JPH028251A - Purification of polycyclic quinone pigment by sublimation and photoreceptor for electrophotography containing the same pigment - Google Patents

Abstract

PURPOSE:To efficiently prepare the subject pigment of high purity with spectral sensitivity properties suitable for printer, etc., capable of providing a photoreceptor for electrophotography excellent in electrophotographic properties by purifying a polycyclic quinone pigment by sublimation thereof under a specified condition. CONSTITUTION:A polycyclic quinone pigment (e.g., dibenzopyrenequinone pigment of the formula) is sublimated and purified at 350-410 deg.C raw material temperature and under 6X10-<4>Torr degree of vacuum during the sublimation. In addition, the above-mentioned sublimation-purification is carried out, e.g., by using an apparatus so constituted that the raw material 4 may be placed in a sublimation board 3 in vacuum devices 1, heated by a heater attached to the upper part and evaporated and a purified pigment recovered on a recovery plate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a sublimation purification method for a polycyclic quinone pigment, and an electrophotographic photoreceptor containing the polycyclic quinone pigment.

[Prior Art] Electrophotographic photoreceptors are generally widely used in electrophotographic copying machines, printers, etc., but the characteristics required of the electrophotographic photoreceptors differ depending on the use. For example, in electrophotographic copying machines, especially office copying machines, importance is placed on the reproducibility of red images (for example, red stamp characters, underlines, etc.) as well as the reproducibility of black and blue originals. Ru. In order to achieve these types of copy image reproducibility, it is desirable that the spectral sensitivity of the electrophotographic photoreceptor be well distributed in the range of 450 ni to 600 nm (620 nm at the longest). The spectral sensitivity of the electrophotographic photoreceptor is 6
If it extends to around 60 rv or 700 nl, the reproduction reproducibility of the above-mentioned red image will be poor, making it undesirable for office copying machines. For this reason, in electrophotographic photoreceptors that use ordinary azo pigments, especially disazo pigments and trisazo pigments, as charge-generating substances, the spectral sensitivity extends to around 700 nm, so light with wavelengths of 620 to 630 nm or more can be filtered out. It is cut and used with lower red sensitivity. However, when such a filter is used, not only the red sensitivity but also the short wavelength sensitivity decreases, resulting in a disadvantage that the overall sensitivity decreases. Furthermore, when such an azo pigment is used as a charge generating substance, it is necessary to form a charge generating layer with a thin film thickness of approximately 0.1 to 0.3 μm due to its low charge transport ability. like? When the film is applied using the dip coating method, which is a common manufacturing method, unevenness and
Coating defects such as dripping and agglomeration are likely to occur, resulting in lower yields and
This led to an increase in costs.

Furthermore, polycyclic quinone pigments are known as pigments with good copy image reproducibility (see JP-A-57-67933). Polycyclic quinone pigments are 450nllll to 570nn+
It has high sensitivity in the region of Has characteristics.

[Problems to be Solved by the Invention] By the way, most of the polycyclic quinone pigments used here are those that are commercially available or those that have been independently synthesized. However, when such polycyclic quinone pigments are used in the construction of electrophotographic photoreceptors, the following problems arise.

In other words, since the polycyclic quinone pigments mentioned above contain impurities such as by-products, surfactants, and inorganic salts, the generated charge carriers are trapped and cannot be repeatedly copied many times. If this is done, the residual potential will accumulate and fog will occur on the copied image.

In order to solve this problem, there is a method of using polycyclic quinone pigments produced by sublimation, taking advantage of the property that polycyclic quinone pigments have sublimation properties, for example, in Japanese Patent Application Laid-Open No.
It is described in Japanese Patent No. 7-67934. However, with conventional sublimation purification methods, it is not always possible to increase the recovery rate because the powder of the sublimation purified product scatters during purification, or impurities are not sufficiently removed and it is not possible to increase the purity. Therefore, satisfactory results in terms of electrophotographic properties could not be obtained.

For this reason, there has been a desire for an electrophotographic photoreceptor that uses a polycyclic quinone pigment as a charge generating substance and has sufficiently good characteristics in practice.

The present invention has been made in view of the above conventional problems,
Firstly, it provides a sublimation purification method for efficiently obtaining a highly pure polycyclic quinone pigment, and secondly, it has spectral sensitivity characteristics suitable for electrophotographic copying machines, printers, etc., and has excellent electrophotographic characteristics. The purpose of the present invention is to provide an electrophotographic photoreceptor that has the following characteristics.

[Means for solving the problem] The sublimation purification method of the present invention uses a vacuum degree of 6×10'To during sublimation.
It is characterized in that polycyclic quinone pigments are purified by sublimation at a temperature below rr and at a raw material temperature of 350 to 410°C during sublimation. Further, the electrophotographic photoreceptor of the present invention is characterized in that the photosensitive layer contains a polycyclic quinone pigment purified by sublimation by such a method.

The method for producing M by sublimation of polycyclic quinone pigments according to the present invention will be described. FIG. 1 is a sectional view showing an example of a specific apparatus used to carry out the sublimation purification method of the present invention.

As shown in FIG. 1, the sublimation purification apparatus used in the present invention includes a recovery plate (2), a sublimation boat (3), and a heater (5) inside a vacuum apparatus (1). The sublimation boat (3) mentioned here is for putting the raw material (4) in and evaporating it, and is made of, for example, graphite.

The recovery plate (2) is attached with screws or the like to the stand (7) on which the sublimation boat is placed, and can be removed after sublimation purification to recover the purified pigment. A vacuum level monitor (6) is attached to the vacuum device (1) so that the vacuum level can be adjusted. Heater (5
) is attached above the raw material (4) and heats the raw material (4) to a predetermined temperature range.

Further, in the above-mentioned sublimation purification apparatus, it is preferable that a net is installed in the sublimation boat (3) so as to cover the raw material, and more preferably, the net has a mesh size of 30 to 400. be.

Using an apparatus with such a configuration, the raw material temperature during sublimation is 350~
410℃ and degree of vacuum during sublimation 6X10-4T or
By performing sublimation purification of a polycyclic quinone pigment under the condition of r or less, a highly pure polycyclic quinone pigment can be obtained in high yield.

Examples of the polycyclic quinone pigments used in the present invention include an anthrone pigment represented by the following formula [A], a dibenzpyrenequinone pigment represented by the following formula [8], and a dibenzpyrene quinone pigment represented by the following formula [CI]. At least one selected from pyranthrone pigments can be mentioned.

General formula [A] General formula [B] In the formula, X represents a halogen atom, a nitro group, a cyam L acyl group, or a carboxyl group, n represents an integer of 0 to 4, and m represents an integer of 0 to 6. .

- Specific compounds of the andanthrone pigment represented by formula [A] are as follows.

-Specific compound examples of dibenzpyrenequinone pigments represented by formula [CI [Al1 [A21 [A91] [A3] [A4] [A10] [A5] [Ac1 [A11] [A71 [A8] General formula [81] The following are examples.

[B1] [B51 ○ [B2] [B11 [B3] [B71 [B41 [B81 [B11 [C1] General formula [C] of the pyranthrone pigment shown in [C2] Specific examples of compounds are as follows.

[C31 [C4] [C7] [C51 [C81 [C61] [C9] The polycyclic quinone pigments described above can be synthesized by known methods, but can also be obtained as commercial products.

Various configurations of electrophotographic photoreceptors are known, but
The electrophotographic photoreceptor of the present invention can take any of these forms.

Usually, the configuration is as shown in FIGS. 2 to 7. Figures 2 and 3
In the figure, a photosensitive layer 11 consisting of a laminate of a charge generation layer 9 containing the above-mentioned polycyclic quinone pigment on a conductive support 8 and a charge transport layer 10 containing as a main component a charge transport substance to be described later. 2 and 3, the stacking order of the charge generation B9 and the charge transport layer 10 is different. As shown in FIGS. 4 and 5, this photosensitive layer 11 may be provided on a conductive support with an intermediate layer 12 such as an adhesive layer or a barrier layer interposed therebetween. When the photosensitive layer 11 has a two-layer structure in this manner, a photoreceptor having the most excellent electrophotographic properties can be obtained. Further, in the present invention, as shown in FIG. 6 and factor 7, a photosensitive layer 11 formed by dispersing the polycyclic quinone pigment in a layer 13 containing a charge transport substance is directly deposited on the conductive support 8. Alternatively, it may be provided via the intermediate layer 12. In addition, in the present invention, the outermost layer contains r! One layer may be provided.

The charge generation layer 9 constituting the two-layer photosensitive layer 11 is applied directly to the conductive support 8 or the charge transport layer 10, or if necessary, to an intermediate layer 12 such as an adhesive layer or a barrier layer.
It can be formed, for example, by the following method.

M-1) A method of applying a solution in which a polycyclic quinone pigment is dissolved in a suitable solvent, or a solution in which a binder resin is added and mixed as necessary.

M-2) The polycyclic quinone compound is pulverized into fine particles (preferably with a particle size of 5 μm) in a dispersion medium using a ball mill, homomixer, etc.
(hereinafter, more preferably 1 μm or less), and a method in which a binder resin is added and mixed and dispersed as necessary, and a dispersion is applied.

Further, this polycyclic quinone pigment may be used in combination with other charge generating substances to form a charge generating layer.

Examples of the solvent or dispersion medium used for forming the charge generation layer include n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N,N-dimethylformamide, acetone, methylethylketone, cyclohexanone, and benzene. , toluene, xylene, chloroform, 1
．． 2-dichloroethane, 1,2-dichloropropane, 1
゜1.2-trichloroethane, 1,1.1-trichloroethane, trichloroethylene, tetrachloroethane, dichloromethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate,
Examples include butyl acetate, dimethyl sulfoxide, methyl cellosolve, and the like.

Further, the charge transport layer can be formed in the same manner as the charge generation layer described above.

Any binder resin can be used to form the charge generation layer or the charge transport layer, but a film-forming polymer that is hydrophobic, has high electric conductivity, and is electrically insulating is used. is preferable. Examples of such high molecular weight polymers include, but are not limited to, the following.

P-1) Polycarbonate P-2) Polyester P-3) Methacrylic acid P-4) Acrylic resin P-5) Polyvinyl chloride P-6) Polyvinylidene chloride P-7) Polystyrene P-8) Polyvinyl acetate P-9 ) Styrene-butadiene copolymer p -io) Vinylidene chloride-acrylonitrile copolymer p-11) Vinyl chloride-vinyl acetate copolymer p-12
) Vinyl chloride-vinyl acetate-maleic anhydride copolymer p-13) Silicone resin p-14) Silicone-alkyd resin p-15) Phenol formaldehyde resin P-16) Styrene-alkyd resin p-17) Poly-N- Vinyl carbazole p-18) Polyvinyl butyral p-19) Polyvinyl formal These binder resins can be used alone or as a mixture of two or more.

In the charge generation layer formed as described above, the weight ratio of the polycyclic quinone pigment to the binder is preferably 10.
0:0 to 1000. If the content of the charge generating substance is less than this, the photosensitivity will be low and the residual potential will increase.
Moreover, if the amount is more than this, dark decay and acceptance potential decrease.

The thickness of the charge generation layer to be formed is preferably 0.01.
~10 μm.

Further, in the charge transport layer formed as described above, the charge transport material is the binder resin 100 in the charge transport layer.
It is preferably 20 to 200 parts by weight, particularly preferably 30 to 150 parts by weight.

Further, the thickness of the charge transport layer to be formed is preferably 5 to 5.
50 μm, particularly preferably 5 to 30 μm.

The charge transport substances used in the present invention include carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidasilone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, and hydrazone compounds. , pyrazoline derivatives, oxacilone derivatives, benzothiazole derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, poly-N-vinylcarbazole, It may be one or more selected from poly-1-vinylpyrene, poly-9-nylanthracene, and the like.

Specific examples of such charge-transporting substances are disclosed in Japanese Patent Application No. 61-1.
No. 95881. The general formula is listed below.

As a charge transport material, a styryl compound having the following general formula [I] or [I[] can be used.

General formula [Equation 1: (However, in this general formula, R' R2: i! represents a substituted or unsubstituted alkyl group or aryl group, and substituents include an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, A halogen atom and an aryl group are used.

Ar', Ar2: represents a substituted or unsubstituted aryl group, and as a substituent, an alkyl group, an alkoxy group, a substituted AMI LL hydroxyl group, a halogen atom, or an aryl group is used.

R3R4: il represents a substituted or unsubstituted aryl group or a hydrogen atom, and as a substituent, an alkyl group, an alkoxy group, a substituted amino LL hydroxyl group, a halogen atom, or an aryl group is used. ) General formula [■]: (However, in this general formula, R5: substituted or unsubstituted aryl group, R6: hydrogen atom, halogen atom, substituted or unsubstituted alkyl group,
It represents an alkoxy group, an amine group, a substituted amine LL water M group, R7, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group. ) In addition, the following general formulas [1], [IV], [IVa], [I
Vb ] Also 1. t [V] (7) A hydrazone compound can also be used General formula [■]: (However, in this general formula, R8 and R9: each a hydrogen atom or a halogen atom, RIO and R11: each a substituted or unsubstituted aryl group, Ar3: @represents a substituted or unsubstituted arylene group.) General formula [■]: (However, in this general formula, R12: M-substituted or unsubstituted aryl group, substituted or unsubstituted carbazolyl group, or Represents a substituted or unsubstituted heterocyclic group, R13R14 and R15: represents a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.) General formula [IVa]: R'' ( However, in this general formula, R16: methyl group, ethyl group, 2-hydroxyethyl group, or 2-chloroethyl group, R17: methyl group, ethyl group, benzyl group, or phenyl group, R18: methyl group, ethyl group, benzyl group or a phenyl group.) General formula [IVbl (However, in this general formula, R+9 is a substituted or unsubstituted naphthyl group; R20 is a substituted or unsubstituted alkyl group,
Aralkyl group or aryl B, R2F is a hydrogen atom,
The alkyl group or alkoxy B, R22 and R23 do not represent the same or different groups consisting of a substituted or unsubstituted alkyl group, aralkyl group or aryl group. ) General formula [V]: (However, in this formula, R24: @substituted or unsubstituted aryl group or substituted or unsubstituted heterocyclic group, R25: hydrogen atom, substituted or unsubstituted alkyl group, or substituted or unsubstituted heterocyclic group) (Unsubstituted aryl group, Q: hydrogen atom, halogen atom, alkyl group, substituted amino group, alkoxy group, or cyano group, S: O or an integer of 1) In addition, as a charge transport substance, the following general formula [ Pyrazoline compounds of VI] can also be used.

- Formula [VI]: (However, in this - formula, ffi: O or 1, R26 and R27: m+i or unsubstituted aryl group, R28: substituted or unsubstituted aryl group, or heterocyclic group, R29 and R30 : Hydrogen atom, alkyl group having 1 to 4 carbon atoms, or substituted or unsubstituted aryl group or aralkyl group (However, both R29 and R30 are not hydrogen atoms, and when the above l is O, R29 is not a hydrogen atom.) Furthermore, an amine derivative of the following general formula [VI] can also be used as a charge transport material.

General formula [V[]: (However, in this formula, Ar4.Ar5 represents a substituted or unsubstituted phenyl group, and a halogen atom, an alkyl group, an alkenyl group, a nitro group, or an alkoxy group is used as a substituent.

Ar6: represents a substituted or unsubstituted phenyl group, naphthyl group, anthryl group, fluorenyl group, heterocyclic group,
Substituents include alkyl groups, alkoxy groups, halogen atoms, hydroxyl groups, aryloxy groups, aryl groups, amimu L
Nitro group, piperidino group, morpholino group, naphthyl group,
Anthryl groups and substituted amino groups are used. However, an acyl group, an alkyl group, an aryl group, or an aralkyl group is used as a substituent for the substituted amino group. ) Furthermore, a compound of the following general formula [■] can also be used as a charge transport material.

General formula [■]: (However, in this formula, A r 7 represents a substituted or unsubstituted arylene group, R31, R32, R33 and R34; substituted or unsubstituted alkyl group, substituted or unsubstituted aryl basis,
Or represents a substituted or unsubstituted aralkyl group. ) Furthermore, compound-b of the following general formula [IX] can be used as a charge transport substance.

General formula [IX]: (However, in this formula, R35, R36, R37 and R3
8 is a hydrogen atom, a substituted or unsubstituted argyl group, a cycloalkyl group, an alkenyl group, an aryl group,
Benzyl group or aralkyl group, R39 and R411,
1 hydrogen atom, substituted or unsubstituted carbon atom, respectively
~40 alkyl, cycloalkyl, alkenyl, cycloalkenyl, aryl or aralgyl I (
fl, 1. R'' and R40 jointly have 3 to 1 carbon atoms
0 saturated or unsaturated hydrocarbon rings may be formed. ) R4+, R42, R43 and R44 are each a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted argyl group, a cycloalkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkoxy group, an amino group, an alkylamino group Or it is an arylamino group. ] The 18 conductive supports used in the electrophotographic photoreceptor of the present invention include metal plates including alloys, metal drums, conductive polymers, conductive compounds such as indium oxide, aluminum including alloys, palladium, etc. Examples include paper, plastic film, etc., made conductive by coating, vapor depositing, or laminating a gold nR layer such as gold. As an intermediate layer such as an adhesive layer or a barrier layer, in addition to the high molecular weight polymer used as the binder resin, polyvinyl alcohol, ethyl cellulose, and the like can be used.

[Example] Next, the present invention will be explained with reference to Examples, but the present invention is not limited by these.

4,10-dibromanthanthrone (Monolite Red 2 YI) is a commercially available polycyclic quinone pigment.
Manufactured by C1 company C. I, No. 59300) L
Fig. 1 Filled into a graphite sublimation boat placed in the vacuum device shown in Figure 1, sublimated for 5 minutes at the raw material temperature and vacuum degree shown in Table 1, and deposited on a collection plate placed 15 cm above the sublimation boat. Purified pigment sample No. 1~N0.
I got 20.

Purified pigment samples No. 1 to No. 20 layers were measured and the recovery rate relative to the amount charged was determined. The results are shown in Table-1.

Next, the thus obtained purified pigment samples No. 1 to No. 2
3 g of 0 was added to 1,2-dichloroethane 10 (hQ) and dispersed in a ball mill for 48 hours to obtain a coating solution for forming a charge generation layer. Next, a coating solution for forming a charge generation layer was obtained. An intermediate layer made of a vinyl chloride-vinyl acetate-maleic anhydride copolymer resin having a thickness of 0.1 μm is provided on the substrate, and the charge generation layer forming coating liquid is applied onto the intermediate layer by a wire bar coating method to obtain a thickness of 0.1 μm. A charge generation layer having a thickness of 1 micron was formed.

On the other hand, 4-methyl-4''-(p-chlorostyryl>triphenylamine 10o and 2,4,6-dolinitro 1
-Chlorbenzene 0. 0111 and polycarbonate resin “Panlite l-1250J (manufactured by Ryotaikasei Co., Ltd.)”
1 3Q tr 1, 2-Schiff CJ) Lt eta>
The charge transport layer obtained was dissolved in 1001 fl of a solvent, and the resulting charge transport layer was applied onto the charge generation layer using a doctor blade coating method, and dried at a temperature of 80° C. for 1 hour to form a layer with a thickness of 1.
A charge transport layer of 4 μm was formed, and an electrophotographic photoreceptor sample F4N was formed.
o. 1 to 20 (Photoreceptor sample No. is purified pigment sample No.
) was created.

The electrophotographic photoreceptor thus obtained was mounted on an electrometer RSP-428 type (manufactured by Kawaguchi-i Kiki Seisakusho), and the voltage applied to the charger discharge electrode was set to 16.
Charging operation was performed for 5 seconds as KV, and the band i! on the surface of the photosensitive layer immediately after this charging operation was performed. Potential V.

(V), the value 5 seconds after this charging is finished, the dark decay rate (DD) of dark decay from 1 to the initial value Vo, and the charge potential attenuating from 500V to 50V due to subsequent light irradiation. Necessary irradiation light IEr (lux-see
) was measured. The results are shown in Table 1. As can be seen from Table 1, the samples of the present invention have a good recovery rate of purified pigment and also exhibit good electrophotographic properties such as dark decay and sensitivity.

On the other hand, in the comparative samples, it was not possible to efficiently obtain purified pigments with high purity, and the results of electrophotographic properties were also not satisfactory.

[Effects of the Invention] As described in detail above, the present invention makes it possible to provide an electrophotographic photoreceptor that has spectral sensitivity characteristics suitable for electrophotographic copying machines, printers, etc., and has excellent electrophotographic characteristics. Ta. In addition, a sublimation purification method for efficiently obtaining the highly pure polycyclic quinone pigments required for this purpose was investigated, and favorable results were obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a specific apparatus used to carry out the sublimation purification method according to the present invention. FIGS. 2 to 7 are cross-sectional views respectively showing structural examples of the photoreceptor of the present invention. 1... Vacuum device 2... Recovery plate 3... Sublimation boat 4... Raw material 5... Heater 6... Vacuum level monitor 7...
- Stand 8... Conductive support 9... Charge generation layer 10... Charge transport layer 11... Photosensitive layer 1
2... Intermediate layer 13... Features a charge transport material

Claims (2)

[Claims] (1) In a method for sublimation purification of polycyclic quinone pigments,
A sublimation purification method for polycyclic quinone pigments, characterized in that the raw material temperature during sublimation is 350 to 410°C, and the degree of vacuum during sublimation is 6 x 10^-^4 Torr or less. (2) A polycyclic quinone pigment characterized in that the photosensitive layer contains a polycyclic quinone pigment purified by sublimation at a raw material temperature of 350 to 410°C during sublimation and a vacuum level of 6 x 10^-^4 Torr or less during sublimation. An electrophotographic photoreceptor containing a ring quinone pigment.