JPS6356973B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic recording medium used for direct electrostatic image formation and image transfer by applying a high charge, and exhibits particularly good recording characteristics over a wide temperature range, and The present invention relates to an electrostatic recording material that has a surface layer that has good abrasion resistance against repeated use, has excellent cleaning properties, and has printing durability.

Conventionally, recording methods using electrostatic charges include electrophotography, which uses a photoconductive material to form an electrostatic latent image through charging and exposure, and electrostatic recording, which forms an electrostatic latent image by directly charging a dielectric layer. The method is well known, and the formatted electrostatic latent image is developed using a developer to obtain a developed image, and this is directly fixed, or this developed image is transferred to general paper etc. and then fixed to form a recording paper. is obtained.
However, recording paper with direct fixation has drawbacks such as poor appearance and feel compared to ordinary paper, and inconvenience in handling.

On the other hand, in the case of the transfer method, general paper is used as the recording paper, so the above drawbacks are eliminated, but
In this case, since the recording medium is used repeatedly, the recording characteristics of the recording medium may deteriorate due to changes in humidity during repeated use or increased humidity in the equipment, resulting in poor clarity, decreased density, or gradation. Many of them had drawbacks, such as not being able to produce the desired results.

The present invention relates to a transfer-type recording medium used in an electrostatic system that has improved such drawbacks, and provides a recording medium that has improved durability compared to conventional recording bodies and exhibits excellent recording characteristics over a wide humidity range. It is.

That is, the present invention provides Al, Ga,
Or In-doped volume resistivity 10 ⁰ to ^{10 3} Ω・cm
A low resistance layer made of at least one type of zinc oxide and a thermosetting resin is provided, and a dielectric layer containing polyester resin and nitrocellulose and having mesh-like protrusions of 5 μm or less is provided thereon. This is an electrostatic recording medium.

Conventionally, conductive agents for electrostatic recording materials include surfactants, organic or inorganic salts, polymer electrolytes, metals,
Fine metal powders, metal oxides, etc. are well known, but among these, the resistance of surfactants, salts, and polymer electrolytes changes greatly depending on the amount of water they contain, so the recording characteristics are affected by humidity. . Furthermore, when metals are used, the resistance value changes little due to humidity, but the resistance value changes greatly depending on the slight difference in the amount of compounding or the coating method, so it is difficult to manufacture a product with constant recording characteristics. It was difficult.

In addition, examples of the highly insulating resin forming the dielectric layer include vinyl acetate resin, vinyl chloride resin, silicone resin, epoxy resin, acrylic resin, vinyl acetate/crotonic acid copolymer, styrene/butadiene copolymer, Vinyl chloride/vinyl acetate copolymer, vinylidene chloride/vinyl chloride copolymer, etc. are known, but when these are used in electrostatic recording media that are used repeatedly, the cleaning properties deteriorate during use. However, the recording paper gradually became foggy and stained black.

On the other hand, the present invention uses a metal oxide doped with a metal as a conductive agent with a volume resistivity of 10 ⁰ to 10 ³ Ωcm, such as zinc oxide doped with Al, Ga, In, etc., to a thermosetting resin. Provides a dispersed low resistance layer,
By providing a dielectric layer having mesh-like protrusions thereon, durability is improved, and a transfer type electrostatic recording material is obtained which exhibits excellent recording properties over a wide humidity range.

Next, to explain the present invention in detail, a plastic film such as polyester, polyvinyl chloride, polyvinylidene chloride, etc. is used as a support, and on this plastic film, for example,
Volume resistivity value 10 ⁰ to ^{10 3} Ω・doped with Al etc.
A conductive layer consisting of 50 to 95 parts by weight of zinc oxide, 50 to 5 parts by weight of a thermosetting resin such as epoxy resin, polyurethane resin, or phenol resin, and 1 to 10 parts by weight of a curing agent is provided, and then a conductive layer made of polyester The electrostatic recording material of the present invention is formed by laminating a dielectric layer having mesh-like protrusions of 5 μm or less, which is made of a resin, nitrocellulose, and, if necessary, a pigment and other additives.

The mesh-like protrusions are formed by pressing onto an intaglio roll after coating the dielectric layer and immediately before drying, by gravure printing, or by a coating method, and preferably have a height of 1 to 5 μm. If it exceeds 5 μm, it is not preferable because it causes wear of the recording electrode needle and reduces transfer efficiency and cleaning properties for residual toner.

The present invention will be explained below using examples.

Example 1 A polyvinylidene chloride film with a thickness of 50 μm was used as a support, and 35% of the following composition was applied on it by dry weight.
g/m ² to provide a low resistance layer with a surface specific resistance value of 1×10 ⁷ Ω.

Ga-doped zinc oxide epoxy resin diethylenetetramine (curing agent) Ethyl acetate 80 parts by weight 20 〃 5 〃 100 〃 On the above coated surface, further apply the following composition at a dry weight of 5 g/m ² and immediately after drying. An electrostatic recording material was produced by pressing a dielectric layer having mesh-like protrusions onto a concave heated roll.

Polyester resin nitrocellulose methyl ethyl ketone 90 parts by weight 10 〃 500 〃 This recording medium was coated with a linear density of 8 lines/mm and an applied voltage of -
A toner image was formed using a 700V electrostatic recording device and transferred to high-quality paper, resulting in a clear recorded image.

Further, after cleaning this electrostatic recording medium to remove residual toner, a high frequency corona of AC 100V and DC +7KV was applied to remove the residual charge. By repeating this operation, 5,000 clear recorded images were obtained.

Example 2 A polyester film with a thickness of 50 μm was used as a support, and the following composition liquid was applied on the support at a dry weight of 40 g/m ²
A low resistance layer with a surface specific resistance value of 8×10 ⁶ Ω was provided.

In-doped indium oxide polyurethane resin Ferric chloride (curing agent) Ethyl acetate 80 parts by weight 20 〃 3 〃 100 〃 On the above coated surface, the following composition liquid was further applied at a dry weight of 5 g/m ² . In this case, upon drying, a dielectric layer naturally having network-like protrusions was obtained.

Polyester resin Nitrocellulose Titanium oxide methyl ethyl ketone 90 parts by weight 10 10 500 Using the obtained recording material, 5000 clear recorded images were obtained in the same manner as in Example 1.

Comparative Example 1 A polyester film with a thickness of 50 μm was used as a support, and polyvinylbenzyltrimethylammonium chloride was applied thereon, and the surface resistivity value was 3.
A low resistance layer of ×10 ⁷ Ω was provided. Example 1
A dielectric layer was provided in the same manner as above to produce an electrostatic recording medium.

When this recording medium was used to record by repeating the same operations as in Example 1, background stains appeared after the 100th print, and the recorded images gradually became unclear.

Claims (1)

[Claims] 1 A low resistance layer made of a thermosetting resin and at least one type of zinc oxide doped with Al, Ga, or In and having a volume resistivity of 10 ⁰ to ^{10 3} Ω・cm is provided on an insulating support, and a low resistance layer made of a thermosetting resin is provided on the insulating support. 1. An electrostatic recording material comprising a dielectric layer containing polyester resin and nitrocellulose and having mesh protrusions of 5 μm or less.