Abstract: In a two-component development system containing a toner and a carrier, an a-Si photosensitive member having a diameter of from 20 mm to 80 mm is used, the photosensitive member is electrostatically charged to have a surface potential of from 300 to 450 V (absolute value), and yellow, magenta, cyan and black toners are used each of which have a weight-average particle diameter of from 4.0 &mgr;m to 10.0 &mgr;m, and, under a condition that the carrier of the two-component developer has a 50% average particle diameter of from 10 &mgr;m to 80 &mgr;m and as image density (D0.5) measured usually after the toner is fixed once when the quantity of unfixed toner on a transfer medium, M/S, is 0.5 mg/cm2, have a coloring power of from 1.0 to 1.9, and in which the difference between a maximum value and a minimum value of D0.5 of yellow, magenta, cyan and black colors is form 0 to 0.5. This makes it possible to obtain high-quality images in a high image density and a superior color reproduction.

Abstract: A magnetic carrier exhibiting excellent durability against mechanical impact as exerted by vibration and capable of exhibiting a stable charging performance in electrophotography is provided.

Abstract: An image forming method has the steps of

Abstract: In a two-component development system containing a toner and a carrier, an a-Si photosensitive member having a diameter of from 20 mm to 80 mm is used, the photosensitive member is electrostatically charged to have a surface potential of from 300 to 450 V (absolute value), and yellow, magenta, cyan and black toners are used each of which have a weight-average particle diameter of from 4.0 &mgr;m to 10.0 &mgr;m, and, under a condition that the carrier of the two-component developer has a 50% average particle diameter of from 10 &mgr;m to 80 &mgr;m and as image density (D0.5) measured usually after the toner is fixed once when the quantity of unfixed toner on a transfer medium, M/S, is 0.5 mg/cm2, have a coloring power of from 1.0 to 1.9, and in which the difference between a maximum value and a minimum value of D0.5 of yellow, magenta, cyan and black colors is form 0 to 0.5. This makes it possible to obtain high-quality images in a high image density and a superior color reproduction.

Abstract: A carrier for use in electrophotography has carrier cores comprising a binder resin and metal compound particles dispersed therein, and a coating resin for coating the surfaces of the carrier cores. Water adsorption TH2O-H (% by weight) after the carrier has been left in an environment of 30° C./80%RH, water adsorption TH2O-L (% by weight) after the carrier has been left in an environment of 23° C./5%RH, and particle surface area Sm (cm2/g) of the carrier satisfy the following relationship: 6.00×10−6≦TH2O-H/(100×Sm)≦1.50×10−5, and 1.00×10−6≦TH2O-L/(100×Sm)≦5.50×10−6.

Abstract: A toner for developing electrostatic images. having a uniform composition and uniform performances over varying sizes of toner particles is constituted by (a) a binder resin, (b) a long-chain alkyl compound and (c) a specific azo-type iron complex. The long-chain alkyl compound is represented by the following formula (1), (2) or (3): CH3&Parenopenst;CH2&Parenclosest;xCH2OH  (1),  CH3&Parenopenst;CH2&Parenclosest;yCH2COOH (3), wherein x and y independently denote an average value in the range of 35-150.

Abstract: A non-metallic black toner is disclosed. The toner has toner particles containing at least a binder resin, a carbon black and an organometallic compound, and an external additive. The toner particles contain 10 to 200 ppm of at least one kind of alkali metal element and at least one kind of organometallic compound. The toner particles further contain a polyester resin. The non-metallic black toner has a weight-average particle diameter of 4 to 11 &mgr;m, the following loss tangents tan &dgr; shown by dielectric loss factor ∈″/dielectric constant ∈′ at frequencies of 5×104 Hz and 105 Hz: tan &dgr; (5×104 Hz)≦0.0125 tan &dgr; (105 Hz)≦0.0105, a Carr's flowability index of 50 or more, and a Carr's floodability index of 65 or more. Also, an image forming method is disclose using the black toner.

Abstract: A two-component type developer has a negatively chargeable toner having toner particles and an external additive and a magnetic-fine-particle-dispersed resin carrier. The magnetic-fine-particle-dispersed resin carrier has composite particles containing at least inorganic compound particles and a binder resin. The inorganic compound particles have been surface-treated with a lipophilic-treating agent having at least one type of functional group (A) selected from the group consisting of an epoxy group, an amino group, a mercapto group, an organic acid group, an ester group, a ketone group, an alkyl halide group and an aldehyde group, or a mixture of the agent. The composite particles have been surface-coated with at least one type of coupling agent having at least one type of functional group (B) different from the functional group (A) the lipophilic-treating agent.

Abstract: A magnetic carrier constituting a two-component developer for use in an electrophotographic image forming method is formed of a carrier core comprising a first resin and magnetic fine particles dispersed in the first resin, and a second resin surface-coating the carrier core. (a) The magnetic carrier has a true specific gravity of 2.5-4.5, a magnetization .sigma..sub.1000 as measured in a magnetic field of 1000.times.(10.sup.3 /4.pi.).multidot.A/m (1000 oersted) of 15-60 Am.sup.2 /kg (emu/g), a residual magnetization .sigma..sub.r of 0.1-20 Am.sup.2 /kg (emu/g) and a resistivity of 5.times.10.sup.11 -5.times.10.sup.15 ohm.cm. (b) The first resin has a polymer chain including a methylene unit (--CH.sub.2 --). (c) The second resin has at least a fluoro-alkyl unit, a methylene unit (--CH.sub.2 --) and an ester unit.

Abstract: An image-forming method uses an assembly having a first toner replenishing hopper, a toner storage room, a nonmagnetic cylindrical rotating member provided with a first mixed magnetic field-generating device, a first magnetic blade, a nonmagnetic cylindrical development sleeve provided with a second fixed magnetic field generating device, a second magnetic blade, an electrostatic image holding member, a cleaning device and a second toner-replenishing hopper. At least certain of the foregoing components are set to have specific positional relationships with one another so that the recovered magnetic toner is efficiently reused together with the fresh magnetic toner.

Abstract: A toner for developing electrostatic images includes a binder resin, a specific long-chain alkyl compound and a specific azo iron complex. The long-chain alkyl compound contains a terminal --OH or --COOH group and from about 35 to 150 (--CH.sub.2 --) groups. The azo iron complex has a cation including 75-98 mol. % of ammonium ion and another ion which is hydrogen, sodium, potassium or mixtures thereof.

Abstract: The toner for developing an electrostatic image has toner particles containing at least binder resin and colorant. The resin components of a range of 2,000 to 100,000 in molecular weight, prepared by preparatory liquid chromatograph from the binder resin, exhibit an M/S ratio of 200 or greater and are 50% to 90% in abundance. The M and S stand for a weight average molecular weight (M) measured by means of light scattering method and an inertia radius (S) measured by means of light scattering method, respectively.

Abstract: A toner for developing an electrostatic image is constituted by toner particles containing at least a binder resin and a colorant, and particles containing at least one double oxide. The double oxide includes a double oxide (A) represented by the following formula (1):M.sub.a Si.sub.b O.sub.c (1),wherein M denotes a metallic element selected from the group consisting of Sr, Mg, Zn, Co, Mn and Ce; a is an integer of 1-9; b is an integer of 1-9; and c is an integer of 3-9. The above particles including a double oxide (A) are effective in improving flowability and triboelectric chargeability of the toner and providing a resultant image with excellent image qualities.

Abstract: An image forming method has the steps of forming a toner image by developing through a developing means a latent image formed on a latent image bearing member; transferring the toner image formed, from the latent image bearing member to a transfer medium through a transfer means to which a bias is applied; cleaning the latent image bearing member from which the toner image has been transferred to the transfer medium, to recover and collect the toner remaining on the latent image bearing member; and feeding the toner recovered and collected, to the developing means for reuse in the developing step. The toner has a binder resin and at least one of a magnetic powder and a colorant. The toner has a weight average particle diameter (D.sub.4) of from 4 .mu.m to 11 .mu.m; a coefficient A of variation of number-base distribution, of not more than 40, which is a coefficient represented by the formula:A=S.sub.n /D.sub.1 .times.100wherein S.sub.n represents a standard deviation of number-base distribution, and D.sub.

Abstract: A toner for developing an electrostatic image has a binder resin, a colorant and a charge control agent. The binder resin has a polyester resin having an acid value of from 15 to 40 and a hydroxyl value of 45 or less. The toner has, in its molecular weight distribution as measured by gel permeation chromatography, tetrahydrofuran-soluble matter having a weight average molecular weight Mw of 100,000 or more, having a ratio of weight average molecular weight Mw to number average molecular weight Mn, Mw/Mn, of not less than 35, containing from 70% to 94% of a low-molecular weight region component having a molecular weight of less than 150,000, containing from 1% to 10% of a medium-molecular weight region component having a molecular weight of from 150,000 to 500,000, and containing from 5% to 25% of a high-molecular weight region component having a molecular weight of more than 500,000. The high-molecular weight region component is more than the medium-molecular weight region component.

Abstract: A magnetic toner which is excellent in the low temperature fixability and the anti-offset properties is disclosed. The binder resin of the toner comprises a non-crosslinked styrene polymer, a non-crosslinked styrene copolymer or a mixture of these, and a polyolefin, wherein;the binder resin has, in its molecular weight distribution pattern measured by gel permeation chromatography (GPC), at least one maximal point (peak) in each region of a low molecular weight of from 5,000 to 20,000 and of a high molecular weight of from 200,00 to 1,000,000, where a height H1 of a maximum peak in the low molecular weight region, a height H3 of a maximum peak in the high molecular weight region and a height H2 of a minimal point between both of said peaks satisfy the relationship H1:H2:H3 of 3-25:1:1.5-12; and has a weight average molecular weight Mw and a number average molecular weight Mn in a value Mw/Mn of from 15 to 80.

Abstract: A toner for developing an electrostatic image is formed as a mixture of toner particles containing at least a binder resin and a colorant, and inorganic fine powder. The inorganic fine powder includes: (A) inorganic fine powder (A) treated at least with silicone oil, and (B) inorganic fine powder (B) comprising a composite metal oxide including at least Si as a constituent element and having a weight-average particle size of 0.3-5 .mu.m. Because of the inclusion of the two types of inorganic fine powders (A) and (B), the toner is stably provided with a high flowability and a high triboelectric charge under various environmental conditions including low-humidity to high-humidity conditions. The toner is suitably used in an image forming system including a contact-charging means, a contact-transfer means and a film (or surf)-fixing system.

Abstract: A toner for developing an electrostatic image is constituted by a resin composition and a colorant. The resin composition includes a high-softening point polyester resin (I) having a softening point of 120.degree.-180.degree. C. a low-softening point polyester resin (II) having a softening point of 80.degree.-120.degree. C., and a long-chain alkyl compound selected from the group consisting of-a long-chain alkyl alcohol principally comprising long-chain alkyl alcohol components having long-chain alkyl groups of 23 to 252 carbon atoms and a long-chain alkyl carboxylic acid principally comprising long-chain alkyl carboxylic acid components having long-chain alkyl groups of 22 to 251 carbon atoms. The resin composition preferably includes a tetrahydrofuran (THF)-soluble content providing a gel permeation chromatogram showing a weight-average molecular weight (Mw) of at least 10.sup.

Abstract: A magnetic toner composed of a binder resin and magnetic fine particles, wherein the magnetic fine particles are coated with an iron-zinc oxide on their surfaces and the magnetic fine particles have a saturation magnetization (.sigma.s) of 50 Am.sup.2 /kg or above under a magnetic field of 79.58 kA/m (1K oersted) where the product of residual magnetization (.sigma.r, Am.sup.2 /kg) and coercive force (Hc, kA/m), .sigma.r.times.Hc, is in the range between 60 and 250 (kA.sup.2 m/kg).

Abstract: A toner for developing electrostatic images comprises,(i) a binder resin,(ii) a colorant, and(iii) a compound made by a reaction of a monohydroxylic compound having a long-chain alkyl group having an alkylene group with 40 or more carbon atoms and a hydroxyl group with a carboxylic acid having a molecular weight of 1,000 or less, or a compound made by a reaction of a monocarboxylic compound having a long-chain alkyl group having an alkylene group with 40 or more carbon atoms and a carboxyl group with an alcohol having a molecular weight of 1,000 or less.