EP3825766A1 - Toner set, image forming method, and scratch image formed product - Google Patents

Toner set, image forming method, and scratch image formed product Download PDF

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Publication number
EP3825766A1
EP3825766A1 EP20208637.7A EP20208637A EP3825766A1 EP 3825766 A1 EP3825766 A1 EP 3825766A1 EP 20208637 A EP20208637 A EP 20208637A EP 3825766 A1 EP3825766 A1 EP 3825766A1
Authority
EP
European Patent Office
Prior art keywords
toner
image forming
scratch
image
developer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP20208637.7A
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German (de)
English (en)
French (fr)
Inventor
Kazumi Suzuki
Daichi Hisakuni
Toyoshi Sawada
Akihiro Kaneko
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ricoh Co Ltd
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Ricoh Co Ltd
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Filing date
Publication date
Application filed by Ricoh Co Ltd filed Critical Ricoh Co Ltd
Publication of EP3825766A1 publication Critical patent/EP3825766A1/en
Pending legal-status Critical Current

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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
    • G03G9/087—Binders for toner particles
    • G03G9/08742—Binders for toner particles comprising macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • G03G9/08755—Polyesters
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G8/00—Layers covering the final reproduction, e.g. for protecting, for writing thereon
    • 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
    • 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
    • G03G9/0827—Developers with toner particles characterised by their shape, e.g. degree of sphericity
    • 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
    • G03G9/087—Binders for toner particles
    • G03G9/08702—Binders for toner particles comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • G03G9/08706—Polymers of alkenyl-aromatic compounds
    • G03G9/08708—Copolymers of styrene
    • G03G9/08711—Copolymers of styrene with esters of acrylic or methacrylic acid
    • 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
    • G03G9/087—Binders for toner particles
    • G03G9/08784—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775
    • G03G9/08795—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775 characterised by their chemical properties, e.g. acidity, molecular weight, sensitivity to reactants
    • 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
    • G03G9/087—Binders for toner particles
    • G03G9/08784—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775
    • G03G9/08797—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775 characterised by their physical properties, e.g. viscosity, solubility, melting temperature, softening temperature, glass transition temperature
    • 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
    • G03G9/09—Colouring agents for toner particles
    • G03G9/0902—Inorganic compounds
    • 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
    • G03G9/097—Plasticisers; Charge controlling agents
    • G03G9/09708—Inorganic compounds
    • 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
    • G03G9/097—Plasticisers; Charge controlling agents
    • G03G9/09708—Inorganic compounds
    • G03G9/09725—Silicon-oxides; Silicates

Definitions

  • the present disclosure relates to a toner set, an image forming method, and a scratch image formed product.
  • an electrostatic latent image is formed on a photoconductor (e.g., photoconductive substance), and a charged toner is attached to the electrostatic latent image to form a visible image.
  • the visible image is then transferred onto a recording medium (e.g., paper) and fixed thereon, thereby outputting an image.
  • JP-4139643-B discloses a scratch sheet made by forming an image on a substrate using an image forming device and further forming a peeling layer having peelability on demand.
  • a concealing layer (scratch concealing layer) is formed with an ink having peelability. Scratch images are widely used for instant lottery tickets, prize lottery tickets, direct mails, campaign sheets, and the like.
  • the scratch concealing layer demonstrates concealability that makes the background image invisible from the outside, and peelability, when being scratched with a coin or a nail, that makes the background image visible.
  • the scratch concealing layer has been formed by offset printing, gravure printing, screen printing, or the like, and has been unsuitable for low-volume, high-mix production.
  • JP-4139643-B is only for forming the peeling layer, which is insufficient from the viewpoint of on-demand property.
  • JP-2013-068787-A and JP-2013-088700-A propose on-demand production of scratch sheets using electrophotography.
  • the scratch sheets are those require a protective layer. Addition of such a layer and an increase of the number of processes give a room for improvement in terms of device configuration and cost.
  • An object of the present invention is to provide a toner set suitable for producing a scratch image formed product having a scratch layer that exhibits excellent peelability.
  • a toner set is provided that is suitable for producing a scratch image formed product having a scratch layer that exhibits excellent peelability.
  • the toner set comprises an image forming toner and a scratch toner.
  • ) between a solubility parameter (SPi) (cal/cm 3 ) 0.5 of the image forming toner and a solubility parameter (SPs) (cal/cm 3 ) 0.5 of the scratch toner is 1.1 (cal/cm 3 ) 0.5 or greater.
  • the toner set according to an embodiment of the present invention contains an image forming toner and a scratch toner.
  • between a solubility parameter (SPi) (cal/cm 3 ) 0.5 of the image forming toner and a solubility parameter (SPs) (cal/cm 3 ) 0.5 of the scratch toner is 1.1 (cal/cm 3 ) 0.5 or greater, preferably greater than 1.4 (cal/cm 3 ) 0.5 .
  • the peelability refers to a property of the scratch layer formed with the scratch toner on a background image to be peeled off when the scratch layer is scraped.
  • the upper limit of the absolute difference is not particularly limited and can be suitably selected to suit to a particular application, and may be, for example, 3.5.
  • the scratch toner is a toner for concealing an image formed with the image forming toner and for forming the scratch layer that can be peeled off by scratch.
  • the solubility parameter (SPi) the image forming toner is not particularly limited and can be suitably selected to suit to a particular application, and may be, for example, 10.0 (cal/cm 3 ) 0.5 or greater and 12.0 (cal/cm 3 ) 0.5 or less.
  • the solubility parameter (SPs) of the scratch toner is not particularly limited and can be suitably selected to suit to a particular application, and may be, for example, 7.5 (cal/cm 3 ) 0.5 or greater and 10.0 (cal/cm 3 ) 0.5 or less.
  • solubility parameter (SPi) of the image forming toner be larger than the solubility parameter (SPs) of the scratch toner in view of image fixability.
  • the image forming toner and the scratch toner each may contain a binder resin, a colorant, and a release agent, and may further contain other components as necessary.
  • binder resin contained in the image forming toner examples include, but are not limited to, amorphous polyester, addition polymerization resin, hybrid resin, and crystalline polyester.
  • binder resin contained in the scratch toner examples include, but are not limited to, amorphous polyester, addition polymerization resin, hybrid resin, and crystalline polyester.
  • the binder resin contained in the image forming toner comprises an amorphous polyester.
  • the binder resin contained in the scratch toner comprises a styrene-acryl resin.
  • a proportion of the amorphous polyester in the binder resin contained in the image forming toner is 75% by mass or greater.
  • a proportion of the styrene-acryl resin in the binder resin contained in the scratch toner is 75% by mass or greater.
  • ⁇ Ev evaporation energy
  • V molecular volume
  • ⁇ Ev/V cohesive energy density
  • the solubility parameter can be measured by, for example, the method proposed by Small et al. or the method proposed by Fedors et al.
  • the solubility parameter of the toner is determined by multiplying the solubility parameter of the binder resin and each component compatibilized with the binding resin with the respective weight percentage, and averaging the resulting products. Toner constituent components other than the binder resin and those compatibilized with the binder resin, such as release agents and colorants, are not used for the calculation of solubility parameter.
  • composition and weight percentages of the toner constituent components can be determined as follows.
  • the dissolved components are evaporated to dryness, and 1 mg of the obtained components are collected and dissolved in 1 ml of chloroform and set in a mass spectrometer (JMS-T100GC manufactured by JEOL Ltd.). A measurement is performed under the following conditions: the cathode voltage is -10 kv, the spectrum recording interval is 0.4 s, and the measurement mass range (m/z) is from 10 to 2,000.
  • the intensity of each carbon number of ester compounds is set to 100 in total, and the relative intensity of each carbon number is calculated to calculate the maximum intensity.
  • Measuring Device Pyrolysis-gas chromatography-mass spectrometer (Py-GCMS) Analyzer: QP2010 manufactured by Shimadzu Corporation Heating furnace: Py2020D manufactured by Frontier Laboratories Ltd.
  • Heating temperature 320 degrees C
  • Temperature rise condition 50 degrees C (held for 1 minute) -> temperature rise (at 10 degrees C/min) -> 340 degrees C (held for 7 minutes)
  • Split ratio 1:100
  • Measurement mode Scan mode Search data: NIST 20 MASS SPECTRAL LIB. Measurement of Solubility Parameter (SP) of Amorphous Polyester, Wax, Addition Polymerization Resin, Hybrid Resin, and Crystalline Polyester
  • amorphous polyester For amorphous polyester, addition polymerization resin, hybrid resin, and crystalline polyester, 100 g of toluene are added to 5 g of the toner, and the mixture is allowed to stand for 24 hours. After that, a centrifugation operation is performed using a centrifuge (HIMAC CP100NX manufactured by Hitachi, Ltd.) at a revolution of 3,000 rpm to precipitate insoluble matter, which is then separated by decantation. The dissolved components are evaporated to dryness, and the obtained components are analyzed by GC-MS (gas chromatography - mass spectrometry) to identify structural units (monomers).
  • GC-MS gas chromatography - mass spectrometry
  • wax the type of wax is identified in the same manner as described in the "Analysis of Type of Wax" section above.
  • the measurement procedure, equipment, and conditions are as follows.
  • Measuring Device ECX-500 NMR manufactured by JEOL Ltd.
  • the solubility parameter of each component is calculated from the measurement results, then the solubility parameter of the toner is calculated.
  • binder resin examples include, but are not limited to, amorphous polyester, addition polymerization resin, hybrid resin, and crystalline polyester.
  • the amorphous polyester is not particularly limited and can be suitably selected to suit to a particular application.
  • Preferred examples thereof include those having a structural unit derived from an aromatic compound.
  • the aromatic compound is not particularly limited and can be suitably selected to suit to a particular application.
  • examples thereof include, but are not limited to, alkylene oxide adducts of bisphenol A, isophthalic acid, terephthalic acid, and derivatives thereof.
  • a proportion of the structural unit derived from an aromatic compound in the amorphous polyester is preferably 50% by mass or more. When the proportion is 50% by mass or more, the toner is prevented from decreasing the chargeability.
  • the method for determining the structural unit of the amorphous polyester is not particularly limited. Examples thereof include the method descried below.
  • toner Approximately 5 g of toner are weighed, 100 g of toluene are added thereto, and the mixture is allowed to stand for 24 hours.
  • the resulted toner solution in which the toner is completely dissolved is subjected to a centrifuge operation, and the supernatant is dried to obtain solid components.
  • the obtained components are analyzed by GC-MS to determine structural units (monomer composition). Based on the information on the obtained monomer composition, a quantitative analysis is performed using 1 H NMR and 13 C NMR to determine the structure of the amorphous polyester.
  • the solubility parameter (SPr) of the amorphous polyester can be determined by the Fedors' method based on the composition of the amorphous polyester determined as above.
  • the glass transition temperature of the amorphous polyester is preferably from 45 to 65 degrees C, more preferably from 50 to 70 degrees C.
  • the glass transition temperature of the amorphous polyester is 45 degrees C or higher, heat-resistant storage stability of the toner is good.
  • it is 65 degrees C or lower, low-temperature fixability of the toner is good.
  • the softening temperature of the amorphous polyester is preferably from 90 to 150 degrees C, more preferably from 90 to 130 degrees C.
  • the softening temperature of the amorphous polyester is 90 degrees C or higher, hot offset resistance of the toner is good.
  • it is 150 degrees C or lower, ductility of the toner at fixing is good.
  • the weight average molecular weight of the amorphous polyester is preferably from 1,000 to 100,000, more preferably from 2,000 to 50,000, and particularly preferably from 3,000 to 10,000.
  • weight average molecular weight of the amorphous polyester is 1,000 or more, heat-resistant storage stability of the toner is good.
  • it is 100,000 or less, the low-temperature fixability of the toner is good.
  • the weight average molecular weight of the amorphous polyester is a polystyrene-equivalent molecular weight measured using gel permeation chromatography.
  • the proportion of the amorphous polyester in the binder resin of the image forming toner is not particularly limited and can be suitably selected to suit to a particular application, but is preferably 40% by mass or more, more preferably 50% by mass or more, and particularly preferably 75% by mass or more.
  • the proportion of the amorphous polyester in the binder resin of the scratch toner is not particularly limited and can be suitably selected to suit to a particular application.
  • Polyesters having a monomer composition generally employed for toner have a relatively large solubility parameter. Specifically, the solubility parameter is often within the range of from 10.8 to 11.4 (cal/cm 3 ) 0.5 .
  • a synthesis example of an amorphous polyester used for the binder resin of the toner is described below.
  • a reaction vessel equipped with a condenser tube, a stirrer, and a nitrogen introducing tube, 352 parts of ethylene oxide 2 mol adduct of bisphenol A, 149 parts of terephthalic acid, and 1.8 parts of tetrabutoxy titanate as a condensation catalyst are put and subjected to a reaction at 230 degrees C for 6 hours under nitrogen gas flow while removing the by-product water.
  • a reaction is performed under reduced pressures of from 5 to 20 mmHg for 1 hour until the weight average molecular weight reaches 5,000.
  • an amorphous polyester A1 having a glass transition temperature of 58 degrees C and a softening temperature of 100 degrees C is produced.
  • the solubility parameter of the amorphous polyester A1 is 11.1 (cal/cm 3 ) 0.5 .
  • the addition polymerization resin refers to a resin obtained by subjecting an addition polymerization monomer to an addition polymerization reaction.
  • Preferred examples of the addition polymerization resin include styrene-acryl resin.
  • the styrene-acryl resin is a copolymer of styrene and a vinyl monomer other than styrene.
  • the addition polymerization monomer is not particularly limited and can be suitably selected to suit to a particular application. Examples thereof include, but are not limited to, vinyl monomers.
  • vinyl monomers include, but are not limited to, styrene-based vinyl monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-amylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-4-dichlorostyrene, m-nitrostyrene, o-nitrostyrene, and p-nitrostyrene; acrylic-acid-based vinyl monomers such as acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl
  • the addition polymerization resin is available either synthetically or commercially.
  • Examples of the commercially-available products include, but are not limited to, BR-50, BR-52, MB-2539, BR-60, BR-64, BR-73, BR-75, MB-2389, BR-80, BR-82, BR-83, BR-84, BR-85, BR-87, BR-88, BR-90, BR-95, BR-96, BR-100, BR-101, BR-102, BR-105, BR-106, BR-107, BR-108, BR-110, BR-113, FB-676, MB-2660, MB-2952, MB-3012, MB-3015, MB-7033, BR-115, MB-2478, BR- 116, BR-117, BR-118, BR-122, and ER-502 (all manufactured by Mitsubishi Rayon Co., Ltd.); A-11, A-12, A-14, A-21, B-38, B-60, B-64,
  • the method for determining the structural unit of the addition polymerization resin is not particularly limited. Examples thereof include the method descried below. Approximately 5 g of toner are weighed, 100 g of toluene are added thereto, and the mixture is allowed to stand for 24 hours. The resulted toner solution in which the toner is completely dissolved is subjected to a centrifuge operation, and the supernatant is dried to obtain solid components. The obtained components are analyzed by GC-MS to determine structural units (monomer composition). Based on the information on the obtained monomer composition, a quantitative analysis is performed using 1 H NMR and 13 C NMR to determine the structure of the addition polymerization resin.
  • the solubility parameter (SPd) of the addition polymerization resin can be determined by the Fedors' method based on the composition of the addition polymerization resin determined as above.
  • Addition polymerization resins having a monomer composition generally employed for toner have a relatively small solubility parameter.
  • the solubility parameter is often within a range of from 6.5 to 10.4 (cal/cm 3 ) 0.5 .
  • the proportion of the addition polymerization resin in the binder resin of the image forming toner is not particularly limited and can be suitably selected to suit to a particular application, but is preferably from 1% to 50% by mass, more preferably from 2% to 20% by mass.
  • the proportion of the addition polymerization resin in the binder resin of the scratch toner is not particularly limited and can be suitably selected to suit to a particular application, but is preferably 1% by mass or more, more preferably 20% by mass or more, and particularly preferably 75% by mass or more.
  • the hybrid resin includes a condensation polymerization resin unit and an addition polymerization resin unit.
  • condensation polymerization resin unit examples include, but are not limited to, an amorphous polyester unit.
  • addition polymerization resin unit examples include, but are not limited to, a styrene-acryl resin unit.
  • the hybrid resin can be formed by bonding the amorphous polyester and the addition polymerization resin to each other. It is possible to adjust the solubility parameter of the hybrid resin within a wide range. As a result, it is also possible to adjust the compatibility with other resins and to function as a dispersant for a release agent.
  • the hybrid resin tends to have properties close to those of polyester, and does not significantly impair low-temperature fixability and internal cohesive force of polyester.
  • the hybrid resin may be obtained by subjecting a monomer mixture of the condensation polymerization resin unit and the addition polymerization resin unit to a condensation polymerization reaction and an addition polymerization reaction simultaneously in a single reaction vessel.
  • the monomer mixture may be subjected to a condensation polymerization reaction and an addition polymerization reaction sequentially regardless of the order of the reactions.
  • the proportion of the hybrid resin in the binder resin of the image forming toner is not particularly limited and can be suitably selected to suit to a particular application, but is preferably from 30% to 95% by mass.
  • the proportion of the hybrid resin in the binder resin of the scratch toner is not particularly limited and can be suitably selected to suit to a particular application, but is preferably from 20% to 95% by mass.
  • a mixture of 25% by mol of styrene (as a raw material monomer of an addition polymerization resin) and 25 g of di-tert-butyl peroxide (as a polymerization initiator) is dripped to a reaction vessel over a period of 1 hour under stirring at 160 degrees C.
  • the temperature is maintained for 1 hour to perform an addition polymerization reaction and thereafter raised to 200 degrees C to perform a condensation polymerization.
  • a hybrid resin HI is produced.
  • the solubility parameter of the hybrid resin HI is 10.3 (cal/cm 3 ) 0.5 .
  • the crystalline polyester refers to a polyester in which the rate of main chains which are regularly oriented to form a crystal structure is particularly high and the viscosity thereof significantly changes at a temperature around the melting point.
  • the crystalline polyester makes it possible that the toner secures a wide margin for low-temperature fixability.
  • the method for synthesizing the crystalline polyester is not particularly limited and can be suitably selected to suit to a particular application.
  • Specific examples thereof include, but are not limited to, polycondensation of a polyol and a polycarboxylic acid, ring-opening polymerization of a lactone, polycondensation of a hydroxycarboxylic acid, and ring-opening polymerization of a cyclic ester having 4 to 12 carbon atoms corresponding to a dehydration condensate between two or three molecules of a hydroxycarboxylic acid.
  • those obtained by polycondensation of a polyol and a polycarboxylic acid are preferred.
  • the polyol may be a diol alone or a combination of a diol with a trivalent or higher alcohol.
  • a crystalline polyester obtained by polycondensation of a diol and a dicarboxylic acid is preferred.
  • the proportion of the crystalline polyester in the image forming toner or the scratch toner is not particularly limited and can be suitably selected to suit to a particular application.
  • a reaction vessel equipped with a condenser tube, a stirrer, and a nitrogen introducing tube 118 parts of 1,6-hexanediol, 104 parts of fumaric acid, and 1.8 parts of tetrabutoxy titanate as a condensation catalyst are put and subjected to a reaction at 230 degrees C for 6 hours under nitrogen gas flow while removing the by-product water.
  • a reaction is performed under reduced pressures of from 5 to 20 mmHg for 1 hour until the weight average molecular weight reaches 5,000.
  • a crystalline polyester C1 having a melting point of 114 degrees C and a softening temperature of 111 degrees C is produced.
  • the solubility parameter of the crystalline polyester C1 is 10.7 (cal/cm 3 ) 0.5 .
  • the release agent examples include, but are not limited to, fatty acid esters, esters of aromatic acids such as phthalic acid, phosphoric acid esters, maleic acid esters, fumaric acid esters, itaconic acid esters, other esters, benzyls, benzoin compounds, ketones such as benzoyl compounds, hindered phenol compounds, benzotriazole compounds, aromatic sulfonamide compounds, aliphatic amide compounds, long-chain alcohols, long-chain dialcohols, long-chain carboxylic acids, and long-chain dicarboxylic acids.
  • fatty acid esters esters of aromatic acids such as phthalic acid, phosphoric acid esters, maleic acid esters, fumaric acid esters, itaconic acid esters, other esters, benzyls, benzoin compounds, ketones such as benzoyl compounds, hindered phenol compounds, benzotriazole compounds, aromatic sulfonamide compounds, aliphatic amide compounds, long-chain alcohol
  • natural waxes including: plant waxes such as carnauba wax, cotton wax, sumac wax, and rice wax; animal waxes such as beeswax and lanolin; mineral waxes such as ozokerite and ceresin; and petroleum waxes such as paraffin, microcrystalline, and petrolatum.
  • synthetic hydrocarbon waxes e.g., Fischer-Tropsch wax, polyethylene wax
  • synthetic waxes e.g., ester wax, ketone wax, ether wax
  • fatty acid amides such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, and chlorinated hydrocarbon
  • homopolymers and copolymers of polyacrylates e.g., poly-n-stearyl methacrylate, poly-n-lauryl methacrylate
  • polyacrylates e.g., poly-n-stearyl methacrylate, poly-n-lauryl methacrylate
  • crystalline polymers having a long alkyl group on a side chain e.g., poly-n-stearyl methacrylate, poly-n-lauryl methacrylate
  • the melting temperature of the release agent is preferably 100 degrees C or lower, more preferably 90 degrees C or lower.
  • the melt viscosity of the release agent is preferably from 5 to 1000 cps, more preferably from 10 to 100 cps, when measured at a temperature 10 degrees C higher than the melting point of the release agent.
  • the release agent comprises a monoester wax. Since the monoester wax has low compatibility with general binder resins, the monoester wax easily exudes out to the surface of the toner at the time the toner gets fixed. Thus, the toner exhibits high releasability while securing high gloss and sufficient low-temperature fixability.
  • the amount of the monoester wax in 100 parts by mass of the toner is from 4 to 8 parts by mass, more preferably from 5 to 7 parts by mass.
  • the monoester wax is of a synthetic ester wax.
  • the synthetic ester wax include, but are not limited to, a monoester wax synthesized from a long-straight-chain saturated fatty acid and a long-straight-chain saturated alcohol.
  • the long-straight-chain saturated fatty acid is represented by the general formula C n H 2n+1 COOH, and n is preferably about 5 to 28.
  • the long-straight-chain saturated alcohol is represented by the general formula C n H 2n+1 OH, and n is preferably about 5 to 28.
  • long-straight-chain saturated fatty acid examples include, but are not limited to, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecanoic acid, tetradecanoic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, heptacosanoic acid, montanic acid, and melissic acid.
  • long-straight-chain saturated alcohol examples include, but are not limited to, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, capryl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, pentadecyl alcohol, cetyl alcohol, heptadecyl alcohol, stearyl alcohol, nonadecyl alcohol, eicosyl alcohol, ceryl alcohol, and heptadecanol, all of which may have a substituent such as a lower alkyl group, amino group, and halogen.
  • the colorant contained in the image forming toner of the present disclosure is not particularly limited. Preferred examples thereof include black, cyan, magenta, and yellow pigments generally used for process colors.
  • black colorants include, but are not limited to, carbon black, various magnetic materials, perylene black, perinone black, and mixed colorants of cyan, magenta, and yellow colorants described below which are toned to black.
  • Preferred examples of cyan colorants include C.I. Pigment Blue 15:3.
  • Preferred examples of magenta colorants include C.I. Pigment Red 122, C.I. Pigment Red 269, and C.I. Pigment Red 81:4.
  • Preferred examples of yellow colorants include C.I. Pigment Yellow 74, C.I. Pigment Yellow 155, C.I. Pigment Yellow 180, and C.I. Pigment Yellow 185. Each of these colorants can be used alone or in combination with others.
  • Preferred examples of the colorant contained in the scratch toner of the present disclosure include pigments that absorb or reflect all visible light wavelengths and transmit a small amount of light.
  • pigments having such properties include, but are not limited to: metal powders such as aluminum powder, brass powder, copper powder, iron powder, silver powder, gold powder, and platinum powder; clay minerals such as calcium carbonate, precipitated barium sulfate, barite powder, white carbon, silica, alumina white, aluminum hydroxide, and kaolin clay; extender pigments such as talc, mica, and nepheline syenite; black pigments such as carbon black, magnetic materials, and mixed colorants of yellow, magenta, and cyan colorants toned to black; and white pigments such as titanium oxide, titanium white, zinc oxide, zinc white, zinc sulfide, lithopone, white lead, antimony white, zirconia, and zirconia oxide.
  • metal powders such as aluminum powder, brass powder, copper powder, iron powder, silver powder, gold powder, and platinum powder
  • clay minerals such as calcium carbonate, precipitated barium sulfate, barite powder, white carbon, silica, alumina
  • Each of these pigments can be used alone or in combination with others in a solid state or a liquid state in consideration of concealability, resistance to weathering, and dispersibility in toner.
  • metal pigments and white pigments that have concealability, resistance to weathering, and dispersibility in toner are preferred.
  • metal pigments aluminum pigments are more preferred.
  • white pigments titanium oxide pigments are more preferred.
  • the proportion thereof in the scratch toner is preferably 10% by mass or more and 20% by mass or less.
  • the proportion is 10% by mass or more, concealability is excellent.
  • the proportion is 20% by mass or less, charging property and electrical property are excellent.
  • the deposition amount of the scratch toner per unit area is preferably 0.6 mg/cm 2 or more.
  • the proportion thereof in the scratch toner is preferably 40% by mass or more and 60% by mass or less.
  • the proportion is 40% by mass or more, concealability is excellent.
  • the proportion is 60% by mass or less, charging property and electrical property are excellent.
  • the deposition amount of the scratch toner per unit area is preferably 0.6 mg/cm 2 or more.
  • the other components are not particularly limited and may include those usually used for toner. Examples thereof include, but are not limited to, charge controlling agents, colorants, and external additives. Each of these can be used alone or in combination with others.
  • the charge controlling agent is not particularly limited and can be suitably selected to suit to a particular application. Specific examples thereof include, but are not limited to: nigrosine; azine dyes having an alkyl group having 2 to 16 carbon atoms (described in JP-42-1627-B ); basic dyes such as C. I. Basic Yellow 2 (C. I. 41000), C. I. Basic Yellow 3, C. I. Basic Red 1 (C. I. 45160), C. I. Basic Red 9 (C. I. 42500), C. I. Basic Violet 1 (C. I. 42535), C. I. Basic Violet 3 (C. I. 42555), C. I. Basic Violet 10 (C. I. 45170), C. I. Basic Violet 14 (C. I. I.
  • dialkyl e.g., dibutyl, dioctyl
  • dialkyl tin borate compounds dialkyl tin borate compounds
  • guanidine derivatives metal complex salts of monoazo dyes described in JP-41-20153-B , JP-43-27596-B , JP-44-6397-B , and JP-45-26478-B
  • salicylic acids described in JP-55-42752-B and JP-59-7385-B
  • sulfonated copper phthalocyanine pigments organic boron salts
  • fluorine-containing quaternary ammonium salts and calixarene compounds.
  • the external additive can be suitably selected to suit to a particular application.
  • examples thereof include, but are not limited to, hydrophobized silica, titanium oxide, and alumina particles; and resin particles. Each of these can be used alone or in combination with others.
  • lubricants such as fatty metal salts and polyvinylidene fluoride particles can be used in combination.
  • the external additive improves fluidity and transferability of the toner.
  • the toner of the present disclosure to which a hydrophobized titanium oxide is externally added exhibits reduced fluctuation in the amount of charge due to humidity change.
  • the toner to which a hydrophobized silica and a hydrophobized titanium oxide are externally added with the amount of the hydrophobized titanium oxide greater than that of the hydrophobized silica exhibits improved fluidity and transferability and reduced fluctuation in the amount of charge due to humidity change.
  • the toner to which a hydrophobized silica having a primary particle diameter of from 0.01 to 0.03 ⁇ m, a hydrophobized silica having a specific surface area of 20 to 60 m 2 /g, and hydrophobized titanium oxide are externally added reduces a decrease in chargeability during actual use and exhibits improved durability.
  • the hydrophobized titanium oxide can be obtained by treating titanium oxide with a hydrophobizing agent.
  • the hydrophobizing agent include, but are not limited to, dimethyldichlorosilane, trimethylchlorosilane, methyltrichlorosilane, allyldimethyldichlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, ⁇ -chloroethyltrichlorosilane, p-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, chloromethyltrichlorosilane, p-chlorophenyltrichlorosilane, 3-chloropropyltrichlorosilane, 3-chloropropyltrimethoxysilane, vinyltriethoxysilane, vinylmethoxysilane, vinyl-tris( ⁇
  • the weight average particle diameter of the image forming toner is preferably from 4 to 8 ⁇ m, more preferably from 5 to 7 ⁇ m.
  • the weight average particle diameter is within the above range, minute dots with 600 dpi or more can be reproduced, and high quality images can be obtained. This is because the particle diameter of the toner particles is sufficiently smaller than minute dots of a latent image and thus excellent dot reproducibility is exhibited.
  • the image forming toner particles transferred onto an image output medium are arranged at a high density before getting fixed thereon, so that scratch toner particles superimposed thereon do not enter the gap between the image forming toner particles.
  • the resulting fixed image is provided with high reproducibility.
  • the weight average particle diameter of the scratch toner is preferably about 120% to 150% of the particle diameter of the contained pigment so that the toner can completely incorporate the pigment.
  • the weight average particle diameter of the scratch toner is preferably from 4 to 8 ⁇ m, more preferably from 5 to 7 ⁇ m, similar to the image forming toner.
  • the particle size distribution of toner particles can be measured using an apparatus for measuring the particle size distribution of toner particles by the Coulter principle.
  • an apparatus for measuring the particle size distribution of toner particles by the Coulter principle examples include, but are not limited to, COULTER COUNTER TA II and COULTER MULTISIZER II (both manufactured by Beckman Coulter Inc.).
  • a surfactant e.g., an alkylbenzene sulfonate
  • an electrolyte solution is an about 1% NaCl aqueous solution prepared with the first grade sodium chloride.
  • ISOTON-II manufactured by Beckman Coulter, Inc.
  • the electrolyte solution in which the sample is suspended is subjected to a dispersion treatment using an ultrasonic disperser for about 1 to 3 minutes and then to the measurement of the weight and number of toner particles using the above-described instrument equipped with a 100- ⁇ m aperture to calculate weight and number distributions.
  • the weight average particle diameter (D4) and number average particle diameter (D1) of the toner can be calculated from the weight and number distributions obtained above.
  • the glass transition temperature Tgi of the image forming toner and the glass transition temperature Tgs of the scratch toner satisfy the relation 0 ⁇ Tgi-Tgs ⁇ 10.
  • Tgi-Tgs is larger than 0, an offset phenomenon is less likely to occur at the time of fixing the toner.
  • Tgi-Tgs is smaller than 10, low-temperature fixability of the scratch image is ensured.
  • Measuring device TA-60WS and DSC-60 manufactured by Shimadzu Corporation
  • the measurement results are analyzed with a data analysis software program (TA-60 version 1.52) made by Shimadzu Corporation.
  • DrDSC curve that is a differential curve of a DSC (differential scanning calorimetry) curve obtained in the second temperature rising is analyzed using a peak analysis function of the data analysis software program to determine a peak temperature within a temperature range of from -5 to +5 degrees C with respect to the lowest temperature at which a maximum peak is observed.
  • the DSC curve is analyzed using the peak analysis function of the data analysis software program to determine a maximum endothermic temperature within the temperature range of from -5 to +5 degrees C of the peak temperature.
  • the maximum endothermic temperature is identified as the Tg of the toner.
  • the toner set according to an embodiment of the present invention may be produced by conventionally known methods such as melt-kneading-pulverization methods and polymerization methods.
  • the image forming toner and the scratch toner may be produced by either the same production method or different production methods.
  • the image forming toner may be produced by a polymerization method
  • the scratch toner may be produced by a melt-kneading-pulverization method.
  • the image forming toner may be produced by a melt-kneading-pulverization method
  • the scratch toner may be produced by a polymerization method.
  • the melt-kneading-pulverization method includes the processes of (1) melt-kneading at least the binder resin, the colorant, and the release agent, (2) pulverizing/classifying the melt-kneaded toner composition, and (3) externally adding fine inorganic particles. It is preferable that fine powder produced in the pulverizing/classifying process (2) is reused as raw materials in the process (1) for saving cost.
  • kneaders used for the kneading include, but are not limited to, closed kneaders, single-shaft or twin-shaft extruders, and open-roll kneaders.
  • Specific examples of the kneaders include, but are not limited to, KRC KNEADER (manufactured by Kurimoto, Ltd.); BUSS CO-KNEADER (manufactured by Buss AG); TWIN SCREW COMPOUNDER TEM (manufactured by Toshiba Machine Co., Ltd.); TWIN SCREW EXTRUDER TEX (manufactured by The Japan Steel Works, Ltd.); TWIN SCREW EXTRUDER PCM (manufactured by Ikegai Ironworks Corp); THREE ROLL MILL, MIXING ROLL MILL, and KNEADER (manufactured by Inoue Mfg., Inc.); KNEADEX (manufactured by Mits
  • pulverizers include, but are not limited to, COUNTER JET MILL, MICRON JET, and INOMIZER (manufactured by Hosokawa Micron Corporation); IDS-TYPE MILL and PJM JET MILL (manufactured by Nippon Pneumatic Mfg.
  • classifiers include, but are not limited to, CLASSIEL, MICRON CLASSIFIER, and SPEDIC CLASSIFIER (manufactured by Seishin Enterprise Co., Ltd.); TURBO CLASSIFIER (manufactured by Nisshin Engineering Inc.); MICRON SEPARATOR, TURBOPLEX ATP, and TSP SEPARATOR (manufactured by Hosokawa Micron Corporation); ELBOW JET (manufactured by Nittetsu Mining Co., Ltd.); DISPERSION SEPARATOR (manufactured by Nippon Pneumatic Mfg. Co., Ltd.); and YM MICRO CUT (manufactured by YASKAWA & CO., LTD. (now URAS TECHNO CO., LTD.)).
  • sieving devices for sieving coarse particles include, but are not limited to, ULTRASONIC (manufactured by Koei Sangyo Co., Ltd.); RESONASIEVE and GYRO-SIFTER (manufactured by TOKUJU CORPORATION); VIBRASONIC SYSTEM (manufactured by DALTON CORPORATION); SONICLEAN (manufactured by SINTOKOGIO, LTD.); TURBO SCREENER (manufactured by FREUND-TURBO CORPORATION); MICRO SIFTER (manufactured by MAKINO MFG. CO., LTD.); and circular vibration sieves.
  • ULTRASONIC manufactured by Koei Sangyo Co., Ltd.
  • RESONASIEVE and GYRO-SIFTER manufactured by TOKUJU CORPORATION
  • VIBRASONIC SYSTEM manufactured by DALTON CORPORATION
  • SONICLEAN manufactured by SINTOKOGIO, LTD.
  • the polymerization method examples include conventionally known methods.
  • the polymerization method may be conducted by the following procedure. First, the colorant, the binder resin, and the release agent are dispersed in an organic solvent to prepare a toner material liquid (oil phase).
  • a polyester prepolymer (A) having an isocyanate group is added to the toner material liquid and allowed to react during granulation so as to form a urea-modified polyester in the resulting toner.
  • the toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and fine resin particles.
  • the aqueous medium comprises an aqueous solvent.
  • the aqueous solvent may comprise water alone or may further comprise an organic solvent such as an alcohol.
  • the amount of the aqueous medium used is preferably from 50 to 2,000 parts by mass, more preferably from 100 to 1,000 parts by mass, based on 100 parts by mass of the toner material liquid.
  • the fine resin particles are not particularly limited and can be suitably selected to suit to a particular application as long as they are capable of forming an aqueous dispersion thereof.
  • examples thereof include, but are not limited to, vinyl resins, polyurethane resins, epoxy resins, and polyester resins.
  • the emulsion i.e., reactant
  • the organic solvent is subjected to removal of the organic solvent and subsequent washing and drying to obtain toner base particles.
  • the image forming toner and the scratch toner each can be used as a one-component developer or a two-component developer.
  • the toner according to the present disclosure is used as a two-component developer
  • the toner is mixed with a magnetic carrier.
  • the amount of the toner in the developer is preferably from 1 to 10 parts by mass based on 100 parts by mass of the carrier.
  • the magnetic carrier examples include conventionally known materials such as iron powder, ferrite powder, magnetite powder, and magnetic resin carriers, each having a particle diameter of about 20 to 200 ⁇ m, but are not limited thereto.
  • Such magnetic carriers may be coated.
  • coating materials for coating the magnetic carrier include, but are not limited to, amino resins (e.g., ureaformaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, epoxy resin), polyvinyl and polyvinylidene resins (e.g., acrylic resin, polymethyl methacrylate resin, polyacrylonitrile resin, polyvinyl acetate resin, polyvinyl alcohol resin, polyvinyl butyral resin), styrene resins (e.g., polystyrene resin, styrene-acrylic copolymer resin), halogenated olefin resins (e.g., polyvinyl chloride), polyester resins (e.g., polyethylene terephthalate resin, polybutylene terephthalate resin), polycarbonate resins, polyethylene resins, polyvinyl fluoride resins, polyvinylidene fluoride resins, poly
  • the coating material may contain a conductive powder, as necessary.
  • the conductive powder include, but are not limited to, metal powder, carbon black, titanium oxide, tin oxide, and zinc oxide.
  • the conductive powder has an average particle diameter of 1 ⁇ m or less. When the average particle diameter is 1 ⁇ m or less, it will not be difficult to control electrical resistance.
  • An image forming method includes a step of forming an image with an image forming toner and a step of forming a scratch layer over at least a part of the image with a scratch toner, and may further include other steps as necessary.
  • the image forming toner and the scratch toner are the image forming toner and the scratch toner, respectively, in the toner set according to an embodiment of the present invention.
  • the image forming method according to an embodiment of the present invention is capable of producing a scratch sheet having excellent peelability at low cost by on-demand production with a few processes without going through many processes, which can meet the demand for a wide variety of products in small quantities with a short delivery time.
  • the fixing of the image and the scratch layer on a recording medium may be performed in a single process.
  • the fixing of the image and the scratch layer on a recording medium may be performed in separate processes.
  • the deposition amount of the scratch toner to form the scratch layer is not particularly limited and can be suitably selected to suit to a particular application, but is preferably 0.60 mg/cm 2 or more, preferably 0.70 mg/cm 2 or more.
  • the upper limit of the deposition amount may be, for example, 0.90 mg/cm 2 .
  • An image forming apparatus includes at least: a photoconductor; a charger configured to charge the photoconductor; an irradiator configured to irradiate the charged photoconductor to form an electrostatic latent image; a developing device containing the toner set according to an embodiment of the present invention, configured to develop the electrostatic latent image formed on the photoconductor into a toner image with the toner set; a transfer device configured to transfer the toner image formed on the photoconductor onto a recording medium; and a fixing device configured to fix the transferred toner image on the recording medium.
  • the image forming apparatus may further include other devices as necessary.
  • An image forming method includes the processes of: charging a photoconductor; irradiating the charged photoconductor to form an electrostatic latent image; developing the electrostatic latent image formed on the photoconductor into a toner image with the toner set according to an embodiment of the present invention; transferring the toner image formed on the photoconductor onto a recording medium; and fixing the transferred toner image on the recording medium.
  • the image forming method may further include other processes as necessary.
  • the photoconductor is not limited in material, structure, and size, any may be suitably selected from known materials.
  • usable materials include, but are not limited to, inorganic photoconductors such as amorphous silicon and selenium, and organic photoconductors such as polysilane and phthalopolymethine.
  • the charger is not particularly limited and can be suitably selected to suit to a particular application as long as it is configured to charge the photoconductor.
  • the charging process is not particularly limited and can be suitably selected to suit to a particular application as long as it is a process of charging the photoconductor.
  • the charger is not particularly limited and can be suitably selected to suit to a particular application. Specific examples thereof include, but are not limited to, contact chargers equipped with a conductive or semiconductive roller, brush, film, or rubber blade and non-contact chargers employing corona discharge such as corotron and scorotron.
  • the charging process may be performed by applying a voltage to a surface of the photoconductor by the charger.
  • the shape of the charger is determined in accordance with the specification or configuration of the image forming apparatus, and may be in the form of a roller, a magnetic brush, a fur brush, etc.
  • the charger is not limited to the contact charger. However, the contact charger is preferred because the amount of by-product ozone is small.
  • the irradiator is not particularly limited and can be suitably selected to suit to a particular application as long as it is configured to irradiate the charged photoconductor to form an electrostatic latent image.
  • the irradiation process is not particularly limited and can be suitably selected to suit to a particular application as long as it is a process for irradiating the charged photoconductor to form an electrostatic latent image.
  • the irradiator is not particularly limited and can be suitably selected to suit to a particular application as long as it can irradiate the surface of the photoconductor charged by the charger with light containing information of an image to be formed.
  • Specific examples thereof include, but are not limited to, various irradiators of radiation optical system type, rod lens array type, laser optical type, and liquid crystal shutter optical type.
  • the light source used for the irradiator is not particularly limited and can be suitably selected to suit to a particular application. Specific examples thereof include, but are not limited to, luminescent matters such as fluorescence lamp, tungsten lamp, halogen lamp, mercury lamp, sodium lamp, light-emitting diode (LED), laser diode (LD), and electroluminescence (EL).
  • luminescent matters such as fluorescence lamp, tungsten lamp, halogen lamp, mercury lamp, sodium lamp, light-emitting diode (LED), laser diode (LD), and electroluminescence (EL).
  • any type of filter can be used, such as sharp cut filter, band pass filter, near infrared cut filter, dichroic filter, interference filter, and color-temperature conversion filter.
  • the irradiation process may be performed by irradiating the surface of the photoconductor with light containing image information by the irradiator.
  • the irradiation process can also be performed by irradiating the back surface of the photoconductor with light containing image information.
  • the developing device is not particularly limited and can be suitably selected to suit to a particular application as long as it is capable of developing the electrostatic latent image formed on the photoconductor into a toner image with the toner set according to an embodiment of the present invention.
  • the developing process is not particularly limited and can be suitably selected to suit to a particular application as long as it is a process of developing the electrostatic latent image formed on the photoconductor into a toner image with the toner set according to an embodiment of the present invention.
  • the developing device includes developing units storing respective toners of the toner set, each configured to apply the toner to the electrostatic latent image by contacting or without contacting the electrostatic latent image. More preferably, each developing unit is equipped with a container containing the toner.
  • the developing unit may be either a monochrome developing unit or a multicolor developing unit.
  • the developing unit includes a stirrer that frictionally stirs and charges the toner of the toner set (hereinafter simply "toner") and a rotatable magnet roller.
  • toner particles and carrier particles are mixed and stirred.
  • the toner particles are charged by friction and retained on the surface of the rotating magnet roller, thus forming magnetic brush.
  • the magnet roller is disposed proximity to the electrostatic latent image bearer (photoconductor), so that a part of the toner particles composing the magnetic brush formed on the surface of the magnet roller are moved to the surface of the electrostatic latent image bearer (photoconductor) by an electric attractive force.
  • the electrostatic latent image is developed with the toner particles and a toner image is formed with the toner particles on the surface of the electrostatic latent image bearer (photoconductor).
  • the toner image includes both a toner image formed of the image forming toner and a toner image formed of the scratch toner.
  • the transfer device is not particularly limited and can be suitably selected to suit to a particular application as long as it is configured to transfer the toner image formed on the photoconductor onto a recording medium.
  • the transfer process is not particularly limited and can be suitably selected to suit to a particular application as long as it is a process of transferring the toner image formed on the photoconductor onto a recording medium.
  • the transfer device includes a primary transfer device configured to transfer the toner image onto an intermediate transferor to form a composite transfer image, and a secondary transfer device configured to transfer the composite transfer image onto a recording medium.
  • the transfer process includes primarily transferring the toner image onto an intermediate transferor and secondarily transferring the toner image onto a recording medium.
  • the transfer process may be performed by the transfer device, specifically charging the toner image on the photoconductor by a transfer charger.
  • each color toner is sequentially superimposed on one another on the intermediate transferor to form a composite image thereon and then the composite image on the intermediate transferor is secondarily transferred onto the recording medium at once.
  • the intermediate transferor is not particularly limited and can be suitably selected from among known transferors to suit to a particular application. Preferred examples thereof include, but are not limited to, a transfer belt.
  • the transfer device (including the primary transfer device and the secondary transfer device) preferably includes a transferrer configured to separate the toner image formed on the photoconductor to the recording medium side by charging.
  • a transferrer configured to separate the toner image formed on the photoconductor to the recording medium side by charging.
  • Specific examples of the transferrer include, but are not limited to, a corona transferrer utilizing corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transferrer.
  • the recording medium is typically plain paper, it is not particularly limited and can be suitably selected to suit to a particular application as long as it is capable of transferring an unfixed image developed.
  • a PET (polyethylene terephthalate) base for use in overhead projector (OHP) can be used as the recording medium.
  • the fixing device is not particularly limited and can be suitably selected to suit to a particular application as long as it is capable of fixing the transferred toner image on the recording medium.
  • the fixing process is not particularly limited and can be suitably selected to suit to a particular application as long as it is a process of fixing the transferred toner image on the recording medium.
  • Preferred examples of the fixing device include known heat-pressure members.
  • Specific examples of the heat-pressure members include, but are not limited to: a combination of a heat roller and a pressure roller; and a combination of a heat roller, a pressure roller, and an endless belt.
  • the fixing process may be performed either each time each toner image is transferred onto the recording medium or at once after all toner images are superimposed on one another.
  • the fixing process may be performed by the fixing device.
  • the heating temperature of the heat-pressure member is preferably from 80 to 200 degrees C.
  • the fixing device may be used together with or replaced with an optical fixer according to the purpose.
  • the fixing pressure is not particularly limited and can be suitably selected to suit to a particular application, but is preferably from 10 to 80 N/cm 2 .
  • the other devices to be optionally included may be, for example, a cleaner, a neutralizer, a recycler, and/or a controller.
  • the other processes to be optionally included may be, for example, a cleaning process, a neutralization process, a recycle process, and a control process.
  • the neutralizer is not particularly limited and can be suitably selected to suit to a particular application as long as it is capable of eliminate charge on the photoconductor by application of a neutralization bias thereto.
  • Specific examples of the neutralizer include, but are not limited to, a neutralization lamp.
  • the neutralization process is not particularly limited and can be suitably selected to suit to a particular application as long as the photoconductor is neutralized by application of a neutralization bias thereto.
  • the neutralization process can be performed by the neutralizer.
  • the recycler is not particularly limited and can be suitably selected to suit to a particular application as long as it is capable of making the developing device recycle the toner removed in the cleaning process.
  • Specific examples of the recycler include, but are not limited to, a conveyer.
  • the recycle process is not particularly limited and can be suitably selected to suit to a particular application as long as the toner particles removed in the cleaning process are recycled by the developing device.
  • the recycle process can be performed by the recycler.
  • FIG. 1 is a schematic diagram illustrating an image forming apparatus according to an embodiment of the present invention.
  • Image data sent to an image processor 14 generates image signals of five colors including Y (yellow), M (magenta), C (cyan), Bk (black), and S (scratch).
  • the image processor 14 transmits the image signals of Y, M, C, Bk, and S to a writing device 15.
  • the writing device 15 modulates five laser beams corresponding to Y, M, C, Bk, and S image signals and scans respective photoconductor drums 21, 22, 23, 24, and 25 having been charged by respective chargers 51, 52, 53, 54, and 55, thus sequentially forming respective electrostatic latent images thereon.
  • the first photoconductor drum 21 corresponds to Y
  • the second photoconductor drum 22 corresponds to M
  • the third photoconductor drum 23 corresponds to C
  • the fourth photoconductor drum 24 corresponding to Bk
  • the fifth photoconductor drum 25 corresponds to S.
  • developing units 31, 32, 33, 34, and 35 serving as the developing device, form toner images of respective colors on the respective photoconductor drums 21, 22, 23, 24, and 25.
  • a sheet feeder 16 feeds a transfer sheet onto a transfer belt 70.
  • Transfer chargers 61, 62, 63, 64, and 65 sequentially transfer each toner image onto the respective photoconductor drums 21, 22, 23, 24, and 25.
  • the transfer sheet is conveyed to a fixing device 80.
  • the fixing device 80 fixes the transferred toner image on the transfer sheet and conveyed to a conveyance belt 90.
  • toner images are formed on the photoconductor drums 21, 22, 23, 24, and 25 in the same manner as in FIG. 1 , then temporarily transferred onto the transfer belt 70, further transferred onto a transfer sheet by a secondary transfer device 66, and fixed on the transfer sheet by the fixing device 80.
  • the toner images are transferred onto the transfer sheet in the reverse order relative to the developing order in the image forming apparatus illustrated in FIG. 1 .
  • the S (scratch toner) image is first transferred onto the transfer belt, then the other toner images are sequentially transferred thereon by the secondary transfer device 66.
  • a separate transfer belt 71 may be provided as in an image forming apparatus illustrated in FIG. 3 .
  • the transfer belt 71 is arranged in the position where the transfer process is performed last.
  • FIG. 5 is a schematic view illustrating a developing unit 4 and a photoconductor drum 1.
  • the developing unit 4 represents one of the developing units 31, 32, 33, 34, and 35 each having almost the same configuration except for handling different color toners.
  • the photoconductor drum 1 represents one of the photoconductor drums 21, 22, 23, 24, and 25 each having almost the same configuration except for handling different color toners.
  • the developing unit 4 includes a developer container 2 containing a two-component developer.
  • a developing sleeve 11 as a developer bearer is rotatably disposed at an opening of the developer container 2 facing the photoconductor drum 1 (hereinafter simply "photoconductor 1") with a predetermined distance from the photoconductor 1.
  • the developing sleeve 11 is formed of a cylinder made of a non-magnetic material. The developing sleeve 11 rotates such that the developing sleeve 11 moves in the same direction as the photoconductor 1 that rotates in the direction indicated by arrow in FIG. 5 , at a portion where they are facing each other.
  • a magnet roller as a magnetic field generator is fixedly disposed.
  • the magnet roller has five magnetic poles N1, S1, N2, N3, and S2.
  • a regulation blade 10 as a developer regulator is attached to a portion of the developer container 2 above the developing sleeve 11.
  • the regulation blade 10 is disposed out of contact with the developing sleeve 11 toward the vicinity of the magnetic pole S2 that is approximately positioned at the uppermost point of the magnet roller in the vertical direction.
  • a supplying conveyance path 2a, a collecting conveyance path 2b, and a stirring conveyance path 2c are disposed.
  • the supplying conveyance path 2a accommodates a supplying screw 5 as a first developer stirring conveyer.
  • the collecting conveyance path 2b accommodates a collecting screw 6 as a second developer stirring conveyer.
  • the stirring conveyance path 2c accommodates a stirring screw 7 as a third developer stirring conveyer.
  • the supplying conveyance path 2a and the stirring conveyance path 2c are disposed obliquely in the vertical direction.
  • the collecting conveyance path 2b is disposed substantially horizontal to the stirring conveyance path 2c on the downstream side of the developing region of the developing sleeve 11.
  • the two-component developer contained in the developer container 2 is stirred and conveyed by the supplying screw 5, the collecting screw 6, and the stirring screw 7 within the supplying conveyance path 2a, the collecting conveyance path 2b, and the stirring conveyance path 2c and supplied to the developing sleeve 11 from the supplying conveyance path 2a.
  • the developer supplied to the developing sleeve 11 is drawn up onto the developing sleeve 11 by the magnetic pole N2 of the magnet roller.
  • the developing sleeve 11 rotates, the developer is conveyed from the magnetic pole S2 to the magnetic pole S1 via the magnetic pole N1 on the developing sleeve 11.
  • the developer reaches the developing region where the developing sleeve 11 and the photoconductor 1 are facing.
  • the regulation blade 10 magnetically regulates the layer thickness of the developer in cooperation with the magnetic pole S2. As a result, a thin layer of the developer is formed on the developing sleeve 11.
  • the magnetic pole S1 of the magnet roller, positioned in the developing region of the developing sleeve 11, is the main developing pole.
  • the developer conveyed to the developing region is formed into a magnetic brush by the magnetic pole S1 and brought into contact with the surface of the photoconductor 1, thereby developing the electrostatic latent image formed on the surface of the photoconductor 1.
  • the developer having been used for developing the electrostatic latent image is returned to the developer container 2 via the developing region and the transport pole N3 as the developing sleeve 11 rotates.
  • the developer is then separated from the developing sleeve 11 by the repulsive magnetic fields of the magnetic poles N2 and N3 and collected into the collecting conveyance path 2b by the collecting screw 6.
  • the supplying conveyance path 2a and the collecting conveyance path 2b disposed obliquely below the supplying conveyance path 2a are separated by the a first partition 3A.
  • the collecting conveyance path 2b and the stirring conveyance path 2c disposed laterally to each other are separated by a second partition 3B.
  • the second partition 3B has an opening for supplying the developer collected into the collecting conveyance path 2b to the stirring conveyance path 2c on a downstream portion thereof with respect to the direction of conveyance of developer by the collecting screw 6 in the collecting conveyance path 2b.
  • the supplying conveyance path 2a and the stirring conveyance path 2c disposed obliquely below the supplying conveyance path 2a are separated by a third partition 3C.
  • the third partition 3C has respective openings for supplying the developer on an upstream portion and a downstream portion thereof with respect to the direction of conveyance of developer by the supplying screw 5 in the supplying conveyance path 2a.
  • FIG. 6 is a cross-sectional view of the collecting conveyance path 2b and the stirring conveyance path 2c at a downstream portion with respect to the direction of conveyance of developer by the collecting screw 6.
  • An opening 2d communicating the collecting conveyance path 2b and the stirring conveyance path 2c is provided.
  • FIG. 7 is a cross-sectional view of the developing unit 4 at an upstream portion with respect to the direction of conveyance of developer by the supplying screw 5.
  • the third partition 3C has an opening 2e communicating the stirring conveyance path 2c and the supplying conveyance path 2a.
  • FIG. 8 is a cross-sectional view of the developing unit 4 at a downstream portion with respect to the direction of conveyance of developer by the supplying screw 5.
  • the third partition 3C has an opening 2f communicating the stirring conveyance path 2c and the supplying conveyance path 2a.
  • FIG. 9 is a schematic diagram illustrating the flow of the developer in the developing unit 4. Each arrow in FIG. 9 indicates the direction of movement of the developer.
  • the developer supplied from the stirring conveyance path 2c is conveyed downstream with respect to the direction of conveyance of developer by the supplying screw 5 while the developer is supplied to the developing sleeve 11.
  • An excess developer having been conveyed to a downstream portion in the supplying conveyance path 2a with respect to the direction of conveyance of developer without being supplied to the developing sleeve 11 is supplied to the stirring conveyance path 2c through the opening 2f as the first developer supply opening provided on the third partition 3C.
  • the developer having been collected from the developing sleeve 11 into the collecting conveyance path 2b by the collecting screw 6 is conveyed to a downstream potion in the collecting conveyance path 2b, in the same direction as the direction of conveyance of developer in the supplying conveyance path 2a.
  • the developer is then supplied to the stirring conveyance path 2c through the opening 2d as the second developer supply opening provided on the second partition 3B.
  • the excess developer and the collected developer having been supplied to the stirring conveyance path 2c are stirred by the stirring screw 7 and conveyed in the direction opposite to the direction of conveyance of the developer in the collecting conveyance path 2b and the supplying conveyance path 2a.
  • the developer having been conveyed to a downstream portion in the stirring conveyance path 2c with respect to the direction of conveyance of developer is supplied to an upstream portion in the supplying conveyance path 2a with respect to the direction of conveyance of developer through the opening 2e as the third developer supply opening provided on the third partition 3C.
  • a toner concentration sensor is disposed below the stirring conveyance path 2c.
  • the toner concentration sensor operates a toner supply controller to supply toner from a toner container.
  • a toner supplied through a toner supply opening 3 is conveyed by the stirring screw 7 downstream with respect to the direction of conveyance of developer while being stirred with the collected developer and the excess developer. It is preferable that the toner is supplied upstream of the stirring screw 7 for extending the stirring time from the supply to the development.
  • the developing unit 4 includes the supplying conveyance path 2a and the collecting conveyance path 2b, so that supply and collection of the developer are performed in separated developer conveyance paths. Therefore, the developer having been used for the development is prevented from coming into the supplying conveyance path 2a. Thus, a decrease of the toner concentration in the developer supplied to the developing sleeve 11 is more prevented at the more downstream side in the supplying conveyance path 2a with respect to the direction of conveyance of developer.
  • the collecting conveyance path 2b and the stirring conveyance path 2c are provided to perform collection and stirring of the developer in separated developer conveyance paths, the developer having been used for the development is prevented from falling during the stirring. Therefore, the developer having been sufficiently stirred is supplied to the supplying conveyance path 2a. Insufficient stirring of the developer to be supplied to the supplying conveyance path 2a is prevented.
  • the developer is supplied from the stirring conveyance path 2c, disposed obliquely below the supplying conveyance path 2a, to the supplying conveyance path 2a.
  • the stirring screw 7 rotates to push the developer into the opening 2e to cause the developer to overflow from the opening 2e, thereby supplying the developer to the supplying conveyance path 2a.
  • the supplying conveyance path 2a is disposed obliquely above the stirring conveyance path 2c. This configuration makes it possible to reduce stress given to the developer during movement of the developer upward as compared with a case in which the supplying conveyance path 2a is disposed vertically above the stirring conveyance path 2c.
  • FIG. 10 is a cross-sectional view of the developing unit 4 at the most downstream portion with respect to the direction of conveyance of developer by the supplying screw 5. As illustrated in FIG.
  • the third partition 3C has an opening 2g communicating the stirring conveyance path 2c and the supplying conveyance path 2a on a downstream portion from the opening 2f with respect to the direction of conveyance of developer by the supplying screw 5.
  • the opening 2g is positioned above the uppermost part of the opening 2f.
  • the developer is conveyed in the axial direction of the supplying conveyance path 2a toward the opening 2f by the supplying screw 5.
  • the developer having reached the lowermost part of the opening 2f falls into the stirring conveyance path 2c disposed therebelow through the opening 2f.
  • the developer failed to reach the lowermost part of the opening 2f is supplied to the developing sleeve 11 while being conveyed further downstream by the supplying screw 5. Therefore, on the downstream side of the opening 2f in the supplying conveyance path 2a, the bulk of the developer gradually becomes lower than the lowermost part of the opening 2f.
  • the bulk of the developer may be high at the most downstream end, since the most downstream end of the supplying conveyance path 2a is a dead end. However, when the bulk comes to have a certain height, the developer is pushed back against rotation of the supplying screw 5 and returned to the opening 2f. The developer having reached the lowermost part of the opening 2f falls into the stirring conveyance path 2c disposed therebelow through the opening 2f. Therefore, on the downstream side of the opening 2f in the supplying conveyance path 2a, the bulk of the developer is not kept increasing but kept in an equilibrium state with a gradient near the lowermost part of the opening 2f.
  • the opening 2g has a function of ensuring sufficient ventilation between the supplying conveyance path 2a and the stirring conveyance path 2c rather than a function of supplying developer between the supplying conveyance path 2a and the stirring conveyance path 2c.
  • the toner set according to an embodiment of the present invention may be contained in a process cartridge detachably mountable on an image forming apparatus body that integrally supports a photoconductor and at least one of an electrostatic latent image forming device, a developing device, and a cleaner.
  • FIG. 4 is a schematic view of a process cartridge according to an embodiment of the present invention that contains the toner of the toner set according to an embodiment of the present invention.
  • the process cartridge includes a photoconductor 120, an electrostatic latent image forming device 132, a developing device 140, and a cleaner 161.
  • the process cartridge is configured to be detachably attachable to an image forming apparatus main body such as a copier and a printer.
  • the photoconductor is driven to rotate at a predetermined circumferential speed.
  • a circumferential surface of the photoconductor is uniformly charged to a predetermined positive or negative potential by the electrostatic latent image forming device, and then irradiated with light emitted from an irradiator by slit exposure or laser beam scanning exposure, so that electrostatic latent images are sequentially formed on the circumferential surface of the photoconductor.
  • the electrostatic latent images thus formed are subsequently developed into toner images by the developing device.
  • the toner images are sequentially transferred onto a transfer material fed from a sheet feeder to between the photoconductor and the transfer device in synchronization with rotation of the photoconductor.
  • the transfer material having the transferred image thereon is separated from the surface of the photoconductor and introduced to the fixing device so that the image is fixed.
  • the transfer material having the fixed image thereon is printed out the apparatus as a copy.
  • the surface of the photoconductor is cleaned by removing residual toner particles by the cleaner and further neutralized to be repeatedly used for image formation.
  • a process cartridge includes a photoconductor and a developing device containing the toner, configured to develop an electrostatic latent image formed on the photoconductor into a toner image with the toner.
  • the process cartridge is detachably mountable on an image forming apparatus body.
  • the process cartridge of the present disclosure is configured to detachably mountable on an image forming apparatus, and contains a photoconductor to bear an electrostatic latent image and a developing device configured to develop the electrostatic latent image on the photoconductor into a toner image with the toner according to an embodiment of the present invention.
  • the process cartridge may further include other members, if necessary.
  • the developing device includes at least a developer container containing a developer containing a toner according to an embodiment of the present invention, and a developer bearer to bear and convey the developer contained in the developer container.
  • the developing device may further include a regulator to regulate the thickness of the developer layer borne on the developer bearer.
  • FIG. 11 is a schematic view of a process cartridge according to an embodiment of the present invention.
  • a process cartridge 111 includes a photoconductor drum 110, a corona charger 158, a developing device 140, a transfer roller 180, and a cleaner 190.
  • Reference numeral 195 denotes a transfer sheet, and reference symbol L denotes a laser beam.
  • the scratch image formed product according to an embodiment of the present invention includes a recording medium, an image, and a scratch layer, and may further include other elements, if necessary.
  • the image is formed over the recording medium.
  • the image is formed with an image forming toner.
  • the scratch layer is formed over at least a part of the image.
  • the scratch layer is formed with a scratch toner.
  • the image forming toner and the scratch toner are the image forming toner and the scratch toner, respectively, in the toner set according to an embodiment of the present invention.
  • the deposition amount of the scratch toner to form the scratch layer is not particularly limited and can be suitably selected to suit to a particular application, but is preferably 0.60 mg/cm 2 or more, preferably 0.70 mg/cm 2 or more.
  • the upper limit of the deposition amount may be, for example, 0.90 mg/cm 2 .
  • the material, shape, size, and structure of the recording medium are not particularly limited and can be suitably selected to suit to a particular application.
  • the scratch image formed product can be suitably used for instant lottery tickets, prize lottery tickets, direct mail, campaign sheets, and the like.
  • a toner was produced using the following toner raw materials.
  • the salicylic acid derivative zirconium salt was a compound having the following structural formula (1).
  • L 1 represents the following structure.
  • the toner raw materials listed above were preliminarily mixed using a HENSCHEL MIXER (FM20B manufactured by NIPPON COKE & ENGINEERING CO., LTD.) and melt-kneaded using a single-shaft kneader (BUSS CO-KNEADER manufactured by Buss AG) at a temperature of from 100 to 130 degrees C.
  • HENSCHEL MIXER FM20B manufactured by NIPPON COKE & ENGINEERING CO., LTD.
  • BUSS CO-KNEADER manufactured by Buss AG
  • the kneaded product was cooled to room temperature and coarsely pulverized using a ROTOPLEX to have a diameter of from 200 to 300 ⁇ m.
  • the resulted coarse particles were further pulverized into fine particles having a weight average particle diameter of 6.2 ⁇ 0.3 ⁇ m by a COUNTER JET MILL (100AFG manufactured by Hosokawa Micron Corporation) while appropriately adjusting the pulverization air pressure.
  • the fine particles were classified by size using an air classifier (EJ-LABO manufactured by MATSUBO Corporation) while appropriately adjusting the opening of the louver such that the weight average particle diameter became 7.0 ⁇ 0.2 ⁇ m and the ratio of weight average particle diameter to number average particle diameter became 1.20 or less.
  • a toner base particle A-Bk was prepared.
  • toner base particle A-Bk 100 parts were stir-mixed with external additives including 1.0 part of HDK-2000 (manufactured by Clariant) and 1.0 part of H05TD (manufactured by Clariant) using a HENSCHEL MIXER.
  • external additives including 1.0 part of HDK-2000 (manufactured by Clariant) and 1.0 part of H05TD (manufactured by Clariant) using a HENSCHEL MIXER.
  • An image forming toner A-C was prepared in the same manner as in the preparation of the image forming toner A-Bk except for replacing 10 parts of the carbon black with 5 parts of Pigment Blue 15:3.
  • An image forming toner A-M was prepared in the same manner as in the preparation of the image forming toner A-Bk except for replacing 10 parts of the carbon black with 6 parts of Pigment Red 269.
  • An image forming toner A-Y was prepared in the same manner as in the preparation of the image forming toner A-Bk except for replacing 10 parts of the carbon black with 7 parts of Pigment Yellow 185.
  • the solubility parameters of the image forming toner A-Bk, the image forming toner A-C, the image forming toner A-M, and the image forming toner A-Y were 11.1 (cal/cm 3 ) 0.5 .
  • An image forming toner B-Bk was produced using the following toner raw materials, in the same manner as in the preparation of the image forming toner A-Bk.
  • An image forming toner B-C was prepared in the same manner as in the preparation of the image forming toner B-Bk except for replacing 10 parts of the carbon black with 5 parts of Pigment Blue 15:3.
  • An image forming toner B-M was prepared in the same manner as in the preparation of the image forming toner B-Bk except for replacing 10 parts of the carbon black with 6 parts of Pigment Red 269.
  • An image forming toner B-Y was prepared in the same manner as in the preparation of the image forming toner B-Bk except for replacing 10 parts of the carbon black with 7 parts of Pigment Yellow 185.
  • the solubility parameters of the image forming toner B-Bk, the image forming toner B-C, the image forming toner B-M, and the image forming toner B-Y were 10.5 (cal/cm 3 ) 0.5 .
  • An image forming toner C-Bk was produced using the following toner raw materials, in the same manner as in the preparation of the image forming toner A-Bk.
  • An image forming toner C-C was prepared in the same manner as in the preparation of the image forming toner C-Bk except for replacing 10 parts of the carbon black with 5 parts of Pigment Blue 15:3.
  • An image forming toner C-M was prepared in the same manner as in the preparation of the image forming toner C-Bk except for replacing 10 parts of the carbon black with 6 parts of Pigment Red 269.
  • An image forming toner C-Y was prepared in the same manner as in the preparation of the image forming toner C-Bk except for replacing 10 parts of the carbon black with 7 parts of Pigment Yellow 185.
  • the solubility parameters of the image forming toner C-Bk, the image forming toner C-C, the image forming toner C-M, and the image forming toner C-Y were 10.7 (cal/cm 3 ) 0.5 .
  • An image forming toner D-Bk was produced using the following toner raw materials, in the same manner as in the preparation of the image forming toner A-Bk.
  • An image forming toner D-C was prepared in the same manner as in the preparation of the image forming toner D-Bk except for replacing 10 parts of the carbon black with 5 parts of Pigment Blue 15:3.
  • An image forming toner D-M was prepared in the same manner as in the preparation of the image forming toner D-Bk except for replacing 10 parts of the carbon black with 6 parts of Pigment Red 269.
  • An image forming toner D-Y was prepared in the same manner as in the preparation of the image forming toner D-Bk except for replacing 10 parts of the carbon black with 7 parts of Pigment Yellow 185.
  • the solubility parameters of the image forming toner D-Bk, the image forming toner D-C, the image forming toner D-M, and the image forming toner D-Y were 10.9 (cal/cm 3 ) 0.5 .
  • the process color toner set of PxP-EQR toner used for RICOH PRO C7201S was used as an image forming toner set E.
  • the solubility parameter of the toners of the image forming toner set E was 10.8 (cal/cm 3 ) 0.5 .
  • a toner was produced using the following toner raw materials.
  • the toner raw materials listed above were preliminarily mixed using a HENSCHEL MIXER (FM20B manufactured by NIPPON COKE & ENGINEERING CO., LTD.) and melt-kneaded using a single-shaft kneader (BUSS CO-KNEADER manufactured by Buss AG) at a temperature of from 100 to 130 degrees C.
  • HENSCHEL MIXER FM20B manufactured by NIPPON COKE & ENGINEERING CO., LTD.
  • BUSS CO-KNEADER manufactured by Buss AG
  • the kneaded product was cooled to room temperature and coarsely pulverized using a ROTOPLEX to have a diameter of from 200 to 300 ⁇ m.
  • the resulted coarse particles were further pulverized into fine particles having a weight average particle diameter of 10.0 ⁇ 0.3 ⁇ m by a COUNTER JET MILL (100AFG manufactured by Hosokawa Micron Corporation) while appropriately adjusting the pulverization air pressure.
  • the fine particles were classified by size using an air classifier (EJ-LABO manufactured by MATSUBO Corporation) while appropriately adjusting the opening of the louver such that the weight average particle diameter became 12.0 ⁇ 0.3 ⁇ m and the ratio of weight average particle diameter to number average particle diameter became 1.30 or less.
  • a scratch toner base particle V was prepared.
  • the solubility parameter of the scratch toner V was 7.8 (cal/cm 3 ) 0.5 .
  • a scratch toner W was produced using the following toner raw materials, in the same manner as in the preparation of the scratch toner V.
  • the solubility parameter of the scratch toner W was 9.5 (cal/cm 3 ) 0.5 .
  • a scratch toner X was produced using the following toner raw materials, in the same manner as in the preparation of the scratch toner V.
  • the solubility parameter of the scratch toner X was 9.9 (cal/cm 3 ) 0.5 .
  • a scratch toner Y was produced using the following toner raw materials, in the same manner as in the preparation of the scratch toner V.
  • the solubility parameter of the scratch toner Y was 10.5 (cal/cm 3 ) 0.5 .
  • a scratch toner Z was produced using the following toner raw materials, in the same manner as in the preparation of the scratch toner V.
  • the solubility parameter of the scratch toner Z was 9.5 (cal/cm 3 ) 0.5 .
  • the hybrid resin A is a hybrid resin containing an amorphous polyester unit and a styrene-acryl resin unit.
  • the addition polymerization resin A and the addition polymerization resin B are styrene-acryl resins.
  • the above materials were dispersed by a homomixer for 20 minutes to prepare a coating layer forming liquid.
  • Manganese (Mn) ferrite particles having a weight average particle diameter of 35 ⁇ m as core materials were coated with the coating layer forming liquid using a fluidized bed coating device while controlling the temperature inside the fluidized bed to 70 degrees C, followed by drying, so that the coating layer was formed on the surface of the core materials with an average film thickness of 0.20 ⁇ m.
  • the core materials having the coating layer were burnt in an electric furnace at 180 degrees C for 2 hours.
  • a carrier A was prepared.
  • Each toner was uniformly mixed with the carrier A by a TURBULA MIXER (available from Willy A. Bachofen AG (WAB)) at a revolution of 48 rpm for 5 minutes to be charged. Thus, each two-component developer was prepared.
  • the mixing ratio of the toner to the carrier was 6% by mass, which was equal to the initial toner concentration in the developer of the test machine.
  • Example 1 Image forming toner set Scratch toner SPi-SPs SPi SPs
  • Example 1 A 11.1 V 7.8 3.3
  • Example 2 A 11.1 W 9.5 1.6
  • Example 3 A 11.1 X 9.9 1.2
  • Example 4 A 11.1 Z 9.5 1.6
  • Example 5 B 10.5 V 7.8 2.7
  • Example 6 C 10.7 V 7.8 2.9
  • Example 7 C 10.7 W 9.5 1.2
  • Example 8 D 10.9 W 9.5 1.4
  • Example 9 D 10.9 Z 9.5 1.4
  • Example 10 E 10.8 V 7.8 3.0 Comparative Example 1 A 11.1 Y 10.5 0.6 Comparative Example 2 B 10.5 W 9.5 1.0 Comparative Example 3 C 10.7 X 9.9 0.8
  • Comparative Example 4 D 10.9 X 9.9 1.0 Comparative Example 5 E 10.8 X 9.9 0.9
  • the image forming toners were installed in the process color unit of RICOH PRO C7201S, and the scratch toner was installed in the special toner unit thereof.
  • the special toner unit was set so that the special toner was formed on the uppermost layer of a recording medium.
  • the paper sheets used for this evaluation were PPC PAPER TYPE6000 (70W) manufactured by Ricoh Co., Ltd.
  • the test chart No. 1-R 1993 of the Society of Electrophotography of Japan was printed as a background image.
  • the sheet on which the background image was printed was set in the sheet feeding tray again, and a solid scratch layer was laminated thereon to create a scratch sheet.
  • the deposition amount of the scratch layer at this time was 0.65 mg/cm 2 .
  • a background image (the test chart No. 1-R 1993 of the Society of Electrophotography of Japan) and a scratch layer were simultaneously formed through one time of printing operation, thereby creating a scratch sheet.
  • the deposition amount of the scratch layer at this time was 0.75 mg/cm 2 .
  • the prepared scratch sheets were subjected to the following evaluations.
  • the evaluation was sensory evaluation by 20 evaluators randomly selected from men and women with an age of 25 to 55 years.
  • Each scratch sheet was scraped with a 100-yen coin to evaluate the state of the base image after the scratch layer had been peeled off.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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EP20208637.7A 2019-11-22 2020-11-19 Toner set, image forming method, and scratch image formed product Pending EP3825766A1 (en)

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