JP2005265961A - Method for forming image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming an image using a magnetic single component toner which can prevent unnecessary toner deposition/residue on a photoreceptor drum, effectively suppress image defects such as black spots and white spots and realizes a high-quality image with high picture quality. <P>SOLUTION: The method for forming an image is carried out by forming an electrostatic latent image on a photoreceptor and developing the electrostatic latent image to form a toner image, wherein the photoreceptor has ≤0.045 μm surface roughness Rz. As for the toner to develop an electrostatic latent image on the photoreceptor, a magnetic single component toner for developing an electrostatic latent image is used which is prepared by externally adding metal soap particles by 0.01 to 1.5 wt.% to toner particles comprising a release agent showing a peak value at 60 to 110°C measured by a differential scanning calorimeter. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming method used in an image forming system using electrophotography such as a copying machine, a facsimile machine, and a laser printer.

In the electrophotographic method, first, the surface of the photosensitive member is uniformly charged to a predetermined polarity, then image exposure by light irradiation is performed based on predetermined document information to form an electrostatic charge image on the surface of the photosensitive member, The charge image is developed to form a toner image, the toner image is transferred to a predetermined sheet, and fixed on the sheet by heating and pressurizing with a fixing roller, thereby forming an image. On the other hand, the photoconductor after the toner image is transferred is prepared for the next image formation by removing the toner remaining on the surface by the cleaning means.
Various apparatuses have been developed as apparatuses for realizing such an image forming method. In particular, in order to cope with environmental problems such as recent energy saving resources, it is strongly required to reduce power consumption. Yes.
As a method for reducing power consumption, methods such as low-temperature fixing, that is, low melting viscosity of a resin used for toner, use of a low melting point wax, and the like have been studied (for example, Patent Documents 1 and 2).

  However, the use of a low melting point wax is effective in improving the low-temperature fixability, but the adhesion of toner particles increases, and for example, a pressing force generated between the surface of the photoreceptor and a cleaning member such as a cleaning blade. In addition, the toner particles are crushed or melted by frictional heat or the like, and adhere to the surface of the photoreceptor, and gradually grow as image formation is repeated. As a result, there is a problem that an image dropout such as a white spot corresponding to the attached portion is generated in a gray or black solid image. In addition, there is a problem that paper dust generated from the paper to be printed adheres to the toner adhering portion and black spots are generated in the margin portion of the image.

Therefore, a method has been proposed in which metal soap particles are added to the toner particles to impart lubricity to the surface of the photoreceptor, and a thin film of metal soap particles is formed to protect the photoreceptor surface ( For example, Patent Documents 1 and 2). By such a method, it is possible to prevent the toner particles from adhering to the surface of the photoreceptor and to easily peel the toner particles with a cleaning blade or the like.
Japanese Patent Publication No. 8-33681 Japanese Examined Patent Publication No. 3-69110

However, according to the study of the present inventor, in particular, in an image forming method using a magnetic one-component toner using a low melting point wax, the addition of the metal soap particles can sufficiently adhere the toner to the surface of the photoreceptor. It was found that it cannot be prevented.
In particular, when the present inventors use metal soap particles that sufficiently prevent the toner from adhering to the surface of the photoreceptor, the chargeability of the magnetic one-component toner is adversely affected. It has been found that there may be a new problem that the image density of the toner is lowered or that the toner adheres to the margin of the image. That is, as compared with the two-component toner used in combination with the carrier, the one-component toner has a poor charging property and is easily affected by the addition of metal soap particles.

  The present invention has been made in view of the above problems, and prevents unnecessary toner adhesion / remaining on the photosensitive drum to effectively suppress image defects such as black spots or white spots, as well as high image quality and high quality. An object is to provide an image forming method using a magnetic one-component toner capable of realizing an image.

In the image forming method using a magnetic one-component toner, the present inventor prevents the toner from adhering to the surface of the photoreceptor while satisfying the recent demand for low-temperature fixing, and does not cause a decrease in image density or fogging. As a result of diligent research on a method for forming a high-quality image, toner particles capable of achieving low-temperature fixing, and a photoconductor having a predetermined surface roughness as a photoconductor for forming a toner image with the toner particles The present inventors have newly found out that an excellent effect can be exhibited by using in combination, and the present invention has been completed.
That is, according to the image forming method using the magnetic one-component toner of the present invention, an electrostatic latent image is formed on a photoreceptor, and the electrostatic latent image is developed to form a toner image. The photosensitive member has a surface roughness Rz of 0.045 μm or less, and a peak value measured by a differential scanning calorimeter as a toner for developing an electrostatic latent image on the photosensitive member is 60 to 110 ° C. A magnetic one-component toner for developing an electrostatic latent image in which metal soap particles are externally added in an amount of 0.01 to 1.5% by weight based on toner particles is used for toner particles containing a release agent. To do.
Moreover, it is preferable to use what is surface-treated with a silane compound as a metal soap particle.

According to the image forming method using the magnetic one-component toner of the present invention, by using a combination of a toner that can be fixed at a low temperature and a photoreceptor having a very smooth surface, unnecessary toner adhesion / Residuals can be prevented, and image defects such as black spots or white spots can be effectively suppressed. As a result, high-quality and high-quality images can be realized. In addition, the external addition of metal soap particles forms a thin film of metal soap particles on the surface of the photoconductor, and the surface of the photoconductor can be protected, so that the smoothness of the surface of the photoconductor can be further improved. It is possible to effectively prevent the particles from remaining on the surface of the photoconductor, and further facilitate the separation of the toner particles by the cleaning means, thereby forming a high-quality and high-quality toner image such as dot image reproducibility. Is possible.
Furthermore, by setting the amount of the metal soap particles within a predetermined range, the effect of the metal soap particles themselves can be effectively exhibited without adversely affecting the charging characteristics of the magnetic one-component toner.
In addition, when using metal soap particles that have been surface-treated with a silane compound, the chargeability of the magnetic one-component toner can be adjusted, and a high-quality, high-quality toner image can be formed more effectively. Can do.

  The magnetic one-component toner that can be used in the image forming method of the present invention usually comprises toner particles containing a binder resin, magnetic powder, and a release agent. The toner is formed by externally adding metal soap particles and optionally an external additive. In addition, a toner compounding agent such as a positive charge control agent may be further dispersed in the toner as necessary.

The binder resin is not particularly limited, and examples thereof include styrene resins, acrylic resins, styrene-acrylic copolymer resins, polyolefin resins such as polyethylene and polypropylene, vinyl chloride resins, and polyester resins. Thermoplastic resins such as polyamide resins, polyurethane resins, polyvinyl alcohol resins, vinyl ether resins, N-vinyl resins, styrene-butadiene resins are used.
In the present invention, among the above thermoplastic resins, styrene resins, styrene-acrylic copolymer resins, and polyester resins are preferable.

  Styrenic resins and styrene-acrylic copolymer resins are styrene homopolymers and copolymers with other copolymerizable monomers copolymerizable with styrene. As copolymerizable monomers, p-chlorostyrene; vinyl naphthalene; ethylene unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; vinyl halides such as vinyl chloride, vinyl bromide, and vinyl fluoride; vinyl acetate, propion Vinyl esters such as vinyl acrylate, vinyl benzoate, vinyl butyrate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, acrylic (Meth) acrylic acid esters such as phenyl acid, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate; other acrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide; Vinyl ethers such as rumethyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidene, etc. N-vinyl compounds of These copolymerization monomers can be used alone or in combination of two or more with a styrene monomer.

Moreover, as a polyester-type resin, what is obtained by the condensation polymerization of a polyhydric alcohol component and a polyhydric carboxylic acid component and copolycondensation polymerization can be used.
Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1, Diols such as 5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; bisphenol A, hydrogenated bisphenol A, polyoxyethylene Bisphenols such as bisphenol A, polyoxypropylene bisphenol A; sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, Pentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, tri Examples of trihydric or higher alcohols such as methylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

  Examples of the polyvalent carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, Divalent carboxylic acids such as malonic acid; n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid Alkyl or alkenyl esters of divalent carboxylic acids such as isododecyl succinic acid and isododecenyl succinic acid; 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid, 2 , 5,7-Naphthalenetricarboxylic acid, 1,2,4-naphthalenetri Rubonic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, Examples thereof include trivalent or higher carboxylic acids such as tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empole trimer acid. In addition, anhydrides of the above divalent or trivalent or higher carboxylic acids can also be used.

The softening point of the binder resin measured with the Koka flow tester is preferably in the range of 110 to 150 ° C, more preferably 120 to 140 ° C. Further, the glass transition point (Tg) is within a range of 55 to 70 ° C. in order to fuse the obtained toners and prevent a decrease in storage stability and to secure toner fixing properties. preferable. In addition, the glass transition point of binder resin can be calculated | required from the change point of specific heat using a differential scanning calorimeter (DSC).
In the present invention, the binder resin described above preferably has a molecular weight that exhibits a predetermined fixing property and offset resistance depending on the type of resin used. This is because if the molecular weight is higher than necessary, the fixing property is impaired, and if the molecular weight is low, the offset resistance is unsatisfactory.

In addition, in order to improve offset resistance and increase toner strength, the binder resin may be partially crosslinked by using a crosslinking agent or a thermosetting resin in combination with the above-described thermoplastic resin as necessary. A structure may be introduced.
The cross-linking agent as described above varies depending on the type of thermoplastic resin used, for example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene, bifunctional carboxylic acid esters such as ethylene glycol di (meth) acrylate, Examples thereof include vinyl compounds having 2 or 3 or more vinyl groups such as divinyl ether.
As thermosetting resins, bisphenol A type epoxy resins, hydrogenated bisphenol A type epoxy resins, novolac type epoxy resins, polyalkylene ether type epoxy resins, cycloaliphatic type epoxy resins, and cyanate resins are used. It can be used singly or in combination of two or more.

The magnetic one-component toner that can be used in the image forming method of the present invention contains magnetic powder. As a result, the magnetic toner can be supplied to the developing area by using magnetic force alone without using a magnetic carrier or the like.
As the magnetic powder, a known powder can be used. For example, ferromagnetic iron oxides such as triiron tetroxide (Fe ₃ O ₄ ) and iron sesquioxide (γ-Fe ₂ O ₃ ), iron oxide zinc (ZnFe ₂ O ₄ ), iron yttrium oxide (Y ₃ Fe ₅ O _12), cadmium oxide (CdFe ₂ O _4), iron oxide gadolinium _{(Gd 3 Fe 5 O 12)} , oxidized iron-copper (CuFe ₂ O _4), oxidation Tetsunamari _(PbFe 12 _{O 19),} iron oxide neodymium Ferrites such as (NdFeO ₃ ), iron barium oxide (BaFe ₁₂ O ₁₉ ), iron manganese oxide (MnFe ₂ O ₄ ), iron lanthanum oxide (LaFeO ₃ ), or a composite thereof, or iron powder (Fe), Ferromagnetic metals or alloys such as cobalt powder (Co) and nickel powder (Ni) can be used alone or in combination. For example, manganese-magnesium ferrite, nickel-zinc ferrite, copper-zinc ferrite, lithium ferrite and the like can be mentioned. The particle shape of the magnetic powder is not particularly limited, and may be any shape such as a spherical shape, a cubic shape, or an indefinite shape. The average particle size of the magnetic powder is preferably from 0.1 to 1 μm, particularly preferably in a fine powder state within the range of 0.1 to 0.5 μm. Further, the magnetic powder may be used after being subjected to a surface treatment with a surface treatment agent such as a titanium coupling agent or a silane coupling agent.
The magnetic powder is suitably 50 to 100 parts by weight per 100 parts by weight of the binder resin.

In the magnetic one-component toner that can be used in the image forming method of the present invention, a release agent such as waxes is dispersed and blended in the binder resin in order to improve the fixing property and the offset property. As the release agent, those having an endothermic peak value measured by a differential scanning calorimeter within a range of 60 to 110 ° C. are suitable. The peak value means a temperature indicating an endothermic peak in the DSC curve of the toner at the time of temperature rise measured by a differential scanning calorimeter (that is, toner particles mixed with the release agent). Therefore, it is necessary to select and use a release agent such that the endothermic peak value of the toner particles containing the release agent is in the range of 60 to 110 ° C.
When the endothermic peak value of the toner particles is less than 60 ° C., toner adhesion occurs on the surface of the photoreceptor, and when it exceeds 110 ° C., fixability particularly at a low temperature is deteriorated.

  Such waxes are not particularly limited, and examples thereof include polyethylene wax, polypropylene wax, Teflon wax, Fischer-Tropsch wax, paraffin wax, ester wax, montan wax, rice wax, carnauba wax, and the like. Can be mentioned. Of these, Fischer-Tropsch wax, ester wax, carnauba wax and the like are preferable.

Fischer-Tropsch wax is a synthetic wax produced using the Fischer-Tropsch reaction, which is a catalytic hydrogenation reaction of carbon monoxide, and is a straight-chain hydrocarbon compound with few iso (iso) structure molecules and side chains. As such Fischer-Tropsch wax, Sazol wax C1 (endothermic peak value: 106.5 ° C.), Sazol wax C105 (endothermic peak value: 102.1 ° C.) available from Sazol, Sazol wax SPRAY (endothermic) Peak value: 102.1 ° C.).
Two or more of these waxes may be used in combination, and in that case, the wax may appear at two or more locations within the above-described range. By adding such a wax, offset property and image smearing can be more efficiently prevented.
It is appropriate that the release agent is usually blended in an amount of 2.0 to 5.0 parts by weight per 100 parts by weight of the binder resin.

  The magnetic one-component toner used in the present invention remarkably improves the charge level and the charge rise characteristic (an index indicating whether the charge is charged to a constant charge level in a short time), and has characteristics such as excellent durability and stability. In order to obtain it, you may mix | blend a charge control agent.

  The charge control agent, for example, as a positive charge control agent, pyridazine, pyrimidine, pyrazine, orthooxazine, metaoxazine, paraoxazine, orthothiazine, metathiazine, parathiazine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,4-oxadiazine, 1,3,4-oxadiazine, 1,2,6-oxadiazine, 1,3,4-thiadiazine, 1,3,5-thiadiazine, 1, 2,3,4-tetrazine, 1,2,4,5-tetrazine, 1,2,3,5-tetrazine, 1,2,4,6-oxatriazine, 1,3,4,5-oxatriazine, Azine compounds such as phthalazine, quinazoline, quinoxaline; azine fast red FC, azine fast red 12BK, azine violet BO, Direct dyes composed of azine compounds such as gin brown 3G, azine light brown GR, azine dark green BH / C, azine deep black EW and azine deep black 3RL; nigrosine compounds such as nigrosine, nigrosine salt, nigrosine derivatives; nigrosine BK, nigrosine Examples include acid dyes composed of nigrosine compounds such as NB and nigrosine Z; metal salts of naphthenic acid or higher fatty acids; alkoxylated amines; alkylamides; quaternary ammonium salts such as benzylmethylhexyldecylammonium and decyltrimethylammonium chloride. These may be used alone or in combination of two or more. In particular, the nigrosine compound is optimal from the viewpoint of obtaining a quicker start-up property.

  Further, a resin or oligomer having a quaternary ammonium salt, a resin or oligomer having a carboxylate, a resin or oligomer having a carboxyl group, or the like can also be used as a positively chargeable charge control agent. More specifically, polystyrene resin having quaternary ammonium salt, acrylic resin having quaternary ammonium salt, styrene-acrylic resin having quaternary ammonium salt, polyester resin having quaternary ammonium salt, carboxylic acid Polystyrene resin with salt, acrylic resin with carboxylate, styrene-acrylic resin with carboxylate, polyester resin with carboxylate, polystyrene resin with carboxyl group, acrylic with carboxyl group 1 type, or 2 or more types, such as resin, the styrene-acrylic resin which has a carboxyl group, and the polyester-type resin which has a carboxyl group, are mentioned. In particular, a styrene-acrylic resin (styrene-acrylic copolymer) having a quaternary ammonium salt, a carboxylate or a carboxyl group as a functional group can easily adjust the charge amount to a value within a desired range. It is optimal from the point of view.

  In this case, preferred acrylic comonomers in the styrene-acrylic resin or acrylic resin itself are methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, acrylic Examples include (meth) acrylic acid alkyl esters such as iso-butyl acid, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, and iso-butyl methacrylate. As the quaternary ammonium salt, a unit derived from a dialkylaminoalkyl (meth) acrylate through a quaternization step is used.

Examples of the derived dialkylaminoalkyl (meth) acrylate include di (amino) ethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, dibutylaminoethyl (meth) acrylate and the like ( Lower alkyl) aminoethyl (meth) acrylate; dimethylmethacrylamide, dimethylaminopropylmethacrylamide are preferred. Further, hydroxy group-containing polymerizable monomers such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and N-methylol (meth) acrylamide can be used in combination during polymerization.
The charge control agent is suitably blended in an amount of 1 to 4 parts by weight per 100 parts by weight of the binder resin.

  In the present invention, the magnetic one-component toner is classified into a classification method, a kneading and pulverizing method, a pulverizing and classifying or kneading and pulverizing method, a spheroidizing method by heat treatment or mechanical impact force, a melt granulating method, a spray granulating method, For example, suspension method, suspension polymerization method, emulsion polymerization method, dispersion polymerization method, interfacial polymerization method, seed polymerization method, etc.), dissolution suspension method (for example, see JP-A-11-52619), phase inversion emulsification method (For example, refer to JP-A-4-303849 and JP-A-5-66600) and the like. Among them, a method of preparing by mixing a binder resin and various compounding agents, melt-kneading using an extruder, etc., further pulverizing, and classifying to have the above-described particle size distribution, manufacturing equipment, and production The wet granulation method is preferable, and the suspension polymerization method and the emulsion polymerization method are more preferable in consideration of the properties, the circularity described above can be easily realized, and the like. Specifically, as a suspension polymerization method, a monomer solution in which a colorant and optionally an additive are dispersed is suspended in a dispersed particle size in a solvent incompatible with this solution, and the monomer is polymerized in a suspended state. Examples thereof include a method for obtaining a toner, and a method for polymerizing monomers in micelles as emulsion polymerization. The central particle size and sphericity of the toner are the heat treatment temperature or timing in the production process, the magnitude or timing of applied force (mechanical impact force, rotation speed of stirring, rotation speed, etc.), the type of raw material, etc. It can be adjusted by appropriately selecting and combining various production conditions.

  The magnetic one-component toner particles are, for example, volume-based average particles in consideration of forming a high-quality, high-quality toner image such as the reproducibility of dots and fine line images while ensuring the image density of the formed image. It is appropriate that the diameter is about 6.0 to 10.0 μm. In consideration of obtaining a higher quality image combined with the toner form, for example, the apparent bulk density is suitably about 0.35 to 0.55 g / cc.

  Metal soap particles are externally added to the magnetic monocomponent toner particles that can be used in the image forming method of the present invention. As the metal soap particles, metal soaps such as fatty acids, resin acids, naphthenic acids, for example, metal salts of higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid (for example, zinc, calcium, magnesium, aluminum, manganese, Copper, iron, cobalt salts, etc.) are suitable. A metal salt of a higher fatty acid having 15 or more carbon atoms is preferred, and zinc stearate is more preferred. In consideration of preventing toner particles from adhering to the surface of the photoreceptor, the metal soap particles preferably have, for example, a number-based average particle size in the range of about 0.1 to 10.0 μm.

The external addition amount of the metal soap particles needs to be 0.01 to 1.5% by weight with respect to the toner particles. When the external addition amount is less than 0.01% by weight, toner adhesion occurs on the surface of the photoreceptor, and when it exceeds 1.5% by weight, the charging characteristics of the toner are deteriorated, resulting in a decrease in image density and an increase in fog density. Will occur.
In the external addition process, toner particles and metal soap particles are put into a stirring mixer (Henschel mixer, Nauter mixer, V-type mixer, turbula mixer, hybridizer, ang mill, etc.), mixed and stirred in a dry manner. Can be done by. At this time, it is preferable that the metal soap particles are not embedded in the toner particles.
The metal soap particles are preferably surface-treated with a silane compound. Thereby, the chargeability of the toner particles can be adjusted, and a higher quality image can be obtained.

Examples of the silane compound include an alkylsilane compound, a fluorine silane compound, and an aminosilane compound.
As the alkylsilane compound, silicon has at least one or two alkyl groups having 1 to 10 carbon atoms, preferably 4 to 8 carbon atoms (for example, methyl, ethyl, propyl, isobutyl, hexyl, octyl groups, etc.). Three, four substituted compounds are mentioned. A plurality of substituted alkyl groups may be the same or all may be different. When there are 3 or less alkyl groups, a hydrogen atom, a monovalent organic group (for example, an alkenyl group such as alkoxy, vinyl and allyl, an aryl group such as phenyl and naphthyl, an aralkyl group such as benzyl and phenylethyl, etc.) May be substituted with one or more of silicon.

  The fluorine silane compound may be one in which one or more fluorine atoms are directly substituted on silicon. Further, the above-described alkylsilane compound may be a compound in which one or more fluorine atoms are substituted on the silicon substituent. Examples of the substituent in this case include a perfluoroalkyl group such as perfluoropropyl. When there are three or less fluorine atoms or substituents containing fluorine atoms, one or more hydrogen atoms and monovalent organic groups may be substituted with silicon as described above.

  The aminosilane compound may be one in which one or more amino groups are directly substituted on silicon. Moreover, the compound by which one or more amino groups were substituted by the substituent to the silicon of the alkylsilane compound mentioned above may be sufficient. Examples of the substituent in this case include an aminoalkyl group such as γ-aminopropyl. When the number of amino groups or substituents containing an amino group is 3 or less, one or more hydrogen atoms and monovalent organic groups may be substituted with silicon as described above.

The surface treatment can be performed by mixing and stirring the metal soap particles and the silane compound in a dry manner using a Henschel mixer as described above. At this time, it is preferable that the silane compound is not embedded in the metal soap particles.
The surface treatment of the metal soap particles with the silane compound is preferably performed at 5 to 100 parts by weight, more preferably 50 to 80 parts by weight, per 100 parts by weight of the metal soap particles.

  In addition to the metal soap particles, the toner particles include inorganic fine particles such as colloidal silica, hydrophobic silica, alumina, titanium oxide, zinc oxide, magnesium oxide, and calcium carbonate (normally an average particle size of 0.3 μm), if necessary. The following may be externally added in combination with one or more surface treatment agents such as organic fine powders such as polymethyl methacrylate. Thereby, the fluidity and storage stability of the toner can be improved. When fine particles such as alumina and titanium oxide are externally added, the adhesion force of the toner to the surface of the photoreceptor can be reduced, or the surface of the photoreceptor can be polished appropriately. Such a surface treatment agent is preferably used in an amount of 2.0 parts by weight or less per 100 parts by weight of toner particles. The external addition of these surface treatment agents can be performed in the same manner as described above.

In the image forming method of the present invention for forming a toner image, the developing method uses an electrostatic induction developing method using a magnetic one-component developer, a jumping developing method, a BMT developing method, and a non-magnetic one-component developer. Various methods such as a fur brush developing method, a pressure developing method, an NSP developing method, a cascade developing method using a two-component developer, and a magnetic brush developing method can be used. Further, it may be regular development or reversal development. In particular, from the viewpoint of obtaining a high-quality image, a reversal development method and a jumping development method are preferable, and a combination thereof is more preferable.
For example, the magnetic one-component toner is supplied onto a developing sleeve with a built-in magnet in a state of being triboelectrically charged to the positive polarity, and is developed by being conveyed and supplied to the developing area. The toner is triboelectrically charged by frictional contact between the magnetic blade and the toner.

The photoconductor on which an electrostatic latent image is to be formed is not particularly limited as long as the surface roughness is 0.045 μm or less, but among these, an organic photoconductor is preferably used.
As a method for adjusting the surface roughness of the photoreceptor, for example, in the case of an organic photoreceptor, the type and / or amount of the charge transport material contained in the photosensitive layer, the type and molecular weight of the resin constituting the photosensitive layer, Addition and type and / or amount of a solvent used for forming a photoconductor, leveling agent (for example, silicon oil) that functions to smooth the surface of the photosensitive layer, and heat drying conditions (temperature, time, etc.) after coating the photosensitive layer ), Etc., are appropriately selected and adjusted. The surface roughness Rz of the photoreceptor surface means a ten-point average roughness (Rz) defined in JIS B0601-1994.
In forming an image, first, the surface of the photoreceptor is uniformly charged. The main charging potential on the surface of the photoconductor at this time can be about +700 V in the case of an organic photoconductor, for example. The main charging can be performed by any means using a corona charger or a charging roller.

Next, light such as laser light is irradiated based on predetermined image information to form an electrostatic latent image on the surface of the photoreceptor. By this image exposure, the portion irradiated with light becomes a low potential.
The electrostatic latent image formed as described above is reversely developed with the developer containing the positively charged toner described above. In other words, a positively charged toner adheres to a portion that is at a low potential when irradiated with light, whereby a toner image is formed.

In such development, a developing bias voltage is applied between the developer supply side (developing sleeve) and the photosensitive member. As the developing bias voltage (potential applied to the developing sleeve), for example, an alternating bias potential in which a DC potential of 250 to 350 V and an AC potential of 0.5 to 2.0 KV (amplitude) are reduced can be applied. The frequency of the alternating potential can be set to about 1 to 5 Hz, for example.
The toner image formed on the surface of the photoreceptor by such development is transferred onto a predetermined sheet by a transfer unit. As the transfer means, any of a transfer roller, a transfer belt, and a corona charger can be used.

By applying a negative transfer bias potential to the transfer roller or the transfer belt, an electric field is generated between the toner image and the transfer unit, and the surface of the paper passing between the photosensitive member and the transfer unit is applied to the transfer roller or transfer belt. The toner image can be transferred.
Further, the corona charger can corona charge the back surface of the paper to a negative polarity and transfer the toner image onto the paper surface by the generated electric field. In this case, an AC corona charger for paper separation is preferably used in combination with a corona charger for transfer. The paper on which the toner image has been transferred has its back surface charged to a negative polarity, so the paper must be separated from the positively charged photoreceptor surface, and this separation is facilitated by AC corona charging. .
The paper on which the toner image has been transferred is introduced into a fixing device comprising a pair of a heat roller (fixing roller) and a pressure roller, and is fixed on the paper surface by heat and pressure. On the other hand, the surface of the photoconductor after the toner image is transferred is cleaned by a cleaning device such as a cleaning blade or a fur brush, and the toner remaining on the surface of the photoconductor is removed. One cycle of image formation is completed, and the next image formation is performed.

The image forming method of the present invention will be described in detail below based on examples.
Examples 1-4 and Comparative Examples 1-4
<Synthesis of binder resin for toner>
A monomer solution composed of 70 parts by weight of styrene and 30 parts by weight of butyl acrylate was added to 6 parts by weight of a polymerization initiator V-65 (2,2-azobis- (2,4-dimethylvaleronitrile), manufactured by Wako Pure Chemical Industries, Ltd.). The solution was added dropwise to a solution containing 200 parts by weight of toluene as a solvent (condenser was provided and toluene was refluxed) over 3 hours, and polymerization was carried out for 12 hours while maintaining the temperature at 60 ° C. Thereafter, toluene was distilled off under reduced pressure to obtain a binder resin (styrene-acrylic resin).

<Manufacture of magnetic one-component toner>
100 parts by weight of styrene-acrylic resin (binder resin, manufactured by Sanyo Chemical Industries), 90.0 parts by weight of magnetic powder (EPT-1000, manufactured by Toda Kogyo), nigrosine dye (charge control agent, manufactured by Orient Chemical Industries, N-01) ) 5.0 parts by weight of the wax shown in Table 1 was charged into a Henschel mixer 20B (Mitsui Mining Co., Ltd.) and mixed at 2500 rpm for 5 minutes.
Further, the mixture was kneaded with a twin-screw kneader (PCM-30, manufactured by Ikegai Co., Ltd.) at 200 rpm, a cylinder temperature of 120 ° C., and an input amount of 6 kg / hour. Next, the drum flaker (made by Mitsui Mining Co., Ltd.) was used, and it cooled by 140 mm / sec and plate | board thickness 3-4mm.
Then, it grind | pulverized with the turbo mill (T-250 type, the turbo industry company make), and classified with the Alpine classifier.
The obtained toner is made of 0.8% by weight of silica (external additive, manufactured by Wacker, H2050EP), 0.8% by weight of titanium oxide (external additive, manufactured by Titanium Industry Co., Ltd., STT-65C), zinc stearate ( Metal soap particles (manufactured by Nippon Oil & Fats Co., Ltd., zinc stearate S) are added to a Henschel mixer 20B (Mitsui Mining Co., Ltd.) so as to have the amount shown in Table 1, and mixed at 2500 rpm for 3 minutes. Each toner shown was made.
Note that the DSC peak value of the toner was raised from a differential scanning calorimeter “DSC3210” manufactured by Mac Science Co., Ltd. to a temperature increase rate of 15 ° C./min from room temperature to 200 ° C., cooled to 25 ° C., and increased again. It is a temperature that shows an endothermic peak of a DSC curve obtained by raising the temperature at a temperature rate of 15 ° C./min and measuring the amount of heat at this time.

<Manufacture of organic photoreceptor A>
X-type metal-free phthalocyanine (PcH ₂ ) 2.5 parts by weight as a charge generating agent, 30 parts by weight of the following compound (HTM) as a hole transporting agent, 30 parts by weight of the following compound (ETM) as an electron transporting agent, shown below 100 parts by weight of copolymer polycarbonate resin having a weight average molecular weight of 120,000 (Resin, molar copolymerization ratio m: n = 80.0 mol%: 20.0 mol%) is dispersed and dissolved in a ball mill for 24 hours together with 700 parts by weight of tetrahydrofuran. Thus, a coating solution for a single-layer type photosensitive layer was prepared.
The obtained coating solution was applied on an aluminum base tube as a support by a dip coating method, dried with hot air at 120 ° C. for 40 minutes, the surface roughness was adjusted to 0.015 μm, and a film thickness of 29.29. A single layer type photoreceptor having a single photosensitive layer of 0 μm was prepared.

The surface roughness of the photoconductor was measured using a universal surface shape measuring instrument SE-3H manufactured by Kosaka Laboratory.
The surface roughness was 0.043 μm (organic photoreceptor B) or 0.051 μm (organic photoreceptor C) by the same method as that of organic photoreceptor A, except that the hole transporting agent was 65 parts by weight or 100 parts by weight. A single-layer type photoreceptor having a single photosensitive layer was prepared.
Surface roughness was obtained in the same manner as for the organic photoreceptor A except that a copolymer polycarbonate resin having a weight average molecular weight of 50,000 (Resin, molar copolymerization ratio m: n = 80.0 mol%: 20.0 mol%) was used. Produced an organic photoreceptor D having a single photosensitive layer of 0.048 μm.
A single photosensitive layer having a surface roughness of 0.046 μm was formed in the same manner as for the organic photoreceptor A except that the photosensitive layer coating solution was applied onto an aluminum base tube and dried with hot air at 150 ° C. for 20 minutes. An organic photoreceptor E was prepared.

<Evaluation of toner adhesion>
Using a Kyocera Mita multi-function machine (KM-2050) of a magnetic one-component jumping development system equipped with the single-layered organic photoreceptor obtained above using each toner, an all-black solid image of A3 paper was converted to 10,000. Print a sheet of paper, compare the 10,000th black solid image with the initial image (first black solid image), and if a white spot-like image defect is observed, evaluate that the toner is attached. X. In addition, when no image defect was observed, the evaluation was given as “Good” because no toner adhered. The toner image forming conditions are shown below.
Charging potential: + 700V
Development method: Reversal development Development bias: DC + 200V to + 400V
AC 0.25KV ~ 2.5KV
Frequency 2.0KHz

<Image evaluation>
For each toner, an image for density measurement was output under the same toner image formation conditions by the above-mentioned Kyocera Mita multifunction machine (KM-2050). The image density (ID) is A4 size paper, the short side direction of the paper is the paper conveyance direction, the measurement image is three 3 × 3 cm solid image portions on the paper, and the paper in the center in the paper conveyance direction. Those arranged vertically at intervals of 10 cm with respect to the transport direction were used. Five points were measured for one solid image, and an average value of five images was obtained. Further, the fog density (FD) was measured at five non-printed portions of the sheet on which the above measurement image was printed, and the average value of the five sheets was obtained. A reflection densitometer (model number TC-6D manufactured by Tokyo Denshoku Co., Ltd.) was used for measurement of image density and fog density. The evaluation criteria are an image density of 1.300 or more and a fog density of 0.008 or less.
These evaluation results are shown in Table 2.

From the results of Table 2, in Examples 1 to 4, metal soap particles were added, and image forming apparatuses using magnetic one-component toner having a peak value measured by a differential scanning calorimeter in the range of 60 to 110 ° C. Since the surface roughness of the photoreceptor is 0.045 μm or less, unnecessary toner adhesion / remaining on the photoreceptor drum can be prevented, and image defects such as black spots or white spots can be effectively suppressed. At the same time, there was no problem in image density and fog density. In particular, in Example 4, although a DSC peak value of 62 ° C. and an external addition amount of zinc stearate of 0.01% by weight are used, a magnetic one-component toner that is extremely susceptible to toner adhesion is used. There was no toner adhesion.
On the other hand, in Comparative Examples 1, 5, and 6, although the metal soap particles were added and the toner having a peak value measured by a differential scanning calorimeter within the range of 60 to 110 ° C. was used, Since the surface roughness of the body was rough (greater than 0.045 μm), toner adhesion occurred and image defects such as black spots or white spots were observed.

Further, in Comparative Examples 2 and 3, a toner in which metal soap particles are added and a peak value measured by a differential scanning calorimeter is in the range of 60 to 110 ° C. is used. Is using a rough organic photoreceptor. However, although the amount of external addition of the metal soap particles was increased, toner adhesion did not occur, but the image density decreased and image fogging increased.
In Comparative Example 4, although the metal soap particles are added, a toner whose peak value measured by a differential scanning calorimeter is outside the range of 60 to 110 ° C. (smaller than 60 ° C.) is used. Even if the surface roughness of the toner was small, toner adhesion occurred and image defects such as black spots or white spots were observed.
From the above experimental results, the surface roughness Rz of the photoconductor, the peak value measured by the differential scanning calorimeter of the magnetic monocomponent toner used in combination with the photoconductor, the metal soap particles added to the magnetic monocomponent toner It has been clarified that by setting the external addition amount within a specific range, an image forming method that satisfies the image density and the image fog and does not adhere to the surface of the photoreceptor can be obtained.

  The present invention can be applied to an image forming apparatus using a wide range of magnetic one-component toner, such as a laser printer, an electrostatic copying machine, a plain paper facsimile apparatus, and a composite apparatus having these functions.

Claims (2)

An image forming method of forming an electrostatic latent image on a photoreceptor and developing the electrostatic latent image to form a toner image,
The photosensitive member has a surface roughness Rz of 0.045 [mu] m or less, and has a peak value measured by a differential scanning calorimeter of 60 to 110 [deg.] C. as a toner for developing an electrostatic latent image on the photosensitive member. A magnetic one-component toner for developing an electrostatic latent image in which metal soap particles are added in an amount of 0.01 to 1.5% by weight based on toner particles to toner particles containing an agent. Forming method. The image forming method according to claim 1, wherein the metal soap particles are surface-treated with a silane compound.