JP4923819B2 - Development device - Google Patents

Description

  The present invention relates to a developing device used by being incorporated in an image forming apparatus such as a copying machine, a printer, or a facsimile.

  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. In other words, 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, so that the toner deterioration such as the external additive is buried in the toner particle or detached from the toner particle. Happened and the image quality deteriorated. Furthermore, when a low softening point toner is used from the viewpoint of reducing the fixing energy, there arises a problem that the toner is fused to the surface of the developing roller. When fusing occurs on the surface of the developing roller, good charging and uniform thin layer formation are not performed, so that streaky unevenness occurs in the toner thin layer on the developing roller, resulting in unevenness in the image.

Although techniques for providing cooling means to prevent fusion have been reported (Patent Documents 5 to 6), there is a problem in terms of cost in installing new cooling means.
JP 2001-51503 A JP-A-9-258552 JP 2004-29357 A JP 2004-85623 A JP 2002-169375 A JP 2002-229330 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device that can sufficiently prevent fusion of the developing roller surface and obtain a high-quality image over a long period of time while suppressing toner deterioration even when a low softening point toner is used. And

The present invention is a developing device for forming a thin toner layer on the surface of a developing roller by bringing a toner regulating roller having an elastic force of 1.6 N or less into pressure contact with the developing roller so that the linear pressure is 5 to 30 N / m,
The present invention relates to a developing device having a toner softening point of 90 to 120 ° C. and a volume average particle diameter of 4.0 to 9.0 μm.

  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 can be suppressed. In addition, even if a low softening point toner is used, it is possible to sufficiently prevent the surface of the developing roller from being fused, so that a thin toner layer without streak irregularities can be formed. As a result, a high-quality image without unevenness 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 1.6 N or less, particularly 0.1 to 1.6 N, preferably 0.5 to 1.6 N, and is deformed by an external force. However, the shape is restored by removing the external force. To do. By using a regulating roller having such an elastic force, the linear pressure between the regulating roller and the developing roller can be effectively reduced to a range described later, so that toner deterioration can be suppressed and a low softening point is used. The fusing of the developing roller surface at the time can be suppressed. As a result, high quality images can be obtained over a long period of time. If a restricting roller with too large 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 below, so that the external additive is buried or detached, Toner deteriorates. Further, since the linear pressure becomes too large, the low softening point toner is fused to the developing roller surface, streaky unevenness occurs in the toner thin layer, and unevenness occurs on the image.

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 10 to 25 N / m. If the linear pressure is too small, toner deterioration can be prevented, but the basic performance of the developing device deteriorates such as 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 high, not only does external additives that cause toner deterioration or detachment occur, but also the toner fuses to the developing roller, causing streaky irregularities in the toner thin layer on the developing roller surface. Also, unevenness occurs in the image. 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, the contact between the regulating roller and the developing roller cannot be secured during driving due to dimensional error of the roller or bending of the shaft. descend. If the pushing amount is too large, toner deterioration and fusion to the developing roller are likely to occur. 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 improving toner chargeability, 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, particularly from the viewpoint of improving toner chargeability. It is preferable that it is 0.2-1.5.

  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 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 improving 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.

  The toner 3 has a softening point of 90 to 120 ° C., preferably 90 to 115 ° C., more preferably 90 to 110 ° C., and a volume average particle size of 4.0 to 9.0 μm, preferably 4 to 8 μm. Use. If the softening point is too high, it is difficult to melt at the time of fixing, so that unevenness occurs on the image and the image quality deteriorates. If the softening point is too low, toner fusing to the developing roller occurs, causing streaky unevenness in the toner thin layer on the surface of the developing roller and unevenness in the image. In addition, the heat resistance of the toner is reduced and aggregation occurs during storage. If the volume average particle size is too small, toner is likely to be fused to the developing roller, causing streaky unevenness in the toner thin layer on the developing roller surface and unevenness in the image. If the volume average particle size is too large, the chargeability is reduced and charging unevenness is likely to occur. Therefore, unevenness occurs on the image and the image quality is deteriorated.

  The softening point of the toner can be controlled by adjusting the softening point of the binder resin constituting the toner. For example, increasing the softening point of the binder resin increases the softening point of the toner. Further, for example, when the softening point of the binder resin is lowered, the softening point of the toner is lowered.

In this specification, the softening point of the toner uses a value measured by subjecting the toner to the following measuring method.
The softening point of the toner is measured using a flow tester (CFT-500; manufactured by Shimadzu Corporation). Die pore size 1 mm, flow ending point from the flow starting point when pores of a die length 1 mm, pressure 20 kg / cm ^2, a sample of 1 cm ³ under the conditions of heating rate 6 ° C. / min to melt outflow The temperature corresponding to ½ of the height is taken as the softening point.

  The softening point of a resin such as a binder resin can be measured by the same method as the toner softening point measurement method, except that the resin is subjected to the measurement method.

  The glass transition point of the toner is usually 40 to 65 ° C., particularly 50 to 60 ° C.

As the glass transition point of the toner, a value measured by subjecting the toner to the following measuring method is used.
The glass transition point of the toner is measured using a differential scanning calorimeter (DSC-200; manufactured by Seiko Denshi Kogyo Co., Ltd.). About 10 mg of toner is precisely weighed and put in an aluminum pan. As a reference, alumina is put 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 rising process, the shoulder value of the endothermic peak of the main peak in the temperature range of 30 to 90 ° C. is defined as the glass transition point.

  The glass transition point of a resin such as a binder resin can be measured by the same method as the toner glass transition point, except that the resin is subjected to the above-described measurement method.

  As the toner configuration, a known toner configuration that has been conventionally used in the field of electrostatic latent image developing toner can be used. For example, a colorant in a binder resin, a charge control agent and a release agent as necessary. A toner particle containing a mold agent or the like and having an external additive added thereto is used. The volume average particle diameter of the toner may be within the above range as the volume average particle diameter of the toner particles before the addition of the external additive, and the volume average particle diameter is not changed by the addition of the external additive.

  As the external additive, known ones commonly 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, strontium titanate, acrylic Organic fine particles such as resin, styrene resin, silicone resin, and fluororesin 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.

As the external additive, it is preferable to use first to third external additives having different BET specific surface areas from the viewpoint of chargeability and heat-resistant storage stability.
Specifically, the BET specific surface area of the first external additive is 160 to 310 m ² / g, preferably 160 to 280 m ² / g, more preferably 170 to 260 m ² / g. The first external additive has a product H1 of 175 to 440 of the addition amount (parts by weight) of the first external additive per 100 parts by weight of toner particles and the BET specific surface area (m ² / g) of the external additive, It is particularly desirable to use 180 to 440, preferably 185 to 420, more preferably 200 to 400. The amount of the first external additive is usually 0.1 to 3 parts by weight with respect to 100 parts by weight of the toner particles. The first external additive is preferably inorganic fine particles, and hydrophobic silica is particularly preferable. Use of the first external additive can improve the fluidity of the toner and the texture of the image. As the first external additive, two or more kinds of fine particles may be used. In this case, the sum of the product of the added amount and the BET specific surface area of each fine particle may be within the above range.

The BET specific surface area of the second external additive is 35 to 110 m ² / g, preferably 40 to 90 m ² / g, and more preferably 50 to 80 m ² / g. The second external additive has a product H2 of 20 to 110 of the addition amount (parts by weight) of the second external additive per 100 parts by weight of toner particles and the BET specific surface area (m ² / g) of the external additive, It is desirable to use it so that it is preferably 25 to 100, more preferably 30 to 90. The amount of the second external additive added is usually 0.1 to 2 parts by weight with respect to 100 parts by weight of the toner particles. The second external additive is preferably inorganic fine particles, and hydrophobic silica is particularly preferable. By using the second external additive, it is possible to eliminate the problem of image loss (missing) when transferring using a transfer roller. As the second external additive, two or more kinds of fine particles may be used. In this case, the sum of the products of the addition amount and the BET specific surface area of each fine particle may be within the above range.

The BET specific surface area of the third external additive is 3 to 22 m ² / g, preferably 4 to 16 m ² / g, and more preferably 5 to 15 m ² / g. The third external additive has a product H3 of 1 to 25 of the addition amount (parts by weight) of the third external additive per 100 parts by weight of toner particles and the BET specific surface area (m ² / g) of the external additive, In particular, it is desirable to use 7 to 25, preferably 10 to 25, more preferably 12 to 20. The addition amount of the third external additive is usually 0.5 to 3 parts by weight with respect to 100 parts by weight of the toner particles. The third external additive is preferably inorganic fine particles, particularly strontium titanate. By using the third external additive, filming and BS can be reduced without damaging the photoreceptor and the cleaning blade. As the third external additive, two or more kinds of fine particles may be used, and in this case, the sum of the products of the addition amount and the BET specific surface area for each fine particle may be within the above range.

When hydrophobic silica is used as the first external additive and the second external additive, hydrophobic titanium oxide may be used as the fourth external additive for fine adjustment of the toner charge amount. The BET specific surface area of the hydrophobic titanium oxide is 35 to 240 m ² / g, preferably 40 to 180 m ² / g, more preferably 50 to 150 m ² / g. The fourth external additive has a product H4 of 5 to 100 between the addition amount (parts by weight) of the fourth external additive per 100 parts by weight of the toner particles and the BET specific surface area (m ² / g) of the external additive. It is desirable to use 10 to 90, more preferably 20 to 80. The addition amount of the fourth external additive is usually 0.1 to 2 parts by weight with respect to 100 parts by weight of the toner particles.

  The total amount of external additives added to the toner is 2.0 to 6.0 parts by weight, particularly 2 to 5 parts by weight, based on 100 parts by weight of the toner particles, from the viewpoints of chargeability and heat-resistant storage stability. It is preferable.

  The toner particles are so-called kneading and pulverizing method, suspension polymerization method, emulsion polymerization method, emulsion polymerization aggregation method in which resin particles and colorant particles obtained by emulsion polymerization are aggregated and fused to obtain toner particles, emulsion dispersion It can be produced by various production methods such as a granulation method and an encapsulation method.

  The binder resin constituting the toner particles is not particularly limited. For example, styrene resin (especially styrene-acrylate resin), polyester resin, epoxy resin, vinyl chloride resin, phenol resin, polyethylene resin, polypropylene Resins, polyurethane resins, silicone resins and the like can be mentioned. In particular, when toner particles are produced by a kneading and pulverization method, the softening point of the toner tends to be about 1 to 2 ° C. lower than the softening point of the binder resin. It is preferable to select. A binder resin having a softening point of 92 to 120 ° C. is usually used.

  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, alkyl salicylic acid metal compounds, curlyx arene compounds, and boron 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.

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

<Manufacture of polyester resin>
To a glass four-necked flask equipped with a thermometer, a stirrer, a downflow condenser and a nitrogen inlet tube, polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene ( 2,2) -2,2-bis (4-hydroxyphenyl) propane, isododecenyl succinic anhydride, terephthalic acid and fumaric acid were adjusted to a weight ratio of 82: 77: 16: 32: 30 to form a polymerization initiator dibutyl Put together with tin oxide. This was reacted in a mantle heater with stirring at 220 ° C. in a nitrogen atmosphere to obtain polyester resins L1 to L5 shown in the table.

  <Manufacture of toner particles DC1>

(Manufacture of pigment master batch)
Binder resin and C.I. I. Pigment Blue 15-3 was charged into a pressure kneader at a weight ratio (resin: pigment) ratio of 7: 3 and kneaded. The kneaded product was cooled and pulverized by a feather mill to obtain a pigment master batch.

(Manufacture of toner particles DC1)
For polyester resin L4 (100 parts), 10 parts of pigment masterbatch, 2.0 parts of zinc complex of salicylic acid (E-84: manufactured by Orient Chemical Industries) as a charge control agent, oxidized low molecular weight polypropylene (100TS: Sanyo) Made by Kasei Co .; softening point 140 ° C., acid value 3.5) 1.0 part after thoroughly mixing with a Henschel mixer, after removing the discharge part of a biaxial extrusion kneader (PCM-30: Ikegai Iron Works) And then cooled after melt-kneading. The obtained kneaded product was cooled with a cooling belt and then coarsely 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 Nippon Pneumatic Industrial Co., Ltd.) to an average particle size of 6.6 μm. After powder classification, toner particles DC1 having a volume average particle size of 6.5 μm were obtained by using a rotor type classifier (Teplex type classifier type: 100ATP: manufactured by Hosokawa Micron Corporation).

<Manufacture of toner particles DC2 to DC11>
Toner particles were obtained by a method similar to the method for producing toner particles DC1, except that the polyester resins listed in Table 2 were used and that the particle size of the toner particles was controlled by adjusting the fine grinding and classification conditions.

<Manufacture of toner>
The toner particles described in Table 3 or Table 4 and the external additive are mixed using a 9 L Henschel mixer (FM10B; manufactured by Mitsui Miike Chemical Co., Ltd.), and toners used in Examples / Reference Examples / Comparative Examples are mixed. Obtained. The Henschel mixer used ST blades as upper blades and AO blades as lower blades. Any toner exhibits negative chargeability. The Tm and Tg of the toner were measured and shown in the table.

S1 represents hydrophobic silica (TS500; manufactured by Cabot Corporation) having a BET specific surface area of 225 m ² / g.
S2 represents hydrophobic silica (BET specific surface area 70 m ² / g) obtained by surface-treating silica (90G; manufactured by Nippon Aerosil Co., Ltd.) with hexamethyldisilazane (HMDS) as a hydrophobizing agent.
S3 indicates hydrophobic silica (BET specific surface area 40 m ² / g) obtained by surface-treating silica (OX50; manufactured by Nippon Aerosil Co., Ltd.) with hexamethyldisilazane (HMDS) as a hydrophobizing agent.
T1 represents hydrophobic titanium oxide (BET specific surface area 100 m ² / g) obtained by surface-treating anatase-type titanium oxide having an average primary particle size of 20 nm with isobutyltrimethoxysilane as a hydrophobizing agent in an aqueous wet process.
TSr represents strontium titanate having an average primary particle size of 350 nm and a BET specific surface area of 8 m ² / g.

<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 for forming the foam layer, the following regulating rollers having different elastic forces were obtained. The elastic force was adjusted by adjusting the amount of the foaming agent when producing the foam.
Regulation roller with elastic force of 0.8N (density 21kg / m ³ , bubble average diameter 1300μm)
Regulation roller with an elastic force of 1.4 N (density 26 kg / m ³ , bubble average diameter 1000 μm)
Regulation roller with elastic force of 1.6 N (density 40 kg / m ³ , bubble average diameter 900 μm)
Regulating roller with an elastic force of 1.8 N (density 52 kg / m ³ , bubble average diameter 800 μm)
The density and the bubble average diameter in the parentheses are those of the foam used in manufacturing each regulating roller.

<Example / Reference example / Comparative example>
The printer (magiccolor 2300DL; manufactured by Konica Minolta Co., Ltd.) was remodeled so that a predetermined regulating roller could be incorporated and an endurance test could be performed under predetermined driving / evaluation conditions. Durability driving equivalent to 5000 blank paper prints was performed (temperature 23 ° C., humidity 65%). The driving / evaluation conditions are the same as the conditions of the magiccolor 2300DL except that the various conditions shown in Tables 5 to 6 are adopted. At this time, the developing roller was pushed into the regulating roller so that the linear pressure became a predetermined value.

-Fusion The toner thin layer on the surface of the developing roller immediately after the endurance driving was removed, and the roller surface was visually observed and evaluated.
○: No fusion occurred;
Δ: Fusing occurred slightly, but no problem in practical use;
X: Fusion occurred clearly and there was a problem in practical use.

-Thin layer unevenness The toner thin layer on the surface of the developing roller immediately after the endurance driving was visually observed and evaluated.
○: No streaky unevenness in the toner thin layer;
Δ: Streaky unevenness was slightly present in the toner thin layer, but there was no practical problem;
X: Streaky unevenness was clearly present in the toner thin layer, and there was a problem in practical use.

-Toner degradation The toner surface of the toner on the developing roller immediately after endurance driving was observed and evaluated with an electron microscope.
○: An external additive was present on the toner particle surface;
Δ: External additive was present on the toner particle surface in a smaller amount than ○, but there was no practical problem;
X: There was almost no external additive on the toner particle surface, and there was a problem in practical use.

-Image unevenness After endurance driving, a half image was printed, and the printed image was visually observed and evaluated.
○: No density unevenness occurred on the image;
Δ: Slight density unevenness occurred on the image, but there was no practical problem;
X: There was a relatively large density unevenness on the image, and there was a problem in practical use.

-Heat resistance 20g of toner was put in a glass bottle and allowed to stand at a high temperature of 50 ° C for 5 hours, and then the toner was evaluated by visually checking the toner.
○: There is a little light agglomerated toner, it can be solved quickly with light force, and there is no problem in practical use;
△: Light soft agglomeration exists, but it can be solved easily with a light force and has no practical problem;
X: There is a strong agglomerate, which cannot be easily solved, and has practical problems.

In the table, 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”.

In the table, 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 of “−100V” means that the bias (solid line) shown in FIG. 4B is applied. In FIG. 4B, the developing roller bias (dotted line) shown in FIG. 4A is also superimposed, 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.

<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.

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 embodiment, and (B) is a schematic diagram showing a bias applied to the regulating roller at the time of evaluation of the embodiment.

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 that forms a thin toner layer on the surface of a developing roller by bringing a toner regulating roller having an elastic force of 1.6 N or less into pressure contact with the developing roller so that a linear pressure is 5 to 30 N / m,
A softening point of the toner is 90 to 120 ° C., a volume average particle diameter of Ri 4.0~9.0μm der,
Toner first external additive having a BET specific surface area 160~310m ² / g, a second external additive having a BET specific surface area 35~110m ² / g, and a third external additive having a BET specific surface area 3~22m ² / g Is externally attached,
The product H1 of the addition amount (parts by weight) of the first external additive per 100 parts by weight of the toner particles and the BET specific surface area (m ² / g) of the external additive is 175 to 440,
The product H2 of the amount (parts by weight) of the second external additive per 100 parts by weight of the toner particles and the BET specific surface area (m ² / g) of the external additive is 20 to 110,
Development wherein the product H3 of the amount (parts by weight) of the third external additive per 100 parts by weight of toner particles and the BET specific surface area (m ² / g) of the external additive is 1 to 25 apparatus. 2. The developing device according to claim 1, wherein the total amount of the external additive is 2.0 to 6.0 parts by weight with respect to 100 parts by weight of the toner particles. The toner regulating roller is counter-rotated relative to the developing roller, to claim 1 or 2, characterized in that the peripheral speed ratio between the toner regulating roller and the developing roller (toner regulating roller / developing roller) is 3.00 or less The developing device described. On the basis of the DC voltage applied to the developing roller, the polarity DC voltage of the same polarity side to the toner is charged, to any one of claims 1 to 3, characterized in that applied to the toner regulating roller The developing device described.

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