JPS63280255A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body which has high sensitivity, is less degraded in definition and has a long printing resistance life by incorporating a specific thiazole deriv. into an electric charge transfer material. CONSTITUTION:The charge transfer material of the electrophotographic sensitive body provided with a layer contg. the charge transfer material and charge generating material on a conductive base contains the thiazole deriv. expressed by the formula I. In the formula I, R1-R3 denote a hydrogen atom, alkyl group, etc. Since this thiazole deriv. has substantially no absorption to light of >=500nm wavelength, the charge generating material, i.e., the material which generates an electric charge by reacting sensitively with light is used together. The electrophotographic sensitive body having excellent electrophotographic characteristics and printing resistance life is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electrophotographic photoreceptor having excellent electrophotographic properties.

(Prior Art) In an electrophotographic photoreceptor that uses a photoconductive substance as a photosensitive material, conventional photoconductive substances are used as photoconductive substances.

Inorganic photoconductive materials such as selenium, zinc oxide, titanium oxide, and cadmium sulfide have been mainly used.

However, many of these are generally highly toxic and there are problems in how to dispose of them.

On the other hand, the use of organic photoconductive compounds is generally less toxic than the use of inorganic photoconductive substances, and is also advantageous in terms of transparency, flexibility, light weight, and price. It has been widely studied recently.

(Problems to be Solved by the Invention) However, in some respects, this method is inferior to the case where an inorganic photoconductive material is used. One reason is that the sensitivity is low, and the second is that the printing life is short. In particular, if you use it repeatedly, the resolution will gradually decrease (see below)
The problem (abbreviated simply as "low resolution") is a major hindrance that shortens printing life. These problems are extremely dependent on charge transport materials, and many new charge transport materials are being investigated to solve these problems. Among them, oxazole derivatives (Japanese Patent Publication No. 60-8500) are charge transport substances with unprecedented high sensitivity, but it has been found that they have a problem in that resolution tends to decrease.

(Means for Solving the Problems) The present inventors therefore investigated the development of a charge transport material that does not reduce resolution while maintaining high sensitivity.

We have discovered the following new charge transport material. The present invention provides a novel electrophotographic photoreceptor using the same, which is highly sensitive, has little reduction in resolution, and has a long printing life.

That is, the present invention provides an electrophotographic photoreceptor in which a layer containing a charge transporting substance and a charge generating substance is provided on a conductive support, in which the charge transporting substance has the following general formula (1) [wherein R1,
Rs and R3 are each independently a hydrogen atom.

halogen atom, hydroxyl group, alkyl group, substituted or unsubstituted amino group, substituted or unsubstituted aryl group, substituted or unsubstituted aralkyl group, or substituted or unsubstituted heterocyclic group]. An electrophotographic photoreceptor comprising:

Although the details of the reason why the thiazole derivative represented by the general formula (1) is a charge transport material with high sensitivity and resistant to decrease in resolution are unknown, the resonance stability of the heterocycle is greater than that of oxazole. The sensitivity is equal to or higher than that of oxazole, and the stability against oxidation of the ring is superior to that of oxazole (Large Organic Chemistry + Vol. 15).
．． P 83 * Asakura Shoten 1960) It is thought that the fact that ozone does not deteriorate easily is one of the reasons why resolution does not deteriorate easily.

The thiazole derivative represented by the above general formula (1) will be explained in detail. In general formula (1), the alkyl group in R1, R1, and R3 is a methyl group or an ethyl group.

n-propyl group * 150-propyl group t n-butyl group, n-mil group, etc. are suitable, and substituted amino groups include dimethylamino group, diethylamino group, dipropylamino group, diphenylamino group, dibenzylamino group, etc. Examples of the group include phenyl group, biphenyl group,
Naphthyl group, anthryl group.

There are phenanthryl groups, etc., and aralkyl groups include benzyl groups, phenethyl groups, naphthylmethyl groups, etc.
Examples of the heterocyclic group include furyl group, thio7lyl group, pyrrolyl group, pyranyl group, and pyridyl group.

Oxacylyl group, thiazolyl group, pyrimidinyl group.

Examples include triazolyl group, acridinyl group, carbazolyl group, carboryl group, quinolyl group, fetchedyl group, and quinoxalyl group. Among these, the aryl group, aralkyl group, and heterocyclic group may be used as they are, or may be halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom, methyl group, ethyl group, n-propyl group*1so- Alkyl groups such as propyl group, n-butyl group, n-amyl group, alkoxy groups such as methoxy group, ethoxy group, butoxy group, amino group, dimethylamino group.

One or more di-substituted amino groups such as diethylamino, dipropylamino, diphenylamino, and dibenzylamino groups may be substituted.

Representative examples of the thiazole derivative represented by the general formula (1) used in the charge transport material of the present invention are illustrated below.

CH3 ■ (Charge transport substance represented by general formula (I) (1) to (5)
2) can be obtained, for example, by condensing a thioamide compound and an α-halogen ketone as shown in the following reaction formula (1) (References: R, H, Wiley,
D.

C, England L, C, Behr “Organ
ic React -1ons”voI!6.P,
367”t~1951)).

In addition, a charge transport substance represented by the general formula (1) (29
) to (52), that is, bithiazolyl derivatives.

For example, ① directly link two thiazole nuclei.

■Condense bisthioamide and halogen ketone.

■Condense bishalogen ketone and thioamide.

(2) It can be obtained by any synthetic method such as condensation of a thiazole derivative having a thioamide group or a halogen ketone group with a halogen ketone or a thioamide.

An example is the case of 22'-bithiazolyl derivatives.

As shown in reaction formula (2), a 2-bromothiazole derivative can be obtained by heating copper powder in p-cumene.

In addition, one reaction formula (as shown in 31, dithiooxamide and α
- Can also be obtained by condensation of halogen ketones.

4.9 reaction formula (3
), it can be obtained by condensation of α,a-dibromoβ,r-diketone and thioamide.

In the case of Mr. 5'-bithiazolyl derivative, 9 reaction formula (4)
As shown in , it can be obtained by condensation of a thiazole having a halogen ketone group and a thioamide.

Bithiazolyl derivatives include 4'-bithiazolyl, 25'-bithiazolyl, and 45'-bithiazolyl derivatives in addition to the above-mentioned 22'-bithiazolyl, 4,4'-bithiazolyl, and 5,5'-bithiazolyl derivatives.

These are also synthesized in the same manner as described above.

Next, some specific examples will be described.

(1) 49o Rube7n i [:31g of chlorpenzoyy1120mI! in ethyl alcohol for 20 hours.

If heated above 60°C, the product will precipitate. When this compound is filtered and recrystallized in benzene, (2) λ
Add 1.8 g of 5-sifuromhexadione-3,4t, ag and thiobenzamide to 20 ml of ethyl alcohol, add 2 drops of piperidine, and add 90 to 10 g of ethyl alcohol.
After heating at 0°C for 1 hour and cooling, the formed crystals were taken out through a suction port and recrystallized with benzene to obtain the desired λ2'-diphenyl-5.5'-dimethyl-44'-
1.69 bithiazolyl is obtained.

(3) Thoroughly stir 1,4-diphenylthyl-3-dibromobutanedione-(1,4) 5.09 obtained by brominating trans-cyhensoil ethylene in chloroform and thiourea 2011, and then stir. Heat slowly without stirring. When the temperature exceeds 110°C, the reaction begins and hydrogen bromide begins to be generated. after that.

After further increasing the temperature and heating at 150°C for 15 minutes, the mixture was added to 30 mJ of concentrated hydrochloric acid. When neutralized with aqueous sodium hydroxide solution and recrystallized in dioxane, the desired Z2'-diamino-4
, 4'-diphenyl-5,5'-bithiazo-#dilyl'Z19 is obtained.

Among thiazole derivatives represented by general formula (1).

For those excluding bithiazolyl derivatives, the general formula (
In 1), Rt, Rs and R3 are preferably each independently a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted heterocyclic group.

Among thiazole derivatives represented by general formula (1).

Regarding bithiazolyl derivatives, each thiazole ring of bithiazolyl is preferably substituted with at least one substituted or unsubstituted aryl group.

The electrophotographic photoreceptor of the present invention contains at least one thiazole derivative represented by the general formula (1) described above as a charge transport material in the photosensitive layer. In addition to the thiazole derivative represented by the general formula (1), conventionally known charge transport substances include oxazole, pyrazoline, hydrazone, stilbene, carbazole, and triphenylamine.

Charge transport substances such as low-molecular compounds such as oxadiazole and their derivatives, and high-molecular compounds such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylacridine and their derivatives are also represented by the general formula (summer). It can also be used in combination in an amount of 100 parts by weight or less per 100 parts by weight of the thiazole derivative. If it exceeds 100 parts by weight, sensitivity decreases.

The thiazole derivative represented by the general formula (1) according to the present invention has almost no absorption for light with a wavelength of 5 Q nm or more. The generated substances are used together to form an electrophotographic photoreceptor.

Substances that generate charges include azoxybenzene, bisazo, trisazo, benzimidazole, polycyclic quinoline, and indigoid.

Pigments known to generate electric charge upon irradiation with light, such as quinacridone-based, phthalocyanine-based, naphthalocyanine-based, perylene-based, and methine-based pigments, can be used. These pigments may be
7-37544, JP-A-47-18543 1% JP-A-47-18544, JP-A-48-43942 1% JP-A-48-70538 9% JP-A-49-1231 9% JP-A-49- No. 105536 2% Kaisho 50-75214 e
Il! f is disclosed in Japanese Patent Publication No. 50-92738. In particular, τ, τ/, ? described in Japanese Patent Application Laid-Open No. 58-182640 and European Patent Application Publication No. 92,255. and -qI type gold metal phthalocyanine It has high sensitivity up to long wavelengths and is useful as a material for printers equipped with diode lasers. There is no particular restriction as long as it is an organic compound that has the function of generating a stain carrier upon irradiation with light.

The above-described charge-generating substance may be contained in the same layer as the charge-transporting substance of the present invention in a single-layer photosensitive layer, or! A two-layer laminated structure in which a layer containing a charge-generating substance (charge-generating layer) and a layer containing a charge-transporting substance (charge-transporting layer) are separated may be used. When the photosensitive layer is opaque, the charge transporting material is preferably contained in an amount of 50 to 1000 parts by weight per 10 parts by weight of the charge generating material. In other ranges, the electrophotographic properties deteriorate. In the case of a two-layer type, it is also possible to contain a charge transport substance in the charge generation layer and a charge generation substance in the charge transport layer in a range of 30 times -is or less.

Furthermore, the order in which the charge generation layer and charge transport layer are stacked is arbitrary, whether the layer is on the top or the bottom, but in terms of the printing life of the electrophotographic photoreceptor, it is better to form the charge transport layer on top of the charge generation layer. is preferred.

Regardless of whether the photosensitive layer is a single layer or consists of two layers, a charge generation layer and a charge transport layer, each layer contains binders, plasticizers, A fluidity imparting agent, a pinhole inhibitor, etc. can be used as necessary.

Examples of the binder include silicone resin, polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polystyrene resin, acrylic resin, and methacrylic resin. Heat and/or photocurable resins can also be used. In any case, there is no particular restriction as long as the resin is electrically insulating and can form a film under normal conditions. The amount of binder to be used is, if the photosensitive layer is a layered type! 50 to 500 parts by weight per 100 parts by weight of the charge-generating substance and the charge-transporting substance.

In the case of a two-layer structure, the amount is preferably 500 parts by weight or less per 100 parts by weight of the charge generating material in the charge generating layer, and the range of 50 to 500 parts by weight per 100 parts by weight of the charge transporting material in the charge transport layer. Outside these ranges, electrophotographic properties such as chargeability and sensitivity tend to become unbalanced.

Examples of plasticizers include halogenated paraffin, dimethylnaphthalene, dibutyl phthalate, etc. Examples of fluidity imparting agents include Modaflow (manufactured by Monosanto Chemical Co., Ltd.) and Acronal 4F (manufactured by Bass 7), etc., and pinhole inhibitors. As for benzoin.

Examples include dimethyl phthalate. these are.

It is preferable to use it in an amount of 5% by weight or less in each layer.

On the other hand, the conductive support according to the present invention is a conductive material such as conductively treated paper or plastic film, a plastic film laminated with metal foil such as aluminum, a metal plate, or a metal drum.

The electrophotographic photoreceptor of the present invention can be obtained by forming a photosensitive layer on the above-mentioned conductive support.

When the photosensitive layer is a layered type, an X charge generating substance, a charge transporting substance,
It can be formed by uniformly dissolving or dispersing a binder and optionally an additive in a solvent such as a7tone, methyl ethyl ketone, tetrahydrone, toluene, xylene, methylene chloride, trichloroethane, etc., followed by coating and drying.

When the photosensitive layer is a two-layer structure, the charge generation layer is formed by vacuum deposition of a charge generation material, or a charge generation material and a binder.

Depending on the case, the additive may be uniformly dissolved or dispersed in the above-mentioned solvent, and then applied and dried to form the coating. The charge transport layer includes a charge transport material and a binder.

Depending on the case, the additive may be uniformly dissolved or dispersed in the above-mentioned solvent, and then applied and dried to form the coating.

Next, the thickness of each layer is 5 to 50 μm if the photosensitive layer is a layered type.
m, particularly preferably 8 to 20 μm. If the thickness is less than 5 μm, the initial sensitivity tends to be low, and if it exceeds 50 μm, the sensitivity tends to decrease. When the photosensitive layer is a two-layer structure, the charge generation layer has a thickness of 0.001 to 10 μm.

Particularly preferred is 0.2 to 5 μm. If it is less than 0.001 μm, the sensitivity tends to be low, and if it exceeds 10 μm, the residual potential tends to be high. The charge transport layer has a thickness of 5 to 50 μm.

Particularly preferred is 8 to 20 μm. If the thickness is less than 5 μm, the initial potential tends to be low, and if it exceeds 50 μm, the sensitivity tends to decrease.

The electrophotographic photoreceptor of the present invention may further have an adhesive layer, barrier layer, or subbing layer immediately above the conductive support, and may also have a protective layer on the surface of the photosensitive layer. good.

When copying or printing is performed using the electrophotographic photoreceptor of the present invention, the surface is charged in the same manner as before.

After exposure, development is performed, and the image is transferred onto a transfer material such as plain paper and fixed.

(Example) Next, the present invention will be explained based on Examples, but the present invention is not limited thereto.

The materials used in the following layers are listed below. Abbreviations are shown in parentheses.

(1)! Charge-generating organic pigment τ-type metal-free phthalocyanine (r-H2PO) (2) Charge transport substance 02-Cp-dipropylaminophenyl)-4-(p-
dimethylaminophenyl)-5-(0-chlorophenyl)-1,3-oxazole (OXZ) 02-(p-sifulobylaminophenyl)-4-ip
-dimethylamino7ale)-5-(O-chlorophenyl)-1,3-thiazole (TIA-1) (representative example of (
5)) 02-(p-dipropylaminophenyl) -4゜5-
Bis(m,p-dimethoxyphenyl)-1,3-thiazole (TIA-2) (representative example (13)')02-(
4-pyridyl)-4-(p-diethylaminophenyl)
-5-(p-methylphenyl)-1,3-thiazole (TIA-3) (Representative example (6)) 04, 4. '5.5'-tetra(p-diethylamino 7
enyl)-42'-biteazolyl (BTZ-1) (representative example (37)) o z 2'-bis(p-diethylaminophenyl)-
4,4'-hyf7 zolyl (BTZ-2) (typical example (4)
2)) 042'-bis(p-diethylaminophenyl)-5
'-Pithiazolyl (BTZ-3) (representative example (46)
) (3) Binder 0 silicone varnish: KP-255 [Shin-Etsu Chemical ■Product name] 0 Polyester resin: Pylon 200 [Toyobo ■Product name] Comparative example r -HzPC2,, Og, Silicone: r-N7 varnish 4.
0 g and Tetrahydro 7ran 949 were kneaded for 8 hours using a ball mill (3-inch pot mill manufactured by Nihon Kagaku Togyo Co., Ltd.). The obtained pigment dispersion was applied onto an aluminum plate (thickness: 0.1 mm) using an applicator and dried at 9100° C. for 15 minutes to form a charge generation layer having a thickness of about 0.5 μm.

Next, OXZ xog and 10 g of polyester resin were mixed with 200 g of tetrahydrofuran. The obtained liquid was applied onto the charge generation layer using an applicator, and heated to 90°C.
The mixture was dried for 20 minutes to form a charge transport layer with a thickness of about 10 μm.

Example 1 A charge generation layer similar to that of the comparative example was formed. TIA on top of that
-1 log and polyester resin 109 in methylene chloride 1
A solution added to a mixed solvent of 209,1,1,2-trichloroethane 609 and 50 g of tetrahydrofuran was applied using an applicator.

It was dried at 115° C. for 30 minutes to form a charge transport layer with a thickness of about 10 μm.

Example 2 An electrophotographic photoreceptor was produced in the same manner as in Example 1 except that TIA-2 was used in place of TEA-1 in Example 1.

Example 3 τ-HzPC 1.0g, TIA-35.0g, polyester resin 15g, methylene chloride 1209.1°1
．． A mixture of 609% of 2-trichloroethane and 509% of tetrahydrofuran was kneaded for 10 hours using a ball mill. The resulting dispersion was coated onto an aluminum plate using an applicator and dried at 120°C for 15 minutes to give a film thickness of 10μ.
A single-layer electrophotographic photoreceptor of m was prepared.

Example 4 T -HzPC2,,OB,'/IJ:! -7”
) Near, 4. OB and tetrahydrofurine 949 were milled using a ball mill (3-inch pot mill manufactured by Nippon Kagaku Tou Co., Ltd.).
Kneaded for hours. The obtained pigment dispersion was applied onto a sia aluminum plate (thickness: 0.1 am) using an applicator.

It was dried at 100° C. for 15 minutes to form a charge generation layer with a thickness of about 0.5 μm.

Next, BTZ-4sg and polyester resin 159 were mixed with 200 g of tetrahydrofuran. The obtained liquid was coated onto the charge generation layer using an ablator and dried at 90° C. for 20 minutes to form a charge transport layer with a thickness of about 10 μm.

Example 5 A charge generation layer similar to that in Example 1 was formed. BT on top of that
Z-2sg and polyester resin 159 in methylene chloride 1
20 g of a solution added to a mixed solvent of 1,1,2-trichloroethane 609 and tetrahydrofuran 509 was applied using an applicator.

It was dried at 115° C. for 30 minutes to form a charge transport layer with a thickness of about 10 μm.

Example 6 r-HhPC1,Og, BTZ-35,0g,
HolJ ester resin 15g, methylene chloride 1209,
A mixture of 1.1.2-trichloroethane aog and tetrahydrofuran 509 was kneaded for 10 hours using a ball mill. The resulting dispersion was applied onto a sialuminum plate using an applicator and dried at 120° C. for 15 minutes to produce a single-layer electrophotographic photoreceptor having a film thickness of 10 μm.

The electrophotographic properties of the obtained electrophotographic photoreceptor were measured using an electrostatic recording paper tester (manufactured by Kawaguchi Electric, 5P-428),
The results are shown in Table 1.

The initial potential Vo (V) in the table indicates the charging potential when a negative or positive 5KV corona is discharged for 10 seconds in dynamic measurement, and the dark decay Vk indicates the potential retention rate when left in the dark for 30 seconds. Shows Es.

indicates the initial negative value (I!x-s) required for the potential to drop by 50 - when irradiated with 10 lux of white light. Residual potential V8 indicates the surface potential after irradiation with 10 lux white light for 30 seconds.

Further, the electrophotographic photoreceptor was applied to an electrophotographic apparatus using the Carlson method, and images were produced using a test chart, and the initial resolution and the resolution after continuous copying of 7,500 sheets are also shown in Table IK.

The electrophotographic photoreceptor of the comparative example had good electrophotographic properties, especially the half-death exposure was small and had high sensitivity, but the number of copies was 7.50.
The resolution after 0 frames is extremely low. On the other hand, the electrophotographic photoreceptors of Examples 1 and 2 had electrophotographic characteristics with high sensitivity equivalent to those of the comparative example.

Moreover, there is very little reduction in resolution. Since the photoreceptor of Example 3 is a single-layer type, the electrophotographic properties are slightly inferior, but there is no reduction in resolution at all. Examples 4, 5, and 6 have slightly inferior electrophotographic characteristics, but the decrease in resolution is small.

As described above, the electrophotographic photoreceptor using the thiazole derivative of the present invention as a charge transport material has high sensitivity.

It can also be seen that it is an excellent electrophotographic photoreceptor with little reduction in resolution during use.

(Effects of the Present Invention) The electrophotographic photoreceptor according to the present invention has excellent electrophotographic properties and printing life.

Claims (1)

[Claims] 1. In an electrophotographic photoreceptor in which a layer containing a charge transport substance and a charge generation substance is provided on a conductive support, the charge transport substance has the following general formula (I) ▲ Numerical formula, chemical formula, table, etc. (I) [In the formula, R_1, R_2, and R_3 each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, An electrophotographic photoreceptor comprising a thiazole derivative represented by the following formula: an unsubstituted aralkyl group or a substituted or unsubstituted heterocyclic group. 2. The electrophotographic photoreceptor according to claim 1, wherein the charge generating substance is a phthalocyanine pigment and/or a naphthalocyanine pigment. 3. The electrophotographic photoreceptor according to claim 1 or 2, wherein the charge transport material and the charge generation material are each contained in separate layers. 4. The electrophotographic photoreceptor according to claim 1 or 2, wherein the charge transport material and the charge generation material are contained in the same layer.