JP2008032771A - Developing device and toner regulating roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device with which a high-quality image can be obtained for a long period by suppressing toner deterioration and achieving the stabilization of an amount of conveyance and electrostatic charging property. <P>SOLUTION: The toner regulating roller 1 is ≤1.8N in elastic force and the developing device 10 brings the toner regulating roller into pressurized contact with the developing roller 2 in such a manner that the line pressure is 5 to 30 N/m. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a developing device that is incorporated and used in an image forming apparatus such as a copying machine, a printer, and a facsimile, and a toner regulating roller that is incorporated and used in the developing device.

  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 to produce a visible toner image. A developing device for forming is used.

  As such a developing device, for example, one having a structure in which a toner regulating roller is disposed in pressure contact with a developing roller disposed close to or in contact with an electrostatic latent image carrier is known. In the developing device, the toner is made into a thin toner layer on the developing roller by the toner regulating roller, and is triboelectrically charged. Then, the toner is conveyed to the developing area facing the electrostatic latent image carrier by the developing roller, and the electrostatic latent image It is used for development. The toner regulating roller generally has a hard roller structure such as a metal material and a hard resin material, and even if the surface portion is made of a foam material or an elastic layer that is softer than the hard roller structure, The elastic force was 2N or more (Patent Documents 1 to 4). The developing roller also generally has a hard roller configuration such as a metal material and a hard resin material, and the surface elastic force is 2N or more.

  In general, the toner regulating roller and the developing roller have a dimensional error in the distance from the shaft to the surface in one roller or bend in the shaft. Therefore, the distance between the toner regulating roller surface and the developing roller surface is locally increased by rotation. It was a problem that could not be avoided. Therefore, one roller having a relatively hard surface is pushed into the other roller having a relatively soft surface to ensure contact between the rollers. For example, when using a toner regulating roller having a diameter of about 12 mm having a foamed polyurethane layer having a surface elastic force of about 5 N and a developing roller having a surface having a silicon rubber layer having a surface elastic force of about 30 N, a developing roller having a diameter of about 16 mm is used. The toner regulating roller was attached by being pushed in by about 0.25 mm. As a result, the contact pressure between these rollers is relatively high, and the toner regulating roller and the developing roller are in pressure contact with a high linear pressure of about 50 to 150 N / m, for example.

However, such a conventional developing device has a problem of toner deterioration. That is, since the toner to which the external additive is externally applied is subjected to a relatively large stress between the toner regulating roller and the developing roller, the external additive, particularly a toner having a relatively small diameter is buried in the toner particles. Deterioration has occurred. When the external additive is buried, the fluidity decreases, so the toner transport amount by the developing roller becomes unstable during the endurance or the chargeability of the toner decreases, resulting in fogging of the image. It was.
JP 2001-51503 A JP-A-9-258552 JP 2004-29357 A JP 2004-85623 A

  Therefore, attempts have been made to reduce the pressure contact between the toner regulating roller and the developing roller. However, if the pressure contact pressure is reduced using the conventional toner regulating roller, the toner conveyance amount of the developing roller becomes unstable from the beginning. The charging stability was lowered.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device and a toner regulating roller that can suppress deterioration of toner, achieve stabilization of chargeability, and obtain a high-quality image over a long period of time.

  The present invention relates to a developing device in which a toner regulating roller having an elastic force of 1.8 N or less is brought into pressure contact with a developing roller so that a linear pressure is 5 to 30 N / m.

  The present invention also relates to a toner regulating roller having an elastic force of 1.8 N or less.

  According to the present invention, since a smaller linear pressure can be effectively achieved between the toner regulating roller and the developing roller, toner deterioration such as burying of the external additive is suppressed, and the conveyance amount and the charging property are stabilized. it can. As a result, the charging stability of the toner is improved, and a high quality image can be obtained over a long period of time.

  In the developing device of the present invention, a specific toner regulating roller (hereinafter simply referred to as “regulating roller”) is brought into pressure contact with the developing roller. For example, as shown in FIG. 1, the regulating roller 1 is disposed in pressure contact with the developing roller 2 upstream of the developing region P in the rotation direction of the developing roller 2, whereby the toner 3 is placed on the surface of the developing roller 2. A thin layer is formed and triboelectrically charged. After the toner thin layer is triboelectrically charged on the surface of the developing roller 2 in the developing device 10, the toner thin layer is conveyed by the developing roller 2 to the developing area P facing the electrostatic latent image carrier 4 and is electrostatic latent image. It is to be used for development. In FIG. 1, reference numeral 5 denotes a toner supply roller that supplies toner to the developing roller 2 and is disposed upstream of the regulating roller 1 in the rotational direction of the developing roller 2, but it is not necessarily present. That doesn't mean it doesn't happen.

  The regulating roller has a surface elastic force of 1.8 N or less, particularly 0.1 to 1.8 N, preferably 0.5 to 1.6 N, and is deformed by an external force, but its shape is restored by removing the external force. To do. By using a regulation roller having such an elastic force, the linear pressure between the regulation roller and the developing roller can be effectively reduced to a range described later, so that toner deterioration is suppressed and the conveyance amount and charging property are stabilized. Can be achieved. If a restricting roller having too much elastic force is used, the linear pressure between the restricting roller and the developing roller becomes too large to be set within the range described later. The toner becomes unstable or the chargeability of the toner decreases.

Elastic force is a measure of hardness, and the smaller the value, the softer it is.
In this specification, the elastic force uses a value measured by the following method. That is, a roller is placed on a measuring table, a plastic disk having a diameter of 13 mm is attached to a push-pull gauge (ZP-20; manufactured by IMADA), and the value when pressed perpendicularly to the central axis of the roller is the elastic force (N ). The amount of indentation at that time is 1.0 mm, and the value one minute after the indentation is taken as the measurement value.

  The push-in amount refers to the maximum deformation amount (distance) in the radial direction of the regulating roller when the regulating roller surface is deformed into a concave shape due to contact between the regulating roller and another member.

  The regulation roller having such an elastic force can be easily obtained by requesting the manufacturer of the roller. For example, it is well known to roller manufacturers that the roller surface is made of foam and the elasticity of the foam can be controlled by adjusting the hardness of the foam. The elastic force of the regulating roller can be controlled by appropriately adjusting the amount of the foaming agent when manufacturing. When the amount of the foaming agent is increased, the hardness of the obtained foam is lowered, so that the elastic force of the roller obtained using the foam is reduced. On the other hand, when the amount of the foaming agent is reduced, the hardness of the obtained foam increases, so that the elastic force of the roller obtained using the foam increases.

  For example, when manufacturing a regulating roller formed by forming a foam layer made of polyurethane foam on the outer peripheral surface of the core metal, specifically, first, a polyol component, a polyisocyanate component and a foaming agent at a predetermined ratio, and, if desired, Additives such as conductivity imparting agent and foam stabilizer are mixed and stirred by a mixer. Next, after discharging and foaming, it is cured by heating. Thereafter, a hole for inserting the cored bar is formed in the foam, and the cored bar having an outer peripheral surface coated with an adhesive is inserted into the hole. After the foam and the metal core are sufficiently adhered, the foam is cut and formed to form a foam layer having a uniform thickness. After forming the foamed layer, a cylindrical tube made of conductive polyamide or the like is usually placed on the foamed layer, and the foamed layer and the end of the tube are bonded with a conductive adhesive to give a thickness of 50- A 300 μm skin layer is formed. When the skin layer is provided on the surface of the foam layer, the elastic force measured from above the skin layer may be within the above range. The thickness of the foam layer is not particularly limited as long as the elastic force can be achieved, and is usually 2 to 10 mm, particularly 2 to 7.5 mm. The diameter of the cored bar is usually 3 to 10 mm.

The density of the foamed layer constituting the regulating roller and the average diameter of the bubbles are not particularly limited as long as the elastic force is achieved, and is usually in the following range;
Foam layer;
Density of 10-80 kg / m ³ , in particular 15-60 kg / m ³ ;
Bubble average diameter 0.2-1.5 mm, especially 0.3-1.2 mm.

The density conforms to JIS K 6400.
For the average bubble diameter, a value measured by measuring the diameter of the bubbles with an electron microscope (SEM) and averaging the diameters of 100 bubbles is used.

The regulating roller preferably has electrical conductivity and usually has the following volume resistance;
Roller containing cored bar; volume resistance 10 ² to 10 ⁸ Ω, particularly 10 ⁴ to 10 ⁶ Ω.

  The volume resistance is set by placing a target roller on a copper plate that also serves as an electrode, applying a weight of 500 g to both ends of the core metal, measuring the current value when a direct current of 100 V is applied between the core metal and the copper plate, and the resistance ( Ω) = 100 (V) / current (A). The contact portion with the copper plate was measured four times at about 90 degrees, and the average was taken as the resistance value of the roller.

  The regulating roller is brought into pressure contact with the developing roller so that the linear pressure is 5 to 30 N / m, preferably 7 to 28 N / m, more preferably 10 to 15 N / m. If the linear pressure is too small, toner deterioration can be prevented, but the amount of toner transported by the developing roller becomes unstable from the beginning, and the chargeability of the toner decreases. If the linear pressure is too large, the amount of toner transported by the developing roller becomes unstable during durability, or the chargeability of the toner decreases. Strictly speaking, the linear pressure is not necessarily constant in the axial direction due to the dimensional error of the roller, the bending of the roller shaft, and the like. That's fine.

  The pressing amount of the regulating roller by the developing roller is usually set to 0.25 to 1.5 mm, preferably 0.40 to 1.2 mm, more preferably 0.50 to 1.0 mm. Therefore, it is sufficient that the linear pressure is achieved when the pushing amount is set to any value within such a range. If the push-in amount is too small, contact between the regulating roller and the developing roller cannot be ensured during driving due to dimensional error of the roller, bending of the shaft, and the like, so that a thin toner layer cannot be formed. If the push-in amount is too large, toner deterioration is likely to occur, so that the amount of toner transported by the developing roller becomes unstable during durability and the chargeability of the toner decreases. Strictly speaking, the pressing amount of the regulating roller is not necessarily constant in the axial direction due to the dimensional error of the roller, the bending of the shaft, and the like. It only has to be done.

The linear pressure between the regulating roller and the developing roller can be measured by the following method using a linear pressure measuring device.
As shown in FIG. 2 which represents a schematic cross-sectional view, the linear pressure measuring device 15 is obtained by incorporating a load converter (9E01-L43-10N; manufactured by NEC Saneisha) 12 into an aluminum roller 11 having a diameter of 16 mm. Specifically, a pressure receiving member 13 extending in the longitudinal direction (axial direction) is provided on the roller surface of the measuring instrument, and when pressure is applied to the pressure receiving member, the pressure is applied by a load converter 12 incorporated therein. The applied load is measured. The linear pressure is obtained from the measured value and the distance in the roller longitudinal direction of the pressure portion of the pressure receiving member 13.

  Specifically, first, the pressing amount of the regulating roller due to the pressure contact between the developing roller and the regulating roller is measured. For example, as shown in FIG. 3A, the pressing amount of the regulating roller 1 when the developing roller 2a is a hard roller that is not deformed by pressure contact with the regulating roller 1 is indicated by y in FIG. Further, for example, as shown in FIG. 3B, the pressing amount of the regulating roller 1 when the developing roller 2b is a soft one that is deformed by pressure contact is indicated by y in FIG. 3B.

  Next, the measured pressing amount y of the regulating roller is reproduced by the linear pressure measuring device and the regulating roller. That is, while keeping the axis of the regulating roller and the axis of the linear pressure measuring device in parallel, the surface center 14 of the pressure receiving member 13 of the linear pressure measuring device is pressed against the regulating roller and pushed in, thereby achieving the pushing amount y. The linear pressure is obtained from the measured value (load) of the linear pressure measuring device at that time and the distance in the roller longitudinal direction at the contact portion between the measuring device and the regulating roller.

  The rotation direction of the regulating roller 1 is a counter (reverse) direction with respect to the developing roller at the contact portion with the developing roller 2 in FIG. 1, but is not limited to this. It may be in the direction, or it may be attached in a stopped state without rotating. From the viewpoint of further improving the chargeability of the toner, it is preferable that the regulating roller rotates in the counter direction. The rotation direction of the regulating roller is the rotation direction at the contact portion with the developing roller, and the rotation direction of the developing roller is shown as a reference.

  When the regulating roller 1 rotates, particularly when it rotates in the counter direction, the peripheral speed ratio between the regulating roller and the developing roller (regulating roller / developing roller) is 3.00 or less from the viewpoint of further improving the chargeability of the toner. In particular, 0.20 to 1.5 is preferable.

  For example, when the cross-sectional diameter of the regulating roller 1 is 10 to 15 mm, the circumferential speed of the regulating roller 1 is usually 0 to 90 m / min, particularly 0 to 30 m / min.

  The developing roller 2 is not particularly limited in the present invention, and those conventionally used in the field of developing devices can be used. For example, it may have a metal roller structure made only of a core metal such as aluminum or stainless steel, or an elastic roller structure in which a rubber layer made of silicon rubber or the like is formed on the outer peripheral surface of such a core metal. Alternatively, it may have a composite roller structure in which a coating layer made of acrylonitrile-butadiene rubber or the like is formed on the outer peripheral surface in those structures. The coating layer may have a single layer structure or a multilayer structure of two or more layers, and preferably has a two-layer structure including an intermediate layer and a surface layer.

  Regardless of the configuration of the developing roller, the surface roughness of the outermost surface is preferably 0.1 to 10 μm from the viewpoint of further stabilizing the toner conveyance amount. When having a metal roller configuration, the surface roughness is achieved by blasting the outermost surface. In the case of having an elastic roller configuration, the surface roughness is achieved by containing fine particles such as silica in the rubber layer. In the case of having a composite roller configuration, the surface roughness is achieved by containing fine particles such as silica in the coating layer, particularly the intermediate layer and the surface layer.

The developing roller preferably has conductivity from the viewpoint of further improving the toner chargeability. The volume resistance is preferably 10 ² to 10 ⁸ Ω, particularly 10 ⁴ to 10 ⁶ Ω. In particular, when the developing roller has an elastic roller structure or a composite roller structure, the volume resistance is achieved by adding a conductivity imparting agent such as carbon black to the rubber layer or the coating layer.

A DC voltage is normally applied to the developing roller and the regulating roller. From the viewpoint of further improving the toner chargeability, it is preferable to apply a DC voltage having the same polarity as the polarity to which the toner is to be charged to the regulating roller with reference to the DC voltage applied to the developing roller.
For example, when the toner is negatively charged, a DC voltage that is more negative than the DC voltage applied to the developing roller is applied to the regulating roller. That is, a DC voltage lower than the DC voltage applied to the developing roller is applied to the regulating roller.
Further, for example, when the toner is positively charged, a DC voltage that is more positive than the DC voltage applied to the developing roller is applied to the regulating roller. That is, a DC voltage higher than the DC voltage applied to the developing roller is applied to the regulating roller.

  The polarity with which the toner should be charged is a positive or negative polarity that the toner should have at the time of development, and can be found by measuring the charge amount of the toner on the developing roller in the developing region.

The potential difference between the DC voltage applied to the developing roller and the DC voltage applied to the regulating roller is not particularly limited as long as the object of the present invention is achieved. ~ 400V, particularly 50-300V is preferred.
The DC voltage applied to the developing roller is usually −100 to −550 V, particularly −250 to −450 V when the toner is negatively charged, and 100 to 550 V when the toner is charged positively. In particular, it is 250 to 450V.

  An AC voltage is preferably superimposed on the developing roller together with the DC voltage. The AC voltage applied to the developing roller is not particularly limited. For example, the peak-to-peak value (Vpp: amplitude) is 800 to 3000 V, particularly 1000 to 2500 V, and the frequency is 1 to 5 kHz, especially 2 to 4 kHz. The duty ratio is preferably 10 to 80%, particularly preferably 20 to 60%. Various waveforms such as a rectangular wave, a sine wave, and a sawtooth wave can be used as the waveform of the AC voltage applied to the developing roller, but a rectangular wave is preferable.

  It is preferable that an AC voltage is superimposed on the regulating roller together with the DC voltage. The AC voltage applied to the regulating roller is not particularly limited. For example, the peak-to-peak value (Vpp: amplitude) is 800 to 3200 V, particularly 1000 to 2700 V, and the frequency is 1 to 5 kHz, particularly 2 to 4 kHz. The duty ratio is preferably 10 to 80%, particularly preferably 20 to 60%. Various waveforms such as a rectangular wave, a sine wave, and a saw wave can be used as the waveform of the AC voltage applied to the regulating roller, but a rectangular wave is preferable.

  As the toner 3, a known toner that has been conventionally used and externally added can be used. For example, a colorant in a binder resin, a charge control agent, a release agent, and the like as necessary. In this case, toner particles containing an additive and an external additive are added. In the present invention, from the viewpoint of further improving the charging property of the toner, it is preferable to use a toner that is negatively charged. The charge polarity of the toner can be easily controlled by the type of charge control agent, the type and amount of external additive, and the like.

  As the external additive, known additives generally used in the field of electrostatic latent image developing toner can be used. For example, inorganic fine particles such as silica, titanium oxide, aluminum oxide, and strontium titanate, and organic fine particles such as acrylic resin, styrene resin, silicone resin, and fluorine resin can be used. In particular, it is preferable to use a silane coupling agent, a titanium coupling agent, or a material hydrophobized with silicon oil or the like.

  An external additive having an average primary particle diameter of 1 nm or more and less than 150 nm, particularly a small diameter of 5 nm or more and 100 nm or less, and preferably an average primary particle diameter of 150 nm or more and 450 nm or less, particularly 150 nm or more and 400 nm together with the small diameter external additive. The following large diameters are used in combination. The addition amount of the small-diameter external additive is usually 0.1 to 3 parts by weight, particularly 0.5 to 2.5 parts by weight with respect to 100 parts by weight of the toner particles. Should just be in the said range. The addition amount of the large-diameter external additive is usually 0.5 to 3 parts by weight, particularly 1 to 3 parts by weight with respect to 100 parts by weight of the toner particles, and when two or more kinds are used, the total amount thereof is in the above range. If it is in.

  The binder resin is not particularly limited. For example, styrene resin (particularly styrene-acrylate resin), polyester resin, epoxy resin, vinyl chloride resin, phenol resin, polyethylene resin, polypropylene resin, polyurethane resin, A silicone resin etc. are mentioned.

  As the colorant, known pigments and dyes generally used in the field of electrostatic latent image developing toner can be used. For example, carbon black, aniline black, activated carbon, magnetite, benzine yellow, permanent yellow, naphthol. Examples include yellow, phthalocyanine blue, first sky blue, ultramarine blue, rose bengal, lake red and the like.

  As the charge control agent, those known in the field of electrostatic latent image developing toner can be used. Examples of charge control agents for positively chargeable toners include nigrosine dyes, quaternary ammonium salt compounds, triphenylmethane compounds, imidazole compounds, and polyamine resins. Examples of the charge control agent for negatively chargeable toners include metal-containing azo dyes such as Cr, Co, Al, and Fe, salicylic acid metal compounds, alkylsalicylic acid metal compounds, and curlyx arene compounds.

  As the release agent, known ones generally used in the field of electrostatic latent image developing toner can be used. For example, polyethylene, polypropylene, carnauba wax, sazol wax, ester wax and the like can be used alone or in combination of two or more.

  The toner particles are so-called pulverization method, suspension polymerization method, emulsion polymerization method, emulsion polymerization aggregation method, emulsion dispersion method in which resin particles obtained by emulsion polymerization and colorant particles are aggregated and fused to obtain toner particles. It can manufacture by various manufacturing methods, such as.

  Hereinafter, “part” indicates “part by weight”.

<Manufacture of toner particles WC1>
(Manufacture of resin fine particles)
In a 5000 ml separable flask equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen introduction device, 7.08 g of an anionic active agent (sodium dodecylbenzenesulfonate: SDS) was dissolved in ion-exchanged water (2760 g) in advance. Add the solution. The internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. On the other hand, the following compound; CH ₃ (CH ₂ ) ₂₀ COOCH ₂ C (CH ₂ OCO (CH ₂ ) ₂ 0CH ₃ ) ₃ 72. Og was added to a monomer composed of 115.1 g of styrene, 42.0 g of n-butyl acrylate, and 10.9 g of methacrylic acid, and heated to 80 ° C. and dissolved to prepare a monomer solution.
Here, the above heated solution was mixed and dispersed by a mechanical disperser having a circulation path to produce emulsified particles having a uniform dispersed particle size. Next, latex particles were prepared by adding a solution obtained by dissolving 0.90 g of a polymerization initiator (potassium persulfate: KPS) in 200 g of ion-exchanged water, and heating and stirring at 80 ° C. for 3 hours. Subsequently, a solution in which 8.00 g of a polymerization initiator (KPS) was dissolved in 240 ml of ion-exchanged water was further added, and after 15 minutes, 383.6 g of styrene, 140.0 g of n-butyl acrylate, 36. A mixed solution of 4 g and 13.7 g of t-dodecyl mercaptan was dropped over 120 minutes. After completion of dropping, the mixture was heated and stirred for 60 minutes and then cooled to 40 ° C. to obtain resin fine particles containing ester wax.

(Manufacture of toner particles)
10 g of sodium n-dodecyl sulfate is dissolved with stirring in 160 ml of ion-exchanged water. To this liquid, C.I. I. 20 g of Pigment Blue 15-3 (cyan pigment) was gradually added, and then dispersed using CLEARMIX. This dispersion is referred to as a cyan colorant dispersion. The above-mentioned resin fine particles 1250 g, ion-exchanged water 2000 ml, and a colorant dispersion are put into a 5-liter four-necked flask equipped with a temperature sensor, a cooling tube, a nitrogen introducing device, and a stirring device and stirred. After adjusting to 30 ° C., a 5 mol / liter aqueous sodium hydroxide solution was added to this solution to adjust the pH to 10.0. Subsequently, an aqueous solution in which 52.6 g of magnesium chloride hexahydrate was dissolved in 72 ml of ion-exchanged water was added at 30 ° C. over 5 minutes with stirring. Then, after standing for 1 minute, temperature increase is started, and the liquid temperature is increased to 90 ° C. in 6 minutes (temperature increase rate = 10 ° C./min). In that state, the particle size was measured with a Coulter Counter TA-II. When the volume average particle size reached 6.5 μm, an aqueous solution in which 115 g of sodium chloride was dissolved in 700 ml of ion-exchanged water was added to stop particle growth. Further, the mixture is heated and stirred at a liquid temperature of 90 ° C. ± 2 ° C. for 6 hours to cause salting out / fusion. Then, it cooled to 30 degreeC on the conditions of 6 degreeC / min, hydrochloric acid was added, pH was adjusted to 2.0, and stirring was stopped. The produced colored particles were filtered, washed repeatedly with ion-exchanged water, and then dried with hot air at 40 ° C., to obtain toner particles WC1 having a volume average particle size of 6.5 μm and an average circularity of 0.975.

<Manufacture of toner particles DC1>
(Production of polyester resin A)
4.0 mol of polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as “PO”), polyoxyethylene (2,0) -2,2-bis (4- Hydroxyphenyl) propane (hereinafter referred to as “EO”) 6.0 mol, terephthalic acid (hereinafter referred to as “TPA”) 9.0 mol and dibutyltin oxide as a catalyst were placed in a glass four-necked flask, and a thermometer, A stainless steel stirring bar, a flow-down condenser, and a nitrogen introduction tube were attached, and the reaction was carried out while stirring and heating in a nitrogen stream in a mantle heater. The progress of this reaction was followed by measuring the acid value. When the predetermined acid value was reached, the reaction was terminated and cooled to room temperature to obtain polyester resin A. The physical properties of the polyester resin A are shown below. Number average molecular weight (Mn): 3,300, weight average molecular weight (Mw) / number average molecular weight (Mn): 4.2, glass transition point (Tg): 68.5 ° C., softening point (Tm): 110.3 C, acid value: 3.3 mgKOH / g, OH value: 28.1 mgKOH / g.

(Manufacture of pigment master batch)
Polyester resins A and C.I. I. Pigment Blue 15-3 was charged into a pressure kneader at a weight ratio of 7: 3, kneaded at 120 ° C. for 1 hour, cooled, and coarsely pulverized with a hammer mill. Pigment with a pigment content of 30 wt% A master batch was used.

(Manufacture of toner particles)
100 parts of polyester resin A, 15 parts of pigment master batch, 2.0 parts of zinc complex of salicylic acid (E-84; manufactured by Orient Chemical Co., Ltd.) as a charge control agent, oxidized low molecular weight polypropylene (100TS; manufactured by Sanyo Chemical Industries, Ltd .: softened) Melting and kneading using a product obtained by removing 2 parts of the twin screw extruder kneader (PCM-30; manufactured by Ikekai Tekko Co., Ltd.) The kneaded product thus obtained was rolled to a thickness of 2 mm with a cooling press roller, cooled with a cooling belt, and then roughly pulverized with a feather mill. Thereafter, the mixture is pulverized with a mechanical pulverizer (KTM: manufactured by Kawasaki Heavy Industries, Ltd.) to an average particle size of 10-12 μm, and further pulverized with a jet pulverizer (IDS: manufactured by Nihon Nippon Industrial Co., Ltd.) to an average particle size of 6.8 μm After classification, toner particles DC1 having a volume average particle size of 6.5 μm and an average circularity of 0.943 were obtained by using a rotor type classifier (Teplex type classifier type: 100ATP: manufactured by Hosokawa Micron). .

<Manufacture of toner>
The toner particles and external additives listed in the table were mixed using a 9 L Henschel mixer (FM10B; manufactured by Mitsui Miike Chemical Co., Ltd.) to obtain a toner. The Henschel mixer used ST blades as upper blades and AO blades as lower blades. Any toner exhibits negative chargeability.

External additive 1; hydrophobic silica having an average primary particle size of 7 nm (TS; manufactured by Cabot Corporation)
External additive 2; Hydrophobic silica having an average primary particle size of 30 nm obtained by surface-treating silica (90G; manufactured by Nippon Aerosil Co., Ltd.) with hexamethyldisilazane External additive 3; Strontium titanate having an average primary particle size of 300 nm (Titanium Industry Co., Ltd.) Made)

<Manufacture of regulated rollers>
A foam layer was formed on the outer peripheral surface of the cylindrical core metal, and a skin layer was formed by covering the outer peripheral surface with a tube to obtain a regulating roller.
Core: SUS, diameter 5mm
Low hardness foam layer; urethane foam, thickness 3.5mm
Skin layer: conductive polyamide (nylon 6), film thickness 100μm

  Specifically, a hole into which the core metal is inserted is formed in the foam of the material to be the foam layer, and the core metal with the hot melt adhesive applied to the outer peripheral surface is inserted into the hole. Subsequently, it heats and a foam and a core metal are adhere | attached through a hot-melt-adhesive. After sufficient adhesion, the foam is cut and formed to form a foam layer having a uniform thickness. Thereafter, a cylindrical tube having a predetermined length is placed on the foam layer, and the foam layer and the end of the tube are adhered with a conductive adhesive to produce a regulating roller having a diameter of 12 mm.

By selecting a foam that forms a foam layer, regulating rollers 1 to 4 having different elastic forces were obtained. The elastic force was adjusted by adjusting the amount of the foaming agent when producing the foam.
The elastic forces of the regulating rollers 1 to 4 were as follows.
Regulating roller 1; 0.8 N (density 21 kg / m ³ , bubble average diameter 1300 μm)
Regulating roller 2; 1.6 N (density 40 kg / m ³ , bubble average diameter 900 μm)
Regulating roller 3; 1.8 N (density 52 kg / m ³ , bubble average diameter 800 μm)
Regulating roller 4; 2.2 N (density 62 kg / m ³ , bubble average diameter 500 μm)
The density and the bubble average diameter in the parentheses are those of the foam used in manufacturing each regulating roller.

[Experiment A]
The relationship between the pushing amount and the linear pressure in the regulating rollers 1 to 4 was obtained. The pressure receiving member 13 of the linear pressure measuring device 15 shown in FIG. 2 was pushed into the regulating roller by a predetermined pushing amount, and the linear pressure at that time was measured.

  Each condition obtained by combining the type of the restriction roller, the pushing amount and the linear pressure in Table 2 is adopted as an evaluation condition described later.

[Experiment B]
Evaluation;
・ Charging stability (buried external additives)
The printer (magiccolor 2300DL; manufactured by Konica Minolta Co., Ltd.) was remodeled so that it could incorporate a specified regulating roller and be subjected to an endurance test under predetermined driving and evaluation conditions, and 150 g of toner was charged in the developer, and A4 vertical white paper was printed. Durability driving equivalent to 5000 sheets was performed (temperature 23 ° C., humidity 65%). The fog on the photoconductor and printed image when a blank paper image was printed after endurance driving was evaluated. The driving / evaluation conditions are the same as the conditions of the magiccolor 2300DL except that various conditions described in Table 3 are adopted.
A: No fogging occurred on either the photoconductor or the printed image;
○: Slight fogging occurred on the photoconductor, but no fogging occurred on the printed image;
Δ: More fog on the photoreceptor than rank “◯”, but not on the printed image, and there was no practical problem;
X: Not only was the fog generated on the photoreceptor, but it was also generated on the printed image, and there was a problem in practical use.

  The evaluation results when various toners are used are shown in the following table. Similar results were obtained when any of the toners 1 and 2 was used. The evaluation condition number corresponds to the evaluation condition number in Table 2.

In Table 3, the rotation direction is the rotation direction of the regulating roller.
The peripheral speed ratio is “the peripheral speed of the regulating roller / the peripheral speed of the developing roller”.
“-” Means not evaluated.

In Table 3, the bias is a bias applied to the regulating roller, and is expressed with reference to the bias shown in FIG. 4A applied to the developing roller. The developing roller bias (dotted line) shown in FIG. 4A is a DC voltage; −320 V, an AC voltage; Vpp 1400 V, a frequency of 2 kHz, and a duty ratio of 35%.
The regulation roller bias “same potential” means that a bias (solid line) shown in FIG. 4B is applied. In FIG. 4 (B), the developing roller bias (dotted line) shown in FIG. 4 (A) is also overlapped, and the regulation roller bias (solid line) and the developing roller bias (dotted line) are DC voltage and AC voltage. Vpp, frequency, and duty ratio are the same.
The regulation roller bias of “−100 V” means that the bias (solid line) shown in FIG. 4C is applied. In FIG. 4 (C), the developing roller bias (dotted line) shown in FIG. 4 (A) is also overlapped, and the regulation roller bias (solid line) and the developing roller bias (dotted line) represent the DC voltage and the AC voltage. The same except for Vpp.
The regulation roller bias “+100 V” means that the bias (solid line) shown in FIG. 4D is applied. In FIG. 4D, the developing roller bias (dotted line) shown in FIG. 4A is also overlapped, and the regulation roller bias (solid line) and the developing roller bias (dotted line) represent the DC voltage and the AC voltage. The same except for Vpp.
The regulation roller bias of “−200 V” means that the bias (solid line) shown in FIG. In FIG. 4 (E), the developing roller bias (dotted line) shown in FIG. 4 (A) is also overlapped, and the regulation roller bias (solid line) and the developing roller bias (dotted line) are DC voltage and AC voltage. The same except for Vpp.

  Charging stability can be improved by counter-rotating the regulating roller or applying a DC voltage on the same polarity side as the toner charging polarity to the regulating roller.

<Measurement method>
(Volume average particle size)
The particle size was measured with Coulter Multisizer II (Beckman Coulter, Inc.). Using Coulter Multisizer II, an interface for outputting the particle size distribution (manufactured by Beckman Coulter) and a personal computer were connected. The aperture in the Coulter Multisizer II was 50 μm, and the volume distribution of a sample of 0.99 μm or more (for example, 2 to 40 μm) was measured to calculate the particle size distribution and average particle size.
(Measurement conditions) (1) Aperture: 50 μm. (2) Sample preparation method (in the case of toner particle size): An appropriate amount of a surfactant (neutral detergent) is added to 50 to 100 ml of an electrolytic solution (ISOTON-II-pc (manufactured by Beckman Coulter)) and stirred. Add 10-20 mg of sample to be measured. This system is prepared by dispersing for 1 minute with an ultrasonic disperser. (3) The sample preparation method (in the case of the particle size of the core particles) was prepared as a measurement sample by adding an appropriate amount of the associated liquid itself to 50 to 100 ml of an electrolytic solution (ISOTON-II-pc (manufactured by Beckman Coulter)).

(Average circularity of toner particles)
The degree of circularity represented by the following formula was measured by a flow type particle image analyzer (FPIA-1000; manufactured by Toa Medical Electronics Co., Ltd.) and determined as an average value of about 10,000 toner particles.
Circularity = (circle perimeter calculated from equivalent circle diameter) / (perimeter of particle image)

(Standard deviation of circularity of toner particles)
The standard deviation of the circularity refers to the standard deviation in the circularity distribution, and the value is obtained simultaneously with the average circularity by the flow type particle image analyzer. It means that the smaller the value, the more uniform the toner particle shape.

(Softening point)
The softening point was measured using a flow tester (CFT-500; manufactured by Shimadzu Corporation). The resin is weighed in an amount of 1.0 to 1.5 g, and pressurized with a load of 180 kg / cm ² for 1 minute using a molding machine. The pressure sample was subjected to flow tester measurement under the following conditions, and the temperature at which the sample flowed out by a half amount was defined as the softening point temperature. RATE TEM (temperature increase rate): 3.0 ° C./min, SET TEMP: 50.0 ° C., MAX TEMP; 120.0 ° C., INTERVAL; 2.0 ° C., PREHEAT; 2.0 ° C., LOAD; 30.0 kgf , DIE (DIA); 1.0 mm, DIE (LENG); 1.0 mm, PLUNGER; 1.0 cm ² . The outflow start temperature was the temperature at which the sample started to flow out.

(Glass transition point)
The glass transition point was measured using a differential scanning calorimeter (DSC-200; manufactured by Seiko Denshi Kogyo Co., Ltd.). About 10 mg of resin is precisely weighed and placed in an aluminum pan. As a reference, alumina is placed in an aluminum pan, and the temperature rise temperature is 30 ° C./min. The temperature was raised from room temperature to 200 ° C. and melt-quenched, then cooled, and the temperature raised was 10 ° C./min. The measurement is performed at 20 to 150 ° C. In this temperature raising process, the shoulder value of the endothermic peak of the main peak in the temperature range of 30 to 80 ° C. was taken as the glass transition point.

(Acid value)
The acid value was expressed in mg of potassium hydroxide required to dissolve a weighed sample in an appropriate solvent and neutralize the acidic group using an indicator such as phenolphthalein.
(Hydroxy acid value)
The hydroxy value was expressed in terms of mg of potassium hydroxide necessary for treating a weighed sample with acetic anhydride, hydrolyzing the resulting acetylated product, and neutralizing free acetic acid.

(Molecular weight)
The molecular weight was determined by polystyrene conversion using gel permeation chromatography (807-IT type; manufactured by JASCO Corporation) and using tetrahydrofuran as a carrier solvent.

1 is a schematic cross-sectional configuration diagram of an example of a developing device of the present invention. A schematic sectional view perpendicular to the axial direction of a linear pressure measuring device is shown. (A) and (B) both show schematic schematic diagrams for explaining the pressing amount of the regulating roller. (A) is a schematic diagram showing a bias applied to the developing roller at the time of evaluation of the example, and (B) to (E) are schematic diagrams showing a bias applied to the regulating roller at the time of evaluation of the example.

Explanation of symbols

  1: toner regulating member, 2: 2a: 2b: developing roller, 3: toner, 4: electrostatic latent image carrier, 5: toner supply roller, 10: developing device, 11: aluminum roller, 12: load converter , 13: pressure receiving member, 14: surface center of pressure receiving member, 15: linear pressure measuring device.

Claims (4)

  A developing device, wherein a toner regulating roller having an elastic force of 1.8 N or less is brought into pressure contact with a developing roller so that a linear pressure is 5 to 30 N / m.   The toner regulating roller is counter-rotated with respect to the developing roller, and the peripheral speed ratio (toner regulating roller / developing roller) between the toner regulating roller and the developing roller is set to 3.00 or less. Development device.   3. The development according to claim 1, wherein a DC voltage having the same polarity as the polarity to which the toner is to be charged is applied to the toner regulating roller with reference to the DC voltage applied to the developing roller. apparatus.   A toner regulating roller having an elastic force of 1.8 N or less.

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