JP2002091051A - Electrophotographic transfer sheet and color image forming apparatus which uses the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic transfer sheet in which image defects due to squeezing out of a transparent resin layer consisting of thermoplastic resin from the end part of the electrophotographic transfer sheet can be prevented without requiring complicated processes and cost, and to provide a color image forming apparatus which uses the above sheet. SOLUTION: In the electrophotographic transfer sheet having an image accepting layer containing thermoplastic resin as the main component on one surface of a substrate, the cut face on at least one end face is formed to make <=75 deg. angle from the back face of the electrophotographic transfer sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic transfer sheet used in a color image forming apparatus such as a color copying machine or a color printer or a color facsimile to which an electrophotographic method is applied, and a color image using the same. With regard to the forming apparatus, in particular, an image receiving layer made of a thermoplastic resin generated when the electrophotographic transfer sheet is fixed while reducing the level difference of an image transferred on the electrophotographic transfer sheet to improve image quality. The present invention relates to a transfer sheet for electrophotography capable of preventing an edge portion from protruding, and a color image forming apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, a color image forming apparatus such as a color copying machine or a color printer to which the above-mentioned electrophotographic system is applied is provided with only one photosensitive drum, and yellow (Y), A toner image of each color such as magenta (M), cyan (C), and black (BK) is sequentially formed, and yellow (Y), magenta (M), cyan (C), and yellow (Y) are sequentially formed on the photosensitive drum. Black (B
K), etc., are configured to form a color image by transferring a plurality of toner images of each color onto a transfer medium and then heating and fixing these toner images onto the transfer medium. Further, the color image forming apparatus is configured to temporarily transfer toner images of respective colors, such as yellow (Y), magenta (M), cyan (C), and black (BK), which are sequentially formed on a photosensitive drum, to an intermediate transfer member. After the primary transfer on the transfer medium, the toner images of each color transferred on the intermediate transfer body are secondarily transferred collectively onto the transfer medium, and these toner images are heated and transferred onto the transfer medium. In some cases, a color image is formed by fixing.

Further, as the above color image forming apparatus, yellow (Y), magenta (M), cyan (C),
A plurality of image forming units corresponding to each color such as black (BK) are provided, and yellow (Y), magenta (M), cyan (C), and black (BK) are sequentially formed on the photosensitive drum of each image forming unit. ), Etc., the toner image of each color is transferred on the transfer medium in a multiplex manner, or once primary-transferred on the intermediate transfer body, and then the toner images of the respective colors transferred on the intermediate transfer body are multiplexed. Some devices are configured so that a color image is formed by heating and fixing these toner images onto the transfer medium after the secondary transfer on the transfer medium.

A color toner to be transferred and fixed onto the transfer medium is usually formed by dispersing or melting a colorant such as a pigment or a dye in a binder resin. It is set to several tens of μm. Such color toners are transferred in a state where a plurality of layers are superimposed on coated paper such as plain paper or general printing paper, and these color toners are heated and melted to form plain paper or general printing paper. And a color image is formed. At this time, unevenness of, for example, about 10 to 100 μm is formed on the surface of the color image depending on the height of the toner layer, and uneven gloss is generated. As a result, a color image formed on coated paper such as plain paper or general printing paper diffusely reflects incident illumination light, and when observed with the naked eye,
The image looks inferior in gloss.

Therefore, in a method of forming a color image by interposing a transparent resin layer on the surface of a transfer body and fixing a color toner on the transparent resin layer, a color tone is abundant, color reproducibility is excellent, and high resolution is achieved. Japanese Patent Laid-Open No. 5-216322 discloses providing a color image forming method capable of obtaining a color image having excellent glossiness.

[0006] The color image forming method disclosed in Japanese Patent Application Laid-Open No. 5-216322 discloses a transfer member 1 as shown in FIG.
00, a transparent resin layer 101 made of a thermoplastic resin
The toner image is melted in the transparent resin layer 101 by a belt-type fixing device having a built-in heat source, and then the transfer member is separated from the belt-type fixing device after cooling and solidification. Thus, a color image can be obtained.

[0007]

However, the prior art described above has the following problems. That is, in the case of the color image forming method according to JP-A-5-216322, when a color image is fixed on a transfer body using a belt-type fixing device, when heat and pressure are applied to the transfer body, As shown in FIG. 11, the transparent resin layer 101 made of a thermoplastic resin interposed on the transfer body 100 is
The thermoplastic resin forming the transparent resin layer 101 protrudes about 00 μm or protrudes and adheres to the fixing belt, and the thermoplastic resin transferred on the fixing belt is transferred to a pressure roll pressed against the fixing belt, There is a problem that the back surface of the transfer body 100 is stained.

Therefore, as a technique for solving the problem caused by the transparent resin layer 101 made of a thermoplastic resin interposed on the transfer member protruding from the end of the transfer member,
As disclosed in US Pat. No. 5,234,782,
As shown in FIG. 12, the thermoplastic resin 2 on the recording medium 200
01 near the edge 202 (at least 1/8 inch)
A technology that does not provide only (does not apply) has already been disclosed.

However, the above US Pat. No. 5,234,782
In the case of the technique disclosed in Japanese Patent Application Laid-Open No. H10-205, the transparent resin layer 201 made of a thermoplastic resin interposed on the recording medium 200
However, although it is possible to solve the problem caused by protruding from the edge of the recording medium 200, the thermoplastic resin is removed after the recording medium 200 is cut into a desired size, or the edge portion on the recording medium 200 is removed. Only in the vicinity 202 (at least 1/8 inch) of the thermoplastic resin 201 from the beginning
Therefore, there is a new problem that a contrivance is required to prevent the application of the resin, which requires a great deal of labor and cost.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to use a thermoplastic resin without requiring much labor and cost. An object of the present invention is to provide an electrophotographic transfer sheet capable of preventing an image quality defect caused by a transparent resin layer protruding from an end of the electrophotographic transfer sheet, and a color image forming apparatus using the same.

[0011]

In order to solve such a problem, a transfer sheet for electrophotography according to claim 1 is provided.
In an electrophotographic transfer sheet provided with an image receiving layer containing a thermoplastic resin as a main component on one surface of a base material, an angle formed by a cut cut surface at at least one edge portion and a back surface of the electrophotographic transfer sheet is 75 °. An electrophotographic transfer sheet, characterized in that:

The electrophotographic transfer sheet according to claim 2, wherein the electrophotographic transfer sheet has a substrate thickness of 1
2. The electrophotographic transfer sheet according to claim 1, wherein the thickness of the image receiving layer is 20 to 250 [mu] m and the thickness of the image receiving layer is 5 to 20 [mu] m.

Further, the color image forming apparatus according to a third aspect of the present invention transfers a toner image made of a color toner onto the image receiving layer of the electrophotographic transfer sheet according to the first aspect,
In a color image forming apparatus for forming a color image, a toner image composed of color toner transferred onto the image receiving layer of the electrophotographic transfer sheet is heated and fused by a belt-type fixing device to form a color image. The fixing device rotatably supports the fixing belt by a plurality of rolls including a heating roll, presses a pressure roll to the heating roll via a fixing belt, and presses a pressure contact portion between the fixing belt and the pressure roll. Passing the electrophotographic transfer sheet so that the toner image is located on the fixing belt side,
A color image forming apparatus, wherein a toner image is fixed by heating and pressing, and an electrophotographic transfer sheet is peeled from the fixing belt in a state where the fixing belt is cooled to some extent.

Further, in the color image forming apparatus according to the present invention, the angle between the cut surface of the transfer sheet for electrophotography and the back surface of the transfer sheet is 75 ° or less. The color image forming apparatus according to claim 3, wherein the color image forming apparatus passes through the press-contact portion.

Further, the color image forming apparatus according to the present invention is characterized in that the pressure of the pressure contact portion between the surface of the portion supported by the heating roll and the pressure roll is ² to 15 kg / cm ^2. A color image forming apparatus according to claim 3 or 4, wherein

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 2 is a configuration diagram showing a color image forming apparatus using an electrophotographic transfer sheet according to Embodiment 1 of the present invention.

The color image forming apparatus 1 receives color image information sent from a host computer such as a personal computer (not shown) and color image information of a color document read by a document reading device (not shown). . In the color image forming apparatus 1, the input color image information is processed by the image processing apparatus 2.
As a result, predetermined image processing such as shading correction, positional deviation correction, brightness / color space conversion, gamma correction, frame erasure, color / movement editing, and the like are performed as necessary.

The image data subjected to the predetermined image processing by the image processing device 2 as described above is yellow (Y),
ROS3 (R) is used as color material gradation data of four colors of magenta (M), cyan (C), and black (BK) (each of 8 bits).
master OutputScanner)
In this ROS 3, image exposure with laser light is performed according to the original color material gradation data.

An image forming means A capable of forming a plurality of toner images of different colors is provided inside the color image forming apparatus 1. The image forming means A mainly includes a photosensitive drum 7 as an image carrier on which an electrostatic latent image is formed.
A scorotron 8 as a charging device for uniformly charging the surface of the photoconductor drum 7 to a predetermined potential, an ROS 3 as an image exposure unit for exposing the surface of the photoconductor drum 7 to an image, And a rotary developing device 9 as a developing means capable of developing an electrostatic latent image formed on the drum 7 to form a plurality of toner images of different colors.

As shown in FIG. 2, the ROS 3 modulates a semiconductor laser (not shown) according to the original reproduction color material gradation data, and emits a laser beam LB from the semiconductor laser according to the gradation data. The laser beam LB emitted from the semiconductor laser is deflected and scanned by the rotary polygon mirror 4, and is scanned and exposed on the photosensitive drum 7 as an image carrier via the f · θ lens 5 and the reflection mirror 6.

The photosensitive drum 7 on which the laser beam LB is scanned and exposed by the ROS 3 is driven to rotate at a predetermined speed in a direction indicated by an arrow by driving means (not shown). The surface of the photosensitive drum 7 is previously charged by a scorotron 8 as a charging device for primary charging.
After being charged to a predetermined polarity (for example, a negative polarity) and a potential, the laser beam L is set in accordance with the original reproduction color material gradation data.
An electrostatic latent image is formed by scanning and exposing B. The electrostatic latent image formed on the photosensitive drum 7 includes four color developing units 9Y, 9M, 9C, and 9BK of yellow (Y), magenta (M), cyan (C), and black (BK). For example, by the rotary developing device 9,
The toner (charged color material) charged to a negative polarity having the same polarity as the charged polarity of the photoconductor drum 7 is reversely developed to form a toner image of a predetermined color. In each of the developing devices 9Y, 9M, 9C, and 9BK of the rotary type developing device 9, for example,
A spherical toner having an average particle size of 5.5 μm is used. still,
The toner image formed on the photosensitive drum 7 is charged with a negative polarity by the pre-transfer charger 10 as necessary, and the charge amount is adjusted.

A toner image of each color formed on the photosensitive drum 7 is transferred onto an intermediate transfer belt 11 serving as an intermediate transfer member disposed below the photosensitive drum 7 as a primary transfer means. The image is multiply transferred by the transfer roll 12. The intermediate transfer belt 11 is moved at the same moving speed as the peripheral speed of the photosensitive drum 7 by a driving roll 13, a driven roll 14a, a tension roll 14b, and a backup roll 15 as an opposing roll constituting a part of the secondary transfer unit. , So as to be rotatable along the arrow direction.

On the intermediate transfer belt 11, yellow (Y), magenta (M), cyan (C), and black (BK) are formed on the photosensitive drum 7 according to the color of the image to be formed. All or some of the toner images of the four colors are transferred by the primary transfer roll 12 while being sequentially superimposed. The toner image transferred onto the intermediate transfer belt 11 is transferred onto a transfer sheet 16 for electrophotography as a recording medium conveyed to a secondary transfer position at a predetermined timing by a backup roll 15 supporting the intermediate transfer belt 11. When,
The transfer is performed by the pressing force and the electrostatic attraction force of the secondary transfer roll 17 constituting a part of the second transfer unit that presses against the backup roll 15. As shown in FIG. 2, the electrophotographic transfer sheet 16 has a predetermined size from a feed cassette 1 serving as a transfer sheet accommodating member disposed at a lower portion in the color image forming apparatus 1.
8a. The fed electrophotographic transfer sheet 16 is transferred to the intermediate transfer belt 11 at a predetermined timing by a plurality of transport rolls 22 and registration rolls 23.
To the secondary transfer position. Then, as described above, the backup roll 15 and the secondary transfer roll 17 as the secondary transfer means are provided on the electrophotographic transfer sheet 16.
Thus, a toner image of a predetermined color is collectively transferred from the intermediate transfer belt 11.

An electrophotographic transfer sheet 16 on which a toner image of a predetermined color is transferred from the intermediate transfer belt 11
After being separated from the intermediate transfer belt 11, the toner image is conveyed to a fixing device 25 by a conveyance belt 24, and the toner image is fixed on the electrophotographic transfer sheet 16 by heat and pressure by the fixing device 25, and is used for one-sided copying. In this case, the sheet is discharged out of the apparatus and the color image forming process is completed.

On the other hand, in the case of double-sided copying, the electrophotographic transfer sheet 1 having a color image formed on the first surface (front surface) is used.
6 is not discharged to the outside of the apparatus as it is, the transport direction is changed downward by a reversing gate (not shown), and is once transported to a reversing passage 29 by a tri-roll 27 and a reversing roll 28 with three rolls pressed against each other. Then, the transfer sheet 16 for electrophotography is conveyed to the two-sided passage 30 by the reversing roll 28 which is reversed this time, and once conveyed to the registration roll 23 by the conveying rolls 31 provided in the two-sided passage 30 and stopped. I do. The transfer of the electrophotographic transfer sheet 16 is started again by the registration roll 23 in synchronization with the toner image on the intermediate transfer belt 11, and the toner image is transferred to the second surface (back surface) of the electrophotographic transfer sheet 16. After the transfer / fixing step is performed, the sheet is discharged outside the apparatus.

In FIG. 2, reference numeral 32 denotes a cleaning device for removing residual toner, paper dust and the like from the surface of the photosensitive drum 7 after the completion of the transfer process, and reference numeral 33 denotes a device for cleaning the intermediate transfer belt 11. Intermediate transfer belt cleaner,
Reference numeral 34 denotes a manual feed tray, and reference numeral 35 denotes a toner cartridge containing toner of each color of yellow (Y), magenta (M), cyan (C), and black (BK).

By the way, the electrophotographic transfer sheet according to this embodiment is an electrophotographic transfer sheet in which an image receiving layer mainly composed of a thermoplastic resin is provided on one surface of a base material, wherein at least one edge portion is provided. The angle between the cut surface and the back surface of the electrophotographic transfer sheet is set to 75 ° or less.

The transfer sheet for electrophotography according to this embodiment is configured such that the thickness of the substrate is 120 to 250 μm and the thickness of the image receiving layer is 5 to 20 μm.

That is, the electrophotographic transfer sheet 16
As shown in FIG. 3, for example, a 10-40 μm thick
m based on a photographic paper base material 42 coated with a polyethylene (PE) coating layer 41, and one surface (surface) of the photographic paper base material 42 is mainly composed of a thermoplastic resin such as polyester. It is configured to provide a transparent image receiving layer (transparent resin layer) 43 coated with a material having a thickness of 5 to 20 μm, for example, a thickness of 10 μm.

In the transfer sheet 16 for electrophotography, the thickness of the support 40 is 150 μm, and the front and back surfaces of the support 40 are provided with a polyethylene covering layer 41 having a thickness of 10 to 30 μm. The thickness of the base material 42 including the support 40 and the coating layer 41 is in the range of 190 to 210 μm. However, the electrophotographic transfer sheet 16
For example, the thickness of the substrate is set to 120 to 250 μm by changing the thickness of the support 40. If the fixing device does not have the thickness of the paper, winding occurs if the thickness is not enough. Therefore, the thickness of the base material 42 needs to be 120 μm or more,
If the thickness exceeds 250 μm, a transfer failure is likely to occur.

As shown in FIG. 3, a back layer 44 is provided on the back of the electrophotographic transfer sheet 16 so that writing with a pencil, a ball-point pen or the like is possible. As the transfer sheet 16 for electrophotography, for example, a sheet having an overall basis weight of 190 to 230 g / m ² is used, but it is a matter of course that a sheet having a basis weight other than this can be used. It goes without saying that the back layer 44 need not be provided.

The electrophotographic transfer sheet 16 is
As shown in FIG. 1, the cut face at least at one edge portion is perpendicular to the surface of the electrophotographic transfer sheet 16, that is, is not 90 °, but the cut face 16 a
(Cutting angle) θ between the sheet and the back surface 16b of the electrophotographic transfer sheet 16 is not more than 75 ° by means such as cutting. Is preferably set to 30 to 75 °. This is 75 °
If the angle is less than 30 °, there is no effect, and if the angle is less than 30 °, the strength of the end portion of the sheet becomes weak, so that the sheet is likely to be broken, which is not preferable.

An electrophotographic transfer sheet 1 according to this embodiment
In 6, various methods are employed as a cutting method for cutting so that the cutting section angle θ becomes 75 ° or less.

That is, as a general cutting method of the electrophotographic transfer sheet 16, for example, the following method can be adopted. Methods such as shear cutting, leather cutting, and score cutting with a slitter. Methods such as shirring sheet cutting, single rotary sheet cutting, twin synchro fly sheet cutting, drum winding sheet cutting with a sheet cutter. Methods such as flat pressure die cutting using a punching method and die cutting using a rotary method.

A specific mode of performing cutting by these methods will be described. First, the electrophotographic transfer sheet 16
To describe the case where the blade is inserted from the back side of, the blade is set obliquely so that the cut surface angle θ = 75 ° or less,
Insert the blade obliquely inward from the back side. This method is effective when a slitter is used and when a drum-wrapped sheet cutter is used. Further, in the case of shear cutting and score cutting by a slitter, the rotation axis of the round blade is inclined inward with respect to the surface of the electrophotographic transfer sheet 16 to obtain
Preferably, it is set at an angle of 75 to 30 °.

Next, when a blade is to be inserted from the front side of the electrophotographic transfer sheet 16, the following three methods are suitable. The blade is set obliquely so as to have a cut surface angle θ = 75 ° or less, and the blade is inserted obliquely outward from the front side of the electrophotographic transfer sheet 16. This method is effective when a slitter is used and when a drum-wrapped sheet cutter is used. Further, in the case of shear cutting or score cutting by a slitter, the rotation axis of the round blade is inclined inward with respect to the back surface of the electrophotographic transfer sheet 16, and preferably, 75
Set at an angle of ~ 30 °. Image receiving layer 43 (transparent resin layer) when cutting using an obtuse angle blade
, The cutting plane angle θ is substantially 75
Cut to less than °. In this method, the fiber of the image receiving layer 43 (transparent resin layer) of the electrophotographic transfer sheet 16 and the fiber of the base material 42 are crushed at the time of cutting by using a rounded blade, and the fiber is loosened by being torn. And the cutting section angle θ becomes substantially 75 ° or less. This method is effective for cutting by a slitter, a sheet cutter and a punching method. When the blade enters from the image receiving layer 43 (transparent resin layer) of the electrophotographic transfer sheet 16 toward the base material 42, the transfer sheet for electrophotography 16 itself is forcibly forced in a direction perpendicular to the cut surface. 16 and cut so that the cut surface angle θ is substantially 75 ° or less.
This method is effective for cutting with a sheet cutter.

As described above, as shown in FIG. 1, the electrophotographic transfer sheet 16 has at least one cut edge face 16a at one edge portion and the electrophotographic transfer sheet 1
6 and the back surface 16b (cutting surface angle) θ are 75 °
The electrophotographic transfer sheet 16 is cut at least so that the cutting section angle θ of the leading end surface in the sheet feeding direction is 75 ° or less. , Two or three sides, or all four sides, may be cut so that the cut angle θ is 75 ° or less. In this manner, when all four sides of the electrophotographic transfer sheet 16 are cut so that the cut surface angle θ is 75 ° or less, the paper feeding direction is not limited. Is set or fed so that is positioned at the leading end in the feeding direction.

By the way, the electrophotographic transfer sheet 16
It is desirable to improve the internal bonding strength of the paper as the support 40 of the sheet 16, and for the improvement of the internal bonding strength of the paper 40, for example, the type of pulp of the base paper (a softwood having high rigidity) , Heat-treated pulp, beaten to increase fiber-to-fiber bond, paper strength agent (polyamide, acrylamide, amine compound, etc.), wet paper strength agent (polyamide,
Addition of epoxy, melamine compounds, etc., impregnation of aqueous resin (polyvinyl alcohol, fluorine resin, acrylic, styrene, acryl-styrene copolymer, amide, urethane, epoxy compound, etc.) with size press, coating, etc. Is appropriately selected depending on the purpose.

The image receiving layer 43 (transparent resin layer) of the present invention is also characterized in that the gloss of the recorded image area is uniform. If the toner is not embedded in the electrophotographic transfer sheet 16 at the time of fixing the toner, the gloss varies depending on the thickness of the toner, and the image quality is significantly reduced. Therefore, it is important to embed the toner in the image receiving layer 43 in order to eliminate uneven gloss. That is, in order to embed the toner, it is necessary that the toner is sufficiently melted by heating for a short time, the transparent resin constituting the image receiving layer 43 is softened, and is compatible with the toner. As a result of intensive study on this,
It is desirable that the image receiving layer 43 has a polyester resin as a main component, the number average molecular weight (Mn) of the resin is in the range of 5,000 to 20,000, and the glass transition temperature is in the range of 30 to 85 ° C. If the molecular weight (Mn) is greater than 20,000, the softening of the transparent resin layer 43 during heating is insufficient, so that it is difficult to embed the toner and the gloss matching property may be reduced. On the other hand, when the molecular weight (Mn) is less than 5,000, cracks may occur due to insufficient formation of the coating film. If the glass transition temperature is lower than 30 ° C., the blocking property is poor and a problem occurs in running properties. On the other hand, if the glass transition temperature is higher than 85 ° C., the softening of the transparent resin layer 43 is insufficient and the toner is insufficiently embedded. It may be.

Examples of the resin constituting the image receiving layer 43 (transparent resin layer) include a polyester resin, a styrene-acrylate resin, a styrene-methacrylate resin and the like, and a polyester resin is particularly preferably used. Examples of the polyhydric alcohol component and the polyhydric carboxylic acid component constituting the polyester resin include the following.

The polyhydric alcohol components include ethylene glycol, propylene glycol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, Neopentylene glycol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, a monomer obtained by adding olefin oxide to bisphenol A, or the like can be used.

Examples of the polycarboxylic acid component include maleic acid, maleic anhydride, fumaric acid, phthalic acid, terephthalic acid, isophthalic acid, malonic acid, succinic acid, glutaric acid,
Dodecenylsuccinic acid, n-octylsuccinic acid, n-dodecenylsuccinic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,
2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxy-2-methyl-2-methylenecarboxypropane, tetra (methylenecarboxy) methane, 1,2,7,8- Octanetetracarboxylic acid, trimellitic acid, pyromellitic acid and lower alkyl esters of these acids can be used.

The polyester resin in the present invention is synthesized by using one or more of the above-mentioned polyhydric alcohol component and polyhydric carboxylic acid component from each component. Also, the components of the toner
Since a polyester resin is mainly used for a color toner and a styrene-acrylic resin is mainly used for a monochrome toner, it is preferable to select a resin composition having high compatibility with the toner. Accordingly, one or a mixture of two or more of polyester resins, styrene-acrylate resins, styrene-methacrylate resins, and the like are used according to the purpose.

Further, the image receiving layer 43 (transparent resin layer)
A pigment, a release agent, a conductive agent, and the like can be contained as long as the transparency is not impaired. In that case, the resin content of the main component with respect to all the resins needs to be 80% by weight or more. Further, it is preferable that the transparent resin layer 43 is adjusted to have a surface electric resistance of 8.0 × 10 ⁸ Ω or more at a temperature of 20 ° C. and a relative humidity of 85%.

In the substrate of the present invention, general high-quality paper is used as the support 40. A coating layer 41 made of polyethylene, polypropylene, polyethylene terephthalate, polystyrene, or the like is provided on both front and back surfaces of the support 40 with a thickness of 20 to 3.
Coated to a thickness of 0 μm. After the coating layer 41 is coated on both the front and back surfaces of the support 40, the coating layer 41 is subjected to a smoothing treatment in a usual curing step, surface treatment step, or the like. The transparent resin layer 43
The surface to be coated with JIS K
The maximum roughness Rmax based on 0601 is adjusted to be 20 μm or less.

As the back layer 44, a layer obtained by adding an adhesive such as a polyester resin to an inorganic pigment or the like and applying a thin film having a predetermined thickness is used. Examples of the pigment used for the back layer 44 include heavy calcium carbonate, light calcium carbonate, kaolin, calcined kaolin, structural kaolin, delamikaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, alumina, and carbonate. Mineral pigments such as magnesium, magnesium oxide, silica, magnesium aminosilicate, particulate calcium silicate, particulate magnesium carbonate, particulate light calcium carbonate, white carbon, bentonite, zeolite, sericite, smexite, polystyrene resin, styrene An acrylic copolymer resin, a urea resin, a melamine resin, an acrylic resin, a vinylidene chloride resin, a benzoguanamine resin, a fine hollow particle thereof, a through-hole type organic pigment, and the like can be mentioned. Used.

The adhesive used for the back layer 44 is selected in consideration of the adhesiveness of the photographic paper base material 42 to the coating layer 41 and the like, and is selected from polyester resins, polyurethane resins, polyolefin resins, polyamide resins, and olefin-anhydride. Synthetic polymer compounds such as maleic acid resin and melamine resin can be exemplified, but polyester resin is preferable.

The mixing ratio of the adhesive used for the back layer 44 is in the range of 100 to 400% by weight with respect to 20% by weight of the pigment.

The back layer 44 preferably contains a releasing agent or a lubricant in an amount of 0.5 to 5 parts by weight based on 100 parts by weight of the inorganic pigment. Is less than 0.5 parts by weight, the adhesion between the image receiving layer 43 (transparent resin layer) and the back layer 44 becomes strong, the coefficient of friction between papers becomes high, and the running property is deteriorated. On the other hand, if it exceeds 5 parts by weight, the generation of paper dust due to the decrease in the strength of the back layer 44 becomes a problem.

Examples of the releasing agent and the lubricant in the present embodiment include higher fatty acids such as stearic acid, metal salts of higher fatty acids such as zinc stearate, higher fatty acid amides such as stearamide and methylolated products thereof, and polyethylene wax. And the like.

In the coating liquid of the back layer 44, in addition to these, various auxiliaries such as a surfactant, a ph regulator, a viscosity regulator, a softener, a gloss-imparting agent, a wax, a dispersant, a fluid Stabilizers, antistatic agents, stabilizers, antistatic agents, crosslinking agents,
A sizing agent, a fluorescent whitening agent, a coloring agent, an ultraviolet absorber, an antifoaming agent, a waterproofing agent, a plasticizer, a lubricant, a preservative, a fragrance, and the like can be appropriately used as needed.

The coating amount of the back layer 44 is selected according to the purpose of use of the transfer sheet of the present invention according to the curl balance and the like. Generally, both sides are coated with the coating layer 41. It is necessary to completely cover irregularities on the surface of the support 40, and the dry weight is 8 to 40 g / m ^2.
Is preferred. As a coating method for forming the back layer 44, generally known coating apparatuses such as a blade coater, an air knife coater, a roll coater, a reverse roll coater, a bar coater, a curtain coater, a die slot coater, a gravure coater, a champlex coater, A brush coater, a two-roll coater, a size press coater of a metering blade type, a bill blade coater, a short well coater, a gate roll coater, or the like can be appropriately provided.

When the back layer 44 is subjected to a smoothing process, it is performed by a normal smoothing device such as a super calender, a gloss calender, a soft calender, etc. In addition, it is appropriately used in an on-machine or an off-machine, and the form of the pressure device, the pressure nip, the heating, and the like are appropriately adjusted according to a normal smoothing device.

The support 40 used for the substrate 42 of the present invention
Is not particularly limited, but for example, papermaking ph is 4.
The papermaking ph containing an alkaline filler such as an acidic paper and calcium carbonate as a main component and having a pH of about 5 from a weak acidity of about 6 to about 9
A paper base such as neutral paper making which is made weakly alkaline is used. As for the papermaking method, a general paper machine such as a long net multi-cylinder type, a round net single-cylinder type, a Yankee or the like is appropriately used. In addition, synthetic paper, nonwoven fabric, and synthetic resin film can be used depending on the application.

To coat the image receiving layer 43 (transparent resin layer) on the substrate 42, a generally known coating apparatus such as a reverse roll coater, a bar coater, a curtain coater, a die slot coater, a gravure coater or the like is used. Used as appropriate.

Further, the sheet 16 coated with the image receiving layer 43 (transparent resin layer) can be subjected to a smoothing treatment as required, and can be formed by a normal super calender, gloss calender,
This is performed by a smoothing processing device such as a soft calender. Further, the form of the pressurizing device, the number of pressurizing nips, heating and the like are appropriately adjusted in accordance with a normal smoothing device. On the other hand, as the base material 42 of the present invention, there is no coating layer 41 or back layer 44,
It is a matter of course that the one composed only of the support can be used. In this case, the sheet 16 is composed of two layers, the support 40 and the image receiving layer 43.

By the way, as shown in FIG. 2, a full-color toner image is transferred and fixed on the electrophotographic transfer sheet 16 configured as described above by the color image forming apparatus 1, as shown in FIG. Then, the electrophotographic transfer sheet 1 on which a full-color toner image has been transferred and fixed
Reference numeral 6 is configured to receive secondary fixing again by a belt-type fixing device. The belt-type fixing device may be used not as a fixing device for performing secondary fixing but as a fixing device 25 disposed inside the color image forming apparatus 1. There is no need to fix.

In this embodiment, the belt-type fixing device rotatably supports the fixing belt with a plurality of rolls including a heating roll, and presses a pressure roll against the heating roll via a fixing belt. The fixing belt is pressed by heating and pressing the toner image by passing the pressure contact portion between the fixing belt and the pressure roll through an electrophotographic transfer sheet so that the toner image is positioned on the fixing belt side, and the fixing belt is cooled to some extent. In this state, the transfer sheet for electrophotography is peeled off from the fixing belt.

FIG. 2 shows a secondary fixing unit used in combination with the color image forming apparatus 1.

The secondary fixing unit 50 has an inlet 51 into which the transfer sheet 16 for electrophotography discharged from the color image forming apparatus 1 is introduced. A switching gate 52 for switching the transfer path of the transfer sheet 16 is provided. In the case where the electrophotographic transfer sheet 16 discharged from the color image forming apparatus 1 is discharged onto an external first discharge tray without performing secondary fixing, the transfer path is switched by the switching gate 52. The sheet is switched to the upper first transport path 53, and is discharged onto the first discharge tray 55 by the discharge roll 54. Further, when the electrophotographic transfer sheet 16 discharged from the color image forming apparatus 1 is subjected to the secondary fixing process, the switching gate 52 causes the conveyance path to move downward to the second path.
Is transported to a belt-type fixing device 58 by a plurality of transport rollers 57, undergoes a fixing process by the belt-type fixing device 58, and
9 discharges onto the second discharge tray 60.

FIG. 4 shows a belt-type fixing device disposed inside the secondary fixing unit 50.

As shown in FIG. 4, the belt-type fixing device 58 includes a heating roller 61, a fixing belt 64 rotatably supported by a plurality of rollers 62 and 63 including the heating roller 61, Fixing belt 64 on roll 61
And a pressure roll 65 pressed into contact therewith.

As the heating roll 61, as shown in FIG. 5, for example, an elastic layer 67 made of silicon rubber or the like having a rubber hardness of 20 to 60 ° is formed on the surface of a metal core 66 made of aluminum or stainless steel. Is formed to a predetermined outer diameter (for example, 50 mm) by covering the surface of the elastic layer 67 with a release layer 68 made of a PFA tube or the like. The heating roll 61 has a heating source of 300 to 350 W
Is heated from the inside such that the surface temperature of the heating roll 61 becomes a predetermined temperature (about 155 ° C. to 195 ° C.).

As the pressure roll 65, for example, one having the same configuration as the heating roll 65 shown in FIG. 5 is used, and the surface of a metal core 66 made of aluminum, stainless steel or the like has a rubber hardness of 20%. An elastic layer 67 made of silicon rubber or the like having a thickness of about 60 ° is coated with a thickness of about 1 to 3 mm, and a surface of the elastic layer 67 is coated with a release layer 68 made of a PFA tube or the like, and has a predetermined outer diameter. (For example, 5
0 mm). Inside the pressure roll 65, a halogen lamp 69 of 300 to 350 W is provided as a heating source.
Is heated from the inside such that the surface temperature of the substrate becomes a predetermined temperature (about 80 ° C. to 180 ° C.).

The heating roll 61 and the pressure roll 65 are configured to be pressed against each other with a load of 75 kg to 200 kg via a fixing belt 64 by pressing means (not shown).

Further, the fixing belt 64 includes a heating roll 61, a peeling roll 62, and a walk control roll 63.
, And is rotatably supported at a predetermined moving speed (30 mm / sec) by a heating roll 61 which is rotatably driven by a driving source (not shown). As the fixing belt 64, for example, an endless film made of polyimide having a thickness of 80 μm coated with a silicon rubber layer having a thickness of 50 μm is used.

Further, on the inner surface side of the fixing belt 64,
A cooling heat sink 70 for forcibly cooling the fixing belt 64 between the heating roll 61 and the peeling roll 62.
The cooling heat sink 70 constitutes a cooling / sheet conveying unit that cools the transfer sheet 16 and conveys the sheet 16. Then, the fixing belt 64 is heated at 50 ° C.
It is cooled to about 80 ° C.

A small-diameter tension roll 71 for applying a fixed tension to the fixing belt 64 is provided between the cooling heat sink 70 and the heating roll 61.

In the belt-type fixing device 58,
As shown in FIG. 4, the color toner image T is transferred to the surface.
The fixed electrophotographic transfer sheet 16 is
The color toner image T is introduced into a pressure contact portion 72 (nip portion) between the pressure roller 1 and the heating roll 61 via a fixing belt 64 via a fixing belt 64 so that the color toner image T is positioned on the heating roll 61 side. While passing through the pressure contact portion 72 between the roll 61 and the pressure roll 65, the color toner image T is heated and melted and fixed on the electrophotographic transfer sheet 16 as shown in FIG. At this time, the image receiving layer 43 (transparent resin layer) formed on the surface of the electrophotographic transfer sheet 16
The fixing belt 64 is also softened by being heated and comes into close contact with the surface of the fixing belt 64.

In this embodiment, when the electrophotographic transfer sheet 16 having the color toner image T transferred and fixed on the surface thereof is introduced into the press contact portion 72 (nip portion) of the belt-type fixing device 58, The electrophotographic transfer sheet 16
Is conveyed such that the cut surface cut so that the cut surface angle θ is 75 ° or less is located at the front end in the sheet feeding direction.

Thereafter, the electrophotographic transfer sheet 16 on which the color toner image T is fixed on the image receiving layer 43 (transparent resin layer) is heated and melted at a pressure contact portion 72 between the heating roll 61 and the pressure roll 65. , The image receiving layer 43 on the surface
The (transparent resin layer) is conveyed together with the fixing belt 64 in a state where the (transparent resin layer) is in close contact with the surface of the fixing belt 64. Meanwhile, the fixing belt 64 is provided with a heat sink 71 for cooling.
After the cooling, the color toner image T and the image receiving layer 43 (transparent resin layer) are cooled and solidified, and then separated by the peeling roll 62 due to the waist (rigidity) of the transfer sheet 16 itself.

After the peeling step is completed, the surface of the fixing belt 64 is cleaned by a cleaner 73 to remove residual toner and the like, and is ready for the next fixing step.

By the way, as shown in FIG. 1, the electrophotographic transfer sheet 16 according to this embodiment is formed of a cut-off cut surface 16a at at least one edge portion and a back surface 16b of the electrophotographic transfer sheet 16. Angle (cutting angle)
θ is 75 ° or less.
Therefore, when the transfer sheet 16 for electrophotography is fixed by the belt-type fixing device 58, the image receiving layer 43 (transparent) of the surface of the transfer sheet 16 for electrophotography is heated and pressed by the heating roll 61 and the pressure roll 65. Resin layer) is softened and extruded on the front end surface of the electrophotographic transfer sheet 16,
The transfer sheet for electrophotography 16 has the cut face 1
The angle (cutting section angle) θ between the base 6a and the back surface 16b is 75
°, the image receiving layer 43 (transparent resin layer) extruded on the front end face is formed on the inclined front end face of the electrophotographic transfer sheet 16 as shown in FIG. Adhere to. Therefore, the image receiving layer 43 (transparent resin layer) protrudes from the leading end surface of the electrophotographic transfer sheet 16 when the fixing process is performed, or the thermoplastic resin forming the transparent resin layer 43 is placed on the fixing belt 64. It is ensured that the thermoplastic resin transferred onto the fixing belt 64 without protruding and adhering to the pressing roll 65 pressed against the fixing belt 64 is transferred to the back surface of the transfer sheet 16 for electrophotography. Can be prevented.

Further, in the case of the electrophotographic transfer sheet 16 according to this embodiment, as shown in FIG. 1, the cut-off cut surface 16a at at least one edge portion and the back surface 16b of the electrophotographic transfer sheet 16 are provided. May be cut so that the angle (cutting angle) θ formed by the above is 75 ° or less, the configuration is simple, and a great deal of labor and cost are not required.

[0076]

Embodiments of the present invention will be specifically described below. In the examples, "parts" and "%" indicate "parts by weight" and "% by weight" unless otherwise specified.

[Preparation of Transfer Sheet for Electrophotography] [Preparation of Support] LBKP (freeness (CSF) = 4
80 ml) 100 parts of pulp slurry, 10 parts of soft calcium carbonate as filler and 0.05 of alkane succinic anhydride (Fibran 81, manufactured by Oji National Co., Ltd.)
Part, chaotinized starch (Ace K, manufactured by Oji National)
1.2 parts and 0.4 parts of a sulfuric acid band were added, and the mixture was diluted with white water to have a pH of 7.0 and a fixed concentration of 1.1.
% Stock was prepared. The stock is paper-made using a fourdrinier paper machine, and then a size press solution having a solution concentration of 6% of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch Co.) is applied at a dry weight of 2.0 g / m ² was applied by a size press, dried, and smoothed by a machine calender to a Beck smoothness of 40 seconds.
8 g / m ² of base paper was obtained.

[Preparation of Base Material] A polyethylene resin having a thickness of 20 μm was coated on both the front and back surfaces of the support 40 prepared as described above.
Is applied and cured to form a coating layer 41,
A substrate 42 as a photographic paper base was prepared. The thickness of the base material 42 as the photographic paper base was 200 μm.

[Formation of Back Layer Provided on Backside of Transparent Resin Layer Coating] Water-dispersed polyester resin (WR-
905) 75 parts by weight of an aqueous dispersion (solid content: 20%) 3 parts by weight of light calcium carbonate (Brilliant S15 manufactured by Shiroishi Calcium Co.) 0.1 part by weight of a surfactant (Sandet BL manufactured by Sanyo Chemical Industries) 21.9 parts by weight of pure water The coating solution was prepared using a bar coater so as to have a dry weight of 10 g / m ² on the back surface of the base material 42, and the basis weight was 190 g / m ² .

[Preparation of Transparent Resin Layer on Base Material] A polyester resin having the following content was applied using a gravure coater so that the thickness after drying was 10 μm.
(Transparent resin layer) was formed. 100 parts by weight of polyester resin (trademark: TP220, manufactured by Nippon Synthetic Chemical Company, molecular weight Mn: 16000, glass transition temperature: 70 ° C)

[Evaluation of Image Quality of Electrophotographic Transfer Sheet] Next, the inventors of the present invention prepared an electrophotographic transfer sheet 16 having at least one cut edge 16a at one edge. FIG. 4 shows a prototype produced by cutting an angle (cutting angle) θ with the back surface 16b so as to be various angles, and transferring the color image T onto the transfer sheet 16 for electrophotography. Using such a belt-type fixing device 58, an experiment was performed to evaluate the protrusion of the image receiving layer 43 (transparent resin layer) and the generation of dirt on the pressure roll 65. Acolo is a color image forming apparatus.
r935 (manufactured by Fuji Xerox) was used. In this embodiment, the fixing process of the electrophotographic transfer sheet 16 was performed using only the belt-type fixing device 58.

FIG. 9 shows the result of the above embodiment.

As is apparent from FIG. 9, when the cut-away angle θ is 90 °, the resin protrudes significantly from the fixed transfer sheet 16 similarly to the first sheet and the 100th sheet. There was no dirt on the roll on the first sheet, but on the 100th sheet,
Roll contamination was remarkably observed.

On the other hand, when the cutting section angle θ is 75 °, the resin protrudes from the transfer sheet 16 after fixing similarly to the first sheet and the 100th sheet. Regarding dirt, the first sheet was free of dirt on the roll, and the 100th sheet was able to reduce the degree of dirt on the roll.

When the cut-section angle θ is 60 ° or less, the resin does not protrude from the transfer sheet 16 after fixing, as in the first sheet and the 100th sheet. Similarly, no roll contamination occurred on the first sheet and the 100th sheet.

Next, the present inventors determined the thickness of the base material 42 (excluding the backing layer, if any) of the electrophotographic transfer sheet 16 excluding the image receiving layer 43 (transparent resin layer). As shown in FIG. 7, the relationship with the length of the slope of the base material 42 was geometrically obtained by changing the cutting plane angle θ.

FIG. 13 shows the thickness of the base material (base paper) 42 geometrically determined by changing the cutting section angle θ (including the back layer if there is one) and the slope of the base material 42. It shows the relationship with the length.

As is apparent from FIG. 13, as the thickness of the base material (base paper) 42 increases, the base material 42
The length of the slope becomes longer, but the cut surface angle θ is 90 ° to 8 °.
When the angle is as large as 0 °, the rate of increase in the length of the slope of the base material 42 is small.

On the other hand, when the cutting angle θ becomes 60 ° or less, the base material (base paper)
It can be seen that the length of the slope exceeds 200 μm, and is sufficiently effective in preventing the image receiving layer 43 (transparent resin layer) from protruding.

[0090]

As described above, according to the present invention, the transparent resin layer made of the thermoplastic resin protrudes from the edge of the electrophotographic transfer sheet without requiring much labor and cost. It is possible to provide an electrophotographic transfer sheet capable of preventing the accompanying image quality defect and a color image forming apparatus using the same.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an electrophotographic transfer sheet according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram showing a color image forming apparatus to which the transfer sheet for electrophotography according to Embodiment 1 of the present invention is applied.

FIG. 3 is a cross-sectional view illustrating an electrophotographic transfer sheet.

FIG. 4 is a configuration diagram illustrating a belt-type fixing device of the color image forming apparatus according to the first embodiment of the present invention.

FIG. 5 is a sectional view showing a heating roll and a pressure roll.

FIG. 6 is an explanatory diagram showing a fixing state of an electrophotographic transfer sheet.

FIG. 7 is a diagram illustrating a thickness and an oblique side of an electrophotographic transfer sheet.

FIG. 8 is a diagram showing a result of the embodiment.

FIG. 9 is a chart showing the results of Examples.

FIG. 10 is a diagram showing a transfer body according to a conventional technique.

FIG. 11 is a diagram illustrating a state after fixing of a transfer body according to a conventional technique.

FIG. 12 is a diagram showing one embodiment of a conventional technique.

FIG. 13 is a graph showing the relationship between the thickness of the base paper and the length of the slope of the base paper.

[Explanation of symbols]

16: transfer sheet for electrophotography, 16a: cut face
16b: back surface, 40: support, 41: coating layer, 42: base material, 43: image receiving layer (transparent resin layer), 44: back layer.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Takashi Ogino, Inventor 2274 Hongo, Ebina-shi, Kanagawa Prefecture F-Xerox Co., Ltd.F-term (reference) BB29 BB30 BB34 BB39

Claims (5)

[Claims] 1. An electrophotographic transfer sheet having an image receiving layer containing a thermoplastic resin as a main component on one surface of a base material, wherein at least one edge portion has a cut cut surface and a back surface of the electrophotographic transfer sheet. An electrophotographic transfer sheet, wherein the angle formed is 75 ° or less. 2. The transfer sheet for electrophotography, wherein the thickness of the substrate is 120 to 250 μm, and the thickness of the image receiving layer is 5 to 20 μm.
2. The transfer sheet for electrophotography according to claim 1, wherein: 3. An electrophotographic transfer sheet according to claim 1, wherein a toner image composed of a color toner is transferred onto the image receiving layer of the electrophotographic transfer sheet, and the color toner is transferred onto the image receiving layer of the electrophotographic transfer sheet. In a color image forming apparatus that forms a color image by heating and fusing and fixing a toner image by a belt-type fixing device, the belt-type fixing device can rotate a fixing belt by a plurality of rolls including a heating roll. A pressing roll is pressed against the heating roll via a fixing belt, and a pressing portion of the fixing belt and the pressing roll is pressed with the electrophotographic transfer sheet so that the toner image is positioned on the fixing belt side. The toner image is fixed by heating and pressurizing the toner image, and the fixing belt is cooled to a certain extent. A color image forming apparatus, wherein a transfer sheet is peeled. 4. The press-contact portion is passed with the surface of the transfer sheet for electrophotography having an angle of 75 ° or less formed between the cut surface of the transfer sheet and the back surface of the transfer sheet at the top. 3. The color image forming apparatus according to 3. 5. The pressure of a pressure contact portion between a surface of a portion supported by the heating roll and a pressure roll is ² to 15 kg / cm ^2.
The color image forming apparatus according to claim 3, wherein