JPH07248637A - Ohp film for color image - Google Patents

Abstract

PURPOSE:To provide a clear image with no inside omission by specifying the average grain size of a toner, the thickness of a resin coat layer before surface roughening, and the roughness of the surface-roughened image forming region of the resin coat layer. CONSTITUTION:This overhead projector (OHP) film 60 contact-transfers a toner image of different colors formed on an image carrier with a transfer device, and it has a base layer and a resin coat layer provided on it. Equations 0.125X(a+6)<=Rz<=a/2, Rz<=0.8t are satisfied, where (a) is the average grain size of the toner used for a color image forming device, (t) is the thickness of the resin coat layer supporting the toner before surface roughening, and Rz is the roughness of the surface-roughened image forming region of the resin coat layer. The OHP film 60 is coated with a polyethylene resin 62 as the upper layer on a PET (polyethylene terephtalate) film layer 61 used as the base layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an OHP film used in an overhead projector (OHP), and more particularly to an OHP film preferably used as a transfer material in a color image forming apparatus.

[0002]

2. Description of the Related Art In a color image forming apparatus, a toner image is formed on an image bearing member by charging, exposing and developing, and a step of transferring the toner image to a transfer material is repeated each time a toner image is obtained. There is one method of obtaining a color image by superposing toner images of a plurality of colors on a transfer material.

A color image forming apparatus of this type has been put into practical use with the configuration described in German Patent No. 2607727, Japanese Patent Laid-Open No. 50-50935, and the like.

A transparent sheet for an overhead projector (hereinafter referred to as OHP), that is, an OHP film is often used as one of transfer materials in this type of color copying machine or the like. O
The color image formed on the HP film is required to have a high degree of light transmittance in order to project a color image having high sharpness on the screen. A large transmissive OHP having a large amount of light is usually used for a large conference. or,
In recent years, a small-sized reflective / transmissive OHP has been used for meetings of a small number of people. However, since the same small amount of light is transmitted through the OHP film twice, the sharpness is originally low in the color OHP film image. The projected image is much lower than that of the large one, and the image quality defect of the original image tends to appear remarkably.

Therefore, in order to always provide a high-quality color projection image regardless of many kinds of OHPs on the market, it is necessary to enhance the sharpness, resolution and light transmittance of the OHP film image as much as possible. For that purpose, it goes without saying that the fixing efficiency in the color image forming process is increased, but on the other hand, a large difference in image quality, particularly in the transparency and sharpness, is also observed depending on the constitution of the OHP film itself, and therefore the improvement is also made. is necessary.

It is known that an OHP film for a color image is excellent in image quality if it has the following constitution. That is, as a base material layer, a PET (polyethylene terephthalate) layer having a thickness of about 100 μm and an upper layer of about 10 μm
The transparent resin coat layer having a thickness of m is provided uniformly and smoothly, and the transparent resin has the same or slightly lower glass transition point or softening point than the toner binder resin.

The OHP film having such a two-layer structure has the following effects. At the same time as the toner melts during fixing, the transparent resin coat layer also softens and melts, so that the toner having an average particle size of about 7 to 8 μm is embedded in the transparent resin coat layer. Therefore, the fine lines are not crushed due to the pressure, and a high-resolution color fixed image can be obtained. In addition, even in a four-color overlapping color image in which the toner thickness varies from solid to different halftone areas in the image after fixing, the unevenness on the surface causes toner to be embedded in the transparent resin coat layer, which is especially the edge of the image pattern. The part becomes gentle and smooth, following the surface of the fixing roller. Therefore, there is no loss of light scattering due to unevenness of the surface with respect to the transmitted light, and it is possible to obtain a highly transparent color projection image. If the surface has irregularities, a shadow contour may be generated, resulting in a very unsightly image.

At present, the color OHP film image output machine for conference presentation is expected as one of the applications of a compact, low-cost, high-quality color printer by incorporating a new technology into the system construction of the color copying machine. ing.

In the image forming apparatus, plain paper and OH
The fixing conditions are different from those of the P film, and the heat capacity of the OHP film is larger than that of the paper because it is made of a plastic resin film. For example, when fixing the toner on the OHP film, the fixing temperature is higher than that of the paper. It is necessary to take measures such as raising the speed or slowing the conveying speed of the OHP film, and therefore, the paper or the OHP film is detected by the optical sensor provided in the transfer material feeding path. A conventional OHP film is made of a resin and a film with good transparency, and is printed on the tip of the OHP film for detection to make a part that does not transmit light. When the OHP film starts passing through the optical sensor, it does not transmit at first.
Next, the image forming apparatus is configured to recognize that the film is an OHP film by detecting light transmission.
In the case of paper, it is recognized that the paper is paper because light is not transmitted while the paper passes through the optical sensor.

[0010]

As a result of the inventors performing output using the OHP film of the above-mentioned conventional example in a color printer experimental machine, a so-called "middle-out" phenomenon occurs, and a part of toner is missing. The state in which it did was seen especially in the character image and the thin line image. This phenomenon is caused by a toner portion that is thickly overlapped when a multicolor transfer is performed from the photosensitive drum to the OHP film on the transfer drum, especially in the center portion of the character pattern when outputting a high resolution character pattern in the image pattern. Is not transcribed and is missing, resulting in a blank state.

By the way, in the transfer drum, a solid transfer having a structure in which an elastic resin or rubber 10b is provided on a metal cylinder 10a as shown in FIG. 10, and a PVdF (polyvinylidene fluoride) sheet 10c is further wound thereon. The drum 10 and a cylindrical support member 72 as shown in FIG.
There is a transfer drum 70 having a so-called notch structure in which the circumferential surface of the PVdF sheet 71 is notched and the PVdF sheet 71 is wound around the notch portion.

The solid transfer drum has a simplified internal structure as compared with a transfer drum having a cutout structure, so that the cost can be reduced, and since a flexible PVdF sheet is supported from the inside, a cutout type transfer drum is provided. There is an advantage that deformation and breakage of the sheet, which is a drawback of, can be reduced.

However, it is known that the above hollow phenomenon is remarkable in the case of a solid transfer drum having a hard surface. The surface hardness of the solid transfer drum is large, and when measured by Asker hardness meter F type manufactured by Kobunshi Keiki Co., Ltd., the notch type is 10 or less, whereas the surface hardness of the solid transfer drum is more than 80. Show. The harder surface of the transfer drum is more likely to cause hollows.
When pressure is applied more strongly to the toner at the nip portion between the photosensitive drum and the transfer drum and the toner is crushed by force and moves away from the nip portion, the chemical affinity between the toner and the photosensitive drum is the transfer drum (OHP film surface) and the toner. It is considered that this is because the toner works toward the photosensitive drum side from the transfer material surface because it works more strongly than the affinity between the toner and the toner amount on the transfer material surface decreases.

As for the hollow phenomenon which occurs in the OHP film used in the color image forming apparatus having the solid transfer drum, the resin portion on the surface (to which toner is transferred) of the OHP film contacting the photosensitive drum is roughened. However, since the roughness of the surface of the OHP film becomes rough, the light transmittance before fixing is lowered, and as a result, it becomes difficult to distinguish the OHP film and the plain paper by the optical sensor.

On the other hand, the fixing conditions are different between the OHP film and the plain paper, and the two are discriminated by the optical sensor before the fixing. However, since the surface roughness of the OHP film is roughened as described above, The OHP film may be mistakenly recognized as plain paper, and as a result, the same fixing condition as that of plain paper may be applied, so that the toner on the OHP film is not sufficiently heated, and thus the color mixing property, the transparency, and the glossiness may be deteriorated. In some cases, the image was insufficient.

For example, the surface roughness of the OHP film is Rz.
In the case of discriminating between the light transmittance when roughened to 3 to 5 μm and the light transmittance in the case of paper, there is a drawback that an expensive optical sensor that requires accuracy is required.

In order to solve such drawbacks, OHP
By forming a transparent part, that is, a smooth surface at the tip of the film, a difference in light transmission from that of plain paper is generated, and OHP
Although it can be detected accurately as a film, in that case, since the leading end is smooth at the beginning of the feeding and feeding, the feeding and feeding roller and the surface are liable to slip, resulting in a feeding failure. was there.

Therefore, the main object of the present invention is to provide a color image O which can obtain a clear color image without a blank area.
It is to provide an HP film.

Another object of the present invention is to provide an OHP film for a color image which can detect an original easily at a low cost.

Still another object of the present invention is to provide an OHP film for color image having good transportability.

[0021]

The above object can be achieved by the OHP film for color images according to the present invention. In summary, the present invention is an OHP film for contact-transferring toner images of different colors formed on an image bearing member by a transfer device in a color image forming apparatus, the OHP film being provided on a base layer and thereon. A resin coat layer, the average particle diameter of the toner used in the color image forming apparatus is a, the thickness of the resin coat layer supporting the toner before roughening treatment is t, and the thickness of the resin coat layer is t. R is the roughness of the image forming area subjected to the rough surface treatment.
When z, 0.125 × (a + 6) ≦ Rz ≦ a /
2. The OHP film is characterized by simultaneously satisfying both the formulas 2 and Rz ≦ 0.8t.

The light transmittance of the resin coating layer subjected to the surface roughening treatment before fixing is n _1, and the surface of the resin coating layer subjected to the surface roughening treatment is smoother and light transmissive than the resin coating layer subjected to the surface roughening treatment. When a good region is provided and the light transmittance of this region is n ₃ , it is preferable to satisfy the formula of n ₁ / n ₃ ≦ 0.7.

The light transmittance after fixing of the roughened surface is set to n _2, and a smooth and light-transmissive area is provided on the leading end side in the direction of conveyance relative to the roughened resin coat layer. , N ₂ / n ₃ ≧ 0.8, where n ₃ is the light transmittance of this region
It is preferable to satisfy the following equation.

According to another aspect of the present invention, the powder toner images of different colors sequentially formed on the image carrier are sequentially superposed on the transfer medium carried on the transfer medium carrier. A transfer device for transferring, wherein the transfer material carrier has an elastic layer made of rubber or resin foam provided on a conductive cylindrical body, and a dielectric layer further provided thereon, Forming a color image having an attraction roller for electrostatically adsorbing the transfer material on the transfer material carrier, and a neutralizing roller for neutralizing the transfer material carrier after the transfer material is separated from the transfer material carrier. An OHP sheet for a color image forming apparatus, characterized in that an OHP film used in the apparatus has a transparent low melting point coating layer on the toner supporting surface side, and the coating layer is convexly curved. .

[0025]

The OHP film for color images according to the present invention will be described below in more detail with reference to the drawings.

First, an example of a color image forming apparatus using an OHP film will be described with reference to FIGS.

FIG. 4 is a vertical cross-sectional view showing a color image forming apparatus. As shown in the drawing, a photosensitive drum 1 as an image carrier is provided in the apparatus, and the photosensitive drum 1 is surrounded by a roller charger. A primary charging device 3, a rotary developing device 4 having a plurality of developing devices, a transfer device 10A, and a cleaner 26 are installed. A laser diode 11, which constitutes an exposure device, a polygon mirror 13 rotated by a high-speed motor 12, a lens 14, and a folding mirror 15 are arranged above the photosensitive drum 1.

The photosensitive drum 1 comprises an aluminum cylinder having a diameter of 40 mm and a photoconductor made of an organic photoconductor (OPC) applied on the outer peripheral surface thereof. The photoconductor may be amorphous Si, CdS, Se or the like. The photosensitive drum 1 is rotated in the direction of the arrow shown by the driving means (not shown) at a peripheral speed of 100 mm / sec.

The developing device 4 is provided with a support 9 which rotates around a rotation shaft 9a at the center thereof, and the yellow developing device 4a, the magenta developing device 4b, the cyan developing device 4c and the black developing device which are held by the support 9 are provided. It is composed of 4d. The developing devices 4a, 4b, 4c, and 4d contain yellow toner, magenta toner, cyan toner, and black toner, which are one-component developers, respectively.

In each of the developing devices 4a, 4b, 4c and 4d,
As shown in FIG. 5, the opening surfaces 5a, 5b, 5c, 5d
Developing sleeve 8a as a developer carrying member,
8b, 8c and 8d are installed. Further, each developing device 4
a, 4b, 4c and 4d have coating rollers 6a, 6b and 6
c, 6d, and toner regulating members 7a, 7b, 7c, 7d
Is installed. Developing sleeves 8a, 8b, 8c, 8
With the rotation of d, the toner is applied onto the developing sleeves 8a, 8b, 8c, 8d by the application rollers 6a, 6b, 6c, 6d, and the toner applied by the toner regulating members 7a, 7b, 7c, 7d is regulated. The triboelectric charge is applied to the toner and the developing sleeves 8a, 8b, 8c,
A toner layer is formed on 8d. This toner regulating member 7
Materials a, 7b, 7c and 7d are preferably charged opposite to the charging polarity of the toner, such as nylon when the toner is negatively charged and silicone rubber when the toner is positively charged. .

Developing sleeves 8a to 8d of the developing devices 4a to 4d, respectively.
The peripheral speed of 8d is 1.0 to the peripheral speed ratio with respect to the photosensitive drum 1.
It is preferable to select it so that the range is 2.0 times.
When the developing devices 4a to 4d face the photosensitive drum 1, the developing devices 4a to 4d are driven so that their opening surfaces 5a to 5d always face the photosensitive drum 1. Details of the driving method of these developing devices 4a to 4d are as described in JP-A-50-93437.

The transfer device 10A is provided with a transfer drum 10 as a transfer material carrier, and around the transfer drum 10, a suction roller 23, a discharging charger 2, a separating claw 24, a cleaner 27 and a discharging roller 28 are arranged. There is. Transfer drum 10
The gripper 2 of the transfer material gripping member at one place on the outer peripheral surface thereof.
Have two. The transfer drum 10 is rotated in the arrow direction at substantially the same speed as the photosensitive drum 1 by a driving unit (not shown). An elastic body 10b is wound on the metal cylinder 10a, and a PVdF sheet (polyvinylidene fluoride sheet) 10c is wound on the elastic body 10b.

In the color image forming apparatus having the above structure, first, a DC voltage of -700 V is applied to the primary charger 3 at a frequency of 700 Hz and Vpp (peak-to-peak voltage) -15.
A voltage obtained by superimposing an AC voltage of 00V is applied, and the surface of the photosensitive drum 1 is primarily charged by the primary charger 3 to about -700V. Next, a signal according to the image pattern of the first color, for example, yellow is input to the laser diode 11 to generate light of the image pattern of yellow, and the photosensitive drum 1 is irradiated through the optical path 16 to be exposed to light. An electrostatic latent image having a yellow image pattern with a light irradiation portion of approximately -100V is formed on the surface of 1. The electrostatic latent image of the yellow image pattern formed on the photosensitive drum 1 is a developing unit facing the developing device 4 as the photosensitive drum 1 rotates, and the yellow developing device 4 located there.
After being developed by a, a first color yellow toner image is formed on the photosensitive drum 1.

On the other hand, the transfer material is supplied from the transfer material cassette 17 to the transfer drum 10 of the transfer device 10A by the pickup roller 18 in synchronization with the image on the photosensitive drum 1. The transfer drum 10 transfers the supplied transfer material to the gripper 2
The photosensitive drum 1 is gripped and rotated by
The image is transferred to the image transfer section opposite to. The transfer material conveyed to the image transfer unit forms a yellow toner image on the photosensitive drum 1 by a transfer voltage applied between the transfer drum 10 and the photosensitive drum 1 via a substrate of the transfer drum 10 by a power source (not shown). Transcribed.

At the same time as this transfer, charges are injected into the transfer material by the transfer voltage, and the transfer material is electrostatically adsorbed and held on the surface of the transfer drum 10. In order to enhance the electrostatic attraction of the transfer material to the transfer drum 10, the attraction roller 23 is installed near the transfer material feeding portion of the transfer drum 10 and a voltage for attraction is applied to the gripper. In many cases, the transfer material is electrostatically adsorbed in advance after being gripped by 22.

After the transfer of the yellow toner image is completed, the photosensitive drum 1 is cleaned by a cleaning member such as a fur brush or a blade installed on the cleaner 26 to remove the residual toner on the surface thereof, and then the primary charging by the primary charger 3 is performed. Image forming operation is performed.

Primary charging of the photosensitive drum 1 as described above, formation of an electrostatic latent image by exposure, formation of a toner image by development of the electrostatic latent image, superposition transfer of the obtained toner image onto a transfer material. Is also performed for the magenta, cyan, and black of the second and subsequent colors, a color image in which four color toner images of yellow, magenta, cyan, and black are superimposed and transferred on the transfer material can be obtained.

The transfer material on which the four color toner images have been transferred is then discharged by the discharging charger 2 arranged around the transfer drum 10, and then separated from the transfer drum 10 by the separating claw 24 on the downstream side. And is sent to the fixing device 25. Then, the toner images of four colors are fixed there by heating and pressurizing, the toner images are mixed and fixed to the transfer material, and a full-color permanent image is formed. Then, the toner images are discharged outside the image forming apparatus. Preferably, the residual toner on the surface of the transfer drum 10 from which the transfer material has been peeled off is cleaned by a cleaner 27 having a cleaning member such as a fur brush or a web.

Next, the color fixing device of this embodiment will be described. As shown in FIG. 6, the color fixing device 25 has a fixing roller 37 and rotates in pressure contact with a pressure roller 38. The heating required for fixing is applied by the halogen heaters 39 and 39 'inside each roller, and the roller temperature is detected by the resistance value change of the thermistor (not shown) in contact with the roller surface or the core metal member to perform temperature control. . The silicone oil in the oil tank 43 is applied to the surface of the fixing roller 37 by contact with the surface of the fixing roller 37 after being regulated by the blade 42 on the application roller 40 via the scooping roller 41.

The unfixed transfer material enters the nip portion of both rollers from the right side in the figure as shown by the dotted arrow, and is pressed and heated by the surface of the fixing roller 37 on which the smooth oil layer is formed and fixed. Will be ejected. The fixed surface is rubbed by a cleaning web 44, which is a nonwoven fabric fiber impregnated with oil, by rotation to remove the offset toner, and then oil is applied again.

The fixing roller 37 has a structure in which an elastic layer of several tens of μm or more is provided on the core shaft of aluminum or the like in order to correspond to the thickness (several to several tens of μm) of the multicolor toner of the color image of one to four colors. is necessary. If the elasticity is low, unfixed portions of the toner may not be fixed or the toner may be crushed, resulting in a decrease in resolution. The material of the elastic layer is phenyl type, dimethyl type RTV, L
TV type liquid silicone rubber has elasticity,
In particular, the RTV type is more suitable because it has a high affinity with silicone rubber oil and is easy to apply oil. RTV and LTV type are used for the surface layer, and the lower layer is HT that is strong against heat
A V type may be provided to provide a multilayer structure in which thermal deterioration and peeling of the front surface and back surface are prevented. In addition, PF of several tens of μm on the surface
A, PTFE coated tube may be provided.

Since the structure of the pressure roller 38 may be less elastic than that of the fixing roller 37, it can be simplified and only HTV silicon rubber, fluororubber or the like may be provided on the aluminum core shaft, and PFA coating or the like may be performed on the surface to form an oil. It may be swell-prevented.

Among the silicone rubber oils, dimethyl oils are generally used at present, and for example, KF-96 manufactured by Shin-Etsu Chemical Co., Ltd. is well known. Regarding the viscosity of the oil, those having a viscosity of tens of thousands cs or less can be used, but those having a viscosity of several thousand cs or less are preferable. Tens of cs
The following items have high volatility, easily contaminate the charging wire inside the machine, and have a low flash point.
s or more is preferable.

In this embodiment, the surface of the fixing roller is set to RT.
V type, and the pressure roller surface layer was LTV type.
Further, the toner is a sharp melt toner used in a color copying machine CLC-200 manufactured by Canon. The fixing temperature was 120 to 180 ° C. and the ripple was within ± 3 ° C., and the roller peripheral speed was 10 to 120 mm / sec. The oil used is 300 cs for KF-96 and 20 for KF-53.
0 cs or 400 cs of KF-54 was used.

Example 1 Next, a first example of the OHP film for a color image according to the present invention, which can be suitably used in the color image forming apparatus having the above-described structure, will be described.

FIG. 1 is an explanatory view showing an OHP film (transfer material for overhead projector) in this embodiment, FIG. 2 is an explanatory view showing a side surface of the OHP film, and FIG. 3 is an enlarged view thereof.

The OHP film 60 in this embodiment is formed by coating a PET film (polyethylene terephthalate film) layer 61 as a base material layer with a polyethylene resin 62 as an upper layer, and the thickness t of the PET film 61 is t.
₁ = 100 μm, thickness t _{2 of} polyethylene resin 62 = 1
It is 0 μm.

Further, the hatched portion in FIG. 1 is a state in which the surface of the resin coating layer 62 has irregularities as shown in FIG. 3, and the transparent area 63 necessary for document detection is a non-image. Within the region, it is provided at a position of w ₁ = 2 mm to w ₂ = 7 mm inside the front end of the OHP film 60 in the transport direction. The surface roughness of the uneven portion is Rz = 3 to 3.5 μm.
m, the surface roughness of the transparent region is Rz ≦ 0.5 μm.

The electric resistance value of the resin side surface is 1 × 10.
It was about ^{10 to} 5 × 10 ¹⁰ Ω (measured by applying 500 V). Also, the electric resistance value on the back surface is 1 × 10 ¹¹ to 1 × 10 ¹⁴ Ω.
Met.

Further, the OHP film 6 in this embodiment is
As shown in FIG. 2, when the resin 62 is placed on an appropriate horizontal base 80 with the resin 62 on the lower side, the amount of so-called curl (bending) of the end portion is lifted from the horizontal base 70 is h = 3 to 7 mm
It was about.

In the color image forming apparatus shown in FIG. 4, the above-mentioned OHP film was coated with toner having an average particle diameter of 8 μm.
When printed in full color, in an environment of temperature and humidity of 25 ° C. and 40%, the suction bias applied to the suction roller 23 is −1000 V, the transfer bias is 1000 V for the first color (magenta), and 1100 V for the second color (cyan). Three
The color (yellow) is applied at 1200V and the color (black) is applied at 1300V. While the transfer bias is sequentially applied for each color, the OHP film is wound around the transfer drum 10, and the rear end of the OHP film is transferred to the transfer drum 10. It is possible to transfer a clear image without floating from above and contacting peripheral members.

After the transfer is completed, the gripper 22 holding the OHP film is released, and at the same time, the tip of the separation claw 24 descends downward and the OHP film is conveyed to the fixing device 25 by hooking the tip of the OHP film. Fixing condition is 1
The temperature is controlled at 50 to 200 ° C, and OH is applied during fixing.
The surface uneven resin portion of the P film and the toner are melted to be uniformly smooth and transparent.

In the OHP film of this embodiment, as shown in FIG. 3, the thickness t ₂ of the resin coat layer 62 before roughening treatment is applied.
(Dashed line part) was 10 μm, and the surface roughness (hatched part) of the resin coating layer after the surface roughening treatment was Rz = 3 to 3.5 μm. When the resin coat layer 62 is roughened, if Rz is too large, that is, if Rz is too large, it does not become sufficiently smooth even after fixing and unevenness remains, so when the OHP film is viewed with OHP, light is scattered and it looks dark. PET film (base resin film)
May be scratched. Therefore, it is preferable that Rz is 80% or less with respect to the thickness t ₂ of the resin coat layer, that is, Rz ≦ 0.8t ... (2) As a result of studies by the present inventors, it was confirmed that a uniform and clear image can be obtained with respect to influence and light transmittance after fixing.

As a condition for roughening the resin coat layer of the OHP film, in order to obtain a clear image, the relationship with the toner particle size is important. When the present inventors conducted a study on the relationship between the two, the study results shown in the graph of FIG. 7 were obtained. If the surface roughness Rz of the resin coat layer is too small with respect to half the toner particle diameter a, the effect of roughening the surface of the resin coat layer is lost, and it is almost the same as the smooth resin coat surface before roughening treatment, The hollows become noticeable.

In the case of this embodiment, a toner having a particle diameter of 8 μm and a resin surface roughness Rz = 2 μm produced a clear image with almost no voids, but a rough surface at Rz = 1.5 μm. The effect of the treatment has disappeared to an extreme extent, and the hollowed-out image becomes noticeable.

For a toner having a particle size of 8 μm, O
When the resin-coated surface of the HP film is further roughened, fine lines are disturbed, and linearity cannot be obtained. For example, Rz =
In the case of 4 μm, a clear image can be obtained without any voids, but in the case of Rz = 5 μm, the voids are few but the linearity of the fine lines is lost and a clear image cannot be obtained.

As a result of examining the relationship between the toner particle diameter a and the roughness Rz at the time of the rough surface treatment of the resin coating layer as described above, a clear image without a hollow image can be obtained by satisfying the following conditions. It was found that

0.125 × (a + 6) ≦ Rz ≦ a / 2 (1) As described above, the relationship between the thickness t of the resin coating layer, the roughness Rz of the resin surface thereof, and the toner particle diameter a. , Rz ≦ 0.8
t and 0.125 × (a + 6) ≦ Rz ≦ a / 2 are set so that the PET layer is not adversely affected, and the light transmittance after fixing is uniform and hollow. A clear image can be obtained.

Example 2 In this example, the OHP film has a thickness t ₁ = 10.
0 μm PET layer 61 and t ₂ = 6 μm resin coat layer 6
2 was used, and the amount of resin was reduced as compared with Example 1 to reduce the cost. The surface roughness of the resin coat layer 62 was set to Rz = 3 to 3.5 μm. In this embodiment, the toner particle size is 8 μm on average, and the surface roughness Rz is preferably half or less of the toner particle size in order to prevent hollow defects.
It is preferable that Rz ≦ 4 μm and Rz be 80% or less of the resin layer thickness. This is shown in a graph in FIG. 8, and the shaded area in the drawing is the proper region.

Also, as in Example 1, when the OHP film was placed on a horizontal table, the end of the OHP film was h = 3.
It is curled so that it floats up to about 7 mm. As a result, the resin side has a convex shape and is easily wound around the transfer drum.

Further, as in the case of Example 1, a non-image area at the tip was provided with a partially smooth and 90% or more light transmitting region as the OHP film detecting portion. still,
Since the OHP film has a roughened surface with irregularities formed in a region from the tip to 2 mm, it is apt to bite due to contact with the feeding roller or the registration roller during feeding.
There is no problem in terms of transportability.

In this embodiment, by making the thickness of the resin coating layer smaller than that of the first embodiment, the amount of resin can be reduced and the cost can be reduced.
When an image was formed under the fixing conditions, it was possible to obtain a clear image with no voids.

Example 3 In addition to the above examples, the inventors of the present invention seek a condition that a clear image can be obtained without causing voids, and the relationship between the toner particle diameter a and the surface roughness Rz of the OHP film resin layer. Was further studied.

First, the above-mentioned color image forming apparatus was examined using toner particles having an average toner particle diameter of 10 μm. As a result, as shown in the graph of FIG. 7, it is appropriate that the OHP film resin surface roughness Rz is 5 μm or less.
It was found that when ≧ 6, the unevenness on the surface of the OHP film was too large to cause hollowing, but the linearity of thin lines was lost, resulting in a doglegged line. When the surface of the OHP film is Rz ≦ 1.5 μm, the particle size is 1
For the toner of 0 μm, the unevenness of the OHP film is weakened, and hollow defects occur. Therefore, the average particle size is 10
With toner particles of μm, the surface roughness Rz of the OHP film is
The proper range of was 2 ≦ Rz ≦ 5 μm.

Similarly, in a toner having an average particle size of 6 μm, hollow defects occur when the surface roughness of the OHP film is Rz ≦ 1 μm, and when Rz ≦ 4 μm, fine lines are disturbed and the average particle size is 6 μm.
In the toner of No. 3, the appropriate range of the OHP film Rz was 1.5 ≦ Rz ≦ 3 μm.

As a matter of course, the OHP film used in this construction has a part of the non-image area smooth and transparent as shown in FIG. 1 in order to improve the transportability and the winding property with the transfer drum. Further, as shown in FIG. 2, the curl is provided so that the resin surface side is convex.

As described above, by setting the roughness of the surface of the resin coat layer of the OHP film to an appropriate range with respect to the average particle diameter of the toner, it was possible to obtain a clear image with no voids. .

Example 4 As described in Examples 1 to 3, by properly roughening the resin-coated surface of the OHP film, a clear image with no voids can be obtained. This rough surface treatment is used. By doing O
It becomes possible to detect an original as an HP film.

In the OHP film of this example, the thickness of the resin layer before the roughening treatment was t = 6 μm, the surface roughness of the resin layer after the roughening treatment was Rz = 3 μm, and the toner of the toner used was When the average particle size is set to a = 8 μm, as shown in FIG. 1, the non-image area at the leading end is made smooth in the document conveying direction, and a portion not subjected to roughening treatment is formed to transmit infrared rays. When the rate was measured, it was found that the light transmittance n ₃ = 95% in the portion not subjected to the rough surface treatment and the light transmittance n ₁ = 50% in the portion subjected to the rough surface treatment. When the sensor using infrared light used in this example was examined, it was possible to sufficiently detect as an OHP film if the relationship of n ₁ / n ₃ ≦ 0.7 (3) was satisfied. In this embodiment, n ₁ / n
₃ = 50 / 95≈0.53.

FIG. 9 shows the OH measured in this example.
It is a graph which shows the surface roughness Rz at the time of performing the roughening process of P film, and the relationship of light transmittance.

When Rz = _{1 to} 7 μm when the surface is roughened, the light transmittance is n ₁ = 45 to 60%,
PET with a thickness of 100 μm without roughening
When the film was coated with a polyester resin having a thickness of 10 μm, the light transmittance was n ₃ = 90%.

It is possible to recognize that the film is an OHP film with a contrast of n ₁ = 45-60% and n ₃ = 90%, and in this embodiment, n ₁ / n ₃ ≦ It becomes possible to detect by setting to 0.7.

As described above, according to the present embodiment, it is possible to easily distinguish from plain paper by using a general optical sensor, and in this case, the front end of the OHP film in the conveying direction is roughened. By having such a portion, it is possible to stably carry the sheet.

Example 5 In the present invention, as described in Examples 1 to 4, since the resin coat layer itself of the OHP film has irregularities, this resin layer is melted during fixing and rough surface is formed. It becomes possible to return to a smooth surface before processing. The value of the surface roughness Rz and the temperature at the time of fixing (150 ° C. to 20 ° C. in this embodiment).
Performed at 0 ° C. ) Causes a slight difference in smoothness, but after fixing, the OHP film becomes entirely smooth,
There is an effect that it is possible to make the original detection unit, which is not subjected to the rough surface treatment before fixing, inconspicuous.

When the light transmittance of the surface subjected to the roughening treatment after fixing is n ₂ and the light transmittance of the portion not subjected to the roughening treatment is n ₃ , n ₂ / n ₃ ≧ 0.8 By satisfying the relationship of (4), it is possible to make the difference between the original detection portion (without rough surface processing) and the rough surface processed portion at the leading edge of the non-image area uniform so that it cannot be visually identified. This makes it possible to obtain an OHP film having high product value.

[0076]

As is apparent from the above description, the OHP film for color images according to the present invention has a base material layer and a resin coat layer provided thereon, and is used in a color image forming apparatus. When the average particle diameter of the toner is a, the thickness of the resin coating layer supporting the toner before roughening treatment is t, and the roughness of the roughened image forming area of the resin coating layer is Rz, 0 .125 × (a + 6) ≦ Rz ≦ a / 2, Rz
By virtue of the constitution that both expressions of ≦ 0.8 t are satisfied at the same time, it is possible to obtain a clear image having no adverse effect on the base material layer and uniform in light transmittance after fixing and having no voids. . Also, by providing a region resin that is smooth and has good light transmittance on the leading end side in the transported direction from the resin coating layer that has been subjected to the rough surface treatment, it becomes possible to easily detect the original document that is distinguished from plain paper. It was Further, since the uneven surface is evenly smoothed after fixing, there is an effect that a clear image having no difference in light transmittance between the document detecting portion and the printing portion can be obtained.

Further, according to another aspect, a transparent low melting point coating layer is provided on the toner supporting surface side, and the coating layer is convexly curved. It also clings well to the rollers, improving the transportability and making it less likely to cause jams.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of an OHP film for color images according to the present invention.

FIG. 2 is an explanatory view showing a side surface of the OHP film for color image of FIG.

FIG. 3 is an enlarged view of the OHP film for color image of FIG.

FIG. 4 is a configuration diagram showing an example of a color image forming apparatus in which the OHP film for color images according to the present invention is preferably used.

5 is a configuration diagram showing a developing device of the color image forming apparatus of FIG.

6 is a configuration diagram showing a fixing device of the color image forming apparatus of FIG.

FIG. 7 is a graph showing a relationship between an OHP film and an average toner particle diameter regarding an image state.

FIG. 8 is a graph showing the relationship between the thickness of the resin coating film and the surface roughness.

FIG. 9 is a graph showing the relationship between the surface roughness of the resin layer and the light transmittance.

FIG. 10 is a perspective view showing a solid transfer drum.

FIG. 11 is a perspective view showing a notch type transfer drum.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 10 Transfer material carrier 10A Transfer device 60 OHP film 61 Resin coat layer 62 PET layer (base material layer) 63 Area with high light transmittance

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takao Kume 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Toshiaki Miyashiro 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Takehiko Suzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Nobuaki Kaburaya 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (4)

[Claims] 1. A color image forming apparatus, which is an OHP film for contact-transferring toner images of different colors formed on an image carrier by a transfer device, the base layer and a resin coat layer provided thereon. The average particle diameter of the toner used in the color image forming apparatus is a, the thickness of the resin coating layer supporting the toner before roughening treatment is t, and the roughening treatment of the resin coating layer is performed. When the roughness of the formed image forming area is represented by Rz, 0.125 × (a + 6) ≦ Rz ≦ a / 2 and Rz ≦ 0.8t are both satisfied at the same time. 2. The light transmittance of the resin coat layer subjected to the surface roughening treatment before fixing is n _1, and the light is smoother and lighter than the resin coat layer subjected to the surface roughening treatment on the leading end side in the transported direction. The OHP film according to claim 1, wherein a region having good transparency is provided, and when the light transmittance of this region is n ₃ , the formula of n ₁ / n ₃ ≦ 0.7 is satisfied. 3. The light transmittance of the surface subjected to the roughening treatment after fixing is n _2, and a region having a smooth and good light transmittance is provided on the leading end side in the direction to be conveyed as compared with the coating layer subjected to the roughening treatment. _3. The OH according to claim 1 or 2, characterized in that, when the light transmittance of this region is set to n ₃ , the formula of n ₂ / n ₃ ≧ 0.8 is satisfied.
P film. 4. A transfer device is provided, which transfers, onto a transfer material carried on a transfer material carrying body, powder toner images of different colors sequentially formed on the image carrying body in an overlapping manner. The transfer material carrier has an elastic layer made of a foamed material of rubber or resin provided on a conductive cylindrical body, and a dielectric layer further provided thereon, and the transfer material is provided on the transfer material carrier. In an OHP film used in a color image forming apparatus, which has an attraction roller for electrostatically attracting and a charge eliminating roller for eliminating charge of the transfer material carrier after the transfer material is separated from the transfer material carrier. An OHP film for a color image forming apparatus, comprising a transparent low melting point coating layer on the toner supporting surface side, and the coating layer is convexly curved.