JP2008084581A - Ferroelectric composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for ferroelectric application capable of forming a ferroelectric layer of an even thickness without unevenness even if formed in an application method. <P>SOLUTION: The composition for ferroelectric application mainly composed of octyl acid metallic compound contains a binder and at least one kind of solvent. Metal of the above octyl acid metallic compound consists of at least two kinds selected from a group of Zr, Ba, Ti, La, and Pb, contained by 1 to 10 wt.% to the composition for the ferroelectric application as a whole. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

Field of Invention

  The present invention relates to a ferroelectric coating composition containing metal octylate as a main component. More specifically, the present invention does not cause unevenness even when formed by a coating method, and can form a ferroelectric layer having a uniform thickness. The present invention relates to a dielectric coating composition.

  Perovskite ferroelectric materials such as barium titanate, lead titanate, and lead zirconate titanate are widely applied to memory elements, piezoelectric elements, display substrates, and the like. For example, a display substrate for an electroluminescent display element has a structure in which a light emitting layer is provided on a ferroelectric layer. Such a ferroelectric layer is formed by forming a ferroelectric material as described above on a substrate such as glass by a vacuum film formation method or a sol-gel method.

  In recent years, with the increase in size of display elements, it has become an important issue to uniformly provide a ferroelectric layer on a large-area substrate.

  However, in the conventional vacuum film forming method, it is necessary to increase the size of the vacuum vapor deposition apparatus itself with an increase in the size of the substrate, resulting in an increase in manufacturing cost.

  In addition, as a method for forming a ferroelectric layer by a sol-gel method, for example, a method for producing a lead zirconate titanate film using hydrolysis of a metal alkoxide is known, but the metal alkoxide is present even in the presence of a slight amount of moisture. Since hydrolysis occurs, there is a problem that the storage stability of the material is low and it is not suitable for mass production.

  In order to solve such a problem, Japanese Patent Application Laid-Open No. 5-58636 (Patent Document 1) discloses a thermal decomposition or oxidative decomposition reaction without preparing a sol-like or gel-like lead zirconate titanate precursor product. It has been proposed to directly form a lead zirconate titanate thin film alone. According to this publication, for example, metal octylates such as lead octylate, zirconyl octylate, and titanium octylate are mixed in an n-butanol solution, and the mixed solution is dried and then fired at 500 ° C. or higher. Shows that a ferroelectric made of lead zirconate titanate can be produced.

The metal octylate disclosed in the above publication is more stable than the metal alkoxide used in the sol-gel method, and can be applied onto the substrate by a wet coating method or the like, so it is considered suitable for a large display substrate. It is done.
JP-A-5-58636

  However, when the metal octylate is mixed with a solvent to prepare a coating solution, and this coating solution is applied onto a substrate to form a ferroelectric layer, the wettability of the coating solution with respect to the substrate is low. In some cases, an uneven ferroelectric layer is formed. In addition, when a ferroelectric layer is further provided by a coating method on a thick film dielectric layer such as PZT (lead zirconate titanate) or PMN (magnesium lead niobate), Since the wettability is low, an uneven ferroelectric layer may be formed.

  In the present invention, in the ferroelectric coating composition mainly composed of metal octylate, even when formed by a coating method by adding a specific amount of a binder component, there is no unevenness and uniform The knowledge that a ferroelectric layer having a thickness can be formed was obtained. The present invention is based on such knowledge.

  Accordingly, an object of the present invention is to provide a ferroelectric coating composition that does not cause unevenness even when formed by a coating method and can form a ferroelectric layer having a uniform thickness.

A ferroelectric coating composition according to the present invention is a ferroelectric coating composition comprising a metal octylate as a main component,
Comprising a binder and at least one solvent,
The metal of the octylic acid metal compound is at least two or more selected from the group of Zr, Ba, Ti, La, and Pb;
It is characterized in that it is contained in an amount of 1 to 10% by weight based on the whole composition for applying a ferroelectric substance.

  In a preferred embodiment of the present invention, at least two kinds of the metal octylates are contained.

  Moreover, as an aspect of the present invention, the binder is preferably ethyl cellulose.

  Furthermore, as an aspect of the present invention, it is preferable that the solvent is selected from the group consisting of isopropyl alcohol, 1-butanol, and α-terpineol.

  In a preferred embodiment of the present invention, isopropyl alcohol is contained in an amount of 40% by weight or more based on the entire solvent.

  In the above-described aspect of the invention, it is preferable that isopropyl alcohol is contained in an amount of 40% by weight or more, 1-butanol is 40% by weight or less, and α-terpineol is contained in an amount of 40% by weight or less with respect to the entire solvent. .

  Furthermore, in the embodiment of the present invention, it is preferable to further comprise an acetylene alcohol surfactant.

As another aspect of the present invention, a method for producing a display substrate comprising a ferroelectric film comprises a step of applying the above-described ferroelectric coating composition on a substrate or a dielectric layer;
Firing the applied ferroelectric coating composition to produce a ferroelectric film; and
It is characterized by comprising.

  As an aspect of the present invention, the applied ferroelectric coating composition may be dried before firing.

  Moreover, the display board obtained by said manufacturing method is provided as another aspect of this invention.

  According to the present invention, even when formed by a coating method, unevenness cannot be produced and a ferroelectric layer having a uniform thickness can be formed.

Ferroelectric coating composition The ferroelectric coating composition according to the present invention can form a ferroelectric film on a substrate by a coating method such as a spin coating method. The main component is a metal octylate, a binder. , And at least one solvent as an essential component.

  The 1-butanol solution of an octylate metal compound such as titanium octylate, which has been conventionally used as a ferroelectric material, has a surface tension of about 24 mN / m, and has a sufficiently low surface tension from the viewpoint of wettability. Have.

  However, when such a low surface tension coating solution is applied to a glass substrate or the like, the coating solution is repelled without spreading on the substrate or unevenness occurs.

  In the present invention, the above problem is solved by adding 1 to 10% by weight of a binder in addition to the metal octylate compound and the solvent. The reason for this is not clear, but is considered as follows.

  That is, a solution in which a metal octylate compound is dissolved in a solvent has low surface tension but low thixotropic properties. For this reason, the solution viscosity at low shear stress is low, and when such a coating solution is applied to a substrate, the coating solution is likely to move on the substrate, and as a result, the coating solution is repelled against the substrate. It is done. Similarly to the above, if the viscosity of the coating solution is low due to low shear stress, convection occurs in the coating solution, resulting in uneven portions in the coating solution, resulting in unevenness in the coating film. It is thought to do.

  In the present invention, by adding 1 to 10% by weight of the binder to the coating solution, the thixotropic property can be increased. As a result, even when formed by a coating method, unevenness cannot be achieved and the thickness is uniform. It is considered that a ferroelectric layer can be formed.

  Hereinafter, each component constituting the ferroelectric coating composition according to the present invention will be described.

(1) Metal octylate The metal octylate composing the ferroelectric coating composition according to the present invention is zirconium octylate, barium octylate, titanium octylate, lanthanum octylate, or lead octylate, preferably These compounds contain at least two of these compounds. For example, barium titanate (BaTiO ₃ ) can be produced by firing a mixture of barium octylate and titanium octylate, and a mixture of zirconium octylate, titanium octylate, and zirconium octylate at 500 ° C. By baking as described above, lead zirconate titanate (Pb ₂ Zr _x TiO _1-x O ₃ ) can be produced.

  By using a ferroelectric material containing such a metal octylate compound, it is possible to directly perform only pyrolysis or oxidative decomposition reaction without preparing sol-like and gelled lead zirconate titanate precursor products. A lead zirconate titanate thin film can be formed. A material obtained by dissolving a metal alkoxide compound such as barium titanium ethylhexanoisopropoxide in a solvent such as isopropyl alcohol, which is a ferroelectric material used in a normal sol-gel method, is dropped on a glass substrate. It becomes powder after the solvent is dried. This is thought to be because the metal alkoxide was rapidly hydrolyzed by moisture in the air, but such a powdery state causes a problem when it is necessary to wipe off. Moreover, since it pulverizes by drying of a solvent, when using the coating device which sprays from a nozzle when applying the said material on a base material, a nozzle may be clogged.

  On the other hand, when the coating liquid containing the octylic acid metal compound as described above is used, the state of the coating film is maintained even after the solvent is dried, and even when wiping needs to occur, the solvent Can be easily wiped off. In addition, there is an advantage that the nozzle is not clogged even when the coating liquid is applied onto the substrate using a device that sprays and applies from the nozzle.

(2) Binder The content of the binder used in the present invention is 1 to 10% by weight with respect to the entire ferroelectric coating composition. By setting the addition amount of the binder to 1% by weight or more, unevenness of the ferroelectric coating film can be significantly reduced. On the other hand, if it exceeds 10% by weight, the viscosity of the coating solution becomes too high, so that the coating solution cannot be applied by a coating method such as spin coating. Moreover, when there is much content of a binder, there exists a tendency for the film | membrane after baking to become sparse. This is because the binder component (resin component) burns or evaporates after the film is formed by heating or during the film formation. Therefore, if the wettability with the substrate can be ensured, the binder content is preferably as low as possible. The addition amount of the binder is more preferably 2 to 5% by weight.

  Binders include cellulose derivatives such as ethyl cellulose, hydroxypropyl cellulose, methyl cellulose and nitrocellulose, polyester resins such as polyacrylic esters and alkyd resins, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, vinyl Acetic acid, methyl methacrylate, methyl acrylate, ethyl acrylate, ethyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, 2-hexyl acrylate, lauryl methacrylate, stearyl methacrylate, stearyl acrylate, dodecyl methacrylate , Dodecyl acrylate, hexyl methacrylate, octi Methacrylate, octyl acrylate, cetyl methacrylate, cetyl acrylate, nonyl acrylate, decyl methacrylate, decyl acrylate, cyclohexyl methacrylate, cyclohexyl acrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate, 2 (2-ethoxyethoxy) ethyl acrylate, 2-hydroxyethyl methacrylate, diacetone acrylamide, N, N-diethylacrylamide, N, N-dimethylaminopropylacrylamide, isopropylacrylamide, diethylaminoethyl methacrylate, t-butyl methacrylate, N, N-dimethylacrylamide, α-methylstyrene, Styrene, vinyl toluene, N-vinyl Examples thereof include copolymers comprising monomers such as 2-pyrrolidone, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, polyolefin resins such as ethylene-vinyl acetate copolymers, polyvinyl formal, and polyvinyl butyral. .

(3) Solvent The ferroelectric coating composition according to the present invention contains a solvent as an essential component. The solvent is not particularly limited as long as the mixture of the metal octylate compound and the binder can be kept in a uniform state. For example, methanol, ethanol, isopropanol, 1-butanol, 2-ethylhexanol, Other than alcohols such as 1-butoxy-2-propanol, α-, β-, and γ-terpineol, and alcohols, ethylene glycol monoalkyl ethers, ethylene glycol dialkyl ethers, diethylene glycol monoalkyl ethers, diethylene glycol dialkyl ethers , Ethylene glycol monoalkyl ether acetates, ethylene glycol dialkyl ether acetates, diethylene glycol dialkyl ether acetates, propylene glycol monoalkyl ether Ethers, propylene glycol dialkyl ethers, propylene glycol monoalkyl acetates, can be used propylene glycol dialkyl ether acetates, and the like.

  In the present invention, among the solvents described above, alcohols such as methanol, ethanol, isopropanol, 1-butanol, 2-ethylhexanol, 1-butoxy-2-propanol, α-, β-, and γ-terpineol are used. They can be preferably used, and these may be used alone or in combination. Solvents other than alcohols include ethylene glycol monoalkyl ethers, ethylene glycol dialkyl ethers, diethylene glycol monoalkyl ethers, diethylene glycol dialkyl ethers, ethylene glycol monoalkyl ether acetates, ethylene glycol dialkyl ether acetates, diethylene glycol dialkyl ethers Acetates, propylene glycol monoalkyl ethers, propylene glycol dialkyl ethers, propylene glycol monoalkyl acetates, propylene glycol dialkyl ether acetates can be preferably used, and these may be added to the above alcohols alone or in combination of two or more. Good.

  As described above, the ferroelectric coating composition containing the binder is excellent in the wettability of the coating solution with respect to the substrate and can suppress unevenness of the coating film. When foreign matter is attached on the top, the coating solution may be repelled, or the coating solution may not enter the concave portion and a uniform coating film may not be formed. According to the present invention, by using the alcohol solvent described above as a solvent, a uniform coating film without unevenness can be formed even when the substrate surface is uneven or foreign matter is adhered on the substrate. I found out that I can do it.

  Among the alcohol solvents described above, isopropyl alcohol is preferable, and it is particularly preferable that 40% by weight or more of isopropyl alcohol is contained with respect to the solvent. Further, when isopropyl alcohol is contained in an amount of 40% by weight or more based on the whole solvent, it is more preferable that 1-butanol is contained in an amount of 40% by weight or less and α-terpineol is contained in an amount of 40% by weight or less. Is preferably 60% by weight or more, 1-butanol is 20% by weight or less, and α-terpineol is preferably 20% by weight or less.

  In addition, you may use 1 type or in mixture of 2 or more types of solvents other than alcohol mentioned above in alcohol solvent.

(4) Other components The ferroelectric coating composition according to the present invention may further contain an acetylene alcohol surfactant. Addition of the acetylene alcohol surfactant further improves the wettability of the coating solution. Examples of the acetylene alcohol surfactant include 3,5-dimethyl-1-hexen-3-ol (Surfinol * 61, manufactured by Air Products and Chemical), but are not limited thereto. .

Display substrate including ferroelectric layer The ferroelectric coating composition according to the present invention can be widely used as a dielectric material for memory elements, piezoelectric elements, etc., but when a dielectric layer is provided on a large substrate as described above In addition, even when formed by a coating method, unevenness cannot be produced, and a ferroelectric layer having a uniform thickness can be formed. Therefore, it can be particularly suitably used for large display substrates such as electroluminescent display elements. Hereinafter, a display substrate for an electroluminescent display element will be described as an example using the composition for applying a ferroelectric according to the present invention as a dielectric material.

  FIG. 1 shows a cross-sectional structure as an example of a display substrate for an electroluminescent display element. The display substrate for the electroluminescent display element includes a first electrode layer 2, a thick film dielectric layer 3, a thin film dielectric layer 4, a light emitting layer 5, a thin film dielectric layer 6, and a second electrode layer 7 on the substrate 1. Has a structure provided. The thin film dielectric layer 4 may be a multilayer. Hereinafter, each layer will be described.

(1) Substrate As a substrate, alumina (Al ₂ O ₃ ), quartz glass (SiO ₂ ), magnesia (MgO), forsterite (2MgO · SiO ₂ ), steatite (MgO · SiO ₂ ), mullite (3Al ₂ Use ceramic substrates such as O ₃ .2SiO ₂ ), beryllia (BeO), zirconia (ZrO ₂ ), aluminum nitride (AlN), silicon nitride (SiN), silicon carbide (SiC + BeO), crystallized glass, quartz glass, and the like. Can do. In addition, Ba-based, Sr-based, and Pb-based perovskites can also be used.

  Further, as the substrate, high heat-resistant glass or the like may be used, or a metal substrate or the like that has been subjected to insulation treatment such as enamel may be used.

(2) First electrode layer The first electrode layer is made of, for example, a metal having good conductivity such as a metal such as Pd or an alloy such as Ag / Pd. In addition to these materials, noble metals such as Au, Pt, and Ir, refractory metals such as Ni, W, Mo, Nb, and Ta, and alloys of these noble metals or refractory metals may be used.

  The first electrode layer 2 is formed on one surface of the substrate 1 and is usually formed by patterning into a predetermined stripe shape. The first electrode layer is formed by mixing the above-mentioned noble metal or refractory metal or their alloy powder, for example, in a solvent, or in a solvent and a resin, or by adding glass frit or the like, and kneading these. The obtained paste is applied by a method such as screen printing to form a desired pattern on the substrate and fired. Alternatively, the paste may be applied to the entire surface of the substrate instead of being patterned and baked, followed by patterning by photolithography.

  The first electrode layer is patterned as described above after a metal layer or an alloy layer is uniformly formed on the entire surface of the substrate by plating, vapor deposition, or sputtering using the above metal or alloy. Alternatively, patterning can be performed by plating, vapor deposition, or sputtering through a mask pattern.

  The thickness of the first electrode layer varies depending on the forming method, but in the case of a method suitable for forming a thick film such as screen printing, it is preferably about 1 to 5 μm, for forming a thin film such as vapor deposition or sputtering. In the case of a suitable method, it is preferably about 0.1 to 1.0 μm.

(3) Thick Film Dielectric Layer The thick film dielectric layer 3 is obtained by mixing dielectric powder with, for example, a solvent, or a solvent and a resin, or adding glass frit and the like, and kneading them. The paste thus formed is applied by a method such as screen printing so as to cover the first electrode layer 2 on the substrate 1 and is baked. In the present invention, it is preferable to place a reference plate having a smooth surface on the upper surface of the thick dielectric layer before firing, compress it by an isostatic pressing method, and then perform firing. The conditions for the isostatic pressing are preferably from 10 to 500 MPa, particularly from 100 to 500 MPa at room temperature to 300 ° C. By setting the pressure to 10 MPa or more, the density of the dielectric powder becomes high after the hydrostatic pressing, and a thick film dielectric layer having excellent dielectric characteristics can be obtained. In addition, the upper limit value of the pressure is limited in a range substantially possible with an isostatic press.

  Needless to say, the formation of the thick dielectric layer is not limited to the isostatic pressing method, and can be formed by a normal sol-gel method, a MOD (Metal Organic Deposition) method, or the like.

Examples of the dielectric powder include BaTiO ₃ , (Ba _x Ca _1-x ) TiO ₃ , Ba _x Sr _1-x ) TiO ₃ , PbTiO ₃ , Pb (Zr _x Ti _1-x ) TiO ₃ (hereinafter, referred to as “dielectric powder”). Ferroelectrics having a perovskite structure such as PZT), composite perovskite ferroelectrics represented by Pb (Mg _1/3 Nb _2/3 ) O ₃ (hereinafter also referred to as PMN), Bi ₄ Ti ₃ It is possible to use a bismuth layered compound represented by O ₁₂ , SrBi ₂ Ta ₂ O ₉ , a tungsten bronze type ferroelectric represented by (Sr _x Ba _1-x ) Nb ₂ O ₆ , PbNb ₂ O ₆ or the like. it can.

Among these, perovskite-type dielectrics such as BaTiO ₃ , PZT, and PMN, which can achieve a higher dielectric constant and can be heat-treated at a lower firing temperature, are more preferable, and among them, a lead element in the chemical composition A dielectric material containing is more preferable. This dielectric containing lead is particularly suitable when glass is used as the substrate. In addition, a composite perovskite type compound containing Pb typified by PMN is called a relaxor and exhibits a high relative permittivity in a wide temperature range, and thus is preferable as a thick film dielectric material.

  The thickness of the thick film dielectric is preferably about 2 to 100 μm, and more preferably about 5 to 20 μm. If it is thicker than 100 μm, it will be difficult to densify, and if it is thinner than 2 μm, the effect of the step at the patterning portion in the first electrode layer will become large.

  The light emitting layer described later is electrically arranged in series with the thick film dielectric layer. Therefore, in order to efficiently apply a voltage to the light emitting layer when a voltage is applied from the outside, the thick film is used. The capacitance of the dielectric layer is preferably higher than the capacitance of the light emitting layer, specifically about 10 times. Note that the ratio between the capacitance of the thick dielectric layer and the capacitance of the light emitting layer is equal to the ratio between the “relative permittivity / film thickness” of each layer.

(4) Thin Film Dielectric Layer As described above, the thick film dielectric layer is formed by the isostatic pressing method, and thus the surface on the light emitting layer side is formed very flat. In the present invention, the thin film dielectric layer 4 is provided on the thick film dielectric layer 4 in order to improve the flatness and further improve the dielectric constant characteristics of the thick film dielectric layer.

  The thin film dielectric layer 4 is formed using the ferroelectric coating composition according to the present invention. First, on the thick dielectric layer 3 that has already been formed, a coating solution comprising the composition is applied to a method suitable for application, for example, a coating method such as a die coating method, a roll coating method, a blade coating method, or a spin coating method. To form a coating film. Next, the thin film dielectric layer 4 can be formed by drying the coating film in accordance with the composition of the coating solution and then performing baking.

  The thin film dielectric layer 4 may include other layers in addition to the layer prepared from the dielectric coating composition according to the present invention. This is because the flatness and electrical characteristics are further improved by stacking layers made of other materials. As a method for producing these other layers, the above-described wet coating and vacuum film formation can also be applied.

  Further, after forming a light emitting layer to be described later, a thin film dielectric layer 6 is provided on the light emitting layer 5. By providing the thin film dielectric layer, it is possible to prevent water vapor, oxygen, and the like from entering the phosphor side. When the thin film dielectric layer 6 is provided on the light emitting layer 5, the thin film dielectric layer can be formed in the same manner as described above.

  The film thickness of the thin film dielectric layer may be about 0.005 to 3 μm. The film thickness of the thin film dielectric layer 4 is preferably about 0.5 to 3 μm, more preferably about 1 to 2 μm. The thickness of the thin film dielectric layer 6 is preferably about 0.01 to 0.5 μm, more preferably about 0.015 to 0.1 μm. When the film thickness is less than 5 nm, it does not have a function as a film. When the film thickness exceeds 3 μm, cracks are likely to occur and the dielectric constant of the entire substrate increases. In some cases, a sufficient voltage is not applied to the phosphor material. The preferable film thickness differs between the thin film dielectric layers 4 and 6 because the surface roughness of the base on which the respective thin film dielectric layers are provided is different.

(5) Light-Emitting Layer The light-emitting layer 5 is formed on the thin film dielectric layer 4. As described above, the thin film dielectric layer has a very uniform surface and is flat, and even if unevenness or foreign matter is adhered on the thick film dielectric layer, the thin film dielectric layer By providing, the surface is flattened. Accordingly, since the light emitting layer is formed on a very flat and uniform surface, the light emitting layer has excellent light emitting characteristics.

The light emitting layer is made of a thin phosphor material. For example, as materials for obtaining red light emission, ZnS, Mn / CdSSe, etc., as materials for obtaining green light emission, ZnS: TbOF, ZnS: Tb, etc., as materials for obtaining blue light emission, SrS: Ce, (SrS _{: Ce / Zns) n, Ca} 2 Ga 2 S 4: Ce, Sr 2 Ga 2 S 4: Ce , etc., and as a material for obtaining a white light emitting SrS: Ce / ZnS: Mn, and the like.

  The light emitting layer can be formed by vapor deposition, sputtering, CVD, or the like using the phosphor material as described above.

  The thickness of the light emitting layer is preferably about 100 to 2000 nm, more preferably about 200 to 1500 nm.

(6) Second Electrode Layer Since the second electrode layer 7 is provided on the observer side, it is necessary to form it with a transparent electrode material so as not to interfere with light emission from the light emitting layer 5, that is, display.

Examples of the transparent electrode material include oxide conductive materials such as ITO (indium tin oxide), SnO ₂ , and ZnO—Al.

  The formation of the second electrode layer can be performed by vapor deposition or sputtering using the above oxide conductive material.

  The thickness of the second electrode layer is preferably about 50 to 200 nm.

  Examples The present invention will be described in more detail with reference to examples, but the scope of the present invention is not limited to these examples.

Example 1
1. Preparation of ferroelectric coating composition Barium octyl titanate (Asahi Denka) is used as the metal octylate, and ethyl cellulose (Ethocel, manufactured by Nisshin Kasei Co., Ltd.) with a viscosity of 7 cP is used as the binder. A ferroelectric coating composition was prepared by mixing each component so as to have the composition shown in Table 1 below. In addition, the metal octylate was mix | blended so that it might become the addition amount of 5 weight% and a binder 2 weight%.

  The wettability of the composition to the glass substrate when the composition was applied onto the substrate was evaluated. The obtained composition had a contact angle of 5 ° or less with respect to the glass substrate and was difficult to measure. Therefore, one drop of the composition was dropped on glass (CP-600V, manufactured by Central Glass), and wettability was evaluated by visually observing the state of wetting and spreading on the glass substrate.

The evaluation criteria were as follows.
A: The liquid level in the central part of the dropping is flat so that it adheres to the substrate, and only the peripheral part of the liquid level is raised, and there are many flat parts in the liquid level (very good wettability) )
○: The liquid level at the dropping center is flat so that it sticks to the substrate, and only the peripheral part of the liquid level is raised (good wettability)
Δ: Liquid level at the center of dripping is not flat but slightly raised (normal wettability)
×: State where the liquid level at the center of the dropping is raised (poor wettability)

Next, each composition shown in Table 2 below was applied on a silicon wafer substrate by spin coating, and baked at a peak temperature of 650 ° C. for 10 minutes in a continuous baking furnace to form a BaTiO ₃ film on the glass substrate. did. The rotation speed of the spin coater was adjusted so that the BaTiO ₃ film thickness after firing was 50 nm (measured with a step gauge). In addition, the numerical value in a table | surface represents weight%.

The surface of the obtained fired film was observed with an optical microscope to evaluate unevenness of the fired film. The evaluation criteria were as follows.
○: There was no unevenness and the film had a uniform thickness. △: Unevenness that seems to be caused by convection of the coating liquid occurred, and the unevenness was generated to the extent that it was not visually recognized. The unevenness was generated to such an extent that the unevenness as shown in FIG. 2 was visually recognized. The evaluation results were as shown in Table 2.

  Although the fired film of Example 26 was not uneven, there was a problem that the film density after firing decreased as shown in FIG.

  Next, a ferroelectric coating composition was prepared by changing the viscosity of the resin used. The composition of each prepared composition was as shown in Table 3 (the numerical values in the table represent% by weight).

  About the obtained composition, viscosity measurement was performed on rheometer RS-150 (product made from HAAKE) on the conditions of cone | corn φ = 60mm, angle 1 degree, and 25 degreeC.

  Moreover, about the obtained composition, the fired film was produced like the above, and the presence or absence of the nonuniformity was evaluated.

The evaluation results are as shown in Table 3.

It is the schematic cross section which showed an example of the electroluminescent display element using the composition for ferroelectric coating by this invention. It is a photograph observing unevenness when a film is formed by firing (area approximately 3 × 2.3 mm) It is an electron micrograph (50,000 times) of a sample with a low film density in the obtained fired film.

Claims (12)

A ferroelectric coating composition comprising a metal octylate compound as a main component,
Comprising a binder and at least one solvent,
The metal of the octylic acid metal compound is at least two or more selected from the group of Zr, Ba, Ti, La, and Pb;
A composition for applying a ferroelectric material, wherein the binder is contained in an amount of 1 to 10% by weight based on the whole composition for applying a ferroelectric material.   The ferroelectric coating composition according to claim 2, wherein at least two kinds of the metal octylates are contained.   The ferroelectric coating composition according to claim 1, wherein the binder is ethyl cellulose.   The ferroelectric coating composition according to claim 1, wherein the solvent is selected from the group consisting of isopropyl alcohol, 1-butanol, and α-terpineol.   The composition for ferroelectric coating according to claim 6, wherein isopropyl alcohol is contained in an amount of 40% by weight or more based on the total amount of the solvent.   6. The composition for applying a ferroelectric substance according to claim 5, comprising isopropyl alcohol in an amount of 40% by weight or more, 1-butanol in an amount of 40% by weight or less, and α-terpineol in an amount of 40% by weight or less based on the whole solvent. object.   The ferroelectric coating composition according to claim 1, further comprising an acetylene alcohol surfactant. A method of manufacturing a display substrate comprising a ferroelectric film,
Applying a ferroelectric coating composition according to any one of claims 1 to 7 on a substrate or a dielectric layer;
Firing the applied ferroelectric coating composition to produce a ferroelectric film; and
A method comprising the steps of:   The method according to claim 8, further comprising a step of drying the applied composition for applying a ferroelectric substance before firing.   The method according to claim 8 or 9, wherein the ferroelectric film has a thickness of 30 to 500 nm.   The display board obtained by the method as described in any one of Claims 8-10.   Use of the ferroelectric coating composition according to any one of claims 1 to 7 for a ferroelectric layer for a display substrate, a ferroelectric layer for a capacitor, or a ferroelectric layer for a memory element.