JP2008116607A - Toner supply roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner supply roller and a developing device, in which toner is sufficiently and stably supplied onto a toner carrier and supplied toner is sufficiently and stably electrified. <P>SOLUTION: The toner supply roller is configured to include a core material, a foamed elastic body layer 3 which is formed on the circumferential surface of the core material and has a cell 4 opened in the outermost surface and toner electrifying fine particles 5 which are exposed at least parts thereof and fixed to the outermost surface 6 of the foamed elastic body layer 3 and the surface 7 of the cell 4 opened in the outermost surface, and satisfies the relation of Wt<SB>1</SB>-Wp≥0.5(eV), where Wp is the work function of the toner electrifying fine particles and Wt<SB>1</SB>is the work function of negatively electrified toner. The developing device is provided with the toner supply roller. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a toner supply roller used in a developing device that develops and visualizes an electrostatic latent image formed on an electrostatic latent image carrier in an image forming apparatus such as a copying machine, a printer, and a facsimile machine, And a developing device including the toner supply roller.

  In an image forming apparatus such as a copying machine, a printer, or a facsimile, an electrostatic latent image formed on an electrostatic latent image carrier such as an electrophotographic photosensitive member or an electrostatic recording dielectric is developed into a visible toner image. A developing device is used. In such a developing device, it is known that a one-component developing device using a one-component developer that does not use a carrier for charging a toner is advantageous in terms of full color and simplification of the device.

  As a one-component developing device, for example, one having the following structure is known. In other words, a toner regulating member is disposed in pressure contact with a roller-type toner carrying body (developing roller) arranged close to or in contact with the electrostatic latent image carrying body, and in the upstream direction of the toner regulating member in the direction of surface movement of the toner carrying body In addition, a toner supply roller is arranged. The toner is supplied onto the toner carrier by the toner supply roller, and the supplied toner is made into a toner thin layer having a predetermined layer thickness by the toner regulating member and is frictionally charged to be supplied to the developing area facing the electrostatic latent image carrier. The electrostatic latent image is developed under application of a developing bias to the toner carrier. The toner on the toner carrier that has not been developed is collected by the toner supply roller.

  In such a one-component developing device, if the toner supply from the toner supply roller to the toner carrier is not smoothly performed, a sufficient amount of the toner thin layer is not formed on the toner carrier, so that the image density is lowered. . For this reason, many techniques for improving and stabilizing the toner supply function have been reported for the toner supply roller.

  For example, in order to stabilize toner supply performance, a plurality of ridges extending in the axial direction are formed at a predetermined pitch on the surface of the foamed elastic layer that is the toner supply roller, and the surface of the foamed elastic layer, and the surface A technique is disclosed in which the surface of the cell opening is formed into a rough surface to improve the slidability between the toner supply roller and a contact member such as a developing roller (Patent Document 1). As a method for forming the rough surface, it is described that a binder containing silicone powder is sprayed.

  In addition, for example, a technique is disclosed in which an additive such as silica protrudes from the cell surface of the foamed elastic layer as a toner supply roller to increase the specific surface area inside the cell, thereby increasing the toner supply capability (Patent Document). 2). As a method for producing the toner supply roller, it is described that a foaming agent and an additive (silica or the like) are added to an elastomer, kneaded, heated and molded, and then the surface is machined.

  However, in these technologies, even if the toner supply property can be ensured, the toner regulating member does not sufficiently charge the toner thin layer. The production of reversely charged reversely charged toner has become a problem. When defectively charged toner or reversely charged toner is generated, an image defect called “fogging” in which the toner is transferred to a region where a toner visible image should not be formed and developed. Therefore, if the pressure contact pressure of the toner regulating member with respect to the toner carrier is increased in order to increase the frictional charging effect, the toner is cracked or the external additive is embedded, and the generation of defectively charged toner or reversely charged toner is remarkable.

In view of this, a technology has been reported in which a developing device using negatively chargeable toner is provided with a member that contacts the toner supply roller so that the work function of the contact member is smaller than that of the toner (Patent Document 3). ). Accordingly, the toner is held on the toner supply roller, and the held toner comes into contact with the corresponding contact member, thereby increasing the negative charge amount of the toner and preventing the positively charged toner from increasing. Is.
JP 2003-287951 A JP 2002-70839 A JP 2005-173013 A

  However, in the developing device having such a configuration, the toner is sufficiently charged by frictional charging. However, since the contact between the toner and the contact member is repeated, the stress on the toner increases as compared with the conventional case. . Therefore, the progress of toner deterioration such as toner cracking and embedding of external additives is accelerated, resulting in defective charging or reverse charging of the toner and fogging. Moreover, providing a new member is difficult in terms of cost.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a toner supply roller and a developing device that can improve toner supply performance and toner charge imparting performance over a long period of time. That is, an object of the present invention is to provide a toner supply roller and a developing device in which sufficient and stable toner supply is performed on a toner carrier, and the supplied toner is sufficiently and stably charged. And

The present invention
A toner supply roller for supplying negatively chargeable toner to a toner carrier for conveying toner to the electrostatic latent image carrier;
A core material, a foamed elastic layer formed on the outer peripheral surface of the core material and having cells opened at the outermost surface, and at least the outermost surface of the foamed elastic layer and the surface of the cell opened at the outermost surface A portion of the toner charging fine particles that are exposed and fixed;
A toner supply roller, wherein the work function (Wp) of the toner charging fine particles and the work function (Wt ₁ ) of the negatively chargeable toner satisfy a relationship of Wt ₁ −Wp ≧ 0.5 (eV); The present invention relates to a developing device including a toner supply roller.

  The toner supply roller and the developing device including the toner supply roller according to the present invention can sufficiently and stably supply the toner to the toner carrier, and sufficiently and stably charge the supplied toner. be able to. Therefore, it is possible to provide a good image over a long period of time without image density reduction due to defective toner supply and without fogging caused by defectively charged toner or reversely charged toner.

  The toner supply roller of the present invention (hereinafter simply referred to as “supply roller”) is a supply roller disposed in the developing device of the image forming apparatus, and serves as a toner carrier that conveys toner to the electrostatic latent image carrier. On the other hand, negatively chargeable toner is supplied. Specifically, for example, as shown in FIG. 5, the supply roller 1 is arranged in contact with the toner carrier 12 and supplies the negatively chargeable toner 15 in the toner tank 14 to the toner carrier 12 by its own rotation. A toner regulating member 13 is disposed in pressure contact with the toner carrier 12 downstream of the supply roller 1 in the rotation direction of the toner carrier 12, and the toner supplied by the supply roller 1 is made into a thin toner layer having a predetermined thickness. Triboelectrically charged. The toner thin layer on the toner carrier 12 that has been frictionally charged is conveyed to a development area facing the electrostatic latent image carrier 11 by the rotation of the toner carrier 12 and is used for developing the electrostatic latent image. The toner on the toner carrier 12 that has not been subjected to development is collected in the tank 14.

  As shown in FIG. 1, the supply roller 1 includes a core material 2, a foam elastic body layer 3 formed on the outer peripheral surface of the core material, and toner charging fine particles fixed on the outer surface of the foam elastic body layer. Have. FIG. 1 is a vertical cross-sectional configuration diagram with respect to the axial direction of the supply roller.

  The core material 2 only needs to have sufficient strength, and as the material, for example, a material such as iron, stainless steel, aluminum, or resin is used. In order to prevent corrosion or the like, the surface may be plated.

  The foamed elastic layer 3 is made of open-celled or single-celled foamed elastic material, and has cells opened at the outermost surface. The cell opened at the outermost surface is indicated by 4 in FIG. 2 representing an enlarged cross section of the surface portion A of FIG. In FIG. 1, the foamed elastic layer 3 has a cylindrical shape as a whole, but is not limited thereto. For example, a plurality of protrusions are axially arranged at a predetermined pitch on the surface of the cylindrical shape. The surface may be formed in a gear shape, a cylindrical shape, a plurality of cuts formed in the axial direction at a predetermined pitch, or a polygonal column shape.

  The foamed elastic layer 3 is usually formed from a foam of a thermosetting resin such as polyurethane, epoxy resin, or acrylic resin, but may be formed from a rubber foam of a thermoplastic resin such as polyethylene or polystyrene. The foamed elastic layer 3 is preferably made of a polyurethane foam (polyurethane foam) from the viewpoint of durability.

  The cells of the foamed elastic layer 3 are not particularly limited as long as the object of the present invention is achieved. From the viewpoint of more effectively improving the toner supply property, the cell average diameter and the cell average opening diameter are 50 to 1000 μm, particularly It is preferably 100 to 500 μm and the number of cells (density) is 10 to 100 cells / inch, particularly 40 to 80 cells / inch.

  The foamed elastic layer 3 may have conductivity or non-conductivity. The method of imparting conductivity to the foamed elastic body is not particularly limited, but is a method of foam-molding from the above raw materials mixed with conductive materials such as carbon black, polypyrrole and ionic conductive materials, and the conductive materials as described above. For example, a foamed elastic body may be impregnated with an impregnating liquid containing, and dried by heating. As a more preferable method for imparting conductivity, a method of impregnating a foamed elastic body with an impregnation liquid containing carbon black can be employed. The reason for this is that, as described above, even after imparting electrical conductivity, the foamed elastic body does not impair the properties of the foamed elastic body, and it is possible to suppress environmental fluctuations in resistance value and hardness as much as possible.

  Examples of the carbon black include carbon black such as furnace black, thermal black, channel black, acetylene black, ketjen black, and color black, and graphite. In addition, a composite system such as carbon black-polymer resin or graphite-polymer resin in which vinyl monomers are branched and polymerized on the surface of carbon black, graphite, or the like can also be used.

  The conductive or non-conductive foamed elastic layer can also be obtained as a commercial product, and examples thereof include urethane foam (ECA; manufactured by INOAC Corporation).

  The toner charging fine particles are indicated by 5 in FIG. 2 showing an enlarged cross section of the surface portion A of FIG. Specifically, the toner charging fine particles 5 are fixed to the outermost surface 6 of the foamed elastic layer 3 and the inner surface 7 of the cell 4 opened at the outermost surface by exposing at least a part thereof. The chargeability is imparted to the toner by the contact. In particular, FIG. 3 shows a schematic sketch when the open cell 4 is viewed from the B direction in FIG.

The toner charging fine particles 5 that satisfy a specific relationship with the toner in terms of work function are used.
That is, the work function (Wp) of the toner charging fine particles and the work function (Wt ₁ ) of the negatively chargeable toner are
Wt ₁ −Wp ≧ 0.5,
Usually 2.0 ≧ Wt ₁ −Wp ≧ 0.5,
Preferably 1.5 ≧ Wt ₁ −Wp ≧ 0.5,
Satisfy the relationship.

  The work function is energy (unit: eV) for extracting one electron from the surface of the substance, and is a characteristic value specific to the substance. Thus, for example, fine particles made of a specific substance usually have a work function different from that of fine particles having a coating layer on the surface thereof. It means that the smaller the work function is, the more easily the substance emits electrons, and the larger the work function, the harder it is to emit electrons. Therefore, when a substance having a small work function is brought into contact with a substance having a large work function, the substance having a small work function is positively charged, and the substance having a large work function is negatively charged.

  In the present invention, by setting the relationship between the toner charging fine particles and the toner in such a work function within the above range, it is possible to achieve improvement in toner charge imparting property and toner supply property in the supply roller over a long period of time. . Although the details of the mechanism are not clear, it is thought to be based on the following mechanism. That is, when the toner is supplied by the supply roller, the toner comes into contact with the toner charging fine particles fixed to the outermost surface 6 and the cell surface 7 in the foamed elastic layer of the supply roller. The toner charging fine particles have a work function relationship with the toner as described above, and have an exposed portion. Therefore, the toner polarity smoothly shifts to a predetermined polarity by contact between the exposed portion and the toner. Specifically, since the work function of the negatively chargeable toner is moderately larger than that of the toner charging fine particles, the toner charge amount is shifted more negatively by contact, and the polarity smoothly shifts to the negative polarity. Therefore, it is possible to achieve improvement in toner chargeability over a long period of time. Furthermore, as a result, an electric attractive force acts between the toner and the toner charging fine particles, and the surface area of the outer surface of the foamed elastic layer is increased, which is induced to the toner carrier by the supply roller. The amount of toner increases. Therefore, improvement in toner supply performance can be achieved over a long period of time.

If “Wt ₁ -Wp” is too small, the toner polarity does not smoothly shift to the predetermined polarity even when the toner and the toner charging fine particle exposed portion come into contact with each other. Cannot be charged properly. For this reason, generation of defectively charged toner and reversely charged toner becomes remarkable, and fogging occurs. In addition, the toner supply performance tends to decrease.

  In the present invention, the work function means the difference between the Fermi level and the vacuum level, and is a value measured as follows. That is, based on the contact potential, it is measured by an ultraviolet photoelectron emission spectrometer (UPS) (this apparatus can determine a work function in addition to the ionization potential of a substance) or a Kelvin method using a change in vibration capacity. It is a physical quantity. In many cases, a value measured by a photoelectron emission device AC-1 manufactured by Riken Keiki Co., Ltd. is used as a work function. However, the photoelectron emission device AC-1 manufactured by Riken Keiki Co., Ltd. measures the photoelectron emission at room temperature, and the value determined by plotting the power of the photoelectron yield against the energy of the incident light is determined from the organic compound. In the material, the ionization potential is different from the work function used in the present invention (see FIG. 7). However, when a metal is measured by a photoelectron emission device AC-1 manufactured by Riken Keiki Co., Ltd., the work function can be measured by obtaining a threshold value for photoelectron emission. This difference is due to the difference in phase between the electronic state of the metal and the organic semiconductor.

  In the present invention, the work function of the toner charging fine particles or the toner is obtained from the contact potential difference obtained by measuring the contact potential difference between each fine particle and the gold as the reference electrode using the contact potential difference measuring apparatus based on the Kelvin method shown in FIG. Can do.

  In FIG. 8, 31 is a reference electrode, which is made of brass plated with gold. Reference numeral 32 denotes a fine particle-dedicated measurement cell base, which is also made of brass plated with gold, and a fine particle sample 33 is held on the cell base. The microparticle sample 33 is a toner charging microparticle or toner. 34 is an ammeter and 35 is an external power source. The difference between the work function of the fine particle sample 33 and the work function of the reference electrode is the contact potential difference, and the measurement principle is as follows. When the fine particle sample 33 formed on the substrate 32 while maintaining electrical contact is opposed to the reference electrode at an interval of 1 to 2 mm and the cell substrate 32 and the reference electrode are electrically connected as shown in FIG. If the voltage of the power source 35 is zero, a potential equal to the contact potential difference between the two particulate sample 33 and the reference electrode is generated. The fine particle sample 33 and the reference electrode are capacitors to which a potential is applied. When the reference electrode is vibrated, the capacitance of the capacitor changes and a current flows through the circuit. Here, when a voltage having the opposite sign and equal to the contact potential is applied between the sample 33 and the reference electrode by the external power source 35, the voltage applied to both ends of the capacitor becomes zero and no current flows. When this current is monitored by the ammeter 34 and the voltage when the current stops flowing is obtained, it corresponds to the contact potential difference between the fine particle sample 33 and the reference electrode. Here, the work function of the reference electrode, which is a metal, can be measured by the photoelectron emission device AC-1 manufactured by Riken Keiki. Therefore, if the contact potential difference with the reference electrode is known, the work function of the sample can be determined. As a measurement environment for ensuring data reproducibility, the temperature control box 36 and external electrostatic influences are excluded in order to ensure the measurement environment under the conditions of a use temperature of 25 ° C. and 55% RH. Therefore, an electromagnetic shield 37 is used.

  The fine particle measurement cell base 32 has a shape having a fine particle sample receiving recess having a diameter of 10 mm and a depth of 1 mm in the center of a disk having a diameter of 13 mm and a height of 5 mm. The sample fine particles 33 are subjected to measurement in a state in which the toner is put into the recesses of the cell substrate 32 without being rammed using a weighing sledge and the surface is leveled and flattened using a knife edge. Since the charge generated at the time of production may affect the measurement value, the fine particle sample 33 is set on the cell substrate 32 and then left in the measurement environment for 6 hours. Note that the measurement sample 33 is left in a measurement environment for 24 hours.

The work function of the toner charging fine particles is preferably 4.3 to 5.3 eV.
The work function of the toner is not particularly limited as long as it satisfies the above-described relationship with the work function of the toner charging fine particles, but the work function of a general nonmagnetic one-component negatively chargeable toner is 5.25 to 5.85 eV. For example, the work function of the negatively chargeable toner (cyan toner for Magiccolor 5450) used in this example was 5.4 eV.

Specific examples of such toner charging fine particles include organic fine particles and inorganic fine particles described below. The numerical values in parentheses indicate work functions.
Organic fine particles: For example, nylon fine particles (about 4.3 to 4.4 eV), polymethyl (meth) acrylate fine particles (about 4.6 to 4.9 eV), silicone resin fine particles (about 5.2 eV), styrene-acrylic resin Fine particles (about 5.2 eV).
Inorganic fine particles; for example, aluminum fine particles (about 4.3 eV), tungsten fine particles (about 4.6 eV), nickel fine particles (about 5.2 eV), silica fine particles (about 5.0 eV).

  Preferred toner charging fine particles include organic fine particles, particularly nylon fine particles, and polymethyl (meth) acrylate fine particles, and more preferred are polymethyl (meth) acrylate fine particles.

  The toner charging fine particles may be used after being surface-treated. In this case, the work function of the toner charging fine particles satisfies the above relationship with the work function of the toner before and after the surface treatment. When the work function of the toner charging fine particles before the surface treatment does not satisfy the above relationship with the work function of the toner, even if the toner charging fine particles are subjected to a surface treatment to satisfy the above relationship, This is because the surface treatment agent is scraped and toner supply to the toner carrier and toner charging cannot be performed stably.

  The toner charging fine particles having an average volume particle diameter of 0.5 μm or more, preferably 0.5 to 5 μm, more preferably 1 to 5 μm are used. When the average volume particle diameter is less than 0.5 μm, the toner additive fine particles are buried in the external additive due to adhesion of the external additive added to the toner after the endurance, and the toner charge fine particles Thus, the image density followability and the toner chargeability are lowered. A toner supply roller to which toner charging fine particles having an average volume particle size exceeding 5 μm are not preferable because the toner supply amount decreases, and the fine particles are cracked and detached, particularly after durability. The image density followability is a characteristic that depends on the toner supply performance by the supply roller, and is a characteristic that stably suppresses a phenomenon in which the image density fluctuates between the paper leading edge and the paper trailing edge in one image. Since the toner supply roller of the present invention has a strong electrostatic toner adhesion force, it is easy to contain new toner during one round even after the toner has been dispensed once, and the image density followability is improved.

  The average volume particle size of the toner charging fine particles can be measured by, for example, a flow type particle image measuring device (FPIA2100 manufactured by Sysmex). Specifically, the average volume particle diameter is an average value of about 5000 toner charging fine particles.

  As the toner charging fine particles, those having the work function relationship with the toner are used, and among the fine particles satisfying such a relationship, those having the above average volume particle diameter are used.

  The toner charging fine particles may be used in combination of two or more kinds of fine particles. In that case, it is only necessary that the two or more types of toner charging fine particles have the above-mentioned relationship with the work function of the toner. The two or more kinds of toner charging fine particles preferably each have a volume average particle size within the above range.

  The amount of toner charging fine particles to be fixed is such that the coverage of the fine particles in the open cells is 30 to 90%, preferably 35 to 85%.

The coverage is the ratio of the area occupied by the toner charging fine particles on the surface of the opened cell.
In this specification, the coverage is determined by observing any 30 open cells with SEM (manufactured by Hitachi; Hitachi S-3400N), and averaging the ratio of the area occupied by the toner charging fine particles in the total surface area of the cells. The calculated value is used. Before observation of the open cells, the toner charging fine particles that were not fixed were washed and removed.

  When the coverage of the toner charging fine particles is too small, the effect of providing the fine particles is not exhibited. That is, when printing an image that constantly supplies toner (with a high printing rate), the image density followability is reduced, which decreases the image density from the leading edge to the trailing edge of the paper. On the other hand, if the coverage is too high, the fine particles occupying the cell will be excessive, and the absolute value of the toner supply amount will be reduced. In other words, in order to maintain an appropriate image density and to prevent the image density from fluctuating between the leading edge and the trailing edge of the paper, the coverage of the inner surface of the toner charging fine particles needs to be within the above range. There is.

  In the supply roller manufacturing method, first, a foamed elastic layer is formed on a core material. The method for forming the foamed elastic body layer is not particularly limited, and the foamed elastic body layer may be foam-molded on the core material, or the molded foamed elastic body may be fixed to the core material with an adhesive or the like. After the formation of the foamed elastic layer, mechanical processing such as cutting and polishing may be performed in order to form the outer diameter size and shape of the foamed elastic multilayer.

  Next, the toner charging fine particles are fixed to the outer surface of the foamed elastic layer while exposing the toner charging fine particles. The method for fixing the toner charging fine particles is not particularly limited as long as the fixing of the toner charging fine particles to the outer surface and the exposure of the toner charging fine particles can be achieved. For example, (1) as shown in FIG. A method in which the toner charging fine particles 5 are adhered to the adhesive layer 8 after the adhesive is applied to the outer surface of the foamed elastic layer 3 and then dried, and (2) toner charging In the case where the fine particles are made of an organic material, the fine particles are dispersed on the outer surface of the foamed elastic layer, and then heated moderately to cause melting at the contact portion with the outer surface of the fine particles, and then cooled to cool the fine particles. Examples include a method for achieving immobilization. FIG. 4 is an enlarged schematic cross-sectional view of the vicinity of the outermost surface 6 and the cell surface 7 of the elastic foam layer in one embodiment of the toner supply roller of the present invention.

  As a method for fixing the toner charging fine particles, if a method of incorporating the toner charging fine particles into the foamed elastic layer by previously including the toner charging fine particles in the raw material of the foamed elastic layer, the fine particles are expanded. It is buried in the elastic layer and is not exposed effectively. Even if mechanical processing is performed after molding, the fine particles fixed on the surface in the cell are not effectively exposed while being embedded in the foamed elastic layer. Therefore, the contact between the toner charging fine particles and the toner is not effectively achieved, and the effect of improving the toner charging property cannot be obtained. In addition, when a coating liquid in which fine particles for charging toner are dispersed in a binder resin solution is applied to the outer surface of the foamed elastic layer and dried, the fine particles are covered with the binder resin and are not exposed. Contact between the charging fine particles and the toner is not effectively achieved, and the effect of improving toner chargeability cannot be obtained.

  The toner supplied by the supply roller as described above is not particularly limited as long as it has a relationship between the toner charging fine particles and the work function described above, and is usually used as a toner for developing an electrostatic latent image conventionally. Are used and have the work function. When the toner contains an external additive, the work function of the toner containing the external additive may have the above relationship with the work function of the toner charging fine particles.

  Since the supply roller 1 is excellent in toner charge imparting property, even if the pressure contact pressure (regulation pressure) of the toner regulating member 13 with respect to the toner carrier 12 is reduced, friction charging with respect to the toner can be effectively performed. Specifically, the pressure contact pressure of the toner regulating member 13 may be 20 N / m or less, particularly 10 N / m or less. Since the pressure contact pressure of the toner regulating member 13 can be effectively reduced as described above, toner deterioration such as toner cracking or external additive embedding can be suppressed, and as a result, defective charging or reverse charging of the toner can be more effectively prevented.

  In FIG. 5, the toner carrier 12 has a simple roller shape. However, the toner carrier 12 is not limited to this as long as the toner thin layer formed on the toner carrier 12 can be conveyed to the development area. You may have the form which becomes.

Hereinafter, the present invention will be described in detail using examples.
[Experimental Example 1]
(Examples 1-9 / Comparative Examples 1-6)
<Manufacture of supply rollers>
ECA (manufactured by Inoac Corporation, cell average diameter of 400μm, number of cells / inch) is used as the foamed elastic body, cut into a 40mm x 40mm x 300mm cuboid and cored in the long axis direction A hole of φ6 was made to insert the material.The iron core material φ8 previously coated with hot melt adhesive with a roll coater was passed through the hole of ECA, and the core material was heated with an electromagnetic induction heater. The adhesive was melted, the ECA and the core were bonded, the core was cooled, and after the bonding was completed, the foamed elastic body was cut to have an outer diameter of φ11.6, and the foamed elastic roller The average opening diameter of the cell was 400 μm.

  An adhesive was sprayed onto the surface of the foamed elastic roller.

  Next, using a fine particle attaching device 20 shown in FIG. 6, a predetermined amount of toner charging fine particles were uniformly attached in a predetermined amount to the surface of the foamed elastic roller 21 to which the adhesive was applied.

  Specifically, the fine particle adhering device 20 is transported by rotating in contact with the transport roller 23 and the transport roller 23 for transporting the toner charge fine particles into the replenishing tank 22 storing the toner charge fine particles. An adhesion roller 24 for flying and adhering the toner charging fine particles conveyed by the roller 23 to the foamed elastic roller 21 is provided. The foamed elastic roller 21 is disposed in a non-contact state with the adhesion roller 24 at a position facing the adhesion roller 24.

Specifically, an arbitrary DC bias can be applied to the transport roller 23, the adhesion roller 24, and the foamed elastic roller 21.
First, a bias is set so that the fine particles are conveyed from the conveying roller 23 to the adhesion roller 24. For example, conveyance roller: GND, adhesion roller: GND-300V. As a result, a predetermined amount of fine particles can be transported to the adhesion roller 24, and the transport amount can be controlled by the numerical value of the bias.
Next, a bias is set so that the fine particles fly and adhere to the foamed elastic roller 21 from the adhesion roller 24. For example, adhesion roller: GND-300V, foamed elastic roller: GND-600V. This makes it possible for the fine particles on the adhesion roller 24 to fly uniformly in a predetermined amount and adhere to the foamed elastic roller 21, and it is also possible to control the adhesion amount by the applied bias and the rotational speed.

In each of the examples / comparative examples, as shown in Table 1, predetermined fine particles for charging the toner are obtained by appropriately adjusting the applied voltage and rotation speed of the transport roller 23, the adhesion roller 24, and the foamed elastic roller 21. A predetermined amount was uniformly deposited.
Thereafter, the foamed elastic roller 21 with the toner charging fine particles adhered thereto was dried by heating to obtain a supply roller.

(Comparative Examples 7-8)
<Manufacture of supply rollers>
The toner charging fine particles listed in Table 2 were kneaded and molded into the foamed raw material, and then processed into a roller shape to obtain a supply roller.

<Evaluation>
The supply roller obtained in each example / comparative example was mounted on a Magiccolor 5450 (manufactured by Konica Minolta), and a printing durability test was performed on 5000 sheets. The following items were evaluated at the initial stage and after printing. As the toner, a negatively chargeable toner (cyan toner for Magiccolor 5450; work function: 5.4 eV) was used. The regulation pressure by the toner regulating member was 25 N / m.
Further, the coverage of the toner charging fine particles on the supply roller was determined by the method described above.

-Toner supply property Evaluation is made with a solid image density (ID) of 1.4 or more as ◎, less than 1.4 as 1.3 or better, less than 1.3 as 1.1 or better, and less than 1.1 as ×. did. The above is the allowable range of the present invention.

・ Reversely charged toner ratio The toner charge distribution on the toner carrier is measured by E-SPART made by Hosokawa Micron. The ratio of the reversely charged toner is less than 5%, 5% or more but less than 10%, △ 10% or more. Was evaluated as x. The above is the allowable range of the present invention.

・ Fog A blank paper image was printed, and the fog was evaluated visually. The case where the fog could not be visually confirmed at all was evaluated as “○”, the case where the fog was slightly confirmed by visual observation as Δ, and the case where the fog could be clearly confirmed by visual observation was evaluated as “X”. The above is the allowable range of the present invention.

The toner charging fine particles used in Examples / Comparative Examples are shown below.
A1) Polymethyl methacrylate (MP-1000 manufactured by Soken Chemical Co., Ltd .: average particle size 0.5 μm, work function 4.6 eV)
A2) Polymethyl methacrylate (MR-7G manufactured by Soken Chemical Co., Ltd .: average particle size 5 μm, work function 4.9 eV)
A3) Polymethyl methacrylate (MP-1450 manufactured by Soken Chemical Co., Ltd .: average particle size 0.25 μm, work function 4.7 eV)
A4) Polymethyl methacrylate (MP-1451 manufactured by Soken Chemical Co., Ltd., average particle size 0.15 μm, work function 4.6 eV)
B1) Nylon fine particles (Toray Nylon SP500 manufactured by Toray Industries Inc .: average particle size 5 μm, work function 4.3 eV)
B2) Nylon fine particles (Toray Nylon KG-10, manufactured by Toray Industries, Inc .: average particle size 10 μm, work function 4.4 eV)
C1) Silicon fine particles (GE Toshiba Silicone Tospearl 120: average particle size 2.1 μm, work function 5.2 eV)
C2) Silicon fine particles (GE Toshiba Silicone Tospearl 145: average particle size 4.4 μm, work function 5.2 eV)
D1) Silica (an anhydrous silica ultrafine powder Aerosil OX50 manufactured by Degussa, Germany: average particle size 40 nm, work function 5.0 eV)
D2) Silica powder D1 hydrophobized with γ-aminopropyltriethoxysilane (average particle size 60 nm, work function 4.6 eV)
E1) Polytetrafluoroethylene particles (Daikin Industries' Lubron L-2: average particle size 5 μm, work function 5.8 eV)
E2) Polytetrafluoroethylene particles (Daikin Industries' Lubron LDW-40: average particle size 0.2 μm, work function 5.8 eV)

[Experiment 2]
(Examples 10 to 12)
Evaluation was performed in the same manner as in Experimental Example 1 except that the same supply roller as in Example 1 was used and that the pressure regulated by the toner regulating member was changed to the values shown in Table 2.

(Comparative Examples 9 to 10)
Evaluation was made in the same manner as in Experimental Example 1 except that the foamed elastic roller obtained in Experimental Example 1 was used as a supply roller as it was and the regulation pressure by the toner regulating member was changed to the value shown in Table 2. went.

FIG. 3 is a schematic cross-sectional view illustrating an embodiment of a toner supply roller of the present invention. It is an enlarged view of the surface part A in FIG. FIG. 3 is a schematic sketch when a cell from a direction B in FIG. 2 is viewed. FIG. 3 is a schematic cross-sectional view of the outermost surface of the foamed elastic layer and the cell surface in an embodiment of the toner supply roller of the present invention. 1 is a schematic cross-sectional view illustrating an embodiment of a developing device including a toner supply roller of the present invention. It is a schematic sectional drawing which shows an example of the apparatus used for manufacture of the toner supply roller of this invention. It is a schematic diagram for demonstrating a work function. It is a schematic block diagram of the contact potential difference measuring apparatus used when calculating | requiring a work function.

Explanation of symbols

  1: toner supply roller, 2: foamed elastic layer, 3: core material, 4: open cell, 5: fine particles for charging toner, 6: outermost surface of foamed elastic layer, 7: surface in open cell, 8 : Adhesive layer, 10: Developing device, 11: Electrostatic latent image carrier, 12: Toner carrier, 13: Toner regulating member, 14: Toner tank, 15: Toner, 20: Particulate adhesion device, 21: Foam elasticity Body roller, 22: Supply tank, 23: Conveyance roller, 24: Adhesion roller, 31: Reference electrode, 32: Dedicated particle cell base, 33: Particle sample, 34: Ammeter, 35: External power supply, 36: Temperature control Box 37: Electromagnetic shield.

Claims (4)

A toner supply roller for supplying negatively chargeable toner to a toner carrier for conveying toner to the electrostatic latent image carrier;
A core material, a foamed elastic layer formed on the outer peripheral surface of the core material and having cells opened at the outermost surface, and at least the outermost surface of the foamed elastic layer and the surface of the cell opened at the outermost surface A portion of the toner charging fine particles that are exposed and fixed;
A toner supply roller, wherein the work function (Wp) of the toner charging fine particles and the work function (Wt ₁ ) of the negatively chargeable toner satisfy a relationship of Wt ₁ −Wp ≧ 0.5 (eV).   The toner supply roller according to claim 1, wherein an average volume particle size of the toner charging fine particles is 0.5 μm or more.   3. The toner supply roller according to claim 1, wherein the ratio of the area occupied by the toner charging fine particles on the surface of the opened cell is 30 to 90%. 4.   A developing device comprising the toner supply roller according to claim 1.

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