JP6428337B2 - Intermediate transfer body and image forming apparatus having the same - Google Patents

Description

  The present invention relates to an intermediate transfer member used in an image forming apparatus and an image forming apparatus including the intermediate transfer member.

  In an electrophotographic image forming apparatus, for example, a latent image formed on an electrostatic latent image carrier (also referred to as an image carrier or a photoreceptor) is developed with toner, and the resulting toner image is formed into an endless belt shape. An intermediate transfer member is temporarily held, and a toner image on the intermediate transfer member is transferred onto a recording material such as paper.

  As such an intermediate transfer member (also referred to as an intermediate transfer belt or a transfer member), as a measure for improving a transfer function such as image quality, for example, polyimide resin or polyphenylene sulfide is used as a resin base layer (simply a base layer or base layer). And a method of installing a surface layer on the surface has been devised.

  For example, Japanese Unexamined Patent Application Publication No. 2008-046463 (Patent Document 1) discloses that a precursor material having three or more acryloyl groups or methacryloyl groups is used as such a surface layer. Japanese Unexamined Patent Application Publication No. 2009-192901 (Patent Document 2) discloses a surface layer having a predetermined hardness.

JP 2008-046463 A JP 2009-192901 A

  As a surface layer as described above, from the viewpoint of imparting durability and functionality, a method of forming a layer by UV-curing (meth) acrylic monomers is common, but (meth) acrylic resin is accompanied by a reaction. There is a problem that curing shrinkage is large, and problems such as cracking and curling accompanying shrinkage cannot be avoided. In addition, there is a problem that smoothness due to the leveling effect at the time of coating the surface layer does not proceed well because it is easily influenced by the surface state of the resin base material layer. For this reason, when the resin base material layer is produced by extrusion molding or the like, surface irregularities such as weld lines and sink marks generated in the resin base material layer are not smoothed by the surface layer, and as a result, the non-uniformity is imaged. The image defect that appears above is also a problem.

  For this problem, for example, the use of a large molecular weight acrylic monomer or a method of lowering the ratio of acrylic groups per volume that undergoes a polymerization reaction during the photocuring reaction by condensing the acrylic monomer in advance may be considered. However, the applicability, the flexibility, the reactivity, etc. accompanying the increase in molecular weight cannot be avoided, and the fundamental solution has not been achieved.

  The present invention has been made in view of the above situation, and an object of the present invention is to provide an intermediate transfer member which is excellent in surface smoothness and hardly causes cracks and image defects.

  The intermediate transfer member of the present invention is an image forming apparatus that primarily transfers a toner image carried on an electrostatic latent image carrier to an intermediate transfer member, and then secondarily transfers the toner image from the intermediate transfer member to a recording material. And having an endless belt-like shape and including at least a resin base material layer and a surface layer, and the surface layer is made of a cured (meth) acrylic resin, and the cured (meta) The acrylic resin includes at least a structural unit derived from a polyfunctional (meth) acrylic acid derivative and a structural unit derived from a (meth) acrylic acid derivative having an actinic ray decomposable structure.

Here, (meth) acrylic acid derivative having the above-described active light degradable structure preferably an amide methylol structure represented by -CO-NH-CH ₂ -O- comprising at least one in the molecule. Further, the (meth) acrylic acid derivative having the actinic ray decomposable structure is more preferably represented by the following structural formula (1).

(Wherein R1 represents a hydrogen atom or a methyl group, R2 represents a hydrogen atom; an alkyl group; an alkyl group having an aromatic ring; an alkyl having an aromatic ring having any one or more of a hydroxyl group, a carboxy group and an alkyl group. A group; a polyalkylene glycol group; a polyalkylene glycol group having an aromatic ring; and an aryl group.)
The cured (meth) acrylic resin is preferably cured by irradiation with actinic rays, and the resin substrate layer is preferably made of polyphenylene sulfide.

  The present invention also relates to an image forming apparatus provided with any of the above intermediate transfer members.

  The intermediate transfer member of the present invention has an excellent effect that it is excellent in surface smoothness and hardly causes cracks and image defects.

1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention.

  Hereinafter, embodiments according to the present invention will be described in more detail. In the following embodiments, the same reference numerals denote the same or corresponding parts when they are described with reference to the drawings.

<Intermediate transfer member>
The intermediate transfer member according to the present embodiment (hereinafter simply referred to as “this embodiment”) first transfers the toner image carried on the electrostatic latent image carrier to the intermediate transfer member, and then transfers the toner image to the intermediate transfer member. It is used in an image forming apparatus that performs secondary transfer from an intermediate transfer member to a recording material. Details of such an image forming apparatus will be described later.

  Such an intermediate transfer member has an endless belt shape and includes at least a resin base material layer and a surface layer. Here, the endless belt-like shape has this literal shape, and is formed, for example, conceptually (geometrically) by joining both ends of one long sheet-like material. However, in practice, a seamless belt-like or cylindrical shape is preferable.

  And such an intermediate transfer body can contain other arbitrary structures, as long as it contains at least the resin base material layer and the surface layer. As such other configurations, for example, a configuration in which a resin base layer, an adhesive layer, and a surface layer are formed in this order, a configuration in which a resin base layer, an elastic layer, and a surface layer are formed in this order, a back coat layer, a resin base The structure etc. which formed the material layer and the surface layer in this order are included.

  Such an intermediate transfer member preferably has high durability while ensuring electrical and physical performance by the synergistic action of the resin base layer and the surface layer.

Hereinafter, each component constituting the intermediate transfer member will be described.
<Resin substrate layer>
As the resin base material layer included in the intermediate transfer member of the present embodiment, a conventionally known one used for this type of application can be used without any particular limitation. For example, such a resin base layer is made of resin materials such as polyimide, polyamideimide, polycarbonate, polyphenylene sulfide, polyvinylidene fluoride, polyalkylene terephthalate (polybutylene terephthalate, etc.), polyether, polyether ketone, polyether ether ketone, etc. Can be configured.

  In particular, polyphenylene sulfide, polycarbonate, polyalkylene terephthalate such as polybutylene terephthalate, polyether ether ketone, etc., which can be formed into a film by extrusion molding with a thermoplastic resin, will cause image defects due to streaks, sink marks, etc. during molding. Among them, polyphenylene sulfide is particularly preferable because it can achieve both strength as an intermediate transfer substrate and easy processability at the time of molding.

<Surface layer>
The surface layer included in the intermediate transfer member of the present embodiment is preferably formed on the above resin base material layer so as to cover the entire surface of the resin base material layer. In this case, the surface of the resin base material layer means the surface on the side where the toner image is transferred (formed), but the surface layer is formed on the surface where the toner image is not transferred (formed) (that is, the back surface). Even if a part of the surface on the resin base material layer is not covered with the surface layer, it does not depart from the present embodiment as long as the above-described effects are exhibited.

  Such a surface layer is made of a cured (meth) acrylic resin, and the cured (meth) acrylic resin has a structural unit derived from a polyfunctional (meth) acrylic acid derivative and an active light-decomposable structure (meth). And at least a structural unit derived from an acrylic acid derivative. It is presumed that the cured (meth) acrylic resin has such a configuration and exhibits the following action.

  That is, the cured (meth) acrylic resin is cured by irradiating with actinic rays, but the actinic ray-decomposable structure is decomposed by actinic rays at the time of curing, and the resin is constituted by this decomposition reaction. It is thought that the van der Waals radius of the molecule increases. This increase reduces the curing shrinkage of the resin, thereby preventing cracking of the surface layer and curling of the intermediate transfer body itself, which are thought to be caused by this curing shrinkage, as well as unevenness on the surface of the resin base material layer. It is presumed that the surface of the intermediate transfer member becomes smooth when the surface layer covers the surface. Therefore, when an image is formed using an image forming apparatus provided with this intermediate transfer member, the occurrence of image defects is prevented.

  Such a surface layer cracks due to stress after forming the surface layer by causing a shrinkage of the film because the free volume decreases at the time of curing because of the problem that has occurred in the surface layer of the prior art using a photocurable acrylic resin. The present inventors have succeeded in overcoming the problem that (cracking) occurs and the problem that it was difficult to reduce the roughness of the surface shape of the resin base material layer due to the leveling effect of the surface layer.

In such an embodiment, the (meth) acrylic acid derivative having an actinic ray-decomposable structure includes at least one amide methylol structure represented by —CO—NH—CH ₂ —O— in the molecule. preferable. Such an amide methylol structure corresponds to an actinic ray-decomposable structure and exhibits the property of decomposing when irradiated with actinic rays. More specifically, in such an amide methylol structure, the methylol moiety is cleaved simultaneously with the polymerization of the (meth) acryl moiety during irradiation with actinic rays, and the decomposition reaction proceeds. This decomposition reaction is considered to cause an increase in the van der Waals radius as described above. The amidomethylol structure is exemplified as a suitable example of the actinic photodegradable structure because such an increase in van der Waals radii remarkably occurs.

  As described above, the cured (meth) acrylic resin of this embodiment is preferably one that has been cured by irradiation with actinic rays. Here, active light means UV (ultraviolet light) or visible light. As long as the effect | action which hardens a (meth) acrylic resin precursor is shown, the wavelength is not specifically limited.

  On the other hand, the actinic ray-decomposable structure as described above means a structure that decomposes upon irradiation with actinic rays. In this case, the actinic rays also mean UV (ultraviolet rays) or visible light as described above. In this case, the wavelength is not particularly limited as long as it exhibits an action of decomposing the active light-decomposable structure. The actinic ray for curing the cured (meth) acrylic resin and the actinic ray for decomposing the actinic ray decomposable structure may be the same (same wavelength) or different (different wavelengths). Also) good. Therefore, when simultaneously curing the (meth) acrylic resin and decomposing the actinic ray-decomposable structure, an actinic ray containing both the actinic ray causing the curing and the actinic ray causing the decomposition is irradiated. It is preferable.

In this embodiment, “(meth) acryl” means “acryl or methacryl”, and “(meth) acrylic resin” means “acrylic resin or methacrylic resin”. Further, “the cured (meth) acrylic resin includes at least a structural unit derived from a polyfunctional (meth) acrylic acid derivative and a structural unit derived from a (meth) acrylic acid derivative having an actinic ray decomposable structure”. Is that a cured (meth) acrylic resin is formed by at least copolymerizing a polyfunctional (meth) acrylic acid derivative as a monomer and a (meth) acrylic acid derivative having an actinic ray-decomposable structure as a monomer. The chemical structure after the copolymerization of the polyfunctional (meth) acrylic acid derivative and the chemical structure after the copolymerization of the (meth) acrylic acid derivative having an actinic ray decomposable structure are contained in the cured (meth) acrylic resin. It is included as a structural unit. However, in this case, the chemical structure after copolymerization of the (meth) acrylic acid derivative having an actinic ray-decomposable structure naturally includes the chemical structure after decomposition after irradiation with actinic rays that decompose the decomposable structure. The chemical structure may be only the chemical structure after decomposition. In addition, the chemical structure after the decomposition corresponds to a portion of R—CO—NH—CH ₂ —OH when the active light decomposable structure is an amide methylol structure.

  “(Meth) acrylic acid derivative” means a compound having a chemical structure derived from (meth) acrylic acid (that is, acrylic acid or methacrylic acid) in terms of chemical structure, and “polyfunctional” means polymerizable. It means having two or more groups. More specifically, the “polyfunctional (meth) acrylic acid derivative” means one having two or more (meth) acryloyloxy groups in one molecule. Such “polyfunctional (meth) acrylic acid derivatives” may contain two or more different structures. The (meth) acryloyloxy group means an acryloyloxy group or a methacryloyloxy group.

In particular, the “(meth) acrylic acid derivative” in the “(meth) acrylic acid derivative having an actinic ray-decomposable structure” more specifically refers to (meth) acrylamide (that is, acrylamide or methacrylamide) in terms of chemical structure. In addition, these themselves mean compounds having a chemical structure derived from (meth) acrylic acid), and more specifically, have a (meth) acryloylamino group. The (meth) acryloylamino group means an acryloylamino group (CH ₂ ═CH—CO—NH—) or a methacryloylamino group (CH ₂ ═C (CH ₃ ) —CO—NH—).

  Further, “(meth) acrylic resin” generally means a polymer of acrylic acid ester or methacrylic acid ester, but is not limited to this in this embodiment, and an acryloyl group or a methacryloyl group is polymerized. Widely include those of structure. Although the molecular weight of such (meth) acrylic resin is not particularly limited, it is formed as a surface layer on a resin base layer and then formed by photocuring, so that its molecular weight is from the viewpoint of low volatility and controllable viscosity. Is preferably in the range of 200-2000.

  Here, specific examples of the polyfunctional (meth) acrylic acid derivative include, for example, bis (2-acryloxyethyl) -hydroxyethyl-isocyanurate, 1,6-hexanediol diacrylate, 1,4-butanediol diester. Bifunctional monomers such as acrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, neopentyl glycol diacrylate hydroxypivalate, urethane acrylate; trimethylolpropane triacrylate, pentaerythritol triacrylate, tris ( (Acryloxyethyl) isocyanurate, ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, urethane acrylate, polyvalent acrylate Trifunctional or more polyfunctional compounds such as ester compounds synthesized from coal and polybasic acids and (meth) acrylic acid (for example, ester compounds synthesized from trimethylolethane / succinic acid / acrylic acid = 2/1/4 mol) A functional monomer etc. are mentioned. The polyfunctional (meth) acrylic acid derivative is preferably a trifunctional or higher polyfunctional acrylate from the viewpoint of increasing the hardness of the surface layer.

  On the other hand, when the specific example of the (meth) acrylic acid derivative which has the said actinic-light-decomposable structure is given, what is represented by the following structural formula (1) can be mentioned as a suitable example. In addition, the (meth) acrylic acid derivative in the (meth) acrylic acid derivative having an actinic ray-decomposable structure is chemically structurally similar to the (meth) acrylic acid derivative in the polyfunctional (meth) acrylic acid derivative. It means a compound having a chemical structure derived from acrylic acid (that is, acrylic acid or methacrylic acid), and more specifically, a compound having a (meth) acryloylamino group in the structure. Such “(meth) acrylic acid derivative having an actinic ray-decomposable structure” may contain two or more different structures.

(Wherein R1 represents a hydrogen atom or a methyl group, R2 represents a hydrogen atom; an alkyl group; an alkyl group having an aromatic ring; an alkyl having an aromatic ring having any one or more of a hydroxyl group, a carboxy group and an alkyl group. A group; a polyalkylene glycol group; a polyalkylene glycol group having an aromatic ring; and an aryl group.)
Here, the alkyl group is preferably, for example, an alkyl group having 1 to 30 carbon atoms, the aromatic ring is preferably a benzene ring, a naphthalene ring, an anthracene ring, or a phenanthrene ring, and the polyalkylene glycol group is a polyethylene glycol group ( The number of carbon atoms is particularly preferably 4 to 30), and the aryl group is preferably a phenyl group, a naphthyl group, an anthranyl group, or a phenanthranyl group.

Note that the polyethylene glycol group, - although "CH ₂ CH ₂ O-'has n number repeated structure (including but n = 1 and a" -CH ₂ CH ₂ O- "group), bonded to an oxygen atom The terminal may be a hydrogen atom or a methyl group. The alkyl group having an aromatic ring may be one in which an aromatic ring and an alkyl group are bonded by oxygen.

  Preferred examples of R2 include a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a phenyl group, a 1-decylpentyl group, and a glycidyl group.

  The cured (meth) acrylic resin in the present embodiment includes 50 to 80% by mass of a structural unit derived from a polyfunctional (meth) acrylic acid derivative, and is derived from a (meth) acrylic acid derivative having an actinic ray decomposable structure. It is preferable to contain 20-50 mass% of a unit. Since the structural unit derived from the polyfunctional (meth) acrylic acid derivative affects the strength of the surface layer, if its content is less than 50% by mass, it tends to cause a decrease in durability of the transfer belt, poor cleaning, etc. If the amount exceeds 80% by mass, the amount of shrinkage of the resin increases, so that it tends to be impossible to completely suppress the occurrence of cracks due to shrinkage and insufficient smoothing of the film. The structural unit and content of the cured (meth) acrylic resin reflect the structure and blending amount of the raw material monomer before the polymerization reaction, but the hydroxyl group generated after the curing reaction should be measured by a known analysis. Thus, the content can be identified.

  In addition, in the structural unit derived from the (meth) acrylic acid derivative having an actinic ray decomposable structure, there is a part that decomposes and falls off from the structural unit after irradiation with an actinic ray. It shall be included in the mass of the structural unit derived from the (meth) acrylic acid derivative which has an actinic-light-decomposable structure.

  Such a surface layer can be formed by applying a coating solution for forming a surface layer on the resin substrate layer and then curing it. Examples of the coating method include spray coating.

  The coating solution for forming the surface layer includes polyfunctional (meth) acrylic acid derivatives and (meth) acrylic acid derivatives having an actinic ray-decomposable structure, as well as surface-treated metal oxide fine particles, polymerization initiators, solvents, etc. The other components are optionally included.

  As a method for preparing the coating solution for forming the surface layer, there may be mentioned a method in which the above-mentioned components are added to the solvent at a ratio of solid content (content) of 3 to 30% by mass and dispersed by, for example, a wet media dispersion type apparatus.

  The polymerization initiator contained in the coating solution for forming the surface layer can be used without particular limitation as long as it can polymerize the actinic ray curable composition with actinic rays such as light. As the polymerization initiator, for example, a photopolymerization initiator such as an acetophenone compound, a benzoin ether compound, a benzophenone compound, a sulfur compound, an azo compound, a peroxide compound, or a phosphine oxide compound can be used.

  The coating solution for forming the surface layer preferably contains a solvent because the coating property (workability) is good. Specific examples of the solvent include ethanol, isopropanol, butanol, 2-butanol, toluene, xylene, acetone, methyl ethyl ketone, ethyl acetate, and butyl acetate. The viscosity of the surface layer forming coating solution is preferably 10 to 100 cP.

  Examples of the curing method include a method of irradiating actinic rays. The actinic ray can be used without limitation as long as it is UV (ultraviolet light) or visible light. As the ultraviolet light source, any light source that generates ultraviolet light can be used. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used. An ArF excimer laser, a KrF excimer laser, an excimer lamp, synchrotron radiation, or the like can also be used. In order to irradiate the spot-like active light, it is preferable to use an ultraviolet laser.

The irradiation conditions vary depending on individual light sources, illuminance, curing unevenness, hardness, curing time, taking into account the cure rate, 50 mW / cm ² or more, more preferably, at 80mW / cm ² ~2000W / cm ² is there. Illuminance indicates a value measured with UIT250 (USHIO INC.).

  The irradiation time of actinic rays is preferably from 0.5 seconds to 5 minutes, and more preferably from 3 seconds to 2 minutes from the viewpoint of curing efficiency and work efficiency.

  The atmosphere during irradiation with actinic rays can be cured without problems in an air atmosphere, but the oxygen concentration in the atmosphere is preferably 5% or less, particularly preferably 1% or less in consideration of curing unevenness, curing time, and the like. In order to obtain this atmosphere, it is effective to introduce nitrogen gas or the like. The oxygen concentration indicates a value measured with an oxygen concentration meter “OX100” (manufactured by Yokogawa Electric Corporation) for atmospheric gas management.

  In addition, it is preferable to dry after apply | coating the coating liquid for surface layer formation on the resin base material layer. This removes the solvent. The coating film may be dried either before or after the polymerization of the polymerizable component and during the polymerization, and can be selected as appropriate by combining them. Specifically, the fluidity of the coating film is determined. It is preferable to perform the primary drying to such an extent that the polymerizable component is polymerized, and then to perform secondary drying in order to make the amount of the volatile substance in the surface layer a specified amount. The method for drying the coating film can be appropriately selected depending on the type of solvent, the layer thickness of the surface layer to be formed, etc. The drying temperature is preferably 40 to 100 ° C., more preferably about 60 ° C. It is. The drying time is preferably, for example, 1 to 5 minutes, and more preferably about 3 minutes.

<Additives>
Said resin base material layer and surface layer can contain an additive, respectively. Examples of such additives include photocuring initiators, conductive particles, various fillers (mainly for the purpose of improving strength), and the like.

<Image forming apparatus>
The image forming apparatus according to the present embodiment includes the intermediate transfer member described above. As long as such an intermediate transfer member is provided, other configurations may be adopted without any particular limitations on conventionally known configurations. Can do.

  Hereinafter, the image forming apparatus of this embodiment will be described with reference to FIG. FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus according to the present embodiment.

  An image forming apparatus 1 in FIG. 1 forms an image on a recording material by a known electrophotographic method, and includes an image processing unit 10, a transfer unit 20, a paper feeding unit 30, a fixing unit 40, and a control unit. 45, and selectively executes color and monochrome printing based on a print job received from an external terminal device (not shown) via a network (for example, LAN).

  The image processing unit 10 includes image forming units 10Y to 10K corresponding to development colors of yellow (Y), magenta (M), cyan (C), and black (K). The image forming unit 10Y includes a photosensitive drum 11 that is an electrostatic latent image carrier, a charger 12, an exposure unit 13, a developing unit 14, a primary transfer roller 15, a cleaner 16, and the like disposed around the photosensitive drum 11. The charger 12 charges the peripheral surface of the photosensitive drum 11 that rotates in the direction indicated by the arrow A.

  The exposure unit 13 exposes and scans the charged photosensitive drum 11 with laser light to form an electrostatic latent image on the photosensitive drum 11. The developing unit 14 contains a developer containing toner, and develops the electrostatic latent image on the photosensitive drum 11 with the toner, whereby a Y-color toner image is formed on the photosensitive drum 11. . That is, the toner image is carried on the electrostatic latent image carrier.

  The primary transfer roller 15 transfers the Y color toner image on the photosensitive drum 11 onto the intermediate transfer member 21 by electrostatic action. That is, the toner image is primarily transferred to the intermediate transfer member. The cleaner 16 cleans residual toner remaining on the photosensitive drum 11Y after transfer. The other image forming units 10M to 10K have the same configuration as the image forming unit 10Y, and the reference numerals are omitted in FIG. The transfer unit 20 includes an intermediate transfer member 21 that is stretched around a driving roller 24 and a driven roller 25 and circulates in the direction of the arrow. The intermediate transfer member 21 has a seamless belt shape (that is, an endless belt shape), and is a cylindrical shape obtained by injection molding or centrifugal molding of a resin material so as to have a desired peripheral length determined by design.

  When color printing (color mode) is executed, a corresponding color toner is formed on the photosensitive drum 11 for each of the image forming units 10M to 10K, and each of the formed toner images is displayed. Transferred onto the intermediate transfer member 21. The image forming operations for the respective colors Y to K are executed while shifting the timing from the upstream side to the downstream side so that the toner images of the respective colors are transferred in a superimposed manner at the same position of the traveling intermediate transfer member 21. The

  The paper feeding unit 30 feeds the sheet S, which is a recording material, one by one from the paper feeding cassette in accordance with the above image forming timing, and directs the fed sheet S on the conveyance path 31 to the secondary transfer roller 22. Transport. When the sheet S conveyed to the secondary transfer roller 22 passes between the secondary transfer roller 22 and the intermediate transfer member 21, each color toner image formed on the intermediate transfer member 21 is transferred to the secondary transfer roller 22. Secondary transfer is collectively performed on the sheet S by electrostatic action. That is, the toner image is secondarily transferred from the intermediate transfer member to the recording material.

  The sheet S after the respective color toner images are secondarily transferred is conveyed to the fixing unit 40 and heated and pressed in the fixing unit 40, whereby the toner on the surface is fused and fixed to the surface of the sheet S. Then, the paper is discharged onto the paper discharge tray 33 by the paper discharge roller 32. In this way, an image corresponding to the toner image is formed on the recording material.

  In the above description, the operation in the case of executing the color mode has been described. However, in the case of executing monochrome (for example, black) printing (monochrome mode), only the black image forming unit 10K is driven, and the above-described operation is performed. By the same operation as the above, black image formation (printing) is performed on the recording sheet S through the steps of charging, exposing, developing, transferring, and fixing the black color.

  The toner or toner pattern that has not been transferred onto the recording sheet S on the intermediate transfer member 21 is removed by a cleaning blade 26 disposed at a position facing the driven roller 25 with the intermediate transfer member 21 interposed therebetween. Further, a density detection sensor 23 made of, for example, a reflection type photoelectric sensor is disposed on the downstream side of the image forming unit 10K in the traveling direction of the intermediate transfer body 21, and the toner pattern formed on the intermediate transfer body 21 is arranged. Detect concentration.

  The control unit 45 controls each unit based on the print job data received from the external terminal device via the network to execute a smooth print operation. Note that an operation panel 35 is disposed at a position on the front side and the upper side of the apparatus main body of the image forming apparatus 1 that is easy for the user to operate. The operation panel 35 includes buttons for receiving various instructions from the user, a touch panel type liquid crystal display unit, and the like, and can transmit the received instruction content to the control unit 45.

  Examples of such an image forming apparatus include an electrophotographic image forming apparatus such as a copying machine, a printer, a digital printing machine, and a simple printing machine, which may be either a dry type or a wet type. The image forming apparatus is particularly effective.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Manufacture of resin base material layer A1>
100 parts by weight of polyphenylene sulfide resin (trade name: “E2180”, manufactured by Toray Industries, Inc.), 16 parts by weight of conductive filler (trade name: “Furness # 3030B”, manufactured by Mitsubishi Chemical Corporation), graft copolymer (trade name: “Modiper” A4400 "(manufactured by Nippon Oil & Fats Co., Ltd.) 1 part by mass and 0.2 parts by mass of calcium montanate were charged into a single screw extruder and melt-kneaded to obtain a resin mixture.

  Subsequently, the kneaded resin mixture was extruded into a seamless belt shape from an annular die having a slit-like seamless belt-shaped discharge port attached to the tip of the single-screw extruder. Next, the extruded seamless belt-shaped resin mixture is externally inserted into a cylindrical cooling cylinder provided at the tip of the discharge port, cooled, and solidified to form a seamless cylindrical shape having a thickness of 150 μm. “Resin substrate layer A1” having an endless belt shape was produced. The ratio D / d between the diameter D of the annular die and the diameter d of the cooling cylinder was 1.00.

  When the surface roughness in the circumferential direction of the obtained “resin substrate layer A1” was measured, it was Rz = 1.4 μm (Rz was a ten-point average roughness Rzjis: JIS B0601: '94 measurement reference length 20 μm). .

<Manufacture of resin base material layer A2>
85 parts by mass of polyetheretherketone (trade name: “Victrex PEEK381G”, manufactured by Victrex) and 16 parts by mass of conductive filler (product name: “Furness # 3030B”, manufactured by Mitsubishi Chemical) were charged into a single screw extruder. Then, the mixture was melt kneaded to obtain a resin mixture.

  Subsequently, the kneaded resin mixture was extruded into a seamless belt shape from an annular die having a slit-like seamless belt-shaped discharge port attached to the tip of the single-screw extruder. Next, the extruded seamless belt-shaped resin mixture is externally inserted into a cylindrical cooling cylinder provided at the tip of the discharge port, cooled, and solidified to form a seamless cylindrical shape having a thickness of 100 μm. “Resin substrate layer A2” having an endless belt-like shape was produced. The ratio D / d between the diameter D of the annular die and the diameter d of the cooling cylinder was 0.90.

  When the surface roughness in the circumferential direction of the obtained “resin base layer A2” was measured, it was Rz = 1.5 μm (Rz was 10-point average roughness Rzjis: JIS B0601: '94 measurement reference length 20 μm). .

<Manufacture of resin base material layer A3>
N-methyl-2-pyrrolidone (NMP) solution of polyamic acid composed of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and p-phenylenediamine (PDA) (trade name: “ Added dry oxidized carbon black (trade name: “SPECIAL BLACK4”, manufactured by Degussa, pH 3.0, volatile content: 14.0%) to Euvarnish S (solid content: 18% by mass), manufactured by Ube Industries Then, by using a collision type disperser (trade name: “GeanusPY”, manufactured by Seanas), colliding after dividing into two parts with a pressure of 200 MPa and a minimum area of 1.4 mm ² , and again passing through a path divided into two parts five times Mixing was performed to obtain a polyamic acid solution containing carbon black. In addition, the addition amount at the time of the addition was 23 parts by mass of oxidized carbon black with respect to 100 parts by mass of the polyamic acid.

  Subsequently, this polyamic acid solution containing carbon black was applied to the inner peripheral surface of the cylindrical mold to a thickness of 0.5 mm via a dispenser, and rotated at 1500 rpm for 15 minutes to form a spread layer having a uniform thickness. . Subsequently, hot air of 60 ° C. was applied for 30 minutes from the outside of the mold while rotating at 250 rpm, and then heated at 150 ° C. for 60 minutes. Thereafter, the temperature was raised to 360 ° C. at a rate of 2 ° C./min, and further heated at 360 ° C. for 30 minutes to complete removal of the solvent, dehydration ring closure, water removal, and imide conversion reaction. Thereafter, the temperature was returned to room temperature and peeled from the cylindrical mold to produce “resin substrate layer A3” having an endless belt-like shape with a thickness of 0.1 mm.

  When the surface roughness in the circumferential direction of the obtained “resin base material layer A3” was measured, it was Rz = 0.9 μm (Rz was 10-point average roughness Rzjis: JIS B0601: '94 measurement reference length 20 μm). .

<Example 1>
Trifunctional acrylic acid monomer (trade name: “KAYARAD PET30”, manufactured by Nippon Kayaku Co., Ltd.) 60 parts by mass as a polyfunctional (meth) acrylic acid derivative, monomer C1 ((meth) acrylic acid derivative having an active photodegradable structure) 40 parts by mass of the following structural formula (2), polymerization initiator (trade name: “Irgacure 184”, manufactured by Ciba Specialty Chemicals), conductive filler (trade name: “T-1”, Mitsubishi Materials Corporation) 50 parts by mass, inorganic filler (trade name: “MEK Si sol”, manufactured by Nissan Chemical Co., Ltd.) 20 parts by mass, lubricant filler (trade name: “NS-10S”, manufactured by Kitamura Chemical Co., Ltd.), 30 parts by mass, leveling agent (Product name: “KF-54”, manufactured by Shin-Etsu Silicone Co., Ltd.) 0.1 parts by mass and 1500 parts by mass of diluting solvent (2-butanol) are mixed and stirred to form a surface layer. To prepare a coating solution.

Next, the surface layer coating solution prepared above is spray-coated on the outer peripheral surface of the resin base material layer A1, subjected to primary drying at 40 ° C. for 30 minutes, and then 600 mJ / mm with a mercury lamp having an ultraviolet intensity of 1 kw / cm ^2. The intermediate transfer body 1 having a surface layer having a thickness of 4 μm formed on the resin base material layer was prepared by curing with an accumulated light quantity of cm ² .

  In addition, the surface layer of this Example is a (meth) acrylic acid derivative having actinic ray decomposable structure, which is made of a cured acrylic resin, which is cured by irradiation with the above-mentioned ultraviolet rays that are actinic rays. It was confirmed by IR analysis that the amidomethylol structure of monomer C1 was decomposed.

  That is, the surface layer of this example is made of a cured acrylic resin, and this cured acrylic resin is a (meth) acrylic acid derivative having a structural unit derived from a polyfunctional (meth) acrylic acid derivative and an actinic ray decomposable structure. And a structural unit derived from.

<Example 2>
Intermediate transfer was carried out in the same manner as in Example 1, except that 40 parts by mass of monomer C2 (the following structural formula (3)) was used instead of monomer C1 as the (meth) acrylic acid derivative having an actinic ray-decomposable structure. Body 2 was produced.

  In addition, the surface layer of this Example 2 is made of a cured acrylic resin, which is cured by irradiation with the above-described ultraviolet ray that is an actinic ray, and is a (meth) acrylic acid derivative having an actinic ray decomposable structure. The amidomethylol structure of a certain monomer C2 is decomposed.

  That is, the surface layer of Example 2 is made of a cured acrylic resin, and the cured acrylic resin is a (meth) acrylic acid having a structural unit derived from a polyfunctional (meth) acrylic acid derivative and an actinic ray decomposable structure. And a structural unit derived from a derivative.

<Examples 3 to 13 and Comparative Examples 1 to 4>
In the same manner as in Example 1, using the resin base layer, the polyfunctional (meth) acrylic acid derivative, and the (meth) acrylic acid derivative having an actinic ray decomposable structure described in Table 1 below, Transfer members 3 to 13 and comparative intermediate transfer members 1 to 4 were prepared.

  In addition, although C6-C8 used for Comparative Examples 2-4 is described in the term of the (meth) acrylic acid derivative which has actinic-light-decomposable structure for convenience in Table 1, it has actinic-photodegradable structure ( It is an acrylic monomer that is not a (meth) acrylic acid derivative.

  The surface layers of Examples 3 to 13 are made of a cured (meth) acrylic resin and cured by irradiation with the above-described ultraviolet rays that are actinic rays, and have (meth) acrylic acid having an actinic ray-decomposable structure. The amide methylol structure of each monomer that is a derivative is decomposed.

  That is, the surface layers of Examples 3 to 13 are made of a cured (meth) acrylic resin, and the cured (meth) acrylic resin is composed of structural units derived from polyfunctional (meth) acrylic acid derivatives and actinic ray decomposability. And a structural unit derived from a (meth) acrylic acid derivative having a structure.

The notations in Table 1 mean the following. Moreover, the numerical value which shows content represents a mass part. For example, the intermediate transfer member 3 of Example 3 has 70 parts by mass of “KAYARAD PET30” as a polyfunctional (meth) acrylic acid derivative and an active light-decomposable structure on the resin substrate layer A1 as the resin substrate layer. It represents that a surface layer having a thickness of 4 μm was formed under the same conditions as in Example 1 using the same coating solution for surface layer as in Example 1 except that 30 parts by mass of monomer C1 was included as the (meth) acrylic acid derivative. Yes.
A1: Resin base material layer A1
A2: Resin base material layer A2
A3: Resin base material layer A3
B1: “KAYARAD PET30” (pentaerythritol triacrylate which is a trifunctional acrylic acid monomer) used in Example 1
B2: Ditrimethylolpropane tetraacrylate which is a tetrafunctional acrylic acid monomer (trade name: “AD-TMP”, manufactured by Shin-Nakamura Chemical Co., Ltd.)
B3: Trimethylolpropane trimethacrylate, a trifunctional methacrylic acid monomer (trade name: “TMPT”, manufactured by Shin-Nakamura Chemical Co., Ltd.)
C3: Monomer C3 (the following structural formula (4))
C4: Monomer C4 (the following structural formula (5))
C5: Monomer C5 (the following structural formula (6))
C6: Methoxypolyethylene glycol acrylate (trade name: “Light acrylate 130A”, manufactured by Kyoeisha Co., Ltd.)
C7: Phenoxyethyl acrylate (trade name: “Biscoat # 192”, manufactured by Osaka Organic Chemical Industry Co., Ltd.)
C8: Dipentaerythritol hexaacrylate (trade name: “Light acrylate PE-4A”, manufactured by Kyoeisha Chemical Co., Ltd.)
C10: Monomer C10 (the following structural formula (7))
C11: Monomer C11 (the following structural formula (8)).

<Evaluation>
<Surface roughness Rz>
The surface roughness Rz in the circumferential direction was measured for each intermediate transfer member of the example and the comparative example. The surface roughness Rz (ten-point average roughness Rzjis) was measured at a measurement standard length of 20 μm according to the method of JIS B0601: '94. The surface roughness measuring machine used was an evaluation type surface roughness measuring machine (trade name: “Surf Test”, manufactured by Mitutoyo Corporation). The results are shown in the “Surface roughness Rz” section of Table 1.

<Image noise>
Set each intermediate transfer member of the example and comparative example on a full-color copying machine (trade name: “Bizhub C454e”, manufactured by Konica Minolta), transfer the four-color toner images of yellow, magenta, cyan, and black, and then The image quality was determined by visual observation of the image on the surface of the intermediate transfer member and the image of the recording material after transfer. Judgment criteria are as follows.
A: Good with no image noise on the recording material.
B: Minor image noise was generated on the recording material, but it was improved by adjusting the transfer current.
C: Minor image noise was generated on the recording material, and even when the transfer current was adjusted, there was no improvement.
D: Striped image noise was generated on the recording material.

  In the above judgment criteria, B or higher, which can be improved by adjusting transfer conditions (transfer current control) of the copying machine, was determined to be acceptable (that is, it can be determined that image defects are unlikely to occur). The results are shown in the “Image Noise” section of Table 1.

  In the above full-color copying machine, image formation is performed in which the toner image carried on the electrostatic latent image carrier is primarily transferred to the intermediate transfer member, and then the toner image is secondarily transferred from the intermediate transfer member to the recording material. A device, schematically shown in FIG.

<Transfer efficiency>
Each intermediate transfer member of the example and the comparative example was set on a full-color copying machine (trade name: “Bizhub C454e”, manufactured by Konica Minolta Co., Ltd.), and 50,000 actual shot tests were performed to evaluate transfer efficiency.

  Specifically, the toner transfer performance in secondary transfer when a two-color overlapping solid image of magenta and cyan was printed was evaluated as transfer efficiency. The transfer efficiency was the ratio of the toner mass of the toner image transferred onto the recording material to the toner mass of the toner image transferred onto the intermediate transfer member. The specific measurement method is as follows.

  That is, a toner having a predetermined area (three points of 10 mm × 50 mm) on the intermediate transfer body after the primary transfer and before the secondary transfer is collected with an adhesive tape having a known weight, and before the secondary transfer. The toner weight (A) was measured. Next, the transfer residual toner on the intermediate transfer member after the secondary transfer was collected in the same manner as described above, the weight (B) of the transfer residual toner was determined, and the transfer efficiency (η) was determined from the following equation.

η = (1−B / A) × 100 (%)
The transfer efficiency is determined to be 85% or more (that is, it is determined that image defects are unlikely to occur), and the transfer efficiency at the initial stage (after 100 sheets of actual images) and after printing (after 50,000 sheets of actual images) is measured. Judgment was made as follows. The results are shown in the “Transfer efficiency” section of Table 1.
A: The transfer efficiency is 95% or more both in the initial stage and after printing.
B: 95% or more at the initial stage and 85% or more after printing.
C: Deteriorated to 95% or more at the initial stage and less than 85% after printing.
D: Deteriorated to less than 95% in the initial stage and less than 85% after printing.

<Crack resistance>
The intermediate transfer members of Examples and Comparative Examples were wound around cylindrical members of φ5 mm, φ10 mm, and φ20 mm, held for 60 seconds, and then the surface was observed to observe the state of cracks. Evaluation was performed according to the following evaluation criteria. The results are shown in the “Crack resistance” section of Table 1.
A: Cracks did not occur in any of φ5 mm, φ10 mm, and φ20 mm.
B: Cracks occurred at φ5 mm, but no cracks occurred at φ10 mm and φ20 mm.
C: Cracks occurred at φ5 mm and φ10 mm, but no crack occurred at φ20 mm.
D: Cracks occurred in any of φ5 mm, φ10 mm, and φ20 mm. Or the surface layer peeled.

  As is clear from Table 1, the intermediate transfer members of the examples have excellent effects of being excellent in surface smoothness and being less prone to cracks and image defects compared to the intermediate transfer members of the comparative examples. It was confirmed that Such excellent effects include a structural unit in which the cured (meth) acrylic resin constituting the surface layer of the intermediate transfer body is derived from a polyfunctional (meth) acrylic acid derivative, and a (meth) acrylic acid derivative having an actinic ray decomposable structure. It is apparent that it is produced because it has a structure including at least a structural unit derived from the above.

  Although the embodiments and examples of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Image forming apparatus, 10 Image process part, 11 Photosensitive drum, 12 Charger, 13 Exposure part, 14 Developing part, 15 Primary transfer roller, 16 Cleaner, 20 Transfer part, 21 Intermediate transfer body, 22 Secondary transfer roller , 23 Density detection sensor, 24 drive roller, 25 driven roller, 26 cleaning blade, 30 paper feeding unit, 31 transport path, 32 paper ejection roller, 33 paper ejection tray, 35 operation panel, 40 fixing unit, 45 control unit.

Claims (6)

The intermediate transfer member used in an image forming apparatus that primarily transfers a toner image carried on an electrostatic latent image carrier to an intermediate transfer member and then secondarily transfers the toner image from the intermediate transfer member to a recording material. And
The intermediate transfer member has an endless belt-like shape, and includes at least a resin base layer and a surface layer,
The surface layer is made of a cured (meth) acrylic resin,
The cured (meth) acrylic resin includes at least a structural unit derived from a polyfunctional (meth) acrylic acid derivative and a structural unit derived from a (meth) acrylic acid derivative having an actinic ray decomposable structure. . The intermediate transfer member according to claim 1, wherein the (meth) acrylic acid derivative having an actinic ray-decomposable structure contains at least one amide methylol structure represented by —CO—NH—CH ₂ —O— in the molecule. The intermediate transfer member according to claim 2, wherein the (meth) acrylic acid derivative having an actinic ray-decomposable structure is represented by the following structural formula (1).

(Wherein R1 represents a hydrogen atom or a methyl group, R2 represents a hydrogen atom; an alkyl group; an alkyl group having an aromatic ring; an alkyl having an aromatic ring having any one or more of a hydroxyl group, a carboxy group and an alkyl group. A group; a polyalkylene glycol group; a polyalkylene glycol group having an aromatic ring; and an aryl group.)   The intermediate transfer body according to claim 1, wherein the cured (meth) acrylic resin is cured by irradiating with actinic rays.   The intermediate transfer member according to claim 1, wherein the resin base material layer is made of polyphenylene sulfide.   An image forming apparatus comprising the intermediate transfer member according to claim 1.

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