JP5347948B2 - Droplet movement control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a droplet movement controlling device including an electret excellent in transparency, in which attenuation of the surface charge density is suppressed for a long period of time when droplets comprise a saturated hydrocarbon having a relatively large number of carbon atoms. <P>SOLUTION: The droplet movement controlling device 1 includes a common electrode 3, an electret 4 disposed on the common electrode, a plurality of counter electrodes 6a, 6b disposed opposing to the electret, an electrostatic energy control means for controlling the electrostatic energy between the electret and the counter electrodes, and a droplet 7 in contact with the electret, and controls movement of the droplet on the electret. The droplet contains a 10-17C saturated hydrocarbon, which is in a liquid state under conditions of 25&deg;C and 10<SP>5</SP>Pa pressure. The electret comprises a laminate including, from the common electrode side, a layer (A) and a layer (B) each containing a specified material, layered in this order, into which charges are injected. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an apparatus for controlling movement of a droplet on an electret.

  Conventionally, an electrostatic induction conversion element using an electret in which an electric charge is injected into an insulating material is used in an electrostatic induction vibration power generator or a condenser microphone. As materials for electrets, chain polymer compounds such as polycarbonate, polypropylene and polytetrafluoroethylene have been conventionally used. Recently, it has been proposed to use a polymer having a fluorine-containing aliphatic ring structure in the main chain (for example, Patent Document 1) or a cycloolefin polymer (for example, Patent Document 2) as the material for the electret. In Patent Document 3, in order to improve the surface charge density, a laminate in which a layer having a specific dielectric constant and a layer having a specific thickness including a material having a specific dielectric constant different by 0.3 or more is stacked as an electret. It has been proposed to use.

  On the other hand, conventionally, a technique for controlling the shape and position of a droplet using electrowetting is known. Electrowetting is a method for electrically controlling the wettability of the film surface. For example, a droplet is placed on an insulating film, and a voltage is applied between a plate electrode under the insulating film and an electrode inserted into the droplet. Then, the surface energy is reduced by the electrostatic energy of the capacitor formed between the droplet and the plate electrode, and the contact angle between the droplet and the insulating film is reduced. Such a technique is applied to a microchemical substance analysis system, a liquid lens, and the like, and is also proposed to be used for an image display device (for example, Patent Document 4). Recently, as a control device for controlling the position and shape of a substance such as a droplet, an apparatus including an electret has been proposed (Patent Document 5).

JP 2006-180450 A JP 2009-212436 A WO09 / 119678 pamphlet JP 2006-276801 A JP 2009-171676 A

The control device described in Patent Document 5 has an advantage that the movement of a droplet or the like can be controlled with a low voltage. However, in the control device, there is a problem that the surface potential of the electret is greatly attenuated over time if the droplet is kept in contact with the electret. Patent Document 5 proposes to provide a protective film on the surface of the electret in contact with the liquid droplets in order to prevent the dissipation of the electric charge from the electret. Polyparaxylylene is described as a material for the protective film. Has been. However, as a result of studies by the present inventors, when a protective hydrocarbon made of polyparaxylylene uses a saturated hydrocarbon having a relatively large carbon number, such as hexadecane, as the droplet, the electret becomes longer when the contact time with the droplet increases. It was found that there was a problem of peeling from. When the protective film is peeled off, the surface potential is attenuated as described above.
Furthermore, it was also found that when a protective film made of polyparaxylylene is provided, the transparency (light transmission) is lowered. The decrease in transparency is not preferable when, for example, the control device is used in an image display device and the electret is arranged on the viewing side with respect to the droplet.
The present invention has been made in view of the above circumstances, and a liquid provided with an electret having excellent surface transparency in which attenuation of a surface potential when a droplet is a saturated hydrocarbon having a relatively large carbon number is suppressed over a long period of time. A droplet movement control device is provided.

As a result of intensive studies, the present inventors have found that the above problems can be solved by using an electret having a specific laminated film injected with a charge, and have completed the present invention.
The present invention is the following [1] to [12].
[1] A common electrode, an electret provided on the common electrode, a plurality of counter electrodes disposed to face the electret, and electrostatic energy for controlling electrostatic energy between the electret and the counter electrode A device comprising a control means and a droplet in contact with the electret, the device controlling the movement of the droplet on the electret,
The droplets contain a saturated hydrocarbon having 10 to 17 carbon atoms that is liquid under conditions of a temperature of 25 ° C. and a pressure of 10 ⁵ Pa;
The electret, from the common electrode side, a layer (A) containing a fluoropolymer (a) having an aliphatic ring in the main chain or a material (a ′) derived from the fluoropolymer (a); The non-fluorinated polymer (b) having an aliphatic ring in the main chain or the layer (B) containing the material (b ′) derived from the non-fluorinated polymer (b) is charged in the laminate in this order. der made by injecting a is,
Value of - [the non-fluoropolymer dielectric constant of (b) the relative dielectric constant of the fluorine-containing polymer (a)], characterized in der Rukoto 0.1 or more and less than 0.3, the liquid Drop movement control device.
[2] The droplet movement control device according to [1], wherein the thickness of the layer (A) is 1 to 50 μm and the thickness of the layer (B) is 0.5 to 10 μm.
[3] A layer (C) containing a fluorine-containing polymer (c) having an aliphatic ring in the main chain or a material (c ′) derived from the fluorine-containing polymer (c) on the layer (B) (C ) Are stacked, the droplet movement control device according to [1] or [2].
[4] The droplet movement control device according to [3], wherein the thickness of the layer (C) is 0.5 to 5 μm.
[5] The droplet movement control device according to [1] to [4], wherein the non-fluorinated polymer (b) has a repeating unit represented by the following formula (b1-1).

［式（ｂ１−１）中、Ｒ^１およびＲ^２はそれぞれ独立に、水素原子、アルキル基またはシクロアルキル基であり、Ｒ^１およびＲ^２が相互に結合して環を形成していてもよい。］

[In Formula (b1-1), R ¹ and R ² are each independently a hydrogen atom, an alkyl group or a cycloalkyl group, and R ¹ and R ² may be bonded to each other to form a ring. . ]

[6] The liquid according to [5], wherein the non-fluorinated polymer (b) has a repeating unit in which R ¹ and R ² in the formula (b1-1) are bonded to each other to form a ring. Drop movement control device.
[7] The droplet movement control device according to [6], wherein the non-fluorinated polymer (b) has a repeating unit represented by the following formula (b1-12).

［式（ｂ１−１２）中、Ｒ^１１は水素原子またはアルキル基である。］

[In the formula (b1-12), R ¹¹ represents a hydrogen atom or an alkyl group. ]

[8] The non-fluorinated polymer (b), further having a repeating ^{unit R 1} and ^{R 2} do not form a ring with each other in the front above formula (b1-1), [6 ] Or [7] droplet movement control device.
[9] The droplet movement control device according to [1] to [8], wherein the fluoropolymer (a) has a carboxy group or an alkoxycarbonyl group as a terminal group.
[10] The droplet movement control device according to [1] to [9], wherein the material (a ′) is a reaction product of the fluoropolymer (a) and a silane coupling agent having an amino group. .
[11] The droplet movement control device according to [1] to [10], wherein the saturated hydrocarbon is hexadecane.
[12] The droplet movement control device according to [1] to [11], which is an image display device.

  ADVANTAGE OF THE INVENTION According to this invention, attenuation | damping of surface potential when a droplet is a saturated hydrocarbon with comparatively large carbon number can be suppressed over a long period of time, and a droplet movement control apparatus provided with the electret which was excellent also in transparency can be provided.

It is a schematic sectional drawing which shows a part of structure of one Embodiment of the droplet movement control apparatus of this invention. It is a schematic block diagram which shows an example of the electrostatic energy control means used for the droplet movement control apparatus of this invention. It is a conceptual diagram of a corona charging device used for charge injection. It is a figure which shows the setting position of the measurement point of surface potential.

The droplet movement control device of the present invention (hereinafter sometimes simply referred to as “control device”) has a common electrode, an electret in which electric charges are injected into a resin film formed on the common electrode, and the electret. A plurality of counter electrodes arranged, electrostatic energy control means for controlling electrostatic energy between the electret and the counter electrode, and droplets in contact with the electret, the droplets on the electret It is a device that controls movement.
“Movement of a droplet on an electret” means a variation in one or both of the position of the droplet on the electret and the shape of the contact surface of the droplet with the electret.

Hereinafter, the configuration of the control device of the present invention will be described with reference to the drawings.
One embodiment of the control device of the present invention is shown in FIG. FIG. 1 is a schematic sectional view of a part of the configuration of the control device 1 of the present embodiment.
The control device 1 includes a transparent substrate 2, a transparent electrode layer (common electrode) 3 formed on the transparent substrate 2, an electret 4 provided on the transparent electrode layer 3, and a constant interval substantially parallel to the electret 4. The counter substrate 5 is provided with a space, and a plurality of counter electrodes 6a and 6b are formed on the surface of the counter substrate 5 on the electret 4 side.
A colorless or colored droplet 7 is arranged in the space between the electret 4 and the counter electrodes 6a and 6b, and a gas such as air exists in a region where the droplet 7 does not exist. Yes. The upper and lower ends of the liquid droplet 7 are in contact with the electret 4 and the counter electrodes 6a and 6b, respectively.
The transparent electrode layer 3 is connected to the ground (reference potential point).

The control device 1 further includes electrostatic energy control means for controlling electrostatic energy between the electret 4 and the counter electrodes 6a and 6b.
The control device 1 can change the shape and position of the droplet 7 based on the same principle as the control device described in Patent Document 5.

The electrostatic energy control means is not particularly limited as long as it can control the electrostatic energy between the electret 4 and the counter electrode 6a or the counter electrode 6b. A switching method is preferable.
As the electrostatic energy control means of this system, for example, as shown in FIG. 2, the connection state between the capacitor and each counter electrode (whether the counter electrode is connected to the capacitor or to the ground (reference potential point)) And a switching device for switching.

In the electrostatic energy control means shown in FIG. 2, one terminal is connected to the counter electrode 6a, the other terminal is connected to the ground, and one terminal is connected to the counter electrode 6b. A second capacitor 8b having the other terminal connected to the ground and an SPDT (Single Pole Double Throw) switch 9 are provided.
When the connection state of the counter electrodes 6a and 6b is switched by the SPDT switch 9, the electrostatic energy between the two changes. As a result, the position of the droplet 7 changes. In the control means shown in FIG. 2, two capacitors 8a and 8b are used. One terminal of each capacitor is grounded, and the other terminal is connected to one of the counter electrodes 6a and 6b. In the state of SPDT 9 shown in FIG. 2, the counter electrode 6a is directly grounded and the counter electrode 6b is connected to the capacitor 8a. When the SPDT 9 is switched, the counter electrode 6b can be directly grounded and the counter electrode 6a can be connected to the capacitor 8a. Thus, the electrostatic energy between the electret 4 and the counter electrodes 6a and 6b is changed by switching the connection state between the counter electrodes 6a and 6b and the capacitors 8a and 8b and the ground (reference potential point). be able to.
For example, when the droplet 7 is first positioned on the counter electrode 6b, the liquid crystal 7a is connected in the state where the counter electrode 6a is connected to the ground and the counter electrode 6b is connected to the capacitor 8b as shown in FIG. The droplet 7 moves in the direction from the counter electrode 6b to the counter electrode 6a. Subsequently, when the counter electrode 6a is connected to the capacitor 8a and the counter electrode 6b is connected to the ground, the droplet 7 moves from the counter electrode 6a to the counter electrode 6b. Note that the moving direction of the droplet is a direction in which electrostatic energy is minimized, and therefore, the moving direction can change depending on the material and surface state of the electret, the dielectric constant of the droplet, and the like.

  As described above, when the electrostatic energy control means including the capacitor and the switching device is used, the movement of the droplet 7 can be controlled only by switching the connection state of the counter electrodes 6a and 6b. Since the switching can be performed at a low voltage of 3 V or less, it is not necessary to supply a high voltage to the control device 1 from the outside.

In this example, the electrostatic energy control means includes two capacitors 8a and 8b and an SPDT switch 9 capable of switching the connection state of each of the two counter electrodes 6a and 6b. It is not limited to this.
For example, the number of counter electrodes may be three or more.
Further, in place of the SPDT switch 9, a semiconductor switch such as a relay switch or a photoMOS relay or other appropriate changeover switch can be used.
Further, as the switching device, a device capable of switching the connection state of only one of the two counter electrodes is used like the control device 22 shown in FIG. 2 of Patent Document 5 (Japanese Patent Laid-Open No. 2009-171676). May be.

  Further, as long as the electrostatic energy between the electret 4 and the counter electrode 6a or the counter electrode 6b can be changed, other electrostatic energy control means other than the one including the capacitor and the switching device may be used. . Examples of the other electrostatic energy control means include a variable capacitor using a change in electrode plate interval and overlapping area.

The control device 1 of the present embodiment is suitable as an image display device. When the control device 1 is used as an image display device, the transparent substrate 2 is on the display side.
Examples of the image display device include an electronic bulletin board, an electronic advertisement, and an electronic paper display.
“Transparent” of the transparent substrate 2 means that light in the visible light region (300 nm to 800 nm) can be transmitted. The transparent substrate 2 preferably has a light transmittance of 90% or more at wavelengths of 550 nm and 650 nm.
As a material constituting the transparent substrate 2, an insulating material is preferable. The resistance value of the insulating material is preferably 10 ¹⁰ Ωcm or more, more preferably 10 ¹² Ωcm or more in terms of volume specific resistance.
The insulating material constituting the transparent substrate 2 preferably has a refractive index of 1.3 to 2.0 at a wavelength of 589 nm, and more preferably 1.4 to 1.7. Specific examples of such an insulating material include inorganic materials such as glass and ceramics, and organic polymer materials such as polyethylene terephthalate, polyethylene naphthalate, polyimide, polycarbonate, acrylic resin, and polyether sulfone. Of these, glass is preferred. In particular, when the droplet movement control device of the present invention is used as an image display device, glass for a display substrate is preferable.
The transparent substrate 2 may be composed of a single layer or may be composed of a plurality of layers.

The transparent electrode layer 3 is made of a conductive material. The resistance value of the conductive material is preferably 0.1 Ωcm or less, more preferably 0.01 Ωcm or less in terms of volume specific resistance.
The conductive material is not particularly limited, and for example, a known material used as an electrode material can be used. Specifically, a metal such as gold, silver, copper, nickel, chromium, aluminum, titanium, tungsten, molybdenum, tin, cobalt, palladium, platinum, an alloy mainly containing at least one of these; ITO ( Examples thereof include metal oxides such as Indium Tin Oxide), IZO (Indium Zinc Oxide), zinc oxide, titanium dioxide, and tin oxide; organic conductive materials made of polyaniline, polypyrrole, PEDOT / PSS, carbon nanotubes, and the like. Among these, metal oxides are preferable, and ITO (Indium Tin Oxide) is particularly preferable.
The transparent electrode layer 3 may be composed of a single layer, may be composed of a plurality of layers, or may form a structure having a distribution in composition.
The thickness of the transparent electrode layer 3 (the total thickness in the case of a plurality of layers) is preferably 10 to 1,000 nm, more preferably 100 to 500 nm, considering transparency, conductivity, productivity, and the like.

The formation method of the transparent electrode layer 3 is not specifically limited, A well-known method can be utilized as formation methods of an electroconductive thin film, such as a physical vapor deposition method and an electroless plating method.
Examples of physical vapor deposition include sputtering, vacuum vapor deposition, and ion plating.
The electroless plating method is selected on the surface of the substrate on which the catalyst has adhered by immersing the substrate with the catalyst on the surface in an electroless plating solution containing a metal salt, reducing agent, etc., and the reducing power of electrons generated from the reducing agent. In this method, a metal is deposited to form an electroless plating film.
As metal salts contained in the electroless plating solution, nickel salts (nickel sulfate, nickel chloride, nickel hypophosphite, etc.), cupric salts (copper sulfate, copper chloride, pyrophosphoric acid, etc.), cobalt salts ( Cobalt sulfate, cobalt chloride, etc.), noble metal salts (chloroplatinic acid, chloroauric acid, dinitrodiammine platinum, silver nitrate, etc.).
Examples of the reducing agent contained in the electroless plating solution include sodium hypophosphite, formaldehyde, sodium tetrahydroborate, dialkylamine borane, hydrazine and the like.
In the case where the transparent electrode layer 3 is formed by an electroless plating method, it is preferable that a catalyst is attached to the surface of the transparent substrate 2 in advance before the transparent electrode layer 3 is formed. Examples of the catalyst include metal fine particles, metal-supported fine particles, colloids, and organometallic complexes.

The electret 4 includes a fluoropolymer (a) having an aliphatic ring in the main chain or a layer (A) containing a material (a ′) derived from the fluoropolymer (a), and an aliphatic ring in the main chain. And a non-fluorinated polymer (b) having a layer or a layer (B) containing a material (b ′) derived from the non-fluorinated polymer (b) and injecting a charge into the laminate laminated in this order It is.
In the laminate, the layer (A) responsible for charge retention as an electret is in contact with the transparent electrode layer 3, and the layer (A) and the layer (B) are in direct contact. By disposing the layer (A) and the layer (B) in this manner, the surface potential of the electret 4 due to contact with the droplets 7 is suppressed over a long period of time, and the durability of the control device 1 is improved. Further, since both the layer (A) and the layer (B) have a high visible light transmittance, the transparency of the entire laminate, and thus the electret 4 is also highly transparent. Therefore, when the transparent substrate 2 is on the display side of the image display device, the droplets 7 are easily visible, and the usefulness of the control device 1 as an image display device is high.

In the laminate, the thickness of the layer (A) is preferably 1 to 50 μm, and more preferably 5 to 20 μm. When the thickness of the layer (A) is 1 μm or more, the charge retention performance of the electret 4 is good, and the heat resistance and the like are improved. When the thickness of the layer (A) is 50 μm or less, the productivity during film formation and the uniformity of the film are excellent.
The thickness of the layer (B) is preferably 0.5 to 10 μm, and more preferably 1 to 6 μm. Within this range, the effect of suppressing the attenuation of the surface potential due to the contact of the droplet 7 is good. Further, when the thickness of the layer (B) is 0.5 μm or more, it is difficult to cause defects in the film when it is formed, and it is easy to ensure the uniformity of the film.
The layer (A), the layer (B), and a method for forming each layer will be described in detail later.

In the laminate, the layer (B) further includes a fluorine-containing polymer (c) having an aliphatic ring in the main chain or a material (c ′) derived from the fluorine-containing polymer (c). It is preferable that (C) is laminated. As a result, the effect of suppressing the attenuation of the surface potential is further improved, and a large contact angle with respect to the droplet can be maintained. Moreover, the tolerance with respect to the saturated hydrocarbon which comprises the droplet 7 of the electret 4 improves, and the film thickness reduction of the said laminated body by this saturated hydrocarbon can be suppressed. As a result, the durability of the control device 1 is further improved.
In the case of providing the layer (C), it is preferable that the layer (C) is disposed on the outermost surface on the side in contact with the droplet 7 in the laminate.
The thickness of the layer (C) is preferably 0.5 to 5 μm, and more preferably 0.5 to 2 μm. When the thickness of the layer (C) is 0.5 μm or more, the effect of improving the resistance to the droplet 7 is excellent, and when it is 5 μm or less, the effect of suppressing the attenuation of the surface potential due to the contact of the droplet 7 is good.
The layer (C) and the formation method thereof will be described later in detail.

The total thickness of the laminate is 1.5 to 60 μm in the case of a two-layer laminate of a layer (A) and a layer (B) because of the characteristics of electret, which is advantageous for processing, etc. Is preferable, and 6 to 30 μm is more preferable. In the case of a three-layer laminate of layer (A), layer (B), and layer (C), 2 to 65 μm is preferable, and 6 to 30 μm is more preferable.
The thickness of each of the layer (A), the layer (B) and the layer (C) and the thickness of the entire laminate can be measured by an optical interference type film thickness measuring device.

The method for forming the laminate is not particularly limited. For example, the transparent substrate 2 on which the transparent electrode layer 3 is formed is used as the substrate, and the layer (A) and the layer (B) and further the layer (C) are sequentially formed on the transparent electrode layer 3 of the substrate. Can be formed.
During the formation of each layer, a surface treatment may be applied to the base (layer on the side to be laminated). As the surface treatment, a method of coating a silane coupling agent, a method of hydrophilizing or roughening the surface by plasma treatment, and the like can be applied.
In the case of coating a silane coupling agent, the surface treatment can be performed by dissolving the silane coupling agent in a solvent and coating on a base. About a silane coupling agent and a solvent, the thing similar to the silane coupling agent and solvent which are mentioned in description of the layer (A) mentioned later, respectively is mentioned. As for the coating method, the same method as the coating method of the coating liquid mentioned in the description of the layer (A) can be mentioned.
When the surface is hydrophilized or roughened by plasma treatment, plasma treatment using a gas such as oxygen, nitrogen, argon, methane, CHF ₃ , or CF ₄ can be applied. These gases may be used singly or in a suitable mixture. In the plasma treatment, it is more preferable to use oxygen, nitrogen, argon, methane gas, or a mixed gas thereof in order to minimize the decrease in the film thickness of the base.

By injecting electric charge into the laminate, the laminate can be made into an electret 4.
As a method for injecting electric charge, any method can be used as long as it is a method for charging an insulator. For example, the corona discharge method described in GMSessler, Electrets Third Edition, pp20, Chapter 2.2 “Charging and Polarizing Methods” (Laplacian Press, 1998), electron beam collision method, ion beam collision method, radiation irradiation method, light irradiation method, A contact charging method, a liquid contact charging method, or the like is applicable. In the present invention, it is particularly preferable to use a corona discharge method or an electron beam collision method.
As a temperature condition for injecting the charge, it is maintained after the injection that the temperature is higher than the glass transition temperature (Tg) of the polymer (a) or the material (a ′) contained in the layer (A) of the laminate. It is preferable from the viewpoint of the stability of the electric charge, and it is particularly preferable to carry out under the temperature condition of about Tg + 10 ° C. to Tg + 20 ° C.
It is preferable to apply a high voltage as the applied voltage for injecting electric charges if it is not higher than the dielectric breakdown voltage of the laminate. In the present invention, the voltage applied to the laminate is 6 to 30 kV for positive charges, preferably 8 to 15 kV, and −6 to −30 kV for negative charges, preferably −8 to −15 kV.
Since the polymer (a) or the material (a ′) can hold a negative charge more stably than a positive charge, the applied voltage is preferably a negative charge. In this case, the surface potential of the electret 4 is negative.

  Here, an example is shown in which a transparent substrate 2 having a transparent electrode layer 3 formed on the surface is used as the substrate, a laminate is formed on the transparent electrode layer 3, and charge is injected. It is not limited to. For example, after forming the laminate on an arbitrary substrate and peeling the laminate from the substrate, the laminate is placed on the transparent substrate 2 on the surface of which the transparent electrode layer 3 is formed, and charges are injected. The electret 4 may be used. Moreover, after forming the said laminated body on arbitrary board | substrates and injecting an electric charge into the electret 4, this electret 4 is peeled from the board | substrate, and this is used as the transparent substrate 2 in which the transparent electrode layer 3 was formed in the surface You may arrange on top.

  When no charge is injected, the substrate can be used without any particular material. In the case of injecting charges, the substrate may be any substrate that can be connected to the ground when injecting charges into the obtained laminate. Preferred materials include, for example, conductivity such as gold, silver, copper, nickel, chromium, aluminum, titanium, tungsten, molybdenum, tin, cobalt, palladium, platinum, and an alloy containing at least one of these as a main component. These metals are mentioned. The substrate is made of an insulating material other than a conductive metal, for example, an inorganic material such as glass, a polymer compound material such as polyethylene terephthalate, polyimide, polycarbonate, or acrylic resin (insulating substrate). In addition, a metal film or a metal oxide such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), zinc oxide, titanium dioxide, or tin oxide by a method such as sputtering, vapor deposition, or wet coating on the surface; polyaniline, polypyrrole , PEDOT / PSS, an organic conductive material made of carbon nanotubes, or the like may be used. Further, a semiconductor material such as silicon can be used as a substrate if the same surface treatment is performed or the semiconductor material itself has a low resistance value. The resistance value of the substrate material is preferably 0.1 Ωcm or less, more preferably 0.01 Ωcm or less, in terms of volume resistivity. With such a low resistance substrate material, it is possible to produce an electret by injecting a charge as it is into the laminate formed on the substrate.

The counter substrate 5 may be transparent like the transparent substrate 2 or may not be transparent.
As a material constituting the counter substrate 5, an insulating material is preferable. The resistance value of the insulating material is preferably 10 ¹⁰ Ωcm or more, more preferably 10 ¹² Ωcm or more in terms of volume specific resistance.
The insulating material constituting the counter substrate 5 may be transparent, may not be transparent, and is preferably transparent. Specific examples of the transparent insulating material include the same insulating materials as those described in the description of the transparent substrate 2.
Additives such as a colorant and a light scattering agent may be blended in the insulating material. For example, when a transparent resin is used as the insulating material and a light scattering agent made of a material having a refractive index different from that of the resin is blended, the light incident on the counter substrate 5 is scattered and the background becomes white when viewed from the display side. appear.
The counter substrate 5 may be composed of a single layer or may be composed of a plurality of layers. For example, a laminate in which a layer in which the additive is blended and a layer in which the additive is not blended may be laminated.

On the counter substrate 5, a plurality of counter electrodes 6a and 6b are formed.
The counter electrodes 6 a and 6 b are preferably transparent like the transparent electrode layer 3.
The material constituting the counter electrodes 6a and 6b is not particularly limited as long as it is a conductive material. The resistance value of the conductive material is preferably 0.1 Ωcm or less, more preferably 0.01 Ωcm or less in terms of volume resistivity. Specific examples of the conductive material include the same conductive materials as those described in the description of the transparent electrode layer 3.
The counter electrodes 6a and 6b may be composed of a single layer, may be composed of a plurality of layers, or may form a structure having a distribution in composition.
The thickness of the counter electrodes 6a and 6b (total thickness in the case of a plurality of layers) is preferably 10 to 1,000 nm, and more preferably 100 to 500 nm. When the thickness is within the above range, the conductivity and productivity are excellent.
The shape and arrangement of the counter electrodes 6a and 6b are not particularly limited, and may be set as appropriate according to how the movement of the droplet is controlled. As a specific example, by placing either one at the center of the pixel and the other at the outer periphery, it is possible to change the appearance (color, light intensity, focal position, etc.) of the pixel center by switching the electrodes. .
It is also possible to construct a Fabry-Perot interferometer with two substrates and change the optical distance by moving the droplet.

A method for forming the counter electrodes 6a and 6b is not particularly limited, and a known method can be used. Specifically, for example, a method of forming a conductive thin film on the counter substrate 5 and patterning the conductive thin film can be mentioned.
Examples of the method for forming the conductive thin film include the physical vapor deposition method and the electroless plating method described in the method for forming the transparent electrode layer 3.
The patterning of the conductive thin film can be performed by, for example, a combination of a photolithography method and a wet etching method, wiring formation by printing nanometal ink, or the like. For example, patterning by a combination of a photolithography method and a wet etching method is performed by applying a photoresist on a conductive thin film to form a resist film, and then exposing and developing the resist film to form a pattern (resist mask). And etching the conductive thin film using the resist mask as a mask. Etching of the conductive thin film can be performed by, for example, wet etching using a liquid (usually an acidic solution) that dissolves the conductive thin film as an etchant. Further, as a method for printing nano metal ink or the like, a screen printing method, an ink jet method, a micro contact printing method, or the like can be used. The nano metal ink refers to an ink in which nanoparticles of the conductive material described above are dispersed in an organic solvent, water, or the like.

As the droplet 7, one containing a saturated hydrocarbon having 10 to 17 carbon atoms, which is liquid under conditions of a temperature of 25 ° C. and a pressure of 10 ⁵ Pa (hereinafter referred to as a standard environment) is used. The saturated hydrocarbon may be an alkane (a linear or branched saturated hydrocarbon) or a cycloalkane (a cyclic saturated hydrocarbon).
The saturated hydrocarbon constituting the droplet 7 is preferably an alkane, and more preferably a linear alkane. Among them, a linear alkane having 10 to 17 carbon atoms is preferable, a linear alkane having 12 to 16 carbon atoms is more preferable, and hexadecane is most preferable.
The saturated hydrocarbon constituting the droplet 7 may be one type or two or more types.

In the present embodiment, the droplet 7 is colored. However, the present invention is not limited to this, and the droplets 7 may be uncolored.
The colorant used for coloring the droplet 7 is not particularly limited and can be appropriately selected from known pigments, dyes and the like. Examples include anthraquinone red, diketopyrrolopyrrole red, salt brominated copper phthalocyanine, copper phthalocyanine and the like.
The blending amount of the colorant can be appropriately set in consideration of the type of colorant to be used and the desired color tone.
The droplet 7 may contain components other than the saturated hydrocarbon and the colorant as long as the effects of the present invention are not impaired. Examples of the other components include surfactants, viscosity modifiers, silane coupling agents, and the like.
However, in consideration of the effect of the present invention, it is preferable that the droplet 7 does not contain components other than the saturated hydrocarbon and the colorant.

The present invention is not limited to the above embodiment.
For example, in the above embodiment, the example in which the number of electrodes opposed to the electret 4 is two (the counter electrodes 6a and 6b) is shown, but the number of the electrodes is not limited to this, and the distance for moving the droplet 7 It can be appropriately determined according to the above.
In the said embodiment, although the example which used the flat plate with the smooth surface was shown as the transparent substrate 2 and the counter substrate 5, this invention is not limited to this, As a transparent substrate 2 or the counter substrate 5, an unevenness | corrugation is formed in the surface You may use the made board | substrate. For example, you may use the board | substrate with which the unevenness | corrugation of the pattern corresponding to the counter electrodes 6a and 6b was formed in the surface. The substrate may be provided with other pattern irregularities.

  As a method for producing a substrate having a surface with unevenness, a conventionally known method such as a vacuum process or a wet process can be used, and is not particularly limited. Examples of the vacuum process include a sputtering method through a mask and a vapor deposition method through a mask. Examples of the wet process include a roll coater method, a cast method, a dipping method, a spin coat method, a water cast method, a Langmuir / Blodget method, a die coat method, an ink jet method, and a spray coat method. Printing techniques such as letterpress printing, gravure printing, lithographic printing, screen printing, and flexographic printing can also be used. Furthermore, examples of a method for manufacturing a substrate having fine unevenness on the surface include a nanoimprint method and a photolithography method.

  In the above embodiment, an example in which the droplet 7 is in contact with both the electret 4 and the counter electrodes 6a and 6b has been described. However, the present invention is not limited to this, and only one of the electret 4 and the counter electrodes 6a and 6b is used. It may be in contact with. However, in the present invention, it is preferable that the droplet 7 is in contact with at least the electret 4.

<Layer (A)>
The layer (A) contains a fluoropolymer (a) having an aliphatic ring in the main chain or a material (a ′) derived from the fluoropolymer (a). Thereby, the layer (A) has high charge retention performance and excellent transparency.
Examples of the material (a ′) include a material obtained by mixing the fluorine-containing polymer (a) with components other than the fluorine-containing polymer (a), the fluorine-containing polymer (a), and the fluorine-containing polymer (a). And reaction products with other components other than the above. When the layer (A) contains the reaction product, the fluoropolymer (a) used for forming the reaction product or a part of other components remains unreacted in the layer (A). It may remain. Details of the material (a ′) will be described later.

[Fluoropolymer (a)]
The fluorinated polymer (a) is a fluorinated polymer having an aliphatic ring in the main chain.
Here, the “fluorinated polymer” is a polymer having a fluorine atom in its structure.
In the fluorine-containing polymer (a), the fluorine atom may be bonded to the carbon atom constituting the main chain or may be bonded to the side chain. The fluorine atom is preferably bonded to the carbon atom constituting the main chain because it is suitable for electretization with a low water absorption and low dielectric constant, high dielectric breakdown voltage, and high volume resistivity.

“Having an aliphatic ring in the main chain” means that at least one of the carbon atoms constituting the ring skeleton of the aliphatic ring is a carbon atom constituting the main chain of the fluoropolymer (a). means.
At least one of the carbon atoms derived from the polymerizable double bond of the monomer used for the polymerization of the fluoropolymer (a) is a carbon atom constituting the main chain. For example, when the fluoropolymer (a) is a fluoropolymer obtained by polymerizing a cyclic monomer as described later, two carbon atoms constituting the double bond constitute the main chain. It becomes a carbon atom. In the case of a fluorinated polymer obtained by cyclopolymerizing a monomer having two polymerizable double bonds, among the four carbon atoms constituting the two polymerizable double bonds At least two are carbon atoms constituting the main chain.

“Aliphatic ring” refers to a ring having no aromaticity. The aliphatic ring may be saturated or unsaturated. The aliphatic ring may have a carbocyclic structure in which the ring skeleton is composed only of carbon atoms, and has a heterocyclic structure that includes atoms other than carbon atoms (heteroatoms) in the ring skeleton. Also good. Examples of the hetero atom include an oxygen atom and a nitrogen atom.
The number of atoms constituting the ring skeleton of the aliphatic ring is preferably 4 to 7, and more preferably 5 to 6. That is, the aliphatic ring is preferably a 4- to 7-membered ring, and more preferably a 5- to 6-membered ring.
The aliphatic ring may or may not have a substituent. The phrase “which may have a substituent” means that a substituent (an atom or group other than a hydrogen atom) may be bonded to an atom constituting the ring skeleton of the aliphatic ring.

The aliphatic ring may be a non-fluorinated aliphatic ring or a fluorinated aliphatic ring. Since it is excellent in charge retention performance, it is preferably a fluorine-containing aliphatic ring.
The non-fluorinated aliphatic ring is an aliphatic ring that does not contain a fluorine atom in the structure. Specifically, as the non-fluorinated aliphatic ring, a saturated or unsaturated aliphatic hydrocarbon ring, and a part of carbon atoms in the aliphatic hydrocarbon ring is substituted with a hetero atom such as an oxygen atom or a nitrogen atom. An aliphatic heterocyclic ring etc. are mentioned.
The fluorine-containing aliphatic ring is an aliphatic ring containing a fluorine atom in the structure. Examples of the fluorinated aliphatic ring include an aliphatic ring in which a substituent containing a fluorine atom (hereinafter referred to as a fluorinated group) is bonded to a carbon atom constituting the ring skeleton of the aliphatic ring. Examples of the fluorine-containing group include a fluorine atom, a perfluoroalkyl group, a perfluoroalkoxy group, and ═CF ₂ .
The fluorine-containing aliphatic ring or non-fluorine-containing aliphatic ring may have a substituent other than the fluorine-containing group.

Preferred fluorine-containing polymers (a) include the following fluorine-containing cyclic polymers (I) and fluorine-containing cyclic polymers (II).
Fluorinated cyclic polymer (I): a polymer having units based on a cyclic fluorinated monomer.
Fluorine-containing cyclic polymer (II): a polymer having units formed by cyclopolymerization of a diene fluorine-containing monomer.
“Cyclic polymer” means a polymer having a cyclic structure.
“Unit” means a repeating unit constituting a polymer.
Hereinafter, the compound represented by the formula (1) is also referred to as “compound (1)”. The same applies to units, compounds and the like represented by other formulas. For example, the unit represented by formula (3-1) is also referred to as “unit (3-1)”.

The fluorinated cyclic polymer (I) has units based on “cyclic fluorinated monomer”.
“Cyclic fluorine-containing monomer” means a monomer having a polymerizable double bond between carbon atoms constituting a fluorine-containing aliphatic ring, or a carbon atom constituting a fluorine-containing aliphatic ring and a fluorine-containing fat. It is a monomer having a polymerizable double bond with a carbon atom outside the group ring.
As the cyclic fluorine-containing monomer, the following compound (1) or compound (2) is preferable.

［式中、Ｘ^１、Ｘ^２、Ｘ^３、Ｘ^４、Ｙ^１およびＹ^２は、それぞれ独立に、フッ素原子、パーフルオロアルキル基またはパーフルオロアルコキシ基である。］

[Wherein, X ¹ , X ² , X ³ , X ⁴ , Y ¹ and Y ² are each independently a fluorine atom, a perfluoroalkyl group or a perfluoroalkoxy group. ]

The perfluoroalkyl group in X ¹ , X ² , X ³ , X ⁴ , Y ¹ and Y ² preferably has 1 to 7 carbon atoms, and more preferably 1 to 4 carbon atoms. The perfluoroalkyl group is preferably linear or branched, and more preferably linear. Specific examples include a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, and the like, and a trifluoromethyl group is particularly preferable.
Examples of the perfluoroalkoxy group in X ¹ , X ² , X ³ , X ⁴ , Y ¹ and Y ² include those in which an oxygen atom (—O—) is bonded to the perfluoroalkyl group, and a trifluoromethoxy group Is particularly preferred.

In formula (1), X ¹ is preferably a fluorine atom.
X ² is preferably a fluorine atom, a trifluoromethyl group, or a perfluoroalkoxy group having 1 to 4 carbon atoms, and more preferably a fluorine atom or a trifluoromethoxy group.
X ³ and X ⁴ are each independently preferably a fluorine atom or a perfluoroalkyl group having 1 to 4 carbon atoms, and more preferably a fluorine atom or a trifluoromethyl group.
Preferable specific examples of compound (1) include compounds (1-1) to (1-5).

In formula (2), Y ¹ and Y ² are each independently preferably a fluorine atom, a C 1-4 perfluoroalkyl group or a C 1-4 perfluoroalkoxy group, and a fluorine atom or trifluoromethyl Groups are more preferred.
Preferable specific examples of compound (2) include compounds (2-1) to (2-2).

The fluorinated cyclic polymer (I) may be composed only of units formed by the cyclic fluorinated monomer, or may be a copolymer having the units and other units. Good.
However, the proportion of units based on the cyclic fluorinated monomer in the fluorinated cyclic polymer (I) is 20 mol% or more based on the total of all repeating units constituting the fluorinated cyclic polymer (I). Is preferable, 40 mol% or more is more preferable, and 100 mol% may be sufficient.
The other monomer is not particularly limited as long as it is copolymerizable with the cyclic fluorine-containing monomer. Specific examples include diene fluorine-containing monomers described later, monomers having a reactive functional group in the side chain, tetrafluoroethylene, chlorotrifluoroethylene, perfluoro (methyl vinyl ether), and the like.
A polymer obtained by copolymerization of a cyclic fluorine-containing monomer and a diene fluorine-containing monomer is considered as a fluorine-containing cyclic polymer (I).

The fluorinated cyclic polymer (II) has a unit formed by cyclopolymerization of a diene fluorinated monomer.
The “diene fluorine-containing monomer” is a monomer having two polymerizable double bonds and fluorine atoms. Although it does not specifically limit as this polymerizable double bond, A vinyl group, an allyl group, an acryloyl group, and a methacryloyl group are preferable.
As the diene fluorine-containing monomer, the following compound (3) is preferable.
_{CF 2 = CF-Q-CF} = CF 2 ··· (3).
In formula (3), Q may have an etheric oxygen atom, and a part of fluorine atoms may be substituted with a halogen atom other than fluorine atoms, preferably 1 to 5 carbon atoms, preferably 1 to 1 carbon atoms. 3 is a perfluoroalkylene group which may have a branch. Examples of halogen atoms other than fluorine include chlorine atom and bromine atom.
Q is preferably a perfluoroalkylene group having an etheric oxygen atom. In that case, the etheric oxygen atom in the perfluoroalkylene group may be present at one end of the group, may be present at both ends of the group, and is present between the carbon atoms of the group. You may do it. From the viewpoint of cyclopolymerizability, it is preferably present at one end of the group.

Specific examples of the compound (3) include the following compounds.
CF ₂ = CFOCF ₂ CF = CF ₂ ,
CF ₂ = CFOCF (CF ₃ ) CF═CF ₂ ,
CF ₂ = CFOCF ₂ CF ₂ CF = CF ₂ ,
CF ₂ = CFOCF ₂ CF (CF ₃ ) CF═CF ₂ ,
CF ₂ = CFOCF (CF ₃ ) CF ₂ CF = CF ₂ ,
CF ₂ = CFOCFClCF ₂ CF = CF ₂ ,
_{CF 2 = CFOCCl 2 CF 2 CF} = CF 2,
CF ₂ = CFOCF ₂ OCF = CF ₂ ,
_{CF 2 = CFOC (CF 3)} 2 OCF = CF 2,
CF ₂ = CFOCF ₂ CF (OCF ₃ ) CF═CF ₂ ,
CF ₂ = CFCF ₂ CF = CF ₂ ,
CF ₂ = CFCF ₂ CF ₂ CF = CF ₂ ,
_{CF 2 = CFCF 2 OCF 2 CF} = CF 2.

  Examples of the unit formed by the cyclopolymerization of the compound (3) include the following units (3-1) to (3-4).

The fluorinated polymer (a) preferably has a reactive functional group. Thereby, the effect of suppressing the attenuation of the surface potential due to the contact of the droplet is improved. The reactive functional group may be bonded to the end of the main chain of the fluoropolymer (a) or may be bonded to the side chain.
The “reactive functional group” is bonded by reacting with other components blended between the molecules of the fluoropolymer (a) or together with the fluoropolymer (a) when heating or the like is performed. Means a reactive group capable of forming.
For example, as the other component, a silane coupling agent described later or a compound having a molecular weight of 50 to 2,000 having two or more polar functional groups (excluding the silane coupling agent) (hereinafter referred to as a polyvalent polar compound). Is used as a material (a ′), the fluorine-containing polymer (a) has a reactive functional group capable of reacting with the functional group possessed by the silane coupling agent or the polar functional group possessed by the polyvalent polar compound. It is preferable to have.

As the reactive functional group possessed by the fluoropolymer (a), in view of ease of introduction into the polymer, strength of interaction with the silane coupling agent or the polyvalent polar compound, etc., a carboxy group And at least one selected from the group consisting of an acid halide group, an alkoxycarbonyl group, a carbonyloxy group, a carbonate group, a sulfo group, a phosphono group, a hydroxy group, a thiol group, a silanol group and an alkoxysilyl group.
Among the above, the fluoropolymer (a) preferably has a carboxy group or an alkoxycarbonyl group.

The relative dielectric constant of the fluoropolymer (a) is preferably 1.8 to 8.0, more preferably 1.8 to 5.0, still more preferably 1.8 to 3.0, and 1.8 to 2. 7 is particularly preferable, and 1.8 to 2.3 is most preferable. When the relative dielectric constant is not less than the lower limit of the above range, the amount of charge that can be stored as an electret is high, and when it is not more than the upper limit, the electrical insulation and the charge retention stability as an electret are excellent. The relative dielectric constant is measured at a frequency of 1 MHz in accordance with ASTM D150.
In addition, since the layer (A) is a part responsible for charge retention as an electret, the fluoropolymer (a) preferably has a high volume resistivity and a high dielectric breakdown strength.
The volume resistivity of the fluoropolymer (a) is preferably 10 ¹⁰ to 10 ²⁰ Ωcm, and more preferably 10 ¹⁶ to 10 ¹⁹ Ωcm. The volume resistivity is measured according to ASTM D257.
The dielectric breakdown strength of the fluoropolymer (a) is preferably 10 to 25 kV / mm, and more preferably 15 to 22 kV / mm. The dielectric breakdown strength is measured according to ASTM D149.
The refractive index of the fluoropolymer (a) is preferably 1.2 to 2.0 from the viewpoint of reducing the difference in refractive index with the substrate, suppressing light interference due to birefringence and the like, and ensuring transparency. 1.2 to 1.5 is more preferable.

The weight average molecular weight of the fluoropolymer (a) is preferably 50,000 or more, more preferably 150,000 or more, further preferably 200,000 or more, and particularly preferably 250,000 or more. When the weight average molecular weight is 50,000 or more, film formation is easy. In particular, when it is 200,000 or more, the heat resistance of the film is improved, and the thermal stability of the retained charge is improved when an electret is formed.
On the other hand, when the weight average molecular weight is too large, it is difficult to dissolve in a solvent, and there is a possibility that problems such as limitation of the film forming process may occur. Therefore, the weight average molecular weight of the fluoropolymer (a) is preferably 1 million or less, more preferably 850,000 or less, further preferably 650,000 or less, and particularly preferably 550,000 or less.

As the fluoropolymer (a), one synthesized by polymerizing the above-described monomers may be used, or a commercially available product may be used.
CYTOP (registered trademark, manufactured by Asahi Glass Co., Ltd.) is a commercially available fluoropolymer having a fluorine-containing aliphatic ring containing an etheric oxygen atom in the main chain and having a carboxy group or an alkoxycarbonyl group at the end of the main chain. Is mentioned.

[Material (a ′)]
As the material (a ′), as described above, a material obtained by mixing the fluorine-containing polymer (a) with other components other than the fluorine-containing polymer (a), the fluorine-containing polymer (a), and the fluorine-containing polymer Reaction products with other components other than the polymer (a), and the like can be mentioned.
As the reaction product, for example, when the coating liquid in which the fluoropolymer (a) and the other components are dissolved in a solvent is heated (such as baking when the solvent is evaporated to form a film), each component is What is produced | generated by reacting is mentioned.
As this other component, a silane coupling agent or a polyvalent polar compound is preferable, and a silane coupling agent is particularly preferable. Thereby, the charge retention performance (thermal stability of the retained charge, stability over time, etc.) of the electret formed is improved. This effect is particularly remarkable when the fluoropolymer (a) has a carboxy group or an alkoxycarbonyl group as a terminal group. This is because the fluorine-containing polymer (a) and the silane coupling agent or polyvalent polar compound cause nanophase separation, and a nanocluster structure derived from the silane coupling agent or polyvalent polar compound is formed. However, it is guessed that it is because it functions as a site | part which stores the electric charge in an electret.
In the material (a ′), the silane coupling agent or the polyvalent polar compound may be present in a state in which molecules react with each other.

It does not specifically limit as a silane coupling agent, It can utilize over a wide range including a conventionally well-known or well-known thing.
As the silane coupling agent, a silane coupling agent having an amino group is preferable.
Considering availability, etc., particularly preferred silane coupling agents are γ-aminopropylmethyldiethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, and N- (β-aminoethyl) -γ-aminopropyltriethoxy One or more selected from silane.

A silane coupling agent may be used individually by 1 type, and may use 2 or more types together.
0.1-20 mass% is preferable with respect to the total amount of a fluoropolymer (a) and a silane coupling agent, and, as for the compounding quantity of a silane coupling agent, 0.3-10 mass% is more preferable, 0.5-5 mass% is the most preferable. When it is in this range, it can be uniformly mixed with the fluoropolymer (a), and when each component is dissolved in a solvent to form a coating solution, phase separation is unlikely to occur.

The polyvalent polar compound is a compound having two or more polar functional groups and a molecular weight of 50 to 2,000 (excluding the silane coupling agent).
The “polar functional group” is a functional group having one or both of the following properties (1a) and (1b).
(1a) Two or more types of atoms having different electronegativity are included, and the functional group has polarity due to polarization.
(1b) Polarization is caused by the difference in electronegativity with carbon bonded to the functional group.

Specific examples of the polar functional group having only the above characteristic (1a) include a hydroxyphenyl group.
Specific examples of the polar functional group having only the characteristic (1b) include a primary amino group (—NH ₂ ), a secondary amino group (—NH—), a hydroxy group, and a thiol group.
Specific examples of the polar functional group having both the above characteristics (1a) and (1b) include sulfo group, phosphono group, carboxy group, alkoxycarbonyl group, acid halide group, formyl group, isocyanate group, cyano group, carbonyl group. And an oxy group (—C (O) —O—) carbonate group (—O—C (O) —O—).

  The molecular weight of the polyvalent polar compound is 50 to 2,000, preferably 100 to 2,000. When the molecular weight of the polyvalent polar compound is less than 50, the molecular weight is low, so that it easily volatilizes, and it is difficult to remain in the film after film formation. Moreover, when the molecular weight of the polyvalent polar compound is more than 2,000, layer separation from the fluoropolymer (a) is facilitated, and a problem is likely to occur in compatibility.

  Examples of the polyvalent polar compound include pentane-1,5-diamine, hexane-1,6-diamine, cyclohexane-1,2-diamine, cyclohexane-1,3-diamine, cyclohexane-1,4-diamine, and 1,2. -Diaminobenzene, 1,3-diaminobenzene, 1,4-diaminobenzene, triaminomethylamine, tris (2-aminoethyl) amine, tris (3-aminopropyl) amine, cyclohexane-1,3,5-triamine , Cyclohexane-1,2,4-triamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, 2,4,6-triaminotoluene, 1,3,5-tris (2 -Aminoethyl) benzene, 1,2,4-tris (2-aminoethyl) benzene, 2,4,6-tris (2-aminoethyl) to More preferred is at least one selected from the group consisting of ene, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and polyethyleneimine, and tris (2-aminoethyl) amine, tris (3-aminopropyl) amine, cyclohexane-1, Most preferred is at least one selected from the group consisting of 3-diamine, hexane-1,6-diamine, diethylenetriamine and polyethyleneimine.

A polyvalent polar compound may be used individually by 1 type, and may use 2 or more types together. For example, a compound having two polar functional groups and a compound having three or more polar functional groups may be mixed and used.
The blending amount of the polyvalent polar compound is preferably 0.01 to 30% by weight, more preferably 0.05 to 10% by weight, based on the blending amount of the fluoropolymer (a). The effect by mix | blending a polyvalent polar compound as this compounding quantity is 0.01 mass% or more is fully acquired. When the blending amount is 30% by mass or less, the miscibility with the fluoropolymer (a) is good, and the distribution in the coating liquid becomes uniform.

It does not specifically limit as a formation method of a layer (A), A well-known film forming method can be utilized. As a preferred formation method, a coating solution obtained by dissolving the fluoropolymer (a) in a solvent, or the fluoropolymer (a) and other components other than the fluoropolymer (a) are dissolved in a solvent. And a method of forming a coating film (layer (A)) using the coating liquid.
As said other component, as above-mentioned, a silane coupling agent or a polyvalent polar compound is preferable, and a silane coupling agent is especially preferable.

As the solvent, a solvent that dissolves at least the fluoropolymer (a) is used, and when it contains other components, the solvent that dissolves the fluoropolymer (a) dissolves the other components. If present, the solvent alone can be a uniform solution. Moreover, you may use together the other solvent which melt | dissolves this other component.
Specific examples of the solvent include a protic solvent, an aprotic solvent, and the like, and a solvent that dissolves a component to be blended in the coating liquid may be appropriately selected.
The “protic solvent” is a solvent having a proton donating property. An “aprotic solvent” is a solvent that does not have proton donating properties.

Examples of the protic solvent include the following protic non-fluorinated solvents and protic fluorinated solvents.
Methanol, ethanol, 1-propanol, isopropyl alcohol, 1-butanol, 2-butanol, t-butanol, pentanol, hexanol, 1-octanol, 2-octanol, ethylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene Protic non-fluorinated solvents such as glycol monobutyl ether, propylene glycol, and methyl lactate.
Protic fluorine-containing solvents such as 2- (perfluorooctyl) ethanol and other fluorine-containing alcohols, fluorine-containing carboxylic acids, amides of fluorine-containing carboxylic acids, and fluorine-containing sulfonic acids.

Examples of the aprotic solvent include the following aprotic non-fluorinated solvents and aprotic fluorinated solvents.
Hexane, cyclohexane, heptane, octane, decane, dodecane, decalin, acetone, cyclohexanone, 2-butanone, dimethoxyethane, monomethyl ether, ethyl acetate, butyl acetate, diglyme, triglyme, propylene glycol monomethyl ether monoacetate (PGMEA), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMA), N-methylpyrrolidone, tetrahydrofuran, anisole, dichloromethane, dichloroethane, chloroform, carbon tetrachloride, chlorobenzene, dichlorobenzene, benzene, toluene, xylene, ethylbenzene, Aprotic non-fluorine-containing solvents such as mesitylene, tetralin and methylnaphthalene.

  Polyfluoroaromatic compounds such as 1,4-bis (trifluoromethyl) benzene, polyfluorotrialkylamine compounds such as perfluorotributylamine, polyfluorocycloalkane compounds such as perfluorodecalin, perfluoro (2-butyltetrahydrofuran) Aprotic fluorine-containing solvents such as polyfluoro cyclic ether compounds such as), perfluoropolyethers, polyfluoroalkane compounds, and hydrofluoroethers (HFE).

Any one of these solvents may be used alone, or two or more thereof may be mixed and used. In addition to these, a wide range of compounds can be used.
Among these, the solvent used for dissolving the fluoropolymer (a) is preferably an aprotic fluorine-containing solvent because the solubility of the fluoropolymer (a) is large and a good solvent.
The solvent for dissolving the silane coupling agent or the polyvalent polar compound is preferably a protic fluorine-containing solvent.
The boiling point of the solvent is preferably 65 to 220 ° C., and preferably 100 to 220 ° C., because a uniform film can be easily formed during coating.

The solvent used for preparing the coating liquid preferably has a low water content. The water content is preferably 100 ppm or less, and more preferably 20 ppm or less.
The concentration of the fluoropolymer (a) in the coating liquid is preferably from 0.1 to 30% by mass, and more preferably from 0.5 to 20% by mass.
What is necessary is just to set the solid content concentration of a coating liquid suitably according to the film thickness to form. Usually, it is 0.1-30 mass%, and 0.5-20 mass% is preferable.
The solid content is calculated by heating the coating liquid whose mass was measured at 200 ° C. for 1 hour under normal pressure to distill off the solvent and measuring the mass of the remaining solid content.

The coating liquid may be obtained by preparing a composition containing each component in advance and dissolving it in a solvent, or by dissolving each component in a solvent and mixing each solution.
As a method for producing the composition in the case of preparing a composition containing each component in advance, the solid and the solid, or the solid and the liquid may be mixed by kneading, eutectic extrusion, etc. Each solution dissolved in may be mixed. Among these, it is more preferable to mix each solution.
For example, when the fluoropolymer (a) and a silane coupling agent are used in combination, the coating liquid comprises a polymer solution obtained by dissolving the fluoropolymer (a) in an aprotic fluorine-containing solvent, and a silane coupling agent. A silane coupling agent solution dissolved in a protic fluorine-containing solvent is preferably prepared, and the polymer solution and the silane coupling agent solution are preferably mixed. The aprotic fluorinated solvent and the protic fluorinated solvent will be described later.

The coating film can be formed, for example, by coating the surface of the substrate with a coating liquid and drying it by baking or the like.
As the coating method, a conventionally known method for forming a film from a solution can be used and is not particularly limited. Specific examples of such a method include a spin coating method, a roll coating method, a casting method, a dipping method, a water casting method, a Langmuir-Blodget method, a die coating method, an ink jet method, and a spray coating method. Printing techniques such as letterpress printing, gravure printing, lithographic printing, screen printing, and flexographic printing can also be used.
Drying may be performed by air drying at normal temperature, but is preferably performed by heating and baking. The baking temperature is preferably equal to or higher than the boiling point of the solvent, and particularly at a high temperature of 230 ° C. or higher, the reaction between the added silane coupling agent or polyvalent polar compound and the polymer (a) is sufficiently completed. Particularly preferred in terms.

<Layer (B)>
The layer (B) contains a non-fluorinated polymer (b) having an aliphatic ring in the main chain or a material (b ′) derived from the non-fluorinated polymer (b). Thereby, attenuation of the surface potential due to the contact of the droplet can be suppressed.
Examples of the material (b ′) include a material obtained by mixing the non-fluorinated polymer (b) with other components other than the non-fluorinated polymer (b), the non-fluorinated polymer (b) and the non-fluorinated polymer ( Reaction products with other components other than b) and the like. When the layer (B) contains the reaction product, the fluoropolymer (b) used for forming the reaction product or a part of other components remains unreacted in the layer (B). It may remain. Details of the material (b ′) will be described later.

[Non-fluorinated polymer (b)]
The non-fluorinated polymer (b) is a non-fluorinated polymer having an aliphatic ring in the main chain.
Here, the “non-fluorinated polymer” is a polymer having no fluorine atom in its structure.
The explanation of “having an aliphatic ring in the main chain” and “aliphatic ring” is as described for the fluoropolymer (a). However, the aliphatic ring in the non-fluorinated polymer (b) is a non-fluorinated aliphatic ring.
Specific examples of the non-fluorinated aliphatic ring include a saturated or unsaturated aliphatic hydrocarbon ring, and a fatty acid in which a part of carbon atoms in the aliphatic hydrocarbon ring is substituted with a hetero atom such as an oxygen atom or a nitrogen atom. Group heterocycle and the like. Among these, an aliphatic hydrocarbon ring is preferable and a saturated aliphatic hydrocarbon ring is preferable.
The non-fluorinated aliphatic ring may have a substituent other than the fluorine-containing group.

  In the present invention, the non-fluorinated polymer (b) is preferably a non-fluorinated polymer in which at least two carbon atoms constituting the non-fluorinated aliphatic ring are incorporated in the main chain. Examples of the non-fluorinated polymer include those having the following unit (b1).

［式中、Ｒ”は置換基を有していてもよい２価の炭化水素基であり、ｍは０〜１０の整数であり、ｒは０または１であり、ｓは０または１である。］

[Wherein R ″ is a divalent hydrocarbon group which may have a substituent, m is an integer of 0 to 10, r is 0 or 1, and s is 0 or 1. .]

In formula (b1), the hydrocarbon group represented by R ″ may be linear, branched or cyclic. The hydrocarbon group may be saturated or unsaturated. It is preferable that it is saturated.
As the linear or branched hydrocarbon group, an alkylene group having 1 to 4 carbon atoms is preferable, and a linear group is particularly preferable.
The cyclic hydrocarbon group is preferably a group obtained by removing two hydrogen atoms from a monocyclic or polycyclic cycloalkane which may have a substituent. As the monocyclic cycloalkane, a cycloalkane having 5 to 8 carbon atoms such as cyclopentane and cyclohexane is preferable. As the polycyclic cycloalkane, a cycloalkane having 7 to 12 carbon atoms is preferable, and specific examples include norbornane and adamantane. Among these, cyclopentane or norbornane is preferable.

Examples of the substituent that the hydrocarbon group of R ″ may have include an alkyl group, a cycloalkyl group, an alkoxy group, an aryl group such as a phenyl group, and a polycyclic aliphatic hydrocarbon group such as an adamantyl group. Can be mentioned.
The alkyl group as a substituent may be linear or branched, and preferably has 1 to 10 carbon atoms, more preferably 1 to 3 carbon atoms. The alkyl group is preferably a methyl group, an ethyl group, a propyl group, or an isopropyl group, more preferably a methyl group or an ethyl group, and particularly preferably a methyl group.
The cycloalkyl group as a substituent preferably has 3 to 10 carbon atoms, and more preferably 5 to 8 carbon atoms. As the cycloalkyl group, a cyclopentyl group or a cyclohexyl group is particularly preferable.
Examples of the alkoxy group as a substituent include those in which an oxygen atom (—O—) is bonded to the alkyl group.

M is an integer of 0-10 in a formula (b1).
When m is an integer of 1 or more, as in the unit (b1-1) described later, the polymer main chain is not an ortho position of the aliphatic hydrocarbon ring, and is bonded with an interval of one or more methylene groups. The aliphatic hydrocarbon ring is incorporated into the polymer main chain.
When m is 0, the aliphatic hydrocarbon ring is incorporated into the polymer main chain by bonding the polymer main chain to the ortho position of the aliphatic hydrocarbon ring as in the unit (b1-2) described later. Yes.
As m, 1-3 are preferable and 1 is the most preferable.

r and s may each be 0 or 1. When m is 0, r and s are preferably 0. When m is 1, r and s are preferably 1.
As the unit (b1), the following unit (b1-1) or unit (b1-2) is preferable.

［式（ｂ１−１）中、Ｒ^１およびＲ^２はそれぞれ独立に、水素原子、アルキル基またはシクロアルキル基であり、Ｒ^１およびＲ^２が相互に結合して環を形成していてもよい。式（ｂ１−２）中、Ｒ^３およびＲ^４はそれぞれ独立に、水素原子、アルキル基またはシクロアルキル基であり、Ｒ^３およびＲ^４が相互に結合して環を形成していてもよい。］

[In Formula (b1-1), R ¹ and R ² are each independently a hydrogen atom, an alkyl group or a cycloalkyl group, and R ¹ and R ² may be bonded to each other to form a ring. . In formula (b1-2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group, or a cycloalkyl group, and R ³ and R ⁴ may be bonded to each other to form a ring. ]

In formula (b1-1), as the alkyl group and cycloalkyl group in R ¹ and R ^2, the alkyl group and cycloalkyl group mentioned as the substituents that the hydrocarbon group of R ″ may have, respectively. The same thing is mentioned.
As the ring formed by bonding R ¹ and R ² to each other, a monocyclic or polycyclic cycloalkane is preferable. As the monocyclic cycloalkane, a cycloalkane having 5 to 8 carbon atoms such as cyclopentane and cyclohexane is preferable. As the polycyclic cycloalkane, a cycloalkane having 7 to 12 carbon atoms is preferable, and specific examples include norbornane and adamantane. Among these, cyclopentane or norbornane is preferable.
The ring may have a substituent. Examples of the substituent include the same groups as those described above as the substituent that the hydrocarbon group of R ″ may have.

Specific examples of the unit (b1-1) when R ¹ and R ² are bonded to each other to form a ring include the following unit (b1-11) and unit (b1-12).
In formula (b1-12), examples of the alkyl group for R ¹¹ include the same alkyl groups as those described above for the substituent that the hydrocarbon group for R ″ may have.

［式（ｂ１−１２）中、Ｒ^１１は水素原子またはアルキル基である。］

[In the formula (b1-12), R ¹¹ represents a hydrogen atom or an alkyl group. ]

In formula (b1-2), R ³ and R ⁴ are the same as R ¹ and R ² , respectively.
Specific examples of the unit (b1-2) in the case where R ³ and R ⁴ are bonded to each other to form a ring include the following units (b1-21) and units (b1-22).
As the alkyl group for R ^13, the same alkyl groups as those described above for the substituent that the hydrocarbon group for R ″ may have may be mentioned.

［式（ｂ１−２２）中、Ｒ^１３は水素原子またはアルキル基である。］

[In formula (b1-22), R ¹³ represents a hydrogen atom or an alkyl group. ]

The non-fluorinated polymer (b) may contain any one of the above units as the unit (b1), or may contain two or more types.
In the non-fluorinated polymer (b), the proportion of the unit (b1) is preferably 30 mol% or more, more preferably 40 mol% or more with respect to the total of all repeating units constituting the non-fluorinated polymer (b). More preferably, it may be 100 mol%.

The non-fluorinated polymer (b) may contain a unit other than the unit (b1) (hereinafter sometimes referred to as a unit (b2)).
As the unit (b2), a known unit conventionally known as a unit that forms a copolymer with the unit (b1) can be used, and is not particularly limited.
The unit (b2) is preferably a unit based on an olefin which may have a substituent. Examples of the unit include the following unit (b2-1).
In formula (b2-1), examples of the alkyl group for R ⁵ include the same alkyl groups as those described above as the substituent that the hydrocarbon group for R ″ may have.

［式（ｂ２−１）中、Ｒ^５は水素原子またはアルキル基である。］

[In Formula (b2-1), R ⁵ represents a hydrogen atom or an alkyl group. ]

As the non-fluorinated polymer (b), the following non-fluorinated polymer (I) and non-fluorinated polymer (II) are particularly preferable.
Non-fluorinated polymer (I): a non-fluorinated polymer having the unit (b1-1).
Non-fluorinated polymer (II): a non-fluorinated polymer having the unit (b1-2) and the unit (b2).
The non-fluorinated polymer (I) may contain units other than the unit (b1-1) as long as the effects of the present invention are not impaired.
The non-fluorinated polymer (II) may contain units other than the unit (b1-2) and the unit (b2) as long as the effects of the present invention are not impaired.

Non-fluorinated polymer (I) may have 1 type as a unit (b1-1), and may have 2 or more types.
In the present invention, it is particularly preferable that the unit (b1-1) has a unit in which R ¹ and R ² are bonded to each other to form a ring. Especially, it is preferable to have a unit (b1-12).
When the unit (b1-1) has a unit in which R ¹ and R ² are bonded to each other to form a ring, the non-fluorinated polymer (I) is further converted into a unit (b1-1). And R ¹ and R ² preferably have a unit which is not bonded to each other to form a ring (hereinafter referred to as unit (b1-13)).
As the unit (b1-13), ^one in which at least one of R ¹ and R ² is a hydrogen atom is preferable, and ^one in which both R ¹ and R ² are hydrogen atoms is particularly preferable.

The Tg of the non-fluorinated polymer (b) is preferably 100 to 160 ° C. from the viewpoint of ease of film formation when the film is formed on the fluoropolymer (a) forming the layer (A). -150 degreeC is more preferable.
In the non-fluorinated polymer (I), the ratio (molar ratio) between the unit (b1-12) and the unit (b1-13) is preferably 10:90 to 100: 0 from the viewpoint of adjusting the Tg, 40: 60-80: 20 is preferable.

  In the non-fluorinated polymer (I), the proportion of the unit (b1-1) is preferably 80 mol% or more, and 90 mol% with respect to the total of all repeating units constituting the non-fluorinated polymer (I). The above is more preferable, and 100 mol% is particularly preferable. That is, as the non-fluorinated polymer (I), a polymer composed only of the unit (b1-1) is particularly preferable. Especially, what consists of a unit (b1-12) and a unit (b1-13) is preferable.

The non-fluorinated polymer (II) may contain one type or two or more types as the unit (b1-2) and the unit (a2), respectively.
In the non-fluorinated polymer (II), the proportion of the unit (b1-2) is preferably 20 to 70 mol% with respect to the total of all repeating units constituting the non-fluorinated polymer (II), and 30 to 50 mol% is more preferable. Moreover, 30-80 mol% is preferable with respect to the sum total of all the repeating units which comprise the said non-fluoropolymer (II), and, as for the ratio of a unit (a2), 50-70 mol% is more preferable.
Moreover, the ratio (molar ratio) of the content of the unit (b1-2) and the unit (a2) in the non-fluorinated polymer (II) is unit (b1-2): unit (a2) = 20: 80 to The range of 70:30 is preferable, and the range of 30:70 to 50:50 is more preferable.
Preferable specific examples of the non-fluorinated polymer (II) include copolymers containing two types of units represented by the following formulas (II-1) and (II-2), respectively.

［式中、Ｒ^１３、Ｒ^５はそれぞれ前記と同じである。］

[Wherein, R ¹³ and R ⁵ are the same as defined above. ]

The non-fluorinated polymer (b) may have a reactive functional group. The reactive functional group may be bonded to the end of the main chain of the fluoropolymer (a) or may be bonded to the side chain.
Examples of the reactive functional group are the same as those described in the description of the fluoropolymer (a).
The reactive functional group possessed by the non-fluorinated polymer (b) includes an alkoxycarbonyl group (also referred to as an ester group), a carboxy group, a carboxylic acid halide group, an amide group, a hydroxyl group, an amino group, a sulfonic acid group, and a sulfonic acid. An ester group, a sulfonamide group, a thiol group, a cyano group and the like are preferable, and a carboxy group or an alkoxycarbonyl group is particularly preferable.

In the case where the main chain terminal or side chain has a carboxy group, a silane compound may be bonded to the carboxy group.
The silane compound can be bonded to the carboxy group by reacting, for example, a non-fluorinated polymer having a carboxy group at the main chain terminal or side chain with a silane coupling agent as described later.

As the non-fluorinated polymer having a reactive functional group such as an alkoxycarbonyl group or a carboxy group at the main chain terminal or side chain, for example, the non-fluorinated polymer is selected from the group consisting of unsaturated carboxylic acids and derivatives thereof. And a modified polymer compound obtained by graft copolymerization of the modified monomer.
Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, nadic acid, methyl nadic acid and the like.
Examples of the unsaturated carboxylic acid derivatives include acid halides, amides, imides, acid anhydrides, esters, and the like of the unsaturated carboxylic acids. Specific examples include maleenyl chloride, maleic anhydride, citraconic anhydride, maleic acid. Examples thereof include methyl and dimethyl maleate.

The relative dielectric constant of the non-fluorinated polymer (b) is not particularly limited, but is excellent in the effect of suppressing the attenuation of the surface potential due to droplets. The relative dielectric constant of the combined (a)] is preferably 0.1 or more and less than 0.5, and more preferably 0.1 or more and less than 0.3.
The Tg of the non-fluorinated polymer (b) is preferably from 100 to 160 ° C, more preferably from 120 to 150 ° C, from the viewpoint of the ease of forming a laminated film with the fluoropolymer (a).
The refractive index of the non-fluorinated polymer (b) is 1.3 to 2 from the viewpoint of reducing the difference in refractive index from the substrate and the layer (A), suppressing light interference due to birefringence and the like, and ensuring transparency. 0.0 is preferable, and 1.4 to 1.7 is more preferable.

As the non-fluorinated polymer (b), a synthesized one or a commercially available one may be used. The non-fluorinated polymer (b) can be synthesized by a known method. For example, the following (1) to (7) are known as a synthesis method of the non-fluorinated polymer having the unit (b1).
(1) A method of addition copolymerization of norbornenes and olefin (for example, a method shown in the following reaction formula (1 ′)).
(2) A method of hydrogenating a ring-opening metathesis polymer of norbornene (for example, a method shown in the following reaction formula (2 ′)).
(3) A method of transannular polymerization of alkylidene norbornene (for example, a method shown in the following reaction formula (3 ′)).
(4) A method of addition polymerization of norbornene (for example, a method shown in the following reaction formula (4 ′)).
(5) A method of hydrogenating 1,2- and 1,4-addition polymers of cyclopentadiene (for example, a method shown in the following reaction formula (5 ′)).
(6) A method of hydrogenating 1,2- and 1,4-addition polymers of cyclohexadiene (for example, a method shown in the following reaction formula (6 ′)).
(7) A method of cyclopolymerizing a conjugated diene (for example, a method shown in the following reaction formula (7 ′)).

In each reaction formula, R ^{1 to} R ⁵ are the same as described above.
R ^{6 to} R ⁷ are each independently an alkyl group, and examples of the alkyl group include the same alkyl groups listed as the substituents that the hydrocarbon group of R may have.

Among these, cycloolefin polymers obtained by the method (1) (addition copolymers of norbornenes and olefins) and cycloolefin polymers obtained by the method (2) (ring-opening metathesis polymers of norbornenes) Hydrogenated polymer) is preferred from the viewpoint of excellent film forming property and easy synthesis.
Examples of the norbornene addition copolymer include those sold under the trade names of Apel (registered trademark) (manufactured by Mitsui Chemicals) and TOPAS (registered trademark) (manufactured by Ticona).
In addition, as the hydrogenated polymer of the ring-opening metathesis polymer of norbornene, there are various types, but since it has transparency, low moisture absorption, and heat resistance, ZEONEX (registered trademark) (manufactured by Nippon Zeon Co., Ltd.), Polymers sold under the trade names of ZEONOR (registered trademark) (manufactured by Nippon Zeon) and Arton (registered trademark) (manufactured by JSR) are preferred.

[Material (b ')]
As the material (b ′), as described above, the non-fluorinated polymer (b) is mixed with other components other than the non-fluorinated polymer (b), the non-fluorinated polymer (b) and the non-fluorinated polymer (b). Examples include reaction products with other components other than the fluoropolymer (b).
As the reaction product, for example, when the coating solution in which the non-fluorinated polymer (b) and the other components are dissolved in a solvent is heated (baking for forming a film by evaporating the solvent, etc.) Are produced by reaction.
As the other component, like the material (a ′), a silane coupling agent or a polyvalent polar compound is preferable, and a silane coupling agent is particularly preferable.
In the material (b ′), the silane coupling agent or the polyvalent polar compound may exist in a state in which molecules react with each other.

The formation method of a layer (B) is not specifically limited, A well-known film forming method can be utilized. For example, it can be formed by the same procedure as the layer (A) except that the non-fluorinated polymer (b) is used instead of the fluoropolymer (a). That is, it can be formed by preparing a coating liquid, coating the surface of the layer (A) with the coating liquid, and drying by baking or the like.
As a solvent used for the preparation of the coating liquid, a solvent capable of dissolving the components blended in the coating liquid may be appropriately selected from the above-mentioned protic solvents and aprotic solvents.
The solvent that dissolves the non-fluorinated polymer (b) is preferably an aprotic solvent, more preferably a hydrocarbon, and aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, mesitylene, tetralin, and methylnaphthalene. Are more preferable, and toluene and xylene are particularly preferable.

<Layer (C)>
The layer (C) contains a fluoropolymer (c) having an aliphatic ring in the main chain or a material (c ′) derived from the fluoropolymer (c). By providing the layer (C), the resistance to the droplets can be improved with almost no loss of transparency.
Examples of the fluoropolymer (c) and the material (c ′) are the same as those of the fluoropolymer (a) and the material (a ′), respectively. The layer (C) can be formed in the same procedure as the layer (A).
In the present invention, the material constituting the layer (A) may be the same or different. For example, the fluoropolymer (a) and the fluoropolymer (c) may be the same or different. In addition, the layer (A) may include the material (a ′), the layer (C) may not include the material (c ′), the layer (A) may not include the material (a ′), and the layer (C) May include material (c ′).

When the electret used in the present invention is formed by injecting a charge into a laminate in which the layer (A) and the layer (B) are laminated in this order, the above-mentioned fluorine-containing cyclic polymer ( A combination of the above-mentioned non-fluorinated polymer (I) as a material obtained by mixing a silane coupling agent or a polypolar compound with II) or the fluorinated cyclic polymer (II) and the layer (B) is preferable. When the above-mentioned polymer is used for the layer (A) and the layer (B), not only is the surface potential attenuated by contact with the droplet 7 over a long period of time, but also excellent in transparency in visible light, Further, this combination is preferable because the difference in refractive index between the two layers is small, and interference fringes due to birefringence and the like are unlikely to occur.
When the electret used in the present invention is formed by injecting a charge into a laminate in which the layer (A), the layer (B), and the layer (C) are laminated in this order, the layer (A) is described above. A fluorine-containing cyclic polymer (II) or a material obtained by mixing a fluorine-containing cyclic polymer (II) with a silane coupling agent or a polypolar compound, and the layer (B) as the non-fluorinated polymer (I), (C) is preferably a combination of the above-mentioned fluorine-containing cyclic polymer (II) or a material obtained by mixing a fluorine-containing cyclic polymer (II) with a silane coupling agent or a polypolar compound. When the layer (A), the layer (B), and the layer (C) are used in the above combination, attenuation of the surface potential due to contact with the droplet 7 is suppressed over a long period of time, and the transparency in visible light is excellent. Further, since the difference in refractive index between the three layers is small, not only interference fringes due to birefringence or the like are not easily generated, but also the solvent resistance is high, and the film thickness reduction due to contact with the droplets 7 can be suppressed.

Specific examples of the above embodiment will be described below as examples. The present invention is not limited to the following examples.
The relative dielectric constant of the material used in each of the following examples is a value measured at a frequency of 1 MHz in accordance with ASTM D150.
The volume specific resistance value is a value measured according to ASTM D257.
The dielectric breakdown voltage is a value measured according to ASTM D149.
The intrinsic viscosity [η] (30 ° C.) (unit: dl / g) is a value measured by an Ubbelohde viscometer at 30 ° C. using perfluoro (2-butyltetrahydrofuran) as a solvent.
The weight average molecular weight (Mw) of the polymer of perfluorobutenyl vinyl ether is described in Journal of Chemical Society of Japan, 2001, NO. 12, p. This is a value calculated from the intrinsic viscosity [η] measured above using the relational expression ([η] = 1.7 × 10 ⁻⁴ × Mw ^0.60 ) between [η] and Mw described in 661.
In each of the following examples, a low-resistance silicon substrate (volume specific resistance value of 0.003 to 0.007 Ωcm) was used as a substrate for forming the electret. Hereinafter, the low-resistance silicon substrate is referred to as a “silicon substrate”.
In each of the following examples, the film thickness was measured using a light interference type film thickness measuring device C10178 manufactured by Hamamatsu Photonics.

[Production Example 1: Preparation of polymer solution P1]
45g of perfluoro butenyl vinyl ether _{(CF 2 = CFOCF 2 CF 2} CF = CF 2), ion exchange water 240 g, methanol 16g, and as a polymerization initiator, diisopropyl peroxydicarbonate powder _{(((CH 3) 2} 0.2 g of CHOCOO) ₂ ) was placed in a pressure-resistant glass autoclave having an internal volume of 1 L. After the inside of the system was replaced with nitrogen three times, suspension polymerization was performed at 40 ° C. for 23 hours. As a result, 40 g of polymer A1 was obtained.
Measurement of the infrared absorption spectrum of the polymer A1, ^{1660 cm} -1 attributable to the double bond that is present in the monomer, absorption near 1840cm ^-1 was not confirmed.

The polymer A1 was heat treated in air at 250 ° C. for 8 hours and then immersed in water to obtain a polymer A2 having —COOH groups as terminal groups.
The intrinsic viscosity [η] (30 ° C.) of the polymer A2 is 0.24 dl / g, the Mw obtained from the intrinsic viscosity [η] is 177,000, the volume resistivity is> 10 ¹⁷ Ωcm, the dielectric breakdown voltage Was 19 kV / mm and the relative dielectric constant was 2.1. Moreover, as a result of measuring the infrared absorption spectrum of the compression molding film of polymer A2, characteristic absorption of 1775 cm < ^-1 > and 1810 cm < ^-1 > originating in -COOH group was recognized. Further, when differential scanning calorimetry (DSC) was performed on the polymer A2, the glass transition temperature (Tg) was 108 ° C. Further, in the compression-molded film of the polymer A2, the refractive index (hereinafter sometimes referred to as “n _D ”) measured with an Abbe refractometer using the D line (wavelength 589 nm) was 1.34.
The polymer A2 was dissolved in perfluorotributylamine at a concentration of 15% by mass to obtain a polymer solution P1.

[Production Example 2: Preparation of polymer composition solution M1]
A solution obtained by adding 10.6 g of perfluorotributylamine to 84.6 g of the polymer solution P1 and 0.4 g of γ-aminopropylmethyldiethoxysilane are added to 4.7 g of 2- (perfluorohexyl) ethanol. The dissolved silane coupling agent solution was uniformly mixed to obtain a polymer composition solution M1.

[Production Example 3: Production of electret A]
(1) Film formation of laminated film A:
A 3 cm square, 350 μm thick silicon substrate was coated with the polymer composition solution M1 by spin coating, then baked at 200 ° C. and dried to form a 15 μm thick coating film (hereinafter “coating film”). Also referred to as “A1”). Next, using a SAMCO International Institute Inc. REACTIVE ION ETCHING SYSTEM RIE-10NR, it was _{N 2} plasma treatment on the surface of the coating film A1. Subsequently, a 15% by mass m-xylene solution of a cycloolefin polymer (ZEONEX 480 manufactured by Nippon Zeon Co., Ltd., relative dielectric constant 2.3, glass transition temperature 138 ° C., refractive index n _D = 1.53) is formed on the coating film A1. Coating was performed by a spin coating method. Thereafter, by baking at 160 ° C. for 1 hour and drying, a laminated film A having a total film thickness of 20 μm [from the substrate side, layer (A): 15 μm / layer (B): two layers laminated in the order of 5 μm. Body].

(2) Charge injection by corona charging:
The obtained laminated film A was electret A by injecting electric charge by corona discharge. Charge injection was performed by the following procedure using a corona charging apparatus whose schematic configuration is shown in FIG. 3 at 120 ° C. under the conditions of a charging voltage of −8 kV and a charging time of 3 minutes. That is, using a substrate (silicon substrate in this example) (10) as an electrode, a DC high voltage power supply device (12) (HAR-20R5; manufactured by Matsusada Precision Co., Ltd.) is used between the corona needle (14) and the substrate (10). By applying a high voltage of −8 kV to the substrate, charges were injected into the laminate (11) formed on the substrate (10). In this corona charging device, the negative ions discharged from the corona needle (14) are made uniform by the grid (16), and then dropped onto the laminate (11) to inject charges. A voltage of −1,200 V was applied to the grid (16) from the grid power supply (18).

(3) Measurement of surface potential:
About electret A immediately after inject | pouring an electric charge by corona charge, it returned to normal temperature (25 degreeC), and the surface potential (initial surface potential) was measured. Moreover, after each electret was stored at 20 ° C. and 60% RH for a certain period of time, the surface potential (surface potential before immersion test) was measured by returning to normal temperature immediately before performing Test Example 1 (solvent immersion test) described later. . The results are shown in Table 1.
The surface potential (V) is a surface potential meter (model 279, manufactured by Monroe Electronics Co., Ltd.), and the surface potential of nine measurement points of each electret (set in a grid pattern every 3 mm from the center of the membrane, see FIG. 4). Were measured and obtained as an average value thereof.

[Production Example 4: Production of electret B]
A coating film A2 having a thickness of 15 μm was formed on a 3 cm square, 350 μm thick silicon substrate in the same manner as in Production Example 3 except that the polymer solution P1 was used instead of the polymer composition solution M1. Next, N ₂ plasma treatment was performed on the surface of the coating film A2 by the same procedure as in Production Example 3. Subsequently, a cycloolefin polymer film is formed on the coating film A2 with a film thickness of 5 μm, and a laminated film B having a total film thickness of 20 μm [from the substrate side, layer (A2): 15 μm / layer (B): 5 μm in this order. To obtain a two-layer laminate].
Electric charges were injected into this laminated film B by the same procedure as in Production Example 3 to obtain electret B, and the initial surface potential and the surface potential before the immersion test were measured. The results are shown in Table 1.

[Production Example 5: Production of electret C]
A coating film A1 having a film thickness of 15 μm was formed on a 3 cm square silicon substrate having a thickness of 350 μm in the same manner as in Production Example 3. Next, N ₂ plasma treatment was performed on the surface of the coating film A1 by the same procedure as in Example 1. Subsequently, in the same manner as in Production Example 3, a cycloolefin polymer film was formed with a film thickness of 5 μm on the coating film A1 to obtain a laminated film having a total film thickness of 20 μm. Furthermore, the polymer composition solution M1 was coated on the laminated film by a spin coating method. Then, by baking at 200 ° C. and drying, a laminated film C having a total film thickness of 21 μm [from the substrate side, layer (A): 15 μm / layer (B): 5 μm / layer (C): laminated in the order of 1 μm. A three-layer laminate] was obtained.
Electric charges were injected into this laminated film C by the same procedure as in Production Example 3 to obtain electret C, and the initial surface potential and the surface potential before the immersion test were measured. The results are shown in Table 1.

[Production Example 6: Production of electret D]
A coating film A1 having a film thickness of 15 μm was formed on a 3 cm square silicon substrate having a thickness of 350 μm in the same manner as in Production Example 3.
Electric charges were injected into this coating film A1 by the same procedure as in Production Example 3 to obtain electret D, and the initial surface potential and the surface potential before the immersion test were measured. The results are shown in Table 1.

[Production Example 7: Production of electret E]
A coating film A1 having a film thickness of 15 μm was formed on a 3 cm square silicon substrate having a thickness of 350 μm in the same manner as in Production Example 3. Next, a polyparaxylylene resin (trade name: Parylene-C, manufactured by Japan Parylene Co., Ltd., relative dielectric constant 2.95, glass transition temperature 87-97 ° C., refractive index n _D = 1.64 is formed on the coating film A1. ) By chemical vapor deposition using a CVD method, and a laminated film E having a total film thickness of 20 μm [a two-layer laminate in which layers (A): 15 μm / layer (B): 5 μm are laminated in this order from the substrate side] Got.
Electric charges were injected into this laminated film E by the same procedure as in Production Example 3 to obtain electret E, and the initial surface potential and the surface potential before the immersion test were measured. The results are shown in Table 1.

[Production Example 8]
The laminated film E obtained in the same manner as in Production Example 7 was coated with the polymer composition solution M1 by a spin coating method, baked at 200 ° C. and dried to obtain a layer (B) (polyparaxylylene resin). As a result, a three-layer laminate could not be formed successfully.

[Production Example 9: Production of electret F]
A coating film A1 having a film thickness of 15 μm was formed on a 3 cm square silicon substrate having a thickness of 350 μm in the same manner as in Production Example 3. Next, N ₂ plasma treatment was performed on the surface of the coating film A1 by the same procedure as in Production Example 3. Subsequently, 12% by mass N-methylpyrrolidone of polyamic acid (trade name: Semicofine SP483, manufactured by Toray Industries, Inc., relative dielectric constant after polyimideization, 3.75, glass transition temperature 350 ° C. or higher) on the coating film A1 ( NMP) solution was coated by spin coating. Then, it heat-processed at 200 degreeC for 5 hours, and it was made into polyimide, the polyimide film with a film thickness of 5 micrometers was formed, and the laminated film with a total film thickness of 20 micrometers was obtained. Furthermore, the polymer composition solution M1 was coated on the laminated film by a spin coating method. Thereafter, by baking at 200 ° C. and drying, a laminated film F having a total film thickness of 21 μm [from the substrate side, layer (A): 15 μm / layer (B): 5 μm / layer (C): laminated in the order of 1 μm. A three-layer laminate] was obtained.
Electric charges were injected into this laminated film F by the same procedure as in Production Example 3 to obtain electret F, and the initial surface potential and the surface potential before the immersion test were measured. The results are shown in Table 1.

[Test Example 1: Solvent immersion test]
The dipping liquid shown in Table 1 was filled in a petri dish, and the electrets A to F obtained above were dipped in the dipping liquid. The sample was left as it was for 25 hours and pulled up from the immersion liquid, and then the surface potential was measured by the same procedure as described above. From the measured value (surface potential after 25 hours of immersion) and the surface potential before immersion test, the residual ratio of the surface potential (surface potential after 25 hours of immersion / surface potential before immersion test × 100 (%)) was determined. The results are shown in Table 1.
The electret having the residual ratio of 70% or more was immersed again in the immersion liquid and left as it was for 105 hours (total 130 hours). Thereafter, the liquid was pulled up from the immersion liquid, and the surface potential (surface potential after 130 hours of immersion) was measured in the same procedure as described above to determine the residual ratio of the surface potential. In addition, the film surface state of the electret (presence or absence of film peeling, presence or absence of film reduction) was observed. The results are shown in Table 1.
Among the electrets used in each example, electrets A to C correspond to the electrets used in the present invention.

From the results of Examples 1-1 to 1-6, when hexadecane was used as the immersion liquid, the surface potential of the electret D (Example 1-4) having only the layer (A) was significantly lowered after 25 hours of immersion. For the electrets A (Example 1-1) and B (Example 1-2) of the two-layer laminate, a layer containing a non-fluorinated polymer (b) having an aliphatic ring in the main chain was used as the layer (B). As a result, the residual rate of the surface potential after 25 hours and 130 hours after immersion was improved. Electret E (Example 1-5) is also a two-layer laminate, but the layer containing the non-fluorinated polymer (b) having an aliphatic ring in the main chain was not used as the layer (B). Compared with 1-1) and B (Example 1-2), the residual rate of the surface potential after 130 hours of immersion was low.
A three-layer electret C (Example 1-3) is a layer containing a non-fluorinated polymer (b) having an aliphatic ring in the main chain as the layer (B), and an aliphatic in the main chain as the layer (C). By using the layer containing the fluorine-containing polymer (c) having a ring, the residual rate of the surface potential after immersion for 25 hours and after 130 hours was improved as compared with electret D (Example 1-4). In particular, by using a three-layer laminate, the surface potential remaining rate after immersion for 25 hours and after 130 hours improved more than electret A having the same configuration up to two layers. As described above, it was confirmed that the electret C (Example 1-3) was particularly excellent in resistance to hexadecane because neither peeling of the film nor reduction of the film thickness due to immersion in the immersion liquid was observed. The electret F of the three-layer laminate did not use a layer containing a non-fluorinated polymer (b) having an aliphatic ring in the main chain as the layer (B), so compared with the electret C (Example 1-3) The residual rate of the surface potential after 25 hours of immersion was low.
Further, from the results of Examples 1-1 and 1-7 to 1-10, Example 1-1 and Example 1-7 in which the droplets are alkanes having 10 to 17 carbon atoms were obtained after immersion for 25 hours and after 130 hours. The residual rate of surface potential was improved. On the other hand, in Examples 1-8 to 10, in which the droplets were not alkanes having 10 to 17 carbon atoms, the residual ratio of the surface potential after 25 hours and 130 hours after immersion decreased. It has been confirmed that the electret using a specific laminated film is effective when the droplet is an alkane having 10 to 17 carbon atoms.

[Test Example 2: Transmittance measurement]
A laminated film having the same structure as the laminated films A, B, C, and E was produced on a 3 cm square and 500 μm thick quartz glass substrate in the same manner as in Production Examples 3 to 5 and 7 (hereinafter, laminated films A ′, respectively). , B ′, C ′, E ′).
A coating film A2 having a film thickness of 15 μm was formed in the same manner as in Production Example 3 except that the polymer solution P1 was used instead of the polymer composition solution M1 on a 3 cm square quartz glass substrate having a thickness of 500 μm. Next, on the coating film A2, a polyparaxylylene resin (Parylene-C, manufactured by Japan Parylene Co., Ltd., relative dielectric constant 2.95, glass transition temperature 87 to 97 ° C.) is formed by chemical vapor deposition by a CVD method, A laminated film G ′ having a total film thickness of 20 μm [a two-layer laminated body in which layers (A): 15 μm / layer (B): 5 μm were laminated in this order from the substrate side] was obtained.
Regarding the laminated films A ′, B ′, C ′, E ′, and G ′, the transmittance (%) of visible light (wavelengths 550 nm and 650 nm) was measured using UV-3100 manufactured by SHIMADZU. The results are shown in Table 2.
Of the laminated films used in each example, laminated films A ′, B ′, and C ′ correspond to the laminated films used in the present invention.

  From the results shown in Table 2, the laminated films A ′ and C ′ having the same substrate-side layer (A) as compared with the laminated film E ′ are judged from the measured values of visible light transmittance. It was found that the laminated film B ′ has higher transparency than the laminated film G ′. Further, in the laminated films E ′ and G ′, generation of interference fringes not seen in the laminated films A ′, B ′, and C ′ was observed. This is caused by the difference in refractive index between the layer (A) and the layer (B) in the laminated films E ′ and G ′ as compared with the laminated films A ′, B ′, and C ′. When used for an apparatus, the configuration of the laminated films A ′, B ′, and C ′ is superior to the configurations of the laminated films E ′ and G ′.

[Example 1: Production of droplet movement control element]
The droplet movement control element of FIG. 1 is created using the electrostatic energy control means of FIG. The droplet 7 is disposed between the counter electrode 6 b and the electret 4, and hexadecane is used as the droplet 7. As the electret 4, the three-layer laminate of Example 1-3 described above is used. The surface potential of the electret 4 is about −1,100V. The capacitances of the capacitors 8a and 8b are both 3 pF including the parasitic capacitance.
When the capacitor 8b is connected to the counter electrode 6b by the SPDT 9 and the counter electrode 6a is grounded, the droplet 7 starts to move in the arrow direction (direction from the counter electrode 6b to the counter electrode 6a) and reaches the counter electrode 6a.
Next, when the SPDT 9 is switched, the capacitor 8a is connected to the counter electrode 6a, and the counter electrode 6b is grounded, the droplet 7 starts to move in the direction of the arrow (direction from the counter electrode 6a to the counter electrode 6b), and the counter electrode 6b To reach.

  DESCRIPTION OF SYMBOLS 1 ... Droplet movement control apparatus, 2 ... Transparent substrate, 3 ... Transparent electrode layer (common electrode), 4 ... Electret, 5 ... Counter substrate, 6a ... Counter electrode, 6b ... Counter electrode, 7 ... Droplet, 8a ... Capacitor , 8b ... Capacitor, 9 ... SPDT switch, 10 ... Substrate, 11 ... Laminated body, 12 ... DC high voltage power supply device, 14 ... Corona needle, 16 ... Grid, 17 ... Ammeter, 18 ... Power supply for grid, 19 ... Hot plate .

Claims (12)

A common electrode, an electret provided on the common electrode, a plurality of counter electrodes disposed to face the electret, and electrostatic energy control means for controlling electrostatic energy between the electret and the counter electrode; A device for controlling the movement of the droplet on the electret, comprising a droplet in contact with the electret,
The droplets contain a saturated hydrocarbon having 10 to 17 carbon atoms that is liquid under conditions of a temperature of 25 ° C. and a pressure of 10 ⁵ Pa;
The electret, from the common electrode side, a layer (A) containing a fluoropolymer (a) having an aliphatic ring in the main chain or a material (a ′) derived from the fluoropolymer (a); The non-fluorinated polymer (b) having an aliphatic ring in the main chain or the layer (B) containing the material (b ′) derived from the non-fluorinated polymer (b) is charged in the laminate in this order. der made by injecting a is,
Value of - [the non-fluoropolymer dielectric constant of (b) the relative dielectric constant of the fluorine-containing polymer (a)], characterized in der Rukoto 0.1 or more and less than 0.3, the liquid Drop movement control device.   The droplet movement control device according to claim 1, wherein the thickness of the layer (A) is 1 to 50 µm, and the thickness of the layer (B) is 0.5 to 10 µm.   A layer (C) containing a fluorine-containing polymer (c) having an aliphatic ring in the main chain or a material (c ′) derived from the fluorine-containing polymer (c) is further laminated on the layer (B). The droplet movement control device according to claim 1 or 2, wherein   The droplet movement control apparatus according to claim 3, wherein the layer (C) has a thickness of 0.5 to 5 μm. The droplet movement control apparatus according to any one of claims 1 to 4, wherein the non-fluorinated polymer (b) has a repeating unit represented by the following formula (b1-1).

[In Formula (b1-1), R ¹ and R ² are each independently a hydrogen atom, an alkyl group or a cycloalkyl group, and R ¹ and R ² may be bonded to each other to form a ring. . ] The droplet according to claim 5, wherein the non-fluorinated polymer (b) has a repeating unit in which R ¹ and R ² in the formula (b1-1) are bonded to each other to form a ring. Movement control device. The droplet movement control device according to claim 6, wherein the non-fluorinated polymer (b) has a repeating unit represented by the following formula (b1-12).

[In the formula (b1-12), R ¹¹ represents a hydrogen atom or an alkyl group. ] The non-fluorinated polymer (b) further has a repeating unit in which R ¹ and R ² in the formula (b1-1) are not bonded to each other to form a ring. The droplet movement control device described.   The droplet movement control apparatus according to any one of claims 1 to 8, wherein the fluoropolymer (a) has a carboxy group or an alkoxycarbonyl group as a terminal group.   The droplet movement according to any one of claims 1 to 9, wherein the material (a ') is a reaction product of the fluoropolymer (a) and a silane coupling agent having an amino group. Control device.   The droplet movement control apparatus according to any one of claims 1 to 10, wherein the saturated hydrocarbon is hexadecane.   The droplet movement control device according to claim 1, which is an image display device.

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