EP0807858A1 - Agent de développement et son procédé de fabrication - Google Patents

Agent de développement et son procédé de fabrication Download PDF

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Publication number
EP0807858A1
EP0807858A1 EP97107882A EP97107882A EP0807858A1 EP 0807858 A1 EP0807858 A1 EP 0807858A1 EP 97107882 A EP97107882 A EP 97107882A EP 97107882 A EP97107882 A EP 97107882A EP 0807858 A1 EP0807858 A1 EP 0807858A1
Authority
EP
European Patent Office
Prior art keywords
wax
viscosity
developing agent
added
binder resin
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.)
Withdrawn
Application number
EP97107882A
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German (de)
English (en)
Inventor
Hiroshi Kawaguchi
Yukihiro Fujikura
Shuitsu Sato
Hisanobu Ajima
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.)
Toshiba Corp
Original Assignee
Toshiba Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Toshiba Corp filed Critical Toshiba Corp
Publication of EP0807858A1 publication Critical patent/EP0807858A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • G03G9/0802—Preparation methods
    • G03G9/081—Preparation methods by mixing the toner components in a liquefied state; melt kneading; reactive mixing
    • 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
    • G03G9/0802—Preparation methods
    • G03G9/0804—Preparation methods whereby the components are brought together in a liquid dispersing medium
    • G03G9/0806—Preparation methods whereby the components are brought together in a liquid dispersing medium whereby chemical synthesis of at least one of the toner components takes place
    • 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
    • G03G9/08775—Natural macromolecular compounds or derivatives thereof
    • G03G9/08782—Waxes

Definitions

  • the present invention relates to an electrophotographic developing agent, particularly, an electrophotographic developing agent used in a thermal fixing method.
  • a developing agent is required to meet various requirements.
  • the developing agent is required (i) to exhibit a high fix retention rate, (ii) to be satisfactory in smear characteristics, and (iii) not to bring about off-set phenomenon.
  • fix retention rate denotes a fixing strength of the developing agent fixed to a recording medium.
  • a high fix retention rate indicates that the developing agent is sufficiently fixed to the recording medium.
  • smear denotes a phenomenon that a mechanical friction causes the developing agent after the fixing step to be peeled off the recorded paper sheet so as to bring about smear of the images recorded on another recording paper sheet. The smear often takes place in the case where, for example, a recorded paper sheet is transferred as an original through an automatic original transfer apparatus.
  • the term "off-set phenomenon" represents a difficulty that the developing agent, which is melted by heating in the fixing step, is attached to the fixing device so as to stain the images recorded on the recording medium.
  • a so-called back stain is brought about.
  • the molten toner is attached to the pressurizing roller so as to stain the back surface of the recording paper sheet.
  • Japanese Patent Disclosure (Kokai) No. 4-358159 discloses a measure for overcoming the above-noted problems. Specifically, this prior art proposes the idea of allowing a toner to contain two kinds of waxes having different softening points. However, it is difficult to disperse uniformly a plurality of different kinds of waxes in the binder resin constituting a main component of the developing agent.
  • the developing agent it is desirable to allow the developing agent to contain a plurality of different kinds of waxes in order to meet the various properties required for the electrophotographic developing agent.
  • An object of the present invention is to provide an electrophotographic developing agent excellent in off-set resistance, shelf stability, fluidity and fixing capability.
  • a method of manufacturing a developing agent comprising:
  • a method of manufacturing a developing agent comprising:
  • a developing agent comprising:
  • a developing agent obtained by purverizing and classifying a kneaded mass prepared by melting and kneading a mixture consisting of a wax-added binder resin prepared by polymerizing a solution containing a polymerizable monomer and a first wax dispersed in the polymerizable monomer and having a first viscosity, a coloring agent, and a second wax having a viscosity higher than that of the first wax.
  • a developing agent obtained by purverizing and classifying a kneaded mass prepared by melting and kneading a mixture consisting of a wax-added binder resin prepared by polymerizing a solution containing a polymerizable monomer and a first wax dispersed in the polymerizable monomer and having a number average molecular weight of 1500 to 4000, a coloring agent, and a second wax having a number average molecular weight of 8000 to 11000.
  • a first wax having a low viscosity is added in the first step of preparing a wax-added binder resin.
  • a second wax having a viscosity higher than that of the first wax is added in the second step of melting and kneading a mixture containing the wax-added binder resin prepared in the first step.
  • a first wax having a low number average molecular weight is added in the first step of preparing a wax-added binder resin, and a second wax having a number average molecular weight higher than that of the first wax is added in the second step of melting and kneading a mixture containing the binder resin mixture prepared in the first step.
  • the particular technique of the present invention permits markedly improving the dispersion capability of the waxes in the kneaded mass. Further, the developing agent obtained from the kneaded mass is excellent in its fixing properties such as the fix retention rate and smear properties, off-set resistance, shelf stability, and fluidity.
  • the method of manufacturing a developing agent according to a first aspect of the present invention comprises a first step of preparing a wax-added binder resin by polymerizing a solution containing a polymerizable monomer and a first wax dispersed in the polymerizable monomer and having a first viscosity, and a second step of melting and kneading a mixture consisting of the wax-added binder resin prepared in the first step, a coloring agent, and a second wax having a viscosity higher than that of the first wax.
  • Additives such as a electrostatic charge control agent can be added when kneading.
  • the kneaded mass is further subjected, as required, to a drying step, a pulverizing step, and a classifying step so as to prepare desired toner particles used for obtaining the developing agent of the present invention.
  • the particular solution is subjected to polymerization, preferably with stirring.
  • a first wax having a low viscosity is added in the first step of preparing a wax-added binder resin. Further, a second wax having a viscosity higher than that of the first wax is added in the second step of melting and kneading a mixture containing the binder resin mixture prepared in the first step so as to obtain a kneaded mass.
  • the particular technique of the first aspect of the present invention permits improving the dispersion capability of the waxes in the resultant toner particles. Further, the developing agent obtained by using these toner particles exhibits excellent off-set resistance, shelf life, fluidity and fixing capability.
  • both first and second waxes are added together in the first step of preparing the wax-added binder resin
  • bleeding takes place in the resin mixture obtained after the second step of melting and kneading a mixture containing the binder resin mixture prepared in the first step.
  • the developing agent prepared by using a resin mixture accompanied by the bleeding problem is attached to a drum, giving rise to a filming problem. If such a developing agent is used for an image formation, the formed image is rendered poor in image quality.
  • both first and second waxes are added together in the second step of melting-kneading a mixture containing the binder resin mixture prepared in the first step, the resultant developing agent is rendered markedly poor in both fluidity and shelf life. If such a developing agent is used for an image formation, fogging takes place in the formed image. Also, charging properties of the developing agent are made unsatisfactory.
  • first and second waxes are added in different steps in the present invention.
  • a first wax having a low viscosity and a second wax having a high viscosity are added in the first step of preparing a wax-added binder resin and the second step of melting and kneading a mixture containing the binder resin mixture prepared in the first step, respectively.
  • the flow chart in FIG. 1 schematically shows a method of manufacturing a developing agent according to the first aspect of the present invention.
  • a first wax and a polymerizable monomer are dispersed in a solvent.
  • the resultant dispersion is subjected to polymerization, which is performed while stirring the dispersion, in the first step (ST 1) so as to prepare a wax-added binder resin.
  • a mixture prepared adding a second wax having a viscosity higher than that of the first wax, a coloring agent, etc. to the binder resin mixture prepared in the first step is melted and kneaded in the second step (ST 2). Further, the kneaded mass prepared in the second step is pulverized and classified in the third step (ST 3) so as to obtain toner particles of a desired particle size.
  • the viscosity of the wax is determined by a Brookfield viscometer.
  • viscosity represents an inner friction of a liquid, which can be detected by measuring the time required for a predetermined amount of liquid to flow through a capillary tube.
  • the viscosity of wax depends on the composition thereof. Specifically, the wax viscosity is increased with increase in the molecular weight of the main component of the wax. Where the wax contains an ester as a main component, the wax viscosity is lowered with increase in the degree of unsaturation of the ester, if the ester has the same number of carbon atoms. Viscosity can be roughly classified into an absolute viscosity, a kinetic viscosity and an industrial viscosity.
  • the absolute viscosity which is precisely defined physically, is indicated by a unit poise (P), which is g/cm.s.
  • P unit poise
  • cP centipoise
  • the kinetic viscosity is obtained by dividing an absolute viscosity of a liquid at a certain temperature by the density of the liquid at the same temperature, and is indicated by a unit stoke (St).
  • St unit stoke
  • the kinetic viscosity is indicated by centistoke (cSt), i.e., 1/100 St.
  • the industrial viscosity is measured by a method defined individually by using a special measuring instrument such as a Redwood viscometer or a Saybolt viscometer.
  • the wax viscosity defined in the present invention denotes a Brookfield viscosity measured by using a Brookfield viscometer.
  • the Brookfield viscometer is a kind of an inner cylinder rotating type rotational viscometer. An outer cylinder is not used in the Brookfield viscometer, and an inner cylinder is allowed to hang directly a sample. The inner cylinder is rotated at a predetermined rotating speed.
  • the Brookfield viscometer can be used conveniently because the viscosity of a sample in a liquid tank can be measured directly during operation of the factory including the liquid tank.
  • the Brookfield viscometer can also be called a B-type viscometer.
  • each of the first and second waxes is defined in terms of a preferred range of the viscosity.
  • a first preferred embodiment relating to the first aspect of the present invention provides a method of manufacturing a developing agent, comprising:
  • the wax is not compatible with the resin and tends to fail to be dispersed sufficiently in the resultant toner. If the viscosity exceeds 1000 cP, however, the wax is too viscous to be dispersed sufficiently even if the wax is added in the first step of preparing the binder resin mixture.
  • the viscosity of the second wax at 100°C is less than 10000 cP, a difference in viscosity between the wax and the binder resin is so large that the wax is not compatible with the resin and tends to fail to be dispersed sufficiently in the melting-kneading step. If the viscosity exceeds 100000 cP, however, fluidity of the wax itself tends to be impaired, leading to a poor dispersion.
  • the first and second waxes are further defined in terms of a further preferred range of viscosity.
  • the preferred second embodiment provides a method of manufacturing a developing agent, comprising:
  • the first and second waxes are defined in terms of the mixing amounts.
  • the third embodiment of the first aspect provides a method of manufacturing a developing agent, comprising:
  • the wax fails to act sufficiently as a repellent agent when the prepared developing agent is used in an image forming operation. As a result, the off-set resistance of the developing agent tends to be impaired. If the first wax is added in an amount exceeding 7% by weight, however, the wax particles once dispersed in the toner are fused again together, resulting in failure for the first wax to be dispersed sufficiently in the toner. On the other hand, if the amount of the second toner is less than 0.1% by weight, the prepared developing agent tends to be poor in its resistance to smear. If the amount exceeds 3% by weight, however, the second wax fails to be dispersed sufficiently in the toner.
  • the fourth embodiment is directed to a method of manufacturing a developing agent, comprising:
  • the method according to the fourth preferred embodiment of the first aspect permits producing the merits of both the first and third preferred embodiments.
  • the method according to the second aspect of the present invention is substantially equal to the method of the first aspect, except that a first wax having a number average molecular weight of 1500 to 4000 is used in the method of the second aspect in place of the first wax having a first viscosity, which is used in the method of the first aspect, and that a second wax having a number average molecular weight of 8000 to 11000 is used in the method of the second aspect in place of the second wax having a second viscosity, which is used in the method of the first aspect.
  • the method of the second aspect is also substantially equal in function and produced effect to the method of the first aspect.
  • the second aspect of the present invention is directed to a method of manufacturing a developing agent, comprising:
  • the first wax having a number average molecular weight of 1500 to 4000 is added in the first step of preparing the wax-added binder resin.
  • the second wax having a number average molecular weight of 8000 to 11000 is added in the second step of melting and kneading a mixture containing the binder resin prepared in the first step.
  • the particular technique permits improving the dispersion capability of the waxes in the toner particles.
  • a developing agent prepared by using these toner particles is excellent in off-set resistance, shelf life, fluidity and fixing properties.
  • the number average molecular weight of the second wax is less than 8000, a smear resistance tends to be impaired. If the number average molecular weight of the second wax exceeds 11000, however, the wax fails to be dispersed sufficiently in the toner, giving rise to a filming problem.
  • the method according to the second aspect of the present invention is defined in terms of the number average molecular weights of the first and second waxes.
  • the limitation in terms of the number average molecular weight of the wax can be employed as a preferred embodiment of the invention relating to the first aspect of the present invention.
  • the particular combination is expected to produce more excellent effects.
  • the present invention according to third aspect provides a method of manufacturing a developing agent, comprising:
  • a fifth preferred embodiment of the present invention is directed to a method of manufacturing a developing agent, comprising:
  • a sixth preferred embodiment of the present invention is directed to a method of manufacturing a developing agent, comprising:
  • An seventh preferred embodiment of the present invention is directed to a method of manufacturing a developing agent, comprising:
  • the first wax in an amount of 1 to 7 parts by weight relative to 100 parts by weight of the kneaded mass prepared in the second step.
  • the second wax in an amount of 0.1 to 3 parts by weight relative to 100 parts by weight of the kneaded mass prepared in the second step. It is desirable for the sum of the first and second waxes used in the manufacture of the developing agent to be at most 10% by weight. It is also desirable for the ratio by weight of the first wax to the second wax to fall within a range of between 1:3 and 70:1.
  • the components of the binder resin prepared in the first step included in the method of manufacturing the developing agent of the present invention can include, for example, a binder resin monomer, a solvent, a polymerization initiator, and a molecular weight controlling agent.
  • the resins used as a binder in the developing agent of the present invention include, for example, styrene-based copolymers such as polystyrene, styrene-butadiene copolymer, and styrene-acrylonitrile copolymer; ethylene-based copolymers such as polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer; so-called petroleum resins such as phenolic resins, polyamide resins, polyester resins, maleic acid-based resins, polymethyl methacrylate, polyacrylic acid, polyvinyl butyral, aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, and aromatic hydrocarbon resins; chlorinated paraffins; and mixtures thereof.
  • styrene-based copolymers such as polystyrene, styrene-butadiene copolymer, and styrene-acrylonitrile
  • coloring agents in the developing agent of the present invention including, for example, carbon black, fast yellow G, benzidine yellow, pigment yellow, indofast orange, irugagine red, carmine FB, permanent bordeaux FRR, pigment orange R, lithole red 2G, chelate red C, rhodamine FB, rhodamine B chelate, phthalocyanine blue, pigment blue, brilliant green B, phthalocyanine green, and quinacridone.
  • coloring agents including, for example, carbon black, fast yellow G, benzidine yellow, pigment yellow, indofast orange, irugagine red, carmine FB, permanent bordeaux FRR, pigment orange R, lithole red 2G, chelate red C, rhodamine FB, rhodamine B chelate, phthalocyanine blue, pigment blue, brilliant green B, phthalocyanine green, and quinacridone.
  • an antistatic agent such as a metal dye, a ligrocine based antistatic agent and a polyamine based antistatic agent to the developing agent of the present invention.
  • antistatic agents can be used in the form of a mixture with, for example, a nuclear toner and/or a surface treating agent.
  • hydrophobic colloidal particles having a polarity equal to that of colored particles such as colloidal silica particles.
  • materials other than the colloidal silica particles can also be added to the developing agent of the present invention.
  • materials such as inorganic oxides such as aluminum oxide, titanium oxide, silicon oxide, zinc oxide, magnesium oxide, calcium oxide, tin oxide, silicon, indium oxide, cerium oxide, and molybdenum trioxide; and inorganic oxide particles having the surfaces treated with coupling agents such as a silane coupling agent, titanium coupling agent, and a silicone oil.
  • fine powders of resins such as styrene-based copolymers including, for example, polystyrene, styrene-butadiene copolymer, and styrene-acrylic acid copolymer; aliphatic copolymers such as polyethylene and ethylene-based copolymer, and polymethyl methacrylate; alicyclic copolymers, silicone resins, and tefrons.
  • fine resin powders having the surfaces treated with a coupling agent, a silicone oil, etc.
  • magnetic powders such as a magnetite powder and a ferrite powder can be added to the developing agent of the present invention.
  • the developing agents according to the fourth and fifth aspects of the present invention include the developing agents manufactured by the methods according to the first and second aspects of the present invention as well as those manufactured by the first to eighth preferred embodiments of the present invention.
  • the present invention according to the fourth aspect provides a developing agent obtained essentially from a kneaded mass prepared by melting and kneading a mixture consisting of a wax-added binder resin prepared by polymerizing a solution containing a polymerizable monomer and a first wax dispersed in the polymerizable monomer and having a first viscosity, a coloring agent, and a second wax having a viscosity higher than that of the first wax.
  • the first and second waxes contained therein are defined in terms of a preferred range of the viscosity of each of these waxes.
  • the preferred first embodiment noted above is directed to a developing agent obtained essentially by melting and kneading a mixture consisting of a wax-added binder resin prepared by polymerizing a solution containing a polymerizable monomer and a first wax dispersed in the polymerizable monomer and having a viscosity ⁇ 1 at 100°C of 100 to 1000 cP, a coloring agent, and a second wax having a viscosity at 100°C of 10000 to 100000.
  • the first and second waxes are defined in terms of ranges of the viscosities.
  • the first and second waxes are defined in terms of the contents thereof in the developing agent.
  • the third preferred embodiment noted above is directed to a developing agent obtained essentially by melting and kneading a mixture consisting of a wax-added binder resin prepared by polymerizing a solution containing a polymerizable monomer and a first wax dispersed in the polymerizable monomer and having a first viscosity, a coloring agent, and a second wax having a second viscosity higher than the first viscosity noted above, wherein the first wax is added in an amount of 1 to 7 parts by weight relative to 100 parts by weight of the kneaded mass, and the second wax is added in an amount of 0.1 to 3 parts by weight relative to 100 parts by weight of the kneaded mass.
  • a preferred fourth embodiment directed to the developing agent of the present invention is intended to provide a developing agent obtained essentially by melting and kneading a mixture consisting of a wax-added binder resin prepared by polymerizing a solution containing a polymerizable monomer and a first wax dispersed in the polymerizable monomer and having a viscosity ⁇ 1 at 100°C of 100 to 1000 cP, a coloring agent, and a second wax having a viscosity at 100°C of 10000 to 100000 cP, wherein the first wax is added in an amount of 1 to 7 parts by weight relative to 100 parts by weight of the kneaded mass, and the second wax is added in an amount of 0.1 to 3 parts by weight relative to 100 parts by weight of the kneaded mass.
  • the present invention according to the fifth aspect is directed to a developing agent obtained essentially by melting and kneading a mixture consisting of a wax-added binder resin prepared by polymerizing a solution containing a polymerizable monomer and a first wax dispersed in the polymerizable monomer, and having a number average molecular weight of 1500 to 4000, a coloring agent, and a second wax having a number average molecular weight of 8000 to 11000.
  • the present invention according to a preferred fifth embodiment directed to the developing agent of the present invention provides a developing agent obtained essentially by melting and kneading a mixture consisting of a wax-added binder resin prepared by polymerizing a solution containing a polymerizable monomer and a first wax dispersed in the polymerizable monomer, having a first viscosity, and also having a number average molecular weight of 1500 to 4000, a coloring agent, and a second wax having a second viscosity higher than the first viscosity noted above, and also having a number average molecular weight of 8000 to 11000.
  • the present invention according to a preferred sixth embodiment directed to the developing agent of the present invention provides a developing agent obtained essentially by melting and kneading a mixture consisting of a wax-added binder resin prepared by polymerizing a solution containing a polymerizable monomer and a first wax dispersed in the polymerizable monomer, having a viscosity at 100°C of 100 to 1000 cP, and also having a number average molecular weight of 1500 to 4000, a coloring agent, and a second wax having a viscosity at 100°C of 10000 to 100000, and also having a number average molecular weight of 8000 to 11000.
  • the present invention according to a preferred seventh embodiment directed to the developing agent of the present invention provides a developing agent obtained essentially by melting and kneading a mixture consisting of a wax-added binder resin prepared by polymerizing a solution containing a polymerizable monomer and a first wax dispersed in the polymerizable monomer and also having a number average molecular weight of 1500 to 4000, a coloring agent, and a second wax having a number average molecular weight of 8000 to 11000, wherein the first wax is added in an amount of 1 to 7 parts by weight relative to 100 parts by weight of the kneaded mass, and the second wax is added in an amount of 0.1 to 3 parts by weight relative to 100 parts by weight of the kneaded mass.
  • the present invention directed to the developing agent of the present invention provides a developing agent obtained essentially by melting and kneading a mixture consisting of a wax-added binder resin prepared by polymerizing a solution containing a polymerizable monomer and a first wax dispersed in the polymerizable monomer, having a number average molecular weight of 1500 to 4000 and also having a viscosity at 100°C of 100 to 1000 cP, a coloring agent, and a second wax having a number average molecular weight of 8000 to 11000 and also having a viscosity at 100°C of 10000 to 100000, wherein the first wax is added in an amount of 1 to 7 parts by weight relative to 100 parts by weight of the kneaded mass, and the second wax is added in an amount of 0.1 to 3 parts by weight relative to 100 parts by weight of the kneaded mass.
  • FIG. 2 schematically shows the construction of an image forming apparatus in which the developing agent of the present invention can be used.
  • the apparatus comprises a photosensitive drum 3, which acts as an image carrier and can be rotated in a direction denoted by an arrow.
  • a charger 5 for uniformly charging the photosensitive drum 3 is arranged to face the drum 3.
  • Arranged above the photosensitive drum 3 are a glass plate 7 for supporting an original, an automatic original feeder (ADF) 8 for feeding the original onto the glass plate 7, and an exposure section 9 for exposing the charged photosensitive drum 3 with light in accordance with the images of the original so as to form electrostatic latent images.
  • ADF automatic original feeder
  • the exposure section 9 comprises a light-exposing lamp 11 which acts as a light source, reflecting mirrors 13a, 13b, 13c, 13d, 13e, and 13f for guiding the light emitted from the lamp 11 onto the photosensitive drum 3, a slit glass 13g, and a lens unit 14 for forming images from the light reflected by the reflecting mirrors 13a to 13f.
  • a developing apparatus 15 housing a toner T and a carrier (not shown) is arranged downstream of the photosensitive drum 3.
  • the electrostatic latent images formed in the exposure section 9 are developed with the toner T in the developer 15.
  • a transfer charger 17 is arranged downstream of the developer 15.
  • the toner images formed in the developer 15 are transferred onto a paper sheet P acting as an image forming medium in the transfer charger 17.
  • the electrostatic charger 5, the exposure section 9 and the developer 15 collectively constitute a means for forming images of the developing agent.
  • a peeling charger 19 for peeling the paper sheet P which has been electrostatically attached to the photosensitive drum 3 in the transfer step is arranged adjacent to the transfer charger 17.
  • a cleaning device 21 for removing the residual toner T on the photosensitive drum 3 after the transfer step is arranged downstream of the peeling charger 19.
  • the cleaning device 21 is provided with a cleaning blade 23.
  • a static eliminator 25 for removing the electric charge of the photosensitive drum 3 is arranged downstream of the cleaning device 19.
  • FIG. 2 shows that a paper feeding cassette 27 housing the paper sheets P is detachably mounted to main body of the image forming apparatus.
  • the cassette 27 is positioned on the right hand side of the photosensitive drum 3.
  • a pick up roller 29 for picking up the paper sheets P one by one is arranged near the paper feeding cassette 27.
  • a pair of paper feeding rollers 31 for feeding the paper sheets P one by one are arranged in the vicinity of the pick up roller 29.
  • a pair of aligning rollers 32 for feeding the paper sheet P toward the photosensitive drum 3 at a predetermined timing are arranged upstream of the transfer charger 17 in the transfer direction of the paper sheet P. It should be noted that the paper sheet P is held between the aligning rollers 32 so as to be fed into a clearance between the photosensitive drum 3 and the transfer charger 17.
  • the transfer belt 33 which is made of an insulating material, electrostatically holds the paper sheet P charged by the transfer charger 17 so as to transfer the charged paper sheet P toward the fixer 35.
  • the fixer 35 comprises a pair of rollers, i.e., a heating roller 37 and a pressing roller 39. These heating roller 37 and the pressing roller 39 are rotated in directions denoted by arrows c and d, respectively, so as to melt and fix the toner images on the paper sheet P.
  • a pair of paper discharge rollers 43 for discharging the paper sheet P after the fixing step to the outside of the image forming apparatus and a paper discharge tray 45 for receiving the paper sheet P discharged from within the image forming apparatus.
  • the ADF 8 comprises an original table 47 on which the original is placed, and a pick up roller 49 for taking up the original placed on the original table 47.
  • the original is placed on the original table 47 such that the images formed on the original are allowed to face upward.
  • a separating belt 51 and a paper feeding roller 53 are arranged to face each other in the vicinity of the pick up roller 49 so as to permit the originals to be separated and fed one by one onto the glass plate 7 for supporting the original.
  • an aligning roller 55 is arranged on the glass plate 7 such that the roller 55 is positioned in the vicinity of the separating belt 51 and the paper feeding roller 53.
  • An original transfer belt 57 for transferring the original along the upper surface of the glass plate 7 is arranged to run along the original-supporting glass plate 7. Further, arranged downstream of the original transfer belt 57 in the transfer direction of the original are an inverting roller 59 for turning the original upside down and a discharge roller 61 for discharging the original to the outside of the ADF 8.
  • the image forming apparatus of the construction described above is operated as follows.
  • an instruction to start the image forming operation is given to the apparatus via an operating panel (not shown).
  • the photosensitive drum 3 begins to rotate in the direction denoted by the arrow a so as to cause the static charger 5 to charge uniformly the surface of the photosensitive drum 3.
  • the ADF 8 permits the original to be fed one by one onto the glass plate 7 for supporting the original.
  • the original supported by the glass plate 7 is irradiated with light emitted from the exposing lamp 11, with the result that an electrostatic latent image is formed by the light exposing section 9 on the charged surface of the photosensitive drum 3 in accordance with the picture image formed on the original.
  • the charged toner T is attached to the electrostatic latent image so as to form a toner image.
  • the paper sheets P are taken up one by one from the paper feeding cassette 27 in accordance with rotation of the pick up roller 29 and the paired paper feeding rollers 31 and, then, fed into the clearance between the photosensitive drum 3 and the transfer charger 17 by the paired aligning rollers 32.
  • the transfer charger 17 serves to impart an electric charge of a polarity opposite to that of the charged toner T to the back surface of the paper sheet P so as to permit the toner image to be transferred onto the paper sheet P.
  • the peeling charger 19 performs an AC corona discharge so as to peel the paper sheet P, which has been electrostatically attached to the photosensitive drum 3 in the transfer step of the toner image, from the photosensitive drum 3. Further, the paper sheet P peeled from the drum 3 is transferred by the transfer belt 33 toward the fixer 35.
  • the toner image formed on the paper sheet P is melted by the heating within the fixer 35, with the result that the toner image is fixed to the paper sheet P. Then, the paper sheet P is discharged onto the discharge tray 45 in accordance with rotation of the paired paper discharge rollers 43.
  • the toner T remaining on the photosensitive drum 3 after the toner image transfer step is removed by the cleaning device 21, followed by removing the charge on the surface of the photosensitive drum 3 by the operation of the static eliminator 25 so as to finish one cycle of the image forming process.
  • the photosensitive drum 3 is charged again by the electrostatic charger 5 when starting the next image forming process.
  • the original is transferred by the original transfer belt 57 so as to be discharged out of the ADF 8.
  • a binder resin mixture having a first wax of a low viscosity included therein was prepared as follows.
  • predetermined amounts of xylene as a solvent and polypropylene wax were put in a reaction vessel, followed by putting styrene, n-butyl acrylate and di-t-butyl peroxide in the reaction vessel and subsequently substituting a nitrogen gas for the air atmosphere within the reaction vessel.
  • the reaction system was heated to a boiling point of xylene (135 to 145°C).
  • a toner was prepared as follows by using a styrene-acrylate copolymer resin having the polypropylene was of a low viscosity added thereto. Specifically, a toner material mixture was prepared by adding 5 parts by weight of carbon black, 2 parts by weight of a metal complex salt of a monoazo dye, 0. 1 part by weight of hydrophobic silica, and a polyethylene-based wax of a high viscosity to 100 parts by weight of the styrene-acrylate copolymer resin having the polypropylene-based wax of a low viscosity added thereto in the polymerizing step.
  • Table 1 shows the toner material mixtures for Examples 1 to 9 obtained by changing the amounts of the polyethylene-based high viscosity wax and the polypropylene-based low viscosity wax and also changing the mixing ratio of these waxes. Of course, the viscosities of these waxes fall within the scopes defined in the present invention.
  • Table 2 shows the toner material mixtures for Comparative Examples 1 to 3, in which the polyethylene-based high viscosity wax and the polypropylene-based low viscosity wax were mixed in amounts and mixing ratio failing to fall within the scopes defined in the present invention.
  • Each of the toner material mixtures shown in Tables 1 and 2 was kneaded at about 170°C for 30 minutes in a pressure kneader, followed by pulverizing the kneaded mass to obtain a powdery material. Further, the powdery material was finely pulverized by an I-type jet mill (DS classifier), followed by an air classification so as to obtain a toner having a 50% volume average particle diameter of 11.0 ⁇ m.
  • DS classifier I-type jet mill
  • a half tone picture image (ID 0.6 to 0.8) was fixed at a fixing temperature of 200°C under a low temperature (10°C) and a low humidity (20%).
  • the fixed image was subjected to a rubbing test with a friction fastness tester, and the image densities before and after the rubbing test were measured so as to evaluate the fix retention rate.
  • the fixing temperature was 200°C.
  • toner Twenty grams of the toner was put in a polyvinyl chloride bottle having an inner volume of 100 ml and left to stand in a water bath of 55°C for 8 hours, followed by evaluating the fluidity of the toner by using a powder tester manufactured by Hosokawa Micron Ltd., Japan. In this test, the toner put on a sieve of 200 meshes was kept vibrated for 10 seconds.
  • test result was evaluated in terms of the amount of the toner left on the sieve after the vibration of the sieve such that "o” denotes 5g or less, “ ⁇ ” denotes 5.1g to 10g, and "x” denotes 10.1g or more.
  • the toner according to any of Examples 1 to 9 of the present invention was found to be satisfactory in any of the dispersion capability, fix retention rate, smear characteristics, off-set resistance and shelf life.
  • the toner contained only one kind of wax i.e., polypropylene wax having a low viscosity
  • the toner contained only the polyethylene wax having a high viscosity
  • the resultant toner was found to be poor in the off-set resistance, even if the wax was added in the step of melting and kneading the binder resin, as apparent from Comparative Example 2.
  • two kinds of waxes differing from each other in viscosity were used in Comparative Example 3.
  • the polyethylene wax having a high viscosity was added in the step of preparing the wax-added binder resin, with the polypropylene wax having a low viscosity added in the step of melting and kneading the wax-added binder resin.
  • the toner in Comparative Example 3 was found to be poor in, particularly, the dispersion capability and the shelf life.
  • a toner material mixture was prepared by adding 5 parts by weight of carbon black, 2 parts by weight of a metal complex salt of monoazo dye, 0.1 part by weight of hydrophobic silica, and 1 part by weight of a polyethylene-based high viscosity wax having a viscosity of 10000 cP at 100°C, to 100 parts by weight of a styrene-acrylate copolymer resin containing 3 parts by weight of a polypropylene-based low viscosity wax having a viscosity of 100 cP at 100°C which had been added in the step of polymerization for preparing the copolymer resin.
  • the toner material mixtures for Examples 10 to 17 were prepared by changing in a various fashion the number average molecular weight of the polyethylene-based high viscosity wax and the number average molecular weight of the polypropylene-based low viscosity wax.
  • Toner was prepared as in Examples 1 to 9 by using the toner material mixtures thus prepared.
  • Various properties of the resultant toner were tested and evaluated, with the results as shown in Table 3.
  • Table 3 Examples Mn 1 /Mn 2 Dispersibility Fix Retention Rate Smear Characteristics Off-set Resistance Shelf Life Over-all Evaluation 10 1500/8000 ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ 11 1500/11000 ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ 12 4000/8000 ⁇ ⁇ ⁇ ⁇ ⁇ 13 4000/11000 ⁇ ⁇ ⁇ ⁇ ⁇ 14 1000/8000 ⁇ ⁇ ⁇ ⁇ 15 5000/8000 ⁇ ⁇ ⁇ ⁇ 16 3000/7000 ⁇ ⁇ ⁇ ⁇ ⁇ 17 3000/12000 ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ Notes Mn 1 : Number average molecular weight of polypropylene-based low viscosity wax.
  • Mn 2 Number average molecular weight of polyethlene-based
  • the toner material mixture in any of Examples 10 to 13 contains a polypropylene-based low viscosity wax, which is added in the first step of preparing the wax-added binder resin and has a number average molecular weight falling within the range of between 1500 and 4000 specified in the present invention.
  • the toner material mixture also contains a polyethylene-based high viscosity wax, which is added in the second step of melting and kneading the binder resin prepared in the first step and has a number average molecular weight falling within the range of between 8000 and 11000 specified in the present invention.
  • the toner obtained in any of Examples 10 to 13 was found to be satisfactory in any of the dispersion capability, fix retention rate, smear characteristics and shelf life.
  • at least one of the polypropylene-based low viscosity wax, which is added in the first step specified in the present invention, and the polyethylene-based high viscosity was, which is added in the second step specified in the present invention failed to meet the preferred range of the number average molecular weight specified in the present invention in any of the toner material mixture used in Examples 14 to 17.
  • the resultant toner was found to be somewhat inferior to the toner obtained in each of Examples 10 to 13 in any of the dispersion capability, fix retention rate, smear characteristics, off-set resistance and shelf life.
  • the off-set phenomenon causes the toner remaining on the heat roller to be transferred onto the press roller so as to stain the back surface of the recording paper sheet and the cleaning members of the fixer.
  • the toner obtained in each of the Examples 1 to 17 and Comparative Examples 1 to 3 was tested to see these stains.
  • the toner for each of Examples 1 to 17 was found to be satisfactory.
  • the toner for Comparative Example 1 was also found to be satisfactory.
  • the toner for each of Comparative Examples 2 and 3 was also found to be unsatisfactory.
  • the low viscosity wax is defined to have a viscosity at 100°C of 100 to 1000 cP.
  • the high viscosity wax is defined to have a viscosity at 100°C of 10000 to 100000 cP.
  • the viscosity of the wax is changed with temperature.
  • the present inventors have used various waxes as a wax having a low viscosity and a wax having a high viscosity in an attempt to find waxes most suitable for use in the present invention. It has been found that, as far as equation (1) or (2) given above is satisfied, the wax exhibits a suitable viscosity under the temperature at which the toner is used. Naturally, the toner containing the waxes meeting the equations (1) and (2) respectively exhibits excellent smear characteristics and fix retention rate.
  • FIG. 3 shows experimental data on the relationship between the viscosity and temperature in respect of some waxes which can be used as the first wax in the present invention.
  • FIG. 4 shows experimental data on the relationship between the viscosity and temperature in respect of some waxes which can be used as the second wax in the present invention.
  • Table 4 shows the data on some points marked in each of FIGS. 3 and 4. It should be noted that graphs 101 to 104 shown in FIG. 3 represent the temperature characteristics of low viscosity waxes A to D shown in Table 4. On the other hand, graphs 105 shown in FIG. 4 represent the temperature characteristics of high viscosity waxes E to G shown in Table 4.
  • Wax Temperature (°C) Viscosity (cp) Low Viscosity Wax Wax A 100 1000 200 22 Wax B 100 950 200 900 Wax C 140 750 180 620 Wax D 100 200 140 70 180 80 200 50 High Viscosity Wax; Wax E 100 100000 200 5000 Wax F 140 90000 180 95000 200 90000 Wax G 100 10000 140 8000 180 8500 200 5000

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Developing Agents For Electrophotography (AREA)
EP97107882A 1996-05-14 1997-05-14 Agent de développement et son procédé de fabrication Withdrawn EP0807858A1 (fr)

Applications Claiming Priority (2)

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JP11925696A JPH09304966A (ja) 1996-05-14 1996-05-14 現像剤及びその製造方法
JP119256/96 1996-05-14

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0950927A2 (fr) * 1998-04-14 1999-10-20 Canon Kabushiki Kaisha Révélateur d' images électrostatiques et procédé de production d' images
US6509129B2 (en) 2000-09-18 2003-01-21 Kao Corporation Toner for electrophotography

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4365567B2 (ja) 2002-01-11 2009-11-18 株式会社リコー 静電荷像現像用トナー及び画像作製方法
JP2004287394A (ja) 2003-03-03 2004-10-14 Hitachi Printing Solutions Ltd 静電荷像現像用トナーおよびそれを用いた現像剤、画像形成装置、画像形成方法
US7306889B2 (en) * 2004-02-20 2007-12-11 Canon Kabushiki Kaisha Process for producing toner, and toner
JP5526822B2 (ja) * 2010-02-01 2014-06-18 富士ゼロックス株式会社 静電潜像現像用トナー、静電潜像現像剤、トナーカートリッジ、プロセスカートリッジ及び画像形成装置
CN104714378B (zh) * 2015-04-02 2019-09-13 湖北鼎龙控股股份有限公司 静电图像显影剂用载体芯材及其制备方法、以及载体
KR102403541B1 (ko) * 2022-01-28 2022-05-31 주식회사 프리즘머트리얼스 고속프린터용 중합 토너 및 그 제조방법

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JPS5756851A (en) * 1980-09-24 1982-04-05 Canon Inc Toner for development
JPS5825642A (ja) * 1981-08-07 1983-02-15 Canon Inc 圧力定着性現像用トナー
JPH04358159A (ja) * 1991-06-04 1992-12-11 Toshiba Corp 電子写真用現像剤
US5344737A (en) * 1993-02-25 1994-09-06 Xerox Corporation Polywax toner compositions and processes
EP0703505A1 (fr) * 1994-08-31 1996-03-27 Mita Industrial Co., Ltd. Révélateur pour agent de développement à deux composants
JPH08106173A (ja) * 1994-10-06 1996-04-23 Toshiba Corp 現像剤

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JPS5756851A (en) * 1980-09-24 1982-04-05 Canon Inc Toner for development
JPS5825642A (ja) * 1981-08-07 1983-02-15 Canon Inc 圧力定着性現像用トナー
JPH04358159A (ja) * 1991-06-04 1992-12-11 Toshiba Corp 電子写真用現像剤
US5292609A (en) * 1991-06-04 1994-03-08 Kabushiki Kaisha Toshiba Electrophotographic developer having different polyolefin waxes
US5344737A (en) * 1993-02-25 1994-09-06 Xerox Corporation Polywax toner compositions and processes
EP0703505A1 (fr) * 1994-08-31 1996-03-27 Mita Industrial Co., Ltd. Révélateur pour agent de développement à deux composants
JPH08106173A (ja) * 1994-10-06 1996-04-23 Toshiba Corp 現像剤

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PATENT ABSTRACTS OF JAPAN vol. 006, no. 133 (P - 129) 20 July 1982 (1982-07-20) *
PATENT ABSTRACTS OF JAPAN vol. 007, no. 101 (P - 194) 28 April 1983 (1983-04-28) *
PATENT ABSTRACTS OF JAPAN vol. 017, no. 228 (P - 1531) 11 May 1993 (1993-05-11) *
PATENT ABSTRACTS OF JAPAN vol. 096, no. 008 30 August 1996 (1996-08-30) *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0950927A2 (fr) * 1998-04-14 1999-10-20 Canon Kabushiki Kaisha Révélateur d' images électrostatiques et procédé de production d' images
EP0950927A3 (fr) * 1998-04-14 2000-02-23 Canon Kabushiki Kaisha Révélateur d' images électrostatiques et procédé de production d' images
US6509129B2 (en) 2000-09-18 2003-01-21 Kao Corporation Toner for electrophotography

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CN1170150A (zh) 1998-01-14

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