CN1312491A - Photoelectric conductor for electronic photography - Google Patents

Abstract

An electrophotographic photoconductor exhibits reduced residual potential after charging and exposure to light, and therefore facilitates high quality imaging. It has a conductive substrate and a photosensitive layer on the substrate. The photosensitive layer contains a compound represented by the formula (I), each of R1 and R2 is independently selected from the group consisting of an optionally substituted aromatic hydrocarbon group, an optionally substituted aliphatic hydrocarbon group, a polycyclic aromatic ring represented by formula (Ia), and a heterocyclic ring represented by formula (Ia), wherein Y represents a residual group to form said polycyclic aromatic ring or said heterocyclic ring, and said substituent being selected from the group consisting of a hydroxyl group, a cyano group, a nitro group and a halogen atom, wherein X is selected from the group consisting of a single bond, O, CO, and COO.

Description

Photoelectric conductor for electronic photography

The present invention relates to be used for the photoelectric conductor for electronic photography (also abbreviating photoconductor as) of electro-photography apparatus (as printer and duplicating machine).Be specifically related to improve as the material component of the photosensitive layer of key component to containing organic material.

The basic structure of photoconductor is by conductive substrate and have that photosensitization is superimposed to be formed at on-chip photosensitive layer.In recent years, the dirigibility of selecting for material, high conductance and the consideration on the safety, active research is used the organic photoconductor of organic substance as the function ingredients that produces electric charge and transfer charge with having developed, and this photoconductor has been used for copy and printer.

Require photoconductor to have and keep surface charge in the dark, be subjected to produce the function that electric charge also shifts the electric charge that produces behind the light.Known photoconductor comprises and collects the so-called single-layer type photoconductor of these functions in one deck photosensitive layer, and has and mainly be subjected to light to produce the charge generation layer of electric charge and be used for keeping surface charge in the dark and be subjected to light to shift the called function independence lamination-type photoconductor of the charge transfer layer of the electric charge that produces.

Recently, what mainly adopt is this function independence lamination-type photoconductor, it comprises the photosensitive layer that charge generation layer and charge transfer layer are formed by stacking, described charge generation layer is to contain dissolving and be dispersed in the charge generating material of the organic pigment in the organic solvent and adhesive resin forms is coated with feed liquid and applies and form, and described charge transfer layer is that the feed liquid that is coated with that contains dissolving and be dispersed in that organic low molecular in the organic solvent quantizes that the charge transport material of compound and adhesive resin form applies and forms.

But the organic photoconductor that uses can not make photoconductor have all required features at present.Specifically, the photoconduction cognition that has the high residue current potential behind charged and photoirradiation descends image quality, thus the problem that causes duplicating machine or printer level and resolution to descend.

It is believed that to produce residual electric potential mechanism as follows: when making photoconductor charged and when making it be subjected to photoirradiation, the electric charge of photoconductor surface reduces and the electric field of thickness direction descends, and this means that charge transport capability descends.Therefore electric charge accumulates on the interface between charge generation layer and the charge transfer layer and accumulates in the charge transfer layer, thereby can not thoroughly eliminate surface charge.Therefore, be retained in charge generation residual electric potential on the photoconductor surface.

Therefore the purpose of this invention is to provide a kind of photoconductor, it has low residual electric potential and can prevent that image quality from descending, thereby produces good image.

Solve the problems referred to above at above-mentioned mechanism the present inventor through big quantity research, discovery exists special electrophilic compound can eliminate between charge generation layer and the charge transfer layer on the interface and the residual electric potential in charge transfer layer on the charge transfer layer, thereby reduces residual electric potential.The present invention finishes on the basis of this discovery.

The photoconductor of the present invention that addresses the above problem comprises conductive substrate and the photosensitive layer on this conductive substrate, and described photosensitive layer comprises the compound of following formula (I) expression: Wherein, each R ¹And R ²Expression randomly has substituent aromatic hydrocarbyl, randomly has a substituent aliphatic hydrocarbyl or with formula (many cyclophanes ring that I a) is represented or also use the formula (heterocycle that I a) is represented separately, described substituting group is selected from hydroxyl, cyano group, nitro, halogen atom, and X represents singly-bound, O, CO or COO in the formula (I).Formula (I a) in Y represent to be used to form the residue of many cyclophanes ring or heterocycle.

Be preferably, photoconductor of the present invention comprises and contains the superimposed successively charge generation layer and the photosensitive layer of charge transfer layer that described charge transfer layer contains the compound of formula (I) expression.

Be preferably, the carbon number of described aliphatic hydrocarbyl is 1-10.

Below with reference to instantiation explanation the present invention.

Fig. 1 is the sectional view of an example of photoconductor basic structure of the present invention.

Fig. 1 photoconductor is an independently lamination-type photoconductor of a kind of electronegative function, and it comprises conductive substrate 1, undercoat 2, the photosensitive layer of being made up of superimposed successively charge generation layer 4 and charge transfer layer 53.Although the example with reference to the lamination-type photoconductor describes the present invention, the invention is not restricted to the description of this example.

Conductive substrate 1 is as the electrode of photoconductor, and also conduct constitutes the supporting mass of other layer of photoconductor.That substrate 1 can have is cylindrical, the shape of planar shaped or film shape, and can make so that have the glass or the resin of suitable electric conductivity by metal or alloy (as aluminium, stainless steel or nickel) or through surface treatment.

Can form the undercoat of making as the layer of key component or sull (as alumite) by resin 2 as required, inject the electric charge of photosensitive layer with control by conductive substrate, cover the surface imperfection of substrate and improve photosensitive layer and substrate between cohesive.Optional as the resin material of undercoat from insulating polymkeric substance, as casein, polyvinyl alcohol (PVA), polyamide, melamine, cellulose, and conducting polymer, as polythiophene, polypyrrole or polyaniline, and be fit to and these polymer mixed material together.Undercoat also can contain metal oxide, as titania or zinc paste.

The charge generation layer 4 that is used to be subjected to light to produce electric charge is the organic photoconductive materials that deposit in a vacuum as charge generating material, and the powder that perhaps applies charge generating material is dispersed in the feed liquid that is coated with that forms in the resin binder and makes.Require charge generation layer to produce electric charge efficiently and have good ability the electric charge iunjected charge transfer layer 5 that produces.That is to say, require the injection of electric charge and electric field irrelevant, even and also can inject charge under low electric field.The phthalocyanine compound of the optional free style of charge generating material (II-1)-(II-6) expression, by the azo-compound of formula (II-7)-(II-24) expression, by anthanthrone (anthanthron) compound of formula (II-25)-(II-32) expression and the derivant of these compounds.The optional autopolyester resin of resin binder, polyvinyl acetate, polyacrylate, polymethacrylate, polycarbonate, polyvinyl alcohol (PVA) acetyl group acetal, the polyvinyl alcohol (PVA) that is used for charge generation layer contract propionic aldehyde (propional), polyvinyl butyral, phenoxy resin, epoxy resin, urethane resin, cellulose esters, cellulose ether and these material suitable mixture.

Charge generating material is per 10 parts by weight resin bonding agent 5-500 weight portions with respect to the content of resin-bonding dosage in charge generation layer, better the 10-100 weight portion.The film thickness of charge generation layer depends on the absorptivity of charge generating material, generally is controlled to be no more than 5 microns, better is no more than 1 micron.

Charge transfer layer 5 comprises the compound of charge transport material, resin binder and general formula of the present invention (I) expression.Object lesson by the compound of formula (I) expression is represented by formula (I-1)-(I-26):

Charge transport material can be selected from any suitable mixture of hydrazone compound, adiene cpd, diamine compound, benzazolyl compounds, dihydroindole compounds, stilbene compounds, two Stilbene (distilbene) compound and these compounds.The object lesson of these charge transport materials can be referring to formula (III-1)-(III-12).Any suitable mixture that is used for the optional self-polycarbonate resin of adhesive resin (as bisphenol A-type, bisphenol Z type or bisphenol-A-biphenyl (bisphenyl) multipolymer), polystyrene resin, polyphenylene resin and these materials of charge transfer layer.The object lesson of these adhesive resins can be referring to formula (IV-1)-(IV-7).The content of the relative adhesive resin amount of charge transport material is per 100 parts by weight resin bonding agent 2-80 weight portions in the charge transfer layer, is preferably the 3-70 weight portion.The thickness of charge transfer layer is preferably the 3-50 micron, and 15-40 micron more preferably is to keep actual effectively surface potential.

When according to the present invention the compound of formula (I) being added charge transfer layer, the content of this compound is controlled at the charge transport material 0.1-10 weight portion of per 100 weight portions usually, is preferably the 0.2-1.0 weight portion.Under the situation of the single-layer type photoconductor that photosensitive layer is made up of simple layer, the content of formula (I) compound is controlled at by photosensitive layer solid total content 1-50 weight %, is preferably 5-20 weight %.

Undercoat 2 or charge transfer layer 5 also can contain adjuvant, as are used to improve the chemical stability of stability against atmospheric influence and the antioxidant and the UV absorbers of the stability that anti-light endangers.The object lesson of this adjuvant can be referring to formula (V-1)-(V-45).When adjuvant is added charge transfer layer, be the 0.01-10 weight portion by 100 its content of weight portion charge transport material, be preferably the 0.01-0.5 weight portion.

Photosensitive layer also can contain silicone oil or fluorocarbon oil, to improve the planarization or the lubricity of the film that forms.

In addition, can form sealer (among Fig. 1 show) as required with the chemical stability of improving anti-environmental gas and improve physical strength.Sealer is to be made by the material of the permanance with chemical stability and anti-mechanical stress, and requires the light experienced with least disadvantage transmission charge generation layer.

Photosensitive layer need contain compound and the charge generating material and the charge transport material of general formula (I) expression in the single-layer type photoconductor of the present invention.But, can the mode similar suitably select other material and the structure of each layer of single-layer type photoconductor for use to above-mentioned lamination-type photoconductor.

Embodiment

With reference to embodiments of the invention the present invention is described in more detail below.

Embodiment 1

Make organic photoconductor to estimate the electrofax characteristic.

At first, the dipping by being coated with feed liquid and 100 ℃ of dryings 30 minutes forms thick about 3 microns undercoat on as the cylindrical outside surface of the aluminium of conductive substrate.Be used for undercoat be coated with feed liquid be with 5 weight portion alcohol soluble nylons (CM 8000, available from Toray Industries Co., Ltd) and 5 weight portions through the dissolving of the titania particulate of aminosilane-treated be dispersed in and make in the 90 weight portion methyl alcohol.

Be coated with feed liquid and on this undercoat, formed thick about 0.3 micron charge generation layer in 30 minutes by dipping 80 ℃ of dryings.The feed liquid that is coated with as charge generation layer is metal-free phthalocyanine (charge generating material) and 1.5 weight account polyethylene butyral resin (S-LEC KS-1 with 1 weight portion formula (II-1), Sekisui ChemicalCo., Ltd system) (resin binder) dissolves and is dispersed in and make in the 60 weight portion methylene chloride.

Be coated with feed liquid and on charge generation layer, formed thick about 17 microns charge transfer layer in 60 minutes by coating 90 ℃ of dryings.The feed liquid that is coated with that is used for charge transfer layer is the carboxylate of the polycarbonate resin (resin binder) of the stilbene compounds (charge transport material) of 80 weight portion formulas (III-11) expressions, 120 weight portion formulas (VI) and 0.5 weight portion formula (I-1) and antioxidant that an amount of formula (V-32) is represented to be dissolved in 600 weight portion methylene chloride make.

Embodiment 2

Make organic photoconductor with the method identical, but in embodiment 2, replace the compound (I-1) that uses among the embodiment 1 with compound (I-2) with embodiment 1.

Embodiment 3

Make organic photoconductor with the method identical, but in embodiment 3, replace the compound (I-1) that uses among the embodiment 1 with compound (I-4) with embodiment 1.

Embodiment 4

Make organic photoconductor with the method identical, but in embodiment 4, replace the compound (I-1) that uses among the embodiment 1 with compound (I-6) with embodiment 1.

Embodiment 5

Make organic photoconductor with the method identical, but in embodiment 5, replace the compound (I-1) that uses among the embodiment 1 with compound (I-7) with embodiment 1.

Embodiment 6

Make organic photoconductor with the method identical, but in embodiment 6, replace the compound (I-1) that uses among the embodiment 1 with compound (I-8) with embodiment 1.

Implementation column 7

Make organic photoconductor with the method identical, but in embodiment 7, replace the charge transport material that uses among the embodiment 1 with the diamine compound of formula (III-8) with embodiment 1.

Embodiment 8

Make organic photoconductor with the method identical, but in embodiment 8, replace the compound (I-1) that uses among the embodiment 7 with compound (I-2) with embodiment 7.

Embodiment 9

Make organic photoconductor with the method identical, but in embodiment 9, replace the compound (I-1) that uses among the embodiment 7 with compound (I-4) with embodiment 7.

Embodiment 10

Make organic photoconductor with the method identical, but in embodiment 10, replace the compound (I-1) that uses among the embodiment 7 with compound (I-6) with embodiment 7.

Embodiment 11

Make organic photoconductor with the method identical, but in embodiment 11, replace the compound (I-1) that uses among the embodiment 7 with compound (I-7) with embodiment 7.

Embodiment 12

Make organic photoconductor with the method identical, but in embodiment 12, replace the compound (I-1) that uses among the embodiment 7 with compound (I-8) with embodiment 7.

Comparative example 1

Make organic photoconductor with the method identical, but in comparative example 1, do not use the compound (I-1) that uses among the embodiment 1 with embodiment 1.

Comparative example 2

Make organic photoconductor with the method identical, but in comparative example 2, do not use the compound (I-1) that uses among the embodiment 7 with embodiment 7.

The evaluation of photoconductor

Estimate the electrofax characteristic of each embodiment and comparative example sample with following method.

In the rotation photoelectric conducting drum, make its charged extremely-650V in the dark.At the charged and back 5 seconds mensuration electric charge conservation rate V that stop the rotation _K5Then, this drum of Continuous irradiation surface and measure surface potential by-600V reduce to-the 300V process in the luminous energy of irradiation, be designated as sensitivity E _1/2, and with surface potential by-600V reduce to-the 100V process in the luminous energy of irradiation be designated as sensitivity E ₁₀₀Simultaneously, measuring the exposure light energy is 2.5 μ J/cm ²The time surface potential, as rest potential V _R2.5Measurement result is listed in table 1.

Table 1

Sample	Conservation rate V after 5 seconds k5(％)	Sensitivity E 1/2(μJ/cm 2)	Sensitivity E 100????μJ/cm 2	Residual electric potential V r2.5????(-V)
					Embodiment 1	????93	????0.20	????0.62	????30
Embodiment 2	????94	????0.19	????0.63	????33
					Embodiment 3	????93	????0.20	????0.62	????34
Embodiment 4	????94	????0.20	????0.63	????34
					Embodiment 5	????93	????0.21	????0.63	????33
Embodiment 6	????93	????0.20	????0.64	????33
					Comparative example 1	????94	????0.20	????0.62	????40
Embodiment 7	????94	????0.26	????0.74	????40
					Embodiment 8	????94	????0.25	????0.75	????42
Embodiment 9	????93	????0.24	????0.76	????43
					Embodiment 10	????94	????0.25	????0.75	????41
Embodiment 11	????93	????0.25	????0.75	????41
					Embodiment 12	????93	????0.26	????0.75	????43
Comparative example 2	????94	????0.25	????0.75	????46

By table 1 as seen, compare with the comparative example 1 that does not contain general formula (I) compound, the present invention contains general formula (I) compound in charge transfer layer embodiment 1-6 has reduced residual electric potential effectively.Equally, compare with the comparative example 2 that does not contain formula (I) compound, the embodiment 7-12 that the present invention contains this compound has reduced residual electric potential.

The foregoing description has exemplified the photoconductor that uses phthalocyanine compound and be used for laser printer.Except the photoconductor of the above-mentioned type, confirm also that after formula (I) compound is added to charge transfer layer the residual electric potential that is used for the photoconductor of the photoconductor of photoconductor, digital duplicating machine of similar duplicating machine and facsimile recorder is also descended effectively.

As mentioned above, the invention provides a kind of organic photoconductor, it can reduce residual electric potential effectively, thereby obtains good image quality.

Claims (2)

1. photoelectric conductor for electronic photography, it comprises: conductive substrate; With the photosensitive layer on this conductive substrate, described photosensitive layer comprises the compound of following formula (I) expression: Wherein, each R ¹And R ²Be selected from separately randomly have substituent aromatic hydrocarbyl, randomly have substituent aliphatic hydrocarbyl, with formula (many cyclophanes ring that I a) is represented and with the formula (heterocyclic group that I a) is represented, formula (I a) in Y represent to be used to form the residue of many cyclophanes ring or heterocycle, described substituting group is selected from hydroxyl, cyano group, nitro and halogen atom

X is selected from singly-bound, O, CO or COO in the formula (I),

2. photoelectric conductor for electronic photography as claimed in claim 1, it is characterized in that described photosensitive layer comprises superimposed charge generation layer on described conductive substrate, and superimposed charge transfer layer on described charge generation layer, described charge transfer layer contains the compound of formula (I) expression.