JP2012128139A - Electrophotographic photoreceptor and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor improving the lowering of sensitivity and potential stability, which becomes a problem when using titanyl phthalocyanine adduct of 2,3-butanediol as a charge generating material, and having an improved comprehensive performance as a photoreceptor such as resistance to gas and crack resistance, and to provide an image forming apparatus using the electrophotographic photoreceptor.SOLUTION: In the electrophotographic photoreceptor, a charge generating layer includes a pigment including titanyl phthalocyanine and 2,3-butanediol adduct titanyl phthalocyanine. A ratio of a reflectance (R700) in 700 nm to a reflectance (R780) in 780 nm of reflection spectrum of the charge generating layer is 0.8-1.3, a charge transport layer includes benzidine compound, and residual benzene solvent that may have a substituent is within a range of 20-10000 ppm.

Description

  The present invention relates to an electrophotographic photoreceptor excellent in sensitivity reduction and potential stability, small in humidity dependency, excellent in gas resistance and crack resistance, and an image forming apparatus using the same.

  In recent years, with the development of electronic equipment, the frequency of use of copying machines and printers using electrophotography has increased, and high-sensitivity electrophotographic photoreceptors (hereinafter sometimes simply referred to as photoreceptors) have been announced one after another. ing. In particular, Y-type titanyl phthalocyanine (hereinafter simply referred to as Y-type pigment) having a maximum peak at 27.2 ± 0.2 ° with a Bragg angle 2θ in the powder X-ray diffraction spectrum is known as a highly sensitive material, and is reported in an academic conference. It has also been. Furthermore, it has been found that the photon efficiency is reduced by dehydration treatment of this Y-type titanyl phthalocyanine in a dry inert gas. Since the quantum efficiency increases again when water is reabsorbed by leaving it in a room temperature and humidity environment, the Y-type pigment has a crystal structure containing water, and the exciton holes and electrons generated by the water molecules by light It is speculated that this is one of the causes of high photon efficiency.

  In an electrophotographic photoreceptor using such a material as a charge generation material, there has been a concern that sensitivity characteristics may change due to environmental fluctuations, particularly humidity fluctuations. The disadvantage that the sensitivity of this Y-type pigment is highly dependent on humidity has recently become increasingly problematic as high image quality is required. For example, if it rains at night and clears the next day, the sealed part of the organic photoconductor (near the developing unit) maintains the high humidity atmosphere of the previous day, and it is between the other open parts of the photoconductor. A difference in sensitivity occurs, and a belt-like image defect occurs due to the difference in sensitivity in an intermediate density image immediately after the start of operation in the morning.

  In order to solve this humidity dependency, there has been an attempt to impart another polar group to the Y-type pigment instead of water, and an adduct titanyl phthalocyanine pigment with 2,3-butanediol has also been reported (Patent Literature). 1).

  Furthermore, a titanyl phthalocyanine adduct of 2,3-butanediol having stereoregularity has been reported as having particularly excellent properties (Patent Documents 2 and 3). A titanyl phthalocyanine adduct of diol and a mixed crystal of titanyl phthalocyanine have been reported as highly sensitive pigments (Patent Document 4).

  However, all of these published technologies have improved humidity dependency of sensitivity, but they are insufficient in sensitivity as compared with the Y-type pigment, and the combination selectivity with the charge transport material is Y-type. Since it is different from the pigment, the potential stability in repeated use is insufficient, and there are problems with respect to gas resistance and crack resistance as a photoreceptor.

  For this reason, in order to adopt it for electrophotographic photoreceptors such as high-speed digital copiers that require high image quality, high speed, and high durability, along with improvement of humidity dependence, higher sensitivity and repeated potential stabilization It is necessary to improve overall performance such as performance.

JP-A-5-273775 JP 7-173405 A Japanese Patent Laid-Open No. 8-82942 Japanese Patent Laid-Open No. 9-230615

  The present invention has been made to solve the above problems.

  That is, the object of the present invention is to improve sensitivity reduction and potential stability, which are problems when a titanyl phthalocyanine adduct of 2,3-butanediol is used as a charge generation material, It is to provide an electrophotographic photosensitive member having improved overall performance as a photosensitive member, and to provide an image forming apparatus using the electrophotographic photosensitive member.

  The above-mentioned problems of the present invention are achieved by improving the sensitivity over that of the Y-type titanyl phthalocyanine pigment while taking advantage of the conventional 2,3-butanediol adduct titanyl phthalocyanine pigment (sensitivity is less dependent on humidity). Based on the technical idea that it will be achieved, the sensitivity of 2,3-butanediol adduct titanyl phthalocyanine pigments was investigated. As a result, the index of the reflection spectrum of the charge generation layer of the pigment containing the 2,3-butanediol adduct titanyl phthalocyanine is in a specific range, and a specific charge transport layer is provided on the charge generation layer. In the case of the structure, the sensitivity is improved by the photoreceptor using the pigment containing the 2,3-butanediol adduct titanyl phthalocyanine, and the potential stability is improved, and the photoreceptor has gas resistance, crack resistance, etc. As a result, it has been found that an electrophotographic photoreceptor having improved overall performance can be obtained, and the present invention has been achieved.

  The object of the present invention is achieved by adopting the following configuration.

  1. In an electrophotographic photosensitive member having a charge generation layer and a charge transport layer on a conductive support, the charge generation layer contains a pigment containing titanyl phthalocyanine and a 2,3-butanediol adduct titanyl phthalocyanine, and the charge generation The ratio (R700 / R780) of the reflectance (R700) at 700 nm and the reflectance (R780) at 780 nm of the reflection spectrum of the layer is 0.8 to 1.3, and the charge transport layer has the following general formula (1) An electrophotographic photoreceptor comprising the compound of formula (3), wherein the residual solvent of the following general formula (3) is in the range of 20 to 10,000 ppm.

  However, the reflectance is a reflectance measured by forming a photosensitive layer (charge generation layer) on an aluminum support, and is a relative reflectance when the reflectance of the aluminum support is 100%.

  Further, the amount of the residual solvent of the following general formula (3) is the amount of the residual solvent in all layers formed on the conductive support.

(In the general formula (1), R ₁ represents an alkyl group, an alkoxy group or a halogen atom, and R ₂ represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom.)

(In General Formula (3), X and Y each independently represent a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, but they are not both hydrogen atoms.)
2. 2. The electrophotographic photosensitive member according to 1, wherein the charge transport layer further contains 40% or less of the compound of the following general formula (2) with respect to the compound of the general formula (1).

(In the general formula (2), R ₃ represents an alkyl group, an alkoxy group or a halogen atom, and R ₄ represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom.)
3. 3. The electrophotographic photosensitive material as described in 2 above, wherein the total content of the compounds of the general formula (1) and the general formula (2) is 40 to 67 parts by mass with respect to 100 parts by mass of the binder of the charge transport layer. body.

  4). 4. Means for forming an electrostatic latent image on the electrophotographic photosensitive member according to any one of 1 to 3, means for developing the electrostatic latent image with toner, means for transferring the formed toner image to an image support An image forming apparatus comprising at least means for fixing the toner image after transfer.

  The electrophotographic photosensitive member of the present invention has the above-described structure, thereby improving the decrease in sensitivity and potential stability, which are problems when a titanyl phthalocyanine adduct of 2,3-butanediol is used as the charge generation material, To provide an electrophotographic photosensitive member that is less dependent and has improved overall performance as a photosensitive member such as gas resistance and crack resistance, and an image forming apparatus using the electrophotographic photosensitive member. It is.

An example of the reflection spectrum of the photosensitive layer containing the pigment of this invention. An example of a reflection spectrum of a photosensitive layer using a pigment containing a 2,3-butanediol adduct titanyl phthalocyanine, which has a characteristic peak at a Bragg angle 2θ (± 0.2 °) of 9.5 ° (9.5 ° And a spectrum diagram of phthalocyanine having a characteristic peak at 8.3 ° (8.3 ° type). 1 is a cross-sectional configuration diagram of a color image forming apparatus using an electrophotographic photosensitive member of the present invention.

  The configuration of the electrophotographic photoreceptor of the present invention will be described below.

  First, the charge generation layer according to the present invention will be described.

(Charge generation layer)
The pigment containing the titanyl phthalocyanine and the 2,3-butanediol adduct titanyl phthalocyanine contained in the charge generation layer of the invention of the present invention (pigment of the invention of the present application) includes at least titanyl phthalocyanine and 2,3 in one pigment particle. -Means a pigment containing butanediol adduct titanyl phthalocyanine.

  The reflection spectrum of the charge generation layer containing the pigment of the present invention is described below.

  The charge generation layer having the pigment of the present invention has a reflection spectrum characteristic in which the ratio (R700 / R780) of the reflectance (R700) at 700 nm and the reflectance (R780) at 780 nm of the reflection spectrum is 0.8 to 1.3. To obtain it, it is necessary to disperse the pigment as follows.

  That is, in the process of preparing the coating solution for the charge generation layer, it is important to sufficiently disperse the charge generation material (pigment) so that secondary agglomerated particles and coarse particles are not included in the coating solution. .

  On the other hand, when the dispersibility of the charge generation material is increased by a high dispersion share, a uniformly dispersed coating film can be formed, but the crystal structure of the charge generation material is changed by the dispersion share and its characteristics are impaired, and sensitivity and potential stability are stabilized. May cause problems with sex.

  That is, the dispersion means preferably used in the present invention is low shear dispersion (low shear dispersion). As the low shear dispersion, ultrasonic dispersion or a medium having a small specific gravity (glass (specific gravity: 2.5)). Media dispersion using beads or the like is preferred.

[Dispersion of pigment in charge generation layer]
In order to make a dispersion liquid such as a charge generation layer using the pigment of the present invention (a pigment containing titanyl phthalocyanine and 2,3-butanediol adduct titanyl phthalocyanine), these pigments are dispersed in a solvent. There are no particular restrictions on the solvent, and ketone solvents such as methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, cyclohexanone, and acetophenone, ether solvents such as tetrahydrofuran, dioxolane, and diglyme, and alcohol solvents such as methyl cellosolve, ethyl cellosolve, and butanol There may be mentioned a large number of solvents, ester solvents such as ethyl acetate and t-butyl acetate, aromatic solvents such as toluene and chlorobenzene, and halogen solvents such as dichloroethane and trichloroethane.

  A binder can be added to the dispersion. The binder can be selected widely as long as it is soluble in the solvent used. Examples include polyvinyl butyral, polyvinyl formal, polyvinyl acetate, polyvinyl chloride, polyamide, polycarbonate, polyester, and copolymers thereof. The ratio of the binder and the pigment is not particularly limited, but is usually 1/10 to 10/1. When the amount of the binder is small, the dispersion becomes unstable, and when the amount is too large, the electric resistance is increased, and when the electrophotographic photosensitive member is formed, the residual potential tends to increase repeatedly.

  The dispersion means preferably used in the present invention is low shear dispersion (low shear dispersion). Examples of the low shear dispersion include ultrasonic dispersion and small specific gravity media (glass (specific gravity: 2.5) beads, etc. ) Is preferred.

  As an indicator of the dispersion state, the ratio of the reflection spectrum of the charge generation layer (R700 / R750) needs to be in the range of 0.8 to 1.3. Control of the ratio of these reflection spectra (R700 / R750) can be performed by adjusting the share applied to the dispersion during dispersion. Specifically, it can be controlled by the dispersion method, the diameter and amount of media used during dispersion, the dispersion time, and the like.

  According to the study results of the present inventors, when the ratio (R700 / R780) of the charge generation layer is 0.8 to 1.3, there is no humidity dependency of sensitivity, and high sensitivity and repeated potential stabilization. It has been found that an electrophotographic photoreceptor having high properties can be obtained.

  FIG. 1 is an example of the reflection spectrum of a photosensitive layer containing the pigment of the present invention.

  FIG. 1A shows a characteristic in which the ratio of reflection spectrum (R700 / R780) is within the scope of the present invention.

  FIG. 1B shows a characteristic in which the ratio of reflection spectrum (R700 / R780) is outside the range of the present invention.

  In the dispersion of the pigment of the present invention, the reflectance near 780 nm increases and the ratio (R700 / R780) decreases as the dispersion of secondary aggregation and the crushing of crystals progress.

  When the ratio (R700 / R780) is less than 0.8, it indicates that the pigment crystal was crushed due to excessive dispersion share, and the 2,3-butanediol adduct titanyl phthalocyanine tends to be decomposed at the defective portion of the crystal. As a result, sensitivity and repetitive characteristics deteriorate.

  On the other hand, when the ratio (R700 / R780) exceeds 1.3, it indicates that secondary aggregated particles or coarse particles with poor dispersion are present, and image defects such as a decrease in image density occur.

  In the present invention, the reflection spectrum of the photosensitive layer is measured with a sample in which a charge generation layer is formed on an aluminum support with a dry film thickness of 0.3 μm. The reflection spectrum is measured as a relative reflectance when the reflectance of the aluminum support is 100%. In order to remove irregularities due to interference fringes in the obtained reflection spectrum, the measurement data is approximated by a second order polynomial in the range of 685 to 715 nm and 765 to 795 nm, and the reflectance (R700) and reflectance (R780) are calculated. The ratio (R700 / R780) is calculated.

  The reflection spectrum was measured by using an optical film thickness measuring device Solid Lambda Thickness (Spectra Corp.).

  The 2,3-butanediol adduct titanyl phthalocyanine pigment has a unique crystal type due to the difference in the addition ratio of butanediol.

  When an excess of titanyl phthalocyanine and at least one of (2R, 3R) -2,3-butanediol or (2S, 3S) -2,3-butanediol (hereinafter also referred to as butanediol) is reacted, In the diffraction spectrum, a pigment having a characteristic peak at a Bragg angle 2θ (± 0.2 °): 9.5 ° (hereinafter abbreviated as 9.5 ° type) is obtained as shown in FIG. The 9.5 type butanediol-added titanyl phthalocyanine pigment has peaks at 16.4 °, 19.1 °, 24.7 °, and 26.5 ° in addition to 9.5.

Structure of the pigment Ti = O absorption near 970 cm ^-1 in the IR spectrum disappeared, 630 cm ^-1 of the absorption of the O-Ti-O appears in the vicinity about the 390 to 410 ° C. in a thermal analysis (TG) 11 % Mass loss (possibly due to the elimination of butylene oxide by thermal decomposition), and from the results of mass spectrometry, titanyl phthalocyanine and (2R, 3R) -2,3-butanediol or (2S, 3S ) -2,3-butanediol is considered to have a dehydrated condensation structure at 1/1.

On the other hand, when a butanediol compound is reacted at 1 mol or less with respect to 1 mol of titanyl phthalocyanine, the powder X-ray diffraction spectrum has a characteristic peak at a Bragg angle 2θ: 8.3 ° (± 0.2 °) ( Hereinafter, the pigment shown in FIG. 2 (2) is obtained. The 8.3 ° butanediol-added titanyl phthalocyanine pigment has peaks at 24.7 °, 25.1 °, and 26.5 ° in addition to 8.3 °. The pigment shows both absorption of Ti = O near 970 cm ⁻¹ and O—Ti—O near 630 cm ⁻¹ in the IR spectrum. In addition, from the result of mass analysis that the mass loss is less than 11% at 390 to 410 ° C. by thermal analysis and from the result of mass analysis, butanediol / titanyl phthalocyanine = 1/1 adduct and titanyl phthalocyanine are mixed at a certain ratio ( It is presumed that two or more compounds are mixed in one pigment particle to form a pigment having a specific crystal type. The butanediol addition ratio is estimated to be 40 to 70 mol% from the mass loss of 390 to 410 ° C. in the thermal analysis.

  In the X-ray diffraction spectrum, the characteristic peak means a clearly different peak exceeding the background variation.

  In the present invention, the pigment of the present invention is characterized by at least a Bragg angle (2θ ± 0.2 °) of 8.3 ° in the X-ray diffraction spectrum in that good sensitivity and repeated potential stability can be obtained. More preferably, it has a peak.

  In the present invention, for synthesis of 2,3-butanediol adduct titanyl phthalocyanine, the optical material of (2R, 3R) -2,3-butanediol or (2S, 3S) -2,3-butanediol is used as a raw material. The isomeric 2,3-butanediol is preferably used, but a racemate that does not exhibit optical isomerism may be used.

The pigment of the present invention is a pigment at the time of synthesis and desirably has a BET specific surface area of 20 m ² / g or more.

  Thus, when the coating solution of the charge generation layer containing a pigment having a large BET specific surface area and a small particle size is dispersed in a low shear to maintain the dispersibility of the pigment during synthesis, good sensitivity and repeated potential are obtained. A photosensitive member having stability can be produced.

[Method for producing 2,3-butanediol adduct titanyl phthalocyanine]
2,3-butanediol adduct titanyl phthalocyanine, for example, an adduct of titanyl phthalocyanine and at least one of (2R, 3R) -2,3-butanediol or (2S, 3S) -2,3-butanediol, Titanyl phthalocyanine and (2R, 3R) -2,3-butanediol or (2S, 3S) -2,3-butanediol (hereinafter sometimes referred to as butanediol compound) in various solvents at room temperature or under heating It can be synthesized by reacting. The raw material titanyl phthalocyanine can be synthesized from phthalonitrile and titanium tetrachloride, synthesized from diiminoisoindoline and alkoxy titanium, or synthesized from phthalonitrile, urea and alkoxy titanium. The method can also be used, but high purity titanyl phthalocyanine with a low chlorine content obtained from diiminoisoindoline and alkoxytitanium is particularly preferred. The titanyl phthalocyanine is preferably made amorphous by a method such as acid paste treatment and then reacted with a butanediol compound. For the addition reaction between amorphous titanyl phthalocyanine and a butanediol compound, usually 5 to 30 times the solvent is used. The solvent is not particularly limited, and aromatic solvents such as chlorobenzene, dichlorobenzene, anisole, chloronaphthalene and quinoline to ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and acetophenone, ether solvents such as tetrahydrofuran, dioxolane and diglyme, Furthermore, there can be mentioned a large number of aprotic polar solvents such as dimethylformamide, dimethylacetamide and dimethylsulfoxide, other halogen-based solvents and ester-based solvents.

The reaction between titanyl phthalocyanine and a butanediol compound is shown below. The reaction can be carried out under a wide range of temperature conditions, the reaction temperature is preferably in the range of 25 to 300 ° C., and a pigment having a BET specific surface area of 20 m ² / g or more. In order to synthesize | combine, it is more preferable that it is the range of 30-100 degreeC.

  The butanediol compound is usually added at a ratio of 0.2 to 2.0 mol with respect to 1 mol of titanyl phthalocyanine. In order to be an equimolar adduct, the diol compound must be used in an amount of 1.0 mol or more. When the diol compound is added in an amount of 1.0 mol or less in the above ratio, the obtained adduct becomes a mixed crystal with titanyl phthalocyanine.

  The charge generation layer contains a charge generation material (CGM). Other substances may contain a binder resin and other additives as necessary.

  In the charge generation layer according to the present invention, the above-mentioned butanediol adduct titanyl phthalocyanine pigment is used as the charge generation material, but other phthalocyanine pigments, azo pigments, perylene pigments, azulenium pigments and the like can be used in combination. .

  When a binder is used as the CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferred resins include formal resin, butyral resin, silicone resin, silicone-modified butyral resin, phenoxy resin, and the like. Can be mentioned. The ratio of the binder resin to the charge generating material is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. By using these resins, the increase in residual potential associated with repeated use can be minimized. The thickness of the charge generation layer is preferably 0.1 μm to 2 μm.

  Next, the charge transport layer according to the present invention will be described.

(Charge transport layer)
The charge transport layer according to the present invention contains the general formula (1).

  The structure of the general formula (1) is a benzidine structure in which a triphenylamine skeleton excellent in charge mobility is connected, and has a characteristic of excellent sensitivity stability. However, because of the structure having relatively high crystallinity, depending on the type of coating solvent and binder resin to be used, it may be deposited at the time of photoconductor preparation, or a micro defect may cause a leak defect. It is preferable to mix the compounds. However, since the compound of the general formula (2) alone has higher crystallinity than the general formula (1), the mixing ratio is preferably 40% by mass or less of the general formula (1).

  Examples of the compound of the general formula (1) include the following compounds.

  On the other hand, examples of the compound of the general formula (2) include the following compounds.

  The charge transport layer contains the charge transport material (CTM) of the general formula (1) and the general formula (2) and a binder resin for forming a film by dispersing the CTM. Other substances may contain additives such as antioxidants as necessary.

  As the charge transport material (CTM), in addition to the charge transport materials (CTM) represented by the general formulas (1) and (2), a known charge transport material (CTM) can be used. For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound, or the like can be used. These charge transport materials are usually dissolved in a suitable binder resin to form a layer.

  The binder resin used for the charge transport layer (CTL) may be either a thermoplastic resin or a thermosetting resin. For example, polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and these resins A copolymer resin containing two or more of the repeating unit structures. In addition to these insulating resins, high molecular organic semiconductors such as poly-N-vinylcarbazole can be used. Of these, polycarbonate resins are most preferred because of their low water absorption and good CTM dispersibility and electrophotographic characteristics.

  The ratio of the binder resin to the charge transport material is preferably 40 to 67 parts by mass with respect to 100 parts by mass of the binder resin. The thickness of the charge transport layer is preferably 10 to 40 μm.

  Although the most preferable layer structure of the photoreceptor of the present invention has been exemplified above, the present invention may employ other photosensitive layer structures.

  As the solvent or dispersion medium used for the layer formation of the charge transport layer, a compound represented by the general formula (3) having high affinity with the compounds of the general formula (1) and the general formula (2) is used.

  Specific examples include toluene, o-, m-, p-xylene or a mixture thereof, anisole, phenetole, chlorobezene, o-, m-, p-dichlorobenzene or a mixture thereof, and bromobenzene. Particularly preferred is toluene. By containing these compounds of the general formula (3) (residual solvent) in the range of 20 to 10,000 ppm, the problem of the compound of the general formula (1) or the compound of the general formula (2), which is originally highly crystalline, is solved. A photoreceptor free from an increase in potential fluctuation due to leakage during endurance and image defects can be obtained. If the amount of the solvent is less than 40 ppm, this effect cannot be obtained sufficiently, resulting in deterioration of potential characteristics and occurrence of image defects. On the other hand, when the concentration is higher than 10,000 ppm, the active gas easily permeates, the resistance to gas is lowered, the image is easily blurred, and the potential stability is easily lowered.

  Examples of the solvent that can be used in combination with the compound represented by the general formula (3) according to the present invention include alcohol-based, ether-based, and ketone-based compounds. For example, methanol, ethanol, tetrahydrofuran, dioxane, acetone, methyl ethyl ketone, diethyl ketone and the like are preferable, and tetrahydrofuran is particularly preferable.

  The amount of residual solvent in the charge transport layer of the present invention can be adjusted by the drying conditions after coating the charge transport layer, the combined conditions of the charge transport layer coating solution solvent, and the like. In general, the drying temperature of the organophotoreceptor is adjusted to at least the boiling point of the solvent and by changing the drying time. The drying temperature is preferably around 70 ° C. to 150 ° C. in relation to productivity and cost.

  As the solvent used for forming layers other than the charge transport layer, the following solvents can be used.

  n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone, methyl ethyl ketone, methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane 1,2-dichloropropane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethane, tetrahydrofuran, dioxolane, dioxane, methanol, ethanol, butanol, isopropanol, ethyl acetate, butyl acetate, dimethyl Examples thereof include sulfoxide and methyl cellosolve. The present invention is not limited to these, but toluene, tetrahydrofuran, dioxolane and the like are preferably used. These solvents may be used alone or as a mixed solvent of two or more.

[Other configurations of electrophotographic photosensitive member]
The configuration other than the charge generation layer and the charge transport layer described above will be described.

(Conductive support)
As the conductive support used in the photoreceptor of the present invention, a sheet-like or cylindrical conductive support is used.

  The cylindrical conductive support of the present invention means a cylindrical support necessary for forming an endless image by rotating, and the straightness is in the range of 0.1 mm or less and the deflection is 0.1 mm or less. Certain conductive supports are preferred. Exceeding the range of straightness and shake makes it difficult to form a good image.

As a material for the conductive support, a metal drum such as aluminum or nickel, a plastic drum deposited with aluminum, tin oxide, indium oxide, or the like, or a paper / plastic drum coated with a conductive substance can be used. The conductive support preferably has a specific resistance of 10 ³ Ω · cm or less at room temperature.

  As the conductive support used in the present invention, one having an alumite film that has been sealed on the surface thereof may be used. The alumite treatment is usually performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid, etc., but anodizing treatment in sulfuric acid gives the most preferable result. In the case of anodizing in sulfuric acid, the sulfuric acid concentration is preferably 100 to 200 g / l, the aluminum ion concentration is 1 to 10 g / l, the liquid temperature is about 20 ° C., and the applied voltage is preferably about 20 V. It is not limited. The average film thickness of the anodized film is usually 20 μm or less, particularly preferably 10 μm or less.

(Middle layer)
In the present invention, it is preferable to provide an intermediate layer having a barrier function between the conductive support and the photosensitive layer (charge generation layer and charge transport layer). In particular, titanium oxide fine particles are contained in a binder resin such as polyamide. An intermediate layer to be dispersed is preferable. The average particle diameter of the titanium oxide particles is preferably in the range of 10 nm to 400 nm in terms of number average primary particle diameter, and is preferably 15 nm to 200 nm. If it is less than 10 nm, the effect of preventing the occurrence of moire by the intermediate layer is small. On the other hand, if it is larger than 400 nm, the titanium oxide particles in the intermediate layer coating solution are likely to settle, and as a result, the uniform dispersibility of the titanium oxide particles in the intermediate layer is poor, and the black spots are likely to increase. An intermediate layer coating liquid using titanium oxide particles having a number average primary particle size in the above range has good dispersion stability, and the intermediate layer formed from such a coating liquid has an environmental characteristic in addition to the function of preventing the occurrence of black spots. Is good and has cracking resistance.

  The shape of the titanium oxide particles used in the present invention includes a dendritic shape, a needle shape, a granular shape, and the like. The titanium oxide particles having such a shape are, for example, titanium oxide particles, anatase type, rutile as crystal types. There are types, amorphous types, and the like. Any crystal type may be used, or two or more crystal types may be mixed and used. Among them, the rutile type and granular type are the best.

  The titanium oxide particles of the present invention are preferably surface-treated. Among these, it is preferable to perform a plurality of surface treatments, and among the plurality of surface treatments, the last surface treatment is a surface treatment using a reactive organosilicon compound. In addition, at least one of the surface treatments is at least one surface treatment selected from alumina, silica, and zirconia, and finally a surface treatment using a reactive organosilicon compound. It is preferable to carry out.

  Alumina treatment, silica treatment and zirconia treatment are treatments for precipitating alumina, silica or zirconia on the surface of the titanium oxide particles. The alumina, silica and zirconia deposited on these surfaces are water of alumina, silica and zirconia. Japanese products are also included. The surface treatment of the reactive organosilicon compound means using a reactive organosilicon compound in the treatment liquid.

  In this way, when the surface treatment of the titanium oxide particles is performed at least twice, the surface of the titanium oxide particles is uniformly coated (treated), and when the surface-treated titanium oxide particles are used for the intermediate layer, the intermediate layer It is possible to obtain a good photoconductor having good dispersibility of the titanium oxide particles therein and causing no image defects such as black spots.

  Preferable reactive organosilicon compounds used for the surface treatment include various alkoxysilanes such as methyltrimethoxysilane, n-butyltrimethoxysilane, n-hexycyltrimethoxysilane, dimethyldimethoxysilane, and methylhydrogenpolysiloxane.

(Photosensitive layer)
The photosensitive layer structure of the photoreceptor of the present invention is preferably the structure of the photosensitive layer described above on the intermediate layer, that is, a structure in which a charge generation layer (CGL) and a charge transport layer (CTL) are laminated. By adopting a configuration in which the functions are separated, an increase in the residual potential due to repeated use can be controlled to be small, and other electrophotographic characteristics can be easily controlled according to the purpose.

  Next, as a coating processing method for producing the electrophotographic photoreceptor of the present invention, coating processing methods such as dip coating, spray coating, and circular amount regulation type coating are used. In order to prevent the lower layer film from being dissolved as much as possible, and in order to achieve uniform coating processing, it is preferable to use a coating processing method such as spray coating or circular amount regulation type (a circular slide hopper type is a typical example). It is most preferable to use the circular amount regulation type coating method for the protective layer. The circular amount regulation type coating is described in detail in, for example, Japanese Patent Application Laid-Open No. 58-189061.

[Image forming apparatus]
FIG. 3 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention.

  In the image forming apparatus of the present invention, it is desirable to use a semiconductor laser or light emitting diode (LED) having an oscillation wavelength of 350 to 850 nm as an image exposure light source when an electrostatic latent image is formed on a photoreceptor. By using these image exposure light sources, the exposure dot diameter in the writing principal direction is narrowed down to 10 to 100 μm, and digital exposure is performed on the organic photoreceptor, so that 600 dpi (dpi: number of dots per 2.54 cm) to 2400 dpi. Or higher-resolution electrophotographic images can be obtained.

The exposure dot diameter refers to the length of the exposure beam along the main scanning direction (Ld: measured at the maximum length) in a region where the intensity of the exposure beam is 1 / e ² or more of the peak intensity.

The light beams used have a scanning optical system and LED solid scanner such as a semiconductor laser, there is a Gaussian distribution and Lorentz distribution, etc. also the light intensity distribution is in each 1 / e ² or more regions of peak intensity The exposure dot diameter according to the present invention is used.

  This color image forming apparatus is called a tandem type color image forming apparatus, and includes four sets of image forming units (image forming units) 10Y, 10M, 10C, and 10Bk, an endless belt-shaped intermediate transfer body unit 7, and a feeding unit. It comprises a paper conveying means 21 and a fixing means 24. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  The image forming unit 10Y that forms a yellow image includes a charging unit (charging step) 2Y disposed around a drum-shaped photoconductor 1Y (photosensitive drum 1Y) as a first image carrier, and an exposure unit ( Exposure process) 3Y, developing means (developing process) 4Y, primary transfer roller 5Y as primary transfer means (primary transfer process), and cleaning means 6Y. An image forming unit 10M that forms a magenta image includes a drum-shaped photosensitive member 1M as a first image carrier, a charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, It has a cleaning means 6M. An image forming unit 10C for forming a cyan image includes a drum-shaped photoreceptor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a primary transfer roller 5C as a primary transfer unit. It has cleaning means 6C. The image forming unit 10Bk that forms a black image includes a drum-shaped photoreceptor 1Bk as a first image carrier, a charging unit 2Bk, an exposure unit 3Bk, a developing unit 4Bk, a primary transfer roller 5Bk as a primary transfer unit, and a cleaning unit. 6Bk.

  The four sets of image forming units 10Y, 10M, 10C, and 10Bk include charging means 2Y, 2M, 2C, and 2Bk that rotate around the photosensitive drums 1Y, 1M, 1C, and 1Bk, and image exposure means 3Y, 3M, 3C and 3Bk, rotating developing means 4Y, 4M, 4C and 4Bk, and cleaning means 6Y, 6M, 6C and 6Bk for cleaning the photosensitive drums 1Y, 1M, 1C and 1Bk.

  The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the colors of toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different, and the image forming unit 10Y is taken as an example in detail. explain.

  The image forming unit 10Y has a charging unit 2Y (hereinafter simply referred to as a charging unit 2Y or a charger 2Y), an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 6Y (around a photosensitive drum 1Y as an image forming body). Hereinafter, the cleaning unit 6Y or the cleaning blade 6Y) is simply disposed, and a yellow (Y) toner image is formed on the photosensitive drum 1Y. In the present embodiment, in the image forming unit 10Y, at least the photosensitive drum 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 6Y are provided so as to be integrated.

  The charging unit 2Y is a unit that applies a uniform potential to the photosensitive drum 1Y. In the present embodiment, a corona discharge type charger 2Y is used for the photosensitive drum 1Y.

  The image exposure means 3Y performs exposure based on the image signal (yellow) on the photosensitive drum 1Y given a uniform potential by the charger 2Y, and forms an electrostatic latent image corresponding to the yellow image. As this image exposure means 3Y, an apparatus comprising LEDs and light-emitting elements arranged in an array in the axial direction of the photosensitive drum 1Y and an imaging element, or a laser optical system is used. .

  The image forming apparatus of the present invention is configured by integrally combining the above-described photosensitive member and components such as a developing device and a cleaning device as a process cartridge (image forming unit), and this image forming unit is connected to the apparatus main body. It may be configured to be detachable. In addition, at least one of a charging device, an image exposure device, a developing device, a transfer or separation device, and a cleaning device is integrally supported together with a photosensitive member to form a process cartridge (image forming unit), which is detachable from the apparatus main body. A single image forming unit may be detachable using guide means such as a rail of the apparatus main body.

  The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk as primary transfer means. Thus, a synthesized color image is formed. An image support P as an image support (support for supporting a fixed final image: for example, plain paper, transparent sheet, etc.) housed in the paper feed cassette 20 is fed by a paper feed means 21 and is supplied to a plurality of image supports P. The intermediate rollers 22A, 22B, 22C, 22D, and the registration roller 23 are conveyed to a secondary transfer roller 5b as a secondary transfer unit, and are secondarily transferred onto the image support P to collectively transfer color images. . The image support P to which the color image has been transferred is subjected to fixing processing by the fixing means 24, is sandwiched between the paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus. Here, a toner image transfer support formed on a photosensitive member such as an intermediate transfer member or an image support is generally referred to as a transfer medium.

  On the other hand, the endless belt-shaped intermediate transfer body 70 obtained by transferring the color image to the image support P by the secondary transfer roller 5b as the secondary transfer means and then separating the curvature of the image support P is subjected to residual toner by the cleaning means 6b. Removed.

  During the image forming process, the primary transfer roller 5Bk is always in contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C are in contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5b contacts the endless belt-shaped intermediate transfer body 70 only when the image support P passes through the secondary transfer roller 5b and the secondary transfer is performed.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10Bk and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10Bk are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the drawing. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, primary transfer rollers 5Y, 5M, 5C, 5Bk, and cleaning means 6b. Consists of.

  The image forming apparatus of the present invention is generally applicable to electrophotographic apparatuses such as electrophotographic copying machines, laser printers, LED printers, and liquid crystal shutter printers. The present invention can be widely applied to such devices.

  In the following, the configuration and effects of the present invention are shown in the embodiments, but of course, the embodiments of the present invention are not limited to these. In addition, “part” in the sentence represents “part by mass”.

Synthesis example 1
(Synthesis of amorphous titanyl phthalocyanine)
1,3-diiminoisoindoline; 29.2 g was dispersed in 200 ml of orthodichlorobenzene, titanium tetra-n-butoxide; 20.4 g was added, and the mixture was heated at 150 to 160 ° C. for 5 hours in a nitrogen atmosphere. After allowing to cool, the precipitated crystals were filtered, washed with chloroform, washed with 2% aqueous hydrochloric acid, washed with water, washed with methanol, and dried to obtain 26.2 g (yield 91%) of crude titanyl phthalocyanine. Next, the crude titanyl phthalocyanine was dissolved by stirring in 250 ml of concentrated sulfuric acid at 5 ° C. or lower for 1 hour, and this was poured into 5 L of water at 20 ° C. The precipitated crystals were filtered and sufficiently washed with water to obtain 225 g of a wet paste product. The wet paste product was then frozen in a freezer, thawed again, filtered and dried to obtain 24.8 g of amorphous titanyl phthalocyanine (yield 86%).

(Synthesis of pigment (CG-1) of the present invention)
The above-mentioned amorphous titanyl phthalocyanine (10.0 g) and (2R, 3R) -2,3-butanediol (0.94 g, 0.6 equivalent ratio) (equivalent ratio is equivalent ratio to titanyl phthalocyanine, hereinafter the same) are combined with orthodichlorobenzene ( ODB) was mixed in 200 ml, and the mixture was heated and stirred at 60 to 70 ° C. for 6.0 hours. After standing overnight, methanol was added to the reaction solution, and the resulting crystals were filtered. The crystals after filtration were washed with methanol (a pigment containing (2R, 3R) -2,3-butanediol adduct titanyl phthalocyanine). CG-1: 10.3 g was obtained. The X-ray diffraction spectrum of CG-1 is shown in FIG. There are distinct peaks at 8.3 °, 24.7 °, 25.1 ° and 26.5 °. There is a peak in the 576 and 648 in the mass spectra, O-Ti-O both absorption appears Ti = O near 970 cm ^-1, around 630 cm ^-1 in the IR spectrum. In addition, since thermal analysis (TG) has a mass loss of about 7% at 390 to 410 ° C., a 1: 1 adduct of titanyl phthalocyanine and (2R, 3R) -2,3-butanediol (shown in Chemical Formula 1 above) A dehydrated condensation structure) and a non-adduct (not added) titanyl phthalocyanine mixed crystal.

It was 31.2 m < ² > / g when the BET specific surface area of the obtained CG-1 was measured with the flow type specific surface area automatic measuring device (Micrometrics flow soap type: Shimadzu Corporation).

Synthesis Example 2 (Synthesis of pigment (CG-2) of the present invention)
(2S, 3S) -2,3 in the same manner as in Synthesis Example 1 except that (2S, 3S) -2,3-butanediol was used instead of (2R, 3R) -2,3-butanediol. -Pigment CG-2 containing butanediol-titanyl phthalocyanine adduct was obtained: 10.5 g. In the X-ray diffraction spectrum of CG-2, clear peaks are observed at 8.3 °, 24.7 °, 25.1 °, and 26.5 °, and in the IR spectrum, Ti = O around 970 cm ⁻¹ , 630 cm. Both absorptions of O—Ti—O appear in the vicinity of ⁻¹ . The BET specific surface area of CG-2 is 30.5 m ² Synthesis Example 3 (Synthesis of Pigment (CG-3) of the Present Invention)
In the reaction of amorphous titanyl phthalocyanine of Synthesis Example 1 and (2R, 3R) -2,3-butanediol, the reaction temperature was changed to 90 to 100 ° C. instead of 60 to 70 ° C. (2R , 3R) -2,3-butanediol adduct, pigment CG-3 containing titanyl phthalocyanine: 10.6 g was obtained. In the X-ray diffraction spectrum of CG-3, clear peaks are observed at 8.3 °, 24.7 °, 25.1 °, and 26.5 °, and in the IR spectrum, Ti = O around 970 cm ⁻¹ , 630 cm. Both absorptions of O—Ti—O appear in the vicinity of ⁻¹ . The BET specific surface area of CG-3 was 20.5 m ² / g.

Synthesis Example 4 (Synthesis of pigment (CG-4) of the present invention)
In the reaction of the amorphous titanyl phthalocyanine of Synthesis Example 1 and (2R, 3R) -2,3-butanediol, the reaction temperature was changed to 130 to 140 ° C. instead of 60 to 70 ° C. (2R , 3R) -2,3-butanediol adduct titanyl phthalocyanine pigment CG-4: 10.6 g was obtained. In the X-ray diffraction spectrum of CG-4, clear peaks are observed at 8.3 °, 24.7 °, 25.1 °, and 26.5 °, and in the IR spectrum, Ti = O around 970 cm ⁻¹ , 630 cm. Both absorptions of O—Ti—O appear in the vicinity of ⁻¹ . The BET specific surface area of CG-4 was 13.5 m ² / g.

Synthesis Example 5 (Synthesis of pigment (CG-5) of the present invention)
In the reaction of amorphous titanyl phthalocyanine of Synthesis Example 1 with (2R, 3R) -2,3-butanediol, (2R, 3R) -2,3-butanediol is converted into a racemic 2,3- Pigment CG-5: 11.5 g containing (racemic) -2,3-butanediol adduct titanyl phthalocyanine was obtained in the same manner except that butanediol was used. Appear both absorption of O-Ti-O Ti = O near 970 cm ^-1, around 630 cm ^-1 in the IR spectrum of CG-5, BET specific surface area was 28.6m ² / g.

Synthesis Example 6 (Synthesis of Pigment (CG-6) of Comparative Example)
In the reaction of amorphous titanyl phthalocyanine of Synthesis Example 1 and (2R, 3R) -2,3-butanediol, 2.35 g (1.5 equivalent ratio) of (2R, 3R) -2,3-butanediol was used, Except that the reaction temperature was 130 to 140 ° C., 12.0 g of pigment CG-6 containing (2R, 3R) -2,3-butanediol adduct titanyl phthalocyanine was obtained. In the X-ray diffraction spectrum of CG-6 (FIG. 2 (1)), clear peaks are observed at 9.5 °, 16.4 °, 19.1 °, 24.7 °, 26.5 °, and IR disappeared Ti = O absorption near 970 cm ^-1 in the spectrum, the absorption of O-Ti-O appears in the vicinity of 630 cm ^-1. The BET specific surface area of CG-6 was 10.2 m ² / g.

Production of Photoreceptor 1 An intermediate layer coating solution having the following composition was dip coated on a cylindrical aluminum substrate to form an intermediate layer having a thickness of 4.0 μm.

<Intermediate layer coating solution>
The following composition was dispersed using a circulating wet disperser.

Polyamide resin “CM8000” (manufactured by Toray Industries, Inc.) 10 parts Titanium oxide (number average primary particle size 35 nm, primary surface treatment; silica / alumina treatment,
Secondary surface treatment; methyl hydrogen polysiloxane treatment) 30 parts Methanol 100 parts The following charge generation layer coating solution was dip coated thereon to form a charge generation layer having a thickness of 0.3 μm.

<Charge generation layer coating solution>
The following composition was mixed and dispersed with a circulating ultrasonic homogenizer RUS-600TCVP (manufactured by Nippon Seiki Seisakusho, 19.5 kHz, 600 W) (abbreviation: circulating homogenizer) at a circulating flow rate of 40 L / H for 0.5 hour.

Charge generation material: CG-1 of Synthesis Example 1 24 parts Polyvinyl butyral resin “ESREC BL-1” (manufactured by Sekisui Chemical Co., Ltd.) 12 parts 3-methyl-2-butanone / cyclohexanone = 4/1 (V / V) 400 parts A charge transport layer coating solution in which the following composition was mixed was applied thereon and dried by heating at 120 ° C. for 70 minutes to form a charge transport layer having a thickness of 20 μm.

<Charge transport layer coating solution>
Charge transport material: combined use of CTM-1A and CTM-2A (ratio 8/2) 150 parts Polycarbonate "Iupilon Z300" (manufactured by Mitsubishi Gas Chemical Company) 300 parts 2,6-di-t-butyl-4-phenylphenol 15 Part Solvent: Toluene / tetrahydrofuran = 2/8 (v / v) 2000 parts The above charge generation layer was dried on an aluminum support and then coated and dried at a film thickness of 0.3 μm to prepare a sample for reflection spectrum measurement. The reflection spectrum was measured using an optical film thickness measuring device Solid Lambda Thickness (manufactured by Spectra Corp.). The measured data is shown in FIG. The reflection spectrum was measured as a relative reflectance when the reflectance of the aluminum support was 100%. In order to remove irregularities due to interference fringes in the obtained reflection spectrum, the measurement data is approximated by a second order polynomial in the range of 685 to 715 nm and 765 to 795 nm, and the reflectance (R700) and reflectance (R780) are calculated. The ratio (R700 / R780) was calculated.

  Moreover, the data which measured the X-ray-diffraction spectrum using the sample which apply | coated and dried the said charge generation layer on the transparent glass plate are shown in FIG. 2 (2).

Method for measuring residual solvent A fixed amount of toluene as a solvent for the charge transport layer coating solution is measured and analyzed by gas chromatography (instrument: HP6890A (manufactured by Agilent), column: TC-WAX MEGABORE 30m carrier: N ₂ gas, heating rate: 10 ° C./min) Then, a calibration curve is created between the injection amount and the peak area.

  II. A certain amount of the photosensitive layer is peeled off from the photoreceptor, the photosensitive layer is dissolved in a high boiling point solvent, and subjected to gas chromatography analysis in the same manner as I above.

  III. The residual solvent amount is calculated from the calibration curve obtained in I above.

  IV. The residual solvent amount is obtained from the following formula.

Residual solvent amount (ppm) = ((mass of residual solvent amount in constant amount of photosensitive layer) / (mass of constant amount of photosensitive layer)) × 1000000
After production of the photoreceptor 1, the residual solvent amount of toluene in the photosensitive layer was measured by the above method, and it was 180 ppm.

Production of Photoreceptor 2 Photoreceptor 2 was produced in the same manner as in Photoreceptor 1 except that the dispersion time of the charge generation material coating solution was changed to 2.5 hours.

Production of Photoreceptor 3 Photoreceptor 3 was produced in the same manner as in Photoreceptor 1 except that CG-2 obtained in Synthesis Example 2 was used as the charge generation material.

Production of Photoreceptor 4 Photoreceptor 4 was produced in the same manner as in Photoreceptor 1 except that the charge generation layer coating solution was changed to ultrasonic dispersion under the following conditions.

<Charge generation layer coating solution>
The following compositions were mixed and subjected to ultrasonic dispersion for 1.5 hours in an ultrasonic cleaning tank (abbreviation: US bath) of 28 kHz and 500 W.

Charge generation material: CG-1 of Synthesis Example 1 24 parts Polyvinyl butyral resin “ESREC BL-1” (manufactured by Sekisui Chemical Co., Ltd.) 12 parts 3-methyl-2-butanone / cyclohexanone = 4/1 (V / V) 400 parts Production of Photoreceptor 5 Photoreceptor 5 was produced in the same manner as in Photoreceptor 4, except that the dispersion time of the charge generation material coating solution was changed to 4 hours.

Production of Photoreceptor 6 Photoreceptor 6 was produced in the same manner as in Photoreceptor 1 except that the charge generation layer coating solution was changed to sand mill (abbreviation: SM) dispersion under the following conditions.

<Charge generation layer coating solution>
The following compositions were mixed, and glass beads having an outer diameter of 1 mm were used as a dispersion medium, and dispersion was performed for 1 hour in a sand mill under conditions of a bead filling rate of 80% by volume and a rotation speed of 800 rpm.

Charge generation material: CG-1 of Synthesis Example 1 24 parts Polyvinyl butyral resin “ESREC BL-1” (manufactured by Sekisui Chemical Co., Ltd.) 12 parts 3-methyl-2-butanone / cyclohexanone = 4/1 (V / V) 400 parts Production of Photoreceptor 7 Photoreceptor 7 was produced in the same manner as in Photoreceptor 6, except that CG-3 obtained in Synthesis Example 3 was used as the charge generation material.

Production of Photoreceptor 8 Photoreceptor 8 was produced in the same manner as in Photoreceptor 6, except that CG-4 obtained in Synthesis Example 4 was used as the charge generation material.

Production of Photoreceptor 9 Photoreceptor 9 was produced in the same manner as in Photoreceptor 1 except that CG-5 obtained in Synthesis Example 5 was used as the charge generation material.

Production of Photoreceptor 10 (Comparative Example) Photoreceptor 10 was produced in the same manner as in Photoreceptor 6, except that the dispersion time of the charge generation layer coating solution was changed to 10 hours.

Production of Photoreceptor 11 (Comparative Example) Photoreceptor 11 was produced in the same manner as Photoreceptor 1 except that CG-4 obtained in Synthesis Example 4 was used as the charge generation material.

Production of Photoreceptor 12 (Comparative Example) Photoreceptor 12 was produced in the same manner as Photoreceptor 6, except that CG-6 obtained in Synthesis Example 6 was used as the charge generation material.

  For the photoconductors 2 to 12, the reflection spectrum was measured in the same manner as the photoconductor 1. The results are shown in Table 2. The values of the reflection spectrum in Table 1 are values measured in the charge generation layer, but almost the same values are obtained even if the charge transport layer is measured after coating.

Production of Photoreceptor 13 In production of Photoreceptor 1, the charge transport material in the charge transport layer: CTM-1A and CTM-2A were used in the same manner except that the ratio of the combination of CTM-1A and CTM-2A was changed from (Ratio 8/2) to (10/0). Thus, a photoreceptor 13 was produced.

Preparation of Photoreceptor 14 In preparation of Photoreceptor 1, the charge transport material in the charge transport layer: CTM-1A and CTM-2A were used in the same manner except that the combined ratio of CTM-1A and CTM-2A was changed from (Ratio 8/2) to (6/4). Thus, a photoreceptor 14 was produced.

Production of Photoreceptor 15 In production of Photoreceptor 1, the charge transport material of the charge transport layer: CTM-1A and CTM-2A were used in the same manner except that the combined ratio of CTM-1A and CTM-2A was changed from (Ratio 8/2) to (5/5). Thus, a photoreceptor 15 was produced.

Production of Photoreceptor 16 Photoreceptor 16 was produced in the same manner as in the production of Photoreceptor 1 except that the volume ratio (v / v) of solvent / toluene / tetrahydrofuran in the charge transport layer coating solution was changed from 2/8 to 5/5. Was made.

Production of photoconductor 17 In production of photoconductor 1, the volume ratio (v / v) of solvent: toluene / tetrahydrofuran in the charge transport layer coating solution was changed from 2/8 to 1/9, and drying after coating the charge transport layer was performed. Photoconductor 17 was prepared in the same manner except that the angle was changed from 120 °, 70 minutes to 130 °, 60 minutes.

Preparation of Photoreceptor 18 (Comparative Example) Photoreceptor 18 was prepared in the same manner as in preparation of photoreceptor 17, except that the drying temperature after application of the charge transport layer was changed from 120 °, 70 minutes to 130 °, 70 minutes.

Production of Photoreceptor 19 Photoreceptor 19 was produced in the same manner as in production of Photoreceptor 1 except that the drying after coating the charge transport layer was changed from 120 °, 70 minutes to 110 °, 70 minutes.

Production of Photoreceptor 20 (Comparative Example) Photoreceptor 20 was produced in the same manner as in production of Photoreceptor 1 except that the drying after applying the charge transport layer was changed from 120 °, 70 minutes to 110 °, 50 minutes.

Production of Photoreceptor 21 Photoreceptor 21 was produced in the same manner as in production of Photoreceptor 1 except that the solvent of the charge transport layer coating solution: toluene / tetrahydrofuran was changed to chlorobenzene / tetrahydrofuran: volume ratio (v / v) to 2/8. Was made.

Preparation of Photoconductor 22 Photoconductor 22 was prepared in the same manner as in preparation of Photoconductor 1, except that the charge transport material of the charge transport layer coating solution was changed to the combined use of CTM-1A and CTM-2B (ratio 9/1). Produced.

Production of Photoreceptor 23 Photoreceptor 23 was produced in the same manner as in production of Photoreceptor 1 except that the charge transport material of the charge transport layer coating solution was changed to the combined use of CTM-1B and CTM-2B (ratio 7/3). Produced.

Production of Photoreceptor 24 Photoreceptor 24 was produced in the same manner as in the production of Photoreceptor 1 except that the composition ratio of the charge transport layer coating solution was changed as follows.
<Charge transport layer coating solution>
Charge transport material: Combined use of CTM-1A and CTM-2A (ratio 8/2) 210 parts Polycarbonate “Iupilon Z300” (manufactured by Mitsubishi Gas Chemical Co., Inc.) 300 parts 2,6-di-t-butyl-4-phenylphenol 21 Parts Solvent: toluene / tetrahydrofuran = 2/8 (v / v) 2000 parts Preparation of photoconductor 25 Photoconductor 25 was prepared in the same manner as in preparation of photoconductor 1, except that the composition ratio of the charge transport layer coating solution was changed as follows. 25 was produced.
<Charge transport layer coating solution>
Charge transport material: combined use of CTM-1A and CTM-2A (ratio 8/2) 120 parts Polycarbonate “Iupilon Z300” (manufactured by Mitsubishi Gas Chemical Co., Inc.) 300 parts 2,6-di-t-butyl-4-phenylphenol 12 Parts Solvent: toluene / tetrahydrofuran = 2/8 (v / v) 2000 parts Production of photoconductor 26 Photoconductor 26 was prepared in the same manner as in production of photoconductor 1, except that the composition ratio of the charge transport layer coating solution was changed to the following. 26 was produced.
<Charge transport layer coating solution>
Charge transport material: Combined use of CTM-1A and CTM-2A (ratio 8/2) 110 parts Polycarbonate “Iupilon Z300” (manufactured by Mitsubishi Gas Chemical Co., Inc.) 300 parts 2,6-di-t-butyl-4-phenylphenol 11 Parts Solvent: toluene / tetrahydrofuran = 2/8 (v / v) 2000 parts Production of photoconductor 27 Photoconductor 27 was prepared in the same manner as photoconductor 1 except that the composition ratio of the charge transport layer coating solution was changed as follows. 27 was produced.
<Charge transport layer coating solution>
Charge transport material: combined use of CTM-1A and CTM-2A (ratio 8/2) 200 parts Polycarbonate "Iupilon Z300" (manufactured by Mitsubishi Gas Chemical Company) 300 parts 2,6-di-t-butyl-4-phenylphenol 20 Parts Solvent: toluene / tetrahydrofuran = 2/8 (v / v) 2000 parts

In Table 1,
Mixed crystal (R, R form) is a pigment containing titanyl phthalocyanine and (2R, 3R) -2,3-butanediol titanyl phthalocyanine adduct. Mixed crystal (S, S form) is titanyl phthalocyanine and (2S , 3S) -2,3-Butanediol titanyl phthalocyanine adduct A mixed crystal (racemic) is a pigment containing titanyl phthalocyanine and (racemic) -2,3-butanediol titanyl phthalocyanine adduct The simple substance means a pigment containing only the (2R, 3R) -2,3-butanediol titanyl phthalocyanine adduct. Characteristic Evaluation 1 to 21 were evaluated using a commercially available full-color multifunction apparatus bizhub PRO C6500 (manufactured by Konica Minolta Business Technologies, Inc .; using exposure light of a semiconductor laser of 600 dpi and 780 nm) basically having the configuration shown in FIG. Since the full-color multifunction peripheral has four image forming units, the photosensitive members of each image forming unit are the same type of photosensitive member (for example, in the case of the photosensitive member 1, four photosensitive members 1 are provided. Prepared) and unified and evaluated. Each evaluation was performed under the conditions of 30 ° C. and 80% RH, and 50,000 sheets of A4 images with a YMCBk color printing ratio of 2.5% were printed on neutral A4 paper. The environmental conditions were evaluated.

<Evaluation of potential stability>
The digital copying machine bizhub PRO C6500 was subjected to a printing durability test of 500,000 A4 sheets in a high temperature and high humidity environment (HH) to evaluate potential stability.

  Judgment criteria are as shown below.

  The initial charging potential was adjusted to 600 ± 50 V, and evaluation was performed based on the amount of change (ΔV) in the exposed portion potential after the initial and 50,000 sheets.

A: ΔV is less than 50V (good)
○: ΔV is 50 to 100 V (no problem in practical use)
×: ΔV is larger than 100V (practical problem)
(Evaluation of gas resistance)
With the digital copier bizhub PRO C6500, after the 50,000-sheet print-out printing test under environmental conditions of 30 ° C. and 80% RH, the main power supply of the actual machine is immediately stopped so that air does not flow through the fan part. It was covered with tape. Immediately after the stop, the power was turned on and the image was ready for printing. Immediately thereafter, a halftone image (relative reflection density of 0.4 with a Macbeth densitometer) and a 6 dot lattice image of the entire A3 were printed on the entire neutral paper of A3. The state of the printed image was observed and the following evaluation was performed.

◎: No blurring in halftone and grid images (good)
○: A thin strip-like density decrease in the longitudinal direction of the photoreceptor is observed only in the halftone image (no problem in practical use)
X: Occurrence of strip-shaped image blurring, loss of lattice image or narrowing of line width (problem in practical use).

(Crack resistance evaluation)
A large amount of hand cream and processing oil were applied to the surface of the photoconductor with a cotton swab and left at room temperature and 60 ° C. for 1 hour, 7 days, 30 days, and 60 days, and the occurrence of cracks on the surface was observed.

A: No occurrence at room temperature and 60 ° C even after 60 days (good)
○: In any of the above evaluations, only a slight crack occurred in the processed oil, but there was no actual damage (no problem in practical use)
X: Hand cream and processing oil cracks occurred at any of the above evaluations (practical problems).

Image Evaluation With the above digital copying machine bizhub PRO C6500, before and after the 50,000-sheet print durability test under environmental conditions of 30 ° C. and 80% RH, the exposed area image (black solid image) and the unexposed area image on A4 paper. (White solid image) was prepared, and image density and fog were evaluated.

Image density:
Image density was measured using Macbeth RD-918. The relative reflection density was measured with the paper reflection density set to “0”. If there is a decrease in sensitivity or an increase in residual potential in a large number of copies, the image density decreases.

A: Black solid image is 1.2 or more B: Black solid image is less than 1.0 to less than 1.2 X: Black solid image is less than 1.0 Image fog:
Using a Macbeth reflection densitometer “RD-918”, the density of unprinted copy paper (white paper) is measured at 20 locations in absolute image density, and the average value is defined as the white paper density. Next, the white background portion of the copy image was similarly measured at 20 locations at the absolute image density, and the value obtained by subtracting the white paper density from the average density was evaluated as the fog density. If the decrease in the unexposed portion potential is increased, fogging occurs.

A: Solid white image density is less than 0.005 (good)
○: Solid white image density of 0.005 or more and less than 0.01 (no problem in practical use)
X: 0.01 or more (practical problem)

  The photoreceptors 1 to 9, 13, 14, 15, 16, 17, 19, 21 to 27 in the present invention have at least no practical problem, but the photoreceptors 10 to 12, 18, 20 shows that there is a problem with at least one of the characteristics.

1Y, 1M, 1C, 1Bk Photosensitive drum 2Y, 2M, 2C, 2Bk Charging unit 3Y, 3M, 3C, 3Bk Image exposure unit 4Y, 4M, 4C, 4Bk Developing unit 10Y, 10M, 10C, 10Bk Image forming unit

Claims (4)

In an electrophotographic photosensitive member having a charge generation layer and a charge transport layer on a conductive support, the charge generation layer contains a pigment containing titanyl phthalocyanine and a 2,3-butanediol adduct titanyl phthalocyanine, and the charge generation The ratio (R700 / R780) of the reflectance (R700) at 700 nm and the reflectance (R780) at 780 nm of the reflection spectrum of the layer is 0.8 to 1.3, and the charge transport layer has the following general formula (1) An electrophotographic photoreceptor comprising the compound of formula (3), wherein the residual solvent of the following general formula (3) is in the range of 20 to 10,000 ppm.
However, the reflectance is a reflectance measured by forming a photosensitive layer (charge generation layer) on an aluminum support, and is a relative reflectance when the reflectance of the aluminum support is 100%.
Further, the amount of the residual solvent of the following general formula (3) is the amount of the residual solvent in all layers formed on the conductive support.

(In the general formula (1), R ₁ represents an alkyl group, an alkoxy group or a halogen atom, and R ₂ represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom.)

(In General Formula (3), X and Y each independently represent a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, but they are not both hydrogen atoms.) 2. The electrophotographic photoreceptor according to claim 1, wherein the charge transport layer further contains 40% or less of the compound of the following general formula (2) with respect to the compound of the general formula (1).

(In the general formula (2), R ₃ represents an alkyl group, an alkoxy group or a halogen atom, and R ₄ represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom.)   The total content of the compound of the said General formula (1) and General formula (2) is 40-67 mass parts with respect to 100 mass parts of binders of a charge transport layer, The electrophotography of Claim 2 characterized by the above-mentioned. Photoconductor.   The means for forming an electrostatic latent image on the electrophotographic photosensitive member according to claim 1, means for developing the electrostatic latent image with toner, and transferring the formed toner image to the image support. An image forming apparatus comprising at least means for fixing the toner image after transfer.

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