JPH0766193B2 - Electrostatic recording body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrostatic recording material, and more particularly to an electrostatic recording material that can obtain clear recording without streak stains or background stains.

(Prior Art) Conventionally, as a high-speed recording method, an electrostatic recording method has been favorably used for facsimiles, printers, etc., but in recent years, an electrostatic printer has been used as an output of a CAD system for designing and drawing using a computer in recent years. -An electrostatic plotter is used. 200 for traditional text-based records
Although about dots / inch was sufficient, for drawing output of such CAD system, high resolution recording of about 400 dots / inch and less stains are required. Many of the drawings output from CAD systems are wide, and the liquid development method is the mainstream for uniform development. In the case of the liquid developing method, the toner particles are finer than those of the powder developing method, and therefore, the electrostatic latent image is likely to appear as a stain on the electrostatic recording medium in addition to the latent image for a recording image, which is caused by a low electric potential due to friction or the like. However, since the generation of such stains may be mistaken as a design change in the records of drawings, etc., there is a demand for improvement even for the occurrence of slight stains that were overlooked in conventional text records. Is the current situation.

Such stains include streak stains and background stains on the white paper portion. Here, streak stains are caused when the electrostatic recording body is rubbed by a slight convex portion or the like at a part of the edge of the recording electrode. This is a phenomenon in which only a portion is frictionally charged and appears as streak-like stains after development. The streak stains often reach several meters or more, and it is particularly required that the electrostatic recording medium for CAD has no streak stains. In addition, the background stain is a phenomenon also called fog.It is noted that the entire surface of the electrostatic recording body is charged with a low electric potential and is developed with toner, and then the blank area which is originally unrecorded is also recorded with a low image density. Say.

Conventionally, the background stain has been dealt with by conducting a conductive treatment on the back surface of the electrostatic recording medium to allow the low-potential electric charges that cause the stain to escape, but such a method alone can meet the current high demand level. The current situation is that it cannot be done at all.

(Problems to be Solved by the Invention) The present invention is an electrostatic recording method, in particular, a high-resolution electrostatic recording method such as 400 dots / inch, in which an electrostatic recording capable of obtaining a clear image without streaking or scumming is obtained. It is intended to provide the body.

(Means for Solving the Problem) For the above purpose, the inventors of the present invention have earnestly studied, and as a result, originally, in a dielectric layer that must have good insulating properties in order to keep a recorded image density high, It has been found that the above problem can be solved without sacrificing the image density by containing a certain amount of the antistatic agent, and the present invention has been completed.

That is, the present invention is an electrostatic recording body comprising a conductive layer and a dielectric layer formed by coating an organic solvent-based coating liquid containing an insulating resin in an organic solvent on a conductive support. An electrostatic recording medium for recording system in which a latent image is directly formed on the dielectric layer by the discharge of, and is further developed with toner, and 2.
An electrostatic recording material comprising 5 × 10 ^{-2 to} 1.5 × 10 ^-1 g / m ² of a zwitterionic antistatic agent or a nonionic antistatic agent.

(Function) Examples of the antistatic agent used in the present invention include polyoxyethylene ethers such as polyoxyethylene alkyl ether and polyoxyethylene alkylphenyl ether which are nonionic antistatic agents, polyoxyethylene laurate and polyoxyethylene. Polyoxyethylene fatty acid esters such as ethylene stearate Polyoxyethylene-based derivatives and polyoxypropylene-based derivatives or copolymers of both, glycerides such as glycerol laurate and glycerol stearate, and zwitterionic charging Examples of the inhibitor include alkyl betaine and alkyl glycine. Among the above antistatic agents, particularly nonionic antistatic agents are easily dissolved or evenly dispersed in the dielectric layer coating when the solvent type coating is applied to form the dielectric layer, or on the dielectric layer. It is more preferably used because it can be applied uniformly. It is more preferable to introduce a hydrophobic group or a hydrophobic polymer chain into the above nonionic antistatic agent because it can be uniformly dispersed or dissolved in the solvent-based dielectric layer coating material. If the content of the antistatic agent is small, the effect of improving stains cannot be seen, and conversely, if the content is large, there is an adverse effect that the recorded image density decreases.

Incidentally, a polymer electrolyte typified by a conductive agent used for imparting conductivity to a support of an electrostatic recording medium is one having 20 to 100 monomers containing anions or cations,
It has a strong hydrophilicity and a molecular weight of several thousand or more, so that it cannot be uniformly dispersed in the solvent-based dielectric layer coating material, and even if it is coated on the dielectric layer, it cannot be coated uniformly. For this reason, when the polymer electrolyte is used, there is a drawback that a portion where the charge for image recording is lost is formed and so-called white spots occur in the recorded image.

In the present invention, the presence of an antistatic agent in the dielectric layer means that the dielectric layer contains an antistatic agent, and the method is usually to charge an organic solvent-based dielectric layer paint Examples of the method include dissolving or dispersing the inhibitor with a stirrer, an attritor, etc., and coating the conductive support with a bar coater or the like.

In the present invention, streak stains and background stains can be eliminated without problems such as reduction in recorded image density and occurrence of white spots. However, such an effect can be obtained when the antistatic agent causes stains. It is presumed that it has a function of effectively releasing the electric charge of the electric potential.

The conductive support for constituting the electrostatic recording material, a cationic polymer electrolyte such as polyvinylbenzyltrimethylammonium chloride, or a conductive agent such as anionic polymer electrolyte such as sodium polystyrene sulfonate,
An inorganic salt such as sodium chloride, or conductive zinc oxide such as zinc oxide doped with aluminum, conductive tin oxide such as tin oxide doped with antimony, or the like is impregnated or coated with a surface specific resistance of 10 ⁵ ~Ten
¹¹ Ω paper, plastic film, etc. are used. Insulating resins such as polyvinyl acetate, polyvinyl butyral, polyester, methacrylic acid esters such as methyl methacrylate and butyl methacrylate, acrylic acid esters and other polymers and copolymers are used as the resin of the dielectric layer that constitutes the electrostatic recording body. As the pigment to be mixed with, there are calcium carbonate, titanium oxide, amorphous silica, calcined clay, plastic pigment and the like.

(Examples) Examples of the present invention will be described below, but it goes without saying that the present invention is not limited to these examples. still,
The parts shown below represent parts by weight.

Example 1 A cationic polymer electrolyte (product name: Chemistat 6300, manufactured by Sanyo Kasei Co., Ltd.) was applied to the surface of a high-quality paper having a basis weight of 53 g / m ^{2 in} an absolute dry weight of 3 g / m ² , and further to the back surface of 2 g / m ^2. Thus coated to form a conductor support. 50 parts of polyvinyl butyral resin, 50 parts of surface-treated calcium carbonate and 100 parts of methyl ethyl ketone
Parts and 100 parts of toluene dissolved and dispersed in a solvent with a stirrer, and 0.5 parts of a zwitterionic antistatic agent (trade name: Anhitol 24B, manufactured by Kao Soap Co.) consisting of alkylbetaine was added to the paint. An electrostatic recording material was prepared by applying an absolute dry weight of 5 g / m ^{2 on} the surface of the permeable support.

Example 2 67 parts of polyester resin (trade name: Byron 20S, manufactured by Toyobo Co., Ltd.), 30 parts of surface-treated calcined clay, high molecular weight nonionic charge composed of a hydrophobic group-introduced polyoxyethylene-polyoxypropylene derivative The same conductivity as that used in Example 1 was obtained by dissolving and dispersing 3 parts of an inhibitor (trade name: Discol 206, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) in a solvent consisting of 100 parts of toluene and 100 parts of methyl ethyl ketone using a stirrer. An electrostatic recording material was prepared by applying an absolute dry weight of 5 g / m ² on a permeable support.

Comparative Example 1 50 parts of polymethylmethacrylate resin and 50 parts of surface-treated calcium carbonate were dissolved and dispersed in 200 parts of toluene using a stirrer, and dried on an electroconductive support the same as that used in Example 1 with an absolute dry weight of 5 g / m ^{2 was} applied to prepare an electrostatic recording material.

Example 2 67 parts of polyester resin (trade name: Byron 20S, manufactured by Toyobo Co., Ltd.), 30 parts of surface-treated baked clay, cationic polymer electrolyte containing quaternary ammonium salt (trade name: Chemistat 6300, manufactured by Sanyo Kasei Co., Ltd.) ) Was dried and 100 parts of toluene and 100 parts of methyl ethyl ketone were dispersed by a stirrer and further dispersed for 1 hour by using a sand grinder to obtain an absolutely dry weight on the same conductive support as used in Example 1.
5 g / m ^{2 was} applied to prepare an electrostatic recording material.

Comparative Example 3 70 parts of polyester resin (trade name: Byron 20S, manufactured by Toyobo Co., Ltd.) and 30 parts of surface-treated baked clay were dissolved and dispersed in a solvent consisting of 100 parts of toluene and 100 parts of methyl ethyl ketone with a stirrer, and used in Example 1. An electrostatic recording material was prepared by applying an absolute dry weight of 5 g / m ² on the same conductive support as described above.

A recording test was performed on each of the above electrostatic recording bodies with an electrostatic plotter EP-101 for CAD manufactured by Matsushita Electric Industrial Co., Ltd., and the recorded image density and the background stain density of the margin were measured (image densitometer RD-100R,
(Manufactured by Macbeth Co.) shown in Table 1. Further, streaks on the recorded image and white spots on the recorded image were visually evaluated, and the results are also shown in Table 1.

The antistatic agents used in the present invention (Examples 1 and 2) all dissolve well in the dielectric layer coating liquid, and the nonionic antistatic agents used in Example 2 have particularly excellent coating properties and solubility. Indicated. The recorded image of the electrostatic recording body according to the present invention has streak stains, background stains,
There were no blank areas in the recording and the recorded image density was also good.

On the other hand, in Comparative Example 2, the polyelectrolyte was not dispersed in the coating liquid for the dielectric layer, resulting in white spots in the recorded image. However, good recording was not obtained.

(Effects) The electrostatic recording medium according to the present invention is free from streaking and background staining and has a high recorded image density, and is particularly suitable as an electrostatic recording medium for a CAD system.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshinori Yagi 4-3-1 Jōkoji, Amagasaki City, Hyogo Prefecture Kanzaki Paper Co., Ltd. Kanzaki Mill (56) References Japanese Patent Publication No. Sho 49-35701 Sho 49-34147 (JP, B1)

Claims (1)

[Claims] 1. An electrostatic recording body comprising a conductive layer and a dielectric layer formed by coating an organic solvent-based coating liquid containing an insulating resin in an organic solvent on a conductive support. Is an electrostatic recording medium for recording system in which a latent image is directly formed on the dielectric layer by discharge of and is further developed with toner.
An electrostatic recording material comprising a zwitterionic antistatic agent or a nonionic antistatic agent in an amount of × 10 ^{-2 to} 1.5 × 10 ^-1 g / m ² .