JPH08202065A - Electrophotographic resin film - Google Patents

Abstract

PURPOSE: To prevent the abnormal implantation of electric charges to a photosensitive drum at the time of image transfer by providing a film with a difference in properties between its front and rear and specifying the surface specific resistance at the ends of its one surface to a specific value or above. CONSTITUTION: The surface specific resistance at the ends of at least one surface of the film varying in the constitution of its front and rear is >=10<11> Ω/square. The front surface of the heat resistant film 1 which is a base material is a toner receptive layer 2. A resin kneaded with an antistatic agent consisting of a surfactant in such a manner that the surface specific resistance of optimum image forming conditions is attained is applied on this layer. The surface specific resistance is adequately 10<8> to 10<10> Ω/square under the environment of 23 deg.C and 60%. On the other hand, the front surface of the attraction surface 3 is similarly subjected to a resistance treatment. Adequate electrostatic attraction force is not obtainable under a highly moist environment if the surface specific resistance is <=10<8> Ω/square in the environment of 23 deg.C and 60%. The implantation of the electric charges into the photosensitive drum is liable to arise at the film ends between 10<8> to 10<10> Ω/square. Then, the surface specific resistance of >=10<11> Ω/square is necessary as an optimum adjustment value.

Description

Detailed Description of the Invention

[0001]

[Industrial applications]

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic apparatus, a charged resin particle called a toner is used to form an electrostatic latent image on a photoconductor, and the visualized toner image is corona-formed. Using a charger or roller charger, transfer to the final transfer material such as paper or film by the action of an electrostatic field, and heat or pressurize the paper or film after this transfer to fix the toner, and a permanent image Is getting Therefore, in order to form a clear toner image on a transfer material made of a polymer such as a film, it is necessary to apply the electrostatic field uniformly and efficiently. In order to achieve this purpose, the conventionally used film is subjected to appropriate antistatic treatment on its front and back surfaces to prevent partial charge-up. For example, as shown in Japanese Patent Publication No. 51-34734, it is said that a surface resistivity of 10 ⁹ to 10 ¹⁵ is suitable.

Further, this antistatic treatment prevents frictional electrification due to contact with other members before these polymer films are subjected to transfer, and the films are electrostatically charged to be electrostatically charged on the sheet conveying path. In addition, it is effective in preventing the phenomenon that it adheres to other members and causes a jam or the like. The band resistance of this film is set to a surface resistance value for a monochrome monochrome copying machine.

On the other hand, in recent years, a multi-transfer type electrophotographic apparatus has been put into practical use for the purpose of multicolor and full color output. One example is shown in FIG. This device is a photosensitive drum 2.
Necessary developing devices 4Y, 4M, according to the order of image formation
A rotatable body 4a for sequentially applying 4C and 4BK to the image forming area and a transfer material such as the film are wound around the rotatable body 4a and a rotatable transfer drum 8 for sequentially electrostatically transferring a toner image from a photosensitive drum, and It has a charger 3, an image exposure system E, etc. necessary for forming a latent image. When a full-color image is formed in the apparatus 100, the transfer material P drawn from the cassette 101 or the like is conveyed to the transfer drum 8 by a paper feed roller such as 106 or 5, and electrostatically attracted or mechanically attached to the transfer drum 8. Wrap it in any way.
Then, the photosensitive drum 2 is attached to the transfer material P on the transfer drum 8.
Therefore, toner images of a large number of colors are sequentially transferred in accordance with the image forming procedure. The transfer at this time is electrostatically performed by the transfer charger 9. That is, from the inside of the transfer drum 8 made of a dielectric sheet such as PVDF (polyvinylidene fluoride), a charge having a polarity opposite to the charging characteristic of the toner is applied to the back surface of the transfer drum 8 by corona discharge or the like, and is generated by the applied charge. With the electric field, the toner is attracted to the surface of the transfer material on the dielectric sheet to perform the transfer. Next, this transfer is repeated many times for each color toner of yellow (Y), cyan (C), magenta (M), and black (K) to form an image of each color of Y, C, M, and K on the transfer material. Then, by passing this transfer material through the thermal fixing device 16, the toners of the respective colors are melted and mixed to obtain a full-color image.

The transfer material conveying system is provided with transfer material supply trays 101 and 102 which are detachably attached to an opening formed on one side of the apparatus main body 100, and the trays 101 and 10.
Paper feed rollers 103 and 10 disposed substantially directly above
4 and a paper feed guide 4A provided with a paper feed roller 106, which is disposed close to the feed rollers 103 and 104.
And 4B, and are provided close to the paper feed guide 4B,
The contact roller 7, the gripper 6, the transfer material separating charger 12 and the separating claw 14 are arranged in the vicinity of the outer peripheral surface from the upstream side to the downstream side in the rotational direction, and the transfer charger 9 is arranged on the inner peripheral side. 1, a transfer drum 8 which is provided with a transfer material separating charger 13 and is rotatable in the direction of the arrow in FIG. 1, a conveying belt means 15 provided in the vicinity of the separating claw 14, and a conveying belt means 15 Is arranged close to the terminal side of the conveyance direction of
A thermal fixing device 1 that extends outside the apparatus main body 100 and is adjacent to a discharge tray 17 that is detachable from the apparatus main body 100.
It consists of 6 and 6.

The thermal fixing device 16 includes a fixing roller 161 having a heater therein and a pressure roller 1 facing the fixing roller.
62, a releasing agent applying device 163 for applying a releasing agent such as silicon oil to the fixing roller, and a fixing roller cleaning means 164.

The photosensitive drum is destaticized by the destaticizing charger 10 and cleaned by the cleaning means 11.

By the way, when a plastic film having a higher resistance than a paper such as a film is used as a transfer material, in the range of the surface resistance value of the conventional black-and-white film, the uneven charging on the film after the first transfer does not disappear. Not only does it cause transfer unevenness in the second and subsequent times, but also an increase in potential due to film charging called charge-up occurs, making it impossible to transfer a large number of times.

In order to prevent this, the surface resistance of the front and back of the film is 10 ⁶ Ω / □ to 10 in all environments from low humidity to high humidity.
^It should be ¹⁰ Ω / □. If it is less than 10 ⁵ Ω / □, on the contrary, the resistance is too low, and the electric charge applied by the transfer charger is reversed, and the necessary electric field cannot be obtained, and if it is more than 10 ¹¹ Ω / □, the charge up described above occurs. It will be easier.

[0010]

However, when an image is formed in the apparatus as shown in FIG. 1 on the film subjected to the antistatic treatment suitable for the above-mentioned multiple transfer, the image is formed corresponding to the end portion of the film. However, there is a problem that a linear electrostatic image is formed on the surface of the photoconductor. In particular, as in recent digital copying machines, electrophotography of a reversal developing method in which imagewise exposure is performed with a laser beam and a toner image having a charge of the same polarity as the charge polarity is formed on a portion of the photosensitive drum where the charge has been erased. In the device, the charge imparted by transfer charging has a polarity opposite to the charge polarity of the photosensitive drum. Therefore, the linear electrostatic image described above is obtained when the photosensitive drum has a negative charging characteristic.
It has a positive charging characteristic, and becomes a permanent image that cannot be removed by a simple static eliminator.

The problem to be solved by the present invention is the problem of forming a linear electrostatic image on the above-mentioned photoreceptor.

[0012]

DISCLOSURE OF THE INVENTION The present invention relates to an electrophotographic resin film having a toner image formed on the surface thereof, the front surface and the back surface of the resin film having different structures, and at least the surface specific resistance of at least one end of one surface. Is 10 ¹¹ Ω / □ or more, which is a resin film for electrophotography.

The resin film according to the present invention does not cause an abnormal charging phenomenon on the photosensitive drum in an electrophotographic apparatus, particularly an apparatus having a multiple transfer system. The feature of the present invention is that the front and back structures of the resin film are different,
By using at least the surface having the surface resistivity of 10 ¹¹ Ω / □ or more in the environment of 23 ° C. and 60% as the non-transfer surface side, abnormal charging of the photosensitive drum during transfer can be prevented.

[0014]

【Example】

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is an example of the electrophotographic film according to the present invention, which is for transparent OHP projection. 1 is a heat-resistant film that is the base material, and the maximum operating temperature is 100 ° C.
Resins having the above heat resistance, such as polyester, polyimide, polyamide-imide, etc., are used. In particular, polyethylene terephthalate (PET) is preferable because of its wider use range in terms of heat resistance and transparency. The film thickness may be 50 μm or more, preferably 100 μm or more in order to provide heating during fixing and appropriate film transportability for electrophotography, and 200 μm or less for ensuring transparency.

Reference numeral 2 denotes a toner-receiving layer, which is coated with a resin such as polyester, acrylic ester, styrene-acryl and the like, which is kneaded with an antistatic agent such as a surfactant, so that the surface specific resistance under the optimum image forming conditions is obtained. . Alternatively, it is formed by separately applying an antistatic agent on the coated surface of the resin.

The surfactant used as the antistatic agent is most preferably a cationic surfactant such as anionic surfactant of chlorine phosphate, primary amine salt system, quaternary ammonium salt and the like.

The surface resistivity with which the toner receiving layer 2 is adjusted is 23 from the viewpoint of preventing charge leakage and charge-up.
In the environment of 60 ° C., 10 ⁸ to 10 ¹⁰ Ω / □ is preferable, and the amount of the antistatic agent in the coating liquid may be appropriately adjusted in forming the layer. Reference numeral 3 denotes a non-image forming surface on the back surface of the film, which is an adsorption surface 3 as an individual expression in a multi-transfer color copying machine or the like. The surface of the adsorption surface 3 is also subjected to low resistance treatment similarly to the toner receiving layer 2, but when the surface resistivity is less than 10 ⁸ Ω / □ in an environment of 23 ° C. and 60%, it is 10 in a high humidity environment. It will be less than ⁶ Ω / □, and it will not be possible to obtain proper electrostatic adsorption force. Also, 23 ℃ 6
Surface resistivity at 0% is 10 ⁸ Ω / □ to 10 ¹⁰ Ω / □
In between, the transfer electric field from the film attracting surface to the photosensitive drum becomes unequal state.Injection of charges, which is considered to be due to the discharge phenomenon, easily occurs at the edge of the film, and the memory phenomenon described above to the photosensitive drum occurs. Occurs. As an optimum adjustment value, a surface specific resistance of 10 ¹¹ Ω / □ or more may be used. When this low resistance treatment is applied to the entire back surface, if the surface specific resistance is 10 ¹⁵ Ω / □ or more, the film may be continuously fed, or the transfer drum may be separated from the transfer drum described in the conventional example. A peeling discharge is likely to occur between the film suction surface 3 and the film suction surface 3, and when this discharge occurs, a problem occurs that a discharge pattern is formed on the transferred image. Therefore, it is preferably adjusted to 5 × 10 ¹⁴ Ω / □ or less. That is, 1 × 10 ^{11 to} 5 × 1
Optimally, the surface specific resistance of the adsorption surface 3 is adjusted within the range of 0 ¹⁴ Ω / □. Needless to say, the same method as for the toner receiving layer 2 can be used to form the adsorption surface 3.

Example 2 FIG. 1 (b) shows another embodiment of the present invention, in which the structure of the adsorption surface 3 is different from that of (a), and a resin coating layer 4 having a high resistance is separately provided at the end of the film. It is a thing.
The resin coating layer 4 is 1 × 10 ¹¹ shown in the first embodiment.
The surface specific resistance is set to Ω / □ or more, and the forming width l is required to be at least 1.5 mm or more. 1.5m
When the width is less than m, the above memory phenomenon occurs as the width becomes narrower. However, it goes without saying that the formation width l is set to be narrower than the image width defined in the specifications of the copying machine main body.

[Embodiment 3] FIG. 1 (c) is a different embodiment of the present invention, which is a modification type of FIG. 1 (b), in which the low resistance treatment of the adsorption surface 3 is not applied only to the end portion of the film. is there. In this case, the surface of the green film is substantially exposed at the edge of the film, and the surface resistivity is 10 ¹⁶ Ω /
□ It will be about.

The embodiment of the present invention has been described above.
In all cases, it is necessary to prevent the formation of an image on the adsorption surface 3 of the film. For this reason, in the embodiment of the present invention, it is more preferable to provide printing or the like so that the film configurations on the front and back sides are necessarily different.

[0021]

As described above, according to the present invention,
By making the physical properties of the front and back of the film different and setting at least one end of one surface to 1 × 10 ¹¹ Ω / □ or more, abnormal charge injection to the photosensitive drum during image transfer can be prevented.

[Brief description of drawings]

1 is a cross-sectional view of a film showing an embodiment of the present invention.

FIG. 2 is a sectional view of an image forming apparatus capable of passing an electrophotographic film.

Claims (3)

[Claims] 1. An electrophotographic resin film having a toner image formed on the surface thereof, wherein the front and back surfaces are different, and the surface specific resistance of at least one end is at least 10 ¹¹ Ω / □. A resin film for electrophotography, which is characterized by being present. 2. The surface resistivity is 10 ¹¹ Ω / □ to 5 × 10.
^The resin film for electrophotography according to claim 1, which has a resistance of ¹⁴ Ω / □. 3. The surface resistivity of the other surface is 10 ⁸ Ω / □
The resin film for electrophotography according to claim 1, which has a resistance of about 10 ¹⁰ Ω / □.