JPH0695415A - Electrophotographic sensitive body and image forming device - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body which causes no transfer defect such as picture void. CONSTITUTION:In the device to form multicolor picture images, picture images are formed in the following process. A toner image is formed with a toner having <=8.0mum average particle size, which is carried on an electrophotographic sensitive body. A transfer material carried on a polyvinylidene fluoride resin sheet as the carrier sheet by a carrying means is brought into contact with this electrophotographic sensitive body. A transfer means is disposed to effect from the carrying means of the transfer material is in the contact position between the photosensitive body and the transfer material to transfer the toner image on the photosensitive body. The surface layer of the photosensitive body contains >=5wt.% powdery fluororesin. Thereby, with the obtd. electrophotographic sensitive body, good picture images without transfer defect such as picture void can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor image forming apparatus, and more particularly to an electrophotographic photosensitive member used in a multicolor electrophotographic apparatus.

[0002]

2. Description of the Related Art Various conventional multicolor electrophotographic apparatuses have been proposed. FIG. 2 shows a multicolor electrophotographic apparatus provided with a developing device called a rotary developing device.

The figure will be briefly described below. In the multicolor electrophotographic apparatus, an image carrier, which is rotatably supported and rotatable in the direction of an arrow, that is, a photosensitive drum 1, is disposed, and an image forming unit is disposed on the outer peripheral portion thereof.

Primary charger 2 for uniformly charging the photosensitive drum
Then, a color-separated light image or a light image corresponding thereto is irradiated to form an electrostatic latent image on the photosensitive drum 1. For example, the exposure unit 3 includes a laser beam exposure device and the like, and the rotary developing device 4 that converts the electrostatic latent image on the photosensitive drum 1 into a visible image.

The rotary developing device 4 includes four developing devices 4 for separately storing four color developers of yellow color developer, magenta color developer, cyan color developer and black color developer.
Y, 4M, 4C, 4BK and these four developing devices 4Y,
4M, 4C, and 4BK, and a substantially cylindrical housing 4a that is rotatably supported and rotatably supported. The rotary developing device 4 conveys a desired developing device to a position facing the outer peripheral surface of the photosensitive drum 1 by the rotation of the housing 4a, develops an electrostatic latent image on the photosensitive drum, and Is rotated once, so that full-color development for so-called four colors is possible.

A visible image on the photosensitive drum 1, that is, a toner image, is transferred onto a transfer material P carried by a transfer device 5.
Is transcribed to. The transfer device 5 is a transfer drum that is rotatably supported, and the transfer drum 5 includes a cylinder 5a and a transfer charging unit that constitutes a transfer means provided in the cylinder 5a, as will be understood with reference to FIG. It has a container 5b and a transfer material gripper 5c for gripping the transfer material P fed from a paper feeding device (not shown). Further, an inner charge eliminating charger 5d and an outer charge eliminating charger 5e, which constitute charge eliminating means, are arranged inside and outside the transfer drum 5. A transfer material carrying sheet 501 is stretched over the outer peripheral surface opening area of the cylinder 5a, and a polyvinylidene fluoride resin film is usually used as the transfer material carrying sheet 501.

A process of forming a full-color image by the multicolor electrophotographic apparatus having the above-mentioned structure will be briefly described. First, the charging device 2 and the image exposing means 3 are operated to form a blue color-separated electrostatic latent image on the outer peripheral surface of the photosensitive drum 1. The electrostatic latent image is stored in the developing device 4Y. It is developed with a yellow developer. On the other hand, the transfer material P fed to the transfer drum 5 is gripped by the gripper 5c,
The toner image formed on the outer peripheral surface of the photosensitive drum 1 is brought into contact with the rotation of the transfer drum 5. The toner image is transferred onto the transfer material P by the operation of the transfer charger 5b, and at the same time, the transfer material P is transferred onto the transfer material carrying sheet 50.
Adsorbed to 1.

The above-mentioned image forming and transfer operations are performed by the magenta,
It is repeated for each color of cyano and black.
When the transfer of the four color visible images onto the transfer material P is completed, the transfer material P is discharged by the inner charging device 5d and the outer charging device 5e, then separated from the transfer drum 5, and the heat roller fixing device 6 is removed. It is discharged to the outside of the machine via. On the other hand, the residual toner on the photosensitive drum 1 is removed by the cleaner 7, and the photosensitive drum 1 is subjected to the next image forming process. Reference numeral 8 denotes a separation claw for separating the transfer material P from the transfer material carrying sheet 501.

[0009]

The multicolor electrophotographic apparatus having the above-described structure operates extremely favorably, and according to the research and experiments conducted by the present inventors, the average particle size of the toner of each color is 8.0.
When the thickness is less than μm, the transfer material carrying sheet 50 of the transfer drum 5
Using a polyvinylidene fluoride resin film as 1,
When a transfer paper is used as the transfer material P and a surface layer of the photosensitive drum contains a polycarbonate resin and a charge transport substance, the initial transfer efficiency before endurance [toner transferred to the transfer material / (photosensitive material The amount of toner remaining on the drum + the amount of toner transferred to the transfer material)] was about 90%, which was a very good image. However, enduring thousands of them,
When the transfer efficiency after endurance was measured, it was about 80%, and at the same time, transfer failure occurred in many small area portions on the halftone image. (Hereinafter referred to as "blurred image") That is, in a multicolor electrophotographic apparatus that visualizes and superimposes a plurality of electrostatic images, a solid image such as a photograph is often printed. Was a problem in that it was very noticeable on the image.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to establish a multicolor electrophotographic apparatus which prevents image blurring due to durability as described above and continues to provide high quality images.

[0011]

That is, according to the present invention, a toner image is formed with a toner having an average particle size of 8.0 μm or less, and a transfer material carrying means carries a transfer material carrying means on an electrophotographic photosensitive member carrying a toner image. The transfer material carried on the polyvinylidene fluoride resin sheet, which is a sheet, is brought into contact with the transfer material, and the transfer means acting from the transfer material carrying means side is arranged at the position where the photoconductor and the transfer material are brought into contact with each other. In a multicolor image forming apparatus for forming an image by transferring a toner image on the photoconductor onto the transfer material, the surface layer of the photoconductor contains 5% by weight or more of a fluororesin powder. And an electrophotographic photoreceptor.

The present invention will be described in detail below.

Fluorine resin powders applicable to the present invention include tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluoropropylene resin, vinyl fluoride resin, vinylidene fluoride resin, and difluorochloroethylene resin. And one or more of these copolymers are appropriately selected. Especially, low molecular grade and average primary particle size of 1.0 μ
m or less is preferable, and 0.3 μm or less is particularly preferable.

The content of the fluorine-based resin powder dispersed in the surface layer is preferably 5 to 50% by weight, and particularly preferably 10 to 40% by weight, based on the solid weight of the surface layer. If the content is less than 5% by weight, the effect of modifying the surface layer by the fluorine-based resin powder is not sufficient, and the effect on image loss is small. On the other hand, if it exceeds 50% by weight, the light transmittance is lowered and the mobility of the carrier is also lowered, so that it tends to be unfavorable in terms of electrophotographic characteristics. The binder resin for forming the surface layer may be a polymer having a film-forming property, but it has a certain degree of hardness even by itself, polymethacrylic acid ester from the viewpoint of not interfering with carrier transport, Polystyrene, methacrylic acid ester / styrene copolymer, polycarbonate, polyarylate, polyester, polysulfone and the like are preferable.

When the electrophotographic photosensitive member used in the present invention is manufactured, the conductive support is a conductive material obtained by dispersing conductive particles in a suitable binder resin on a support such as metal such as aluminum and stainless steel, paper, plastic or the like. A cylindrical cylinder provided with layers or a film is used. However, when the support itself is conductive, the conductive support need not be provided with a conductive layer.

An undercoat layer (adhesive layer) having a barrier function and an undercoat function can be provided on these conductive supports.

The subbing layer is for improving the adhesion of the photosensitive layer, improving the coating property, protecting the conductive support, covering defects on the conductive support, improving the charge injection property from the conductive support, and the photosensitive layer. It is formed for protection against electric breakdown of Known materials for the subbing layer include polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, ethylene-acrylic acid copolymer, casein, polyamide copolymerized nylon, glue and gelatin. These are dissolved in a suitable solvent and coated on a support. The film thickness is about 0.2 μm to 2 μm.

As the charge generating substance, a cyanine dye, an azulene dye, a squarylium dye, a pyrylium dye, a thiapyrylium dye, a phthalocyanine pigment,
Azo pigments such as anthanthrone pigment, dibenzpyrenequinone pigment, pyranthrone pigment, monoazo pigment, disazo pigment and trisazo pigment, indigo pigment, quinacridone pigment, asymmetric quinocyanine and quinocyanine can be used. As the charge transport material, pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N-phenylhydrazino-3-methylidene-9-ethylcarbazole, N, N-
Diphenylhydrazino-3-methylidene-9-ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, N, N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, p- Diethylaminobenzaldehyde-N,
N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, p-pyrrolidinobenzaldehyde-N, N-diphenylhydrazone, 1,3,3-trimethylindolenine-ω-aldehyde-N, N-diphenylhydrazone, p
-Hydrazones such as diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2,5-
Bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1-phenyl-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl)
Pyrazoline, 1- [quinolyl (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3- (p
-Diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [6-methoxypyridyl (2)]-3- (p-diethylaminostyryl) -5-
(P-Diethylaminophenylpyrazoline, 1- [pyridyl (3)]-3- (p-diethylaminostyryl)-
5- (p-diethylaminophenyl] pyrazoline, 1-
[Lepidil (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3- (p-diethylaminostyryl) -4-methyl-5- (P-Diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3-
(Α-Methyl-p-diethylaminostyryl] -5-
(P-diethylaminophenyl) pyrazoline, 1-phenyl-3- (p-diethylaminostyryl) -4-methyl-5- (p-diethylaminophenyl] pyrazoline,
1-Phenyl-3- (α-benzyl-p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, pyrazolines such as spiropyrazolin, 2-
(P-Diethylaminostyryl) -6-diethylaminobenzoxazole, 2- (p-diethylaminophenyl) -4- (p-dimethylaminophenyl) -5- (2
-Chlorophenyl) oxazole and other oxazole compounds, 2- (p-diethylaminostyryl) -6-diethylaminobenzthiazole and other thiazole compounds, bis (4-diethylamino-2-methylphenyl)
Triarylmethane compounds such as phenylmethane,
1,1-bis (4-N, N-diethylamino-2-methylphenyl) heptane, 1,1,2,2-tetrakis (4-N, N-dimethylamino-2-methylphenyl)
Polyarylalkanes such as ethane, 5- (4-diphenylaminobenzylidene) -5Hdibenzo [a, d]
A stilbene compound such as cycloheptene or 1,2-benzo-3- (d-phenylstyryl) -9-n-butylcarbazole can be used.

The method for preparing the electrophotographic photosensitive member of the present invention will be described by taking the case of a function-separated type photosensitive member in which a charge transport layer is laminated on a charge generating layer as an example.

The above charge generating substance is used together with a binder resin and a solvent of about 0.3 to 10 times, a homogenizer, ultrasonic waves,
Disperse well by methods such as pole mill, vibration pole mill, sand mill, attritor, and roll mill. This dispersion was coated on the support coated with the subbing layer, dried, and then dried.
A coating film of about 1 to 1 μm is formed.

In this example, since the surface layer serves as a charge transport layer, the fluororesin powder is dispersed therein.

That is, the binder resin and the fluororesin powder are dispersed together with a solvent by a homogenizer, ultrasonic wave, pole mill, sand mill, attritor, roll mill, etc., and a solution of the charge transport substance and the binder resin is added to this to obtain the desired mixture. The charge transport layer liquid is prepared.

The mixing ratio of the charge transport material and the binder resin is about 2: 1 to 1: 4.

As the solvent, aromatic hydrocarbons such as toluene and xylene, chlorine-based hydrocarbons such as dichloromethane, chlorobenzene, chloroform and carbon tetrachloride are used. When applying this solution, for example, a coating method such as a dip coating method, a spray coating method, a spinner coating method, a pied coating method, a blade coating method or a curtain coating method can be used, and drying is performed at 10 to 200 ° C. It can be carried out at a temperature in the range of 20 to 150 ° C. for 5 minutes to 5 hours, preferably for 10 minutes to 2 hours under blast drying or static drying. The formed charge transport layer has a thickness of about 10 to 30 μm.

Further, in the case of a photoreceptor in which the charge generating layer is coated on the charge transporting layer, the charge generating layer serves as the surface layer, and therefore the dispersion-stabilized fluorine resin powder is contained therein. This charge generation layer dispersion is prepared by adding and mixing the dispersion prepared by dispersing the fluororesin powder in the binder resin used for the charge generation layer to the charge generation dispersion prepared as described above. This dispersion can be applied onto the charge transport layer to obtain the photoreceptor of the present invention.

When the photosensitive layer has a protective layer, the protective layer serves as a surface layer of the photosensitive layer, and the dispersion-stabilized fluorine resin powder is contained in the protective layer. This protective layer can be obtained by applying a dispersion liquid of the fluorine-based resin powder dispersion-stabilized in the resin forming the protective layer onto the photosensitive layer as described above.

The present invention will be described in more detail below with reference to specific examples.

[0028]

【Example】

(Embodiment 1) The present invention can be suitably implemented in a multicolor electrophotographic apparatus having a rotary developing device shown in FIG. Therefore, in this embodiment, the multicolor image forming apparatus is embodied in the multicolor electrophotographic apparatus of FIG.

As described above, the multicolor electrophotographic apparatus of FIG. 2 uses four color toners having an average particle size of 8.0 μm or less,
A polyvinylidene fluoride resin film is used as the transfer material carrying sheet 501 of the transfer drum 5, and a transfer paper is used as the transfer material P to form a multicolor image.

The structure and operation are basically as described above, but the diameter of the photosensitive drum 1 is, for example, 80 mm, and the diameter of the transfer drum 5 is 160 mm (twice the diameter of the photosensitive drum).

The photosensitive drum 1 is 160 mm / sec.
Is rotated in the direction of the arrow, and the surface of the photosensitive drum 1 is uniformly primary-charged to -300 to -900V by the primary charger 2. The developing devices 4Y, 4M, 4C of the rotary developing device 4,
And 4BK have toner of each color having a negative charge, and visualize the latent image formed on the photosensitive drum 1 by reversal development.

The developing devices 4Y, 4M, 4C, and 4BK
A developing bias is applied by a developing bias power source (not shown) at positions where these developing units are close to the photosensitive drum 1. Specifically, for example, a DC voltage (V _DC ) -450 V is applied to the latent image forming unit as an example for an electrostatic latent image having a dark part potential (V _O ) -600 V and a light part potential (V _L ) -200 V. Peak and peak voltage is 3 by superimposing
An AC voltage of 00 to 2500 V _PP and a frequency of 200 to 3000 Hz is applied to the sleeve 10 of the developing device at a position where the developing device is close to the photosensitive drum 1, and the photosensitive drum 1
Is held at ground potential.

The method for producing the photoconductor in the present invention will be described below.

50 parts by weight of conductive titanium oxide powder coated with tin oxide containing 10% antimony oxide, 25 parts by weight of phenol resin, 20 parts by weight of methyl cellosolve, 5 parts by weight of methanol and silicone oil (polydimethylsiloxane poly). 0.002 parts by weight of the oxyalkylene copolymer (number average molecular weight 3000) was dispersed for 2 hours in a sand mill using φ1 mm glass beads to prepare a conductive coating material. Aluminum cylinder (φ80mm x 360)
Dip-coat the above paint on the top, and at 140 ℃ for 30
It was dried for a minute to form a conductive layer having a film thickness of 20 μm.

Next, 30 parts by weight of methoxymethylated nylon resin (number average molecular weight 32000) and 10 parts by weight of alcohol-soluble copolymerized nylon resin (number average molecular weight 29000) are mixed in a mixed solvent of 260 parts by weight of methanol and 40 parts by weight of butanol. The dissolved liquid was applied onto the conductive layer by a dipping coating machine to form an undercoat layer having a film thickness after drying of 1 μm.

Next, a disazo pigment represented by the following structural formula [1]

[0037]

[Chemical 1] 4 parts by weight, 2 parts by weight of benzal resin, and 40 parts by weight of tetrahydrofuran were dispersed for 60 hours in a sand mill using φ1 mm glass beads, and then diluted with a cyclohexanone / tetrahydrofuran mixed solvent to prepare a charge generation layer coating material.

This coating solution was applied onto the above-mentioned undercoat layer by a dipping coating machine to form a charge generation layer having a thickness of 0.1 μm after drying.

Next, the following structural formula [2]

[0040]

[Chemical 2] 10 parts by weight of the charge-transporting material and 10 parts by weight of a polycarbonate resin (number average molecular weight 25000) are dissolved in a mixed solvent of 20 parts by weight of dichloromethane and 40 parts by weight of monochlorobenzene, and this solution is dip-coated on the charge generation layer. Then, it was dried at 120 ° C. for 60 minutes to form a charge transport layer having a film thickness of 20 μm.

Next, 6 parts by weight of a polycarbonate resin (number average molecular weight 25,000), 3 parts by weight of the above charge transport material, polytetrafluoroethylene (average primary particle size 0.3 μm)
1 part by weight is dissolved in a mixed solvent of 200 parts by weight of dichloromethane and 300 parts by weight of monochlorobenzene, and this solution is spray coated on the charge transport layer and dried at 120 ° C. for 60 minutes to obtain a surface protective layer having a thickness of 6 μm. Was formed.

The electrophotographic photosensitive member thus produced was evaluated for durability image formation by the multicolor electrophotographic apparatus having the above-mentioned structure. As a result, it was possible to obtain a good image with no transfer defects such as image blur in the halftone image after running 10,000 sheets.

(Example 2) The surface protective layer of the electrophotographic photosensitive member of Example 1 was not provided, and the polytetrafluoroethylene particles (average primary particle size 0.3 µm) were 10 in the charge transport layer.
%, Except under the same conditions as in Example 1,
Durability image formation evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 3) The same conditions as in Example 1 except that 30% by weight of polytetrafluoroethylene in the surface protective layer of the electrophotographic photosensitive member in Example 1 was contained in the surface protective layer. The durability image output evaluation of the sample prepared in 1 was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 4 The same conditions as in Example 1 except that 5% by weight of polytetrafluoroethylene in the surface protective layer of the electrophotographic photosensitive member of Example 1 was contained in the surface protective layer. The durability image output evaluation of the sample prepared in 1 was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1) Example 1 is the same as Example 1 except that the surface protective layer of the electrophotographic photosensitive member is not provided and the charge transport layer containing no polytetrafluoroethylene particles is the surface layer. Under the same conditions as above, evaluation of durability image formation was performed in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 Under the same conditions as in Example 1 except that the thickness of the charge transport layer of the electrophotographic photosensitive member of Comparative Example 1 not containing the polytetrafluoroethylene particles was 26 μm. Durability image formation evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 3) The same conditions as in Example 1 except that the surface protective layer contained 3% by weight of polytetrafluoroethylene in the surface protective layer of the electrophotographic photosensitive member of Example 1. The durability image output evaluation of the sample prepared in 1 was performed in the same manner as in Example 1. The results are shown in Table 1.

[0049]

[0050]

As described above, the average particle size is 8.0 μm.
A toner image is formed with a toner having a size of m or less, and the transfer material carried by the transfer material carrying sheet is carried on the polyvinylidene fluoride resin sheet which is the transfer material carrying sheet by the transfer material carrying means. An image is formed by transferring a toner image on the photoconductor to the transfer material by arranging a transfer means that acts from the transfer material carrying means side at a position where the photoconductor and the transfer material come into contact with each other. In a multicolor image forming apparatus to be formed, by using an electrophotographic photosensitive member whose surface layer contains 5% by weight or more of a fluororesin powder in the surface layer of the photosensitive member, it is possible to obtain a good image without a transfer defect such as a missing image in a durable image. It is possible to obtain a clear image.

[Brief description of drawings]

FIG. 1 is a constitutional view of an electrophotographic photosensitive member containing a fluororesin powder of the present invention.

FIG. 2 is a schematic view showing an example of a multicolor electrophotographic apparatus to which the present invention can be applied.

[Explanation of symbols]

 a Aluminum cylinder b Conductive layer c Subbing layer d Charge generation layer e Charge transport layer f Surface protective layer g Fluorine-based resin powder 1 Photosensitive drum 2 Primary charger 4 Rotating developing device 4Y, 4M, 4C, 4BK Developing device 5 Transfer drum 10 Development sleeve

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Masaaki Yamagami 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (2)

[Claims] 1. A toner image having an average particle diameter of 8.0 μm or less is formed on a polyvinylidene fluoride resin sheet which is a transfer material carrying sheet by a transfer material carrying means on an electrophotographic photoreceptor carrying the toner image. The transfer material carried and conveyed is brought into contact with the transfer material, and the transfer means acting from the transfer material carrying means side is arranged at the position where the transfer material is brought into contact with the transfer material so that the toner image on the transfer material is transferred to the transfer material. In a multicolor image forming apparatus for forming an image by transferring to the transfer material, an electrophotographic photosensitive member characterized in that the surface layer of the photosensitive member contains 5% by weight or more of a fluororesin powder. 2. A multicolor image forming apparatus comprising the electrophotographic photosensitive member according to claim 1.