WO1993007542A1

WO1993007542A1 - Image recording method

Info

Publication number: WO1993007542A1
Application number: PCT/JP1992/001282
Authority: WO
Inventors: Hiroshi Tokunaga; Akira Shirakura; Hideki Matsuzaka; Yuichirou Ikemoto; Toshimi Fukuoka; Takaki Mori; Norikazu Iwasaki; Yuji Yakura; Hisashi Andoh; Koichi Kawasumi
Original assignee: Sony Corporation
Priority date: 1991-10-03
Filing date: 1992-10-02
Publication date: 1993-04-15
Also published as: DE69220031T2; EP0560990B1; EP0560990A1; EP0560990A4; DE69220031D1

Abstract

An electrostatic latent image is formed on a substrate (photosensitive member) by a Carlson process, etc, and is developed by a solid developing agent prepared by dispersing colorant particles in a dispersion medium which remains solid at normal temperature and repeats reversibly change phases above and below its melting point. Then, the substrate and a transfer member are brought into pressure contact and heated, and this pressure contact heating temperature is raised above the melting point of the dispersion medium to melt the latter. Subsequently, the dispersion medium is cooled to a temperature below the melting point and the transfer member is peeled to transfer the developed image to the transfer member. Alternatively, the pressure contact heating temperature is set to a temperature not exceeding the melting point to soften the dispersion medium, and then the transfer member is peeled to transfer the developed image to the latter. A resin layer having compatibility with the dispersion medium of the developing agent is formed on the surface of recording paper.

Description

Technical Field The present invention relates to an image recording method for performing printing or image printing based on an image signal. BACKGROUND ART For example, various printing methods have been proposed for printers of computers and word processors, and thermal transfer / recording methods have also been proposed.

This thermal transfer recording method uses a thermal transfer ribbon having a heat-meltable ink as an ink layer. The transfer principle is as follows.

First, a thermal transfer ribbon coated with a hot-melt ink solid at room temperature on a substrate is brought into close contact with the transfer paper by the pressing force of a thermal head. At this time, the heat-meltable ink that is solid at room temperature is softened and melted by the heat of the thermal head. Then, when the thermal transfer ribbon is peeled off from the transfer receiving body when the ink returns to a solid state, the heat-fusible ink of the softened and melted portion is transferred onto the transfer receiving paper, and the print or the like is printed on the transfer receiving paper. Not formed.

By the way, the above-described thermal transfer recording method can simplify the apparatus configuration, and is extremely difficult to provide a small and low-cost printer apparatus. However, it has the following disadvantages.

First, in the thermal transfer recording method, only binary recording can be performed, and gradation cannot be output. This is not a problem when printing only, but is a major obstacle when forming images.

In addition, the recording energy is as large as 4 to 6 JZ cm ² and the speed is slow. Furthermore, the pixel density is limited. (The current technology limits the pixel density of the thermal head to about 300 dpi.) In addition, there are many problems in terms of running costs, environmental protection, and the like. 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 heat transfer ribbon cannot be reused. Therefore, the force that causes most ink to be discarded ^ This increases running costs and may lead to environmental damage.

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

However, in the image formation by the wet development method using the solidified developer, there is a problem that image transfer is difficult.

For example, the applicant of the present application has previously described in Japanese Patent Application Laid-Open No. 2-81073 a method in which a colorant (or toner) and a dispersion medium on a substrate (for example, a photoreceptor) are dispersed. It proposes a method in which the developer image is heated and transferred in a molten state by contacting the transfer object, or a method in which the developer image is pressed against the transfer object during cooling and solidification.

However, if the transferred image is brought into contact with a substrate (for example, a photoreceptor) and pulled off while the developer image is in a molten state, the image may be disturbed, uniform transfer is difficult, and unevenness is often observed. . Also, if 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 also significantly deteriorated. Further, there is a problem that the recorded image transferred to the transfer object lacks abrasion resistance.

As described above, the lack of gradation and the lack of resolution in the thermal transfer recording system are also caused by the wet development system using a solidified developer. Durability has become a major issue, and its solution is awaited.

Therefore, an object of the present invention is to provide an image recording method which can obtain a gradation in a recorded image, obtain an image with high resolution, and have excellent transferability and excellent durability of the recorded image.

Another object of the present invention is to provide an image recording method that requires a small recording energy for image formation, does not waste ink, and has a very high recording speed. DISCLOSURE OF THE INVENTION In order to achieve the above object, the image recording method of the first invention of the present invention forms an electrostatic latent image on a substrate, and forms the electrostatic latent image as a solid at room temperature. Reversible solidification by melting and cooling by heating above the melting point After developing a developer image composed of the colorant particles and the dispersion medium on the surface of the substrate by developing using a solidified developer obtained by dispersing the colorant particles in the returning dispersion medium, the substrate and the transfer-receiving body are pressed against each other. The transfer medium is heated to a temperature equal to or higher than the melting point of the dispersion medium to melt the dispersion medium, and then the dispersion medium is cooled to a temperature below the melting point. The method is characterized in that an image is transferred to an object to be transferred and the image is recorded.

Further, the image recording method of the second invention of the present invention forms an electrostatic latent image on a substrate, and the electrostatic latent image is solid at room temperature and solidified by melting and cooling by heating above its melting point. After forming a developer image consisting of the colorant particles and the dispersion medium on the surface of the substrate by developing using a solidified developer in which the colorant particles are dispersed in a reversibly repeating dispersion medium, 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 medium is peeled from the base to transfer the developer image on the surface of the base. It is characterized in that it is transferred to the body and an image is recorded.

In the present invention, the image is formed by a wet development method using a solidified developer. Therefore, it is possible to obtain a gradation in the recorded image, and it is possible to obtain a resolution far exceeding the case where the thermal head is used. Further, the recording energy for forming a plane image can be on the order of 1 O-s JZ cm ² .

On the other hand, the solidified developer image thus formed is heated by press-contact at a temperature higher than the melting point of the dispersion medium or at a temperature at which the dispersion medium is softened, and the toner image is transferred onto the transfer object by approximately 100%. Is done. Also, since the transfer is performed collectively without using a thermal head or the like, High speed and sufficient durability.

In addition, since ink (toner) is used only for the necessary parts of the image, there is no waste of ink, which is advantageous in terms of running costs and environmental protection. FIG. 1 is a schematic diagram showing a charging process.

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

FIG. 3 is a schematic diagram showing the developing process.

FIG. 4 is a schematic diagram showing the transfer step.

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

FIG. 6 is a schematic diagram showing a configuration example of a monochromatic printer using a photoreceptor belt.

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

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

Fig. 9 is a schematic diagram showing the configuration of the printer used in the examples.

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

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

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 a box actually used. O Best Mode for Carrying Out the Invention The image forming process of the present invention comprises a charging step, an exposing step, a developing step, a pressure heating step, and a separating step. Further, the transferred object is converted into a recorded image through a heat treatment step, if necessary, while the substrate (photoreceptor) is used again in the image forming process after a cleaning step. -The above charging step and exposure step are the same as in the case of ordinary Carlson method electrophotography. That is, first, as shown in FIG. 1, a photosensitive member I 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, a known organic photoconductor or inorganic photoconductor can be used for the photosensitive layer 3 of the photoconductor 1. For example, organic photoconductors can be selected from a wide range of well-known substances, and practically used materials include poly (N-vinylcarbabul) and 2,4,7-trinitrofluorene-1-one. An electrophotographic photosensitive substrate consisting of: an organic pigment obtained by sensitizing poly (N-vinylcarbazole) with a pyrimine salt-based dye and a poly (N-vinylcarbazole) sensitized with a cyanine-based dye Examples thereof include an electrophotographic photosensitive substrate having a main component, and an electrophotographic photosensitive substrate mainly having a eutectic complex composed of a dye and a resin. Inorganic photoconductors include zinc oxide, zinc sulfide, sulfur dioxide, selenium, Selenium-tellurium alloys, selenium-arsenic alloys, selenium-tellurium-arsenic alloys, amorphous gay materials, and the like.

Then, in the next exposure step, selective light irradiation corresponding to the image information is performed using an appropriate exposure means such as a semiconductor infrared laser light source, and the negative charge of the exposed portion is reduced as shown in FIG. It disappears 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 dion 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, and as shown in FIG. 3, a developer containing colorant particles in accordance with the electrostatic latent image Image 4 is formed.

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 the 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, more preferably 40 ° C. or higher, in consideration of a normal use environment and handleability. Although the upper limit of the melting point is not particularly limited, it is practically about 100 ° C, more preferably 80 ° C or less. This means that extra energy is consumed for heating even if the melting point is too high, and that the temperature exceeds the heat resistance temperature of the material commonly used as a support when used on a support while it is used. This is in consideration of things that must not be done.

Materials for the dispersion medium satisfying these requirements include paraffins and Class I, and mixtures thereof. First, as paraffins, there are various normal paraffins having 19 to 60 carbon atoms ranging from nonadecane to hexacontan. Examples of the waxes include vegetable waxes such as carnauba wax and cotton wax, animal waxes such as miwa wax, ozokerite, and petroleum waxes 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.

Furthermore, homopolymers or copolymers of polyacrylates such as polyethylene, polyacrylamide, poly-η-stearyl acrylate, poly-η-stearyl methacrylate (for example, copolymer η-stearyl acrylate-ethyl methacrylate, etc.) Although a crystalline polymer having a long alkyl group in the chain can be used, the above-mentioned paraffins and waxes are preferable in consideration of the degree of distortion at the time of heating. As the colorant particles, conventionally known inorganic pigments, organic 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. Organic pigments and dyes include Hansa Yellow (1.1680), Benzidine Yellow G (C. 21090), Benzidine Orange (1.2110), Fast Strand (C-. 1.37085), and Brisbane. Lianto Carmine 3 B (C. 1.16015-Lake), Phthalocyanine Blue (1.74160), Victoriaable (C. 1.42595-Lake), Spirit Black (I. 50415), Oil Lou (1.74305), Alkali Blue (I. 42770A), Fast Tosslet (1.112315), Rhodamin 6B (I. 45160), Rhodamin Rake (I. 45160-Lake) , Fast Sky Blue (C. 1.720400-Lake), Nigguchi Shin (C.I. 50415), carbon black, and the like. These can be used singly or as a mixture of two or more, and those having desired coloration 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, the chargeability of the colorant, and the like. 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, and a .Synthetic resins such as cryl resin, methacrylic resin, polyester resin, polycarbonate resin, polyvinyl acetate resin, rosin resin, hydrogenated rosin resin, and amaji oil modified alkyd resin Alkyd resins including modified alkyds, and natural resins such as polyterpenes. In addition, modified phenolic resins such as phenolic resins, phenolic formalin resins, phenolic erythritol phthalate, coumarone-indene resins, ester gum resins, vegetable oil polyamide resins, etc. Halogenated hydrocarbon polymers such as polyvinyl chloride, chlorinated polypropylene, etc .; synthetic rubbers such as vinyltoluene-butylene, butadiene-isoprene; 2-ethylhexylmethacrylate Polymers of acryl-based monomers having long-chain alkyl groups such as acrylate, lauryl methacrylate, stearyl methacrylate, lauryl acrylate, octyl acrylate, or other polymerizable monomers (Eg, styrene-laurylme) Tacrylate copolymers, acrylate-lauryl methacrylate copolymer, etc.), polyolefins such as polyethylene, polyterpenes, and the like can also be used.

Further, a charge-imparting agent is usually added to the above-mentioned developer, and the developer used here is no exception. The charge-providing agent used is, for example, a metal salt of a fatty acid such as naphthenic acid, octenoic acid, oleic acid, stearic acid, isostearic acid or carboxylic acid, a metal salt of sulfosuccinates, an oil. Metal salts of soluble sulfonic acid, metal salts of phosphoric acid esters, metal salts such as abietic acid, metal salts of aromatic carboxylic acids, and metal salts of aromatic sulfonic acids.

In order to improve the charge of the colorant particles (6), S i 〇 _{2, A 1 2 0 3,} T i 0 2, Z n _{_{〇, G a 2 0 3. I}} n 2 0 3, G e 〇 2, S n 0 _2, P b 〇 _2, the M g metal oxide particles, and mixtures thereof, such as 0 may be added as a charge enhancing additive.

After the developer image 4 is formed by the above-described developing process, the transfer-receiving member 5 is overlapped as shown in FIG. 4, and the transfer process is performed.

Here, as a 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. Examples include various types of paper such as natural paper and synthetic paper, cloth or nonwoven fabric made of vegetable fibers such as cotton and hemp, and animal fibers such as silk and wool, polyamides, polyesters, polyacetals, and polyurethanes. These include fabrics or nonwoven fabrics made of organic synthetic fibers, inorganic fibers such as ceramics and carbon, meshes of metals and organic polymers, and polymer foams such as polyurethane foam. To save the document in the form of a normal document, use a white paper as the transfer object from the viewpoint of enhancing visibility. It is preferable to use such as, but of course, the present invention is not limited to this. '

The transfer target 5 may have a resin layer compatible with the dispersion medium of the solidified developer formed on the surface thereof for the purpose of ensuring the adhesive force to the solidified developer. . 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-receiving member may be any resin as long as it is compatible with the dispersion medium. For example, thermoplastic elastomer, low-density polyolefin , Ionomer resin, vinyl acetate copolymerized polyolefin, low molecular weight polyolefin, hot melt adhesive, and the like. 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 trade name Acryft (manufactured by 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, for example, using a pressure roller or the like, and the entire surface is heated to melt or soften. That is, the developer is heated to a temperature equal to or higher than the melting point of the dispersion medium constituting the developer image 4 and melted, 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 equal to or higher than the melting point and melted), the developer image 4 is cooled to return the temperature to a temperature equal to or lower than the melting point of the dispersion medium, and the transfer medium 5 is separated. 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 object. On the other hand, in the latter case (temperature not exceeding the melting point) (If softened at the same time), the resin may be separated as it is, or may be separated after cooling to lower the temperature.

Note that if the developer image 4 is not sufficiently solidified when the transfer object 5 is separated, the cohesive force is insufficient and cohesive burst occurs, and the transfer rate does not reach 100%. It costs. In addition, if the adhesive force between the substrate 1 and the developer image 4 is weakened by heating from the side of the substrate 1 at the time of separation, compared with the adhesive force between the transfer-receiving body 5 and the developer image 4, the transfer rate is further improved. .

Also, the separated transferred object 5 is subjected to heat treatment at a temperature higher than the pressure heating temperature irrespective of the upper limit of the temperature determined by the heat resistance of the substrate 1, except when it is not particularly necessary due to the pressure heating condition or the like. The bonding force of the image to the object to be transferred 5 can be increased, and the wear resistance can be improved. It is not possible to apply much heat to the substrate 1 which is a photoreceptor, but it is possible to freely apply heat to the transfer receiving member 5 after separation, and the ripening process can be performed freely. Is possible. The heat treatment temperature in the heat treatment step is arbitrary, but it is preferable that the heat treatment temperature be equal to or higher than the pressure heating temperature or equal to or higher than the softening point of the resin layer when the resin layer is formed on the transfer object. . If the heat treatment step is not required due to the pressure heating condition, the apparatus can be made compact, while the residual solidified developer on the surface of the substrate 1 is removed in the cleaning step. , Again subjected to a series of processes starting from the charging process

Ό ο

The above is the basic process in the image recording method of the present invention. Next, a specific example of an apparatus for performing the method of the present invention will be described.

Figure 5 shows the equivalent of a monochrome laser printer. An image composed of the solidified developer described above is formed on the ram 11 and is transferred onto a recording paper 12.

Therefore, a cleaning roller 13, a corona charger 14 for charging, a light source for exposing with a laser beam hV, a developing unit 15 using solidified developer are provided around the photosensitive drum 11. Are arranged so that an image composed of the solidified developer is formed on the photosensitive drum 11 in advance.

The recording paper 12 is pressed against the photoconductor drum 11 by the roller 16, and the image formed of the solidified developer on the photoconductor drum 11 is melted or softened at the portion of the recording paper 12. After that, the recording paper 12 travels along the photosensitive drum 11 for a while, or the solidified developer image is cooled and solidified during this time, and when the recording paper 12 separates from the photosensitive drum 11, recording is performed. Transferred to paper 12

FIG. 6 shows an example of an apparatus using a photosensitive belt 21 instead of the photosensitive drum 11.

In this example, an annular photoreceptor belt 21 is circulated through guide rolls 22, 23 and 24, and the surface thereof is exposed to a corona charger 25 and a laser beam h. Charge, exposure, and development are sequentially performed by a light source and a developing unit 26 using a solidified developer, and the formed developer image is also transferred onto a recording paper 28 by a heat roller 27. After the completion of the transfer, light is emitted from the neutralization lamp, the remaining toner is removed by the cleaning blade 29, and the process is again shifted to the charging step.

In this example, since the recording paper 28 and the photoreceptor belt 21 are in contact with each other for a long period of time, the development roller melted and softened by the heat roller 27 is used. The agent image can be cooled and solidified sufficiently, 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), yellow (M), cyan (C), and The black (K) color developing units 33, 32, 33, and 34 may be arranged around the photosensitive drum 11 as needed. The same applies to an apparatus using a photoreceptor belt. As shown in FIG. 8, instead of the development unit 26, each of the Y, M, C, and K color development units 41, 42, 43, and 4 is used. 4 may be sequentially arranged along the running direction of the photoreceptor belt 21.

In the case of color printing, a method in which Y, M, C, and K colors are superimposed on the photoreceptor and transferred collectively, and Υ, Μ, C, and Κ images are transferred each time and color superimposed on recording paper There is a method to do this, and either may be adopted.

Hereinafter, specific examples to which the present invention is applied will be described in detail with reference to the drawings.

First, Fig. 9 shows the configuration of the printer used in the experiment. In the printer, a charging unit including a photosensitive belt 54, a charging charger 55, a laser optical system 56, a developing unit 57, a transfer unit, etc. It is built in.

A paper cassette 1 is detachably mounted on the printer body 66, and a developer image is recorded on a transfer sheet 52 set in the paper cassette 71. Will be.

The photoreceptor belt 54 is stretched between various rollers described later, and runs clockwise in the drawing. Around the photoreceptor belt 54, a charging charger 55, a laser optical system 56, and a developing device for repeatedly performing charging—exposure → development → transfer—separation → discharge → cleaning are repeated. A device 57, a pressure contact mechanism 58, a separation device 59, a static elimination lamp 72, and a cleaning device 62 are provided.

The developing device 57 is supplied with a solidified developer 67 that repeats melting and solidification by heating and cooling as described above, and the developer 67 is melted by heating to form a liquid developer. The electrostatic latent image on the photoreceptor belt 54 is developed in the same manner as in the case of the wet development using the photoconductor.

Further, of the photoreceptor belt 54, a position on the back side facing the charging charger 55, the laser optical system 56 and the developing device 57 is provided for heating the photoreceptor belt 54. There are 7 days a week. Further, a cooling plate 65 (or a cooling means such as a cooling roller or a cooling fan) is provided at the outlet side position of the developing device 57 as needed.

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

On the other hand, the pressing mechanism 58 includes a pressing roller 58a and a pressing roller 58b. The pressing roller 58a and the pressing roller 58b sandwich the photosensitive belt 54. Is configured. Among these rollers, the pressing roller 58 b also serves as a guide roller for the photosensitive belt 54, and the pressing roller 58 a serves as the photosensitive belt 5 on which the transfer sheet 52 has been developed. Plays a role of superimposing 4. However, when the transfer sheet 52 itself is sufficiently pressed, the pressure roller 58a can be omitted.

Also, at a position where the transfer sheet 52 is separated from the photoreceptor belt 54, the separation roller 68 is set so as to be in contact with the back side of the photoreceptor belt 54. Then, the separation roller 68 functions as a guide roller, and the traveling direction of the photoreceptor belt 54 is changed. At a position facing the peeling roller 68, a cooling plate 69 is provided so as to be in contact with the back side of the transfer sheet 52, and the photoreceptor belt 54 is separated by the separating roller 68 as necessary. The transfer sheet 52 is configured to be heated or cooled by the cooling plate 69.

A separation device 59 such as a separation claw is provided near the separation roller 68 so as to separate the transfer sheet 52 from the photoreceptor belt 54. When the transfer sheet 52 is separated by separating the curvature on the separation roller 68, the separation device 59 is unnecessary. -A guide plate 74, a fixing device 70, and a discharge unit 61 as necessary are arranged in the traveling direction of the transferred transfer sheet 52, and the transfer sheet 52 is provided.

52 is designed to 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 fixing the visible image by heating the transfer sheet 52 after transfer. It has been.

When the roller is heated in the printer having the above-described structure, a roller or the like 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 figure, the surface 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. . When the electrostatic latent image passes through the developing device 57, the developer

Visualized by 6 7 Thereafter, if necessary, the temperature of the developer image 80 is lowered from the melting point of the dispersion medium by a cooling plate 65 (or a cooling roll or a cooling fan) provided inside the photoreceptor belt 54. Bring to solid state.

On the other hand, the transfer sheet 52 is fed from the sheet feeding device 51 in the direction of the arrow in the figure, and the registration roller 53 captures the evening image and conveys it to the latent image carrier including the photosensitive belt 54. . 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 pressing device 58 and the separation / separation device 59. Then, the transfer sheet 52 closely attached to the photoreceptor belt 54 is mechanically separated.

In the transfer, the photoreceptor belt 54 is transported to the entrance of the transfer roll pair 58 while holding the developed image, and the transfer sheet 52 is brought into close contact with the transfer sheet 52 so that the transfer sheet 52 is brought into close contact therewith. It is performed by pressing and heating (press-contact heating).

As described above, the pressing mechanism 58 is configured so that the photosensitive belt 54 is sandwiched between the pressing roller 58a and the pressing roller 58b, as shown in FIGS. 10A and 10B. As described above, the developer image 80 is melted or softened by the heating of the pressure roller 58 a and the press contact roller 58 b, and the transfer is performed on the transfer sheet 52.

After pressing by the pressing mechanism 58, the photoreceptor belt 54 and the transfer sheet 52 are conveyed in a state of being in close contact with each other, and are separated by a separation device 59 such as a curvature separation or separation claw on the separation roller 68. Separation takes place. At the time of separation, the separation 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 exposed. To make it easier to separate from body belt 54 It may be.

Thereafter, the transfer sheet 52 is conveyed to a fixing device 70, where the visible image on the transfer sheet 52 is fixed by the fixing device 70, and is discharged to a discharge unit 61 in the direction of the arrow in the figure.

On the other hand, the residual developer is removed from the photoreceptor belt 54 after the transfer of the visible image by a cleaning device 62 having a cleaning blade, and the removed developer 67 is a tallying device 6. Collected in 2.

FIG. 11 shows an image forming method process in the apparatus of the present embodiment in which the photosensitive member 54, the developer image 80, the sheet material 52a of the transfer sheet 52 and the surface resin layer 52b are formed. It was shown as a state.

First, before transfer, naturally, as shown in FIG. 11A, the developer surface image 80 on the photoreceptor belt 54 and the surface resin layer 52 b (thickness) of the transfer sheet 52 (0.1 to 0.08 mm).

Next, pressure and heating are performed in the transfer process, and the developer image 80 is brought into contact with the surface resin layer 52b. At this time, as shown in FIG. 11B, the transfer state in which the contacting portions adhere to each other with viscosity due to the heating temperature (hereinafter, the process of transferring through such a state is referred to as attachment transfer). Alternatively, as shown in FIG. 11C, the molten state is fused to each other (hereinafter, the process of transferring through such a state is referred to as absorption transfer).

Then, in the separation process, the temperature of the developer surface image 80 is lowered from the temperature at the time of transfer (adhesive force between the photoreceptor 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 transferred to the photoreceptor belt. Transfer the sheet to the transfer sheet 52 side by separating it cleanly from 5 4.

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 52, and as shown in Fig. The strength is made almost equal to the hardness of the surface purpose layer 52.

As described above, the transfer process can be performed while maintaining the developed state of a gradation image and an image with good resolution, and the transfer rate can be made approximately 100%.

Then, the transfer process was actually performed using the above-mentioned printer under various temperature conditions. 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 wax chart (spO110, manufactured by Nippon Seimitsu Co., Ltd.) used in the following experiment has a DSC chart as shown in FIG. 13 and a melting point of 46 ° C.

For the transfer, those with and without a resin layer on the surface were used, but the softening point of the resin layer was determined by the plastic viscosity of thermoplastics specified in Japanese Industrial Standard JISK 720. The softening temperature was measured according to the test method.

Table 1 shows the type of transfer process, and Table 2 shows the transfer process and temperature conditions in each example. In the transfer process, regardless of the presence or absence of the surface resin layer on the transfer sheet, for convenience, the case of heating to a temperature higher than the melting point of the developer is referred to as absorption transfer (melting) and the case of heating to a temperature lower than the melting point. Was regarded as adhesion transfer (softening). Table 2 also shows the effects of each example. Table 1 Materials

Process transfer process process

Developer

A Absorption transfer None

(Sleep

B None

Simultaneous transcription (softening)

No process

C Absorption transfer

(Melt 10 softening point T s

D Appendix Photo Resin material

(Softening) Melting Tm Softening point T s

E Absorption transfer None

(Flat

F with and without photo

Transfer process (softening) Available

Ten meters

G Fixing process Absorption transfer

(Leakage Tm Softening point T s

H Fiber

(Softening), Tm softening point T s

Table 2

Claims

The scope of the claims

1. An electrostatic latent image is formed on a substrate, and the colorant particles are dispersed in a dispersion medium which is a solid at room temperature and which reversibly repeats solidification by melting and cooling by heating above the melting point. After forming a developer surface image composed of the colorant particles and the dispersion medium on the surface of the substrate by developing using a solidified developer, the substrate and the transfer-receiving body are pressed and heated, and the pressure heating temperature is adjusted to the dispersion value. The dispersion medium is melted at a temperature equal to or higher than the melting point of the medium, and then the dispersion medium is cooled to a temperature lower than the melting point, and then the transfer target is separated from the base, thereby transferring the developer image on the base surface to the transfer target. An image recording method characterized by recording an image.

2. Forming an electrostatic latent image on a substrate, dispersing the colorant particles in a dispersion medium that is solid at room temperature and that reversibly repeats solidification by melting and cooling by heating above its melting point. After forming a developer image consisting of the colorant particles and the dispersing medium on the surface of the substrate by performing development using a solidified developer, the substrate and the transfer-receiving body are pressed and heated. The dispersion medium is softened within a range that does not exceed the melting point of the medium, and then the image of the developer is transferred from the substrate to the image of the substrate by transferring the developer surface image from the substrate to 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 1, wherein when the transfer object is separated from the substrate, heating is performed from the back side of the substrate.

5. The image recording device according to claim 1, wherein after the transfer object is separated from the substrate, the transfer object is heat-treated at a temperature equal to or higher than a pressing temperature. Recording method.

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.