JPWO2007000820A1 - Charging roller - Google Patents

Abstract

An object of the present invention is to provide a charging roller capable of forming a high-quality toner image. The present invention includes a support shaft and at least one resin layer formed on the peripheral surface of the support shaft, and the resin layer has a ferret diameter number average particle size of 5 in the base resin material. The present invention relates to a charging roller in which carbon black having a particle size of ˜300 nm and primary particles of 5% or more is dispersed.

Description

  The present invention relates to a charging roller used in an image forming apparatus employing an electrophotographic process such as an electrophotographic copying machine or a printer.

  Generally, in a copying machine or printer that employs an electrophotographic process, a charger is employed to uniformly charge a photoreceptor. As charging devices, various so-called contact charging devices that generate less ozone have been proposed, and charging rollers have already been put into practical use from the viewpoint of uniform charging properties and high-speed charging properties. For example, Patent Document 1 is known as an image forming apparatus using this type of charging roller.

  The image forming apparatus described in Patent Document 1 has a configuration in which a charging roller is rotatably contacted with the outer peripheral surface of a photosensitive drum, and is forced to rotate by the rotation of the photosensitive drum or by a motor or the like. It is configured to be possible. A power source is connected to the charging roller, and a bias voltage composed of DC and AC components is applied from the power source to charge the photosensitive drum with a very small amount of ozone generated. In this Patent Document 1, a DC bias of ± 500 to 1000 V and an AC bias of 100 Hz to 10 KHz and 200 to 3500 V (pp) are introduced as a normal applied voltage in a superimposed manner.

The charged photosensitive drum is irradiated with light, and an electrostatic latent image is formed on the surface of the photosensitive drum. The toner is developed with toner, but the surface of the photosensitive drum is charged by the charger to achieve high-quality image formation. Is desired to be uniformly charged. In Patent Document 1 described above, in order to ensure uniform chargeability, a cored bar as a charging roller and a rubber layer such as chloroprene rubber, urethane rubber, silicon rubber or the like, which is a conductive elastic member provided on the outer periphery thereof, or those And a protective layer (release coating layer) made of a release fluorine-based resin or silicon resin layer having a thickness of 0.01 to 1 μm on the outermost layer is introduced.
In order to impart conductivity to these protective layers and rubber layers, it is generally widely adopted that carbon black is dispersed in the base material of each layer.
JP 2004-246120 A

  However, with the trend toward higher image quality in recent years, there is an increasing demand for images that are closer to printing, and a solid image (solid latent image) has been developed on a charging roller using carbon black that is commercially available. In some cases, uneven density is pointed out as a problem. This is due to a demand for high image quality close to printing even at a level where there is no problem as a conventional image. According to the study by the inventors, this is due to the variation in conductivity depending on the portion of the charging roller. As a result, the potential with respect to the photosensitive member varies slightly. As a result of intensive studies on this cause, it has been found that carbon black dispersed in each layer is one of the causes.

Normally, carbon black exists as secondary particles in which a plurality of basic particles are chemically and physically bonded, ie, aggregates (also referred to as structures) (see FIG. 5). This agglomerate has a complex agglomerated structure branched into irregular chains. In addition, the aggregates are Van
Since secondary agglomerates are also formed from der Waals forces, simple aggregation, adhesion, and entanglement, it is difficult to obtain a sufficient micro-dispersed structure. Moreover, it may have a complicated shape, and even when dispersed in the medium of each layer of the above-described charging roller, it was difficult for these compositions to exhibit uniform conductivity.

  In particular, silicon and urethane are mainly used as the base material for the rubber layer. However, since the affinity between these base materials and carbon black is poor, the dispersibility is poor and uniform conductivity can be achieved. Is a difficult factor.

  Furthermore, since the protective layer is subjected to mechanical contact and friction with the photoreceptor, there is a problem that the electrical characteristics change over time due to the aggregates being detached from the surface layer.

  Accordingly, an object of the present invention is to provide a charging roller capable of forming a high-quality and uniform toner image.

The above objects are achieved by the following (1) to (9).
(1) It has a support shaft and at least one resin layer formed on the peripheral surface of the support shaft, and the resin layer has a ferret diameter number average particle size of 5 to 5 in the base resin material. A charging roller characterized in that carbon black having a particle size of 300 nm and primary particles of 5% or more is dispersed.
(2) The charging roller according to (1), wherein the resin layer includes a plurality of resin layers, and the carbon black is dispersed in at least one of the plurality of resin layers.
(3) The plurality of resin layers include: a base rubber layer formed on the support shaft; and a surface layer provided on the outer peripheral side from the base rubber layer. Charging roller.
(4) The charging roller according to (3), wherein the carbon black is dispersed in the base rubber layer.
(5) The charging roller according to (3), wherein the carbon black is dispersed in the surface layer.
(6) The charging roller according to (3), wherein an intermediate layer is provided between the base rubber layer and the surface layer.
(7) The charging roller according to (6), wherein the carbon black is dispersed in the intermediate layer.
(8) The charging roller according to (1), wherein the surface of the carbon black is surface-treated with an organic compound.
(9) The charging roller according to (8), wherein the organic compound includes at least a phenol compound and / or an amine compound.

  The primary particles referred to in this application will be described. Ordinary carbon black exists in the form of aggregates, but these aggregates are in a form in which a plurality of basic particles are chemically / physically aggregated. As used herein, primary particles refer to the basic particles. However, it does not refer to the basic particles in the state of constituting the aggregate, but refers to particles that are separated from the aggregate and exist stably in the state of the basic particles. As used herein, secondary particles refer to aggregates formed by aggregation of basic particles. Here, secondary aggregates in which aggregates are aggregated are also collectively referred to as secondary particles in the present application.

  FIG. 1 is a diagram for explaining the relationship between secondary particles and basic particles. The state where the basic particles are aggregated is defined as secondary particles. FIG. 2 shows a state in which the basic particles constituting the secondary particles are separated from the secondary particles and exist stably, and the particles existing as a single basic particle are defined as primary particles.

Details will be described below.
(1) Number average particle diameter of ferret diameter The carbon black of the present invention has a number average particle diameter of ferret diameter in the range of 5 to 300 nm. Preferably, it is 10-100 nm, Most preferably, it is 10-80 nm.
By taking such a range, for example, it can be finely dispersed on the surface of the resin molding, and the surface properties can be improved.

Here, the measurement target of the number average particle diameter of the ferret diameter is primary particles and secondary particles of carbon black that exist stably. In the case of carbon black existing as an aggregate, the aggregate is an object of measurement, and the basic particles in the aggregate are not measured.
In order to control the number average particle diameter, the carbon black existing as aggregates is appropriately selected so that the basic particle diameter of the carbon black falls within the above range, or the aggregate is divided into primary particles during production. This can be achieved by changing the conditions.

The number average particle diameter of the ferret diameter can be observed with an electron microscope.
When determining the number average particle size of the ferret diameter from carbon black alone, the image is magnified 100,000 times with a scanning electron microscope (SEM), and 100 particles are appropriately selected and calculated.

  In addition, when calculating | requiring the average particle diameter of carbon black from moldings, such as resin, you may magnify | shoot and image | photograph 100 times by a transmission electron microscope (TEM), and may select and calculate 100 particles suitably. .

  In addition, the ferret diameter used by this invention represents the maximum length in arbitrary one directions of each carbon black particle in the several carbon black particle image | photographed with the said electron microscope. The maximum length means a distance between parallel lines in the case where two parallel lines that are perpendicular to the one arbitrary direction and are in contact with the outer diameter of the particle are drawn.

  For example, in FIG. 3, an arbitrary direction 201 is defined for a photograph 300 of the carbon black particles 200 taken with an electron microscope. A distance between two straight lines 202 perpendicular to the arbitrary one direction 201 and in contact with each carbon black particle 200 is a ferret diameter 203.

  The carbon black of the present invention preferably has a number average particle diameter of the ferret diameter of primary particles of 2 to 100 nm. In particular, it is 3 to 80 nm. By using carbon black in such a range, when dispersed in a resin molded product, the strength can be increased. Alternatively, the gloss of the molded product can be improved, or the finished state can be made beautiful. The method for measuring the number average particle size of the primary particles is in accordance with the method for measuring the number average particle size of the carbon black. However, the number of measured particles is 100 primary particles.

(2) Proportion of primary particles The carbon black of the present invention contains 5% or more of primary particles in the carbon black based on the number. The upper limit is 100%. These ratios vary depending on the industrial field to which they are applied. However, as the proportion of the primary particles increases, the performance of the product in the industrial field to be applied can be improved. If it is a resin molding, mechanical strength, surface glossiness, etc. will improve. Specifically, it is preferable in the order of 10% or more, 20% or more, 30% or more, 40% or more, 50% or more. The ratio of primary particles is measured in the same manner using the above-mentioned electron microscope, but the number of measured particles is calculated by counting the primary particles present in 1000 carbon black particles.

(3) Carbon black In the carbon black of the present invention, it is preferable that the surface of the carbon black particles which finally exist stably is surface-treated (including grafting) with an organic compound or the like.
The grafting rate is defined below.
The grafting rate is represented by ((Y−Z) / Y) × 100 (%), where Y is the amount of organic compound before reaction and Z is the extracted organic compound.
The grafting rate is preferably 50% or more. Dispersibility improves as the surface is uniformly treated.

  The carbon black of the present invention desirably has at least a surface grafted with an organic compound having an active free radical described later or capable of being generated. By adopting such a configuration, not only the dispersion into the medium is improved, but also the mechanical strength can be improved.

(4) Method for producing carbon black A preferred method for producing the carbon black of the present invention will be described.
A suitable production method that can be used in the present invention includes at least the following steps.
(A) a surface treatment step of treating the surface of carbon black containing secondary particles composed of an aggregate (structure) of at least basic particles with an organic compound having active free radicals or capable of being generated;
(B) A step of imparting mechanical shearing force to carbon black containing at least secondary particles to form primary particles, and grafting an organic compound into the separated particles separated from the secondary particles.

Hereinafter, (A) and (B) will be described in detail.
(A) Surface treatment step of treating the surface of carbon black containing secondary particles composed of organic compounds having active free radicals or capable of being generated and comprising at least basic particle aggregates (structures). A surface treatment of the surface of carbon black made of the above organic compound.
In this step, radicals are generated on the surface of the structure, which is the minimum aggregation unit, by heat or mechanical force, and surface treatment is performed with an organic compound that can capture the radicals. By this process, the strong agglomeration force between the carbon blacks can effectively reduce the re-aggregation sites that have been agglomerated again and prevent the primary particles of the structure and carbon black from aggregating and adhering.

  Here, the surface treatment includes treatment for adsorbing the surface with an organic compound and treatment for grafting an organic compound. In order to stabilize the particles after the primary particles are formed, it is preferable that the organic compound is grafted on the entire surface of the secondary particles in a portion other than the surface separated from the secondary particles. In order to make the primary particles stably exist after the grafting step described later, it is preferable to graft an organic compound on the carbon black surface in this step.

  As a surface treatment method, for example, the surface treatment can be performed by mixing carbon black aggregates with an organic compound having active free radicals or capable of being generated. This surface treatment preferably includes a mixing step for applying a mechanical shearing force. That is, the surface of the carbon black secondary particles is activated in the step of applying mechanical shearing force, and the organic compound itself is also activated by shearing force, so that it is likely to be in a so-called radicalized state. It is presumed that the grafting of the organic compound is easily promoted on the carbon black surface.

In the surface treatment step, an apparatus capable of applying a mechanical shearing force is preferable.
About the preferable mixing apparatus used for the surface treatment step in the present invention, polylab system mixer (manufactured by Thermo Electron), refiner, single screw extruder, twin screw extruder, planetary screw extruder, cone screw extruder, A continuous kneader, a sealed mixer, a Z-type kneader, or the like can be used.

When using the said apparatus at the time of a surface treatment process, it is preferable to set so that the mixture fullness of the mixing zone in a mixer may be 80% or more. The degree of fullness is obtained by the following formula.
Z = Q / A
Z: degree of fullness (%) Q: volume of filling (m ² ) A: void volume of mixing part (m ² )

  That is, a mechanical shearing force can be uniformly applied to the entire particles by setting a high filling state at the time of mixing. When the degree of fullness is low, the transmission of shearing force is insufficient, the activity of carbon black and organic compounds cannot be increased, and grafting may not proceed easily.

  At the time of mixing, the temperature of the mixing zone is preferably not less than the melting point of the organic compound, preferably not more than the melting point + 200 ° C., more preferably not more than the melting point + 150 ° C. When a plurality of types of organic compounds are mixed, it is preferable to set the temperature with respect to the melting point of the organic compound having the highest melting point.

  At the time of mixing, the degree of surface treatment and process of the process can be adjusted by using electromagnetic waves such as ultrasonic waves, microwaves, ultraviolet rays and infrared rays, ozone action, oxidant action, chemical action and / or mechanical shear force action in combination. It is possible to change the time. The mixing time is about 15 seconds to 120 minutes, depending on the desired degree of surface treatment. Preferably it is 1 to 100 minutes.

  The organic compound used for the surface treatment is preferably added within a range of 5 to 300 parts by weight with respect to 100 parts by weight of the carbon black to perform the surface treatment process. More preferably, it is 10-200 weight part. By adding the organic compound in such a range, the organic compound can be uniformly attached to the surface of the carbon black, and further, an amount sufficient to adhere to the separation surface generated when the secondary particles are formed. It can be. For this reason, it is possible to effectively prevent the decomposed primary particles from aggregating again, and the carbon black inherent to the organic compound that is excessively present in the finished carbon black, which is generated when added more than this addition amount The possibility of losing the characteristics of is reduced.

(B) A step of applying mechanical shearing force to carbon black containing at least secondary particles to form primary particles, and grafting an organic compound on a separation surface separated from the secondary particles. In this process, the carbon black having fewer re-aggregation sites is cleaved to form secondary particles to primary particles, and at the same time, the surface is grafted with an organic compound to form stable primary particles. That is, for example, mechanical shear force is applied to the carbon black surface-treated with the organic compound, and the organic compound is grafted to the agglomerated part of the basic particles while cracking the part, thereby suppressing the reaggregation of the carbon black. I will do it. By applying mechanical shearing force continuously to the carbon black, the cracked part is expanded, and the organic compound is grafted to the separation surface generated by the cleavage while making primary particles, and finally separated as primary particles Then, it is the process of making it exist as a stable next particle by making it the state which does not exist the active part which can be aggregated. In this case, since the same mechanical shearing force is applied to the added organic compound, the organic compound itself is also activated by the mechanical shearing force, and grafting is promoted.

  As used herein, “carbon black grafted with an organic compound” refers to carbon black in which an organic compound portion is grafted to a carbon black portion. Furthermore, “grafting” as used herein is carbon as defined by Jean-Baptiste Donnet et al. In his book “Carbon Black” (published on May 1, 1978, Kodansha). An irreversible addition of an organic compound to a substrate such as black.

  The grafting step is a step of grafting an organic compound having an active free radical or capable of being generated at least in a crack portion, but grafting may occur simultaneously in addition to the crack portion. Moreover, you may perform simultaneously or as a separate process during said surface treatment process progress.

  As means for causing the above cracks, various forms such as irradiation of electromagnetic waves such as ultrasonic waves, microwaves, ultraviolet rays, and infrared rays, ozone action, action of an oxidizing agent, chemical action, mechanical shear force action can be taken. .

In the present invention, it is preferable to cause a crack by applying at least a mechanical shearing force. It is desirable to place the carbon black (structure) surface-treated with an organic compound in a place where a mechanical shearing force acts to adjust the surface-treated carbon black from the structure to primary particles. When applying this mechanical shearing force, other means for causing cracks as described above may be used in combination.
The mechanical shearing force here is preferably a shearing force similar to the mechanical shearing force in the surface treatment step described above.

  As described above, the action of the mechanical shearing force can not only make carbon black fine particles from aggregates into primary particles, but also generate active free radicals by breaking the chains inside the carbon black. Organic compounds having or capable of generating free radicals used in the present invention are organic compounds that have active free radicals or can be generated by cleavage under the action of, for example, a mechanical shear force field including. When the active free radicals cannot be sufficiently formed only under the action of mechanical shearing force, under irradiation of electromagnetic waves such as ultrasonic waves, microwaves, ultraviolet rays, infrared rays, under the action of ozone, or under the action of an oxidizing agent, The number of active free radicals can be complemented.

  Polylab system mixer (manufactured by Thermo Electron), refiner, single screw extruder, twin screw extruder, planetary screw extruder, cone screw extruder, continuous kneader, sealed mixer Z-type kneaders can be used. The conditions for applying the mechanical shearing force are preferably the same as those for the surface treatment described above from the viewpoint of effectively applying the mechanical shearing force. In addition, by using these devices, mechanical energy can be effectively and continuously applied to the entire particles uniformly, so that grafting can be performed efficiently and uniformly. preferable.

In the surface treatment step and the grafting step, the organic compound to be added may be added gradually or intermittently so that the organic compound becomes a predetermined amount, or may be added in advance at the start of the surface step. A fixed amount may be added and executed until the grafting step.
The organic compound used in the grafting step as the material to be grafted with the organic compound used in the surface treatment step as the surface treatment material may be the same or different.

  The grafting step described above is desirably performed under conditions that are equal to or higher than the melting point of the organic compound used. The upper limit of the temperature condition is particularly preferably within the melting point of the organic compound + 200 ° C., more preferably within the melting point + 150 ° C., from the viewpoint of promoting the graft reaction and the splitting of the primary particles. When a plurality of types of organic compounds are mixed, it is preferable to set the temperature with respect to the melting point of the organic compound having the highest melting point.

  The above-described mechanical shearing force application time depends on the amount and scale of the sample, but in order to sufficiently perform the process, it is preferably 1 minute or more and 100 minutes or less from the viewpoint of improving the uniformity of the reaction. .

  In the production method of the present invention described above, it is preferable to apply mechanical shearing force by mixing carbon black and an organic compound described later without using a solvent. Since a shearing force is applied as a reaction at a temperature higher than the melting temperature of the organic compound, the organic compound becomes liquid, so that it can be uniformly adapted to the solid carbon black surface and the reaction can be effectively advanced. When a solvent is used, the uniformity is improved, but since the transmission of energy when applying mechanical shearing force is reduced, the level of activation is reduced and grafting is effectively advanced. It is estimated that it will be difficult to do.

  The method for adjusting the amount of primary particles is not particularly limited, but it can be adjusted by changing the conditions for applying the mechanical shearing force. More specifically, the degree of mixture fullness in the mixing zone in the mixer for applying the shearing force is adjusted to be 80% or more, and the mechanical shearing force can be changed by changing the degree of filling. The abundance ratio of the particles can be adjusted. Furthermore, it can also be adjusted by changing the stirring torque at the time of mixing, and as a method for adjusting this torque, it can be controlled by the stirring rotation speed and the stirring temperature in addition to the above-mentioned fullness. More specifically, when the temperature at the time of mixing is lowered, the viscosity of the molten organic compound is increased, so that the torque is increased and the resultant shear force is increased. That is, the abundance of primary particles increases.

2) Carbon black as a starting material Usable carbon black can be any commercially available carbon black such as furnace black, channel black, acetylene black, lamp black, etc., but carbon having an aggregate structure Black. The aggregate structure means a carbon black which is formed by agglomeration of primary particles as basic particles and has a structure structure, and is formed of aggregates of so-called primary particles and formed into secondary particles. In addition, in order to facilitate the surface treatment and graft reaction of organic compounds on carbon black, sufficient oxygen-containing functional groups such as carboxyl groups, quinone groups, phenol groups and lactone groups on the surface of carbon black, and active layer surface periphery. It is desirable that many hydrogen atoms exist. Therefore, the carbon black used in the present invention preferably has an oxygen content of 0.1% or more and a hydrogen content of 0.2% or more. In particular, the oxygen content is 10% or less and the hydrogen content is 1% or less. Here, the oxygen content and the hydrogen content are respectively obtained by dividing the number of oxygen elements or the number of hydrogen elements by the total number of elements (sum of carbon, oxygen, and hydrogen elements).
By selecting such a range, the surface treatment or graft reaction of the organic compound onto the carbon black can be facilitated.

  Further, by selecting the above range, an organic compound having a free radical or capable of being generated can be surely grafted, and the reaggregation preventing effect is enhanced. When the oxygen content and hydrogen content on the carbon black surface are below the above ranges, gas phase oxidation such as heated air oxidation or ozone oxidation, or nitric acid, hydrogen peroxide, potassium permanganate, sodium hypochlorite, The oxygen content and hydrogen content of carbon black may be increased by liquid phase oxidation treatment with bromine water or the like.

3) Organic compound The organic compound used for surface treatment of carbon black in the surface treatment step or for grafting to carbon black in the grafting step is an organic compound having a free radical or capable of being generated. is there.

  In the organic compound capable of generating a free radical, the conditions for generating the free radical are not particularly limited, but the organic compound used in the present invention has a free radical during the grafting process. It is necessary to be in a state. The organic compound is preferably a compound capable of generating free radicals by electron transfer, a compound capable of generating free radicals by thermal decomposition, or a compound capable of generating free radicals as a result of the structure of the compound being cleaved by shearing force or the like. .

  About the organic compound which is equipped with the free radical used by this invention, or can be produced | generated, it is preferable that the molecular weight is 50 or more, and it is preferable that it is 1500 or less as an upper limit. By adopting an organic compound having such a molecular weight range, it is possible to obtain a carbon black whose surface is substituted with an organic compound having a somewhat large molecular weight, and to suppress reaggregation of the formed primary particles. In addition, by making the molecular weight 1500 or less, the characteristics possessed by the carbon black itself are sufficiently obtained without excessive surface modification and without excessively exhibiting the characteristics of the organic compound grafted on the surface. Can be demonstrated.

  The organic compounds used in the surface treatment step and the grafting step may be the same or different, and plural types of organic compounds may be added to each step. In order to simplify the control of the reaction temperature and other conditions, it is desirable that the organic compound used in the surface treatment step and the grafting step be the same.

  Examples of the organic compound include organic compounds capable of capturing free radicals on the carbon black surface of phenolic compounds, amine compounds, phosphate ester compounds, and thioether compounds.

  As these organic compounds, so-called antioxidants and light stabilizers are preferable. More preferred are hindered phenols and hindered amines. Moreover, antioxidants of phosphate ester compounds, thiol compounds, and thioether compounds can also be used. A plurality of these organic compounds may be used in combination. Depending on the combination, various characteristics of the surface treatment can be exhibited.

  Further, these organic compounds preferably do not have an isocyanate group in order to reliably control the reaction. That is, when an organic compound having excessive reactivity is used, a uniform grafting reaction is difficult to be formed, and it may be necessary to use a large amount of reaction time and amount of organic compound. Although the reason for this is not clear, when an organic compound having a high reactivity as described above is used, the reaction proceeds in addition to the surface active sites, and is formed by the mechanical shear force that is the original purpose. It is presumed that the reaction to the active site becomes insufficient.

  Specific examples of the organic compound are shown below.

（有機化合物２）

（有機化合物３）

（有機化合物４）

（有機化合物５）

（有機化合物６）

（有機化合物７）

（有機化合物８）

（有機化合物９）

（有機化合物１０）

（有機化合物１１）

（有機化合物１２）

（有機化合物１３）

（有機化合物１４）

（有機化合物１５）

（有機化合物１６）

（有機化合物１７）

（有機化合物１８）

（有機化合物１９）

（有機化合物２０）

（有機化合物２１）

（有機化合物２２）

（有機化合物２３）

（有機化合物２４）

（有機化合物２５）

（有機化合物２６）

（有機化合物２７）

（有機化合物２８）

（有機化合物２９）

（有機化合物３０）

（有機化合物３１）

（有機化合物３２）

（有機化合物３３）

（有機化合物３４）

（有機化合物３５）

（有機化合物３６）

（有機化合物３７）

（有機化合物３８）

（有機化合物３９）

（有機化合物４０）

（有機化合物４１）

（有機化合物４２）

（有機化合物４３）

（有機化合物４４）

（有機化合物４５）

（有機化合物４６）

（有機化合物４７）

（有機化合物４８）

（有機化合物４９）

（有機化合物５０）

（有機化合物５１）

（有機化合物５２）

（有機化合物５３）

（有機化合物５４）

（有機化合物５５）

（有機化合物５６）

（有機化合物５７）

（有機化合物５８）

（有機化合物５９）

（有機化合物６０）

（有機化合物６１）

（有機化合物６２）

（有機化合物６３）

（有機化合物６４）

（有機化合物６５）

（有機化合物６６）

（有機化合物６７）

（有機化合物６８）

（有機化合物６９）

（有機化合物７０）

（有機化合物７１）

（有機化合物７２）

（有機化合物７３）

（有機化合物７４）

（有機化合物７５）

（有機化合物７６）

（有機化合物７７）

（有機化合物７８）

（有機化合物７９）

（有機化合物８０）

（有機化合物８１）

（有機化合物８２）

（有機化合物８３）

（有機化合物８４）

（有機化合物８５）

（有機化合物８６）

（有機化合物８７）

（有機化合物８８）

アミン系化合物
（有機化合物８９〜１４４）
（有機化合物８９）

（有機化合物９０）

（有機化合物９１）

（有機化合物９２）

（有機化合物９３）

（有機化合物９４）

（有機化合物９５）

（有機化合物９６）

（有機化合物９７）

（有機化合物９８）

（有機化合物９９）

（有機化合物１００）

（有機化合物１０１）

（有機化合物１０２）

（有機化合物１０３）

（有機化合物１０４）

（有機化合物１０５）

（有機化合物１０６）

（有機化合物１０７）

（有機化合物１０８）

（有機化合物１０９）

（有機化合物１１０）

（有機化合物１１１）

（有機化合物１１２）

（有機化合物１１３）

（有機化合物１１４）

（有機化合物１１５）

（有機化合物１１６）

（有機化合物１１７）

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（有機化合物１２０）

（有機化合物１２１）

（有機化合物１２２）

（有機化合物１２３）

（有機化合物１２４）

（有機化合物１２５）

（有機化合物１２６）

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（有機化合物１３０）

（有機化合物１３１）

（有機化合物１３２）

（有機化合物１３３）

（有機化合物１３４）

（有機化合物１３５）

（有機化合物１３６）

（有機化合物１３７）

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（有機化合物１４０）

（有機化合物１４１）

（有機化合物１４２）

（有機化合物１４３）

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チオール系及びチオエーテル系化合物
（有機化合物１４５〜１５３）
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（有機化合物１４８）

（有機化合物１４９）

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リン酸エステル系化合物
（有機化合物１５４〜１６０）
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フェノール系有機化合物
（有機化合物１６１）

Phenolic compounds (organic compounds 1 to 88)
(Organic compound 1)

(Organic compound 2)

(Organic compound 3)

(Organic compound 4)

(Organic compound 5)

(Organic compound 6)

(Organic compound 7)

(Organic compound 8)

(Organic compound 9)

(Organic compound 10)

(Organic compound 11)

(Organic Compound 12)

(Organic Compound 13)

(Organic Compound 14)

(Organic Compound 15)

(Organic Compound 16)

(Organic compound 17)

(Organic compound 18)

(Organic Compound 19)

(Organic compound 20)

(Organic compound 21)

(Organic compound 22)

(Organic Compound 23)

(Organic Compound 24)

(Organic compound 25)

(Organic compound 26)

(Organic Compound 27)

(Organic compound 28)

(Organic Compound 29)

(Organic Compound 30)

(Organic compound 31)

(Organic compound 32)

(Organic compound 33)

(Organic Compound 34)

(Organic compound 35)

(Organic Compound 36)

(Organic Compound 37)

(Organic compound 38)

(Organic Compound 39)

(Organic compound 40)

(Organic compound 41)

(Organic Compound 42)

(Organic compound 43)

(Organic compound 44)

(Organic compound 45)

(Organic compound 46)

(Organic Compound 47)

(Organic compound 48)

(Organic compound 49)

(Organic compound 50)

(Organic Compound 51)

(Organic Compound 52)

(Organic Compound 53)

(Organic compound 54)

(Organic compound 55)

(Organic compound 56)

(Organic Compound 57)

(Organic compound 58)

(Organic compound 59)

(Organic compound 60)

(Organic Compound 61)

(Organic Compound 62)

(Organic compound 63)

(Organic compound 64)

(Organic compound 65)

(Organic compound 66)

(Organic compound 67)

(Organic Compound 68)

(Organic Compound 69)

(Organic compound 70)

(Organic compound 71)

(Organic Compound 72)

(Organic Compound 73)

(Organic compound 74)

(Organic compound 75)

(Organic compound 76)

(Organic compound 77)

(Organic Compound 78)

(Organic compound 79)

(Organic compound 80)

(Organic Compound 81)

(Organic compound 82)

(Organic compound 83)

(Organic compound 84)

(Organic compound 85)

(Organic compound 86)

(Organic compound 87)

(Organic Compound 88)

Amine compounds (organic compounds 89-144)
(Organic compound 89)

(Organic compound 90)

(Organic compound 91)

(Organic compound 92)

(Organic compound 93)

(Organic compound 94)

(Organic compound 95)

(Organic compound 96)

(Organic compound 97)

(Organic Compound 98)

(Organic compound 99)

(Organic compound 100)

(Organic compound 101)

(Organic compound 102)

(Organic compound 103)

(Organic compound 104)

(Organic compound 105)

(Organic compound 106)

(Organic compound 107)

(Organic compound 108)

(Organic compound 109)

(Organic compound 110)

(Organic compound 111)

(Organic compound 112)

(Organic compound 113)

(Organic compound 114)

(Organic compound 115)

(Organic compound 116)

(Organic compound 117)

(Organic compound 118)

(Organic Compound 119)

(Organic compound 120)

(Organic Compound 121)

(Organic compound 122)

(Organic compound 123)

(Organic compound 124)

(Organic compound 125)

(Organic compound 126)

(Organic compound 127)

(Organic Compound 128)

(Organic Compound 129)

(Organic Compound 130)

(Organic Compound 131)

(Organic Compound 132)

(Organic Compound 133)

(Organic Compound 134)

(Organic compound 135)

(Organic compound 136)

(Organic compound 137)

(Organic compound 138)

(Organic Compound 139)

(Organic Compound 140)

(Organic compound 141)

(Organic Compound 142)

(Organic Compound 143)

(Organic Compound 144)

Thiol-based and thioether-based compounds (organic compounds 145 to 153)
(Organic compound 145)

(Organic compound 146)

(Organic compound 147)

(Organic compound 148)

(Organic Compound 149)

(Organic Compound 150)

(Organic compound 151)

(Organic Compound 152)

(Organic compound 153)

Phosphate ester compounds (organic compounds 154-160)
(Organic compound 154)

(Organic compound 155)

(Organic compound 156)

(Organic compound 157)

(Organic compound 158)

(Organic compound 159)

(Organic compound 160)

Phenolic organic compounds (organic compound 161)

Next, embodiments of the present invention will be described in detail.
(Charging roller configuration)
First, the basic configuration of the contact charging roller of the present invention will be described with reference to FIG. The charging roller 100 according to this embodiment has a configuration in which the outer periphery of a cored bar 101 is covered with a layer made of a conductive elastic member 102 (also simply referred to as a conductive elastic layer or a conductive rubber layer). Is brought into contact with the photosensitive member (image carrier), and a voltage is applied to the charging roller to charge the photosensitive member (image carrier).
Such a charging roller system may be either a DC charging system in which a DC voltage is applied to the roller or an induction charging system in which an AC voltage is applied to the roller.

  In addition, the frequency f of the voltage applied by the induction charging method is arbitrary, but an appropriate frequency is selected according to the relative speed of the conductive elastic roller and the image carrier member in order to prevent strobing, that is, a stripe pattern. Can be selected. The relative speed can be determined by the size of the contact area between the conductive elastic roller and the image carrier.

  Examples of rubber compositions that can be used for the conductive rubber layer include natural rubber, ethylene propylene diene methylene rubber (EPDM), styrene-butadiene rubber (SBR), silicone rubber, urethane rubber, epichlorohydrin rubber, and isoprene rubber (IR). , Butadiene rubber (BR), nitrile-butadiene rubber (NBR), chloroprene rubber (CR) and the like. These rubber | gum can be used individually or as 2 or more types of mixed rubbers.

  In order to impart conductivity, a conductivity imparting agent is blended with these rubber compositions. As a suitable conductivity imparting agent, known carbon black (furnace carbon black or ketien black), carbon having a ferret diameter number average particle diameter of 5 to 300 nm and primary particles of 5% or more on the number basis. Examples thereof include metal powders such as black and tin oxide. The usage-amount of an electroconductivity imparting agent is about 5 to about 50 mass parts with respect to the rubber composition whole quantity.

In addition to the rubber base material, the foaming agent, and the conductivity imparting agent, the rubber composition may be blended with a rubber chemical and a rubber additive as necessary to obtain a conductive foamed rubber composition. Rubber chemicals and rubber additives include vulcanizing agents such as sulfur and peroxide, vulcanization accelerators such as zinc white and stearic acid, vulcanized sulfenamide, thyrium, thiazole and granidine Accelerators, amine-based, phenol-based, sulfur-based, phosphorus-based anti-aging agents, antioxidants, UV absorbers, ozone degradation inhibitors, tackifiers, etc. can be used, and various reinforcing agents In addition, an inorganic filler such as a friction coefficient modifier, silica, talc, clay and the like can be arbitrarily selected and used. These conductive rubber layers preferably have a DC volume resistivity in the range of 10 ³ to 10 ⁷ Ωcm.

Furthermore, a releasable coating layer 103 may be provided outside the conductive elastic layer 102 for the purpose of preventing the toner remaining on the surface of the photoreceptor from adhering to the charging member. The covering layer 103 also prevents oil from seeping out of the elastic layer 102 and cancels uneven resistance of the elastic layer 102 to equalize resistance, and protect the surface of the charging roller 100. It performs functions such as adjusting the hardness. The covering layer may be any layer as long as it satisfies the above physical properties, and may be a single layer or a plurality of layers. Examples of the material include resins such as hydrin rubber, urethane rubber, nylon, polyvinylidene fluoride, and polyvinylidene chloride. The thickness of the covering layer 103 is preferably 100 to 1000 μm, and the resistance value is preferably 10 ⁵ to 10 ⁹ Ω · cm. Moreover, it is preferable that resistance value becomes large as it approaches the surface layer. As a method for adjusting the resistance, known coating materials such as carbon black, carbon black having a ferret diameter number average particle diameter of 5 to 300 nm and primary particles of 5% or more based on the number, metal and metal oxide, etc. And the like.

  Moreover, although a core metal is not specifically limited, it is a conductive thing with a diameter of about 1 mm-10 mm, and metals, such as iron, copper, stainless steel, aluminum, nickel, can be used as a material. Further, for the purpose of preventing rust and improving scratch resistance, the surface may be plated to such an extent that the conductivity is not impaired.

Specific examples and comparative examples will be described below.
(Manufacture of carbon black)
(Carbon black # 1)
50 parts by weight of organic compound 48 (molecular weight = 741, melting point = 125 ° C.) with respect to 100 parts by weight of carbon black (N220, manufactured by Mitsubishi Chemical Corporation: Ferre diameter number average particle diameter = 210 nm) and the same carbon black Was added to the twin screw extruder. This biaxial extruder is a machine that mixes with two screws, and used PCM-30 (manufactured by Ikegai Seisakusho). It was not modified so that it could be kneaded in a continuous manner, but was modified so that the outlet could be sealed and stirred with two screws. Both were put into the apparatus so that the degree of fullness was 94%, and then stirred while being heated to a first temperature (Tp1) of 160 ° C. (melting point + 35 ° C.).

  Under the stirring conditions, the first stirring speed (Sv1) was set at 10 rotations as the first processing time (T1) with the screw rotation set at 30 rotations per minute, and the stirring processing was performed. Sampling was performed after the stirring treatment, and when the grafting state was confirmed by Soxhlet extraction, it was found that the grafting rate was about 30%. That is, it was confirmed that grafting was progressing on the carbon black surface.

  Next, as a stirring condition of the mixing apparatus, the second stirring speed (Sv2) is set to 50 revolutions per minute at the number of rotations of the screw, the second temperature (Tp2) is set to 180 ° C. (melting point + 55 ° C.), and the mechanical shearing force is higher. The conditions were changed and the second treatment time (T2) was set to 60 minutes. Thereafter, it was cooled and the treated carbon black was taken out. The organic compound was grafted on the surface of the curve black at a grafting rate of 91%. In addition, 65% by number of primary particles were present. The number average particle diameter of the ferret diameter of carbon black was 42 nm. This carbon black is referred to as “carbon black # 1”.

(Carbon black # 2 to # 4)
Carbon black # 2, # 3, and # 4 were obtained in the same manner except that the production conditions for carbon black # 1 were as shown in Tables 1 and 2.

(Carbon black # 5)
Carrying out 100 parts by weight of carbon black (N220, manufactured by Mitsubishi Chemical Corporation) and 80 parts by weight of an organic compound 47 (molecular weight = 784, melting point = 221 ° C.) with respect to the carbon black so that the filling degree is 94%. The batch type twin screw extruder used in Example 1 was charged. Subsequently, the mixture was stirred while being heated to 240 ° C. (melting point + 19 ° C.) (Tp1). Stirring was performed at a stirring speed (Sv1) of 35 rotations per minute by screw rotation and stirring for 15 minutes (T1). Sampling was performed after the stirring treatment, and when the grafting state was confirmed by Soxhlet extraction, it was found that the grafting rate was about 32%. That is, it was confirmed that the grafting was progressing on the surface. Next, as stirring conditions, the stirring speed (Sv2) is set to 55 revolutions per minute at the number of rotations of the screw, the heating temperature (second temperature Tp2) is set to 270 ° C. (melting point + 49 ° C.), and the mechanical shearing force is higher. It changed and processed for 70 minutes as processing time (T2). Thereafter, it was cooled and the treated carbon black was taken out. The organic compound was grafted on the surface at a grafting rate of 72%. Further, 53% by number of primary particles were present. The number average particle diameter of the ferret diameter was 48 nm. This carbon black is referred to as “carbon black # 5”.

(Carbon black # 6 to # 9)
Carbon black # 6 to # 9 were obtained in the same manner except that the production conditions for carbon black # 1 were as shown in Tables 1 and 2.

(Carbon black # 10)
In carbon black # 1, instead of carbon black (N220, manufactured by Mitsubishi Chemical Corporation), Raven 1035 (manufactured by Columbia Chemical Industry Co., Ltd.) was used, and the other conditions were the same as shown in Tables 1 and 2. Carbon black # 10 was obtained.

(Carbon black # 11)
In carbon black # 5, instead of carbon black (N220, manufactured by Mitsubishi Chemical Corporation), Raven 1035 (manufactured by Columbia Chemical Industry Co., Ltd.) was used, and the other conditions were the same as shown in Tables 1 and 2. Carbon black # 11 was obtained.

(Carbon black # 12 to # 13)
Carbon black # 12 to # 13 were obtained in the same manner except that the production conditions for carbon black # 1 were as shown in Tables 1 and 2.

(Carbon black # 14)
Carbon black (N220, manufactured by Mitsubishi Chemical Corporation) that has not been subjected to the surface treatment and grafting process is referred to as carbon black # 14.

(Carbon black # 15)
In carbon black # 1, the sample was taken out after 1 minute of the first treatment time (T1). This is called carbon black # 15.

(Carbon black # 16)
In carbon black # 1, the organic compound was treated in the same manner except that it was changed to stearic acid (molecular weight = 284, melting point = 70 ° C.) (comparative compound 1) in which free radicals were not generated. This is called carbon black # 16.
Table 3 shows the number average particle diameter of the ferret diameter of carbon black and the number ratio of primary particles in each of the carbon blacks # 1 to # 16.

(Carbon black # 17)
Carbon black # 16 was treated in the same manner except that the carbon black was changed to carbon black having a ferret diameter number average particle diameter of 500 μm.
155 parts by mass of the treated carbon black was mixed with 100 parts by mass of carbon black 1 to prepare carbon black having a ferret diameter number average diameter of 320 μm and a primary particle number ratio of 26%. This is called carbon black # 17.
Table 3 shows the number average particle size of the ferret diameter of carbon black and the number ratio of primary particles in each of carbon blacks # 1 to # 17.

Example 1
First, a charging roller manufactured through the following steps was prepared as the charging roller of Example 1. First, a metal core made of stainless steel having a diameter of 4.0 mm was placed in a mold having a cylindrical molding space with a diameter of 6 mm, and the mold was filled with a conductive elastic layer forming material. As the conductive elastic layer forming material, 100 parts by mass of styrene-butadiene rubber (SBR), 30 parts by mass of carbon black # 1 as a conductivity imparting agent, and 0.5 parts by mass of sulfur as a vulcanizing agent are added. The compounded rubber material was kneaded using a twin screw extruder (product name: PCM-30, manufactured by Ikegai Co., Ltd.). This conductive elastic layer forming material was filled in a mold, then vulcanized and taken out of the mold to form a layer having a layer thickness of 1.0 mm on the cored bar. The obtained base rubber layer had a volume resistance value of 1 × 10 ⁵ Ω · cm.

On the other hand, the releasable coating layer 103 was installed as follows. To 100 parts by mass of epichlorohydrin rubber, 30 parts by mass of titanium oxide for controlling conductivity is added, dispersed using a ball mill, and methyl ethyl ketone (MEK) as an organic solvent is added and mixed and stirred. Then, a coating liquid for forming a releasable coating layer was prepared, and this coating liquid was applied to the outer peripheral surface of the conductive elastic layer by a dipping method to form a layer having a layer thickness of 700 μm. The obtained releasable coating layer 113 had a volume resistance value of 1 × 10 ⁶ Ω · cm.

(Examples 2 to 12, Comparative Examples 1 to 5)
In each of the charging rollers of Examples 2 to 12 and Comparative Examples 1 to 5, carbon black # 1 which is a conductivity imparting agent used for the conductive elastic body layer of the charging roller of Example 1 is carbon black # 2 to ##. Except for the change to 17, the same production method as in Example 1 was adopted. Carbon blacks # 2 to # 12 are Examples 2 to 12, and carbon blacks # 13 to # 17 are Comparative Examples 1 to 5.

(Evaluation)
Each of the charging rollers of Examples 1 to 12 and Comparative Examples 1 and 2 obtained as described above is applied to a printer magiccolor 2540 manufactured by Konica Minolta Business Technologies, Inc., and a solid image is printed on thin plain paper having a weight of 45 g. did. The charging roller core was charged by applying a DC voltage of 500 (V).
And the transmission density light quantity was measured about arbitrary 10 points | pieces using the Sakura densitometer (made by Konica Corporation) for the printing result. The results are shown in Table 4.

  As understood from Table 4, when the image formation is performed using the charging roller of the embodiment according to the present invention, the density unevenness in the solid image is larger than when the image formation is performed using the charging roller of the comparative example. The image quality has been confirmed to be improved.

It is a figure explaining the relationship between a secondary particle and a basic particle. It is a figure which shows the state which the basic particle which comprises a secondary particle is isolate | separated from the secondary particle, and exists stably. It is a figure explaining the diameter of a ferret used by the present invention. It is sectional drawing which shows the structure of the charging roller of embodiment of this invention. It is a figure which shows the aggregate (structure) of the conventional carbon black.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100: Developing roller 101: Core metal 102: Conductive elastic layer 103: Releasable coating layer

Claims (9)

A support shaft;
And at least one resin layer formed on the peripheral surface of the support shaft,
The resin layer is characterized in that carbon black having a ferret diameter number average particle diameter of 5 to 300 nm and primary particles of 5% or more on a number basis is dispersed in the base resin material. roller.   The charging roller according to claim 1, wherein the resin layer includes a plurality of resin layers, and the carbon black is dispersed in at least one of the plurality of resin layers.   The charging roller according to claim 2, wherein the plurality of resin layers include a base rubber layer formed on the support shaft and a surface layer provided on an outer peripheral side of the base rubber layer.   4. The charging roller according to claim 3, wherein the carbon black is dispersed in the base rubber layer.   4. The charging roller according to claim 3, wherein the carbon black is dispersed in the surface layer.   The charging roller according to claim 3, wherein an intermediate layer is provided between the base rubber layer and the surface layer.   The charging roller according to claim 6, wherein the carbon black is dispersed in the intermediate layer.   The charging roller according to claim 1, wherein the surface of the carbon black is surface-treated with an organic compound. The charging roller according to claim 8, wherein the organic compound includes at least a phenol compound and / or an amine compound.

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