JP2012018221A - Electrophotographic developer, image forming apparatus and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid developer which is excellent in transfer property, is easily and sufficiently fixed, and is capable of forming a high-quality image.SOLUTION: A liquid developer for an adhesive transfer process contains toner particles dispersed in a liquid carrier; and the developer contains, as a toner resin component constituting the toner, a moiety derived from an acrylic ester, a moiety derived from a methacrylic ester, a moiety derived from an acryloylmorpholine, a moiety derived from a glycidyl acrylate, and a moiety derived from an acrylic acid.

Description

  The present invention relates to a liquid developer for developing an electrostatic latent image including toner particles and a liquid in which toner particles are dispersed. The liquid developer adheres toner to a latent image on a latent image carrier. It is particularly suitable for use in an image forming method in which the latent image is developed and the toner image formed on the latent image carrier is transferred with the adhesive force of the toner.

  The present invention comprises a toner containing a colorant and a liquid in which the toner is dispersed, and the latent image is developed on the latent image carrier by developing the latent image by attaching the toner to the latent image on the latent image carrier. The present invention relates to a liquid developer used in an image forming method for transferring a toner image with the adhesive force of toner.

Today, as consumers' needs are diversifying, the tendency to demand a small quantity and a wide variety of production is also becoming more prominent. Thus, attention has been paid to an electrophotographic method that does not require a costly and time-consuming plate making process as a method for meeting such requirements.
With the development of digital latent image forming technologies such as LEDs and laser beams in electrophotography, it is possible to write high-definition dot images such as 1200 DPI. An image forming method and apparatus capable of forming a fine and high quality image is desired. In order to obtain such a high-quality print, accurate reproducibility of the dot area is necessary. Toner scattering during transfer of a toner image from a latent image carrier or intermediate transfer member to an intermediate transfer member or recording medium is required. Crushing (which occurs even with heat and pressure fixing) is a major problem especially in color printing. A high-resolution toner image can be realized by reducing the particle size of the toner used. In addition, if toner with a fine particle size is used, the thickness of the toner image is reduced and the color expression in the case of obtaining a color print by color superposition is improved, and the toner image transferred onto the transfer paper as the final recording medium As the thickness of the toner is reduced in accordance with the particle diameter, the degree of curling of the transfer paper and the cracking of the toner image are also improved. As the toner, there are a powder toner used in a dry development system by friction charging with a powder carrier or the like, and a toner (hereinafter referred to as a liquid toner) used in a liquid development system by being dispersed in a solvent as a liquid carrier.

Among these, when the powder toner is a fine powder toner having a particle size on the order of 5 microns to submicron, it is difficult to suppress the toner scattering and to remove the residual toner on the photoreceptor as a latent image carrier after the transfer process. There's a problem. On the other hand, since the liquid toner is used by being dispersed in a solvent, such a problem does not occur and handling as a fine toner is easy. Therefore, compared with dry electrophotography using powder toner, it can achieve high definition as high as a method capable of printing high-definition images such as gravure printing and offset printing. it can.
Further, the lower the melting temperature of the toner is, the more advantageous for the power consumption and the higher speed, but there is a problem that powder toner having a low melting temperature causes blocking. On the other hand, since liquid toner is used by being dispersed in a solvent, a toner having a low melting point (low softening point) can be employed without such a problem.

In the conventional liquid development method, the electrostatic latent image is developed by liquid development, the transfer paper is brought into contact with the surface of the photoreceptor on which the toner image is formed, and a transfer electric field is applied to the back surface of the transfer paper by a corona discharge device, a transfer roller, or the like. Form. As a result, when an electrostatic transfer method for transferring the toner image on the photoconductor onto the transfer paper is used, the charged transfer paper may be electrostatically adsorbed to the photoconductor by being charged. there were.
Further, as a result of pressure applied by a transfer roller or the like, the toner image may be crushed, and it may be difficult to faithfully reproduce, for example, the width of a fine line or the dot area.

  Further, in the conventional liquid development image forming apparatus, since the carrier liquid is used, the image may be crushed and a high-definition image may not be obtained. A toner image composed of a developer layer containing not only toner but also carrier liquid is formed on the surface of the latent image carrier developed by the developer composed of toner and carrier liquid. In order to transfer a toner image on a latent image carrier formed by liquid development onto a recording medium or the like with an electric field, the transfer between the latent image carrier on which the transfer electric field is formed and a transfer partner such as a recording medium is performed. That is, an appropriate amount of carrier liquid is necessary for the transfer gap.

  However, if the carrier liquid is excessive, the toner image such as dots and lines may be crushed, the line width may be widened, and the image density may be uneven. The toner image formed on the latent image carrier It is difficult to faithfully transfer to a recording medium. This is because when the carrier liquid is excessively present on the surface of the latent image carrier, the electric field is insufficient at the same transfer potential difference as when the carrier liquid is small, and the toner constituting the toner image on the surface of the latent image carrier at the time of transfer is This is thought to be due to the inability to move faithfully to the latent image. In order to form a necessary electric field according to a large amount of carrier liquid, a problem that requires a higher voltage occurs.

  In addition, various types of recording media used for printing have been required. As a recording medium, not only plain paper, but also coated paper or resin film coated with white clay called `` clay '' on the surface to give gloss or smoothness to the paper surface It is expected to be used. Coated paper and resin films do not absorb the carrier liquid at all or absorb less than plain paper because of the surface smoothness and material characteristics. For this reason, the transfer state may occur as in the case where the carrier liquid in the transfer gap is large, and the image may be crushed.

  In order to solve such a problem, some conventional liquid development image forming apparatuses include a squeeze roller that removes excess liquid carrier from the surface of the latent image carrier. The configuration including the squeeze roller includes a method of rotating the surface of the latent image carrier so that the surface moves in the opposite direction with a predetermined distance from the surface of the latent image carrier. There has been proposed a method in which a roller provided with a potential difference not to be removed is brought into contact with a toner image and a carrier liquid is adhered to remove the toner image.

  Further, as a method for preventing the collapse, a roller to which a voltage is applied is opposed to the surface of the toner image on the latent image carrier with a gap so that the toner image formed on the latent image carrier is cured. There is a method of transferring the toner image to a recording medium later (for example, Patent Document 1 and Patent Document 2).

  Patent Document 3 proposes a method for electrostatic transfer by supplying a non-aqueous solvent to a recording medium after transfer after drying a toner image on a latent image carrier or an intermediate transfer member. ing. By drying, the carrier liquid present between the toner particle particles forming the toner image evaporates and the toner particles aggregate, thereby increasing the interaction between the toner particles and supplying a non-aqueous solvent. Electric field transfer. When transferring to a transfer material, toner particles do not behave individually and transfer as aggregates of toner particles, so that toner images can be prevented from being crushed and spread, and high-resolution images with high resolution can be obtained. it can.

  However, even when such a method for preventing crushing is used, when electrostatic transfer is performed by the liquid development method, the toner moves from the surface of the latent image carrier to the recording medium so that the toner migrates in the liquid. Therefore, a liquid is required between the latent image carrier and the recording medium. In addition, there is a problem that the liquid is crushed or the liquid is in the paper and the paper is swollen to disturb the image.

Therefore, there are methods described in Patent Documents 4 and 5 for performing transfer by a liquid developing method other than an electrostatic method. In Patent Document 5, there is a method called adhesive transfer, offset transfer, or the like in which the adhesiveness of the toner is increased by adjusting the glass transition temperature and the drying degree of the carrier liquid, and transferring with the adhesive force. When the toner image is self-fixed, a rapid film formation is performed, and the toner image that becomes a film and behaves integrally is transferred by its adhesive force. Thus, if the transfer is performed with the adhesive force of the toner, the liquid other than the toner can be eliminated as much as possible before the transfer, and the image can be transferred satisfactorily without being crushed or left behind.
However, even with the method described in Patent Document 4, a part of the toner image sometimes remains on the surface of the photosensitive member during transfer. This occurs because, even in a toner image formed on a film, the connection between the toner particles is weak, and a part of the toner image is peeled off from the film-like toner image and remains on the surface of the photoreceptor. When a part of the toner image remains on the surface of the photoreceptor, the image of that part is lost.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid developer that has excellent transferability, is easily and sufficiently fixed, and can form a good image. Another object of the present invention is to provide a liquid developer for adhesive transfer that can be used in an image forming method in which a toner image formed on a latent image carrier is transferred with the adhesive force of toner and can prevent an image from being lost during transfer. is there.
In particular, good transferability can be obtained regardless of the characteristics (resistance value, etc.) and surface properties (irregularities, etc.) of the transfer substrate, and fixing is also performed by removing the carrier in the toner layer by squeezing after development without heating. It is to provide an electrophotographic liquid developer and an image forming method therefor, in which the toner is pressed and fixed onto a transfer medium with a pressure roller.
In order to realize non-heating adhesive transfer, it is important that when the carrier solvent occurs, the toner layer exhibits adhesiveness and the toner layer is integrally transferred. Even if the toner layer is sticky, if it is divided in the toner layer, the transfer rate decreases, and the target image density cannot be obtained.
One of the purposes is to perform transfer such as A and B instead of divided transfer such as C and D in FIG.
It is also important that the final fixed image does not remain sticky. Therefore, it is possible to provide a liquid developer that exhibits adhesiveness when a certain amount of carrier solvent is removed during transfer, and that the toner layer is integrally transferred and finally forms an image having no adhesiveness. Is one of the further objects of the present invention.

The above problems are solved by the present inventions (1) to (9) described below.
(1) “In the electrophotographic liquid developer containing toner particles dispersed in a liquid carrier, as a toner resin component constituting the toner, a site derived from the monomer A represented by the general formulas (1) to (5), a monomer A liquid developer for adhesive transfer comprising a site derived from B, a site derived from monomer C, a site derived from monomer D, and a site derived from monomer E.

（ＲはＨ又はＣＨ_３を表わし、ＲがＨの場合ｎ：６〜９であり、ＲがＣＨ_３の場合ｎ：１０〜１４である）

(R represents H or CH ₃ , n is 6 to 9 when R is H, and n is 10 to 14 when R is CH ₃ )

（ｎは６〜８である。）

(N is 6-8.)

（ＲはＨ又はＣＨ_３を表わす。）

(R represents H or CH ₃ )

（ＲはＨ又はＣＨ_３を表わす。）

(R represents H or CH ₃ )

（ＲはＨ又はＣＨ_３を表わす。）。
（２）「前記樹脂のモノマー成分由来の部位比がモノマーＡ／モノマーＢ／モノマーＣ／モノマーＤ／モノマーＥ＝３〜３０ｍｏｌ％／４０〜９０ｍｏｌ％／１〜３０ｍｏｌ％／１〜３０ｍｏｌ％／１〜３０ｍｏｌ％であることを特徴とする前記（１）項に記載の粘着転写用液体現像剤。」
（３）「前記樹脂のモノマー成分由来の部位比がモノマーＡ／モノマーＢ／モノマーＣ／モノマーＤ／モノマーＥ＝５〜２０ｍｏｌ％／４０〜８０ｍｏｌ％／２〜２０ｍｏｌ％／２〜１６ｍｏｌ％／２〜２５ｍｏｌ％であることを特徴とする前記（２）項に記載の粘着転写用液体現像剤。」
（４）「前記樹脂の重量平均分子量Ｍｗが２００００〜５００００、数平均分子量Ｍｎが１００００〜４００００であることを特徴とする前記（１）項乃至（３）項のいずれかに記載の粘着転写用液体現像剤。」
（５）「前記樹脂の体積抵抗が１×１０^１０〜１×１０^１６Ω・ｃｍであることを特徴とする前記（１）項乃至（４）項のいずれかに記載の粘着転写用液体現像剤。」
（６）「前記トナー粒子が着色剤及び樹脂を含有するものであることを特徴とする前記（１）項乃至（５）項のいずれかに記載の粘着転写用液体現像剤。」
（７）「前記液状担体中に分散されたトナー粒子を静電潜像に静電気的に付着させて可視像化後、トナーの粘着力により基材に非加熱で転写を行う電子写真粘着転写技術に使用されるものであることを特徴とする前記（１）項乃至（６）項のいずれかに記載の粘着転写用液体現像剤。」
（８）「静電潜像担持体上に静電潜像を形成する静電潜像形成手段と、当該静電潜像担持体上に形成された静電潜像にトナー粒子を含有する粘着転写性液体現像剤を供給して、当該静電潜像をトナー像化する現像手段と、当該トナー像が形成された静電潜像担持体に付着した前記現像剤中の液体担体の一部を当該静電潜像担持体から除去する余剰液除去手段と、当該液体担体の一部が除去された静電潜像担持体上のトナー像を転写基材上に転写する転写手段とを備えた画像形成装置において、前記粘着転写性液体現像剤は前記（１）項乃至（６）項のいずれか１項記載の粘着転写性液体現像剤であることを特徴とする画像形成装置。」
（９）「静電潜像担持体上に静電潜像を形成する静電潜像形成工程と、当該静電潜像担持体上に形成された静電潜像にトナー粒子を含有する粘着転写性液体現像剤を供給して、当該静電潜像をトナー像化する現像工程と、当該トナー像が形成された静電潜像担持体に付着した前記現像剤中の液体担体の一部を当該静電潜像担持体から除去する余剰液除去工程と、当該液体担体の一部が除去された静電潜像担持体上のトナー像を転写基材上に転写する転写工程とを備えた画像形成方法において、前記粘着転写性液体現像剤は、前記（１）項乃至（６）項のいずれか１項記載の粘着転写性液体現像剤であることを特徴とする画像形成方法。」

(R represents H or CH ₃ ).
(2) “The ratio of the parts derived from the monomer component of the resin is monomer A / monomer B / monomer C / monomer D / monomer E = 3 to 30 mol% / 40 to 90 mol% / 1 to 30 mol% / 1 to 30 mol% / 1. The liquid developer for pressure-sensitive adhesive transfer according to item (1), characterized in that it is ˜30 mol%. ”
(3) “The ratio of the parts derived from the monomer component of the resin is monomer A / monomer B / monomer C / monomer D / monomer E = 5 to 20 mol% / 40 to 80 mol% / 2 to 20 mol% / 2 to 16 mol% / 2. The liquid developer for adhesive transfer according to item (2), characterized in that it is ˜25 mol%. ”
(4) “Adhesive transfer according to any one of (1) to (3) above, wherein the resin has a weight average molecular weight Mw of 20,000 to 50,000 and a number average molecular weight Mn of 10,000 to 40,000. Liquid developer. "
(5) The liquid development for adhesive transfer according to any one of (1) to (4) above, wherein the volume resistance of the resin is 1 × 10 ¹⁰ to 1 × 10 ¹⁶ Ω · cm. Agent. "
(6) “The liquid developer for adhesive transfer according to any one of (1) to (5) above, wherein the toner particles contain a colorant and a resin.”
(7) “Electrophotographic adhesive transfer in which toner particles dispersed in the liquid carrier are electrostatically attached to an electrostatic latent image to be visualized, and then transferred to the substrate without heating by the adhesive force of the toner. The liquid developer for pressure-sensitive adhesive transfer as described in any one of (1) to (6) above, which is used in technology.
(8) “An electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and an adhesive containing toner particles in the electrostatic latent image formed on the electrostatic latent image carrier. A developing means for supplying a transferable liquid developer to convert the electrostatic latent image into a toner image, and a part of the liquid carrier in the developer attached to the electrostatic latent image carrier on which the toner image is formed A surplus liquid removing means for removing the toner from the electrostatic latent image carrier, and a transfer means for transferring the toner image on the electrostatic latent image carrier from which a part of the liquid carrier has been removed onto a transfer substrate. In the image forming apparatus, the adhesive transferable liquid developer is the adhesive transferable liquid developer according to any one of (1) to (6).
(9) “An electrostatic latent image forming step of forming an electrostatic latent image on the electrostatic latent image carrier, and an adhesive containing toner particles in the electrostatic latent image formed on the electrostatic latent image carrier. A developing step of supplying a transferable liquid developer to convert the electrostatic latent image into a toner image, and a part of the liquid carrier in the developer attached to the electrostatic latent image carrier on which the toner image is formed An excess liquid removing step for removing the toner from the electrostatic latent image carrier, and a transfer step for transferring the toner image on the electrostatic latent image carrier from which a part of the liquid carrier has been removed onto a transfer substrate. In the image forming method, the adhesive transferable liquid developer is the adhesive transferable liquid developer described in any one of (1) to (6).

As will be understood from the following detailed and specific description, according to the present invention, an electrophotographic liquid developer capable of forming a high-definition image on a low-resistance substrate or an uneven substrate is provided. When this liquid developer is used for adhesive transfer to transfer an image by adhesive force, the image can be integrated and transferred, so that a high-definition image can be formed on a substrate with low resistance or unevenness. The effect of being able to create an image is demonstrated.
That is, the liquid developer of the present invention, and the image forming method and the adhesive transfer method integrated with the liquid developer according to the present invention enable good charge controllability and non-heated adhesive transfer property and enable high image density printing. Since the toner layer is integrated and transferred without being restricted by the material (resistance value, etc.) of the material, good transfer can be performed even on uneven substrates. Monomer A for imparting adhesiveness during transfer (site A after becoming a polymer), increasing affinity with solvent in toner, improving dispersion stability of toner, and improving adhesiveness after fixing Monomer B for suppressing (site B after becoming a polymer), promoting the film formation of the toner layer, transferring the toner layer integrally at the time of transfer, and strengthening the toner layer film after fixing Monomer C (site B after becoming a polymer), resin skeleton grafted to a cross-linked structure, the toner layer film strength at the time of transfer is increased, or the monomer D (to the polymer to be adsorbed and integrated with the colorant) The specific composition ratio of the monomer E (the site E after becoming a polymer) that acts on the formation of the cross-linked structure after the formation of the structure and the transfer of the toner layer to the film by the hydrogen bond of the carboxylic acid Because it is a combination of Is one that uses a resin component with a specific molecular structure of a specific coordination that exhibits these functions to the maximum, and therefore has the extremely excellent effect that the problem solving of the present invention can be achieved smoothly and sufficiently. Played.

FIG. 6 is a schematic diagram illustrating transfer of integrated toner according to the present invention. The assumption apparatus of the volume resistance of resin used by this invention is shown. 1 shows an example of an image forming apparatus of the present invention. Another example of the image forming apparatus of the present invention is shown. Another example of the image forming apparatus of the present invention will be described.

  In order to achieve the object of the present invention, as described above, in the electrophotographic liquid developer including toner particles dispersed in a liquid carrier, the following general formula ( 1) to (5), the site derived from the monomer A, the site derived from the monomer B, the site derived from the monomer C, the site derived from the monomer D, and the site derived from the monomer E. .

（ＲはＨ又はＣＨ_３を表わし、ＲがＨの場合ｎ：６〜９であり、ＲがＣＨ_３の場合ｎ：１０〜１４である）

(R represents H or CH ₃ , n is 6 to 9 when R is H, and n is 10 to 14 when R is CH ₃ )

（ｎは６〜８である。）

(N is 6-8.)

（ＲはＨ又はＣＨ_３を表わす。）

(R represents H or CH ₃ )

（ＲはＨ又はＣＨ_３を表わす。）

(R represents H or CH ₃ )

（ＲはＨ又はＣＨ_３を表わす。）。

(R represents H or CH ₃ ).

  In the present invention, the part derived from the monomer A contained in the adhesive transfer liquid developer imparts adhesiveness at the time of transfer, and the part derived from the monomer B enhances the affinity between the toner and the solvent, thereby developing the liquid. Improves the dispersion stability of the toner in the agent. Further, the site derived from the monomer C has an effect of accelerating the formation of the toner layer into a film and integrally transferring the toner layer during transfer or strengthening the toner layer coating after fixing. As a result of intensive studies by the present inventors, a conventional liquid developer for adhesive transfer is obtained by forming a polymer in which the monomer C is hanging and graft polymerized where the monomer A and the monomer B are copolymerized. It has been found that a film-like toner image can be formed which is less prone to chipping of the toner image.

However, since the monomer C cannot be directly graft-polymerized to the polymer in which the monomer A and the monomer B are copolymerized, the monomer D and the monomer E play a connecting role. That is, in order to avoid the copolymerization of the monomer C to the monomer A or the monomer B, or the polymerization of the monomers C as much as possible, and to establish the coordination structure as described above, for example, a connection structure of the monomer D and the monomer E is formed. Or at substantially the same time as the formation of the tether structure, monomer C can be added to the reaction system and bonded to the tether structure.
As described above, according to the present invention, as the resin component of the toner, each part derived from the monomer A, the monomer B, the monomer C, the monomer D, and the monomer E is used to form an image that is transferred with the adhesive force of the toner. When used in the method, there is an excellent effect that an image can be prevented from being lost during transfer.

  Such monomers include hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, decyl methacrylate, undecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, tetradecyl methacrylate and the like for monomer A, and hexyl methacrylate for monomer B. Examples of the acrylate, heptyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, the monomer C include acryloyl morpholine and methacryloyl morpholine, and the monomer D includes glycidyl acrylate and glycidyl methacrylate. Examples of the monomer E include acrylic acid and methacrylic acid.

  The monomer A imparts adhesiveness at the time of transfer, and if it is less than 3 mol% in the components of the synthetic resin, the adhesive force is insufficient and the adhesive transferability tends to be lowered. If the amount of the monomer A is more than 30 mol%, the effect of forming a film on the toner layer is hindered, and it is liable to cause a problem that the printed surface is separated even after fixing or separated in the toner layer at the time of adhesive transfer. Therefore, the monomer A is desirably 3 mol% to 30 mol%, and more desirably 5 mol% to 20 mol%, in the resin component.

  Monomer B has the effect of increasing the affinity with the solvent in the toner, improving the dispersion stability of the toner, and suppressing the adhesiveness after fixing. When the monomer B is less than 40 mol%, the effect of dispersion stability is lowered, and when it is more than 90 mol%, the tackiness tends to be lowered and the adhesive transferability tends to be inhibited. For this reason, the monomer B is desirably 40 mol% to 90 mol%, and more desirably 40 mol% to 80 mol%, in the resin component.

  The monomer C has an effect of promoting the film formation of the toner layer, integrating the toner layer during transfer, and strengthening the toner layer film after fixing. If it is less than 1 mol%, the film-forming effect is small and transfer failure occurs, or the fixing strength is lowered. If it is more than 30 mol%, the affinity with the solvent is lowered and aggregation may occur. Therefore, the monomer C is preferably 1 mol% to 30 mol%, and more preferably 2 to 20 mol%.

  Monomer D has the effect that the resin skeleton is grafted and crosslinked to increase the strength of the toner layer film at the time of transfer or to be adsorbed and integrated with the colorant. If it is less than 1 mol%, the effect is small, and if it is 30 mol% or more, the solvent affinity tends to decrease. For this reason, the monomer D is desirably 1 mol% to 30 mol%, and more desirably 2 to 16 mol%.

Monomer E reacts with monomer D to affect the formation of a cross-linked structure, or film integration transfer of the toner layer by hydrogen bonding of the remaining carboxylic acid (which has not been subjected to addition ring-opening reaction of monomer D to the epoxy group) Has an effect on sex. If it is less than 1 mol%, the effect is small, and if it is 30 mol% or more, the solvent affinity is lowered. Therefore, the monomer E is desirably 1 mol% to 30 mol%, and more desirably 2 to 25 mol%.
However, the total amount of monomer A, monomer B, monomer C, monomer D, and monomer E is naturally 100 mol%.
As for Tg (glass transition point) of resin obtained by these monomers, -20-30 degreeC is preferable. If the temperature is lower than -20 ° C, the image remains sticky even after fixing.
Moreover, although the structure of resin changes with polymerization methods, the following general formula (6) is mentioned as an example.

The weight average molecular weight Mw of the resin is preferably 10,000 to 100,000, and the number average molecular weight Mn is preferably 10,000 to 80,000. Furthermore, Mw is particularly preferably 20000 to 50000, and the number average molecular weight Mn is particularly preferably 10,000 to 40000. When Mw is less than 10000 and Mn is less than 10000, adhesive transferability and toner cohesive force at the time of transfer are lowered, and when Mw is 100,000 or more and Mn is 80000 or more, dispersion stability is lowered.
When a part of the resin is grafted with monomers D and E to form a cross-linked structure, the cohesive strength of the toner layer is increased, and even if there is a solvent, good adhesive transferability can be exhibited.

Further, the volume resistance of the resin is preferably 1 × 10 ¹⁰ to 1 × 10 ¹⁶ Ω · cm. When the toner is less than 1 × 10 ¹⁰ , developability deteriorates. On the other hand, if it is higher than 1 × 10 ¹⁶ Ω · cm, the toner is poorly charged. Here, the volume resistance of the resin is measured by using the apparatus shown in FIG. 2 when a resin as a measurement object is filled in a 2 cm × 2 cm electrode plate and a cell 5 having a distance between electrodes of 5 mm and a voltage of 500 V is applied. It was calculated from the current value flowing through the following formula.

Volume resistance (Ω · cm) = (applied voltage (500 V) / current value) × (electrode area (2 cm × 2 cm) / distance between electrodes (0.5 cm))

  The ratio between the colorant and the synthetic resin of the present invention is preferably 1/1 to 1/5. When the ratio of the synthetic resin is less than 1/1, the adhesive transferability is lowered, and when it is more than 1/5, the toner coloring power is lowered.

As the colorant, general inorganic / organic pigments and dyes can be used.
For example, Printex V, Printex U, Printex G, Special Black 15, Special Black 4, Special Black 4-B (manufactured by Degussa), Mitsubishi # 44, # 30, MR-11, MA-100 (and above) (Mitsubishi Kasei Co., Ltd.), Raven 1035, Raven 1252, NEWSPECT II (Columbia Carbon), Legal 400, 660, Black Pearl 900, 1100, 1300, Mogal L (Cabot), and other inorganic pigments, phthalocyanine Blue, phthalocyanine green, sky blue, rhodamine rake, malachite green rake, methyl violet rake, peacock blue rake, naphthol green B, naphthol green Y, naphthol yellow S, naphthol red, resolf Toast Yellow 2G, Permanent Red 4R, Brilliant First Scarlet, Hansa Yellow, Benzidine Yellow, Resol Red, Lake Red C, Lake Red D, Brilliant Carmine 6B, Permanent Red F5R, Pigment Scarlet 3B Indigo, Thioindigo Oil Pink and Bold-10B, etc. Organic pigments, Disperse Fast Yellow G, Disperse Blue FFR, Disperse Blue Green B, Disperse Yellow 5G, Disperse Red FB, Reactive Orange 2R, Reactive Red 3B, Reactive Blue 3G, Reactive Brilliant Blue R And dyes such as Reactive Black B. These colorants preferably have a high purity, and more preferably 80% or more.

Further, when it is desired to control the polarity and resistance of the colorant, flushing the colorant is also effective for controlling the chargeability of the toner particles. In the flushing process, a resin dispersion medium is further added to a water-containing liquid in which a pigment is dissolved in water, and the mixture is mixed well in a kneader called a flasher, and water existing around the pigment is replaced by a resin dispersion medium added later. The process to do.
The water taken out by this operation is discharged, the pigment is dispersed in the resin solution, dried, the solvent is removed, and the resulting mass is pulverized to obtain a colorant powder.
The ratio of the colorant to the resin during the flushing is suitably 10 to 60 parts by weight of the colorant with respect to 100 parts by weight of the resin. It is particularly advantageous to perform the flushing treatment in the presence of humic acid, a humic acid salt (Na salt, NH ₄ salt etc.) or a humic acid derivative. The amount of these humic acids added is suitably about 0.1 to 30% by weight of the colorant-containing liquid.
The resin used in the flushing treatment is preferably a polyester resin, an epoxy resin, a polyolefin resin, or the like.

  As the carrier liquid used in the liquid developer of the present invention, a high resistance and low dielectric constant is preferable, and isoparaffin hydrocarbon, liquid paraffin, polyalphaolefin, silicone oil and the like are preferable. Isoparaffin hydrocarbons are Isopar C, Isopar E, Isopar G, Isopar H, Isopar L, Isopar M, Isopar V, Solvesso 100, Solvesso 150, Solvesso 200, Exor 100/140, Exor D30, Exor D40, Exor D80, Exol D110, Exol D130 (exxonmobile) etc., liquid paraffin is Christol J52, J72, J102, J142, J172, J202 (above Esso Petroleum) etc., polyalphaolefin is Syn2, Syn4, Syn6. (Exxon Mobil Co., Ltd.) and other silicone-based oils include KF96 1-10000 cst (Shin-Etsu Silicone), SH200, SH344 (Toray Silicone), TSF451 Toshiba silicone), and the like.

  The ζ potential of the toner is preferably 10 to 200 mV. When the zeta potential is lower than 10 mV, the toner particles aggregate, electrophoretic properties are deteriorated and the soiling is caused, and the density is lowered. On the other hand, if the ζ potential is higher than 200 mV, the adhesion amount of the photosensitive member may decrease and the density may decrease.

  The average particle size is preferably 0.1 to 3 μm. If the particle size is 0.1 μm or less, sufficient density may not be obtained or blurring may occur easily. If the particle size is 5 μm or more, the color and resolution will deteriorate. There is.

  The liquid developer of the present invention exhibits adhesiveness by increasing the solid content in the developing process and the liquid removing process, and enables adhesive transfer. After the adhesive transfer and fixing to the substrate, the solvent disappears, so the adhesiveness is lost.

[Image forming apparatus and image forming method]
FIG. 3 is a diagram showing a schematic configuration of the image forming apparatus according to the first embodiment of the present invention. The image forming apparatus (10) according to the first embodiment includes a charging voltage applying member (12) such as a charging charger, a developing device (11) around a drum-shaped photoconductor (11) as an electrostatic latent image carrier. 13), a squeeze roller (14), a transfer roller (15), a transfer substrate separating roller (16), a cleaning blade (17), and a cleaning roller (18). Further, this image forming apparatus (10) is an exposure apparatus (not shown) that irradiates the photoreceptor (11) with exposure (L) corresponding to image information, and exposure that neutralizes charges remaining on the surface of the photoreceptor (11). A neutralization device (not shown) for irradiating (E) and a blower (B) for drying and removing a part of the liquid carrier in the developer applied on the photoreceptor (11) are also provided.

When an image is formed on a transfer substrate (P) such as transfer paper by such an image forming apparatus, a charging voltage applying member (on the surface of the photoreceptor (11) that is driven to rotate in the direction of the arrow (A) ( 12) uniformly charges the surface of the photoconductor 11 to give a charge, and exposure (L) erases the charge in the non-image area. As the photoconductor (11), a selenium photoconductor, an organic photoconductor, or an amorphous silicon photoconductor can be used. The surface potential of the photoreceptor is good in the range of 400V to 1600V.
Toner particles are supplied to the electrostatic latent image on the photosensitive member (11) where electric charges remain by the liquid developer (D) supplied from the developing roller (13a) rotating in the arrow (B) direction of the developing device (13). Then, a toner image is formed and developed. Thereafter, the excess developer (D) is removed by the squeeze roller (14), and the toner image is transferred to the transfer substrate P by the adhesive force of the toner particles. In this case, the transfer pressure applied by the transfer roller (16) is preferably 0.1 to 10 kg / cm ² .

  The developing roller (13a) rotates in the forward direction with the photoconductor (11), and the squeeze roller (14) rotates in the direction opposite to the photoconductor (11). In this case, the effective linear speed for the photosensitive member (11) is 1.2 to 6 times for the developing roller (13a), and 1.2 to 4 times for the squeeze roller (14). A gap (G1) is formed between the developing roller (13a) and the photosensitive member (11), and the liquid developer supplied between the developing roller (13a) and the surface of the photosensitive member (11). (D) is applied and formed in a predetermined thickness on the surface of the photoreceptor (11) through the gap (G1). The gap (G1) between the developing roller (13a) and the surface of the photoreceptor (11) is recommended to be 50 to 250 μm.

  Since the toner particles in the liquid developer (D) supplied to the surface of the photoreceptor (11) by the developing roller (13a) are electrostatically attracted to the surface side of the photoreceptor (11), The liquid developer (D) on the side separated from the surface of the photoreceptor (11) is mainly composed of a liquid carrier. The liquid carrier in the liquid developer (D) on the side separated from the surface of the photoconductor (11) is removed from the surface of the photoconductor (11) by a squeeze roller (14) that rotates in reverse to the photoconductor (11). Thus, in order to remove the liquid carrier in the liquid developer (D) on the side separated from the surface of the photoreceptor (11) from the surface of the photoreceptor (11), the squeeze roller (14) and the photoreceptor (11). A gap (G2) is also formed between the surface and the surface. The gap (G2) is preferably 30 to 150 μm. After the developer (D) that has not been transferred and remains on the photoconductor (11) is removed by the cleaning blade (17) and the cleaning roller (18), the photoconductor (11) is discharged and the surface of the photoconductor (11) is removed. Set to the initial state. In this embodiment, as the exposure (L), the charge of the image portion is left and the charge of the non-image portion is erased. However, the image development method that erases the charge of the image portion and leaves the charge of the non-image portion is similarly used. Can be formed.

  FIG. 4 is a diagram showing a schematic configuration of an image forming apparatus according to the second embodiment of the present invention. The image forming apparatus (20) according to the second embodiment is an example in which an intermediate transfer roller (21) is added as an intermediate transfer member to the image forming apparatus (10) according to the first embodiment shown in FIG. In the image forming apparatus (20) according to the second embodiment, an intermediate transfer roller (21) rotating in the direction of arrow (F) is used. The toner image formed on the surface of the photoconductor (11) is transferred to the surface of the intermediate transfer roller (21), and the toner image transferred to the surface of the intermediate transfer roller (21) is in the direction indicated by the arrow (H). Is transferred by a transfer roller (22) onto a transfer substrate (P) conveyed to the substrate. In this embodiment, as the squeeze roller, the squeeze roller (14a) for removing a part of the developer (D) without contacting the surface of the photoreceptor (11) and the surface of the photoreceptor (11) are in contact. Further, a squeeze roller (14b) for removing the liquid carrier in the developer (D) is used.

The material of the intermediate transfer roller (21) is preferably a solvent-resistant and elastic material such as urethane rubber, nitrile rubber, hydrin rubber, and more preferably coated with a fluororesin. In the image forming apparatus (20) according to the second embodiment, a higher transfer pressure can be applied than in the image forming apparatus (10) according to the first embodiment shown in FIG. In this case, when a material having a low surface energy such as a fluororesin is used for the surface of the intermediate transfer roller (21), there is an advantage that high solid differentiation can be performed when the toner image is transferred to the intermediate transfer roller (21). The adhesive transferability is improved as compared with the image forming apparatus (10) according to the first embodiment. In this case, the primary transfer for transferring the toner image from the photoreceptor (11) to the intermediate transfer roller (21) uses electrostatic transfer of 100V to 1000V, the primary transfer pressure is 0.1 to 3 kg / cm ² , and the intermediate transfer. The secondary transfer pressure for transferring the toner image from the roller (21) to the transfer substrate P is preferably from 0.1 to 30 kg / cm ² .

  FIG. 5 is a diagram showing a schematic configuration of an image forming apparatus according to the third embodiment of the present invention. The image forming apparatus (30) according to the third embodiment includes a liquid developer (from the developing roller (13a) to the surface of the photoreceptor (11) in the image forming apparatus (10) according to the first embodiment shown in FIG. The developing device (13) for supplying D) is changed. That is, the liquid developer (D) is pumped from the container (13d) storing the liquid developer (D) by the pumping roller (13c), and the liquid developer (D) pumped by the pumping roller (13c) is supplied to the supply roller (13). 13b), a liquid developer (D) having a predetermined thickness is transferred from the supply roller (13b) to the developing roller (13a), and the liquid developer (D) having a predetermined thickness is transferred from the developing roller (13a) to the photosensitive roller. It is designed to be supplied to the surface of the body (11). By using such a developing device (13), it is possible to supply and develop the liquid developer (D) in a thin layer on the surface of the photoreceptor (11). In this case, the layer thickness of the liquid developer (D) formed on the surface of the photoreceptor (11) is preferably about 1 to 15 μm, and preferably 3 to 10 μm. If the layer thickness is 1 μm or less, the density is not sufficient, and if it is 15 μm or more, the resolution is lowered.

  In the image forming apparatus (30) according to the third embodiment, the liquid carrier removing roller (23) is used to remove the liquid carrier of the liquid developer (D) adhered on the intermediate transfer roller (21). ) Is disposed to face the surface of the intermediate transfer roller (21). By disposing such a liquid carrier removing roller (23), it is possible to more appropriately adjust the degree of adhesion of the toner image transferred onto the transfer substrate (P).

  The image forming apparatus (30) according to the third embodiment is basically the same as the image forming apparatus (20) according to the second embodiment and the method of forming an image on the transfer substrate (P). The description is omitted. In the image forming apparatus (30) according to the third embodiment, the electrostatic charge image liquid toner layer (liquid developer (D)) formed on the developing roller (13a) is subjected to electrostatic discharge after corona discharge. By developing the latent image, the cohesive force of the toner particles can be improved and the resolution can be increased. This corona discharge is highly effective when it has the same polarity as the toner particles, and the voltage is preferably about 500 to 8000V.

[Developer preparation]
The electrophotographic liquid developer can be charged, dispersed, and kneaded by adding a colorant, resin, and carrier liquid to a dispersing machine such as a ball mill, a kitty mill, a disk mill, and a pin mill.
The ratio of a general material is 5 to 20% by mass of the colorant, 5 to 40% by mass of the resin, 65 to 95% by mass of the carrier liquid, and 0.1 to 1% by mass of the charge control agent.
This developer is used as it is or after being diluted to an appropriate ratio and is put in an image forming machine to form an image.

  Next, specific examples in this embodiment will be described. In addition, this invention is not limited to the following Example at all.

(Resin synthesis example 1)
A 0.5 L flask equipped with a stirrer, thermometer, condenser, and dropping funnel was charged with 300 g of ISOPAR H, heated to 88 ° C. and stirred with 0.02 mol of lauryl methacrylate (monomer A), 2-ethylhexyl methacrylate ( A monomer solution consisting of 0.26 mol of monomer B), 0.04 mol of glycidyl methacrylate (monomer D), 0.01 mol of methacrylic acid, and 1 g of benzoyl peroxide (reaction initiator) was added dropwise over 2 hours. After the dropping, polymerization was carried out for 5 hours while maintaining at 88 ° C.
Thereafter, a monomer solution consisting of 0.08 mol of acryloylmorpholine (monomer C) and 0.3 g of azbisisobutyronitrile (reaction initiator) was added dropwise over 1 hour, and polymerization was carried out for 1 hour while maintaining at 81 ° C.
The polymerization rate of the synthesized resin was 93%, the molecular weight Mn was 36000, and Mw was 47000.

(Resin synthesis example 2)
A 0.5 L flask equipped with a stirrer, thermometer, condenser, and dropping funnel was charged with 320 g of Cristol J72, heated to 94 ° C. and stirred with 0.07 mol of tridecyl methacrylate (monomer A), heptylmeta Acrylate (monomer B) 0.14 mol, acryloylmorpholine (monomer C) 0.02 mol, glycidyl methacrylate (monomer D) 0.06 mol, methacrylic acid (monomer E) 0.06 mol, benzoyl peroxide (reaction initiator) 1 g The monomer solution consisting of was added dropwise over 3 hours. After the dropwise addition, polymerization was carried out for 5 hours while maintaining at 90 ° C.
The polymerization rate of the synthesized resin was 95%, the molecular weight Mn was 11000, and Mw was 21000.

(Resin synthesis example 3)
Into a 0.5 L flask equipped with a stirrer, thermometer, condenser, and dropping funnel was charged 270 g of Exol D130, heated to 80 ° C. and stirred with stirring, 0.06 mol of 2-ethylhexyl acrylate (monomer A), hexyl methacrylate (Monomer B) 0.29 mol, methacryloylmorpholine (monomer C) 0.01 mol, glycidyl acrylate (monomer D) 0.04 mol, methacrylic acid (monomer E) 0.02 mol, benzoyl peroxide (reaction initiator) 0.6 g The monomer solution consisting of was added dropwise over 3 hours.
After the dropwise addition, polymerization was carried out for 5 hours while maintaining the temperature at 85 ° C.
The polymerization rate of the synthesized resin was 98%, the molecular weight Mn was 32000, and the Mw was 43,000.

(Resin synthesis example 4)
A 0.5 L flask equipped with a stirrer, thermometer, condenser, and dropping funnel was charged with 350 g of isododecane, heated to 85 ° C. and stirred with 0.04 mol of tetradecyl methacrylate (monomer A), 2-ethylhexyl methacrylate. A monomer solution consisting of (monomer B) 0.33 mol, glycidyl methacrylate (monomer D) 0.01 mol, methacrylic acid (monomer E) 0.01 mol, and benzoyl peroxide (reaction initiator) 1 g was added dropwise over 2 hours. . After the dropwise addition, polymerization was carried out for 5 hours while maintaining the temperature at 85 ° C.
Thereafter, a monomer solution consisting of 0.03 mol of acryloylmorpholine (monomer C) and 0.3 g of azbisisobutyronitrile (reaction initiator) was added dropwise over 1 hour, and polymerization was carried out for 2 hours while maintaining at 80 ° C.
The polymerization rate of the synthesized resin was 97%, the molecular weight Mn was 28000, and Mw was 48,000.

(Resin synthesis example 5)
A 0.5 L flask equipped with a stirrer, a thermometer, a condenser, and a dropping funnel was charged with 350 g of Isopar M, heated to 85 ° C., and stirred with stirring, decyl methacrylate (monomer A) 0.05 mol, 2-ethylhexyl methacrylate ( A monomer solution consisting of monomer B) 0.20 mol, glycidyl methacrylate (monomer D) 0.04 mol, methacrylic acid (monomer E) 0.10 mol, and benzoyl peroxide (reaction initiator) 1 g was added dropwise over 2 hours. After the dropwise addition, polymerization was carried out for 5 hours while maintaining the temperature at 85 ° C.
Thereafter, a monomer solution consisting of 0.02 mol of acryloylmorpholine (monomer C) and 0.4 g of azbisisobutyronitrile (reaction initiator) was added dropwise over 1 hour, and polymerization was carried out for 2 hours while maintaining the temperature at 80 ° C.
The polymerization rate of the synthesized resin was 96%, the molecular weight Mn was 39000, and the Mw was 49000.

(Resin synthesis comparative example 1)
A 0.5 L flask equipped with a stirrer, thermometer, condenser, and dropping funnel was charged with 320 g of ISOPAR L, heated to 105 ° C., and stirred with 0.10 mol of stearyl methacrylate (monomer A) and octyl methacrylate (monomer B ) 0.20 mol, methyl methacrylate (not applicable) 0.15 mol, glycidyl methacrylate (monomer D) 0.03 mol, methacrylic acid (monomer E) 0.02 mol, benzoyl peroxide (reaction initiator) 1 g monomer The solution was added dropwise over 3 hours. After the dropping, polymerization was carried out for 5 hours while maintaining the temperature at 100 ° C.
The polymerization rate of the synthesized resin was 97%, the molecular weight Mn was 15000, and the Mw was 27000.

(Resin synthesis comparative example 2)
A 0.5 L flask equipped with a stirrer, thermometer, condenser, and dropping funnel was charged with 290 g of Isopar H, heated to 85 ° C. and stirred with stirring, 0.35 mol of 2-ethylhexyl methacrylate (monomer B), styrene ( Not applicable) A monomer solution consisting of 0.02 mol, glycidyl acrylate (monomer D) 0.03 mol, methacrylic acid (monomer E) 0.02 mol, and benzoyl peroxide (reaction initiator) 0.5 g was added dropwise over 3 hours. . After the dropwise addition, polymerization was carried out for 5 hours while maintaining the temperature at 85 ° C.
The polymerization rate of the synthesized resin was 95%, the molecular weight Mn was 31,000, and Mw was 48,000.

(Resin synthesis comparative example 3)
A 0.5 L flask equipped with a stirrer, thermometer, condenser, and dropping funnel was charged with 290 g of Isopar H, heated to 85 ° C., and stirred with stirring, butyl methacrylate (not applicable) 0.36 mol, benzyl acrylate (applicable) None) A monomer solution consisting of 0.05 mol, glycidyl acrylate (monomer D) 0.04 mol, methacrylic acid (monomer E) 0.03 mol, and benzoyl peroxide (reaction initiator) 0.5 g was added dropwise over 3 hours.
After the dropwise addition, polymerization was carried out for 5 hours while maintaining the temperature at 85 ° C.
The polymerization rate of the synthesized resin was 96%, the molecular weight Mn was 20000, and Mw was 37000.

Phthalocyanine blue (PB-15: 3) (manufactured by Dainichi Seika Co., Ltd.) 13 parts Resin of Synthesis Example 1 (solid content 18.5%) 211 parts Isopar H (manufactured by ExxonMobil) 21 parts Charge control agent (phosphatidyl) Choline) (manufactured by Sakai Oil Co., Ltd.) 2 parts were placed in a ball mill and dispersed for 72 hours, then 30 parts of Isopar H was further added and dispersed for 1 hour, and this was used as a concentrated liquid developer.
An image was formed with the apparatus shown in FIG. 3 using a developer obtained by mixing 100 g of this concentrated liquid developer toner and 1 L of Isopar H.
Adhesive transfer was performed on Ricoh paper 70W at a transfer developer solid content of 89% and a transfer pressure of 2 kg / cm ² .

The same procedure as in Example 1 was performed except that image formation and adhesive transfer were performed with the apparatus of FIG.
The primary transfer was electrostatic transfer at an applied voltage of 200 V, and the secondary transfer was adhesive transfer at a transfer pressure of 8 kg / cm ² . The developer solid content at the time of secondary transfer was 96%.

Quinacridone Red (PR-122) (Fuji Pigment) /
Polyester resin (manufactured by Mitsubishi Rayon Co., Ltd.) Flushing kneaded product (ratio 1/1) Resin of Synthesis Example 2 (solid content 14.8%) 95 parts Cristol J72 (manufactured by Esso Petroleum) 23 parts Charge control agent (naphthene) Zirconate (made by Nippon Kagaku Sangyo Co., Ltd.) 2 parts was placed in a ball mill and dispersed for 90 hours. Then, 30 parts of Cristol J72 was added and dispersed for 1 hour, and this was used as a concentrated liquid developer.
This concentrated liquid developer was developed in a thin layer with the apparatus of FIG. 5 to form an image.
The primary transfer was electrostatic transfer at an applied voltage of 300 V, and the secondary transfer was adhesive transfer to a Ricoh OHP sheet at a transfer pressure of 5 kg / cm ² . The developer solid content at the time of secondary transfer was 77%.

Disperse Blue 60 (DB-60) (Arimoto Chemical Co., Ltd.) 15 parts Resin of Synthesis Example 3 (solid content 20.2%) 149 parts Exol D130 (ExxonMobil Corp.) 8 parts Charge control agent (Cobalt naphthenate) (Made by Nippon Kagaku Sangyo Co., Ltd.) 2 parts were placed in a basket mill and dispersed for 5 hours, and then 5 parts of Exol D130 was further added and dispersed for 1 hour to obtain a concentrated liquid developer.
Image formation was performed with the apparatus shown in FIG. 4 using a developer obtained by mixing 200 g of this concentrated liquid developer toner and 1 L of Exol D130.
Primary transfer was performed by electrostatic transfer at an applied voltage of 300 V, and secondary transfer was performed by adhesive transfer to polyester satin at a transfer pressure of 10 kg / cm ² . The developer solid content at the time of secondary transfer was 93%.

Naphthol Red (PR-184) (manufactured by Clariant) 16 parts Resin of Synthesis Example 4 (solid content 18.2%) 440 parts Isododecane (manufactured by ExxonMobil) 20 parts Charge control agent (zirconium naphthenate) (Nippon Chemical Industries) 2 parts were placed in a ball mill and dispersed for 96 hours, 30 parts of isododecane was further added and dispersed for 1 hour, and this was used as a concentrated liquid developer.
This concentrated liquid developer was developed in a thin layer with the apparatus of FIG. 5 to form an image.
The primary transfer was electrostatic transfer at an applied voltage of 300 V, and the secondary transfer was adhesive transfer to a brass plate having a thickness of 0.5 mm at a transfer pressure of 8 kg / cm ² . The developer solid content at the time of secondary transfer was 93%.

Naphthol red (PR-184) (manufactured by Clariant) / epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd.) (fitting ratio: 1/1) 30 parts Resin of Synthesis Example 5 (solid content: 14.3%) 315 parts Isopar M (manufactured by ExxonMobil) 6 parts charge control agent (zirconium naphthenate) (manufactured by Nippon Chemical Industry Co., Ltd.) 2 parts in a ball mill and dispersed for 90 hours, then 10 parts of Isopar M was added and dispersed for 1 hour. Was used as a concentrated liquid developer.
This concentrated liquid developer was developed in a thin layer with the apparatus of FIG. 5 to form an image.
The primary transfer was electrostatic transfer with an applied voltage of 300 V, and the secondary transfer was adhesive transfer to high-coat paper at a transfer pressure of 6 kg / cm ² . The developer solid content during the secondary transfer was 95%.

(Comparative Example 1)
Phthalocyanine blue (PB-15: 3) (manufactured by Dainichi Seika Co., Ltd.) 14 parts Resin Synthesis Comparative Example 1 resin (solid content 22.1%) 190 parts Isopar H (made by ExxonMobil) 30 parts Charge control agent (phos Fattydylcholine (manufactured by Sakai Oil Co., Ltd.) 3 parts were placed in a ball mill and dispersed for 72 hours, and then 30 parts of Isopar H was added and dispersed for 1 hour to obtain a concentrated liquid developer.
An image was formed with the apparatus shown in FIG. 3 using a developer obtained by mixing 100 g of this concentrated liquid developer toner and 1 L of Isopar H.
Adhesive transfer was performed on Ricoh paper 70W at a transfer developer solid content of 90% and a transfer pressure of 2 kg / cm ² .

(Comparative Example 2)
Disperse Blue 60 (DB-60) (Arimoto Chemical Co., Ltd.) 15 parts Resin Synthesis Comparative Example 2 resin (solid content 25.6%) 117 parts Exol D130 (ExxonMobil Corporation) 40 parts Charge control agent (naphthene) (Cobalt acid) (manufactured by Nippon Kagaku Sangyo Co., Ltd.) 3 parts were placed in a basket mill and dispersed for 5 hours. Further, 40 parts of Exol D130 was added and dispersed for 1 hour, and this was used as a concentrated liquid developer.
Image formation was performed with the apparatus shown in FIG. 4 using a developer obtained by mixing 200 g of this concentrated liquid developer toner and 1 L of Exol D130.
Primary transfer was performed by electrostatic transfer at an applied voltage of 300 V, and secondary transfer was performed by adhesive transfer to polyester satin at a transfer pressure of 10 kg / cm ² . The developer solid content during the secondary transfer was 92%.

(Comparative Example 3)
Disperse Blue 60 (DB-60) (Arimoto Chemical Co., Ltd.) 15 parts Resin Synthesis Comparative Example 3 resin (solid content 26.6%) 113 parts Exol D130 (ExxonMobil Corporation) 40 parts Charge control agent (naphthene) (Cobalt acid) (manufactured by Nippon Kagaku Sangyo Co., Ltd.) 3 parts were placed in a basket mill and dispersed for 5 hours. Further, 40 parts of Exol D130 was added and dispersed for 1 hour, and this was used as a concentrated liquid developer.
Image formation was performed with the apparatus shown in FIG. 4 using a developer obtained by mixing 200 g of this concentrated liquid developer toner and 1 L of Exol D130.
Primary transfer was performed by electrostatic transfer at an applied voltage of 300 V, and secondary transfer was performed by adhesive transfer to polyester satin at a transfer pressure of 10 kg / cm ² . The developer solid content at the time of secondary transfer was 93%. These results are shown in Table 1.

＊濃度はＸ−Ｒｉｔｅにより測定
＊平均粒径は島津製作所ＳＡ−ＣＰ３による
液体現像剤を積分球式濁度計で透過率１５％程度になるまでアイソパーで希釈し、ＳＡ−ＣＰ３用セルに充填する。測定条件はＡＣＣＥＬ４８０、ＭＯＤＥ：ＣＥＮＴ、３〜１６チャンネルで行った。
＊転写率はテープ剥離法による濃度から算出
転写率＝（転写前感光体上濃度−転写後感光体残濃度）／（転写前感光体上濃度）×１００％
＊帯電制御率は電着法により算出
電極間距離：１ｃｍ、電極面積：２ｃｍ×２ｃｍ、電着時間：１００秒で測定した。

* Concentration measured by X-Rite * Average particle diameter is diluted with Isopar until the transmittance is about 15% with an integrating sphere turbidimeter with a Shimadzu SA-CP3, and filled into a cell for SA-CP3 To do. The measurement conditions were ACCEL480, MODE: CENT, 3-16 channels.
* Transfer rate is calculated from the density by the tape peeling method. Transfer rate = (Concentration on photoconductor before transfer−Remaining photoconductor density after transfer) / (Concentration on photoconductor before transfer) × 100%
* The charge control rate was measured by an electrodeposition method with a calculated distance between electrodes: 1 cm, electrode area: 2 cm × 2 cm, and electrodeposition time: 100 seconds.

As is clear from the results in Table 1, the combination of the present image forming method, the adhesive transfer method, and the liquid developer made it possible to print with high image density with good charge controllability and non-heated adhesive transferability.
Since the toner layer is integrated and transferred without being restricted by the material (resistance value, etc.) of the transfer substrate, good transfer could be performed even on an uneven substrate.
In Example 1, since the liquid developer of the present invention is used, adhesive transferability is good. However, transferability is lower than that in Example 2 because of direct transfer from the photoreceptor. As can be seen from the results of Example 2, it is considered that the intermediate transfer member has lower surface energy than the photosensitive member, the toner layer has good releasability, and pressure is applied during transfer.
In Example 3, since the ratio of the adhesive resin was low, the transfer rate was slightly lowered.
In Example 4, although the transfer base material was an uneven cloth, the image was formed into a film and transferred integrally.
Example 5 was able to transfer at a high transfer rate even to a metal transfer substrate which is difficult to electrostatic transfer.
In Example 6, since the ratio of the monomer E was high, the toner charging rate slightly decreased.
In Comparative Example 1, since the material of the present invention was not used, no tackiness was exhibited, toner characteristics non-heat-adhesive transfer could not be performed, and toner characteristics were not good.
In Comparative Example 2, since the monomer A component of the present invention was not present, the adhesiveness was not exhibited and the adhesive transfer was not performed. Further, since there was no monomer C component, the film was not formed into a film and split in the toner layer, and the resin developability was poor because the resin resistance was low.
In Comparative Example 3, the solvent affinity of the synthetic resin was low, the toner particle size was large due to aggregation, the developability was poor, the transfer layer was soft, and the image after fixing was sticky.

DESCRIPTION OF SYMBOLS 1 Electrostatic latent image carrier 2 Transfer base material 2A Transfer base material 2B Transfer base material 3 Toner layer 3a Toner layer 3b Toner layer 4A Electrode plate 4B Electrode plate 5 Cell 10 Image forming apparatus 11 Photoconductor 12 Charge voltage applying member 13 Development Device 13a Developing roller 13b Supply roller 13c Pumping roller 13d Container 14 Squeeze roller 14a Squeeze roller 14b Squeeze roller 15 Transfer roller 16 Transfer base material separation roller 17 Cleaning blade 18 Cleaning roller 20 Image forming device 21 Intermediate transfer roller 22 Transfer roller 23 Liquid carrier Removal roller 30 Image forming apparatus D Liquid developer E Static elimination G1 Gap G2 Gap L Exposure P Transfer base material

No. 2990675 JP-A-9-204109 JP-A-2-272476 Japanese National Patent Publication No. 11-513423 Special table 2001-501654 gazette

Claims (9)

In an electrophotographic liquid developer containing toner particles dispersed in a liquid carrier, a part derived from monomer A or a part derived from monomer B represented by formulas (1) to (5) as a toner resin component constituting the toner. A liquid developer for pressure-sensitive adhesive transfer comprising a part derived from monomer C, a part derived from monomer D, and a part derived from monomer E.

(R represents H or CH ₃ , n is 6 to 9 when R is H, and n is 10 to 14 when R is CH ₃ )

(N is 6-8.)

(R represents H or CH ₃ )

(R represents H or CH ₃ )

(R represents H or CH ₃ ).   The site ratio derived from the monomer component of the resin is monomer A / monomer B / monomer C / monomer D / monomer E = 3-30 mol% / 40-90 mol% / 1-30 mol% / 1-30 mol% / 1-30 mol% The liquid developer for adhesive transfer according to claim 1, wherein the liquid developer is used.   The site ratio derived from the monomer component of the resin is monomer A / monomer B / monomer C / monomer D / monomer E = 5 to 20 mol% / 40 to 80 mol% / 2 to 20 mol% / 2 to 16 mol% / 2 to 25 mol% The liquid developer for adhesive transfer according to claim 2, wherein the liquid developer is used.   The liquid developer for pressure-sensitive adhesive transfer according to any one of claims 1 to 3, wherein the resin has a weight average molecular weight Mw of 20,000 to 50,000 and a number average molecular weight Mn of 10,000 to 40,000. The liquid developer for adhesive transfer according to claim 1, wherein the resin has a volume resistance of 1 × 10 ¹⁰ to 1 × 10 ¹⁶ Ω · cm.   6. The adhesive transfer liquid developer according to claim 1, wherein the toner particles contain a colorant and a resin.   Used in an electrophotographic adhesive transfer method in which toner particles dispersed in the liquid carrier are electrostatically attached to an electrostatic latent image to make a visible image, and then transferred to a substrate without heating by the adhesive force of the toner. The liquid developer for adhesive transfer according to any one of claims 1 to 6, wherein the liquid developer is used for adhesive transfer.   Electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and adhesive transferable liquid development containing toner particles in the electrostatic latent image formed on the electrostatic latent image carrier The developer is supplied to form a toner image of the electrostatic latent image, and a part of the liquid carrier in the developer attached to the electrostatic latent image carrier on which the toner image is formed is transferred to the electrostatic latent image. Image forming apparatus comprising: excess liquid removing means for removing from the latent image carrier; and transfer means for transferring the toner image on the electrostatic latent image carrier from which a part of the liquid carrier has been removed onto a transfer substrate. 7. The image forming apparatus according to claim 1, wherein the adhesive transferable liquid developer is the adhesive transferable liquid developer according to any one of claims 1 to 6.   An electrostatic latent image forming step for forming an electrostatic latent image on the electrostatic latent image carrier, and an adhesive transferable liquid developer containing toner particles in the electrostatic latent image formed on the electrostatic latent image carrier A developing step of supplying the developer to form the electrostatic latent image into a toner image, and a part of the liquid carrier in the developer attached to the electrostatic latent image carrier on which the toner image is formed Image forming method comprising: excess liquid removing step for removing from latent image carrier; and transfer step for transferring toner image on electrostatic latent image carrier from which part of liquid carrier has been removed onto transfer substrate 7. The image forming method according to claim 1, wherein the adhesive transferable liquid developer is the adhesive transferable liquid developer according to any one of claims 1 to 6.

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