EP0422892A2 - Révélateur et procédé de révélation - Google Patents

Révélateur et procédé de révélation Download PDF

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Publication number
EP0422892A2
EP0422892A2 EP90311048A EP90311048A EP0422892A2 EP 0422892 A2 EP0422892 A2 EP 0422892A2 EP 90311048 A EP90311048 A EP 90311048A EP 90311048 A EP90311048 A EP 90311048A EP 0422892 A2 EP0422892 A2 EP 0422892A2
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EP
European Patent Office
Prior art keywords
carrier
developer
toner
magnetic carrier
weight
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Granted
Application number
EP90311048A
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German (de)
English (en)
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EP0422892A3 (fr
EP0422892B1 (fr
Inventor
Takatomo Fukumoto
Takashi Teshima
Kazuhiko Yamamura
Kyouya Taguchi
Hiroyuki Hazama
Takeshi Higuchi
Koji Honda
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Kyocera Mita Industrial Co Ltd
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Mita Industrial Co Ltd
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Publication of EP0422892A3 publication Critical patent/EP0422892A3/fr
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Publication of EP0422892B1 publication Critical patent/EP0422892B1/fr
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/0821—Developers with toner particles characterised by physical parameters
    • G03G9/0823—Electric parameters
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/10—Developers with toner particles characterised by carrier particles
    • G03G9/113—Developers with toner particles characterised by carrier particles having coatings applied thereto
    • G03G9/1132—Macromolecular components of coatings
    • G03G9/1135—Macromolecular components of coatings obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • G03G9/1136—Macromolecular components of coatings obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds containing silicon atoms

Definitions

  • the present invention relates to a developer for use in the electronic reproduction and the like. More particularly, the present invention relates to a two-component type developer comprising a toner and a magnetic carrier, which can provide a high-density image even when a toner having a low electroconductivity is used, and a developing process using this developer.
  • the two-component type magnetic developer there is widely used a mixture comprising a magnetic carrier composed of an iron powder or sintered ferrite particles and a toner composed of particles formed by dispersing additives such as a colorant and a charge-controlling agent in a binder resin.
  • An ordinary developing mechanism in which a developer as described above is used has a structure as shown in Fig. 1. More specifically, a box-shaped toner supply mechanism 4 is arranged on the developing mechanism 2 and a toner 6 is supplied from above. The toner 6 is fed into a developing device 10 disposed below through a supply opening 8 equipped with a feeder and is stirred together with a carrier in the developing device 10 by stirrers 12 to form a two-component type developer 14.
  • a developing sleeve (developer-supporting member) 16 equipped with many magnetic poles is arranged in the developing device 10.
  • the developer 14 having the frictionally charged toner is supplied into the developing sleeve 16 and a magnetic brush 18 of the developer is formed on the surface of the sleeve by a magnetic force.
  • the length of the magnetic brush 18 is adjusted by a brush-cutting mechanism 20, and a uniform layer of the developer is formed on the surface of the developing sleeve 16.
  • This developer layer is delivered to the nip position to a surface photosensitive layer 24 of an electrophotographic photosensitive material drum (image carrier) 22.
  • the photosensitive material drum 22 is arranged apart by a distance DD-S from the developing sleeve 16, and the developing sleeve 16 and photosensitive material 22 are rotatably supported and are driven so that the moving directions (indicated by arrows) of the sleeve 16 and the drum 22 are the same at the nip position (the rotation directions are reverse to each other).
  • a corona charger 26 connected to a variable high voltage power source 25 and an optical system 28 for the light exposure are arranged around the photosensitive material drum 22 upstream of the developing device 10 to form an electrostatic latent image having a predetermined surface voltage.
  • a bias power source 33 equipped with a voltage-adjusting mechanism 30 is connected between the photosensitive drum 22 and the developing sleeve 12 so that an optional value voltage (bias voltage)which has the same polarity as that of the surface voltage and is lower than the surface voltage is applied onto the photosensitive layer 24.
  • a transfer mechanism 34 for transferring a toner image to a copying machine is arranged around the photosensitive layer 24 downstream of the developing zone.
  • the developer 14 forms the magnetic brush 18 on the developing sleeve 16 and at the nip position, this magnetic brush 18 reacts with the electrostatic latent image of the photosensitive layer 24 to form a visible image of the toner on the photosensitive layer 24.
  • the electric resistance (the inverse number of the electroconductivity) of titanium oxide used for a white toner or coloring toner or a coloring pigment is higher than that of a black pigment such as carbon and its charge quantity tends to increase, and it sometimes becomes impossible to maintain the image density (ID) of the toner image at a high level.
  • a black pigment such as carbon
  • ID image density
  • the amount coated of the resin should be controlled to less than 0.01 %.
  • the amount coated of the resin is small, the surface of the carrier core is not sufficiently covered and protected, and there is a risk of contamination of the toner by oxidation of the carrier core or the like.
  • the obtained image is yellowish and the whiteness is insufficient.
  • the change of the resistance value of the developer relative to the toner concentration (T/D) (the weight ratio of the toner to the two-component type developer) is large, and if only the T/D value is a little decreased, blanking is caused in the image (the phenomenon that a white portion to which the toner is not fixed is formed in the solid image area). It is considered that blanking will be prevented by increasing the particle size of the carrier. However, if the particle size of the carrier is excessively increased, the image quality is degraded and the consumption of the toner increases.
  • the organic photosensitive material which has a good processability and is advantageous in the manufacturing cost and has a large freedom of the design of functions is recently used as the photosensitive material for the electrophotography.
  • the organic photosensitive material includes a negatively chargeable type and a postively chargeable type. Since the negatively chargeable type often induces contamination of the copying environment, use of the positively chargeable photosensitive material (OPC) is now expected.
  • the residual voltage is apt to become larger than in the conventional Se type photosensitive material, and therefore, in the case where the positively chargeable photosensitive material is used, the bias voltage should be maintained at a level higher than 250 V. Elevation of the bias voltage increases the charge repulsion between the magnetic carrier and the developing sleeve. Accordingly, when an image is formed by using a positively chargeable organic photosensitive material and a white toner or color toner, prevention of carrier dragging and improvement of the image quality are required.
  • Another object fo the present invention is to provide a developer which can give a high-density image without such disadvantages as blanking, random spot-like transfer of the toner and carrier dragging even if a white toner or color toner having a low electroconductivity is used.
  • Still another object of the present invention is to provide a white developer capable of giving a clear and sharp image.
  • Still another object of the present invention is to provide a developer which is preferably applied to a positively chargeable organic photosensitive material.
  • a developer comprising a developer toner having an electroconductivity lower than 3.5 x 10 -10 S/cm and a magnetic carrier coated with an amino group-containing silicone resin.
  • the electroconductivity of the toner is in the range of from 2.0 x 10- 10 to 3.0 x 10- 10 S/cm and the current value of the magnetic carrier is in the range of from 0.1 to 70 nA.
  • the amount of the coating resin is 0.01 to 0.5% by weight based on the carried core.
  • the diameter Dso of the weight average particle size corresponding to 50% of the weight of entire carrier particles in the magnetic carrier is in the range of from 70 to 120 am.
  • a white toner comprising titanium oxide can be used for the developer of the present invention.
  • a developing process which comprises feeding a two-component type developer comprising a developer toner having an electroconductivity lower than 3.5 x 10- 10 S/cm and a magnetic carrier coated with an amino-group-containing silicone resin between a developer carrier and an electrostatic image carrier, to which a bias voltage of at least 250 V is applied to effect development.
  • the distance between the electrostatic image carrier and the developer carrier is adjusted to less than 1.2 mm.
  • the current value of the magnetic carrier is adjusted to 0.1 to 70 ⁇ A.
  • the diameter Dso of the weight average particle size corresponding to 50% of the weight of entire carrier particles in the magnetic carrier is adjusted to 70 to 120 ⁇ m.
  • the diameter D 50 of the weight average particle size corresponding to 50% of the weight of entire carrier particles in the magnetic carrier is adjusted to 70 to 90 ⁇ m and an Se type photosensitive material is used as the electrostatic image carrier.
  • the diameter D 50 of the weight average particle size corresponding to 50% of the weight of entire carrier particles in the magnetic carrier is adjusted to 80 to 120 u.m and a positively chargeable organic photosensitive material is used as the electrostatic image carrier.
  • the present invention is based on the finding that if a developer is formed by combining a toner having a low electroconductivity with a magnetic carrier coated with an amino group-containing silicone resin, an image having a good quality and a high density can be formed without occurrence of any trouble or disadvantage in the coated carrier.
  • the present invention is also based on the finding that if the particle size of the magnetic carrier coated with the above-mentioned coating resin is uniformly adjusted within a specific range, occurrence of carrier dragging and random spot-like transfer of the toner, which are readily caused on reduction of the resistance of the carrier, can be prevented.
  • the electroconductivity is lower than 3.5 x 10 -10 , especially lower than 3.0 x 10 -10 .
  • This reduction of the electroconductivity of the toner is due to the presence of colorants in the toner.
  • Many colorants for toner satisfying the above requirement of the low electroconductivity are present and available as the organic pigment, and therefore, colorants can be freely selected over a broad range.
  • the range of selection of colorants is narrow and a desirable color can hardly be obtained.
  • toner pigments can be freely selected and the range of the color of the developer can be broadened.
  • the electroconductivity of the toner is lower then 3.5 x 10 -10 S/cm, especially 2.0 x 10- 10 to 3.0 x 10 -10 S/cm, when this toner is used in combination with an ordinary carrier, the transferability is degraded by increase of the charge quantity per unit weight, and a high-density image can hardly be obtained.
  • an amino group-containing silicone resin in order to moderate this charge of the charge quantity which is due to the low electroconductivity, it is important that an amino group-containing silicone resin should be used as the coating resin for the magnetic carrier.
  • the amino group-containing silicone resin reduces the resistance of the magnetic carrier, as compared with the resistance attained by the convention coating resin. If this magnetic carrier is stirred with the toner having a low electroconductivity, increase of the charge quantity in the toner is controlled, and the toner can be supplied to the photosensitive material (electrostatic image carrier) in the appropriately charged state.
  • Example 1 As is apparent from the results shown in Example 1 and Comparative Example 1 given hereinafter, even if a developer comprising a carrier coated with an amino group-containing silicone resin is used for a long time, yellowing of the image is not caused but a high density can be maintained. It is preferred that the coating amount of the amino group-containing silicone resin be 0.05 to 5% by weight based on the carrier core.
  • Fig. 2 shows the appropriate charge quantity of the magnetic carrier found for the use of the toner having a low electroconductivity.
  • the amount coated of the resin can be 0.05% by weight at largest or smaller.
  • the magnetic carrier coated with an amino group-containing silicone resin even if the coating amount is increased to 0.1% by weight, no problem arises in connection with the charge quantity. Accordingly, in the case where an amino group-containing silicone resin is used as the coating resin for the magnetic carrier, the charge quantity of the magnetic carrier is reduced and a satisfactory protecting coating layer can be formed on the carrier core. This reduction of the charge quantity of the magnetic carrier by the use of the specific coating resin controls the increase of the charge quantity of the toner, and the amount coated of the coating resin can be increased.
  • the current value, described hereinafter, of the magnetic carrier has a close relation to the carrier material and the amount coated of the resin. It is preferred that the current value of the magnetic carrier be adjusted to 0.1 to 70 1 lA, especially 0.5 to 3 ⁇ A when an Se type photosensitive material is used or 30 to 40 uA when a positively chargeable organic photosensitive material is used. In case of a developer satisfying this requirement, reduction of the density, such as blanking, is not found in the formed image, and an excellent image having a high density can be obtained.
  • by the current value is meant the current value observed when the carrier is connected to a direct current power source of 200 V in the state where a magnetic brush is formed on the developing speed and is moved.
  • blanking means the phenomenon that in the solid image area of the electrostatic latent image, the toner is not transferred to a certain part because of the adhesion of the carrier to the drum or the like.
  • the particle size of the carrier be adjusted so that the diameter Dso of the weight average particle size corresponding to 50% of the weight of entire carrier particles is 70 to 120 I lm, especially 70 to 90 u.m when an Se type photosensitive material is used or 80 to 120 um when a positively chargeable organic photosensitive material is used, and that the carrier having the particle size thus adjusted be coated with the above-mentioned coating resin.
  • the particle size of the carrier is adjusted within the above-mentioned range, blanking, random spot-like transfer of the toner and carrier dragging are hardly-caused. If the particles size of the magnetic carrier is below the above-mentioned range, also because of the low resistance of the carrier, carrier particles having a relatively small particle size induce blanking, random spot-like transfer of the toner and carrier dragging. On the other hand, if the particle size of the carrier exceeds the above range, the consumption of the toner increases.
  • the diameter D 50 of the weight average particle size corresponding to 50% of entire carrier particles is determined as follows.
  • the weight of the carrier is counted in order from particles having a small particle size, and when the counted weight reaches 50% of the entire weight, the median particle size of the carrier is determined as the diameter D so .
  • Sieves having a predetermined mesh size are used for this counting.
  • Fig. 3 shows the relation between the bias voltage and the state of carrier dragging, observed with respect to the developer comprising the conventional carrier and the developer comprising the carrier of the present invention.
  • the particle size is adjusted in the above-mentioned manner and the content of particles having a size smaller than 250 mesh is adjusted below 8% by weight.
  • the developer can be used under a bias cottage of at least 250 V, especially at least 280 V. Elevation of the bias voltage results in diminishment of the influence of the residual voltage. Namely, if the residual voltage is as high as at least about 150 V, the photosensitive material provides an excellent image quality without occurrence of carrier dragging.
  • the photosensitive material having such a high residual voltage there can be mentioned a positively chargeable photosensitive material (OPC), and the OPC has conditions under which the developer of the present invention is preferably used.
  • OPC positively chargeable photosensitive material
  • the development voltage difference that is, the difference between this voltage and the surface voltage
  • the development has to be conducted under a low voltage.
  • the image density is degraded.
  • DD-S width smaller than 1.2 mm, especially smaller than 1.0 mm
  • the developer of the present invention is a two-component type developer comprising a magnetic carrier and a toner.
  • the magnetic carrier, the toner and the developer will now be described in order.
  • ferrite particles coated with an amino group-containing silicone resin are preferably used as the magnetic carrier, and it is preferred that the particle size distribution be adjusted in the above-mentioned manner.
  • the amino group-containing silicone resin is a silicone resin containing an amino group, and it is preferred that the content of the amino group be 0.1 to 10% by weight, especially 0.1 to 5% by weight.
  • the amount of the resin coated on ferrite particles is preferably 0.01 to 1.0% by weight, especially preferably 0.02 to 0.7% by weight. If the amount coated of the resin is below this range, corrosion of the surfaces of the ferrite particles cannot be sufficiently prevented, and if the amount coated of the resin exceeds the above-mentioned range, the charge quantity of the magnetic carrier increases and no good results can be obtained.
  • amino group-containing silicone resin there can be mentioned an alkylamine silicone resin and aromatic amine silicone resins, and an aromatic amine silicone resin such as a benzylamine silicone resin is especially preferably used.
  • a ferrite can be mentioned as a specific example of the magnetic carrier, and sintered ferrite particles composed of at least one member selected from the group consisting of zinc iron oxide (ZnFe 2 0 4 .), yttrium iron oxide (Y 3 Fe 5 O 12 ), cadmium iron oxide (CdFe 2 0 4 .), gadolinium iron oxide (Gd 3 Fe 5 O 12 ), lead iron oxide (PbFei 2 0i 9 ), nickel iron oxide (NiFe 2 0 a .), neodium iron oxide (NdFeO s ), barium iron oxide (BaFe 12 O 19 ), magnesium iron oxide (MgFe 2 0 4 .), manganese iron oxide (MnFe 2 0 4 ) and lanthanum iron oxide (LaFeOs are used.
  • a soft ferrite comprising at least one member, preferably at least two members, selected from the group consisting of Cu, Zn, Mg, Mn and Ni,
  • the resin-coated magnetic carrier particles should have a spherical shape, and it is important that the carrier particles should satisfy the above-mentioned requirement of the diameter D 50 of the weight average particle size corresponding to 50% of the weight of entire particles.
  • This adjustment of the particle size can be performed according to a known method, and this adjustment can be carried out at the step of sintering ferrite or after coating with the amino group-containing silicone resin.
  • the difference between the diameter D 25 of the weight average particle size corresponding to 25% of the weight of entire carrier particles and the diameter D 75 of the weight average particle size corresponding to 75% of the weight of entire carrier particles is adjusted to 0 to 20 ⁇ m simultaneously with the above-mentioned adjustment of the particles size of the carrier particles, the particles size distribution becomes sharper, and even if the DD-S width is further reduced from 1 mm, carrier dragging is not caused. Moreover, even in the state where the bias voltage is high, carrier dragging can be prevented. In the magnetic carrier having the above-mentioned particle size distribution, the image density can be increased. In the case where the photosensitive material and the developing sleeve are of the drum type, because of increase of the lower limit of the particle size by sharpening of the particle size distribution, the torque is reduced and the sliding contact force of the drum is reduced.
  • the content of fine particles having a size smaller than 250 mesh be as low as possible, that is, lower than 8% by weight, especially lower than 5% by weight.
  • carrier dragging is sufficiently prevented even under a high bias voltage, and an effect of controlling fogging can be attained as an additional effect.
  • the magnetic carrier having a saturation magnetization of 50 to 70 emu/g, especially 55 to 65 emu/g, is used.
  • This range of the saturation magnetization is lower than the saturatization magnetization range of the carrier for the conventional developer.
  • this magnetic carrier promotes softening of the magnetic brush, which results in reduction of the drum stress.
  • This saturation magnetization is preferred when the DD-S width is smaller than 1.2 mm, especially smaller than 1.0 mm.
  • the flowability of the carrier used in the present invention be 15 to 35 sec/50 g, especially 20 to 30 sec/50 g.
  • the current value of the magnetic carrier has a close relation to the carrier material and the amount coated of the resin, and it is preferred that the current value of the magnetic carrier be in the range of from 0.1 to 70 nA.
  • the current value can be measured by a measurement apparatus shown in Fig. 4. Referring to Fig. 4, a direct current power source (200 V) 62 is connected in series to a developing box 64, a resistor 66 of 10 ka and a resistor 68 of 1 M g , and a voltage meter 69 is arranged in the resistor 66 of 10 ka.
  • a magnet drum 70 assumed as the developing sleeve and a photosensitive material drum 72 are arranged in the developing box 64, and a magnetic carrier layer 74 is disposed between the two drums.
  • the distance between the magnet drum 70 and the photosensitive material drum 72 is adjusted to 4.5 mm.
  • the magnet drum and photosensitive material drum are rotated, and the current value is determined by dividing the measured value of the voltage meter 69 by the resistance value of the resistor 66.
  • the toner used in the present invention is formed by incorporating a colorant and a charge controlling agent, and optionally other known toner additives, into a binder resin, and has an electroconductivity lower than 3.5 x 10- 10 S/cm, especially 2.0 x 10 -10 to 3.0 x 10 -10 S/cm.
  • a binder resin for a toner, a colorant, a charge controlling agent and other toner additives are appropriately selected and combined, so that the above requirement is satisfied.
  • a styrene resin, an acrylic resin, a styrene/acrylic copolymer resin, a polyester resin, a silicone resin, a polyurethane resin, a polyamide and a modified resin are generally used as the binder resin.
  • a styrene/acrylic copolymer resin is one of preferred binder resins. It is preferred that the styrene monomer (A)/acrylic monomer (B) weight ratio be in the range of from 50/50 to 90/10, especially from 60/40 to 85/15. In general, a resin having an acid value of from 0 to 25 is preferably used. From the viewpoint of the fixing property, it is preferred that the resin should have a glass transition temperature (Tg) of 50 to 65 C.
  • the colorants are roughly divided into white, cyan, magenta and yellow pigments. It is preferred that the colorant be incorporated in an amount of 1 to 20 % by weight based on the binder resin. Specific examples of the colorant that can be used in the present invention are described below.
  • C.I. Pigment Red 81 As the magenta type colorant, there can be mentioned C.I. Pigment Red 81, C.I. Pigment Red 122, C.I. Pigment Red 57, C.I. Solvent Red 49, C.I. Solvent Red 19, C.I. Solvent 52, C.I. Basic Red 10 and C.I. Disperse Red 15.
  • C.I. Pigment Blue 15 As the cyan type colorant, there can be mentioned C.I. Pigment Blue 15, C.I. Pigment Blue 16, C.I. Solvent Blue 25, C.I. Solvent Blue 55, C.I. Solvent Blue 70, C.I. Direct Blue 86 and C.I. Direct Blue 25.
  • the yellow type colorant there can be mentioned C.I. Pigment Yellow 17, C.I. Pigment Yellow 12, C.I.
  • Pigment Yellow 1 C.I. Pigment Yellow 97, C.I. Pigment Yellow 138, C.I. Pigment Yellow 12, C.I. Pigment Yellow 73, C.I. Pigment Yellow 13, C.I. Solvent Yellow 29, C.I. Solvent Yellow 162 and C.I. Solvent Yellow 93.
  • white pigment there can be mentioned zinc flower, titanium oxide, antimony white and zinc sulfide, and titanium oxide is especially preferably used.
  • charge controlling agents for example, oil-soluble dyes such as Nigrosine Base (Cl 50415), Oil Black (Cl 26150) and Spiron Black, metal salts of naphthenic acid, fatty acids, soaps and resin acid soaps, can be optionally used as the charge controlling agent.
  • oil-soluble dyes such as Nigrosine Base (Cl 50415), Oil Black (Cl 26150) and Spiron Black
  • metal salts of naphthenic acid fatty acids, soaps and resin acid soaps
  • the particle size of toner particles is 8 to 14 ⁇ m, especially 10 to 12 ⁇ m, as the median size based on the volume, measured by a Coulter counter.
  • the shape of the toner particles may be an indeterminate shape formed through melt kneading and pulverization, or a spherical shape formed by dispersion or suspension polymerization.
  • the flowability of the toner can be improved by sprinkling the surface of the toner with a known surface-treating agent such as finely divided hydrophobic silica or resin powder.
  • the above-mentioned magnetic carrier and toner be mixed at a weight ratio of from 99/1 to 90/10, especially 98/2 to 95/5. It also is preferred that the initial charge quantity of the developer, as measured by the blow-off method, be 5 to 25 ⁇ c/g, especially 10 to 20 I lc/g, and that the loose apparent specific gravity be 1.7 to 2.1 g/cm 3 , especially 1.8 to 2.0 g/cm 3 .
  • the developer of the present invention is used under ordinary development conditions customarily adopted in the art. In order to especially improve the image density, it is preferred that the developer of the present invention be used under such development conditions that the distance DD-S between the image carrier and the developer carrier is smaller than 1.2 mm and the development voltage difference is smaller than 500 V.
  • the image carrier and the developer carrier in the developing device used may be of the plane type, or they may be of the drum type as shown in Fig. 1, and the type is optional so far as DD-S is within the above-mentioned range.
  • the developer of the present invention gives an image having an excellent gradient and an excellent image density even by low-voltage development, and if the above-mentioned requirements for the carrier are additionally satisfied, carrier dragging and other troubles are not caused. Furthermore, it is preferred that with diminishment of the DD-S width, the brush cut length be adjusted to 0.5 to 1.5 mm, especially 0.7 to 1.2 mm.
  • the developer of the present invention is used in the state where the development voltage difference is smaller than 500 V, especially smaller than 480 V. Accordingly, in the case where a surface voltage of 750 to 850 V is applied to the photosensitive material drum, a bias voltage of 250 to 350 V can be applied to the photosensitive material drum and the like. If the bias voltage is thus elevated, the photosensitive material drum can be used even if the residual voltage is higher than about 150 V, especially about 200 V.
  • the developer is preferably used for a positively chargeable photosensitive material (OPC).
  • the positively chargeable photosensitive material comprises a charge-generating material and a charge-transporting material, which are mixed mainly in one layer, and therefore, an electron and a hole migrate in this one layer and one of them acts as a trap, with the result that the residual voltage tends to increase.
  • This photosensitive material should have a bias voltage of at least 250 V or at least 280 V under certain circumstances.
  • the developer of the present invention can form an excellent image even under such a high bias voltage, and carrier dragging is not caused.
  • a photosensitive material formed by combining a known charge-generating material with a known charge-transporting material can be used as the positively chargeable photosensitive material.
  • An organic photosensitive material previously proposed in Japanese Patent Application No. 62-277158 is especially preferably used as the positively chargeable photosensitive material.
  • the developer of the present invention is advantageously used for the development using an organic photosensitive material which is often used recently, especially a positively chargeable organic photosensitive material.
  • Spherical ferrite carriers coated with an amino group-containing silicone resin or an acrylic polymer were used as the magnetic carrier.
  • the physical properties of the carriers are shown in Table 1.
  • the amino group-containing silicone resin was N- ⁇ -(aminoethyl)- ⁇ -aminopropyltrimethoxysilane, H 2 NC 2 H 4 NHC 3 H 6 Si(OCH) 3 ) 3 , KBM 603 supplied by Shinetsu Silicone (Toray Silicone SH6020).
  • Toners having the known particle size, pigment component and electroconductivity were used.
  • the physical properties of the toners are shown in Table 1.
  • Developers were formed by mixing the toner and carrier at a weight ratio of 4.5/95.5.
  • the basic physical properties of the developers are shown in Table 1.
  • the DD-S width, the brush cut length, the development voltage difference, the bias voltage and the photosensitive material are shown in Table 1.
  • Example 2 In the developer used in Example 1, the coating amount of the amino group-containing silicone resin was charged to examined the influence of the coating amount of the resin. The development conditions were the same as in Example 1. The obtained results are shown in Table 2.
  • the amount coated of the coating resin was smaller than 0.01% by weight, the solid image area became uneven, and the durability of the developer was poor. On the other hand, if the amount coated of the coating resin was larger than 0.5% by weight, the image density became insufficient.
  • the current value of the carrier was changed in the developer of Example 3 and the development was carried out under the same conditions as in Example 3. Incidentally, the current value of the carrier was charged by adjusting the apparent density while keeping the amount coated of the coating resin constant. The obtained results are shown in Table 3. If the current value was smaller than 0.5 ⁇ A, the image density became insufficient, and if the current value was larger than 3.0 u.A, fogging was caused.
  • the current value was changed in the developer of Example 2 and the development was carried out under the same developing conditions as in Example 2.
  • the current value of the carrier was changed by adjusting the apparent density while keeping the amount coated of the resin constant. The obtained results are shown in Table 3. If the current value was smaller than 30 ⁇ A, the image density was insufficient, and if the current value was larger than 40 ⁇ A, the solid image area became uneven.
  • the particle size of the carrier was changed in the developer of Example 3, and the development was carried out under the same conditions as in Example 3.
  • the obtained results are shown in Table 4. If the diameter D 50 was smaller than 70 ⁇ m, the image density was insufficient, and if the diameter D 50 was larger than 90, fogging was caused.
  • the particle size of the carrier was changed in the developer of Example 1, and the development was carried out under the same conditions as in Example 1.
  • the obtained results are shown in Table 4. If the diameter Dso was smaller than 80 ⁇ m, the image became uneven, and if the diameter Dso was larger than 120 ⁇ m, fogging was caused.
  • Example 1 By using the developer of Example 1, the development was carried out under the same conditions as in Example 1 except that the bias voltage was changed as shown in Table 5. The obtained results are shown in Table 5. If the bias voltage was lower than 250 V, fogging was caused.
  • Example 2 By using the developer of Example 1, the development was carried out under the same conditions as in Example 1 except that the DD-S width was changed as shown in Table 5. The obtained results are shown in Table 5. If the DD-S width was larger than 1.2 mm, the image density was insufficient.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Developing Agents For Electrophotography (AREA)
  • Magnetic Brush Developing In Electrophotography (AREA)
EP19900311048 1989-10-09 1990-10-09 Révélateur et procédé de révélation Expired - Lifetime EP0422892B1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP26224389 1989-10-09
JP262243/89 1989-10-09
JP49513/90 1990-03-02
JP2049513A JP2648221B2 (ja) 1989-10-09 1990-03-02 白色トナーを用いての磁気ブラシ現像方法

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EP0422892A2 true EP0422892A2 (fr) 1991-04-17
EP0422892A3 EP0422892A3 (fr) 1991-05-29
EP0422892B1 EP0422892B1 (fr) 1995-02-15

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JP (1) JP2648221B2 (fr)
DE (1) DE69016913T2 (fr)
ES (1) ES2071037T3 (fr)

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EP0915386A2 (fr) * 1997-11-11 1999-05-12 Brother Kogyo Kabushiki Kaisha Révélateur coloré
US9897935B2 (en) 2015-03-25 2018-02-20 Konica Minolta, Inc. Image forming method, electrostatic charge image developer set, and image forming apparatus

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3497396B2 (ja) * 1998-12-24 2004-02-16 京セラミタ株式会社 静電潜像現像用キャリア及び静電潜像現像剤

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GB2119108A (en) * 1982-03-15 1983-11-09 Xerox Corp Coated carrier for electrostatographic toner
JPS6350866A (ja) * 1986-08-21 1988-03-03 Minolta Camera Co Ltd 静電潜像現像剤用キヤリア

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0915386A2 (fr) * 1997-11-11 1999-05-12 Brother Kogyo Kabushiki Kaisha Révélateur coloré
EP0915386A3 (fr) * 1997-11-11 1999-10-20 Brother Kogyo Kabushiki Kaisha Révélateur coloré
US9897935B2 (en) 2015-03-25 2018-02-20 Konica Minolta, Inc. Image forming method, electrostatic charge image developer set, and image forming apparatus

Also Published As

Publication number Publication date
EP0422892A3 (fr) 1991-05-29
DE69016913T2 (de) 1995-06-08
JP2648221B2 (ja) 1997-08-27
ES2071037T3 (es) 1995-06-16
JPH03200978A (ja) 1991-09-02
EP0422892B1 (fr) 1995-02-15
DE69016913D1 (de) 1995-03-23

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