056] Furthermore, since the electrodes of the present invention are of this type of fibrous structure, their softness (compression characteristics) or bending characteristics can be evaluated by the following methods.

[0057] That is, as an objective method for evaluating the feel of fabric products, the KES system (Kawabata Evaluation System) is previously known, which uses measuring equipment and methods manufactured by Kato Tech Co., Ltd. In this invention, as described in the embodiments described later, the following evaluations were performed on electrostatic attractants using different electrodes, specifically evaluating their 1) bending characteristics and 2) compression characteristics, and confirming these differences.

[0058] 1) Bending characteristics

[0059] The bending characteristics were measured using a KES-FB2-S pure bending tester manufactured by Kato Tech Co., Ltd. Through this evaluation, the hardness or resilience (so-called "toughness," strength, etc.) of the electrode itself or the electrostatic adsorbent of the present invention can be measured.

[0060] As a specific example, a 20cm × 20cm electrode test piece was fabricated and placed on a testing machine, with a maximum curvature of 2.5cm. -1 Under these conditions, the relationship between curvature and bending moment during pressing and returning was measured. An example of a graph obtained from these measurements is shown below. Figure 3 The figure shown is obtained as a hysteresis curve. The specific analysis method for the hysteresis curve is shown below. Figure 5 (i) "Bending stiffness" (B), defined by a slope with a curvature of 0.5 to 1.5 or -0.5 to -1.5, is related to the softness and stiffness felt by a person when bending an object. A larger B value indicates greater bending stiffness, while a smaller B value indicates greater softness. Additionally, "bending resilience" (2HB), defined by a hysteresis (width) with a curvature of 1.0 or -1.0, is the size of the area enclosed by the line. This can be understood as being related to the force required for a person to recover after bending the object—the tactile sensation of resilience (elasticity). A larger 2HB value (wider width) indicates less resilience, while a smaller 2HB value (narrower width) indicates more resilience.

[0061] Furthermore, based on the hysteresis curve obtained by this method, it is understood that the bending stiffness (B) of the electrostatic attractor using the specified electrode according to the present invention, in terms of average value (absolute value), is preferably 0.25 gf·cm. 2 / cm or more. Furthermore, it is understood that the bending recovery (2HB), in terms of average value (absolute value), is preferably 0.25 gf·cm / cm or more.

[0062] On the other hand, there is no upper limit to these values ​​of B and 2HB, but based on the results of the embodiments described later, B is preferably 0.40 gf·cm³ in terms of average value (absolute value). 2 / cm or less, more preferably 0.35gf·cm 2 / cm or less. In addition, the upper limit of 2HB, in terms of average value (absolute value), is preferably 0.40 gf·cm / cm or less, and more preferably 0.35 gf·cm / cm or less.

[0063] 2) Compression characteristics

[0064] Compression characteristics were measured using a KES-FB3-A compression testing machine manufactured by Kato Tech Co., Ltd. This evaluation provides data on the compressive stiffness, compressive energy, and resilience of fabrics and other products, revealing properties such as "expansion," "smoothness," and "elasticity" that affect hand feel.

[0065] As a specific example, an electrode test piece of 20cm × 20cm is made and clamped in a testing machine, having an area of ​​2cm². 2 Between circular flat steel plates, at a compression speed of 50 sec / mm and a maximum compression load (pressure) of 50 gf / cm². 2 Compression is then performed. At this point, the thickness (displacement) between the steel plates is set as x (mm), and the load (pressure) is set as y (gf / cm²). 2 The location of the point where the load (pressure) is detected is set to x = 0, and measurements are taken in the compression direction. The recovery process is also measured at the same rate. An example of a graph obtained through these measurements is shown below. Figure 4 The specific analysis method for the aforementioned charts is shown below. Figure 5 (ii) using Figure 5 The areas of triangle ABC, region a+b, and region b, as described in the text, are defined by the following formulas to represent the characteristics of LC (compression stiffness), WC (compression energy), and RC (compression recovery). The closer LC (compression stiffness) is to 1, the greater the compression stiffness; the smaller the LC, the greater the initial compressibility. Furthermore, the larger the WC (compression energy) value, the more easily the fabric can be compressed. Moreover, it can be observed that the closer RC (compression recovery) is to 100%, the greater the recovery. For example, regarding compressibility as perceived through sensory evaluation, it can be observed that the higher the LC and WC values, the easier the fabric is to flatten; a smaller LC and a larger WC value indicate greater compressibility.

[0066] • LC (compression stiffness) = (area of ​​a + b) / (area of ​​triangle ABC)

[0067] • WC (compression energy) = area of ​​a + b

[0068] • RC (Compressibility Resilience) = (Area of ​​b) / (Area of ​​a + b)

[0069] Here, in the electrostatic attractor of the present invention, increasing the frictional force with the object becomes important, and so do the compression characteristics, particularly LC (compression hardness) and WC (compression energy). This is believed to be because increasing the flexibility in the compression direction increases the contact area with the object. Furthermore, regarding the compression characteristics obtained by this method, it is understood that the compression hardness (LC) of the electrostatic attractor using the specified electrodes of the present invention is preferably 0.16 or less on average. More preferably, LC is 0.120 or more and 0.16 or less. Additionally, it is understood that the compression energy (WC) is preferably 0.030 gf·cm / cm on average. 2 The following is a preferred WC value: 0.015 gf·cm / cm. 2 Above and 0.030 gf·cm / cm 2 the following.

[0070] That is, regarding the compression characteristics obtained by this method, it can be seen that the electrostatic attractant using the specified electrode of the present invention has the largest displacement and the greatest flexibility in the vertical direction among the electrostatic attractants evaluated in the examples. In other words, it is understood that by using the specified electrode of the present invention, compared with the case where other copper foils or the like are used as electrodes, it has the unique characteristics of strong "toughness" and high flexibility in the vertical direction in the pure bending test.

[0071] <Soft high molecular weight organic matter>

[0072] The first and second soft polymer organic materials used in this invention are used in such a way that one or both of their surfaces contact (adsorb) the adsorbed object. Here, the "soft polymer organic material" may be, for example, a resin film or a hardened material formed by curing a gel-like polymer organic material, but a resin film is preferred.

[0073] Furthermore, at least the soft polymeric organic materials used for the contact surface (also called the adsorption surface, hereinafter the same) of the adsorbed object need to have a volume resistivity of 1×10⁻⁶. 8 ~1×10 13 The volume resistivity of the soft polymer organic material at the contact surface exceeds 1×10 Ω·cm. 13 At a volume resistivity of Ω·cm, the attraction to the attracted object decreases; for example, it becomes more susceptible to the weight of the electrostatically attracted object itself, making it unable to maintain adhesion and potentially causing it to fall off or peel off. On the other hand, the volume resistivity is less than 1×10⁻⁶. 8At a volume resistivity of Ω·cm, it is presumed that the attraction force acting on the attracted object increases. However, continuous small discharges occur between the electrostatic attractor and the attracted object, which, especially in applications involving the human body, can cause itching or pain, potentially damaging the skin (the attracted object). Therefore, this is not preferred. Considering both attraction force performance and safety, a volume resistivity of 1×10⁻⁶ is preferred. 10 ~1×10 12 Ω·cm.

[0074] Furthermore, for soft polymer organic materials not used for contact with the adsorbed object, their volume resistivity can be appropriately set. However, it is possible that the current that should flow from the soft polymer organic material on the contact surface side to the adsorbed object may flow to the soft polymer organic material side opposite to the contact surface. Therefore, the volume resistivity of the soft polymer organic material on the opposite side is preferably equal to or greater than the volume resistivity of the soft polymer organic material on the contact surface side.

[0075] Furthermore, at least for the soft polymeric organic material in contact with the object being attracted, its tensile modulus (Young's modulus) must be set to 1 MPa or more but less than 100 MPa. Especially when using relatively soft objects such as human skin as the object being attracted, although the detailed principle is not yet determined, it is required that the material can follow the shape of the object being attracted and that, when attracted to the object, the repulsive force (stress) generated within the electrostatic attractor body can be suppressed as much as possible to maintain (hold) the attracted state. Due to these requirements, the tensile modulus (Young's modulus) of the soft polymeric organic material on the contact side is set to the aforementioned range. Furthermore, for the soft polymeric organic material on the side opposite to the contact side with the object being attracted, its tensile modulus (Young's modulus) can be appropriately set, but in order not to hinder the overall softness of the electrostatic attractor body, it is preferable to have the same tensile modulus (Young's modulus) as described above, or a smaller one.

[0076] Furthermore, regarding the aforementioned soft polymer organic materials, in order to ensure insulation, the ability to follow the adsorption of the object, and the adsorption force, the thickness of both the first and second soft polymer organic materials can be appropriately adjusted, preferably with each thickness set to 20 μm to 200 μm. More preferably, each thickness can be set to 50 μm to 100 μm. When the thickness is less than 20 μm, dielectric breakdown is easily caused, and if pinholes are formed on the resin film, it may no longer function as an electrostatic attractant. On the other hand, when it exceeds 200 μm, the ability to follow the adsorption of the object deteriorates, or the distance relative to the object increases, thereby potentially reducing the adsorption force. In addition, each soft polymer organic material can be used alone or in combination. Even in the case of multiple materials, it is preferable that the total thickness is within the aforementioned range.

[0077] Furthermore, as a specific example of using a resin film in a soft polymer organic material as described above, the first resin film and the second resin film may be the same or different. Examples include polyimide, polyethylene terephthalate (PET), nylon, polypropylene, polyurethane, soft polyvinyl chloride, polyvinylidene chloride, etc., or those processed (mixed with fillers, etc.) to adjust their conductivity. In particular, regarding the resin film used in the contact surface with the adsorbed object, in order to set the volume resistivity and tensile modulus of elasticity within the specified range, polyurethane or soft polyvinyl chloride is preferred, and soft polyvinyl chloride is more preferred.

[0078] In addition, as specific examples of curing agents that harden gel-like (gel-like) polymeric organic materials, examples include curing agents of UV-curable liquid silicone rubber (e.g., polydimethylsiloxane).

[0079] <Laminated film>

[0080] Furthermore, at least the first and second soft polymer organic materials and electrodes described above are used, and these are stacked to form a laminate. The electrodes must be sandwiched between the soft polymer organic materials in a concealed manner. A specific method is to sandwich the electrodes between these soft polymer organic materials and then apply heat and pressure to fuse them. Alternatively, bonding sheets, adhesives, or binders can be used as needed. However, when the electrostatic attractant deforms and expands, if other raw materials are inserted as adhesive layers, deformation and expansion may be hindered, or peeling of the adhesive surfaces may occur. Therefore, a method utilizing the thermoplasticity of a resin film to fuse these materials is more preferable.

[0081] Regarding the laminated sheet, a sheet formed by laminating a soft polymer organic material and an electrode can be used, for example, a flat sheet, or its shape can be appropriately modified according to the state of the object being attracted. Specifically, as long as the object being attracted is sheet-like, the electrostatic attractor can also be sheet-like or flat. On the other hand, in cases where the object being attracted has multiple rounds or corners, making it difficult to obtain a sufficient contact surface (contact point), it is preferable, for example, to form the electrostatic attractor in a hand-like shape, so that the object can be held or clamped. In this way, it is presumably possible to ensure a sufficient contact surface (contact point), while also contributing to the flexibility (shape conformability) of the electrostatic attractor, thereby effectively demonstrating the attraction and retention force.

[0082] Regarding the laminate, the overall thickness can be adjusted appropriately according to the object being attracted, but it is preferably set to around 40μm to 1000μm. If the laminate is too thin, it is speculated that flexibility or shape conformation will improve, but it may break due to excessive bending. Conversely, if the thickness is too thick, it affects the compressibility or increases the stiffness (flexural stiffness) of the laminate, potentially hindering the overall flexibility of the electrostatic attractor.

[0083] Furthermore, regarding the laminated sheet, it is preferable that the surface that becomes the contact surface with the adsorbed object (the contact surface of the soft polymer organic material) has fine irregularities. The soft polymer organic material and the fibrous structure serving as the electrode are flexible, and it has been confirmed that when they are laminated, the surface of the soft polymer organic material will have fine irregularities. However, it is presumed that when the adsorption surface adheres to the adsorbed object, the adsorption surface will deform, which can impart an effect similar to multiple suction cups. Moreover, in order to give the soft polymer organic material such fine irregularities, the surface state of the soft polymer organic material itself can be changed (processing, etc.), but it is preferable, as described above, to combine the surface irregularities of the fibrous structure used as the electrode to give the contact surface of the soft polymer organic material fine irregularities.

[0084] <Power Supply>

[0085] After the laminated sheet is formed as described above, a power supply device is needed to apply voltage to the electrodes to generate electrostatic force. The power supply device can be connected to the electrodes of the laminated sheet via connecting terminals and a switch (not shown). It can be the same device used in general electrostatic adsorption structures, as long as it can generate a high DC voltage. The generated potential difference can be set to approximately 500V to 5000V. If necessary, it can also be configured to include a boost circuit (high voltage generation circuit) capable of boosting the voltage to the required level. In particular, for the application of the electrostatic adsorbent of the present invention to human skin, it is preferable to design it with consideration of the following (1) to (3). That is,

[0086] (1) To generate sufficient attraction, apply as high a voltage as possible.

[0087] (2) Set the potential of the human body to 0V as much as possible. The reason is that if the potential applied to the human body is biased towards either positive or negative, static electricity will remain in the body and will be impacted when it is discharged.

[0088] (3) Even if there is a chance, the current that is dangerous to the human body will not flow in.

[0089] Preferably, the voltage applied to the electrostatic attractor is determined based on the design concepts described in (1) to (3) above, especially considering (2) and (3). Furthermore, to achieve (2), when using a unipolar electrode layer, it is preferable to ground the object being attracted (human skin) to the ground wire of the voltage generation source (e.g., a high-voltage generation circuit) in the power supply device. On the other hand, when using a bipolar electrode layer, it is preferable to apply positive and negative symmetrical voltages to the first and second electrodes of the electrode layer, respectively, thereby preferably making the human body as close to 0V as possible. In addition, to achieve (3), it is preferable to suppress the output current from the power supply to 0.5mA or less. This is because if it is below 0.5mA, it is generally imperceptible to the human body. However, when current is stored in the electrostatic attractor or the human body and then discharged all at once, a large current may be generated. Therefore, the electrostatic capacitance of the electrostatic attractor is set to be less than 1000pF, which is the same as that of the human body. Specifically, it is set to about 10pF to 100pF, and the voltage is set to within ±5000V. Thus, even if it is stored in the human body, the current is less than 5μC. Therefore, it is preferable to set it as described above.

[0090] The electrostatic attractor of the present invention is formed by including the laminated sheet and power supply device as described above. The electrostatic attractor of the present invention may also be supplemented with sensors, etc., as needed, and, for example, the electrode pattern may be changed, etc., and appropriate structural modifications and additions may be made within the scope of the purpose of the present invention.

[0091] Furthermore, as the object to be attracted in this invention, a conductive material is obviously acceptable, but non-conductive materials such as paper or cloth can also be used. In particular, objects with a softness comparable to human skin, i.e., objects with a fixed surface that can be contacted and attracted by an electrostatic attractant, can be included. Examples include organs, animal skin, plants, meat and processed meat products, vegetables and processed vegetable products, fruits and processed fruit products, etc., or plastic containers such as bags, trays, and bottles used for food and packaging, or paper materials such as corrugated paper. Alternatively, combinations of these can also be used. The volume resistivity of the attracted object is 10... 12 Ω·cm~10 14 Objects with a diameter of approximately Ω·cm are considered special cases. Although the detailed principle of their attraction is not yet determined, it is speculated that the reason is that a tiny current is generated between the attraction surface of the electrostatic attractor (layered sheet) and the object being attracted. Therefore, it is speculated that the attraction force generated by the Johnson-Labec effect acts between the attraction surface of the electrostatic attractor (layered sheet) and the object being attracted.

[0092] The electrostatic attractant or laminate of this invention is also preferably used in the field of logistics or transportation, for example, it can be assembled into equipment or devices for conveying or holding, such as robotic arms.

[0093] Example

[0094] Hereinafter, preferred embodiments of the present invention will be specifically described based on examples and comparative examples, but the present invention is not limited thereto or interpreted therein.

[0095] <Making of Electrostatic Adhesives>

[0096] [Example 1]

[0097] First, prepare with Figure 1 The aluminum-coated cloth (trade name: Alink, source: Alink Co., Ltd. (address: 797 Changdaero, Seongsangu, Changwon, Gyeongnam Korea); homepage: http: / / www.alink21.com), width: 35mm, length: 119mm, thickness: 130μm) is used as an electrode. Next, two adhesive layers (trade name MPD62 manufactured by MeCan Imaging, width: 40mm, length: 123mm, thickness: 25μm) with the same width and length as the electrodes are prepared and placed on the upper and lower surfaces of the electrodes. Furthermore, resin films c and c' (both with a volume resistivity of 1×10⁻⁶) containing two pieces of soft polyvinyl chloride are passed through the adhesive layers. 10 Ω·cm (measured by the method described later), tensile modulus of elasticity (Young's modulus): 20MPa~30MPa, film thickness 100μm] sandwiched in, pressed and crimped at the same time to form a laminated sheet a ( Figure 1 Two laminated sheets, 'a', were prepared as the positive and negative electrodes.

[0098] The power supply device for applying voltage to the fabricated laminate a is prepared as follows. First, a voltage-resistant cable (trade name 03-103723 manufactured by VONA Corporation) with connectors is soldered onto a copper foil strip (not shown). The copper foil strip is then attached to the ends of the electrodes and insulated with insulating tape. Next, the connectors are connected to the positive or negative terminals of each power supply device (including a high-voltage generating device (±2000V output) and a power supply device with a 24V power supply cable) (not shown), thus creating the electrostatic attractant (positive and negative terminals) of Example 1.

[0099] [Comparative Example 1]

[0100] Except that copper foil (thickness: 18 μm) with the same width and length as the electrode in Example 1 is used as the electrode, two electrostatic attractors (electrostatic attractors of Comparative Example 1) connected to the positive and negative electrodes are fabricated using the same procedure as in Example 1.

[0101] <Evaluation of the Adhesion of Electrostatic Adhesives>

[0102] As Figure 6 Implemented according to the structure shown.

[0103] 1. Attach the two pieces (positive and negative electrodes) of each electrostatic attractor to a polyvinyl chloride (PVC) board with a W 84mm × L 135mm (contact insulation) for fixation.

[0104] 2. Next, fix the 120mm square silicon plate onto the temperature control device, set the temperature to 25℃, and set the humidity of the chamber (an acrylic box that can be controlled to the target humidity and temperature) to 50%. Hang the PVC plate with electrostatic adsorption on the hook of the force gauge, and place the PVC plate on the silicon plate by contacting the electrostatic adsorption with the silicon plate (contact area W 70mm × L 109mm).

[0105] The temperature and humidity of the electrostatic attractant and the silicon plate remain unchanged for the time being.

[0106] 3. Set the force gauge to MAX (PEAK) mode, then restore the setting to "0". Start applying voltage (±2kV) from the power supply. After 10 seconds, pull the force gauge 30mm in the direction of the arrow in the diagram at a speed of 1mm / s.

[0107] 4. The value of MAX was recorded. The same operation was repeated (number of repetitions: 20).

[0108] 5. The procedure in step 3 was repeated without applying voltage (repetition count: 20 times).

[0109] The electrostatic attractant of Example 1 and the electrostatic attractant of Comparative Example 1 were subjected to procedures 1 to 5, and the average value of the obtained measurements (average of 20 measurements) was taken as the attraction force of each electrostatic attractant. The results are shown in Table 1.

[0110] [Table 1]

[0111]

[0112] (Cavity temperature and humidity: 25℃, 50%; Applied voltage: ±2kV; Adsorption area: W 70mm×L 109mm)

[0113] <Evaluation based on KES system>

[0114] Regarding the evaluation based on the KES system, an external testing organization (Kanagawa Prefectural Institute of Advanced Industrial Science and Technology (KISTEC)) was commissioned to conduct 1) the KES-FB2-S pure bending test and 2) the KES-FB3-A compression test.

[0115] The sample used Figure 2 As shown in (I) to (III). (I) The electrode is a copper foil (18 μm thick), (II) The electrode is the same as described above (Alink), and (III) No electrode is used, only a vinyl chloride strip is used. Furthermore, in Figure 2 In China, "vinyl chloride strip" is referred to as "PVC". Figure 2 In this context, "MPD62" and "PVC" (vinyl chloride tape) refer to the adhesive layer MPD62 and the resin film containing flexible polyvinyl chloride, respectively.

[0116] The resulting charts are shown below. Figure 3 and Figure 4 The analytical method is presented at the same time. Figure 5 . Figure 3 The horizontal axis (X) represents "curvature," and the vertical axis (Y) represents "bending moment." Additionally... Figure 4 The horizontal axis (X) represents "thickness" (displacement), and the vertical axis (Y) represents "pressure". Furthermore, Figure 4 The graph lines (I) to (III) on the horizontal axis (X-axis) appear in different positions, but the difference is simply due to the varying distances from the self-compressing sensor to the sample surface and has no particular significance. This can be adjusted through the initial settings during measurement (e.g., sensor height).

[0117] In addition, Table 2 summarizes the B (bending hardness) and 2HB (bending recovery) values ​​in the pure bending test of KES-FB2-S, and the LC (compression hardness), WC (compression energy), and RC (compression recovery) values ​​in the compression test of KES-FB3-A.

[0118] The experimental conditions are as follows.

[0119] 1) KES-FB2-S Pure Bending Test

[0120] • Sensitivity: Standard

[0121] • Direction: Twisted (WARP)

[0122] • Number of repetitions: 1

[0123] • Sensors (SENS): 2×1

[0124] • Measurement cycle: 1 cycle

[0125] Sample width: 20cm

[0126] • Maximum curvature: 2.5 1 / cm

[0127] 2) KES-FB3-A Compression Test

[0128] • Sensitivity: Standard

[0129] • Number of repetitions: 1

[0130] SENS: 2×5

[0131] • Speed: 50 sec / mm

[0132] • Intake interval: Standard

[0133] Sample width: 20cm

[0134] • Maximum load (pressure): 50 gf / cm 2

[0135] [Table 2]

[0136]

[0137] As shown in Table 2, the electrostatic attractant of the present invention (II) using the specified electrodes exhibits a bending hardness (B) of 0.25 gf·cm in the KES-FB2-S pure bending test. 2 The bending recovery (2HB) is above 0.25 gf·cm / cm. Furthermore, in the KES-FB3-A compression test, the compressive hardness (LC) is below 0.16, and the compressive energy (WC) is 0.030 gf·cm / cm. 2 the following.

Claims

1. An electrostatic attractor, comprising: The laminated sheet has at least a first soft polymer organic material, an electrode, and a second soft polymer organic material stacked sequentially. The device includes a power supply that applies a voltage to the electrodes; and uses the electrostatic force generated by applying the voltage to the electrodes to make either the first or second soft polymer organic material serve as a contact surface to attract and hold the object being attracted. The electrostatic attractor is characterized in that... The first soft polymer organic material and / or the second soft polymer organic material have a tensile elastic modulus of 1 MPa or more but less than 100 MPa, and a volume resistivity of 1 × 10⁻⁶. 8 Ω·cm~1×10 13 Ω·cm, The electrode is a conductive fiber structure.

2. The electrostatic attractant according to claim 1, characterized in that, The electrode is a cloth containing fibers coated with metallic ink, or a cloth containing conductive fibers.

3. The electrostatic attractant according to claim 1 or 2, characterized in that, Regarding the electrostatic attractant, the flexural stiffness (B) in the pure flexural properties, as measured by the KES-FB2-S testing machine, is 0.25 gf·cm. 2 / cm or more.

4. The electrostatic attractant according to claim 1 or 2, characterized in that, Regarding the electrostatic attractant, in the compression test measured by the KES-FB3-A testing machine, the compressive hardness (LC) is below 0.16, and the compressive energy (WC) is 0.03 gf·cm / cm. 2 the following.

5. The electrostatic attractant according to claim 1 or 2, 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 attractant according to claim 1 or 2, characterized in that, The adsorbed material is any or a combination thereof selected from the group consisting of human skin, organs, animal skin, plants, meat and meat products, vegetables and vegetable products, fruits and fruit products, plastic containers and paper materials.

7. The electrostatic attractant according to claim 1 or 2, wherein, The electrode includes a bipolar electrode having a first electrode and a second electrode.

8. The electrostatic attractant according to claim 1 or 2, wherein, The electrodes include unipolar electrodes.

9. A robotic arm comprising an electrostatic adsorbent as described in any one of claims 1 to 8.

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