JP2011050212A - Electrostatic induction-type power generation element and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic induction-type power generation element having an electret which is superior in thermal stability of the retained charge and is constituted of a film formed by patterning, and to provide a method of manufacturing the element. <P>SOLUTION: The electrostatic induction-type power generation element includes a substrate 11, a pattern electrode 12 formed on the substrate 11, and the electret obtained by injecting the charge into a pattern film 13 which covers a pattern electrode 12 and is formed of a pattern corresponding to the pattern electrode 12. The pattern film 13 contains a polymer (A) having an aliphatic ring in a main chain or a material (A') derived from the polymer (A), and has a curved surface with a curvature radius of 0.5 to 15 &mu;m continuously curved from the upper surface of the pattern film 13 to the side surface. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an electrostatic induction power generation element and a method for manufacturing the same.

Conventionally, an electrostatic induction conversion element using an electret in which an electric charge is injected into an insulating material has been proposed as an element used in an electrostatic induction vibration power generator, a condenser microphone, or the like.
In general, an electrostatic induction power generation element that forms an electrostatic induction vibration power generation device includes an electrode (base electrode) having an electret formed on an upper surface, and a predetermined distance from the base electrode and the electret. The counter electrode is configured such that either the base electrode or the counter electrode can move relatively so that the overlapping area of the base electrode and the counter electrode changes. In the electrostatic induction power generating element, by moving the base electrode or the counter electrode relatively, a charge opposite to the charge injected into the electret is electrostatically induced in the counter electrode, and the base electrode and the counter electrode are Current flows through the connected external load.

As electrets used for applications such as electrostatic induction power generation elements, conventionally, a coating film formed by pasting or applying a linear fluoropolymer such as polytetrafluoroethylene on a conductive substrate has been used. However, in recent years, it has been proposed to form an electret by patterning on a substrate for the purpose of improving the amount of power generation.
The linear fluoropolymer has a low fine processability and is not suitable for the above patterning. There are also problems such as low charge retention capability and insufficient surface potential. In order to solve such a problem, for example, Patent Document 1 proposes a polymer having a fluorine-containing aliphatic ring structure in the main chain as an insulating material for electrets that is excellent in fine workability. Patent Document 2 discloses an electret using a mixture of a fluorinated polymer having a ring structure in the main chain and containing a carboxy group as a terminal group and a silane coupling agent in order to improve the surface potential. It has been proposed to form.
However, electrets using organic materials such as conventional fluoropolymers have a problem that it is difficult to stably retain injected charges at high temperatures, and the charges are likely to be released over time at high temperatures. . This problem causes a decrease in the surface potential of the electret, and in turn, deterioration of the electrostatic induction characteristics of the electrostatic induction conversion element using the electret. Therefore, an improvement in charge retention characteristics (thermal stability) that can stably retain injected charges at high temperatures is required.

On the other hand, with respect to electrets used for condenser microphones and the like, in recent years, along with thinning and miniaturization of devices on which condenser microphones are mounted, electrets are also being thinned and miniaturized. Along with the reduction in thickness and size, electrets using an inorganic material such as a silicon oxide film or a silicon nitride film as an insulating material have been proposed. For example, Patent Document 3 discloses an electret structure including a silicon oxide film having a rounded upper end as an electret having excellent charge retention performance.
However, the electret has a problem to be applied as a power generation element. In other words, when the same material is used, the charge retention performance improves as the film thickness increases. However, in the case of a silicon oxide film or silicon nitride film, it is not easy to form a thick film in the process, and therefore, the power generation element is required. It is not easy to have the charge retention performance.

JP 2006-180450 A JP 2008-266563 A JP 2006-245398 A

When the electret is composed of a film formed by patterning, the thermal stability tends to be poor compared to the case where the electret is composed of an unpatterned film.
When the electrostatic induction conversion element is used as a power generation element, specifically, it is required that the surface potential of the electret is less attenuated when exposed to an environment of 100 ° C. for a long time. It is difficult for an electret formed by patterning to satisfy this requirement.
This invention is made | formed in view of the said situation, and provides the electrostatic induction type electric power generation element which comprises the electret excellent in the thermal stability of the hold | maintained electric charge, and its manufacturing method.

The present invention for solving the above problems has the following aspects.
[1] A substrate, a pattern electrode formed on the substrate, and an electret that covers the pattern electrode and injects charges into a pattern film formed in a pattern corresponding to the pattern electrode,
The pattern film contains a polymer (A) having an aliphatic ring in the main chain or a material (A ′) derived from the polymer (A),
An electrostatic induction power generating element having a curved surface with a radius of curvature of 0.5 to 15 μm that curves continuously from the upper surface to the side surface of the pattern film.
[2] The electrostatic induction power generating element according to [1], wherein the polymer (A) is a fluoropolymer having an aliphatic ring in the main chain.
[3] The electrostatic induction according to [1] or [2], wherein the polymer (A) is a polymer having an aliphatic ring in the main chain and a carboxy group or an alkoxycarbonyl group as a terminal group. Type power generation element.
[4] The material (A ′) is a material including a reaction product of the polymer (A) and a silane coupling agent having an amino group, [1] to [3] The electrostatic induction power generating element described in 1.
[5] A method for producing the electrostatic induction power generating element according to any one of [1] to [4],
An electrode forming step of forming a patterned electrode on the substrate;
A pattern film forming step of forming the pattern film on the pattern electrode;
A charge injection step of injecting charges into the pattern film to form electrets;
A method for manufacturing an electrostatic induction power generating element.
[6] In the pattern film forming step, a coating liquid containing the polymer (A) is applied to the substrate on which the pattern electrode is formed, and baked to form a coating film. Patterning a pattern corresponding to the pattern electrode, forming a pattern film having a curvature radius of 0.5 to 15 μm that is continuously curved from the upper surface to the side surface, and heat-treating the pattern film The method for manufacturing an electrostatic induction power generating element according to [5], wherein a curved surface having a curvature radius of 0.5 to 15 μm that is continuously curved from the upper surface to the side surface of the pattern film is formed.
[7] The method for producing an electrostatic induction power generating element according to [6], wherein the heat treatment is performed at a glass transition temperature of the polymer (A) + 20 ° C or higher.
[8] The coating liquid contains, as the polymer (A), a polymer having an aliphatic ring in the main chain and having a carboxy group or an alkoxycarbonyl group as a terminal group, and further having an amino group. The method for producing an electrostatic induction power generating element according to [6] or [7], which contains a coupling agent.

  ADVANTAGE OF THE INVENTION According to this invention, the electrostatic induction type electric power generation element which comprises the electret comprised from the film | membrane formed by the patterning excellent in the thermal stability of the hold | maintained electric charge, and its manufacturing method can be provided.

It is a schematic perspective view which shows a part of structure of one Embodiment of an electrostatic induction type electric power generation element. It is explanatory drawing explaining the "side surface" of a pattern film. It is explanatory drawing explaining the measuring method of a curvature radius (R). It is a schematic top view which shows a part of structure of one Embodiment of an electrostatic induction type electric power generation element. It is a schematic process drawing explaining one Embodiment of the manufacturing method of an electrostatic induction type electric power generation element. It is a schematic process drawing explaining one Embodiment of the manufacturing method of an electrostatic induction type electric power generation element. It is a schematic process drawing explaining one Embodiment of the manufacturing method of an electrostatic induction type electric power generation element. It is a schematic process drawing explaining one Embodiment of the manufacturing method of an electrostatic induction type electric power generation element. It is a schematic process drawing explaining one Embodiment of the manufacturing method of an electrostatic induction type electric power generation element. It is a schematic process drawing explaining one Embodiment of the manufacturing method of an electrostatic induction type electric power generation element. It is a schematic process drawing explaining one Embodiment of the manufacturing method of an electrostatic induction type electric power generation element. It is a schematic process drawing explaining one Embodiment of the manufacturing method of an electrostatic induction type electric power generation element. It is a schematic process drawing explaining one Embodiment of the manufacturing method of an electrostatic induction type electric power generation element. It is a schematic process drawing explaining one Embodiment of the manufacturing method of an electrostatic induction type electric power generation element. It is a top view which shows the shape after the patterning of the metal thin film formed on the glass substrate in the manufacture example 2. FIG. It is a fragmentary sectional view in position X-X 'in FIG. It is a graph which shows the relationship between heat processing temperature and R. FIG. It is a SEM photograph of the section of a pattern film after performing heat processing for 1 hour at 300 ° C. It is a conceptual diagram of a corona charging device used for charge injection. It is a graph which shows the result of a thermal stability test.

<Electrostatic induction type power generation element>
The electrostatic induction power generating element of the present invention covers a substrate, a pattern electrode formed on the substrate, and the pattern electrode, and charges are injected into a pattern film formed in a pattern corresponding to the pattern electrode. An electret.
Hereinafter, the configuration of the electrostatic induction power generating element of the present invention will be described with reference to the drawings. In the following description of the embodiments with reference to the drawings, components corresponding to those shown in the previous drawings are given the same reference numerals, and detailed descriptions thereof are omitted.
FIG. 1 is a schematic perspective view of a part of the configuration of an embodiment of the electrostatic induction power generating element of the present invention.
The electrostatic induction power generating element of the present embodiment includes a first substrate 11 and a second substrate 21 that is disposed substantially parallel to the first substrate 11 at a constant interval.

As materials constituting the first substrate 11 and the second substrate 21, insulating materials are 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.
Specific examples of the insulating material include inorganic materials such as glass, organic polymer materials such as polyethylene terephthalate, polyimide, polycarbonate, and acrylic resin.
In the present embodiment, each of the first substrate 11 and the second substrate 21 is a flat plate having a smooth surface, and an electrode 12 and an electrode 22 are formed on the surface, respectively. However, the present invention is not limited to this, and the first substrate 11 and the second substrate 21 may each be a substrate on which irregularities of a pattern corresponding to the electrode 12 are formed. The substrate may be provided with other pattern irregularities.

On the first substrate 11, a plurality of line-shaped electrodes 12 are provided as pattern electrodes, and the length of the line in the direction of arrow D (the direction in which the second substrate 21 moves) in FIG. It is formed so that the directions intersect. Each of the plurality of electrodes 12 is connected at the end by a wiring (not shown), and is electrically connected to a load (not shown) via the wiring.
The material constituting the electrode 12 is not particularly limited as long as it has conductivity. The resistance value of the 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 gold, silver, copper, nickel, chromium, aluminum, titanium, tungsten, molybdenum, tin, cobalt, palladium, platinum, and alloys containing at least one of these as a main component. Can be mentioned. Further, examples thereof include metal oxide conductive films such as ITO (Indium Tin Oxide) and IZO (Indium Zinc Oxide), and organic conductive films made of polyaniline, polypyrrole, PEDOT / PSS, carbon nanotubes, and the like.
The electrode 12 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 width of the electrode 12 is not particularly limited. However, the smaller the width, the better the conversion from kinetic energy to electrical energy can be performed by a small relative motion, and the conversion efficiency is improved. Therefore, the width of the electrode 12 and the electrode 22 is preferably 1 mm or less, more preferably 500 μm or less, and even more preferably 300 μm or less. The lower limit of the width is not particularly limited, but is preferably 50 μm or more, more preferably 100 μm or more in consideration of durability, productivity, characteristics as an electret (size of surface potential and its stability), and the like.
The thickness of the electrode 12 (the 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 electrode 12 is covered with a line-shaped pattern film 13.
The pattern film 13 contains a polymer (A) having an aliphatic ring in the main chain or a material (A ′) derived from the polymer (A). Thereby, the electret formed is excellent in charge retention performance.
Although mentioned later in detail, as a polymer (A), since it is excellent in the said effect, the fluorine-containing polymer which has an aliphatic ring in a principal chain is preferable. A polymer having an aliphatic ring in the main chain and having a carboxy group or an alkoxycarbonyl group as a terminal group is preferred.

Examples of the material (A ′) include a material containing a reaction product of the polymer (A) and other components other than the polymer (A).
The other component is preferably a silane coupling agent or a compound (C) having a molecular weight of 50 to 2,000 having two or more polar functional groups (excluding the silane coupling agent), and the silane coupling agent is Particularly preferred. Thereby, the thermal stability of the electric charge held by the electret formed is further improved, and the temporal stability and the like are also improved. The effect is particularly remarkable when the polymer (A) is a polymer having an aliphatic ring in the main chain and a carboxy group or an alkoxycarbonyl group as a terminal group.
As the reaction product, for example, a coating solution in which the polymer (A) and other components are dissolved in a solvent is heated (baking when the solvent is evaporated to form a film, and continuously curved from the top surface to the side surface of the pattern film. And the like which are produced by the reaction of each component when a curved surface having a predetermined radius of curvature is formed.
Components other than the polymer (A) used for forming the material (A ′) will be described in detail later.

The pattern film 13 has a curved surface with a radius of curvature (hereinafter sometimes referred to as R) of 0.5 to 15 μm that is continuously curved from the upper surface to the side surface. The R is more preferably from 0.5 to 10 μm, particularly preferably from 1.0 to 4.0 μm. When R is within the above range, the thermal stability of the retained charge is improved. The upper limit value indicates the maximum value for maintaining the shape of the pattern, and the lower limit value indicates the minimum value for obtaining a sufficient effect for improving the thermal stability of the held charges.
Here, “upper surface” and “side surface” will be described with reference to FIG. The “upper surface” is defined as a surface that coincides with the horizontal surface at the position where the height in the direction perpendicular to the surface of the substrate 11 (horizontal plane) is the highest among the surfaces of the pattern film 13, and the “side surface” It is defined as a plane in which the angle formed with the substrate 11 is the maximum from the portion rising with respect to the substrate 11 (the portion closest to the substrate 11) to the “upper surface”. For example, when the pattern film 13 has the cross-sectional shape shown in FIG. 2A, the angle formed with respect to the surface of the substrate 11 is not a plane where the angle is θ _a-1 (a plane that coincides with the broken line L _a1 ). ), The surface where the angle formed with respect to the surface of the substrate 11 is θ _a-2 (the surface that coincides with the broken line _La2 ) is the side surface of the pattern film 13.

A method of measuring R from the upper surface to the side surface of the pattern film 13 will be described more specifically with reference to FIG. FIG. 3 is a schematic partial cross-sectional view of the electrostatic induction power generating element of this embodiment.
In FIG. 3, the upper surface of the pattern film 13 is a surface coinciding with the horizontal plane including the broken line L1, and the side surface is a surface coinciding with the plane including the broken line L2.
The pattern film 13 is continuously curved from the upper surface to the side surface (from the edge of the upper surface (position P1) to the upper edge (position P2) of the side surface), and R of the curved portion is 0.5 to 15 μm. .

The R is measured by the following procedures (1) to (3).
(1) The substrate 11 on which the pattern film 13 is formed is cut, and a cross-sectional photograph thereof is taken with a scanning electron microscope (Scanning Electron Microscopy (SEM), for example, S-4300 manufactured by Hitachi High-Technologies Corporation) (magnification: 4000 times). ).
(2) Next, a circle is drawn in the cross-sectional photograph, and the circle is fitted to a curved surface from the upper surface to the side surface of the pattern film 13 as shown in FIG.
(3) Measure the radius of the fitted circle, that is, R.

In (2) above, the fitting is performed by taking an image into a device capable of obtaining R using image processing software (for example, a digital microscope VHX-900 manufactured by Keyence Corporation), and using a built-in software, This can be done by drawing and fitting the size of the circle to the curved surface of the pattern end of the pattern film 13. Also, paste images on the screen of software such as Microsoft Excel, Word, PowerPoint, Adobe Photoshop, illustrator, Autodesk AutoCAD LT, and then draw a perfect circle in the photo on the software. It can also be performed by fitting the size to the curved surface of the pattern end of the pattern film 13.
In (3) above, R is measured by comparing the radius of the circle drawn in the cross-sectional photograph in (2) above with the scale (indicating a length corresponding to 1 μm width) displayed in the cross-sectional photograph. it can.

The angle formed by the upper surface and the side surface of the pattern film 13 (angle θ _{1 in} FIG. 3) is preferably 80 degrees or more. The angle θ ₁ is preferably 80 to 150 degrees, and more preferably 90 to 120 degrees.
The cross-sectional shape of the pattern film 13 is a substantially rectangular shape in which the upper side and two sides of the rectangle are connected by a predetermined R curved surface, or the upper side of the trapezoid and the two sides are connected by a predetermined R curved surface. The substantially trapezoidal shape is preferable.

The width W of the pattern film 13 is not particularly limited, but is preferably the same as or larger than that of the electrode 12, and more preferably larger than the width of the electrode 12. When the width W is larger than the width of the electrode 12, the surface potential value when electretized can be increased, and the stability of charge retention (both room temperature stability and stability during heating) can be increased.
The thickness of the pattern film 13 (the shortest distance from the upper surface of the electrode 12 to the top of the pattern film 13) is preferably 1 to 200 μm, and more preferably 5 to 20 μm in consideration of power generation output, ease of processing and the like.

On the surface of the second substrate 21 on the first substrate 11 side, a plurality of line-shaped electrodes 22 are formed at positions facing the pattern film 13.
The second substrate 21 is configured to reciprocate (vibrate) substantially horizontally in the direction of arrow D in FIG.
As with the electrode 12, the ends of the plurality of electrodes 22 are connected by wiring (not shown), and are electrically connected to a load (not shown) by the wiring.
The description of the electrode 22 is the same as the description of the electrode 12. However, the composition (material, layer configuration, etc.) of the electrode 22 may be the same as or different from that of the electrode 12.

  In the electrostatic induction power generating element of the present embodiment, power can be generated by reciprocating (vibrating) the substrate 21 substantially horizontally in the direction of arrow D in FIG. That is, due to the vibration, the position of the substrate 21 relative to the substrate 11 varies relatively, and accordingly, the overlapping area between the electret that injects charges into the pattern film 13 and the electrode 22 at the opposite position changes. In the overlapping portion of the pattern film 13 and the electrode 22, the charge having the opposite polarity to the charge injected into the pattern film 13 is electrostatically induced in the electrode 22 by the charge injected into the pattern film 13. On the other hand, in the portion where the pattern film 13 and the electrode 22 do not overlap, there is no reverse charge opposite to the previously induced charge, and a current flows through the load to cancel the potential difference with the external load. Electric energy is generated by taking this repetition as a voltage wave. In this way, kinetic energy is converted into electrical energy.

The maximum power generation output P _{max at} this time is expressed by the following mathematical formula.
P _max = 2πσ ² nAf / {εε ₀ / d × (εg / d + 1)}
[In the formula, σ is the surface charge density of the pattern film 13 into which charges are injected, n is the number of poles (the number of electrodes 12 arranged in the movement direction of the substrate 11 (that is, the number of pattern films 13)), and A is the pattern The maximum overlapping area of the film 13 and the electrode 22, f is the frequency of the reciprocating motion of the electrode 22, ε is the relative dielectric constant, ε ₀ is the dielectric constant of vacuum, d is the thickness of the pattern film 13, and g is the pattern film 13 The distance from the electrode 22. ]

  As shown in the above formula, the power generation output increases as the thickness d of the pattern film 13 increases. In the case of a film made of an inorganic material such as a silicon oxide film or a silicon nitride film, it is difficult to set the thickness d of the pattern film 13 to 2 μm or more. On the other hand, in the present invention, by using a specific material, for example, the pattern film 13 having a thickness of 10 μm or more can be easily formed, and fine processing is also possible.

In addition, this invention is not limited to the said embodiment, As an electret, except having provided what inject | poured the charge into the pattern film | membrane which was formed using the specific material from the upper surface to the side surface from the upper surface. A configuration of a known electrostatic induction power generation element can be appropriately employed.
For example, in the above-described embodiment, the electrode 12, the pattern film 13, and the electrode 22 are shown in the form of a line. However, the present invention is not limited to this, and any shape, for example, conventionally used for an electrostatic induction power generation element. The shape of the patterned electrode can be adopted as appropriate. Examples of shapes other than the line shape include a comb shape, a ring shape, and a checkered pattern. The number of pattern electrodes formed on the substrate surface may be one or plural.
Further, in the present embodiment, an example in which the pattern film 13 covers the upper surface and side surfaces of the electrode 12 is shown, but the present invention is not limited to this, and the pattern film 13 may cover only the upper surface of the electrode 12. .

The pattern film 13 may be composed of a single composition layer, or may have a multilayer structure in which a plurality of layers having different compositions are laminated.
If necessary, another layer may be laminated on the pattern film 13. As another layer which can be laminated | stacked, the layer which consists of a protective layer, an inorganic substance, etc. are mentioned, for example.
A structure in which other layers are stacked can be formed by, for example, forming the other layers on the coating film before patterning the coating film to form a pattern.

As shown in FIG. 4, a guard electrode 14 may be formed on the first substrate 11 in the gaps between the plurality of pattern films 13 (and electrodes 12). The guard electrode 14 is normally grounded. As a result, the counter electrode faces the pattern film 13 and faces the guard electrode after electrostatic induction occurs, so that a change in potential generated in the counter electrode increases, and the amount of power generation can be increased. The guard electrode 14 can be formed in the same manner as the electrode 12.
In the embodiment shown in FIG. 1, the relative movement between the pattern film 13 (and the electrode 12) and the electrode 22 is realized by the vibration of the substrate 21, but the present invention is not limited to this. For example, the substrate 11 may be vibrated instead of the substrate 21.

<Method for manufacturing electrostatic induction power generation element>
The method of manufacturing the electrostatic induction power generating element of the present invention includes, for example,
An electrode forming step of forming a patterned electrode on the substrate;
A pattern film forming step of forming the pattern film on the pattern electrode;
A charge injection step of injecting charges into the pattern film to form electrets;
It can manufacture with the manufacturing method which has this.

(Electrode formation process)
Examples of the substrate include the same ones as the substrate 11.
A method for forming the pattern electrode is not particularly limited, and a known method can be used. Specifically, for example, there is a method of forming a conductive thin film on a substrate and patterning the conductive thin film.
Examples of the method for forming the conductive thin film include physical vapor deposition and electroless plating.
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.
When forming a conductive thin film by an electroless plating method, it is preferable to attach a catalyst to the surface of the substrate 1 in advance before forming the conductive thin film.
Examples of the catalyst used in the electroless plating method include metal fine particles, metal-supported fine particles, colloid, and organometallic complex.

  The patterning of the conductive thin film can be performed by 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 (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.

(Pattern film forming process)
In this step, the pattern film is formed on the pattern electrode. That is, the pattern electrode is covered, formed in a pattern corresponding to the pattern electrode, containing the polymer (A) or the material (A ′), and continuously curved from the upper surface to the side surface. A pattern film having a curved surface (hereinafter sometimes referred to as “R-attached pattern film”) is formed.

The method for forming the pattern film with R is not particularly limited, and a known patterning technique can be used.
Specific examples include the following methods (Ia) to (Ig).
Method (Ia): A coating liquid containing the polymer (A) is applied on the substrate on which the pattern electrode is formed, and baked to form a coating film. The coating film corresponds to the pattern electrode. A pattern film formed by patterning corresponding to the pattern electrode and having substantially no curved surface with a radius of curvature of 0.5 to 15 μm continuously curved from the upper surface to the side surface is formed by patterning into a pattern, A method of forming a curved surface of R0.5 to 15 μm that is continuously curved from the upper surface to the side surface by heat-treating the film.
Hereinafter, “substrate with pattern electrode” is referred to as “substrate with electrode”, and “pattern film having substantially no curved surface of R0.5 to 15 μm that is continuously curved from the upper surface to the side surface” is referred to as “cornered pattern”. Sometimes referred to as a membrane.
“Substantially free” in a cornered pattern film means that a curved surface of R0.5 to 15 μm may be formed at a part of the corner of the pattern film depending on the patterning conditions or the like. .

Method (Ib): The coating liquid is applied on a substrate with electrodes, baked to form a coating film, and the coating film is patterned into a pattern corresponding to the pattern electrode to form a cornered pattern film. A method of forming a curved surface of R0.5 to 15 μm that continuously curves from the upper surface to the side surface by wet etching the pattern film with corners.
Method (Ic): The coating liquid is applied on a substrate with electrodes, baked to form a coating film, and the coating film is patterned with a pattern corresponding to the pattern electrode, and the resist has a substantially trapezoidal cross section. A method of forming a film, dry-etching the coating film using the resist film as a mask, and transferring the shape of the resist film to the coating film.

Method (Id): A method in which the coating liquid is applied onto a substrate with electrodes, baked to form a coating film, and the coating film is patterned by an imprint method to form a pattern film with R.
Method (Ie): The coating liquid is applied onto a substrate with electrodes, baked to form a coating film, and the coating film is patterned into a pattern corresponding to the pattern electrode to form a cornered pattern film. A method of forming a polymer film by applying a polymer solution on the pattern film with corners, and dry-etching the polymer film to form a pattern film with R.

Method (If): The pattern electrode is coated on the substrate with electrodes by printing the coating solution, a pattern solution layer formed in a pattern corresponding to the pattern electrodes is formed, dried, and a pattern with R A method of forming a film.
Method (Ig): After patterning of the oil-repellent / lipophilic corresponding to the pattern electrode on the substrate surface with the electrode, the pattern electrode is coated by dipping or printing of the coating liquid, and corresponds to the pattern electrode A method of forming a pattern liquid layer formed with a pattern to be formed and drying to form a pattern film with R.

  Among the above methods, the method (Ia) is preferable because the effects of the present invention are excellent. In particular, when a coating liquid containing a silane coupling agent is used, the heat stability of the retained charge is further improved by performing heat treatment.

[Method (Ia)]
The method (Ia) will be described in more detail with reference to FIG.
First, a coating liquid containing the polymer (A) is applied onto a substrate with electrodes 30 (electrodes are not shown here) and baked to form a coating film, which corresponds to the pattern electrode. The cornered pattern film 31 is formed by patterning into a pattern to be formed. Thereafter, when the cornered pattern film 31 is heat-treated, it is softened by the heat, and the corners 31a and 31b of the cornered pattern film 31 are removed to form a curved surface, thereby obtaining an R-patterned film 31 ′.
At this time, R can be adjusted to a desired value by adjusting the heat treatment temperature.

The composition of the coating liquid will be described later.
Examples of the method for applying the coating liquid include spin coating, roll coating, casting, dipping, water casting, Langmuir-Blodgett, die coating, ink jet, and spray coating. Among these, the spin coat method is preferable.

The baking temperature for forming the coating film may be a temperature at which at least a part of the solvent in the coating film evaporates to form the coating film. For example, baking at a temperature higher than the boiling point of the solvent (high temperature baking) Or by baking at a temperature lower than the boiling point of the solvent (low temperature baking).
Here, the “boiling point of the solvent” when a plurality of solvents are used as the solvent means the boiling point of the solvent having the highest boiling point among the plurality of solvents.

Among the above, when high-temperature baking is performed, there is an advantage that the structure of the film on which the pattern is formed is less likely to collapse by the subsequent heat treatment, and the possibility that the pattern is crushed is low. In addition, the coating liquid contains, as the polymer (A), a polymer having an aliphatic ring in the main chain, a polymer having a carboxy group or an alkoxycarbonyl group as a terminal group, and further having an amino group. In the case where it contains, the reaction between the alkoxycarbonyl group and the amino group is promoted by high-temperature baking, and there is an advantage that the heat resistance of the electret can be ensured when the formed pattern film with R is electretized.
When low-temperature baking is performed, since the solvent remains in the coating film after baking, the corners 31a and 31b can be easily removed by subsequent heat treatment, and R can be easily increased. In addition, when low-temperature baking is performed, there is an advantage in terms of processes such that the same change can be caused in the shapes of the corners 31a and 31b even if the subsequent heat treatment is performed at a lower temperature than when high-temperature baking is performed. For example, if a coating film is formed by high-temperature baking and a desired R can be obtained by heat treatment at about 300 ° C., a coating film formed by low-temperature baking has a temperature of less than 300 ° C., for example, about 270 to 280 ° C. Equivalent R can be obtained by heat treatment.

What is necessary is just to set baking time suitably according to baking temperature.
The atmosphere at the time of baking may be an inert gas atmosphere or an air atmosphere. The coating solution contains, as the polymer (A), a polymer having an aliphatic ring in the main chain, a carboxy group or an alkoxycarbonyl group as a terminal group, and a silane coupling agent having an amino group. In this case, an air atmosphere is preferable for promoting the condensation of the silane coupling agent.
The atmosphere during baking may be normal pressure or reduced pressure, and normal pressure is preferable from the viewpoint of ensuring the smoothness of the formed film.

  The thickness of the coating film may be appropriately set according to the desired electret thickness, the amount of solvent remaining in the coating film, and the like. For example, in consideration of heat treatment when forming a pattern film with R, reduction in thickness due to solvent volatilization, etc., when the thickness of the electret is set to 1 to 200 μm (preferably 10 to 20 μm), the thickness of the coating film The thickness is preferably 2 to 220 μm (preferably 12 to 25 μm).

In the method (Ia), the patterning of the coating film can be performed by a conventionally known method and is not particularly limited.
As a specific example, there is a method of forming a mask having a predetermined pattern on the coating film and performing etching.
The mask can be formed, for example, by the same method as the pattern electrode. However, the material constituting the mask only needs to have a certain etching selectivity with respect to the coating film, and may not be a conductive material. For example, a resist film patterned in a pattern corresponding to the pattern electrode may be used as the mask. The resist film can be patterned by a known lithography method.

The heat treatment conditions (temperature, time) for the cornered pattern film 31 may be appropriately set in consideration of the desired R, the glass transition temperature (Tg) of the polymer (A), the thermal decomposition temperature (Td), and the like.
The heat treatment temperature is usually set in the range of 150 to 400 ° C, preferably in the range of 200 to 320 ° C. Within this range, R tends to increase as the heat treatment temperature increases.
The heat treatment is preferably performed at a temperature of Tg + 20 ° C. or higher of the polymer (A), more preferably Tg + 40 ° C. or higher because R can be increased. The upper limit of this temperature should just be temperature lower than Td of a polymer (A). The temperature of Td-50 degrees C or less of a polymer (A) is preferable, and the temperature of Td-100 degrees C or less is more preferable.
The heat treatment time varies depending on the heat treatment temperature, but is usually in the range of 10 minutes to 24 hours, preferably 30 minutes to 1 hour.
The atmosphere during the heat treatment may be an inert gas atmosphere or an air atmosphere.
The heat treatment contains, as a polymer (A), a polymer having an aliphatic ring in the main chain, a carboxy group or an alkoxycarbonyl group as a terminal group, and a silane coupling agent having an amino group. When the composition is used as a coating liquid and baking is performed at a low temperature to form the coating film, the reaction between the alkoxycarbonyl group and the amino group is promoted, and the pattern-formed film is electreted. It also has the effect of ensuring the heat resistance of the electret when it is made.

[Method (Ib)]
The formation of the R-attached pattern film by the method (Ib) can be performed by, for example, the procedure shown in FIG.
First, a coating film is formed on the substrate with electrode 30 in the same manner as in the method (Ia) and patterned to form a cornered pattern film 31. When an etching solution is allowed to flow along the pattern direction on the electrode-attached substrate 30, the corners of the cornered pattern film 31 are dissolved to form a curved surface, thereby forming an R-attached pattern film 31 ′.
As the etching solution, for example, the same solvent as that used in the coating solution can be used.

The formation of the patterned film with R by the method (Ib) can also be performed by the procedure shown in FIG.
First, the coating film 41 is formed on the substrate with electrode 30 in the same manner as in the method (Ia). Next, the coating film 41 is irradiated with an electron beam (EB). As a result, the coating film 41 of the EB irradiation part is removed by EB and removed, and the non-irradiation part remains as a pattern to form a cornered pattern film. After that, when wet etching is performed, the corners of the cornered pattern film are dissolved to form a curved surface as in the case of flowing the etching solution, and the R-thickness pattern film 41 ′ is formed.
As an EB irradiation method, a method generally used in EB lithography can be used, and either direct drawing or irradiation through a mask may be used.
As the etchant used for wet etching, for example, the same solvent as that used in the coating solution can be used.

[Method (Ic)]
The formation of the R-attached pattern film by the method (Ic) can be performed, for example, by the procedure shown in FIG.
First, a negative resist solution is applied on the coating film 41 formed on the electrode-attached substrate 30 and baked to form a resist film 42. The the resist film 42 is exposed through a mask 43 which is arranged at a predetermined interval d _4, patterning the resist film and developed.
In this case, by leaving spaced somewhat apart d ₄ between the mask 43 and the resist film 42, patterned resist film (hereinafter, referred to as a resist mask.) Cross section of 42 'is substantially trapezoidal. That is, the light transmitted through the mask 43 enters the resist film 42 while diffusing. Therefore, the horizontal sectional area of the exposed portion of the resist film 42 increases as it approaches the bottom surface (interface with the coating film 41). Therefore, when the unexposed portion of the resist film 42 is dissolved and removed by development, the cross-sectional shape of the remaining resist film (resist mask 42 ′) becomes a substantially trapezoidal shape. In addition to the above, since the mask 43 and the resist film 42 are spaced apart from each other, diffraction occurs, the boundary (pattern edge) between the pattern forming portion and the non-pattern portion blurs, and the exposed portion of the resist film 42 is exposed. In the vicinity of the edge, the exposure amount gradually decreases toward the portion that becomes the shadow of the mask. In this part, it is considered that the photoreaction until the resist has sufficient durability against the developer does not occur in the resist, and the phenomenon that the particularly weak corner part dissolves in the developer is also occurring.
When dry etching of the coating film 41 is performed using the resist mask 42 ′ as a mask, the shape of the resist mask 42 ′ is transferred to the coating film 41, and an R-attached pattern film 41 ′ is formed.
The suitable range of d ₄ varies depending on the size of R to be produced, the parallelism of the exposure light source, the sensitivity of the resist, etc., but is generally preferably 0.5 to 500 μm, more preferably 1 to 100 μm. Most preferred is ˜50 μm.

The coating film 41 can be formed in the same manner as in the method (Ia).
The resist film 42 can be formed in the same manner as the coating film 41 except that a negative resist solution is used instead of the coating liquid.
The negative resist is not particularly limited, and a commercially available one can be used.
Although FIG. 8 shows an example using a negative resist, the present invention is not limited to this, and a positive resist may be used. As described above, even when using a positive resist, blurred edges of the pattern by a distance d ₄ of the mask 43 and the resist film 42, the portion where the exposure amount becomes Gurajuaru, solubility is sufficiently changed in a developer In particular, it is considered that the phenomenon of dissolving in the developer from a particularly weak corner portion occurs.
The positive resist is not particularly limited, and a commercially available resist can be used.
As a resist that is particularly preferably used, a resist for forming a thick film, which will be described later, can be cited for both negative and positive resists.

The formation of the R-attached pattern film by the method (Ic) can also be performed by the procedure shown in FIG.
First, a negative resist solution having low durability against a developing solution is applied on the coating film 41 formed on the substrate with electrode 30 and baked to form a resist film 44. The resist film 44 is exposed through a mask 43 and is over-developed to pattern the resist film 44. As a result, a resist mask 44 ′ having a substantially trapezoidal cross section is formed.
Therefore, when dry etching is performed by oxygen plasma etching or the like using the resist mask 44 ′ as a mask, the shape of the resist mask 44 ′ is transferred to the coating film 41, and an R-attached pattern film 41 ′ is formed.

Here, “over-development” means that when a resist mask is formed using the resist, the development is performed beyond an optimal development time that can form a resist mask having a target dimension.
Since resist having low durability against a developing solution is used, the surface of the formed resist mask dissolves when over-development is performed. This dissolution is easier to proceed as the surface layer is closer to the surface of the resist film, and as a result, a resist mask 44 'having a substantially trapezoidal cross section is formed.
As the negative resist having low durability against the developer as the resist, it is preferable to use a resist for forming a thick film. For example, “SU-8 3000” manufactured by Kayaku Microchem Corp., “KMPR” manufactured by Kayaku Microchem Corp. "TMMR S2000" manufactured by Tokyo Ohka Kogyo Co., Ltd., and the like.
Although FIG. 9 shows an example using a negative resist, the present invention is not limited to this, and a positive resist may be used. As a positive resist having low durability against a developing solution, a resist for forming a thick film is preferably used as in the case of the negative type, and examples thereof include “PMER-900” manufactured by Tokyo Ohka Kogyo Co., Ltd.

Formation of the patterned film with R by the method (Ic) can also be performed by the procedure shown in FIG.
First, a negative resist solution is applied on the coating film 41 formed on the substrate with electrode 30 and baked at a low temperature to form a resist film 45. The resist film 45 is exposed through a mask 43, developed, and then baked at a high temperature. As a result, a resist mask 45 ′ having a substantially trapezoidal cross section is formed.
Therefore, when dry etching is performed by oxygen plasma etching or the like using the resist mask 45 ′ as a mask, the shape of the resist mask 45 ′ is transferred to the coating film 41, and an R-attached pattern film 41 ′ is formed.

Here, “low temperature” of baking at the time of forming a resist film means a temperature lower than the boiling point of the solvent in the resist. When the baking is performed at a low temperature, the solvent remains in the resist film 45 and thus in the resist mask 45 ′. For this reason, when high-temperature baking is performed after development, the resist mask 45 ′ is reduced in volume while the contact surface with the coating film 41 is fixed due to volatilization of the solvent. Also, as in the method (Ia), the resist mask 45 ′ Since the corners are rounded off due to heat, the cross-sectional shape is substantially trapezoidal.
Here, the “boiling point of the solvent” in the case of using a plurality of solvents as the resist solvent means the boiling point of the solvent having the highest boiling point among the plurality of solvents.
The high temperature baking after the development can be performed in the same manner as the heat treatment described in the method (Ia).
In addition, although the example using a negative resist was shown in FIG. 10, it is not limited to this, You may use a positive resist. The resist is not particularly limited, and any commercially available resist can be used. In particular, the above-described resist for forming a thick film is preferably used.

  In the method (Ic), when the R of the formed patterned film with R does not have a desired value, a heat treatment similar to the method (Ia) or a wet etching similar to the method (Ib) is further performed. R may be changed to a desired value.

[Method (Id)]
In the method (Id), the coating film can be formed in the same manner as in the method (Ia).
Formation of the pattern film with R by imprinting can be performed by a known method. Specifically, as shown in FIG. 11, a mold 46 corresponding to the shape of the target pattern film with R is created, the mold 46 is pressed into the coating film 41, and the shape of the mold 46 is transferred. Thereafter, the mold 46 is released to obtain an R-attached pattern film 41 ′.
The method for producing the mold 46 is not particularly limited, and a known method such as a method of directly mechanically scraping a metal plate, a glass plate, or an organic polymer plate, an electron beam on a metal plate, a glass plate, or an organic polymer plate. It can be produced by a method of drawing using, a method of transferring the shape of a mold prepared from a metal plate or glass plate to a mold using an organic polymer or the like.

[Method (Ie)]
In the method (Ie), the coating film can be formed and patterned in the same manner as in the method (Ia).
As shown in FIG. 12, a polymer film 47 is formed by applying a polymer solution onto the electrode-attached substrate 30 on which the cornered pattern film 31 is formed. In the polymer film 47, the thickness of the corner portion of the cornered pattern film 31 is reduced. Therefore, when the polymer film 47 is removed by dry etching using oxygen plasma etching or the like, the thin portion of the polymer film 47, that is, the corners of the cornered pattern film 31 are also removed at the same time, and the R-patterned film 31 ′ Is formed.
The polymer solution may contain a polymer and a solvent. The polymer is not particularly limited as long as it is an organic polymer, but it is particularly preferable to use a polymer (A) solution or a solution containing a material (A ′) derived from the polymer (A). The polymer solution may be the same as or different from the coating solution.

[Method (If)]
The printing method of the coating liquid is not particularly limited, and a known printing method can be used. Specifically, a screen printing method, a relief printing method, a gravure printing method, a flat plate printing method, a flexographic printing method, an ink jet method, a dispenser direct drawing method, and the like can be given. Among these, the screen printing method, the ink jet method, and the dispenser direct drawing method are preferable in terms of the simplicity of the process and the ease of application to the pattern of the present invention.
Since the pattern liquid layer formed on the substrate with electrodes by printing contains a solvent, the pattern edge is rounded. Therefore, the pattern film with R is formed by drying the pattern liquid layer.

As an example, first, as shown in FIG. 13, the coating liquid 51 is applied onto the screen 52, the screen 52 is brought into contact with the substrate with electrode 30, the coating liquid 51 is extruded, and then the screen 52 is removed. . Thereby, pattern liquid layer 51 'is formed on the board | substrate 30 with an electrode. Thereafter, the pattern liquid layer 51 ′ is baked at a temperature equal to or higher than the boiling point of the solvent of the coating liquid 51 and dried to form the R-attached pattern film 51 ″.
Here, the “boiling point of the solvent” when a plurality of solvents are used as the solvent of the solution means the boiling point of the solvent having the highest boiling point among the plurality of solvents.
In addition, although the example which forms pattern liquid layer 51 'by screen printing was shown in FIG. 13, you may form by other printing methods, such as an inkjet method and a dispenser direct drawing method.

[Method (Ig)]
The method (h) can be performed, for example, according to the procedure shown in FIG.
First, the oil repellent part 53 is formed on the substrate with electrode 30 with a pattern corresponding to the pattern electrode. Next, the coating liquid 51 adheres to the non-oil repellent part (hydrophilic part) by printing the coating liquid 51 on the surface of the electrode-equipped substrate 30 or dipping into the coating liquid 51 of the substrate 30 with the electrode, Similar to the method (If), the pattern liquid layer 51 ′ is formed. Therefore, by drying the pattern liquid layer 51 ′, an R-attached pattern film 51 ″ is formed.
Thereafter, the pattern liquid layer 51 ′ is baked at a temperature equal to or higher than the boiling point of the solvent and dried to form a pattern film 51 ″ with R. The oil repellent part 53 is a material for forming the oil repellent part 53. It can be removed by treating with a solvent that dissolves or UV-ozone treatment.

Examples of the material used for forming the oil repellent portion 53 include a fluorine-containing silane coupling agent, a fluorine-containing acrylate, a copolymer of fluorine-containing methacrylate, and the like.
Examples of the method for forming the oil repellent portion 53 include a photolithography method, an ink jet method, a micro contact printing method, and the like.

(Charge injection process)
By injecting charges into the R-pattern film formed as described above, the R-pattern film can be used as an electret.
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.
Further, as a temperature condition at the time of injecting the charge, it is possible to stabilize the charge held after the injection by performing at a temperature higher than the glass transition temperature (Tg) of the polymer (A) or the material (A ′) contained in the electret. It is preferable from the surface of property, and it is particularly preferable to carry out under a temperature condition of about Tg + 10 to 20 ° C.
Furthermore, it is preferable to apply a high voltage as the applied voltage for injecting the charge if it is not higher than the dielectric breakdown voltage of the pattern. In the present invention, a high voltage of ± 6 to ± 30 kV is applicable, and voltage application of ± 8 to ± 15 kV is particularly preferable. In particular, when the polymer (A) is a fluorine-containing polymer, it is more preferable to apply a voltage of −8 to −15 kV because it can hold a negative charge more stably than a positive charge.

<Polymer (A)>
The polymer (A) is a polymer having an aliphatic ring in the main chain. The aliphatic ring contributes to improvement of charge retention performance.
“Aliphatic ring” refers to a ring having no aromaticity.
The aliphatic ring may have a carbocyclic structure in which the ring skeleton is composed only of carbon atoms, or has a heterocyclic structure in which the ring skeleton includes atoms (heteroatoms) other than carbon atoms. May be. Examples of the hetero atom include an oxygen atom and a nitrogen atom.
The aliphatic ring may be saturated or unsaturated.
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.

Examples of the aliphatic ring include a saturated or unsaturated aliphatic hydrocarbon ring, an aliphatic heterocyclic ring 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, A fluorine-containing aliphatic ring in which a hydrogen atom in an aliphatic hydrocarbon ring or an aliphatic heterocyclic ring is substituted with a fluorine atom is preferred.
The aliphatic ring may have a substituent (excluding a fluorine atom). “It may have a substituent” means that part or all of the hydrogen atom or fluorine atom bonded to the carbon atom constituting the ring skeleton of the aliphatic ring may be substituted with a substituent. Means.
Among the above, the polymer (A) preferably has a fluorine-containing aliphatic ring or an aliphatic hydrocarbon ring in the main chain.

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

The polymer (A) preferably has a reactive functional group. In particular, when the polymer (A) is used in combination with a silane coupling agent or a compound (C), the polymer (A) is a functional group of the silane coupling agent or a polar function of the compound (C). It preferably has a reactive functional group capable of reacting with the group.
A “reactive functional group” can form a bond by reacting with other components blended together with the polymer (A) or between the molecules of the polymer (A) when heated or the like. It means a group having reactivity. By having a reactive functional group, the effect of the present invention is improved.

Considering the strength of interaction with the silane coupling agent or compound (C) and the ease of introduction into the polymer, the reactive functional group possessed by the polymer (A) is a carboxy group or an acid halide group. And at least one selected from the group consisting of 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 polymer (A) preferably has a carboxy group or an alkoxycarbonyl group.

The weight average molecular weight of the polymer (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 less than 50,000, film formation is difficult. Moreover, the heat resistance of a film | membrane improves that it is 200,000 or more, and the thermal stability as an electret improves.
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 polymer (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.

In consideration of charge retention performance as an electret, the polymer (A) preferably has a relative dielectric constant of 1.8 to 8.0, more preferably 1.8 to 5.0, and more preferably 1.8 to 3 0.0 is particularly preferred. The relative dielectric constant is a value measured at a frequency of 1 MHz in accordance with ASTM D150.
Further, the polymer (A) is preferably one having a high volume resistivity and a high dielectric breakdown voltage.
The volume resistivity of the polymer (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 voltage of the polymer (A) is preferably 10 to 25 kV / mm, and more preferably 15 to 22 kV / mm. The breakdown voltage is measured according to ASTM D149.
As the polymer (A), a highly hydrophobic polymer is preferable in order to eliminate water that adversely affects insulation and maintain high insulation.

Specifically, the polymer (A) is preferably a fluoropolymer or cycloolefin polymer described later. The cycloolefin polymer is a polymer having an aliphatic hydrocarbon ring in the main chain, and at least two carbon atoms constituting the aliphatic hydrocarbon ring are incorporated in the main chain of the polymer. .
As the cycloolefin polymer, for example, an addition copolymer of norbornenes can be used. Specifically, for example, those sold under the trade names of Apel (registered trademark) (manufactured by Mitsui Chemicals) and TOPAS (registered trademark) (manufactured by Ticona) are preferably used. Also, hydrogenated polymers of ring-opening metathesis polymers of norbornenes can be used. Specifically, polymers sold under the trade names of ZEONEX (registered trademark) (manufactured by ZEON Corporation), ZEONOR (registered trademark) (manufactured by ZEON Corporation), and ARTON (registered trademark) (manufactured by JSR Corporation) are used. Is preferred.

[Fluoropolymer]
The fluoropolymer is a fluoropolymer having an aliphatic ring in the main chain. Examples of the aliphatic ring include those described above.
Here, the “fluorinated polymer” is a polymer having a fluorine atom in its structure. In the fluoropolymer, the fluorine atom may be bonded to the carbon atom constituting the main chain or may be bonded to the side chain. From the viewpoint of obtaining a polymer suitable for electretization having a low water absorption and low dielectric constant, a high dielectric breakdown voltage, and a high volume resistivity, it preferably has at least fluorine atoms bonded to carbon atoms constituting the main chain. . That is, the fluoropolymer preferably has a fluorinated aliphatic ring in the main chain.
In particular, since the fluorinated aliphatic ring is a fluorinated aliphatic ring having a heterocyclic structure having 1 to 2 etheric oxygen atoms in the skeleton, it is easy to produce a polymer from a monomer. Is preferable from the viewpoint of easy availability.
The fluorine-containing aliphatic ring may have a substituent.

Preferred fluorine-containing polymers include the following fluorine-containing cyclic polymers (I ′) and fluorine-containing cyclic polymers (II ′).
Fluorine-containing cyclic polymer (I ′): a polymer having units based on a cyclic fluorine-containing 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.

In the formula, X ¹¹ , X ¹² , X ¹³ , X ¹⁴ , Y ¹¹ and Y ¹² are each independently a fluorine atom, a perfluoroalkyl group or a perfluoroalkoxy group.
The perfluoroalkyl group in X ¹¹ , X ¹² , X ¹³ , X ¹⁴ , Y ¹¹ and Y ¹² 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 ¹¹ , X ¹² , X ¹³ , X ¹⁴ , Y ¹¹ and Y ¹² include those in which an oxygen atom (—O—) is bonded to the perfluoroalkyl group. Specific examples include a trifluoromethoxy group.
X ¹¹ is preferably a fluorine atom.
X ¹² is preferably a fluorine atom, a trifluoromethyl group, or a perfluoroalkoxy group having 1 to 4 carbon atoms, more preferably a fluorine atom or a trifluoromethoxy group.
X ¹³ and X ¹⁴ are each independently preferably a fluorine atom or a C 1-4 perfluoroalkyl group, more preferably a fluorine atom or a trifluoromethyl group.
Y ¹¹ and Y ¹² are each independently preferably a fluorine atom, a perfluoroalkyl group having 1 to 4 carbon atoms, or a perfluoroalkoxy 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).
Preferable specific examples of compound (2) include compounds (2-1) to (2-2).

The fluorine-containing cyclic polymer (I ′) may be composed only of units formed by the cyclic fluorine-containing monomer, and is a copolymer having the units and other units. Also good.
However, the proportion of the units based on the cyclic fluorinated monomer in the fluorinated cyclic polymer (I ′) is 20 mol with respect to the total of all repeating units constituting the fluorinated cyclic polymer (I ′). % Or more 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 units formed by cyclopolymerization of the “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 the formula, 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 3 carbon atoms. It 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 units formed by the cyclopolymerization of the compound (3) include the following units (3-1) to (3-4).

As the fluoropolymer, 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 fluorinated aliphatic ring containing an ether oxygen atom in the main chain and a carboxy group or alkoxycarbonyl group at the end of the main chain. Is mentioned.

<Coating solution>
In the present invention, the coating liquid used for forming the pattern film with R is obtained by dissolving the polymer (A) in a solvent, or other than the polymer (A) and the polymer (A). Components are dissolved in a solvent.
Any solvent can be used as long as it dissolves each component contained in the coating solution, and a solvent that dissolves at least the polymer (A) is used.
When other components are included, the solvent alone can dissolve the polymer (A), and the solvent alone can be used to form a uniform solution. Moreover, you may use together the other solvent which melt | dissolves this other component.

  As said other component, as above-mentioned, it is preferable to contain a silane coupling agent or a compound (C), and it is especially preferable to contain a silane coupling agent. Thereby, the thermal stability of the electric charge held by the electret formed is further improved, and the temporal stability and the like are also improved. The effect is particularly remarkable when the polymer (A) is a polymer having an aliphatic ring in the main chain and a carboxy group or an alkoxycarbonyl group as a terminal group. This is because the polymer (A) and the silane coupling agent cause nanophase separation, a nanocluster structure derived from the silane coupling agent is formed, and the nanocluster structure functions as a site for storing charges in the electret. It is assumed that there is.

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 a polymer (A) and a silane coupling agent are used in combination, the coating liquid is a polymer (A) solution in which the polymer (A) is dissolved in an aprotic fluorine-containing solvent, and the silane coupling agent is protonated. It is preferable to obtain each by preparing a silane coupling agent solution dissolved in a fluorinated solvent and mixing the polymer (A) solution and the silane coupling agent solution. The aprotic fluorinated solvent and the protic fluorinated solvent will be described later.

[Silane coupling agent]
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.

  0.1-20 mass% is preferable with respect to the total amount of a polymer (A) and a silane coupling agent, as for content of a silane coupling agent, 0.3-10 mass% is more preferable, 0.5 ˜5% by mass is most preferred. Within this range, the polymer (A) can be uniformly mixed, and phase separation is unlikely to occur when each component is dissolved in a solvent to form a coating solution.

[Compound (C)]
The compound (C) 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 compound (C) is 50 to 2,000, preferably 100 to 2,000. When the molecular weight of the compound (C) is less than 50, the molecular weight is low, so that the compound (C) is easily volatilized, and it is difficult to remain in the film after film formation. Further, when the molecular weight of the compound (C) is more than 2,000, the polymer (A) is easily separated into layers, and a problem is likely to occur in compatibility.

  As the compound (C), pentane-1,5-diamine, hexane-1,6-diamine, cyclohexane-1,2-diamine, cyclohexane-1,3-diamine, cyclohexane-1,4-diamine, 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) tolu More preferred is at least one selected from the group consisting of ethylene, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and polyethyleneimine, 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 compound (C) 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 content of the compound (C) is preferably 0.01 to 30% by mass of the content of the polymer (A), and more preferably 0.05 to 10% by mass. When the content is 0.01% by mass or more, an effect obtained by blending the compound (C) is sufficiently obtained, and sufficient thermal stability of the charge, stability over time, etc. can be secured as an electret. When the content is 30% by mass or less, the miscibility with the polymer (A) is good, and the distribution in the coating liquid becomes uniform.

[solvent]
The coating liquid contains at least a solvent that dissolves the polymer (A). The solvent may be appropriately selected depending on the polymer (A) to be used. For example, when the fluoropolymer is used as the polymer (A), a fluorine-containing organic solvent can be used.
As the fluorine-containing organic solvent, an aprotic fluorine-containing solvent is preferable. The “aprotic fluorine-containing solvent” is a fluorine-containing solvent having no proton donating property.
Examples of the aprotic fluorine-containing solvent include polyfluoroaromatic compounds such as 1,4-bis (trifluoromethyl) benzene, polyfluorotrialkylamine compounds such as perfluorotributylamine, and polyfluoros such as perfluorodecalin. Cycloalkane compounds, polyfluorocyclic ether compounds such as perfluoro (2-butyltetrahydrofuran), perfluoropolyethers, polyfluoroalkane compounds, hydrofluoroethers (HFE), and the like can be used.

As the fluorine-containing organic solvent, it is preferable to use only an aprotic fluorine-containing solvent because of its high solubility and good solvent.
The boiling point of the fluorine-containing organic solvent is preferably 65 to 220 ° C. If the boiling point of the fluorine-containing organic solvent is 100 ° C. or higher, it is easy to form a uniform film during coating.

The solvent for dissolving the silane coupling agent or compound (C) is preferably a protic fluorine-containing solvent. The “protic fluorine-containing solvent” is a fluorine-containing solvent having proton donating properties.
As the protic fluorine-containing solvent, for example, fluorine-containing alcohols such as 2- (perfluorooctyl) ethanol, fluorine-containing carboxylic acids, amides of fluorine-containing carboxylic acids, fluorine-containing sulfonic acids and the like can be used.

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 polymer (A) in the coating liquid is preferably 0.1 to 30% by mass, and more preferably 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.

In the electrostatic induction power generating element of the present invention, the electret included in the electrostatic induction power generating element is superior in the thermal stability of the retained charge as compared with the conventional electret. Therefore, it has excellent durability during power generation. Moreover, since it contains a specific material, the charge retention performance is high and a large power generation output can be obtained.
In particular, when the electret contains a material having an aliphatic ring in the main chain and a reaction product of a polymer having a carboxy group or an alkoxycarbonyl group as a terminal group and a silane coupling agent having an amino group, The thermal stability is further improved. Moreover, this electret is excellent also in the adhesiveness with respect to a pattern electrode and a board | substrate.

Since it is excellent in the thermal stability of the electric charge held by the electret, the electrostatic induction power generating element of the present invention has a feature that the characteristic is hardly deteriorated under a high temperature (for example, 80 to 120 ° C.) condition.
Further, the polymer (A) has a dielectric breakdown strength higher than 5 kV / 0.1 mm of Teflon (registered trademark) AF which is a conventionally used material (for example, a fluorine-containing aliphatic ring is included in the main chain). (The dielectric breakdown strength of CYTOP (registered trademark) which is a polymer having 11 kV / 0.1 mm). Since the dielectric breakdown strength is high, the amount of charge injected into the electret can be increased, and thereby the power generation amount of the power generation element including the electret can be improved.

Specific examples of the above embodiment will be described below as examples. The present invention is not limited to the following examples.
In each of the following examples, the volume resistivity value is a value measured according to ASTM D257.
The breakdown voltage is a value measured according to ASTM D149.
The relative dielectric constant is a value measured at a frequency of 1 MHz in accordance with ASTM D150.
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 a 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 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, the film thickness was measured using an optical interference film thickness measuring device C10178 manufactured by Hamamatsu Photonics.

<Production Example 1: Preparation of coating liquid M1>
(1) Preparation of polymer solution:
Perfluorobutenyl 45g of vinyl ether _{(CF 2 = CFOCF 2 CF 2} CF = CF 2), diisopropyl peroxydicarbonate powder 240g of ion-exchanged water, methanol 7 g, and as a polymerization initiator _(((CH 3) 2 CHOCOO ₂ ) 0.1 g of ₂ ) was put into a pressure-resistant glass autoclave having an internal volume of 500 mL. 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, 39 g of polymer B1 was obtained.
Measurement of the infrared absorption spectrum of the polymer B1, ^{1660 cm} -1 attributable to the double bond which was present in the monomer, there was no absorption in the vicinity of 1840cm ^-1.

The polymer B1 was heat treated in air at 250 ° C. for 8 hours and then immersed in water to obtain a polymer B2 having —COOH groups as terminal groups.
As a result of measuring an infrared absorption spectrum of the compression-molded film of the polymer B2, characteristic absorptions of 1775 and 1810 cm ⁻¹ derived from —COOH groups were observed.
The intrinsic viscosity [η] (30 ° C.) of the polymer B2 was 0.32 dl / g, and the weight average molecular weight Mw of the polymer determined from the result was 287,000.
The volume resistivity of polymer B2 was> 10 ¹⁷ Ωcm, the dielectric breakdown voltage was 19 kV / mm, and the relative dielectric constant was 2.1.
When differential scanning calorimetry (DSC) was performed on the polymer B2, the glass transition temperature (Tg) of the polymer B2 was 108 ° C.
The polymer B2 was dissolved in perfluorotributylamine at a concentration of 9% by mass to obtain a polymer solution P1.

(2) Formulation of silane coupling agent:
76.3 g of the polymer solution P1 and a silane coupling agent solution in which 0.3 g of γ-aminopropylmethyldiethoxysilane was dissolved in 4.4 g of 2- (perfluorohexyl) ethanol were mixed. Thereby, a uniform coating solution M1 was obtained.

<Production Example 2: Production of electret and power generation test of electrostatic induction power generation element>
Vapor deposition was performed on a Pyrex (registered trademark) glass substrate having a thickness of 0.7 mm using a small vacuum deposition apparatus (“VPC-060” manufactured by ULVAC), and Cr / Au / Cr (thickness of each layer: A metal thin film having a three-layer structure laminated in the order of 50 nm / 200 nm / 50 nm) was formed. A photoresist (“AZP-4400” manufactured by AZ Electronic Materials) was applied to the metal thin film with a thickness of about 3 μm, and exposure and development were performed through a photomask having a pattern shown in FIG. Subsequently, the Cr / Au / Cr layers were wet-etched to pattern the pattern shown in FIG. 15 to form the base electrode 62a, the guard electrode 62b, the wirings 63a and 63b, and the external terminal connection portions 64a and 64b. In FIG. 15, reference numeral 61 denotes a glass substrate. At this time, “Chrome Etching TW Solution” manufactured by Nihon Kasei Co., Ltd. was used for Cr etching, and “AURUM-302” manufactured by Kanto Chemical Co., Ltd. was used for Au etching.

As shown in FIG. 15, one end of each base electrode 62a is connected to the external terminal connection part 64a via the wiring 63a, and one end of each guard electrode 62b is connected to the external terminal connection part 64b via the wiring 63b. The configuration was communicated.
FIG. 16 is a partial cross-sectional view at position XX ′ in FIG.
In this production example, the width W ₁ of the base electrode 62a is 280 μm, and the electrode interval W ₂ is 25 μm. Width _{W 3} of the guard electrode 62b was 300 [mu] m.

Next, the coating liquid M1 was spin-coated on the glass substrate 61 at 1000 rpm for 20 seconds, and prebaked at 100 ° C. for 10 minutes. A series of operations from spin coating to pre-baking was repeated three times to form a coating film having a thickness of 15 μm, and then baked at 280 ° C. for 60 minutes to obtain a coating film.
A Cu layer having a thickness of about 200 nm was formed on the coating film by vapor deposition. A photoresist (“AZP-4400” manufactured by AZ Electronic Materials Co., Ltd.) was applied on the Cu layer with a film thickness of about 3 μm, and exposure and development were performed through a photomask having a pattern for an electret film. Subsequently, wet etching is performed with a 1/10/10 mixed solution of hydrogen peroxide / acetic acid / water, and patterning is performed so as to leave only the upper part of the base electrode 62a, and the line-shaped Cu layers are arranged at equal intervals. A mask was formed. At this time, the width of each line was 300 μm.

Next, dry etching using oxygen plasma was performed for 60 to 70 minutes with 100 W of RF power, and the coating film was patterned. As a result, a line-shaped square pattern film having a width of 300 μm was formed on each base electrode 62a.
Thereafter, the Cu layer was peeled off by wet etching similar to that described above to expose the upper surface of the cornered pattern film.

For the cornered pattern film, the corner portion R was determined by the following procedure.
The glass substrate 61 was cleaved, and a cross-sectional photograph was taken with a SEM (S-4300, manufactured by Hitachi High-Technologies Corporation) at a magnification of 4000 times. The photograph of the photographed cross-section photograph is taken into the KEYENCE digital microscope VHX-900, and the radius of the circle fitted to the roundness of the corner of the pattern edge of the pattern film is measured using the built-in software, and the measurement is performed. The value was determined as R. As a result, R was 0.25 μm.

Next, the square pattern film obtained as described above was heat-treated at the temperature shown in Table 1 for 1 hour.
When the cross section of the patterned film after heat treatment (hereinafter referred to as heat treated pattern film) was observed with an SEM, it was a curved surface continuously curved from the upper surface to the side surface. About this curved surface, R was calculated | required in the procedure similar to the above.
The measurement results are shown in Table 1 and FIG. In addition, FIG. 18 shows an SEM photograph actually used for the measurement of R in the case where heat treatment was performed at 300 ° C. for 1 hour.
As shown in Table 1 and FIG. 17, R of the formed curved surface was proportional to the heat treatment temperature.

Next, a corona discharge treatment was performed on the square pattern film or the heat treatment pattern film using a corona charging apparatus having a schematic configuration shown in FIG.
In the corona charging device, a corona needle 72 and an electrode 73 are arranged to face each other, and a high voltage is applied between the corona needle 72 and the electrode 73 by a DC high-voltage power supply device 71 (HAR-20R5; manufactured by Matsusada Precision Co., Ltd.). It can be applied. A grid 74 is disposed between the corona needle 72 and the electrode 73, and a grid voltage can be applied to the grid 74 from a grid power supply 75. As a result, the negative ions discharged from the corona needle 72 are made uniform by the grid 74, and then poured onto the pattern film on the surface of the glass substrate 61 placed on the electrode 73, so that charges are injected. . In order to stabilize the charge injected into the pattern film, the hot plate 76 can heat the pattern film during the charge injection process to a glass transition temperature or higher. Reference numeral 77 is an ammeter.
In this production example, the heating temperature of the square pattern film or the heat-treated pattern film by the hot plate 76 was set to 120 ° C., which is 12 ° C. higher than the glass transition temperature (108 ° C.) of the polymer (polymer B2) used.
Then, a high voltage of −8 kV was applied between the corona needle 72 and the electrode 73 for 10 minutes in an air atmosphere. The grid voltage between them was set to −1,100V.

About the obtained electret, when the surface potential immediately after inject | pouring an electric charge was measured in the following procedures, it was -600V.
An average value obtained by measuring the surface potential of nine measurement points on the electret (measured on a square of 6 mm square at intervals of 3 mm from the center of the patterning film) using a surface potentiometer (model 279; manufactured by Monroe Electronics) The same).
Subsequently, using the obtained electret, a power generation test was performed assuming that it was applied as an electrostatic induction power generation element. This power generation test was performed according to the method of Example 4 described in International Publication No. 2008/114489 pamphlet.
With respect to the electret, a counter substrate as shown in FIG. 1 (second substrate 21 with electrode 22 formed on the surface, width of electrode 22: 300 μm, electrode spacing: 15 μm), and spacing with electret is 100 μm. They were arranged in parallel so that the vibration was 1G, the vibration frequency was 20 Hz, and the amplitude was 1.2 mm. Meanwhile, the voltage change was measured through an external load and the amount of power generation was measured, and it was confirmed that 120 μW power generation was possible.
From this result, it was found that the electret of the present invention can be applied as an electrostatic induction power generating element.

[Thermal stability test]
About the obtained electret, the influence which said R has on the thermal stability in 100 degreeC was evaluated in the following procedures supposing the electrostatic induction type power generating element for sensor power supplies.
The glass substrate 61 on which the electret was formed was stored at 100 ° C. in a constant temperature layer. When a predetermined time (0 hours (h), 3h, 6h, 20h, 25h, 45h, 100h, 115h, 300h) has elapsed since the start of storage, the substrate 61 is taken out from the apparatus and returned to room temperature, and the same procedure as described above is performed. The surface potential was measured.
From the measurement results, the surface potential remaining rate (%) was calculated by the following formula.
Surface potential remaining rate (%) = surface potential measured at each elapsed time (V) / surface potential at start of test (V) × 100

  The results are shown in Table 2 and FIG. As shown in the results, the electret having the R of 1.0 to 3.7 μm had a high surface potential remaining rate. On the other hand, the electret using the cornered pattern film having the R of 0.25 μm and not subjected to the heat treatment had a low surface potential remaining rate.

<Production Example 3: Production of electret>
In the manufacturing example 2, the width of the base electrode is 130 μm, the width of the guard electrode is 150 μm (the electrode interval is not changed), and the width of the pattern film is 150 μm. Then, a heat treatment pattern film was formed, and R was measured. The results are shown in Table 3.

  Next, charges were injected into the cornered pattern film or the heat-treated pattern film in the same manner as in Production Example 3 to obtain electrets, and a thermal stability test was performed. The results are shown in Table 4. As shown in the results, the electret having R of 1.1 to 4.0 μm had a high surface potential remaining rate. On the other hand, the electret using the cornered pattern film with R of 0.2 μm and not subjected to heat treatment had a low surface potential remaining rate.

  DESCRIPTION OF SYMBOLS 11 ... First substrate, 12 ... Electrode, 13 ... Pattern film, 14 ... Guard electrode, 21 ... Second substrate, 22 ... Electrode, 30 ... Substrate with electrode, 31 ... Pattern film with corner, 31 '... With R Pattern film 41... Coating film, 41 ′ Pattern film with R, 42. Resist film, 42 ′ Resist mask, 43. Mask, 44. Resist film, 44 ′ Resist mask, 45. Resist mask, 46 ... mold, 47 ... polymer film, 51 ... coating liquid, 51 '... pattern liquid layer, 51 "... pattern film with R, 52 ... screen, 53 ... oil repellent part, 61 ... glass substrate, 62a ... base Electrode, 62b ... Guard electrode, 63a, 63b ... Wiring, 64a, 64b ... External terminal connection site, 71 ... DC high voltage power supply device, 72 ... Corona needle, 73 ... Electrode, 74 ... Gr De, 75 ... power grid, 76 ... hot plate, 77 ... ammeter

Claims (8)

A substrate, a pattern electrode formed on the substrate, and an electret that covers the pattern electrode and injects a charge into a pattern film formed in a pattern corresponding to the pattern electrode;
The pattern film contains a polymer (A) having an aliphatic ring in the main chain or a material (A ′) derived from the polymer (A),
An electrostatic induction power generating element having a curved surface with a radius of curvature of 0.5 to 15 μm that curves continuously from the upper surface to the side surface of the pattern film.   The electrostatic induction power generating element according to claim 1, wherein the polymer (A) is a fluoropolymer having an aliphatic ring in the main chain.   The electrostatic induction power generating element according to claim 1, wherein the polymer (A) is a polymer having an aliphatic ring in a main chain and a carboxy group or an alkoxycarbonyl group as a terminal group.   The electrostatic material according to any one of claims 1 to 3, wherein the material (A ') is a material containing a reaction product of the polymer (A) and a silane coupling agent having an amino group. Inductive power generation element. A method for producing the electrostatic induction power generating element according to any one of claims 1 to 4,
An electrode forming step of forming a patterned electrode on the substrate;
A pattern film forming step of forming the pattern film on the pattern electrode;
A charge injection step of injecting charges into the pattern film to form electrets;
A method for manufacturing an electrostatic induction power generating element.   In the pattern film forming step, a coating liquid containing the polymer (A) is applied on the substrate on which the pattern electrode is formed, and baked to form a coating film. The coating film is formed on the pattern electrode. To form a pattern film substantially having no curved surface with a radius of curvature of 0.5 to 15 μm that is continuously curved from the upper surface to the side surface, and heat-treating the pattern film, The method for manufacturing an electrostatic induction power generating element according to claim 5, wherein a curved surface having a curvature radius of 0.5 to 15 μm that is continuously curved from the upper surface to the side surface of the pattern film is formed.   The method for producing an electrostatic induction power generating element according to claim 6, wherein the heat treatment is performed at a glass transition temperature of the polymer (A) + 20 ° C. or higher.   The coating liquid contains, as the polymer (A), a polymer having an aliphatic ring in the main chain, a carboxy group or an alkoxycarbonyl group as a terminal group, and a silane coupling agent having an amino group. The manufacturing method of the electrostatic induction type power generating element of Claim 6 or 7 containing.