JPH0352055B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to electrostatic recording media, and more particularly to electrostatic recording media that can be used multiple times. Conventionally, electrostatic recording paper, in which a conductive layer is provided between the recording layer and the base paper, has been generally used as a recording medium in electrostatic recording devices. A latent image is formed, developed with toner, and fixed to obtain a recorded image. However, when using such electrostatic recording paper,
Not only does it have disadvantages such as the unavoidable adhesion of excess toner to the surface of the recording paper, and it is highly susceptible to the atmosphere during use (moisture, heat, etc.), but the electrostatic recording paper itself is different from plain paper. Since they are special in comparison, they have the disadvantage that running costs are significantly higher when used as consumables. In order to solve these drawbacks, electrostatic recording devices that transfer data onto plain paper have been developed (for example, Japanese Patent Publication No. 46-34077).
Publication No.). According to this method, a recording medium is formed in the form of a belt, in which a dielectric layer having a volume resistivity of 10 ¹² Ω·cm or more is provided on a biaxially stretched polyester base material, and a needle electrode is connected to the recording medium using a multi-stylus. The dielectric surface is charged by applying a high voltage between the surface and the dielectric surface, and the electrostatic latent image formed is then developed with toner to obtain a powder image, which is then printed on plain paper. Images are obtained by electrostatic transfer. However, with this method, the toner image is electrostatically transferred to plain paper, so the transfer efficiency is low.
It is low at around 80%, which is disadvantageous in terms of a decrease in image density, cleaning and scattering of residual toner, and image disturbance due to electrostatic transfer. On the other hand, a dielectric thin layer is provided on the surface of a conductive rigid cylinder, an electrostatic latent image is formed on the surface of this dielectric thin layer, and after this latent image is developed with toner, it is transferred and fixed onto plain paper using pressure. The method is known (for example, JP-A-54-78134, JP-A-55-
134872). In this method, the dielectric thin layer is rubbed by the paper, resulting in its surface being polished. Therefore, in order to increase the hardness of the dielectric layer, inorganic dielectrics such as anodized aluminum, thermally sprayed Al ₂ O ₃ and glass enamel, and organic dielectrics such as polyamide and polyimide are used. However, inorganic dielectric layers such as anodized aluminum, sprayed Al ₂ O ₃ , and glass enamel suffer from a significant decrease in surface resistance due to adhesion of moisture in the atmosphere, making it impossible to always obtain stable and good images. On the other hand, it can be said that the electrical properties of an organic dielectric recording layer made of polyimide, polyamide, fluororesin, etc. are relatively less susceptible to environmental dependence on temperature and humidity. However, organic recording layers have insufficient abrasion resistance, so when applied to transfer-type electrostatic recording devices, sufficient durability cannot be obtained due to problems such as surface cutting and scratches caused by cleaners. It is. Particularly when performing the above-mentioned pressure transfer and simultaneous fixing step, scratch marks with the transfer paper are also taken into consideration, making it even more difficult to use the organic recording layer. Moreover, these organic recording layers are subject to oxidation by ozone or the like under high electric fields during long-term use, and their humidity characteristics eventually deteriorate. Generally, polyimide-based and polyamide-based resins have relatively high hardness, but are weak against impact and are prone to crack-like scratches, which cause cutting.
Furthermore, in the pressure transfer method, the transfer efficiency tends to be low at 80% or less because the surface energy is large. Although fluorine-based resins have sufficient transfer efficiency, they tend to be prone to scratches due to their softness. Additionally, the highly insulating resin that has been commonly used for dielectric layers is oxidized by ozone generated from ion generators used to form electrostatic latent images.
As a result, polar groups are introduced onto the surface, which poses a problem in that after repeated use, it becomes impossible to form an electrostatic latent image in accordance with electrical signals. The object of the present invention is to provide an electrostatic recording medium, particularly a recording medium that can be used multiple times and is used in an electrostatic recording device that uses pressure to transfer and fix a toner image on the surface of a dielectric layer of the recording medium onto plain paper. It has no adverse effects on images even in high humidity atmospheres, has high developer transfer efficiency, and has good abrasion resistance with no adhesion of organic components in the developer during long-term continuous use. An object of the present invention is to provide a recording medium for electrostatic recording that can perform image quality recording. That is, the present inventors have conducted repeated research in view of the above points, and have found that when forming the dielectric layer constituting the above-mentioned recording medium, a fluorine-containing block copolymer is contained in the film-forming resin. By (1) increasing water repellency on the surface of the dielectric layer without reducing the hardness of the dielectric layer;
By improving the releasability, non-adhesiveness, and slipperiness as well as the adhesion of the dielectric layer to the conductive substrate, the transfer efficiency of the developer is high, and the organic components in the developer are difficult to adhere to and are resistant. (2) The ozone generated during operation of the ion generator used to form the electrostatic latent image prevents oxidation of the dielectric layer surface, resulting in a dielectric layer with good wear characteristics. We have discovered that it is possible to prevent deterioration of electrical characteristics, and (3) to suppress fluctuations in image quality due to environmental changes such as humidity. That is, the present invention provides an electrostatic recording medium that is used in a transfer method and has a dielectric layer and a conductive substrate, in which the dielectric layer contains a film-forming resin, a functional segment having surface migration properties, and a film-forming resin. The present invention is an electrostatic recording medium characterized by containing a fluorine-containing block copolymer having a compatible segment that is compatible with a resin. In a preferred embodiment of the present invention, the dielectric layer has a pencil hardness characteristic of H (measured according to the Japanese Industrial Standard JIS K-8400 "Pencil Scratch Test Method") or more and a volume of 10 ¹³ Ω·cm or more after film formation. Examples include those containing a film-forming resin having resistivity and a fluorine-containing block copolymer. At this time, the fluorine-containing block copolymer is contained in the dielectric layer in an amount of 0.5 to 30% by weight, preferably 1 to 10% by weight. If the amount of the fluorine-containing block copolymer added is less than 0.1% by weight, water repellent and mold release effects cannot be obtained, and if it is more than 50% by weight, the impact resistance of the coating film will decrease, which is not preferable. The fluorine-containing block copolymer used in the present invention is
It has a functional segment that has surface migration properties and a compatible segment that is compatible with the above-mentioned film-forming resin. Specifically, it is an A-B type block copolymer obtained by block polymerizing a fluorine-containing monomer component (for example, the fluorine-containing alkyl group described below) that acts as a functional segment on one end of a polymer that acts as a compatible segment. be. The fluorine-containing monomer component that acts as a functional segment is -CH ₂
(CF ₂ ) ₂ H, −CH ₂ (CF ₂ ) ₄ H, −CH ₂ CF ₃ , −CH ₂ CH ₂
Fluoroalkyl groups such as ( _{CF2 ) 7CF3 , -CF3} , _C2F6 are preferred. In addition, the polymer that acts as a compatible segment is preferably one containing a vinyl monomer component, and specifically, polyalkyl methacrylate such as polymethyl methacrylate, polybutyl methacrylate, polymethyl acrylate, polyethyl acrylate, etc. Polyalkyl acrylates are suitable. A-B containing this fluoroalkyl group as one component
The compatible segments of the type fluorine-containing block copolymer are compatible with the film-forming resin, making it possible to improve the adhesion of the coating film to the substrate and the hardness, and also act as functional segments. The fluoroalkyl group migrates to the surface and can improve the water repellency, mold releasability, non-adhesiveness, and slipperiness of the coating surface. These points cannot be obtained when random polymers of the same composition are used, as will be made clear in the comparison below. These fluorine-containing block copolymers can be synthesized using polymex peroxide as a polymerization initiator [Proceedings of the 33rd Annual Conference of the Society of Polymer Science and Technology, Vol.
266 pages (Vol. 33, No. 2, 1984)]. Furthermore, as the fluorine-containing block copolymer, Moviper F100, F110, F200, and F210 manufactured by NOF Corporation can be used. The present invention will be explained below with reference to the drawings. FIG. 1 shows a dielectric drum 1 serving as a recording medium in which a dielectric layer 2 is provided as a recording layer on a conductive substrate 3. Here, the shape of the recording medium is not limited to the drum shape as shown in FIG. 1, but may be belt-shaped or flat plate-shaped. The conductive substrate 3 is selected from aluminum, aluminum alloy, stainless steel, and other metals, and preferably has a thickness that is not deformed by pressure during pressure transfer or pressure transfer and simultaneous fixing. In addition, in order to harden the surface of the conductive substrate or increase the surface area of the conductive substrate and improve the adhesion of the coated dielectric layer, for example, anodizing the aluminum alloy surface or hard chrome plating the stainless steel surface. You may also do this. Next, the dielectric layer 2 is made of 100 parts by weight of a film-forming resin having a pencil hardness of H or higher and a volume resistivity of 10 ¹³ Ω·cm or higher after film formation, and 0.1 to 0.1 to 0.1 to fluorine-containing block copolymer.
A mixture consisting of 50 parts by weight, preferably 1 to 10 parts by weight, is formed on a conductive substrate directly or via another dielectric layer. Here, it is appropriate for the film-forming resin to have a pencil hardness of H or more, preferably 3H or more, from the viewpoint of improving wear resistance, and a volume resistivity of 10 ¹³ Ω・cm or more, preferably A value of 10 ¹⁵ Ω·cm or more is appropriate from the viewpoint of obtaining good images. The film-forming resin used is specifically, for example, polyimide, polyamideimide, polyamide, polyesterimide, polyester, polyvinyl formal, epoxy resin, polyurethane, melamine resin, acrylic resin, polyacrylamide, silicone resin, imide epoxy resin, Examples include urethane acrylate resin and epoxy acrylate resin. Next, a preferred embodiment of the recording medium 1 will be described. In the case of a drum-shaped recording medium, a cylinder is made of a conductive substrate such as aluminum, aluminum alloy, stainless steel, or the like. The wall thickness of the cylinder at this time needs to be thick enough to withstand pressure during pressure transfer or pressure transfer simultaneous fixing. In the case of aluminum and aluminum alloys, it is desirable to have a thickness of 10 mm or more. Next, a paint made of the film-forming resin used in the present invention, a fluorine-containing block copolymer, and, if necessary, a solvent, a curing agent, etc., is applied to the cylinder surface directly or via another dielectric layer. Dry and form a film. The film thickness at this time must be at least 3 μm to maintain electrical insulation, and preferably 10 μm.
That's all. Next, the dielectric drum prepared as described above is incorporated into an electrostatic recording apparatus shown in FIG. 2 as a recording medium. The configuration of the electrostatic recording device shown in FIG. 2 will be briefly described as follows.
The electrostatic latent image is formed using the recording head 4,
As a method, the multi-stylus disclosed in Japanese Patent Publication No. 36-4119, or the method disclosed in Japanese Patent Application Publication No. 53-96834,
Any of the ion implantation type disclosed in Japanese Patent Publication No. 54-53537 can be used, and basically any type that can form an electrostatic latent image on the surface of the dielectric 2 in a dot shape may be used. Preferably, a type that does not involve direct discharge between the dielectric 2 and the recording head 4, such as the latter ion implantation type, is used. Next, the electrostatic latent image formed by the above method is visualized in the developing section 5 and then transferred onto plain paper 9 by pressure by the pressure roller 7. At this time, if a pressure fixable toner is used, the visible image is transferred to plain paper and fixed at the same time. Next, in accordance with a conventional method, the recording medium after the visible image has been transferred is neutralized by the static eliminator unit 8, and the residual toner remaining after the transfer is removed by the cleaner unit 6. Further, as the conditions for simultaneous pressure transfer and fixing, it is preferable to use a pressure of 20 kg/cm ² or more for compressing and fixing the toner. Also, the toner used is
In addition to capsule toner, polyethylene, ethylene-
An externally added toner in which carbon and a magnetic material are externally added to resin particles such as vinyl acetate copolymer or polyamide, or an internally added toner in which a magnetic material is internally added to resin particles such as polyethylene can be used. In addition, a charge control agent and an abrasive can be added to the externally added toner or the internally added toner. In addition, in order to record an electrostatic image according to an image signal on the electrostatic image holding cylinder 1 in the electrostatic recording 4, Japanese Patent Application Laid-Open No. 54
The electrostatic recording head (ion generator) disclosed in Japanese Patent No. 78134 can be used. The electrostatic recording head 4 includes a dielectric 3 as shown in FIG.
5, drive electrode 36, control electrode 37,
It consists of a screen electrode 39 with ion emitting apertures 38. An AC voltage is applied between the drive electrode 36 and the control electrode 37 by the power supply 34, and a switch 3 is applied between the control electrode 37 and the conductive substrate 3 of the electrostatic image holding cylinder 1.
A DC voltage is applied from a power source 31 through the screen electrode 39 and the conductive substrate 3, and a DC voltage is applied from a power source 32 between the screen electrode 39 and the conductive substrate 3. The AC voltage applied between the drive power supply 36 and the control electrode 37 generates positive and negative ions alternately. The switch 33 is turned on by the image signal (contact Y
If the electrostatic image holding cylinder 1 is electrically conductive), the negative ions are accelerated and reach the dielectric layer 2 of the electrostatic image holding cylinder 1, where they are held. At this time, since positive ions are not accelerated, they are discharged between them and the control electrode 37. There is no image signal and switch 33 is off (conducting to contact X)
If so, the positive and negative ions will not be accelerated and will be discharged between them and the control electrode 37. In this way, an electrostatic latent image can be recorded according to the image signal. Further, as a method for forming an electrostatic latent image, an electrostatic latent image is formed by transferring an electrostatic latent image formed on the surface of an electrophotographic photoreceptor having a photoconductive layer to the above-mentioned dielectric layer. A method can also be used. Hereinafter, the present invention will be explained according to examples. still,
Pencil hardness measurements in the following Examples and Comparative Examples were conducted in accordance with Japanese Industrial Standards JIS K-8400 "Pencil Scratch Test Method." Example 1 Cyclobutadiene rubber paint JSR CBR-M (trademark of Japan Synthetic Rubber Co., Ltd., containing 80% xylene by weight) was applied to the outer peripheral surface of an aluminum alloy cylinder with an inner diameter of 60 mm, an outer diameter of 100 mm, and a length of 230 mm, and then heated at 180°C. at 60
The cylinder was heated and dried for 30 minutes to obtain a cylinder coated with a film thickness of 3 μm. To this cylinder, 8 g of a 25% MEK solution of benzophenone and 4 g of triethanolamine as a reaction accelerator were added to 100 g of UV-curable epoxy acrylate paint Unidek V-5502 (trademark of Dainippon Ink & Chemicals Co., Ltd., resin content 100%). , Deiper, which is an A-B type block polymer containing a fluoroalkyl group as one component, is added to the mixed paint.
Apply 5g of F200 (trademark of Nippon Oil & Fats Co., Ltd.) mixture, dry at 80℃ for 10 minutes, and then irradiate with a 4KW concentrating ultraviolet lamp at a distance of 15cm for 1 minute, resulting in a coating thickness of 20μ.
A cylinder was obtained in which a coating film having a thickness of 23 μm was formed together with the cyclized butadiene rubber layer. Pencil hardness is 5H, volume resistivity is 5.1×10 ¹⁵ Ω・
It was cm. This cylinder was used to incorporate it into the electrostatic recording device shown in Figure 2, and an ion implantation recording head was used at 25°C, 60% humidity, and 35°C, 90% humidity.
% environment. The results are shown in Table 1. Comparative Example 1 A cylinder was prepared and imaged in exactly the same manner as in Example 1, except that Modeiper F200 (same as above) used in the paint for cylinder surface application in Example 1 was removed. The results are shown in Table 1. The pencil hardness of the coating film was H, and the volume resistivity was 4.7×10 ¹⁵ Ω·cm. Example 2 A-B type block polymer Modiaper F100 (trademark of NOF Corporation) containing 100 g of acrylic paint Duuraclone SE-5377 (trademark of Mitsubishi Rayon Co., Ltd., resin content 50%) and a chloroalkyl group as one component ) 1.0g of the mixture was applied onto the same cylinder as in Example 1 and dried by heating at 150°C for 1 hour to determine the coating film thickness.
A cylinder formed with a film of 15 μm was obtained. Image printing was performed using the cylinder mentioned above. Table 1 shows the results.
It is written in Pencil hardness is 5H, volume resistivity is 7×
It was 10 ¹⁵ Ω・cm. Comparative Example 2 A cylinder was prepared and imaged in exactly the same manner as in Example 2, except that the Modeliper F100 (same as above) used in the paint for cylinder surface application in Example 2 was omitted. The results are shown in Table 1. The pencil hardness of the coating film was 2H, and the volume resistivity was 6.2×10 ¹⁵ Ω·cm. Comparative Example 3 A cylinder with a coating thickness of 14 μm was obtained in exactly the same manner as in Example 2, except that the Duracron SE-5377 (same as above) used in the paint for cylinder surface application in Example 2 was removed, and a cylinder with a coating thickness of 14 μm was obtained in the same manner as in Example 2. I used this method to create an image. The results are shown in Table 1. The pencil hardness of the coating film was 2H, and the volume resistivity was 1.1×10 ¹⁴ Ω·cm. Comparative Example 4 Instead of Modeiper F200 used in Example 1,
A dielectric layer was formed to form a recording medium in exactly the same manner except that the same amount of polytetrafluoroethylene powder was used, and then an image was formed. The results are shown in Table 1. The pencil hardness of the coating film was 5H, and the volume resistivity was 4.8×10 ¹⁵ Ω·cm. Comparative Example 5 Instead of Modeiper F100 used in Example 2,
A dielectric layer was formed to form a recording medium in exactly the same manner except that the same amount of polytetrafluoroethylene powder was used, and then an image was formed. The results are shown in Table 1. The pencil hardness of the coating film was 7H, and the volume resistivity was 6.4×10 ¹⁵ Ω·cm.

[Table] As explained above, by using a dielectric layer containing an A-B type block polymer containing a fluoroalkyl group as a recording medium in a pressure transfer type electrostatic recording device, (1) pressure can be reduced. The transfer efficiency of the developer was increased due to simultaneous transfer and fixing. (2) The adhesion of organic polymers to the recording medium is reduced and there is no humidity dependence, making it possible to improve the quality of images over a long period of time. (3) The abrasion resistance of recording media has improved, making it possible to use them for long periods of time. (4) Durability deterioration due to ozone oxidation could be prevented. (5) Changes in characteristics due to humidity could be prevented.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of the electrostatic recording medium of the present invention. FIG. 2 is a sectional view of an electrostatic recording device using the electrostatic recording medium of the present invention. FIG. 3 is a cross-sectional view schematically showing an electrostatic latent image forming section in an electrostatic recording device using the electrostatic recording medium of the present invention. 1; dielectric drum, 2; dielectric layer, 3; conductive substrate, 4; recording head, 5; developing device, 6; cleaner, 7; pressure roller, 8; static eliminator, 9; transfer paper, 31, 32, 34; power supply, 33; switch,
35; dielectric, 36; drive electrode, 37; control electrode, 38; ion release aperture,
39; Screen electrode.

Claims (1)

[Scope of Claims] 1. In an electrostatic recording medium having a dielectric layer and a conductive substrate used in a transfer method, the dielectric layer comprises a film-forming resin, a functional segment having surface migration properties, and a film-forming resin. 1. An electrostatic recording medium comprising a fluorine-containing block copolymer having a compatible segment that is compatible with a resin for use in the electrostatic recording medium. 2. The electrostatic recording medium according to claim 1, wherein the content of the fluorine-containing block copolymer is 0.1 to 50 parts by weight based on 100 parts by weight of the film-forming resin. 3. The electrostatic recording medium according to claim 1 or 2, wherein the film-forming resin has a pencil hardness of H or higher and a volume resistivity of 10 ¹³ Ω·cm or higher after film formation. 4. The electrostatic recording medium according to claim 1, wherein the fluorine-containing block copolymer is a block copolymer in which a fluorine-containing alkyl group is block-polymerized as a fluorine-containing monomer component at one end of the polymer. . 5. The electrostatic recording medium according to claim 4, wherein the fluorine-containing block copolymer has a vinyl monomer component. 6. The electrostatic recording medium according to claim 4 or 5, wherein the fluorine-containing block copolymer contains polyalkyl acrylate or polyalkyl methacrylate.