JP2007147824A - Electrophotographic photoreceptor and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having excellent crack resistance and sensitivity characteristics and capable of keeping preferable image characteristics for a long period of time, and to provide an image forming apparatus having the photoreceptor. <P>SOLUTION: The electrophotographic photoreceptor has a photosensitive layer containing a charge generating agent, a hole transporting agent, an electron transporting agent and a binder resin on a conductive substrate, wherein the total add amount of the hole transporting agent and the electron transporting agent is in a range of 100 to 150 parts by weight with respect to 100 parts by weight of the binder resin, and the hole transporting agent contains a hole transporting agent having the molecular weight of 700 to 1,200. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member and an image forming apparatus including the same. In particular, the present invention relates to an electrophotographic photosensitive member that is excellent in stain resistance and can suppress generation of exposure memory for a long period of time, and an image forming apparatus including the same.

Conventionally, as an electrophotographic photosensitive member used in an image forming apparatus, a charge generating agent for generating a charge by light irradiation, a charge transporting agent for transporting the generated charge, and these substances are dispersed. An organic photoreceptor containing a binder resin for forming a layer is widely used.
An image forming apparatus used for such an organic photoconductor includes a charging unit for charging the surface of the photoconductor, an exposure unit for irradiating the charged surface with light to form a latent image, and the latent image. An image forming process is employed in which a developing unit for developing a toner image to form a toner image and a transfer unit for transferring the toner image onto printing paper are sequentially arranged.
In this image forming process, in order to erase the residual charge remaining on the surface of the photoconductor after transfer, there is provided a neutralizing means for neutralizing by irradiation with light. Thereby, even if it is used repeatedly, the potential remaining until the previous round can be reset to suppress the occurrence of so-called transfer memory and exposure memory.
However, even when such a method is used, space charges are generated inside the photoconductor, and when used repeatedly, the space charges are accumulated in the photoconductor to obtain certain image characteristics. The problem of disappearing was seen.

Therefore, in order to solve such problems, by using a specific electron transport agent and using a terphenyl compound as an additive, the occurrence of a transfer memory is small even when the reversal development method is used, A positively charged single layer type electrophotographic photosensitive member having improved gas resistance against NOx, ozone and the like is disclosed. (For example, see Patent Document 1)
Further, an electrophotographic photosensitive member is disclosed in which a biphenyl derivative is contained as an additive in the photosensitive layer, thereby improving the repeated stability of electric characteristics in positive charging. (For example, see Patent Document 2)
JP-A-2001-242656 (Claims) JP 2000-314969 (Claims)

  However, even when such a photoconductor is used, depending on the use conditions and the like, there is still a case where residual charges are generated in the photosensitive layer after transfer. Further, in the process of repeated use in this way, if contaminating components originating from the human body or from the contact member of the photoconductor adhere to the surface of the photoconductor, cracks are generated as a starting point and the image characteristics are deteriorated. Was also seen. Furthermore, since these photoconductors require a method of erasing residual charges using an electricity removing unit as an image forming system, there is a problem that it is difficult to cope with downsizing of the apparatus.

Therefore, as a result of intensive studies, the inventors of the present invention set the total addition amount of the hole transporting agent and the electron transporting agent as the charge transporting agent within a predetermined range and a positive molecular weight having a predetermined molecular weight. It has been found that by incorporating a hole transport agent, elution of the hole transport agent into contaminating components can be prevented while maintaining the charge transport capability in the photosensitive layer.
That is, an object of the present invention is to provide an electrophotographic photosensitive member that can maintain good image characteristics over a long period of time and is excellent in stain resistance and crack resistance, and an image forming apparatus including the same. And

According to the electrophotographic photoreceptor of the present invention, an electrophotographic photoreceptor comprising a photosensitive layer containing a charge generator, a hole transport agent, an electron transport agent, and a binder resin on a conductive substrate. The total amount of the hole transporting agent and the electron transporting agent is set to a value within the range of 100 to 150 parts by weight with respect to 100 parts by weight of the binder resin, and the hole transporting agent has a molecular weight of 700. An electrophotographic photoreceptor comprising a hole transporting agent having a value in the range of ˜1200 is provided, and the above-described problems can be solved.
That is, by making the total addition amount of the hole transporting agent and the electron transporting agent a predetermined amount, while maintaining the charge transporting ability in the photoconductor, and further containing a hole transporting agent of a predetermined molecular weight, It is possible to prevent a decrease in crack resistance accompanying the addition of a predetermined amount of the agent.
Therefore, if such a photoreceptor having excellent charging characteristics and anti-contamination properties can maintain good image characteristics over a long period of time, and also suppress the occurrence of exposure memory, a static elimination-less system is adopted. This can contribute to downsizing of the device.

In constituting the present invention, when the hole transporting agent is the first hole transporting agent, it is preferable to further include a second hole transporting agent having a molecular weight of less than 700.
By comprising in this way, the dispersibility in a photosensitive layer is improved with the 2nd hole transport agent, suppressing generation | occurrence | production of exposure memory, suppressing the elution to a contaminating component by the 1st hole transport agent. Can be suppressed.
Therefore, the crack resistance obtained by increasing the molecular weight and the improvement of the dispersibility obtained by reducing the molecular weight, that is, the suppression of the exposure memory can be effectively exhibited.

In configuring the present invention, the amount of the first hole transport agent added is preferably set to a value in the range of 30 to 130 parts by weight with respect to 100 parts by weight of the binder resin.
By comprising in this way, the elution amount to the contaminating component of a positive hole transport agent can be controlled to the quantity in a predetermined range, and the photosensitive layer excellent in stain resistance and crack resistance can be formed.

In configuring the present invention, the amount of the electron transport agent added is preferably set to a value within the range of 20 to 60 parts by weight with respect to 100 parts by weight of the binder resin.
By comprising in this way, the content balance of a hole transport agent and an electron transport agent can be maintained in a predetermined range, and the charge transport ability of a photosensitive layer can be improved effectively.

  In constituting the present invention, the photosensitive layer preferably contains a compound represented by the following general formula (1) as an additive.

（一般式（１）中、Ｒ¹〜Ｒ¹⁰はそれぞれ独立しており、水素原子、ハロゲン原子、置換または非置換の炭素数１〜１２のアルキル基、置換または非置換の炭素数１〜１２のアルコキシ基、置換または非置換の炭素数６〜３０のアリール基、置換または非置換の炭素数６〜３０のアラルキル基、置換または非置換の炭素数３〜１２のシクロアルキル基、ヒドロキシル基、シアノ基、ニトロ基、アミノ基であり、Ｒは、置換または非置換の炭素数１〜１２のアルキレン基を示し、ｎは０〜３の整数を示す。）

(In General Formula (1), R < ¹ > -R < ¹⁰ > is respectively independent, a hydrogen atom, a halogen atom, a substituted or unsubstituted C1-C12 alkyl group, a substituted or unsubstituted C1-C12 An alkoxy group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 30 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 12 carbon atoms, a hydroxyl group, A cyano group, a nitro group, and an amino group, R represents a substituted or unsubstituted alkylene group having 1 to 12 carbon atoms, and n represents an integer of 0 to 3).

  By comprising in this way, it can suppress generation | occurrence | production of a crack because a compound (1) acts on the part to which the contaminating component adhered, and it combines with containing the hole transport agent of predetermined molecular weight, Furthermore, crack resistance can be improved effectively.

In constituting the electrophotographic photosensitive member of the present invention, the additive is preferably a compound represented by the following formulas (2) to (7) or a derivative thereof.
By comprising in this way, the stress which arises in a photosensitive layer can be relieve | moderated more effectively, and crack resistance can be improved.

In constituting the electrophotographic photosensitive member of the present invention, it is preferable that the amount of the additive is set to a value within the range of 5 to 15% by weight with respect to the solid content of the photosensitive layer.
By comprising in this way, the addition amount of an additive can be adjusted corresponding to the elution amount of a hole transport agent, and generation | occurrence | production of a crack can be prevented effectively.
Further, since the glass transition point of the photosensitive layer may decrease as the additive amount increases, the glass transition point can be controlled and the wear resistance can be controlled by controlling the value within such a range. Sex can also be maintained.

In constituting the electrophotographic photosensitive member of the present invention, the photosensitive layer is preferably a single layer type.
With this configuration, the present invention can be applied to both positive and negative charge types, and a simple layer configuration can improve productivity.

According to another aspect of the present invention, there is provided an image forming apparatus including any one of the electrophotographic photosensitive members described above, and a charging unit, an exposing unit, a developing unit, and a transfer unit are disposed around the electrophotographic photosensitive member. In addition, a static elimination-less type image forming apparatus in which the static elimination means is omitted.
That is, a photoconductor that contains a hole transport agent having a predetermined molecular weight and that defines a total addition amount of the hole transport agent and the electron transport agent within a predetermined range is applied to an image forming apparatus equipped with a static elimination-less system. By applying the image forming apparatus, it is possible to provide an image forming apparatus excellent in crack resistance and wear resistance while suppressing generation of exposure memory. Therefore, the image forming apparatus can be reduced in size and the number of parts can be reduced to reduce the cost.

[First Embodiment]
The first embodiment of the present invention is an electrophotographic photoreceptor comprising a photosensitive layer containing a charge generating agent, a hole transporting agent, an electron transporting agent, and a binder resin on a conductive substrate. The total amount of the hole transport agent and the electron transport agent is set to a value within the range of 100 to 150 parts by weight with respect to 100 parts by weight of the binder resin, and the molecular weight of the hole transport agent is 700 to An electrophotographic photosensitive member comprising a hole transporting agent having a value within a range of 1200.
Hereinafter, the single layer type electrophotographic photosensitive member according to the first embodiment of the present invention will be described in detail.

1. Basic Configuration As shown in FIG. 1A, a single-layer electrophotographic photosensitive member 10 has a single photosensitive layer 14 provided on a conductive substrate 12.
The photosensitive layer 14 is formed by applying a coating solution in which a charge generating agent, an electron transporting agent, a hole transporting agent, a binder resin, and an additive are dissolved or dispersed in a predetermined solvent on the conductive substrate 12. It can be formed by applying to and drying.
Such a single-layer type photoreceptor 10 is applicable to both positive and negative charge types, has a simple layer structure, and can suppress film defects when forming a photosensitive layer, so that it has excellent productivity. ing. Moreover, since there are few interfaces between layers, optical characteristics can be improved.
In addition, as illustrated in FIG. 1B, a single-layer type photoreceptor 10 ′ in which an intermediate layer 16 is formed between the photosensitive layer 14 and the conductive substrate 12 may be used.
Further, the thickness of the photosensitive layer 14 is usually a value in the range of 5 to 100 μm, preferably a value in the range of 10 to 50 μm.

2. Conductive substrate As the conductive substrate 12 illustrated in FIG. 1, various conductive materials can be used. For example, iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, Examples thereof include metals such as titanium, nickel, palladium, indium, stainless steel, and brass, plastic materials on which the above metal is vapor-deposited or laminated, glass coated with aluminum iodide, tin oxide, indium oxide, and the like.
Further, the shape of the support substrate may be any of a sheet shape, a drum shape, or the like in accordance with the structure of the image forming apparatus to be used. The substrate itself has conductivity or the surface of the substrate has conductivity. It only has to have. Further, it is preferable that the support substrate has sufficient mechanical strength when used. In the case of a drum shape, the diameter of the conductive substrate is preferably 10 to 60 mm, more preferably 10 to 27 mm, from the viewpoint of miniaturization of the apparatus.

Further, in order to prevent the occurrence of interference fringes, the surface of the support substrate is roughened using a method such as etching, anodizing, wet blasting, sand blasting, rough cutting, or centerless cutting. It is preferable.
If anodization or the like is performed on the conductive substrate, it may become non-conductive or semiconductor characteristics. However, even in such a case, the conductive substrate may have a predetermined effect. Can be included.

3. Intermediate Layer Further, as shown in FIG. 1B, an intermediate layer 16 containing a predetermined binder resin may be provided on the support base 12.
The reason for this is that the adhesion between the conductive substrate and the photosensitive layer is improved, and the addition of a predetermined fine powder in the intermediate layer can scatter incident light and suppress the generation of interference fringes. This is because it can. The fine powder is not particularly limited as long as it has light scattering properties and dispersibility, and examples thereof include white pigments such as titanium oxide, zinc oxide, zinc white, zinc sulfide, lead white, and lithopone. Inorganic pigments such as alumina, calcium carbonate, barium sulfate and the like, fluorine resin particles, benzoguanamine resin particles, styrene resin particles, and the like can be used.

Moreover, it is preferable that the film thickness of this intermediate layer is defined within a predetermined range. This is because if the intermediate layer is too thick, a residual potential is likely to be generated on the surface of the photoreceptor, which may cause a decrease in electrical characteristics. On the other hand, if the thickness of the intermediate layer becomes too thin, the unevenness on the surface of the support substrate cannot be sufficiently relaxed, and the adhesion between the support substrate and the photosensitive layer cannot be obtained.
Therefore, the thickness of the intermediate layer is preferably set to a value in the range of 0.1 to 50 μm, and more preferably set to a value in the range of 0.5 to 30 μm.

4). Charge generator In addition, examples of the charge generator in the present invention include phthalocyanine pigments such as metal-free phthalocyanine and oxotitanyl phthalocyanine, perylene pigments, bisazo pigments, diketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, and metal naphthalocyanine pigments. Organic photoconductivity such as phthalocyanine pigment, squaraine pigment, trisazo pigment, indigo pigment, azurenium pigment, cyanine pigment, pyrylium pigment, ansanthrone pigment, triphenylmethane pigment, selenium pigment, toluidine pigment, pyrazoline pigment, quinacridone pigment And conventionally known charge generating agents such as inorganic photoconductive materials such as selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, and amorphous silicon can be used.
More specifically, it is more preferable to use phthalocyanine pigments (CGM-A to CGM-D) represented by the following formulas (8) to (11).
This is because a photoreceptor having sensitivity in a wavelength region of 600 to 800 nm or more is required when used in a digital optical image forming apparatus such as a laser beam printer or a facsimile provided with a semiconductor laser as a light source. It is.
On the other hand, when used in an analog optical image forming apparatus such as an electrostatic copying machine having a white light source such as a halogen lamp, a photosensitive member having sensitivity in the visible region is required. Perylene pigments and bisazo pigments can be preferably used.

5. Hole transport agent (1) 1st hole transport agent Moreover, the hole transport agent used for this invention contains the hole transport agent whose molecular weight is a value within the range of 700-1200, It is characterized by the above-mentioned. . Hereinafter, the hole transport agent having a molecular weight in the range of 700 to 1200 will be described as the first hole transport agent.
Here, with reference to FIG. 3 and FIG. 4, the influence of the molecular weight of the first hole transport agent on crack resistance and image characteristics will be described.
First, FIG. 3 is a characteristic diagram showing the relationship between the molecular weight of the first hole transport agent and crack resistance. In this characteristic diagram, the horizontal axis represents the molecular weight of the first hole transport agent, and the vertical axis represents the crack growth rate, which is an index of crack resistance.
As can be understood from this characteristic diagram, it can be said that as the molecular weight of the first hole transport agent increases, the crack growth rate decreases and the crack resistance is improved. However, when the molecular weight is too large, the dispersibility of the hole transport agent in the photosensitive layer is lowered, which may be a factor in generating an exposure memory.
Therefore, the molecular weight range of the first hole transport agent is preferably 800 to 1100, more preferably 900 to 1000.
As an example of the method for measuring the crack growth rate in this characteristic diagram, the photosensitive layer is formed under the conditions described in Example 1 described later against oleic acid triglyceride having a behavior similar to that of the contamination component derived from the human body. There is a method in which the growth rate (mm / min) is obtained by dipping for a predetermined time and measuring the length (mm) of a crack generated on the surface of the photosensitive layer.

Next, FIG. 4 is a characteristic diagram showing the relationship between the molecular weight of the first hole transport agent and the image characteristics. In this characteristic diagram, the horizontal axis represents the molecular weight of the first hole transport agent, and the vertical axis represents the exposure memory potential, which is an index of image characteristics.
As can be understood from the characteristic diagram, there is a quadratic correlation between the molecular weight of the first hole transport agent and the exposure memory, and the first hole transport agent having a molecular weight within a predetermined range. It can be said that the exposure memory is improved by using.
This is presumably because when the molecular weight of the first hole transport agent is increased, the dispersibility is lowered, the hole transport agent is localized inside the photosensitive layer, and the generation of exposure memory is increased.
Conversely, if the molecular weight is decreased, the number of molecular ends is excessively increased, the charge transport ability is lowered, and exposure memory is likely to be generated.
Therefore, the molecular weight range of the first hole transport agent is preferably 800 to 1100, more preferably 900 to 1000.
In addition, the molecular weight of the hole transport agent may be a value calculated based on the structural formula, or may be determined using a GPC method or the like.

(1) -1 Types The first hole transport agent used in the present invention is not particularly limited as long as it satisfies the above-mentioned molecular weight conditions. For example, benzidine compounds, phenylenediamines are used. Compounds, naphthylenediamine compounds, phenanthrylenediamine compounds, oxadiazole compounds, styryl compounds, carbazole compounds, pyrazoline compounds, hydrazone compounds, triphenylamine compounds, indole compounds, oxazole compounds Compound, isoxazole compound, thiazole compound, thiadiazole compound, imidazole compound, pyrazole compound, triazole compound, butadiene compound, pyrene-hydrazone compound, acrolein compound, carbazole-hydrazone compound, key Phosphorus - hydrazone compounds, stilbene compounds, stilbene - hydrazone compounds, and alone or two or more combinations of di-phenylenediamine compounds.

(1) -2 Specific Example Specific examples of the first hole transport agent include compounds (HTM-1 to 5) represented by the following general formulas (12) to (16).

(1) -3 Addition Amount The addition amount of the first hole transport agent is preferably set to a value in the range of 30 to 130 parts by weight with respect to 100 parts by weight of the binder resin.
This is because when the amount of the hole transporting agent added is less than 30 parts by weight, the hole transporting ability of the photosensitive layer is extremely lowered, which may adversely affect image characteristics. However, when the added amount exceeds 130 parts by weight, there may be a problem that dispersibility is lowered and crystallization is likely to occur.
Therefore, the amount of the first hole transport agent added is preferably set to a value in the range of 35 to 100 parts by weight, and a value in the range of 40 to 80 parts by weight with respect to 100 parts by weight of the binder resin. More preferably.

(2) Second hole transport agent The hole transport agent used in the present invention is a second hole transport agent having a molecular weight of less than 700 in addition to the first hole transport agent described above. It is preferable to contain.
The reason is that the dispersibility can be improved while suppressing the elution to the contaminating component by containing the second hole transport agent having a relatively low molecular weight in addition to the first hole transport agent. This is because it can.
However, when the molecular weight of the second hole transport agent is excessively reduced, the contaminating components are likely to be eluted, and the crack resistance may be lowered.
Accordingly, the molecular weight range is preferably set to a value within the range of 100 to 600, and more preferably set to a value within the range of 200 to 500.
The second hole transport agent used in the present invention is also preferably used by mixing a plurality of hole transport agents having a molecular weight of less than 700 and different molecular structures.
This is because, by using a plurality of hole transport agents having a molecular weight of less than 700, a high charge transport ability can be effectively obtained by appropriately selecting a combination with an electron transport agent described later.

(2) -1 Type The second hole transport agent used in the present invention is not particularly limited as long as it satisfies the above-described solubility conditions. For example, benzidine compounds, phenylenediamine Compounds, naphthylenediamine compounds, phenanthrylenediamine compounds, oxadiazole compounds, styryl compounds, carbazole compounds, pyrazoline compounds, hydrazone compounds, triphenylamine compounds, indole compounds, oxazole compounds Compound, isoxazole compound, thiazole compound, thiadiazole compound, imidazole compound, pyrazole compound, triazole compound, butadiene compound, pyrene-hydrazone compound, acrolein compound, carbazole-hydrazone compound, key Phosphorus - hydrazone compounds, stilbene compounds, stilbene - hydrazone compounds, and alone or two or more combinations of di-phenylenediamine compounds.

(2) -2
Specific examples of the second hole transport agent include compounds (HTM-6 to 12) represented by the following general formulas (17) to (23).

(3) -3 Addition Amount of addition of the second hole transport agent is preferably 20 to 50 parts by weight or less with respect to 100 parts by weight of the binder resin.
The reason for this is that when the added amount of the hole transport agent exceeds 50 parts by weight, the dispersibility is improved, but when a contaminating component adheres, the hole transport agent is likely to be eluted and crack resistance is improved. This is because there is a case of lowering. Conversely, when the amount added is less than 20 parts by weight, the dispersibility of the hole transport agent is lowered.
Therefore, the amount of the second hole transfer agent added is preferably a value within the range of 25 to 45 parts by weight, and within a range of 30 to 40 parts by weight with respect to 100 parts by weight of the binder resin. More preferably, the value of

6). Electron transport agent The electron transport agent used in the present invention is not particularly limited, and examples thereof include benzoquinone compounds, naphthoquinone compounds, anthraquinone compounds, diphenoquinone compounds, dinaphthoquinone compounds, and naphthalenetetracarboxylic acids. Diimide compounds, fluorenone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, dinitroanthracene compounds, dinitroacridine compounds, nitroantharaquinone compounds, dinitroanthraquinone compounds, one or more The combination of these is mentioned.

(1) Specific example Moreover, the compound (ETM-1-6) represented by the following general formula (24)-(29) is mentioned as a specific example of an electron transfer agent.

(2) Addition amount The addition amount of the electron transfer agent is preferably set to a value within the range of 20 to 60 parts by weight with respect to 100 parts by weight of the binder resin.
This is because when the amount of the electron transport agent added is less than 20 parts by weight, the sensitivity is lowered and a practical problem may occur. On the other hand, when the added amount of the electron transport agent exceeds 60 parts by weight, the electron transport agent is likely to be crystallized, and an appropriate film as a photoreceptor may not be formed.
Therefore, the addition amount of the electron transport agent is preferably a value within the range of 30 to 45 parts by weight, and more preferably a value within the range of 35 to 40 parts by weight.
In such an electron transport agent, it is also preferable to use a plurality of electron transport agents having different molecular structures by mixing them at a predetermined ratio.
This is because by using a plurality of electron transport agents having different chemical structures, a suitable charge transport ability can be exhibited in combination with the hole transport agent described above.

7). The total addition amount of the hole transport agent and the electron transport agent In the present invention, the total addition amount of the hole transport agent and the electron transport agent described above is 100 to 150 weights with respect to 100 parts by weight of the binder resin. Part.
Here, with reference to FIG. 5 and FIG. 6, the influence of the total addition amount of the hole transport agent and the electron transport agent on crack resistance and image characteristics will be described.
First, FIG. 5 is a characteristic diagram showing the relationship between the total addition amount of the hole transport agent and the electron transport agent and the crack resistance. In this characteristic diagram, the horizontal axis represents the total addition amount of the hole transfer agent and the electron transfer agent, and the vertical axis represents the crack growth rate, which is an index of crack resistance.
As can be understood from the characteristic diagram, it can be said that as the total amount of the hole transport agent and the electron transport agent decreases, the crack growth rate decreases and the crack resistance is improved. However, if the amount added is too small, the charge transport capability of the photosensitive layer is significantly reduced, which can be a factor in generating an exposure memory.
Therefore, the range of the total addition amount of the hole transport agent and the electron transport agent is preferably a value in the range of 100 to 140 parts by weight, and more preferably a value in the range of 105 to 120.
As an example of the method for measuring the crack growth rate in this characteristic diagram, the photosensitive layer is formed under the conditions described in Example 1 described later against oleic acid triglyceride having a behavior similar to that of the contamination component derived from the human body. There is a method in which the growth rate (mm / min) is obtained by dipping for a predetermined time and measuring the length (mm) of a crack generated on the surface of the photosensitive layer.

Next, FIG. 6 is a characteristic diagram showing the relationship between the total addition amount of the hole transport agent and the electron transport agent and the image characteristics. In this characteristic diagram, the horizontal axis represents the total addition amount of the hole transport agent and the electron transport agent, and the vertical axis represents the exposure memory potential, which is an index of image characteristics.
As can be understood from the characteristic diagram, it can be said that as the total amount of the hole transport agent and the electron transport agent is increased, the exposure memory potential is decreased and the image characteristics are improved.
This is because the total amount of the hole transporting agent and the electron transporting agent, that is, the amount of the charge transporting agent added, increases the charge transporting ability in the photosensitive layer and reduces the residual charge on the surface of the photoreceptor. it is conceivable that.
However, when the amount of the charge transport agent added is increased in this way, in the case where a contaminating component adheres to the surface of the photoreceptor, the charge transport that is a monomer component in the photosensitive layer with respect to the contaminated component is performed. The agent may elute and cause cracks.
Therefore, the range of the total addition amount of the hole transport agent and the electron transport agent is preferably a value within the range of 100 to 140 parts by weight, and more preferably within the range of 105 to 120. .

8). Additives In the present invention, the photosensitive layer preferably contains a predetermined additive.
The reason for this is that when contaminants adhere to the surface of the photoconductor and vacancies are formed inside the photosensitive layer, the additive acts on these vacancies to release local stress and generate cracks. It is because it can suppress.

(1) Specific example Moreover, the compound (BP-1-6) represented by the following general formula (2)-(7) is mentioned as a specific example of an additive.

  Further, specific examples of the additive used in the present invention include compounds (BP-7 to 24) represented by the following general formulas (30) to (47) in addition to the compounds described above.

(2) Addition amount The addition amount of the additive in the present invention is preferably set to a value within the range of 5 to 15% by weight with respect to the solid content of the photosensitive layer.
The reason for this is that when the amount added exceeds 15% by weight, the glass transition point of the photosensitive layer is lowered, and the wear resistance may be lowered. Moreover, it is because the dispersibility in binder resin falls and the case where it crystallizes is seen.
However, when the addition amount is less than 5% by weight, the stress relaxation action as described above cannot be sufficiently exhibited, and crack generation cannot be sufficiently prevented.
Accordingly, the range of the addition amount is preferably 6 to 13% by weight, and more preferably 7 to 10% by weight.
The solid content of the photosensitive layer means a constituent component of the photosensitive layer excluding the solvent. In the present invention, the charge generating agent, the charge transporting agent, the binder resin, and the additive are combined. Means something.

(3) Molecular weight Moreover, it is preferable to make the molecular weight of this additive into the value within the range of 150-350.
This is because when the molecular weight is less than 150, the stress in the vicinity of the pores may not be released sufficiently.
Conversely, when the molecular weight exceeds 350, the dispersibility in the binder resin is lowered, and the interaction with the pores cannot be sufficiently exhibited.
Accordingly, the molecular weight range is preferably set to a value within the range of 200 to 300, and more preferably set to a value within the range of 230 to 270.
The molecular weight of the additive can be calculated based on, for example, the structural formula, or can be measured using a mass spectrum obtained with a mass spectrometer.

9. Binder Resin (1) Type The type of binder resin used in the electrophotographic photosensitive member of the present invention is not particularly limited. For example, polycarbonate resin, polyester resin, polyarylate resin, and styrene-butadiene copolymer are used. Polymer, 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, polyether resin, etc., silicone resin, epoxy resin, phenol resin, Urea resin, Ramin resin, other crosslinking thermosetting resins, epoxy acrylate, urethane - resin such as photocurable resin such as acrylate can be used.

(2) Weight average molecular weight The weight average molecular weight of the binder resin is not particularly limited. In the present invention, a hole transport agent having a predetermined molecular weight is used, and a hole transport agent and an electron are used. Since the crack resistance can be maintained by setting the total addition amount of the transport agent within a predetermined range, even when a relatively low molecular weight binder resin is used, the crack resistance and wear resistance thereof are used. The image characteristics can be maintained without lowering the image quality. However, if the weight average molecular weight is too low, the crack resistance may also be lowered.
Therefore, the range of the weight average molecular weight is preferably 70000 or less, and more preferably in the range of 20000 to 55000.
In addition, the weight average molecular weight of the binder resin can be obtained using a GPC method or the like.

(3) Specific example Moreover, as a specific example of binder resin, it is Z type polycarbonate resin (BD-1) represented by the following general formula (48).

10. Glass transition point In the electrophotographic photoreceptor of the present invention, the glass transition point (Tg) of the photosensitive layer is preferably set to a value of 60 ° C or higher.
This is because, as described above, when an additive is contained, the glass transition point of the photosensitive layer changes, which may affect the wear resistance.
That is, if the additive is excessively contained and the glass transition point is set to a predetermined value or less, the pressure resistance is lowered and the image characteristics may be adversely affected when used repeatedly. On the other hand, if the glass transition point becomes too high, the surface of the photoreceptor is excessively cured, and there is a problem that cracks are likely to occur.
Therefore, the value of the glass transition point (Tg) is preferably set to a value within the range of 60 to 90 ° C, and more preferably set to a value within the range of 65 to 80 ° C.
In addition, a glass transition point can be calculated | required from the change point of a specific heat using a differential scanning calorimeter (DSC). As a measuring apparatus, it can obtain | require by measuring an endothermic curve using the differential scanning calorimeter DSC-6200 by Seiko Instruments.
More specifically, 10 mg of a measurement sample composed of a charge generating agent, an electron transport agent, a hole transport agent, an additive, and a binder resin, which are materials constituting the photoconductor, is placed in an aluminum pan and empty as a reference. Using an aluminum pan, the glass transition point can be determined from the endothermic curve obtained by measuring at a measurement temperature range of 25 to 200 ° C. and a temperature increase rate of 10 ° C./min under normal temperature and normal humidity.

11. Production Method The production method of the single-layer electrophotographic photosensitive member is not particularly limited, but can be carried out by the following procedure.
First, a coating solution is prepared by adding a charge generating agent, a charge transporting agent, a binder resin, an additive and the like to a solvent. The coating solution thus obtained is applied onto a conductive substrate (aluminum tube) using a coating method such as a dip coating method, a spray coating method, a bead coating method, a blade coating method, or a roller coating method. Apply.
Then, for example, it is dried with hot air at 100 ° C. for 30 minutes to obtain a single layer type electrophotographic photosensitive member having a photosensitive layer having a predetermined thickness.
In addition, as a solvent for making a dispersion liquid, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol; aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; Aromatic hydrocarbons such as benzene, toluene, xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride, chlorobenzene; dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,3-dioxolane Ethers such as 1,4-dioxane, ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as ethyl acetate and methyl acetate; dimethylformaldehyde, dimethyl Examples include tilformamide and dimethyl sulfoxide. These solvents are used alone or in admixture of two or more. At this time, in order to improve the dispersibility of the charge generating agent and the smoothness of the surface of the photoreceptor layer, a surfactant, a leveling agent and the like may be added.

It is also preferable to form an intermediate layer on the conductive substrate before forming this photosensitive layer.
In forming this intermediate layer, a binder resin and, if necessary, an additive (organic fine powder or inorganic fine powder) together with an appropriate dispersion medium, a known method such as a roll mill, ball mill, attritor, paint shaker, ultrasonic wave A coating solution is prepared by dispersing and mixing using a disperser or the like, and this is applied by a known means such as a blade method, a dipping method, or a spray method, and subjected to heat treatment to form an intermediate layer.
In addition, the additive is in a range where precipitation during production does not become a problem, and various additives (organic fine powder or inorganic fine powder are used for the purpose of preventing the occurrence of interference fringes by causing light scattering. ) Can be added in small amounts.
Next, the obtained coating solution is applied to a support substrate (aluminum base tube) according to a known production method, such as dip coating, spray coating, bead coating, blade coating, roller coating, etc. It can apply | coat using the apply | coating method.
Then, it is preferable to perform the process of drying the coating liquid on a support base in the range of 5 minutes-2 hours at the temperature of 20-200 degreeC.

  In addition, as a solvent for making such a coating liquid, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol; aliphatic hydrocarbons such as n-hexane, octane and cyclohexane. Aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride and chlorobenzene; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate Dimethylformaldehyde, dimethylformamide, dimethyl sulfoxide and the like. These solvents are used alone or in admixture of two or more.

12 Laminated Photoreceptor Also, it is preferable to use a laminated electrophotographic photoreceptor as shown in FIG. 2A as the electrophotographic photoreceptor for wet development of the present invention. In this multilayer photoconductor 20, a charge generation layer 24 containing a charge generation agent is formed on the substrate 12 by means of vapor deposition or coating, and then an electron transport agent is bound on the charge generation layer 24. The charge transporting layer 22 can be formed by applying a coating solution containing a resin and drying it.
In contrast to the above structure, as shown in FIG. 2B, the charge transport layer 22 may be formed on the substrate 12, and the charge generation layer 24 may be formed thereon. However, since the charge generation layer 24 is much thinner than the charge transport layer 22, for protection, the charge transport layer 22 is formed on the charge generation layer 24 as shown in FIG. It is more preferable to form
Further, as in the case of the single-layer type photoreceptor, it is also preferable to form the intermediate layer 25 on the conductive substrate.

The charge generating layer forming coating liquid and the charge transport layer forming coating liquid are, for example, a predetermined component such as a charge generating agent, a charge transporting agent, and a binder resin, together with a dispersion medium, a roll mill, a ball mill, an attritor, a paint shaker, It can be prepared by dispersing and mixing using an ultrasonic disperser or the like.
In the laminated photosensitive layer 20, the thickness of the photosensitive layer is not particularly limited, but the charge generation layer is preferably 0.01 to 5 μm, more preferably 0.1 to 3 μm, and the charge transport layer is The thickness is preferably 2 to 100 μm, more preferably 5 to 50 μm.

[Second Embodiment]
The second embodiment includes the electrophotographic photosensitive member according to the first embodiment, a charger for carrying out charging means, and an exposure light source for carrying out exposure means around the electrophotographic photosensitive member. The image forming apparatus is characterized in that it is of a static elimination-less type in which a developing device for carrying out the developing means and a transfer device for carrying out the transferring means are arranged and the static eliminating means is omitted.
In the following description of the image forming apparatus, a case where a single-layer type photoreceptor is used as an electrophotographic photoreceptor will be described as an example.

As shown in FIG. 7, around the photosensitive member 31, there are a charger 32 for carrying out the charging means, an exposure light source 33 for carrying out the exposure means, and a developing device 34 for carrying out the developing means. The transfer device 35 for carrying out the transfer means is sequentially arranged.
The photoconductor 31 rotates at a constant speed in the direction of the arrow, and the electrophotographic process is performed on the surface of the photoconductor 31 in the following order. More specifically, the photosensitive member 31 is entirely charged by the charger 32, and then the print pattern is exposed by the exposure light source 33.
Next, the developing device 34 develops toner corresponding to the print pattern, and the transfer device 35 further transfers the toner to a transfer material (paper) 36.
Here, the developer 34a in which the toner is dispersed is conveyed by the developing roller 34b, and the toner is attracted onto the surface of the photoconductor 31 by applying a predetermined developing bias, and developed on the photoconductor 31. Will be.
That is, when the electrophotographic photosensitive member of the present invention is used as the photosensitive member 31, the cracking property due to the contaminating component is improved and the occurrence of exposure memory can be suppressed over a long period of time. As the forming process, an image forming apparatus including a static elimination-less system in which the static elimination unit is omitted can be employed.

[Example 1]
(1) Production of electrophotographic photosensitive member As shown in Table 1, 4 parts by weight of X-type metal-free phthalocyanine (CGM-A) as a charge generating agent and (HTM-1) (molecular weight as a first hole transporting agent) : 777) 60 parts by weight, (ETM-1) 40 parts by weight as an electron transport agent, Z-type polycarbonate resin (BD-1) (weight average molecular weight: 35000) 100 parts by weight as a binder resin, and additives (BP-1) was added so that the ratio of the additive to the solid content of the photosensitive layer was 5% by weight, and was mixed and dispersed in a ball mill for 50 hours together with 800 parts by weight of tetrahydrofuran to prepare a photosensitive layer coating solution. .
Next, the obtained coating solution is applied onto a cylindrical aluminum tube (diameter: 30 mm, length: 254 mm) and dried with hot air at 100 ° C. for 40 minutes, thereby providing a single-layer type photosensitive layer having a thickness of 30 μm. A photosensitive drum was obtained.

(2) Crack resistance test After the obtained electrophotographic photosensitive member was immersed in oleic acid triglyceride for 120 minutes at a temperature of 20 ° C and a humidity of 60%, cracks generated on the surface of the photosensitive member were measured, and crack growth was observed. The speed (mm / min) was evaluated.
That is, the surface of the photosensitive layer was observed using an optical microscope, and the value obtained by dividing the total length (mm) of the generated cracks by the immersion time 120 (min) was defined as the crack growth rate. And evaluated. The obtained results are shown in Table 2.
A: The crack growth rate is a value less than 1 (mm / min).
Δ: Crack growth rate is a value of 1 (mm / min) or more and less than 2.5 (mm / min).
X: The crack growth rate is a value of 2.5 (mm / min) or more.

(3) Evaluation of exposure memory potential The obtained electrophotographic photosensitive member is mounted on a multi-function printer (Antico40) manufactured by Kyocera Mita, which eliminates the charge eliminating means, and the surface potential of the unexposed part and the surface of the exposed part after the charging means. The potential was measured, and the difference was evaluated as an exposure memory potential according to the following criteria.
○: Memory potential is less than 90 (V).
Δ: Memory potential is 90 (V) or more and less than 100 (V).
X: The memory potential is a value exceeding 100 (V).

[Examples 2 to 10]
In Examples 2 to 10, as shown in Table 1, except that the kind and addition amount of the hole transport agent, the kind and addition amount of the electron transport agent, the kind and addition amount of the additive were changed, respectively, An electrophotographic photoreceptor was prepared and evaluated in the same manner as in 1. The obtained results are shown in Table 2.
The molecular weights of the first hole transport agents used in Examples 2 to 10 are 749 for HTM-2, 957 for HTM-3, 927 for HTM-4, and 1029 for HTM-5, respectively.
Further, the molecular weights of the second hole transport agents used in Examples 2 to 10 are 673 for HTM-6 and 416 for HTM-7, respectively.

[Comparative Examples 1-3, 6]
In Comparative Examples 1-3 and 6, as shown in Table 1, except that the type and addition amount of the hole transport agent, the type and addition amount of the electron transport agent, the type and addition amount of the additive were changed, An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1. The obtained results are shown in Table 2.

[Comparative Example 4]
In Comparative Example 4, an electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the compound (HTM-13) (molecular weight 1216) represented by the following formula (49) was used as the hole transporting agent. And evaluated. The obtained results are shown in Table 2.

[Comparative Example 5]
In Comparative Example 5, an electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the compound (HTM-14) (molecular weight 1268) represented by the following formula (50) was used as the hole transport agent. And evaluated. The obtained results are shown in Table 2.

According to the electrophotographic photosensitive member of the present invention, a hole transporting agent having a predetermined molecular weight is contained, and the amount of charge transporting agent added is regulated to a value within a predetermined range, whereby cracks caused by contaminating components are caused. As a result, the generation of exposure memory can be suppressed over a long period of time.
Therefore, the electrophotographic photosensitive member of the present invention is expected to contribute to high durability, high speed, high performance, etc. in various image forming apparatuses such as copying machines and printers.

1 is a cross-sectional view showing a single layer type photoreceptor according to the present invention. 1 is a cross-sectional view showing a multilayer photoreceptor according to the present invention. It is a characteristic view which shows the relationship between the molecular weight of a 1st positive hole transport agent, and crack resistance. It is a characteristic view which shows the relationship between the molecular weight of a 1st positive hole transport agent, and an image characteristic. It is a characteristic view which shows the relationship between the total addition amount of a hole transport agent and an electron transport agent, and crack resistance. It is a characteristic view which shows the relationship between the total addition amount of a hole transport agent and an electron transport agent, and image characteristics. 1 is a schematic diagram illustrating an example of an image forming apparatus according to the present invention.

Explanation of symbols

  10: Single layer type photoreceptor, 12: Conductive substrate, 14: Photosensitive layer, 16: Intermediate layer, 20: Multilayer type photoreceptor, 22: Charge transport layer, 24: Charge generation layer, 25: Intermediate layer, 31: Photoconductor, 32: Charger, 33: Exposure light source, 34: Developer, 35: Transfer device, 36: Transfer paper, 37: Cleaning blade

Claims (9)

An electrophotographic photoreceptor comprising a photosensitive layer containing a charge generating agent, a hole transporting agent, an electron transporting agent, and a binder resin on a conductive substrate,
The total addition amount of the hole transport agent and the electron transport agent is set to a value within a range of 100 to 150 parts by weight with respect to 100 parts by weight of the binder resin,
The electrophotographic photoreceptor, wherein the hole transport agent includes a hole transport agent having a molecular weight in a range of 700 to 1200.   2. The electrophotographic photosensitive material according to claim 1, further comprising a second hole transport agent having a molecular weight of less than 700 when the hole transport agent is a first hole transport agent. body.   3. The electrophotographic photosensitive member according to claim 2, wherein the amount of the first hole transport agent added is set to a value within a range of 30 to 130 parts by weight with respect to 100 parts by weight of the binder resin. .   4. The electron according to claim 1, wherein an addition amount of the electron transfer agent is set to a value within a range of 20 to 60 parts by weight with respect to 100 parts by weight of the binder resin. Photoconductor. The electrophotographic photoreceptor according to any one of claims 1 to 4, wherein the photosensitive layer contains a compound represented by the following general formula (1) as an additive.

(In General Formula (1), R < ¹ > -R < ¹⁰ > is respectively independent, a hydrogen atom, a halogen atom, a substituted or unsubstituted C1-C12 alkyl group, a substituted or unsubstituted C1-C12 An alkoxy group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 30 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 12 carbon atoms, a hydroxyl group, A cyano group, a nitro group, and an amino group, R represents a substituted or unsubstituted alkylene group having 1 to 12 carbon atoms, and n represents an integer of 0 to 3). The electrophotographic photosensitive member according to claim 5, wherein the additive is a compound represented by the following formulas (2) to (7) or a derivative thereof.

  The electrophotographic photosensitive member according to claim 5 or 6, wherein an additive amount of the additive is set to a value in a range of 5 to 15% by weight with respect to a solid content of the photosensitive layer.   The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer is a single layer type. An image forming apparatus comprising the electrophotographic photosensitive member according to any one of claims 1 to 8,
An image forming apparatus, characterized in that a charging unit, an exposure unit, a developing unit, and a transfer unit are disposed around the electrophotographic photosensitive member, and the static elimination type is omitted in which the neutralizing unit is omitted.

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