JPH0436770A - Electrostatic heat recording method - Google Patents

Abstract

PURPOSE:To form a vivid image at a simple stage and at low cost in a stage where it is fitted for color or multi-level monochrome by giving a heat signal so that an electrostatic latent image may be formed and developing it with toner having reverse polarity to the latent image after electrostatically charging an electrostatic heat recording layer. CONSTITUTION:In an electrostatic charging means 3, the most uniform electrostatic charging is performed in a method by corona discharging, and a method in which voltage is impressed on a metallic roller and a method in which triboelectrification is performed by means of various rollers having a brush and a sponge material whose surface is made of organic or inorganic material are also used. In this recording method, heating is performed according to a digital signal from a thermal head 4 at a heating stage by the heat signal. Development is performed by using the toner 5 having the reverse polarity to the electrostatic latent image. The image developing toner on a recording medium is used to be transferred and fixed to a non-recording medium such as a paper, and the electrostatic recording layer having the image developing toner is used as it is. Since the development is performed with the toner having reverse polarity to the electrostatic latent image, the adhesive force of the recording layer and the toner is stable and a trouble such as image flowing is not caused even when the recording layer has a smooth and low energy surface, thereby obtaining a sharp image.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to an electrostatic thermal recording method.

[Prior Art] A resin layer that reduces electrical resistance by heating, such as a resin layer made of polyvinyl chloride, polyethylene, polyester, polystyrene, styrene-maleic acid copolymer, etc., is provided on an electrically conductive substrate, and this layer is A method of forming an electrostatic latent image by electrostatically charging and irradiating with heat rays according to the original image (Japanese Patent Publication No. 85-14722), or using polyester, chlorinated polyvinyl chloride, vinyl chloride, etc. A copying method in which an electrothermographic material that is sufficiently transparent to heat rays is placed on the original image to be copied, an electrostatic charge is applied, and then an electrostatic latent image is created by the action of heat rays, which is then reversely developed and fixed using dry toner. Kosho H-14347) is known.

In these techniques, infrared rays are irradiated while the document is in close contact with the document, resulting in poor image resolution and the required recording energy. Another problem is that the chargeable material directly serves as the recording material for images, resulting in high material costs.

The present inventor previously made a proposal to improve these problems (Japanese Patent Application No. 1-240578).

This method involves reversal development with toner of the same polarity as the electrostatic latent image,
The recording method j, which transfers and fixes onto a non-recording medium, is suitable for printers and copiers whose main signal source is monochrome character information, but it is suitable for printers and copiers whose main signal source is monochrome character information, but it is not possible to use color information, multi-tone monochrome (photographic information), or information with many solid areas. It is not necessarily a sufficient recording method.

[Problem to be solved by the invention] In view of these circumstances, the present invention can solve the problem by a simple process, at low cost,
It is an object of the present invention to provide a recording method that can form a clear image that is suitable for color, multi-gradation monochrome, or solid information.

[Means for Solving the Problems] As a result of intensive study, the inventor of the present invention found that in applications where it is desired to record color information, multi-tone monochrome (photographic information), or information with many solid areas, it is preferable to It is better to visualize the
When used in microfilms and the like, the inventors discovered that it is better to use the visualized electrostatic thermal recording medium as it is without performing transfer, leading to the present invention.

That is, the present invention has the following features: (1) After uniformly charging an electrostatic thermal recording layer that is chargeable at room temperature and becomes non-chargeable or weakly chargeable under heating, a thermal signal corresponding to an image signal is applied. (2) an electrostatic thermal recording method in which an electrostatic latent image is formed with a toner of opposite polarity to that of the electrostatic latent image; (2) the electrostatic latent image according to claim (1) is developed with a toner of opposite polarity; Alternatively, there is an electrostatic thermal recording method in which a medium having an electrostatic thermal recording layer carrying visualization information is used as an image display body by performing reversal development with toner of the same polarity.

The electrostatic thermal recording layer in the method of the present invention has a softening point of 30 to 2
A suitable material is a thermoplastic plastic layer heated at 00°C, preferably 60 to 150°C, and has an electrical resistance of 10"Qcm or more at room temperature and 109 Ωell or less when receiving a heating signal.

Specific examples include polyvinyl chloride, cellulose acetate, polyacetal, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, acrylic polymer, styrene polymer, polyester, polyamide, polyethylene, polypropylene, polypropylene polymer, fluorine Examples include chemically acrylic-acrylic copolymers, styrene-acrylic copolymers, and the like.

Among them, fluorinated acrylic-acrylic copolymer,
Polypropylene and polypropylene copolymers are preferred, particularly polypropylene, polypropylene copolymers, or mixtures thereof.

The above polypropylene copolymer is polypropylene-
Ethylene, polypropylene-butene, polypropylene-
Ethylene-butene terpolymer, polypropylene-vinyl acetate, polypropylene-ethyl acrylate, polypropylene-ionomer copolymer, etc., and the thickness of the electrostatic thermal recording layer is 5 to 100 μm, preferably 10 to 30 μm. It is.

The structure of the recording medium of the present invention will be specifically explained with reference to the drawings. FIG. 1 shows an example of the electrostatic thermal recording medium of the present invention.

It consists of an electrostatic thermal recording layer 1 and a conductive layer 2. The electrostatic thermal recording layer 2 has a softening point of 30 to 200°C, preferably 60 to 150°C.
℃ thermoplastic layer.

The base layer is a support member for the electrostatic thermal recording layer 1, and is made of a film-forming material such as polyester, vinyl chloride, polyethylene, etc., and may also be used as the electrostatic thermal recording layer 1.

Although it is better to have the conductive layer 2 in order to obtain uniform charging, it is not necessary if charging is carried out on a metal roller or metal plate in the charging process.

The material for the conductive layer is A1 vapor deposition layer (100 JI to 200
0 thickness) and various conductive treatment agents are used. Furthermore, if a metal drum or belt is used, it can also be used as the base layer.

The present invention will be explained below based on the drawings.

FIGS. 1(A) to 1(C) are diagrams illustrating the electrostatic thermal recording method of the present invention.

Charging process (Figure 1 (A)) The method using corona discharge provides the most uniform charging, but it is also possible to apply a voltage to a metal roller or use frictional charging using a roller with a brush or sponge material that has various organic or inorganic surfaces. A method of doing this can also be used.

Heating process using thermal signals (Figure 1 (B)) In conventional thermoelectrostatic recording, the document and the recording medium are overlapped and the absorption and heat generation of the black areas by infrared irradiation is utilized (analog signal), but this recording Heating is performed using digital signals from the heat head.

(The thermal head used is a serial head or line head with a high resolution of 8 dots/am to IB dots/am.

Development process (FIG. 1(C)) Development is carried out using toner (Φ toner in the figure) having a polarity opposite to that of the electrostatic latent image (θ in the figure).

The visualized toner on the recording medium can be used even if it is transferred to a non-recording medium such as paper and fixed, but the electrostatic recording layer containing the visualized toner can also be used as it is.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 A 25μ polypropylene (pp) film was placed closely on an A1 drum, a surface potential of θ500v was placed on it using an e-corona, and thermal writing was performed using an 8 dot/aS thermal head. When the remaining E latent image area was developed using a polar cyan liquid developer manufactured by Ricoh, a clear cyan image was obtained as a negative image when the written signal area (character area) was set as positive.

Apply this filter to an OHP projector (Ricoh 313R).
) and projected it onto a screen, a sharp character pattern stood out against the clear cyan background.

Example 2 An electrostatic thermal recording medium in which AI was deposited on 50 μm white PET (with white pigment) was used as an endless belt, and a surface potential of Φ700v was applied to it via a conductive rubber roller in the same manner.
The recording medium was thermally written using a Dot/SS thermal head and developed with cyan powder toner (Φ polarity) for Ricoh color copying machine (ARTAGE-5310).
As shown in Figure), after displaying an image and cleaning the used screen, the recording medium and toner could be reused.

Example 3 EE with a conductive rubber roller on 25 μs PP deposited with AI
After being charged with an oov charge, photo information was thermally written on the A1 side using a thermal head, and at the same time, the electrostatic thermal recording layer on the opposite side was developed using a sponge roller impregnated with Ricoh's e-polar liquid developer. An image was obtained that faithfully reproduced the tone of the image. Since the PP surface of this recording medium does not come into direct contact with the thermal head, it has less unevenness due to heat and is suitable for repeated use (confirmed up to 1000 times).

[Effects of the Invention] As explained above, since the electrostatic latent image is developed with toner of opposite polarity, the adhesion between the recording layer and the toner is stable, and the recording layer has a smooth and low energy surface (such as PP). )but,
Sharp images can be obtained without any problems such as image blurring.

Also, when performing reversal development with toner of the same polarity as the electrostatic latent image,
It can also be used in applications where a recording medium containing visualization information is used as is.

When the thermal writing surface is provided on the side opposite to the development surface, writing and development can be performed simultaneously, making it possible to downsize the device, increase the recording speed, and further increase the number of times of repeated use.

[Brief explanation of drawings]

FIGS. 1A to 1C are diagrams for explaining each step of the electrostatic thermal recording method of the present invention, and FIG. 2 is a diagram for explaining the electrostatic thermal recording method when an endless belt is used as a recording medium.

Claims (3)

[Claims] (1) After uniformly charging the electrostatic thermal recording layer, which is chargeable at room temperature and becomes non-chargeable or weakly chargeable under heating,
An electrostatic thermal recording method characterized by forming an electrostatic latent image by applying a thermal signal corresponding to an image signal, and developing the electrostatic latent image with toner having a polarity opposite to that of the electrostatic latent image. (2) The electrostatic latent image according to claim (1) is developed with a toner of opposite polarity or is reversely developed with a toner of the same polarity, and the medium having an electrostatic thermal recording layer having the visualization information is used as an image display as it is. An electrostatic thermal recording method characterized by being used as a body. (3) The electrostatic thermal recording method according to claim 1 or 2, wherein the thermal signal corresponding to the image signal is applied from the surface opposite to the development surface.