JPH11231620A - Image forming method using ferroelectric body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute electrification, image exposure and development in a bright room by setting the volume average particle size of a ferroelectric body being an inorganic oxide ferroelectric body to a specified value. SOLUTION: The ferroelectric element is constituted of a ferroelectric layer 1 and a conductive supporter layer 4. The volume average particle size of the inorganic oxide ferroelectric body 2 used for the layer 1 is within 0.5 to 3.0 μm. Dipoles of the body 2 are arrayed in one direction by corona electrification. The dipoles are inverted by subjecting to the part corresponding to an image part or a non-image part to a corona electrification through a mask. After the layer 1 where the dipoles are inverted is heated to <= the ferroelectric and paraelectric phase change point (Curie point) of the body 2, an electrostatic latent image is made to appear by cooling. Thereafter, the electrostatic latent image is developed into a visible image by using electrostatic power toner or liquid toner at a temperature at which the body 2 shows the ferroelectricity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method, and more particularly, to an image forming method of forming an electrostatic latent image using a ferroelectric substance and then visualizing the electrostatic latent image using toner. About the method.

[0002]

2. Description of the Related Art In general, an electrophotographic method, which is one of image forming methods used in copying machines and printers, charges a photosensitive member having a photosensitive layer composed of a photoconductor and then exposes the photosensitive member by image exposure. Form an electrostatic latent image on the photosensitive layer of the body, develop it with electrostatic toner, transfer the toner image on the photoconductor to film, plain paper, etc., and fix the transferred toner image To form a visible image. To form the same visible image again, the toner adhered to the photoconductor is cleaned, charged again, and the same steps such as image exposure, transfer, and fixing are repeated. Therefore, when a plurality of identical images are created, the copying speed is limited, and high-speed copying is difficult.

In order to solve this problem, "Photographic Science and Engineering (Ph.
otographic Science and Engineering ”Vol. 25 (1981)
Years) pp. 35-39 and 209-215 propose an electrophotographic photosensitive member having memory properties. According to this method, once image exposure is performed, a plurality of copies can be made by repeating the above-described steps from development to fixing.

However, the electrophotographic photoreceptor described in this document cannot store a latent image formed by image exposure for a long period of time, has a problem in memory, and cannot store it in a bright room. In addition, printing durability and environmental stability are poor, and they have not been put to practical use.

Also, a ferromagnetic material is used to form a latent image having memory properties according to the magnitude of its magnetic susceptibility, developed using a magnetic toner, transferred, fixed and transferred to a plurality of visible images by one image writing. Such as "Repro MG8000" (manufactured by Iwasaki Tsushinki), "Varipress M450" (Bull-Nipson)
Has been put to practical use.

Further, Japanese Patent Application Laid-Open No. Hei 5-221139 discloses that after an organic ferroelectric layer is subjected to a poling (dipole orientation) treatment, light is applied to write an image so that the exposed portion has a Curie point (Tc) or more. To form a latent image,
A recording method capable of continuous copying and storing a latent image has been proposed.

[0007]

As described above, the conventional electrophotographic method using a photoconductor is used in various fields such as a printer, a copying machine, and a direct plate making. Must be performed in a dark room,
Also, in order to create a plurality of identical images, the toner attached to the photoconductor is cleaned and then charged again, and then the same processes such as image exposure, transfer, and fixing are repeated. High-speed copying is difficult.

Further, in the method using a ferromagnetic material, a magnetic head is used as a writing head, so that the resolution is limited, and it is difficult to produce a color magnetic toner, so that a color image cannot be produced. There is a point.

Further, in writing an image using an organic ferroelectric substance, a method of irradiating light and heating an exposed portion to a temperature equal to or higher than the Curie point (Tc) to form a latent image is a method of forming a latent image. Due to the low mechanical strength, the surface is easily scratched by toner development or the like, and such scratches make it easier for toner to adhere to the non-image area, and the stain on the non-image area increases as the number of printed sheets increases. There is a problem. For this reason, there are problems that the method of toner development is limited and that the method is not suitable for printing many sheets.

Problems to be solved by the present invention are charging,
Image exposure and development can be performed in a bright room,
Colorization of images is possible, charging, image exposure, writing and erasing of images at any time are possible, it is possible to create multiple sheets of the same toner image with one image writing, and further mechanically An object of the present invention is to provide an image forming method using a ferroelectric material, which has high strength, is hardly scratched on the surface by toner development or the like, does not limit the method of toner development, and is suitable for printing many sheets.

[0011]

Means for Solving the Problems As a result of intensive studies, the present inventors have formed a latent image using a specific inorganic oxide ferroelectric and formed a toner image by electrophotography. Thus, the present invention has been completed.

That is, in order to solve the above problems, the present invention provides (1) a ferroelectric element in a ferroelectric element in a ferroelectric element having a ferroelectric layer containing a ferroelectric substance on a conductive support. A first step of arranging the dipoles of the body in one direction, (2) a second step of inverting the dipoles in a portion corresponding to an image portion or a non-image portion, and (3) a uniform Curie point of the ferroelectric layer. After heating below, cool to develop an electrostatic latent image
A step (4) of forming an electrostatic latent image using a toner, wherein the ferroelectric substance is an inorganic oxide ferroelectric substance and the volume average particle diameter thereof is Is in the range of 0.5 to 3.0 μm.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A ferroelectric element used in an image forming method of the present invention comprises a ferroelectric layer and a conductive support layer. As shown in FIG. The support layer may be in a state of being in close contact, or may have an intermediate layer provided between the ferroelectric layer and the support layer.

The inorganic oxide ferroelectric used for the ferroelectric layer may be capable of reversing the dipole orientation and the dipole in the image portion or the non-image portion by corona charging or the like. , Which decrease when the temperature is raised from room temperature.
Further, these inorganic oxide ferroelectrics preferably have a layered structure. These inorganic oxide ferroelectrics can be used alone or in combination of two or more.

The inorganic oxide ferroelectric used in the present invention is a material having a volume average particle diameter in the range of 0.5 to 3.0 μm. When the volume average particle diameter of the inorganic oxide ferroelectric substance is larger than 3.0 μm, the smoothness of the surface of the ferroelectric layer is deteriorated, so that the toner which is not originally adhered to the non-image area or the like is likely to adhere. When the toner adhered to the image area is transferred to paper or the like, the toner image quality deteriorates because the toner is not sufficiently transferred. When the volume average particle diameter of the inorganic oxide ferroelectric is smaller than 0.5 μm, the surface potential generated due to the change in the electric resistance of the ferroelectric layer and the pyroelectricity of the ferroelectric material is small. Therefore, a sufficient surface potential contrast cannot be obtained, and the quality of the toner image deteriorates.

The conductive support layer is not particularly limited as long as it has necessary mechanical strength and smoothness and has conductivity, and the material is not particularly limited. Metals such as platinum and aluminum,
Conductive inorganic materials such as conductive polymers and carbon black,
And the like, and a laminate obtained by laminating a conductive film on plastic, paper, or another insulating substrate may be used.

The ferroelectric element used in the image forming method of the present invention includes, for example, (A) a method of forming a ferroelectric layer on a conductive support layer, and (B) a ferroelectric layer and a conductive support. A method in which the body layers are separately manufactured and then bonded to each other.

As the method (A), a ferroelectric material, a resin and a solvent are mixed and dissolved, and the mixed solution is subjected to a dipping method, a bar coating method, a roll coating method, a spray coating method, a spin coating method, or the like. A method of forming a ferroelectric layer by removing a solvent after coating on a substrate, a method of forming a ferroelectric layer by forming a film by an electrodeposition method using the mixed solution used above, and the like. .

As the method (B), a ferroelectric material, a resin and a solvent are mixed and dissolved, and the mixed solution is subjected to dipping, bar coating, roll coating, spray coating, spin coating, or the like. After coating, a solvent is removed to form a film, a ferroelectric film is formed, and then a method is used in which the film is brought into close contact with a support layer using a conductive adhesive, and the like.

When a resin is used for forming the ferroelectric layer, examples of the resin material include polyvinyl butyral, polyester, polycarbonate, epoxy resin, and polymethyl methacrylate.

The solvent used for the mixed solution for forming the ferroelectric layer is a solvent which does not deteriorate the inorganic oxide ferroelectric substance and may be any solvent which can dissolve or disperse the resin material. Examples of suitable solvents include ketone solvents such as acetone and methyl ethyl ketone; chlorine solvents such as dichloromethane and 1,2-dichloroethane; and aromatic polar solvents such as toluene.

The thickness of the ferroelectric layer is such that a dipole is oriented by applying an electric field. If the thickness is too large, a high charging voltage is required, or charging tends to be required repeatedly. So it ’s not desirable,
On the other hand, if it is too thin, the difference between the surface potential of the image area and the surface potential of the non-image area becomes small, and the contrast of the visible image with the toner tends to decrease.
The range of m is preferred.

In the first step of the image forming method of the present invention, the method of arranging the ferroelectric dipoles in the ferroelectric layer in one direction (hereinafter referred to as dipole alignment treatment) is based on corona charging. A charging method used in electrophotography such as a method and a method using a roller electrode can be used.

The dipole alignment treatment by corona charging can be performed using a corona charger of a usual corotron type or scorotron type. In addition, the dipole orientation treatment by roller charging is performed by bringing a conductive rubber roller to which a high voltage is applied into contact with a dielectric layer, for example, with a resistance value of 10 ⁵ to 1.
0 ⁹ [Omega] cm approximately conductive method of charging by applying a few hundred volts or more voltage to the rubber roller, the resistance value 10 ³ to 10 ⁵ Omega
There is a method of attaching a fibrous wire rod having a thickness of cm to the surface of the conductive roller in a brush shape to enhance the contact property, and applying a high voltage to the conductive roller to charge the conductive roller. In both cases, a suitable method may be selected according to the system configuration of the apparatus.

The time required for dipole alignment is corona voltage,
It depends on the applied voltage of the roller electrode or its shape, and can be appropriately set according to the system configuration of the apparatus, the method of use of the apparatus, or the application.

In the second step of the image forming method of the present invention, the method of inverting the dipole of the portion corresponding to the image portion or the non-image portion is as follows. And a method of inverting a dipole corresponding to an image portion or a non-image portion using a stylus head, a method of inverting a dipole of an image portion or a non-image portion by ion flow, and the like. No.

When the volume resistivity of the ferroelectric substance is small, for example, 10 ¹⁰ Ωcm, the electric field of the corona is not sufficiently applied, and the orientation of the dipole and the inversion of the dipole in the image portion or the non-image portion are suppressed. However, since the writing is not performed sufficiently, the image writing tends to be unsatisfactory.

When the relative dielectric constant of the ferroelectric substance is large, for example, 1000 or more, since the capacitance is large, an electrostatic contrast sufficient for toner development can be obtained at a film thickness of about 100 μm. Because they tend not to be
The relative permittivity of the ferroelectric material is preferably small.

The capacitance of the ferroelectric layer can be reduced by increasing the film thickness. However, the increase in the corona electric field required for dipole orientation and the like, and the energy required for heating and cooling require less energy. It is not preferable to increase the film thickness, since it tends to increase remarkably.

In order to generate a surface potential difference between the written latent image portion and the non-image portion, the third method of forming an image of the present invention is performed.
In the process, the ferroelectric layer in which the dipole of the portion corresponding to the image portion or the non-image portion is inverted is heated to a temperature below the ferroelectric-paraelectric phase transition point of the dielectric, cooled, and cooled to form an electrostatic latent image. Develop image. It is essential that ferroelectrics have ferroelectricity at room temperature, and since the orientation of the dipoles of the ferroelectrics is resolved beyond the ferroelectric-paraelectric phase transition point, the stability of image information is reduced. Therefore, it is necessary to keep the heating temperature lower than the ferroelectric-paraelectric phase transition point.

When the ferroelectric layer is heated to a temperature below the ferroelectric-paraelectric phase transition point, the spontaneous polarization of the ferroelectric changes, and the bound surface charges become free charges. , Since the electric resistance of the ferroelectric layer becomes lower,
This free charge leaks.

By cooling from the heated state, the spontaneous polarization reversibly returns to its original size, but the leaked surface charge is irreversible, so that a potential is generated due to the spontaneous polarization. Therefore, the electric resistance of the ferroelectric layer needs to be reduced by increasing the temperature from room temperature.

It is suitable that the temperature of the ferroelectric layer be reduced immediately after the heating. In the case of a device in which a heating element such as a heat roll contacts the ferroelectric substance to heat the ferroelectric layer, the heating element is heated. The smaller the heat capacity, the better.

As a means for heating the ferroelectric, a method of irradiating light or the like and converting the energy into heat can be used. The method of irradiating light is particularly preferable in that the method is non-contact and the temperature is lowered immediately after heating.

Examples of the light source of the light irradiation device include an infrared lamp, a halogen lamp, a xenon lamp, a metal halide lamp, an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a laser and the like.

In the method of heating by irradiating light, the light irradiation time and irradiation intensity need to be at least a certain intensity, but the emission wavelength of the light source, the absorption wavelength of the light absorbing material,
Since the optimum value of the light intensity to be irradiated varies depending on conditions such as the heat capacity of the ferroelectric element, it is necessary to select appropriate conditions as appropriate. That is, an appropriate value may be selected for the intensity of the irradiated light depending on conditions such as the emission wavelength, the absorption wavelength of the light absorbing substance, and the heat capacity of the ferroelectric element.

It is effective to uniformly irradiate the ferroelectric layer temporally and planarly to uniformly heat the inside of the ferroelectric layer.

In the fourth step of the image forming method of the present invention,
After forming an electrostatic latent image, at a temperature showing ferroelectricity,
The latent image is developed into a visible image by developing using an electrostatic powder toner or a liquid toner.

As the electrostatic powder toner and the liquid toner, appropriate ones may be selected from commercial products.

The toner image developed on the surface of the ferroelectric layer is electrostatically transferred to the plain paper or film by charging the plain paper or the back surface of the film after laminating the plain paper or film. After that, fixing may be performed.

In order to continuously produce a plurality of identical images, if the surface of the ferroelectric layer has a surface potential contrast that allows electrostatic toner development, the electrostatic toner development, transfer, and fixing are successively performed. Just do it.

When the surface potential contrast or the like is reduced due to the influence of the transfer conditions or the surrounding environment, the surface potential contrast is formed by heating and cooling the ferroelectric layer, if necessary, and then the toner development is performed. Then, transfer and fixing may be performed.

[0043]

The present invention will be described in more detail with reference to the following examples. However, the invention is not limited to these examples. In the following examples, "%" represents "% by weight", and each of the evaluation characteristics means the following symbols and contents.

Vr: pyroelectric potential; surface potential generated by the change in resistance of the ferroelectric layer and the pyroelectricity of the ferroelectric at a unit thickness of the ferroelectric layer. (V / μm) (However, the measurement temperature is room temperature and the heating temperature is 150 ° C.)

Example 1 Strontium carbonate (SrC)
After sufficiently mixing 1 g of O ₃ ), 1.35 g of titanium oxide (TiO ₂ ) and 3.16 g of bismuth trioxide (Bi ₂ O ₃ ), the mixture was sintered at 810 ° C. for 1 hour using an electric furnace. The mixture after sintering was pulverized using a mortar to obtain powdery Sr ₂ Bi ₄ Ti ₅ O ₁₈ .

The thus obtained Sr ₂ Bi ₄ Ti ₅ O ₁₈
Powder 2.5%, polyvinyl butyral (“BH-3” manufactured by Sekisui Chemical Co., Ltd.) 2.5% and methyl ethyl ketone 4
A mixture consisting of 7.5% and a zirconia ball having a diameter of 2 mm, which is 2.5 times the weight of the mixture, are charged, and a planetary-type fine-milling machine “PULVERISETTE 7” (manufactured by FRITSCH) is used. , Set the speed to 5, 1
Time-dispersed and mixed.

The volume average particle size of the ferroelectric substance in the dispersion mixture thus obtained was measured by using a light scattering type particle size distribution analyzer “SA”.
It was about 0.85 μm as a result of measurement using “LD2000” (manufactured by Shimadzu Corporation).

The dispersion mixture thus obtained was applied on an alumite-treated aluminum substrate using a bar coater so that the film thickness after drying was 50 μm. By heating and drying for a period of time to form a ferroelectric layer, a ferroelectric element was obtained.

The ferroelectric element has a pulse width of 0.1
The alignment treatment was performed by applying a negative corona pulse having a voltage of 6 kV 50 times per second. The ferroelectric element was heated to 150 ° C. using a heater, cooled, and the surface of the ferroelectric element was measured using a surface electrometer CATE717 (manufactured by Gentec). As a result, Vr = 0.95. (V /
μm).

Through an arbitrary mask, a pulse width of 0.2
By applying a positive corona pulse having a voltage of 6 kV for 100 times per second, the polarization was inverted only in the portion corresponding to the image portion.

Next, the ferroelectric element was heated to 150 ° C. using a heater, and then cooled to form an electrostatic latent image. When the electrostatic latent image was visualized on the ferroelectric element treated in this manner using a powder toner having a positive polarity, the toner adhered to the portion where the polarization was inverted. This toner image was transferred to plain paper and fixed to obtain a first arbitrary image.

Further, after the visible image is transferred to plain paper, the ferroelectric element is heated and cooled, and development, transfer and fixing are repeated in the same manner as in the first sheet, whereby a plurality of arbitrary sheets can be obtained. Image was obtained.

After storing the ferroelectric element in a bright room for one month, the ferroelectric element was heated to 150 ° C. using a heater and then cooled to form an electrostatic latent image. When the electrostatic latent image was visualized on the thus treated ferroelectric element using the powder toner of the positive electrode, the toner adhered only to the portion where the polarization was inverted. This toner image was transferred to plain paper and fixed to obtain a similar image.

After the visible image is transferred to plain paper, the ferroelectric element is heated, then cooled, and development, transfer, and fixing are repeated in the same manner as in the first sheet to obtain a plurality of arbitrary images. I got

Further, the ferroelectric element was subjected to an alignment treatment by applying a negative corona pulse having a pulse width of 0.1 second and a voltage of 6 kV 50 times. By applying a positive corona pulse having a pulse width of 0.2 seconds and a voltage of 6 kV 100 times through an arbitrary mask, the polarization was inverted only in the portion corresponding to the image area. Next, the ferroelectric element was heated to 150 ° C. using a heater, and then cooled,
An electrostatic latent image was formed. When the electrostatic latent image was visualized on the ferroelectric element treated in this manner using a powder toner of positive polarity, the toner adhered only to the portion where the polarization was inverted. This toner image was transferred to plain paper and fixed to obtain a first arbitrary image.

Further, the ferroelectric element after the visible image has been transferred to plain paper is heated and cooled, and development, transfer and fixing are repeatedly performed in the same manner as in the first sheet, whereby a plurality of arbitrary sheets can be formed. Image was obtained.

(Example 2) Sr ₂ Bi ₄ Ti ₅ O ₁₈ was prepared in the same manner as in Example 1 except that the speed of the planetary type fine particle grinder was set to 10 and dispersed and mixed for 3 hours.
A dispersion mixture consisting of 50% of powder, 2.5% of polyvinyl butyral and 47.5% of methyl ethyl ketone was obtained.

The volume average particle diameter of the ferroelectric substance in the dispersion mixture thus obtained was measured in the same manner as in Example 1, and as a result, it was about 0.58 μm.

A ferroelectric device was obtained in the same manner as in Example 1, except that the thus obtained dispersion mixture was used.

The pulse width of the ferroelectric element is 0.1
The alignment treatment was performed by applying a negative corona pulse having a voltage of 6 kV 50 times per second. The ferroelectric element was heated to 150 ° C. using a heater, cooled, and the surface of the ferroelectric element was measured using a surface electrometer CATE717 (manufactured by Gentec). As a result, Vr = 0.68. (V /
μm).

Using this ferroelectric element, orientation processing, writing of a latent image, formation of an electrostatic latent image, development, transfer and fixing are performed in the same manner as in Example 1, and the first arbitrary image is formed. I got

Further, the ferroelectric element after the transfer of the visible image to plain paper is heated and then cooled, similarly to the first sheet.
Developing, transferring and fixing were repeated to obtain a plurality of arbitrary images.

After storing this ferroelectric element in a light room for one month, it was heated and cooled to 150 ° C. to form an electrostatic latent image in the same manner as in Example 1. When the electrostatic latent image was visualized using the toner, the toner adhered only to the portion where the polarization was inverted. This toner image was transferred to plain paper and fixed to obtain a similar image.

After the visible image is transferred to plain paper, the ferroelectric element is heated, then cooled, and development, transfer, and fixing are repeated in the same manner as in the first sheet to obtain a plurality of arbitrary images. I got

Further, in the same manner as in Example 1, an orientation process, polarization reversal of an image portion, heating and cooling were performed on this ferroelectric element to form an electrostatic latent image, and the electrostatic latent image was visualized. Then, the toner image was transferred to plain paper and fixed to obtain a first arbitrary image.

Further, after the visible image is transferred to plain paper, the ferroelectric element is heated, then cooled, and development, transfer and fixing are repeatedly performed in the same manner as in the first sheet, whereby a plurality of arbitrary sheets can be obtained. Image was obtained.

Example 3 Sr ₂ Bi ₄ Ti ₅ O ₁₈ was prepared in the same manner as in Example 1, except that the speed of the planetary fine pulverizer was set to 2 and dispersed and mixed for 5 minutes. A dispersion mixture consisting of 50% of powder, 2.5% of polyvinyl butyral and 47.5% of methyl ethyl ketone was obtained.

The volume average particle diameter of the ferroelectric substance in the dispersion mixture thus obtained was measured in the same manner as in Example 1. As a result, it was about 2.65 μm.

A ferroelectric device was obtained in the same manner as in Example 1, except that the thus obtained dispersion mixture was used.

This ferroelectric element has a pulse width of 0.1
The alignment treatment was performed by applying a negative corona pulse having a voltage of 6 kV 50 times per second. This ferroelectric element was heated to 150 ° C. using a heater, cooled, and the surface of the ferroelectric element was measured using a surface electrometer CATE717 (manufactured by Gentec). As a result, Vr = 1.31. (V /
μm).

Using this ferroelectric element, orientation processing, writing of a latent image, formation of an electrostatic latent image, development, transfer, and fixing are performed in the same manner as in Example 1, and the first arbitrary image is formed. I got

Further, the ferroelectric element after the transfer of the visible image to plain paper is heated and cooled, and the same as in the first sheet,
Developing, transferring and fixing were repeated to obtain a plurality of arbitrary images.

After storing this ferroelectric device in a light room for one month, it was heated and cooled to 150 ° C. in the same manner as in Example 1 to form an electrostatic latent image, When the electrostatic latent image was visualized using the toner, the toner adhered only to the portion where the polarization was inverted. This toner image was transferred to plain paper and fixed to obtain a similar image.

After the visible image has been transferred to plain paper, the ferroelectric element is heated, cooled, and repeatedly subjected to development, transfer and fixing in the same manner as in the first sheet, thereby forming a plurality of arbitrary images. I got

Further, in the same manner as in Example 1, the ferroelectric element was subjected to orientation treatment, polarization reversal of the image portion, heating and cooling to form an electrostatic latent image, and the electrostatic latent image was visualized. Then, the toner image was transferred to plain paper and fixed to obtain a first arbitrary image.

Further, the ferroelectric element after the visible image has been transferred to the plain paper is heated and cooled, and the development, transfer and fixing are repeated in the same manner as in the first sheet, whereby a plurality of arbitrary sheets can be obtained. Image was obtained.

Example 4 In Example 1, 2.5% of polyvinyl butyral and 47.5 of methyl ethyl ketone were used.
%, Acetone 50% was used, the speed of the planetary type fine mill was set to 5, and the mixture was dispersed and mixed for 1 hour.
Powder 5 of Sr ₂ Bi ₄ Ti ₅ O _{18 was} prepared in the same manner as in Example 1.
A dispersion mixture consisting of 0% and 50% acetone was obtained.

The volume average particle size of the ferroelectric substance in the dispersion mixture thus obtained was measured in the same manner as in Example 1, and as a result, it was about 0.83 μm.

The solvent acetone is removed by heating,
A powdery Sr ₂ Bi ₄ Ti ₅ O ₁₈ was obtained. A mixture composed of 5% of the powder of Sr ₂ Bi ₄ Ti ₅ O ₁₈ thus obtained, 3% of polyvinyl butyral (“BH-3” manufactured by Sekisui Chemical Co., Ltd.) and 92% of acetone was dispersed using an ultrasonic homogenizer. Mixed.

After two stainless steel (SUS-304) substrates were inserted in parallel in the dispersion mixture at an interval of 1 cm, a DC current of 300 V was applied between the two substrates.
Upon application for 2 seconds, powder precipitated on the negative electrode side. This was pulled up from the solution to obtain a ferroelectric element having a ferroelectric layer in which a ferroelectric powder was dispersed in a polyvinyl butyral film.

This ferroelectric element has a pulse width of 0.1
The alignment treatment was performed by applying a negative corona pulse having a voltage of 6 kV 50 times per second. This ferroelectric element was heated to 150 ° C. using a heater, then cooled, and the surface of the ferroelectric element was measured using a surface electrometer CATE717 (manufactured by Gentec). As a result, Vr = 0.89. (V /
μm).

Using this ferroelectric element, orientation processing, writing of a latent image, formation of an electrostatic latent image, development, transfer and fixing are performed in the same manner as in Embodiment 1, and the first arbitrary image is formed. I got

Further, the ferroelectric element after the visible image was transferred to plain paper was heated and then cooled, and the same as in the first sheet,
Developing, transferring and fixing were repeated to obtain a plurality of arbitrary images.

After storing this ferroelectric element in a light room for one month, it was heated and cooled to 150 ° C. to form an electrostatic latent image in the same manner as in Example 1. When the electrostatic latent image was visualized using the toner, the toner adhered only to the portion where the polarization was inverted. This toner image was transferred to plain paper and fixed to obtain a similar image.

The ferroelectric element after the visible image is transferred to plain paper is heated, cooled, and repeatedly subjected to development, transfer, and fixing in the same manner as the first sheet to obtain a plurality of arbitrary images. I got

Further, in the same manner as in Example 1, an orientation process, polarization reversal of the image portion, heating and cooling were performed on this ferroelectric element to form an electrostatic latent image, and the electrostatic latent image was visualized. Then, the toner image was transferred to plain paper and fixed to obtain a first arbitrary image.

Further, the ferroelectric element after the visible image has been transferred to the plain paper is heated and cooled, and development, transfer and fixing are repeatedly performed in the same manner as in the first sheet, whereby a plurality of arbitrary sheets can be obtained. Image was obtained.

(Comparative Example 1) Sr ₂ Bi ₄ Ti ₅ O was prepared in the same manner as in Example 1 except that the speed of the planetary mill was set to 10 and dispersed and mixed for 20 hours.
_A dispersion mixture consisting of 50% of a powder of ₁₈ , 2.5% of polyvinyl butyral and 47.5% of methyl ethyl ketone was obtained.

The volume average particle diameter of the ferroelectric substance in the dispersion mixture thus obtained was measured in the same manner as in Example 1. As a result, it was about 0.42 μm.

A ferroelectric element was obtained in the same manner as in Example 1 except that the thus obtained dispersion mixture was used.

The pulse width of the ferroelectric element is 0.1
The alignment treatment was performed by applying a negative corona pulse having a voltage of 6 kV 50 times per second. The ferroelectric element was heated to 150 ° C. using a heater, cooled, and the surface of the ferroelectric element was measured using a surface potentiometer CATE717 (manufactured by Gentec). As a result, Vr = 0.45. (V /
μm). It is clear that the ferroelectric of Comparative Example 1 has a lower pyroelectric potential Vr and lower surface potential contrast between the image area and the non-image area than the ferroelectric substance of the example.

Comparative Example 2 A powder 50 of Sr ₂ Bi ₄ Ti ₅ O _{18 was} prepared in the same manner as in Example 1 except that a homogenizer was used in place of the planetary fine pulverizer.
%, 2.5% polyvinyl butyral and 47.5% methyl ethyl ketone.

The volume average particle diameter of the ferroelectric substance in the dispersion mixture thus obtained was measured in the same manner as in Example 1. As a result, it was about 3.56 μm.

A ferroelectric device was obtained in the same manner as in Example 1, except that the thus obtained dispersion mixture was used.

The resulting dispersion mixture was applied to an alumite-treated aluminum substrate and dried to a thickness of 50 μm.
After applying using a bar coater, 60
By heating and drying at a temperature of 3 ° C. for 3 hours to form a ferroelectric layer, a ferroelectric element was obtained.

The pulse width of the ferroelectric element is 0.1
The alignment treatment was performed by applying a negative corona pulse having a voltage of 6 kV 50 times per second. The ferroelectric element was heated to 150 ° C. using a heater, cooled, and the surface of the ferroelectric element was measured using a surface electrometer CATE717 (manufactured by Gentec). As a result, Vr = 1.38. (V /
μm).

Through an arbitrary mask, a pulse width of 0.2
By applying a positive corona pulse having a voltage of 6 kV for 100 times per second, the polarization was inverted only in the portion corresponding to the image portion.

Next, the ferroelectric element was heated to 150 ° C. using a heater, and then cooled to form an electrostatic latent image. When the electrostatic latent image was visualized on the ferroelectric element treated in this manner using a powder toner having a positive polarity, the toner adhered not only to the portion where the polarization was inverted but also to the portion where the polarization was not inverted. .

This toner image was transferred to plain paper and fixed to obtain a first arbitrary image. The obtained image has a larger amount of toner adhered to the non-image portion as compared with Example 1,
Image quality has decreased. Also, more toner remained on the surface of the ferroelectric layer after transfer than in the examples.

[0100]

According to the image forming method using the ferroelectric element of the present invention, the latent image can be stably stored in a bright room for a long period, and the image can be written and erased as needed.

Further, according to the image forming method using the ferroelectric element of the present invention, the contrast of the surface potential at the time of toner development is a difference between potentials having different polarities. It is possible to form a sheet toner image.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a ferroelectric element of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ferroelectric layer 2 Ferroelectric 3 Resin 4 Support layer

Claims (3)

[Claims] (1) A ferroelectric element having a ferroelectric layer containing a ferroelectric substance on a conductive support, in which ferroelectric dipoles in the ferroelectric layer are arranged in one direction. One step, (2) a second step of inverting a dipole in a portion corresponding to an image portion or a non-image portion, and (3) heating the ferroelectric layer uniformly below the Curie point, cooling it, and electrostatically cooling the ferroelectric layer. An image forming method comprising: a third step of developing a latent image; and (4) a fourth step of developing the electrostatic latent image using toner, wherein the ferroelectric substance is an inorganic oxide ferroelectric substance, And an image forming method wherein the volume average particle size is in the range of 0.5 to 3.0 μm. 2. The image forming method according to claim 1, wherein the ferroelectric layer is an inorganic ferroelectric resin dispersion layer. 3. The image forming method according to claim 1, wherein the ferroelectric layer is a layer deposited on a substrate by electrodeposition from a mixed solution containing an inorganic ferroelectric and a resin solution.