JP2005128170A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which a photoreceptor drum is brought into contact with a transfer means and deposition of paper powder is suppressed although the apparatus has no discharging means. <P>SOLUTION: The image forming apparatus is equipped with a charging means, an exposing means, a developing means, a transfer means and a paper powder removing means, all disposed around an electrophotographic photoreceptor drum, and has no cleaning means. The single layer type electrophotographic photoreceptor contains a compound expressed by a general formula (1) as a hole transport agent in a photosensitive layer. In the formula (1), R<SB>1</SB>to R<SB>7</SB>are identical with one another or different from one another and each represents an aliphatic group, an aryl group or a hydrogen atom, and at least one in R<SB>1</SB>to R<SB>3</SB>and R<SB>5</SB>to R<SB>7</SB>is a ≥3C aliphatic group, and n is 1 or 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a facsimile machine, or a laser beam printer. More specifically, the present invention uses an electrophotographic photosensitive member and does not have a cleaning unit, and paper dust on a photosensitive drum. The present invention relates to an image forming apparatus without adhesion.

  In an image forming apparatus using an electrophotographic method, a photosensitive member is charged (main charging process), and an image is exposed to form an electrostatic latent image (exposure process). A developing bias voltage is applied to the electrostatic latent image. In this state, the toner is developed (development process), and the formed toner image is transferred onto transfer paper (transfer process) and fixed to form an image. The residual toner on the photoconductor is cleaned by a cleaning blade such as a urethane blade (cleaning process), and the residual charge on the photoconductor is erased by an LED or the like (static elimination process).

  In the image forming process using the electrophotographic method, the photosensitive drum is charged positively and the transfer is applied so as to be negatively charged. On the other hand, negatively charged paper dust is generated from the transfer target (transfer paper) when the image formation is continuously operated. However, the stronger the negative output of the transfer, the easier the paper dust adheres to the photosensitive drum. The paper dust is cleaned together with the toner by a cleaning blade and removed from the surface of the photoreceptor.

In recent years, polymerization toners with high roundness and toners that have undergone spheroidization have been used to increase the resolution and image quality of images. Since such toner has high roundness, it passes through the cleaning blade, and it is difficult to remove the toner remaining on the photoconductor after transfer. Therefore, as described in Patent Document 1, a so-called cleaning-less configuration in which the cleaning means is omitted has been used. In this configuration, instead of having no cleaning means, a method is used in which the residual toner is loosened with a brush or the like and then collected by the developing means. The above brush is arranged downstream of the transfer roller in the rotation direction of the photosensitive drum, and a predetermined bias voltage is applied. Therefore, the toner remaining after the transfer is strongly electrostatically coupled with the charge on the surface of the photosensitive drum. It works to weaken the state of being. Furthermore, it also functions as a paper dust removing brush that electrically captures paper dust on the surface of the photosensitive drum.
JP 09-211979 A

  However, the paper dust removing brush has a weaker removing action than a paper brush that mechanically scrapes paper dust like a cleaning blade, and it is difficult to completely remove the paper dust. In the image forming process in which the member of the charging, developing, or transferring means is in contact with the photosensitive member, such as the transfer roller is in contact with the drum, the paper dust is pressed when the paper dust remains on the photosensitive member, It will be strongly attached on the drum. In such a state, there is a problem that the removal by a paper dust removing means such as a paper dust removing brush becomes more difficult. The adhesion of paper dust appears as black spots or black streaks on the image, and the image quality deteriorates.

  If both the blade and the brush are provided, both the paper dust and the toner can be sufficiently removed and collected, but the image forming apparatus becomes large and the manufacturing cost increases.

  As described above, removing paper dust adhering to the photosensitive drum is indispensable for high-quality image formation. On the other hand, the cleaning process is omitted, and the image forming apparatus is downsized and the initial cost is reduced. Is desired. The conventional method relies on electrically removing the adhered paper dust using a brush, and has not been sufficiently studied from the viewpoint of suppressing adhesion to the photosensitive drum itself. SUMMARY OF THE INVENTION An object of the present invention is to provide means for suppressing paper dust from adhering to a photosensitive drum even in an image forming system that does not have a cleaning means and easily adheres to paper dust.

  As a result of intensive studies and studies to solve the above problems, the present inventors have completed the invention of the following image forming apparatus.

That is, the image forming apparatus of the present invention is an image forming apparatus in which a charging unit, an exposing unit, a developing unit, and a transferring unit are arranged around an electrophotographic photosensitive drum and does not have a cleaning unit.
The photoreceptor is formed on a conductive substrate by forming a single layer type electrophotographic photoreceptor comprising a binder resin containing at least a charge generator and a charge transport agent, and the charge transport agent is represented by the general formula (1):

（式中、Ｒ_１〜Ｒ₇は同一または異なって、脂肪族基、アリール基または水素原子を表し、かつＲ_１、Ｒ_２、Ｒ_３、Ｒ_５、Ｒ_６およびＲ₇のうち少なくとも１つは、炭素数３以上の脂肪族基であり、ｎは１または２である。）で表される化合物をホール輸送剤として含有することを特徴とする。

(Wherein R _{1 to} R ₇ are the same or different and each represents an aliphatic group, an aryl group or a hydrogen atom, and at least one of R ₁ , R ₂ , R ₃ , R ₅ , R ₆ and R ₇ ) Is an aliphatic group having 3 or more carbon atoms, and n is 1 or 2.) is contained as a hole transporting agent.

  One embodiment of the image forming apparatus of the present invention is characterized in that the ratio of the inorganic value / organic value of the compound represented by the general formula (1) is 0.255 or less.

  According to another embodiment of the image forming apparatus of the present invention, in the single-layer electrophotographic photosensitive member, 10 to 110 parts by weight of the compound represented by the general formula (1) with respect to 100 parts by weight of the binder resin. It is characterized by containing in the ratio.

  According to the image forming apparatus of the present invention, although the paperless is usually a system in which paper dust tends to adhere to the photosensitive drum, the adhesion of the paper dust is well suppressed, and black spots caused by the paper dust are reduced. It is extremely effective in preventing occurrence. On the other hand, when the transfer unit is placed in contact with the photosensitive drum, it is advantageous in terms of the generation of ozone and NOx gas and the drum surface is not affected, but the member of the charging, developing or transfer unit is in contact with the photosensitive drum. Tends to cause foreign matter adhesion. Therefore, according to the present invention, even when contact charging, contact development, or contact transfer is performed, it is not necessary to have a cleaning unit. Therefore, the image forming apparatus can be downsized and the initial cost can be reduced.

The single-layer electrophotographic photosensitive member used in the present invention is characterized by containing a compound represented by the general formula (1) as a hole transport agent. That is, in the compound of the general formula (1), the substituent of R ₁ , R ₂ , R ₃ , R ₅ , R ₆ or / and R ₇ is an aliphatic group having 3 or more carbon atoms and has high organicity. Therefore, by using such a compound as a hole transport agent, the adhesion of paper dust is unexpectedly suppressed. In particular, it is preferable that at least one of R ₁ , R ₂ , R ₆ and R ₇ is an aliphatic group having 3 or more carbon atoms, and the substitution position can be selected from ortho, meta and para positions, The substitution of the para position is effective for suppressing adhesion of paper dust. Furthermore, it is preferable that the compound of general formula (1) has a ratio of inorganic value / organic value of 0.255 or less and organicity is enhanced.

  According to the present invention, there is provided an image forming apparatus that uses an electrophotographic photosensitive member and has an extremely good suppression of paper dust adhesion in an image forming system that does not have a cleaning process.

  A configuration example of the image forming apparatus of the present invention will be described with reference to the schematic diagram of FIG. The electrophotographic photosensitive member 1 (the photosensitive layer 11 is formed on the conductive substrate 10) has an axis 13 connected to the driving means 14 via a gear and a pulley, and is in one direction (the direction of the arrow A). ) At a constant speed. A main charging unit 2, an exposure unit 3, a developing unit 4, a transfer unit 5 and a paper dust removing unit 9 are provided in this order around the photosensitive member 1 in the driving direction, that is, the rotating direction. In addition, as shown in FIG. 1, separation means 6 and static elimination means 7 may be provided as necessary.

  Further, the image forming apparatus of the present invention is provided with a fixing unit 12 so that the toner image is fixed to the transfer paper 8 onto which the toner image has been transferred.

  When forming an image, first, the surface of the photoreceptor 1 is uniformly charged by the charging means 2. Next, the surface of the photoreceptor 1 is exposed along the exposure axis 31 by the exposure unit 3 to form an electrostatic latent image corresponding to the document image. That is, in the exposed electrostatic latent image area of the photoreceptor 1, the potential with respect to the ground portion (hereinafter referred to as a surface potential) quickly decreases to the value of the bright potential. The non-image area that has not been exposed is stabilized at the dark potential value with almost no decrease in the surface potential.

  Thereafter, the developing means 4 attaches toner to the portion corresponding to the electrostatic latent image and performs so-called reversal development. Then, the toner image on the surface of the photoreceptor 1 is transferred onto the transfer paper 8 conveyed (in the direction of arrow B) by the transfer unit 5. After the transfer, the transfer paper 8 is separated from the photoreceptor 1 by the separating unit 6 and then fixed by toner by the fixing unit 12.

  After the transfer, the toner that cannot be transferred onto the transfer paper 8 and remains on the surface of the photoreceptor 1 is loosened by the paper dust removing means 9. The paper dust removing means 9 is a brush-like member, and the tip of the brush is in contact with the surface of the photoreceptor 1. The residual toner is loosened by the brush when passing through the paper dust removing means 9. This can weaken the state in which the residual toner is strongly electrostatically coupled with the charge on the surface of the photoreceptor 1. As shown in FIG. 1, when a bias voltage is applied to the paper dust removing means 9, the residual toner is further loosened. Thereafter, the photosensitive member 1 is irradiated with the neutralizing light 71 from the neutralizing unit 7 to neutralize the photosensitive member 1 and the residual toner. In the present invention, a configuration in which the static elimination means 7 is not provided is also possible. Next, the residual toner is charged together with the photoreceptor 1 by the charging unit 2. Then, after being exposed by the exposure means 3, it is collected by the developing means 4. At this time, the residual toner is attracted to the developing means 4 side and collected by the Coulomb force generated from the difference between the bias applied to the developing means 4 and the surface potential of the photoreceptor 1. At the same time, the developing unit 4 develops the electrostatic latent image into a toner image. Here, since the amount of residual toner on the surface of the photoreceptor 1 is small and is loosened by the paper dust removing means 9, the residual toner is electrostatically charged during recharging by the charging means 2 and exposure by the exposure means 3. The latent image is not disturbed.

  After the transfer, the paper dust generated from the transfer paper 8 and adhering to the surface of the photoreceptor 1 is adsorbed by the brush member of the paper dust removing means 9. As shown in FIG. 1, when a bias voltage is applied to the paper dust removing means 9, the paper dust is more effectively adsorbed.

  The paper dust removing means 9 has a large number of thin brush materials planted. As this brush material, acrylic resin, resin such as Teflon (registered trademark), fur brush, metal, resin-coated metal, or the like can be used. When a bias voltage is applied to the paper dust removing means 9, the same polarity as the potential with respect to the grounding portion of the photosensitive member 1 is used, preferably 0 to 1500V, more preferably about 0 to 1000V.

  As the charging unit 2, for example, a conventionally known method of applying corona discharge by applying a high voltage to a charge wire provided close to the surface of the photoreceptor 1, or a charging member such as a conductive roller or a charging brush is used as the photoreceptor 1. A method of applying a charge to the photosensitive member 1 by contacting the surface is applied. In order to keep the surface potential at the main charging portion constant, a method in which a charging member is brought into contact with the surface of the photoconductor 1 or a grid electrode is provided between the charge wire of the main charger and the photoconductor 1 to corona discharge. It is preferable to use the method of performing.

  The main charging voltage applied from the charging unit 2 to the photoconductor 1 varies depending on the characteristics of the photoconductor 1 and toner, development conditions, and the like. For example, in the case of a general positive charge type photoconductor, the grounding portion on the surface of the photoconductor 1 is used. What is necessary is just to set so that the electric potential difference with respect to may be + 300V- + 1000V.

  As the exposure means 3, a laser beam having a wavelength at which the photosensitive member 1 exhibits sensitivity is generally used. Specifically, light having a wavelength that the charge generating agent absorbs may be used. For example, when a phthalocyanine pigment is used as the charge generator, a laser beam having a wavelength of about 600 to 850 nm, a perylene pigment of about 400 to 600 nm, and a bisazo pigment of about 400 to 700 nm is used.

  The exposure amount should be set so that the light potential is as low as possible. Specifically, the exposure is performed so that the light potential of the photosensitive member 1 is the same polarity as the potential of the main charged photosensitive member 1 with respect to the ground portion, and is preferably 0 to 500 V, and more preferably 0 to 300 V. The amount should be set.

  As the developing means 4, a conventionally known contact or non-contact developing apparatus can be used, and any of dry and wet methods may be used. The developer used in the developing unit 4 may be either a one-component system or a two-component system.

  As the transfer means 5, any conventionally known contact transfer or non-contact transfer method can be applied. Specifically, a transfer voltage is applied to the photoreceptor 1 via the transfer paper 8 by a charger, a roller, a brush, a plate, or the like.

  As the separating means 6, as with the charging means 2, those using a corona discharge by a charge wire, those using a conductive roller, etc. can be used, and those using a corona discharge are preferably used. The separation voltage applied to the photoreceptor 1 by the separation means 6 is generally an alternating current.

  When providing the static elimination means 7, conventionally well-known static elimination lamps, such as an LED array and a fluorescent tube, can be used. As the charge eliminating lamp, a lamp that irradiates the photosensitive member 1 with a light having a sensitivity and a sufficient amount of light to remove residual charges on the surface of the photosensitive member 1 may be used.

  As the fixing unit 12, conventionally known methods such as thermal fixing, pressure fixing, thermal pressure fixing, flash fixing, etc. may be used.

  In the image forming apparatus of the present invention, the photoreceptor in the photoreceptor drum forms a single layer type electrophotographic photoreceptor comprising a binder resin containing at least a charge generator and a charge transport agent on a conductive substrate. The photoconductor is an organic photoconductor, which is easier to manufacture than conventional inorganic photoconductors, is low in cost, and has various options for photoconductor materials such as a charge transport agent, a charge generator, and a binder resin. It has the advantage that the degree of freedom in functional design is high. The organic photoreceptor includes a single-layer type photoreceptor in which a charge transport agent (a hole transport agent, an electron transport agent) is dispersed in the same photosensitive layer together with a charge generator, a charge generation layer containing the charge generator, and a charge. There are laminated type photoconductors with a charge transport layer containing a transport agent, and the single layer type photoconductor has a simple layer structure and excellent productivity, and it can improve optical characteristics because there are few interfaces between layers. .

  The single layer type electrophotographic photosensitive member used in the present invention will be described below.

<Hole transport agent>
The single-layer type electrophotographic photosensitive member in the present invention contains a stilbene compound represented by the general formula (1) as a hole transport agent.

In the general formula (1), examples of the aliphatic group corresponding to R _{1 to} R ₇ include an alkyl group and an alkoxy group.

  Examples of the alkyl group include alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, pentyl, isopentyl, neopentyl, and hexyl. can give.

  The alkyl group may have a substituent, specifically, a hydroxyalkyl group, an alkoxyalkyl group, a monoalkylaminoalkyl group, a dialkylaminoalkyl group, a halogen-substituted alkyl group, an alkoxycarbonylalkyl group, a carboxyalkyl group. Alkanoyloxyalkyl group, aminoalkyl group and the like.

  In particular, in the general formula (1), an alkyl group having an electron-donating group such as an alkoxy group, a monoalkylamino group, an amino group, or a dialkylamino group as a substituent is preferable from the viewpoint of increasing charge mobility. Examples of the hydroxyalkyl group include hydroxymethyl, 2-hydroxyethyl, 1,1-dimethyl-2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, 2-hydroxybutyl, 1-hydroxypentyl, and 6-hydroxy. Examples thereof include hydroxyalkyl groups having 1 to 6 carbon atoms in the alkyl moiety, such as hexyl.

  As the alkoxyalkyl group, for example, methoxymethyl, methoxyethyl, methoxybutyl, ethoxyhexyl, ethoxymethyl, butoxyethyl, t-butoxyhexyl, hexyloxymethyl, etc. 6 is an alkoxyalkyl group.

  Examples of the monoalkylaminoalkyl group include methylaminomethyl, ethylaminomethyl, hexylaminomethyl, ethylaminoethyl, hexylaminoethyl, methylaminopropyl, butylaminopropyl, methylaminobutyl, ethylaminobutyl, hexylaminobutyl, Examples thereof include alkylaminoalkyl groups having 1 to 6 carbon atoms in the alkyl moiety, such as methylaminohexyl, ethylaminohexyl, butylaminohexyl, hexylaminohexyl and the like.

  Examples of the dialkylaminoalkyl group include dimethylaminomethyl, diethylaminomethyl, dihexylaminomethyl, diethylaminoethyl, dihexylaminoethyl, dimethylaminopropyl, dibutylaminopropyl, dimethylaminobutyl, diethylaminobutyl, dihexylaminobutyl, dimethylaminohexyl, Examples thereof include dialkylaminoalkyl groups having 1 to 6 carbon atoms in the alkyl moiety, such as diethylaminohexyl, dibutylaminohexyl, dihexylaminohexyl and the like.

  Examples of the alkoxycarbonylalkyl group include methoxycarbonylmethyl, methoxycarbonylethyl, methoxycarbonylhexyl, ethoxycarbonylmethyl, ethoxycarbonylethyl, propoxycarbonylmethyl, isopropoxycarbonylmethyl, butoxycarbonylmethyl, pentyloxycarbonylmethyl, hexylcarbonylmethyl. , Hexylcarbonylbutyl, hexylcarbonylhexyl, etc., both alkyl and alkoxy moieties include alkoxycarbonylalkyl groups having 1 to 6 carbon atoms.

  Examples of the carboxyalkyl group include carboxyalkyl groups having 1 to 6 carbon atoms in the alkyl moiety, such as carboxymethyl, carboxyethyl, carboxybutyl, carboxyhexyl, and 1-methyl-2-carboxyethyl. Examples of the halogen-substituted alkyl group include monochloromethyl, monobromomethyl, monoiodomethyl, monofluoromethyl, dichloromethyl, dibromomethyl, diiodomethyl, difluoromethyl, trichloromethyl, tribromomethyl, triiodomethyl, trifluoromethyl, and monochloro. 1 carbon atom substituted with 1 to 3 halogen atoms, such as ethyl, monobromoethyl, monoiodoethyl, monofluoroethyl, dibromobutyl, diiodobutyl, difluorobutyl, chlorohexyl, bromohexyl, iodohexyl, fluorohexyl, etc. ˜6 alkyl groups.

  Examples of the alkanoyloxyalkyl group include an alkanoyl moiety having 2 to 6 carbon atoms such as acetoxymethyl, 2-acetoxyethyl, propionyloxymethyl, 1-hexanoyloxy-2-methylpentyl, and an alkyl having 1 to 6 carbon atoms. And an alkanoyloxy group having a moiety. Examples of the aminoalkyl group include aminoalkyl groups having 1 to 6 carbon atoms in the alkyl moiety, such as aminomethyl, aminoethyl, aminopropyl, aminobutyl, and aminohexyl.

In the general formula (1), examples of the alkoxy group corresponding to R _{1 to} R ₇ include methoxy, ethoxy, propoxy, isopropoxy, butoxy, t-butoxy, pentyloxy, hexyloxy and the like having 1 to 6 carbon atoms. An alkoxy group is mention | raise | lifted. In addition, an alkoxy group corresponding to R _{1 to} R ₇ The alkoxy group corresponding to may have a substituent, and examples of the substituent include substituents similar to the aforementioned alkyl groups such as a halogen atom, an amino group, a hydroxyl group, a carboxyl group, and an alkanoyloxy group. can give.

In the general formula (1), examples of the aryl group corresponding to R _{1 to} R ₇ include groups such as phenyl, naphthyl, anthryl, and phenanthryl. In addition, examples of the aralkyl group corresponding to R ¹ and R ³ include 1 carbon atom in the alkyl moiety such as benzyl, 1-phenylethyl, 3-phenylpropyl, 4-phenylbutyl, 5-phenylpentyl, and 6-phenylhexyl. And an aralkyl group of ˜6.

  The aryl group and aralkyl group may have a substituent. Examples of the substituent include a halogen atom, an amino group, a hydroxyl group, an optionally esterified carboxyl group, a cyano group, and the like. And an alkyl group which may have a substituent having 1 to 6 carbon atoms, an alkoxy group which may have a substituent having 1 to 6 carbon atoms, and the like. In addition, the substitution position of these substituents is not particularly limited.

As described above, in the present invention, in the general formula (1), at least one of R ₁ , R ₂ , R ₃ , R ₅ , R ₆ and R ₇ is an aliphatic group having 3 or more carbon atoms. It takes a thing. In particular, at least one of R ₁ , R ₂ , R ₆ and R ₇ is preferably an aliphatic group having 3 or more carbon atoms. Examples of the aliphatic group having 3 or more carbon atoms include those having 3 or more carbon atoms in the above-described aliphatic groups, and those having 3 to 6 carbon atoms are particularly preferable. Among them, an alkyl group having 3 or more carbon atoms or an alkoxy group is preferable, and an alkyl group having 3 to 6 carbon atoms is particularly preferable.

  Moreover, it is preferable that the ratio of the inorganic value / organic value of the compound of the general formula (1) is 0.255 or less. Here, the inorganic value / organic value (hereinafter sometimes referred to as I / O value) is a value that handles the polarity of various organic compounds in an organic concept. 1-16 (1954); Chemistry, Volume 11, No. 10, 719-725 (1957); Fragrance Journal, No. 34, 97-111 (1979); Fragrance Journal, No. 50, pp. 79-82 (1981); and the like, and one carbon (C) is made organic 20, while various polar groups are inorganic and organic. The value is defined as shown in Table 1 below, and the sum of the inorganic value and the organic value is obtained and the ratio of the two is taken.

なお、上記の表１において、Ｒは、主にアルキル基を示し、Φは、主にアルキル基もしくはアリール基を示す。

In Table 1 above, R mainly represents an alkyl group, and Φ mainly represents an alkyl group or an aryl group.

  Briefly explaining the concept of I / O value, the properties of a compound are divided into an organic group representing a covalent bond and an inorganic group representing an ionic bond, and all organic compounds are divided into an organic axis and an inorganic axis. It is shown by positioning each point on the named orthogonal coordinates.

  In this case, the inorganic value is a value obtained by quantifying the magnitude of the influence on the boiling point of various substituents and bonds of the organic compound based on the hydroxyl group. Specifically, when the distance between the boiling point curve of the linear alcohol and the boiling point curve of the linear paraffin is about 100 ° C., the influence of one hydroxyl group is set to 100 as a numerical value. Based on this numerical value, the value obtained by quantifying the influence of various substituents or various bonds on the boiling point is the inorganic value of the substituent that the organic compound has. For example, as shown in Table 1 above, the inorganic value of the —COOH group is 150, and the inorganic value of the double bond is 2. Therefore, the inorganic value of a certain organic compound means the sum of inorganic values such as various substituents and bonds of the compound.

On the other hand, the organic value is determined based on the influence of the methylene group in the molecule as a unit and the boiling point of the carbon atom representing the methylene group. That is, since the average value of the boiling point rise is 20 ° C. when one carbon is added in the vicinity of 5 to 10 carbon atoms of the linear saturated hydrocarbon, the organic value of one carbon atom is set to 20 on the basis of this. A value obtained by quantifying the influence of various substituents and bonds on the boiling point based on this value is an organic value. For example, as shown in Table 1 above, the organic value of the nitro group (—NO ₂ ) is 70. Therefore, the inorganic value of a certain type of organic compound means the sum of various substituents and bonds of the compound.

For example, in the general formula (1-1) used in the examples described later, the I / O value of the (hole transfer agent) of the compound in which R ₆ is a methyl group is calculated as follows.

Organic factor-Has 47 organic 20 carbon atoms.

    Therefore, the organic value is 20 × 47 = 940.

Inorganic factor-Has 7 non-polar benzene rings.

  -It has two nonpolar amines (> N-) of 70.

  -It has two double bonds (excluding the benzene ring part) with nonpolarity 3.

    Therefore, the nonpolar value is (17 × 7) + (70 × 2) + (3 × 2) = 251.

  Therefore, the I / O value of this compound is 251/940 = 0.267.

  The I / O value calculated as described above indicates a non-polar (hydrophobic, large organic) organic compound as the value is closer to 0, and a larger polarity (hydrophilic, inorganic) as it is larger. ) Organic compound.

  The compound represented by the general formula (1) includes various stilbene derivatives depending on the substitution position on the central phenylene ring, and in particular, the stilbene derivatives represented by the following general formulas (11) to (13) Is preferred.

（式中、Ｒ_１ 〜Ｒ_７ およびｎは、前記と同じ意義を有する。）
一般式（１１）〜（１３）で表されるスチルベン誘導体として、以下のＨＴＭ−１〜ＨＴＭ−２１のスチルベン誘導体が好ましく例示される。これらの式において、Ｒは炭素数３以上の脂肪族基であることを示す。

(Wherein R ₁ ~R ₇ And n have the same meaning as described above. )
Preferred examples of stilbene derivatives represented by the general formulas (11) to (13) include the following stilbene derivatives of HTM-1 to HTM-21. In these formulas, R represents an aliphatic group having 3 or more carbon atoms.

前記の一般式（１）で表される化合物は、例えば特開２０００−２３９２３６号公報、特開２００１−３１２０７５号公報、特開２００２−３４１６０３号公報などに記載された化合物、あるいはこれら公報に開示された製造方法によって得られる。

The compound represented by the general formula (1) is, for example, a compound described in JP-A No. 2000-239236, JP-A No. 2001-312075, JP-A No. 2002-341603, or the like. Obtained by the manufacturing method.

  The content of the compound represented by the general formula (1) is preferably 10 to 110 wt%, more preferably 30 to 80 wt%, based on the weight of the binding resin.

<Charge generator>
In an image forming apparatus, when a laser is used as a light source, a semiconductor laser or an LED is often used from the viewpoints of small size, low cost, and simplicity. Therefore, an organic photoreceptor having sensitivity in a wavelength region of at least 700 to 850 nm is necessary. As charge generators used in organic photoreceptors that satisfy the above requirements, for example, polycyclic quinone compounds, pyrylium compounds, squalium compounds, phthalocyanine compounds, azo compounds and the like have been proposed or put into practical use. Various phthalocyanine compounds are preferable for the single-layer type electrophotographic photoreceptor used in the invention.

  In general, phthalosinine-based compounds are roughly classified into metal-free phthalocyanine (CGM-1) having no central metal and metal phthalocyanine having a central metal, which has been actively researched and developed in recent years. Examples of the latter include titanyl phthalocyanine (CGM-2), and aluminum phthalocyanine, vanadium phthalocyanine, cadmium phthalocyanine, antimony phthalocyanine, chromium phthalocyanine, copper 4-phthalocyanine, germanium phthalocyanine, iron phthalocyanine, chloroaluminum phthalocyanine, chloroindium phthalocyanine, Examples include chlorogallium phthalocyanine, magnesium phthalocyanine, dialkyl phthalocyanine, tetramethyl phthalocyanine, and tetraphenyl phthalocyanine. Further, the phthalocyanine compounds include crystal types such as α-type, β-type, γ-type, δ-type, ε-type, σ-type, x-type, and τ-type.

  <CGM-1>

＜ＣＧＭ−２＞

<CGM-2>

本発明で使用する単層型電子写真感光体には、フタロシアニン系化合物として、メタルフリーフタロシアニン、またはチタニルフタロシニンが好適に使用される。また、フタロシアニン系化合物は、結合樹脂重量に対して１．０〜４．０ｗｔ％含有することが好ましい。

In the single-layer electrophotographic photosensitive member used in the present invention, metal-free phthalocyanine or titanyl phthalosinine is preferably used as the phthalocyanine compound. Further, the phthalocyanine compound is preferably contained in an amount of 1.0 to 4.0 wt% with respect to the weight of the binding resin.

<Electron transport agent>
Examples of the electron transport agent used in the single-layer electrophotographic photosensitive member used in the present invention include the following quinone compounds (ETM-1, ETM-2, ETM-3, ETM-4, ETM-5, ETM-6). ), An imine compound (ETM-7) and the like can be preferably used.

電子輸送剤の含有量は、結合樹脂重量に対して１０〜６０ｗｔ％、更には２０〜４０ｗｔ％が好ましい。

The content of the electron transfer agent is preferably 10 to 60 wt%, more preferably 20 to 40 wt%, based on the weight of the binding resin.

<Binding resin>
As the binding resin for dispersing each component, various resins conventionally used in the photosensitive layer can be used.

  For example, styrene-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, polyester, alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, etc. Resin such as thermoplastic resin, silicone resin, epoxy resin, phenol resin, urea resin, melamine resin, other cross-linkable thermosetting resin, epoxy acrylate, urethane acrylate, etc. It is. These binder resins can be used alone or in combination of two or more.

  Particularly preferred resins include bisphenol Z-type polycarbonates derived from bisphenol Z-type monomers and phosgene, such as Panlite manufactured by Teijin Chemicals Ltd. and PCZ manufactured by Mitsubishi Gas Chemical Company, Inc.

  The weight average molecular weight of the binder resin in the above example is preferably 5,000 to 200,000, more preferably 15,000 to 100,000.

  In addition to the above-described components, the single-layer type electrophotographic photosensitive member used in the present invention includes various conventionally known additives such as antioxidants and radical scavengers in a range that does not adversely affect the electrophotographic characteristics. Deterioration inhibitors such as singlet quenchers and ultraviolet absorbers, softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, acceptors, donors, and the like can be blended. In order to improve the sensitivity of the photosensitive layer, for example, a known sensitizer such as terphenyl, halonaphthoquinone, and acenaphthylene may be used in combination with the charge generator.

  In the single-layer electrophotographic photosensitive member, a barrier layer may be formed between the conductive substrate and the photosensitive layer as long as the characteristics of the photosensitive member are not impaired.

  A single layer type electrophotographic photosensitive member is obtained by providing a single photosensitive layer on a conductive substrate. This photosensitive layer is formed by dissolving or dispersing a charge generator, a hole transport agent, an electron transport agent, a binding resin, etc. in an appropriate solvent, coating the resulting coating solution on a conductive substrate, and drying. The

  As the conductive substrate on which the photosensitive layer is formed, various materials having conductivity can be used. For example, iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium Examples thereof include simple metals such as nickel, palladium, indium, stainless steel, and brass, plastic materials on which the above metals are vapor-deposited or laminated, glass coated with aluminum iodide, tin oxide, indium oxide, and the like.

  The shape of the conductive substrate may be any of a sheet shape and a drum shape according to the structure of the image forming apparatus to be used. The substrate itself has conductivity or the surface of the substrate has conductivity. If you do. The conductive substrate preferably has sufficient mechanical strength when used.

  When the photosensitive layer is formed by a coating method, the above-exemplified hole transporting agent, charge generating agent, electron acceptor, binder resin and the like together with a suitable solvent are known methods such as a roll mill, a ball mill, an attritor. A dispersion is prepared by dispersing and mixing using a paint shaker, an ultrasonic disperser, etc., and this is applied by a known means and dried.

  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 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, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, Ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and methyl acetate, dimethylformaldehyde, dimethylformamide, dimethyl sulfoxide, etc. Can be given. These solvents are used alone or in combination of two or more.

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

  Next, the image forming apparatus of the present invention uses the single-layer type electrophotographic photosensitive member, and at least a charging unit, an exposing unit, a developing unit, a transferring unit, and a paper dust remover along the traveling direction of the photosensitive unit. The transfer means is disposed without a cleaning means, and the transfer means is disposed in contact with the photosensitive member. Examples of the image forming apparatus include a copying machine, a facsimile machine, and a laser beam printer.

  Since the single layer type electrophotographic photosensitive member of the present invention has a very small transfer / exposure memory, a memory image is not generated even if it is used in the image forming apparatus having no charge eliminating step.

  Further, as described above, the charge removal step is omitted for the purpose of downsizing the image forming apparatus and reducing the initial cost.

  Hereinafter, the present invention will be described with reference to examples and comparative examples. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.

<Comparative Examples 1-3 and Examples 1-6>
2.5 parts by weight of X-type metal-free phthalocyanine (CGM-1) as a charge generating agent, 65 parts by weight of a hole transporting agent represented by the general formula (1-1), and 35 by weight as an electron transporting agent (ETM-1) 100 parts by weight of a bis-Z type polycarbonate resin having a weight average molecular weight of 30,000 as a binder resin and 800 parts by weight of tetrahydrofuran are dispersed or dissolved in a ball mill for 24 hours to prepare a coating solution for a single-layer type photosensitive layer. did. Then, this coating solution is applied on an aluminum base tube as a support by a dip coating method, followed by hot air drying at 125 ° C. for 30 minutes, and a single-layer photoreceptor having a single photosensitive layer with a thickness of 20 μm. Was made.

  General formula (1-1):

（式中、Ｒ_６は、水素原子、メチル基、エチル基、プロピル基、ブチル基、ペンチル基、イソプロピル基、イソブチル基またはイソペンチル基である。）
上記の一般式（１−１）で示される化合物のＩ／Ｏ値を表２に示し、またＲ_６のアルキル基の炭素数とＩ／Ｏ値の関係を図２に示す。一般式（１−１）の化合物は、特開平１０-２３９８７４号公報公報に記載されている。

(In the formula, R ₆ represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, an isopropyl group, an isobutyl group, or an isopentyl group.)
The I / O value of the compound represented by the general formula (1-1) is shown in Table 2, and the relationship between the carbon number of the alkyl group of R ₆ and the I / O value is shown in FIG. The compound of the general formula (1-1) is described in JP-A-10-239874.

The single layer type electrophotographic photoreceptors obtained in Comparative Examples 1 to 3 and Examples 1 to 6 were mounted on a printer (printer DP-560) manufactured by Kyocera Mita except for the cleaning blade. When plain paper (A4 size) is used as the transfer paper, the main charging potential is set to +850 V, the development bias voltage is set to +400 V, and the image formation cycle by reversal development is repeated through the transfer paper, and 10,000 sheets are printed. The number of adhering paper dust on the photosensitive drum (per 1 mm ² ) was measured. Further, the image quality of the printed matter at this time was visually evaluated according to the following criteria.

    A: There are no black spots and black streaks.

    ○: Several black spots or black streaks are recognized, but the level cannot be recognized without staring.

    Δ: Several black spots or black streaks that can be recognized at a glance occurred.

    X: Ten or more black spots or black streaks that can be recognized at a glance occurred.

    XX: Black spots or black streaks were severely generated, and there were portions where printing was difficult to see.

  The results are shown in Table 2. Further, FIG. 3 shows the relationship between the I / O value and the number of adhering paper dust.

この結果、一般式（１−１）において、Ｒが炭素数３以上のアルキル基を有する化合物をホール輸送剤として用いた単層型電子写真感光体を搭載したプリンタは、クリーニング手段を有していないにもかかわらず、長時間の運転後も感光体ドラムへの紙粉付着が抑制されている。また、画質が良好であった。中でもホール輸送剤としてＩ／Ｏ値が０．２５０以下の化合物を用いた実施例２、３および６においては、紙粉付着が非常に少なく、画質も特に良好であった。

As a result, a printer equipped with a single-layer electrophotographic photosensitive member using a compound in which R in the general formula (1-1) has an alkyl group having 3 or more carbon atoms as a hole transport agent has a cleaning means. Despite the absence, paper dust adherence to the photosensitive drum is suppressed even after a long operation. Also, the image quality was good. In particular, in Examples 2, 3 and 6 using a compound having an I / O value of 0.250 or less as a hole transporting agent, paper dust adhesion was very small and the image quality was particularly good.

<Comparative Examples 4-6 and Examples 7-9>
A single photosensitive layer was formed in the same manner as in Comparative Examples 1 to 3 and Examples 1 to 6 except that the hole transfer agent represented by General Formula (1-2) was used instead of General Formula (1-1). A single-layer type photoreceptor having the same was produced.

  General formula (1-2):

（式中、Ｒ_１およびＲ_６は同一であり、水素原子、メチル基、エチル基、プロピル基、ヘキシル基またはオクチル基である。）
上記の一般式（１−２）で示される化合物のＩ／Ｏ値を表３に示し、またＲ_６のアルキル基の炭素数とＩ／Ｏ値の関係を図４に示す。一般式（１−２）の化合物は、特開平１０-２３９８７４号公報公報に記載されている。

(In the formula, R ₁ and R ₆ are the same and are a hydrogen atom, a methyl group, an ethyl group, a propyl group, a hexyl group or an octyl group.)
The I / O values of the compounds represented by the general formula (1-2) are shown in Table 3, and the relationship between the carbon number of the alkyl group of R ₆ and the I / O value is shown in FIG. The compound of the general formula (1-2) is described in JP-A-10-239874.

  Using the single-layer electrophotographic photoreceptors obtained in Comparative Examples 4 to 6 and Examples 7 to 9, the number of paper dust adhered and the image quality after printing 10,000 sheets were evaluated in the same manner as described above.

  The results are shown in Table 3. Further, FIG. 3 shows the relationship between the I / O value and the number of adhering paper dust.

この結果、一般式（１−２）において、Ｒが炭素数３以上のアルキル基を有し、Ｉ／Ｏ値が０．２５０以下の化合物をホール輸送剤として用いた単層型電子写真感光体を搭載したプリンタは、クリーニング手段を有していないにもかかわらず、長時間の運転後も感光体ドラムへの紙粉付着が抑制されている。また、画質が良好であった。

As a result, a single-layer electrophotographic photoreceptor using a compound having a general formula (1-2) in which R has an alkyl group having 3 or more carbon atoms and an I / O value of 0.250 or less as a hole transporting agent. Although a printer equipped with a printer does not have a cleaning means, the adhesion of paper dust to the photosensitive drum is suppressed even after a long operation. Also, the image quality was good.

  The image forming apparatus of the present invention is practically and advantageously used in electrophotographic copying machines, facsimiles, laser beam printers and the like because paper dust adhesion to the photosensitive drum is suppressed and there is no charge eliminating step. it can.

1 is a schematic diagram of an image forming apparatus. In the formula (1-1), shows the relationship between the number of carbon atoms and the I / O value of the _{R 6} (alkyl group). In General formula (1-1), the relationship between an I / O value and the number of paper dust adhesion is shown. In the general formula (1-2), shows the relationship between the number of carbon atoms and the I / O value of the _{R 6} (alkyl group). In General formula (1-2), the relationship between an I / O value and the number of paper dust adhesion is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Charging means 3 Exposure means 4 Developing means 5 Transfer means 9 Paper dust removing means

Claims (3)

In an image forming apparatus in which a charging unit, an exposure unit, a developing unit, a transfer unit, and a paper dust removing unit are arranged around the electrophotographic photosensitive member and does not have a cleaning unit.
The photoreceptor is formed on a conductive substrate by forming a single layer type electrophotographic photoreceptor comprising a binder resin containing at least a charge generator and a charge transport agent, and the charge transport agent is represented by the general formula (1):

(Wherein R _{1 to} R ₇ are the same or different and each represents an aliphatic group, an aryl group or a hydrogen atom, and at least one of R ₁ , R ₂ , R ₃ , R ₅ , R ₆ and R ₇ ) Is an aliphatic group having 3 or more carbon atoms, and n is 1 or 2.) An image forming apparatus comprising a compound represented by the formula:   The image forming apparatus according to claim 1, wherein the compound represented by the general formula (1) has an inorganic value / organic value ratio of 0.255 or less.   2. The monolayer electrophotographic photosensitive member according to claim 1, wherein the compound represented by the general formula (1) is contained at a ratio of 10 to 110 parts by weight with respect to 100 parts by weight of the binder resin. Image forming apparatus.

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