EP0744668A2 - Toner für magnetische Zweikomponentenentwickler - Google Patents

Toner für magnetische Zweikomponentenentwickler Download PDF

Info

Publication number
EP0744668A2
EP0744668A2 EP96303651A EP96303651A EP0744668A2 EP 0744668 A2 EP0744668 A2 EP 0744668A2 EP 96303651 A EP96303651 A EP 96303651A EP 96303651 A EP96303651 A EP 96303651A EP 0744668 A2 EP0744668 A2 EP 0744668A2
Authority
EP
European Patent Office
Prior art keywords
toner
weight
resin
parts
amount
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Withdrawn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
EP96303651A
Other languages
English (en)
French (fr)
Other versions
EP0744668A3 (de
Inventor
Masatomi c/o Mita Ind. Co. Ltd. Funato
Hideaki c/o Mita Ind. Co. Ltd. Kawata
Seijiro c/o Mita Ind. Co. Ltd. Ishimaru
Norio c/o Mita Ind. Co. Ltd. Kubo
Yoshiteru c/o Mita Ind. Co. Ltd. Hatase
Tadao c/o Mita Ind. Co. Ltd. Sumiyoshi
Terumichi c/o Mita Ind. Co. Ltd. Asano
Yoshitake c/o Mita Ind. Co. Ltd. Shimizu
Kazuya c/o Mita Ind. Co. Ltd. Nagao
Tomohide c/o Mita Ind. Co. Ltd. Iida
Hidekazu c/o Mita Ind. Co. Ltd. Tamura
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.)
Kyocera Mita Industrial Co Ltd
Original Assignee
Mita Industrial Co Ltd
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
Priority claimed from JP7123743A external-priority patent/JPH08314194A/ja
Priority claimed from JP7128699A external-priority patent/JPH08328301A/ja
Priority claimed from JP7128082A external-priority patent/JPH08320595A/ja
Priority claimed from JP7128084A external-priority patent/JPH08320592A/ja
Priority claimed from JP7128083A external-priority patent/JPH08320596A/ja
Application filed by Mita Industrial Co Ltd filed Critical Mita Industrial Co Ltd
Publication of EP0744668A2 publication Critical patent/EP0744668A2/de
Publication of EP0744668A3 publication Critical patent/EP0744668A3/de
Withdrawn legal-status Critical Current

Links

Images

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
    • G03G9/083—Magnetic toner particles
    • 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
    • G03G9/08786—Graft polymers
    • 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
    • G03G9/08791—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775 characterised by the presence of specified groups or side chains
    • 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
    • G03G9/0904—Carbon black

Definitions

  • the present invention relates to a toner for a two-component magnetic developing agent having excellent resistance against being spent. More specifically, the invention relates to a toner for a two-component magnetic developing agent without containing charge control agent that has a property to migrate onto the carrier surfaces.
  • a so-called two-component magnetic developing agent has been widely used for developing static charge image formed on an electrophotosensitive material.
  • the two-component magnetic developing agent is constituted by a mixture of a magnetic carrier comprising iron powder, ferrite particles, etc. and an electroscopic toner comprising a colored resin composition.
  • the magnetic carrier and the toner are mixed together so that the toner particles are electrically charged to a predetermined polarity.
  • the mixture is conveyed in the form of a magnetic brush up to the photosensitive material, the surface of the photosensitive material is rubbed with the magnetic brush, and the charged toner is adsorbed and held by the charge image on the surface of the photosensitive material so as to form a visible image.
  • a charge control agent is contained in the toner particles so that the toner particles will be frictionally charged to a predetermined polarity.
  • a negatively charging toner uses a negative charge control agent such as a metal-containing complex salt dye or a metal complex of oxycarboxylic acid (e.g., Japanese Laid-Open Patent Publication No. 67268/1991), and a positively charging toner uses a positively charging control agent such as an oil-soluble dye, for example, Nigrosine or an amine-type control agent (e.g., Japanese Laid-Open Patent Publication No. 106249/1981).
  • a magnetic toner has long been used as a toner for the two-component magnetic developing agent.
  • Japanese Laid-Open Patent Publication No. 106249/1981 and Japanese Laid-Open Patent Publication No. 162563/1984 disclose toners to which a magnetic power is internally added, i.e., disclose toners containing a magnetic powder
  • Japanese Laid-Open Patent Publication No. 67268/1991 discloses a toner to which a magnetic powder is externally added, i.e., discloses a toner to which is added and mixed a silica powder and a magnetic powder.
  • the two-component magnetic developing agent exhibits satisfactory charging property in its early stage of use upon mixing the magnetic carrier and the toner together, but loses its charging property due to the occurrence of a so-called spent toner causing its life to be shortened.
  • the spent toner is a phenomenon in which the toner component adheres like a film onto the surfaces of the magnetic carrier. That is, the surfaces of the magnetic carrier become close to those of the toner, and the frictional series of the two become close to each other, so that predetermined charging property is no longer maintained.
  • the magnetic carrier must be discarded and must be replaced by the new magnetic carrier.
  • the object of the present invention therefore is to provide a heat-fixing toner for a two-component magnetic developing agent having excellent resistance against being spent and featuring extended life of toner and carrier.
  • Another object of the present invention is to provide a heat-fixing toner for a two-component magnetic developing agent without containing charge control agent (CCA) that has a property to migrate onto the carrier surfaces, the toner without scattering at the time of developing and being capable of increasing apparent developing sensitivity.
  • CCA charge control agent
  • a further object of the present invention is to provide a heat-fixing toner for a two-component magnetic developing agent, which enables the image to be efficiently transferred onto the paper from the surface of the photosensitive material though it does not contain the charge control agent having migrating property.
  • a negatively charging toner for a two-component magnetic developing agent obtained by dispersing carbon black in a fixing resin medium
  • said fixing resin medium is a copolymerized resin or a resin composition having a free or neutralized anionic polar group and has an acid value of from 4 to 30 by measuring said anionic polar group in the form of a free acid
  • said carbon black has a pH of smaller than 7 and a ratio (7-pH)/specific surface area (m 2 /g) of from 0.010 to 0.050, and is blended in an amount of from 4 to 15% by weight per said resin fixing medium.
  • a two-component magnetic developing agent comprising the above-mentioned toner and a magnetic carrier coated with a resin or a magnetic carrier obtained by dispersing a magnetic powder in a resin.
  • the present inventors have forwarded the study in an effort to prevent the occurrence of spent toner and have found an interesting fact.
  • Fig. 1 is a graph showing a curve of absorbancy at wavelengths of from 200 to 700 nm of an extract obtained by extracting with methanol a toner that contains a chromium complex salt dye (2:1 type) as a charge control agent among toners for the conventional two-component magnetic developing agent used for developing positively charged image, the peaks lying over a region of wavelengths of from 400 to 700 nm.
  • Fig. 2 is a graph showing a curve of absorbancy at wavelengths of from 200 to 700 nm of an extract obtained by extracting with methanol a toner that contains a metal salicylate complex as a charge control agent, the peaks lying over a region of wavelengths of from 280 to 350 nm.
  • the two extracts exhibit characteristic absorption peaks due to the charge control agents. This means that the charge control agent is contained at a considerably high concentration in the surfaces of the toner particles.
  • Fig. 3 is a graph showing a curve of absorbancy at wavelengths of from 200 to 700 nm of an extract obtained by extracting with methanol a carrier which is poorly charged due to the occurrence of spent toner.
  • the carrier is contained in a two-component magnetic developing agent containing the toner used in the measurement of Fig. 1. In the curve, the peaks lying over a region of wavelengths of from 400 to 700 nm.
  • Figs. 4 and 5 are graphs plotting relationships between the mixing time and the spent amount, and relationships between the mixing time and the amount of charge of when there are used a mixture of a toner containing a positive or negative charge control agent and a magnetic carrier, and a mixture of a toner without containing charge control agent and the magnetic carrier. From these results, the fact becomes obvious in that when the charge control agent is contained, the spent amount increases with an increase in the mixing time, and the amount of charge decreases to a large extent.
  • Fig. 6 is a graph illustrating relationships between the spent amount of the carrier to which the spent toner is adhered and the charge control agent in the spent toner, wherein a dotted line is drawn by plotting estimated values calculated from the toner recipe.
  • Fig. 7 illustrates relationships between the mixing time and the spent amount of when each of the components in the toner and the magnetic carrier are mixed together.
  • the conventional two-component magnetic developing agent becomes poorly charged due to the occurrence of spent toner as explained in Fig. 8. That is, in an early stage of use of the mixture, the carrier has been positively charged and the toner has been negatively charged. As the charge control agent selectively migrates onto the carrier surface to form spent toner, however, the spent layer is negatively charged and whereby a toner of a reverse polarity (positively charged) is formed.
  • the present invention there is used no charge control agent having property to migrate onto the toner particles, and, hence, no charge control agent migrates onto the surfaces of the magnetic carrier.
  • the absorbancy is substantially zero over wavelengths of from 400 to 700 nm.
  • the toner of the present invention is not, as a matter of course, blended with a positive charge control agent such as metal salicylate complex, and its extract with methanol exhibits no peak of absorbancy over the wavelengths of from 280 to 350 nm.
  • the absorbancy which is substantially zero stands for that no absorption peak is quite detected in the above-mentioned wavelength region from an extract obtained by extracting 0.1 g of toner with 50 ml of methanol or the absorbancy at the peak is not larger than 0.05 if it is detected.
  • the toner without containing charge control agent is electrically charged in an amount which is inevitably smaller than that of the toner containing the charge control agent.
  • a copolymerized resin composition having anionic polar group as a fixing resin medium
  • carbon black having a pH on the acidic side as a coloring agent.
  • the anionic polar group possessed by the fixing resin medium gives a negatively charging property to the toner and exists in the molecular skeleton of the resin. Therefore, the anionic polar group does not migrate onto the carrier surfaces and does not become a cause of spent toner unlike the charge control agent.
  • the fixing resin medium used in the present invention has an acid value in connection with the possession of an anionic polar group.
  • the acid value must lie within a range of from 4 to 30.
  • the amount of anionic groups increases whereby the toner exhibits increased hygroscopic property making it difficult to frictionally charge the toner maintaining stability.
  • the acid value becomes smaller than 4 on the other hand, the amount of anionic groups is so small that it becomes difficult to maintain the electric charge of the toner in an amount large enough for the developing.
  • the anionic polar group may exist in a free form (in the form of a free acid) or may exist in the form of a metal salt such as sodium salt or the like salt, i.e., may exist in a neutralized form.
  • the acid value is measured in the form of a free acid. That is, in the present invention, if the anionic polar groups at least partly exist in the neutralized form, the acid value stands for a value that is found by hydrolyzing the groups to form free acids.
  • carbon black which is a coloring agent must have a pH which lies on the acidic side (i.e., smaller than 7) and a ratio (7-pH)/specific surface area (m 2 /g) that lies within a range of from 0.010 to 0.050.
  • the carbon black has a pH of about 8 which is on the neutral to alkaline side.
  • the present invention selectively uses the carbon black having a pH of smaller than 7 which, however, does not mean that the invention uses the carbon black of which the electrically conducting property is controlled.
  • the present inventors have confirmed through their study that the carbon black is negatively charged when the carbon black and the magnetic carrier are mixed together and are stirred. That is, according to the present invention which uses the acid-treated carbon black having a pH of smaller than 7, the fixing resin medium having the anionic polar group exhibits reinforced negatively charging property, and the drop of the charging property is effectively prevented despite the negative charge control agent is not blended.
  • the ratio (7-pH)/specific surface area is an index representing the degree of treatment with acid, i.e., representing the density of acidic functional groups existing on the surfaces of the carbon black.
  • this value is smaller than the aforementioned range, the negatively charging property is not reinforced to a sufficient degree and the charging property inevitably drops.
  • this value is larger than the aforementioned range, on the other hand, the toner exhibits increased hygroscopic property and it becomes difficult to stably maintain the amount of charge by friction.
  • the pH of carbon black is measured in the following way. Five grams of a sample is put into 100 ml of ion-exchanged water and is boiled for 5 minutes. After left to cool, water is replenished by an amount that has vaporized and is filtered using a paper. Then, the filtrate is measured by using a commercially available glass-electrode pH measuring instrument.
  • the fixing resin medium used in the present invention is a copolymerized resin having an anionic polar group.
  • the anionic polar group may be any polar group such as of carboxylic acid, sulfonic acid or phosphonic acid. Among them, however, the anionic polar group of carboxylic acid is particularly preferred.
  • the copolymerized resin having such an anionic polar group is obtained by incorporating a monomer having a polar group into a resin relying upon random copolymerization, block-copolymerization or graft-copolymerization. Preferred examples of the monomer are as described below. In the following description, a lower alkyl group stands for the one having not more than 5 carbon atoms, and a higher alkyl group stands for the one having not less than 12 carbon atoms.
  • carboxylic acid type examples include ethylenically unsaturated carboxylic acid, such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, lower alkyl half ester of maleic acid, lower alkyl half ester of fumaric acid and the like.
  • carboxylic acid such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, lower alkyl half ester of maleic acid, lower alkyl half ester of fumaric acid and the like.
  • Examples of those of the sulfonic acid type include styrenesulfonic acid, 2-acrylamide-2-methylprop anesulfonic acid and the like.
  • Examples those of the phosphonic acid type include 2-acid phosphoxypropyl methacrylate, 2-acid phosphoxyethyl methacrylate, 3-chloro-2-acid phosphoxypropyl methacrylate and the like.
  • anionic polar group-containing monomer units may be incorporated in the form of free acids or in the form neutralized with an alkali metal such as sodium or potassium, an alkaline earth metal such as calcium or magnesium, or zinc.
  • Another monomer which is a chief component of the copolymerized resin composition exhibits fixing property and charging property required for the toner when it is polymerized, and may be one or two or more kinds of monomers having an ethylenically unsaturated bond.
  • Preferred examples of the monomer include acrylic ester type monomer, aromatic monovinyl monomer, vinyl ester type monomer, vinyl ether type monomer, diolefin type monomer and monoolefin type monomer. Described below are concrete examples.
  • Preferred examples include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ⁇ -hydroxyethyl acrylate, ⁇ -hydroxypropyl acrylate, ⁇ -hydroxybutyl acrylate, ⁇ -hydroxyethyl methacrylate, lauryl acrylate, tridecyl acrylate, stearyl acrylate, docosyl acrylate, dicyclohexylmethyl acrylate, dicyclohexylpropyl acrylate, cyclododecyl acrylate, cycloundecanemethyl acrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, docosyl methacrylate, di
  • Preferred examples include styrene, ⁇ -methylstyrene, vinyltoluene, ⁇ -chlorostyrene, o-, m- or p-chlorostyrene, p-ethylstyrene, m- or p-laurylstyrene, m- or p-stearylstyrene, ⁇ -methyl-3-stearylstyrene, m- or p-stearoxystyrene, 4-vinylstearyl benzoate and 4-stearoylaminostyrene.
  • the anionic polar groups exist in such an amount that the acid value is from 4 to 30 and, particularly, from 5 to 15.
  • the anionic polar groups of the copolymerized resin are partly or wholly neutralized, the anionic polar groups inclusive of the neutralized polar groups are contained in an amount that corresponds to the above-mentioned acid value.
  • the acid value of the copolymerized resin is smaller than the above-mentioned range, charging property of the toner becomes unsatisfactory.
  • the acid value of the copolymerized resin is greater than the above-mentioned range, on the other hand, the toner becomes susceptible to humidity, and charging property of the toner becomes insufficient, too.
  • a preferred copolymerized resin contains a monomer having anionic polar groups and one or two or more kinds of acrylic monomers of the formula (1) and, further, contains monomers of the formulas (2) to (6) and, particularly, the styrene monomer of the formula (2).
  • the copolymerized resin containing anionic polar group can be used as a fixing resin medium in a single kind as described above and can be further used as a composition containing two or more kinds of anionic polar group-containing copolymerized resins or as a composition containing an anionic polar group-containing copolymerized resin and a copolymerized resin without having anionic polar group. Even in this case, the content of the anionic polar groups in the whole resin composition should be such that the acid value lies within the range specified above for the copolymerized resin.
  • the fixing resin medium has a weight average molecular weight over a range of from 70,000 to 200,000 to maintain a property of being pulverized and a granulating property.
  • the fixing resin medium contains low molecular components having peak molecular weights over a range of from 4,000 to 30,000 and high molecular components having a molecular weight distribution in a high molecular weight region. The low molecular components help increase toner transfer efficiency and heat-fixing property, and high molecular components help improve resistance against the offset.
  • the low molecular components in the resin medium tend to selectively adhere onto the carrier surfaces to form a spent toner. That is, even when the charge control agent is not used, it was found through experiment that the occurrence of spent toner is not perfectly prevented; i.e., the spent toner is formed by the low molecular components as the developing is executed for extended periods of time though the amount of the spent toner is small.
  • the anionic polar groups exist in the low molecular components adhered onto the carrier surfaces, however, the carrier itself tends to be negatively charged giving rise to the formation of a toner charged to an opposite polarity. When the developing is repeated for extended periods of time, therefore, the scattering of toner and fogging become no longer negligible due to the toner charged to the opposite polarity.
  • the acid value of the low molecular components in the fixing resin medium is set to be lower than the acid value of the whole resin medium, i.e., set to lie within a range of from 3 to 15.
  • the acid value of the low molecular components is larger than the above-mentioned range, the amount of the anionic polar groups in the spent toner becomes so large that it becomes difficult to effectively prevent the occurrence of the toner charged to the opposite polarity.
  • the acid value of the low molecular components is within a range of from 10 to 95% with respect to the acid value of the whole fixing resin medium. It is further desired that the low molecular components are contained in an amount of from 40 to 75% by weight per the fixing resin medium.
  • the fixing resin medium can be easily produced by using monomer components mentioned earlier and by radical polymerizing with a widely known polymerization initiator.
  • the fixing resin medium containing low molecular components and high molecular components is obtained by preparing, in advance, the low molecular components having a predetermined low acid value and blending them with high molecular components having a high acid value that are separately prepared, or by preparing the high molecular components by effecting the radical polymerization in the presence of the low molecular components. From the standpoint of compatibility between the high molecular components and the low molecular components, in general, it is desired that the high molecular components are prepared in the presence of low molecular components.
  • Monomers for low molecular components and the polymerization initiator are mixed together and stirred in an organic solvent such as toluene or xylene capable of dissolving both the monomer components and the resin that is to be formed.
  • the mixture solution is introduced into a reaction oven and is polymerized with sufficient stirring. After the polymerization, the solution is deaerated and is dried to obtain a polymer that serves as a low molecular component.
  • the time and temperature of polymerization are usually from 60 to 250°C and from about 3 to about 10 hours, though they may vary depending upon the kind and amount of the polymerization initiator.
  • the temperature and time of polymerization are set depending upon the kind and amount of the polymerization initiator so that there is obtained a polymer having a molecular weight in a desired range. Usually, however, the temperature and time of polymerization is from 60 to 200°C and from about 5 to about 24 hours.
  • the acid value can be easily adjusted by adjusting the amount of feeding the anionic polar group-containing monomers.
  • a parting agent such as wax is usually blended in the toner.
  • the wax that is blended as a parting agent has an SP value (solubility parameter) greatly different from that of the fixing resin medium and cannot be uniformly dispersed in the medium causing the amount of wax to vary depending upon the individual toner particles or causing the wax to be distributed in deviated amounts on the surfaces of the toner particles. That is, when the developing is effected using such a toner, the wax tends to adhere as spent on the surfaces of the carrier particles.
  • the fixing resin medium contains a polymer component that has a higher alkyl group with not less than 12 carbon atoms on a side chain thereof.
  • Use of the polymer component having such a higher alkyl group makes it possible to effectively solve the above-mentioned problem that stems from nonuniform dispersion of the parting agent. Though the reason has not yet been clarified, the present inventors consider it as described below.
  • a polymer having a higher alkyl group on a side chain thereof has an SP value close to that of the wax, and is, hence, compatible with the wax. It is therefore considered that the fixing resin medium containing such a polymer permits the parting agent to be uniformly dispersed therein.
  • the polymer having a higher alkyl group may be the aforementioned polymer having an anionic polar group and having a higher alkyl group on a side chain thereof. Or, the polymer having an anionic polar group may be used as a separate polymer. Generally, the former polymer is preferably used.
  • the fixing resin medium is prepared by using, for example, a monomer for introducing anionic groups, a monomer for introducing higher alkyl groups and, as required, other monomers, and polymerizing these monomers based upon the block-polymerization, random polymerization or graft-polymerization.
  • the monomer for introducing higher alkyl groups will be the one having a higher alkyl group selected from the aforementioned monomers of the formulas (1) to (6).
  • Preferred examples of the fixing resin medium include the following copolymers, i.e., (meth)acrylic acid-stearyl (meth)acrylate copolymer, styrene-stearyl (meth)acrylate-(meth)acrylic acid copolymer, (meth)acrylic acid ester-stearyl (meth)acrylate-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid ester-stearyl (meth)acrylate-(meth)acrylic acid copolymer, styrene-stearyl (meth)acrylate-maleic acid copolymer, maleic acid-stearyl(meth)acrylate copolymer, styrene-tridecyl (meth)acrylate-(meth)acrylic acid copolymer, styrene-lauryl (meth)acrylate-(meth)acrylic acid copolymer.
  • copolymers
  • the acid values should lie within the aforementioned range.
  • the higher alkyl group on the side chain of the polymer exists in an amount of from 0.1 to 20 parts by weight and, particularly, from 0.5 to 10 parts by weight per 100 parts by weight of the fixing resin medium on the basis of the monomer having the higher alkyl group.
  • the amount of the higher alkyl group is smaller than the above-mentioned range, compatibility drops between the parting agent and the fixing resin medium, and durability is not improved to a satisfactory degree.
  • the amount of the higher alkyl group is larger than the above-mentioned range, on the other hand, the fixing resin medium exhibits decreased Tg and the toner loses preservation stability.
  • any carbon black can be dispersed in the fixing resin medium provided it has a pH of smaller than 7 and, preferably, from 2 to 5 and has a ratio (7-pH)/specific area (m 2 /g) of from 0.010 to 0.050 and, particularly, from 0.015 to 0.040.
  • a pH of smaller than 7 and, preferably, from 2 to 5 and has a ratio (7-pH)/specific area (m 2 /g) of from 0.010 to 0.050 and, particularly, from 0.015 to 0.040 it is desired to use furnace black treated with acid so as to have a pH value satisfying the above-mentioned conditions.
  • the treatment with acid can be carried out by using an inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid or by using an organic acid such as acetic acid, citric acid, propionic acid, benzoic acid, salicylic acid or toluenesulfonic acid. Due to this treatment, an acidic group such as carboxylic group is introduced into the surfaces of the carbon black to reinforce the negatively charging property of the toner. As will be obvious from the pH conditions mentioned above, the acid is used in a very small amount in the treatment and does not adversely affect electric properties of the toner.
  • an inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid
  • organic acid such as acetic acid, citric acid, propionic acid, benzoic acid, salicylic acid or toluenesulfonic acid. Due to this treatment, an acidic group such as carboxylic group is introduced into the surfaces of the carbon black to reinforce the negatively charging property
  • the carbon black has a specific surface area of usually not smaller than 50 m 2 /g and, particularly, from 100 to 300 m 2 /g from the standpoint of dispersion property in the resin.
  • the carbon black is blended in an amount of from 4 to 15% by weight and, particularly, from 6 to 12% by weight per the fixing resin medium.
  • the blending amount is smaller than the above-mentioned range, negatively charging property of the toner is not satisfactory causing fogging to occur.
  • the carbon black is used in an amount larger than the above range, on the other hand, the toner exhibits decreased fixing property.
  • the toner for a two-component magnetic developing agent of the present invention may be blended with various additives in addition to the above-mentioned carbon black like the conventional toners but without being blended with the charge control agent.
  • additives may include parting agent, body, fixing improving agent, magnetic powder, etc.
  • the present invention which uses, as a fixing resin medium, a resin composition containing the above-mentioned low molecular components and high molecular components, it is allowed to increase resistance against the offset during the heat-fixing. By being blended with a parting agent, furthermore, resistance against the offset can be further improved.
  • Such a parting agent may be natural or synthetic waxes.
  • a polyolefin wax such as polypropylene wax, polyethylene wax, propylene-ethylene random copolymer wax and, particularly, polypropylene wax.
  • Such a parting agent is used in an amount of from 0.01 to 10 parts by weight and, particularly, from 0.1 to 6 parts by weight per 100 parts by weight of the fixing resin medium.
  • amount is smaller than the above-mentioned range, resistance against the offset is not satisfactory.
  • amount is larger than the above-mentioned range, on the other hand, charging property of the toner decreases and the toner scatters and develops fogging due to poor electric charge.
  • a fixing resin medium containing a polymer that has a higher alkyl group on a side chain thereof As mentioned earlier.
  • the above-mentioned wax can be blended in the toner by being graft-fixed to a suitable polymer such as the polymer constituting the fixing resin medium.
  • the wax that is blended by the graft-fixing is very advantageous from the standpoint of uniformly dispersing the wax in the fixing resin medium.
  • the wax can be easily graft-fixed relying upon the radical polymerization in the presence of wax at the time of synthesizing the copolymerized resin having anionic polar group based on the radical polymerization. That is, the wax is graft-fixed to part of the copolymer having anionic polar group; i.e., the wax is graft-fixed simultaneously with the preparation of the copolymerized resin for fixing.
  • a resin or a copolymerized resin containing a polymer to which the wax is graft-fixed is obtained by subjecting a monomer without anionic polar group, for example, by subjecting at least one of the monomers (preferably, having a higher alkyl group) of the formulas (2) to (6), to the radical polymerization in the presence of wax.
  • This resin or copolymerized resin may be blended with a copolymerized resin containing an anionic polar group.
  • the extender pigment is blended to adjust physical properties such as bulk density, etc., and its examples include barite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white. Such a pigment is used in an amount of from 2 to 20 parts by weight and, particularly, from 5 to 15 parts by weight per 100 parts by weight of the fixing resin medium.
  • the fixing resin medium may be blended with a magnetic powder in addition to the above-mentioned blending agents.
  • a magnetic powder By being blended with such a magnetic powder, the toner particles in the magnetic brush during the developing is held on the carrier by the coulomb force as well as the magnetic attractive force. Accordingly, the toner is more reliably prevented from scattering, which is very desirable from the standpoint of preventing the copying machine from being contaminated with toner and preventing the copy from developing fogging.
  • Such advantages are desired as the copying speed increases.
  • the amount of charge can be decreased per a toner particle. Therefore, developing sensitivity can be increased and image of a high density can be obtained.
  • the magnetic powder examples include those magnetic powders that have heretofore been used for the magnetic toners such as tri-iron tetroxide (Fe 3 O 4 ), iron sesquioxide ( ⁇ -Fe 2 O 3 ), zinc iron oxide (ZnFe 2 O 4 ), yttrium iron oxide (Y 3 Fe 5 O 12 ), cadmium iron oxide (CdFe 2 O 4 ), gadolinium iron oxide (Gd 3 Fe 5 O 12 ), copper iron oxide (CuFe 2 O 4 ), lead iron oxide (PbFe 12 O 19 ), nickel iron oxide (NiFe 2 O 4 ), neodymium iron oxide (NdFeO 3 ), barium iron oxide (BaFe 12 O 19 ), magnesium iron oxide (MgFe 2 O 4 ), manganese iron oxide (MnFe 2 O 4 ), lanthanum iron oxide (LaFeO 3 ), iron powder (Fe), cobalt powder (Co), nickel powder (Ni), etc. Particularly preferred magnetic powder
  • the preferred magnetite is of a regular octahedral shape having particle sizes of from 0.05 to 1.0 ⁇ m.
  • the magnetite particles may be treated for their surfaces with a silane coupling agent or a titanium coupling agent.
  • the magnetic powder may be blended in an amount as small as from 0.1 to 5 parts by weight and, particularly, from 0.5 to 3.0 parts by weight per 100 parts by weight of the resin medium.
  • the magnetic powder is used in an amount larger than 10 parts by weight per 100 parts by weight of the resin medium.
  • the magnetic powder is used in an amount considerably smaller than the above-mentioned amount. The internal addition of the magnetic powder even in such a small amount makes it possible to form an image of a high density yet preventing the toner from scattering.
  • the present invention it is desired to blend a polyethylene having a number average molecular weight of from 1000 to 7000 as a fixing improving agent. That is, the anionic polar group contained in the fixing resin medium gives negatively charging property to the toner but tends to increase the heat-melting temperature of the resin medium due to association among the polar groups. Such a rise in the heat-melting temperature is not desirable from the standpoint of fixing.
  • the polyethylene having the above-mentioned number average molecular weight that is blended makes it possible to prevent a drop in the fixing property caused by the presence of anionic polar groups but rather helps increase the fixing property. Though the reason is not yet obvious why the polyethylene that is blended helps improve the fixing property, the present inventors consider it in the following way.
  • the polyethylene having a number average molecular weight over the above-mentioned range has a softening point lower than that of the fixing resin medium, and loses the viscosity abruptly near its softening point and melts.
  • the toner is heat-fixed, therefore, the polyethylene melts, first, and infiltrates into the paper.
  • the fixing resin medium loses wettability for the paper and exhibits improved permeability.
  • the fixing resin medium that is melted does not diffuse but infiltrates into the paper enabling the fixing property to be improved.
  • the polyethylene is used in an amount of from 0.5 to 5 parts by weight per 100 parts by weight of the fixing resin medium from the standpoint of improving fixing property of the toner without impairing other properties.
  • the toner of the present invention can be prepared by a widely known method such as pulverization-classification method, melt-granulation method, spray-granulation method or polymerization method.
  • the toner is prepared by the pulverization-classification method. That is, the above-mentioned fixing resin medium and various blending agents are pre-mixed together in a mixer such as Henschel's mixer and are kneaded using a kneader such as biaxial extruder. The kneaded composition is cooled, pulverized and is classified to obtain a toner.
  • the particle diameter of the toner is generally from 5 to 15 ⁇ m and, particularly, from 7 to 12 ⁇ m in terms of a volume-based average particle diameter (median diameter using the Coulter counter).
  • a fluidity improving agent such as silica obtained by the hydrophobic vapor-phase method is externally adhered onto the surfaces of the toner particles to improve fluidity of the toner.
  • the fluidity improving agent is a very fine powder having a primary particle size of usually as small as from 0.005 to 0.050 ⁇ m, and is externally added in an amount of from 0.1 to 2.0% by weight with respect to the whole weight of the toner (total amount of the toner particles and the externally added agents).
  • spacer particles having a diameter of from 0.05 to 1.0 ⁇ m and, particularly, from 0.07 to 0.5 ⁇ m larger than the particle diameter of the fluidity improving agent are externally added to the toner particles together with the fluidity improving agent.
  • spacer particles being externally added, bonding is weakened between the toner image and the latent image on the surface of the photosensitive member, enabling the toner image to be easily peeled and the transfer efficiency to be improved in the step of transferring the toner image.
  • the spacer particles use is made of organic or inorganic inert particles of a definite shape having the aforesaid particle diameter.
  • the particle diameter is larger than the above-mentioned range, the bonding force becomes weak between the toner image and the latent image on the surface of the photosensitive material, and it becomes difficult to form a favorable image.
  • the particle diameter is smaller than the above-mentioned range, on the other hand, a sufficiently large gap is not formed between the toner image and the latent image (photosensitive material), whereby the bonding force is not weakened between the two and the transfer efficiency is not improved to a satisfactory degree.
  • the inert particles having a definite shape may include silica, alumina, titanium oxide, magnesium carbonate, acrylic resin powder, styrene resin powder and magnetic powder. They should be externally added in an amount of not larger than 10% by weight, preferably, from 0.1 to 10% by weight and, most preferably, from 0.1 to 5% by weight with respect to the whole weight of the toner (total amount of the toner particles and externally added materials). When they are used in excess amounts, the density of the image decreases. When a magnetic powder is used as the spacer particles, it is desired that the total amount of the magnetic powder inclusive of the magnetic powder that has been internally added to the toner particles is not larger than 10% by weight with respect to the fixing resin medium. When the total amount becomes too large, the density of the image decreases, too.
  • first spacer particles having a resistivity of from 10 to 10 5 ⁇ cm and, particularly from 10 3 to 10 5 ⁇ cm and second spacer particles having a resistivity of from 10 8 to 10 13 ⁇ cm and, particularly, from 10 9 to 10 12 ⁇ cm in combination Use of two kinds of spacer particles having different resistivities makes it possible to enhance the transfer efficiency of the toner image from the photosensitive material onto the transfer paper as well as to divide the resistance on the surfaces of the toner particles into two. From the viewpoint of exchange of electric charge of the toner, therefore, the function is divided for generating the electric charge and for leaking the electric charge. As a result, the toner maintains desired amount of electric charge efficiently and more stably, so that image is formed maintaining stable density.
  • the resistivity can be easily adjusted by treating the surfaces to be electrically conducting, i.e., doping the surfaces with, for example, tin. That is, the spacer particles that are usually used have a relatively large resistivity like the second spacer particles and are treated to become electrically conducting and to exhibit a decreased resistivity, and are used as the first spacer particles.
  • the spacer particles that are usually used have a relatively large resistivity like the second spacer particles and are treated to become electrically conducting and to exhibit a decreased resistivity, and are used as the first spacer particles.
  • titanium oxide or magnesium oxide of which the surfaces are doped with tin is favorably used as the first spacer particles
  • titanium oxide or magnesium oxide which is not doped with tin is favorably used as the second spacer particles.
  • the first spacer particles and the second spacer particles are used at a weight ratio of from 1:7 to 7:1 and, particularly, from 1:4 to 4:1, and in a total amount as described earlier.
  • the resistivity of the spacer particles can be measured by using, for example, a resistivity measuring device 4 shown in Fig. 10.
  • a sample of spacer particles (203) is introduced into a vinyl chloride tube (41) having an inner diameter (H 1 ) of 1 inch and is sandwiched by electrodes (421) made of a steel.
  • Teflon plates (43) having a thickness of 2 mm are arranged on both outer sides of the electrodes (421), and a pressure Pr of 200 kg/cm 2 is applied from one side of the Teflon plates (43) by using a hydraulic pressing machine, in order to measure a resistance r ( ⁇ ) at 500 V using an ultra-insulation resistance tester (42) (Model SM-5 manufactured by Toa Denpa Kogyo Co.).
  • the surfaces of the toner particles onto which the spacer particles will be adhered or the surfaces of the spacer particles are treated with a metal stearate or amide, i.e., it is desired that the metal stearate is adhered onto the surfaces of either of these particles.
  • parting property is not adversely affected between the toner particles and the surface of the photosensitive material and, besides, the resistance of the toner suitably decreases, which is advantageous for forming image maintaining a high density.
  • the melting temperature of the toner decreases giving another advantage in that infiltration of the toner into the transfer paper is promoted during the heat-fixing by using a heat roll, and fixing property of the transferred toner image is enhanced.
  • the melting temperature of the metal stearate is lower than the melting temperature of the fixing resin medium, the surface of the image exhibits improved smoothness when the transferred toner image is heat-fixed, making it possible to obtain image with luster.
  • metal stearate or amide examples include zinc stearate, magnesium stearate, aluminum stearate, calcium stearate, chromium stearate, mercury stearate, cerium stearate, ferric stearate, sodium stearate, lead stearate, barium stearate and stearic acid amide, which may be used in a single kind or in a combination of two or more kinds.
  • zinc stearate or magnesium stearate Most desirably, zinc stearate is used in a single kind.
  • these metal stearates are used in an amount of from 0.001 to 3% by weight, preferably, from 0.003 to 1% by weight and, most preferably, from 0.005 to 0.2% by weight per the whole weight of the toner. Moreover, the metal stearates may be adhered on the surfaces of the toner particles or on the surfaces of the spacer particles.
  • any widely known magnetic carrier can be used in combination with the above-mentioned toner.
  • magnetite (M Fe) or ferrite (M is other than Fe) represented by the following formula (7), MOFe 2 O 3 (7) wherein M is at least one metal selected from the group consisting of Cu, Zn, Fe, Ba, Ni, Mg, Mn, Al and Co.
  • the magnetic carrier particles permit electric resistance to change little depending upon the environment or aging, and exhibit stable charging property.
  • the magnetic brush has a soft ear and does develop white streaks such as sweeping traces of magnetic brush on the formed image.
  • the magnetic carrier has an average particle diameter of generally from 30 to 200 ⁇ m and, particularly, from 50 to 150 ⁇ m, a saturation magnetization of from 30 to 80 emu/g and, particularly, from 45 to 70 emu/g, and a volume resistivity of from 10 5 to 10 9 ⁇ cm and, particularly from 10 6 to 10 8 ⁇ cm.
  • the magnetic carrier particles serving as cores may be coated with a variety of thermoplastic resins and thermosetting resins.
  • the thermoplastic resin include thermoplastic acrylic resin, thermoplastic styrene-acrylic resin, polyester resin, polyamide resin and olefin-type copolymer resin
  • the thermosetting resin include modified or unmodified silicone resin, thermosetting acrylic resin, thermosetting styrene-acrylic resin, phenol resin, urethane resin, thermosetting polyester resin, epoxy resin, amino resin, fluorine-containing resin and melamine resin.
  • Such resin coatings make it possible to more effectively avoid the occurrence of spent toner.
  • the amount of resin coating is from 0.001 to 2.5 parts by weight and, particularly, from 0.005 to 2.0 parts by weight per 100 parts by weight of the core particles.
  • a cationic polar group is introduced into the coating resin. That is, provision of the resin coating layer having a cationic polar group helps increase the positively charging property of the carrier whereby the negatively charging property of the toner is further enhanced.
  • a cationic polar group can be represented by a basic nitrogen-containing group such as primary, secondary or tertiary amino group, quaternary ammonium group, amide group, imino group, imide group, hydrazino group, guanidino group or amidino group. Among them, amino group and quaternary ammonium group are particularly preferred.
  • the resin should be produced by using, for example, a monomer component having the cationic group.
  • the cationic polar group can be also introduced by treating the surfaces of the resin using a silane coupling agent having a cationic group.
  • the silane coupling agent may include N- ⁇ (aminoethyl) ⁇ -aminopropyltrimethoxysilane, N- ⁇ (aminoethyl) ⁇ -aminopropylmethyldimethoxysilane, ⁇ -aminopropyltriethoxysilane, N-phenyl- ⁇ -aminopropyltrimethoxysilane, etc.
  • the cationic polar group is introduced usually in an amount of from 0.1 to 2000 millimols and, particularly, from 0.5 to 1500 millimols per 100 g of the resin.
  • the resin coating layer may be blended with a variety of known additives such as silica, alumina, carbon black, fatty acid metal salt, silane coupling agent, silicone oil, etc., as a matter of course.
  • the carrier particles serving as cores can be coated with a resin by a widely known method.
  • the above-mentioned coating resin is dissolved in a suitable solvent.
  • the resin solution the resin is coated by immersion method, spray method, fluidized bed method, moving bed method or rolling bed method.
  • the resin may be cured by heating or the like means after the resin is coated by using a solution of uncured resin or oligomer.
  • a binder-type carrier obtained by dispersing a magnetic powder in a binder resin.
  • a magnetic powder there can be preferably used the aforementioned magnetic powder and, particularly, the magnetite having a particle diameter of not larger than 2.0 ⁇ m and, particularly, from 0.05 to 1.0 ⁇ m.
  • the magnetic powder may be used in an amount of from 150 to 900 parts by weight and, particularly, from 250 to 600 parts by weight per 100 parts by weight of the binder resin.
  • binder resin examples include thermoplastic resin, thermosetting resin which is uncured or in the form of an initial condensate, such as aromatic vinyl resin like polystyrene, as well as acrylic resin, polyvinyl acetal resin, polyester resin, epoxy resin, phenol resin, petroleum resin and polyolefin resin. Among them, styrene resin, acrylic resin and styrene-acrylic copolymer resin are preferred.
  • the binder-type carrier may be blended with a known assistant such as carbon black for adjusting electric resistance, dispersing agent, dispersion assistant, low molecular or high molecular charge control agent.
  • a known assistant such as carbon black for adjusting electric resistance, dispersing agent, dispersion assistant, low molecular or high molecular charge control agent.
  • the cationic polar group may be introduced to enhance the positively charging property of the carrier in order to enhance the negatively charging property of the toner.
  • the toner of the present invention is mixed together with the above-mentioned various magnetic carriers and is used as a magnetic developing agent. Generally, it is desired that these carriers and the toner are mixed together at a ratio of from 98:2 to 90:10 and, particularly, from 97:3 to 94:6 on the weight basis.
  • the electrostatic latent image can be formed by any known system.
  • the photoconducting layer on the conducting substrate is uniformly charged and is exposed to light to form an electrostatic latent image.
  • the electrostatic image is easily developed by bringing a magnetic brush of the two-component magnetic developing agent into contact with the substrate.
  • the toner image formed by developing is transferred onto a copying paper and is fixed upon contact with a heating roll.
  • Fig. 11 shows a curve of GPC molecular weight of the low molecular polymer, from which it will be obvious that the low molecular polymer has a peak molecular weight in a region of from 4,000 to 30,000.
  • Fig. 12 shows a curve of GPC molecular weight of the resin for fixing, from which it will be obvious that the resin for fixing exhibits nearly the same peak molecular weight as that of the above-mentioned low molecular polymer and further exhibits molecular weight distribution on the side of high molecular weight.
  • the resin for fixing possessed a weight average molecular weight of 100,000.
  • fixing resin for obtained above 100 parts by weight, carbon black (pH: 3.5, (7-pH)/specific surface area: 0.025, treated with nitric acid), 9 parts by weight, and magnetite (magnetic powder), 2 parts by weight, were melt-kneaded using a biaxial extruder.
  • the kneaded product was then pulverized using a jet mill and was classified by a wind classifier to obtain particles of a diameter of 10.0 ⁇ m.
  • the toner obtained above and an uncoated ferrite carrier having an average particle diameter of 100 ⁇ m were mixed together to obtain a two-component developing agent having a toner concentration of 3.5%.
  • spherical ferrite particles having an average particle diameter of 100 ⁇ m were added to a coating solution obtained by dissolving 3.5 parts by weight of styrene-acrylic resin and 1.5 parts by weight of methylated melamine resin in 200 parts by weight of toluene, and were heated and stirred. Then, the solvent (toluene) was removed by drying from the mixture obtained above and was heat-treated at 200°C for one hour to obtain resin-coated carrier particles.
  • a two-component developing agent having a toner concentration of 3.5% by weight was obtained quite in the same manner as in Example 1 with the exception of using the above carrier particles as the magnetic carrier.
  • the kneaded product was then pulverized using a jet mill and was classified by a wind classifier to obtain carrier particles of a diameter of 80 ⁇ m.
  • a two-component developing agent having a toner concentration of 5.0% by weight was obtained in the same manner as in Example 1 by using magnetic carrier particles that were obtained by dispersing the magnetic powder in the resin.
  • a toner and a developing agent were prepared in the same manner as in Example 1 but using the carbon black having a pH of 9 and a ratio (7-pH)/specific surface area of -0.013 (without treated with acid).
  • a toner and a developing agent were prepared in the same manner as in Example 1 but using the carbon black having a pH of 3 and a ratio (7-pH)/specific surface area of -0.122 (treated with nitric acid).
  • the amount of toner in a toner hopper prior to starting the copying operation and the amount of toner in the toner hopper after a predetermined number of copies were taken, were measured, and the amount of toner that was consumed was calculated from a difference therebetween. Furthermore, the amount of toner recovered in a step of cleaning was measured while the predetermined number of copies were being taken to find the amount of toner that was recovered. Based upon these values, the toner transfer efficiency was calculated in compliance with the following formula. Here, the document being copied was a character document having a black area of 8%. Transfer efficiency (%) [(A - B)/A] x 100 wherein A represents the amount of toner consumed, and B represents the amount of toner recovered.
  • the developing agent was sampled.
  • the developing agent was placed on a sieve of 400 mesh and was sucked by a blower from the lower side to separate it into the toner and the carrier. 5 Grams of the carrier remaining on the sieve was introduced into a beaker, and toluene was further added thereto in order to dissolve the toner that adhered onto the carrier surfaces as spent toner. Then, the toluene solution was discarded in a state where the carrier was attracted by a magnet from the lower side of the beaker.
  • Comparative Example 1 On the other hand, the toner scattered to a conspicuous degree at normal temperature. Under high-temperature and high-humidity conditions, furthermore, the toner developed fogging and scattered to a conspicuous degree.
  • the toner maintains the electric charge in an amount large enough for effecting the developing, no charge control agent migrates onto the carrier surfaces, and the charging property is not deteriorated by the spent toner but is stably maintained for extended periods of time, enabling the life of the toner and the carrier to be lengthened.
  • the acid value of the low molecular components contained in the fixing resin medium By setting the acid value of the low molecular components contained in the fixing resin medium to be lower than the acid value of the whole resin, furthermore, the charging property of the toner is more reliably prevented from being impaired by the spent toner, and scattering of toner and fogging can be effectively avoided.
  • a fixing resin use was made of a copolymerized resin containing units inherent in styrene, stearyl methacrylate, acrylic acid and butyl methacrylate at weight ratios of 74:4:5:16, having an acid value of 10, peak molecular weight of a low molecular polymer component of 10,000, and a weight average molecular weight of 100,000.
  • fixing resin obtained above 100 parts by weight, polypropylene wax (average molecular weight: 4000), 3 parts by weight, carbon black (pH: 3.5, (7-pH)/specific surface area (m 2 /g): 0.025, treated with nitric acid), 10 parts by weight, and magnetite (magnetic powder), 2 parts by weight, were melt-kneaded using a biaxial extruder.
  • the kneaded product was then pulverized using a jet mill and was classified by a wind classifier to obtain particles of a diameter of 10.0 ⁇ m.
  • the toner obtained above and a ferrite carrier having an average particle diameter of 100 ⁇ m were mixed together to obtain a two-component developing agent having a toner concentration of 3.5% by weight.
  • a fixing resin (containing no higher alkyl group) comprising a styrene-acrylic acid-butyl methacrylate copolymer was prepared in the same manner as in Example 1 but using styrene, acrylic acid and butyl methacrylate at weight ratios of 75:20:5.
  • the resin possessed a peak molecular weight due to a low molecular polymer component of 10,000 and a weight average molecular weight of 100,000.
  • a toner and a developing agent were prepared in the same manner as in Example 4 but using the above resin for fixing.
  • spherical ferrite particles having an average particle diameter of 100 ⁇ m were added to a coating solution obtained by dissolving 3.5 parts by weight of styrene-acrylic resin and 1.5 parts by weight of methylated melamine resin in 200 parts by weight of toluene, and were heated and stirred. Then, the solvent (toluene) was removed by drying from the mixture obtained above and was heat-treated at 200°C for one hour to obtain resin-coated carrier particles.
  • a two-component developing agent having a toner concentration of 3.5% by weight was obtained quite in the same manner as in Example 4 but using the above carrier particles as the magnetic carrier.
  • the kneaded product was then pulverized using a jet mill and was classified by a wind classifier to obtain carrier particles of a diameter of 80 ⁇ m.
  • a two-component developing agent having a toner concentration of 5.0% by weight was obtained in the same manner as in Example 1 but using binder-type carrier particles that were obtained by dispersing the magnetic powder in the resin.
  • Example 5 which uses the fixing resin medium without higher alkyl group-containing polymer component.
  • Example 4 using a higher alkyl group-containing fixing resin medium, however, the durability is improved to a considerable degree.
  • the following components a mixture of styrene, butyl methacrylate and acrylic acid at a weight ratio of 80:15:5, 100 parts by weight, and a polypropylene wax (average molecular weight: 4,000), 0.6 parts by weight, a polymerization initiator were mixed, stirred and dissolved in a solvent.
  • the obtained mixture solution was introduced into a reaction oven and was polymerized at 150°C for 5 hours with sufficient stirring using a stirrer vane. Thereafter, the reaction solution was deaerated and dried to obtain a low molecular polymer containing a component to which the polypropylene wax is graft-fixed.
  • low molecular polymer obtained above 100 parts by weight, a mixture of styrene, butyl methacrylate and acrylic acid at a weight ratio of 70:25:5, 100 parts by weight, the same polypropylene wax as the above one, 5.4 parts by weight, and a polymerization initiator, were mixed and stirred in a solvent to prepare a mixture solution.
  • the mixture solution was introduced into a reaction oven and was polymerized at 80 ⁇ é for 15 hours with sufficient stirring using stirrer vanes.
  • the reaction solution was then deaerated and dried to obtain a desired fixing resin having an acid value of 10.
  • the fixing resin possessed a peak molecular weight of 10,000, a molecular weight distribution on the side of high molecular weights, and a weight average molecular weight of 100,000.
  • fixing resin obtained above 103 parts by weight (containing 3 parts by weight of wax), carbon black (pH: 3.5, (7-pH)/specific surface area (m 2 /g): 0.025, treated with nitric acid), 10 parts by weight, and magnetite (magnetic powder), 2 parts by weight, were melt-kneaded using a biaxial extruder.
  • the kneaded product was then pulverized using a jet mill and was classified by a wind classifier to obtain particles of a diameter of 10.0 ⁇ m.
  • the toner obtained above and a ferrite carrier having an average particle diameter of 100 ⁇ m were mixed together to obtain a two-component developing agent having a toner concentration of 3.5% by weight.
  • a resin for fixing was prepared in the same manner as in Example 8 but without using polypropylene wax.
  • a toner was prepared quite in the same manner as in Example 8 but using 100 parts by weight of the above resin for fixing and 3 parts by weight of the polypropylene wax used in Example 8. Then, a two-component developing agent was prepared.
  • spherical ferrite particles having an average particle diameter of 100 ⁇ m were added to a coating solution obtained by dissolving 3.5 parts by weight of styrene-acrylic resin and 1.5 parts by weight of methylated melamine resin in 200 parts by weight of toluene, and were heated and stirred. Then, the solvent (toluene) was removed by drying from the mixture obtained above and was heat-treated at 200°C for one hour to obtain resin-coated carrier particles.
  • a two-component developing agent having a toner concentration of 3.5% by weight was obtained quite in the same manner as in Example 8 but using the above resin-coated carrier particles.
  • the kneaded product was then pulverized using a jet mill and was classified by a wind classifier to obtain binder-type carrier particles of a diameter of 80 ⁇ m.
  • a two-component developing agent having a toner concentration of 5.0% by weight was obtained in the same manner as in Example 8 but using binder-type carrier particles that were obtained by dispersing the magnetic powder in the resin.
  • resin for fixing styrene-acrylic copolymer having a carboxyl group, acid value of 8
  • 100 parts by weight carbon black (pH: 3.5, (7-pH)/specific surface area (m 2 /g): 0.025, 7 parts by weight, magnetic powder (magnetite), 2 parts by weight, and polyethylene resin (molecular weight: 4000), 2 parts by weight, were melt-kneaded using a biaxial extruder.
  • the kneaded product was then pulverized using a jet mill and was classified by a wind classifier to obtain toner particles having an average particle diameter of 10.0 ⁇ m.
  • the toner obtained above and a ferrite carrier having an average particle diameter of 100 ⁇ m were mixed together to obtain a two-component developing agent having a toner concentration of 3.5% by weight.
  • the toner particles were prepared quite in the same manner as in Example 12 but without being blended with polyethylene, and a developing agent was prepared.
  • a flat bottom of a weight of 400 g was wrapped with a uniformly stretched cotton cloth to rub a solid black portion of the image five round trips at a predetermined speed.
  • the image density (ID) of before being rubbed and the image density (ID) of after rubbed were measured, and a peeling factor was regarded to be a fixing factor.
  • Fixing factor (%) ID after rubbing ID before rubbing x 100
  • Example 13 the fixing factor was slightly smaller than 80% but in Example 12, the fixing factor was not smaller than 90%.
  • Styrene, butyl methacrylate and acrylic acid were mixed together at weight ratios of 80:15:5, and were mixed and dissolved together with a polymerization initiator in a solvent with stirring.
  • the reaction system was heated and polymerized. After polymerized, the reaction solution was deaerated and dried to prepare a resin for fixing comprising a styrene-butyl methacrylate-acrylic acid copolymerized resin.
  • the resin for fixing possessed an acid value of 10.
  • the weight average molecular weight of the resin for fixing was 100,000.
  • resin for fixing obtained above 100 parts by weight, carbon black (pH: 3.5, (7-pH)/specific surface area (m 2 /g): 0.025, treated with nitric acid), 7 parts by weight, and magnetite (magnetic powder), 2 parts by weight, were melt-kneaded using a biaxial extruder.
  • the kneaded product was then pulverised using a jet mill and was classified by a wind classifier to obtain particles of a diameter of 10.0 ⁇ m.
  • the surface-treated toner particles and a ferrite carrier having an average particle diameter of 100 ⁇ m were mixed together to obtain a two-component developing agent having a toner concentration of 3.5% by weight.
  • a toner and a developing agent were prepared quite in the same manner as in Example 14 but using, as spacer particles, 0.5 parts by weight of magnetite particles (2 x 10 3 ⁇ cm) having an average particle diameter of 0.3 ⁇ m and 0.5 parts by weight of alumina particles (10 10 ⁇ cm) having an average particle diameter of 0.3 ⁇ m.
  • a toner and a developing agent were prepared quite in the same manner as in Example 14 but externally adding 0.2 parts by weight of zinc stearate.
  • spherical ferrite particles having an average particle diameter of 100 ⁇ m were added to a coating solution obtained by dissolving 3.5 parts by weight of styrene-acrylic resin and 1.5 parts by weight of methylated melamine resin in 200 parts by weight of toluene, and were heated and stirred. Then, the solvent (toluene) was removed by drying from the mixture obtained above and was heat-treated at 200°C for one hour to obtain resin-coated carrier particles.
  • a two-component developing agent having a toner concentration of 3.5% by weight was obtained quite in the same manner as in Example 14 but using the above carrier particles as a magnetic carrier.
  • the kneaded product was then pulverized using a jet mill and was classified by a wind classifier to obtain binder-type carrier particles of a diameter of 80 ⁇ m.
  • a two-component magnetic developing agent having a toner concentration of 5.0% by weight was obtained in quite the same manner as in Example 14 but using the binder-type carrier particles that were obtained by dispersing the magnetic powder in the resin.
  • a toner and a developing agent were prepared quite in the same manner as in Example 14 but using the carbon black having pH of 9 and a ratio (7-pH)/specific surface area (m 2 /g) of -0.013, which has not been treated with acid.
  • a toner and a developing agent were prepared in quite the same manner as in Example 14 but without using spacer particles.
  • the amount of toner in a toner hopper prior to starting the copying operation and the amount of toner in the toner hopper after a predetermined number of copies were taken, were measured, and the amount of toner that was consumed was calculated from a difference therebetween. Furthermore, the amount of toner recovered in a step of cleaning was measured while the predetermined number of copies were being taken to find the amount of toner that was recovered. Based upon these values, the toner transfer efficiency was calculated in compliance with the following formula. Here, the document being copied was a character document having a black area of 8%. Transfer efficiency (%) [(A - B)/A] x 100 wherein A represents the amount of toner consumed, and B represents the amount of toner recovered.
  • the invention provides a negatively chargeable toner which maintains an electric charge in an amount sufficient for developing in the absence of a negative charge control agent. Hence migration of charge control agent to the surface of the magnetic carrier is prevented and the deterioration of charging properties by the occurrence of spent toner is reduced.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Developing Agents For Electrophotography (AREA)
EP96303651A 1995-05-23 1996-05-22 Toner für magnetische Zweikomponentenentwickler Withdrawn EP0744668A3 (de)

Applications Claiming Priority (10)

Application Number Priority Date Filing Date Title
JP7123743A JPH08314194A (ja) 1995-05-23 1995-05-23 二成分系磁性現像剤用トナー
JP123743/95 1995-05-23
JP128084/95 1995-05-26
JP7128699A JPH08328301A (ja) 1995-05-26 1995-05-26 二成分系磁性現像剤用トナー及び現像剤
JP128082/95 1995-05-26
JP7128082A JPH08320595A (ja) 1995-05-26 1995-05-26 二成分系磁性現像剤用トナー及び現像剤
JP7128084A JPH08320592A (ja) 1995-05-26 1995-05-26 二成分系磁性現像剤用トナー及び現像剤
JP128699/95 1995-05-26
JP7128083A JPH08320596A (ja) 1995-05-26 1995-05-26 二成分系磁性現像剤用トナー及び現像剤
JP128083/95 1995-05-26

Publications (2)

Publication Number Publication Date
EP0744668A2 true EP0744668A2 (de) 1996-11-27
EP0744668A3 EP0744668A3 (de) 1997-01-02

Family

ID=27527002

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96303651A Withdrawn EP0744668A3 (de) 1995-05-23 1996-05-22 Toner für magnetische Zweikomponentenentwickler

Country Status (3)

Country Link
EP (1) EP0744668A3 (de)
KR (1) KR960042242A (de)
CA (1) CA2177103A1 (de)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0869399A2 (de) * 1997-04-04 1998-10-07 Canon Kabushiki Kaisha Toner zur Herstellung von Bildern, Bildherstellungsverfahren, und Wärme-Fixierungsverfahren
US6352808B1 (en) 1999-09-30 2002-03-05 Minolta Co., Ltd. Electrostatic-latent-image developing toner and inorganic particles used for such a toner
EP1980914A1 (de) * 2007-04-10 2008-10-15 Xerox Corporation Chemischer Toner mit kovalentem Bindungsfreigabewirkstoff
US7470498B2 (en) 2003-03-31 2008-12-30 Kanto Denka Kogyo Co., Ltd. Mg-based ferrite, an electrophotographic development carrier containing the ferrite, and a developer containing the carrier
EP3582019A1 (de) * 2018-06-13 2019-12-18 Canon Kabushiki Kaisha Magnetischer toner und verfahren zur herstellung von magnetischem toner
US10656545B2 (en) 2018-06-13 2020-05-19 Canon Kabushiki Kaisha Toner and method for producing toner
US10732529B2 (en) 2018-06-13 2020-08-04 Canon Kabushiki Kaisha Positive-charging toner
US10732530B2 (en) 2018-06-13 2020-08-04 Canon Kabushiki Kaisha Toner and method for producing toner
US10859931B2 (en) 2018-06-13 2020-12-08 Canon Kabushiki Kaisha Toner and two-component developer
US10877388B2 (en) 2018-06-13 2020-12-29 Canon Kabushiki Kaisha Toner
US10877389B2 (en) 2018-06-13 2020-12-29 Canon Kabushiki Kaisha Toner
US10969705B2 (en) 2018-06-13 2021-04-06 Canon Kabushiki Kaisha Two-component developer
US11112709B2 (en) 2018-06-13 2021-09-07 Canon Kabushiki Kaisha Toner and toner manufacturing method

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1241530B1 (de) * 2001-03-15 2006-03-22 Canon Kabushiki Kaisha Magnetischer Toner und Prozesskartusche

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6069659A (ja) * 1983-09-27 1985-04-20 Canon Inc マイクロカプセルトナー及びその製造方法
JPS60222864A (ja) * 1984-04-20 1985-11-07 Konishiroku Photo Ind Co Ltd 静電荷像現像用トナ−
EP0380813A1 (de) * 1989-01-31 1990-08-08 Agfa-Gevaert N.V. Trockene elektrophotographische Tonerzusammensetzung
EP0467439A1 (de) * 1990-07-19 1992-01-22 Agfa-Gevaert N.V. Trockne elektrostatografische Entwicklerzusammensetzung
EP0560341A1 (de) * 1992-03-11 1993-09-15 Mitsubishi Chemical Corporation Toner zur Entwicklung elektrostatischer Bilder und dessen Herstellungsverfahren
EP0622688A1 (de) * 1993-04-27 1994-11-02 Kao Corporation Verfahrensmethode zur Herstellung von Bindemittelharzen und Toner für die Elektrophotographie, der diese Bindemittelharze enthält
EP0643337A1 (de) * 1993-08-19 1995-03-15 Mita Industrial Co., Ltd. Toner für ein zwei-komponenten-Typ magnetisches Entwicklungsagenz mit excellentem "Spent"-Widerstand

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6069659A (ja) * 1983-09-27 1985-04-20 Canon Inc マイクロカプセルトナー及びその製造方法
JPS60222864A (ja) * 1984-04-20 1985-11-07 Konishiroku Photo Ind Co Ltd 静電荷像現像用トナ−
EP0380813A1 (de) * 1989-01-31 1990-08-08 Agfa-Gevaert N.V. Trockene elektrophotographische Tonerzusammensetzung
EP0467439A1 (de) * 1990-07-19 1992-01-22 Agfa-Gevaert N.V. Trockne elektrostatografische Entwicklerzusammensetzung
EP0560341A1 (de) * 1992-03-11 1993-09-15 Mitsubishi Chemical Corporation Toner zur Entwicklung elektrostatischer Bilder und dessen Herstellungsverfahren
EP0622688A1 (de) * 1993-04-27 1994-11-02 Kao Corporation Verfahrensmethode zur Herstellung von Bindemittelharzen und Toner für die Elektrophotographie, der diese Bindemittelharze enthält
EP0643337A1 (de) * 1993-08-19 1995-03-15 Mita Industrial Co., Ltd. Toner für ein zwei-komponenten-Typ magnetisches Entwicklungsagenz mit excellentem "Spent"-Widerstand

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 009, no. 207 (P-382), 24 August 1985 & JP-A-60 069659 (CANON KK), 20 April 1985, *
PATENT ABSTRACTS OF JAPAN vol. 010, no. 086 (P-443), 4 April 1986 & JP-A-60 222864 (KONISHIROKU SHASHIN KOGYO KK), 7 November 1985, *

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0869399A3 (de) * 1997-04-04 1999-01-07 Canon Kabushiki Kaisha Toner zur Herstellung von Bildern, Bildherstellungsverfahren, und Wärme-Fixierungsverfahren
EP0869399A2 (de) * 1997-04-04 1998-10-07 Canon Kabushiki Kaisha Toner zur Herstellung von Bildern, Bildherstellungsverfahren, und Wärme-Fixierungsverfahren
US6352808B1 (en) 1999-09-30 2002-03-05 Minolta Co., Ltd. Electrostatic-latent-image developing toner and inorganic particles used for such a toner
US7470498B2 (en) 2003-03-31 2008-12-30 Kanto Denka Kogyo Co., Ltd. Mg-based ferrite, an electrophotographic development carrier containing the ferrite, and a developer containing the carrier
CN105068390B (zh) * 2007-04-10 2020-01-10 施乐公司 具有共价键合的脱模剂的化学调色剂
EP1980914A1 (de) * 2007-04-10 2008-10-15 Xerox Corporation Chemischer Toner mit kovalentem Bindungsfreigabewirkstoff
US7901859B2 (en) 2007-04-10 2011-03-08 Xerox Corporation Chemical toner with covalently bonded release agent
CN105068390A (zh) * 2007-04-10 2015-11-18 施乐公司 具有共价键合的脱模剂的化学调色剂
US10732529B2 (en) 2018-06-13 2020-08-04 Canon Kabushiki Kaisha Positive-charging toner
US10656545B2 (en) 2018-06-13 2020-05-19 Canon Kabushiki Kaisha Toner and method for producing toner
EP3582019A1 (de) * 2018-06-13 2019-12-18 Canon Kabushiki Kaisha Magnetischer toner und verfahren zur herstellung von magnetischem toner
US10732530B2 (en) 2018-06-13 2020-08-04 Canon Kabushiki Kaisha Toner and method for producing toner
US10859931B2 (en) 2018-06-13 2020-12-08 Canon Kabushiki Kaisha Toner and two-component developer
US10877388B2 (en) 2018-06-13 2020-12-29 Canon Kabushiki Kaisha Toner
US10877389B2 (en) 2018-06-13 2020-12-29 Canon Kabushiki Kaisha Toner
US10969704B2 (en) 2018-06-13 2021-04-06 Canon Kabushiki Kaisha Magnetic toner and method for manufacturing magnetic toner
US10969705B2 (en) 2018-06-13 2021-04-06 Canon Kabushiki Kaisha Two-component developer
US11112709B2 (en) 2018-06-13 2021-09-07 Canon Kabushiki Kaisha Toner and toner manufacturing method
US11262666B2 (en) 2018-06-13 2022-03-01 Canon Kabushiki Kaisha Positive-charging toner
US11287758B2 (en) 2018-06-13 2022-03-29 Canon Kabushiki Kaisha Toner and method for producing toner

Also Published As

Publication number Publication date
KR960042242A (ko) 1996-12-21
EP0744668A3 (de) 1997-01-02
CA2177103A1 (en) 1996-11-24

Similar Documents

Publication Publication Date Title
EP0744668A2 (de) Toner für magnetische Zweikomponentenentwickler
EP0703505B1 (de) Toner für Zweikomponentenentwickler
EP0643337B1 (de) Toner für ein zwei-komponenten-Typ magnetisches Entwicklungsagenz mit excellentem "Spent"-Widerstand
EP0703504B1 (de) Toner für Zweikomponentenentwickler
JPH08320595A (ja) 二成分系磁性現像剤用トナー及び現像剤
JPH08328299A (ja) 耐スペント性及び転写効率に優れた二成分系磁性現像剤用トナー及び現像剤
JPH0876444A (ja) 二成分系現像剤
JPH08314194A (ja) 二成分系磁性現像剤用トナー
JPH0876495A (ja) 二成分系現像剤
JPH0876511A (ja) 二成分系現像剤
JPH08320596A (ja) 二成分系磁性現像剤用トナー及び現像剤
JPH0876485A (ja) 二成分系現像剤
JPH0876509A (ja) 二成分系現像剤
JPH07140707A (ja) 二成分系磁性現像剤用トナー
JPH08328301A (ja) 二成分系磁性現像剤用トナー及び現像剤
JPH0876437A (ja) 二成分系現像剤
JPH0876482A (ja) 二成分系現像剤
JPH08320592A (ja) 二成分系磁性現像剤用トナー及び現像剤
JPH0876432A (ja) 二成分系現像剤
JPH0876470A (ja) 二成分系現像剤
JPH0876496A (ja) 二成分系現像剤
JPH0876510A (ja) 二成分系現像剤
JPH0876487A (ja) 二成分系現像剤
JPH0876445A (ja) 二成分系現像剤
JPH0876471A (ja) 二成分系現像剤

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): CH DE FR GB IT LI

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): CH DE FR GB IT LI

17P Request for examination filed

Effective date: 19970701

17Q First examination report despatched

Effective date: 19970827

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19980109