JPH09127796A - Liquid developing method for electrophotographic lithographic printing plate and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably obtain an excellent image quality with improved edge effect, in the liquid developing method for squeezing liquid by holding with squeeze rolls pair, and a liquid developing device capable of executing the same. SOLUTION: The liquid developing is performed by applying voltage in-between the squeeze rolls pair 32 and 33 held in contact with an electrostatic latent image forming surface, and a metallic supporting body. Then, liquid developer feeding means 28 and electrodeposition means is severally arrange corresponding to the rolls 32 and 33, and the liquid developing is performed by executing the electrodeposition of the toner particle on the squeezing roll surface. Moreover, the toner particle remaining on the squeeze rolls 32 and 33 surface is removed by toner particle removing means 27, while the liquid developing is performed. Furthermore, a part of the liquid developer is recovered into the tray 17 by providing recovering means of the developer in-between the electrodeposition means and the squeeze rolls pair 31, while the liquid developing is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of carrying an electrophotographic lithographic printing plate having an electrostatic latent image formed on a photoconductive layer while bringing a liquid developer into contact with the electrostatic latent image forming surface. More specifically, the present invention relates to a liquid developing method and apparatus for an electrophotographic lithographic printing plate which is sandwiched between squeezing rolls and squeezed, and more specifically, to an electrophotographic lithographic printing plate capable of stably obtaining a high quality image by suppressing an edge effect. Liquid developing method and device.

[0002]

2. Description of the Related Art An electrophotographic lithographic printing plate comprises a photoconductive layer provided on a conductive support, and in the heavy printing field where the number of printable sheets is required, the electroconductive support is made hydrophilic. A treated metal sheet of aluminum or the like, and an organic photoconductive compound binder resin dispersion material is generally used as a material for forming the photoconductive layer.

An electrophotographic lithographic printing plate having a photoconductive layer on a metallic support (hereinafter, an electrophotographic lithographic printing plate having a photoconductive layer on a metallic support is referred to simply as an electrophotographic lithographic printing plate or a printing plate. In the general plate-making process of (described), a uniform charge is applied on the printing plate photoconductive layer in the charging process, and an active light of the organic photoconductive compound is exposed in the exposure process to correspond to the image. An electrostatic latent image is formed. In recent years, with the development of organic photoconductive compounds that have excellent sensitivity even in the long-wavelength region and the construction of a computer system that instantaneously stores, processes, and communicates large amounts of data, drawing and printing directly from a computer A plate-making system for obtaining a plate has been put into practical use, and scanning exposure with laser light is performed in the exposure process.

The electrophotographic lithographic printing plate on which the electrostatic latent image is formed is subsequently liquid-developed using a liquid developer for electrophotographic lithographic printing plate (hereinafter referred to as liquid developer) in a liquid developing step. Then, a toner image corresponding to the electrostatic latent image is formed. Non-image areas other than the toner image are eluted and removed by a treatment liquid containing an alkali agent or the like in the elution step, and each treatment such as washing with water, rinsing, and application of a plate surface protective liquid is performed as necessary. The final printing plate is obtained.

FIG. 5 shows an example of a conventional liquid developing apparatus for performing liquid development on an electrophotographic lithographic printing plate. The liquid developing apparatus includes a liquid developing processing unit 101, a drying unit 102, and a heat fixing unit 103. The liquid developing processing unit 101 includes a developing electrode 35, a developing electrode unit 34 including a lower guide plate 36, and a squeeze roll pair 31. ′, A liquid developer supply port 80 and a liquid developer storage tank 12 are installed. The liquid developer storage tank 12 is connected to the liquid developer supply port 80 by a pipe 74, and a liquid developer supply pump is provided in the middle of the pipe. 72 is installed and the liquid developer 2 stored in the liquid developer storage tank 12 passes through the liquid developer discharge port 80, and is placed between the developing electrode 35 and the lower guide plate 36 (developing electrode portion 34). It is designed to be supplied.

The electrophotographic lithographic printing plate 1 on which the electrostatic latent image is formed is conveyed into the developing electrode section 34 by a conveying means (not shown) for conveying the plate in the direction of arrow B at a constant speed.
Before the printing plate 1 enters the developing electrode section 34, the liquid developer supply pump 72 starts operating to supply the liquid developer 2 to the developing electrode section 34. The supplied liquid developer 2 fills the gap between the printing plate 1 and the developing electrode 35, is provided for liquid development, and is then collected again in the liquid developer storage tank 12 and circulated for use.

A bias voltage is applied to the developing electrode 35 by a voltage applying means (not shown), and the liquid filled in the gap between the electrostatic latent image on the surface of the printing plate 1 and the electric field generated by the developing electrode 35. The toner particles in the developer 2 are electrophoresed and adhere to the surface of the printing plate 1 imagewise according to the electrostatic latent image. Thereafter, the printing plate 1 is sandwiched between the squeeze roll pair 31 ′, and the printing plate 1 that has passed through the squeeze roll pair 31 ′ has the excess liquid developer 2 almost removed, and is then dried.
It is transported to 02. In the drying unit 102, the dispersion medium of the liquid developer 2 remaining on the plate surface is dried and removed, and then the toner particles are thermally fixed in the thermal fixing unit 103, and the toner particles are melted to form a film.

In the liquid developing method using the conventional liquid developing apparatus as described above, when an image having a high resolution is required, an excessive amount near the boundary of the non-image portion of the image portion, which is called an edge effect, is generated. Toner particle adhesion becomes a problem. The generation mechanism of this edge effect will be described with reference to FIG. 6 by taking as an example the case where the electrophotographic lithographic printing plate is positively charged and a positive bias voltage is applied from the developing electrode.

In the electrostatic latent image formed by charging and laser exposure, the surface potential of the exposed portion X is at most about 10 V, while the unexposed portion Y generally holds a charged surface potential of 200 V or more. Therefore, when a bias voltage is applied to the developing electrode 35 arranged so as to face the electrostatic latent image forming surface, an electric field as indicated by an electric force line 112 is generated. FIG.
6A shows a case where the developing electrode 35 and the printing plate 1 have a large gap, and FIG. 6B shows a case where the gap is narrow. The bias voltage is set so that the electric field strength in the direction perpendicular to the plate surface in the exposed portion X becomes equal.

Near the boundary between the exposed portion X and the unexposed portion Y (E1
And E2), since a strong electric field having a component parallel to the plate surface due to the surface charging potential of the unexposed portion Y is added to the electric field in the direction perpendicular to the plate surface due to the effect of the bias voltage, exposure other than near the boundary is performed. The lines of electric force are concentrated and the electric field strength is stronger than in the portion X. Therefore, E1 and E
More positively charged toner particles adhere to the two areas, and the edge effect is developed. In the areas E1 and E2 where the edge effect appears, even if there is a charging potential holding area that is originally a non-image portion, toner particles adhere to the charging potential holding area due to the edge effect, and as a result, the non-image The area that should be a copy becomes the image area.

Specifically, when a shadow dot is in contact with a wide non-image area, shadow shadow collapse occurs, and when a negative fine line image is in contact with a wide non-image area. In this case, the negative thin line is crushed in the boundary area. For the image failure due to these edge effects, it is effective to narrow the E1 and E2 regions where the edge effect shown in FIG. 6 is made, that is, narrow the distance between the developing electrode and the electrostatic latent image forming surface. By narrowing the distance between the developing electrode and the electrostatic latent image forming surface from d1 when it is wide to d2 when it is narrow, it is possible to narrow the region in which the edge effect appears from E1 to E2.

When the electrostatic latent image forming surface comes into contact with the liquid developer in the portion where the developing electrode is not present, the unexposed portion is exposed as in the case where the distance between the developing electrode and the electrostatic latent image forming surface is infinite. Since the development of the exposed portion other than the vicinity of the boundary is not performed and only the adhesion of the toner particles by the edge effect is started, the edge effect is deteriorated. Therefore, in order to suppress the edge effect, the gap between the developing electrode and the electrostatic latent image forming surface is set to be small, and the method described in JP-A-5-6 is used.
As described in Japanese Patent No. 6655, the area where the liquid developer is in contact with the electrostatic latent image forming surface is limited in the portion without the developing electrode,
In addition, it is important that the liquid developer comes into contact with the electrostatic latent image forming surface only in an extremely narrow gap that fills the minimum amount of liquid developer required for liquid development.

However, in the liquid development of the electrophotographic lithographic printing plate, since the toner particles are melted and fixed on the plate surface after the toner particles are attached, the excess dispersion medium of the liquid developer is removed from the plate surface before the heat fixing. Even if the squeeze roll pair is provided immediately after the developing electrode to remove the excess liquid developer as in the conventional liquid developing device, the liquid developing is performed on the developing electrode side near the squeeze roll pair. The agent comes into contact with the electrostatic latent image forming surface in a region other than the developing electrode portion, which makes it difficult to suppress the edge effect.

In addition, the printing plate can be rigid because the gap between the developing electrode and the electrostatic latent image forming surface is kept in non-contact with the liquid developer and filled with a minimum amount of liquid developer required for liquid development. It is difficult in that it has a slight distortion because it has and is cut on the sheet. Furthermore, when a large number of printing plates are liquid-developed for a long period of time, it is not possible to prevent the gap from changing due to positional changes of the printing plates during conveyance, and if the degree is severe, the printing electrodes come into contact with the printing plates and the There is a risk that a short circuit or scratching may occur.

A change in the distance between the developing electrode and the electrostatic latent image forming surface of the printing plate means a change in the electric field strength in the gap, which causes image unevenness or fine lines on the plate surface. This may cause deterioration of reproducibility of dots and halftone dots, which is not preferable. Even if such an abnormality for each plate is not observed, there is a high possibility that image quality fluctuations such as dot density fluctuations occur between plates. In any case, if the distance between the plate surface and the developing electrode is narrow, the change in the electric field strength in the gap becomes larger even if the fluctuation width due to the position fluctuation is the same.
The image quality variation will be more prominent.

In order to prevent the contact between the printing plate and the developing electrode during conveyance, Japanese Patent Laying-Open No. 6-337573 discloses that an introducing roller is rotatably installed on the upstream side of the developing electrode during conveyance. When the position of the printing plate changes, the technique is disclosed in which the printing plate is restricted by the introduction roller before contacting the developing electrode to avoid contact with the developing electrode.
However, even with this, there is a limit in narrowing the distance between the printing plate and the developing electrode. Further, by this method, even if the edge effect is suppressed by reducing the distance to the limit at which contact with the developing electrode does not occur, even if contact with the developing electrode does not occur, the inside of the gap as described above is It is not possible to prevent image quality fluctuations due to changes in electric field strength.

Therefore, when liquid development processing is carried out while the electrophotographic lithographic printing plate is conveyed, no electric short circuit due to contact between the developing electrode and the printing plate or scratches due to rubbing occurs, and the electric field strength changes. A liquid developing method or a liquid developing method capable of obtaining a high quality image in which the edge effect is not substantially observed even when a high resolution image is developed, while suppressing the image quality variation due to There was no device.

[0018]

SUMMARY OF THE INVENTION Therefore, according to the present invention, a liquid developer is brought into contact with an electrostatic latent image forming surface while conveying an electrophotographic lithographic printing plate having an electrostatic latent image formed on a photoconductive layer. In the liquid developing method and apparatus for electrophotographic lithographic printing plate which is sandwiched by a pair of squeezing rolls and then squeezed, electrophotographic lithographic printing that can suppress edge effect and stably obtain high quality image It is an object of the present invention to provide a liquid developing method and device for a plate.

[0019]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the following liquid developing method and apparatus were achieved. That is, while transporting the electrophotographic lithographic printing plate having the electrostatic latent image formed on the photoconductive layer of the electrophotographic lithographic printing plate having the photoconductive layer provided on the metallic support, the liquid developer is electrostatically latent imaged. In the liquid developing method of an electrophotographic lithographic printing plate, which is brought into contact with the image forming surface and then sandwiched between a pair of squeeze rolls to squeeze the liquid, the squeezing roll contacting the electrostatic latent image forming surface and the electrophotographic lithographic printing plate metal This is achieved by applying a voltage between the support and the liquid to develop the liquid (first invention).

Further, while applying a voltage between the liquid developer supply means and the squeeze roll in contact with the electrostatic latent image forming surface, the liquid developer supply means squeezes through the squeeze roll in contact with the electrostatic latent image forming surface. It is achieved by bringing the liquid developer into contact with the electrostatic latent image forming surface and applying a voltage between the squeeze roll and the printing plate metallic support which are in contact with the electrostatic latent image forming surface to perform liquid development ( Second invention).

Further, while applying a voltage between the liquid developer supply means and the squeeze roll in contact with the electrostatic latent image forming surface, the liquid developer supply means squeezes through the squeeze roll in contact with the electrostatic latent image forming surface. The liquid developer is brought into contact with the electrostatic latent image forming surface, a voltage is applied between the squeeze roll and the printing plate metallic support which are in contact with the electrostatic latent image forming surface to perform liquid development, and the squeeze roll pair is used. This is accomplished by removing the toner particles remaining on the surface of the squeeze roll that is in contact with at least the electrostatic latent image forming surface after squeezing the liquid developer (third invention).

Further, while applying a voltage between the liquid developer supply means and the squeeze roll in contact with the electrostatic latent image forming surface, the liquid developer supply means squeezes through the squeeze roll in contact with the electrostatic latent image forming surface. After the liquid developer is brought into contact with the electrostatic latent image forming surface and before the liquid developer comes into contact with the electrostatic latent image forming surface, a part of the liquid developer is collected from the squeeze roll to form the electrostatic latent image forming surface. Liquid is developed with an unrecovered liquid developer while applying a voltage between the squeeze roll and the printing plate metallic support in contact with the squeeze roll, and after squeezing the liquid developer with a squeeze roll pair as desired, at least This is achieved by removing the toner particles remaining on the surface of the squeeze roll that is in contact with the surface on which the latent image is formed (the fourth invention).

In addition to each of the above-mentioned inventions, electrophotography when a voltage is applied between the squeeze roll in contact with the electrostatic latent image forming surface and the electrophotographic lithographic printing plate metallic support to perform liquid development. This is achieved by the length of the region in which the lithographic printing plate is in contact with the liquid developer in the transport direction being equal to or less than the radius of the squeeze roll in contact with the electrostatic latent image forming surface (fifth invention).

In addition to the above first to fifth inventions, the use of an electrophotographic lithographic printing plate having a side end portion of the electrophotographic lithographic printing plate subjected to an insulating treatment (sixth invention), This can be achieved by at least a portion where the side end portion of the electrophotographic lithographic printing plate of the squeezing roll that contacts the electrostatic latent image forming surface contacts is in an insulating state (seventh invention).

Further, a liquid developing apparatus for an electrophotographic lithographic printing plate which carries out the invention and supplies the liquid developer to the electrostatic latent image forming surface of the electrophotographic lithographic printing plate on which the electrostatic latent image is formed to develop the liquid. In a liquid developing device having at least a liquid developer supplying means and a pair of aperture rolls, a liquid developing device further comprising voltage applying means for applying a bias voltage to the aperture roll in contact with the electrostatic latent image forming surface is achieved. (Eighth invention).

A liquid developing apparatus for an electrophotographic lithographic printing plate, which supplies a liquid developer to an electrostatic latent image forming surface of an electrophotographic lithographic printing plate on which an electrostatic latent image is formed to develop the liquid, A voltage applying means for applying a bias voltage to the diaphragm roll in contact with the latent image forming surface, and an electrodeposition means for applying a voltage between the liquid developer supplying means and the diaphragm roll in contact with the electrostatic latent image forming surface. This is achieved by the liquid developing device having the ninth invention.

Further, a voltage is applied between the voltage applying means for applying a bias voltage to the diaphragm roll in contact with the electrostatic latent image forming surface, the liquid developer supplying means and the diaphragm roll in contact with the electrostatic latent image forming surface. And a collection means for collecting excess liquid developer from the aperture roll in contact with the electrostatic latent image forming surface by controlling the supply amount of the liquid developer supplied from the liquid developer supply means. And a removing unit that removes toner particles remaining on the surface of the squeeze roll in contact with the electrostatic latent image forming surface after squeezing the liquid developer by the squeeze roll pair (the tenth invention). .

Further, a voltage is applied between the voltage applying means for applying a bias voltage to the diaphragm roll in contact with the electrostatic latent image forming surface and the liquid developer supplying means and the diaphragm roll in contact with the electrostatic latent image forming surface. An electrodeposition means, a recovery means for controlling the supply amount of the liquid developer supplied from the liquid developer supply means, and recovering the excess liquid developer from the diaphragm roll in contact with the electrostatic latent image forming surface, and a pair of diaphragm rolls. In the liquid developing apparatus having a removing means for removing the toner particles remaining on the surface of the squeeze roll in contact with the electrostatic latent image forming surface after squeezing the liquid developer by the electrodeposition means, the electrodeposition means supplies the liquid developer. A conductive roll, which is installed facing the squeeze roll with a gap and can apply a voltage, and a sheet between which the collecting means is impregnated with the liquid developer is placed between the conductive roll and the squeeze roll supplying the liquid developer. To pass Thus is achieved by the liquid developing device is a liquid developer impregnated sheet to perform both the supply and recovery of the liquid developer (eleventh aspect).

A liquid developing apparatus for an electrophotographic lithographic printing plate which supplies a liquid developer to the electrostatic latent image forming surface of the electrophotographic lithographic printing plate on which the electrostatic latent image is formed to develop the liquid. An endless belt that is in contact with the agent supply means and the squeeze roll on the electrostatic latent image forming surface side, at least a contact surface with the electrostatic latent image forming surface is made of an elastic material, and holds a certain amount of liquid developer, and a bias voltage. Is achieved by a liquid developing device having a voltage applying unit for applying (a twelfth invention).

[0030]

The liquid developer is electrostatically charged while transporting the electrophotographic lithographic printing plate having the electrostatic latent image formed on the photoconductive layer of the electrophotographic lithographic printing plate having the photoconductive layer provided on the metallic support. According to the first invention in which a voltage is applied between the squeeze roll and the printing plate metallic support which are in contact with the latent image forming surface and are in contact with the electrostatic latent image forming surface, the gap between the squeeze roll and the printing plate is wide. Not only uniformly and stably in the direction, but by storing the required minimum amount of liquid developer on the printing plate including the gap formed by the printing plate and the squeeze roll, only that area is developed. As a result, it becomes possible to carry out liquid development in which a high quality image in which the edge effect is suppressed can be obtained.

Further, while applying a voltage between the liquid developer supplying means and the squeeze roll in contact with the electrostatic latent image forming surface, the liquid developer supplying means squeezes through the squeeze roller in contact with the electrostatic latent image forming surface. According to the second invention in which the liquid developer is brought into contact with the electrostatic latent image forming surface and a voltage is applied between the squeeze roll and the printing plate metallic support which are in contact with the electrostatic latent image forming surface to perform the liquid development, When the toner particles are close to the surface of the squeeze roll, the toner particle concentration of the liquid developer in the developing area can always be kept good. Further, the toner particles that are brought closer to the surface of the squeeze roll by the electrodeposition means contribute to the development when they are closest to the printing plate in the developing area. Development takes place,
A high quality image in which the edge effect is further suppressed can be obtained.

Further, while applying a voltage between the liquid developer supply means and the squeeze roll which is in contact with the electrostatic latent image forming surface, the liquid developer is squeezed by the liquid developer supply means through the squeeze roll. The liquid is developed by bringing it into contact with the image forming surface and applying a voltage between the squeeze roll and the printing plate metallic support. According to the third aspect of the present invention for removing the toner particles, the toner particles electrodeposited from the liquid developer supplying means to the squeeze roll are always kept in a constant state,
In combination with the above operation, high quality image quality without density unevenness can be stably obtained.

While applying a voltage between the liquid developer supplying means and the squeeze roll in contact with the electrostatic latent image forming surface, the liquid developer supplying means squeezes through the squeeze roller in contact with the electrostatic latent image forming surface. After the liquid developer is brought into contact with the electrostatic latent image forming surface and before the liquid developer comes into contact with the electrostatic latent image forming surface, a part of the liquid developer is collected from the squeeze roll to form the electrostatic latent image forming surface. Liquid is developed with an unrecovered liquid developer while applying a voltage between the squeeze roll and the printing plate metallic support in contact with the squeeze roll, and after squeezing the liquid developer with a squeeze roll pair, if desired, at least According to the fourth invention for removing the toner particles remaining on the surface of the squeeze roll in contact with the electrostatic latent image forming surface, the liquid developer staying in the developing area does not increase, and a proper amount of the liquid developer is always present in the developing area. Retained.

In addition to each of the above-mentioned inventions, electrophotography when liquid is developed by applying a voltage between the squeeze roll in contact with the electrostatic latent image forming surface and the electrophotographic lithographic printing plate metal support. According to the fifth aspect of the invention, the length of the area in which the lithographic printing plate is in contact with the liquid developer in the transport direction is equal to or less than the radius of the squeeze roll in contact with the electrostatic latent image forming surface. It plays the role of an electrode and can suppress the edge effect.

In addition to the above-mentioned inventions, according to a sixth invention, which uses an electrophotographic lithographic printing plate having an insulating treatment applied to a side end of the electrophotographic lithographic printing plate, a side end of the electrophotographic lithographic printing plate is obtained. It is possible to prevent a short circuit of the bias voltage due to the contact between the exposed metal support and the squeeze roll to which a voltage is applied, and it is possible to always apply a constant electric field to the developing area in the width direction.

According to the seventh aspect of the invention, at least the portion of the squeeze roll that comes into contact with the electrostatic latent image forming surface is brought into contact with the side end portion of the electrophotographic lithographic printing plate so as to be in an insulating state. It is possible to prevent a short circuit of the bias voltage due to the contact between the metal support portion exposed at the side end and the squeeze roll that applies a voltage, and always apply a constant electric field to the developing area in the width direction. Can be done.

Further, a liquid developing apparatus for an electrophotographic lithographic printing plate for carrying out the above-mentioned invention, which supplies a liquid developer to the electrostatic latent image forming surface of the electrophotographic lithographic printing plate on which an electrostatic latent image is formed and develops it. According to an eighth aspect of the present invention, in a liquid developing device having at least a liquid developer supply unit and a pair of aperture rolls, further comprising a voltage applying unit for applying a bias voltage to the aperture roll in contact with the electrostatic latent image forming surface. The liquid developing device enables liquid development with a good image quality in which the edge effect is suppressed.

Further, there is provided a voltage applying means for applying a bias voltage to the diaphragm roll in contact with the electrostatic latent image forming surface, and a voltage is applied between the liquid developer supplying means and the diaphragm roll in contact with the electrostatic latent image forming surface. With the liquid developing device of the ninth invention having the electrodeposition means for applying the voltage, the toner particle concentration of the liquid developer in the developing area can be always kept good in a state where the toner particles are close to the surface of the squeeze roll. . Further, since the toner particles that are close to the surface of the squeeze roll by the electrodeposition means contribute to the development when the squeeze roll and the printing plate are closest to each other in the developing area, a very narrow gap area immediately before the contact between the squeeze roll and the printing plate. Development is carried out to obtain a high-quality toner image in which the edge effect is further suppressed.

Further, a voltage is applied between the voltage applying means for applying a bias voltage to the diaphragm roll in contact with the electrostatic latent image forming surface and the liquid developer supplying means and the diaphragm roll in contact with the electrostatic latent image forming surface. And a collection means for collecting excess liquid developer from the aperture roll in contact with the electrostatic latent image forming surface by controlling the supply amount of the liquid developer supplied from the liquid developer supply means. And a removing means for removing toner particles remaining on the surface of the squeeze roll in contact with the electrostatic latent image forming surface after squeezing the liquid developer by the pair of squeeze rolls. An appropriate amount of liquid developer is always retained in the development area without increasing the amount of liquid developer staying in the area, and high-quality liquid development can be performed.

Further, a voltage is applied between the voltage applying means for applying a bias voltage to the diaphragm roll in contact with the electrostatic latent image forming surface and the liquid developer supplying means and the diaphragm roll in contact with the electrostatic latent image forming surface. An electrodeposition means, a recovery means for controlling the supply amount of the liquid developer supplied from the liquid developer supply means, and recovering the excess liquid developer from the diaphragm roll in contact with the electrostatic latent image forming surface, and a pair of diaphragm rolls. In the liquid developing apparatus having a removing means for removing the toner particles remaining on the surface of the squeeze roll in contact with the electrostatic latent image forming surface after squeezing the liquid developer by the electrodeposition means, the electrodeposition means supplies the liquid developer. A conductive roll, which is installed facing the squeeze roll with a gap and can apply a voltage, and a sheet between which the collecting means is impregnated with the liquid developer is placed between the conductive roll and the squeeze roll supplying the liquid developer. To pass Therefore, with the liquid developing apparatus of the eleventh invention, which is a liquid developer-impregnated sheet that both supplies and recovers the liquid developer, it is possible to stably suppress the edge effect and perform high-quality liquid development with a simple configuration. I can.

A liquid developing apparatus for an electrophotographic lithographic printing plate which supplies a liquid developer to the electrostatic latent image forming surface of the electrophotographic lithographic printing plate on which the electrostatic latent image is formed to develop the liquid. An endless belt that is in contact with the agent supply means and the squeeze roll on the electrostatic latent image forming surface side, at least a contact surface with the electrostatic latent image forming surface is made of an elastic material, and holds a certain amount of liquid developer, and a bias voltage. With the liquid developing device according to the twelfth aspect of the invention having a voltage applying unit for applying a voltage, the degree of freedom in supplying the liquid developer and installing the electrodeposition unit is improved, and the edge effect is more stably and reliably suppressed. Liquid development can be performed. Further, when liquid development is performed by the method and apparatus of each of the above inventions, it is possible to develop the developing bias voltage at a value lower than the conventional value, so that the surface potential in the charging step can be suppressed to a low level, and therefore, It is also possible to prevent image failure due to discharge leak that tends to occur at high surface potential.

The liquid developing method and apparatus for electrophotographic lithographic printing plate of the present invention will be described in more detail below.

The squeeze roll pair relating to the liquid developing method and the liquid developing apparatus for the electrophotographic lithographic printing plate of the present invention holds the electrophotographic lithographic printing plate on which the electrostatic latent image is formed and conveys it while squeezing the roll. By applying a bias voltage between the printing plate metallic support, the upper squeeze roll in contact with the printing plate electrostatic latent image forming surface (hereinafter, the upper squeeze roll in contact with the printing plate electrostatic latent image forming surface (Simply described as upper squeeze roll) and a developing bias electric field is generated in a portion (developing area) where the electrophotographic lithographic printing plate and the squeeze roll surface on the conveyance inlet side of the contact portion of the electrophotographic lithographic printing plate face each other with a narrow gap, Liquid development of the electrostatic latent image on the plate surface is performed by the liquid developer supplied thereto.

The electrostatic latent image on the plate surface is subjected to liquid development in the above-mentioned developing area, and after the excess liquid developer is removed by the pair of squeeze rolls, it is sent to the next drying step and heat fixing step. To be Therefore, the squeezing roll pair according to the present invention is
Forming a developing area and applying a developing bias electric field to the developing area, as well as the role of a squeezing roll pair in a conventional liquid developing apparatus such as transporting a printing plate and removing excess liquid developer on the plate surface. Plays the role of.

If the removal of the liquid developer by the pair of squeezing rolls is not good, the dispersion medium cannot be completely evaporated and remains on the plate surface in the subsequent drying step, and in the subsequent heat fixing step, poor heat fixing and surface charging are caused. As a result, the image quality is deteriorated such that the toner image is broken due to the movement of the toner particles adhering to the printing plate due to the loss of electric charge. When the image quality deteriorates due to the deterioration of the liquid developer removal efficiency as described above, the liquid developer removal efficiency can be improved by adjusting the hardness and shape of the squeeze roll, the pressing method, and the like. . When the pressing method is applied to press the bearing portions at both ends of the roll, it is desirable to perform crown processing to make the diameter of the central portion of the roll rubber portion thicker than the diameter of the end portions of the roll rubber portion.

Further, regarding the formation of the developing region, a portion where the upper squeeze roll surface and the electrophotographic lithographic printing plate are substantially opposed to each other with a narrow gap is provided on the conveyance inlet side of the contact portion between the upper squeeze roll and the electrophotographic lithographic printing plate. It must be formed stably, and for that purpose, the hardness, shape, and
It is also necessary to adjust the pressing method so that the ratio of the contact width of the upper squeezing roll and the electrophotographic lithographic printing plate in the transport direction to the upper squeezing roll diameter does not become large. The preferable ratio between the contact width and the upper drawing roll diameter is 0.00
It is in the range of 5 to 0.2.

Further, the application of the developing bias electric field to the developing area depends on the material and the resistance value of the rubber portion of the upper squeeze roll. If the resistance value is too low, a short circuit occurs and a voltage can be applied. On the other hand, if the resistance value is too high, it means that a sufficient developing bias electric field is not formed in the developing region, and good liquid developing cannot be performed. In order to obtain a good resistance value of the upper squeeze roll, it can be performed by conducting a conductive treatment on the rubber portion of the squeeze roll or adjusting the thickness of the rubber portion.

The rubber hardness of at least the portion of the squeezing roll pair according to the present invention that comes into contact with the printing plate is preferably in the range of 30 to 70 degrees, more preferably 35 to 60 degrees.
A range of degrees is preferred. The rubber hardness in the present invention is J
It can be measured by a spring type hardness tester A type specified in IS K 6301, but the value measured by this hardness tester A type may be in the above range regardless of the rubber thickness of the roll.

As the material of the rubber portion of the pair of squeeze rolls according to the present invention, at least the developing bias electric field must be able to be applied well to the developing region, but in addition, it has resistance to the liquid developer component and swells. It ’s hard to do,
Further, it preferably has abrasion resistance, aging resistance, weather resistance and the like. A preferred rubber material is a synthetic rubber made of a component having low solubility in hydrocarbons and solvents, such as acrylonitrile-butadiene copolymer rubber (NBR), isoprene-acrylonitrile copolymer rubber, chloroprene rubber (CR), acrylic rubber. (ACM / ANM), chlorosulfonated polyethylene rubber (CSM), silicone rubber (Q), polysulfide rubber (TR), fluororubber and the like.

Of these, NBR containing a large amount of acrylonitrile is excellent in terms of abrasion resistance, solvent resistance, processability, cost and the like. To these rubbers, additives such as a reinforcing filler, an expanding filler, a dispersibility improver, an adhesiveness improver, a heat resistance additive, an antioxidant, a colorant, a crosslinking agent, and a curing catalyst are solvent-resistant. It can be contained within a range that does not affect the above. Further, the preferable volume specific resistance value of the rubber material in the present invention is in the range of 10 ³ to 10 ¹⁴ Ω · cm, and the conductive treatment can be performed so as to fall within this range.

The diameter of the upper squeezing roll according to the present invention is
Any diameter may be used as long as the resistance value can effectively apply the developing bias electric field and liquid developer removal efficiency is effective, but in view of sufficient formation of the developing area and downsizing of the apparatus, the upper squeeze roll 20m as diameter range
The range from m to 400 mm is preferable, and more preferably 4
It is in the range of 0 mm to 200 mm. The diameter of the lower squeeze roll forming a pair with the upper squeeze roll is not particularly limited and may be the same as or different from the diameter of the upper squeeze roll.

The bias voltage value according to the present invention is such that the entire surface solid image of the electrophotographic planographic printing plate, that is, the entire surface potential is approximately 0.
When liquid development is performed by the method of the present invention in the V state,
Adjust so that the toner particles adhere well to the entire surface. This bias voltage value changes depending on the shape of the squeeze roll, the squeeze roll resistance value, the transport speed, etc., but the range of the preferable bias voltage value is in the range of 10V to 300V, and more preferably in the range of 30V to 150V. .

As a method of supplying the liquid developer to the upper squeeze roll according to the present invention, the liquid developer may be directly discharged to the upper squeeze roll, or may be discharged to the upper squeeze roll via a sloping plate or the like. You may supply so that it may flow in by gravity. In any case, it is installed so that the liquid developer supplied to the upper squeeze roll reaches the above-mentioned developing area along the roll surface and never flows into the outlet side of the squeeze roll pair nip portion in the conveying direction. Things are needed.

In the present invention, in order to direct the toner particles in the liquid developer supplied to the upper squeeze roll surface toward the upper squeeze roll surface, a voltage is applied to the upper squeeze roll from the liquid developer supply means. Things are preferred. As a specific method, a conductive plate material or a roll facing the upper squeeze roll with a gap is provided below the liquid developer supply portion on the peripheral surface of the squeeze roll, and the member and the upper squeeze roll are provided. Electrodeposition can be performed by applying a voltage to. When a conductive plate material facing the upper squeeze roll is provided, the conductive plate material may be curved so as to face the upper squeeze roll at the same interval in order to effectively face the upper squeeze roll. .

On the other hand, when the toner particles electrodeposited on the surface of the squeeze roll face the surface potential holding portion of the electrostatic latent image on the plate surface in the developing area, that is, the non-image portion, the toner particles are on the plate surface. When the liquid developer is supplied again as it is, the toner particle concentration of the liquid developer varies depending on the width direction of the roll and is stable. Therefore, high quality liquid development may not be possible. Therefore, in the present invention, it is preferable to remove at least the toner particles remaining on the upper squeeze roll before newly supplying the liquid developer.

As a removing method for removing the toner particles remaining on the upper squeeze roll, an electrical method and a mechanical method can be mentioned. As an electrical method, a method may be mentioned in which a voltage is applied to a conductive member installed facing the upper squeeze roll so that the toner particles move in a direction away from the surface of the upper squeeze roll. At that time, a minute gap may be provided between the conductive member and the squeeze roll, or an insulating member may be provided between the conductive member and the squeeze roll so as to contact with the squeeze roll so that the toner particles adhere to the insulating member. You can Further, in order to facilitate the movement of the toner particles, a small amount of a dispersion medium of the toner particles used for the liquid developer may be supplied between the conductive member and the squeeze roll.

Further, as a mechanical method, a method of removing the toner particles by bringing a scraping or wiping member into contact with the surface of the squeezing roll can be mentioned. At that time, a dispersion medium of the toner particles or a solvent capable of dissolving the toner particles may be supplied. Whichever method is used, the removed toner particles and the toner particle dispersion medium, solvent, etc. supplied as desired are not only attached to the printing plate after completion of liquid development, but also reattached to the upper squeeze roll and newly added. It is important to collect and discard all of the liquid developer so that it does not mix with the supplied liquid developer.

Further, in the present invention, in order to prevent the liquid developer from staying excessively in the developing area formed by the upper squeeze roll and the printing plate, the liquid developer supplied to the upper squeeze roll is used. A part of the liquid developer may be collected before reaching the developing area and the amount of the liquid developer reaching the developing area may be adjusted. That is, if it is attempted to adjust the supply amount of the liquid developer in the liquid developer supply means in advance without performing this recovery, there is a possibility that uneven supply may occur particularly in the squeeze roll width method. The supply mechanism of the supply means and the adjusting method thereof are more complicated, which is not preferable.

As a method of collecting the liquid developer supplied to the upper squeeze roll, a certain gap is provided below the liquid developer supply means and the upper squeeze roll, and the liquid developer passed through the certain gap. Only the liquid developer may be brought into contact with the printing plate, and the other liquid developer may be recovered. Further, the sheet that absorbs the liquid developer may be brought into contact with the upper squeeze roll to collect the liquid developer.

When a sheet which absorbs the liquid developer is used, the sheet is preliminarily impregnated with the liquid developer, and the sheet is passed between the electrodeposition means and the upper squeeze roll to obtain the liquid developer. It is possible to supply and recover the developer at the same time, and to adjust the supply amount and the recovery amount of the liquid developer, change the type of the liquid developer impregnated sheet, apply pressure to the liquid developer impregnated sheet, etc. Is preferable because it can be easily adjusted. The liquid developer-impregnated sheet according to the present invention can be used as long as it is a sheet-shaped member having resistance to the liquid developer component and capable of impregnating and carrying the liquid developer, Sponge, cloth, non-woven fabric, etc. can be used.

Regarding the relationship between the supply amount and the recovery amount of the liquid developer, if the result is that the amount of the liquid developer retained in the developing area formed by the upper squeeze roll and the electrophotographic lithographic printing plate becomes excessive, The liquid developer goes up to the direction of the entrance side of the conveyance, and as described above, the liquid developer comes into contact with the electrostatic latent image in the portion where the developing electrode does not exist, so that the edge effect is deteriorated. On the contrary, if the amount of the liquid developer staying in the developing area is too small, the amount of toner particles necessary for forming a toner image will be insufficient, and an image defect will occur especially in the solid image portion (solid portion).

In the liquid developing method of the present invention, the length in the conveying direction of the region where the supplied liquid developer is in contact with the electrophotographic lithographic printing plate is not more than the radius of the upper squeezing roll. desirable. More preferably, it is less than or equal to half the radius of the upper squeeze roll. As a method of maintaining the length of the liquid developer in the transport direction of the printing plate contact area as described above, the blades, etc., that do not adversely affect the electrostatic latent image and the plate surface on the printing plate loading direction side can be used. Method of blocking liquid developer by providing liquid developer blocking means, arranging a pair of printing plate transport rolls on the printing plate loading direction side, transporting the printing plate and introducing it to the liquid development processing section, and printing plate Examples thereof include a method of blocking the liquid developer running upward, a method of tilting the electrophotographic lithographic printing plate obliquely downward and inserting it into the squeezing roll pair according to the present invention, and a method of combining these.

Whichever of the above-mentioned methods is adopted, the length in the transport direction of the area where the supplied liquid developer is in contact with the electrophotographic lithographic printing plate does not exceed the radius of the upper squeezing roll. It is preferable to adjust the recovery amount so that a good liquid developer amount stays in the developing area. When the obtained toner image density is low, the liquid developer supply amount is increased rather than the toner particle concentration. It is preferred to use high liquid developers.

The electrophotographic lithographic printing plate according to the present invention has a layer structure, a manufacturing method and the like which will be described in detail later, but at least a photoconductive layer is provided on a metallic support and cut into a desired size. It was done. When the electrophotographic lithographic printing plate remains cut, the metal support is exposed at the side end portion, that is, the cut surface, and is sandwiched and conveyed by the pair of squeeze rolls according to the present invention. At this time, there is a risk that an exposed portion of the metallic support member at the side end portion thereof and the surface of the upper squeeze roll to which the bias voltage is applied come into contact with each other to cause an electrical short circuit.
Therefore, it is preferable that the side edges of the electrophotographic lithographic printing plate be subjected to an insulating treatment so that the upper squeeze roll and the metallic support do not come into contact with each other.

As the insulating treatment agent applied to the side edge portion of the electrophotographic lithographic printing plate according to the present invention, there is disclosed in JP-A-63-1782.
Resins described in Japanese Patent No. 40 can be used. Examples of the insulating treatment agent used in the present invention include styrene / maleic anhydride copolymer, styrene / maleic acid monoester copolymer, methacrylic acid / methacrylic acid ester copolymer, styrene / methacrylic acid / methacrylic acid ester copolymer. Coalesced, acrylic acid / methacrylic acid ester copolymer,
Styrene, methacrylic acid ester, acrylic acid ester, vinyl acetate, benzoic acid such as styrene / acrylic acid / methacrylic acid ester copolymer, vinyl acetate / crotonic acid copolymer, vinyl acetate / crotonic acid / methacrylic acid ester copolymer Copolymers of carboxylic acid-containing monomers or acrylic acid group-containing monomers such as vinyl with acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, etc., methacrylic acid amide, phenolic Examples thereof include a copolymer containing a monomer having a hydroxyl group, a sulfonic acid group, a sulfonamide group, and a sulfonimide group, a phenol resin, a partially saponified vinyl acetate resin, a xylene resin, and a vinyl acetal resin such as polyvinyl butyral.

Among the above resins, the former monomer-containing copolymer having a carboxyl group and the phenol resin are particularly excellent in film forming property and insulating property and can be advantageously used in the present invention. As the monomer-containing copolymer having a carboxyl group, a copolymer of styrene and maleic acid monoester, a binary copolymer of acrylic acid or methacrylic acid and their alkyl, aryl, or aralkyl ester may be used. preferable. Further, a copolymer of vinyl acetate or vinyl benzoate and crotonic acid is also preferable. Particularly preferred phenolic resins include novolak resins obtained by condensing phenol, o-cresol, m-cresol, or p-cresol with methanal or ethanal under acidic conditions. These resins may be used alone or in 2
A mixture of more than one species may be used.

The electrophotographic lithographic printing plate according to the present invention is provided with a lower layer of the insulating treatment layer, that is, an end face on the side of the support, in order to improve the coating property and enhance the adhesiveness by smoothing the side ends of the electrophotographic lithographic printing plate. The intermediate layer between the insulating treatment layer and the insulating treatment layer is disclosed in JP-A-2-61.
Nos. 654 and 4-22972, etc. may be provided with a hydrophilic coating layer, or an insulating treatment layer may be laminated on the easily alkali-soluble resin described in JP-A-2-66566. Furthermore, by coexisting an appropriate amount of organic polymer fine particles such as polystyrene, nylon, polymethylmethacrylate, and polyurethane in the insulating treatment layer, the film property can be improved without significantly affecting the insulating property. Further, in order to improve the coating property and the adhesiveness with the support,
It is also preferable to add various surfactants when preparing the coating liquid.

The insulative treatment layer provided on the end portion of the printing plate according to the present invention is applied in the form of a coating liquid by a conventionally known method such as coating with a brush, sponge, non-woven fabric, or roller, or spray coating. Just set it up. Solvents for the coating liquid include aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane and chloroform, alcohols such as methanol, ethanol, 2-propanol, 1-butanol and propanediol, Ketones such as 2-butanone, 4-methyl-2-pentanone and cyclohexanone, glycol ethers such as 2-methoxyethanol and 2-methoxyethyl acetate, cyclic ethers such as oxolane, oxane and dioxane, ethyl acetate and propyl acetate And fatty acid alkyl esters such as butyl acetate and ethyl lactate. These solvents may be used alone or in combination of two or more.

As described above, the insulating treatment layer provided on the end portion of the printing plate according to the present invention makes contact with the exposed portion of the metallic support on the end portion of the printing plate and the surface of the upper squeeze roll to which a bias voltage is applied. Therefore, not only the risk of causing an electrical short circuit can be substantially avoided, but also at least the side end face must be charged with a constant charge potential to suppress toner fog. Therefore, the insulating treatment layer is charged to a high potential, more preferably to a potential equivalent to the charging potential of the electrophotographic photoconductive layer by the bias voltage at the time of liquid development, and is completely removed at least in the elution treatment. It is desirable to be in the range. The chargeability and the like cannot be specified unconditionally because it varies depending on the agent used for the charge retention layer, but the recommended general solid coating amount is 0.2 to 6.5 g / m ² , and more preferably 1 Is in the range of up to 5 g / m ² .

In the present invention, when the size of the electrophotographic lithographic printing plate to be liquid-developed, especially the width is fixed to some extent, the side end of the electrophotographic lithographic printing plate is subjected to an insulating treatment. Instead, it is also preferable to subject the upper squeezing roll to a portion where the side edge of the electrophotographic lithographic printing plate may come into contact with an insulating treatment. As a method of applying insulation treatment to the upper squeeze roll, in addition to the method of applying an insulating treatment agent as described above, a method of winding (pasting) an insulating film on the roll surface, an electrophotographic lithographic printing plate of the upper squeeze roll Examples include a method in which an insulating member having the same rubber hardness as the roll diameter of the other portion and having a rubber hardness of the other portion is inserted into a portion that may come into contact with the side end portion of the printing plate.

The upper squeezing roll according to the present invention is
There is an elastic member around the conductive shaft to which a bias voltage can be applied, which has excellent liquid developer removal efficiency and can form a developing bias electric field in the developing area near the nip on the transport inlet side. It does not matter if it is not in a roll shape as described above. That is, the endless belt made of an elastic material may be wound around the conductive roll. In that case, the liquid developer supply according to the present invention,
The electrodeposition of the toner particles by the electrodeposition means and the partial recovery of the liquid developer by the recovery means are all performed on the surface of the endless belt which is in contact with the electrostatic latent image forming surface. It is also desirable to remove the toner particles adhering to the surface of the endless belt by the removing means.

The endless belt according to the present invention can be freely passed through the endless belt so that the respective arrangements of the liquid developer supply, electrodeposition means, recovery means and removal means according to the present invention can exert their respective effects. You can decide. The endless belt length is preferably 1/2 or more of the length of the electrophotographic lithographic printing plate to be liquid-developed in the transport direction, and more preferably the length of the electrophotographic lithographic printing plate in the transport direction or more. .

Next, the electrophotographic lithographic printing plate according to the present invention will be described. The electrophotographic lithographic printing plate according to the present invention comprises a photoconductive layer provided on at least a metallic support. The metal support used for the electrophotographic lithographic printing plate includes aluminum, zinc, copper-aluminum, copper-stainless steel, bimetal such as chromium-copper, chromium-copper-aluminum, chromium-lead-iron, chromium-copper-stainless steel. Examples of the conductive support include a base made of a metal plate such as trimetal and the like, and at least one surface of which is hydrophilized.
The thickness of these is preferably 0.07 to 2.0 mm, more preferably 0.1 to 0.5 mm. Among these substrates, the aluminum plate is preferably used. The aluminum plate may contain aluminum as a main component and contain a trace amount of a different element, and conventionally known and publicly available materials can be appropriately used.

From the viewpoint of forming a photoconductive layer film, electrophotographic properties, printing durability, etc., at least the surface of the metallic support on which the photoconductive layer is provided has a center line average roughness (Ra) of 0.3-.
It preferably has a rough surface shape of 0.8 μm, more preferably 0.45 to 0.65 μm. Further, the pit spacing on the rough surface is preferably 30 to 100 μm in view of elution property,
Further, it is desirable that the bearing length (Rtp) defined by ISO 4287/1 has a rough surface shape of 70 to 85%. In order to form such a desired surface shape on the surface of the metallic support on which the photoconductive layer is provided, graining or anodic oxidation may be performed by a known method.

A desired electrophotographic photoconductive layer is provided on the conductive support thus obtained to obtain an electrophotographic lithographic printing plate. The photoconductive layer of the electrophotographic lithographic printing plate according to the present invention contains at least a photoconductive compound, and conventionally known photoconductive compounds may be used alone or in combination of two or more if desired. In the electrophotographic lithographic printing plate photoconductive layer used in the present invention, a metal-free or metal phthalocyanine pigment having photoconductivity is advantageously used. Among them, He-Ne lasers and semiconductors are preferred. Χ-type metal-free phthalocyanine and titanyl phthalocyanine, which have excellent photosensitivity even in a long wavelength region corresponding to a light source such as a laser, are more preferable.

A binder resin is used in combination with the photoconductive layer of the electrophotographic lithographic printing plate used in the present invention to improve the film-forming property and the adhesion to the support. When used as a printing plate, it is necessary to finally remove the photoconductive layer other than the image area. This step depends on the relative relationship between the solubility of the photoconductive layer in the eluate and the resist property of the toner in the eluate. Although it cannot be unequivocally expressed because it is determined, the binder resin is preferably a polymer compound that is soluble or dispersible in the eluate. Further, all the resins that can be used for the insulating treatment layer can be used as the binder resin for the photoconductive layer. Even when the insulating treatment layer and the photoconductive layer are made of the same kind of resin, the molecular weight, the acid value, etc. may be appropriately changed and used.

The mixing ratio of the photoconductive compound and the resin in the photoconductive layer of the electrophotographic lithographic printing plate according to the present invention should be determined so as to satisfy various characteristics such as desired electrophotographic characteristics and plate-making characteristics. Although it is sufficient, it is generally preferable to use a photoconductive compound mixed with the resin in an amount of 5 to 40% by weight. The thickness of the photoconductive layer is preferably 0.1 to 30 μm, more preferably 0.5 to 10 μm in view of charging property and elution property.
However, it is more preferably 1.5 to 6.0 μm.

The electrophotographic lithographic printing plate according to the present invention can be obtained by coating a photoconductive layer on a metallic support by a conventional method. The coating liquid is prepared by dissolving and dispersing each component constituting the photoconductive layer in a suitable solvent. When a component such as a photoconductive compound insoluble in the solvent is used, the average particle size of the dispersion is 0.
4 μm or less, more preferably 0.2 μm or less are dispersed and used. In addition to the photoconductive compound and the resin, a plasticizer, a surfactant, and other additives can be added to the photoconductive layer, if necessary. The additives used in the photoconductive layer can be added during or after the dispersion of the photoconductive compound.

An electrophotographic lithographic printing plate can be obtained by coating and drying the coating solution thus prepared on a conductive support by a known method. As the solvent for the coating liquid, various solvents described above as the solvent for the charge retention layer can be used. Further, the concentration (or viscosity) of the coating liquid and the mixing ratio of the solvent are appropriately selected depending on the coating method and the drying device. In the drying of the photoconductive layer-forming coating liquid, electrophotographic characteristics may be deteriorated particularly due to the drying conditions (temperature and air volume) in the initial drying zone.
It is preferable to set mild drying conditions.

Finally, a method for forming an electrostatic latent image on an electrophotographic lithographic printing plate according to the present invention and a liquid developer used for liquid development will be described. The method of forming an electrostatic latent image on an electrophotographic lithographic printing plate according to the present invention includes substantially uniformly charging in a dark place to form an electrostatic latent image by imagewise exposure, and then performing liquid development by the method described above. To do. Examples of the exposure method include reflection image exposure using a xenon lamp, a tungsten lamp, a fluorescent lamp, or the like as a light source, contact exposure through a transparent positive film, and scanning exposure using a laser beam, a light emitting diode, or the like. The light source for scanning exposure is a He-Ne laser,
Argon ion laser, krypton ion laser, ruby laser, YAG laser, nitrogen laser, dye laser, excimer laser, GaAs / GaAlAs, InGa
A laser light source such as a semiconductor laser such as AsP can be used,
Alternatively, scanning exposure using a light emitting diode or a liquid crystal shutter (including a line printer type light source using a light emitting diode array, a liquid crystal shutter array, or the like) may be performed.

Next, the electrostatic latent image is developed with a liquid developer. The toner particles used in the liquid development according to the present invention need to be composed of at least a resin component having a resist property with respect to the eluate. Examples of the resin component include acrylic resin made of methacrylic acid, acrylic acid, and esters thereof, vinyl acetate resin, copolymer of vinyl acetate and ethylene or vinyl chloride, vinylidene chloride resin, vinyl chloride resin, polyvinyl butyral. Etc., vinyl acetal resins, polystyrene, copolymers of styrene and butadiene, methacrylic acid esters, etc., polyethylene, polypropylene and its chlorides, polyester resins such as polyethylene terephthalate, polyamide resins such as polycapramide, phenol resins, xylene resins, alkyds. Examples thereof include resins, vinyl-modified alkyd resins, and other waxes. In addition, the toner may contain a dye or a charge controlling agent as long as the toner does not adversely affect development or fixing.

In the electrophotographic lithographic printing plate after the development, at least the non-image area photoconductive layer is eluted and removed by an alkaline elution solution in the elution section. The printing plate from which the non-image area photoconductive layer was eluted and removed was then rinsed to remove the solubilized photoconductive layer components remaining on the plate surface, further improving the scratch resistance of the plate surface and eliminating the non-image area For the purpose of oiling, etc., it is treated with a protective gum and then used for printing.

[0083]

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited thereby.

Example 1 A liquid developing apparatus used in the liquid developing process in Example 1 is shown in FIG. In the liquid developing apparatus shown in FIG. 1, electrodeposition for applying a voltage to a pair of aperture rolls 31, a liquid developer supply unit 28 that also serves as a means for collecting the liquid developer 2, and an upper aperture roll 32 that contacts the electrostatic latent image forming surface. An electrophotographic conductive roll 26 as means, a toner removing roll 27 as removing means for removing toner particles remaining on the upper squeeze roll 32 after squeezing the liquid developer by the squeeze roll pair 31, and an upper squeeze roll 32 and electrophotography It comprises a bias voltage applying means 41 for applying a voltage between the lithographic printing plate 1 and the metallic support. A voltage is applied between the electro-deposition conductive roll 26 and the upper squeeze roll 32 by the electro-deposition bias voltage applying means 42.

The diaphragm roll pair 31 comprises an upper diaphragm roll 32 and a lower diaphragm roll 33. The shaft 32h of the upper diaphragm roll 32 is connected to the bias voltage applying means 41 so that the bias voltage is applied. ing.
The lower squeeze roll 33 is configured to rotate by a driving unit (not shown), and the upper squeeze roll 32 is pressed at both ends in the direction of the lower squeeze roll 33. It is adapted to rotate following the rotation of 33.

The liquid developer supply means 28 comprises guide rolls 21, 22, and 23, pressure rolls 24 and 25, and a liquid developer carrying sheet 43, and the liquid developer 2 is stored below them. A liquid developer storage tank 12 is arranged. The liquid developer carrying sheet 43 is stretched endlessly by the electro-deposition conductive roll 26 and the guide rolls 21, 22, and 23, and holds the liquid developer 2 from the liquid developer storage tank 12 to the upper squeeze roll 32. The liquid developer 2 is supplied.

The liquid developer carrying sheet 43 that has passed through the liquid developer storage tank 12 is sufficiently impregnated with the liquid developer 2 and carried to the guide roll 22. The pressure roll 2 is sandwiched between the guide roll 22 and the liquid developer carrying sheet 43.
4 is provided, and this pressure roll 24 is connected to the guide roll 2
The liquid developer carrying sheet 4 is urged in the direction of 2.
The amount of the impregnated liquid developer in 3 is limited, and the amount of the liquid developer 2 supplied between the electro-deposition conductive roll 26 and the upper squeezing roll 32 is adjusted. A bias voltage is applied from the liquid developer carrying sheet 43 to the upper squeeze roll 32 by the electrodeposition bias voltage applying means 42, and when the upper squeeze roll 32 and the liquid developer carrying sheet 43 come into contact with each other, the liquid developer carrying sheet 43. The liquid developer 2 impregnated and carried on the electrode is electrodeposited on the surface of the upper squeeze roll 32, and is supplied to the developing area 90 along the surface of the upper squeeze roll 32.

Liquid developer 2 supplied to developing area 90
Is a bias voltage applying means 41 for applying a voltage between the upper squeeze roll 32 and the metallic support of the electrophotographic lithographic printing plate 1, whereby the toner particles in the liquid developer 2 are formed on the electrostatic latent image forming surface of the printing plate. While the excess liquid developer 2 is electro-deposited on the exposed portion, the excess liquid developer 2 is squeezed by the squeeze roll pair 31, and is collected by the tray 17 provided below the squeeze roll pair 31.

The liquid developer carrying sheet 43 that has passed through the upper squeeze roll 32 holds the part of the liquid developer that has not been electrodeposited on the upper squeeze roll 32, while holding the guide roll 2
After returning to the inside of the liquid developer storage tank 12 via 3 and passing through the guide roll 21 immersed in the liquid developer 2 of the liquid developer storage tank 12, the pressure roll 25 urges The liquid developer remaining on the liquid developer carrying sheet 43 is squeezed, and then the cycle in which the liquid developer 2 in the liquid developer storage tank 12 is impregnated and carried again to the guide roll 22 is repeated.

When the liquid developer 2 impregnated and carried in the liquid developer carrying sheet 43 passes between the electro-deposition conductive roll 28 and the upper draw roll 32, the upper draw roll 3
Since the surface of the liquid developer 2 is electrodeposited, the concentration of at least toner particles in the liquid developer 2 is reduced, and this is replaced by squeezing liquid and re-impregnation with the guide roll 21 and the pressure roll 25. By this cycle, the liquid developer storage tank 1
Since the concentration of at least the toner particles in 2 also decreases, by the control of the liquid developer concentration control means (not shown),
The liquid developer concentration in the liquid developer storage tank 12 is always maintained within a fixed range.

The toner removing roll 27 is a conductive roll whose surface has been subjected to an insulating treatment, is in contact with the upper squeezing roll 32, and has a conductive portion of the toner removing roll 27 and the upper squeezing roll 32. By applying a voltage by a voltage application unit (not shown), the toner particles adhering to the upper squeeze roll 32 are moved from the surface of the upper squeeze roll 32 to the surface of the toner removing roll 27 for removal. The toner particles attached to the toner removing roll 27 are scraped off by the scraping blade 8 which is in contact with the toner removing roll 27.
It is scraped off by 7 and collected in the waste toner collecting tank 88.

Liquid development of the electrophotographic lithographic printing plate 1 on which the toner image is formed is completed through a drying process and a heat fixing process which are not shown.

As an electrophotographic planographic printing plate 1, ODP.N
D-300 (manufactured by Mitsubishi Paper Mills, this printing plate is 0.3 m
An m-thick surface-treated hydrophilic aluminum support has an ink-receptive photoconductive layer, and an insulating resin is applied to the side end portions of the photoconductive layer for insulation treatment. )It was used.
The image forming surface of the electrophotographic lithographic printing plate is charged so that the charging potential becomes about +180 V in the dark, and the semiconductor laser (780
nm), scanning exposure of an image including shadow halftone dots and negative fine lines was performed, and then liquid development was performed by the above liquid developing apparatus. As the liquid developer 2, a positively chargeable liquid developer ODP
An isoparaffin-based dispersion medium IP-1620 (manufactured by Idemitsu Petrochemical Co., Ltd.) was added to TR (manufactured by Mitsubishi Paper Mills Ltd.) and diluted 5-fold.

The upper squeeze roll 32 has a diameter 54 of the rubber portion.
mm, rubber hardness 40 degrees, and the rubber material used was a roll having a volume resistance of about 10 ⁶ Ω · cm by kneading a conductive agent into NBR. On the other hand, the lower squeeze roll 33 has a rubber portion with a diameter of 36 m.
m, rubber hardness 50 degrees, and the rubber material used was a substantially non-conductive roll of NBR. Further, as the liquid developer supporting sheet 43, non-woven Sontara 8005 (manufactured by DuPont)
Was used.

The bias voltage applied by the bias voltage applying means 41 between the upper squeeze roll 32 and the metal support of the electrophotographic lithographic printing plate 1 is 50 V, and the electro-deposition conductive roll 26 and the upper squeeze roll 32 are The bias voltage applied between the electrodeposition bias voltage applying means 42 is 1
It was set to 50V. Further, the squeeze roll pair 31 of the electrophotographic planographic printing plate 1 is adjusted by adjusting a printing plate transport mechanism (not shown).
By setting the insertion angle of the liquid developer to be inclined with respect to the horizontal by 5 degrees and adjusting the amount of liquid developer 2 supplied from the liquid developer supply means 28 to the upper squeeze roll 32, the development is performed. The length of the area in which the liquid developer 2 and the electrophotographic lithographic printing plate 1 contact each other in the area 90 in the transport direction is 18 mm.

Liquid development was performed using the above-mentioned liquid development apparatus under the above-mentioned liquid development processing conditions, followed by elution and rinsing processing using an elution device (not shown), and the image quality of the obtained printing plate was evaluated. As a result, the halftone dots in the shadow area were not crushed at all, and the negative fine lines were reproduced well. Other solid images, fine line images, and halftone images were also reproduced well, and high quality images were obtained.

Example 2 In the upper squeeze roll 32 of the liquid developing apparatus used in Example 1, from the portion in contact with both ends of the electrophotographic planographic printing plate 1 in the conveying direction to the end of the roll, the roll diameter and A roll having the same rubber hardness and not subjected to a conductive treatment without kneading a conductive agent only in that portion (the roll portion in contact with the electrostatic latent image forming portion of the printing plate has the same conductivity as in Example 1). In the same manner as in Example 1 except that the electrophotographic lithographic printing plate 1 used in Example 1 was replaced with the electrophotographic lithographic printing plate before insulating treatment. An electrophotographic lithographic printing plate was prepared including a liquid development process.

Similar to the results of Example 1, the image of this plate-making product was free from the collapse of halftone dots in the shadow portion, and was well reproduced with respect to the negative fine line. Other solid images, fine line images, and halftone dot images were reproduced well, and high-quality image quality was obtained as in Example 1.

Example 3 In the liquid developing apparatus used in Example 1, the pressure roll 2 was used.
4, the amount of the liquid developer 2 supplied between the electro-deposition conductive roll 26 and the upper squeezing roll 32 is increased by relaxing the urging force of No. 4 and allowing the liquid developer supporting sheet 43 to be impregnated and supported.
An electrophotographic lithographic printing plate was prepared in the same manner as in Example 1 including a liquid development process.

As a result, the length in the conveying direction of the contact area between the liquid developer 2 and the electrophotographic lithographic printing plate 1 in the developing area 90 is 30 mm, which may be due to the edge effect after liquid development. Although the halftone dots in the shadow portion and the crushing of the negative fine line were observed, the printed image obtained by mounting the plate-making product on the printing machine was at the same level as the other portions. Other solid images, fine line images, and halftone dot images had no problem, and good image quality was obtained as in Example 1.

Example 4 Liquid development was carried out using a liquid development apparatus as shown in FIG. 2 in place of the liquid development apparatus used in Example 1. This liquid developing apparatus uses the same pair of aperture rolls 31 and bias voltage applying means 41 as the liquid developing apparatus used in the embodiment 1, and a liquid developer supplying means 45 is attached to this.
The squeeze roll pair 31 is pressed by a pressurizing means (not shown) in a direction to generate a nip pressure, and is rotated by a driving means. Bias voltage applying means 41
Is connected to a conductive shaft 32h of the upper squeeze roll 32 so that a voltage can be applied to the shaft 32h.

On the other hand, the liquid developer supply means 45 comprises a liquid developer supply pump 72, a pipe 74, and a liquid developer discharge means 80, and the liquid developer storage tank 12 is operated by the operation of the liquid developer supply pump 72. Liquid developer 2 stored in
Is supplied to the developing area 90 formed by the electrophotographic lithographic printing plate 1 and the upper squeeze roll 32 via the pipe 74 and the liquid developer discharging means 80.

The electrophotographic lithographic printing plate 1 on which the electrostatic latent image is formed is conveyed obliquely downward according to the direction of rotation of the pair of aperture rolls 31 indicated by the arrow. The liquid developer 2 supplied by the liquid developer supply means 45 is supplied to the upper squeeze roll 32.
And stays in the developing area 90 formed by the electrophotographic planographic printing plate 1. A bias voltage is applied to the conductive shaft 32h of the upper squeeze roll 32 by the bias voltage applying means 41 between the conductive shaft 32h and the metallic support of the electrophotographic lithographic printing plate 1, and the liquid developer 2 in the developing area The toner particles are adhered imagewise according to the electrostatic latent image by electrophoresis.

In the liquid developing treatment, the electrophotographic lithographic printing plate 1 and the liquid developer 2 used in Example 1 were used, and the steps before liquid developing were performed in the same manner as in Example 1. The inclination angle during transportation is set so that it is inclined 5 degrees from the horizontal,
The discharge amount of the liquid developer 2 was adjusted so that the length in the transport direction of the area where the liquid developer 2 and the electrophotographic lithographic printing plate 1 contact each other was 30 mm. Further, the bias voltage applied by the developing bias voltage applying means 41 between the upper squeeze roll 32 and the metallic support of the electrophotographic lithographic printing plate 1 is 150.
V was set.

Liquid development was performed using the above-mentioned liquid development apparatus under the above-mentioned liquid development processing conditions, followed by elution and rinsing processing using an elution apparatus (not shown), and the image quality of the obtained printing plate was evaluated. As a result, the dot diameter of the shadow area was slightly smaller, and the line width of the negative fine wire was also slightly smaller, but the print image printed by mounting the plate-making product on a printing machine is at a level similar to other areas. And there is no problem with other solid images, fine line images, and halftone images,
Similar to Example 1, good image quality was obtained.

Example 5 Liquid development was carried out using a liquid developing apparatus as shown in FIG. 3 in place of the liquid developing apparatus used in Example 4. This liquid developing device is the same as the liquid developing device used in the fourth embodiment.
The electrodeposition electrode 44 and the toner removal pad 37 are newly installed to face the upper squeeze roll 32, and the liquid developer discharging means 80 is supplied to the upper squeeze roll 32 from above the electrodeposition electrode 44. .

The electrodeposition electrode 44 is made of a conductive material, and the squeeze roll 32 is provided in a portion facing the upper squeeze roll 32.
The curvature is provided so as to face the surface with a constant gap. A voltage can be applied to the electrodeposition electrode 44 by the electrodeposition bias voltage applying means 42 between the electrodeposition electrode 44 and the upper squeeze roll 32. On the other hand, the toner removing pad 37 is formed by winding a non-woven fabric around an elastic member so that the toner particles remaining on the surface of the roll can be wiped off by coming into contact with the upper squeeze roll 32. The toner removal pad 37 contains a small amount of a solvent that dissolves the toner particles, thereby improving the toner particle removal efficiency.

When the liquid developer 2 is discharged from the liquid developer discharge means 80 to the upper slope of the electrodeposition electrode 44 by the liquid developer supply means 45, the liquid developer 2 travels along the slope and the upper squeeze roll 32. And the electrode 44 for electrodeposition. A voltage is applied between the electrodeposition electrode 44 and the upper squeeze roll 32 by the electrodeposition bias voltage applying means 42, so that the toner particles in the liquid developer 2 are electrodeposited on the surface of the upper squeeze roll 32, and the liquid Development area 9 formed by electrophotographic lithographic printing plate 1 and upper squeeze roll 32 together with developer 2.
It is designed to be supplied to 0. The electrophotographic lithographic printing plate 1 on which the electrostatic latent image has been formed is developed by the liquid developer 2 staying in the developing area 90 by passing between the squeeze roll pair 31, and a toner image is formed.

The inclination angle at the time of conveyance is set so as to be inclined by 5 degrees from the horizontal, and the ejection amount from the liquid developer ejecting means 80 and the gap between the upper squeeze roll 32 and the electrodeposition electrode 44 are adjusted. The length of the contacting area between the liquid developer 2 and the electrophotographic lithographic printing plate 1 in the transport direction was set to 25 mm. Further, the upper squeeze roll 32 and the electrophotographic lithographic printing plate 1
Developing bias voltage applying means 41 between the metallic support of
Is 50 V, and the bias voltage applied between the electrodeposition electrode 44 and the upper aperture roll 32 is 200 V.
Was set, and the electrophotographic lithographic printing plate 1 and the liquid developer 2 used in Example 5 were used, and the liquid development treatment was performed in the same manner as in Example 5 in the steps before the liquid development.

Liquid development was carried out using the above liquid development apparatus under the above-mentioned liquid development processing conditions, followed by elution and rinsing processing using an elution apparatus (not shown), and the image quality of the obtained printing plate was evaluated. As a result, the effect of the edge effect is the same as that of the fifth embodiment.
The image was further improved and the image of the halftone dots and the negative fine lines were not disturbed, and the print image printed by mounting the plate-making product on the printing machine was at the same level as the other parts. Further, other solid images, fine line images, and halftone dot images had no problem, and good image quality was obtained as in Example 1.

Example 6 The liquid developing device used in Example 1 was replaced with a liquid developing device as shown in FIG. 4 for liquid development. This liquid developing device basically has a configuration in which the upper squeeze roll 32 in the liquid developing device used in the first embodiment is replaced with an endless belt 68 and a conductive roll 67. The endless belt 68 has at least the same conductivity in the thickness direction as the upper squeeze roll 32 in the liquid developing apparatus used in the first embodiment, and is capable of absorbing and impregnating the liquid developer 2 and releasing it by pressing. It is stretched by the tension roll 39 and a conductive roll 67 which is substantially the same as the upper squeeze roll 32 in the liquid developing apparatus used in the first embodiment.

On the outer peripheral surface of the endless belt 68, a liquid developer supplying means 28 which also serves as a means for collecting the liquid developer 2 used in the liquid developing apparatus used in the first embodiment, the electroconductive conductive roll 26, and the toner. A removal roll 27 is installed. Further, a backup roll 38 is arranged on the electro-deposition conductive roll 26 and the toner removal roll 27 with the endless belt 68 interposed therebetween, and urges the electro-deposition conductive roll 26 and the toner removal roll 27.

The liquid developer 2 supplied from the liquid developer supplying means 28 to the endless belt 68 and electrodeposited is supplied to the electrophotographic lithographic printing plate 1 which is carried along with the endless belt 68 and passes over the lower squeezing roll 33. It On the other hand, since a bias voltage is applied to the electroconductive roll 67 by the bias voltage applying means 41 between the electroconductive roll 67 and the metallic support of the electrophotographic lithographic printing plate 1, the toner particles in the liquid developer 2 in the development area 90 are not removed. It is adapted to adhere imagewise by electrophoresis according to the electrostatic latent image on the surface of the printing plate.

The inclination angle at the time of conveyance is set so as to be inclined at 5 degrees from the horizontal, and this and the liquid developer supplying means 28 are set.
By adjusting the supply amount of the liquid developer 2 from the endless belt 68 to the endless belt 68, the length in the transport direction of the contact area between the liquid developer 2 and the electrophotographic lithographic printing plate 1 was set to 18 mm. Also,
The bias voltage applied by the bias voltage applying means 41 is 50 V between the conductive roll 67 and the metal support of the electrophotographic lithographic printing plate 1, and the electrodeposition between the conductive roll 26 and the ground roll 38 is electrodeposition. Bias voltage applying means 42
The bias voltage applied by was set to 150V.

The electrophotographic lithographic printing plate 1 and the liquid developer 2 used in Example 1 were used for plate making, and the above liquid developing apparatus was used in the same manner as in Example 1 for the steps before liquid development. Liquid development was performed under the development processing conditions, followed by elution and rinsing processing using an elution device (not shown), and the image quality of the obtained printing plate was evaluated. As a result, no influence of the edge effect was observed, and there was no disturbance in the image of shadow dots and negative fine lines. In addition, other solid images, fine line images, and halftone dot images had no problem, and good image quality was obtained as in Example 1.

Comparative Example The liquid developing apparatus used in Example 1 was replaced with the liquid developing apparatus as shown in FIG. The liquid development processing section 101 of this liquid development apparatus includes a development electrode section 34 composed of a development electrode 35 and a lower guide plate 36, a pair of squeeze rolls 31 'having upper and lower non-conductive roll rubber sections, and a liquid developer discharge means. The liquid developer storage tank 12 is connected to the liquid developer discharge means 80 by a pipe 74, and the liquid developer supply pump 72 is installed in the middle of the pipe 74. The liquid developer 2 stored in the liquid developer storage tank 12 is supplied between the developing electrode 35 and the lower guide plate 36 (developing electrode portion 34) through the liquid developer discharging means 80. Has become.

The electrophotographic lithographic printing plate 1 on the surface of which the electrostatic latent image is formed by being charged and laser-exposed is conveyed to the developing electrode portion by a conveying means (not shown) for conveying the plate at a constant speed in the direction of arrow B. It is conveyed into 34. Before the electrophotographic lithographic printing plate 1 enters the developing electrode section 34, the liquid developer supply pump 72 starts operating and supplies the liquid developer 2 to the developing electrode section 34. The supplied liquid developer 2 fills the gap between the electrophotographic lithographic printing plate 1 and the developing electrode 35,
After being used for toner development, it is collected again in the liquid developer storage tank 12 and circulated for use.

A bias voltage is applied to the developing electrode 35, and the liquid development filled between the developing electrode 35 and the electrophotographic lithographic printing plate 1 according to the electrostatic latent image on the printing plate and the electric field generated by the developing electrode 35. The toner particles in the agent 2 are electrophoresed and are imagewise adhered to the electrophotographic lithographic printing plate 1 according to the electrostatic latent image. After that, the electrophotographic planographic printing plate 1 was squeezed roll pair 31
The excess liquid developer 2 on the electrophotographic lithographic printing plate 1 is held by the squeeze roll pair 31 ′ by being held by the ‘′, and the electrophotographic lithographic printing plate 1 passing through the squeeze roll pair 31 ′ is The excess liquid developer 2 is sent to the next drying unit 102 in a state where most of the liquid developer 2 is removed. In the drying section, the excess dispersion medium of the liquid developer on the plate surface is dried and removed, and in the subsequent heat fixing section, the toner particles are heat-fixed,
The toner particles melt and form a film.

The distance between the developing electrode 35 and the lower guide plate 36 was set to 1.5 mm. The length of the developing electrode 35 in the transport direction is 50 mm. The bias voltage applied to the developing electrode 35 is set to 150 V, and the electrophotographic planographic printing plate 1
The inclination angle at the time of conveyance was set so as to be inclined at 5 degrees from the horizontal.

The electrophotographic lithographic printing plate 1 and the liquid developer 2 used in Example 1 were used for plate making, and the above liquid developing apparatus was used in the same manner as in Example 1 for the steps before liquid development. Liquid development was performed under the development processing conditions, followed by elution and rinsing processing using an elution device (not shown), and the image quality of the obtained printing plate was evaluated. As a result, there were no major problems with solid images, fine line images, and halftone dot images, but crushing was seen in the shadow halftone dots and negative fine lines. This crushed image was reproduced even in a printed image printed by mounting the plate-making product on a printing machine, and a plate-making product having good image quality could not be obtained.

[0121]

When the electrophotographic lithographic printing plate is liquid-developed by the plate-making method of the present invention or by the liquid-developing apparatus of the present invention to which the plate-making method of the present invention is applied, the edge effect is improved and a high quality is obtained. A plate-making product having an image quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the configuration of a liquid developing apparatus of the present invention.

FIG. 2 is a schematic diagram showing the configuration of another liquid developing apparatus of the present invention.

FIG. 3 is a schematic diagram showing the configuration of another liquid developing apparatus of the present invention.

FIG. 4 is a schematic diagram showing the configuration of another liquid developing apparatus of the present invention.

FIG. 5 is a schematic diagram showing a configuration of a conventional liquid developing apparatus.

FIG. 6 is an explanatory diagram regarding an edge effect in liquid development of an electrophotographic lithographic printing plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrophotographic lithographic printing plate 2 Liquid developer 12 Liquid developer storage tank 26 Electrodeposition conductive roll 27 Toner removal roll 28 Liquid developer supply means 31, 31 'Squeeze roll pair 32, 32' Upper squeeze roll 33 Lower side Aperture roll 35 Development electrode 36 Lower guide plate 41 Bias voltage application means 42 Electrodeposition bias voltage application means 43 Liquid developer carrying sheet 67 Conductive roll 68 Endless belt 90 Development area

Claims (12)

[Claims] 1. A liquid developer is fed while transporting an electrophotographic lithographic printing plate having an electrostatic latent image formed on the photoconductive layer of an electrophotographic lithographic printing plate having a photoconductive layer provided on a metallic support. In the liquid developing method of an electrophotographic lithographic printing plate, which is brought into contact with the electrostatic latent image forming surface, and then sandwiched between a pair of squeeze rolls to squeeze the liquid, a squeeze roll and an electrophotographic lithographic printing plate in contact with the electrostatic latent image forming surface. A liquid developing method for an electrophotographic lithographic printing plate, which comprises applying a voltage between a plate metal support and performing liquid development. 2. A liquid developer supply unit and a squeeze roll in contact with the electrostatic latent image forming surface while applying a voltage between the liquid developer supply unit and the squeeze roll in contact with the electrostatic latent image forming surface. 2. The liquid developing method for an electrophotographic lithographic printing plate according to claim 1, wherein the liquid developing agent is brought into contact with the electrostatic latent image forming surface. 3. After squeezing the liquid developer with a pair of squeezing rolls,
The liquid developing method for an electrophotographic lithographic printing plate according to claim 2, wherein at least toner particles remaining on the surface of the squeeze roll in contact with the electrostatic latent image forming surface are removed. 4. A part of the liquid developer after the liquid developer is supplied from the liquid developer supply means to the squeeze roll in contact with the electrostatic latent image forming surface and before the liquid developer comes into contact with the electrostatic latent image surface. The liquid developing method for an electrophotographic lithographic printing plate according to claim 2 or 3, wherein the liquid is collected from a squeezing roll. 5. The length of the region in which the electrophotographic lithographic printing plate is in contact with the liquid developer in the carrying direction is equal to or less than the radius of the aperture roll in contact with the electrostatic latent image forming surface. 5. A liquid developing method for an electrophotographic lithographic printing plate according to any one of 1 to 4. 6. The electrophotographic lithographic printing plate according to claim 1, wherein an electrophotographic lithographic printing plate having an insulating treatment applied to a side end portion of the electrophotographic lithographic printing plate is used. Liquid development method. 7. An insulating state is provided at least at a portion where a side end portion of the electrophotographic lithographic printing plate of the squeeze roll that contacts the electrostatic latent image forming surface contacts.
8. A liquid developing method for an electrophotographic lithographic printing plate according to any one of 1. 8. A liquid developing apparatus for an electrophotographic lithographic printing plate, which supplies a liquid developer to an electrostatic latent image forming surface of an electrophotographic lithographic printing plate on which an electrostatic latent image is formed and develops the liquid. In a liquid developing device having a developer supply means and a pair of aperture rolls, an electrophotographic lithographic printing plate characterized by further comprising voltage applying means for applying a bias voltage to the aperture roll in contact with the electrostatic latent image forming surface. Liquid developing device. 9. The electrophotographic lithographic printing plate according to claim 8, further comprising electrodeposition means for applying a voltage between the liquid developer supply means and the squeeze roll in contact with the electrostatic latent image forming surface. Liquid developing device. 10. A recovery unit for controlling the supply amount of the liquid developer supplied from the liquid developer supply unit to recover the excess liquid developer from the squeeze roll in contact with the electrostatic latent image forming surface.
10. The electrophotographic lithographic printing method according to claim 9, further comprising: a removing unit that removes toner particles remaining on the surface of the squeeze roll that is in contact with the electrostatic latent image forming surface after squeezing the liquid developer by the squeeze roll pair. Plate liquid developing device. 11. The electro-deposition means is a conductive roll, which is installed facing the squeeze roll supplying the liquid developer with a gap and is capable of applying a voltage, and the collecting means is a sheet impregnated with the liquid developer. The liquid developer for an electrophotographic lithographic printing plate according to claim 10, which is a liquid developer-impregnated sheet for supplying and recovering the liquid developer by passing it between a conductive roll and a squeezing roll for supplying the liquid developer. apparatus. 12. A liquid developing apparatus for an electrophotographic lithographic printing plate, which supplies a liquid developer to an electrostatic latent image forming surface of an electrophotographic lithographic printing plate on which an electrostatic latent image is formed to develop the liquid. In a liquid developing device for an electrophotographic lithographic printing plate having an agent supply means and a pair of squeeze rolls, the liquid developer supply means is in contact with the squeeze roll on the electrostatic latent image forming surface side, and at least the electrostatic latent image forming surface A liquid developing apparatus for an electrophotographic lithographic printing plate comprising: an endless belt whose contact surface is made of an elastic material, which holds a fixed amount of liquid developer, and voltage applying means for applying a bias voltage.