JP3951579B2 - Intermediate transfer member and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an intermediate transfer member and an image forming apparatus including the intermediate transfer member.
[0002]
[Prior art]
Image forming apparatuses applicable to facsimiles, printers, copiers, and the like include a serial method, a drum method, and an intermediate transfer method.
[0003]
For example, a serial inkjet recording apparatus forms an image by reciprocating a recording head in a direction orthogonal to a conveyance direction of a recording medium such as paper. However, this image forming apparatus takes a long printing time.
[0004]
In the drum system, a recording medium is held on a drum, and an image is formed while rotating the drum at a high speed, so that the printing time can be shortened. As a method for holding the recording medium on the drum, a gripper method, a negative pressure adsorption method, and the like are known. However, the mechanism is complicated and the apparatus becomes larger and heavier. In addition, as a method for holding a recording medium on a drum with a relatively simple configuration, a method using electrostatic force is also known, but in order to print a high-quality image, an electrostatic field gives ink ejection performance. Measures to mitigate adverse effects are necessary.
[0005]
Further, a common drawback of the serial method and the drum method is that the recording head is likely to deteriorate. This occurs because the recording head and the recording medium are arranged close to each other, and the recording medium comes into contact with the recording head or is generated from the recording medium due to an error in conveying the recording medium or the use of a non-standard recording medium. Clogging of the nozzle occurs due to foreign matter (paper dust).
[0006]
The intermediate transfer method solves the above-mentioned drawbacks, but the image must be accurately formed on the intermediate transfer member and the image must be efficiently transferred to the recording medium. As such an image forming apparatus, Japanese Patent Laid-Open No. 1-146750 discloses an image formed with an ultraviolet curable oil-based ink on an intermediate transfer member in which a thin film of a glycerin aqueous solution is formed on a smooth surface. An image forming apparatus for transferring the image to a recording medium is disclosed. Japanese Patent Application Laid-Open No. 7-89067 discloses an image formed with an aqueous ink on an intermediate transfer member in which a thin film of a surfactant having an HLB value of 2 to 15 is formed on a smooth surface. An image forming apparatus for transferring to a recording medium is disclosed. The intermediate transfer members disclosed therein have a good transfer efficiency because the above-mentioned thin film is formed on the surface and functions as a release layer.
[0007]
However, the image on the liquid thin film is unstable, and a process for thickening and stabilizing the image before transferring it to a recording medium is required.
[0008]
[Problems to be solved by the invention]
The present invention has been made to solve the above-mentioned problems, and it is not necessary to stabilize an image before transfer, and an image can be accurately formed on an intermediate transfer member, and the formed image can be efficiently used as a recording medium. It is an object of the present invention to provide an intermediate transfer type image forming apparatus capable of transferring, and an intermediate transfer member used therefor.
[0009]
[Means for Solving the Problems]
  The first aspect of the present invention is on its surfaceBy droplet ink particlesAn intermediate transfer member used for transferring a formed image to a recording medium, and having a porous body impregnated with a release agent on the surfaceA meniscus is formed by the release agent in the pores on the surface of the porous body.Intermediate transfer member. This porous body is preferably ink-repellent.
[0011]
  thisThe porous body preferably has a three-dimensional network structure. Specifically, it is preferable that the polymorph is formed of a fluororesin or a polyolefin resin. Moreover, it is preferable that the average pore diameter of the polymorph is 0.01 to 100 μm.The droplet ink particles are preferably ink particles ejected by an ink jet recording head.
[0012]
The releasing agent is preferably ink-repellent, non-volatile and incompatible with an ink for forming an image. Specifically, the release agent preferably contains silicone oil.
[0013]
  Furthermore, the present invention2Is an image forming apparatus including the intermediate transfer member.. IInk jet recording apparatus. When the intermediate transfer member according to the first aspect is used, it is preferable that the image forming apparatus further includes a replenishing unit that replenishes the intermediate transfer member with a release agent. When the replenishing means replenishes the release agent from the surface opposite to the surface on which the image of the intermediate transfer member is formed, the replenishing means may include a second porous body that contacts the porous body. it can. The replenishing means can slide or follow the porous body of the intermediate transfer member, or can slide or follow the porous base material integrated with the porous body..
[0014]
  In the first aspect of the present invention, the release agent impregnated in the porous body forms a meniscus in the micropores on the surface of the porous body. The spacing between the microporesDroplet ink particles (hereinafter sometimes simply referred to as “ink particles”)If the size is sufficiently smaller than the size, a state close to a state in which the surface of the intermediate transfer member is substantially covered with a liquid film of a release agent can be realized.
[0015]
Since this release agent receives the capillary force of the fine pores of the porous body, unlike the release agent liquid film formed on the smooth intermediate transfer member as in the prior art, it receives some external force. But it does not move or flow out easily.
[0016]
Then, the ink particles come into contact with the intermediate transfer member at a contact angle exceeding 90 ° due to the ink repellent effect of the release agent. At first glance, it seems to be an unstable adhesion state, but the release agent in contact with the ink particles also forms a meniscus between the ink particles and the porous body, so the interfacial tension acting on the ink particles keeps the ink particles stable. Acts as a force.
[0017]
Further, the fine uneven structure on the surface of the porous body also has an effect of stabilizing the ink particles.
[0018]
As described above, when the ink particles are held on the intermediate transfer member to such an extent that they do not move due to vibration or impact generated in the image forming apparatus due to the effect of the meniscus formed by the release agent and the uneven structure of the porous body surface. At the same time, because of the ink repellent effect of the release agent, it adheres to the intermediate transfer member at a contact angle of more than 90 °, and therefore 100% is transferred from the intermediate transfer member to the recording medium.
[0019]
  Less thanFrom above, high-speed and high-quality transfer is possible.
[0020]
  In the present invention, the ink is at least an aqueous inkjet ink.TheIncluding.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0022]
  As shown in FIG. 1, the intermediate transfer member 1 according to the first embodiment of the present invention has a porous body 3 impregnated with a release agent 2 on its surface.. During ~Interim transfer member1'sThe shape may be a cylindrical shape or a belt shape.
[0023]
  The intermediate transfer member of the present invention has a substrate (see FIG.1's4) is used. As the material of the base material, any material can be used as long as it can stably hold the surface layer and can stably maintain the contact state with the transfer means via the recording medium, such as metal such as aluminum and stainless steel, ceramic, resin, etc. Any material can be used.
[0024]
A porous substrate can be used when the intermediate transfer member is brought into contact with replenishing means described later. The porous substrate is formed of a material having sufficient mechanical strength and capable of continuous use at a high speed for a long period of time. This porous base material is integrated with the porous body. When this integration is performed by applying a predetermined heat and pressure [melt-compression (thermal lamination) method], the porous base material is an intermediate material. A material that melts at a temperature lower than the melting point of the porous body of the transfer member is selected. For example, when PTFE resin is used as the porous body, polyolefin resin (for example, polyethylene resin, polypropylene resin, etc.), nylon resin that melts below the melting point of PTFE resin, that is, 230 to 250 ° C., as the porous substrate. Nonwoven fabrics, woven fabrics, meshes, nets, and the like formed from polyester resins, aramid resins, and the like, and composite materials thereof can be used.
[0025]
When the porous substrate and the porous body are integrated with an adhesive, the same material as the porous body of the intermediate transfer member can be used as the porous substrate. In that case, as the adhesive, a thermoplastic adhesive, a thermosetting adhesive, or a room temperature adhesive can be used. Specifically, a combination of an imide-based, epoxy-based, cyanoester-based, polyamide-based, phenol-based room temperature adhesive and a silicone elastomer has sufficient adhesion to a low surface energy material, and It is suitable because it is chemically stable and excellent in chemical resistance and environmental resistance. When adhering, if the porous body and the porous substrate are separated by the adhesive layer, the release agent cannot be replenished to the porous body. It is necessary to secure the communication path from the replenishing means to the porous body by applying them separately, such as stripes or lattices.
[0026]
  The spacing between the micropores in the porous body is the ink particle (Fig.1'sIt is preferable that the size is sufficiently smaller than the size of 6). As long as this condition is satisfied, a structure in which isolated pores exist discretely, a fine groove structure in which ultrafine fibers are knitted, a structure in which a material having a capillary structure such as a hollow fiber is bundled, and a three-dimensional mesh-like porosity Any of the quality structures may be used. Among these, a three-dimensional network porous structure is preferable. If the interval between the micropores is smaller than the size of the ink particles, the porous body impregnates the release agent to form a meniscus (5 in FIG. 1) in the micropores on the surface, and substantially the surface is formed. It can be covered with a liquid film of a release agent. Moreover, if a three-dimensional network-like porous structure is used, the release agent can be rapidly and uniformly infiltrated into the porous body simply by supplying the release agent to any part of the porous body. .
[0027]
  The average pore size of the porous body is preferably 0.01 to 100 μm. When the average pore diameter is less than 0.01 μm, the release agent is less likely to penetrate the porous body, and a special method such as a pressurizing method is required to impregnate a predetermined amount of the release agent. On the other hand, when the average pore diameter exceeds 100 μm, the meniscus holding force decreases, and as a result, the release agent may flow out to the surface of the porous body due to external force such as vibration or impact. In the present invention, the average pore diameter is measured by a mercury intrusion method. When the intermediate transfer member of the present invention is used in an ink jet recording apparatus, the average pore diameter is more preferably 0.1 to 30 μm.New.
[0028]
Further, the porosity of the porous body is preferably 10 to 90%. When the porosity exceeds 90%, the mechanical strength is insufficient, and when the porosity is less than 10%, the exposure rate of the porous body increases and the effect of the release agent is not exhibited. The porosity is measured by mercury porosimetry.
[0029]
The average pore diameter range and the porosity range are also preferable in the case of an ink-repellent porous body.
[0030]
  In the intermediate transfer member according to the first aspect of the present invention, since the release agent impregnated in the porous body exhibits a release function during image transfer, the release property of the porous body itself is not high. In addition, it is possible to select materials that have excellent mechanical properties such as tensile strength or can be obtained at low cost. However, in order to further improve transfer efficiency, the porous body is preferably ink-repellent.. ManyIn order for the porous body to exhibit ink repellency, the surface tension of the porous body needs to be smaller than the surface tension of the ink. Specifically, the surface tension of the porous body is preferably 40 mN / m or less, more preferably 30 mN / m or less, and further preferably 20 mN / m or less.
[0031]
Examples of the ink-repellent porous material include PTFE (tetrafluoroethylene polymer), PFA (tetrafluoroethylene / perfluorovinyl ether copolymer), PVDF (polyvinylidene fluoride), FEP (ethylene tetrafluoride). / Fluoropolymers such as propylene hexafluoride copolymer), ETFE (ethylene / tetrafluoroethylene copolymer), PCTFE (ethylene trifluoride chloroethylene polymer); PE (polyethylene), PP (polypropylene), PB ( Polyolefin resin such as polybutylene). Other materials for the porous body include polysulfone resins such as polysulfone polymers; polyester resins such as PET (polyethylene terephthalate) and PBT (polybutylene terephthalate); nylon (6, 6-6, 6-2). 12) and the like; polyimide resins such as polyimide and polyamideimide; polyurethane resins; polyacrylonitrile polymers such as polyacrylonitrile polymers, methacrylic acid alkyl esters, N-alkyl (meth) acrylamides, and carboxy (meth) acrylates Resin; Polystyrene resin such as hydroxystyrene resin; Polyketone resin such as polyetherketone resin; Silicone resin such as silicone gel; Ethylene / vinyl acetate copolymer (EVA); Polyvinyl chloride resin; Polyvinylidene chloride resin; Poly -Bonate (PC); Polyoxymethylene (POM); Polyphenylene sulfide (PPS); Polyether ether ketone (PEEK); Fibrous resins such as ethyl cellulose, cellulose acetate, cellulose nitrate, and cellulose propionate . These can be used alone or in admixture of two or more.
[0032]
Among these, fluororesins such as PTFE are preferable because they have high chemical resistance and heat resistance and are excellent in ink repellency. Polyolefin resins such as polyethylene have chemical resistance and ink repellency similar to those of fluororesins, and are excellent in mechanical strength. Therefore, they are particularly preferable as a material constituting an intermediate transfer member in the form of a belt. .
[0033]
As a method for forming the porous body, a known production method, for example, a foaming method, a sintering method, a stretching method, an extraction method, a track etching method, a melt phase separation method, a phase change method, or the like can be used. The most appropriate method is selected according to the situation. For example, a porous body can be obtained by melting or dispersing various additives in the above material, molding the obtained melt or dispersion, and then removing the additives. Furthermore, a porous body can be obtained by subjecting a temporary molded product formed of the fine particles of the material and various additives to heat treatment and stretching treatment in the vicinity of the melting point of the material. When a fluororesin is used, it is preferable to use a stretching method or an extraction method in which a heat treatment not lower than the melting point of the resin is applied.
[0034]
When providing a porous body on a base material, it is preferable to wind a film-like porous body around a base material, or to apply a porous body on a base material in the form of a film. Further, the film itself may be made into an endless belt and the base material may be omitted.
[0035]
When the porous body is formed of a resin other than the fluororesin, the fluororesin may be applied to the porous body by spraying, dipping, or the like.
[0036]
The release agent used in the present invention is preferably ink repellent, that is, the surface tension of the release agent is smaller than the surface tension of the ink. Further, it is desirable that the surface tension is small in order to impregnate the fine pores of the porous body. Specifically, the surface tension of the release agent is preferably 30 mN / m or less.
[0037]
Moreover, it is preferable that the mold release agent used for this invention is non-volatile so that the impregnation state of a porous body may not change. Specifically, the vapor pressure of the release agent is preferably about 13.3 Pa (0.1 mmHg) or less at room temperature (25 ° C.).
[0038]
Furthermore, the release agent used in the present invention is preferably incompatible with the ink for forming an image. Specifically, the solubility of the release agent in the ink is preferably 0.1% by weight or less at normal temperature (25 ° C.).
[0039]
The kinematic viscosity of the release agent used in the present invention is 1-1000 mm at room temperature.²A range of / s is desirable. Kinematic viscosity is 1mm²If it is less than / s, the amount of release agent evaporated at room temperature increases, making it difficult to maintain the performance of the intermediate transfer member for a long period of time. Also, kinematic viscosity is 1000mm²When it exceeds / s, it becomes difficult for the release agent to flow, and the time required for impregnation into the porous body becomes longer.
[0040]
As the release agent, organic solvents and oils that are liquid at room temperature can be suitably used. Specifically, organic solvents such as octane, nonane, tetradecane, dodecane, oleic acid, linoleic acid, n-decanol, dimethylbutanol, dibutyl phthalate, dibutyl maleate, and vegetable oil, mineral oil, silicone oil, fluorine oil, etc. These oils can be preferably used. These may be used singly or a plurality of types may be mixed and used as long as they can be mixed uniformly. Further, a plurality of materials may be mixed to adjust the viscosity and surface tension to a preferable range.
[0041]
In these, the silicone oil which is excellent in said each characteristic is preferable.
[0042]
When joining the said porous body layer and a base material, an adhesive agent can be used. The adhesive preferably has a resistance to the release agent and can adhere a material having a high release property. Specifically, a silicone-based adhesive, a fluorine-based adhesive such as PFA or FEP, a urethane-based adhesive, or the like can be used. Further, the porous body layer and the base material may be bonded by thermal fusion.
[0043]
In the intermediate transfer member of the present invention, an intermediate layer may be provided between the base material and the porous body layer. Examples of the intermediate layer include a primer layer for improving adhesiveness and an elastic layer for improving the contact state between the recording medium and the intermediate transfer member during transfer.
[0044]
  The intermediate transfer member of the present invention can be applied to an intermediate transfer member of an intermediate transfer type image forming apparatus. As such an image forming apparatus, an ink jet recording apparatus is used.PlaceIs mentioned.theseImage forming apparatusIsAnd a recording means for applying an image on the intermediate transfer member of the present invention.
[0045]
In the case of an ink jet recording apparatus, this recording means ejects ink droplets in accordance with a print signal, and specifically includes an ink jet recording head using an electrothermal conversion element or a piezoelectric element.
[0047]
  The image forming apparatus further includes a transfer unit that transfers the image on the intermediate transfer member to a recording medium. When the image forming apparatus is an ink jet recording apparatus, the transfer means is a contact type that makes the recording medium contact the intermediate transfer member.The
[0048]
As the contact type, it is possible to use a roll which is disposed at a position facing the intermediate transfer member of the present invention and which can be rotated according to the movement of the recording medium. In this case, the interval between the roll and the intermediate transfer member is set to be shorter than the thickness of the recording medium, whereby the recording medium is pressed against and contacts the intermediate transfer member with a predetermined pressure.
[0049]
  When the image forming apparatus is an ink jet recording apparatus, since the ink particles are liquid, transfer can be performed simply by bringing the recording medium into contact with the intermediate transfer member.The
[0051]
According to the present invention, since the image formed on the intermediate transfer member is transferred to the recording medium 100%, it is not always necessary to provide a cleaning means, but before the transfer to the recording medium is completed due to a trouble such as a paper jam. In some cases, the device may stop. In this case, since it is necessary to clean the image remaining on the intermediate transfer member, the image forming apparatus preferably includes a cleaning unit for cleaning the surface of the intermediate transfer member. As the cleaning means, a blade made of a rubber material can be used. Alternatively, an ink-absorbing sponge may be used as a cleaning means to suck out an image. In either case, the surface of the intermediate transfer member has a high release property due to the effect of the release agent, and can be easily cleaned. The cleaning unit may always be in contact with the intermediate transfer member to clean the intermediate transfer member every time the image is formed, or may be in contact with the intermediate transfer member only when a trouble such as a paper jam occurs.
[0052]
Since the release agent used in the present invention is held in the micropores of the porous body, the amount transferred onto the recording medium together with the image during transfer is very small, but the consumption increases as the printing is repeated. Even if the release agent is somewhat reduced, the meniscus of the release agent is recovered by the capillary force of the porous body, but in order to guarantee a longer apparatus life, the intermediate transfer member of the first aspect is used. In this case, the image forming apparatus preferably includes a replenishing unit that replenishes the intermediate transfer member with a release agent.
[0053]
As the replenishing means, any non-contact type such as a spray, contact type such as a coating roll, a pad, a wick (7 in FIG. 2), and a porous body (for example, sponge) can be used. In the case of the contact type, the replenishing means is partly immersed in a release agent (9 in FIG. 2) housed in a storage container (8 in FIGS. 2 and 3) and the other part of the intermediate transfer member. Placed in contact with the surface. In these, the porous body which can adjust the replenishment amount easily is preferable.
[0054]
In the case of a coating roll, the coating roll may be driven with the rotation of the intermediate transfer member, or may be rotated independently of the rotation of the intermediate transfer member.
[0055]
The porous body is preferably a resin porous body produced by stretching, rolling, foaming or the like. Specific examples include fluororesin porous bodies produced by stretching and rolling, polyolefin resin porous bodies, so-called foams such as polyurethane foam, polyethylene foam, polystyrene foam produced by foaming, and foamed rubbers. Is mentioned. Further, a material having a continuous void porous structure in which fine grooves on the surface or inside thereof can come into contact with the porous body of the intermediate transfer member on the surface, such as a fiber material or a paper material, can also be suitably used. As such a thing, the said sponge, a nonwoven fabric, felt, cloth, etc. are mentioned. These materials are not altered or deteriorated by the release agent used, and the pore diameter of the porous body of the intermediate transfer member is set to r.₁The contact angle between the porous body of the intermediate transfer member and the release agent is θ₁, The pore diameter of the porous body of the replenishing means is r₂, And the contact angle between the porous body and the release agent is θ₂In the contact portion between the intermediate transfer member and the porous body of the replenishing means, (cos θ₁/ R₁)> (Cos θ₂/ R₂) Is preferably satisfied. When this equation is satisfied, the release agent held in the supply means can be supplied to the intermediate transfer member by bringing the porous body of the supply means into contact with the porous body of the intermediate transfer member.
[0056]
The replenishment may be performed every time the image is formed, or may be performed when a certain period of time has elapsed or when a certain number of image formations have been completed. When a multicolor image is formed, it may be replenished each time an image of each color is formed, or may be replenished when the formation of a multicolor image is completed. When the image is not replenished each time the image is formed, the replenishing unit is connected to the moving member and can be moved from a position close to the intermediate transfer member to a position separated from the intermediate transfer member. It is arranged at the position to do.
[0057]
The replenishing means is preferably arranged downstream of the cleaning means in the rotation direction of the intermediate transfer member.
[0058]
When the image forming apparatus includes a replenishing unit, the image forming apparatus can further include a replenishment amount regulating unit to prevent the release agent from being excessively replenished to the intermediate transfer member. As the replenishment amount regulating means, when the replenishing means is an application roll, as shown in FIG. 3, a blade 11 that contacts the outer peripheral surface of the application roll 10 and adjusts the amount of the release agent 9 on the application roll. And a blade disposed downstream of the replenishing unit in the rotation direction of the intermediate transfer member and contacting the intermediate transfer member to scrape off excess release agent. When the replenishing means is a porous body, the porous body can serve as both the replenishing means and the replenishment amount regulating means.
[0059]
When the intermediate transfer member is a belt, the image forming apparatus includes a plurality of rolls for winding and rotating the belt-like intermediate transfer member. In this case, it is preferable that image formation, transfer, and replenishment of the release agent are performed at positions facing each roll.
[0060]
When the width of the recording means is narrower than the width of the recording medium (for example, when printing by scanning a short recording head in the width direction of the recording medium) or when forming a multicolor image, an intermediate transfer member In order to form an image thereon, it is necessary to rotate the intermediate transfer member a plurality of times. In such a case, a means that abuts on the intermediate transfer member and performs its function, for example, a replenishing means, a transferring means, a cleaning means, or a replenishment amount regulating means, forms a completed image on the intermediate transfer member. Until then, it may be connected to the moving member so that it can be arranged at a position separated from the intermediate transfer member.
[0061]
  Figure9As shown, the replenishing means may replenish the release agent on the surface of the intermediate transfer member opposite to the surface on which the image is formed. In this case, the image forming apparatus can be downsized. Replenishment means is figure9The release agent may be dropped in a non-contact manner with the porous body of the intermediate transfer member using gravity or a pressure mechanism (not shown) as shown in FIG.10From figure13As shown in FIG.
[0062]
  Figure10Then, the replenishing means slides on the surface opposite to the surface on which the porous body image of the intermediate transfer member is formed. A stable contact state can be maintained by pressing the replenishing unit and the intermediate transfer member. In such a replenishing means, it is easy to secure a contact surface with a sufficient area, and thus the entire replenishing means can be reduced in size. Many of the release agents (particularly silicone oil) used in the present invention have a small surface tension and also have a performance as a lubricant. Therefore, the rotational accuracy of the intermediate transfer member that causes damage or deterioration of image quality due to sliding is low. Decrease can be avoided.
[0063]
  When sliding the replenishing means and the intermediate transfer member,13As shown in FIG. 5, the porous base material integrated with the porous body of the intermediate transfer member and the replenishing means may be slid. In that case, the life of the intermediate transfer member can be extended and the reliability can be improved.
[0064]
  Figure11Then, the replenishing means follows the surface of the intermediate transfer member opposite to the surface on which the porous image is formed. In this case, there is no fear of problems due to wear, and12Thus, when the intermediate transfer member is an endless belt, the replenishing means can be used as a tension roll, and the cost can be reduced by downsizing the apparatus and reducing the number of parts.
[0065]
  Figure10~ Figure13In this case, the replenishing means is arranged to face the recording head, but the replenishing means does not have to face the recording head.
[0066]
  A specific configuration of the above image forming apparatus is shown in FIG.And 5Shown in
[0067]
An image forming apparatus 20 shown in FIG. 4 is an ink jet recording apparatus, and includes a drum-shaped intermediate transfer member 22 that can rotate clockwise. The intermediate transfer member 22 has a porous body impregnated with a release agent on its surface, around which a recording head 24 and a pressure roll 26 as transfer means are clockwise, and one end is connected to the intermediate transfer member 22. The cleaning blade 28 that contacts, the release agent 32 stored in the storage container 30, partly in contact with the other part, and the other part in contact with the intermediate transfer member 22. A blade 36 is disposed as a replenishment amount regulating means in contact therewith. The distance between the pressure roll 26 and the intermediate transfer member 22 is set smaller than the thickness of the recording medium 38.
[0068]
The image forming apparatus 40 in FIG. 5 is also an ink jet recording apparatus. Note that the same components as those of the image forming apparatus 20 in FIG. In the image forming apparatus 40, the intermediate transfer member 42 is a belt and is wound around a plurality of rollers 44 disposed at positions facing the recording head 24, the pressure roll 26, and the application roll 34. The intermediate transfer member 42 also has a porous body impregnated with a release agent on the surface.
[0074]
  These image forming apparatuses 20, 40Is the application roll 34Intermediate transfer members 22, 42A predetermined amount of a release agent is supplied to the porous body layer, impregnated, and held. The release agent forms a meniscus in the micropores present on the surface of the porous body.
[0075]
  Next, the intermediate transfer members 22, 4 are recorded by the recording means.2 aboveAn image is formed. In the image forming apparatuses 20 and 40, the recording head 24 forms an image directly on the intermediate transfer members 22 and 42.CompleteThe Intermediate transfer members 22, 42 aboveThe image is adhered to the surface of the intermediate transfer member at a contact angle of 90 ° or more due to the ink repellent effect of the release agent, the ink repellent effect of the porous body, and the like, and the mold release agent formed between the mold release agent and the image Due to the surface tension of the meniscus and the effect of the concavo-convex structure on the surface of the porous body, it adheres under a restraining force that does not move even if it receives some external force.
[0076]
  This image contacts the recording medium 38 conveyed at a predetermined timing at the transfer position, and is transferred to the recording medium 38.Droplet ink particlesFormed withImageThe recording medium 38 is transferred onto the recording medium 38 only by contact with the recording medium 38, and the recording medium 38 is pressed by the intermediate transfer members 22 and 42 and the pressure roll 26 in order to ensure transfer..
[0077]
  After transfer, intermediate transfer members 22, 42 isCleaning blade 28The surface is more cleaned. Then, application roll 34More intermediate transfer members 22, 42A release agent is supplied to the porous body, and the replenishment amount of the release agent is adjusted by the blade 36.
[0078]
The above operation is repeated.
[0079]
  These image forming apparatuses 20, 4To zeroIn the cleaning blade 28 isCan be omitted.
[0081]
  In these apparatuses, the application roll 3 is used as a supply means.FourInstead, replenishing the release agent from the surface opposite to the image forming surface of the intermediate transfer member9From figure13Needless to say, the configuration of the above may be used.
[0082]
【Example】
Hereinafter, the present invention will be described based on examples.
Example 1
In the ink jet recording apparatus shown in FIG. 4, a porous PTFE film (average pore diameter 1.0 μm, porosity 80%) manufactured by a uniaxial stretching method is placed on an aluminum pipe, and the temperature is equal to or higher than the melting point of PTFE. Heat-treated, and the film was adhered to the pipe, and the porous PTFE film was coated with silicone oil (surface tension 20 mN / m, kinematic viscosity 20 mm²/ S, vapor pressure 0.1 Pa or less (less than measurement limit) at 25 ° C., intermediate transfer member impregnated with ink solubility at 25 ° C. (0% by weight), thermal ink jet head (short head), foam as replenishment means A polyurethane roll, an aluminum roll (having the same width as the paper width) as a transfer means, and an ethylene propylene rubber strip blade as a cleaning means were used. As the ink, four colors of water-based ink (surface tension 40 mN / m (both four colors)) of black, cyan, magenta, and yellow were used. The contact angle between the intermediate transfer member and the ink was 100 °.
[0083]
  When this ink jet recording apparatus was used, the image could be transferred to the recording medium without thickening the image on the intermediate transfer member. The transfer rate was 100%.
(Example 2)
  A 40 μm thick porous polypropylene film (average pore diameter 0.2 μm, porosity 46%) manufactured by uniaxial stretching method is placed on a 100 μm thick PET film on the ink jet recording apparatus of FIG. Heat-treat withPolypropylene on PET filmGlue the film to the porous polypropylene film with silicone oil (surface tension 20mN / m, kinematic viscosity 20mm²An intermediate transfer member impregnated with / s) was used. The intermediate transfer member was wound around a first roll disposed at a position facing the recording head, a second roll disposed at the transfer position, and a third roll disposed at the replenishment position. Other conditions were the same as in Example 1. The contact angle between the intermediate transfer member and the ink was 100 °.
[0084]
  When this ink jet recording apparatus was used, the image could be transferred to the recording medium without thickening the image on the intermediate transfer member. The transfer rate was 100%.
(Reference example 1)
  Figure6A porous PTFE film (average pore diameter of 0.5 μm, porosity of 80%) manufactured by a uniaxial stretching method is placed on an aluminum pipe on an ink jet recording apparatus shown in FIG. Then, an intermediate transfer member having a film bonded to a pipe, a thermal ink jet head (short head), and an aluminum roll (having the same width as the paper width) as transfer means were used. As the ink, four colors of water-based ink (surface tension 40 mN / m (both four colors)) of black, cyan, magenta, and yellow were used. The contact angle between the intermediate transfer member and the ink was 110 °.
[0085]
  When this ink jet recording apparatus was used, the image could be transferred to the recording medium without thickening the image on the intermediate transfer member. The transfer rate was 100%. The image on the recording medium obtained by this example is shown in FIG.7The image quality was equivalent to that printed directly on the recording medium.
(Comparative Example 1)
  Other than using an intermediate transfer member using a non-porous PTFE filmReference example 1The same ink jet recording apparatus and ink were used. Transfer rate isReference example 1However, since the ink particles moved and bonded on the intermediate transfer member, a high-quality image could not be formed on the intermediate transfer member. The image on the recording medium obtained in Comparative Example 1 is shown in FIG.8Shown inReference example 1Images obtained with7), The dot size and shape changed, and the image information could not be faithfully reproduced.
(Example3)
  Figure14In the ink jet recording apparatus, an adhesive mainly composed of an epoxy resin is arranged in isolated dots on a polyethylene resin nonwoven fabric having an average pore diameter of 100 μm as a porous substrate, and an average pore diameter of 1.0 μm and empty A porous PTFE with a porosity of 80% and a thickness of 85 μm is pressed and then the adhesive is cured at room temperature to integrate the porous base material and the porous body into an intermediate endless belt having a width of 215 mm and a circumferential length of 315 mm. Used as a transfer member.
[0086]
A polyurethane foam layer (average pore diameter of 300 μm) having a thickness of 5 mm was formed on the outer periphery of the aluminum roll to produce a supply means. Silicone oil as a release agent for polyurethane foam layer (surface tension 20mN / m, kinematic viscosity 20mm²/ S, a vapor pressure at 25 ° C. of 0.1 Pa or less (measurement limit or less), and an ink solubility at 25 ° C. of 0 wt% (measurement limit)) was impregnated.
[0087]
An endless belt was wound around the supply means and the tension roll. Further, a thermal ink jet head (short head) and a rubber roll (having the same width as the paper width) as transfer means were used. In addition, as inks, black, cyan, magenta and yellow water-based inks (surface tension of 35 to 40 mN / m (both colors), kinematic viscosity 3 mm)²/ S (4 colors)) was used. The contact angle of the release agent with respect to the porous PTFE is 30 °, the contact angle of the release agent with respect to the porous substrate is approximately 0 °, and the contact angle of the release agent with respect to the polyurethane foam is approximately 0 °. there were. The peripheral speed of the intermediate transfer member is 1000 mm / s, and the writing method is a helical scan method in which printing is performed by the interaction of the intermediate transfer member that rotates a plurality of times and a recording head that moves linearly in a direction perpendicular to the paper surface.
[0088]
Using this inkjet recording apparatus, continuous printing of 5000 A4 sheets was performed, and it was confirmed that there were no image quality defects due to ink repelling or coalescence. In addition, the intermediate transfer member was not soiled due to transfer failure, and the ink image was transferred 100% each time. From this, it was confirmed that the release agent was properly supplied from the supply means to the intermediate transfer member.
[0089]
【The invention's effect】
Since the present invention uses an intermediate transfer member having a porous body impregnated with a release agent or an ink-repellent porous body on its surface, there is no need to stabilize the image before transfer, and the intermediate transfer member An image can be accurately formed, and the formed image can be efficiently transferred to a recording medium.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an intermediate transfer member according to a first embodiment of the present invention, in which a three-dimensional network-like porous body layer is provided on a substrate, and the porous body layer is impregnated with a release agent. It is.
FIG. 2 is a cross-sectional view showing an example of replenishing means that can be used in the image forming apparatus of the present invention.
FIG. 3 is a cross-sectional view illustrating another example of a replenishing unit that can be used in the image forming apparatus of the present invention and an example of a replenishing amount regulating unit.
FIG. 4 is a schematic configuration diagram of an image forming apparatus of the present invention.
FIG. 5 is a schematic configuration diagram of another image forming apparatus of the present invention.
FIG. 6 is a schematic configuration diagram of still another image forming apparatus of the present invention.
7 is an image obtained by Example 3. FIG.
8 is an image obtained by Comparative Example 1. FIG.
FIG. 9 is a cross-sectional view showing still another example of replenishing means that can be used in the image forming apparatus of the present invention.
FIG. 10 is a cross-sectional view showing still another example of replenishing means that can be used in the image forming apparatus of the present invention.
FIG. 11 is a cross-sectional view showing still another example of replenishing means usable in the image forming apparatus of the present invention.
FIG. 12 is a cross-sectional view showing still another example of replenishing means that can be used in the image forming apparatus of the present invention.
FIG. 13 is a cross-sectional view showing still another example of replenishing means that can be used in the image forming apparatus of the present invention.
14 is a diagram illustrating a schematic configuration of an image forming apparatus used in Embodiment 4. FIG.
[Explanation of symbols]
  1, 22, 42112 Intermediate transfer member
  2,9 Mold release agent
  3Porous material
  7 Wick
  10, 34Application roll
  20, 40110 Image forming apparatus

Claims (17)

The image formed by the droplet ink particles on its surface an intermediate transfer member that is used to transfer the recording medium, comprising a release agent impregnated porous body surface, the porous body An intermediate transfer member in which a meniscus by the release agent is formed in a hole on the surface of The intermediate transfer member according to claim 1 multi porous body is a ink-repellent.   The intermediate transfer member according to claim 1, wherein the release agent is ink repellent.   The intermediate transfer member according to claim 1, wherein the release agent is a non-volatile liquid that is incompatible with an ink that forms an image.   The intermediate transfer member according to claim 1, wherein the release agent contains silicone oil. The intermediate transfer member according to any one of claims 1 to 5, wherein the porous body has a three-dimensional network structure. The intermediate transfer member according to claim 1 , wherein the polymorph is formed of a fluororesin or a polyolefin resin. The intermediate transfer member according to any one of claims 1 to 7 , wherein an average pore diameter of the polymorph is 0.01 to 100 µm. An image forming apparatus including an intermediate transfer member according to any one of claims 1 to 8. The image forming apparatus according to claim 9 , further comprising supply means for supplying a release agent to the intermediate transfer member. The image forming apparatus according to claim 10 , wherein the replenishing unit replenishes the release agent from a surface opposite to a surface on which the image of the intermediate transfer member is formed. The image forming apparatus according to claim 10 , wherein the replenishing unit includes a second porous body that contacts the porous body. Said replenishing means is an image forming apparatus according to claim 11 or 12 slides with said porous body of said intermediate transfer member. Said replenishing means is an image forming apparatus according to claim 11 or 12, driven with said porous body of said intermediate transfer member. The intermediate transfer member further comprises a porous substrate which is integral with the porous body, wherein the replenishing means image forming apparatus according to claim 11 or 12 slides or the driven and the porous substrate. The image forming apparatus according to claim 9 or 10 which is an ink jet recording apparatus. An intermediate transfer member used for transferring an image formed on a surface of an ink jet recording head for discharging droplet ink particles onto a recording medium, and a porous body impregnated with a release agent on the surface An intermediate transfer member provided with a meniscus formed by the release agent in holes on the surface of the porous body.

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