JP2010072388A - Image forming method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method and an image forming apparatus, by which a transferability is improved and an offset is prevented by restraining a low-volatile carrier liquid from remaining on a recording material. <P>SOLUTION: In the image forming method, by which a toner image developed using wet type developer containing the low-volatile carrier liquid is transferred and fixed to the surface of a recording medium, a resin emulsion liquid is imparted to the surface of the recording medium, before the transfer of the toner image to the surface of the recording medium, and a solvent component of the resin emulsion liquid is removed to form a resin layer. The image forming apparatus has at least an imparting means for imparting the resin emulsion liquid to the surface of the recording medium, and the resin layer is formed on the surface of the recording medium, before the toner image is transferred to the surface of the recording medium. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming method and an image forming apparatus using a wet electrophotographic system such as a copying machine, a printer, and a digital printing machine.

  In electrophotographic image formation, generally, an electrostatic latent image is formed on an electrostatic latent image carrier such as a photoconductor by image exposure according to a document image or image data. The electrostatic latent image is developed into a visible toner image, and the toner image is transferred and fixed on a recording material to obtain a target image.

  In the wet development method, a wet developer is used in which toner particles mainly composed of a pigment and a binder resin, a charge control agent, a dispersion stabilizer, and the like are dispersed in an electrically insulating dispersion medium (carrier liquid). . The toner particles used in the wet developer can be made fine because there is no fear of escaping into the atmosphere, and those having an average particle size of submicron are also practical. Therefore, there are advantages such that an image having a high resolution can be obtained and gradation is excellent. Furthermore, in recent years, in consideration of the environment, development of a wet developer using a low-volatile carrier liquid instead of a volatile carrier liquid has been promoted.

  However, when a low-volatility carrier liquid is used, the carrier liquid is difficult to volatilize, so that there is a problem that the carrier liquid remains in the recording material, transferability is lowered, and show-through occurs. Here, the show-through refers to a phenomenon in which an image can be seen through from the back side of the image forming surface. In particular, show-through occurs remarkably on high-quality paper (recording paper containing cellulose as a main component) with high liquid absorption. In order to solve this, the liquid may be volatilized, but the boiling point of the low-volatile carrier liquid is 100 ° C. or higher (flash point is 70 ° C. or higher), and enormous energy is required for volatilization. Become. In addition, it is conceivable to select a recording material having a low liquid absorbency or a printing material having a low liquid absorbency, but there is a problem that the recording material and the printing material are limited.

On the other hand, Patent Document 1 proposes a method of removing a carrier liquid by bringing a porous elastic body into contact with a toner image formed on a transfer paper. Patent Document 2 discloses a non-contact heating unit that heats an unfixed image in a non-contact manner with respect to an unfixed image on a recording medium, and a solvent that is removed from the carrier liquid deposited by the heating of the non-contact heating unit. A method using an image fixing device having a removing unit has been proposed.
JP-A-8-16004 JP 2003-98864 A

  However, in the method of Patent Document 1, since the carrier liquid penetrates into the inside of the high-quality paper having high permeability, the carrier liquid cannot be sufficiently removed, and the porous elastic body is directly brought into contact with the recording medium. There is a problem that the image may be disturbed. Further, the method of Patent Document 2 has a problem that the carrier liquid cannot be sufficiently removed because the carrier liquid penetrates into the inside of high-quality paper having high permeability.

  As described above, when a low-volatile carrier liquid is used, a sufficient solution has been found for the problem that the carrier liquid remains in the recording material, which deteriorates transferability and causes show-through. This is the current situation.

  Accordingly, the present invention provides an image forming method and an image forming apparatus that solve the above-described problems and suppress the remaining of low-volatile carrier liquid on the recording material to improve transferability and prevent show-through. Aimed to do.

  In order to solve the above problems, an image forming method of the present invention is an image forming method for transferring and fixing a toner image developed using a wet developer using a low-volatile carrier liquid onto a recording medium, Before transferring the toner image onto the recording medium, a resin emulsion liquid is applied to the surface of the recording medium, and a solvent component of the resin emulsion liquid is removed to form a resin layer.

  In the present invention, it is preferable to remove the solvent component of the resin emulsion liquid by penetrating the surface of the recording medium.

  Moreover, in this invention, the solvent component of the said resin emulsion liquid can also be removed by heating.

  In the present invention, the solvent component of the resin emulsion liquid can be removed by liquid absorption.

  Moreover, in the method of this invention, it is preferable that the said resin emulsion liquid is an O / W type | mold emulsion.

  Moreover, in this invention, it is preferable that the resin particle of the said resin emulsion liquid consists of urethane resins.

  Moreover, in this invention, it is preferable that the glass transition point of the resin particle of the said resin emulsion liquid is 30 degrees C or less.

  Moreover, in this invention, it is preferable that the solid content concentration of the said resin emulsion liquid is 20 weight% or more.

  Moreover, in this invention, it is preferable that the particle size of the resin particle of the said resin emulsion liquid is 1 micrometer or less.

  The image forming apparatus of the present invention is an image forming apparatus used in an image forming method for transferring and fixing a toner image developed using a wet developer using a low-volatile carrier liquid onto a recording medium, At least, there is provided application means for applying a resin emulsion liquid to the surface of the recording medium, and a resin layer is formed on the surface of the recording medium before the toner image is transferred onto the recording medium.

  The apparatus of the present invention has a removing means for removing the carrier liquid from the surface of the recording medium, and a heating means or a liquid absorbing means can be used as the removing means.

  According to the present invention, since the resin layer for preventing the penetration of the carrier liquid is provided on the surface of the recording medium before the toner image is transferred onto the recording medium, the carrier is transferred when the toner image is transferred onto the recording medium. It is possible to transfer the liquid without penetrating into the recording medium. Thereby, transferability can be improved and show-through can be prevented.

Hereinafter, embodiments of the present invention will be described in detail.
The image forming method of the present invention is a wet development method in which a toner image developed using a wet developer using a low-volatile carrier liquid is transferred onto a recording medium and fixed, and the toner image is placed on the recording medium. Before the transfer, a resin emulsion liquid is applied to the surface of the recording medium, and a solvent component of the resin emulsion liquid is removed to form a resin layer.

Embodiment 1 FIG.
<Developer>
The wet developer used in the present invention comprises at least a carrier liquid, colored fine particles (toner particles), and a dispersant. As the carrier liquid, a solvent having low volatility and high electrical insulation having a dielectric constant of 3 or less can be used. For example, hydrocarbon type (liquid paraffin), silicon oil, animal and vegetable oils, mineral oil and the like can be mentioned, but liquid paraffin is preferable. In the present invention, the low volatile solvent means a solvent having a flash point of 70 ° C. or higher.

The toner particles used in the present invention contain at least a colorant and a binder resin.
It is preferable to use a thermoplastic polyester resin as the binder resin. This is because the polyester resin has sharp melt properties, and it is easy to achieve both storage stability and fixability.

The polyester resin can be obtained by polycondensation of a polybasic acid and a polyhydric alcohol.
Polybasic acids include isophthalic acid, terephthalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, and acid anhydrides, trimellitic acid, trimesic acid, pyro A merit acid etc. can be mentioned.

  Examples of the polyhydric alcohol include, but are not limited to, propylene glycol such as ethylene glycol, diethylene glycol, triethylene glycol, and 1,2-propylene glycol, butanediol such as 1,4-butanediol. , Alkylene glycols (aliphatic glycols) such as neopentyl glycol and 1,6-hexanediol, and their alkylene oxide adducts, bisphenols such as bisphenol A and hydrogenated bisphenol, and phenolic glycols of these alkylene oxide adducts And alicyclics such as monocyclic or polycyclic diols, and aromatic diols, glycerol, triols such as trimethylolpropane, and the like. These can be used alone or in admixture of two or more.

  The desired polyester resin is polymerized by polycondensation of the above polybasic acid and polyhydric alcohol. As the polycondensation method, generally known polycondensation methods can be used. Although it varies depending on the type of raw material monomer, it is generally carried out at a temperature of about 150 ° C to 300 ° C. Moreover, it can carry out on arbitrary conditions, such as using inert gas as atmospheric gas, using various solvents, or making the reaction container internal pressure normal pressure or pressure reduction. An esterification catalyst may be used to promote the reaction. As the esterification catalyst, metal organic compounds such as tetrabutyl zirconate, zirconium naphthenate, tetrabutyl titanate, tetraoctyl titanate, 3/1 stannous oxalate / sodium acetate, etc. can be used, but they are products. Those that do not color the ester are preferred. Moreover, you may use an alkyl phosphate, an allyl phosphate, etc. as a catalyst or a hue regulator.

  In order to control the molecular weight of the product polyester resin, the polymerization temperature, reaction system pressure, reaction time, etc. may be adjusted. The acid value can be controlled by the molar ratio of the carboxylic acid to be reacted and the alcohol, the molecular weight of the polymer, and the like.

  In addition to polyester resins, binder resins include styrene-acrylic copolymer resins, styrene-acrylic modified polyester resins, polyolefin copolymers (especially ethylene copolymers), epoxy resins, and rosin-modified phenolic resins as necessary. Further, a resin such as rosin-modified maleic acid resin, paraffin wax or the like may be used by mixing an appropriate amount within a range of 30% by weight or less of the total weight.

  Examples of pigments include furnace black, lamp black, acetylene black, channel black, C.I. I. Pigment Black, Orthoaniline Black, Toluidine Orange, Permanent Carmine FB, First Yellow AAA, Disazo Orange PMP, Lake Red C, Brilliant Carmine 6B, Phthalocyanine Blue, Quinacridone Red, C.I. I. Pigment blue, C.I. I. Pigment Red, C.I. I. Pigment Yellow, Dioxane Violet, Pictoria Pure Blue, Alkali Blue Toner, Alkali Blue R Toner, First Yellow 10G, Ortho Nitroaniline Orange, Toluidine Red, Barium Red 2B, Calcium Red 2B, Pigment Scar Red 3B Lake, Anthosine 3B Lake, Rhodamine 6B lake, methyl violet lake, basic blue 6B lake, first sky blue, reflex blue G, brilliant green lake, phthalocyanine green G, bitumen, ultramarine blue, iron oxide powder, zinc white, calcium carbonate, clay, barium sulfate, alumina Examples thereof include white, aluminum powder, daylight fluorescent pigment, and pearl pigment.

  A pigment derivative may be used in order to improve the pigment dispersibility. A pigment derivative having a desired functional group such as a carboxyl group, a sulfonic acid group, a hydroxyl group, an amino group, or an amide group can be used.

  The pigment is dispersed in the resin, and its secondary particle size is 50 nm to 1 μm, preferably 50 nm to 300 nm. When it is larger than 1 μm, it is difficult to obtain sufficient coloring power, hiding power, and transparency after fixing with a fixed adhesion amount.

  The blending amount of the pigment is 3% or more and 50% or less, preferably 5% or more and 30% or less by mass ratio with respect to the resin. This is because if it is 3% or less, the desired concentration cannot be obtained, and if it is 50% or more, the dispersibility and fixability in the resin may be impaired.

  Next, a colored kneaded product composed of the binder resin thus obtained and a colorant added as necessary is coarsely pulverized using a cutter mill, a jet mill or the like. In this, wet pulverization is performed, and the toner is finely pulverized until the volume average particle diameter of the toner becomes 0.1 to 10 μm, preferably 0.5 to 5 μm, to obtain a concentrated liquid developer. The concentrated liquid developer thus obtained is diluted or dispersed as necessary to a suitable concentration with a carrier liquid containing additives such as a charge control agent and a dispersant (dispersion stabilizer). Use.

  As the basic polymer dispersant, those having an amino group, an imino group, an amide group, or a pyrrolidone group are preferable. For example, a polyalkylene polyamine, a salt of a long-chain polyaminoamide and a high molecular weight acid ester, a salt of a polyaminoamide and a polar acid ester, a modified polyurethane, a polyester polyamine, or the like can be used.

  Specific examples of the dispersant include “Anti-Terra-U (polyaminoamide phosphate)”, “Anti-Terra-204 (high molecular weight polycarboxylate)”, “Disperbyk-101 (polyaminoamide) manufactured by BYK Chemie. Examples thereof include phosphates and acid esters) 130 (polyamide), 13940 (polyesteramine type), 17000, 18000, 19000 (fatty acid amine type), 11200, etc. manufactured by Avicia Co., Ltd. V-216, V-220, WP-660 (polyvinylpyrrolidone having a long chain alkyl group) and the like can also be mentioned.

  The polymer dispersant is preferably added in a mass ratio of 1% to 100% with respect to the toner particles. If it is less than 1%, the dispersibility is lowered, and if it exceeds 100%, the conductivity of the liquid is increased, causing a problem in chargeability.

<Developing device>
FIG. 1 is a schematic diagram showing an example of the configuration of an experimental machine of a wet image forming apparatus used in the present embodiment. Around the drum-shaped image carrier 201, a charging device 203, an exposure device 204, a developing roller 103, an intermediate transfer member 301, and an image carrier cleaning blade 202 are arranged in order in the rotation direction indicated by the arrows. A secondary transfer roller 307 is disposed around the transfer body 301.

  The surface of the image carrier 201 is uniformly charged to a predetermined surface potential by the charging device 203, and then image information is exposed by the exposure device 204 to form an electrostatic latent image on the surface of the image carrier 201. . Next, the electrostatic latent image on the image carrier 201 is developed with a developer containing toner and carrier liquid by the developing roller 103 to form a toner image on the surface of the image carrier 201. At this time, not only the toner but also the carrier liquid adheres to the surface of the image carrier 201. Note that the developer coating layer on the surface of the developing roller 103 is held at a constant thickness by the regulating blade 101.

  Next, the toner image on the image carrier 201 is transferred to the intermediate transfer member 301 by applying a primary transfer voltage. A voltage having a polarity opposite to that of the toner is applied to the primary transfer voltage. At this time, the potential difference from the image carrier is 300 V to 3 kV.

Although FIG. 1 shows an example in which a roller is used for the intermediate transfer member 301, a belt may be used. When the intermediate transfer member is a belt, the belt material is a resin or an elastic member, and an elastic member is desirable in view of transferability to rough paper, and one having heat resistance is desirable. It is desirable that the thickness is 50 μm or more and 1 mm or less, the volume resistivity is 10 ⁶ or more and 10 ¹² Ω · cm or less, and the surface resistivity is 10 ⁶ or more and 10 ¹² Ω / □ or less. Examples of the resin include polyester, polypropylene, polyamide, polyimide, fluorine-based resin, polyphenyl sulfate, and the like, and examples of the elastic body include silicon rubber, fluorine rubber, EPDM, urethane rubber, nitrile rubber, and the like, but are not limited thereto. Considering the stability of conveyance, a multilayer belt having an elastic body on a resin substrate is desirable. In this case, the thickness of the resin substrate is desirably 50 μm to 200 μm, and the thickness of the elastic body is desirably 200 μm to 1 mm. Further, the outermost layer is desired to have high releasability. Therefore, it is preferable that the surface layer is provided with a low surface energy polymer such as fluorine-based or silicon-based or a hard layer of 1 μm or less by plasma treatment or the like.

  The developer transferred to the intermediate transfer member is transferred to the recording medium 320 by the secondary transfer roller 307. A voltage having a polarity opposite to that of the toner is applied to the secondary transfer roller 307. Reference numerals 309 and 310 denote heat rollers on which toner is fixed.

  The apparatus used in this embodiment has at least an applying unit that applies a resin emulsion liquid to the surface of the recording medium, and forms a resin layer on the surface of the recording medium before transferring the toner image onto the recording medium. Here, in the embodiment of FIG. 1, an application roller 306 is used as an example of an application unit that applies the resin emulsion liquid to the surface of the recording medium. A resin emulsion liquid 314 is accommodated in the tank 313, and the resin emulsion liquid 314 adhering to the application roller 306 is applied to the surface of the recording medium 320 supplied between the counter roller 305 and then the resin emulsion liquid 314. After a sufficient time has passed for the solvent component to permeate inside and be removed from the surface of the recording medium to form a resin layer, the toner image is transferred by the intermediate transfer member 301.

  In the present invention, an applying means for applying the resin emulsion liquid to the recording medium is used. The applying means means a method of attaching the resin emulsion liquid to the surface of the recording medium, and a method of spraying or applying the liquid. Is included. Specific examples include non-contact means for applying the coating liquid from the head as in the ink jet method, and contact means for applying a member such as a roller, brush, or sponge to the recording medium. Among them, the contact means is preferable. The reason for this is that it can be applied more efficiently than non-contact means, can be applied at a higher speed, and can be applied more near the surface of the recording medium. In the ink jet system, as a result of the resin emulsion liquid penetrating into the back of the recording medium, the resin fine particles in the resin emulsion liquid may reach the back and the permeation preventing effect may be reduced.

  In the present invention, a resin layer is formed on the surface of the recording medium before the toner image is transferred onto the recording medium. For this purpose, it is necessary to remove the solvent component of the resin emulsion. In the embodiment of FIG. 1, the resin component is formed by allowing sufficient time for the solvent component of the resin emulsion liquid to penetrate into the interior and be removed from the surface of the recording medium. This time is preferably at least 0.5 seconds. For this purpose, for example, the distance between the application roller and the secondary transfer roller may be increased. Moreover, as a method of removing the solvent component of the resin emulsion liquid, a method of volatilizing the solvent component or a method of absorbing the liquid can be used. These aspects will be described later.

<Resin emulsion liquid>
In the present invention, a resin emulsion liquid is used to prevent the carrier liquid from penetrating into the recording medium. The reason is that the resin emulsion liquid is quick-drying, and when the solvent component is removed, the resin fine particles are instantly solidified and the film formation proceeds rapidly. As the resin emulsion liquid, either an O / W type emulsion or a W / O type emulsion can be used, but an O / W type emulsion is preferable from the viewpoint of safety and environment.

  Examples of the resin fine particles in the resin emulsion liquid include, but are not limited to, a urethane resin, a nitrile resin, and a styrene / butadiene resin. The illustrated resin has high adhesiveness to the recording medium and high flexibility, so that even when the recording medium is bent, the resin is hardly peeled off or cracked. The glass transition point of the resin is desirably 30 ° C. or lower. This is because when the temperature is 30 ° C. or lower, the film can be instantly formed by removing the solvent component. Further, the urethane resin is more desirable because it has a highly reactive functional group at the terminal and becomes a stronger film after a lapse of time after film formation. In order to make a stronger film, a reaction accelerator (crosslinking agent) having a plurality of reactive functional groups such as epoxy group, isocyanate group, methylol group, amine group in one molecule may be added to the resin emulsion.

  The particle size of the resin fine particles is desirably 1 μm or less. More preferably, the thickness is 10 nm to 1 μm. If it is 1 micrometer or less, the force which self-film-forming of microparticles | fine-particles will become stronger. This is because if it is larger than 1 μm, film formation may be difficult.

  Further, the solid content ratio of the resin emulsion liquid is preferably 20 to 60% by weight, and more preferably 30 to 50% by weight. This is because if it is less than 20% by weight, the ratio of the liquid becomes large and it becomes difficult to form a film.

  According to this embodiment, when transferring a toner image onto a recording medium, the carrier liquid can be transferred without penetrating into the recording medium. Thereby, transferability can be improved and show-through can be prevented. In particular, it is effective in preventing the show-through of recording paper mainly composed of cellulose, such as high-quality paper, having a high liquid absorption.

Embodiment 2. FIG.
The present embodiment is the same as the first embodiment except that the solvent component of the resin emulsion liquid is removed by heating the recording medium.

  FIG. 2 is a schematic diagram showing an example of the configuration of an experimental machine of the image forming apparatus used in the present embodiment. In the present embodiment, a removing unit including heating rollers 311 and 312 is provided on the downstream side of the applying unit including the application roller 306.

  According to this embodiment, the same effect as in the embodiment can be obtained. However, the solvent component of the resin emulsion liquid can be removed in a shorter time by using a heating roller as the removing means.

Embodiment 3 FIG.
The present embodiment is the same as the first embodiment except that the solvent component of the resin emulsion liquid is absorbed and removed.

  FIG. 3 is a schematic diagram showing an example of the configuration of an experimental machine of the wet image forming apparatus used in the present embodiment. In the present embodiment, a removing unit including a sponge roller 315 and a counter roller 316 is provided on the downstream side of the applying unit including the application roller 306.

  According to this embodiment, the same effect as that of the embodiment can be obtained, but since the solvent component is absorbed using a sponge roller as the removing means, the removal of the solvent component of the resin emulsion liquid is further shortened. Can be done in time.

  The present invention will be specifically described using examples, but the present invention is not limited to the following examples. In the following examples, “part” means “part by weight” unless otherwise specified, “Mw” means “weight average molecular weight”, and “Mn” means “number average”. "Molecular weight", and "Tg" represents "glass transition temperature".

  In the following examples, Mw and Mn were calculated from the results of gel permeation chromatography, respectively. The gel permeation chromatography is a high-performance liquid chromatograph pump TRI ROTAR-V type (manufactured by JASCO Corporation), an ultraviolet spectroscopic detector UVIDEC-100-V type (manufactured by JASCO Corporation), a 50 cm long column Shodex GPC A- 803 (manufactured by Showa Denko KK) was used, and from the chromatographic results, the molecular weight of the test sample was calculated as polystyrene as a standard substance, and was calculated as polystyrene-equivalent Mw and Mn. The test sample used was 0.05 g of binder resin dissolved in 20 ml of tetrahydrofuran (THF).

  The glass transition temperature (Tg) was measured using a differential scanning calorimeter DSC-20 (manufactured by Seiko Denshi Kogyo Co., Ltd.) under the conditions of a sample amount of 35 mg and a heating rate of 10 ° C./min. The acid value was measured under the conditions of JIS K5400 method.

(Developer Production Example 1)
1280 parts of propylene oxide adduct of bisphenol A, 320 parts of bisphenol A ethylene oxide adduct and terephthalic acid in a round bottom flask equipped with a reflux condenser, water / alcohol separator, nitrogen gas inlet tube, thermometer and stirrer 890 parts was added, nitrogen gas was introduced with stirring, and dehydration polycondensation or dealcoholization polycondensation was performed at a temperature of 200 to 240 ° C. When the acid value of the produced polyester resin or the viscosity of the reaction solution reached a predetermined value, the temperature of the reaction system was lowered to 100 ° C. or less to stop polycondensation. Thus, a thermoplastic polyester resin A was obtained.

  The obtained polyester resin A had Mw = 7000, Mn = 2200, Tg = 68.3 ° C., and acid value = 7.0 mgKOH / g.

  100 parts by weight of polyester resin A and 15 parts by weight of copper phthalocyanine are mixed, mixed thoroughly with a Henschel mixer, melt-mixed with a twin screw extruder kneader, cooled, coarsely pulverized, and average particles with a jet pulverizer. The toner particles were obtained by fine pulverization to a diameter of 6 μm.

  25 parts by weight of the toner particles, 0.5 part by weight of polyvinylpyrrolidone V220 (manufactured by ISP) as a dispersant, 75 parts by weight of liquid paraffin (flash point 100 ° C.), and 100 parts by weight of zirconia beads are mixed, and 120 parts by sand mill. The mixture was stirred for a time to obtain wet developer A. The average particle size of the wet developer A was 2.6 μm.

Example 1.
A urethane resin emulsion liquid (HUX-232, manufactured by ADEKA, average particle diameter of 0.08 μm, solid content of 30%, glass transition temperature of 20 ° C.) was placed in a tank 313 of the apparatus shown in FIG. The process speed of the apparatus was 500 mm / s, and the distance between the coating roller 306 and the secondary transfer roller 307 was 300 mm. As the recording paper, 81 g of high-quality paper gold diamond manufactured by Mitsubishi Paper Industries Co., Ltd. was used. Wet developer A was used as the developer.

Example 2
A urethane resin emulsion liquid (HUX-320, manufactured by ADEKA, average particle size of 0.2 μm, solid content of 33%, glass transition temperature of 15 ° C.) was placed in the tank of the apparatus shown in FIG. The process speed of the apparatus was 300 mm / s, and the distance between the coating roller 306 and the secondary transfer roller 307 was 300 mm. Wet developer A was used as the developer.

Example 3
A urethane resin emulsion liquid (HUX-395, manufactured by ADEKA, average particle size 2 μm, solid content 62%, glass transition temperature −42 ° C.) was placed in the tank of the apparatus shown in FIG. The process speed of the apparatus was 300 mm / s, and the distance between the coating roller 306 and the secondary transfer roller 307 was 300 mm. Wet developer A was used as the developer.

Comparative Example 1
It is the same as that of Example 2 except having used the acrylic resin solution (The resin solution which melt | dissolved the acrylic resin in ethyl acetate, 20% of solid content) instead of the urethane resin emulsion liquid.

Comparative Example 2
Example 1 is the same as Example 1 except that the application roller 306 and the counter roller are not used.

(Evaluation methods)
1. Evaluation of see-through A solid image of cyan single color was printed (toner amount 1.5 g / m ² ) on fine paper (Minishi 81 g / m ² manufactured by Mitsubishi Paper Industries Co., Ltd.). When the ID of the image surface is X and the ID of the back surface is Y, the case where Y / X is less than 0.2 is ○, and the case where 0.2 or more is ×. The X-Rite densitometer was used for the measurement. The results are shown in Table 1.

2. Transferability Evaluation A solid image of cyan single color was printed (toner amount about 1.5 g / m ² ) on high-quality paper (81 g / m ^2, manufactured by Mitsubishi Paper Industries Co., Ltd.). The amount of toner on the intermediate transfer body before transfer to paper was X g / m ² , and the amount of toner on the paper after transfer was Y g / m ² . Y / X of 90% or more was rated as ◯, 80% or more and less than 90% as Δ, and less than 80% as x. The results are shown in Table 1.

  In each of Examples 1 to 3, show-through was suppressed and transferability was excellent. On the other hand, in Comparative Example 2 in which the resin layer was not formed on the recording paper, the show-through could not be suppressed. In Comparative Example 1 in which a resin solution was used instead of the resin emulsion, transferability was lowered.

1 is a schematic diagram illustrating an example of a configuration of an image forming apparatus of the present invention. It is a schematic diagram which shows another example of a structure of the image forming apparatus of this invention. It is a schematic diagram which shows another example of a structure of the image forming apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Developing tank 101 Control blade 102 Developer solution 103 Developing roller 201 Image carrier 202 Cleaning blade 203 Charging device 204 Exposure device 301 Intermediate transfer roller 305 Opposing roller 306 Application roller 307 Secondary transfer roller 309 Heating roller 310 Heating roller 311 Heating roller 312 Heating roller 313 Tank 314 Resin emulsion liquid 315 Sponge roller 316 Opposed roller 320 Recording medium

Claims (12)

An image forming method of transferring and fixing a toner image developed using a wet developer using a low-volatile carrier liquid onto a recording medium,
An image forming method in which a resin emulsion is applied to the surface of a recording medium and a solvent component of the resin emulsion is removed to form a resin layer before transferring the toner image onto the recording medium.   The image forming method according to claim 1, wherein the solvent component of the resin emulsion liquid is removed by penetrating the surface of the recording medium.   The image forming method according to claim 1, wherein the solvent component of the resin emulsion is removed by heating.   The image forming method according to claim 1, wherein the solvent component of the resin emulsion liquid is removed by liquid absorption.   The image forming method according to claim 1, wherein the resin emulsion liquid is an O / W type emulsion.   6. The image forming method according to claim 1, wherein the resin particles of the resin emulsion liquid are made of a urethane resin.   The image forming method according to claim 1, wherein a glass transition point of the resin particles of the resin emulsion liquid is 30 ° C. or less.   The image forming method according to claim 1, wherein the solid content concentration of the resin emulsion liquid is 20% by weight or more.   The image forming method according to claim 1, wherein the resin emulsion has a resin particle size of 1 μm or less. An image forming apparatus used in an image forming method for transferring and fixing a toner image developed using a wet developer using a low-volatile carrier liquid onto a recording medium,
At least, it has an applying means for applying a resin emulsion to the surface of the recording medium,
An image forming apparatus in which a resin layer is formed on the surface of a recording medium before the toner image is transferred onto the recording medium.   The image forming apparatus according to claim 10, further comprising a removing unit that removes the carrier liquid from the surface of the recording medium, wherein the removing unit uses a heating unit.   The image forming apparatus according to claim 10, further comprising a removing unit that removes the carrier liquid from the surface of the recording medium, wherein the removing unit uses a liquid absorbing unit.

Images