JPH03224786A - Reversible thermal medium - Google Patents

Abstract

PURPOSE:To enhance heat resistance and abrasion resistance by forming the protective layer of a reversible thermal medium from poly-p-xylene or a similar polymer thereof. CONSTITUTION:A thermal layer 22 composed of a reversible thermal material is formed on a support 21 made of a polymer film and a poly-p-xylene layer 23 or a layer composed of a polymer similar to poly-p-xylene is further formed thereon as a protective layer. Therefore, when the reversible thermal medium 4 thus prepared is constituted in a belt form to be provided between the photosensitive body 1 and roll of an image forming apparatus under tension, the medium 4 is smoothly moved. When the reversible thermal medium 4 is sent to the nip between a heating roll 3 and a press roll 2 to be subjected to a transfer/fixing process, it is not deteriorated by heat. Further, when the medium 4 is fed to the part between an exposure means and the photosensitive body 1, the photosensitive body 1 can receive sufficient exposure because the medium 4 is colorless and transparent. Furthermore, since the medium 4 has high insulating properties, the lowering of image quality due to the discharge of the charge forming an electrostatic latent image is prevented and the surface thereof is not deteriorated even when the medium 4 generates the frictional slide with a developing means.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a reversible thermosensitive medium used in an image forming apparatus that forms an image on a reversible thermosensitive medium using a heat-generating recording element and records the image on plain paper. It's about the medium.

(Prior Art) Conventionally, in an image forming apparatus that uses a heat-generating recording element to record on thermal paper, the heat-generating recording element used for image formation is inexpensive, and the process is simple, so the price of the apparatus is also low.

Therefore, it is widely used in FAXs and printers that utilize a thermal recording method in which thermal writing is performed directly on thermal paper.

However, the recording paper used in this heat-sensitive recording method is a special paper that develops color when heated, and has a major problem in the storage stability of recordings.

To improve this, a thermal transfer recording method was proposed in which a film coated with ink is used as an intermediate medium, and a heat-generating recording element melts the ink on the film and transfers it to recording paper.This method is also widely used in printers. It is applied.

However, in the image forming apparatus with the above configuration, it is necessary to use a special recording paper, and if the surface is not smooth, the ink cannot be sufficiently transferred to the recording paper, so a heat-generating recording element is used. There are no devices that can record on plain paper.

On the other hand, an electrophotographic recording method is a typical example of a device that records on plain paper, and is widely used in copy paper and printers.

In addition, when applying this to a printer etc., the exposure means should be a combination of a laser and an imaging optical system, or an LED.
A combination of an array and an imaging optical system is used, but both are expensive.

That is, there is a problem in that an inexpensive device cannot record on plain paper, and a device that can record on plain paper is expensive, and neither can be satisfied.

Therefore, by solving the problems of the above conventional image forming apparatus,
Image forming apparatuses that are inexpensive and capable of recording on plain paper are available (see Japanese Patent Publication No. 30791/1983).
.

In addition, reversible heat-sensitive media used in such image forming apparatuses are made of polymers such as polyester or It is formed by dispersing organic low-molecular substances such as behenic acid in a matrix material made of resin.

FIG. 4 is a temperature/light transmission rate relationship diagram of a conventional reversible heat-sensitive medium.

The reversible heat-sensitive medium reversibly changes between a transparent state and a cloudy state depending on the temperature, and can maintain the two forms even at room temperature.

i) Formation of a transparent state The temperature of the reversible heat-sensitive medium, which initially exhibited a transmittance of (A) or (D) in the figure, was raised from room temperature T0 to exceed T2.
When the temperature reaches , the transmittance changes from (8) to (B) or from (D) to (B). After that, when it is cooled from T2 to room temperature T0, the transmittance changes from (B) to (D) and is fixed in a transparent state.

ii) Formation of an opaque state As the temperature of the reversible heat-sensitive medium, which initially showed a transmittance of (A) or (D), is increased, it exceeds T + , T z , and when the temperature reaches T1 or higher, ( A) → (B) → (C
) or (D)→(B)→(C).

After that, when cooling from T3 to room temperature T0, the transmittance becomes (
It changes from C) to (A) and is fixed in an opaque state.

On the other hand, reversible heat-sensitive media that utilize polymer compatibility/immiscibility include a mixture of a vinylidene fluoride polymer and an acrylic acid ester polymer.

FIG. 5 is a temperature/light transmission rate relationship diagram of another conventional reversible heat-sensitive medium.

In the figure, when forming a writing part, the temperature of the reversible heat-sensitive medium, which is initially in state A or C, is raised to exceed T1 and T.
2, the reversible thermosensitive medium is in state B and becomes opaque. After that, when it is rapidly cooled to room temperature T0, the state changes to A.
The reversible heat-sensitive medium is thus maintained in an opaque state.

On the other hand, if the temperature of the reversible heat-sensitive medium in state A or C is raised to T2 and then slowly cooled to room temperature T0, the state becomes B.
It changes from to C and becomes transparent.

That is, by controlling the cooling rate from the temperature T2, transparent state C and opaque state A can be formed.

These reversible heat-sensitive media are constructed by forming a heat-sensitive layer made of a reversible heat-sensitive material on a transparent polymer film support. Polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polystyrene, polycarbonate, polyester, polyimide, etc. are used for the polymer film.

Then, a protective layer is formed on the heat-sensitive layer in order to prevent thermal oxidation and abrasion of the heat-sensitive layer and adhesion of the reversible heat-sensitive material to the heat-generating recording element.

The protective layer includes SiO2, SiO, MgO, ZnO, T
iO2, A1□0. , Ta, 05, and other transparent inorganic materials are used.

(Problems to be Solved by the Invention) However, the reversible heat-sensitive medium having the above structure has a problem in that the protective layer formed on the heat-sensitive layer lacks flexibility and insulation. That is, since the reversible heat-sensitive medium is used in the form of a belt, it is required to have flexibility, and since it is necessary to adhere the toner onto the reversible heat-sensitive medium by electrostatic force, it is required to have high insulation properties.

Therefore, it is preferable to form the protective layer with a polymer, but in the fixing process, the reversible heat transfer medium is heated to around 160° C. by a heating roll to melt the toner, and ends up melting. Moreover, in the case of polymers, they are easily abraded and easily scratched.

The present invention solves the problems of the conventional reversible heat-sensitive media and forms a protective layer that is highly heat resistant, wear resistant, scratch resistant, colorless and transparent, and allows for efficient exposure. The purpose of the present invention is to provide a reversible heat-sensitive medium.

(Means for Solving the Problems) For this purpose, in the reversible misothermic medium of the present invention, a heat sensitive layer made of a reversible misothermic material is formed on a polymer film, and further thereon, poly-p-xylylene or A protective layer is formed from a similar polymer.

The melting point of poly-p-xylylene and its similar polymers is 40
It has a high temperature of 5°C, and a high volume resistivity of 1.4 XIO"Ω1. It is also colorless and transparent, and is resistant to wear and scratches. Furthermore, since it is a polymer, it is flexible.

(Function) According to the present invention, a heat-sensitive layer made of a reversible heat-sensitive material is formed on a polymer film as described above, and a protective layer made of poly-p-xylylene or a similar polymer thereof is further formed thereon. Therefore, the reversible heat transfer medium is configured in a belt shape,
Even when it is stretched between a photoreceptor and a roll of an image forming apparatus, it can be moved smoothly.

Further, even when the transfer/fixing process is carried out by being sent between a heat generating roll and a pressure roll, it will not deteriorate due to heat. Moreover, since it is colorless and transparent, when it is sent between the exposure means and the photoreceptor, the photoreceptor can receive sufficient exposure.

Furthermore, since the insulating property is high, the charge forming the electrostatic latent image will not be discharged and the quality of the image will not deteriorate, and the surface will not deteriorate even if it rubs against a developing means or the like.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of the reversible heat-sensitive medium of the present invention.

In the figure, 21 is a support made of polymer film;
22 is a heat sensitive layer. The phase change of fatty acids dispersed in the polymer or the state change between compatibility and incompatibility of the polymer is used. 23 is a protective layer made of poly-p-xylylene or a similar polymer thereof, which protects the heat-sensitive layer 22 thermally and mechanically (from abrasion, etc.) and prevents the reversible heat-sensitive material from adhering to the heat-generating recording element. prevent.

FIG. 2 is a diagram showing the main physical properties of poly-p-xylylene and its similar polymers. All of them have good heat resistance, insulation properties, and light transmittance.

FIG. 3 is a schematic diagram of an image forming apparatus using the reversible thermosensitive medium of the present invention.

In the figure, 1 is a drum-shaped photoreceptor;
It is formed by providing a photoconductive layer on a conductive support. Any of selenium photoreceptors, organic photoreceptors, etc. can be used. 2 is a pressure roll, and 3 is a heating roll. The heating roll 3 can be a hollow metal member with a built-in halogen lamp, or a metal surface with a heating element directly provided thereon.

4 is a reversible heat-sensitive medium, in which a heat-sensitive layer made of a reversible heat-sensitive material is formed on a transparent support, that is, a polymer film, and a protective layer made of poly-p-xylylene or a similar polymer is further formed thereon. Forming 7 The reversible heat-sensitive medium 4 is placed between the photoreceptor 1 and the pressure roll 2. 5 is a heat-generating recording element, which is usually called a thermal hend. 6 is a platen roll, and the reversible heat-sensitive medium 4 is connected to the heat generating recording element 5 and the platen roll 6.
It is sandwiched between and pressurized.

A corona charger 7 is a charging means, and is provided facing the surface of the photoreceptor 1. In addition to this, a brush charger or the like can be used as the charging means.

Reference numeral 8 denotes a fluorescent lamp serving as a full-surface exposure means, and is provided on the reversible heat-sensitive medium 4 which is closely stacked on the photoreceptor l. As the whole surface exposure means, in addition to a fluorescent lamp, any light source with uniform light intensity, such as a halogen lamp or an LED, can be used.

The developing means attracts the toner 10 onto the developing roll 9, conveys it, and develops it, and is provided on the surface of the reversible heat-sensitive medium 4 which is closely stacked on the photoreceptor 1. As the developing means, any of a two-component magnetic brush developer, a -component magnetic brush developer, a -component non-magnetic developer, etc. can be used.

11 is recording paper, and plain paper can be used.

A fixing cleaner 12 removes toner remaining on the reversible heat-sensitive medium 4 after the transfer process. Reference numeral 13 denotes a static eliminating brush, which removes static electricity charged on the reversible heat-sensitive medium 4. Reference numeral 14 denotes a static elimination lamp, which removes residual charges on the photoreceptor 1. Reference numeral 15 denotes a heating element over the entire surface, which heats and slowly cools the reversible heat-sensitive medium 4 to bring it into an erased state (transparent IQ).

Next, the operation and function of an image forming apparatus using a mixture of a vinylidene fluoride polymer and an acrylic acid ester polymer as the heat-sensitive layer of the reversible thermal medium will be described.

When the photoreceptor 1, the pressure roll 2, the heating roll 3, and the platen roll 6 are rotated at a constant circumferential speed in the direction of the arrow shown in the figure by a driving means (not shown), the reversible heat-sensitive medium 4 is rotated by the photoreceptor 1,
It moves in the direction of the arrow shown in the figure by the pressure roll 2, heating roll 3, and platen roll 6.

First, the heat-generating recording element 5 is used to perform thermal writing on the reversible thermosensitive medium 4 in accordance with an image signal.

In this case, the reversible heat-sensitive medium 3 is heated in a pulsed manner by each element of the heat-generating recording element 1, and the heated portion becomes opaque, forming a dot image. and,
The heated area is rapidly cooled and remains opaque, so that the reversible thermosensitive medium 3 forms an image due to the difference in transmittance.

On the other hand, the photoreceptor 1 is uniformly charged using a corona charger 7. Next, the reversible heat-sensitive medium 4 is closely stacked on the photoreceptor 1, and the entire surface of the reversible heat-sensitive medium 4 is irradiated with light using the full-surface exposure means 9. The amount of light corresponding to the image formed by the difference in transmittance of the reversible heat-sensitive medium 4 is transmitted through the reversible heat-sensitive medium 4 and is irradiated onto the photoreceptor 1 . This results in
An electrostatic latent image is formed on the photoreceptor 1.

In the developing process, lines of electric force accompanying the electrostatic latent image formed on the photoreceptor 1 are generated in the space between the developing roll 9 and the reversible heat-sensitive medium 4, penetrating the reversible heat-sensitive medium 4. Developing roll 9
The upper charged toner 10 adheres to the reversible heat-sensitive medium 4 by electrostatic force and is developed.

In the transfer/fixing process, recording paper 11 is fed and fed from a paper feed section (not shown), and is passed through a pressure roll 2 and a heating roll 3.
transported between. Here, the recording paper 11 is the reversible thermosensitive medium 4
can be layered on top. The toner image formed on the reversible heat-sensitive medium 4 is heated and melted by the heat of the heating roll 3. The molten toner 10 penetrates between the fibers of the recording paper 11 under pressure and is fixed. Then, the fixed recording paper 11
is transported outside the device.

On the other hand, the reversible heat-sensitive medium 4, which had until then held an image in which a written part and a non-written part existed due to the difference in transmittance, is heated to around a temperature T by the entire surface heating element 15. Then, by the time it reaches the heat-generating recording element 5, it is gradually cooled down to room temperature and returns to its original transparent state. In this way, the reversible thermosensitive medium 4
The image is erased and used repeatedly.

Further, although a small amount of toner may remain on the reversible heat-sensitive medium 4 after being transferred to the recording paper 11, it can be easily wiped off by pressing the fixing cleaner 12 on the pressure roll 3. Further, although the reversible heat-sensitive medium 4 may be charged with static electricity, it is removed by the static electricity removal brush provided in contact with the reversible heat-sensitive medium 4. In this way, the reversible heat-sensitive medium 4 is used repeatedly after the image is erased, cleaned, and static electricity is removed.

On the other hand, the photoreceptor 1 is exposed to a reversible heat-sensitive medium 4 after the development process.
After separation, the residual charge on the surface is removed by the static elimination lamp 14. In this way, the photoreceptor 1 can also be used repeatedly.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

For example, in addition to the printers shown in the embodiments, the reversible heat-sensitive medium of the present invention can be used in display devices that form an image on a reversible heat-sensitive medium using a heat-generating recording element and visualize the image with toner using a photoreceptor. It can be applied to

(Effects of the Invention) As described in detail above, according to the present invention, the protective layer of the reversible heat-sensitive medium is made of poly-p-xylylene or a similar polymer thereof, so the reversible heat-sensitive medium has high heat resistance and abrasion resistance. A thermosensitive medium can be provided.

In addition, poly-p-xylylene or a polymer similar thereto has high insulation properties (and excellent transparency), resulting in good image quality.

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view of the reversible heat-sensitive medium of the present invention, Figure 2 is a diagram showing the main physical properties of poly-p-xylylene and its similar polymers, and Figure 3 is a diagram showing the reversible heat-sensitive medium of the present invention. A schematic configuration diagram of the image forming apparatus used; FIG. 4 is a diagram showing the temperature/light transmission speed relationship of a conventional reversible heat-sensitive medium; and FIG. 5 is a diagram showing the temperature/light transmission speed relationship of another conventional reversible heat-sensitive medium. be. DESCRIPTION OF SYMBOLS 1... Photoreceptor, 2... Pressure roll, 3... Heat generating roll, 4... Reversible thermosensitive medium, 5... Heat generating recording element, 7... Corona charger, 10...・Toner, 13...
- Static elimination brush, 15... Full heating element, 2I... Support, 22... Heat sensitive layer, 23... Polyxylylene.

Claims (4)

[Claims] (1) (a) A heat-sensitive layer made of a reversible heat-sensitive material is formed on a polymer film, and (b) a protective layer made of poly-P-xylylene is formed on the heat-sensitive layer. A reversible heat-sensitive medium. (2) (a) A heat-sensitive layer made of a reversible heat-sensitive material was formed on a polymer film, and (b) a protective layer made of poly-monochloro-p-xylylene was formed on the heat-sensitive layer. Characteristic reversible heat-sensitive medium. (3) (a) A heat-sensitive layer made of a reversible heat-sensitive material was formed on a polymer film, and (b) a protective layer made of poly-dichloro-p-xylylene was formed on the heat-sensitive layer. Characteristic reversible heat-sensitive medium. (4) (a) A heat-sensitive layer made of a reversible heat-sensitive material was formed on a polymer film, and (b) a protective layer made of poly-tetrafluoro-p-xylylene was formed on the heat-sensitive layer. Characteristic reversible heat-sensitive medium.