JP4605080B2 - Electrophotographic transfer sheet - Google Patents

Description

  The present invention relates to an electrophotographic transfer sheet and the like, and more particularly, to an electrophotographic transfer sheet suitable for color image formation.

  Conventionally, as a color image forming apparatus such as an electrophotographic color copier or a color printer, for example, an electrostatic latent image is formed for each color on a photoconductor, and these electrostatic latent images are converted into Y (yellow), Sequential development with color toners such as M (magenta), C (cyan) and, if necessary, BK (black) to form color toner images for each color, and each time a toner image of each color is formed, it is superimposed on the transfer body. In this method, a color image is formed by transferring, heating, and fixing. As another method, color toner images of different colors are formed on a photoconductor, and the superimposed color toner images are collectively transferred onto a transfer body, which is heated and fixed to form a color image. The method to do is mentioned.

  In such a color image forming apparatus, the color toner having a particle size of several μm to several tens of μm is superimposed on the surface of the transfer sheet, so that the glossiness of the color image tends to be lowered. As a method for improving this, a method of forming a color image using a color toner having a small particle diameter on the surface of a transfer sheet having a transparent resin layer has been reported (see Patent Document 1).

  The present applicant also uses an electrophotographic transfer sheet in which the edge of the transfer sheet provided with an image receiving layer containing a thermoplastic resin is cut so that the angle formed with the back surface of the transfer sheet is 75 ° or less. Thus, a color image forming apparatus that improves the glossiness of a color image and prevents image quality defects has been reported (see Patent Document 2).

JP 05-216322 A Japanese Patent Laid-Open No. 2002-091051

By the way, when a transfer sheet for forming a color image as reported in Patent Document 1 or Patent Document 2 described above is used, there is a problem that the transfer member may be significantly deteriorated with time.
As a result of further investigation by the inventor on such a problem, the transfer sheet reported in Patent Document 1 and the like has a relatively thick structure because a transparent resin layer is laminated on a substrate. It turned out to be one of the causes.
That is, when the toner images that have been multiplex-transferred onto the transfer member are collectively contact-transferred onto such a relatively thick transfer sheet, a discharge occurs due to a gap generated between the transfer member and the transfer sheet in and near the transfer region. It becomes easy. For this reason, it is considered that the discharge product adheres to a transfer member such as a transfer belt and the transfer member is damaged, and as a result, when a color image is continuously printed, the transfer member is significantly deteriorated with time.

The present invention has been made to solve such problems. That is, an object of the present invention is to provide an electrophotographic transfer sheet that can prevent deterioration of a transfer member when a color image is continuously printed.
Another object of the present invention is to provide an image forming apparatus capable of continuously printing color images without causing the transfer member to deteriorate over time.

Thus, according to the present invention, there is provided a transfer sheet for electrophotography on which a toner image is transferred to the surface, the thickness from the front surface to the back surface opposite to the front surface is 100 μm or more, There is provided an electrophotographic transfer sheet characterized by having a shape with an angle (θ) formed by more than 90 degrees.
Here, in the electrophotographic transfer sheet, the shape of all edge portions including the tip portion is such that the angle (θ) formed between the side surface and the back surface of each edge portion exceeds 90 degrees. Is preferred.
Furthermore, the electrophotographic transfer sheet preferably has a wetting tension of 30 mN / m to 40 mN / m, a basis weight of 150 gms or more, and a volume resistance of 12 log Ω · cm or more.
The electrophotographic transfer sheet preferably has a structure having an image receiving layer made of a thermoplastic resin on the surface to which the toner image is transferred.

  Next, according to the present invention, the toner image forming means for forming the toner image, the transfer means for transferring the toner image formed by the toner image forming means onto the sheet, and the sheet at the transfer position of the toner image in the transfer means A sheet conveying means for conveying the sheet, and the sheet conveying means conveys a sheet having a thickness of 100 μm or more and an angle (θ) formed between the side surface and the back surface of the leading end portion exceeding 90 degrees to the transfer position. An image forming apparatus is provided.

Further, according to the present invention, the toner image forming unit for forming the toner image and the transfer unit for transferring the toner image formed by the toner image forming unit onto the sheet are provided. There is provided an image forming apparatus characterized in that a toner band having a predetermined length is formed at a leading end non-image portion and / or a leading end portion of a sheet onto which toner is transferred.
Here, the toner image forming unit preferably forms a toner band having a band width larger than the width of the sheet.
Further, it is preferable that the toner image forming unit forms a toner band composed of a yellow (Y) toner image.

  According to the electrophotographic transfer sheet to which the present invention is applied, deterioration over time of the transfer member is suppressed.

Hereinafter, the best mode (embodiment) for carrying out the present invention will be described. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary. Also, the drawings used are used to describe the present embodiment and do not represent the actual size.
FIG. 1 is a diagram illustrating an overall configuration of an image forming apparatus to which the exemplary embodiment is applied. The image forming apparatus shown in FIG. 1 is a so-called tandem type digital color printer. As shown in FIG. 1, an image forming apparatus includes an image processing system 10 that forms an image corresponding to gradation data of each color, an electrophotographic transfer sheet (hereinafter simply referred to as “transfer sheet”). IPS (Image Processing System), which is an image processing system that is connected to a sheet conveying system 40 that conveys P, for example, a personal computer, an image reading apparatus, etc., and performs predetermined image processing on received image data 50.

  The image processing system 10 includes four image forming units 11Y and 11M of yellow (Y), magenta (M), cyan (C), and black (K), which are arranged in parallel at regular intervals in the horizontal direction. , 11C, 11K, a transfer unit 20 that multiplex-transfers each color toner image formed on the photosensitive drum 12 of the image forming units 11Y, 11M, 11C, 11K onto the intermediate transfer belt 21, and the image forming units 11Y, 11M. , 11C, and 11K are provided with a ROS (Raster Output Scanner) 30 that is an optical system unit that irradiates laser light. In addition, the main body 1 includes a fixing device 29 that fixes the image on the transfer sheet P secondarily transferred by the transfer unit 20 to the transfer sheet P using heat and pressure. Further, the image forming units 11Y, 11M, 11C, and 11K have toner cartridges 19Y, 19M, 19C, and 19K for supplying toner of each color.

  The transfer unit 20 includes a drive roll 22 that drives an intermediate transfer belt 21 that is an intermediate transfer member, a tension roll 23 that applies a constant tension to the intermediate transfer belt 21, and secondary superimposed toner images of each color on a transfer sheet P. A backup roll 24 for transferring and a cleaning device 25 for removing residual toner and the like existing on the intermediate transfer belt 21 are provided. The intermediate transfer belt 21 is wound around the drive roll 22, the tension roll 23, and the backup roll 24 with a constant tension, and is driven to rotate by a dedicated drive motor (not shown) excellent in constant speed. The roll 22 is circulated and driven at a predetermined speed in the direction of the arrow. As the intermediate transfer belt 21, for example, a belt whose resistance is adjusted with a belt material (rubber or resin) that does not cause charge-up is used. The cleaning device 25 includes a cleaning brush 25a and a cleaning blade 25b, and removes residual toner, paper dust, and the like from the surface of the intermediate transfer belt 21 after the toner image transfer process is completed, and prepares for the next image forming process. .

  The ROS 30 includes a polygon mirror 31 that deflects and scans laser light (LB-Y, LB-M, LB-C, LB-K) emitted from the semiconductor laser, in addition to a semiconductor laser and a modulator (not shown). In FIG. 1, the ROS 30 is provided with a rectangular parallelepiped frame 32 that seals each component, and is made of glass through which laser light (LB-Y, LB-M, LB-C, LB-K) passes. A window 33 is provided above the frame 32 to enhance the shielding effect together with the scanning exposure.

  The sheet conveyance system 40 is supplied from a sheet feeding device 41 that stacks and supplies a transfer sheet P on which an image is recorded, a nudger roll 42 that picks up and supplies the transfer sheet P from the sheet feeding device 41, and a nudger roll 42. A feed roll 43 that separates and conveys the transferred sheets P one by one, and a conveyance path 44 that conveys the transfer sheets P separated one by one by the feed roll 43 toward the image transfer unit. The transfer sheet P conveyed through the conveyance path 44 is also brought into contact with the backup roll 24 provided at the secondary transfer position and the registration roll 45 that conveys the transfer sheet P in a timely manner toward the secondary transfer position. A secondary transfer roll 46 for secondary transfer of an image on P is provided. Further, a discharge roll 47 for discharging the transfer sheet P on which the toner image is fixed by the fixing device 29 to the outside of the main body 1 and a discharge tray 48 for stacking the transfer sheet P discharged by the discharge roll 47 are provided. In addition, a double-sided conveyance unit 49 is provided that enables double-sided recording by inverting the transfer sheet P fixed by the fixing device 29.

Next, the image forming units 11Y, 11M, 11C, and 11K in the image process system 10 will be described in detail.
FIG. 2 is a diagram for explaining the configuration of the image forming units 11Y, 11M, 11C, and 11K. Here, a yellow (Y) image forming unit 11Y and a magenta (M) image forming unit 11M are shown. The other image forming units 11C and 11K are configured in substantially the same manner.

  The image forming units 11Y, 11M, 11C, and 11K are charged by a photosensitive drum 12 as an image carrier that carries a toner image, a charger 13 that charges the photosensitive drum 12 using a charging roll 13a, and a charger 13. , A developing device 14 for developing an electrostatic latent image formed on the photosensitive drum 12 by a developing roller 14a by a laser beam (LB-Y, LB-M, LB-C, LB-K) from the ROS 30, an intermediate transfer A primary transfer roll 15 is provided to face the photosensitive drum 12 with the belt 21 interposed therebetween, and transfers the toner image developed on the photosensitive drum 12 onto the intermediate transfer belt 21, and remains on the photosensitive drum 12 after transfer. A cleaning device 16 for removing residual toner is provided.

  In the present embodiment, the photosensitive drum 12, the charger 13, and the cleaning device 16 of the image forming units 11Y, 11M, 11C, and 11K are integrated into a cartridge so that the image forming unit 11Y, 11M, 11C, and 11K can be integrated into a cartridge. Only the cartridge can be removed, and only the cartridge can be attached to the main body 1. Each of these cartridges is mounted with a nonvolatile memory (not shown). In this nonvolatile memory, for example, when the cartridge is mounted in a predetermined image forming unit 11Y, 11M, 11C, or 11K such as the rotational speed of the photosensitive drum 12, the high voltage application time, the number of prints, etc. Each cartridge usage history information is stored. These cartridges can be used by being replaced between the image forming units 11Y, 11M, 11C, and 11K. Since each of the cartridges is equipped with a non-volatile memory, the cartridge itself can store its own usage history information even when the cartridge is used in different units. As a result, for example, the correct lifetime can be determined for each cartridge.

  Next, the operation of the image forming apparatus shown in FIG. 1 will be described. A color material reflected light image of a document read by a document reading device (not shown) and color material image data formed by a personal computer (not shown) are, for example, R (red), G (green), and B (blue). Each 8-bit reflectance data is input to the IPS 50. In the IPS 50, the input reflectance data is subjected to predetermined image processing such as various image editing such as shading correction, position shift correction, lightness / color space conversion, gamma correction, frame deletion, color editing, and moving editing. Is done. The image data that has been subjected to image processing is converted into color material gradation data of four colors of yellow (Y), magenta (M), cyan (C), and black (K), and is output to the ROS 30.

  In the ROS 30, laser light (LB-Y, LB-M, LB-C, LB-K) emitted from a semiconductor laser (not shown) is converted into f-θ in accordance with input color material gradation data. The light is emitted to the polygon mirror 31 through a lens (not shown). In the polygon mirror 31, the incident laser light is modulated in accordance with gradation data of each color, deflected and scanned, and image forming units 11Y, 11M, 11C, and 11K through an imaging lens (not shown) and a plurality of mirrors. The photosensitive drum 12 is irradiated. On the photosensitive drum 12 of the image forming units 11Y, 11M, 11C, and 11K, the charged surface is scanned and exposed to form an electrostatic latent image. The formed electrostatic latent image is developed as a toner image of each color of yellow (Y), magenta (M), cyan (C), and black (K) in each of the image forming units 11Y, 11M, 11C, and 11K. Is done.

  The toner images formed on the photosensitive drums 12 of the image forming units 11Y, 11M, 11C, and 11K are multiple-transferred onto an intermediate transfer belt 21 that is an intermediate transfer member. At this time, the black image forming unit 11 </ b> K that forms a black toner image is provided on the most downstream side in the moving direction of the intermediate transfer belt 21, and the black toner image is finally transferred to the intermediate transfer belt 21. Is done.

  On the other hand, in the sheet conveying system 40, the nudger roll 42 rotates in synchronization with the image formation timing, and a transfer sheet P having a predetermined size is supplied from the paper feeding device 41. The transfer sheets P separated one by one by the feed roll 43 are conveyed to the registration roll 45 through the conveyance path 44 and are temporarily stopped. Thereafter, the registration roll 45 rotates in accordance with the movement timing of the intermediate transfer belt 21 on which the toner image is formed, and the transfer sheet P is conveyed to the secondary transfer position formed by the backup roll 24 and the secondary transfer roll 46. The On the transfer sheet P conveyed from the lower side to the upper side at the secondary transfer position, the toner images in which the four colors are multiplexed are sequentially transferred in the sub-scanning direction using a pressing force and a predetermined electric field. . The transfer sheet P on which the toner images of the respective colors are transferred is subjected to a fixing process by heat and pressure by the fixing device 29 and then discharged to a discharge tray 48 provided on the upper portion of the main body 1 by a discharge roll 47. Instead of being discharged to the discharge tray 48 as it is, the transfer direction can be switched by a switching gate (not shown), and the transfer sheet P fixed by the fixing device 29 can be reversed by the double-side transfer unit 49. After the inverted transfer sheet P is conveyed to the resist roll 45, an image is formed on both sides of the transfer sheet P by forming an image on the other unprinted surface by the same flow as described above. It becomes possible.

Next, the electrophotographic transfer sheet (transfer sheet P) used in the image forming apparatus to which the exemplary embodiment is applied will be described.
FIG. 3 is a diagram for explaining the transfer sheet P. FIG. As shown in FIG. 3A, the transfer sheet P is required to have a thickness of usually 100 μm or more, preferably 150 μm or more. However, the thickness is usually 280 μm or less. Here, the thickness of the transfer sheet P is such that the toner image formed on the intermediate transfer belt 21 (FIG. 1) is transferred, and then the toner image is fixed by the fixing device 29, and the surface opposite to this surface. It is the length to the back side.
The shape of the four edge portions of the transfer sheet P is characterized in that the angle (θ) formed between the side surface of the edge portion and the back surface of the transfer sheet P exceeds 90 degrees. Yes. However, the angle (θ) is usually 150 degrees or less.
As described above, the transfer sheet P is configured such that the four edge portions are all configured so that the angle (θ) exceeds 90 degrees, so that the sheet feeding direction is not limited.

Note that, here, a description will be given of a recording sheet in which the angle (θ) formed by the side surface and the back surface of the four edge portions exceeds 90 degrees, but the present embodiment is applied. The shape of the electrophotographic transfer sheet used in the image forming apparatus is not necessarily limited to the transfer sheet P having the shape as shown in FIG.
That is, the recording paper conveyed to the secondary transfer position (the backup roll 24 and the secondary transfer roll 46 (FIG. 1)) has a thickness of 100 μm or more and is directed at least to the transfer position for transferring the toner image. The tip portion can be used as long as the angle (θ) formed between the side surface and the back surface of the edge portion exceeds 90 degrees.

  Next, FIG. 3B is a cross-sectional view taken along the line A-A ′ in FIG. As shown in FIG. 3B, the transfer sheet P is composed of a base material 61 and an image receiving layer 62 provided on one surface (front surface) of the base material 61. The toner image transferred to the intermediate transfer belt 21 (FIG. 1) is transferred to the image receiving layer 62. Further, as described above, the end edge portion of the transfer sheet P has a shape in which the angle (θ) formed between the side surface of the end edge portion and the back surface of the transfer sheet P exceeds 90 degrees.

  Further, as shown in FIG. 3C, the base 61 of the transfer sheet P includes, for example, a support 611 made of high-quality paper and a coating layer made of polyethylene (PE) provided on both the front and back surfaces of the support 611. 612 and 613 and a back layer 614 provided on the back surface of the transfer sheet P as necessary.

Although the material of the support body 611 which comprises the base material 61 is not specifically limited, For example, paper bases, such as acidic papermaking and neutral papermaking, are mention | raise | lifted. Moreover, a synthetic paper, a nonwoven fabric, a synthetic resin film, etc. can also be used according to a use.
Examples of the material of the coating layers 612 and 613 include polyethylene, polypropylene, polyethylene terephthalate, and polystyrene. The coating layers 612 and 613 are coated on both the front and back surfaces of the support 611 and then smoothed by a surface treatment process or the like.
As the back layer 614, an adhesive containing an inorganic pigment, an organic pigment, or the like is usually used. Examples of the adhesive include polyester resin, polyurethane resin, polyolefin resin, polyamide resin, olefin-maleic anhydride resin, and melamine resin. Further, the back layer 614 is mixed with a release agent, a lubricant, or the like as necessary.

  Examples of the material of the image receiving layer 62 include thermoplastic resins such as polyester resin, styrene-acrylate resin, and styrene-methacrylate resin. In the image receiving layer 62 (transparent resin layer), it is necessary that the toner is sufficiently melted by heating for a short time, and the transparent resin constituting the image receiving layer 62 is also softened and compatible with the toner. For this reason, as a material which comprises the image receiving layer 62, it is preferable to have as a main component the polyester resin which is number average molecular weight (Mn) 5000-20000 and glass transition temperature 30 degreeC-85 degreeC.

Moreover, about each layer which comprises the transfer sheet P, it is preferable that the thickness of the base material 61 is 120 micrometers-250 micrometers. The thickness of the image receiving layer 62 is usually preferably 5 μm to 20 μm.
Moreover, it is preferable that the thickness of the support body 611 which comprises the base material 61 is 100 micrometers-230 micrometers normally, and it is preferable that the thickness of the coating layers 612 and 613 is 10 micrometers-30 micrometers normally.

Furthermore, the transfer sheet P to which this embodiment is applied preferably has a wetting tension in the range of 30 mN / m to 40 mN / m. If the wetting tension is excessively small, the toner image tends not to be transferred onto the transfer sheet P. The basis weight of the total than 150Gms, preferably of 190g ^{/ m 2} ~230g ^/ m 2 is used. Furthermore, as the transfer sheet P, a sheet having a volume resistance of 10 log Ω · cm or more, preferably 12 log Ω · cm or more is used.

The manufacturing method of the transfer sheet P to which the present embodiment is applied is not particularly limited, but, for example, using a slitter or a drum winding sheet cutter to which a predetermined cutting blade is attached, There is a method of inserting a blade from the back surface side of the transfer sheet P toward the oblique outer side so that the angle (θ) formed between the side surface and the back surface of the transfer sheet P is 90 degrees or more.
In this case, it is necessary to make the scanning direction of the cutter the same direction. That is, when cutting the leading edge and the trailing edge of the transfer sheet P, if the reciprocating motion is performed in the scanning direction of the cutter, the cut surface becomes an acute angle and an obtuse angle. It is difficult to cut so that the angle (θ) formed between the side surface of the edge portion and the back surface of the transfer sheet P exceeds 90 degrees.
When roll paper is used as recording paper, a slitter or sheet cutter having a predetermined cutting blade is attached to the sheet conveyance system 40 (FIG. 1), and the leading end of the recording paper in the paper feeding direction is The angle (θ) formed between the side surface and the back surface of the edge portion can be formed in a shape exceeding 90 degrees.

As described above, the transfer sheet P to which the present embodiment is applied is provided with the image receiving layer 62 made of a transparent resin layer on the surface of the substrate 61, so that the full-color toner image is fixed by the fixing device 29. After that, by performing secondary fixing again with a belt-type fixing device (not shown), it is possible to obtain a color image with excellent glossiness.
Here, the belt-type fixing device, for example, rotatably supports the fixing belt by a plurality of rolls including a heating roll, presses the pressure roll to the heating roll via the fixing belt, and pressurizes the fixing belt. The roll pressure contact part is passed through the electrophotographic transfer sheet so that the toner image is positioned on the fixing belt side, and the toner image is heated and pressurized to perform secondary fixing, and the fixing belt is cooled to some extent. The electrophotographic transfer sheet is separated from the fixing belt.

Next, suppression of deterioration over time of the transfer member using the transfer sheet P to which the present embodiment is applied will be described.
FIG. 4 is a diagram illustrating the transfer sheet P and the intermediate transfer belt 21 at the secondary transfer position. As shown in FIG. 4A, intermediate transfer is performed on the surface of the transfer sheet P conveyed to the secondary transfer position formed by the backup roll 24 and the secondary transfer roll 46, using a pressure contact force and a predetermined electric field. The four-color multiplex toner images formed on the belt 21 are sequentially transferred in the sub-scanning direction.
Here, as shown in FIG. 4B, the angle (θ) formed between the side surface of the edge portion of the transfer sheet P and the back surface of the transfer sheet P is set to a shape exceeding 90 degrees, When the intermediate transfer belt 21 that is a transfer member comes into contact with the intermediate transfer belt 21, no gap is generated between the edge portion of the transfer sheet P and the intermediate transfer belt 21, so that the discharge is suppressed. As a result, as shown in FIG. 4 (c), the intermediate transfer belt 21 and the recording time degradation of the intermediate transfer belt 21 to discharge product adhered is considered to cause the discharge generated in the gap between the sheet P _1, It can be greatly suppressed.

Next, in the image forming apparatus to which this exemplary embodiment is applied, a second exemplary embodiment that suppresses deterioration with time of the intermediate transfer belt 21 that is a transfer member will be described.
FIG. 5 is a diagram illustrating the toner band. Figure 5 (a), the toner image formed on the intermediate transfer belt 21, in the case of collectively transferred onto the transfer sheet P ₂ at the secondary transfer position, the transfer sheet P ₂ the tip of the intermediate transfer belt When contacting 21, a toner image (toner band) is usually formed also in a region corresponding to a blank portion (tip non-image portion).
Bandwidth toner band (H) is in a recording paper transfer sheet P ₂ in the sheet width or more to be used, usually, it is preferably about 5mm respectively larger from both ends of the transfer sheet P _2. The length (L) of the toner band is usually 5 mm or less, preferably 3 mm or less. The toner band is preferably a toner image using yellow (Y), which has low human eye recognition ability.

Here, as shown in FIG. 5 (b), by forming a toner image (toner band) in the region corresponding to the margin of the transfer sheet P _2, the leading edge of the transfer sheet P ₂ conveyed to the secondary transfer position Contact with the toner band formed on the intermediate transfer belt 21. Therefore, the angle formed between the side surface and the rear surface of the edge portion of the transfer sheet P ₂ (alpha) is also an acute angle, the discharge between the intermediate transfer belt 21 and the transfer sheet P ₂ is suppressed. As a result, as shown in FIG. 5 (c), the intermediate aging of the transfer belt 21 that discharge products adhered by discharge generated in the gap is considered to be caused between the intermediate transfer belt 21 and the transfer sheet P ₂ is suppressed Is done.

Hereinafter, the present embodiment will be described in more detail based on examples. Note that this embodiment is not limited to the examples.
Example 1
As a transfer sheet, the shape of the four edge portions of a recording paper based on cellulose coated with an image receiving layer containing a polyester resin and a wax has an angle (θ) between the side surface of the edge portion and the back surface of 100 degrees. What was cut as it was was used. The recording paper used has a wetting tension of 35 mN / m, a thickness of 200 μm, a basis weight of 220 gsm, and a volume resistance of 12 log Ω · cm.
As a result of continuous printing using the DCC f450 (DocuCenterColor f450) as a printing device on the transfer sheet prepared in this manner, no discharge products adhered to the transfer member, and a stable and good image was obtained. I was able to confirm that

(Comparative Example 1)
The same operation as in the first embodiment is performed by using the printer cut in such a manner that the angle (θ) formed between the edge side surface and the back surface of the recording paper used in the first embodiment is 80 degrees. Although printing was continuously performed, a phenomenon occurred in which the discharge product adhered to the transfer member and the image was stripped.

(Example 2)
As the recording paper, the shape of the four edge portions of a recording paper based on cellulose coated with an image receiving layer containing polyester resin and wax is set to an angle (θ) between the edge side surface and the back surface of 80 degrees. What was cut as it was was used. The recording paper used has a wetting tension of 35 mN / m, a thickness of 200 μm, a basis weight of 220 gsm, and a volume resistance of 12 log Ω · cm.
The recording paper prepared in this manner was subjected to image processing using a DCC f450 as a printing device, and a toner band was provided at the non-image portion at the leading edge of the image, and continuous printing was performed to check the variation in image quality.
Here, the toner band was formed of yellow (Y) (Cin 60%) toner, the band length was 500 μm, and the band width was increased by +5 mm from both side edges of the transfer sheet.
As a result, it was confirmed that there was no discharge product adhering to the transfer member and a stable and good image was obtained.

(Comparative Example 2)
The recording paper used in Example 2 was printed continuously using DCC f450 as a printing device and without performing image processing in which a toner band for a non-image portion was provided, but the transfer member was about 2 kPV. As a result, the phenomenon that the image was lost on the image surface occurred, and a stable image could not be obtained.

As described above in detail, in the transfer sheet used in this example, the shape of the four edge portions of the paper is such that the angle (θ) formed between the side surface of the edge portion and the back surface exceeds 90 degrees. By cutting, the discharge generated in the gap between the transfer sheet and the transfer member is suppressed.
In addition, by performing image processing in which a toner band is provided in the non-image portion at the leading edge of the image, the discharge generated in the gap between the transfer member and the recording paper is suppressed, and the transfer member that is considered to be caused by the discharge product adhering to the transfer member The deterioration over time can be greatly suppressed.

1 is a diagram illustrating an overall configuration of an image forming apparatus to which the exemplary embodiment is applied. It is a figure for demonstrating the structure of an image forming unit. It is a figure for demonstrating a transfer sheet. FIG. 4 is a diagram illustrating a transfer sheet and an intermediate transfer belt at a secondary transfer position. FIG. 6 is a diagram illustrating a toner band.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main body, 10 ... Image process system, 11Y, 11M, 11C, 11K ... Image forming unit, 12 ... Photoconductor drum, 13 ... Charger, 13a ... Charge roll, 14 ... Developer, 15 ... Primary transfer roll, 16 DESCRIPTION OF SYMBOLS ... Cleaning device, 20 ... Transfer unit, 21 ... Intermediate transfer belt, 40 ... Sheet conveyance system, 50 ... IPS (Image Processing System), 61 ... Base material, 62 ... Image receiving layer

Claims (4)

An electrophotographic transfer sheet on which a toner image is transferred to the surface,
The thickness from the front surface to the back surface opposite to the front surface is 100 μm or more,
An electrophotographic transfer sheet characterized in that the angle (θ) formed between the side surface of the tip and the back surface exceeds 90 degrees.   2. The electrophotographic apparatus according to claim 1, wherein the shape of all edge portions including the tip portion is such that an angle (θ) formed between a side surface of each edge portion and the back surface exceeds 90 degrees. Transfer sheet.   2. The electrophotographic transfer sheet according to claim 1, further comprising a wetting tension of 30 mN / m to 40 mN / m, a basis weight of 150 gms or more, and a volume resistance of 12 log Ω · cm or more.   2. The electrophotographic transfer sheet according to claim 1, further comprising an image receiving layer made of a thermoplastic resin on a surface onto which the toner image is transferred.

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