Manufacturing method of electrorheological sheet, and electrorheological sheet

Abstract

To provide a manufacturing method of an electrorheological sheet that can increase a degree of freedom in a dispersion ratio of electrorheological particles and can reduce a coefficient of friction on a surface of the electrorheological sheet.SOLUTION: There is provided a manufacturing method of an electrorheological sheet, comprising: dispersing electrorheological particles 5 in a binder to form a paste 9 having a predetermined Young's modulus; spreading the paste 9 in a layer state on a base film 7 to form a semi-finished sheet 11; and performing a curing treatment on the binder in the semi-finished sheet 11 to form an electrical insulator 3, thereby obtaining an electrorheology sheet 1.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an electrorheological sheet capable of electrically adjusting frictional force or adhesive force, and a method for manufacturing the electrorheological sheet. [Background technology]

[0002] Conventional methods for producing electrorheological sheets include, for example, as described in Patent Document 1, in which a paste in which electrorheological particles are dispersed in a binder is thermally cured in a mold.

[0003] In such a manufacturing method, the electrorheological particles are covered with the binder resin on the surface of the electrorheological sheet, which increases the coefficient of friction of the surface.

[0004] In response to this, by increasing the dispersion ratio of the electrorheological particles, the electrorheological particles will appear on the surface of the electrorheological sheet, making it possible to lower the coefficient of friction.However, when the dispersion ratio of the electrorheological particles is increased, the fluidity of the paste decreases, causing air to be entrained during molding, resulting in the generation of many voids in the sheet, and so there is a limit to how high the dispersion ratio of the electrorheological particles can be increased. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2012-153837 A Summary of the Invention [Problem to be solved by the invention]

[0006] The problems to be solved were that the electrorheological particles were covered with a binder resin, resulting in a high coefficient of friction on the surface of the electrorheological sheet produced, and that there was a limit to the dispersion ratio of the electrorheological particles. [Means for solving the problem]

[0007] The present invention provides a method for producing an electrorheology sheet, which comprises dispersing electrorheological particles in a binder to form a paste with a predetermined Young's modulus, spreading the paste in a layer on a substrate to form a semi-finished sheet, and curing the binder in the semi-finished sheet to make it an electrical insulator, thereby obtaining an electrorheology sheet to which the substrate is releasably attached.

[0008] The present invention provides an electrorheological sheet having a substrate releasably attached to the back surface and electrorheological particles dispersed in an electrical insulator and exposed on the front surface, wherein the ratio of the electrorheological particles to the electrical insulator is 5 vol% to 90 vol%. Effect of the Invention

[0009] The present invention can expand the degree of freedom in the dispersion ratio of electrorheological particles and can reduce the coefficient of friction of the surface of the electrorheological sheet. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing the electrorheological sheet according to the first embodiment. [Diagram 2] FIG. 2(A) is a schematic cross-sectional view showing a state in which a paste is spread on a base film, and FIG. 2(B) is a schematic cross-sectional view showing the forming of a semi-finished sheet used for the electrorheology sheet of FIG. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing the electrorheological sheet according to the second embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view showing the formation of a semi-finished sheet used in the electrorheological sheet of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The objectives of increasing the freedom in the dispersion ratio of electrorheological particles and lowering the surface friction coefficient of the electrorheological sheet were achieved by spreading a paste in which electrorheological particles are dispersed in a binder on a substrate and then subjecting it to a hardening treatment.

[0012] That is, as shown in the figure, electrorheological particles 5 are dispersed in binder 8 to form paste 9 with a predetermined Young's modulus. Paste 9 is spread in layers on substrate 7 to form semi-finished sheet 11. Then, binder 8 of semi-finished sheet 11 is cured to become electrical insulator 3, thereby obtaining electrorheological sheet 1 with substrate 7 releasably attached.

[0013] In one embodiment, the semi-finished product sheet 11 may have a back surface 9a of the spread paste 9 covered by the substrate 7 and a front surface 9b thereof open.

[0014] The dispersion ratio of the electrorheological particles 5 in the binder 8 is arbitrary, but may be 5 vol % to 90 vol %.

[0015] The Young's modulus of the paste 9 is arbitrary, but may be in the range of 100 kPa to 2500 kPa.

[0016] The volume resistivity of the electrorheological sheet 1 is 1×10 7 ~1×10 11 It is preferable that the volume resistivity is in the range of Ω·cm. (If the volume resistivity of the resulting electrorheological sheet 1 is within this range, a conductive filler or a non-conductive filler may be added as appropriate in addition to the electrorheological particles 5.)

[0017] In one embodiment, in the semi-finished product sheet 1, recesses 13 may be formed on the surface of the spread paste 9.

[0018] The recesses 13 can be formed by pressing a mold against the back surface 9a of the spread paste 9. The mold may be pressed against the semi-finished sheet 11.

[0019] The semi-finished sheet 11 may be formed by spreading the paste 9 on the substrate 7 in layers through a pair of rolling rollers 10a and 10b. A mode in which a rolling roller having a protrusion forms a recess may also be used. In a mode having multiple pairs of rolling rollers 10a and 10b, the pair of rolling rollers may be divided into a pair that flattens the surface of the paste 9 and a pair of rolling rollers that form a recess.

[0020] The electrical insulator 3 is not particularly limited, but may be an elastomer such as a silicone resin, a urethane resin, a fluorine resin, or a synthetic rubber such as NBR.

[0021] The electrorheological sheet 1 produced by the above-mentioned method has electrorheological particles 5 dispersed in an electrical insulator 3, a substrate 7 releasably attached to the back surface 1a, and the electrorheological particles 5 exposed on the front surface 1b. It is preferable that the ratio of the electrorheological particles 5 to the electrical insulator 3 is 5 vol% to 90 vol%, and the electrorheological particles appearing on the surface of the electrorheological sheet can reduce the coefficient of friction. EXAMPLES

[0022] [Electro-rheological sheet] FIG. 1 is a schematic cross-sectional view showing the electrorheological sheet according to the first embodiment.

[0023] The electrorheological sheet (hereinafter referred to as "ER sheet") 1 in FIG. 1 is a sheet-like member in which electrorheological particles (hereinafter referred to as "ER particles") 5 are dispersed in an electrical insulator 3.

[0024] The ER sheet 1 is capable of electrically adjusting frictional force and adhesive force by the electrorheological effect (hereinafter referred to as "ER effect"). The ER sheet 1 is provided with the base film 7 of this embodiment on the back surface 1a. Therefore, the ER sheet 1 is configured such that the release film 7 is removably attached. The rubber hardness of the ER sheet 1 is preferably 30 to 100 IRHD (JIS K 6253), and the thickness is preferably 0.1 mm to 3.0 mm.

[0025] The electrical insulator 3 may be made of any material having electrical insulation properties, and may be made of elastomer, such as silicone resin, urethane resin, or fluorine resin. In this embodiment, the electrical insulator 3 is made of elastic silicone resin. The electrical insulator 3 is formed to a certain thickness, for example, about 0.1 mm to 3.0 mm. The specific gravity of the electrical insulator 3 is about 0.9 to 2.2. From the viewpoint of expression of the ER effect, the volume resistivity of the electrical insulator 3 is set to 1×10 10 It is preferable that the resistivity is Ω·cm or more.

[0026] The ER particles 5 are conductive fillers that exhibit the ER effect when dispersed in the electrical insulator 3. Examples of the ER particles 5 that can be used include solid particles such as metal particles, metal oxide particles, and silica gel, carbon particles, and composite particles consisting of a core material of an organic polymer compound and a surface layer of electrically semiconducting inorganic particles.

[0027] The particle size of the ER particles 5 is about 0.1 μm to 100 μm. The specific gravity of the ER particles 5 is, for example, about 0.8 to 11.0, and is about 1.16 in this embodiment. The volume resistivity of the ER particles 5 is 1×10 3 ~1×10 8 The range of Ω·cm is preferable. The dispersion ratio of the ER particles 5 in the electrical insulator 3 is preferably 5 vol % to 90 vol %, and more preferably 40 vol % to 90 vol %.

[0028] To achieve a sufficient ER effect, the volume resistivity of the ER sheet 1 must be 1×10 7 ~1×10 11 As long as the volume resistivity of the resulting ER sheet 1 is within this range, a conductive filler or a non-conductive filler may be added in addition to the ER particles 5, as appropriate.

[0029] Examples of conductive fillers include metal particles, metal oxide particles, solid particles such as silica gel, and carbon particles. Examples of non-conductive fillers include silica powder, glass powder, alumina powder, talc powder, boron nitride powder, and organic polymer compound particles.

[0030] A plurality of ER particles 5 are randomly exposed on the surface 1b of the ER sheet 1. Here, exposure means that the ER particles 5 protrude from the surface of the electrical insulator 3 of the ER sheet 1.

[0031] Therefore, the front surface 1b of the ER sheet 1 has a friction coefficient that depends on the exposed ER particles 5, and the back surface 1a of the ER sheet 1, where the ER particles 5 are not exposed, has a friction coefficient that depends on the electrical insulator 3. In this embodiment, since the ER particles 5 have a lower friction coefficient than the electrical insulator 3, the front surface 1b of the ER sheet 1 has a lower friction coefficient than the back surface 1a.

[0032] The base film 7 is in close contact with and covers the back surface 1a of the ER sheet 1. The material of the base film 7 is not particularly limited as long as it can be easily peeled off from the ER sheet 1, and in this embodiment, it can be made of, for example, a PET film.

[0033] When using the ER sheet 1, the base film 7 on the back surface 1a is peeled off and electrodes are placed on the back surface 1a. When adjusting the adhesive force or frictional force against an object on the front surface 1b of the ER sheet 1, a voltage is applied via the electrodes placed on the back surface 1a.

[0034] In this embodiment, the ER particles 5 exposed on the surface of the ER sheet 1 sink into the electrical insulator 3 in response to application of a voltage, increasing the adsorptive force and frictional force that depend on the electrical insulator 3. The ER sheet 1 may generate an attractive force by electrical force based on Maxwell stress. In this case, the ER particles 5 do not need to be immersed, and the electrical insulator 3 may be configured to have no elasticity.

[0035] To reduce the adhesive force or frictional force with respect to the object, the application of voltage can be stopped.

[0036] [Method of manufacturing electrorheological sheet] The method for producing the electrorheology sheet of this embodiment includes 1. a kneading step, 2. a dividing and rolling step, 3. a hardening step, and 4. a cutting step. In addition, 5. an impurity removing step may be added as necessary.

[0037] 1. Mixing process The binder 8 and the ER particles 5 are kneaded with a kneader or the like, and the ER particles 5 are dispersed in the binder 8 to form a kneaded product, that is, a paste 9. At this time, a conductive filler or a non-conductive filler may be added as appropriate. When kneading, it is preferable to pre-disperse the ER particles 5 and other fillers in the binder 8, and it is more preferable to perform the kneading in a closed system in which the ER particles 5 and other fillers do not scatter. In addition, it is preferable to perform the kneading with a material that is almost solvent-free.

[0038] The binder 8 has a degree of fluidity that allows the ER particles 5 to be appropriately dispersed, and is changed into the electrical insulator 3 by a subsequent curing process. In this embodiment, for example, liquid-type RTV silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd.) is used as the binder 8. In this embodiment, composite particles are used as the ER particles 5.

[0039] The dispersion ratio of the ER particles 5 in the binder is preferably 5 vol% to 90 vol%, and by dispersing the ER particles 5 in the binder 8 at such a dispersion ratio, the Young's modulus of the paste 9 becomes about 100 kPa to 2500 kPa. Note that the Young's modulus of the paste 9 needs to be such that it can at least maintain the layer shape on a flat surface.

[0040] 2. Separation and rolling process FIG. 2(A) is a schematic cross-sectional view showing a state in which a paste 9 is spread on a base film 7, and FIG. 2(B) is a schematic cross-sectional view showing the formation of a semi-finished sheet 11 used in the ER sheet 1 of FIG.

[0041] 2(A), in the spreading and rolling process, the paste 9 is spread on the base film 7. When spreading, the paste 9, which has been formed into a plate or sheet shape in advance, is placed on the base film 7. The plate thickness of the paste 9 at this time is set to be larger than the plate thickness of the ER sheet 1.

[0042] 2(B), the base film 7 provided with the paste 9 is passed between a pair of pressure rollers 10a and 10b to be rolled. The pressure rollers 10a and 10b preferably have mirror surfaces.

[0043] By this rolling, the surface 9b of the paste 9 is uniformly rolled against the base film 7. At this time, the surface 9b of the paste 9 is formed flat. The paste 9 may be flattened by sandwiching it between a pair of mirror bodies. In this case, one of the mirror bodies is peeled off from the paste 9, and the other mirror body is used as the base material, and the base film 7 can be omitted.

[0044] In this way, the paste 9 is spread in a layer on the base film 7, and the surface 9b is formed flat to obtain a semi-finished sheet 11. The thickness of the semi-finished sheet 11 is, for example, 0.1 mm to 3.0 mm at the portion of the paste 9. If the base film 7 is made of a transparent material, it becomes possible to visually check for foreign matter or air contamination.

[0045] 3.Curing process The binder 8 of the paste 9 of the semi-finished sheet 11 is cured to form the electrical insulator 3 shown in Fig. 1. The method of curing is appropriately set according to the properties of the binder 8, and moisture curing, heat curing, UV curing, etc. can be used.

[0046] The curing process in this embodiment is moisture curing, and under conditions of, for example, a temperature of 40° C. and a humidity of 50%, curing can be achieved in about 16 hours.

[0047] Due to the curing treatment, the surface 9b of the paste 9 is open and not covered by the base film 7, and therefore shrinks to form the surface of the electrical insulator 3. As a result, the ER particles 5 are randomly exposed on the surface 1b of the ER sheet 1 according to their dispersion state. In addition, the back surface 9a of the paste 9 is covered by the base film 7 and does not shrink to the extent that the ER particles 5 are exposed, and in this state forms the electrical insulator 3 with the base film 7 attached.

[0048] 4.Cutting process The cured ER sheet 1 is punched out using a mold or cut into a desired planar shape, such as a rectangle or a circle, to obtain the electrorheology sheet 1 shown in Fig. 1. In this way, the ER sheet 1 is held on the base film 7 until the cutting process, which prevents foreign matter from entering the back surface 1a.

[0049] 5.Impurity removal process The hardened ER sheet 1 may be subjected to a process for removing low molecular weight components by a process such as decompression or humidification (water addition).

[0050] In the manufacturing method of such an ER sheet 1, ER particles 5 are dispersed in a binder 8 to form a paste 9 with a predetermined Young's modulus, and the paste 9 is spread in the form of a layer on a base film 7 to form a semi-finished sheet 11. The binder 8 of this semi-finished sheet 11 is cured to form an electrical insulator 3, thereby obtaining the ER sheet 1 to which the base film 7 is releasably attached.

[0051] For this reason, in this embodiment, there is no need to put the paste 9 into a mold, and air entrapment due to the low fluidity of the paste 9 is eliminated, so that the degree of freedom in the proportion of the ER particles 5 that can be dispersed in the binder 8 can be increased.

[0052] In the semi-finished sheet 11, the back surface 9a of the spread paste 9 is covered with the release film 7, and the front surface 9b of the spread paste 9 is open. Therefore, by the hardening treatment of the paste 9, the ER particles 5 are exposed on the front surface 1b of the ER sheet 1, and the exposure of the ER particles 5 on the back surface 9a of the paste 9 can be suppressed.

[0053] Therefore, since the ER sheet 1 manufactured by the manufacturing method of this embodiment has a small friction coefficient on the front surface 1b, the adhesive force and friction force can be reliably adjusted by applying a voltage, and the back surface 1a can be reliably bonded to other components such as electrodes.

[0054] In the method for producing the ER sheet 1, the ratio of the ER particles 5 to the electrical insulator 3 is preferably 5 vol % to 90 vol %, which makes it possible to obtain an electrorheology sheet 1 with excellent performance and a small coefficient of friction on the surface 1b.

[0055] The sheet used in the manufacturing method of the ER sheet 1 is the base film 7 which can be easily peeled off from the ER sheet 1, so the paste 9 can be easily spread in a layer on the base film 7. This makes it easy to handle the semi-finished sheet 11, and also makes it easy to harden the paste 9.

[0056] In the semi-finished sheet 11, the paste 9 is spread in layers on the base film 7 by passing it between the pair of pressure rollers 10a and 10b, so that the paste 9 can be easily spread in layers. EXAMPLES

[0057] Fig. 3 is a schematic cross-sectional view showing the electrorheological sheet according to Example 2. Fig. 4 is a schematic cross-sectional view showing the molding of a semi-finished sheet used for the electrorheological sheet of Fig. 3. Note that the basic configuration is similar to that of Example 1, and the same or corresponding configurations are given the same reference numerals and redundant explanations are omitted.

[0058] The ER sheet 1 of the present embodiment 2 has a plurality of recesses 13 on the surface 1b. The recesses 13 ensure the detachability of the ER sheet 1 when the application of a voltage is released.

[0059] That is, when a voltage is applied to the ER sheet 1 as in Example 1 and the frictional force or adhesive force with respect to the object increases, the surface of the electrical insulator 3 having viscoelasticity on the surface 1b of the ER sheet 1 may adhere to the object. In this case, if there are no multiple recesses 13 on the surface 1b of the ER sheet 1, the electrical insulator 3 will tend to maintain its adhesive holding force with respect to the object even when the applied voltage is released.

[0060] On the other hand, when a plurality of recesses 13 are provided on the surface 1b as in this embodiment, the adhesive strength of the surface 1b to the object decreases, and the object can be easily removed from the ER sheet 1.

[0061] [Creating a recess] As shown in FIG. 4, recesses 13 are formed on the surface of the spread paste 9 on the semi-finished product sheet 11.

[0062] In this case, the recesses 13 are formed by pressing a mold 15 against the surface of the spread paste 9. The mold 15 has protrusions 15a for forming the recesses 13.

[0063] The paste 9 on the base film 7 in Fig. 4 shows a state after pressing a mold 15. Pressing of the mold 15 may be performed before the surface of the paste 9 is shaped as in Fig. 2(A) or after the surface of the paste 9b is shaped as in Fig. 2(B).

[0064] When forming the recesses 13, a mold 15 is pressed against the surface of the paste 9 spread on the base film 7 before or after molding, and the paste is passed between pressure rollers 10a and 10b. This causes the mold 15 to be pressed against the paste 9, and the surface 9b of the paste 9 is molded flat as shown in FIG. 4, while the recesses 13 are formed.

[0065] Therefore, a semi-finished sheet 11 having recesses 13 can be formed.

[0066] The paste 9 of this semi-finished sheet 11 is cured to form an electrical insulator 3, thereby obtaining an ER sheet 1 having recesses 13 on the surface 1b. The planar shape of the recesses 13 can be selected from a variety of shapes, including a simple groove shape, a honeycomb shape, a circle, a rectangle, etc. The cross-sectional shape of the recesses 13 can also be selected from a variety of shapes.

[0067] In the second embodiment, the object can be easily removed from the ER sheet 1, and the same effects as those of the first embodiment can be achieved. [Explanation of symbols]

[0068] 1 Electrorheological sheet (ER sheet) 1a Back 1b surface 3 Electrical insulators 5 Electrorheological particles (ER particles) 7 Substrate (substrate, release film) 9. Paste 9a back side 9b surface 10a, 10b Roller 11 Semi-finished product sheet 13 Recess 15-inch

Claims

1. Disperse electrorheological particles in a binder to form a paste with a desired Young's modulus; The paste is spread in a layer on a substrate to form a semi-finished sheet; The binder of the semi-finished sheet is cured to make it an electrical insulator, thereby obtaining an electrorheological sheet to which the substrate is releasably attached. Method for manufacturing electro-rheological sheet.

2. A method for producing the electrorheological sheet of claim 1, comprising the steps of: In the semi-finished product sheet, the back surface of the spread paste is covered by the base material, and the front surface of the spread paste is open. Method for manufacturing electro-rheological sheet.

3. A method for producing the electrorheological sheet of claim 1, comprising the steps of: The ratio of the electrorheological particles to the binder is 5 vol % to 90 vol %; Method for manufacturing electro-rheological sheet.

4. A method for producing the electrorheological sheet of claim 1, comprising the steps of: The Young's modulus of the paste is 100 kPa to 2500 kPa; A method for producing an electro-rheological sheet.

5. A method for producing the electrorheological sheet of claim 1, comprising the steps of: forming a recess on the surface of the spread paste in the semi-finished product sheet; A method for producing an electro-rheological sheet.

6. A method for producing the electrorheological sheet of claim 5, comprising the steps of: The recess is formed by pressing a mold against the surface of the spread paste. Method for manufacturing electro-rheological sheet.

7. A method for producing the electrorheological sheet according to any one of claims 1 to 6, The paste is spread in layers on the substrate by passing it through a pair of rolling rollers. A method for producing an electro-rheological sheet.

8. A method for producing the electrorheological sheet according to any one of claims 1 to 6, The electrical insulator is an elastomer. Method for manufacturing electro-rheological sheet.

9. A method for producing the electrorheological sheet according to any one of claims 1 to 6, The rubber hardness of the electrorheological sheet is 30 to 100 IRHD. A method for producing an electro-rheological sheet.

10. A method for producing the electrorheological sheet according to any one of claims 1 to 6, The volume resistivity of the electrorheological sheet is 1×10 ７ ~1×10 １１ Ω cm, A method for producing an electro-rheological sheet.

11. An electrorheological sheet having a substrate releasably attached to a back surface and electrorheological particles dispersed in an electrical insulator and exposed on a front surface, The ratio of the electrorheological particles to the electrical insulator is 5 vol % to 90 vol %. Electrorheological sheet.

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