JP3071996B2 - OHP film for color images - Google Patents

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 for an overhead projector (OHP), and more particularly to an OHP film suitably 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 process of forming a toner image on an image carrier by charging, exposing, and developing and transferring the toner image onto a transfer material every time a toner image is obtained is repeated for different processes. There is one method of obtaining a color image by superposing a plurality of color toner images on a transfer material.

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

[0004] A transparent sheet for an overhead projector (hereinafter referred to as an OHP), that is, an OHP film, is often used as one of the transfer materials in, for example, a color copying machine of this type. O
A color image formed on an HP film requires a high degree of light transmittance in order to project a color image with high sharpness on a screen. As a large-sized OHP usually used for a large conference, a large-volume, direct-transmission OHP is used. or,
In recent years, small transflective OHPs have been used for meetings of small numbers of people. However, since the same small amount of light passes through the OHP film twice, the sharpness of the original OHP film image with low transparency is low. There is a tendency that the projected image becomes much lower than that of the large-sized one, and the image quality defect of the original image remarkably appears.

Therefore, in order to always provide high-quality color projection images regardless of the types of OHP films on the market, it is necessary to enhance the sharpness, resolution and light transmittance of OHP film images as much as possible. To this end, of course, the fixing efficiency of the color image forming process is increased, but on the other hand, there is a large difference in image quality, especially in transparency and sharpness, depending on the configuration of the OHP film itself. is necessary.

It has been known that an OHP film for a color image having the following structure has good image quality. That is, about 10 μm as an upper layer on a PET (polyethylene terephthalate) layer having a thickness of about 100 μm as a base layer.
The transparent resin coating layer has a thickness of about m or slightly lower than or slightly lower than that of the toner binder resin with respect to the toner binder resin.

The two-layer OHP film has the following effects. Since the transparent resin coat layer softens and melts at the same time as the toner melts during fixing, a toner having an average particle size of about 7 to 8 μm is embedded in the transparent resin coat layer. For this reason, the collapse of fine lines due to pressure is eliminated, and a high-resolution color fixed image can be obtained. In addition, after fixing, even in a four-color superimposed color image in which the toner thickness varies from a solid density different in toner density to a halftone area in the image, unevenness on the surface is embedded in the transparent resin coat layer because the toner is embedded in the image. The portion becomes gentle and becomes smooth following the surface of the fixing roller. Therefore, loss of light scattering due to unevenness of the surface with respect to transmitted light is eliminated, and a color projection image with high transmittance can be obtained. If the surface has irregularities, a shadow contour may be generated and an extremely unsightly image may be obtained.

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

In the image forming apparatus, plain paper and OH
The fixing condition is different from that of the P film, and the heat capacity of the OHP film is larger than that of the paper because it is formed of a plastic resin film. It is necessary to take measures such as increasing the paper speed or reducing the transport speed of the OHP film. Therefore, the paper or the OHP film is detected by an optical sensor provided in the transfer material feeding path. The conventional OHP film is made of resin and film with good transparency, and printed at the tip for OHP film detection to create 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 detect the transmission of light and recognize that the film is an OHP film.
In the case of paper, it is recognized that the paper is paper because light does not pass through the paper while passing through the optical sensor.

[0010]

As a result of output from an OHP film of the above-mentioned conventional type using a color printer experimental machine, a phenomenon called a so-called "missing" occurs, and toner is partially missing. This state was particularly observed in character images and fine line images. This phenomenon is caused by the toner portion that is thickly overlapped when performing multi-color transfer from the photosensitive drum to the OHP film on the transfer drum, especially when the high-resolution character pattern in the image pattern is output, the toner at the center of the character pattern Are not transferred and are lost, resulting in a blank state.

On the transfer drum, a solid transfer member 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. Drum 10 and cylindrical support member 72 as shown in FIG.
Is provided with a transfer drum 70 having a so-called notch structure in which a PVdF sheet 71 is wound around the notch.

[0012] The solid transfer drum can be simplified in its inside as compared with a transfer drum having a notch structure, so that the cost can be reduced. In addition, since a flexible PVdF sheet is supported from the inside, a notch type transfer drum is used. There is an advantage that deformation and breakage of the sheet, which is a drawback of the above, 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 the notch type is 10 or less, while the surface hardness of the solid transfer drum is over 80, as measured by an Asker hardness meter F manufactured by Kobunshi Keiki Co., Ltd. Show. It is considered that the harder the transfer drum surface is, the more likely it is
At the nip portion between the photosensitive drum and the transfer drum, pressure is applied to the toner more strongly. When the toner is crushed and separated from the nip portion, the chemical affinity between the toner and the photosensitive drum causes the transfer drum (the OHP film surface) and the toner It is considered that this is because the amount of toner on the surface of the transfer material is reduced because the toner is carried to the photosensitive drum side from the surface of the transfer material because the toner works more strongly than the affinity between the two.

In order to prevent a hollow phenomenon occurring in an OHP film used in a color image forming apparatus having a solid transfer drum, a resin portion on a surface (to which toner is transferred) of the OHP film in contact with the photosensitive drum is roughened. However, since the surface roughness of the OHP film becomes rough, the light transmittance before fixing decreases, and as a result, it becomes difficult to distinguish the OHP film from 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 an optical sensor before the fixing. However, as described above, the surface roughness of the OHP film is roughened. The OHP film may be erroneously recognized as plain paper, and as a result, the same fixing conditions as the plain paper may not be obtained, so that the toner on the OHP film may not be sufficiently heated, and the color mixing property, the transparency and the gloss In some cases, images were insufficient.

Further, for example, the surface roughness of an OHP film is defined as Rz
There is a drawback that an expensive optical sensor requiring accuracy is required when discriminating between the light transmittance when coarsened to 3 to 5 μm and the light transmittance when paper is used.

In order to solve such disadvantages, OHP
By forming a transparent portion, that is, a smooth surface, at the leading end of the film, a difference in light transmittance from that of plain paper is caused.
The film can be detected accurately, but in this case, the leading edge is smooth in the initial stage of paper feeding, so the paper feeding roller and the surface are slippery, resulting in poor paper feeding. was there.

Accordingly, a main object of the present invention is to provide a color image O which can obtain a clear color image without any voids.
To provide an HP film.

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

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

[0021]

The above object is achieved by the OHP film for color images according to the present invention. In summary, the present invention relates to an OHP film for contact-transferring toner images of different colors formed on an image carrier by a transfer device in a color image forming apparatus, provided with a base layer and provided thereon. A, 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 is t, The roughness of the image forming area subjected to the rough surface treatment is represented by R
When z, 0.125 × (a + 6) ≦ Rz ≦ a /
2. An OHP film characterized by simultaneously satisfying both formulas of Rz ≦ 0.8t.

The light transmittance before fixing of the surface-treated resin coat layer is defined as n _1, and the light-transmittance is smoother and light-transmissive on the leading end side in the transported direction than the surface-treated resin coat layer. Assuming that a good region is provided and the light transmittance of this region is n ₃ , it is preferable to satisfy the following expression: n ₁ / n ₃ ≦ 0.7.

The light transmittance of the roughened surface after fixing is set to n _2, and a smoother and more light-transmissive region is provided on the leading end side in the transported direction with respect to the resin coat layer subjected to the roughened surface. When the light transmittance of this area is n ₃ , n ₂ / n ₃ ≧ 0.8
It is preferable to satisfy the following expression.

[0024]

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the OHP film for a color image according to the present invention will be described 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 longitudinal sectional view showing a color image forming apparatus. As shown, a photosensitive drum 1 as an image carrier is provided in the apparatus, and a roller charger is provided around the photosensitive drum 1. 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 provided. Above the photosensitive drum 1, a laser diode 11 constituting an exposure device, a polygon mirror 13 rotated by a high-speed motor 12, a lens 14, and a folding mirror 15 are arranged.

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

The developing device 4 has a support 9 which rotates around a central rotation axis 9a. The developing device 4 includes a yellow developing device 4a, a magenta developing device 4b, a cyan developing device 4c, and a black developing device held by the support 9. 4d. The developing devices 4a, 4b, 4c, and 4d contain a one-component developer of yellow toner, magenta toner, cyan toner, and black toner, respectively.

In each of the developing devices 4a, 4b, 4c and 4d,
As shown in FIG. 5, the opening surfaces 5a, 5b, 5c, 5d
, A developing sleeve 8a as a developer carrier,
8b, 8c and 8d are provided. Furthermore, each developing unit 4
a, 4b, 4c, 4d, the application rollers 6a, 6b, 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 and 8d by the application rollers 6a, 6b, 6c and 6d, and the applied toner is regulated by the toner regulating members 7a, 7b, 7c and 7d. As a result, a 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
a, 7b, 7c and 7d are preferably materials that are charged in the opposite direction to the charge polarity of the toner, such as nylon when the toner is negatively charged, and silicone rubber or the like when the toner is positively charged. .

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

The transfer device 10A includes a transfer drum 10 as a transfer material carrier. Around the transfer drum 10, an attraction roller 23, a static eliminator 2, a separation claw 24, a cleaner 27, and a static elimination roller 28 are disposed. I have. Transfer drum 10
A gripper 2 of a transfer material gripping member
Two. The transfer drum 10 is rotated in a direction indicated by an arrow at substantially the same speed as the photosensitive drum 1 by a driving unit (not shown). An elastic body 10b is wound on a metal cylinder 10a, and a PVdF sheet (polyvinylidene fluoride sheet) 10c is wound thereon.

In this color image forming apparatus, first, the primary charger 3 is supplied with a DC voltage of -700 V, a frequency of 700 Hz, and a Vpp (peak-to-peak voltage) of -15.
A voltage on which an AC voltage of 00 V is superimposed is applied, and the surface of the photosensitive drum 1 is primarily charged to about −700 V by the primary charger 3. Next, a signal according to the first color, for example, a yellow image pattern is input to the laser diode 11 to generate light of a yellow image pattern, and the light is irradiated to the photosensitive drum 1 through an optical path 16 to expose the photosensitive drum 1. An electrostatic latent image having a yellow image pattern with a light irradiation part of approximately −100 V is formed on the light emitting unit 1. The electrostatic latent image of the yellow image pattern formed on the photosensitive drum 1 is transferred to a developing unit opposed to the developing device 4 with the rotation of the photosensitive drum 1 by a yellow developing unit 4 located there.
a, and 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.
2 to rotate the photosensitive drum 1
Is transported to the image transfer unit facing the. The transfer material conveyed to the image transfer unit causes the yellow toner image on the photosensitive drum 1 to be transferred by a transfer voltage applied between the transfer drum 10 and the photosensitive drum 1 via the base of the transfer drum 10 by a power supply (not shown). Transcribed.

At the same time as the transfer, electric charges are injected into the transfer material by a transfer voltage, and the transfer material is electrostatically attracted 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 gripper is provided by installing the suction roller 23 near the paper supply unit of the transfer material of the transfer drum 10 and applying a voltage for suction. In many cases, the transfer material is electrostatically adsorbed in advance after the holding by the grip 22.

The photosensitive drum 1 on which the transfer of the yellow toner image has been completed is cleaned and removed of residual toner on the surface thereof by a cleaning member such as a fur brush or a blade provided on a cleaner 26, and then is subjected to primary charging by the primary charger 3. Is performed.

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

The transfer material on which the transfer of the toner images of the four colors is completed is then discharged by the discharging charger 2 disposed around the transfer drum 10 and then separated from the transfer drum 10 by the separation claw 24 on the downstream side. To the fixing device 25. Then, the toner images of the four colors are fixed by heating and pressurizing, and the toner images are mixed and fixed to the transfer material, and are then formed into a full-color permanent image, which is then discharged out of the image forming apparatus. Preferably, residual toner on the surface of the transfer drum 10 from which the transfer material has been removed 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. The color fixing device 25 has a fixing roller 37 as shown in FIG. Heat required for fixing is applied by halogen heaters 39 and 39 'inside each roller, and the temperature of the roller is detected by detecting the roller temperature based on a change in the resistance value of a thermistor (not shown) in contact with the surface of the roller or a metal core. . The silicone oil in the oil tank 43 passes through the pumping roller 41, and is applied on the surface of the fixing roller 37 after its application amount is regulated by the blade 42 on the application roller 40.

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

The fixing roller 37 has a structure in which an elastic layer is provided on the core shaft of aluminum or the like to have a thickness of several tens μm or more in order to correspond to the thickness (several to several tens of μm) of the multi-color toner of one to four colors of a color image. is necessary. If the elasticity is low, the resolution is lowered due to the unfixed toner concave portion and the collapse of the toner. The material of the elastic layer is phenyl or dimethyl RTV, L
TV type liquid silicone rubber has elasticity,
In particular, the RTV type is more suitable because it has a high affinity for silicone rubber oil and is easy to apply oil. RTV and LTV types are used for the surface layer, and the lower layer is an HT that is resistant to heat.
A V type may be provided to provide a multilayer structure in which thermal degradation and peeling of the back surface of the surface layer are prevented. Also, a PF of about several tens μm
A, A PTFE coated tube may be provided.

The structure of the pressure roller 38 may be simplified since it may have less elasticity than the fixing roller 37, and only the HTV silicon rubber, the fluorine rubber, or the like may be provided on the aluminum core shaft. A swelling-prevented one may be used.

As the oil, among the silicone rubber oils, a dimethyl-based oil is currently generally used, and for example, KF-96 manufactured by Shin-Etsu Chemical is well known. The viscosity of the oil can be used from those of tens of thousands cs or less, but those of several thousand cs or less are preferable. Tens of cs
The following materials have high volatility, easily pollute the charged wires inside the machine, have a low flash point, and have safety problems.
More than s is preferred.

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

Embodiment 1 Next, a first embodiment of an 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 configuration, will be described.

FIG. 1 is an explanatory view showing an OHP film (transfer material for an 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 obtained by coating a PET film (polyethylene terephthalate film) layer 61 as a base layer with a polyethylene resin 62 as an upper layer.
₁ = 100 μm, thickness t ₂ = 1 of polyethylene resin 62
0 μm.

The shaded portion in FIG. 1 shows a state in which irregularities as shown in FIG. 3 are formed on the surface of the resin coat layer 62, and the transparent area 63 necessary for document detection is a non-image area. Within the region, the OHP film 60 is provided at a position from w ₁ = 2 mm to w ₂ = 7 mm inside the leading end 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 of the resin side surface is 1 × 10
It was about ^{10 to} 5 × 10 ¹⁰ Ω (measured by applying 500 V). The electric resistance of the back surface is 1 × 10 ¹¹ to 1 × 10 ¹⁴ Ω.
Met.

Further, the OHP film 6 in this embodiment is
As can be seen from FIG. 2, when the resin 62 is placed on an appropriate horizontal table 80 with the resin 62 facing down, the so-called curl (curve) amount at which the end rises from the horizontal table 70 is h = 3 to 7mm
It was about.

The above-mentioned OHP film was coated with a toner having an average particle diameter of 8 μm in a color image forming apparatus shown in FIG.
When printing in full color, in an environment of a temperature and humidity of 25 ° C. and 40%, the suction bias applied to the suction roller 23 is −1000 V, and the transfer bias is 1000 V for the first color (magenta) and 1100 V for the second color (cyan). , 3
The OHP film is wrapped around the transfer drum 10 while the transfer bias is applied to each color in the order of 1200 V for the color (yellow) and 1300 V for the color (black). A clear image can be transferred without being lifted up from and coming into contact with peripheral members.

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

As shown in FIG. 3, the OHP film of this embodiment has a thickness t ₂ of the resin coat layer 62 before the rough surface treatment.
(Broken line portion) was 10 μm, and the surface roughness (hatched portion) of the resin coat layer after the rough surface treatment was Rz = 3 to 3.5 μm. When the resin coating layer 62 is roughened, if it is too rough, that is, if Rz is too large, it will not be sufficiently smooth even after fixing and unevenness will remain, so when the OHP film is viewed with OHP, light will be scattered and appear dark. Or PET film (base resin film)
May be damaged. Therefore it is preferable to the Rz with respect to the thickness t ₂ of the resin coat layer to 80% or less, i.e., Rz ≦ 0.8t ... ... (2 ) By roughened to satisfy, to a PET film As a result of the study by the present inventors, it has been confirmed that uniform and clear images can be obtained with respect to the influence and the light transmittance after fixing.

As a condition for roughening the resin coat layer of the OHP film, the relationship with the toner particle diameter is important for obtaining a clear image. The present inventors have studied the relationship between the two, and as a result, a study result as shown in the graph of FIG. 7 has been obtained. If the surface roughness Rz of the resin coat layer is too small with respect to half of 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 the roughening treatment. Hollow holes become noticeable.

In the case of this embodiment, a clear image was obtained with almost no voids by using a toner having a particle diameter of 8 μm and setting the resin surface roughness Rz = 2 μm, but a rough surface was obtained at Rz = 1.5 μm. The effect of the processing was extremely reduced and the voids became noticeable.

For toner having a particle diameter of 8 μm, O
When the resin-coated surface of the HP film is further roughened, particularly thin lines are disturbed, and linearity cannot be obtained. For example, Rz =
In the case of 4 μm, a clear image was obtained without any voids. However, in the case of Rz = 5 μm, the voids were small, but the linearity of the thin line was lost and a clear image could not be obtained.

As described above, 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 was examined, and as a result, a clear image without hollow was obtained when the following conditions were satisfied. Was obtained.

0.125 × (a + 6) ≦ Rz ≦ a / 2 (1) As described above, the relationship between the thickness t of the resin coat layer, the roughness Rz of the resin surface, and the toner particle diameter a is as follows. , Rz ≦ 0.8
By setting both t and 0.125 × (a + 6) ≦ Rz ≦ a / 2, there is no adverse effect on the PET layer and the light transmittance after fixing is uniform and hollow. A clear image with no image can be obtained.

Example 2 In this example, the OHP film had a thickness t ₁ = 10
PET layer 61 of 0 μm and resin coat layer 6 of t ₂ = 6 μm
2, and the cost was reduced by reducing the amount of resin as compared with Example 1. The surface roughness of the resin coat layer 62 was set to Rz = 3 to 3.5 μm. Further, in the present embodiment, the average particle diameter of the toner is 8 μm, and the surface roughness Rz is preferably equal to or less than half of the toner particle diameter in order to prevent hollowing out.
It is preferable that Rz ≦ 4 μm and Rz be 80% or less of the resin layer thickness. FIG. 8 shows this in a graph, and the shaded area in the figure is the appropriate area.

When the OHP film was placed on a horizontal table as in the first embodiment, the end of the OHP film was h = 3.
It is curled so as to float up to about 7 mm. As a result, the resin side becomes convex, and it becomes easy to wind around the transfer drum.

Further, as shown in FIG. 1, a non-image area at the leading end of the OHP film was provided with a partially smooth area through which 90% or more of light was transmitted, as shown in FIG. still,
Since the OHP film has irregularities formed in a region up to 2 mm from the leading end and has a rough surface, when the sheet is fed, the sticking by the contact with the sheet feeding roller and the registration roller is good,
There is no problem in terms of transportability.

In this embodiment, by making the thickness of the resin coat layer smaller than that in the first embodiment, the amount of resin can be reduced to reduce the cost.
When an image was formed under the fixing conditions, a clear image without any voids could be obtained.

Example 3 In addition to the above-mentioned example, the present inventors further determined the relationship between the toner particle diameter a and the surface roughness Rz of the OHP film resin layer in order to determine a condition under which clear images could be obtained without hollowing out. Was further studied.

First, the above 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 surface roughness Rz of the OHP film resin is 5 μm or less.
When ≧ 6, it was found that the OHP film surface had too large irregularities and no hollowing occurred, but there was a drawback that the linearity of the thin line was lost and the line became a U-shaped line. When the surface of the OHP film is Rz ≦ 1.5 μm, the particle size is 1
For the 0 μm toner, the unevenness of the OHP film is weakened, and hollow holes occur. Therefore, the average particle size is 10
For μm toner particles, the surface roughness Rz of the OHP film
Was in the range of 2 ≦ Rz ≦ 5 μm.

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

Of course, in the OHP film used in this configuration, a part of the non-image area is made 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 resin surface is curled so as to be convex.

As described above, by setting the surface roughness of the resin coat layer of the OHP film within an appropriate range with respect to the average particle size of the toner, a clear image without any voids could be obtained. .

Example 4 As described in Examples 1 to 3, by appropriately roughening the resin-coated surface of the OHP film, it is possible to obtain a clear image without any voids. By doing O
It is possible to detect a document as an HP film.

In the OHP film of this embodiment, the thickness of the resin layer before the roughening treatment is t = 6 μm, the surface roughness of the resin layer after the roughening treatment is Rz = 3 μm, the toner When the average particle size is set to a = 8 μm, as shown in FIG. 1, a non-image area at the leading end in the document conveying direction is smoothed to form a portion that is not subjected to surface roughening, and is transmitted by infrared rays. When the rate was measured, the light transmittance n ₃ = 95% at the place where the rough surface treatment was not performed was n ₁ = 50% at the place where the rough surface treatment was performed. Examination with the sensor using infrared light used in this example revealed that if the relationship of n ₁ / n ₃ ≦ 0.7 (3) was satisfied, detection as an OHP film was sufficiently possible. In this embodiment, n ₁ / n
₃ = 50/95 ≒ 0.53.

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

At Rz = _{1 to} 7 μm after the rough surface treatment, n ₁ = 45 to 60% light transmittance was exhibited.
100 μm thick PET without rough surface treatment
When a polyester resin having a thickness of 10 μm was applied to the film, the light transmittance was n ₃ = 90%.

If the contrast is about n ₁ = 45 to 60% and n ₃ = 90%, it can be sufficiently recognized that the film is an OHP film. In this embodiment, n ₁ / n ₃ ≦ By setting the value to 0.7, detection can be performed.

As described above, according to the present embodiment, it is possible to easily discriminate from plain paper by a general optical sensor, and in this case, rough surface treatment is performed on the leading end of the OHP film in the transport direction. By having such a location, it is possible to stably carry.

Example 5 In the present invention, as described in Examples 1 to 4, since the resin coat layer of the OHP film itself has irregularities, the resin layer melts during fixing and has a rough surface. It is 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
Performed at 0 ° C. ) Causes a slight difference in its smoothness, but after fixing, the OHP film becomes entirely smooth,
There is also an effect that the original detection unit that does not perform the rough surface processing before fixing can be made inconspicuous.

Assuming that the light transmittance of the surface subjected to the surface roughening after fixing is n ₂ and the light transmittance of the part not subjected to the surface roughening is n ₃ , n ₂ / n ₃ ≧ 0.8. By satisfying the relationship (4), it is possible to make the difference between the document detection portion (without rough surface processing) at the leading end of the non-image area and the portion subjected to rough surface processing so uniform that it cannot be visually identified. OHP film with high product value can be obtained.

[0076]

As is apparent from the above description, the OHP film for a color image according to the present invention has a base layer and a resin coat layer provided thereon, and is used in a color image forming apparatus. When the average particle size of the toner is a, the thickness of the resin coating layer supporting the toner before the roughening treatment is t, and the roughness of the image-formed area of the resin coating layer after the roughening treatment is Rz, 0 .125 × (a + 6) ≦ Rz ≦ a / 2, Rz
With the configuration satisfying both the formulas of ≦ 0.8t at the same time, it is possible to obtain a clear image without any adverse effect on the base material layer and uniform in light transmittance after fixing without any voids. . In addition, by providing a resin having a smooth and light-transmissive region on the leading end side in the transported direction relative to the resin coat layer subjected to the rough surface treatment, it is possible to easily detect a document which is distinguished from plain paper. Was. Furthermore, since the uneven surface becomes even and smooth after fixing, a clear image having no difference in the light transmittance between the original detecting unit and the printing unit is obtained.

[0077]

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a color image OHP film according to the present invention.

FIG. 2 is an explanatory view showing a side surface of the OHP film for a color image of FIG. 1;

FIG. 3 is an enlarged view of the OHP film for a color image of FIG. 2;

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

FIG. 5 is a configuration diagram illustrating a developing device of the color image forming apparatus of FIG. 4;

FIG. 6 is a configuration diagram illustrating a fixing device of the color image forming apparatus of FIG. 4;

FIG. 7 is a graph showing a relationship between an OHP film and an average toner particle diameter with respect to 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 Region with large light transmittance

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takao Kume 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Toshiaki Miyashiro 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside (72) Inventor Takehiko Suzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Nobuaki Kamiya 3-30-2, Shimomaruko 3-chome, Ota-ku, Tokyo Canon Inc. ( 56) References JP-A-2-230162 (JP, A) JP-A-54-22831 (JP, A) JP-A-57-81270 (JP, A) JP-A-6-19338 (JP, A) JP-A-5-173435 (JP, A) JP-A-5-204263 (JP, A) JP-A-5-134562 (JP, A) JP-A-51-12143 (JP, A) JP-A-62-280874 (JP , A) (58) Fields studied (Int. . ⁷ , DB name) G03G 7/00

Claims (3)

(57) [Claims] 1. An OHP film for contact-transferring toner images of different colors formed on an image carrier by a transfer device in a color image forming apparatus, comprising: a base material layer and a resin coat layer provided thereon. A, 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 the rough surface treatment is t, the rough surface treatment of the resin coat layer is An OHP film characterized by satisfying both the following expressions: Rz ≦ a / 2, Rz ≦ 0.8t, where Rz is the roughness of the formed image forming area. 2. The light transmittance before fixing of the surface-treated resin coat layer is defined as n _1, and the light-transmissivity of the resin coat layer subjected to the surface roughening is smoother and lighter than the surface-treated resin coat layer. 2. The OHP film according to claim 1, wherein an area having good transmittance is provided, and the light transmittance of the area is n ₃ , wherein the following expression is satisfied: n ₁ / n ₃ ≦ 0.7. 3. The light transmittance of the surface having been subjected to the surface roughening after fixing is defined as n _2, and a smoother and light-transmitting region is provided on the leading end side in the transported direction with respect to the coating layer subjected to the surface roughening. The OH according to claim 1 or 2, wherein when the light transmittance of this region is n ₃ , the following formula is satisfied: n ₂ / n ₃ ≧ 0.8.
P film.