JP3214102B2 - Image recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording method for performing printing or image printing based on image signals.

[0002]

2. Description of the Related Art For example, various printing methods have been proposed for printers of computers and word processors, and a thermal transfer recording method is one of them. This thermal transfer recording system uses a thermal transfer ribbon having a heat-meltable ink as an ink layer, and its transfer principle is as follows.

[0003] First, a thermal transfer ribbon having a solid, hot-melt ink applied at room temperature on a substrate is brought into close contact with a transfer paper by pressing force of a thermal head. At this time, the heat-meltable ink solid at room temperature is softened and melted by the heat of the thermal head. Next, when the thermal transfer ribbon is peeled off from the transfer receiving body when the ink returns to the solid state, the heat-meltable ink in the softened and melted portion is transferred onto the transfer receiving paper, and a print or the like is formed on the transfer receiving paper. You.

The above-described thermal transfer recording method is very useful for providing a compact and low-cost printer device because the device configuration can be simplified. Has disadvantages. First, in the thermal transfer recording method, only binary recording can be performed, and gradation cannot be output. This does not cause much problem when only printing is performed, but becomes a major obstacle when forming an image.

The recording energy is 4-6 J / cm ^2.
Big and slow. Further, there is a limit to the pixel density. (In the current technology, the pixel density of the thermal head is limited to about 300 dpi.) In addition, there are many problems in terms of running cost and environmental protection. That is, the ink in the non-image portion of the heat-meltable ink remains on the ink ribbon as it is, but the ink remaining on the thermal transfer ribbon cannot be used repeatedly. Therefore, most of the ink will be discarded, but this will increase running costs and may also lead to environmental destruction.

On the other hand, as a method for image recording, an electrostatic latent image formed on a photoreceptor is developed with a developer in which a toner containing colorant particles is dispersed in a liquid and electrically insulating dispersion medium. There is also a known method. This is what is called an electrophotographic process, and according to the wet development method,
It is possible to obtain resolution and gradation comparable to silver halide photography. Above all, a wet development method using a solidified developer in which a dispersion medium which is solid at room temperature and melts by heating and solidifies by cooling is subjected to wet development in a heat-melted state, in terms of storage stability and handleability of the developer. It is very good.

However, in the image formation by the wet development method using the solidified developer, there is a problem that it is difficult to transfer the image. For example, the applicant of the present application has disclosed in Japanese Patent Application Laid-Open No. Hei 2-81073 that a developer image having a colorant (or a toner) and a dispersion medium on a substrate (for example, a photoreceptor) is heated and coated in a molten state. There has been proposed a method in which a transfer member is brought into contact with a transfer member to transfer the image, or a method in which a developer image is transferred by pressing against a transfer member during solidification by cooling.

However, if the transferred image is brought into contact with a substrate (for example, a photoreceptor) and peeled off while the developer image is in a molten state, the image may be disturbed, uniform transfer is difficult, and unevenness is often observed. Can be Further, when the transfer member is pressed against the transfer member during cooling and solidification, the transfer is not sufficiently performed, and the quality of the transferred image is significantly deteriorated. Furthermore, there is a problem that the recorded image transferred to the transfer receiving body lacks abrasion resistance.

[0009]

As described above, in the thermal transfer recording system, gradation cannot be obtained, resolution is insufficient, and transfer is difficult in the wet development system using a solidified developer. The properties and durability of the recorded images have become major issues, and their solutions are expected to be solved.

Accordingly, the present invention has been proposed in view of such a conventional situation.
It is an object of the present invention to provide an image recording method capable of obtaining an image having a high resolution and having excellent transferability and excellent durability of a recorded image. A further object of the present invention is to provide an image recording method which requires a small recording energy for image formation, does not waste ink, and has a very high recording speed.

[0011]

In order to achieve the above-mentioned object, an image recording method according to a first aspect of the present invention forms an electrostatic latent image on a substrate, and forms the electrostatic latent image at room temperature. The colorant particles and the dispersion are dispersed on the surface of the substrate by developing using a solidified developer in which the colorant particles are dispersed in a dispersion medium that is solid and reversibly repeats solidification by melting and cooling by heating exceeding the melting point. After forming the developer image composed of the medium, the base and the transfer-receiving body were pressed and heated, the pressure heating was set to the melting point of the dispersion medium or higher to melt the dispersion medium, and then the dispersion medium was cooled to a temperature equal to or lower than the melting point. Thereafter, the developer image is recorded by transferring the developer image on the substrate surface to the transfer object by reheating the substrate from the back side and peeling the transfer object from the substrate.

Further, according to the image recording method of the second invention of the present invention, an electrostatic latent image is formed on a substrate, and the electrostatic latent image is solid at room temperature and is melted and cooled by heating exceeding a melting point. After forming a developer image composed of the colorant particles and the dispersion medium on the surface of the substrate by performing development using a solidified developer obtained by dispersing the colorant particles in a dispersion medium that reversibly solidifies, the substrate and The transfer medium is heated under pressure, the pressure heating temperature is set within a range not exceeding the melting point of the dispersion medium, the dispersion medium is softened, and then the transfer object is peeled off from the base to thereby transfer the developer image on the substrate surface to the transfer medium. The image is recorded by transferring the image to a computer.

The image forming process of the present invention comprises a charging step, an exposing step, a developing step, a press-contact heating step, and a peeling step. Further, if necessary, the transferred object is subjected to a heat treatment step to form a recorded image. The photoconductor is used again in the image forming process after a cleaning process.

The charging step and the exposing step are the same as in the case of the usual Carlson method electrophotography. That is, first, as shown in FIG. 1, a photosensitive member 1 having a photosensitive layer 3 provided on a conductive substrate 2 is uniformly charged, for example, negatively by using a suitable charging means such as corona discharge in a charging step. Be charged.

Here, for the photosensitive layer 3 of the photoreceptor 1, a known organic photoconductor or inorganic photoconductor can be used. For example, the organic photoconductor can be selected from a wide range of well-known substances, and practically used materials include poly-N-vinylcarbazole and 2,4,7
-An electrophotographic photosensitive substrate comprising -trinitrofluoren-9-one, poly-N-vinylcarbazole sensitized with a pyrylium salt dye, poly-N-vinylcarbazole sensitized with a cyanine dye, Examples thereof include an electrophotographic photosensitive substrate mainly containing an organic pigment, and an electrophotographic photosensitive substrate mainly containing a eutectic complex composed of a dye and a resin. As the inorganic photoconductor, zinc oxide, zinc sulfide, cadmium sulfide, selenium, selenium-tellurium alloy, selenium-arsenic alloy,
Selenium-tellurium-arsenic alloys, amorphous silicon-based materials and the like can be mentioned.

Then, in the next exposure step, selective light irradiation corresponding to the image information is performed by using an appropriate exposure means such as a semiconductor infrared laser light source and the like, as shown in FIG. The negative charges disappear and an electrostatic latent image is formed. Note that the electrostatic latent image may be formed on the surface of the dielectric substrate by an electrostatic method such as a multi-stylus or an ion flow method without using a photoconductor.

In the developing step, the photoreceptor 1 on which the electrostatic latent image has been formed as described above is developed by a developer.
As shown in FIG. 3, a developer image 4 containing colorant particles is formed according to the electrostatic latent image. At this time, a solidified developer in which positively charged colorant particles are dispersed in an electrically insulating dispersion medium that is solid at room temperature is used as the developer.
The developer is heated and melted by a heating means, and is in a liquid state during development, but solidifies again when cooled.

The dispersion medium used in the developer is an electrically insulating organic substance, and its melting point is set to 30 ° C. or higher in consideration of ordinary use environment and handleability, more preferably 40 ° C.
Above. The upper limit of the melting point is not particularly limited, but is practically about 100 ° C, more preferably 80 ° C.
It is as follows. This means that extra energy is consumed for heating even if the melting point is too high, and that the material must not exceed the heat-resistant temperature of the material generally used as a support when used on a support. It is a matter of consideration.

Materials for the dispersion medium satisfying these requirements include paraffins, waxes, and mixtures thereof. First, as paraffins, there are various normal paraffins having 19 to 60 carbon atoms ranging from nonadecane to hexacontan. Carnauba wax,
Vegetable wax such as cotton wax; animal wax such as beeswax; ozokerite; and petroleum wax such as paraffin wax, microcrystalline wax and petrolatum. These materials are generally dielectric materials having a dielectric constant ε of about 1.9 to 2.3. In order to increase the cohesion of the dispersion medium, an ethylene-vinyl acetate copolymer or the like may be added.

Further, polyethylene, polyacrylamide, poly-n-stearyl acrylate, poly-n
A crystalline polymer having a long alkyl group in the side chain such as a homopolymer or copolymer of polyacrylate such as stearyl methacrylate (eg, copoly-n-stearyl acrylate-ethyl methacrylate) can be used, Considering the above, paraffins and waxes are preferred.

The colorant particles dispersed in the electrically insulating organic material include inorganic pigments, organic pigments, and conventionally known pigments.
Dyes and mixtures thereof can be used. For example, inorganic pigments include chromium pigments, cadmium pigments, iron pigments, cobalt pigments, ultramarine, navy blue and the like. In addition, as organic pigments and dyes, Hansa Yellow (CI11
680), benzidine yellow G (CI21090), benzidine orange (CI21110), fast red (CI3708)
5), Brilliant Carmine 3B (CI16015-Lake), Phthalocyanine Blue (CI74160), Victoria Blue
(CI42595-Lake), Spirit Black (CI50415)
, Oil blue (CI74350), alkaline blue (CI4
2770A), first scarlet (CI12315), rhodamine 6B (CI45160), rhodamine lake (CI4516
0-Lake), First Sky Blue (CI74200-Lake)
, Nigrosine (CI50415), carbon black and the like. These can be used alone or as a mixture of two or more kinds, and those having a desired color may be selected and used.

In addition to the electrically insulating organic substance and the colorant particles, a resin may be used in combination with the developer for the purpose of improving the dispersibility and the chargeability of the colorant. As the resin, known materials can be appropriately selected and used. For example, rubbers such as butadiene rubber, styrene-butadiene rubber, cyclized rubber, and natural rubber, styrene resin, vinyl toluene resin, acrylic Resins such as synthetic resins, methacrylic resins, polyester resins, polycarbonate resins, polyvinyl acetate resins, and alkyd resins including modified alkyds such as rosin resins, hydrogenated rosin resins, and linseed oil-modified alkyd resins And natural resins such as polyterpenes. In addition, modified phenol resins such as phenol resins and phenol formalin resins, pentaerythritol phthalate, coumarone-indene resins, ester gum resins, vegetable oil polyamide resins, etc. are also useful, and polyvinyl chloride, chlorinated Halogenated hydrocarbon polymers such as polypropylene, synthetic rubbers such as vinyltoluene-butadiene and butadiene-isoprene;
Polymers of acrylic monomers having a long-chain alkyl group such as ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, lauryl acrylate, octyl acrylate, or copolymers thereof with other polymerizable monomers (for example, styrene-lauryl methacrylate) Copolymers, acrylic acid-lauryl methacrylate copolymers), polyolefins such as polyethylene, polyterpenes, and the like.

Further, a charge donor is usually added to the above-mentioned developer, and the developer used here is no exception. Examples of the charge donor used include metal salts of fatty acids such as naphthenic acid, octenoic acid, oleic acid, stearic acid, isostearic acid and lauric acid, metal salts of sulfosuccinates, metal salts of oil-soluble sulfonic acid, and phosphoric acid. Metal salts such as ester metal salts and abietic acid; metal salts of aromatic carboxylic acids; and metal salts of aromatic sulfonic acids.

Further, in order to improve the charge of the colorant particles, SiO ₂ , Al ₂ O ₃ , TiO ₂ , ZnO, G
a ₂ O ₃ , In ₂ O ₃ , GeO ₂ , SnO ₂ , Pb
Fine particles of metal oxide such as O ₂ and MgO or a mixture thereof may be added as a charge enhancer.

After the developer image 4 is formed by the above-described development process, the transfer-receiving member 5 is overlaid as shown in FIG. 4, and the transfer process is performed. Here, as the material that can be used as the transfer object, a material having a large adhesive force to the solidified developer as described above is preferable, and can be appropriately selected depending on the application. For example, various papers such as natural paper and synthetic paper,
Cloth or nonwoven fabric made of vegetable fiber such as cotton or hemp, or animal fiber such as silk or wool, cloth or nonwoven fabric made of organic synthetic fiber such as polyamide, polyester, polyacetal or polyurethane, inorganic fiber such as ceramics or carbon, metal And meshes of organic polymers and the like, and polymer foams such as polyurethane foams and the like. In order to save the document in the form of a normal document, it is preferable to use a white paper or the like as the transfer object from the viewpoint of enhancing the visibility, but it is needless to say that the present invention is not limited to this.

The transfer member 5 may have a resin layer compatible with the dispersion medium of the solidified developer formed on the surface thereof for the purpose of securing an adhesive force to the solidified developer. Good. Thereby, the transfer of the developer image 4 can be made more reliable.

The resin constituting the resin layer formed on the surface of the transfer object may be any resin as long as it is compatible with the dispersion medium, such as a thermoplastic elastomer, a low-density polyolefin, and an ionomer resin. , Vinyl acetate copolymerized polyolefin, low molecular weight polyolefin,
An adhesive for hot melt or the like can be used. These are commercially available under the trade name Chemipearl (A type, M type, S type, V type, W type) (all manufactured by Mitsui Petrochemical Co., Ltd.) and under the trade name Aklift (Sumitomo Chemical Co., Ltd.).

In the press-contact heating step, the transfer-receiving member 5 is pressed against the surface of the substrate (photoreceptor) 1 on which the developer image 4 is formed using, for example, a pressure roller, and the entire surface is heated to be melted or softened. . That is, the developer is heated and melted to a temperature not lower than the melting point of the dispersion medium constituting the developer image 4, or is softened by heating to a temperature not exceeding the melting point and higher than room temperature.

Thereafter, in the former case (when heated to a temperature higher than the melting point and melted), the developer image 4 is cooled to return the temperature to a temperature lower than the melting point of the dispersion medium, and the transfer object 5 is peeled off. I do. The cooling may be natural cooling or may be performed by providing a cooling means. In addition, the cooling is preferably performed via the transfer target. On the other hand, in the latter case (when softened at a temperature not exceeding the melting point), the film may be peeled as it is, or may be peeled after the temperature is lowered by cooling.

Note that if the developer image 4 is not sufficiently solidified when the transfer member 5 is peeled off, the cohesive force will be insufficient and cohesive failure will occur, and the transfer rate will not reach 100%. It costs. Further, at the time of peeling, if the adhesive force between the substrate 1 and the developer image 4 is weakened by heating from the side of the substrate 1 as compared with the adhesive force between the transfer object 5 and the developer image 4, the transfer rate is further improved.

The exfoliated transfer object 5 is subjected to a heat treatment at a temperature higher than the press-contact heating temperature irrespective of the upper limit of the temperature determined by the heat resistance of the base 1, unless it is particularly unnecessary due to the press-contact heating conditions and the like. It is possible to increase the bonding force of the recorded image to the transfer object 5, and to improve the wear resistance. Although little heat can be applied to the substrate 1, which is a photoreceptor, heat can be freely applied to the transferred body 5 after peeling, and the heat treatment step can be performed freely. . The heat treatment temperature in the heat treatment step is arbitrary, but is preferably not less than the pressure heating temperature or, if a resin layer is formed on the transfer object, not less than the softening point of the resin layer. Further, when the heat treatment step is not required due to the pressure heating condition or the like, the apparatus can be downsized.

On the other hand, the residual solidified developer on the surface of the substrate 1 in the cleaning step is removed, and the substrate 1 is subjected to a series of steps starting from the charging step again.

The above is the basic process in the image recording method of the present invention. Next, a specific example of an apparatus for carrying out the method of the present invention will be described. FIG. 5 corresponds to a monochrome laser printer, which forms an image made of the above-mentioned solidified developer on the photosensitive drum 11 and transfers it to the recording paper 12.

Accordingly, around the photosensitive drum 11, a cleaning roller 13, a corona charger 14 for charging, a light source for exposing with a laser beam hν, and a developing unit 15 made of solidified developer are arranged in advance. An image composed of a solidified developer is formed on the photosensitive drum 11.

The recording paper 12 is pressed against the photosensitive drum 11 by the heat roller 16, and at this portion, the image formed of the solidified developer on the photosensitive drum 11 is melted or softened. Thereafter, the recording paper 12 travels along the photosensitive drum 11 for a while. During this time, the solidified developer image is cooled and solidified, and is transferred onto the recording paper 12 when the recording paper 12 is separated from the photosensitive drum 11. Is done.

FIG. 6 shows an example of an apparatus using a photosensitive belt 21 instead of the photosensitive drum 11. In this example, the annular photoreceptor belt 21 is
2, 23, and 24, the surface of which is sequentially charged, exposed, and developed by a corona charger 25, a light source for exposing with laser light hν, and a developing unit 26 using solidified developer. The formed developer image is also transferred onto the recording paper 28 by the heat roller 27. After the completion of the transfer, light is irradiated by the charge removing lamp, the remaining toner is removed by the cleaning blade 29, and the process proceeds to the charging step again.

In this embodiment, since the period in which the recording paper 28 and the photosensitive belt 21 are in contact with each other and run is long, the heat roller 2
7, the molten and softened developer image can be sufficiently cooled and solidified, and reliable transfer is possible.

When a color printer is used, as shown in FIG. 7, instead of the developing unit 15 in the apparatus shown in FIG. 5, yellow (Y), magenta (M), cyan (C), and further, The black (K) color developing units 31, 32, 33, and 34 are accordingly
Should be placed around the. The same applies to an apparatus using a photosensitive belt, and as shown in FIG.
6, instead of Y, M, C, and K color developing units 41,
What is necessary is just to arrange | position sequentially 42,43,44 along the running direction of the photoreceptor belt 21. FIG.

In the case of a color printer, Y,
M, C, K color superimposition and batch transfer
There is a method of transferring the M, C, and K images each time and superimposing the images on recording paper, and any of them may be adopted.

[0040]

In the present invention, the image is formed by a wet development method using a solidified developer. Therefore, a gradation is obtained and the resolution is secured. Further, the recording energy for forming an image can be on the order of 10 ⁻⁶ J / cm ² . On the other hand, the formed solidified developer image is formed by press-contact heating at a temperature higher than the melting point at which the dispersion medium melts or at a temperature at which the dispersion medium is softened, and almost 100% of the toner image is transferred onto the transfer-receiving body. . Further, since the transfer is performed collectively without using a thermal head or the like, the transfer speed is very high. Further, at the time of peeling, if the adhesive force between the substrate and the developer image is made weaker than the adhesive force between the substrate and the developer image by heating from the substrate side, the transfer rate is further improved.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below in detail with reference to the drawings.

First, FIG. 9 shows the configuration of the printer used in the experiment. This printer has a printer body 6 which is an outer casing.
6, a charging exposure unit including a photoreceptor belt 54, a charging charger 55, a laser optical system 56, and the like, a developing device 57, a transfer unit, and the like are built therein. The printer body 66
The sheet cassette 71 is removably loaded in the printer, and the developer image is recorded on the transfer sheet 52 set in the sheet cassette 71.

The photoreceptor belt 54 is stretched between various rollers described later and runs clockwise in the drawing. Then, around the photoreceptor belt 54, charging → exposure →
Charger 55, laser optical system 56, developing device 57, pressure contact mechanism 58, separation device 59, static elimination lamp 7 for repeatedly performing development → transfer → separation → discharge → cleaning
2. A cleaning device 62 is provided.

The developing device 57 has a solidified developer 67 which repeats melting and solidification by heating and cooling as described above.
The developer 67 is melted by heating, and the electrostatic latent image on the photoreceptor belt 54 is developed as in the case of wet development using a liquid developer.

A heater 73 for heating the photoreceptor belt 54 is provided at a position on the back side of the photoreceptor belt 54 opposite to the charger 55, the laser optical system 56, and the developing device 57. I have. Further, a cooling plate 6 is provided at the exit side of the developing device 57 as necessary.
5 (or a cooling means such as a cooling roller or a cooling fan) is provided.

In this embodiment, the photoreceptor belt is used instead of the photoreceptor drum because the latter has a smaller heat capacity and has a higher sensitivity to temperature when performing a cooling / heating process.

On the other hand, the pressing mechanism 58 is
8a and a pressure roller 58b. The pressure roller 58a and the pressure roller 58b
It is configured so as to sandwich it. Among these rollers, the pressing roller 58b also serves as a guide roller for the photosensitive belt 54, and the pressing roller 58a plays a role of superimposing the transfer sheet 52 on the developed photosensitive belt 54. However, if the pressing by the transfer sheet 52 itself is sufficient, the pressure roller 58a can be omitted.

Further, from the photosensitive belt 54 to the transfer sheet 5
A peeling roller 68 is provided at a position where the belt 2 is peeled off so as to be in contact with the back side of the photoreceptor belt 54. The peeling roller 68 functions as a guide roller and changes the traveling direction of the photoreceptor belt 54. A cooling plate 69 is provided at a position facing the peeling roller 68 so as to be in contact with the back side of the transfer sheet 52, and the photosensitive belt 54 can be heated by the peeling roller 68 if necessary. To cool the transfer sheet 52.

A separation device 59 such as a separation claw is disposed near the separation roller 68 so as to separate the transfer sheet 52 from the photosensitive belt 54. In the case where the transfer sheet 52 is separated by curvature separation on the separation roller 68, the separation device 59 is used.
Is unnecessary.

A guide plate 74, a fixing device 70 and, if necessary, a discharge section 61 are arranged in the traveling direction of the separated transfer sheet 52 so that the transfer sheet 52 can be discharged smoothly. . The fixing device 70 provided in front of the discharge unit 61 is composed of a heat roll, a heat oven, or the like, and has a structure capable of heating the transfer sheet 52 after transfer and fixing the visible image. .

In the printer having the above-described structure, when heating the roller, a roller with a built-in heater is used.

In the above-described printer, an electrostatic latent image is formed on the photoreceptor belt 54, and is developed using the developer 67. That is, the photoreceptor belt 54 is driven to rotate clockwise in the drawing, the surface of the photoreceptor belt 54 is charged by the charging charger 55, and then the laser beam from the laser optical system 56 is irradiated to form an electrostatic latent image. This electrostatic latent image is visualized by the developer 67 when passing through the developing device 57.

Thereafter, if necessary, the photosensitive belt 54
The temperature of the developer image 80 is made lower than the melting point of the dispersion medium by a cooling plate 65 (or a cooling roll or a cooling fan) provided inside to make a solid state.

On the other hand, a transfer sheet 52 is fed from a paper feeder 51 in the direction of the arrow in the figure, and is conveyed to a latent image carrier consisting of a photoreceptor belt 54 at a timing by a registration roller 53. Then, the visible image (developer image 80) composed of the developer 67 is transferred to the transfer sheet 52 conveyed to the photoreceptor belt 54 by the pressure contact device 58 and the separation / separation device 59. The transfer sheet 52 that is in close contact with the sheet is mechanically separated.

In the transfer, the photosensitive belt 54 is conveyed to the transfer roll pair 58 entrance while holding the developed image,
The transfer sheet 52 is brought into close contact with the transfer sheet 52 at a proper timing, and is pressed and heated (press-contact heating) between the transfer roller pair 58. As described above, the pressure contact mechanism 58 is configured to sandwich the photoreceptor belt 54 between the pressure roller 58a and the pressure roller 58b. As shown in FIGS. The developer image 80 is melted or softened by the heating of the pressing roller 58a and the pressing roller 58b, and the transfer is performed on the transfer sheet 52.

After the pressing by the pressing mechanism 58, the photosensitive belt 54 and the transfer sheet 52 are conveyed in a state of close contact, and are separated on the separating roller 68 by a separating device 59 such as a curvature separating or separating claw. At the time of peeling, the peeling roller 68 is heated to heat the photoreceptor belt 54 from the back, and at the same time, the transfer sheet 52 is cooled from the back side by the cooling plate 69, so that the visible image is easily peeled from the photoreceptor belt 54. You may do so.

Thereafter, the transfer sheet 52 is transferred to the fixing device 70.
Then, the visible image on the transfer sheet 52 is fixed by the fixing device 70, and is discharged to the discharge unit 61 in the direction of the arrow in FIG. On the other hand, the residual developer is removed from the photosensitive belt 54 after the transfer of the visible image by the cleaning device 62 having the cleaning blade, and the removed developer 67 is collected by the cleaning device 62.

FIG. 11 shows an image forming method process in the apparatus of this embodiment, in which the photosensitive belt 54, the developer image 80,
Sheet material 52a and surface resin layer 52b of transfer sheet 52
It was shown as a state. First, before the transfer, as shown in FIG. 11A, the developer image 80 on the photoreceptor belt 54 and the surface resin layer 52b of the transfer sheet 52 are naturally understood.
(Thickness: 0.01 to 0.08 mm).

Next, pressure and heat are applied in the transfer process, and the developer image 80 and the surface resin layer 52b are brought into contact. At this time, as shown in FIG. 11B, a transfer state in which the contacting parts stick with each other depending on the heating temperature (hereinafter, a process transferred through such a state is referred to as adhesion transfer), or FIG. 11C. As shown in (1), a compatible state in which they are mutually melted (hereinafter, a process of transferring through such a state is referred to as absorption transfer).

In the peeling process, the temperature of the developer image 80 is lowered from the temperature at the time of transfer (adhesive force between the photosensitive belt and the developer) <(adhesive force between the surface resin layer and the developer) < As shown in FIG. 11D or E, the developer image 80 is separated from the photoreceptor belt 54 and transferred to the transfer sheet 52 side as shown in FIG. 11D or E.

Finally, if necessary, in the fixing process, the developer image 80 and the surface resin layer 52b are heated to the softening point temperature of the surface resin layer 52b, and as shown in FIG. The hardness is substantially equal to the hardness of the purpose layer 52b. As described above, the transfer process can be performed while maintaining the developed state, which is a gradation image and a high-resolution image, and the transfer rate can be made almost 100%.

Then, the transfer process was actually performed under various temperature conditions using the above-described printer. The melting point of the dispersion medium of the developer used was determined from the peak of the endothermic reaction in the differential scanning calorimetry (DSC) shown in FIG. For example, the DSC chart of the wax (trade name: sp0110, manufactured by Nippon Seiro Co., Ltd.) used in the following experiment is as shown in FIG. 13, and the melting point is 46 ° C.

In the transfer, those having no resin layer on the surface were used. The softening point of the resin layer was determined according to the Vicat softening temperature test method for thermoplastics specified in Japanese Industrial Standard JIS K7206. It was measured. Table 1 shows the types of the transfer process, and Table 2 shows the transfer process and the temperature conditions in each example. Regarding the transfer process, regardless of the presence or absence of the surface resin layer of the transfer sheet, for convenience, the case where heating is performed at a temperature equal to or higher than the melting point of the developer is referred to as absorption transfer (melting), and the case where heating is performed at a temperature lower than the melting point is performed as adhesion transfer ( Softening). Table 2 also shows the effect of each embodiment.

[0064]

[Table 1]

[0065]

[Table 2]

The specific embodiments to which the present invention is applied have been described above, but it goes without saying that the present invention is not limited to these embodiments.

[0067]

As is clear from the above description, in the present invention, an image is formed in advance by developing a solidified developer, and this is transferred onto a recording paper by pressure transfer. Thus, it is possible to obtain a gradation in a recorded image, and to obtain a resolution far exceeding the case where a thermal head is used. In addition, the transfer rate can be set to almost 100%, and sufficient durability can be ensured.

In the present invention, the recording energy required for image formation is extremely small, on the order of 10 ⁻⁶ J / cm ² , and the recording speed is extremely high because a thermal head is not used. Further, since ink (toner) is used only for a necessary portion of an image, the ink is not consumed wastefully, which is advantageous in terms of running cost and environmental protection. Further, at the time of peeling, the transfer rate can be further improved by heating from the substrate side to make the adhesive force between the substrate and the developer image weaker than the adhesive force between the transfer-receiving body and the developer image.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a charging step.

FIG. 2 is a schematic view showing an exposure step.

FIG. 3 is a schematic view illustrating a developing step.

FIG. 4 is a schematic view showing a transfer step.

FIG. 5 is a schematic diagram illustrating a configuration example of a monochrome printer using a photosensitive drum.

FIG. 6 is a schematic diagram illustrating a configuration example of a monochrome printer using a photosensitive belt.

FIG. 7 is a schematic diagram illustrating a configuration example of a color printer using a photosensitive drum.

FIG. 8 is a schematic diagram illustrating a configuration example of a color printer using a photosensitive belt.

FIG. 9 is a schematic diagram illustrating a configuration of a printer used in the embodiment.

FIG. 10 is a schematic cross-sectional view of a main part showing a state in which a photosensitive belt and a transfer sheet are pressed against each other.

FIG. 11 is a schematic cross-sectional view schematically showing a state of a developer and a surface resin layer in a transfer process.

FIG. 12 is a characteristic diagram showing a typical example of a DSC curve obtained by differential scanning calorimetry.

FIG. 13 is a characteristic diagram showing a DSC curve of wax actually used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 4 ... Developer image 5 ... Transfer receiving body 21 ... Photoreceptor belt

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akira Shirakura 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Yuji 6-35 Kita-Shinagawa, Shinagawa-ku, Tokyo 7-35 Inside Sony Corporation (72) Inventor Yuichiro Ikemoto 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Sony Corporation Inside (72) Inventor Tosumi Fukuoka 6-35-35 Kita Shinagawa, Shinagawa-ku, Tokyo Sony Incorporated (72) Inventor Ando Hisashi 18 Satsuki-cho, Kanuma-shi, Tochigi Sony Chemical Co., Ltd.Kanuma Plant (72) Inventor Koichi Kawasado 6-35 Kita Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (72 ) Inventor Hiroshi Tokunaga 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (56) References JP-A-2-81073 (JP, A) JP-A 4-264476 (JP, ) (58) investigated the field (Int.Cl. ^7, DB name) G03G 15/16

Claims (7)

(57) [Claims] 1. A method for forming an electrostatic latent image on a substrate, comprising dispersing the electrostatic latent image in a dispersion medium which is solid at ordinary temperature and which reversibly repeats solidification by melting and cooling by heating above its melting point. After forming a developer image composed of the colorant particles and the dispersion medium on the surface of the substrate by performing development using a solidified developer that is dispersed, the substrate and the transfer receiving body are pressed and heated, and the pressure heating temperature is set to the above-described range. After melting the dispersion medium to a temperature equal to or higher than the melting point of the dispersion medium and then cooling the dispersion medium to a temperature equal to or lower than the melting point, the dispersion medium is re-applied from the back side of the substrate.
An image recording method, comprising: transferring an image of a developer on a surface of a substrate to a member to be transferred by heating to separate the member from the substrate by heating ; 2. An electrostatic latent image is formed on a substrate, and the colorant particles are dispersed in a dispersion medium which is solid at ordinary temperature and which reversibly solidifies by melting and cooling by heating exceeding a melting point. After forming a developer image composed of the colorant particles and the dispersion medium on the surface of the substrate by performing development using a solidified developer that is dispersed, the substrate and the transfer-receiving member are pressed and heated, and the pressure heating temperature is increased. Softening the dispersion medium so as not to exceed the melting point of the dispersion medium, and subsequently transferring the developer image on the substrate surface to the transfer object by peeling the transfer object from the substrate, and recording the image. Image recording method. 3. The image recording method according to claim 1, wherein the substrate is a belt-shaped substrate. 4. The image recording method according to claim 2 , wherein when the transfer object is separated from the substrate, heating is performed from the back side of the substrate. 5. The image recording method according to claim 1, wherein, after the transfer object is separated from the substrate, the transfer object is subjected to a heat treatment at a temperature equal to or higher than a pressing temperature. 6. The image recording method according to claim 1, wherein the surface of the transfer object is made of a resin compatible with the dispersion medium. 7. The image recording method according to claim 6, wherein after the transfer object is separated from the substrate, the transfer object is heat-treated at a temperature equal to or higher than the softening point of the resin on the transfer object surface.