JP2009223260A - Toner and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner having sufficient high-speed properties, high image quality, high durability and high environmental stability. <P>SOLUTION: The toner is used in an image forming method comprising: repeating formation of a toner image on a first image carrier and primary transfer of the toner image onto a second image carrier, for each of toner images of multiple colors and superposing the toner images of multiple colors on the second image carrier; then secondarily transferring the toner images together onto a transfer material to form a color image; and applying charges through a fixed charging brush to the transfer residual toner remaining on the second image carrier after the secondary transfer, resulting in reverse transfer of the toner from the second image carrier onto the first image carrier; and further recovering the toner by a cleaning device of the first image carrier. The toner has a charged aggregation degree (A) of 25 to 85% when the toner is charged by shaking under conditions of 23°C and 50% RH; and a ratio B/C of the volume resistivity B of the toner to the volume resistivity C of the fixed charging brush ranges from 1×10<SP>5</SP>to 1×10<SP>9</SP>. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to toner and image formation used in an image forming apparatus such as an electrophotographic system or an electrostatic recording system in which a developer is attached to a latent image formed on an image carrier for visualization. It is about the method.

  Recent copiers and printers are becoming increasingly demanding in terms of size reduction, weight reduction and high reliability, and demands on toner performance are becoming strict. For example, from the viewpoint of miniaturization, there is a demand for a toner that is superior to conventional toner performance by reducing parts and reducing waste toner box.

  In order to achieve such a demand, many proposals have been made that define the physical properties of the toner.

  Up to now, there has been proposed an image forming method in which the transfer residual toner is reversely charged and returned to the latent image carrier to perform cleaning (see, for example, Patent Documents 1, 2, and 3). However, there is room for improvement in terms of further component reduction, and further improvement is required under more severe environmental conditions.

  Also, from the viewpoint of miniaturization, an image forming method and a toner are proposed in which the residual transfer toner is reversely charged using an intermediate transfer member and returned to the latent image carrier for cleaning in order to reduce parts and waste toner box. (For example, refer to Patent Document 4). However, there is room for improvement in terms of further component reduction, and further improvement is required under more severe environmental conditions.

  In addition, there is disclosed an image forming method in which four color developing devices are arranged in a horizontal row, and an intermediate transfer member is used to reversely charge the transfer residual toner and return to the latent image carrier to perform cleaning (see, for example, Patent Document 5). ). However, there is room for improvement in terms of further component reduction, and further improvement is required under more severe environmental conditions.

  As described above, there is no toner that can solve various problems as a whole.

JP-A-4-340564 Japanese Patent Laid-Open No. 5-29739 JP-A-1-105980 Japanese Patent Laid-Open No. 9-50167 JP 2003-241479 A

  In view of the above circumstances, an object of the present invention is to provide a toner and an image forming method that satisfy high speed, high image quality, high durability, and high environmental stability.

  The above object is achieved by the present invention described below.

That is, the present invention repeats the formation of the toner image on the first image carrier and the primary transfer of the toner image onto the second image carrier for the plurality of color toner images. After superimposing a plurality of color toner images on the body, the plurality of color toner images are collectively transferred to a transfer material to form a color image, and after the secondary transfer, the second image carrier The transfer residual toner remaining on the first image carrier is reversely transferred from the second image carrier to the first image carrier by applying an electric charge with at least one fixed charging brush. A toner used in an image forming method collected by an image carrier cleaning device,
The toner has an aggregation degree (charge aggregation degree) A of 25 to 85% when charged by shaking under a condition of a temperature of 23 ° C./humidity of 50%, and the toner has a volume resistance value B and the fixed value. The present invention relates to a toner satisfying that the ratio B / C of the volume resistance value C of the charging brush is 1 × 10 ^{5 to} 1 × 10 ⁹ , and an image forming method.

  According to the present invention, it is possible to obtain a developer which is excellent in suppressing toner deterioration and excellent in suppressing member contamination. According to the present invention, a developer excellent in development stability and transferability can be obtained. Furthermore, according to the present invention, a developer having excellent cleaning properties on the intermediate transfer member can be obtained.

The present invention repeats the formation of a toner image on a first image carrier and the primary transfer of the toner image onto the second image carrier for a plurality of color toner images, and the second image carrier. After the toner images of a plurality of colors are superimposed on each other, the toner images of the plurality of colors are collectively transferred to a transfer material to form a color image. After the secondary transfer, the toner images on the second image carrier are formed. The remaining transfer residual toner is reversely transferred from the second image carrier onto the first image carrier by applying an electric charge with at least one fixed charging brush, and further, the first image Toner used in an image forming method collected by a carrier cleaning device,
When the toner is charged by shaking under a condition of a temperature of 23 ° C./humidity of 50%, the aggregation degree (charge aggregation degree) A is 25 to 85%, and the volume resistance value B of the toner and the fixed The ratio B / C of the volume resistance value C of the charging brush is 1 × 10 ^{5 to} 1 × 10 ⁹ .

  In the present invention, the toner to be used has good chargeability and transferability in various situations from a low temperature and low humidity environment to a high temperature and high humidity environment by satisfying the above-mentioned items. Even in such a case, good results can be obtained. Further, in an image forming method in which an intermediate transfer member (second image carrier) is used and the transfer residue is reversely transferred to the image carrier without using a cleaning blade, the cleaning property is excellent.

  Specifically, it will be described below.

  In the present invention, first, the degree of aggregation (charge aggregation degree) A when charged by shaking under conditions of a temperature of 23 ° C./humidity of 50% needs to be 25 to 85%.

  When toner is used in an image forming apparatus, the design of its charging characteristics and powder characteristics is important.

  The degree of aggregation (charge aggregation degree) A when the toner is charged by shaking under a condition of a temperature of 23 ° C./humidity of 50% in the toner represents the fluidity of the toner in the image forming apparatus. Controlling this shows good cleaning performance in an image forming method in which an intermediate transfer member is used and the transfer residue is reversely transferred to the image carrier without using a cleaning blade for cleaning.

  If the degree of aggregation (charge aggregation degree) A when charged is less than 25%, the fluidity is high, so when a charge is applied by a non-rotating fixed charging brush, the toner enters the back of the brush, and the latent image It becomes difficult to perform reverse transfer to the carrier. When the degree of aggregation (charge aggregation degree) A when charged exceeds 85%, the electrophotographic characteristics (charge amount, fog, etc.) tend to deteriorate.

  Here, the aggregation degree (charge aggregation degree) method when charged according to the present invention will be described below.

<Charging aggregation method>
The degree of aggregation of the toner in the present invention was measured as follows.

  As a measuring apparatus, a powder tester (manufactured by Hosokawa Micron Co., Ltd.) having a digital vibrometer (manufactured by DEGITAL VIBLATIONMETER MODEL 1332 SHOWA SOKKI CORPORATION) was used.

  As a measurement method, set 390 mesh, 200 mesh, and 100 mesh sieves on the shaking table in order of narrow opening, that is, 390 mesh, 200 mesh, and 100 mesh sieves so that the 100 mesh sieve is at the top. did.

  An accurately weighed sample of 5 g was added to the set 100 mesh sieve, the displacement value of the digital vibrometer was adjusted to 0.60 mm (peak-to-peak), and vibration was applied for 15 seconds. Thereafter, the mass of the sample remaining on each sieve was measured to obtain the degree of aggregation based on the following formula.

The measurement samples at that time were previously left in a 23 ° C. and 60% RH environment or in a 30 ° C. and 80% RH environment for 24 hours, and the measurement was performed in a 23 ° C. and 60% RH environment.
Aggregation degree (%) = (residual sample mass on 100 mesh sieve / 5 g) × 100 + (residual sample mass on 200 mesh sieve / 5 g) × 60 + (residual sample mass on 390 mesh sieve / 5 g) × 20

Furthermore, in the present invention, the ratio B / C of the volume resistance value B of the toner and the volume resistance value C of the fixed charging brush needs to satisfy 1 × 10 ^{5 to} 1 × 10 ⁹ .

When the ratio B / C of the volume resistance value B of the toner and the volume resistance value C of the fixed charging brush is 1 × 10 ^{5 to} 1 × 10 ⁹ , the toner held on the charging brush and the first image carrier ( The toner returned to the latent image carrier can be balanced. Further, a bias is smoothly applied from the charging brush to the untransferred toner, and excellent cleaning properties can be obtained.

When the ratio B / C is less than 1 × 10 ⁵ , the volume resistance value B of the toner is close to the volume resistance value C of the fixed charging brush, and it is difficult to apply a bias from the charging brush to the transfer residual toner. This makes it easier for toner to accumulate in the brush. In such a case, an appropriate applied bias cannot be applied and the white background of the paper is soiled.

When the ratio B / C exceeds 1 × 10 ⁹ , the volume resistance value B of the toner is separated from the volume resistance value C of the fixed charging brush, and a bias is applied to the transfer residual toner from the charging brush. In this case, unevenness in the conductivity of the brush tends to occur. In such a case, vertical stripes appear in the image so as to correspond to unevenness.

<Toner and external additive volume resistance measurement method>
The volume resistance value of the toner was measured by the following method.

That is, the measurement was performed in a state where a cylinder having a lower electrode with a diameter of 5 mm was tapped with 0.3 to 1.0 g of a conductive material, an upper electrode with a diameter of 15 mm was placed, and a load of 350 g was applied. At this time, after measuring the thickness of the sample, the applied voltage was swept from 0V to 100V. The electric field was calculated from the measured resistance value, sample thickness, and applied voltage, and the volume resistance value at 1 × 10 ⁴ V / cm was determined.

  An apparatus used for measuring the volume resistance value is shown in FIG.

  In FIG. 2, 11 indicates a lower electrode, 12 indicates an upper electrode, 14 indicates an ammeter, 15 indicates a constant voltage device, 17 indicates a measurement sample, 18 indicates a guide ring, and d indicates a measurement. The thickness of a sample is shown, A shows a volume resistance measuring cell.

  The sample was filled in the cell A, electrodes 11 and 12 were arranged so as to be in contact with the filled sample 17, a voltage was applied between the electrodes, and the current flowing at that time was measured by an ammeter 14.

  The measurement conditions were 23 ° C., 65% environment, and sample thickness of 0.5 to 1.0 mm.

<Measuring method of volume resistance of member>
In the present invention, for example, measurement can be performed in a volume resistance measuring device (4140B pA MATER manufactured by Hewlett-Packard Company) in an environment of 23 ° C. and 65%.

  Furthermore, in the present invention, it is preferable that the following conditions are satisfied in that the above-described effects are increased and the characteristics are excellent in a more severe use environment.

  The degree of aggregation D of the toner is 10 to 35%, and the relationship with the degree of charge aggregation A is A> D.

  The repose angle E of the toner is 10 to 30 °, and the repose angle F is 15 to 45 °.

  The average circularity measured by the flow type particle image measuring device of the toner is 0.950 to 0.995.

  The average circularity measured by the flow type particle image measuring device of the toner is 0.960 to 0.995.

  The toner has a melt viscosity at 100 ° C. of 15000 to 80,000 (PaS).

  The toner has a melt viscosity at 100 ° C. of 15000 to 60000 (PaS).

  The charge aggregation degree A of the toner is 30 to 70%.

  The repose angle E of the toner is 10 to 30 °, and the repose angle F is 20 to 40 °.

The ratio B / G of the volume resistivity B of the toner at a temperature of 23 ° C./humidity of 50% and the volume resistivity of the toner at a temperature of 30 ° C./humidity of 80% is 1 × 10 ^{1 to} 1 × 10 ⁴ .

The toner includes, as external additives, silica fine powder a having a volume resistance value of 1 × 10 ^{10 to} 1 × 10 ¹⁷ and non-silica fine powder b having a volume resistance value of 1 × 10 ^{5 to} 1 × 10 ¹³ (however, the volume of a) (Volume resistance value of resistance value> b) is used.

  Examples of the wax used in the present invention include paramethylene wax, polyolefin wax, microcrystalline wax, polymethylene wax such as Fischer Tropish wax, amide wax, ketone wax, higher fatty acid, long chain alcohol, ester wax, and graft compounds thereof. And derivatives such as block compounds.

  Examples of the wax preferably used include linear alkyl alcohols having 15 to 100 carbon atoms, linear fatty acids, linear acid amides, linear esters, and montan derivatives. Those from which impurities such as liquid fatty acids have been previously removed from these waxes are also preferred.

  Further, the wax preferably used is a low molecular weight alkylene polymer obtained by polymerizing alkylene with radical polymerization under high pressure or Ziegler catalyst or other catalyst under low pressure; alkylene obtained by thermally decomposing high molecular weight alkylene polymer Polymer: A low molecular weight alkylene polymer produced as a by-product in the polymerization of alkylene, separated and purified; a hydrocarbon polymer distillation residue obtained from a synthesis gas consisting of carbon monoxide and hydrogen by the age method, or a distillation residue And polymethylene wax obtained by extracting and fractionating specific components from a synthetic hydrocarbon obtained by hydrogenation. These waxes may contain an antioxidant.

  The content in the toner is preferably 6 to 15% by mass of wax.

  In the present invention, the average circularity of the toner is preferably 0.950 to 0.995.

  Here, the flow type particle image measuring apparatus is an apparatus that statistically performs image analysis of particle imaging, and the average circularity is calculated by the arithmetic average of the circularity obtained by the following equation using the apparatus.

  In the above equation, the perimeter of the particle projection image is the length of the contour line obtained by connecting the edge points of the binarized particle image, and the perimeter of the equivalent circle is the binarized particle This is the length of the outer circumference of a circle having the same area as the image. The equivalent circle diameter is the diameter of a circle having the same area as the area of the measured two-dimensional image of the particles.

  FPIA-2100 (manufactured by Sysmex Corporation) is used as a flow type particle image measuring apparatus. As a measurement method, 0.02 g of a measurement sample is added to 10 ml (20 ° C.) of a solution prepared by adding 0.1 to 0.5 mass% of a surfactant (preferably Wako Pure Chemicals Contaminone) to ion-exchanged water. To prepare a sample dispersion. As a means for dispersion, an ultrasonic disperser UM-50 manufactured by SMT Co., Ltd. (vibrator is a titanium alloy chip of 5φ) is used, and the dispersion time is set to 5 minutes. Cooled to. In the measurement, the range of 0.60 to 400 μm is divided into 226 channels, and in the actual measurement, particles are measured in a range where the equivalent circle diameter is 0.60 μm or more and less than 159.21 μm.

  When the average circularity is 0.950 to 0.990, the toner shape is almost spherical, so that there is little transfer residue, and a good result is obtained with little load in charging in the roller and recovery in the cleaning unit. When the average circularity is less than 0.950, a large amount of toner remains after transfer, so that charging roller contamination and fusing in the cleaning portion are likely to occur.

  The toner of the present invention preferably has a melt viscosity measured by a flow tester at 100 ° C. of 15000 to 80000. This is because it is difficult to judge the behavior of the toner, which is a composite of various functional substances, based only on the physical properties and addition amount of the material substance, and the gel content (insoluble content) and non-gel content of the binder resin ( It is considered that it can be evaluated as a complex of a release agent) and a release agent.

  In the present invention, by setting the melt viscosity measured at 100 ° C. of the toner to 15000 to 80,000, a full color image having stable color reproducibility and fixing property can be obtained without impairing durability stability in development. When the toner has a melt viscosity of less than 15000, the fixability in a fixing device with a low applied pressure is poor or color mixing is insufficient, resulting in poor color reproducibility. When the melt viscosity of the toner exceeds 80,000, the durability stability during development deteriorates, and the fixing property tends to be inferior to the high temperature offset resistance.

  Here, a method for measuring the melt viscosity of the toner at 100 ° C. measured by a flow tester is shown below.

<Measurement of melt viscosity measured by flow tester>
As an apparatus, for example, a flow tester CFT-500D (manufactured by Shimadzu Corporation) is used, and measurement is performed under the following conditions.
Sample: 1.0 g of toner is weighed and molded by pressing it with a pressure molding machine having a diameter of 1 cm at a load of 20 kN for 1 minute.
・ Die hole diameter: 1.0mm
-Die length: 1.0mm
・ Cylinder pressure: 9.807 × 10 ⁵ (Pa)
Measurement mode: Temperature rising method Temperature rising rate: 4.0 ° C./min

  By the method described above, the viscosity (Pa · s) of the toner at 50 ° C. to 200 ° C. is measured to obtain the viscosity (Pa · s) at 100 ° C.

  The method for producing the toner of the present invention is a method in which a toner is directly produced using a suspension polymerization method; toner particles are produced by direct polymerization in the presence of a water-soluble polymerization initiator that is soluble in a monomer. Examples thereof include production of toner particles by an emulsion polymerization method typified by a soap-free polymerization method. In addition, production of an interfacial polymerization method such as a microcapsule production method, an in situ polymerization method, a coacervation method, and the like can also be mentioned. Alternatively, a method in which the toner obtained by the pulverization method is spheroidized by a mechanical impact force can be used.

  Among these, a suspension polymerization method that can easily obtain toner particles having a small particle diameter is particularly preferable. When suspension polymerization is used as a method for producing toner particles, the toner particles can be produced directly by the following production method.

  Adds a colorant, polymerization initiator, cross-linking agent, and other additives to the monomer, and contains a dispersion stabilizer that is uniformly dissolved or dispersed by a homogenizer, ultrasonic disperser, etc. Disperse in an aqueous medium using a normal stirrer, homomixer or homogenizer. Preferably, granulation is performed by adjusting the stirring speed and time so that the droplets of the monomer composition have a desired toner particle size. Thereafter, stirring may be performed to such an extent that the particle state is maintained and the sedimentation of the particles is prevented by the action of the dispersion stabilizer. Polymerization is carried out at a polymerization temperature of 40 ° C. or higher, usually 50 to 80 ° C. (preferably 55 to 70 ° C.). The temperature may be raised in the latter half of the polymerization reaction, and the pH may be changed as necessary. In the present invention, in order to remove unreacted polymerizable monomers and by-products that cause odor during toner fixing, the aqueous medium is partially distilled off in the latter half of the reaction or after the completion of the reaction. May be. After completion of the reaction, the produced toner particles are collected by washing and filtration and dried.

  The following describes the material of the polymerization toner.

  As the polymerizable monomer used when the toner of the present invention is produced by the polymerization method, a vinyl polymerizable monomer capable of radical polymerization is used. As the vinyl polymerizable monomer, a monofunctional polymerizable monomer is mainly used. Monofunctional polymerizable monomers include styrene; α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, pn-butyl. Styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p -Styrene derivatives such as phenylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, n-amyl acrylate, n-hexyl acrylate, 2 -Ethylhexyl acrylate acrylic polymerizable monomers such as n-octyl acrylate, n-nonyl acrylate, cyclohexyl acrylate, benzyl acrylate, dimethyl phosphate ethyl acrylate, diethyl phosphate ethyl acrylate, dibutyl phosphate ethyl acrylate, 2-benzoyloxyethyl acrylate; Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, iso-propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate , N-nonyl methacrylate, diethyl phosphate ethyl methacrylate Methacrylic polymerizable monomers such as dibutyl phosphate ethyl methacrylate; methylene aliphatic monocarboxylic acid esters; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, vinyl formate; vinyl methyl ether Vinyl ether such as vinyl ethyl ether and vinyl isobutyl ether; vinyl ketone such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropyl ketone.

  In the present invention, the above monofunctional polymerizable monomers are used alone or in combination of two or more.

  In the present invention, a water-soluble initiator may be used in combination as an aid to the reaction. Examples include ammonium persulfate, potassium persulfate, 2,2′-azobis (N, N′-dimethyleneisobutyroamidine) hydrochloride, 2,2′-azobis (2-aminodinopropane) hydrochloride, azobis (isobutyl) Amidine) hydrochloride, sodium 2,2′-azobisisobutyronitrile sulfonate, ferrous sulfate or hydrogen peroxide.

  In order to control the degree of polymerization of the polymerizable monomer, a chain transfer agent, a polymerization inhibitor or the like can be further added and used.

  Dispersion stabilizers include tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, and barium sulfate. , Bentonite, silica, alumina, hydroxyapatite and the like. Usually, it is preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer composition.

  As the organic compound, for example, polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, starch and the like are used. These dispersants are preferably used in an amount of 0.2 to 2.0 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  Other dispersion stabilizers preferably used include sparingly water-soluble metal salts of sulfuric acid, carbonic acid, phosphoric acid, pyrophosphoric acid, and polyphosphoric acid. These are acid alkali metal salts and metal halide salts under high-speed stirring in a dispersion medium. It is preferable to prepare by this reaction.

  In order to make these dispersants fine, 0.001 to 0.1% by mass of a surfactant may be used in combination. Specifically, commercially available nonionic, anionic and cationic surfactants can be used. For example, sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate and the like are preferably used.

  In the present invention, when a condensation compound is used, for example, polyester, polycarbonate, phenol resin, epoxy resin, polyamide, cellulose and the like can be mentioned. More preferably, polyester is desired due to the variety of materials.

  The colorant used in the present invention is carbon black or a known yellow / magenta / cyan colorant as shown below.

  As the yellow colorant, compounds typified by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds are used. Specifically, C.I. I. CI Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 151, 154, 155, 168, 180, etc. are preferably used. It is done.

  As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 146, 166, 150, 169, 177, 184, 185, 202, 206, 220, 221, 254, 269 are particularly preferred.

  As the cyan colorant used in the present invention, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66 and the like are particularly preferably used.

  These colorants can be used alone or in combination and further in the form of a solid solution. The colorant of the present invention is selected from the viewpoints of hue angle, saturation, brightness, weather resistance, OHP transparency, and dispersibility in the toner. The colorant is added in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the resin.

  As the toner additive that can be used in the present invention, oil-treated inorganic fine particles such as silica and titania are preferably used. In addition to oxides such as zirconium oxide and magnesium oxide, silicon carbide, silicon nitride, boron nitride, aluminum nitride, magnesium carbonate, organosilicon compounds, and the like can be used in combination.

Silica is preferable in that the coalescence of the primary particles can be controlled arbitrarily to some extent depending on the starting material or the oxidation conditions such as temperature. For example, the silica can be either a so-called dry method produced by vapor phase oxidation of silicon halide or alkoxide, or a so-called wet silica produced from alkoxide, water glass, etc. is there. Dry silica is preferred because it has few silanol groups on the surface and inside the silica fine powder, and few production residues such as Na ₂ O, SO ₃ ²⁻ . In dry silica, it is also possible to obtain composite fine powders of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride and titanium chloride together with silicon halogen compounds in the production process. Is also included.

  Furthermore, the silica is preferably hydrophobized in order to reduce the dependency of the toner charge amount on the environment, such as temperature and humidity, and to prevent excessive release from the toner surface. Examples of the hydrophobizing agent include coupling agents such as a silane coupling agent, a titanium coupling agent, and an aluminum coupling agent. In particular, the silane coupling agent reacts with residual groups on the inorganic oxide fine particles or adsorbed water to achieve a uniform treatment, which is preferable in terms of stabilizing charging of the toner and imparting fluidity.

The silane coupling agent has the following general formula RmSiYn
R: alkoxy group m: integer of 1 to 3 Y: alkyl group hydrocarbon group including vinyl group, glycidoxy group, methacryl group n: represented by an integer of 1 to 3, for example, vinyltrimethoxysilane, vinyl Triethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxy Examples include silane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, and n-octadecyltrimethoxysilane.

More preferably,
C _a H _{2a + 1} —Si (OC _b H _{2b + 1} ) ₃
(A = 4-12, b = 1-3)
It is.

  Here, when a in the general formula is smaller than 4, the treatment becomes easy, but the hydrophobicity cannot be sufficiently achieved. On the other hand, if a is greater than 12, the hydrophobicity is sufficient, but the coalescence between the particles increases, and the fluidity imparting ability decreases. When b is larger than 3, the reactivity is lowered and the hydrophobicity is not sufficiently performed. Therefore, a in the above general formula is 4 to 12, preferably 4 to 8, and b is 1 to 3, preferably 1 to 2.

  With respect to the oil treatment of silica, untreated silica may be directly treated with oil, but it is more preferable from the viewpoint of charging stability that the hydrophobized silica is further treated with oil. As the oil, dimethylpolysiloxane, methylhydrogenpolysiloxane, paraffin, mineral oil and the like can be used, and among them, dimethylpolysiloxane excellent in environmental stability is preferable. The appropriate amount of oil used for the treatment is 2 to 40 parts by mass with respect to 100 parts by mass of the silica fine particle matrix.

  In the toner of the present invention, other additives such as a lubricant powder such as polyethylene fluoride powder, zinc stearate powder and polyvinylidene fluoride powder; An abrasive such as strontium titanate powder, an anti-caking agent such as aluminum oxide powder, or a conductivity imparting agent such as carbon black powder, zinc oxide powder or tin oxide powder, and organic and inorganic fine particles of reverse polarity. A small amount can be used as a developability improver.

  Next, an image forming method of the present invention, an image forming apparatus that implements the method, and a process cartridge will be described.

  An image forming method to which the present invention can be applied will be described below with reference to the accompanying drawings.

(Non-magnetic one-component image forming device)
(1) Example of Image Forming Apparatus FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus according to the present invention. The image forming apparatus of this example has an intermediate transfer belt type electrophotographic color (multicolor image) printer having a tandem configuration in which photosensitive drums as a plurality of image carriers (latent image carriers) are arranged vertically in a linear direction. It is.

  PY, PM, PC, and PBk are first to fourth image forming units (image forming units) for forming toner images of yellow (Y), magenta (M), cyan (C), and black (Bk), respectively. Unit), which are arranged in the image forming apparatus main body in parallel from the bottom to the top.

  These first to fourth image forming units PY, PM, PC, and PBk have the same configuration and electrophotographic image forming function except that the colors of the toner images formed are different as described above. Yes. That is, each of the first to fourth image forming units includes a drum-type electrophotographic photosensitive member (photosensitive drum) 1 as a first image carrier, a charging roller 2 as a primary charging unit, and a laser as an exposure unit. The irradiation device 3 includes a toner developing device 4 as a developing unit, a primary transfer roller 5 as a primary transfer unit, a blade cleaning device 6 as a cleaning unit, and the like. The developers accommodated in the toner developing devices 4 of the first to fourth image forming units are yellow toner, cyan toner, magenta toner, and black toner, respectively. Each color toner will be described later.

  The image forming apparatus according to the present exemplary embodiment includes four processes of the photosensitive drum 1, the charging roller 2, the developing device 4, and the blade cleaning device 6 in the first to fourth image forming units PY, PM, PC, and PBk, respectively. The apparatus is a process unit (process cartridge) that is detachable and replaceable with respect to the main body of the image forming apparatus.

  Reference numeral 30 denotes an endless belt-shaped intermediate transfer belt as a second image carrier, and the photosensitive drum 1 side (front side of the printer) of the first to fourth image forming portions PY, PM, PC, and PBk. In FIG. 3, the four image forming units are arranged in the vertical direction by being suspended between a plurality of support rollers (not shown). In each of the first to fourth image forming units, the primary transfer roller 5 is in pressure contact with the photosensitive drum 1 via the intermediate transfer belt 30. A contact portion between each photosensitive drum 1 and the intermediate transfer belt 30 is a primary transfer portion.

  In each of the first to fourth image forming units PY, PM, PC, and PBk, each photosensitive drum 1 that is driven to rotate forward is rotated by a charging roller 2 to which a charging bias is applied from a power supply circuit (not shown). The primary charging is uniformly performed to a predetermined polarity and potential. Light image exposures LY, LM, LC, and LBk according to each image pattern of yellow, magenta, cyan, and black, which are color separation component images of full-color images, are made by the LED array device 3 on the charging processing surface, An electrostatic latent image of image information is formed on each photosensitive drum 1. Each of the electrostatic latent images is developed as a toner image by the developing device 4 so that each of the first to fourth image forming portions PY, PM, PC, and PBk has an electrophotographic process on the surface of each photosensitive drum 1. As a result, yellow, magenta, cyan, and black color toner images, which are color separation component images of the full-color image, are formed at a predetermined sequence control timing.

  Then, in each of the first to fourth image forming units PY, PM, PC, and PBk, the yellow, magenta, cyan, and black color toner images formed on the surface of each photosensitive drum 1 are the positive images of each photosensitive drum 1. The first to fourth image forming units PY, PM, PC, and PBk with respect to the surface of the intermediate transfer belt 30 that is driven to rotate at the same speed as the photosensitive drum 1 in the clockwise direction of the forward arrow in the rotation direction. In the primary transfer portion, the images are sequentially superimposed and transferred to the primary transfer roller by a primary transfer bias applied from a power supply circuit (not shown). As a result, an unfixed full-color toner image (mirror image) is synthesized and formed on the surface of the intermediate transfer belt 30 that is rotationally driven.

  In each of the first to fourth image forming units PY, PM, PC, and PBk, the transfer residual toner remaining on each photosensitive drum 1 after the primary transfer of the toner image to the intermediate transfer belt 30 is the cleaning blade of the blade cleaning device 6. Excluded by. And it is stored by the storage part 6b in this apparatus 6. FIG.

  32 is a secondary transfer roller, and 32a is a counter roller. The counter roller 32a is disposed inside the intermediate transfer belt at the lower end side of the intermediate transfer belt 30, and the secondary transfer roller 32 sandwiches the intermediate transfer belt 30 between the counter roller 32a and the intermediate transfer belt 30. Is disposed in contact with the outer surface. A contact portion between the secondary transfer roller 32 and the intermediate transfer belt 30 is a secondary transfer portion.

  Reference numeral 40 denotes a paper feed cassette disposed in the lower part of the main body of the image forming apparatus, in which a transfer material P as a final recording medium is stacked and accommodated. The CPU 80 drives the conveying means (pickup roller) 31 at a predetermined sequence control timing to separate and feed one transfer material P in the paper feed cassette 40, and feeds it to the secondary transfer section at a predetermined timing. . The unfixed full-color toner image synthesized and formed on the intermediate transfer belt 30 is transferred onto the surface of the transfer material P by a secondary transfer bias applied from a power supply circuit (not shown) to the secondary transfer roller 32 in the secondary transfer portion. It will be batch-transcribed.

  The transfer material P that has passed through the secondary transfer portion is separated from the surface of the intermediate transfer belt 30 and sent to the fixing device 7 by the transport belt 35.

  The transfer residual toner remaining on the intermediate transfer belt 30 is charged by the charging brush 33 and the charging roller 34, reversely transferred to the electrophotographic photosensitive member (photosensitive drum) 1, and removed by the cleaning blade of the blade cleaning device 6. And it is stored by the storage part 6b in this apparatus 6. FIG.

  In FIG. 1, the charging brush and the charging roller are in contact with the intermediate transfer belt where the cleaning blade is normally disposed. In this embodiment, the charging brush uses a brush member made of conductive fibers.

The charging brush has a resistance value controlled by adding carbon or metal powder to a fiber such as rayon, acrylic or polyester. The thickness is preferably 30 denier or less and the density is preferably 1 × 10 ^{6 to} 1 × 10 ⁹ particles / m ² so that the transfer residual toner can be uniformly contacted. In this embodiment, 6 denier, 1.55 × 10 ⁸ pieces / m ² (100,000 pieces / inch ² ), the length of the bristle leg is 5 mm, and the resistance of the brush is 8.1 × 10 ⁷ Ω · cm. did.

In the present invention, when the brush bristle density is H (lines / m ² ), the brush bristle average diameter is I (m), and the toner weight average particle diameter (D4) is J (m), the relational expression is the following formula 1 × 10 ⁻⁵ <H × I × J <1 × 10 ⁰
If this is the case, the toner remaining on the second image carrier is collected by the brush, charged, and collected on the first image carrier, and image defects do not occur.

  When the value of the average bristle diameter I of the charging brush is too large, when a large amount of toner comes to the brush due to paper conveyance failure or the like, the holding ability is low and a streak-like image defect tends to occur.

  On the other hand, if the value of I is too small, the durability of the brush itself is insufficient, or the toner tends to stay behind the brush and cause streak-like image defects.

  When the toner weight average particle diameter J is too large, when a large amount of toner comes to the brush due to poor paper conveyance or the like, it tends to accumulate at the tip of the brush and cause streak-like image defects.

  On the other hand, when the value of J is too small, the toner tends to penetrate too deep into the brush and cause streak-like image defects.

  From the above balance, it is preferable that the relational expression satisfies the above range.

If H × I × J <1 × 10 ⁻⁵ , the durability of the brush itself may be insufficient, or the toner may stay in the back of the brush and cause streak-like image defects.

When 1 × 10 ⁰ <H × I × J, a large amount of toner comes to the brush due to poor paper conveyance or the like, and may accumulate at the tip of the brush and cause streak-like image defects.

In the form of Example 1, the average bristle diameter was 30 μm, that is, 3.0 × 10 ⁻⁵ (m), and the average particle diameter of the toner was 5.8 μm, that is, 5.8 × 10 ⁻⁶ (m).

<Measurement method of brush hair average diameter>
The measurement of the average bristle diameter was performed by taking a photograph of the brush hair magnified 500 to 1000 times with an electron microscope FE-SEM (S-4700, manufactured by Hitachi, Ltd.) and using the magnified photograph.

  The diameter of 12 brush hairs was arbitrarily measured on the enlarged photograph, and the average value of 10 hairs excluding the maximum value and the minimum value was determined as the average long hair diameter.

<Method for Measuring Toner Weight Average Particle Size (D4)>
The weight average particle diameter (D4) of the toner was measured using a Coulter Counter TA-II type (manufactured by Coulter) according to the operation manual of the apparatus. An interface (manufactured by Nikka) and a PC 9801 personal computer (manufactured by NEC) for outputting the number distribution and volume distribution were connected to the apparatus.

  As the electrolytic solution, a 1% NaCl aqueous solution was prepared using primary sodium chloride, but ISOTON R-II (manufactured by Coulter Scientific Japan) may be used.

  As a measuring method, 0.1 to 5 ml of a surfactant, preferably alkylbenzene sulfonate, was added as a dispersant to 100 to 150 ml of the electrolytic solution, and 2 to 20 mg of a measurement sample was further added. The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes. The dispersion-treated sample was subjected to the above apparatus equipped with a 100 μm aperture as an aperture, and the volume distribution and number distribution were calculated by measuring the volume and number of toners of 2.00 μm or more. The weight-based weight average particle diameter (D4) determined from the volume distribution was determined. The median value of each channel used was used as a representative value for each channel.

  The channels include: 2.00 to less than 2.52 μm; 2.52 to less than 3.17 μm; 3.17 to less than 4.00 μm; 4.00 to less than 5.04 μm; 5.04 to less than 6.35 μm; 6.35 to less than 8.00 μm; 8.00 to less than 10.08 μm; 10.08 to less than 12.70 μm; 12.70 to less than 16.00 μm; 16.00 to less than 20.20 μm; 13 channels of less than 40 μm; 25.40 to less than 32.00 μm; 32.00 to less than 40.30 μm were used.

  This charging brush was brought into contact with the intermediate transfer belt so that the penetration amount was 1 mm, and the width of the contact nip was 5 mm.

  The charging roller has a three-layer structure in which a lower layer, an intermediate layer, and a surface layer are laminated around a core bar (support member). The lower layer is a foamed sponge layer, the intermediate layer is a resistance layer for obtaining uniform resistance for the entire charging roller, and the surface layer is provided to prevent leakage even if there are defects such as pinholes. It is a protective layer.

The charging roller of the present embodiment uses a stainless steel round bar having a diameter of 6 mm as a core, carbon is dispersed in fluororesin as the surface layer 2d, the outer diameter of the roller is 14 mm, and the roller resistance is 10 ⁴ Ω to 10 ⁴ . ⁷ Ω.

  The unfixed full-color toner image on the transfer material P sent to the fixing device 7 is melted and fixed to the transfer material P by applying heat and pressure by the fixing device 7, passes through the sheet path 41, and the upper surface of the image forming apparatus main body. The sheet is discharged as a color image formed product onto a paper discharge tray 36 disposed in the above.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but this does not limit the present invention in any way.

<Synthesis of binder resin>
(Synthesis example 1 of polar resin)
The following raw materials were placed in a four-neck flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas introduction tube.
-Diol component represented by the general formula (1) 55 mol%

（式中、Ｒはエチレン又はプロピレン基を表し、ｘ，ｙはそれぞれ１以上の整数であり、かつｘ＋ｙの平均値は２〜１０である。本実施例ではｘ＋ｙの平均値は３である。）
・イソフタル酸 ２０ｍｏｌ％
・テレフタル酸 ２５ｍｏｌ％

(In the formula, R represents an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 10. In this example, the average value of x + y is 3. )
・ Isophthalic acid 20mol%
・ Terephthalic acid 25mol%

  Further, the titanium oxalate compound (1) having a catalyst amount of 0.5% by mass relative to 100 parts by mass of the raw material.

を入れ、四口フラスコに窒素ガスを通し撹拌しながら徐々に昇温し、１５０℃で１０時間反応し、縮重合反応の後半２００℃に温度を上げ、減圧下で縮重合反応をすすめた。結果、重量平均分子量Ｍｗが１１０００の前駆ポリエステル樹脂（１）（酸価５ｍｇＫＯＨ／ｇ）を得た。

The mixture was gradually warmed with nitrogen gas passing through a four-necked flask and stirred, reacted at 150 ° C. for 10 hours, the temperature was raised to 200 ° C. in the latter half of the condensation polymerization reaction, and the condensation polymerization reaction was promoted under reduced pressure. As a result, a precursor polyester resin (1) (acid value 5 mgKOH / g) having a weight average molecular weight Mw of 11000 was obtained.

  Thereafter, 100 parts by mass of the precursor polyester resin (1) was placed in a four-necked flask and heated to a temperature of 150 ° C. Next, 0.5 parts by mass of trimellitic anhydride was added, and the mixture was gradually heated to prepare a polar resin (1) in which the polymer terminal of the precursor polyester resin (1) was modified with trimellitic acid.

<Example of toner production>
(Black toner production example 1)
3 parts by mass of tricalcium phosphate is added to 900 parts by mass of ion-exchanged water heated to 65 ° C., and stirred at 10,000 rpm using a TK homomixer (made by Tokushu Kika Kogyo Co., Ltd.) to obtain an aqueous medium. It was.

on the other hand,
Styrene 80 parts by mass n-butyl acrylate 20 parts by mass polar resin (1) 3 parts by mass polar resin (2) 2 parts by mass (polycondensate of propylene oxide modified bisphenol A and terephthalic acid, Tg = 55 ° C., Mn = 2500 Mw / Mn = 1.9)
Carbon black (carbon black Nipex 30 pH: 9.0) 10 parts by mass charge control agent 1: aromatic oxycarboxylic acid Zn compound (Bontron E-84: manufactured by Orient Chemical Co., Ltd.) 4 parts by mass charge control agent 2: methylcalixarene 1 Part by mass The above formulation was uniformly dispersed and mixed using an attritor (Mitsui Miike Chemical Co., Ltd.). This monomer composition is heated to 65 ° C.
Paraffin wax (1) 10 parts by mass (DSC endothermic peak: 69 ° C., Mw: 700, Mn: 500)
Was mixed and dissolved, and 5 parts by mass of a polymerization initiator (t-butylperoxypivalate) was dissolved in this.

The polymerizable monomer system was put into the aqueous medium, and the mixture was granulated by stirring at 10,000 rpm for 7 minutes with a TK homomixer in an N ₂ atmosphere at 70 ° C. Thereafter, the mixture was reacted at 70 ° C. for 4 hours while stirring with a paddle stirring blade.

  Finally, the liquid temperature was raised to 85 ° C. and stirring was continued for 3 hours.

  Hydrochloric acid was added to the suspension cooled to room temperature (25 ° C.) to dissolve the calcium phosphate salt, followed by filtration and washing with water to obtain wet colored particles.

  Next, the particles were dried at 40 ° C. for 12 hours to obtain black colored particles (1) having a weight average particle diameter of 5.8 μm.

  Thereafter, 100 parts by mass of black particles (1) were subjected to a hydrophobization treatment with 0.5 parts by mass of a fine powder of titania having a primary particle size of 100 nm that had been subjected to a hydrophobization process with silicone oil, and with silicone oil. Next, 2.0 parts by mass of silica fine powder having a particle size of 15 nm was added, and the mixture was uniformly diffused using a Henschel mixer manufactured by Mitsui Mining Co., Ltd. The physical properties are shown in Table 1.

(Black toner production examples 2 and 3)
Instead of the black toner production example 1, the amount of the charge control agents 1 and 2 was adjusted, the titania fine powder having a primary particle diameter of 50 nm subjected to the hydrophobic treatment, and the primary particle diameter subjected to the hydrophobic treatment. Black toners (2) and (3) were obtained in the same manner as in black toner production example 1 except that the addition amount of fine silica powder of 15 nm was adjusted. The physical properties are shown in Table 1.

(Black toner production example 4)
Instead of the black toner production example 1, the charge control agents 1 and 2 are not added, and the hydrophobic titania fine powder having a primary particle diameter of 50 nm is changed from 0.2 parts by weight to 3.0 parts by weight. A black toner (4) was obtained in the same manner as in black toner production example 1 except that the silica fine powder having a primary particle size of 15 nm subjected to the hydrophobization treatment was not added.

(Black toner production example 5)
In place of Black toner production example 1, the amount of charge control agent 1 added is changed from 4 parts by weight to 10 parts by weight, and no titania fine powder having a primary particle diameter of 50 nm subjected to hydrophobic treatment is added. A black toner (5) was obtained in the same manner as in the black toner production example 1 except that the silica fine powder having a primary particle diameter of 15 nm subjected to the hydrophobic treatment was changed from 1.3 parts by mass to 3.0 parts by mass. .

(Black toner production example 6)
Instead of the black toner production example 1, the addition amount of the charge control agent 2 was changed from 4 parts by mass to 10 parts by mass, and the silica fine powder was not subjected to the hydrophobization treatment. Similarly, black toner (6) was obtained.

(Black toner production example 7)
Instead of the black toner production example 1, the amount of carbon black added is changed from 10 parts by mass to 20 parts by mass, and the titania fine powder having a primary particle diameter of 50 nm subjected to the hydrophobizing process and the hydrophobizing process are performed. A black toner (7) was obtained in the same manner as in the black toner production example 1 except that the amount of silica fine powder having a primary particle diameter of 15 nm was adjusted.

(Black toner production examples 8 to 14)
Instead of Black Toner Production Example 1, the amount of charge control agents 1 and 2 was adjusted, and the titania fine powder having a primary particle diameter of 50 nm, whose volume resistance value was changed by hydrophobic treatment, and volume resistance by hydrophobic treatment. Black toners (8) to (14) were obtained in the same manner as in black toner production example 1, except that the value was changed to silica fine powder having a primary particle diameter of 15 nm and the addition amount was adjusted. The physical properties are shown in Table 1.

(Black toner production example 15)
-Polar resin (1) 100 parts by mass-Paraffin wax (1) 10 parts by mass (DSC endothermic peak: 69 ° C, Mw: 700, Mn: 500)
Charge control agent: Aromatic oxycarboxylic acid Zn compound (Bontron E-84: manufactured by Orient Chemical Co., Ltd.) 4 parts by massPigment: Black pigment 10 parts by mass (carbon black Nipex 30 pH: 9.0)
The above materials were kneaded and pulverized to obtain pulverized particles (1).
Thereafter, 100 parts by mass of the pulverized particles (1) whose particle size distribution was adjusted were subjected to the same treatment as in (Black Toner Production Example 1) to obtain Black Toner (15).

(Black toner production example 16)
The pulverized particles (1) obtained by pulverization in Toner Production Example 15 are subjected to surface treatment by changing the number of rotations and time in a machine with a rotor rotating, and then the particle size distribution is adjusted to obtain black particles (16). Got. Thereafter, the same treatment as in (Black Toner Production Example 1) was performed on 100 parts by mass of the black particles (16) to obtain a black toner (16).

(Black toner production examples 17 to 19)
Instead of the black toner production example 1, the black toners (17) to (17) are obtained in the same manner as in the black toner production example 1 except that the addition amount of the polymerization initiator (t-butylperoxypivalate) and the reaction temperature are changed. 19) was obtained.

(Black toner production examples 20 to 21)
Instead of the black toner production example 1, the amount of tricalcium phosphate added and the rotation number of the TK homomixer were changed to change the toner weight average particle diameter, and the same as in the black toner production example 1. Black toners (20) and (21) were obtained.

(Black toner production examples 22 to 25)
Instead of the black toner production example 1, the black toner (black toner) was prepared in the same manner as the black toner production example 1 except that the external additive (a) or the external additive (b) was changed to the external additive having the physical properties shown in Table 1. 22) to (25) were obtained.

(Toner Production Examples 26 to 28)
C. replaces the pigment with carbon black. I. Pigment Red 122; magenta toner (1) was obtained in the same manner as in Toner Production Example 1 except that 5 parts by mass were used. In addition, C.I. I. Pigment Blue 15: 3; cyan toner (1) was obtained in the same manner as in Toner Production Example 1 except that 5 parts by mass were used. C. I. Pigment Yellow 151: Yellow Toner 1 was obtained in the same manner as in Toner Production Example 1 except that 5 parts by mass were used. The obtained physical properties are shown in Table 1.

<Examples 1 to 23 and Comparative Examples 1 and 2>
(Image evaluation)
Using the obtained toners 1 to 25, image evaluation was performed according to the following method.

  As an image forming apparatus, a commercially available laser printer HP-made CLJ-3700 (manufactured by HP) is used, and a low-temperature, low-humidity environment (15 ° C., 10% RH) and a high-temperature, high-humidity environment (30 ° C., 80%). RH).

  For the intermediate transfer member, the cleaning blade and the waste toner box were removed, and a charging brush and a charging roller were mounted instead.

  In FIG. 1, the charging brush and the charging roller are in contact with the intermediate transfer belt where the cleaning blade is normally disposed. In this embodiment, the charging brush uses a brush member made of conductive fibers.

The charging brush has a resistance value controlled by adding carbon to the fiber of rayon. In this embodiment, 6 denier, 1.55 × 10 ⁸ pieces / m ² (100,000 pieces / inch ² ), the length of the bristle leg is 5 mm, and the resistance of the brush is 8.1 × 10 ⁷ Ω · cm. did.

  This charging brush was brought into contact with the intermediate transfer belt so that the penetration amount was 1 mm, and the width of the contact nip was 5 mm.

  The charging roller has a three-layer structure in which a lower layer, an intermediate layer, and a surface layer are laminated around a core bar (support member). The lower layer is a foamed sponge layer, the intermediate layer is a resistance layer for obtaining uniform resistance for the entire charging roller, and the surface layer is provided to prevent leakage even if there are defects such as pinholes. It is a protective layer.

The charging roller of the present embodiment uses a stainless steel round bar having a diameter of 6 mm as a core, carbon is dispersed in fluororesin as the surface layer 2d, the outer diameter of the roller is 14 mm, and the roller resistance is 10 ⁴ Ω to 10 ⁴ . ⁷ Ω.

  The fixing device is a commercially available fixing device for a laser printer CLJ-1500 (manufactured by HP) so that the temperature control and the pressing force can be changed, and the fixing device is modified and installed so as to enter CLJ-3700.

  The same cartridge for CLJ-3700 was used with the following changes.

(Method for producing developing roller D-1)
As the shaft core, a SUS cylinder was plated with nickel, and a silane coupling primer was applied and baked.

  Next, the shaft core was placed in a mold, the mold was heated at 100 ° C. for 5 minutes, and conductive dimethyl silicone rubber (Asker C hardness 20 ° product) was injected into the cavity formed in the mold. Subsequently, the silicone rubber was vulcanized and cured by heating at 100 ° C. for 15 minutes, and after cooling, it was demolded to provide an elastic layer on the outer periphery of the shaft core body.

  Next, a necessary amount of TMP-modified TDI is added as a cross-linking material based on a chain-extended polyol, and the solid content of the urethane resin (total amount of the chain-extended polyol and isocyanate used as the cross-linking material) is 18. A mixed solution containing methyl ethyl ketone as a main solvent, adjusted to be mass%, and carbon black (trade name: MA-100, manufactured by Mitsubishi Chemical Co., Ltd.) added to the resin component by 30 parts by mass and sufficiently stirred are dip. Liquid. After the shaft core body 11 provided with the elastic layer 12 is dipped and coated in this liquid, the surface layer 13 is provided on the outer periphery of the elastic layer 12 by lifting and drying, and heat-treating at 120 ° C. for 5 hours. A developing roller D-1 was obtained.

As a transfer material, LETTER size XEROX 4024 paper (manufactured by XEROX, 75 g / m ² ) was used.

  As an evaluation of the present invention, a storage mode of 40 ° C./90% RH / 14 days is provided as a pretreatment before image evaluation, and then the printing ratio is 1% in a high temperature and high humidity environment (30 ° C./80% RH). Using this image, 10,000 sheets were printed in the monochrome printing mode by the continuous printing method shown below.

  The image forming speed was set to the speed in the plain paper mode.

  Image evaluation was performed based on the following evaluation criteria using the 5000th image.

<Examples 24 to 27>
(Image evaluation)
The evaluation was performed by changing the brush hair density and diameter (thickness) of the charging brush.

<Example 28>
(Image evaluation)
The obtained black toner 1, magenta toner 1, cyan toner 1 and yellow toner 1 were used for evaluation in the full color mode. Like the evaluation with a single color, all items were rated as A.

<Comparative Examples 1 and 2>
(Image evaluation)
Image evaluation was performed according to the following method using the obtained toners 4 to 5.

<Comparative Examples 3 to 4>
(Image evaluation)
Evaluation was performed by changing the volume resistance value of the charging brush.

<Comparative Example 5>
(Image evaluation)
The charging brush was removed for evaluation.

  Each evaluation result is shown in Table 2.

[Developability evaluation method]
(Measurement of fogging)
The fog was measured using a REFECTOMETER MODEL TC-6DS (manufactured by Tokyo Denshoku Co., Ltd.) and calculated according to the following formula. A lower fog value is better.
Fog (reflectance;%) = (reflectance of standard paper;%) − (reflectance of white solid portion of sample;%)
A: 1.5% or less B: 1.5% and 2.5% or less C: 2.5% and 3.5% or less D: 3.5% or more

(Transfer efficiency)
As for transfer efficiency, the toner transferred on the paper with respect to the toner basis weight developed on the photoconductor using the image forming apparatus shown in FIG. 1 with the developer after passing 5000 sheets, in a high temperature and high humidity environment (30 ° C./80% RH). The basis weight ratio was evaluated based on the following evaluation criteria.
A: 90% or more.
B: More than 80% and less than 90%.
C: More than 70% and less than 80%.
D: Less than 70%.

(Intermediate transfer member cleanability)
The intermediate transfer member cleaning property was evaluated based on the following evaluation criteria by visually observing the surface of the intermediate transfer member and further observing image defects.
A: No defects are recognized at all on the surface of the intermediate transfer member and the image.
B: In the latter half of the durability, some contamination is observed on the surface of the intermediate transfer member, but it does not appear in the image.
C: In the latter half of the durability, some contamination is observed on the surface of the intermediate transfer member, and some unevenness occurs in the image.
D: In the latter half of the durability, the surface of the intermediate transfer member is very dirty, and the image is uneven.

(Solid uniformity)
The obtained solid image on the transfer paper was evaluated as A, B, C, and D with a density difference of 5 points.
A: 5% or less B: Over 5% and 10% or less C: Over 10% and 15% or less D: Over 15%

(Image density change)
The image density is measured with a Macbeth densitometer or a color reflection densitometer (for example, Colorreflection densityometer X-RITE 404 Amanufactured by X-Rite Co.).

Evaluation is based on the difference between the initial density and the density after the endurance of 10,000 sheets.
A: 10% or less B: Over 10% and 20% or less C: Over 20% and 30% or less D: Over 30%

(Intermediate transfer member contamination)
The intermediate transfer member contamination was evaluated based on the following evaluation criteria by visually observing the belt surface and further observing image defects.
A: Defects are not recognized at all on the belt surface and the image.
B: In the latter half of the durability, the belt surface is slightly stained but does not appear in the image.
C: In the latter half of the durability, some contamination is observed on the belt surface, and some unevenness occurs in the image.
D: In the latter half of the durability, the belt surface is very dirty, and the image is uneven.

(Fixing stability)
10,000 sheets are continuously fed under the condition of the heating member set temperature of 150 ° C., and the fixability of the first and 5000th sheets is confirmed. The obtained fixed image is rubbed twice with sylbon paper applied with a load of 4900 N / m ² , and fixing is performed when the image density reduction rate before and after the rubbing becomes 10% or less. The following four ranks were evaluated according to the degree.
A: Initially fixed after passing 10,000 sheets and the reduction rate is 10% or less.
B: Fixed at the beginning, but not offset after passing 10,000 sheets, but the density reduction rate is 10% or more.
C: Initially fixed, but offset after 10,000 sheets passed, and the back surface is dirty.
D: Offset is in the initial stage.

It is explanatory drawing of an example of the image forming apparatus using the developing device of this invention. It is explanatory drawing of an example of the apparatus which measures the volume resistance value in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Photosensitive drum charging roller 3 Exposure apparatus 4 Developing apparatus 5 Primary transfer roller 6 Cleaning apparatus 6a Cleaning blade 7 Fixing apparatus 11 Lower electrode 12 Upper electrode 14 Ammeter 15 Constant voltage apparatus 17 Measurement sample 18 Guide ring 30 Intermediate transfer belt 31 Pickup roller 32 Secondary transfer roller 33 Charging roller 34 Charging brush 35 Paper transport belt 36 Paper discharge section

Claims (16)

The formation of a toner image on the first image carrier and the primary transfer of the toner image onto the second image carrier are repeated for a plurality of color toner images, and a plurality of colors are formed on the second image carrier. After the toner images are superimposed, the plurality of color toner images are secondarily transferred onto a transfer material in a lump, and at least one of the transfer residual toner remaining on the second image carrier after the secondary transfer is transferred. By applying an electric charge with the above-described fixed charging brush, the transfer residue is reversely transferred from the second image carrier to the first image carrier and reversely transferred by the cleaning device for the first image carrier. A toner used in an image forming method for collecting toner,
When the toner is charged by shaking under a condition of a temperature of 23 ° C./humidity of 50%, the aggregation degree (charge aggregation degree) A is 25 to 85%, and the volume resistance value B of the toner and the fixed A toner having a charging brush volume resistance value ratio B / C of 1 × 10 ^{5 to} 1 × 10 ⁹ .   2. The toner according to claim 1, wherein the toner has a cohesion degree D of 10 to 35% and a relationship with the charge cohesion degree A is A> D.   The toner according to claim 1, wherein the repose angle E of the toner is 10 to 30 °, and the repose angle F is 15 to 45 °.   The toner according to any one of claims 1 to 3, wherein an average circularity measured by the flow type particle image measuring device of the toner is 0.950 to 0.995.   4. The toner according to claim 1, wherein an average circularity measured by the flow type particle image measuring device of the toner is 0.960 to 0.995. 5.   The toner according to claim 1, wherein the toner has a melt viscosity at 100 ° C. of 15000 to 80,000 (PaS).   6. The toner according to claim 1, wherein the toner has a melt viscosity at 100 ° C. of 15000 to 60000 (PaS).   The toner according to claim 1, wherein the toner has a charge aggregation degree A of 30 to 70%.   The toner according to claim 1, wherein the repose angle E of the toner is 10 to 30 °, and the repose angle F is 20 to 40 °. The ratio B / G of the volume resistivity B of the toner at a temperature of 23 ° C./humidity of 50% and the volume resistivity of the toner at a temperature of 30 ° C./humidity of 80% is 1 × 10 ^{1 to} The toner according to claim 1, wherein the toner is 1 × 10 ⁴ . The toner includes, as external additives, silica fine powder a having a volume resistance value of 1 × 10 ^{10 to} 1 × 10 ¹⁷ and non-silica fine powder b having a volume resistance value of 1 × 10 ^{5 to} 1 × 10 ¹³ (however, the volume of a) The toner according to claim 1, wherein a volume resistance value (resistance value> b) is used. The formation of a toner image on the first image carrier and the primary transfer of the toner image onto the second image carrier are repeated for a plurality of color toner images, and a plurality of colors are formed on the second image carrier. After superimposing the toner images, the plurality of color toner images are collectively transferred to a transfer material to form a color image, and after the secondary transfer, the transfer residue remaining on the second image carrier is also transferred. The toner is reversely transferred from the second image carrier onto the first image carrier by applying an electric charge with at least one fixed charging brush, and further, the first image carrier is cleaned. An image forming method for collecting by an apparatus,
The toner has an aggregation degree (charge aggregation degree) A of 25 to 85% when charged by shaking under a condition of a temperature of 23 ° C./humidity of 50%, and the toner has a volume resistance value B and the fixed value. An image forming method satisfying that the ratio B / C of the volume resistance value C of the charging brush is 1 × 10 ^{5 to} 1 × 10 ⁹ .   13. The image forming method according to claim 12, wherein the fixed charging brush is of a non-rotating type. 14. The image forming method according to claim 12, wherein the hair density H of the fixed charging brush is 1 × 10 ^{6 to} 1 × 10 ⁹ (lines / m ² ). When the brush bristle density is H (lines / m ² ), the brush bristle average diameter is I (m), and the toner weight average particle diameter (D4) is J (m), the relational expression satisfies the following formula. The image forming method according to claim 12, wherein the image forming method is an image forming method.
1 × 10 ⁻⁵ <H × I × J <1 × 10 ⁰   16. The image forming method according to claim 12, wherein the image forming method has a tandem configuration in which four color developing devices are arranged in a linear direction, and the transfer residual toner is collected by being distributed to the four developing devices. The image forming method described.

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