JP2002268491A - Image forming device provided with cleaning means with elastic blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve toner welding to the surface of an organic photosensitive drum ('dash mark' or 'toner filming') and the trouble with use of an elastic blade ('blade squeaking' or 'blade turning-up') and to improve the wear resistance of the photosensitive body (to extend the life) with respect to the organic photosensitive drum and a cleaning means having the elastic blade. SOLUTION: An image forming device is provided with an elastic blade 28 which is brought into contact with an image carrier surface with a contact pressure of 8 to 20 g/cm linear pressure, and the image forming device uses an organic photosensitive body 21 to which the contact angle of the elastic blade 28 is 12 to 30 deg. and which is made of binder resin containing copolymerized polycarbonate in the outermost surface layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrostatic copying machine, a facsimile, and a laser beam printer. More specifically, an organic photoreceptor drum having good abrasion resistance, provided with cleaning means having an elastic blade, "dash mark", "toner filming",
The present invention relates to an image forming apparatus that does not generate “blade squeal” and “blade roll-up” and has “long life”.

[0002]

2. Description of the Related Art In the above-mentioned image forming apparatus, an electrophotographic photosensitive member is used in a repetitive process of a charging unit, an exposing unit, a developing unit, a transferring unit, and a cleaning unit in an image forming process. The electrostatic latent image formed by the charging and exposing means is developed with toner, which is a fine powder. Further, the developed toner is transferred to a transfer material such as paper by the transfer means, but 100% of the toner is not transferred, and a part thereof remains on the image carrier, that is, the surface of the photoreceptor. Unless the remaining toner is removed, a high-quality image free from dirt or the like cannot be obtained in the repetitive process. Therefore, cleaning of the remaining toner is required.

A typical cleaning means uses a fur brush, a magnetic brush, an elastic blade, or the like. From the viewpoints of cleaning accuracy, rationalization of the apparatus configuration, and the like, the blade-shaped resin plate directly contacts the photosensitive member. In general, a cleaning means using an elastic blade for performing cleaning is selected.

On the other hand, in the above-mentioned image forming apparatus, various photosensitive members having sensitivity in a wavelength region of a light source used in the image forming apparatus are used. One is an inorganic photoreceptor using an inorganic material such as selenium for the photosensitive layer, and the other is an organic photoreceptor (OPC) using an organic material for the photosensitive layer. Of these, organic photoreceptors are easier to manufacture than inorganic photoreceptors, and have a wide variety of photoreceptor materials, such as charge transport agents, charge generators, and binder resins, and a high degree of freedom in functional design. In recent years, extensive research has been conducted.

The organic photoreceptor includes a so-called laminated type photoreceptor having a laminated structure of a charge generating layer containing a charge generating agent and a charge transporting layer containing a charge transporting agent, and a charge generating agent and a charge transporting agent. Is dispersed in a single photosensitive layer, that is, a so-called single-layer type photosensitive member. Of these, the multilayer photoconductor occupies a wide market scale.

However, the single-layer type photoreceptor has a simple layer structure and is excellent in productivity, can suppress the occurrence of film defects in the photosensitive layer, and can improve optical characteristics because of a small number of interfaces between layers. The combined use of an electron transporting agent and a hole transporting agent as the charge transporting agent has the advantage that one photoreceptor can be used for both the positively charged type and the negatively charged type.

[0007]

As described above, the cleaning means using the elastic blade removes the residual toner on the surface of the organic photoconductor by bringing the blade-shaped resin plate into contact with the surface of the organic photoconductor. However, if the force of the elastic blade pressing the surface of the organic photosensitive drum (linear pressure of the blade) or the angle of contact between the elastic blade and the surface of the organic photosensitive drum (the pressure contact angle of the blade) is small, the remaining toner will be in contact with the elastic blade. A phenomenon called so-called "dash mark" or "toner filming" in which the toner particles penetrate under the small gaps between the photoreceptor surfaces while being pressed, and are firmly fused to the surface of the organic photoreceptor while the toner particles are crushed. Is caused, the surface potential of the organic photoreceptor at the fused portion of the toner is greatly reduced, and light is blocked, so that light attenuation does not occur, which causes image defects.

In order to improve the cleaning performance and prevent the occurrence of the dash mark and the toner filming, if the linear pressure or the contact angle of the blade is increased, resonance occurs when the elastic blade rubs the surface of the organic photoreceptor. A phenomenon called "blade squeal" that generates sound,
Alternatively, a phenomenon called "blade curling" may occur, in which the blade undulates or reverses in the same rotational direction as the drum.

Further, the mechanical load on the surface of the organic photoreceptor increases, and the amount of abrasion of the photosensitive layer increases.
Problems such as deterioration in sensitivity occur early, making it difficult to obtain high-quality images, and a so-called “long-life” image forming apparatus cannot be obtained.

An object of the present invention is to provide a cleaning means having an organic photosensitive drum and an elastic blade as an image carrier, and to provide the above-mentioned "dash mark", "toner filming", "blade squeal" and "blade curling". An object of the present invention is to provide an image forming apparatus which is free from occurrence and has a "long life". Further, it is another object of the present invention to specify the binder resin structure of the organic photoreceptor drum to further extend the life of the image forming apparatus.

[0011]

Means for Solving the Problems As a result of earnest studies, the present inventors have sequentially provided a charging means, an exposure means, a developing means, a transfer means, and a cleaning means around a rotatable image carrier, and have developed, An image forming apparatus in which toner remaining on the surface of the image carrier after passing through a transfer unit is removed by the cleaning unit, wherein the cleaning unit is held by a support member and has a linear pressure of 8 g / g. 20 cm or more
an elastic blade in contact with the surface of the image carrier at a contact pressure of not more than g / cm, and a pressure contact angle of the elastic blade is not less than 12 ° and not more than 30 °; An image forming apparatus characterized by being an organic photoreceptor having a photosensitive layer made of a binder resin containing at least a charge generating agent and a charge transport agent on a conductive substrate, a dash mark, toner filming, blade squealing, It has been found that the occurrence of blade curling is small, the abrasion resistance of the organic photoreceptor is good, and the life is long.

Further, the linear pressure is 10 g / cm or more and 18
g / cm or less, or when the pressure contact angle is 15 ° or more and 25 ° or less, a dash mark, toner filming,
It has been found that blade squeal and blade curling are more effectively prevented, and that the organic photoreceptor is more effectively prevented from being scraped.

On the other hand, the organic photoreceptor as the image bearing member has a repeating structural unit represented by the general formula [1] and a repeating structural unit represented by the general formula [2] as a binder resin of the outermost surface layer. Polymerized polycarbonate resin or copolymerized polycarbonate resin having a repeating structural unit represented by general formula [1], a repeating structural unit represented by general formula [2], and a repeating structural unit represented by general formula [3] When it is contained, it has been found that it is particularly effective for preventing the occurrence of dash marks, toner filming, blade squealing, or blade curling, the wear resistance of the organic photoreceptor is remarkably improved, and the life is further extended. .

General formula [1]

Embedded image (In the general formula [1], R ¹⁰ and R ¹¹ are the same or different and each represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)

General formula [2];

Embedded image (In the general formula [2], R ²⁰ and R ²¹ are the same or different and represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a phenyl group, and R ²² and R ²³ are the same or different and represent a carbon atom. Number 1
And alkyl groups, phenyl groups, and cycloalkylidene groups which may form a ring and have a substituent. )

General formula [3];

Embedded image (In the general formula [3], X ³⁰ , X ³¹ , and X ³² are the same or different and are-(CH ₂ ) _n- , n is an integer of 1 to 6, and R
³⁰ , R ³¹ , R ³² , and R ³³ are the same or different and each represent a hydrogen atom, a phenyl group, an alkyl group or an alkoxy group having 1 to 3 carbon atoms, and m represents a numerical value of 0 to 200. )

[0017]

The image forming apparatus of the present invention has a charging unit, an exposing unit, a developing unit, a transferring unit and a cleaning unit around a rotatable image carrier in order, and after passing through a developing unit and a transferring unit. The toner remaining on the surface of the image carrier is removed by the cleaning unit, and the cleaning unit is held by a support member, and the linear pressure of the cleaning unit is 8 g / cm.
An elastic blade that is in contact with the surface of the image carrier with a contact pressure of not less than 20 g / cm, and a pressure contact angle of the elastic blade is not less than 12 ° and not more than 30 °; On a conductive substrate, at least a charge generating agent,
The organic photoreceptor is provided with a photosensitive layer made of a binder resin containing a charge transport agent.

Further, the linear pressure is 10 g / cm or more and 18 or more.
g / cm or less, or the case where the pressure contact angle is 15 ° or more and 25 ° or less.

When the linear pressure of the elastic blade is less than 8 g / cm or the pressure contact angle is less than 12 °, the abrasion resistance of the organic photoreceptor is good and the charging ability and sensitivity are hardly deteriorated.
Dash marks and toner filming occur frequently. Conversely, if the linear pressure of the elastic blade is greater than 20 g / cm or the pressure contact angle is greater than 30 °, dash marks and toner filming do not occur, but a large torque is required to rotate the photoconductor. The blade squeal and blade curling frequently occur, and the abrasion resistance of the organic photoreceptor is significantly deteriorated.

In particular, the organic photoreceptor as the image bearing member has a repeating structural unit represented by the general formula [1] and a repeating structural unit represented by the general formula [2] as a binder resin of the outermost surface layer. Polymerized polycarbonate resin or a copolymerized polycarbonate resin having a repeating structural unit represented by the general formula [1], a repeating structural unit represented by the general formula [2], and a repeating structural unit represented by the general formula [3] It is preferred to contain.

The repeating structural unit represented by the general formula [1] has high rigidity of the molecule and is extremely effective in improving the wear resistance of the photosensitive layer. Further, since the repeating structural unit represented by the general formula [3] has a siloxane bond in the main chain, it has an effect of improving the abrasion resistance of the photosensitive layer and, in particular, reduces the friction coefficient of the cleaning blade against the surface of the photosensitive layer. Since it is effective, it is also effective in preventing blade squeal and blade curling, and reduces the surface energy of the photosensitive layer, so that toner fusion hardly occurs.

However, although the polycarbonate resin having a repeating structural unit represented by the general formula [1] or [3] has the above-mentioned effects, it is inferior in solubility in a solvent and compatibility with a charge transporting agent. There is a disadvantage that electrical characteristics such as charging ability and sensitivity are slightly deteriorated. Thus, by incorporating a polycarbonate resin having a repeating structural unit represented by the general formula [2] in combination by copolymerization, the solubility in a solvent and the compatibility with a charge transport agent are remarkably improved, and the electric characteristics are improved.

In particular, the image forming apparatus of the present invention is suitably used when the organic photoreceptor as the image carrier is a single-layer type photoreceptor. In the case of a laminated photoreceptor (negatively charged type), the charge transporting layer in contact with the cleaning blade has only a hole transporting agent molecularly dispersed in a binder resin. On the other hand, the single-layer type photoreceptor contains a charge generating agent, a hole transporting agent, and an electron transporting agent in the binder resin at the same time as described above, and the content of the low molecular weight compound dispersed in the molecule is large, Further, since the charge generating agent is dispersed in particles, the surface lubricity of the photosensitive layer is often reduced as compared with the laminated photoreceptor, and blade squeal and blade curling are more likely to occur.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Cleaning Means of Image Forming Apparatus] An image forming apparatus of the present invention has a charging means, an exposing means, a developing means, a transferring means, and a cleaning means around a rotatable image carrier in order. After development and transfer, the toner remaining on the surface of the image carrier is removed by the cleaning means, and the cleaning means is held on a support member and has a linear pressure of 8 g / cm to 20 g / cm.
an elastic blade which is in contact with the surface of the image carrier with a contact pressure of not more than 10 cm, and a pressure contact angle of the elastic blade is not less than 12 ° and not more than 30 °. Further, the linear pressure is 10 g / cm or more and 18 g / cm or less,
Alternatively, it is preferable that the pressure contact angle is 15 ° or more and 25 ° or less.

In the cleaning means, when the elastic blade is brought into pressure contact with the surface of the rotating organic photoreceptor drum, generally, as shown in FIG. 13, the tip of the elastic blade 11 is pressed against the surface of the rotating organic photoreceptor 12.

The contact surface 11a of the elastic blade 11 contacting the organic photoreceptor 12 and the tangent X of the organic photoreceptor 12 at the contact point make the pressure contact of the elastic blade 11 on the rotational direction side of the organic photoreceptor 12. Angle θ is 12-30
° and the pressing force (linear pressure) f of the elastic blade against the organic photoreceptor is set to 8 to 20 g / cm.

Further, in order to efficiently scrape off the residual toner from the surface of the organic photosensitive member 12, it is preferable to swing the elastic blade 11 in the axial direction of the organic photosensitive member 12. Also, depending on the type of the organic photoreceptor 12 to be used, when a fixed portion is kept pressed for a long time by the elastic blade 11, when a half image is copied, the contact portion appears as image noise (blade pressure contact). Therefore, when the organic photoconductor 12 is not rotating,
It may be separated from the organic photoreceptor 12 (blade separation / contact).

The cleaning means of the image forming apparatus of the present invention is applied only when the peripheral speed of the organic photoreceptor 12 is 9
0 to 300 mm / sec is preferable. If the peripheral speed is outside the above range, the wear resistance and the cleaning property of the photosensitive layer change, so that it is necessary to reset the cleaning conditions.

[Image Carrier of Image Forming Apparatus] The image forming apparatus of the present invention is suitably used when the image carrier is a single-layer photosensitive member as described above. Hereinafter, a single-layer type photoconductor will be described as an example of the image carrier, and the constituent materials thereof will be described in detail.

<Binder Resin> As the binder resin, various resins conventionally used for the photosensitive layer can be used. In particular, the repeating structural unit represented by the general formula [1] and the general formula [2] Or a repeating structural unit represented by the general formula [1], a repeating structural unit represented by the general formula [2], and a repeating structural unit represented by the general formula [3] It is preferable to contain a copolymerized polycarbonate resin having a unit.

When the above-mentioned copolymer resin is contained, at least the copolymer resin may be contained.
Various resins conventionally used for the photosensitive layer can be used.

The resins conventionally used in the photosensitive layer include, for example, other polycarbonate resins, polyester resins, polyarylate resins, and styrene resin.
Butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polyvinyl chloride , Polypropylene, ionomer, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide, polyurethane, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, thermoplastic resin such as polyether resin, silicone resin, epoxy resin, phenol Resins such as resins, urea resins, melamine resins, other cross-linkable thermosetting resins, and photo-curable resins such as epoxy acrylate and urethane-acrylate can be used.

The above-mentioned binder resins can be used alone or as a blend or copolymer of two or more.

When a polycarbonate resin having a repeating structural unit represented by the general formula [1] or [3] is contained, the repeating structural unit represented by the general formula [1] is added to the total amount of the binder resin. 10 to 50 mol%
And 0.1% of the repeating structural unit represented by the general formula [3].
It is preferably contained in an amount of from 0.05 to 10 mol%. When the content of the repeating structural unit represented by the general formula [1] is 50 mol
%, The abrasion resistance of the photosensitive layer is improved, but problems such as a decrease in solvent solubility and compatibility with the charge transport agent occur. When the content of the repeating structural unit represented by the general formula [3] is more than 10 mol%, the lubricity of the surface of the photosensitive layer is improved, but the solubility in the solvent and the compatibility with the charge transporting agent are similarly reduced. As a result, the sensitivity of the photoconductor may deteriorate.

Conversely, when the content of the repeating structural unit represented by the general formula [1] is less than 10 mol%, or when the content of the repeating structural unit represented by the general formula [3] is 0.05%
When the amount is less than mol%, the effect of improving the abrasion resistance of the photosensitive layer and improving the lubricity of the photosensitive layer surface is reduced.

The weight average molecular weight of the binder resin is from 10,000 to 400,000, and more preferably from 30,000 to
200,000 is preferred.

<Charge Generating Agent> Examples of the charge generating agent include phthalocyanine pigments such as metal-free phthalocyanine, oxotitanyl phthalocyanine, and hydroxygallium phthalocyanine, perylene pigments, bisazo pigments, diketopyrrolopyrrole pigments, and metal-free naphthalocyanine. Pigments,
Organics such as metal naphthalocyanine pigments, squaraine pigments, trisazo pigments, indigo pigments, azulhenium pigments, cyanine pigments, pyrylium pigments, anthanthrone pigments, triphenylmethane pigments, sulene pigments, toluidine pigments, pyrazoline pigments, and quinacridone pigments Conventionally known charge generating agents such as photoconductors and inorganic photoconductive materials such as selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon are exemplified. The charge generating agents described above can be used alone or in combination of two or more so as to have an absorption wavelength in a desired region.

Among the above-described charge generating agents, in particular, a digital optical image forming apparatus such as a laser beam printer or a facsimile using a light source such as a semiconductor laser includes:
Since a photoreceptor having a sensitivity in a wavelength region of 700 nm or more is required, phthalosinine pigments such as metal-free phthalocyanine, oxotitanyl phthalocyanine, and hydroxygallium phthalocyanine are preferably used. In addition,
The crystal form of the phthalocyanine pigment is not particularly limited, and various types can be used.

<Charge Transport Agent> Examples of the charge transport agent include conventionally known electron transport agents and hole transport agents. In particular, in the case of a single layer type photoreceptor, a hole transporting agent and an electron transporting agent are mixed and contained in the photosensitive layer in order to improve sensitivity or charge stability.

[Hole transport agent] Examples of usable hole transport agents include N, N, N ', N'-tetraphenylbenzidine derivatives, N, N, N', N'-tetraphenylphenylenediamine derivatives, N, N, N ', N'-
Tetraphenylnaphthylenediamine derivative, N, N,
N ', N'-tetraphenylphenanthrylenediamine derivative, 2,5-di (4-methylaminophenyl)-
Oxadiazole compounds such as 1,3,4-oxadiazole, styryl compounds such as 9- (4-diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, organic polysilane compounds, 1-
Pyrazoline compounds such as phenyl-3- (p-dimethylaminophenyl) pyrazoline, hydrazone compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds And nitrogen-containing cyclic compounds such as triazole compounds and condensed polycyclic compounds.

In particular, the hole transporting agent preferably contains a compound represented by the general formula [4], [5], [6] or [7].

Formula [4];

Embedded image (In the general formula [4], R ⁴⁰ , R ⁴¹ , R ⁴² and R ⁴³ are the same or different and each represent an alkyl group, an alkoxy group, an aryl group, an aralkyl group, or a halogen atom;
n, p and q are the same or different and represent an integer of 0-3. R ⁴⁴ and R ⁴⁵ are the same or different and each represent a hydrogen atom or an alkyl group. Also, -X-

Embedded image Or

Embedded image Is shown. )

General formula [5];

Embedded image (In the general formula [5], R ⁵⁰ and R ⁵² represent the same or different alkyl groups which may have a substituent, and R ⁵¹ and R ^52
53 is the same or different and represents a hydrogen atom or an alkyl group which may have a substituent. )

General formula [6];

Embedded image (In the general formula [6], R ⁶⁰ , R ⁶¹ , R ⁶² , R ⁶³ and R
⁶⁴ is the same or different and is a hydrogen atom, a halogen atom,
It represents an alkyl group or an alkoxy group which may have a substituent. )

General formula [7];

Embedded image (In the general formula [7], R ⁷⁰ , R ⁷¹ , R ⁷² and R ⁷³ may be the same or different and may have a halogen atom or a substituent,
It represents an alkyl group, an alkoxy group or an aryl group.
a, b, c and d are the same or different and each represents an integer of 0 to 5; When a, b, c or d is 2 or more, each R
⁷⁰ , R ⁷¹ , R ⁷² and R ⁷³ may be different. )

The hole transporting agent represented by the general formulas [4], [5], [6] and [7] has a very high mobility and efficiently transports holes. It is effective for improving the sensitivity of the photoreceptor.

The hole transporting agent may be used alone or in combination of two or more.

[Electron Transporting Agent] Examples of usable electron transporting agents include diphenoquinone derivatives and benzoquinone derivatives, as well as JP-A-2000-147806 and JP-A-200-200.
Azoquinone derivatives described in JP-A-242009;
A monoquinone derivative, a dinaphthylquinone derivative, a tetracarboxylic diimide derivative, a carboxylic imide derivative, a stilbenequinone derivative, an anthraquinone derivative described in 00-075520 or JP-A-2000-258936;
Malononitrile derivative, thiopyran derivative, trinitrothioxanthone derivative, 3,4,5,7-tetranitro-9-fluorenone derivative, dinitroanthracene derivative, dinitroacridine derivative, nitroantaraquinone derivative, dinitroanthraquinone derivative, tetracyanoethylene, 2, 4,8-trinitrothioxanthone,
Various compounds having an electron accepting property such as dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride, and dibromomaleic anhydride are exemplified.

In particular, the electron transporting agent may be any one of the general formulas [8], [9], [10], [11], [12], [13] and [14]. ] It is preferable to contain the compound shown by these.

General formula [8];

Embedded image (In the general formula [8], R ⁸⁰ and R ⁸¹ represent the same or different alkyl groups which may have a substituent.)

General formula [9];

Embedded image (In the general formula [9], R ⁹⁰ and R ⁹¹ represent the same or different monovalent hydrocarbon groups which may have a substituent.)

General formula [10];

Embedded image (In the general formula [10], R ¹⁰⁰ represents a halogen atom, an alkyl group or an aryl group which may have a substituent,
¹⁰¹ represents an alkyl group or an aryl group which may have a substituent, or a group: -OR ^101a . R ^101a represents an alkyl group or an aryl group which may have a substituent. )

General formula [11];

Embedded image (In the general formula [11], R ¹¹⁰ , R ¹¹¹ , R ¹¹² and R ¹¹³ are
It represents the same or different alkyl groups which may have a substituent. )

General formula [12];

Embedded image (In the general formula [12], R ^{120 to} R ¹²³ are the same or different and each represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms,
To 12 alkoxy groups, aryl groups which may have a substituent, cycloalkyl groups, aralkyl groups which may have a substituent, and halogenated alkyl groups. The substituent represents a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a hydroxyl group, a cyano group, an amino group, a nitro group, or a halogenated alkyl group. )

General formula [13];

Embedded image (In the general formula [13], R ¹³⁰ and R ¹³¹ are the same or different and each represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms,
To 12 alkoxy groups, aryl groups which may have a substituent, cycloalkyl groups, aralkyl groups which may have a substituent, and halogenated alkyl groups. R ^{132 to} R ¹³⁶ are
Same or different, hydrogen atom, halogen atom, carbon number 1
Alkyl group of 12 to 12, alkoxy group having 1 to 12 carbon atoms,
It represents an aralkyl group which may have a substituent, a phenoxy group which may have a substituent, and an alkyl halide group, and two or more groups may combine to form a ring. The substituent represents a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a hydroxyl group, a cyano group, an amino group, a nitro group, or a halogenated alkyl group. )

General formula [14];

Embedded image (In the general formula [14], R ^{140 to} R ¹⁴³ are the same or different and are each a hydrogen atom, an alkyl group having 1 to 12 carbon atoms,
To 12 alkoxy groups, aryl groups which may have a substituent, cycloalkyl groups, aralkyl groups which may have a substituent, and halogenated alkyl groups. R ¹⁴⁴ and R ¹⁴⁵ are
The same or different and represent a hydrogen atom and an alkyl group having 1 to 12 carbon atoms. R ^{146 to} R ¹⁵³ are the same or different and are a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group which may have a substituent, a halogenated alkyl group; Is shown. The substituent is a halogen atom, an alkyl group having 1 to 6 carbon atoms, 1 to 6 carbon atoms.
Represents an alkoxy group, a hydroxyl group, a cyano group, an amino group, a nitro group, and a halogenated alkyl group. )

An electron represented by the above general formula [8], general formula [9], general formula [10], general formula [11], general formula [12], general formula [13] or general formula [14] The transport agent has an extremely high mobility and efficiently transports electrons, and thus is effective for improving the sensitivity of the photoreceptor.

The electron transporting agent may be used alone or in combination of two or more.

The thickness of the photosensitive layer is 5 to 100 μm, more preferably 15 to 100 μm.
About 50 μm is preferable. The charge generating agent is 0.1 to 50% by weight based on the total weight of the binder resin, and more preferably 0.5 to 50% by weight.
It is preferable to contain 30 wt%. The electron transporting agent is preferably contained in an amount of 1 to 100% by weight, more preferably 5 to 80% by weight based on the total weight of the binder resin. The hole transport agent is 5 to 500 wt% based on the total weight of the binder resin,
More preferably, the content is 25 to 200 wt%.
The total amount of the electron transporting agent and the hole transporting agent is 20 to 500% by weight, and more preferably 30 to 200 w
It is preferable to contain t%.

Further, the total amount of the electron transporting agent and the hole transporting agent is most preferably 40 to 100% by weight based on the binder resin. Since the charge transport agent acts as a plasticizer in the binder resin, when the content of the charge transport agent increases, the abrasion resistance of the photosensitive layer decreases. For this reason, it is ideal to reduce the solid content concentration of the charge transport agent in order to improve the abrasion resistance, but inevitably the electrical characteristics such as the charging stability and the sensitivity are lowered.

However, by using an arbitrary charge transporting agent having a large hole or electron transporting ability, such as the compounds represented by the general formulas [4] to [14], 40 to 100 wt% of the binder resin can be obtained. Even with a low solid content, sufficient sensitivity can be obtained even with a single-layer type photoreceptor.

In the photosensitive layer, in addition to the components described above, various conventionally known additives such as an antioxidant, a radical scavenger, a singlet quencher, Deterioration inhibitors such as UV absorbers, softeners,
Plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, acceptors, donors, and the like can be added. Also, in order to improve the sensitivity of the photosensitive layer, for example,
Known sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene may be used in combination with the charge generator.

A barrier layer may be formed between the support and the photosensitive layer as long as the characteristics of the photosensitive member are not impaired.

As the support on which the photosensitive layer is formed, various conductive materials can be used.
Iron, aluminum, copper, tin, platinum, silver, vanadium,
Molybdenum, chromium, cadmium, titanium, nickel,
Examples of the material include simple metals such as palladium, indium, stainless steel, and brass; plastic materials on which the above metals are deposited or laminated; glass coated with aluminum iodide, tin oxide, indium oxide, and the like.

The support may be in the form of a drum, and the support itself may have conductivity, or the surface of the support may have conductivity. The support preferably has a sufficient mechanical strength when used.

When the photosensitive layer is formed by a coating method, the above-described charge generating agent, charge transporting agent, binder resin and the like are used together with a suitable solvent in a known manner, for example, a roll mill, a ball mill, an attritor, a paint coater. What is necessary is just to disperse and mix using an acre, an ultrasonic disperser or the like to prepare a dispersion, apply it by a known means, and dry it.

As the solvent for preparing the dispersion, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol, and aliphatic solvents such as n-hexane, octane and cyclohexane. Hydrocarbons, aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride, and chlorobenzene; dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether. Ethers, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and methyl acetate, dimethylformaldehyde, dimethylformamide, dimethyls Rufoxide and the like. These solvents are used alone or in combination of two or more.

Further, a surfactant, a leveling agent and the like may be used in order to improve the dispersibility of the charge generating agent, the charge transporting agent and the like and the smoothness of the surface of the photosensitive layer.

[0069]

The present invention will be described below with reference to examples and comparative examples. Note that the following embodiments are merely examples embodying the present invention, and do not limit the technical scope of the present invention.

[Image Forming Apparatus] FIG. 2 schematically shows an image forming apparatus of the present invention provided with a blade type cleaning device. The image forming apparatus includes a photoconductor (positively charged single-layer OPC) drum 21 that rotates in the direction of arrow 22. A cleaning device 27 provided with a main charger 23, an exposure device 24, a developing device 25, a transfer roller 26, and a cleaning blade 28 is arranged around the photoreceptor drum 21 in order along the rotation direction 22. .

At the time of image formation, the photosensitive drum 21 is rotationally driven in the direction of arrow 22 at a constant speed (peripheral speed: 110 mm / sec), and the surface of the photosensitive drum 21 has a predetermined potential (discharged) by the discharge of the main charger 23. 850 V). The positively charged surface faces the exposure device 24 by the rotation of the photosensitive drum 21 and is exposed to light corresponding to an image to be formed. This allows
A high potential area and a low potential area are formed on the surface of the photoconductor drum 21, and a so-called electrostatic latent image is formed. When the photosensitive drum 21 further rotates, the electrostatic latent image formed on the surface thereof faces the developing device 25 and is developed by toner. When the toner image reaches a position facing the transfer roller 26, the toner image is transferred onto the transferred transfer paper P.

Normally, a part of the toner remains on the surface of the photosensitive drum 21 after the transfer without being transferred to the transfer paper P. When the photosensitive drum 21 is further rotated and the surface to which the residual toner adheres faces the cleaning device 27, the residual toner is collected by the cleaning device 27.

Specifically, the cleaning device 27 includes:
A cleaning blade 28 (made of urethane rubber) that is long in the axial direction of the photoconductor drum 21 is provided, and the leading edge thereof is pressed over almost the entire width of the surface of the photoconductor drum 21. The residual toner is scraped off the surface of the photosensitive drum 21 by the cleaning blade 28. The cleaning blade 28 is bonded to a blade holder 29 formed by bending an iron plate into an L-shaped cross section.

In the above-described image forming apparatus, the pressing force f of the cleaning blade 28 against the photosensitive drum 21
(G / cm) and the pressure contact angle θ (°), and the following various positively charged single-layer type photoconductor drums are used as the photoconductor drum 21 to obtain abrasion resistance, toner fusion, drum squeal or The blade was turned up and evaluated.

[Production of Single Layer Photoreceptor and Printing Test] [Examples 1 to 42] [Comparative Examples 1 to 24] X-type metal-free phthalocyanine (Pc) was used as a charge generating agent.
H ₂₎ 4.5 parts by weight, the electron transport agent (ETM-1) 30 parts by weight, the hole transport agent (HTM-1) 55 parts by weight, weight average molecular weight of 100,000 of the binder resin (Resin
-1 to -3) 100 parts by weight of tetrahydrofuran 70
The mixture was dispersed or dissolved together with 0 parts by weight in a ball mill for 24 hours to prepare a single-layer type photosensitive layer coating solution. And
This coating solution is applied on an aluminum tube as a support by a dip coating method, and dried with hot air at 125 ° C. for 45 minutes to produce a single-layer type photoreceptor having a single photosensitive layer with a thickness of 35 μm. Then, it was mounted on a facsimile machine (a modified model of the Creation 8331 manufactured by Kyocera Mita Corporation) having the configuration shown in FIG. 2, and a printing test described later was performed.

[ETM-1]

Embedded image

[HTM-1]

Embedded image

[Resin-1]

Embedded image

[Resin-2]

Embedded image

[Resin-3]

Embedded image

With respect to the single-layer type photoreceptors of the above Examples and Comparative Examples, abrasion resistance, toner fusion, drum squeal or blade curling were evaluated by the following tests.

[Abrasion Resistance Evaluation Test] The single-layer type photoreceptor of each of the above Examples and Comparative Examples was mounted on a FAX machine having a configuration shown in FIG. A printing test of 100,000 sheets (paper A4 lengthwise) was performed while changing the linear pressure (f) and the pressure contact angle (θ). Then, the film thickness of the photosensitive layer before and after the test was measured, and the amount of change in film thickness (amount of wear) was calculated. The smaller the wear amount, the better the wear resistance. Regarding the amount of wear, 3.0 μm or less was acceptable, and the case where it was larger than 3.0 μm was not acceptable.

[Drum Squeal and Blade Roll-Up Evaluation Test] During the above-described 100,000-sheet printing test, the occurrence of drum squeal and blade roll-up was examined every 1000 sheets. It can be evaluated that the larger the number of images printed before the occurrence of the problem, the less likely it is for the drum to squeal or the blade to roll up. It is not possible to make a defect when the number of prints is less than 50,000.

[Dash mark, toner filming evaluation test] During the above-mentioned 100,000-sheet printing test, 10
Using a blank document for every 00 sheets, an A4 horizontal printing test was performed to check for the occurrence of dash marks or toner filming at both ends of the drum. During the A4 vertical printing test,
Dash marks or toner filming are likely to occur at both ends of the drum, which is a non-image forming portion, and when it occurs, the toner attached portion appears as a noise image. It can be evaluated that the larger the number of printed images until the occurrence of the problem, the more likely it is that the dash mark or toner filming is unlikely to occur in the single-layer type photoconductor. It is not possible to make a defect when the number of prints is less than 50,000.

Tables 1 to 6 show the results of the above evaluation tests.
1 to 6 are graphs of Tables 1 to 6, wherein the blade linear pressure / pressure contact angle-amount of wear (FIGS. 1, 4), the blade linear pressure / pressure contact angle-dash mark or the number of toner filming occurrences. (FIGS. 2 and 5), the relationship between the blade linear pressure / pressure contact angle and the number of drum squeals or blade roll-ups (FIGS. 3 and 6) are shown. Note that the data that the number of dash marks or toner filming occurrences and the number of drum squeal or blade roll-up occurrences are 100,000 are the number of printings of 10
If the above failure occurs at the time of 10,000 sheets, or 10
Either the failure did not occur in the printing test of 10,000 sheets.

[0086]

[Table 1]

[0087]

[Table 2]

[0088]

[Table 3]

[0089]

[Table 4]

[0090]

[Table 5]

[0091]

[Table 6]

1 and 4, there is a correlation between the amount of wear and the blade linear pressure or the blade contact angle, and as the blade linear pressure or the contact angle increases, the amount of wear increases and the wear resistance deteriorates. .

When the linear pressure was 20 g / cm or less or the pressure contact angle was 30 ° or less, the abrasion loss of all the single-layer type photosensitive members was 3 μm or less.

In particular, when Resin-1 and -2 are used as the binder resin of the single-layer type photosensitive member, Resin-
In comparison with the case of using No. 3, the amount of wear was small and the wear resistance was good. This is presumably because the repeating structural unit (biphenyl-type polycarbonate) represented by the general formula [1] effectively acted to improve the abrasion resistance.

2 and 5, when the linear pressure is 8 g / cm or more or the pressure contact angle is 12 ° or more, dash marks or toner fills are obtained in all the single-layer type photoconductors within 50,000 sheets. No ming occurred. Further, when the linear pressure was 10 g / cm or more, or the pressure contact angle was 15 ° or more, the problem did not occur within 80,000 copies of all the single-layer type photoreceptors.

In particular, when Resin-2 is used, R
Compared to the case where esin-1 was used, there was a tendency that the number of printed sheets before the occurrence of a defect at the same line pressure or the same pressure contact angle was larger. This is presumably because the repeating structural unit (siloxane-containing polycarbonate) represented by the general formula [3] reduced the surface energy of the single-layer type photoreceptor, and was effective in preventing toner fusion.

On the other hand, when Resin-3 was used, toner fusion was most difficult to occur. This is Resin-
It is considered that the single-layer type photoreceptor using No. 3 has poor abrasion resistance, and the fused toner is easily scraped off together with the photosensitive layer.
From this result, it was found that toner abrasion easily occurs when the abrasion resistance is improved.

3 and 6, the linear pressure is 20 g / cm or less.
Alternatively, when the pressure contact angle was 30 ° or less, no drum squeal or blade roll-up occurred in all the single-layer type photoconductors within 50,000 copies. Further, when the linear pressure was 18 g / cm or less, or the pressure contact angle was 25 ° or less, all of the single-layer type photoreceptors did not have this problem when the number of printed sheets was 80,000 or less.

In particular, when Resin-2 is used, R
Compared to the case where esin-1 and -3 were used, the number of prints until drum squeal or blade roll-up at the same linear pressure or the same pressure contact angle was generated was clearly larger. This is presumably because the repeating structural unit (siloxane-containing polycarbonate) represented by the general formula [3] improved the surface lubricity of the single-layer type photoreceptor and effectively acted to reduce the friction coefficient with the blade.

From the above results, the blade linear pressure was 8 g / c.
m or more and 20 g / cm or less, and the blade contact angle is 12
At least 30 ° and at most 30 °, all single-layer type photoconductors have a wear amount of 3 μm or less, and the number of prints is within 50,000 sheets, and there is no occurrence of dash marks or toner filming, drum squeal or blade curling. Was.

In particular, when the blade linear pressure is 10 g / cm or more and 1
8 g / cm or less, the blade pressure contact angle is 15 ° or more and 25 ° or less, and in all the photoconductors,
There was no dash mark, toner filming, drum squeal or blade roll-up, and a more favorable result was obtained.

When the binder resin of the single-layer type photoreceptor contains a polycarbonate resin having a repeating structural unit of the general formula [1] or [3] (Re
sin-1 or Resin-3), improved wear resistance,
It was more effective in preventing drum squeal or blade roll-up.

[0103]

A charging means is provided around a rotatable image carrier.
An image forming apparatus, comprising: an exposing unit, a developing unit, a transferring unit, and a cleaning unit, wherein the toner remaining on the surface of the image carrier after developing and transferring is removed by the cleaning unit. Cleaning means
An elastic blade held by a support member and having a linear pressure of 8 g / cm or more and 20 g / cm or less with an abutting pressure on the surface of the image bearing member; At least 12 ° and not more than 30 °, wherein the image carrier is an organic photoreceptor having a photosensitive layer made of a binder resin containing at least a charge generating agent and a charge transporting agent on a conductive substrate. In the image forming apparatus, the occurrence of dash marks, toner filming, blade squeal, and blade curling is small, the abrasion resistance of the organic photoreceptor is good, and the life is long.

Further, the linear pressure is 10 g / cm or more and 18
g / cm or less, or when the pressure contact angle is 15 ° or more and 25 ° or less, a dash mark, toner filming,
It is even more effective in preventing the occurrence of blade squeal and blade curling and the prevention of film shaving of the organic photoreceptor.

On the other hand, the organic photoreceptor as the image carrier has a repeating structural unit represented by the general formula [1] and a repeating structural unit represented by the general formula [2] as a binder resin of the outermost surface layer. Polymerized polycarbonate resin or copolymerized polycarbonate resin having a repeating structural unit represented by general formula [1], a repeating structural unit represented by general formula [2], and a repeating structural unit represented by general formula [3] When it is contained, it is particularly effective for preventing the occurrence of dash marks, toner filming, blade squealing or blade curling, the abrasion resistance of the organic photoreceptor is remarkably good, and the life is further extended.

[0106]

[Brief description of the drawings]

FIG. 1 is a partial explanatory view of an image forming apparatus of the present invention showing a state in which a cleaning blade is brought into contact with a photosensitive member.

FIG. 2 is a simplified cross-sectional view showing an internal configuration of an image forming apparatus of the present invention provided with a blade-type cleaning device.

FIG. 3 is a graph showing a relationship between a blade linear pressure f and a wear amount when a blade contact angle θ is constant (18 °).

FIG. 4 is a graph showing the relationship between the blade linear pressure f and the number of printed sheets where a dash mark or toner filming occurs when the blade contact angle θ is constant (18 °).

FIG. 5 is a graph showing the relationship between the blade linear pressure f and the number of prints at which drum squeal or blade curling occurs when the blade pressure contact angle θ is constant (18 °).

FIG. 6 is a graph showing the relationship between the blade contact angle θ and the amount of wear when the blade linear pressure f is constant (11 g / cm).

FIG. 7 is a graph showing the relationship between the blade contact angle θ and the number of printed sheets where a dash mark or toner filming occurs when the blade linear pressure f is constant (11 g / cm).

FIG. 8 is a graph showing the relationship between the blade contact angle θ and the number of prints at which drum squeal or blade curling occurs when the blade linear pressure f is constant (11 g / cm).

Continued on the front page F term (reference) 2H068 AA03 AA13 AA14 AA20 AA21 AA31 BA63 BA64 BB20 BB26 BB33 BB53 FA03 FC15 FC20 2H134 GA01 GB02 GB08 HD05 HD11 KG08 KH01 KH05 KH15

Claims (9)

[Claims] An image bearing member includes a charging unit, an exposing unit, a developing unit, a transferring unit, and a cleaning unit in order around a rotatable image carrier. Is an image forming apparatus that is removed by the cleaning unit, wherein the cleaning unit is held on a support member and has a linear pressure of 8 g / cm or more and 2 g / cm 2 or more.
An elastic blade that is in contact with the surface of the image carrier at a contact pressure of 0 g / cm or less, and a pressure contact angle of the elastic blade is 12 ° or more and 30 ° or less; An image forming apparatus comprising: an organic photoreceptor having a photosensitive layer made of a binder resin containing at least a charge generating agent and a charge transporting agent on a conductive substrate. 2. The method according to claim 1, wherein the linear pressure is 10 g / cm or more and 18 g / cm.
The image forming apparatus according to claim 1, wherein: 3. The image forming apparatus according to claim 1, wherein said pressure contact angle is not less than 15 ° and not more than 25 °. 4. The image forming apparatus according to claim 1, wherein the peripheral speed of the image carrier is 90 mm / sec or more and 300 mm / sec or less. 5. An organic photoreceptor as the image bearing member having a repeating structural unit represented by the general formula [1] and a repeating structural unit represented by the general formula [2] as a binder resin of the outermost surface layer. 5. The image forming apparatus according to claim 1, further comprising a polymerized polycarbonate resin. General formula [1]; (In the general formula [1], R ¹⁰ and R ¹¹ are the same or different and each represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.) General formula [2]; (In the general formula [2], R ²⁰ and R ²¹ are the same or different and represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a phenyl group, and R ²² and R ²³ are the same or different and represent a carbon atom. Number 1
And alkyl groups, phenyl groups, and cycloalkylidene groups which may form a ring and have a substituent. ) 6. An organic photoreceptor as an image bearing member, wherein a binder resin for the outermost surface layer comprises a repeating structural unit represented by the general formula [1] and a repeating structural unit represented by the general formula [2]; 5. The image forming apparatus according to claim 1, further comprising a copolymerized polycarbonate resin having a repeating structural unit represented by the formula [3]. General formula [3]; (In the general formula [3], X ³⁰ , X ³¹ , and X ³² are the same or different and are — (CH ₂ ) _n —, n is an integer of 1 to 6, and R
³⁰ , R ³¹ , R ³² , and R ³³ are the same or different and each represent a hydrogen atom, a phenyl group, an alkyl group or an alkoxy group having 1 to 3 carbon atoms, and m represents a numerical value of 0 to 200. ) 7. The organic photoreceptor as the image bearing member contains 10 to 50 mol% of the repeating structural unit represented by the general formula [1] based on the total amount of the binder resin in the outermost surface layer. The image forming apparatus according to claim 5. 8. The organic photoreceptor as the image carrier contains 0.05 to 10 mol% of the repeating structural unit represented by the general formula [3] based on the total amount of the binder resin in the outermost surface layer. The image forming apparatus according to claim 6, wherein: 9. A single-layer type wherein the organic photoreceptor serving as the image carrier has a single photosensitive layer comprising a binder resin containing at least a charge generating agent, a hole transporting agent and an electron transporting agent on a conductive substrate. 9. A photosensitive member.
The image forming apparatus as described in the above.