JPH04204456A - Photoconductive material and its manufacturing method - Google Patents

Abstract

PURPOSE:To obtain a photoconductive material having sensitivity up to an IR wavelength region by preparing an org. polymer contg. specified repeating units and dispersing other org. material whose decomposition temp. is above a heat treatment temp. for crystallizing the org. polymer. CONSTITUTION:An org. polymer contg. repeating units represented by formula I is prepd. and other org. material whose decomposition temp. is above a heat treatment temp. for crystallizing the org. polymer is dispersed in the org. polymer. In the formula I, n>=2, X is 0, S, Se or Te, Y is an optionally substd. arom. group and Z is a group contg. an imido ring. The crystallinity of the org. polymer can be remarkably enhanced by heat treatment, the interaction between the adjacent macromolecules is strengthened by the enhanced crystallinity and light absorption in a film, electric charge generating ability and electric charge transferring ability are increased. A photoconductive material having satisfactory photosensitivity in a wide wavelength region from visible wavelength to IR long wavelength is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a photoconductive material suitable for a photoconductor in electrophotographic copying machines, optical printers, etc., and a method for manufacturing the same.

[Prior Art] In recent years, the development of photoconductive organic materials has become active as photoconductive materials for electrophotography. The present applicant proposed polyparaphenylene sulfide (hereinafter referred to as PPS) as a material with high carrier transport ability. The carrier transport ability of this PPS is greatly improved by heat treatment in oxygen. However, the light absorption wavelength range of PPS is limited to wavelengths shorter than visible light. Therefore, we proposed incorporating a functional group with a light absorption band in the visible light region into the skeleton of the PPS molecule.

- For example, if it has an imide ring, the incorporated polymer will be a polyimide. The sensitivity wavelength range extends to the visible range of 57 Qnm.

[Problems to be Solved by the Invention] However, the conventional technology has a problem in that the photosensitivity region decreases significantly on the longer wavelength side than around 600 nm. Therefore, when a semiconductor laser with an oscillation wavelength of 70 C1 nm or more is considered as a light source, further sensitization is required.

SUMMARY OF THE INVENTION In order to solve the problems of the prior art described above, an object of the present invention is to provide a photoconductive material having a sensitivity range even in the infrared wavelength region and a method for manufacturing the same.

[Means for Solving the Problems] In order to achieve the above object, the photoconductive material of the present invention has an organic polymer containing a repeating unit represented by the following general formula (A), which has a decomposition temperature higher than that of the organic polymer. It consists of a structure in which other organic materials whose temperature is higher than the heat treatment temperature for crystallization are dispersed.

-Z-(-X-Y-) -(A) (where n≧2, X is any element of O, S, Se, Te, Y is an aromatic or substituted aromatic group, Z is an imide It is a group containing a ring.) Furthermore, in the structure of the present invention, it is preferable that the organic material is a phthalocyanine pigment.

Next, in the method of the present invention, a diamine compound represented by the following general formula (C) and an organic material are mixed in an organic solution, and then a carboxylic acid compound represented by the following general formula (B) is mixed in the mixed solution. is added to cause a condensation reaction, and the following general formula (D) is obtained.
A polymer or oligomer represented by is obtained, and then a mixed solution containing the dispersed organic material and a polymer or oligomer represented by general formula (D) is applied to a substrate surface, and then condensation polymerization is carried out. do.

0 (Co) -R-(CO)20 (B)H2N
-R2-NH2(C) E However, R1 is an aromatic or substituted aromatic group, R2 is a group containing a repeating unit represented by the following general formula (A), -Z-(-X-Y-) -( A) (where n≧2, X is any element of O, S, Se, or Te, Y is an aromatic or substituted aromatic group, and Z is a group containing an imide ring). ] In the production method of the present invention, it is preferable to perform heating crystallization after the polycondensation step.

[Function] According to the configuration of the present invention, the organic polymer represented by the general formula (A) can be heat-treated to significantly improve its crystallinity. Improved crystallinity strengthens the interaction between adjacent polymers, increasing light absorption, charge generation ability, and charge transport ability in the film.

Sensitization is possible by embedding organic molecules having a light absorption band at long wavelengths into this polymer.

The condition for the organic molecules to be dispersed is that they have a decomposition temperature equal to or higher than the above-mentioned heat treatment temperature. Further, these organic materials interact with the organic polymer of the above general formula (A) to form a charge transfer complex.

The formed charge transfer complex has two effects on photoconductivity. First, a new light absorption region appears in the intermediate wavelength region of the absorption bands specific to the polymer and the dispersed organic material. Secondly, it is possible to efficiently transfer light absorbed and generated charges in the dispersed organic material to the host polymer through this absorption band. Due to the above-described effects, a photoconductive material having a sensitivity range in a wide range including the infrared wavelength region can be obtained.

Further, as the organic material, phthalocyanine compounds, perylene pigments, etc. can be used, but it is preferable to use phthalocyanine pigments. This is because phthalocyanine pigments have a light absorption band at long wavelengths, have a high carrier generation ability, and have a high decomposition temperature of 400'C or higher.

Furthermore, according to the manufacturing method of the present invention, since the dispersed organic material is dispersed within the polymer before the polymerization step, it is possible to uniformly disperse it at the molecular level.

[Example] In the polymer containing the group having the structure of general formula (A), examples of Y: aromatic or substituted aromatic include the following. benzene, anthracene, naphthalene,
Pyrene, perylene, naphthacene, benzanthracene,
Fused polycyclic hydrocarbons and substituted derivatives thereof such as benzophenanthrene, chrysene, triphenylene, and phenanthrene; Fused polycyclic quinones and substituted derivatives thereof such as anthraquinone, dibenzopyrenequinone, anthanthrone, isoviolanthrone, and pyranthrone; metal-free phthalocyanine;
Metal phthalocyanines containing metals such as copper, lead, nickel, and aluminum, indigo, thioindigo, etc., and derivatives thereof. Here, the group represented by the general formula (A) may be present in the main chain or in the side chain of the polymer.

A1 to All below are examples of polyimide. A
1 to 5, the acid component of the polyimide is pyromellitic acid, and in the general formula (A), (XXY) is A of (S, benzene ring)
1, A2 of (Sa, benzene ring), A3 of (S, naphthalene ring), A4 of (S, anthracene ring), and A5 of (S, perylene ring). Next, A6 to 11 are (XXY)
Or (S.

Benzene ring) 3.3', 4.4'-benzophenonetetracarboxylic dianhydride A 6.3.3', 4.4'-biphenyltetracarboxylic acid component of polyimide with n=2 fixed Acid dianhydride A7.1. i'
, 5.5'-biphenyltetracarboxylic dianhydride A8, naphthalene-1,4,5,8-tetracarboxylic dianhydride A9, naphthalene-2,3,6,7-tetracarboxylic dianhydride AIO, perylene-3,4,9,
All of 10-tetracarphonic dianhydride. A1
2 is (X, Y) or (S, 2.5-
This is the case for dichlorobenzene).

OO A5:Ar= OO O.

o O A typical example of the method for producing these polyimides is the general formula (B
) is a method in which various tetracarboxylic dianhydrides as acid components are reacted with a diamine compound represented by general formula (C) in an organic polar solution. The reaction involves ring-opening polyaddition to form a polyamic acid, followed by dehydration and ring-closing to form a polyimide. Here, the dehydration ring closure may be carried out by any of 1) a reprecipitation method, 2) a chemical ring closure method, and 3) a solution thermal ring closure method.

The heat treatment for crystallizing the organic polymer in this example is carried out at a temperature below the melting point of the organic polymer. The heating atmosphere may be any gas such as oxygen, nitrogen, or argon. Alternatively, it may be carried out under reduced pressure. The heating time depends on the crystallization rate at the heating temperature, but in the case of the polymer of the present invention, it is 0.25 to 3
It is within the range of 0 hours.

An example of an organic material dispersed in the polymer of general formula (A) is a phthalocyanine compound (hereinafter abbreviated as Pc). For example, metal-free phthalocyanine, XPc (X=Cu, Ni
, Co, Tie, Mg, 5i(OH), etc.) AIC
IPcCl, Ti0C1PcC1, InClPcC1,
Examples include InClPc and InBrPcBr. All of these have decomposition temperatures of 400'C or higher. Compounds having a perylene skeleton are also effective.

The amount of dispersion is 0.01 to 20% for the polymer of general formula (A).
% by weight is preferred.

The photoconductor of this example shown in FIG. 1 consists of a support 1 and a photoconductive layer 2 containing the organic polymer of the present invention, and this photoconductive layer 2 has a free surface 3.

The photoconductor of this example shown in FIG. 2 is composed of a photoconductive layer 12 containing the organic polymer of the present invention and other layers 13 (for example, an insulating layer, a carrier transport layer) on a support 11. and has a free surface 14 on the one hand. layer 12 and layer 13
The order may be reversed. By the way, although the configuration shown in FIG. 2 is the same as that of a laminated type photoreceptor, the photoconductive material of the present invention provides good characteristics even in this configuration.

The thickness of the photoconductive layer is 1 to 50 μm, preferably 5 to 30 μm.
Let it be m. Among the organic polymers containing the group represented by the general formula (A), the photoconductive layer for electrophotographic photoreceptors with good printing durability includes:
Its Vickers hardness is 10 or more, preferably 30.
That's all. A film with good crystallinity has high optical carrier generation efficiency and high carrier transport ability. When looking at crystallinity using an X-ray diffraction intensity curve, the interplanar spacing between adjacent polymers is 3 to IO.
A (A is angstrom) characteristic diffraction scattering peak is desirable. Furthermore, when the crystallinity is evaluated by the half width of each scattering peak, it is 5 degrees or less, preferably 2 degrees or less. At this time, the crystal thickness evaluated from the following 5hetet formula is IOA or more, preferably 25A or more.

d = 0.9 It is 10% or more, preferably 30% or more, in the evaluation expressed by the ratio of the contribution of scattering to the total scattering and the evaluation by density.

Absorption wave number derived from stretching vibration of imide ring carbonyl group seen in infrared absorption spectrum of the polymer of the present invention ~ 1725c
m, ~1720 cm-', the imidization rate defined by the absorption coefficient ratio to the absorption wave number ~1500 cm-1 derived from the vibration of the benzene ring is 50% or more, preferably 80
% or more.

In the photoconductor of the present invention, a barrier layer may be provided between the support and the photoconductive layer in order to effectively prevent carriers from injecting into the photoconductive layer from the support.

For example, materials for forming the barrier layer include Al2O, B
aO, BaOXBed, Bi2O3, CaO1CeO2
, Ce2O3, La2o3, Dy2O3, LuO, C
r2O3, CuO1Cu20, FeO, PbOlMgO
,5rO1TaO,ThO1ZrO2,HfO2,T
i02 , Tie, S i02 , GeO2, S jO
.

Metal oxides such as GeO or TiN, AIN X5
nN.

Metal nitrides such as NbN, TaN, GaN, or metal carbides such as WClSnC, TiC, or SiC
, SiN XGeC.

Insulators such as GeN, BC, and BN, and heat-resistant organic compounds such as polyimide, polyamideimide, and polyacrylonitrile are used.

Furthermore, a surface coating layer may be formed on the free surface in FIG. For example, suitable materials for the surface coating layer include Si ○ , 5iXC1-1, 1-X Si N X Ge O, Ge
C, Gx l-x X l-X
X 1-XeX N1-X-Bx N1-X-Bx
C1-X □A I N (0<!<1), carbon, and inorganic substances such as layers containing 1-x hydrogen or halogen.

Example 1 To synthesize an organic polymer of general formula (A), general formula (B
) There are four types of polymerization degrees (n
=2.3.4) paraphenylene sulfide diamine (
Hereinafter, abbreviated as PSDA-n), pyromellitic anhydride (abbreviated as PSDA-n) is used as the carbonic acid compound represented by general formula (C).
Two types were used: 3.3.4.4-benzophenonetetracarboxylic dianhydride (hereinafter referred to as BPDA).

Metal-free phthalocyanine (N2
Pc) and copper phthalocyanine (CuPc) were mixed at 0.01 to 10% by weight.

To synthesize the dispersed polyimide, PSDA-n and a phthalocyanine compound at a predetermined weight ratio are added in advance to a solution of dimethylacetamide. PMDA or BPD in this mixed solution
Add A and stir for approximately 1 hour. A film of 5 to 20 μm is coated on a metal substrate (aluminum) using a dipping method with the polymerized polyamic acid solution. 3 at approximately 100'C
After drying for 0 minutes and removing the solution, imidization reaction and crystallization are performed by heat treatment at the melting point temperature of the polymer. The heating time was kept constant for 2 hours.

Photoconductivity was evaluated as a sensitivity characteristic of electrophotography. Using a charging exposure tester manufactured by Kawaguchi Electric Co., Ltd., the charging voltage was set to 6KV and the initial surface potential was set to +600■, and the irradiation amount of white light from a halogen lamp was 600 lux, through an optical filter.
It is applied as monochromatic light in the range of 00 to 900 nm. It is expressed as the amount of monochromatic light exposure (hereinafter referred to as E (μJ/cm2)) required to halve this surface potential (+300V).

1/2 Shows the spectral sensitivity characteristics of the half-decreased exposure amount E1/2 depending on the difference in the polymer matrix when the metal-free phthalocyanine is kept constant at 5% by weight. FIG. 3 shows the results for PMDA-2, 3°4, and FIG. 4 shows the results for BPDA-2, 3, 4. In either case, 90 nm for wavelengths below 600 nm in the sensitivity range of the host polymer
This shows that the sensitivity region extends to long wavelengths up to 0 nm. Among them, BPDA-2 has good sensitivity in the range of 400 to 850 nm, <1 μJ/cm.

A film of 15 μm of the metal-free phthalocyanine dispersed BPDA-2 was formed on the surface of a drum-shaped aluminum substrate, and the film was mounted on a copying machine and a racer printer for image evaluation.

In a copy machine, for white exposure ~l 1uxSec
It has a sensitivity of 100,000, and gave good results even after outputting 100,000 A4 size images. On the other hand, laser printers have an additional 20
Good images were obtained even after printing 10,000 sheets.

Sensitivity changes with respect to the amount of dispersion were evaluated in polymer BPDA-2. The results are shown in Figure 5.) In the case of both metal-free and copper phthalocyanine compounds, the minimum value is around 5% by weight7.Dispersion of more than 5% by weight inhibits the crystallization of polymers The phthalocyanine compounds may act as traps for carrier transport, resulting in decreased sensitivity.

Example 2 Gold-free phthalocyanine dispersed BPDA in Example 1
The following procedure was used to synthesize and form a film.

A polyamic acid precursor of the base polymer BPDA-2 is synthesized without adding a dispersion material. Next, a prescribed amount (5% by weight)
) of metal-free phthalocyanine is added to the boriamic acid and mixed. A polymer film is formed from this mixed polyamic acid.

FIG. 6 shows the change in sensitivity of the polymer membrane with respect to mixing time.

The irradiation wavelength was 800 nm. After 20 hours of mixing, only 1/3 of the sensitivity is achieved for the mixing method of Example 1.

Example 3 After forming a 1 μm film of metal-free phthalocyanine-dispersed BPDA-2 of Example 1 on the substrate surface, 15 μm of non-dispersed BPDA-2 was deposited on the substrate surface.
m layers were laminated to form a laminated photoreceptor having negative charging characteristics. It has good sensitivity of E I/2 < 2 μJ/cm2 in the wavelength range of 650 to 850 nm with respect to a surface potential of -600V.

The dispersed organic polymer of this example could be made into a photoconductive material having good photosensitivity in a wide wavelength range from visible wavelengths to long wavelengths of infrared light.

This material can be applied to both electrophotographic copying machines that use white light as a light source and printers that use infrared wavelength lasers as light sources. It also brings about a significant improvement in printing durability.

[Effects of the Invention] As explained above, according to the present invention, an organic polymer containing a repeating unit represented by the general formula (A) has a decomposition temperature equal to or higher than the heat treatment temperature for crystallizing the organic polymer. By dispersing other organic materials, a photoconductive material with good photosensitivity over a wide range of wavelengths from visible wavelengths to long infrared wavelengths could be obtained.

Further, by using a phthalocyanine pigment as the organic material, it is possible to obtain a material having a high carrier generation ability and a high decomposition temperature.

Furthermore, according to the manufacturing method of the present invention, the dispersed organic material is dispersed within the polymer before the polymerization step, so that it can be uniformly dispersed at the molecular level.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view of a photoconductor in an example of the present invention, FIG. 2 is a schematic vertical cross-sectional view of another photoconductor in this example, and FIG. A spectral sensitivity characteristic diagram, FIG. 4 is a spectral sensitivity characteristic diagram of another photoconductive material of Example 1, and FIG. 5 is a spectral sensitivity characteristic diagram for the amount of dispersion of Example 1.
FIG. 6 is a diagram showing changes in electrophotographic sensitivity characteristics with respect to mixing time of the photoconductive material of Example 2. DESCRIPTION OF SYMBOLS 1...Support, 2...Photoconductive layer, 3...Free surface,
DESCRIPTION OF SYMBOLS 11...Support, 12...Photoconductive layer, 13...Other layers (eg, insulating layer, carrier transport layer), 14...
free surface. Name of agent: Patent attorney Hiroyuki Ikeuchi Haka 1 person 11...
Support 12: Photoconductive layer (Figure 2) Dispersion amount (% by weight) Figure 5. Figure Time (h')

Claims (3)

[Claims] (1) A photoconductive material in which another organic material having a decomposition temperature equal to or higher than the heat treatment temperature for crystallization of the organic polymer is dispersed in an organic polymer containing a repeating unit represented by the following general formula (A). -Z-(-X-Y-)_n-(A) (where n≧2, X is any element of O, S, Se, Te, Y is an aromatic or substituted aromatic group, Z is (It is a group containing an imide ring.) (2) Claim 1 wherein the organic material is a phthalocyanine pigment.
Photoconductive materials as described. (3) a diamine compound represented by the following general formula (C);
An organic material is mixed in an organic solution, and then a carboxylic acid compound represented by the following general formula (B) is added to the mixed solution to cause a condensation reaction, thereby producing a polymer or oligomer represented by the following general formula (D). and then applying a mixed solution containing the dispersed organic material and a polymer or oligomer represented by the general formula (D) to the substrate surface, followed by condensation polymerization. Method. O(CO)_2-R_1-(CO)_2O(B) H_2N-R_2-NH_2(C) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(D) [However, R_1 is an aromatic or substituted aromatic group, R_
2 is a group containing a repeating unit represented by the following general formula (A), -Z-(-X-Y-)_n-(A) (however, n≧2, X is any of O, S, Se, Te) (Y is an aromatic or substituted aromatic group, and Z is a group containing an imide ring). ]