JP2006263586A - Production method of conductive belt, conductive belt painting apparatus, and conductive belt formed by this production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method of a conductive belt capable of forming the surface layer of the conductive belt by spraying a paint without a solvent or with a small amount of the solvent in order to eliminate or simplify a drying process, and to provide a conductive belt painting apparatus, and the conductive belt formed by the production method. <P>SOLUTION: The production method of the conductive belt comprises warming the paint such that the viscosity of the paint is 1 to 1,000 mPa×S prior to spraying of the paint. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a conductive belt used in an image forming apparatus such as an electrophotographic apparatus such as a copying machine or a printer, or an electrostatic recording apparatus, and a conductive belt formed by this method. The present invention relates to a material that can be applied to form a surface layer efficiently and with high accuracy.

  Conventionally, in an electrostatic recording process in a copying machine, a printer, etc., first, the surface of a photosensitive member (latent image holding member) is uniformly charged, and an image is projected onto the photosensitive member from an optical system and exposed to light. An electrostatic latent image is formed by erasing the charged portion, and then toner is supplied to the electrostatic latent image to form a toner image by electrostatic adhesion of the toner, which is formed on paper, OHP, photographic paper For example, a method of printing by transferring to a recording medium such as the above is employed.

  In this case, color printers and color copiers basically perform printing according to the above process, but in the case of color printing, the color tone is reproduced using toners of four colors, magenta, yellow, cyan, and black. Therefore, a process for obtaining a necessary color tone by superimposing these toners at a predetermined ratio is required, and several methods have been proposed for performing this process.

  These methods can be roughly classified according to the stage at which the toner is overlapped. First, the first method is to superimpose different color toners on the photosensitive drum. In the same manner as in the case where the toner is supplied, when the electrostatic latent image is visualized by supplying the toner onto the photosensitive member, development is performed by sequentially superposing the toners of the four colors of magenta, yellow, cyan, and black. This is called a multiple development method. According to this method, it is possible to configure the apparatus relatively compactly, but there is a problem in that it is very difficult to control gradation and high image quality cannot be obtained.

  In the second method, different color toners are superimposed on a recording medium. As one of these methods, four photosensitive drums are provided, and the latent image on each drum is developed with magenta, yellow, cyan, and black toners, so that a magenta toner image, a yellow toner image, and a cyan toner are developed. By forming four toner images, that is, an image and a black toner image, arranging the photosensitive drums on which the toner images are formed in a line, sequentially transferring the toner images onto a recording medium such as paper, and superimposing the toner images on the recording medium. There is a direct tandem method for reproducing color images. Although this method can obtain a good image, the four photosensitive drums, the charging mechanism and the developing mechanism provided for each photosensitive drum are arranged in a line, and the apparatus becomes large and expensive. It becomes.

  FIG. 1 shows a configuration example of a printing unit of a direct tandem image forming apparatus. Four printing units, each composed of a photosensitive drum 61, a charging roll 62, a developing roll 63, a developing blade 64, a toner supply roll 65, and a cleaning blade 66, corresponding to yellow Y, magenta M, cyan C, and black B toners. The toner images are sequentially transferred onto a sheet that is arranged and circulated by the driving roller 68 and conveyed by the transfer conveying belt 60 to form a color image. Charging and discharging of the transfer / conveying belt are performed by a charging roll 67a and a discharging roll 67b, respectively. Further, a suction roller (not shown) is used for charging the paper for sucking the paper onto the belt. Owing to these measures, generation of ozone can be suppressed. The suction roller places the paper on the transfer conveyance belt from the conveyance path and performs electrostatic adsorption on the transfer conveyance belt. Further, the sheet separation after the transfer can be performed only by the curvature separation by lowering the transfer voltage to weaken the adsorption force between the sheet and the transfer conveyance belt.

  The material of the transfer conveyance belt 60 includes a resistor and a dielectric, and each has advantages and disadvantages. Since the resistance belt has a short charge holding time, when it is used for direct tandem transfer, there is little charge injection during transfer, and the voltage rise is relatively small even during continuous transfer of four colors. In addition, when it is repeatedly used for the transfer of the next sheet, the electric charge is released, and no electrical reset is required. However, since the resistance value changes due to environmental fluctuations, there are disadvantages such as affecting transfer efficiency and being easily influenced by the thickness and width of the paper.

  On the other hand, in the case of a dielectric belt, there is no spontaneous release of injected charge, and both charge injection and discharge must be electrically controlled. However, since the charge is stably held, the sheet can be adsorbed reliably and can be conveyed with high accuracy. Since the dielectric constant is less dependent on temperature and humidity, the transfer process is relatively stable to the environment. The drawback is that the transfer voltage increases because charges are accumulated on the belt each time the transfer is repeated.

  Of the second method, as a method different from the direct tandem method, a recording medium such as paper is wound around a transfer drum and rotated four times, and magenta, yellow, cyan, and black are sequentially recorded on each photosensitive drum. There is also a transfer drum system in which a color image is reproduced by transferring to a medium. According to this method, a relatively high image quality can be obtained. However, when the recording medium is a cardboard such as a postcard, it is difficult to wind the recording medium around the transfer drum, and the type of the recording medium is limited. There is.

  As a third method, there has been proposed an intermediate transfer method in which toner of each color on a photosensitive drum is superimposed on an intermediate transfer member, and the superimposed toner image is transferred to a recording medium as it is. With respect to the system, the direct tandem system, and the transfer drum system, a good image quality can be obtained, and the type of recording medium is not particularly limited.

  In other words, this intermediate transfer system is provided with an intermediate transfer member consisting of a drum and a belt that temporarily transfers and holds the toner image on the photosensitive member, and a magenta toner image, a yellow toner image, a cyan toner image, and a black toner on the photosensitive drum. By sequentially transferring the toner images on the intermediate transfer member, a color image is formed on the intermediate transfer member, and the color image is transferred onto a recording medium such as paper. Therefore, since the gradation is adjusted by superimposing the four color toner images, it is possible to obtain high image quality, and there is no need to wrap the recording medium around the drum, so the type of recording medium is limited. It is nothing.

  As a representative example of the third method, the intermediate transfer method, an intermediate transfer belt method in which one photosensitive drum and one intermediate transfer belt are combined, a plurality of photosensitive drums arranged in tandem, and one intermediate transfer belt There is a tandem intermediate transfer belt system in which these are combined, and these will be described below.

  FIG. 2 is a diagram showing a configuration of an intermediate transfer belt system, in which 71 is a photosensitive drum photoreceptor, which rotates in the direction of the arrow in the figure. The photosensitive drum 71 is charged by the primary charger 72, and then the charged portion of the exposed portion is erased by the image exposure 73, and an electrostatic latent image corresponding to the first color component is formed on the photosensitive drum 61. The electrostatic latent image is developed with the first color magenta toner M by the developing device 75 a, and the first color magenta toner image is formed on the photosensitive drum 71. Next, the toner image is circulated and driven by the driving roller 76 and transferred to the intermediate transfer belt 70 that rotates while rotating in contact with the photosensitive drum 71. In this case, transfer from the photoreceptor 61 to the intermediate transfer belt 70 is performed by a primary transfer bias applied from the power source 77 to the intermediate transfer belt 70 at the nip portion between the photosensitive drum 71 and the intermediate transfer belt 70. After the first color magenta toner image is transferred to the intermediate transfer belt 70, the surface of the photosensitive drum 71 is cleaned by the cleaning device 74, and the development transfer operation for the first rotation of the photosensitive drum 71 is completed. Thereafter, the photosensitive drum 71 rotates three times, and the second color cyan toner image, the third color yellow toner image, and the fourth color black toner image are sequentially used by the developing devices 75a to 75d for each turn. The toner image is formed on the upper surface of the intermediate transfer belt 70 and is superimposed and transferred to the intermediate transfer belt 70 for each turn. A composite color toner image corresponding to the target color image is formed on the intermediate transfer belt 70. In the apparatus of FIG. 2, the developing devices 75 a to 75 d are sequentially replaced with each rotation of the photosensitive drum 71 so that development with magenta toner M, cyan toner C, yellow toner Y, and black toner B is sequentially performed. It has become.

  Next, the transfer roller 81 comes into contact with the intermediate transfer belt 70 on which the composite color toner image is formed, and a recording medium 83 such as paper is fed from the paper feed cassette 82 to the nip portion. At the same time, the secondary transfer bias is applied from the power source 84 to the transfer roller 81, and the composite color toner image is transferred from the intermediate transfer belt 70 onto the recording medium 83 and is heat-fixed to form the final image. After the composite color toner image is transferred to the recording medium 83, the transfer residual toner on the surface of the intermediate transfer belt 70 is removed by the cleaning device 78, returns to the initial state, and prepares for the next image formation.

  FIG. 3 is a diagram showing a configuration example of the tandem intermediate transfer belt system. The first developing device 94a develops the electrostatic latent image on the photosensitive drum 92a with yellow, and the electrostatic latent image on the photosensitive drum 92b is magenta. A second developing device 94b for developing the electrostatic latent image on the photosensitive drum 92c, a third developing device 94c for developing the electrostatic latent image on the photosensitive drum 92c with cyan, and a fourth developing device 94d for developing the electrostatic latent image on the photosensitive drum 92d with black. Are arranged along the intermediate transfer belt 90, and the intermediate transfer belt 90 is circulated and driven in the direction of the arrow in the figure to form four color toner images formed on the photosensitive drums 92a to 92d of the developing devices 94a to 94d. Are sequentially transferred onto the intermediate transfer belt 90 to form a color toner image on the intermediate transfer belt 90, and the toner image is transferred onto a recording medium 93 such as paper to be preliminarily transferred. It is intended to theft.

  In the figure, 95 is a driving roller or tension roller for circulatingly driving the intermediate transfer belt 90, 96 is a recording medium feeding roller, 97 is a recording medium feeding device, 98 is an image heated on the storage medium, etc. It is a fixing device that fixes by means of In the figure, reference numeral 99 denotes a power supply device (voltage applying means) for applying a voltage to the intermediate transfer belt 90. The power supply device 99 transfers toner images from the photosensitive drums 92a to 92d to the intermediate transfer belt 90. The polarity of the applied voltage can be reversed when the toner image is transferred from the intermediate transfer belt 90 to the recording medium 93.

  The above-described conductive belt functioning as the transfer conveyance belt 60 and the intermediate transfer belts 70 and 90 has a single-layer or two-layer structure, and the conductive belt has a two-layer or more structure. The outer surface layer and intermediate layer are formed by spray coating or dip coating on a band-shaped base portion formed using a mold or the like.

Among these methods, the spray coating method forms a surface layer by moving the conductive belt in the length direction while displacing the spray gun in the width direction of the conductive belt and spraying the paint on the outer surface of the base portion. Compared to other methods, it is possible to form a thin film layer with high accuracy and does not require a tank or paint tank for storing a large amount of paint, which necessitates production of large lots. It has the feature that it is suitable for the production form of small quantities of other varieties. (For example, see Patent Document 1)
JP 2003-93699 A

  However, when forming the surface layer of the conductive belt using this method, it is necessary to lower the viscosity of the coating material in order to atomize the coating material. In order to increase the viscosity of the surface layer forming material, the amount of the solvent is increased and adjusted. On the other hand, a paint diluted with a solvent in this manner requires a drying process for vaporizing the solvent after the coating, and a drying line for this purpose, a space for installing this line, and further for drying. A heat source is required. In particular, when a paint diluted with a large amount of solvent is used, there is a problem that the cost and space for that purpose are enormous. Furthermore, the lengthening of the drying process has a problem that the thickness of the surface layer becomes nonuniform due to the flow of the coating film during drying.

  The present invention has been made in view of such problems, and in order to eliminate or simplify the drying process, the surface layer of the conductive belt is formed by spraying a solvent-free or small amount of solvent paint. It is an object of the present invention to provide a conductive belt manufacturing method, a conductive belt coating apparatus, and a conductive belt formed by this manufacturing method.

  <1> is a method of manufacturing a conductive belt in which a surface layer or an intermediate layer is formed by spraying a coating material on the peripheral surface of an endless belt-like base portion, and the viscosity of the coating material is 1 to 1000 mPa · The conductive belt manufacturing method is characterized in that the temperature of the coating is raised so as to be S.

  <2> is a method for producing a conductive belt using <1> that contains an ultraviolet curable resin or an electron beam curable resin as a coating material.

  <3> is the length of the base part with respect to the spray gun for spraying paint and at least one of the base part with respect to the other in the state where the base part is rotated around the shaft part in <1> or <2> This is a method for producing a conductive belt in which paint is sprayed while being relatively displaced in the vertical direction.

<4> is a conductive belt coating apparatus used in a method of manufacturing a conductive belt in which a surface layer or an intermediate layer is formed by spraying a coating on the peripheral surface of an endless belt-shaped base portion,
A spray gun for spraying the paint, a paint tank for accommodating the paint, and a tank heating device for raising the temperature of the paint contained in the paint tank, including a paint supply pipe for transporting the paint from the paint tank to the spray gun; The conductive belt coating apparatus is provided with at least one of a pipe heating apparatus for heating the paint passing through the paint supply pipe.

  <5> is a conductive belt coating apparatus provided with a paint return pipe that bypasses the spray gun and returns the paint supplied from the paint tank through the paint supply pipe to the paint tank in <4>.

  <6> has an endless belt-like base portion and a surface layer or an intermediate layer covering the peripheral surface of the base portion, and the surface layer or the intermediate layer is any one of <1> to <3> This is a conductive belt formed by the method for manufacturing a conductive belt.

  According to the invention of <1>, since the temperature of the paint is raised so that the viscosity of the paint becomes 1 to 1000 mPa · s prior to spraying the paint, the paint can be used even with a solvent-free or small amount of solvent. Can be atomized in good condition, and as a result, the drying line can be simplified or eliminated, saving the cost and space required for this, and during the drying process The problem of non-uniform thickness of the layer due to the flow of the paint in can be solved.

  When the viscosity of the paint is less than 1 mPa · S, the paint particles in the paint atomization become too fine and the coating efficiency deteriorates. On the other hand, when the viscosity exceeds 1000 mPa · S, the paint becomes difficult to atomize. The uniformity of the film is deteriorated.

  According to the invention of <2>, since a paint containing an ultraviolet curable resin or an electron beam curable resin is used as the paint, the paint can be cured instantaneously to eliminate the flow of the paint after painting, and the coating thickness Can be prevented from changing.

  According to the invention of <3>, at least one of the spray gun for spraying the paint and the base part with the base part running while applying tension in the length direction thereof, the base part width with respect to the other Since the paint is sprayed while being relatively displaced in the direction, it is possible to continuously form the surface layer in a spiral shape along the width direction of the conductive belt, and waste the paint In addition, a coating film having a smooth and uniform thickness can be formed.

  According to the invention <4>, since one or both of the tank heating device and the pipeline heating device are provided, the temperature of the paint can be increased efficiently.

  According to the invention <5>, since the paint return pipe for returning the paint supplied from the paint tank via the paint supply pipe to the paint tank by bypassing the spray gun is provided, the paint is not used. However, the temperature of the paint in the paint tank and the paint supply piping path can be raised, and the paint can be in a good atomized state immediately after the start of spraying.

  According to the invention of <6>, it has an endless belt-like base portion and a surface layer or intermediate layer covering the peripheral surface of the base portion, and this surface layer or intermediate layer is formed by the above-described method. Therefore, as described above, it is possible to reduce the cost and space by simplifying the drying process, and at the same time, prevent the film thickness change in the drying process and form a highly uniform surface layer. Therefore, it is possible to contribute to high image quality of the image forming apparatus.

  The embodiment of the present invention will be described in more detail. FIG. 4 is a view showing a conductive belt according to the present invention, FIG. 4 (a) is a perspective view, and FIG. 4 (b) is a cross-sectional view corresponding to the arrow b1-b1 in FIG. 4 (a). In FIG. 4A, W represents the width direction of the conductive belt 1, and L represents the length direction of the conductive belt 1. The conductive belt 1 includes an endless belt-like base portion 3 and a surface layer 4 that covers the outer peripheral surface in the thickness direction of the base portion 3. Although the illustrated conductive belt has a two-layer structure, the present invention is also applicable to the case where an intermediate layer other than the surface layer is formed by spray coating even if it has a structure of three or more layers. be able to.

  Here, the thickness of the base portion 3 is preferably 30 to 200 μm, and the thickness of the surface layer 4 is preferably 1 to 200 μm.

  As the base portion 3, a resin material added with a conductive agent to provide conductivity is used. The resin material used for the base portion is not particularly limited, and commercially available materials may be used. For example, polyamide 12, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-ethylenepropylene-styrene copolymer, polyamide 6/12 , Polyamide 6, polyamide 66, polyacetal, polymethyl methacrylate, poly vinylidene fluoride, polyvinyl fluoride, poly hexafluoroethylene propylene, poly trifluoride ethylene, ethylene-tetrafluoroethylene copolymer, polyacrylonitrile, polyarylate, poly Butylene terephthalate, polycarbonate, polyethersulfone, polyethylene, polyethylene terephthalate, polystyrene, polyphenylene oxide, polysulfone, polyarylate, polypropylene, heat Plastic polyester (PET, PBT, etc.) Polyethylene naphthalate, polybutylene naphthalate, polyphenylene sulfide, polysulfone, polyether ketone, and liquid crystal polyester can be used to support high mechanical performance. Among them, polyamide 12 And acrylonitrile-butadiene-styrene copolymer is preferred, and polyamide 12 is particularly preferred.

  Various conductive agents can be used as the conductive agent added to the base portion 3. The carbon-based conductive agent can obtain high conductivity with a small amount of addition, and as the carbon-based conductive agent, ketjen black or acetylene black is preferably used, but SAF, ISAF, HAF, FEF, GPF, SRF, Carbon black for rubber such as FT and MT, carbon black for ink such as oxidized carbon black, pyrolytic carbon black, graphite and the like can also be used.

  Examples of ionic conductive agents include dodecyltrimethylammonium such as tetraethylammonium, tetrabutylammonium and lauryltrimethylammonium, octadecyltrimethylammonium such as hexadecyltrimethylammonium and stearyltrimethylammonium, ammonium such as benzyltrimethylammonium and modified aliphatic dimethylethylammonium. Organic ionic conducting agents such as perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, sulfate, alkylsulfate, carboxylate, sulfonate; Perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, trifluoromethyl sulfate, sulfate of alkali metal or alkaline earth metal such as sodium, calcium, magnesium It can be exemplified inorganic ion conductive agent such as phosphate salts.

  Electronic conductive agents other than carbon-based ones can also be used. Examples of such electronic conductive agents include fine particles of metal oxides such as ITO, tin oxide, titanium oxide, and zinc oxide; nickel, copper, silver, germanium, and the like. Examples thereof include metal oxides; conductive titanium oxide whiskers, transparent whiskers such as conductive barium titanate whiskers; and the like.

  Two or more kinds of conductive agents may be used as a mixture, and in this case, the conductivity can be stably exhibited even when the applied voltage varies or the environment changes. As an example of mixing, a carbon-based conductive agent mixed with an electronic conductive agent other than a carbon-based conductive agent or an ionic conductive agent can be used.

  Further, the surface layer 4 is made of, for example, nylon, polyester, urethane-modified acrylic resin, phenol resin, acrylic resin, epoxy resin, urethane resin, urea resin, fluorine resin, or other suitable resin depending on the purpose. Although it can be formed, a fluororesin is preferably used from the viewpoint of surface smoothness and low adhesion to a photoreceptor or the like.

  Examples of fluororesins include polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-ethylene copolymer, polychlorotriethylene. Fluoroethylene, chlorotrifluoroethylene-ethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, chlorotrifluoroethylene-vinyl ether copolymer, tetrafluoroethylene-vinylidene fluoride copolymer, chlorotrifluoroethylene- And vinyl ester copolymers, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymers, etc. Dispersion type water-based fluororesin is preferably used dispersed in, more preferably dispersion type water-based fluorine resin dispersed with fine particles of polytetrafluoroethylene in water is used. The particle size of the fluororesin fine particles used is not particularly limited, but is preferably 5 μm or less, and particularly preferably 0.05 to 1 μm.

  Moreover, the surface layer 4 can also be formed by mixing other resins with these fluororesins within a range not impairing the effect of the fluororesin. In this case, other resins mixed with the fluororesin include polyvinyl acetal resin, urethane resin, polyester resin, acrylic resin, nylon resin, epoxy resin, vinylidene chloride copolymer, acrylic-urethane copolymer, and the like. The surface layer 4 can be formed by mixing one or more of these with the fluororesin. Among these resins, a polyvinyl acetal resin, a urethane resin, a polyester resin, and a vinylidene chloride copolymer are preferable from the viewpoints of forming a coating film of a fluororesin and uniformity of resistance, and a polyvinyl acetal resin is particularly preferable.

  In the surface layer 4, when it is desired to ensure the smoothness, a water-based resin is preferably used. The water-based resin may be any type such as a water-soluble type, an emulsion type, and a suspension type as long as the solvent is water, but in particular, an acrylic hot water-soluble resin having active hydrogen such as a carboxyl group, a hydroxyl group, and an amino group. Is preferred.

  Furthermore, an appropriate amount of an appropriate additive such as a thickener, thixotropic agent, and structural viscosity agent can be added to the surface layer 4 as necessary. In this case, the additive is inorganic. Either an organic type or an organic type may be used.

  Moreover, a crosslinkable resin is also preferably used as the resin constituting the surface layer 4. The crosslinkable resin refers to a resin that self-crosslinks with heat, catalyst, air (oxygen), moisture (water), electron beam, or the like, or a resin that crosslinks by reaction with a crosslinking agent or other crosslinkable resin. Examples of such crosslinkable resins include hydroxyl groups, carboxyl groups, acid anhydride groups, amino groups, imino groups, isocyanate groups, methylol groups, alkoxymethyl groups, aldehyde groups, mercapto groups, epoxy groups, unsaturated groups, etc. Fluorine resin, polyamide resin, acrylic urethane resin, alkyd resin, phenol resin, melamine resin, silicone resin, urethane resin, polyester resin, polyvinyl acetal resin, epoxy resin, polyether resin, amino resin, acrylic resin, Mention may be made of urea resins and the like and mixtures thereof. Of these, fluorine resins, polyamide resins, acrylic urethane resins, alkyd resins, phenol resins, melamine resins, silicone resins, urethane resins, polyester resins, polyvinyl acetal resins, epoxy resins, and mixtures thereof are preferred, and alkyd resins are particularly preferred. , Phenol resin, melamine resin and mixtures thereof are preferable from the viewpoint of charging ability of the developer, non-contamination to the developer, reduction of frictional force with other members, non-contamination to the image forming body, and the like.

  For the crosslinkable resin, a catalyst and a crosslinking agent are used as necessary. Examples of the catalyst include radical catalysts such as peroxides and azo compounds, acid catalysts, basic catalysts, and the like. In addition, the crosslinking agent has one molecule of reactive group such as hydroxyl group, carboxyl group, acid anhydride group, amino group, imino group, isocyanate group, methylol group, alkoxymethyl group, aldehyde group, mercapto group, epoxy group, and unsaturated group. Examples thereof include compounds having two or more compounds, for example, polyol compounds, polyisocyanate compounds, polyaldehyde compounds, polyamine compounds, polyepoxy compounds and the like. This crosslinkable resin can be further charged with a charge control agent, lubricant, conductive agent, other resin, etc. as desired for the purpose of further improving the charging ability to the developer, reducing the frictional force with other members, and imparting conductivity. Various additives can be contained.

  Among the above resins, those containing an electron beam curable resin or an ultraviolet curable resin are preferable in that a drying step is not required after the surface layer 4 is applied. These resins are irradiated with an electron beam, Alternatively, it can be cured by irradiating with ultraviolet rays in the presence of an ultraviolet polymerization initiator. Furthermore, when a paint made of these resins is used, the surface layer can be instantly solidified by irradiating it with ultraviolet rays or electron beams after completion of the coating, and left in the same posture under fluidized conditions. In contrast to this, the change in the thickness of the surface layer can be suppressed.

  As electron beam curable resin or ultraviolet curable resin, polyester resin, polyether resin, fluorine resin, epoxy resin, amino resin, polyamide resin, acrylic resin, acrylic urethane resin, urethane resin, alkyd resin, phenol resin, melamine resin, A urea resin, a silicone resin, a polyvinyl butyral resin, etc. are mentioned, These 1 type (s) or 2 or more types can be mixed and used.

  Furthermore, modified resins in which specific functional groups are introduced into these resins can also be used. Further, in order to improve the mechanical strength and environmental resistance characteristics of the resin layer 4, it is preferable to introduce one having a crosslinked structure.

  Among the above-mentioned electron beam curable resins or ultraviolet curable resins, a composition formed from a (meth) acrylate ultraviolet curable resin containing a (meth) acrylate oligomer is particularly suitable.

  Examples of such (meth) acrylate oligomers include urethane (meth) acrylate oligomers, epoxy (meth) acrylate oligomers, ether (meth) acrylate oligomers, ester (meth) acrylate oligomers, and polycarbonate (meth). Examples include acrylate oligomers, and fluorine-based and silicone-based (meth) acrylic oligomers.

  The (meth) acrylate oligomer is composed of a compound such as polyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, bisphenol A type epoxy resin, phenol novolac type epoxy resin, adduct of polyhydric alcohol and ε-caprolactone, It can be synthesized by reaction with (meth) acrylic acid or by urethanizing a polyisocyanate compound and a (meth) acrylate compound having a hydroxyl group.

  The urethane-based (meth) acrylate oligomer can be obtained by urethanizing a polyol, an isocyanate compound and a (meth) acrylate compound having a hydroxyl group.

  Examples of the epoxy-based (meth) acrylate oligomer may be any reaction product of a compound having a glycidyl group and (meth) acrylic acid. Among them, a benzene ring, a naphthalene ring, a spiro ring, a dicyclopentadiene, A reaction product of a compound having a cyclic structure such as tricyclodecane and having a glycidyl group and (meth) acrylic acid is preferred.

  Furthermore, ether-based (meth) acrylate oligomers, ester-based (meth) acrylate oligomers and polycarbonate-based (meth) acrylate oligomers react with polyols (polyether polyols, polyester polyols and polycarbonate polyols) and (meth) acrylic acid, respectively. Can be obtained by:

  A reactive diluent having a polymerizable double bond is blended in the electron beam curable resin composition or the ultraviolet curable resin composition as necessary to adjust the viscosity. As such a reactive diluent, for example, a monofunctional, difunctional or polyfunctional polymerizable compound having a structure in which (meth) acrylic acid is bonded to a compound containing an amino acid or a hydroxyl group by an esterification reaction or an amidation reaction Etc. can be used. These diluents are usually preferably used in an amount of 10 to 200 parts by weight per 100 parts by weight of the (meth) acrylate oligomer.

  The resin constituting the surface layer 4 is mixed with a conductive agent for the purpose of controlling its conductivity. As the conductive material, the same conductive agent contained in the base portion 3 as described above is used. be able to.

  Next, a method for forming the surface layer 4 as described above by applying a paint to the outside of the base portion 3 of the conductive belt 1 will be described with reference to FIG. FIG. 5A is a plan view showing a coating apparatus that forms a surface layer 4 by spraying paint, and FIG. 5B is a cross section showing a cross section corresponding to the b2-b2 arrow in FIG. 5A. The coating apparatus 10 includes a belt traveling device 5 that travels an endless conductive belt 1 in its length direction, a spray gun 11 that sprays paint on the conductive belt 1, and traveling of the conductive belt 1. The gun traverse device 20 that displaces the spray gun 11 in the width direction of the conductive belt 1 in synchronization with the paint gun, the paint supply device 30 that supplies the spray gun 11 with paint, and the common base 25 on which these devices are mounted. .

  The belt traveling device 5 includes two rollers, a driving roller 21 and a driven roller 22 that stretch the base portion 3 of the conductive belt 1, a driving side support member 23 that pivotally supports both ends of the driving roller 21, and the driving roller 21. A motor 24 that is rotationally driven and a driven side support member 27 that pivotally supports both ends of the driven roller 22 are configured. The motor 24 may be one that rotates at a predetermined constant speed, such as a servo motor or a pulse motor. The driven side support member 27 is supported by a linear guide 28 so as to be displaceable in a direction parallel to the running direction of the conductive belt 1, and a substantially constant tension is applied by a tension spring 29 attached to the common base 25. It is configured to act on the base portion 3 of the conductive belt 1.

  The driving roller 21 and the driven roller 22 are configured to be detachable with respect to one of the driving side support member 23 and the driven side support member 27 by means (not shown), respectively, and are electrically conductive with a surface layer formed thereon. The belt 1 can be taken out from the belt traveling device 5, and the conductive belt 1 having only the base portion 3 without the surface layer 4 can be attached to the belt traveling device 5.

  As shown in the figure, the gun traversing device 20 includes a mounting block 15 to which the spray gun 11 is attached, a servomotor 14 with a speed reducer that traverses the block 15 via the ball screw 12, and a linear that guides the linear travel of the block 15. A guide 13 can be provided.

  FIG. 6 is a piping system diagram showing a configuration example of the paint supply device 30. The paint supply device 30 is a paint tank 31 that contains paint, and a paint pump that sucks paint from the paint tank 31 and pumps it to the spray gun 11. 32 and a paint supply pipe 34 for guiding the paint from the paint tank 31 to the spray gun 11, and in the spray gun 11, an atomizing air supply pipe 42 for atomizing the paint is provided.

  A paint pressure adjusting valve 45 for adjusting the pressure of the paint is provided in the middle of the paint supply pipe 34, and an air pressure adjusting valve 43 for adjusting the pressure of the atomizing air is provided in the middle of the atomizing air pipe 42. For example, the spray conditions can be changed manually or automatically according to the type of the conductive belt 1.

  The present invention is characterized in that the temperature of the paint is raised prior to spraying the paint from the spray gun 11, so that the coating apparatus 10 raises the paint in the paint tank 31 to a predetermined temperature. When the tank heating device 33 for maintaining the temperature after heating and the pipe heating device 36 for heating the paint passing through the paint supply pipe 34 to a predetermined temperature are provided, and the paint is not sprayed from the spray gun 11 However, a paint return pipe 35 for circulating the paint is provided so that the paint does not stagnate in the paint supply pipe 34 and is cooled.

  In accordance with this, a flow path switching valve 41 is provided, and when spraying paint from the spray gun 11 onto the conductive belt base 3, the outlet to the spray gun 11 side is opened, and when spraying is not performed, paint is applied. The outlet to the return pipe 35 is opened so that the paint can be circulated. Furthermore, preferably, the paint tank 31 is provided with a stirrer 48 for making the temperature of the paint more uniform.

  Since the spray gun 11 sprays the paint while being displaced, the paint supply pipe 34 and the paint return pipe 35 are connected to the spray gun 11 through flexible hoses 37a and 37b.

  Here, the tank heating device 33 can be constituted by, for example, a temperature control jacket that is attached so as to go around the inside or the outside of the tank body, and this temperature control jacket is formed by passing steam or hot water inside. Alternatively, this can be used as the heat source by using an electric heater. Further, the pipe heating device 36 can also be constituted by a similar temperature control jacket surrounding the outside of the paint supply pipe 34 in the radial direction. Further, it is preferable that the paint supply pipe 34 and the paint return pipe 3 are kept in a wide range as much as possible in order to further stabilize the paint temperature and save energy.

  The temperature of the paint immediately before atomization when the temperature is raised using such a heating device is preferably 30 to 100 ° C, more preferably 40 to 70 ° C. 30 ° C is the minimum temperature necessary to keep the viscosity of the paint low, and if it exceeds 100 ° C, if it exceeds this temperature, the paint components will evaporate or gel and stable coating Because it becomes difficult.

  In the above example, both the tank heating device 33 and the pipe heating device 36 are provided. However, only one of them may be used depending on the type of paint and the coating conditions. Further, in order to improve the coating efficiency, the coating material is sprayed by an electrostatic coating method in which a high voltage is applied between the peripheral surface of the base portion 4 of the conductive belt 1 and the spray gun 11 to assist the electrostatic force. You can also

  The form shown in FIG. 6 is a method of atomizing paint using atomized air, and the spray gun 11 is compatible with the air atomization method. In this case, the paint pressure immediately before atomization is set to 100. It is preferable to set the pressure of atomizing air to 50 to 1000 kPa, and this makes it possible to obtain a good atomized state.

  Also, the paint can be atomized by an airless system that does not rely on atomizing air, and the atomization is achieved by making the paint pressure extremely high and setting the flow rate of the paint at the spray gun nozzle to a predetermined value or higher. FIG. 7 shows a piping system diagram in this case. As can be seen by comparing FIG. 7 with FIG. 6, the configuration of the device in the case of the airless system is different from that shown in FIG. This is only the point of using the spray gun 11A of the type, and therefore the detailed description is omitted. In the case of the airless system, since the paint is atomized by increasing the pressure, the pressure is preferably 0.5 to 10 MPa.

  In order to form the surface layer 4 by coating the base portion 3 of the conductive belt 1 using the coating apparatus 10 configured as described above, the motor 24 is mounted after the base portion 2 is mounted on the belt traveling device 5. Is driven to drive the servomotor 14 with a speed reducer while driving the base body 3 in the direction of arrow A, and the spray gun 11 is moved in the width direction of the conductive belt 1 and in the direction of arrow B. The spray gun 11 is moved by a pitch that is shorter than the width of the base body 3 and narrower than the spread width of the paint while the base body section 3 travels one round. Thereby, the surface layer 4 can be formed with a spirally extending coating as shown in FIG. 5A from one end of the base portion 3 to the other end.

  Thereafter, the conductive belt 1 having the surface layer 4 formed in this manner is taken out from the belt running device 5 and the surface layer 4 is cured in a drying process (not shown) or using an ultraviolet curing device or an electron beam curing device. To complete the production of the conductive belt 1.

  The coating apparatus 1 was used to change the type of paint and the temperature condition of the paint during spraying, and an experiment was conducted to form the surface layer 4 by spraying the paint under the respective conditions. The surface roughness and thickness of the coating film were measured. The results are summarized in Table 1. For paint A and paint B in Table 1, these formulations are shown in Table 2. These coating materials are all ultraviolet curable coating materials. The amount of solvent (*) in Table 2 represents the mass ratio of the solvent with respect to the total amount of the paint in%.

  In addition, for the paint used in the above experiment, the viscosity when the temperature is changed is measured, the temperature dependence curve of the paint viscosity is obtained, the measured paint temperature during spraying, and the temperature dependence curve of the paint viscosity From this, the viscosity of the paint at the time of spraying was estimated, and this is also shown in Table 1 as “viscosity”.

  In Table 1, “Applicability” means “○” when the paint can be sprayed stably, “△” when the paint can be sprayed but unstable, and no atomization of the paint. The possible items are indicated by “x”, and “Pass / Fail Judgment” is “Pass” when the applicability is “O” and the surface roughness Ra of the coating film is 2.0 μm or less. The thing was expressed as "fail".

  “Paint temperature” in Table 1 represents the temperature at the time of spraying at the point detected by the thermocouple by disposing a thermocouple contact in the paint path of the spray gun.

  The measuring instrument for determining the temperature dependence curve was a rheometer manufactured by ThermoHaake (model: ReoStress300 + TC81). In this measurement, the measurement liquid is sandwiched between the cone and the plate, and the viscosity is obtained from the torque acting on the cone when the cone is rotated and reciprocated at a constant frequency. The model number was c20 / 1 (manufactured by the same company, diameter 20 mm, cone cone tilt angle 1 degree with respect to the plate), and the frequency of rotational reciprocation of the cone was 1 Hz.

  The conductive belt used in the trial production was an intermediate transfer belt, and the size was a circumferential length of 800 mm, a belt width of 250 mm, a base portion thickness of 0.2 mm, and a surface layer thickness of 0.01 to 0.02 mm.

  As is clear from Table 1, the conductive belts of the examples have good atomization state, excellent surface properties of the coating film, and the film thickness is more uniform than that of the comparative examples. It can be seen that

  The conductive belt according to the present invention is mounted on an image forming apparatus such as a plain paper copying machine, a plain paper facsimile machine, a laser beam printer, a color laser beam printer, and a toner jet printer as a transfer conveyance belt, an intermediate transfer bell, or the like. Are preferably used.

1 is a schematic side view of an image forming apparatus that forms an image by a tandem method. 1 is a schematic side view of an image forming apparatus that forms an image by an intermediate transfer belt method. 1 is a schematic side view of an image forming apparatus that forms an image by a tandem intermediate transfer belt method. It is sectional drawing which shows the electroconductive belt which concerns on this invention. It is a top view which shows the coating apparatus which forms the surface layer of an electroconductive belt. It is a piping system diagram which shows the coating material supply apparatus of a coating device. It is a piping system diagram which shows the other embodiment of a coating material supply apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive belt 3 Base | substrate part 4 Surface layer 5 Belt travel apparatus 10 Coating apparatus 11, 11A Spray gun 12 Ball screw 13 Linear guide 14 Servomotor with a reduction gear 15 Mounting block 20 Gun traverse apparatus 21 Drive roller 22 Follower roller 23 Drive side Support member 24 Motor 25 Common base 27 Driven support member 28 Linear guide 29 Tension spring 30 Paint supply device 31 Paint tank 32 Paint pump 33 Tank heating device 34 Paint supply piping 35 Paint return piping 36 Pipe heating devices 37a, 36b Flexible hose 41 Flow path switching valve 42 Atomization air supply piping 43 Air pressure adjustment valve 45 Paint pressure adjustment valve 48 Stirrer

Claims (6)

In the method for producing a conductive belt in which a surface layer or an intermediate layer is formed by spraying a paint on the peripheral surface of an endless belt-like base portion,
Prior to spraying the paint, a method for producing a conductive belt, wherein the temperature of the paint is increased so that the viscosity of the paint is 1 to 1000 mPa · s.   The method for producing a conductive belt according to claim 1 or 2, wherein a paint containing an ultraviolet curable resin or an electron beam curable resin is used.   In a state where the base portion is caused to run with tension in the length direction, the paint is sprayed while at least one of the spray gun for spraying the paint and the base portion is relatively displaced with respect to the other in the width direction of the base portion. The manufacturing method of the electroconductive belt of Claim 1 or 2 sprayed. A coating device for a conductive belt used in a method for manufacturing a conductive belt in which a surface layer or an intermediate layer is formed by spraying paint on the peripheral surface of an endless belt-shaped base portion,
A spray gun for spraying the paint, a paint tank for accommodating the paint, and a tank heating device for raising the temperature of the paint contained in the paint tank, including a paint supply pipe for transporting the paint from the paint tank to the spray gun; A conductive belt coating apparatus provided with at least one of a pipe heating apparatus for heating the paint passing through the paint supply pipe.   The conductive belt coating apparatus according to claim 4, further comprising a paint return pipe that bypasses the spray gun and returns the paint supplied from the paint tank through the paint supply pipe to the paint tank.   It has an endless belt-like base part and a surface layer or an intermediate layer covering the peripheral surface of the base part, and this surface layer or the intermediate layer is the conductive belt according to any one of claims 1 to 3. A conductive belt formed by a manufacturing method.

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