JP2007064998A - Electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which is satisfactory in electrophotographic characteristics and image quality, is high in discharge resistance, wear resistance and heat deterioration resistance, and is long in printing resistance lifetime. <P>SOLUTION: In the electrophotographic photoreceptor having a conductive layer, a charge generating layer containing an organic pigment generating charges, a charge transfer layer having a function of charge holding/transfer, and a protective layer, a flat inorganic packing material which is powder of ≤1 μm in average grain size is added to a thermosetting resin or a thermoplastic resin, which is used in the protective layer, at 0.5 to 15 parts by weight to 100 parts by weight resin and both are uniformly composited. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member having a conductive layer, a charge generation layer containing an organic pigment for generating charges, and a charge transport layer having a charge holding / transporting function.

  In an electrophotographic photoreceptor using a photoconductive substance as a photosensitive material, conventionally, an inorganic photoconductive substance such as selenium, zinc oxide, titanium oxide, cadmium sulfide has been mainly used as the photoconductive substance. Although these inorganic photoconductive substances have excellent photoconductive performance, they are generally highly toxic and therefore have a problem of having a great influence on the environment during daily maintenance and disposal.

  On the other hand, photosensitive materials using organic photoconductive compounds are generally less toxic than those using inorganic photoconductive substances, and are transparent, flexible, lightweight, surface smoothness, price, etc. In recent years, it has been widely studied and put into practical use. In particular, composite photoconductors that separate the functions of charge generation and transport can greatly improve the sensitivity, which has been a major drawback of conventional photoconductors using organic photoconductive compounds. Has made great progress.

  When these composite photoconductors are applied to an electrophotographic apparatus, first, an electrostatic latent image is formed on the surface of the photoconductor, and then developed with a developer generally called a toner charged to a different sign, The image can be transferred and fixed to another substrate, such as paper, to obtain a copy.

  In general, an electrophotographic photoreceptor using the conventional organic photoconductive compound as described above is generally formed by sequentially laminating a charge generation layer and a charge transport layer on a conductive layer, and charging the surface of the photoreceptor, followed by light irradiation. To form an electrostatic latent image. In addition, after transferring the developed toner image to paper or the like by attaching a toner charged with a different sign to the formed electrostatic latent image, the toner remaining on the surface of the photoreceptor for the next copy is detached and collected. Is done.

  Here, in order to charge the surface of the photosensitive member, there is a case where charging means using discharge is used. In this case, erosion deterioration due to the generated discharge itself or oxidation deterioration due to ozone generated by the discharge. Depending on the case, the organic matter on the surface of the photoreceptor may be deteriorated.

  On the other hand, when collecting the toner remaining on the photoreceptor surface by bringing a collection means such as a collection brush or a collection blade into contact with the surface of the photoreceptor, the organic material on the surface of the photoreceptor is mechanically affected by abrasion with the contacted collection means. Will deteriorate. Further, when the formed toner image is transferred to a substrate such as paper, wear due to contact with the substrate, heat generated by a heat fixing means disposed near the photoconductor for fixing the toner image transferred to the substrate is a heat source. The organic material used in the photoreceptor deteriorates due to deterioration or the like.

  As described above, the organic material used in the photoconductor gradually deteriorates in the process of repeatedly performing copying because various deterioration elements act alone or in combination. In particular, the surface of the photoconductor is most susceptible to damage, so that its smoothness is lost as the deterioration progresses, leading to a decrease in printing performance such as blurring of the transferred image. It also causes a significant reduction in the life of the photoreceptor, such as peeling of the layers.

As described above, since the photoreceptor is required to have strong durability, as disclosed in Patent Document 1 and Patent Document 2, the surface of the outermost layer of the photoreceptor is made of a thermoplastic resin or a thermosetting resin. It has been proposed to provide a protective layer.
JP 52-76928 A JP 54-17732 A

  However, when a protective layer is provided on the outermost layer surface of the photoreceptor as described above, it is necessary to increase the thickness of the protective layer in order to obtain a sufficient wear resistance effect. There has been a drawback that the residual potential in electrophotographic characteristics is liable to increase and the sensitivity tends to decrease. Therefore, development of an electrophotographic photosensitive member that improves the durability of the photosensitive member and prevents a decrease in sensitivity has been eagerly desired.

  The present invention has been proposed in order to solve the above-mentioned problems of the prior art, and its purpose is that electrophotographic characteristics and image quality are good, and discharge resistance, wear resistance, and heat deterioration resistance are good. An object of the present invention is to provide an electrophotographic photosensitive member that is high and has a long printing life.

  In order to achieve the above object, the invention described in claim 1 includes a conductive layer, a charge generation layer containing an organic pigment that generates charges, a charge transport layer having a charge holding / transport function, and a protective layer. The electrophotographic photoreceptor is characterized in that a flat inorganic filling material is uniformly combined with a thermosetting resin or a thermoplastic resin used in the protective layer.

  According to the invention of claim 1 having the above-described configuration, a flat and fine inorganic filling material dispersed in a thermosetting resin or a thermoplastic resin used in a protective layer located on the surface of the photoreceptor. Suppression of erosion degradation of resin material due to discharge, suppression of thermal oxidation degradation due to suppression of gas diffusivity, improvement of mechanical strength due to restraint of polymer chain, wear resistance by surface coating of fine inorganic filler Therefore, a strong protective layer having good discharge resistance, heat resistance, wear resistance and the like can be obtained. As a result, a robust protective layer can be obtained, so that a high-definition electrostatic latent image can be formed, electrophotographic characteristics and image quality are good, and discharge resistance, wear resistance, and heat deterioration resistance are high. An electrophotographic photosensitive member having a long printing life can be obtained.

  The invention according to claim 2 is the electrophotographic photosensitive member having a conductive layer, a charge generation layer containing an organic pigment for generating charges, and a charge transport layer having a charge holding / transporting function. About the thermosetting resin or thermoplastic resin used in each of the charge transport layer and the charge transport layer, flat inorganic filling only in the charge transport layer resin or both the charge generation layer charge charge layer resin and the charge transport layer resin It is characterized by uniformly compounding the materials.

  According to the invention described in claim 2 having the above-described configuration, a flat and fine inorganic material dispersed in a thermosetting resin or a thermoplastic resin used in at least the charge transport layer located on the surface of the photoreceptor. Filling material suppresses erosion degradation of resin material due to electric discharge, suppresses thermal oxidative degradation due to suppression of gas diffusivity, improves mechanical strength due to restraint of polymer chain, surface coating of minute inorganic filler Since it contributes to the improvement of wear resistance, a strong charge transport layer having good discharge resistance, heat resistance, wear resistance and the like can be obtained. As a result, good durability can be realized without providing a protective layer on the surface of the photoreceptor, electrophotographic characteristics and image quality are good, and discharge resistance, wear resistance, and heat deterioration resistance are good. An electrophotographic photosensitive member that is high and has a long printing life can be obtained.

According to a third aspect of the present invention, in the electrophotographic photosensitive member according to the first or second aspect, the inorganic filler is a layered clay compound.
The invention according to claim 4 is the electrophotographic photosensitive member according to claim 3, wherein the layered clay compound contains at least one selected from a mineral group consisting of a smectite group, a mica group, and a vermiculite group. It is characterized by.
The invention according to claim 6 is the electrophotographic photosensitive member according to claim 1 or 2, wherein the inorganic filling material is boron nitride.

  The inventions according to claims 3, 4, and 6 having the above-described configuration define the inorganic filling material more specifically.

The invention according to claim 5 is the electrophotographic photosensitive member according to claim 3 or 4, wherein the metal cation existing between the layers of the layered clay compound is substituted with a quaternary ammonium salt. To do.
According to the invention of claim 5 having the above-described configuration, the affinity between the layered clay compound and the resin material to which the layered clay compound is added is improved, so that the delamination property during stirring is improved. Thus, dispersibility can be improved.

According to a seventh aspect of the present invention, in the electrophotographic photosensitive member according to any one of the first to sixth aspects, the inorganic filling material is a powder having an average particle size of 1 μm or less, and the amount added Is 0.5 to 15 parts by weight with respect to 100 parts by weight of the thermosetting resin or thermoplastic resin used in the layer to which the inorganic filler is added.
The invention described in claim 7 having the above-described configuration more specifically defines the properties and addition amount of the inorganic filling material.

  According to the present invention as described above, it is possible to provide an electrophotographic photosensitive member having good electrophotographic characteristics and image quality, high discharge resistance, wear resistance and heat deterioration resistance, and a long printing life.

  Next, the best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be specifically described with reference to the drawings.

(1) First Embodiment (1-1) Configuration As shown in FIG. 1, the electrophotographic photosensitive member of the present embodiment is a conductive film or plastic film, a plastic film in which a metal foil such as aluminum is laminated, A charge generation layer 2 containing an organic pigment that generates charges, a charge transport layer 3 having a charge holding / transport function, and a protective layer on the outer peripheral surface of a conductive layer 1 made of a conductive material such as a metal plate or a metal drum 4 are sequentially laminated by means such as coating.

  Here, as an organic pigment for generating charges contained in the charge generation layer 2, azoxybenzene, disazo, trisazo, benzimidazole, polycyclic quinoline, indigoid, quinacridone, phthalocyanine, perylene It is possible to use pigments that are known to generate charges upon irradiation with light such as methine and methine. In addition to such organic pigments, any organic pigment that generates charge carriers by light irradiation can be used.

  In this embodiment, a flat and fine inorganic filler is uniformly combined with a thermoplastic resin or a thermosetting resin that forms the protective layer 4 serving as the outermost layer (photoconductor surface). As this inorganic filler, a layered clay compound or boron nitride (BN) as exemplified later is used.

  In addition, by using particles having a flat shape as the inorganic filling material, when the photoreceptor layer is applied to a substrate such as a metal drum, the inorganic material uniformly mixed inside the resin is in a direction parallel to the substrate surface. The action / effect of exhibiting a tendency to be oriented and showing a higher shielding effect / resistance against erosion degradation, gas diffusion, wear, etc. from the surface layer than when spherical particles are used is obtained.

  Further, the size of the inorganic filler to be added is required to be fine particles having an average particle size of 1 μm or less, and particularly preferably 0.1 μm or less. Moreover, it is preferable that the addition amount of the inorganic filler to the thermoplastic resin or thermosetting resin forming the protective layer 4 is 0.5 to 15 parts by weight with respect to 100 parts by weight of the resin.

  Here, as a resin material for forming the protective layer 4, in addition to the conventionally used cured film of butyl etherified melamine / formaldehyde resin or polyvinyl acetal resin, polyethylene, polypropylene, acrylic resin, methacryl Resins, vinyl chloride resins, vinyl acetate resins, epoxy resins, polyurethane resins, phenol resins, polyester resins, alkyd resins, polycarbonate resins, silicone resins, melamine resins, and other addition polymerization resins, polyaddition resins, polycondensation resins, In addition, various thermosetting resins and thermoplastic resins such as copolymer resins containing two or more of these resin repeating units can be used.

  The layered clay compound only needs to contain at least one selected from a mineral group consisting of a smectite group, a mica group, and a verculite group. For example, in the smectite group, montmorillonite, hectorite, saponite, saconite, beidellite, stevensite, nontronite and the like can be mentioned. Examples of the mica group include chlorite, phlogopite, lepidrite, mascobite, biotite, paragonite, margarite, teniolite, and tetrasilicic mica. Examples of the vermiculite group include trioctahedral vermiculite and dioctahedral vermiculite.

  These layered clay compounds have a structure in which a silicate layer is laminated. In order to uniformly combine this layered clay compound in the above thermoplastic resin or thermosetting resin, the silicate layer can be separated and dispersed by simple stirring. Since it is difficult, it is desirable to stir and disperse in a state where a high shear force is applied with a ball mill, an attritor, a roll mixer or the like.

  As described above, the layered clay compound has a structure in which silicate layers are laminated, and the layers are bonded with metal cations. By using an organically modified layered clay compound in which the metal cation is replaced with an organic compound, the affinity with the resin material for forming the protective layer is improved, the delamination property during stirring is improved, and the dispersibility is improved. can do. As the organic compound for ion exchange, it is desirable to use various quaternary ammonium salts.

  Further, the boron nitride (BN) is an inorganic particle having a flat crystal form, and the action / effect as the above-described “flat” particle can be obtained. Furthermore, since boron nitride (BN) is a crystalline material that exhibits high thermal conductivity as a simple substance, it acts to improve the thermal conductivity of the coating layer when it is compounded with a high filling rate in the resin. The effect which suppresses the thermal deterioration of the resin material is acquired.

(1-2) Actions / Effects According to the electrophotographic photosensitive member of the present embodiment having the above-described configuration, the flat and fine inorganic filling material uniformly dispersed therein causes the erosion degradation of the resin material due to discharge. It contributes to suppression, thermal oxidation degradation due to suppression of gas diffusibility, improvement of mechanical strength due to restraint of polymer chains, improvement of wear resistance due to surface coating of minute inorganic filler, etc. A strong protective layer 4 having good discharge properties, heat resistance, wear resistance and the like is obtained.

  For this reason, since a robust protective layer can be obtained even if the film thickness of the protective layer 4 is reduced, a high-definition electrostatic latent image can be formed, electrophotographic characteristics and image quality are good, and It is possible to provide an electrophotographic photosensitive member having high dischargeability, wear resistance, and heat deterioration resistance and a long printing life.

(2) Second Embodiment (2-1) Configuration This embodiment relates to an electrophotographic photosensitive member having no protective layer.
That is, as shown in FIG. 2, the electrophotographic photosensitive member of this embodiment is a conductive material such as a paper or plastic film subjected to conductive treatment, a plastic film laminated with a metal foil such as aluminum, a metal plate, a metal drum, or the like. A charge generation layer 2 containing an organic pigment that generates charges and a charge transport layer 3 having a charge holding / transporting function are sequentially laminated on the outer peripheral surface of the conductive layer 1 made of the above by means such as coating.

  Here, as an organic pigment for generating charges contained in the charge generation layer 2, azoxybenzene, disazo, trisazo, benzimidazole, polycyclic quinoline, indigoid, quinacridone, phthalocyanine, perylene Pigments that are known to generate charges upon irradiation with light such as methine and methine can be used. In addition to such organic pigments, any organic pigment that generates charge carriers by light irradiation can be used.

  In the present embodiment, a flat and fine inorganic filler is uniformly combined with a thermoplastic resin or a thermosetting resin that forms the charge transport layer 3 serving as the outermost layer (photoconductor surface). As the inorganic filler, a layered clay compound or boron nitride as exemplified later is used.

  In addition, by using particles having a flat shape as the inorganic filling material, when the photoreceptor layer is applied to a substrate such as a metal drum, the inorganic material uniformly mixed inside the resin is in a direction parallel to the substrate surface. The action / effect of exhibiting a tendency to be oriented and showing a higher shielding effect / resistance against erosion degradation, gas diffusion, wear, etc. from the surface layer than when spherical particles are used is obtained.

  Further, the size of the inorganic filler to be added is required to be fine particles having an average particle size of 1 μm or less, and particularly preferably 0.1 μm or less. Moreover, it is preferable that the addition amount of the inorganic filler to the thermoplastic resin or thermosetting resin forming the charge transport layer 3 is 0.5 to 15 parts by weight with respect to 100 parts by weight of the resin.

  Here, as a resin material for forming the charge transport layer 3, an organic semiconductor having charge transport performance such as poly-N-vinyl carbazole, polyvinyl pyrene, polyvinyl benzothiophene, polyvinyl pyrazoline and derivatives thereof is used alone. Carbazole, 3-phenylcarbazole, 2-phenylindole, oxadiazole, 1-phenyl-3- (4-diethylaminostyryl) -5- (4-diethylaminophenyl) pyrazoline, hydrazone, 2-phenyl-4 Low molecular compounds having charge transport performance such as-(4-diethylaminophenyl) -5-phenyloxazole, triphenylamine, imidazole, polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin Two or more of addition resins such as polyurethane resins, phenol resins, polyester resins, alkyd resins, polycarbonate resins, silicone resins, melamine resins, polyaddition resins, polycondensation resins, and repeating units of these resins A resin dispersed in a thermosetting resin such as a copolymer resin containing thermoplastic resin or a thermoplastic binder resin can be used.

  The layered clay compound only needs to contain at least one selected from a mineral group consisting of a smectite group, a mica group, and a verculite group. For example, in the smectite group, montmorillonite, hectorite, saponite, saconite, beidellite, stevensite, nontronite and the like can be mentioned. Examples of the mica group include chlorite, phlogopite, lepidrite, mascobite, biotite, paragonite, margarite, teniolite, and tetrasilicic mica. Examples of the vermiculite group include trioctahedral vermiculite and dioctahedral vermiculite.

  These layered clay compounds have a structure in which a silicate layer is laminated. In order to uniformly combine this layered clay compound in the above thermoplastic resin or thermosetting resin, the silicate layer can be separated and dispersed by simple stirring. Since it is difficult, it is desirable to stir and disperse in a state where a high shear force is applied with a ball mill, an attritor, a roll mixer or the like.

  The layered clay compound has a structure in which silicate layers are laminated, and the layers are bonded with metal cations. By using an organically modified layered clay compound in which the metal cation is replaced with an organic compound, the affinity with the resin material for forming the charge transport layer is improved, the delamination property during stirring is improved, and the dispersibility is improved. Can be better. As the organic compound for ion exchange, it is desirable to use various quaternary ammonium salts.

  Further, the boron nitride (BN) is an inorganic particle having a flat crystal form, and the action / effect as the above-described “flat” particle can be obtained. Furthermore, since boron nitride (BN) is a crystalline material that exhibits high thermal conductivity as a simple substance, it acts to improve the thermal conductivity of the coating layer when it is compounded with a high filling rate in the resin. The effect which suppresses the thermal deterioration of the resin material is acquired.

(2-2) Actions / Effects According to the electrophotographic photosensitive member of the present embodiment having the above-described configuration, the flat and fine inorganic filler material uniformly dispersed therein causes the erosion degradation of the resin material due to discharge. It contributes to suppression, thermal oxidation degradation due to suppression of gas diffusibility, improvement of mechanical strength due to restraint of polymer chains, improvement of wear resistance due to surface coating of minute inorganic filler, etc. A strong charge transport layer 3 having good discharge properties, heat resistance, wear resistance and the like is obtained.

  Therefore, according to the present embodiment, it is possible to achieve good durability without providing a protective layer on the surface of the photoreceptor, good electrophotographic characteristics and image quality, and discharge resistance and wear resistance. It is possible to provide an electrophotographic photosensitive member having high heat deterioration resistance and a long printing life.

(3) Other Embodiments The present invention is not limited to the above-described embodiment, and in addition to the charge transport layer 3 shown in the second embodiment, a charge generation layer 2 disposed on the inside thereof is formed. Similarly to the above, if the flat and fine inorganic filler is uniformly combined, the above-mentioned deterioration-resistant effect is obtained for all organic layers laminated on the conductive layer 1. Therefore, a more robust and durable electrophotographic photosensitive member can be obtained.

  Here, as a resin material for forming the charge transport layer 3, an organic semiconductor having charge transport performance such as poly-N-vinyl carbazole, polyvinyl pyrene, polyvinyl benzothiophene, polyvinyl pyrazoline and derivatives thereof is used alone. Carbazole, 3-phenylcarbazole, 2-phenylindole, oxadiazole, 1-phenyl-3- (4-diethylaminostyryl) -5- (4-diethylaminophenyl) pyrazoline, hydrazone, 2-phenyl-4 Low molecular compounds having charge transport performance such as-(4-diethylaminophenyl) -5-phenyloxazole, triphenylamine, imidazole, polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin Two or more of addition resins such as polyurethane resins, phenol resins, polyester resins, alkyd resins, polycarbonate resins, silicone resins, melamine resins, polyaddition resins, polycondensation resins, and repeating units of these resins A resin dispersed in a thermosetting resin such as a copolymer resin containing thermoplastic resin or a thermoplastic binder resin can be used.

  The resin material for forming the charge generation layer 2 is the same resin material as that of the charge transport layer 3, but the substance to be supported is not a charge transport substance but an azo dye (monoazo dye, polyazo dye, metal Complex salt azo dyes, pyrazolone azo dyes, stilbene azo dyes, thiazole azo dyes, etc.), perylene dyes (perylene acid anhydride, perylene imide, etc.), anthraquinone to polycyclic quinone dyes (anthraquinone derivatives, anthanthrone derivatives, di) Benzpyrenequinone derivatives, pyranthrone derivatives, violanthrone derivatives, isoviolanthrone derivatives, etc.), indigoid dyes (indigo derivatives, thioindigo derivatives, etc.), phthalocyanine dyes (metal phthalocyanine, metal-free phthalocyanine, etc.), carbonium dyes (diphenylmethane dyes) ,bird Phenylmethane dye, xanthene dye, acridine dye, etc.), quinoneimine dye (azine dye, oxazine dye, thiazine dye, etc.), methine dye (cyanine dye, azomethine dye, etc.), quinoline dye, nitro dye, nitroso dye, It differs from the charge transport layer 3 in that it is changed to various organic pigments such as benzoquinone and naphthoquinone dyes, naphthalimide dyes, perinone dyes (bisbenzimidazole derivatives, etc.) and quinacridone dyes.

Sectional drawing which shows the structure of 1st Embodiment of the electrophotographic photoreceptor which concerns on this invention. Sectional drawing which shows the structure of 2nd Embodiment of the electrophotographic photoreceptor which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Conductive layer 2 ... Charge generation layer 3 ... Charge transport layer 4 ... Protective layer

Claims (7)

In an electrophotographic photosensitive member having a conductive layer, a charge generation layer containing an organic pigment that generates charge, a charge transport layer having a charge holding / transporting function, and a protective layer,
An electrophotographic photoreceptor, wherein a flat inorganic filling material is uniformly combined with a thermosetting resin or a thermoplastic resin used in the protective layer. In an electrophotographic photosensitive member having a conductive layer, a charge generation layer containing an organic pigment for generating charge, and a charge transport layer having a charge holding / transporting function,
The thermosetting resin or thermoplastic resin used in each of the charge generation layer and the charge transport layer is flattened only on the charge transport layer resin or on both the charge generation layer and charge transport layer resins. An electrophotographic photosensitive member characterized by uniformly combining various inorganic filler materials.   The electrophotographic photosensitive member according to claim 1, wherein the inorganic filler is a layered clay compound.   4. The electrophotographic photoreceptor according to claim 3, wherein the layered clay compound contains at least one selected from a mineral group consisting of a smectite group, a mica group, and a vermiculite group.   The electrophotographic photoreceptor according to claim 3 or 4, wherein a metal cation existing between layers of the layered clay compound is substituted with a quaternary ammonium salt.   The electrophotographic photosensitive member according to claim 1, wherein the inorganic filling material is boron nitride.   The inorganic filling material is a powder having an average particle size of 1 μm or less, and the addition amount is 100 parts by weight of the thermosetting resin or thermoplastic resin used in the layer to which the inorganic filling material is added. The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is 0.5 to 15 parts by weight.

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