JP4445146B2 - Electrostatic latent image liquid developing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to liquid development of an electrostatic latent image in which an electrostatic latent image formed by a method such as electrophotography, electrostatic recording, or ionography is visualized using a liquid developer.EquipmentIt is related.
[0002]
[Prior art]
In a conventional image forming apparatus, for example, a developing device used in an electrophotographic copying machine, a printer, or a facsimile machine, a liquid developer or a powder developer is usually used as a developer for developing an electrostatic latent image. Although there are agents, liquid developers are usually used in electrostatic recording devices and the like that require high image quality. This is because the toner particle diameter of the powder developer is 7 to 10 μm, whereas the toner particle diameter of the liquid developer is 0.1 to 0.5 μm. Therefore, the liquid developer was used. This is because a high-resolution image can be obtained as compared with the case where a powder developer is used. In general, powders have poor flowability compared to liquids, and therefore powder developers are more difficult to stir than liquid developers. Therefore, it is difficult to perform uniform development over a wide range with powder developers. It is.
[0003]
[Problems to be solved by the invention]
By the way, a conventional large electrostatic recording apparatus or the like generally uses a low-viscosity liquid developer in which toner is mixed at a ratio of about 1 to 2% with Isopar G (registered trademark: manufactured by Exxon), which is an organic solvent. Yes. As described above, the conventional apparatus has a small toner ratio and requires a large amount of liquid developer. Therefore, it is difficult to reduce the size of the apparatus. In addition, IsoparG used as an insulating liquid (carrier liquid) has high volatility and emits a bad odor, so that the conventional apparatus has a problem that not only the working environment is bad but also an environmental problem is caused.
Further, the insulating liquid adhering to the non-image area cannot be reduced, the background stain of the non-image area cannot be reduced, and the toner particles in the developer are filmed on the image support.
[0004]
An object of the present invention is to solve the problem that the insulating liquid in the developer adheres to the non-image area on the image support and is consumed. An amorphous fluororesin that is in a liquid phase in a temperature range usually used as a liquid developing device for electrostatic latent images, that is, a temperature range of 0 to 70 ° C. The resin is a material that can be chemically modified by having at least one functional group that can be bonded to the substrate of the image support by hydrolysis. It is.
[0005]
That is, thin film coating is achieved by using an amorphous fluororesin. Thin film coating and improved wear resistance are achieved simultaneously by the hydrolyzable group provided on a part of the fluororesin strongly bonding with the surface layer of the image support whose surface has been oxidized by aggressive means. Is done. Furthermore, by making it a liquid phase in the above-mentioned temperature range of 0 to 70 ° C., even if partial peeling occurs, it becomes possible that the fluororesin moves due to the wear work itself and covers the peeling surface again. Further, it is possible to prevent the exfoliation of the peeled surface which causes a problem with the solid phase fluororesin.
[0006]
As a material of the amorphous fluororesin, it is desirable to use an amorphous fluororesin having a perfluoropolyether structure as a main chain. The perfluoropolyether structure exists so that the main chain is horizontal to the substrate of the image support even when a functional group chemically bonded to the surface layer of the image support is added to the end, and even at room temperature, It is known that it easily rotates around a functional group bonded to a substrate. Since it has such characteristics, it is possible to quickly cover the peeled area partially generated by wear.
[0007]
On the other hand, in fluoroalkylsilanes and the like, only the silane structure region side faces the surface layer of the image support and rises perpendicularly to the surface layer of the image support like a micelle structure. When it occurs, recovery to the peeled region is unlikely to occur.
The functional group that causes hydrolysis may be an alcohol group or an alkoxy group to which a group that directly hydrolyzes carbon is bonded, or may be an alkoxysilane group, a silanol group, a carboxylic acid group, or an ester group. However, in order to facilitate hydrolysis, the hydrolyzing group is preferably an OH group, a methoxy group, or a low molecular weight alkoxy group such as an ethoxy group.
In order to further promote the hydrolysis, a methylene group in which at least one hydrogen is substituted with a halogen atom having a high electron density such as iodine or bromine is present between the hydrolyzing group and the main chain. This is effective because oxygen radicals are stabilized.
[0008]
As conventional techniques using perfluoropolyalkyl groups as fluorine-based materials, JP-A-9-61605, “Antireflection Filter”, JP-A-9-157388, “Silicon-containing organic fluorine-containing polymer and its Manufacturing method "and Japanese Patent Application Laid-Open No. 9-157582," Anti-fouling substrate ", etc., both of which are inventions paying attention to the anti-fouling property, and the insulating liquid in the developer as in the present invention This is different from the idea of adhering to the non-image area on the image support and being consumed.
[0009]
For example, Japanese Patent Application Laid-Open No. 9-61605 uses the anti-coating property as an antireflection material for a display, and is not applicable to an image support of a liquid developing device. Japanese Patent Laid-Open No. 9-157388 discloses a silicon-containing organic fluoropolymer having a structure in which a main chain is a perfluoroalkyl group having a hydrolyzable silanol or alkoxysilane as a terminal group. A silicon-containing organic fluoropolymer having a structure in which an alkoxy group is easily removed as a radical and a perfluoroalkyl group having a hydroxyl group as a terminal group is a main chain by sandwiching a halogenated (bromine, iodine) alkylene between them. In this case, it is shown that the hydroxyl group as a terminal group is easily removed, and that the main chain of the fluoride provides low surface energy, and thus has an effect on antifouling property, releasability and the like. Japanese Laid-Open Patent Publication No. 9-157582 only discloses that oily contamination on almost all material surfaces can be prevented.
[0010]
The present invention is based on the problems as described above. First, in the electrostatic latent image liquid developing apparatus, the insulating liquid in the developer is prevented from adhering to the non-image area on the image support and being consumed. An object is to provide a liquid developing device for an electrostatic latent image.
A second object of the present invention is to provide an image forming apparatus using an electrostatic latent image liquid developing device capable of reducing the consumption of insulating liquid.
A third object of the present invention is to provide a liquid developing method for an electrostatic latent image using an electrostatic latent image liquid developing apparatus capable of reducing the consumption of the insulating liquid.
[0011]
[Means for Solving the Problems]
  The invention of claim 1PhotoconductorAn electrostatic latent image liquid developing device for developing an electrostatic latent image formed thereon with toner, which is a charged visualization particle, wherein the toner is contained in an insulating liquid.IsScattered 100-10000 mPa · sThe viscosity ofA developer support coated with a liquid developer of a predetermined degree through the liquid developerPhotoconductorBy contactingPhotoconductorDeveloping means for supplying toner to the latent image surface of
  The surface of the photoreceptor is oxidized, and a release layer composed of an amorphous resin having perfluoropolyether in the main chain is formed on the surface of the photoreceptor.It is formed. As described above, the amorphous fluororesin and the surface of the image support subjected to the oxidation treatment are bonded by hydrolysis. In other words, amorphous fluororesinPhotoconductorChemical modification can be carried out by having at least one functional group capable of binding to. For this reason,PhotoconductorThe release layer on the surfacePhotoconductorBy forming a chemical bond with the surface, it exhibits a highly durable release performance,PhotoconductorThe adhesion of the developer to the developer can be reduced, and the insulating liquid in the developerPhotoconductorAdhering to the non-image area on the top and reducing consumptionPhotoconductorFilming of solid particles present in the upper liquid developer can be prevented.
[0012]
  In particular, the photoreceptorBy oxidizing the surface, it was easily oxidized with amorphous fluororesinPhotoconductorSurface binds by hydrolysisit can. Furthermore, since an amorphous fluororesin having a perfluoropolyether structure as the main chain is used, even if this perfluoropolyether structure is provided with a functional group chemically bonded to the image support at the end, the surface of the photoreceptor is not affected. It is known that it exists so as to be horizontal and easily rotates around a functional group bonded to the image support. Even if it peels off, it is possible to cover the missing part easily..
[0013]
  Claim2In the liquid developing apparatus for electrostatic latent images according to claim 1,Of the oxidized photoreceptor.The release layer is formed after the surface is surface-treated with a silane coupling agent.
  in this way,PhotoconductorA surface treatment with a silane coupling agent makes it easy to produce amorphous fluororesin without oxidation.PhotoconductorBy combining the surface with hydrolysis, the same effect as in claim 1 can be obtained.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
An electrostatic latent image liquid developing apparatus, an image forming apparatus, and an electrostatic latent image liquid developing method according to the present invention will be described.
[1] First embodiment
FIG. 1 shows a schematic configuration of an electrostatic latent image liquid developing apparatus according to the present embodiment and an image forming unit of an image forming apparatus equipped with the apparatus.
[0028]
The image forming apparatus is a printer 1, and the printer 1 is equipped with an electrostatic drum used for ionography or the like as an image support 3 in the image forming unit 2.
As shown in FIGS. 2A and 2B, the image support 3 has a surface layer 6 formed on a conductive aluminum element tube 4. The surface layer 6 has an insulating layer 5a which is an insulating film, and the thickness of the insulating layer 5a is about 30 μm. The image support 3 is rotationally driven in the direction of the arrow (see FIG. 1) at a constant speed during printing by a driving means such as a motor (not shown).
Around the image support 3 which is an electrostatic drum, a charging unit 7 for charging the surface layer 6 with an electrostatic latent image, a developing unit 8 which is a liquid developing device, an intermediate transfer member 9 and an image support cleaning unit 11. , A static eliminator 10 and the like are disposed. Further, the transfer roller 12 disposed to face the intermediate transfer member 9 functions to transfer the image formed on the intermediate transfer member 9 onto the recording paper p.
[0029]
The charging unit 7 includes an ion flow head. By this, the surface layer 6 of the image support 3 is irradiated with ions based on image information, and an electrostatic latent image can be formed.
The developing unit 8 includes a developing unit 13, a developing roller 14, a developer collecting unit 15, an m developer containing unit (hereinafter referred to as “developer adjusting unit”) 16, a toner bottle 17, and a carrier bottle 18. It is mainly composed. The liquid developer w used in the present embodiment has a viscosity of 100 to 10,000 mPa · s and a toner concentration of 5 to 40%. More specifically, for example, those having a viscosity of 300 mPa · s and a toner concentration of 15% are used.
[0030]
Here, when the liquid developer contains toner having an average particle diameter of 0.1 to 5 μm at a concentration of 5 to 40%, a liquid developer in which the toner is dispersed at a high concentration in the insulating liquid can be obtained. it can. Further, the resolution is improved substantially in inverse proportion to the particle size of the toner. Usually, the toner is present in a mass of about 5 to 10 on the printed paper, and therefore, when the average particle size of the toner is 5 μm or more, the resolution is deteriorated. On the other hand, when the average particle diameter of the toner is 0.1 μm or less, the physical adhesion becomes strong and it becomes difficult to peel off the toner during transfer.
[0031]
In the developing unit 13, a storage tank 19 in which the liquid developer w is stored, a coating roller 21 that applies the liquid developer w to the developing roller 14 that is a developer support, and a liquid developer w that is supplied to the coating roller 21 A pair of screws 22a and 22b and a regulating blade 23 for regulating the amount of the liquid developer w on the surface of the coating roller 21 are disposed. The storage tank 19 can store 100 to 150 cc of liquid developer w. The liquid developer is transported from the developer adjusting unit 16 into the storage tank 19 by the transport pump 24. The liquid level of the liquid developer w in the storage tank 19 rises when the pair of screws 22a and 22b is driven, and the liquid developer is supplied to the application roller 21 when the raised portion comes into contact with the application roller 21. Is done. When the liquid developer w transported by the transport pump 24 is supplied excessively, it overflows into the developer recovery section 15 that recovers the undeveloped toner on the developing roller 14 via a flow path (not shown), thereby adjusting the developer. Collected in the section 16. The liquid developer w supplied to the application roller 21 is formed so that the amount of the liquid developer is regulated by the regulation blade 23 and applied to the development roller 14 at about 30 cc per minute.
[0032]
The developer recovery unit 15 mainly includes a cleaning blade 26 and a screw 25, and is formed so as to clean the liquid developer w remaining on the surface of the developing roller 14 and transport it to the developer adjustment unit 16.
The electrostatic latent image of the surface layer 6 on the image support 3 is developed by the developing unit 8, and an image is formed on the image support 3. The image formed on the image support 3 is transferred onto an intermediate transfer member 9 that is driven at the same speed as the image support 3. The image on the intermediate transfer member 9 is transferred to the recording paper p by the transfer roller 12 onto the recording paper p conveyed from the paper feed cassette (not shown) to the transfer unit e1.
[0033]
After the transfer is completed, the recording paper p is fixed by a fixing unit (not shown) and discharged. The liquid developer on the image support 3 that has not been transferred onto the intermediate transfer member 9 is removed from the surface layer 6 of the image support by the image support cleaning unit 13. Further, the transfer residual developer on the intermediate transfer member 9 is removed by an intermediate transfer member cleaning unit (not shown).
Thereafter, the residual potential of the surface layer 6 of the image support 3 is removed by the static eliminator 10 to prepare for the next printing.
[0034]
Next, the surface layer 6 of the image support 3 shown in FIGS. 1 and 2 will be described.
As shown in FIGS. 2A and 2B, the surface layer 6 is formed so as to cover the surface of the conductive aluminum elementary tube 4, and an insulating layer (insulating film) 5 and a release layer (coat layer). 30. The film thickness of the insulating layer 5 is about 30 μm.
In this method of creating the surface layer 6, the insulating layer 5 that covers the surface of the aluminum base tube 4 is subjected to surface oxidation treatment to form an oxide film 27, which serves as a substrate for the image support 3. As the oxide film forming process, the following five methods (1) to (5) are selectively adopted.
(1) When the first oxide film formation step is used, the insulating layer 5 is exposed to a temperature environment necessary for surface oxidation for a predetermined time to oxidize the surface of the insulating layer 5. The insulating layer 5 is desirably exposed to an environment of 270 ° C. or more for 30 minutes or more.
(2) When the second oxide film forming step is used, the insulating layer 5 is exposed to ultraviolet rays having a wavelength of 400 nm or less for a predetermined time to oxidize the surface of the insulating layer 5. Here, the light source may be a normal halogen lamp, but in order to increase the decomposition efficiency of oxygen molecules, it is desirable to use a short wavelength light source such as an excimer lamp and expose for 5 minutes or more. Excimer laser irradiation is also effective from the viewpoint of energy efficiency.
(3) When the third oxide film forming step is used, the insulating layer 5 is exposed to an infrared lamp or flash to oxidize the surface of the insulating layer 5.
(4) When the fourth oxide film forming step is used, the surface of the insulating layer 5 is oxidized by exposure to oxygen plasma ionized or radicalized by electromagnetic waves or high-frequency voltage.
(5) When the fifth oxide film formation step is used, the surface of the insulating layer 5 is oxidized by exposure under an oxygen beam.
By adopting any of the oxide film forming steps described above, the surface layer of the insulating layer 5 was subjected to surface oxidation treatment to form an oxide film 27.
Next, utilizing the fact that the main chain of fluoride provides low surface energy, the insulating layer 5 having the oxide film 27 formed on the surface thereof is coated with a fluorine-based material to form a coating layer 30 as a release layer, The surface energy of the image support was made smaller than the surface energy of the liquid developer.
[0035]
As a coating process of the fluorine-based material for forming the coat layer 30, when the coating using the following five kinds of materials is performed, and on the surface of the insulating layer 5 of the image support, the above-mentioned positive A total of six fluorine-based material coating methods in which the surface oxidation is not performed will be sequentially described.
[0036]
(A) (Example 1)
The oxide film 27 of the insulating layer 5 which is the surface layer of the image support was immersed for 5 minutes or more with an alcohol-terminated perfluoropolyether using a suitable perfluorocarbon as a solvent. Thereafter, the hydrolysis reaction was completed by leaving it in an environment of at least 50 ° C. and 70 ° C. for at least 15 minutes. In this way, the alcohol group, which is a hydrolyzable functional group, is bonded to the oxide film 27 of the insulating layer 5 that is the surface layer of the image support through hydrolysis, and oxygen is bonded to the amorphous resin on the image support. Formed. That is, an amorphous fluororesin having a perfluoropolyether structure as a main chain is formed as a release layer (coat layer) 30 on the image support. The perfluoropolyether structure exists even when a functional group chemically bonded to the image support is provided at the end, and exists so as to be horizontal with respect to the image support surface, and is easily centered on the functional group bonded to the image support. It is known to rotate. Even when peeled off, it is possible to easily cover the lacking portion.
In order to further promote the hydrolysis, the oxygen radical is stabilized by the presence of a methylene group in which at least hydrogen is substituted with a halogen atom having a high electron density such as iodine or bromine between the hydrolyzing group and the main chain. This is effective.
[0037]
Like the above-mentioned amorphous fluororesin having a perfluoropolyether structure as the main chain, a polymer having a fluorine-containing aliphatic cyclic structure is low in crystallinity or high in spite of the fluororesin because of no crystallinity. It exhibits transparency and high light transmittance, and because it is a fluorine-containing polymer, it is superior in resistance, weather resistance, and chemical resistance compared to ordinary hydrocarbon resins. Furthermore, it is possible to prevent the developer from adhering to the image support, and it is possible to prevent the insulating liquid in the developer from adhering to the non-image area on the image support and being consumed.
In order to complete the above hydrolysis reaction, desirable conditions are 80 to 200 ° C. and 30 minutes or more. There is concern about the decomposition of the fluorine material itself under the condition of 200 ° C. or higher. In addition, the coating thickness of the produced release layer (coat layer) 30 was 10 nm or less.
[0038]
(B) (Example 2)
The oxide film 27 of the insulating layer 5 which is the surface layer of the image support was immersed for 5 minutes or more with an alkoxysilane terminal-modified perfluoropolyether using a suitable perfluorocarbon as a solvent. Thereafter, the hydrolysis reaction was completed by leaving it in an environment of at least 50 ° C. and 70 ° C. for at least 15 minutes. As described above, the alkoxysilane group which is a hydrolyzable functional group is bonded to the oxide film 27 of the insulating layer 5 which is the surface layer of the image support through hydrolysis, and the amorphous resin is bonded to the image support. It will be formed on top. Desirable conditions are 80 to 200 ° C. and 30 minutes or more. There is concern about the decomposition of the fluorine material itself under the condition of 200 ° C. or higher. In addition, the produced coating thickness was 10 nm or less.
[0039]
(C) (Example 3)
A suitable perfluorocarbon is used as a solvent, and the oxide film 27 of the insulating layer 5 which is the surface layer of the image support is immersed for 5 minutes or longer with an alkoxysilane terminal-modified perfluoropolyether having a structure different from that in Example 2 of (b). did. Thereafter, the hydrolysis reaction was completed by leaving it in an environment of at least 50 ° C. and 70 ° C. for at least 15 minutes. Desirable conditions are 80 to 200 ° C. and 30 minutes or more. There is concern about the decomposition of the fluorine material itself under the condition of 200 ° C. or higher. In addition, the produced coating thickness was 10 nm or less.
[0040]
(D) (Comparative Example 1)
The oxide film 27 of the insulating layer 5 which is the surface layer of the image support was immersed for 5 minutes or more with fluoroalkylsilane using a suitable perfluorocarbon as a solvent. Thereafter, the hydrolysis reaction was completed by leaving it in an environment of at least room temperature for 15 minutes or longer. Desirable conditions are 80 to 200 ° C. for 1 hour. There is concern about the decomposition of the fluorine material itself under the condition of 200 ° C. or higher. In addition, the produced coating thickness was 10 nm or less.
[0041]
(E) (Comparative Example 2)
The oxide film 27 of the insulating layer 5 which is the surface layer of the image support was immersed for 5 minutes or more with an amorphous fluororesin having a glass transition point of 100 ° C. or higher using a suitable perfluorocarbon as a solvent. Thereafter, the hydrolysis reaction was completed by leaving it in an environment of at least 50 ° C. and 70 ° C. for at least 15 minutes. Desirable conditions are 80 to 200 ° C. and 30 minutes or more. There is concern about the decomposition of the fluorine material itself under the condition of 200 ° C. or higher. In addition, the produced coating thickness was 10 nm or less.
[0042]
(F) (Comparative Example 3)
Unlike the other examples, the material described in (Example 1) of (a) is the same as (Example 1) on the oxide film 27 of the insulating layer 5 which is the surface layer of the image support that has not been subjected to active surface oxidation. Coated in process.
As described above, when image formation is performed using the image support 3 having the surface layer 6 produced by the six types of fluorine-based material coating methods (a) to (f), the insulation of the non-image portion attached in the development process is performed. Liquid was reduced.
Further, the wettability of the liquid developer was evaluated while performing an abrasion resistance test, and the applicability of each material to the image support was evaluated. The result is shown in FIG.
[0043]
In FIG. 3, the horizontal axis is a relative value of durability when normalized with respect to the specified wear durability (number of scratches), and the vertical axis is a value related to the contact angle with respect to the liquid developer. (Constant) / (specification lower limit angle−constant), which is appropriately normalized so that the lower limit angle of the specification becomes 1. In this graph, a material in one or more regions on both the horizontal axis and the vertical axis is a material that sufficiently satisfies the specifications.
[0044]
Clearly, (Example 1) and (Example 2) were effective, and (Comparative Example 1) to (Comparative Example 3) could not satisfy the specifications. In (Example 1) to (Example 3), the deterioration rate of the contact angle is slow, and the effect of the main chain of perfluoropolyether having a recovery function against microfracture due to wear appears. (Example 3) tends to have a lower contact angle as a whole compared to other examples. This is because (Example 1) and (Example 2) are almost completely hydrolyzed and the fluorine-based material is strongly bonded to the oxide film 27 of the insulating layer 5 which is the surface layer of the image support. Compared to this, the coupling rate of the insulating layer 5 to the oxide film 27 is low.
[0045]
(Comparative Example 1) is a type in which an alkoxysilane group similar to (Example 2) is bonded to the oxide film 27 of the insulating layer 5 which is the surface layer of the image support by hydrolysis, but in the perfluoroether main chain, Since there is no recovery function for microfracture due to wear, the deterioration rate of the contact angle is faster than the materials of (Example 1) to (Example 3).
(Comparative Example 2) is a material in which the coated fluororesin does not have a chemical bond with the oxide film 27 of the insulating layer 5 which is the surface layer of the image support and does not have a recovery function. The coating almost completely peeled off.
[0046]
(Comparative Example 3) has an intermediate contact angle deterioration rate between (Comparative Example 1) and (Comparative Example 2). This is because the surface layer portion of the image support is not actively subjected to surface oxidation treatment, so the density of chemical bonding is low. In the surface layer of the untreated image support, the thickness of the oxide film is less than 1 nm, and it has been confirmed by an ellipsometer that an oxide film of 1 nm or more is formed when the above-described aggressive surface oxidation treatment is performed. .
To summarize the above results, the wear durability is the logical product of the recovery effect of the peeled portion as a liquid phase in the practical temperature range brought about by the main chain structure and the bonding degree (density) of the functional group that performs chemical bonding. The following tendencies are shown in order of strongness.
[0047]
Liquid Phase and Image Support Surface Layer Oxidation and Hydrolysis Group (Example 1, Example 2)> Liquid Phase and Image Support Surface Layer Surface Oxidation and Weak Hydrolysis Group (Example 3)> Image Support Surface Layer Surface oxidation and hydrolysis group (Example 1)> Liquid phase and hydrolysis group (Example 3)
About (Example 1) and (Example 2) which obtained the effective result in the said evaluation test, the adhesion amount of the insulating liquid to a non-image part does not increase, and also a soiling component is not seen and is favorable. A good surface condition.
On the other hand, with respect to the durability that is about 1/10 of the specification and the contact angle was significantly reduced (Comparative Example 2), the amount of developer adhered on the surface of the image support was not uniform, and the insulating liquid in the non-image area The amount of adhesion increases, and the amount of adhesion also varies in the image area, and a uniform image cannot be obtained.
[0048]
Further, a polymer such as polyimide or polysulfone is used as the insulating material for the surface layer of the image support, and at least one of the five active oxide film forming steps (1) to (5) described above is applied to the surface. The same tendency was obtained when the polymer having a surface with a contact angle with respect to water of 25 ° or less and an untreated image support were used as the image support.
Furthermore, an oxide film having a thickness of 1 nm or more is formed on the surface by performing at least one of the first to fifth active oxide film forming processes described above on non-oxide ceramics such as silicon carbide and silicon nitride. The same tendency was obtained when the non-oxide ceramic without active oxidation treatment was used as an image support.
[0049]
Even when an image support using an oxide ceramic such as zirconia or alumina was used, the effect of the liquid phase and the effect of the hydrolysis group were the same.
In this embodiment, the coating thickness of the fluorine-based material is set to 10 nm. However, as a result of an experiment in which the thickness is changed, it has been clarified that a thickness of 1 nm or more is effective. Below this, even if the initial characteristics were good, the recovery function as an effect as a liquid phase resin was not obtained, and the contact angle deterioration characteristics similar to (Comparative Example 1) were exhibited.
In addition, although the embodiment for oxidizing the surface of the image support has been described, if the oxidation treatment cannot be performed, the surface treatment is performed with a silane coupling agent, and the amorphous structure having a perfluoropolyether structure of an amorphous fluororesin as the main chain. The image support surface layer may be release-coated using a high-quality fluororesin.
[0050]
Next, description is added about each material used with the printer 1 as an image forming apparatus which is one Embodiment of this invention.
The liquid developer w used in the present embodiment includes a resin that is a binder such as an epoxy, a charge control agent that gives a predetermined charge to the toner, a color pigment, a toner that uniformly disperses the toner, and a carrier liquid. It consists of. The composition of the toner is basically the same as that used in conventional liquid developers, but their formulation has been changed to be compatible with silicone oil to adjust charging characteristics and dispersibility. . The smaller the average particle diameter of the toner, the better the resolution. However, when the particle diameter is small, the physical adhesion increases and it becomes difficult to peel off when transferring. For this reason, in this embodiment, the average particle diameter of the toner is adjusted so that the center of the particle diameter distribution is about 2 to 4 μm for the purpose of improving transferability.
[0051]
The viscosity of the liquid developer w is determined by the carrier liquid, resin, color pigment, charge control agent, and the like used, and their concentrations. In this embodiment, the experiment was performed by changing the viscosity in the range of 50 to 6000 mPa · s and the toner concentration in the range of 5 to 40%.
As the carrier liquid, dimethylpolysiloxane oil, cyclic polydimethylsiloxane oil or the like exhibiting high electrical resistance is used. Since the liquid developer layer on the developing roller is formed in a thin layer, the amount of carrier liquid contained in the liquid developer layer is extremely small. Accordingly, since the amount of carrier liquid contained in the liquid developer supplied to the latent image surface of the photoconductor 10 is extremely small, the amount of carrier liquid absorbed by paper or the like during transfer is extremely small. For this reason, if the viscosity is 1000 mPa · s or less, almost no carrier liquid remains after fixing.
[0052]
According to the experiments by the present inventors, when an image-drawing experiment was performed using SH200 manufactured by Toray Dow Corning Co., Ltd. having a viscosity of 100 mPa · s or 50 mPa · s, the carrier remaining on the paper after fixing. No liquid was seen. Furthermore, since the surface tension of the carrier liquid is 22 mN / m, which is larger than the release layer which is the above-described image support surface layer, the carrier liquid attached to the non-image area on the image support is reduced. There are many types of carrier liquids such as Toray Dow Corning and Shin-Etsu Chemical Co., Ltd., and any of them may be selected as long as electrical resistance, evaporation characteristics, surface tension, safety, etc. are satisfied.
The electrical resistance value has a problem of toner charging stability.¹⁴Ωcm or more is desirable. 10 at a minimum¹²Ωcm or more is necessary.
[0053]
In the experiments conducted by the present inventors, it is sufficient that the surface tension of the carrier liquid is larger than the critical surface tension of the image support, and the carrier liquid is not particularly limited to silicon oil.
Therefore, the coating layer 30 which is a release layer formed on the image support in this embodiment is a release layer on the surface of the image support in a liquid developing device using the liquid developer w using silicon oil as a carrier liquid. The coating layer 30 is formed by chemically bonding with the oxide film 27 of the insulating layer 5 on the image support substrate side surface, thereby exhibiting a highly durable release performance, and the surface of the image support 3 The adhesion of the developer to the layer 6 can be prevented, and the insulating liquid in the developer can be prevented from adhering to the non-image area on the surface layer 6 and being consumed. Further, it is possible to prevent filming of solid particles present in the liquid developer w on the image support 3.
[0054]
[2] Second embodiment
In the first embodiment, the liquid developing apparatus using an electrostatic drum used in ionography or the like as the image support 3 and the printer 1 as an image forming apparatus equipped with the apparatus have been described. A liquid developing apparatus and a printer 1a as an image forming apparatus equipped with the apparatus will be described.
FIG. 4 shows a schematic configuration of an image forming unit 2a which is a main part of the printer 1a. The image forming unit 2a is provided with a photosensitive drum 31 as an image support.
[0055]
Around the photosensitive drum 31, a charging unit 32, an optical writing unit (not shown) for irradiating the photosensitive drum 31 with writing light LB based on image information, a developing unit 34 that is a liquid developing device, an intermediate transfer member 35, A static elimination lamp 36, a photosensitive drum cleaning unit 37, and the like are provided. Further, an image formed on the intermediate transfer member 35 is transferred onto the recording paper p by a transfer roller 38 disposed opposite to the intermediate transfer member 35.
As shown in FIGS. 5A and 5B, the photosensitive drum 31 as an image support forms a photosensitive member 6 a that forms a surface layer on a conductive aluminum tube 41.
[0056]
The insulating layer 5a, which is a photoconductive insulating layer of the photoreceptor 6a, is covered with a coat layer 42, which is a protective layer, to improve electrical characteristics and wear characteristics. In this embodiment, a base treatment layer 43 by an oxidation treatment that does not lose the photoreceptor characteristics is applied to the insulating layer 5a that is the photoreceptor surface layer.
Although many oxidation treatment methods are listed in the first embodiment described above, as a method for forming the base treatment layer 43 by oxidizing the insulating layer 5a here, oxidation treatment using ozone is preferable. As a specific method, the oxidation treatment by corona discharge was the easiest.
[0057]
In the above configuration, the photosensitive drum 31 as an image support is rotated in the direction of the arrow at a constant speed during printing by a driving unit such as a motor (not shown). The photosensitive drum 6a on the surface of the photosensitive drum 31 is uniformly charged by the charging unit 32, and then the writing light LB is irradiated and imaged based on the image information by an optical writing unit (not shown) to form an electrostatic latent image. It is formed on the photoreceptor 6a. The electrostatic latent image is developed by the developing unit 34 and an image is formed on the photosensitive drum 31. The image formed on the photoconductive drum 31 is transferred onto an intermediate transfer body 35 that is driven at the same speed as the photoconductive drum 31. The image on the intermediate transfer member 35 is transferred by a transfer roller 38 to a recording paper p conveyed from a paper feed cassette (not shown) to a transfer unit.
[0058]
After the transfer is completed, the recording paper p is fixed by a fixing unit (not shown) and discharged. The liquid developer w on the photosensitive drum 31 that has not been transferred onto the intermediate transfer member 35 is removed from the photosensitive drum 31 by the photosensitive drum cleaning unit 37. Further, the transfer residual developer on the intermediate transfer member 35 is removed by an intermediate transfer member cleaning unit (not shown). Thereafter, the residual potential on the surface of the photosensitive drum 31 is removed by the charge eliminating lamp 36, and the surface is prepared for the next printing.
[0059]
As shown in FIG. 4, the developing unit 34 in the printer 1 a of the present embodiment includes a developing unit 45, a developing roller 46, a developer collecting unit 47, and a developer container (hereinafter referred to as “developer adjusting unit”). ) 48, a toner bottle 49, and a carrier bottle 50. The liquid developer w used in the present embodiment has a viscosity of 100 to 10,000 mPa · s and a toner concentration of 5 to 40%. More specifically, for example, those having a viscosity of 300 mPa · s and a toner concentration of 15% are used.
[0060]
The developing unit 45 includes a storage tank 51 in which the liquid developer w is stored, a coating roller 52 that applies the liquid developer to the developing roller 46, and a pair of screws 53a and 53b that supply the liquid developer to the coating roller 52. A regulating blade 54 for regulating the amount of the liquid developer w on the surface of the coating roller 52 is disposed. The storage tank 51 can store 100 to 150 cc of liquid developer. The liquid developer w is transported from the developer adjusting unit 48 into the storage tank 51 by the transport pump 55. When the pair of screws 53a and 53b are driven, the liquid developer liquid level in the storage tank 51 rises, and when the raised portion comes into contact with the application roller 52, the liquid developer is supplied to the application roller 52. The When the liquid developer transported by the transport pump 55 is supplied excessively, it overflows into the developer recovery section 47 that recovers undeveloped toner on the developing roller 46 through a flow path (not shown), thereby adjusting the developer. Collected in part 48. The liquid developer w supplied to the application roller 52 is regulated in amount by the regulating blade 54 and about 30 cc of liquid developer is applied to the development roller 46 per minute.
[0061]
The developer recovery unit 47 includes a wiping roller 56, a cleaning blade 57 that scrapes off the developer recovered by the wiping roller 56, and a screw 58. The liquid developer remaining on the surface of the developing roller 46 is cleaned to adjust the developer. To the unit 48.
[0062]
An image was formed using the printer 1a equipped with the electrostatic latent image liquid developing apparatus of the second embodiment.
5A and 5B obtained the same result as that of the electrostatic drum of the first embodiment described above. When the coating layer 42 as the release layer was formed using the alcohol-terminal-modified perfluoropolyether and the alkoxysilane-terminal-modified perfluoropolyether of (Example 1) and (Example 2) in the first embodiment, With the liquid developer w used in the embodiment, the surface of the photoreceptor 6a forming the surface layer was developed. In this case, the coating layer 42 which is a release layer is formed by chemical bonding with the base treatment layer 43 which is the oxidation treatment layer of the insulating layer 5a, thereby exhibiting a highly durable release performance and image support. It is possible to prevent the developer from adhering to the photoreceptor 6a which is the surface of the body, and the insulating liquid in the developer adheres to the non-image area on the photoreceptor 6a which is the surface of the image support and is consumed. We were able to prevent.
[0063]
In the above description, the embodiment in which the insulating layer 5a, which is the surface of the image support, is oxidized has been described. However, when the oxidation treatment cannot be performed, the base treatment is performed with a silane coupling agent, An amorphous fluororesin having an ether structure as a main chain may be used, and a coating layer as a release layer may be release coated on the surface layer of the image support.
[0064]
[3] Third embodiment
In the third embodiment, compared to the second embodiment, a liquid developing device of the same electrophotographic system except for the configuration of the photosensitive drum 31b and a printer 1b as an image forming apparatus equipped with the same will be described. Note that members other than the photoconductive drum 31 have the same configuration, and thus a duplicate description is omitted.
In the electrophotographic liquid developing apparatus here, the photosensitive drum 31 as an image support includes a conductive aluminum elementary tube 41 as a base, and an amorphous silicon photosensitive member 6b as a surface layer thereof.
[0065]
As shown in FIGS. 6A and 6B, the amorphous silicon photoconductor 6b also has a protective layer 61 formed on the surface layer and a release layer formed on the protective layer 61 as in the second embodiment. In this case, however, the amorphous silicon photoconductor 6b includes a carrier injection blocking layer 62, a carrier transport layer 63, and a carrier generation layer 64, and a protective layer 61 serving as a surface layer is provided with a to prevent oxidation. A -SiC: H film or a-SiN: H film is provided. In addition to C and N, fluorine may be used. In this embodiment, the alcohol-terminal-modified perfluoropolyether and alkoxysilane-terminal-modified perfluoropolyether described in (Example 1) and (Example 2) of the first embodiment are used as a release layer to protect the amorphous silicon photoreceptor. Layer 61 was formed.
[0066]
Therefore, the amorphous silicon photoreceptor 6b can form a release layer made of an amorphous resin as the protective layer 61 on the surface. In particular, it is possible to form a strong release layer without oxidizing the surface of the amorphous silicon photoreceptor 6b. Further, when the photosensitive member 6b is developed with the liquid developer w used in the first embodiment, the protective layer 61 which is a release layer on the surface of the image support is the surface of the image support (aluminum elementary tube 41 side). By forming a chemical bond with the carrier injection blocking layer 62, the carrier transport layer 63, and the carrier generation layer 64, a highly durable release performance is exhibited and the adhesion of the developer to the image support is prevented. It was possible to prevent the insulating liquid in the developer from adhering to the non-image area on the image support and being consumed.
[0067]
In addition, although the embodiment for oxidizing the surface of the image support has been described, if the oxidation treatment cannot be performed, the surface treatment is performed with a silane coupling agent, and the amorphous structure having a perfluoropolyether structure of an amorphous fluororesin as the main chain. The image support surface layer may be release-coated using a high-quality fluororesin.
In the above description, the printers 1 and 1a have been described as image processing apparatuses. However, the present invention is not limited to this, and the present invention may be applied to electrophotographic copying machines, facsimiles, various printing machines, and the like. In these cases, similar effects can be obtained.
[0068]
【The invention's effect】
  As described above, the invention of claim 1PhotoconductorThe release layer on the surfacePhotoconductorBy forming a chemical bond with the surface, it exhibits a highly durable release performance,PhotoconductorThe adhesion of the developer to the developer can be reduced, and the insulating liquid in the developerPhotoconductorAdhering to the non-image area on the top and reducing consumptionPhotoconductorFilming of solid particles present in the upper liquid developer can be prevented.
[0069]
  In particular,PhotoconductorBy oxidizing the surface, it was easily oxidized with amorphous fluororesinPhotoconductorBond surfaces by hydrolysisit can. Furthermore, since an amorphous fluororesin having a perfluoropolyether structure as the main chain is used, even if this perfluoropolyether structure is provided with a functional group chemically bonded to the image support at the end, the surface of the photoreceptor is not affected. It is known that it exists so as to be horizontal and easily rotates around a functional group bonded to the image support. Even if it peels off, it is possible to cover the missing part easily..
  Claim2The invention ofPhotoconductorA surface treatment with a silane coupling agent makes it easy to produce amorphous fluororesin without oxidation.PhotoconductorThe surface may be bonded by hydrolysis, and the same effect as in claim 1 can be obtained.The
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a printer equipped with a liquid developing device for an electrostatic latent image according to an embodiment of the present invention.
2A and 2B show an image support of the printer of FIG. 1, in which FIG. 2A is an enlarged cross-sectional view, and FIG. 2B is a cross-sectional explanatory view of a surface layer portion;
FIG. 3 is a durability-contact angle characteristic diagram of the surface layer of the image support of FIG. 1, and is an evaluation diagram of applicability to the surface layer of image supports made of different materials.
FIG. 4 is a schematic configuration diagram of a printer equipped with a liquid developing device for an electrostatic latent image according to another embodiment of the present invention.
5A and 5B show an image support of the printer of FIG. 4, in which FIG. 5A is an enlarged cross-sectional view, and FIG. 5B is a cross-sectional explanatory view of a photoconductor portion.
6A and 6B show an image support used in an electrostatic latent image liquid developing apparatus according to another embodiment of the present invention, in which FIG. 6A is an enlarged cross-sectional view and FIG. 6B is a cross-sectional explanatory view of an amorphous silicon photoconductor portion. It is.
[Explanation of symbols]
1, 1a Printer
2, 2a Image forming unit
3 Image support
4, 41 Aluminum tube
5,5a Insulating layer
6 Surface layer (Latent image surface of image support)
6a Photoconductor (Latent image surface of image support)
6b Amorphous silicon photoconductor (latent image surface of image support)
8, 34 Development unit (liquid development device)
14, 46 Development roller (developer support)
27 Oxide film
30, 42 Coat layer (release layer)
31, 31b Photosensitive drum (image support)
61 Protective layer (release layer)
w Insulating liquid

Claims (2)

The liquid developing apparatus of an electrostatic latent image is developed by a developing particles charged electrostatic latent image formed on the photoconductor toner, 100～10000MPa which the toner has been dispersed minute in the insulating liquid · s of the viscosity developer carrier to which the liquid developer is applied to, by contacting the photosensitive member via the liquid developer, a developing means for supplying toner to the latent image surface of the photosensitive member Prepared,
The surface of the photoreceptor is oxidized,
An electrostatic latent image liquid developing apparatus, wherein a release layer composed of an amorphous resin having perfluoropolyether as a main chain is formed on a surface of the photoreceptor . 2. The electrostatic latent image liquid developing apparatus according to claim 1 , wherein the release layer is formed after the surface of the oxidized photoconductor is ground-treated with a silane coupling agent .

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