WO2006134755A1 - Electrophotographic electrification member and electrophotographic image forming apparatus using the same - Google Patents

Abstract

This invention provides an electrophotographic electrification member having a polyurethane foam layer, which is less likely to undergo strain by compressive force, and an electrophotographic image forming apparatus using the same. The electrophotographic electrification member having a polyurethane foam layer is characterized in that the polyurethane foam layer contains tin-containing electrically conductive metal oxide particles as a polymerization catalyst for polyurethane foaming, and electrically conductive particles using carbon, the volume specific resistance of the electrically conductive metal oxide particles is less than 107 Ω·cm, and electrically conductive particles, which do not function as the polymerization catalyst of the polyurethane foam, are contained in an amount of not less than 1% by mass and less than 20% by mass.

Description

 Specification

 Electrophotographic charging member and electrophotographic image forming apparatus using the same

 The present invention relates to a charging member used in an electrophotographic image forming apparatus such as a copying machine or a printer using an electrophotographic developing system, and an electrophotographic image forming apparatus using the charging member.

 Background art

 Conventionally, in a copying machine or a printer using an electrophotographic developing system, a photoconductor

 A charging roll is used to charge the surface of the photoreceptor by being brought into pressure contact with the (drum) and applying a DC voltage and an AC voltage superimposed on each other. As one of such charging tools, as described in JP-A-11-305519 (Patent Document 1), a conductive rubber composition is formed on the outer peripheral surface of a shaft body (core metal). A conductive base layer having a solid structure formed by using the conductive base layer is provided with a predetermined thickness, and a resistance adjustment layer is provided on the outer peripheral surface of the conductive base layer. It is known that an electrode layer is formed between the adjustment layer and a protective layer is laminated on the outer peripheral surface of the resistance adjustment layer.

 [0003] In the above patents, it is proposed that an amorphous metal oxide conductive agent is used as a contact charging member with less pinhole generation, and that the particle size of the conductive agent is 1 to: LOOnm. We proposed a charging member whose surface was coated with conductive rubber formed using tin oxide sol. However, these charging rolls are less likely to bleed and have improved unevenness and improved durability. The hardness of the rubber is low and the contact surface on the surface of the photoconductor does not work well, which may cause uneven charging. .

[0004] Further, foaming is performed using a conductive foaming rubber composition in which conductive particles such as carbon black and metal powder are added to the outer peripheral surface of the shaft body as having a different structure. The formed conductive base layer is provided with a predetermined thickness, and a substantially thin surface smooth layer having a thermoplastic resin material force is provided on the outer peripheral surface of the conductive base layer. A resistance adjustment layer is further provided on the outer peripheral surface of the smooth layer, and if necessary, the outer peripheral surface of the resistance adjustment layer. JP-A-2001-154456 (Patent Document 2) is known in which a protective layer is formed by laminating a protective layer thereon.

[0005] Further, as a general method for producing foamed polyurethane, JP 2003-301022 A (Patent Document 3) discloses polyurethane foam rubber using triethylenediamine or acid tin sol as a catalyst. is doing.

 [0006] In the charging roll having a foamed structure, the conductive base layer is formed with a foamed sponge structure, so that it is advantageous to reduce the hardness without adding a large amount of softening agent. This could be achieved, and contamination of the photoreceptor due to the exudation of the softening agent from the conductive base layer could be effectively prevented.

[0007] Further, as described above, excellent characteristics not seen in a charging roll having a conductive base layer configured with a solid structure, such as its light weight can be advantageously achieved, can be exhibited. ! /

[0008] Further, the surface smoothing layer provided on the outer peripheral surface of the conductive base layer can impart smoothness to the surface of the conductive base layer that has been exposed to air bubbles and is in a rough state.

On the outer peripheral surface of the conductive base layer, a resistance adjusting layer and a protective layer for reducing leak-proof material adhesion can be satisfactorily formed.

 Patent Document 1: JP-A-11 305519

 Patent Document 2: Japanese Patent Laid-Open No. 2001-154456

 Patent Document 3: Japanese Patent Laid-Open No. 2003-301022

 Disclosure of the invention

 Problems to be solved by the invention

[0009] By the way, as is well known, it is necessary to contact these charging rolls with a uniform force when used in contact with the photoreceptor.

[0010] In addition, it is important to combine durability for maintaining stable pressing for a long time, conductivity, and charging characteristics (appropriate leakage current range).

[0011] For this reason, foaming rubber is suitable because of the stability of the pressing force and the ability to follow the surface of the photoreceptor, which have been known so far. In order to achieve the required volume resistivity of about 10 ⁶ Ωcm, a considerable amount of conductive material Force required to be added Carbon black or the like needs to be added, and carbon black alone has high conductivity, so that there is a problem that the composite electrical resistance with rubber rapidly decreases.

 [0012] When mixing both, devise a mixing method! There is a risk of causing wrinkles and uneven charging.

 [0013] To achieve the object of the invention other than the mixing method, attention must be paid to the stability of the reaction. In the synthesis of polyurethane, the reaction is controlled by the combined use of an amine compound and organotin.

 When polyurethane is used for the charging roll, since the polyurethane is insulative, the electrical characteristics of the charging roller to which conductive particles are added are controlled.

 [0015] However, in the foam added with the conductive particles of the prior art, the distortion due to the compressive force is difficult to recover, and it is slightly deformed to come into contact with the photoconductor, causing abnormal noise. I found out that

 [0016] As a result of intensive studies, the present inventors have found that the addition of conductive particles is a large factor affecting the strain due to compressive force. In other words, in the prior art, the conductive particles are simply dispersed as a conductive material, and therefore, at the interface between the conductive particles and the foam, interfacial peeling or cracks occur due to external force. It is presumed that the distortion will not be recovered soon after this.

 [0017] Since such abnormal noise is smaller than the sound that generates the overall power of the device, it has not been noticed so far, but as the device is improved, the generated noise level becomes smaller and the noise generated by the charging roll is reduced. Began to become a problem.

 [0018] On the other hand, Japanese Patent Application Laid-Open No. 2003-301022 filed by the present applicant regarding polyurethane includes acid stannic sol having an amino group as a polyurethane foaming catalyst (tin sol itself is Japanese Patent Publication No. 35-6616). Using organometallic catalysts for polyurethane foams by using the method described in the previous section! /, And proposing measures against bleed deposition for environmental hormones!

[0019] In addition, Japanese Patent Application Laid-Open No. 11-305519 discloses a force disclosed by a manufacturing method of a charged roller using a tin oxide sol as a conductive substance, these are so-called rubbers which are not foamable, and these The charging roller made by this method improves durability, but the hardness is lower than that of foam. Therefore, the problem of unevenness of the part that is pressed against the photoconductor and the part that is not so is the problem.

 The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electrophotographic charging member having a polyurethane foam layer that is not easily distorted by compressive force, and electrophotographic image formation using the same. To provide an apparatus.

 [0021] Japanese Patent Application Laid-Open No. 11-305519 discloses that the use of an acid-tin tin sol as a conductive agent discloses that 10 vol% is preferable according to this publication. When this invention is used for foamed polyurethane, a sufficient amount of acid-tin tin sol is added, and the necessary electrical conductivity for the charging roll can be obtained, but it becomes difficult to control polyurethane foaming.

 Means for solving the problem

The object of the present invention is achieved by the following configurations. The electrophotographic charging member having a polyurethane foam layer contains conductive metal oxide particles containing tin and conductive particles using carbon as a polymerization catalyst for polyurethane foam and the conductive metal oxide. A polyurethane foam layer having a volume resistivity of less than 10 ⁷ Q ′ _C m and containing 1% by mass or more and less than 20% by mass of conductive particles that do not act as a polymerization catalyst for the polyurethane foam. An electrophotographic charging member characterized by the above.

 2.

 2. The electrophotographic charging member according to 1 above, wherein an amine compound is used in combination as the polymerization catalyst.

 3.

 2. The charging member for electrophotography according to 1 or 2 above, wherein the particles containing 1% by mass or more and less than 20% by mass of conductive particles that do not act as a polymerization catalyst for the polyurethane foam are carbon.

 Four.

4. The electrophotographic charging member according to any one of 1 to 3, wherein the electrophotographic charging member is an electrophotographic charging roll. 5. An electrophotographic image forming apparatus using the electrophotographic charging member according to any one of 1 to 4 above.

 6.

 6. The electrophotographic image forming apparatus as described in 5 above, wherein the electrophotographic charging member is charged in contact with a member to be charged.

[0023] The present inventor exists in the form of a polymerization catalyst by using an electrophotographic charging member having a polyurethane foam layer containing conductive metal oxide particles used as a polymerization catalyst. Since the metal oxide particles are bonded to the polyurethane existing around the particles, the metal oxide particles are not easily distorted by the compressive force, and the metal oxide particles are electrically conductive. As a result, the amount of conductive particles that do not act as an additive can be reduced, and the recovery of compressive strain of the polyurethane foam layer is improved, leading to the present invention.

 The invention's effect

 [0024] According to the charging member of the present invention, the polyurethane foam layer of the charging member is not easily distorted by a compressive force.

 Brief Description of Drawings

 FIG. 1 is a perspective view showing a main part of an image forming apparatus according to an embodiment of the present invention.

 Explanation of symbols

[0026] 1 Semiconductor laser light source

 2 Polygon mirror

 3 ί θ lens

 4 Photosensitive drum

 5 Charging roller

 51 Shaft (Core)

 6 Developer

 7 Transfer device

8 Transcript 9 Separation pole

 10 Fixing unit

 11 Cleaning device

 12 Pre-charge exposure (PCL)

 13 Cleaning blade

 14 Power supply

 BEST MODE FOR CARRYING OUT THE INVENTION

Examples of embodiments relating to the present invention are shown below, but the aspects of the present invention are not limited to these.

<Electrophotographic image forming apparatus>

 First, an electrophotographic image forming apparatus using the charging member according to the present invention will be described. In this example, a charging roll is used as a charging member, and a photoconductor is used as a member to be charged.

FIG. 1 is a cross-sectional configuration diagram showing an example of an electrophotographic image forming apparatus of the present invention. Reference numeral 4 denotes a photosensitive drum as a charged body, which is formed by forming an organic photoconductor (OPC) as a photosensitive layer on the outer peripheral surface of an aluminum drum base, and rotates at a predetermined speed in the direction of an arrow. Do

In FIG. 1, exposure light is emitted from the semiconductor laser light source 1 based on information read by a document reading device (not shown). This is divided by the polygon mirror 2 in the direction perpendicular to the paper surface of FIG. 1, and is projected onto the surface of the photoconductor through the fΘ lens 3 that corrects image distortion, thereby forming an electrostatic latent image. The photosensitive drum 4 is uniformly charged by the charging roll 5 in advance, and starts rotating clockwise in accordance with the timing of image exposure.

 [0031] The electrostatic latent image on the surface of the photosensitive drum is developed by the developing device 6, and the formed developed image is transferred to the transfer member 8 conveyed in time by the action of the transferring device 7. . Further, the photosensitive drum 4 and the transfer body 8 are separated by a separator (separation electrode) 9, but the developed image is transferred and supported on the transfer body 8 and guided to the fixing device 10 and fixed.

[0032] Untransferred toner remaining on the surface of the photoconductor is cleaned by a cleaning device 11 using a cleaning blade method, and the residual charge is removed by pre-charge exposure (PCL) 12, and then charged again for the next image formation. The roll 5 is uniformly charged. A power supply unit 14 applies a voltage to the charging roll 5 and supplies a predetermined voltage to a shaft body (core metal) 51 of the charging roll 5. The applied voltage is preferably a DC voltage superimposed with an AC voltage.

 [0034] The mechanical pressure applied between the charging roll and the electrophotographic photosensitive member is such that the contact pressure of the charging roll to the photosensitive member is 5 to 500 gZcm, and the electrical pressure is applied to the charging roll. The DC voltage to be adjusted should be adjusted to an absolute value of 200 to 900 V, and when applying an AC voltage, the peak to peak voltage should be adjusted to 500 to 5, OOOVp-p, and the frequency should be adjusted to 50 to 3,000 Hz.

 [0035] For example, the applied voltage preferably has a peak-to-peak voltage value that is at least twice the charging start voltage value for the photoreceptor.

[0036] The charging roll may be driven and driven non-rotatingly by a surface-driven driven photoconductor, or in a forward or reverse direction with respect to the surface movement direction of the photoconductor at the contact portion. Even if it is actively driven to rotate at a predetermined peripheral speed,

[0037] The transfer member is typically plain paper, but is not particularly limited as long as it can transfer an unfixed image after development, and of course includes a PET base for OHP.

[0038] The cleaning blade 13 uses a rubber-like elastic body having a thickness of about 1 to 30 mm, and urethane rubber is most often used as the material. Since this is used in pressure contact with the photoconductor, it is desirable to provide a release mechanism that easily transfers heat and to keep it away from the photoconductor when no image forming operation is performed.

<Charging roll>

 Next, the charging roll according to the present invention will be described in detail.

The charging roll 5 includes a shaft body (core metal) 51 made of a stainless steel rod and a conductive elastic layer portion 52 having a polyurethane foam layer on the outer periphery thereof.

[0041] If the charging roll 5 can achieve the object of the present invention, the polyurethane foam layer of the present invention can be used.

One layer may be provided. In addition to the polyurethane foam layer of the present invention, other elastic layers may be combined.

[0042] From the viewpoint of charging performance and leakage prevention, the volume resistivity of the polyurethane foam layer of the charging roll is 10 ³ Ω'cm ~: LO ^u Q'cm, more preferably 10 ⁶ Ω'cm ~ : LO ^u Q 'c m is preferred.

 [0043] The volume resistivity of the polyurethane foam layer can be measured by the following method.

[0044] The polyurethane foam is cut into cubes each having a side of 5 cm, and is applied with a pressure of 10 ⁷ Pa with a flat plate press heated to 140 ° C and left for 20 minutes to form a sheet. The middle part of this sheet is cut out with a width of lcm to make a sample for measuring volume resistivity. Since the thickness of the sample differs depending on the density of the foam, measure it with a thickness gauge. Adhere four copper wires with a diameter of 0.2 mm and a length of 4 cm to the surface of the sample cut into 1 cm x 5 cm strips using a dotite and dry thoroughly. Using the electrode thus formed, volume resistivity is measured by the 4-terminal method in an environment adjusted to a temperature and humidity of 25 ° C and 50% RH.

[0045] The density of the polyurethane foam layer of the charging roller of the present invention, 0. 02gZcm ³ Power et al. 0. 5 g / cm ^3, further preferably be 0. 03gZcm ³ force better 0. lgZcm ^3. If the density is too high, the resistivity will increase, and if the density is too low, it will be too soft.

 [0046] The density is measured by a known method.

 [0047] Hereinafter, a method for producing a polyurethane foam according to the present invention, conductive metal oxide particles used as a catalyst during the production, application of the conductive metal oxide particles to a catalyst for producing a polyurethane foam, polyurethane A foam etc. are demonstrated concretely.

 [0048] <Polyurethane foam>

 The polyurethane foam used in the present invention is a known flexible polyurethane foam having a basic blend prescription of polyether polyol or polyester polyol, or a mixture of both, isocyanate compound, catalyst, surfactant and foaming agent. The polyurethane resin handbook (Nikkan Kogyo Shimbun, edited by Keiji Iwata; ISBN: 4526022349; (1987/09)), a functional polyurethane, except that it relates to a polymerization catalyst in the novel electrophotographic charging roll manufacturing technology which is an embodiment of the invention Basics and Applications (Matsunaga Katsuji Edition; CMC; ISB N: 4882312972; (2000Z11)) and new edition polyurethane raw materials 'Comprehensive Survey of Products New Materials' New Material Series (CMC; ISBN: 4882316404; New Edition (2000Z09)) It is manufactured with the raw materials and manufacturing techniques described in known literatures such as

[0049] That is, in the presence of a catalyst, at least a polyol component and a polyfunctional isocyanate are added. In the process for producing a polyurethane foam having a step of reacting the composition to be contained, a process for producing a polyurethane foam containing conductive metal oxide particles used as the polymerization catalyst was devised and the present invention was completed.

 <Polyol component>

 The polyol component according to the present invention will be described.

[0051] Examples of the polyether polyol include polyhydric alcohols such as ethylene glycol, glycerin, and trimethylol propan, addition polymers obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide to these polyhydric alcohols, and the like. , And mixtures thereof.

[0052] The polyester polyol is obtained by a condensation reaction between a polyvalent carboxylic acid such as adipic acid, phthalic acid or succinic acid and a polyhydric alcohol such as ethylene glycol, propylene glycol, diethylene glycol, butylene glycol or trimethylolpropane. And the like, and mixtures thereof.

[0053] Examples of the polymer polyol include those obtained by polymerizing a butyl monomer such as acryl-tolyl or styrene in the presence of a radical polymerization initiator in at least one of the polyols listed above and stably dispersing them, and the like. These mixtures are mentioned.

[0054] Examples of other polyol components include a polyol in which melamine or ammonium polyphosphate is dispersed, a phosphorus-containing polyol, a polylataton-based polyol obtained by ring-opening polymerization of rataton using a polyhydric alcohol as an initiator, and a polycarbonate polyol. , Polygen polyols, and the like, and mixtures thereof.

[0055] Furthermore, the polyol may be used as an OH group-terminated polymer reacted with a polyfunctional isocyanate described below.

[0056] In particular, the use of a hydrophobic polyol described below is preferable because it provides water resistance.

 The hydrophobic polyol passes the polyol compatibility test described below and passes.

[0057] Specifically, dimer acid-based polyols include dimer acid and esterified products of polyfunctional hydroxides such as ethylene glycol, diethylene glycol, trimethylolpropane, and glycerin, castor oil and castor oil modified product, polybutadiene Polyol and water thereof Additives, polyisoprene-based polyols and hydrogenated products thereof. Examples of these polyols include, but are not limited to, OH group-terminated prepolymers or NCO group-terminated previously reacted with a polyfunctional isocyanate described later.

 [0058] <Multifunctional isocyanate>

 The polyfunctional isocyanate according to the present invention will be described.

 [0059] Polyfunctional isocyanates include aromatic polyisocyanates and aliphatic polyisocyanates containing two or more isocyanate groups in the molecule, or modified products thereof. , Toluene diisocyanate (TDI), Diphenolmethane isocyanate (MDI), Isophorone diisocyanate (IPDI), Hexamethylene diisocyanate (HDI), Tetramethylxylylene diisocyanate (TMXDI) And mixtures thereof. In addition, NCO group-terminal prepolymers reacted with the above-mentioned polyols, mixtures thereof and the like can be mentioned.

 [0060] <Polymerization catalyst>

 As the polymerization catalyst, conductive metal oxide particles described later are used. Moreover, it is preferable to use an amine compound in combination as the polymerization catalyst.

 [0061] As the amine compound, a general primary amine compound to a tertiary amine compound or a salt thereof can be used. Aromatic amines such as pyridine can also be used. Among these amine compounds, triethylenediamine is preferable.

 [0062] Here, it is preferable to mix the amine compound at a ratio of 0.01 to 2 for 0.01-2, in which case the strength is used only for stannic acid. In comparison, it improves the chemical properties of polyurethane foam rubber and contributes to improved durability.

 <Manufacturing method of polyurethane foam>

 The manufacturing method of the polyurethane foam of this invention is demonstrated.

[0064] The method for producing the polyurethane foam of the present invention forms a polyurethane foam using the raw materials described above, and the production method thereof is conventionally known (1 It can be produced by any of the following methods: a prepolymer method, (2) a one-shot method, and (3) a partial prepolymer method, but the one-shot method is preferably used in the present invention. [0065] For the one-shot method, reference can be made to, for example, published by Kobunshi Publishing Co., Ltd., Yoshio Imai, "Polyurethane Foam", (1987) and the like.

 [0066] In this one-shot method, a mixture of tin and polyol pre-mixed with PPG-BM and a mixture of carbon pre-mixed with TDI-80 are mixed to obtain a more homogeneous tin oxide and carbon. Even after the reaction after dispersion in the material, the conductive substances tin and carbon remain uniformly, so that it has suitable foaming properties and can ensure uniformity in the foamed polyurethane rubber.

 [0067] <Foam stabilizer>

 The foam stabilizer used in the present invention will be described.

 [0068] Examples of the foam stabilizer include organic silicone foam stabilizers, surfactants, and the like, and mixtures thereof. In the former, it is preferable not to use them depending on the application, but if they are used intentionally, they are polyfunctional. It is preferable to use a silicone foam stabilizer having an active group such as a hydroxyl group, a mercapto group, an amino group, an epoxy group, or a carboxyl group that reacts with a functional isocyanate. Examples of the latter include jetylaminooleate, sorbitan monostearate, glycerin monooleate, bulurpyrrolidone, fluorine, organic compound, and mixtures thereof.

 [0069] <Foaming agent>

 The foaming agent used in the present invention will be described.

 [0070] Examples of the foaming agent include water; inert gases such as nitrogen, carbon dioxide, and air, which are gaseous at normal pressure; halogen alkanes such as monofluorinated trichloromethane and didichloromethane; butane, pentane, and the like Examples include low boiling point alkanes; azobisisoptyl-tolyl that generates cracked nitrogen gas, and the like, and mixtures thereof.

 [0071] As other additives, a crosslinking agent, a colorant, a resin modifier, a flame retardant, an ultraviolet absorber, a durability improver, and the like can be optionally used as necessary.

[0072] If the metal oxide particles used as the catalyst have high conductivity, the polyurethane foam of the present invention can be used as it is for the charging roll, but when sufficient conductivity as the charging roll cannot be obtained. It is preferable to add 1% by mass or more of conductive particles that do not act as a catalyst. However, if a large amount of conductive particles that do not act as a catalyst are used in combination, Therefore, the addition of 20% by mass or more is not preferable.

[0073] The conductive particles that do not act as a catalyst have a volume resistivity of less than 10 ⁴ Ω 'cm, more preferably 10 ² Ω' cm. Less than good V ,. Carbon powders typified by carbon black and the like which are suitable as the conductive particles without acting as such a catalyst are materials described in the Carbon Black Handbook edited by the Carbon Black Association.

 [0074] The amount of carbon black is preferably 1% by mass or more and less than 20% by mass. If 20% by mass or more is mixed, the charging roller becomes too conductive, increasing the amount of leakage and degrading the charging performance.

 [0075] When the amount of carbon black is less than 1% by mass, the resistance becomes too high, and it is necessary to increase other catalyst metals in order to achieve the predetermined resistance, making it difficult to control the foaming reaction.

 <Conductive metal oxide particles>

 The conductive metal oxide particles according to the present invention (hereinafter sometimes referred to as metal oxide particles) will be described.

 [0077] The metal oxide particles are metal oxide particles having conductivity, metal oxide particles such as typical metal elements and transition metal elements shown in the periodic table as long as the object of the present invention can be achieved. The force that can be used may include a plurality of metal elements. For their compositional formula or chemical formula, reference can be made to the description of upper and lower inorganic chemistry (Kaifu-an) by Cotton Wilkinson. An acid compound having the same compositional formula or chemical formula as the crystalline compound described in this book can also be suitably used.

[0078] Note. The volume resistivity of the conductive metal oxide particles is preferably less than 10 ⁷ Ω′cm. Here, when particles of 10 ⁷ Ωcm or more are used, when trying to make a roller whose resistance of the charging roller of the present invention is ΙΟ ^ Ωcm or less, it is necessary to mix 30% by mass or more as a quantity. As a result, since the conductive metal particles have a catalytic action, an excessive reaction occurs in addition to the original tin oxide catalyst, making it difficult to control and a stable foam cannot be obtained.

[0079] The volume resistivity of the particles is measured by the two-terminal method in an environment adjusted to a temperature and humidity of 25 ° C and 50% RH after molding into a tablet. About tablet production method, After the mold, it is produced by applying hydrostatic pressure of 10 ⁸ Pa or more. Hydrostatic pressure of 5 X 10 ⁸ Pa or more may be applied, but if the pressure is too high, it will release from the rubber mold, so it is preferably less than 5 X 10 ⁸ Pa. More preferably, it is 3 × 10 ⁸ Pa or less.

 [0080] The catalytic activity of metal oxide particles varies depending on the element, and Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Mo, Pd, Ag, Cd, Among the preferred metal oxide particles containing at least one metal element selected from element group forces such as In, Sn, Sb, and Pt forces, high catalytic activity Sn ( Metal oxide particles containing tin).

 [0081] Further, the content of the Sn component in the metal oxide particles is usually 1% by mass or more of the Sn component, preferably 1% by mass to 95% by mass, and more preferably. Is 10% by mass to 90% by mass, and particularly preferably 50% by mass to 90% by mass.

 [0082] Amorphous metal oxide particles having high catalytic activity are preferably used as the metal oxide particles used in the present invention. Here, the amorphous metal oxide particles are those having a crystalline component content of less than 50%.

 In the present invention, the distinction between amorphous and crystalline can be made by analyzing the diffraction X-ray scattering pattern. Specifically, a substance with a crystallite size magnitude force less than lOOnm, which is calculated by the half-value width of one of the diffraction peaks measured at 100 degrees or less, is made amorphous. In the present invention, crystalline means a crystal having a clear unit cell and a repeating unit of 500,000 or more.

 [0084] The shape of the particles may be a spherical shape, a cubic shape, or a rectangular parallelepiped shape as observed by an electron microscope, and may not belong to any of these. Alternatively, it may be an aggregate of particles, a fibrous particle, or a tangled form thereof.

 [0085] Particles that can be distinguished from one particle when viewed with an electron microscope are called primary particles. In this case, if the primary particles are not spherical but anisotropic or fibrous, the size is expressed by the minimum size that can be measured. At this time, the size of the metal oxide particles is preferably in the range of 0.5 nm or more and 50000 nm or less of the average size of the primary particles observed in the electron microscope image from the viewpoint of improving the dispersion stability. More preferably, it is 0.5 nm or more and lOOOnm or less, and particularly preferably 0.5 nm or more and 500 nm or less.

[0086] The amount of organic matter contained in the metal oxide particles used as the catalyst of the present invention is less than 1% by mass. The metal oxide particles containing organic substances contained in an amount of 1% by mass or more are not used.

[0087] The present invention does not use organotin, and the hydrolyzate using organotin does not improve the conductivity, but it can be controlled between 10 ² and 10 ⁸ Ωcm.

[0088] As a method for producing metal oxide particles according to the present invention, a known method such as a hydrolysis method of a compound containing a hydrolyzable metal, a combustion method of metal powder, or the like can be used. Does not limit the method.

 [0089] The method for producing these metal oxide particles can be prepared, for example, by referring to the method described in the Chemical Review "Ultrafine Particle Science and Application" edited by the Chemical Society of Japan.

 [0090] Further, amorphous metal oxide particles obtained by hydrolyzing a metal alkoxide metal halide are preferred. For example, stannic oxide obtained by washing a hydrolyzate of tin tetrachloride at room temperature.

 [0091] In particular, the amorphous metal oxide particles according to the present invention include stannic oxide (hereinafter referred to as SnO).

 2) and a sol and an organic compound having an amino group dispersed in water, and those prepared through a step of adjusting the water-dispersed sol are preferably used.

 [0092] Specifically, an acid varnish niss sol (SN-1 in Examples described later) prepared with reference to Japanese Examined Patent Publication No. 35-6616 is mixed with an organic compound having an amino group and water. It was found that a sol superior in stability to the conventionally known ammonia-dispersed acid varnish sol can be produced by dispersing in the above.

 <Compound having amino group>

 The compound having an amino group is one or a combination of two or more selected from organic compounds containing N described in “The MERCK INDEXtwelfth edition” (1996) published by Merck.

Specific examples of the compound having an amino group include, for example, monoethanolamine, N, N-dimethylethanolamine (DMEA), N, N dimethylaminoethoxyethanol, N, N dimethylaminoethoxyethoxyethanol, N, N dimethylaminohexanol, N, N, N 'trimethylaminoethylethanolamine, N, N, N'-trimethylaminopropylethanolamine, N-methyl N'-hydroxychetylpiperazine (MHEP ), N 1, N, N, N, 1 terroramethylhydroxypropyl diamine (TMHPDA) Compounds having a syl group, triazinethiol triazine-tricyol, butyl aminotriazine-dithiol, hexylaminotriazine-dithiol, jetylamino triazine-dithiol, butoxyaminotriazine-dithiol, etc., imidazole 1-methyl-5 mercapto 1, Examples include 2, 3, 4 tetrazole and the like, and compounds having a mercapto group such as a mixture thereof.

 [0095] From the viewpoint of dispersibility in water and suitability for catalysts for polyurethane production, aliphatic amino alcohols are preferably used. Specific examples include C2 such as monoethanolamine, jetanolamine, and triethanolamine. Preferred compounds include C3 compounds such as monopropanolamine, dipropanolamine, and tripropanolamine, where C2 represents the number of carbon atoms constituting the substituent of the amino group. , I as a compound. In the present invention, a compound having a C50 or less is preferably used in consideration of water compatibility.

In the above embodiment, the present invention can be applied to charging members such as a blade type, a rod type, and a belt type in addition to the force roll type shown as an example of the charging roll as the charging member.

 In the above-described embodiment, an example has been described in which the charging roll contacts the photosensitive member that is the charged member to charge the photosensitive member. However, the charged member for the charging member of the present invention is not limited to the photosensitive member. For example, the present invention can also be applied to a transfer member (for example, a transfer roll) that charges a transfer material that is an object to be charged.

 Example

 Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.

<Preparation of conductive amorphous metal oxide particles>

 As described below, conductive amorphous metal oxide particles ASN-1 and ASN-2 were prepared.

 [0100] <Preparation of sol precipitates of acid stannic acid (hereinafter sometimes referred to as SnO)>: SN-1 SnO

 2 2 The sol was synthesized based on the method described in JP-B 35-6616.

[0101] SnCl · 5Η 0 (65 g) was dissolved in 2 liters of distilled water for 1 hour and boiled, and the resulting precipitate was collected.

 4 2

After it is collected, washing with water is repeated until the by-product chlorine ions can be completely removed. After confirming that the chlorine ions were gone, precipitate SN-1 was obtained. [0102] <Preparation of acid varnish sol using amino group-containing compound>: ASN-1 1 Add 10g of precipitate SN-1 obtained above and 0.1g of monoethanolamine, and heat. However, when stirred vigorously with a commercially available laboratory mixer, the clouded SN-1 becomes a clear solution. The solution thus obtained is designated as ASN-1.

 [0103] When ASN-1 was analyzed, the concentration of stannic oxide was 10.0% by mass, and the initial viscosity immediately after preparation was 4.2 mPa's. It was stable without gelling even after being left for 3 months.

 [0104] The obtained ASN-1 was dried in an oven at 100 ° C.

(Specifically, evaporation of moisture) was checked, and when mass loss ceased, it was judged that moisture was virtually eliminated.) After that, elemental analysis and X-ray diffraction measurement were performed, and amorphous Sn Confirmed to be O. Put these particles in a tablet machine and press at 4 X 10 ⁸ Pa, thickness

2

A 5 mm diameter 3 cm tablet was prepared. The volume resistivity of this tablet was measured by the two-terminal method in an environment adjusted to a temperature and humidity of 25 ° C, 50% RH, and converted to density, and the volume resistivity of ASN-1 particles was determined. 10 ³ Ω'cm.

 [0105] <Preparation of Sb-doped acid varnish niss sol>: ASN-2 Sb-doped varnish oxidized niss ultrafine powder (Ishihara Sangyo Co., Ltd.) 10g, distilled water 10g, monoethanolamine 0.1 lg was added and heated. Shina force When stirred vigorously with a commercially available lab mixer, a pale suspension solution is formed. The solution thus obtained is designated as ASN-2.

 [0106] The obtained ASN-2 was dried in an oven at 100 ° C.

 (Specifically, the evaporation of moisture was checked, and it was determined that the moisture was virtually gone when the mass loss ceased.) After that, elemental analysis and X-ray diffraction measurement were performed. It was confirmed that it was Sb-doped SnO.

 2

[0107] The particles were put into a tablet molding machine in the same manner as in ASN-1, and tablets with a thickness of 5 mm and a diameter of 3 cm were prepared. The volume resistivity of the tablet was measured, performs density conversion, it was ASN 2 was determined a volume resistivity of particles 10- ² Ω 'cm.

 <Example 1>

Component A is a slurry of 49 g of TDI-80 and carbon black (trade name: Ketjen Black EC, manufactured by Lion Akuzo) in a mortar. Component B is PPG-BM (glycerin-based polyoxy) Propylene triol: Mw = 3000: OH value 56) 100g, silicon interface Activator (L520) 1.2g, water and catalyst mixed. The catalyst used was 10 g of ASN-2.

 [0109] The A component was added while vigorously mixing the B component, and lg was poured from the mixture into the center of the mold in the shape of a charging roll and heated to 50 ° C to cause a foaming reaction. . After 60 minutes from the start of the reaction, the product was removed from the mold, aged at 80 ° C for 4 hours, and then the surface was polished flat, taking care not to expose the cell to the outside. The surface was yellowish white with a slight bluish tint.

[0110] The volume resistivity of the urethane foam layer was 10 ⁸ Ω'cm.

 [0111] The obtained charging roll is attached to the electrophotographic image forming apparatus shown in Fig. 1, and the photosensitive member is charged under the following conditions in an environment of 23 ° C / 53% RH, and 1000 predetermined images are obtained. Printed out continuously.

 Charging conditions

 Photoconductor contact pressure; 50gZcm,

 DC voltage applied to the charging roll; 600V, AC voltage; 2, OOOVp-p, frequency; 1 50Hz

 As a result, although the image was slightly stained from about 500 sheets, it was almost good. After that, remove the charging roll and sandwich it between two 10cm square plates and apply 1kg load for 24 hours. After removing the load and leaving it for 24 hours, the difference between the average of the three outer diameters of the three points of the pinched portion and the average of the three outer diameters of the pinched portion (evaluation of strain due to compression) As a result, it was 0.

 <Example 2>

 A charging roll was produced in the same manner as in Example 1, except that the amount of component A carbon black (trade name: Ketjen Black EC, manufactured by Lionaxo) was changed to 8 g.

[0113] The volume resistivity of the polyurethane foam layer was 10 ⁷ Ω'cm.

 [0114] Durability evaluation similar to that in Example 1 was performed. As a result, although the image was slightly stained from about 800 sheets, the result was almost satisfactory. Thereafter, strain was evaluated in the same manner as in Example 1. As a result, 0.05 mm of strain was observed.

<Example 3> The amount of component A carbon black of Example 1 (trade name: Ketjen Black EC, manufactured by Lionaxo Corporation) was 10 g, 10 g of ASN-1 was used as a catalyst, and 0.1 mg of triethylenediamine was the amine compound. A charging roll was produced in the same manner as in Example 1 except that was used in combination.

[0116] The volume resistivity of the polyurethane foam layer was 10 ⁷ Ω'cm.

 [0117] Durability evaluation similar to that of Example 1 was performed. As a result, although the image was slightly stained from about 800 sheets, almost satisfactory results were obtained. Thereafter, the strain was evaluated in the same manner as in Example 1. As a result, a strain of 0.06 mm was observed.

[0118] <Example 4>

 The charging roll manufactured in Example 2 was wound with lmm-thick raw rubber prepared by the following formulation and heated and vulcanized to produce a charging roll.

 Ie

 {Rubber compound}

 Epichlorohydrin rubber terpolymer 100 parts by mass

 20 parts by mass of carbon black

 Conductive tin oxide (Ishihara Sangyo) 5 parts by mass

 Quaternary ammonium salt 1 part by mass

 Zinc oxide 5 parts by mass

 Fatty acid 2 parts by mass

 The above materials were kneaded for 10 minutes in a closed mixer adjusted to 60 ° C, then 5 parts by mass of sebacic acid polyester plasticizer was added to 100 parts by mass of epichlorohydrin rubber, and the mixture was cooled to 20 ° C. The mixture was further kneaded for 20 minutes to prepare a raw material compound.

 [0119] To this compound, 100 parts by mass of raw material epichlorohydrin rubber was combined with 1 part by mass of sulfur as a vulcanizing agent, 1 part by mass of Noxeller DM as a vulcanization accelerator, and 5 parts by mass of Noxeller TS0.5. It was kneaded for 10 minutes with a two-roll mill cooled to 20 ° C. The obtained compound was molded and wound around the charging roll produced in Example 2 by an extrusion molding machine so as to form a roll, and was heated and vulcanized and then polished.

[0120] The roll obtained here was provided with a surface layer to obtain a charging roll. As a material for the surface layer, Acrylic polyol solution (active ingredient 70% by weight) 100 parts by weight Isocyanate A (IPDI, active ingredient 60% by weight) 40 parts by weight

 Isocyanate B (HDI, active ingredient 80% by mass) 30 parts by mass

 Conductive tin oxide (made by Ishihara Sangyo) 90 parts by mass

 Load control resin (CCR1) 12 parts by mass

 Methyl isobutyl ketone (MIBK) solvent 340 parts by mass

 Were mixed using a mixer to prepare a mixed solution.

 [0121] Next, the mixed solution was subjected to a dispersion treatment using a circulation type bead mill disperser to prepare a coating material for destubing. This coating material for dubbing is applied on the roll so that the film thickness becomes 10 m by the dubbing method, air-dried for 10 minutes, and then dried at 160 ° C for 1 hour in a heating type dryer. Got.

 [0122] The durability evaluation was performed in the same manner as in Example 1. As a result, the image was almost satisfactory even after 1000 sheets were printed out. Thereafter, strain was evaluated in the same manner as in Example 1. As a result, a strain of 0.02 mm was observed.

 <Example 5>

 A component is 51 g of TDI-80 and 30 g of the same carbon black as in Example 1 is mixed in a mortar. B component is PPG-BM (glycerin-based polyoxypropylene triol: Mw = 3000: OH 56) 100g, silicone surfactant (L520) lg, water and catalyst mixed. As the catalyst, 10 g of ASN-1 was used.

[0124] A component was added while mixing B component vigorously, and lg was poured from the mixture into the center of the mold in the shape of a charging roll and heated to 70 ° C to cause a foaming reaction. . After 60 minutes from the start of the reaction, the product was removed from the mold, aged at 80 ° C for 4 hours, and then the surface was polished flat, taking care not to expose the cell to the outside. The volume resistivity of the foamed urethane layer was 10 ⁷ Ω'cm.

 [0125] Durability evaluation similar to that of Example 1 was carried out. As a result, although the image was slightly stained from about 500 sheets, it was almost satisfactory. Thereafter, strain was evaluated in the same manner as in Example 1. As a result, a strain of 0.5 mm was observed.

<Comparative Example 1> During the reaction, the same procedure as in the production of the charging roll of Example 1 was conducted, except that 3.9 g of water was used and 0.1 g of triethylenediamine and 0.3 g of dibutyltin laurate were used as the catalyst instead of ASN-2. A foaming reaction was performed to produce a comparative charging roll.

[0127] When the electrophotographic image forming apparatus shown in Fig. 1 was mounted and evaluated, the evaluation was stopped because a dirty image appeared on the first print without performing a sufficient function as a charging roll.

Comparative Example 2 A charging roll was produced in the same manner except that 40 g of carbon black (trade name: Ketjen Black EC, manufactured by Lionaxo) was added to the component A of Comparative Example 1.

[0129] A durability evaluation similar to that of Example 1 was performed. As a result, abnormal noise was observed after 800 sheets had passed. Thereafter, the strain was evaluated in the same manner as in Example 1. As a result, a strain of 1.5 mm was observed.

[0130] The evaluation results are summarized in Table 1. The value of conductive particles (mass%) in the table that do not act as a catalyst was calculated by calculating the ratio in the solid content and rounding off the first decimal place.

[0131] [Table 1]

以上の実施例と比較例から、本発明の帯電ロールは、耐久試験の結果も良好で、 さらに耐久試験後のサンプルでも圧縮による歪みがつきにくいことから、長時間使用 しても変形せず、本発明の目的を達成している。

From the above examples and comparative examples, the charging roll of the present invention has good durability test results, and even after the durability test, the sample is not easily distorted by compression. The object of the present invention has been achieved.

Claims

The scope of the claims [1] An electrophotographic charging member having a polyurethane foam layer contains conductive metal oxide particles containing tin and conductive particles using carbon as a polymerization catalyst for polyurethane foam, and the conductive material. 1 to 20% by mass of conductive particles that do not act as a polymerization catalyst for the polyurethane foam, wherein the volume resistivity of the conductive metal oxide particles is less than 10 ⁷ Q ′ _C m A charging member for electrophotography, comprising:  2. The charging member for electrophotography according to claim 1, wherein an amine compound is used in combination as the polymerization catalyst. [3] The claim 1 or claim 2 wherein the particles containing 1% by mass or more and less than 20% by mass of conductive particles that do not act as a polymerization catalyst for the polyurethane foam are carbon. The charging member for electrophotography described in 1. [4] The electrophotographic charging member according to any one of [1] to [3], wherein the electrophotographic charging member is an electrophotographic charging roll. [5] An electrophotographic image forming apparatus using the electrophotographic charging member according to any one of claims 1 to 4. 6. The electrophotographic image forming apparatus according to claim 5, wherein the charging member for electrophotography is charged in contact with a member to be charged.