JP2005215257A - Image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method by which glossiness, angle dependency of gloss, deformation and color deviation of dots, and color gamut can be satisfied. <P>SOLUTION: In the image forming method using a fixing device with which a toner image is fixed under a higher fixing pressure on the paper ejection side than on the paper feed side, the toner image is formed with a toner satisfying the following conditions (a) and (b); (a) wax whose domain diameter is 0.05-0.25 μm is contained 1.5-26.0% on a number basis, (b) wax whose domain diameter is 0.31-1.22 μm is contained 18.6-99.8% on a number basis. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming method using an oilless toner, and more particularly to an image forming method for forming a color image using a toner having a distribution of wax domain diameters.

  Full-color image forming methods in electrophotography were mostly used for color photocopying and design companies. However, in recent years, there has been an increasing number of cases where color multifunction machines that also serve as color printers and color copiers are introduced into offices. The background of this is the business of planning documents and reports, etc. by connecting each personal computer and a color multifunction device over the network as the cost of the equipment is reduced, miniaturized, speeded up, and IT is progressing in the office. One of the reasons is that documents are now output on color multifunction devices.

  From the viewpoint of such an office printer, development of an apparatus capable of saving energy and responding to quick start has been studied, and a fixing method using a belt for the fixing unit has been proposed as one means for achieving this problem. (For example, refer to Patent Document 1). Since this fixing method has a structure capable of providing a large fixing nip, it is an effective method for melting and deforming toner, and promotes speeding up of image formation.

  In addition, with the advent of so-called oilless toners in which wax is added to toner particles to provide release performance, oilless color machines that do not have the trouble of supplying oil to devices have become widespread. Then, an image forming apparatus capable of saving energy and increasing speed by using an oilless toner in which the content of wax and the size of the dispersion diameter are controlled and the above fixing method has appeared (for example, see Patent Documents 2 and 3).

  The color images created by the color image forming apparatuses described in these documents are mainly finished with reduced gloss, but they have high gloss on the user side and are faithful in color reproducibility. There has been a strong demand for a color image capable of expressing the above.

  However, although high gloss image formation was attempted through the fixing device, it was found that it was very difficult to uniformly form a wax layer on the toner image. As a result, it was possible to obtain only a color image having a non-uniform finish with unevenness in which good glossiness was exhibited on the color image and a region having low glossiness was mixed. In addition, the belt-shaped pressure member that forms the fixing device rotates with the rotation of the heating roller, causing vibrations that cause the dots of the unfixed toner image on the recording sheet to be deformed or color-shifted. I let you.

Thus, the advent of an image forming apparatus that creates a color image that satisfies the user's needs and that has high glossiness without unevenness and no color misregistration and exhibits good color reproducibility has been awaited.
JP-A-9-120225 Japanese Patent Application Laid-Open No. 11-133776 JP 2001-356625 A

  An object of the present invention is to provide an image forming method that can satisfy glossiness, gloss angle dependency, dot deformation and color shift, and color gamut.

  The present inventor has studied to solve the above problems from the viewpoint of toner design. In order to develop glossiness uniformly on the toner image, it was studied to make the thickness of the wax layer formed on the toner image uniform. In particular, the fixing device disclosed in the above-mentioned patent document paid attention to variations in the fixing pressure at the nip portion formed by the fixing roller and the belt-like pressure member. And after repeated investigations, we focus on the wax domain diameter in the toner and speculate that wax leaching can be controlled according to the fixing pressure by giving a distribution to the size of the domain diameter. After further studies, the present invention has been found. That is, the object of the present invention is achieved by any of the configurations described below.

  Probably, this mechanism probably causes the wax leached from the large domain to be squeezed by the action of a large fixing pressure in the vicinity of the discharge part, but the leaching of wax from the small domain forms a wax layer. As a result of acting as a finishing step, it is presumed that the wax in the toner was sufficiently leached out of the toner to form a wax layer having no thickness or unevenness.

  Furthermore, by increasing the pressure applied to the fixing pressure member and the fixing heating member of the fixing device locally near the exit of the nip, it becomes difficult to form a gap due to the thickness between the recording medium and the toner layer. Dependence, dot deformation and prevention of color shift, and color gamut can be satisfied.

  In addition, it was not initially expected that the configuration of the present invention could suppress the occurrence of vibration caused by the rotation of the belt-like pressure member to the fixing roller in the fixing device. Is presumed that a wax layer having a uniform thickness is formed on the toner image and lubrication is imparted between the fixing roller and the pressure belt by the presence of the wax layer, thereby suppressing the occurrence of rotation. However, I don't know the actual situation.

  Although the mechanism is not clear, the conveyance force of the recording medium is stabilized by adhering to the surface of the polyimide fixing member together with the wax.

  The object of the present invention is achieved by the following configurations.

(Claim 1)
In an image forming method using a fixing device that fixes a toner image by setting a fixing pressure on a paper discharge side to be stronger than that on a paper supply side, the toner image is a toner that satisfies the following conditions (a) and (b): An image forming method characterized in that the image forming method is used.
(A) A wax having a domain diameter of 0.05 to 0.25 μm is contained in an amount of 1.5 to 26.0% based on the number.
(B) 18.6 to 99.8% of wax having a domain diameter of 0.31 to 1.22 μm is contained on a number basis.

(Claim 2)
2. The image forming method according to claim 1, wherein the fixing pressure on the paper discharge side is maximized in the vicinity of an exit of a nip formed by the fixing pressure member and the fixing heating member.

(Claim 3)
The image forming method according to claim 1, wherein the toner includes toner particles having a polyester domain.

(Claim 4)
The image forming method according to claim 1, wherein the image forming method is performed using a toner having the following properties (a) to (c).
(A) The average value of circularity is 0.979-0.996
(B) The volume average particle size is 4.4 to 9.8 μm.
(C) An endothermic peak measured by DSC is present at 58 to 73 ° C., and the endothermic amount is 12.6 to 24.5 J / mg.

(Claim 5)
The image forming method according to claim 1, wherein the image forming method performs toner image formation by a non-magnetic one-component developing method.

  The image forming method of the present invention has excellent effects that can satisfy glossiness, angle dependency of glossiness, dot deformation and color shift, and color gamut.

  As a result of intensive studies, the present inventors have found that the wax in the domain having a domain diameter of 05 to 0.25 μm is 1.5 to 26.0% on the number basis and the wax in the domain having a domain diameter of 0.31 to 1.22 μm. When the image is formed by combining a toner containing 18.6 to 99.8% on the basis of the number of toner and a fixing device having a strong fixing pressure (hereinafter also referred to as nip pressure) on the paper discharge side, the glossiness and gloss angle The present inventors have found that it is possible to satisfy dependency, dot deformation and color shift, and color gamut.

  Further, it was confirmed that the toner used in the present invention is preferably a chemical toner that can easily control the wax domain diameter and distribution, the average value of circularity, the volume average particle diameter, the endothermic peak and the endothermic amount.

  The method for producing the chemical toner is not particularly limited, and examples thereof include a method in which resin particles are formed by an emulsion polymerization method and the toner particles are assembled to produce a toner, and a method in which a toner is produced by suspension polymerization. A specific example of a production method in which resin particles are formed by an emulsion polymerization method and the resin particles are associated will be described later.

  The toner used in the present invention contains a resin component, a wax component, and a colorant component in the toner particles.

  Polyester is preferably used as the wax component because it is easy to satisfy glossiness, angle dependency of glossiness, dot deformation and color shift, color gamut, and the like.

  The domain diameter and distribution of the wax in the toner particles can be controlled by the dispersion and temperature conditions when dispersing the wax component, the association conditions when associating, and the like.

  Next, a method for measuring the wax domain diameter and the like will be described.

<Wax domain diameter>
As a method for measuring the domain diameter (number average) of the wax, toner particles are embedded in a resin, and a section having a thickness of about 0.2 μm is prepared with a microtome. This section was photographed with a transmission electron microscope at a negative magnification of 280 times, and stretched to create a photograph at 1200 times. The domain diameter is measured with an image analysis apparatus “SPICCA” (manufactured by Nippon Avionics Co., Ltd.). Here, 500 or more domains are measured, a number-based histogram is created with the wax domain diameter (Ferret diameter) on the horizontal axis, and the number falling within the range of (a) and (b) of claim 1 is obtained.

<Average value of circularity of toner particles>
In the present invention, the degree of circularity of toner particles can be measured by “FPIA-1000” (manufactured by Sysmec). At this time, the equivalent circle diameter is defined by the following equation.

Equivalent circle diameter = 2 × (projected area of particle / π) ^1/2
<Volume average particle diameter of toner>
In the present invention, the volume average particle diameter of the toner is a value obtained by calculating the volume average particle diameter by using “SD-2000” (manufactured by Sysmec), measuring the volume of the toner having an orifice diameter of 30 μm, and having a diameter of 1 μm or more. .

<Endothermic peak and endothermic amount measured by DSC of toner>
In the present invention, the endothermic peak temperature and the endothermic amount are values obtained by measuring the toner with a “differential thermal analyzer” (DSC). The DSC curve is measured according to ASTM D3418-8. In the present invention, the temperature at the main maximum peak point in the obtained DSC curve is referred to as the endothermic peak temperature.

  Specifically, for example, a differential thermal analyzer “DSC-7” (manufactured by Perkin Elmer) is used for the measurement. The temperature correction of the device detection unit uses the endothermic peaks of indium and zinc, and the correction of heat quantity uses the heat of fusion of indium. The sample is an aluminum pan, an empty pan is set for the control, and the heating rate is 10 ° C./min.

  Next, the wax used for the toner according to the present invention will be described.

  The wax used in the present invention is particularly limited as long as it acts so that the toner exhibits an endothermic peak at 58 to 73 ° C. when the toner is measured with “DSC-7” or the like as described above. Is not to be done.

  The content of the wax constituting the toner according to the present invention is usually 1 to 30% by mass, preferably 2 to 20% by mass, and more preferably 3 to 15% by mass.

  Preferred waxes include ester compounds represented by the following general formula.

General formula
R _1- (OCO-R ₂ ) n
In the formula, n represents an integer of 1 to 4, preferably 2 to 4, more preferably 3 to 4, and particularly preferably 4.

R ₁ and R ₂ represent a hydrocarbon group which may have a substituent.

R ₁ : carbon number = 1-40, preferably 1-20, more preferably 2-5
R ₂ : carbon number = 1-40, preferably 16-30, more preferably 18-26
Specific examples of the ester compound represented by the above general formula are shown below. Among them, the toner has a melting point such as behenyl behenate, stearyl stearate, etc., that causes the toner to exhibit an endothermic peak between 58-73 ° C. Those are preferred.

  Next, a toner manufacturing method according to the present invention will be described.

  The toner according to the present invention is preferably a toner obtained by polymerizing at least a polymerizable monomer in an aqueous medium, and is preferably a toner obtained by associating at least resin particles in an aqueous medium. preferable. That is, the polymer is emulsion-polymerized in a suspension polymerization method or in a liquid (in an aqueous medium) to which an emulsion of necessary additives is added to prepare fine polymer particles (resin particles). And a method of producing the resin particles by associating them by adding an organic solvent, a flocculant and the like. Here, “association” means that a plurality of the resin particles are fused, and includes a case where the resin particles and other particles (for example, colorant particles) are fused.

  The method for producing the toner particles according to the present invention is not particularly limited. Specifically, the resin particles are formed by an emulsion polymerization method, and the resin particles are assembled to form a toner particle dispersion or suspension polymerization method. And a method for preparing a toner particle dispersion liquid. For example, it contains a release agent formed through multistage polymerization as disclosed in JP-A-2002-49180 and JP-A-2002-131978. A method for producing toner particles by salting out / fusing the resulting resin particles in an aqueous medium (coagulation of the resin particles and disappearance of the interface between the resin particles simultaneously), as disclosed in JP-A-2000-131877 After the colorant particle dispersion and the release agent particle dispersion are mixed in the resin particle dispersion prepared by emulsion polymerization to form aggregated particles, the aggregated particles are heated and fused to produce toner particles. Way It is below.

  As described above, the toner particles according to the present invention are produced through the polymerization process after introducing the raw material into the aqueous medium and then through the aging step.

  Further, the toner particles are solid-liquid separated from the toner particle dispersion liquid containing the toner particles obtained in the above step to produce a toner cake, and the water cake is removed from the toner cake to remove deposits such as surfactants. I do. Examples of the solid-liquid separation method include a centrifugal separation method using a rotating cylindrical dehydrator and the like, a vacuum filtration method using a Nutsche and the like, a filter press method, and the like. Of these, solid-liquid separation by centrifugation is preferred.

  The toner cake subjected to the water washing treatment is dried to become toner. The drying method is not particularly limited, but vacuum drying is preferred. Examples of the vacuum dryer include, but are not limited to, a vacuum spray dryer, a vacuum freeze dryer, and a vacuum dryer. Specifically, it is preferable to use a stationary shelf dryer, a movable shelf dryer, a fluidized bed dryer, a rotary dryer, a stirring dryer, or the like that can be decompressed.

  The toner used in the present invention is produced through the above steps.

  A polymerizable monomer which is a resin material constituting the toner used in the present invention will be described.

(1) Hydrophobic monomer As a hydrophobic monomer which comprises a monomer component, it does not specifically limit and a conventionally well-known monomer can be used. Moreover, it can be used combining 1 type (s) or 2 or more types so that the required characteristic may be satisfy | filled.

  Specifically, monovinyl aromatic monomers, (meth) acrylic acid ester monomers, vinyl ester monomers, vinyl ether monomers, monoolefin monomers, diolefin monomers , Halogenated olefin monomers and the like can be used.

  Examples of vinyl aromatic monomers include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, p-ethyl styrene, p. -N-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2, Examples thereof include styrene monomers such as 4-dimethylstyrene and 3,4-dichlorostyrene and derivatives thereof.

  Examples of acrylic monomers include acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, methyl methacrylate, methacrylic acid. Examples include butyl acid, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and the like. Examples of vinyl ester monomers include vinyl acetate, vinyl propionate, and vinyl benzoate. Examples of the vinyl ether monomer include vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl phenyl ether and the like.

  Examples of the monoolefin monomer include ethylene, propylene, isobutylene, 1-butene, 1-pentene, 4-methyl-1-pentene and the like. Examples of the diolefin monomer include butadiene, isoprene, chloroprene and the like.

(2) Crosslinkable monomer A crosslinkable monomer may be added to improve the properties of the resin particles. Examples of the crosslinkable monomer include those having two or more unsaturated bonds such as divinylbenzene, divinylnaphthalene, divinyl ether, diethylene glycol methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and diallyl phthalate.

(3) Monomer having an acidic polar group Monomers having an acidic polar group include (a) an α, β-ethylenically unsaturated compound having a carboxyl group (—COOH) and (b) a sulfone group (— Mention may be made of α, β-ethylenically unsaturated compounds having SO ₃ H).

Examples of the α, β-ethylenically unsaturated compound (a) having a —COO group include acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid, maleic acid monobutyl ester, maleic acid. Examples thereof include acid monooctyl esters and metal salts thereof such as Na and Zn. (B) Examples of α, β-ethylenically unsaturated compounds having a sulfo group (—SO ₃ H group) include sulfonated styrene, its Na salt, allylsulfosuccinic acid, allylsulfosuccinic acid octyl, its Na salt and the like. Can be mentioned.

  The initiator (also referred to as polymerization initiator) used for the polymerization of the polymerizable monomer according to the present invention will be described.

  The polymerization initiator used in the present invention can be appropriately used as long as it is water-soluble. For example, persulfates (potassium persulfate, ammonium persulfate, etc.), azo compounds (4,4′-azobis-4-cyanovaleric acid and its salts, 2,2′-azobis (2-amidinopropane) salts, etc.), Examples thereof include peroxide compounds such as hydrogen peroxide and benzoyl peroxide. Furthermore, the said polymerization initiator can be combined with a reducing agent as needed to make a redox initiator. By using a redox initiator, the polymerization activity is increased, the polymerization temperature can be lowered, and the polymerization time can be further shortened.

  The polymerization temperature may be any temperature as long as it is equal to or higher than the lowest radical generation temperature of the polymerization initiator. For example, a range of 50 ° C. to 80 ° C. is used. It is also possible to polymerize at or near room temperature by using a polymerization initiator that starts at room temperature, for example, a combination of hydrogen peroxide-reducing agent (such as ascorbic acid).

  The chain transfer agent used in the present invention will be described.

  In the present invention, conventionally known generally used chain transfer agents can be used for the purpose of adjusting the molecular weight of the resin particles produced by polymerization of the polymerizable monomer.

  The chain transfer agent is not particularly limited. In particular, a compound having a mercapto group is preferably used because a toner having a sharp molecular weight distribution can be obtained and storage stability, fixing strength, and offset resistance are excellent. For example, a compound having a mercapto group such as octanethiol, dodecanethiol, and tert-dodecanethiol is used. Preferred examples include ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, decyl thioglycolate, thioglycol Examples include dodecyl acid, thioglycolic acid ester of ethylene glycol, thioglycolic acid ester of neopentyl glycol, and thioglycolic acid ester of pentaerythritol. Among these, n-octyl-3-mercaptopropionic acid ester is preferably used from the viewpoint of suppressing odor during toner heat fixing.

  Next, the colorant, internal additive, and external additive used in the toner according to the present invention will be described.

《Colorant》
The colorant relating to each of the four colors of yellow (Y), magenta (M), cyan (C), and black (Bk) used in the present invention is manufactured from the viewpoint of improving the toner charging uniformity. At the time of salting out, agglomerating and fusing the composite resin particles, it is preferably salted out, agglomerated and fused together with the resin particles and contained in the toner particles.

  Examples of the colorant used in the toner according to the present invention (colorant particles used for salting out, agglomeration, and fusion with composite resin particles) include various inorganic pigments, organic pigments, dyes, and the like. Examples of inorganic pigments include conventionally known black pigments and magnetic powders.

  Examples of the black pigment used for the preparation of the black toner include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and examples of the magnetic powder include magnetite and ferrite.

  These inorganic pigments can be used alone or in combination as required. The content of the inorganic pigment in the toner is preferably in the range of 2 to 20% by mass, more preferably in the range of 3 to 15% by mass.

  When used as a magnetic toner, the above-mentioned magnetite can be added. In this case, from the viewpoint of imparting predetermined magnetic properties, the content in the toner is preferably 20 to 120% by mass.

  Conventionally known organic pigments and dyes can also be used. Specific organic pigments and dyes are exemplified below.

  Examples of organic pigments for magenta or red used for preparing magenta toner include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of organic pigments for orange or yellow used for the preparation of yellow toner include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment yellow 155, C.I. I. And CI Pigment Yellow 156.

  Examples of organic pigments for green or cyan used for preparing cyan toner include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  As the dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95 and the like. These dyes may be used alone or as a mixture of a plurality of dyes.

  Furthermore, these organic pigments and dyes can be used alone or in combination as desired. The content of the organic pigment or dye in the toner is preferably in the range of 2 to 20% by mass, more preferably in the range of 3 to 15% by mass.

  The colorant (colorant particles) used in the present invention may be surface-modified. As the surface modifier, conventionally known ones can be used, and specifically, silane coupling agents, titanium coupling agents, aluminum coupling agents and the like can be preferably used.

  Silane coupling agents include: methyltrimethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane, alkoxysilane such as diphenyldimethoxysilane, siloxane such as hexamethyldisiloxane, γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, Vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-ureidopropyltri An ethoxysilane etc. are mentioned.

  Examples of titanium coupling agents include TTS, 9S, 38S, 41B, 46B, 55, 138S, and 238S, which are commercially available under the trade name “Plenact” manufactured by Ajinomoto Co., Inc., and commercial products A manufactured by Nippon Soda Co., Ltd. -1, B-1, TOT, TST, TAA, TAT, TLA, TOG, TBSTA, A-10, TBT, B-2, B-4, B-7, B-10, TBSTA-400, TTS, TOA -30, TSDMA, TTAB, TTOP and the like.

  Examples of the aluminum coupling agent include “Plenact AL-M” manufactured by Ajinomoto Co., Inc.

  The addition amount of these surface modifiers is preferably in the range of 0.01 to 20% by mass, more preferably 0.1 to 5% by mass with respect to the colorant.

  Examples of the method for modifying the surface of the colorant particles include a method in which a surface modifier is added to the dispersion of the colorant particles and this system is heated to react. The surface-modified colorant particles are collected by filtration, washed with the same solvent and filtered, and then dried.

《Internal additive》
The toner according to the present invention may contain an internal additive other than wax such as a charge control agent. Examples of the charge control agent contained in the toner include nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts or metal complexes thereof. Can be mentioned.

<External additive>
As the toner according to the present invention, the toner prepared above may be used as it is, but it is preferable to add a so-called external additive for the purpose of improving fluidity and cleaning properties. . These external additives are not particularly limited, and various inorganic fine particles, organic fine particles and lubricants can be used.

  Examples of inorganic fine particles that can be used as an external additive include conventionally known fine particles. Specifically, silica fine particles, titanium oxide fine particles, alumina fine particles and the like can be preferably used. These inorganic fine particles are preferably hydrophobic.

  Specific examples of the silica fine particles include commercially available products R-805, R-976, R-974, R-972, R-812, R-809 manufactured by Nippon Aerosil Co., Ltd., HVK-2150, H manufactured by Hoechst Co., Ltd. -200, commercially available products TS-720, TS-530, TS-610, H-5, MS-5, spherical monodispersed silica manufactured by Cabot Corporation.

  Specific examples of the titanium oxide fine particles include, for example, commercial products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., and commercial products MT-100S, MT-100B, MT-500BS, MT-600 manufactured by Teika Co., Ltd. MT-600SS, JA-1 etc. are mentioned.

  Specific examples of the titanium oxide fine particles include commercial products TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T manufactured by Fuji Titanium Co., Ltd., and commercial products IT-S, IT manufactured by Idemitsu Kosan Co., Ltd. -OA, IT-OB, IT-OC, rutile type titanium oxide and the like.

  Specific examples of the alumina fine particles include commercial products RFY-C and C-604 manufactured by Nippon Aerosil Co., Ltd., and commercial products TTO-55 manufactured by Ishihara Sangyo Co., Ltd.

  Examples of the organic fine particles that can be used as the external additive include spherical fine particles having a number average primary particle diameter of about 10 to 2000 nm. Examples of the constituent material of the organic fine particles include polystyrene, polymethyl methacrylate, styrene-methyl methacrylate copolymer and the like.

  Examples of the lubricant that can be used as an external additive include metal salts of higher fatty acids. Specific examples of such higher fatty acid metal salts include: stearic acid metal salts such as zinc stearate, aluminum stearate, copper stearate, magnesium stearate, calcium stearate; zinc oleate, manganese oleate, iron oleate, olein Oleic acid metal salts such as acid copper and magnesium oleate; palmitate metal salts such as zinc palmitate, copper palmitate, magnesium palmitate and calcium palmitate; linoleic acid metal salts such as zinc linoleate and calcium linoleate; ricinol Examples include ricinoleic acid metal salts such as zinc acid and calcium ricinoleate.

  The addition amount of the external additive is preferably about 0.1 to 5% by mass with respect to the toner.

  Examples of the apparatus for adding and mixing the external additive to the toner include various known mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer.

  Next, the fixing device used in the present invention will be described.

  FIG. 1 is a cross-sectional configuration diagram showing an example of a form of a fixing device used in the present invention.

  In FIG. 1, a fixing roller 100, an endless belt 110, a pressure pad (pressure member) 120 a that is pressed against the fixing roller 100 via the endless belt 110, a pressure pad (pressure member) 120 b, and the lubricant supply member 400. The main part is composed.

  The fixing roller 100 includes a metal core (cylindrical metal core) 100a and a heat-resistant elastic body layer 100b and a release layer (heat-resistant resin layer) 100c formed around the core 100a. A halogen lamp 140 is disposed as a heating source. The temperature of the surface of the fixing roller 100 is measured by the temperature sensor 150, and the halogen lamp 140 is feedback-controlled by a temperature controller (not shown) based on the measurement signal, so that the surface of the fixing roller 100 is adjusted to a constant temperature. The endless belt 110 is in contact with the fixing roll 100 so as to be wound at a predetermined angle to form a nip portion.

  Inside the endless belt 110, a pressure pad 120 having a low friction layer on its surface is disposed in a state of being pressed against the fixing roller 100 via the endless belt 110. The pressure pad 120 is provided with a pressure pad 120a to which a strong nip pressure is applied and a pressure pad 120b to which a weak nip pressure is applied, and is held by a holder 120c made of metal or the like.

  Further, a belt traveling guide is attached to the holder 120c so that the endless belt 110 can smoothly slide and rotate. The belt traveling guide is preferably a member having a low coefficient of friction because it rubs against the inner surface of the endless belt 110, and a member having low heat conduction is preferable so that heat is not easily taken from the endless belt 110.

  The fixing roller 100 is rotated in the direction of arrow D by a motor (not shown), and the endless belt 110 is also rotated by this rotation. The toner image 170 is transferred onto the recording medium S by a transfer device (not shown), and the recording medium 160 is conveyed from the right side of the drawing toward the nip portion (in the direction of arrow C). The toner image 170 on the recording medium S inserted through the nip portion is fixed by the pressure acting on the nip portion and the heat applied through the fixing roller 100 by the halogen lamp 140. If fixing is performed by the apparatus having the configuration shown in FIG. 1, a wide nip portion can be taken, so that stable fixing performance can be ensured.

  The recording medium S after fixing is peeled off satisfactorily without being wound around the fixing roller 100 due to both effects of the release layer 100c and the distortion at the nip portion. It is desirable to provide the peeling means 200 downstream of the nip portion. The peeling unit 200 is configured to be held by a guide 200b in a state where the peeling sheet 200a is in contact with the fixing roller 100 in a direction opposite to the rotation direction of the fixing roller 100 (reverse).

  Hereinafter, each configuration will be described in detail. As the core 100a, a metal cylinder having high thermal conductivity such as iron, aluminum, and stainless steel can be used. Regarding the outer diameter and thickness of the core 100a, since the pressing force of the pressure pad 120 is small in the fixing device used in the present invention, one having a small diameter or one having a thin wall can be used. In this case, an outer diameter of about 20 to 35 mm and a thickness of about 0.3 to 0.5 mm can be used. Of course, since the strength and thermal conductivity differ depending on the material used, the optimum dimensions may be determined as appropriate.

  Any material can be used for the heat resistant elastic layer 100b formed on the surface of the core 100a as long as it is an elastic body having high heat resistance. In particular, it is preferable to use an elastic body such as rubber or elastomer having a rubber hardness of about 25 to 40 ° (JIS-A), and specific examples include silicone rubber and fluorine rubber. The thickness of the heat-resistant elastic layer 100b is preferably about 0.3 to 1.0 mm, although it depends on the rubber hardness of the material used.

  In the fixing device used in the present invention, a wide nip portion provides sufficient fixing performance, and effective releasability can be obtained with a small amount of distortion, so that the total load by the pressure pad 120 is small. In addition, the heat-resistant elastic layer 100b can be thinned. As described above, the fixing device used in the present invention can reduce the outer diameter of the core 100a, reduce the thickness, and reduce the thickness of the heat-resistant elastic layer 100b formed on the surface of the core 100a. Compared with the roll-pair type fixing device of this type, the heat capacity is extremely low, the instant start property is improved, and / or the output of the halogen lamp 140 as a heating source can be reduced, and between the inner surface and the outer surface of the fixing roller 100 The thermal resistance can be reduced and the thermal response is accelerated. Therefore, power consumption can be reduced and faster fixing can be achieved.

  As the release layer (heat resistant resin layer) 100c formed on the heat resistant elastic layer 100b, any resin may be used as long as it is a heat resistant resin. For example, a fluorine resin, a silicone resin, or the like may be used. Can be mentioned. It is particularly preferable to use a fluororesin considering the releasability and wear of the release layer 100c. As the fluororesin, fluororesins such as PFA (perfluoroalkyl vinyl ether copolymer resin), PTFE (polytetrafluoroethylene), FEP (tetrafluoroethylene hexafluoropropylene copolymer resin) can be used. PFA is optimal from the viewpoints of workability and workability. The thickness of the release layer 100c is preferably 5 to 30 μm, more preferably 10 to 20 μm. If the thickness of the release layer 100c is less than 5 μm, wrinkles based on the distortion of the fixing roller 10 may occur, and if it exceeds 30 μm, the release layer 100c becomes hard and image quality defects such as uneven gloss are caused. May appear, both are undesirable. As a method for forming the release layer 100c, any conventionally known method can be employed, and examples thereof include a dip coating method, a spray coating method, a roll coating method, a bar coating method, and a spin coating method.

  The endless belt 110 is preferably composed of a base layer and a release layer coated on the surface thereof (the surface in contact with the fixing roll 100 or both surfaces). The base layer is selected from polyimide, polyamide, polyamideimide and the like, and the thickness thereof is preferably about 50 to 125 μm, more preferably about 75 to 100 μm. The release layer formed on the surface of the base layer is preferably a layer coated with a fluororesin such as PFA having a thickness of 5 to 20 μm as described above.

  The winding angle of the endless belt 110 around the fixing roll 100 is preferably about 20 to 45 ° so as to ensure a sufficiently wide nip portion, although it depends on the rotation speed of the fixing roll 100. Also, the due time of the nip portion (recording medium insertion time) is 30 msec. In particular, 50 to 70 msec. It is preferable to set the wrapping angle to a degree. As described above, by using the endless belt 110 that can follow and follow the shape of the fixing roll 100, the width of the nip portion can be widened, and the toner fixing property and releasability can be improved. it can.

  As a basic configuration of the pressure pad 120, a pressure pad 120a having a weak nip pressure for securing a wide nip portion is provided on the inlet side of the nip portion, and a pressure pad for obtaining a strong nip pressure with the fixing roller 100. 120b is disposed on the exit side of the nip portion. Further, in order to reduce the sliding resistance between the inner peripheral surface of the endless belt 120 and the pressure pad 120, a low friction layer is provided on the surfaces of the pressure pad 120a and the pressure pad 120b that are in contact with the endless belt 120. The nip member 120b is made of the same material as 120b.

  In the present invention, a lubricant may be applied between the surface of the pressure pad 120 and the inner surface of the endless belt 110. For example, silicone oil, fluorine oil, grease or the like is used. This lubricant is applied to the inner surface of the belt. However, since there is a possibility that the lubricant travels around the endless belt 110 and adheres to the fixing roll, it is desirable to have a releasability. Furthermore, silicone oil is preferable to fluorine oil in view of safety issues.

  Examples of the silicone oil include dimethyl silicone oil, amino-modified silicone oil, carboxy-modified silicone oil, silanol-modified silicone oil, and sulfonic acid-modified silicone oil. Among these, amino-modified silicone oil having a viscosity of 500 to 10000 cs is preferable in that the starting torque and driving torque of the image fixing device can be effectively maintained in a desired low range, and the handleability is excellent. Although the lubricant is not consumed, it may wrap around as described above when used for a long period of time, and may gradually decrease and eventually be exhausted. At this time, the torque increases. Therefore, the present invention includes the lubricant supply member 400 that holds and supplies the lubricant corresponding to the life of the fixing device so that the lubricant does not run out.

  The lubricant holding member 410 of the lubricant supply member 400 preferably has a large number of continuous pores, has heat resistance at the fixing temperature and has an appropriate elastic modulus, and examples thereof include felts and sponges. The lubricant permeation restriction film 42 of the lubricant supply member 40 has a large number of continuous pores, has heat resistance at a fixing temperature and a small friction coefficient, for example, has heat resistance and a friction coefficient. A film obtained by stretching and molding a small resin is preferable, and a film obtained by stretching and molding a fluororesin is preferable.

  The lubricant holding member 410 is impregnated with a lubricant, and the lubricant permeation amount regulating film 420 of the lubricant supply member 400 is in contact with almost the entire region in the axial direction of the endless belt. Then, when the endless belt 110 rotates, the lubricant is supplied to the entire inner peripheral surface of the endless belt 110. The supply amount of the lubricant does not need to be large, and therefore, the contact pressure of the lubricant supply member 400 with respect to the endless belt 110 is small and may be finely contacted.

  It is important to continue supplying a minute amount of the lubricant to the inner peripheral surface of the endless belt 110 over a long period of time. The amount of lubricant supplied to the inner peripheral surface of the endless belt 110 regulates the amount of lubricant permeated through the lubricant permeation amount regulating film 420 by changing the porosity of the porous lubricant permeation amount regulating membrane 420. To do.

  In the lubricant supply member 400, it is desirable that the amount of lubricant supplied near the center in the axial direction of the endless belt 110 is larger than the amount of lubricant supplied near the end in the axial direction of the endless belt 110. This is because the contact width of the lubricant supply member 400 near the center of the endless belt 110 is wider than the end, or the contact pressure of the lubricant supply member 400 near the center is stronger than the end. It is possible by doing. The supply amount is increased by making the contact width of the central portion of the lubricant supply member 400 wider than the end portion. This affects wrinkles when the endless belt 110 rotates. If the belt speed at the center is higher than the end speed, the belt does not wrinkle. However, if the belt speed at the center is lower than the end speed, the belt tends to wrinkle. Therefore, by making the supply amount of the lubricant larger in the central portion than in the end portion, the central portion of the belt can easily travel and wrinkles are prevented.

  The lubricant supply member 400 is attached to the outer surface of the belt traveling guide and is in weak contact with the inner peripheral surface of the endless belt 110. The lubricant supply member 400 is disposed in the vicinity of the nip entrance. On the nip portion entrance side, a force that presses the belt against the traveling guide by the rotation of the endless belt 110 acts, and therefore, by providing the lubricant supply member 400 here, the belt can be pressed without escaping.

  FIG. 2 shows the result of examining the belt nip pressure distribution of the fixing device shown in FIG.

  As shown in FIG. 2, it can be seen that the pressure distribution in the belt nip is weak on the paper feed side (inlet side) of the pressure roll and strong on the discharge side (outlet side). This makes it difficult to form a gap due to the thickness between the recording medium and the toner layer, and can satisfy the angle dependency of gloss, the occurrence of dot deformation and color misregistration, and the color gamut.

  A polyimide resin is preferably used as a belt material of the endless belt 110 constituting the fixing device used in the present invention.

Examples of such polyimide resins include polypyromellitic acid imide resin materials such as Kapton HA manufactured by DuPont, and polybiphenyltetracarboxylic acid imide resin materials such as Upilex S manufactured by Ube Industries, Ltd. Polybenzophenone tetracarboxylic imide acid resin materials such as Upilex R manufactured by Ube Industries, Ltd. and LARC-TPI (thermoplastic polyimide resin) manufactured by Mitsui Toatsu Chemicals, Inc. can be exemplified. All of them have a Young's modulus of 3430 N / mm ² or more, and can satisfy the mechanical properties as a belt substrate with a thickness of 70 to 100 μm.

  A polyimide resin is generally a polymer synthesized by condensation polymerization using tetracarboxylic dianhydride and diamine or diisocyanate as monomer components. Examples of the tetracarboxylic acid component of the dianhydride include pyromellitic acid, naphthalene-1,4,5,8-tetracarboxylic acid, naphthalene-2,3,6,7-tetracarboxylic acid, 2,3,5, 6-biphenyltetracarboxylic acid, 2,2 ', 3,3'-biphenyltetracarboxylic acid, 3,3', 4,4'-biphenyltetracarboxylic acid, 3,3 ', 4,4'-diphenyl ether tetracarboxylic acid Acid, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic acid, 3,3 ′, 4,4′-azobenzenetetracarboxylic acid, bis ( 2,3-dicarboxyphenyl) methane, bis (3,4-dicarboxyphenyl) methane, β, β-bis (3,4-dicarboxyphenyl) propane, β, β-bis (3,4 Radical Po hydroxyphenyl) hex-off Oro propane.

  Examples of the diamine component include m-phenyldiamine, p-phenyldiamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 2,4-diaminochlorobenzene, m-xylylenediamine, p-xylylenediamine, 1, 4-diaminonaphthalene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4'-diaminonaphthalebiphenyl, benzidine, 3,3-dimethylbenzidine, 3,3'-dimethoxybenzidine, 3,4 ' -Diaminodiphenyl ether, 4,4'-diaminodiphenyl ether (oxy-p, p'-dianiline; ODA), 4,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophenone, 4,4'-diaminophenyl sulfone, 4,4'-diaminoazobenzene, 4,4'-diamy Diphenylmethane, beta, beta-bis (4-amine phenyl) propane. The compound which substituted the amino group in the above-mentioned diamine component made into the said isocyanate component with the isocyanate group is mentioned. Commercially available products of these polyimides include, for example, pyromellitic acid-based polyimide (Kapton HA: manufactured by DuPont) having diamine as a diamine component, and 3,3 ′, 4,4′-biphenyltetracarboxylic acid-based polyimide (Upilex S: Ube Industries, Ltd.).

  In addition, the polyimide resin used in the present invention satisfies, for example, the relational expression between the Young's modulus and the amount of displacement of the belt due to the load at the time of driving the belt described in Japanese Patent Laid-Open No. 2000-338778, or It may have a contact angle with a water droplet disclosed in Japanese Patent No. -231684 and a mechanical property of surface resistivity.

  The toner according to the present invention can be used as a non-magnetic one-component developer or a two-component developer mixed with a carrier, but is preferably used as a non-magnetic one-component developer.

  Next, an image forming apparatus used in the image forming method of the present invention will be described.

  The image forming method of the present invention is performed using an image forming apparatus equipped with the fixing device. The image forming method can be developed by either a non-magnetic one-component development method or a two-component development method, but it is preferable to employ a non-magnetic one-component development method.

  FIG. 3 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus that forms a full-color image equipped with the fixing device of FIG.

  In FIG. 3, an organic photosensitive drum 10 (hereinafter referred to as “photosensitive member 10”) that is rotationally driven in the direction of arrow a in the drawing, a laser scanning optical system 20, a full-color developing device 30, and a rotational drive in the direction of arrow b in the drawing. The endless intermediate transfer belt 40 and a paper feed unit 60 are included. Around the photoreceptor 10, a cleaner 12 including a charging brush 11 that charges the surface of the photoreceptor 10 to a predetermined potential and a cleaner blade 12 a that removes toner remaining on the photoreceptor 10 is provided.

  The laser scanning optical system 20 is a well-known one incorporating a laser diode, a polygon mirror, and an fθ optical element, and its control unit prints for each of cyan (C), magenta (M), yellow (Y), and black (Bk). Data is transferred from the host computer. The laser scanning optical system 20 sequentially outputs print data for each color as a laser beam, and scans and exposes the photosensitive member 10. Thereby, an electrostatic latent image for each color is sequentially formed on the photoreceptor 10.

  The full-color developing device 30 is an integrated unit of four color developing devices 31C, 31M, 31Y, and 31Bk containing a one-component developer made of non-magnetic toners of C, M, Y, and Bk. It can rotate clockwise as a fulcrum. Each developing device includes a developing sleeve 32 and a toner regulating blade 34. The toner conveyed by the rotation of the developing sleeve 32 is charged by passing through a pressure contact portion (regulating portion) between the blade 34 and the developing sleeve 32.

  The intermediate transfer belt 40 is stretched endlessly on support rollers 41 and 42 and tension rollers 43 and 44 and is driven to rotate in the direction of arrow b in the figure in synchronization with the photosensitive member 10. A projection (not shown) is provided on a side portion of the intermediate transfer belt 40, and the microswitch 45 detects the projection to control image forming processes such as exposure, development, and transfer. The intermediate transfer belt 40 is pressed by a rotatable primary transfer roller 46 and is in contact with the photoreceptor 10. This contact portion is the primary transfer portion T1. The intermediate transfer belt 40 is in contact with a rotatable secondary transfer roller 47 at a portion supported by the support roller 42. This contact portion is the secondary transfer portion T2.

  Further, a cleaner 50 is installed in the space between the developing device 30 and the intermediate transfer belt 40. The cleaner 50 has a blade 51 for removing residual toner on the intermediate transfer belt 40. The blade 51 and the secondary transfer roller 47 can be brought into contact with and separated from the intermediate transfer belt 40.

  The paper feed unit 60 includes a paper feed tray 61 that can be opened to the front side of the image forming apparatus main body 1, a paper feed roller 62, and a timing roller 63. The recording medium S is stacked on the paper feed tray 61, fed one sheet at a time by the rotation of the paper feed roller 62, and synchronized with the image formed on the intermediate transfer belt 40 by the timing roller 63. To the secondary transfer section. The recording sheet horizontal conveyance path 65 includes an air suction belt 66 including the paper feeding unit, and a vertical conveyance path 71 including conveyance rollers 72, 73, and 74 is provided from the fixing device 70. The recording medium S is discharged from the vertical conveyance path 71 to the upper surface of the image forming apparatus main body 1.

  Here, the printing operation of the full-color printer will be described. When the printing operation is started, the photoconductor 10 and the intermediate transfer belt 40 are rotationally driven at the same peripheral speed, and the photoconductor 10 is charged to a predetermined potential by the charging brush 11.

  Subsequently, a cyan image is exposed by the laser scanning optical system 20, and an electrostatic latent image of the cyan image is formed on the photoreceptor 10. The electrostatic latent image is immediately developed by the developing device 31C, and the toner image is transferred onto the intermediate transfer belt 40 at the primary transfer portion. Immediately after the completion of the primary transfer, the developing device 31M is switched to the developing portion D, and then magenta image exposure, development, and primary transfer are performed. Further, switching to the developing device 31Y, yellow image exposure, development, and primary transfer are performed. Further, switching to the developing device 31Bk, black image exposure, development, and primary transfer are performed, and the toner image is superimposed on the intermediate transfer belt 40 for each primary transfer.

  When the final primary transfer is completed, the recording medium S is sent to the secondary transfer portion, and the full-color toner image formed on the intermediate transfer belt 40 is transferred onto the recording medium S. When the secondary transfer is completed, the recording medium S is conveyed to the fixing device 70, and the full color toner image is fixed on the recording medium S and discharged onto the upper surface of the printer main body 1.

In the image formation, the toner adhesion amount on the solid image portion on the recording sheet is based on the photoreceptor surface potential of −550 V, the development bias voltage of −200 V, the primary transfer bias voltage of 900 V, and the secondary transfer bias voltage of 500 V. The setting was performed under the conditions of 0.7 mg / cm ² and a fixing temperature of 160 ° C.

The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited to these examples.
<Manufacture of toner>
<Toner particle dispersion 1>
(Preparation of resin particle dispersion A)
A solution obtained by mixing 588 g of styrene, 160 g of n-butyl acrylate, 52 g of methacrylic acid, and 8 g of n-octanethiol is dissolved in 10 g of anionic surfactant “Emar 27C” (manufactured by Kao Corporation) in 2700 g of ion-exchanged water. The emulsion was polymerized in a reaction vessel, and 500 g of ion-exchanged water having 15 g of potassium persulfate dissolved therein was added thereto while stirring at a low speed for 10 minutes. After carrying out nitrogen substitution, while stirring the inside of the reaction vessel, the contents were heated with a heating device until the temperature reached 80 ° C., and polymerization was continued for 1 hour.

  After 1 hour, emulsion polymerization was continued (aged) for another 2 hours to prepare “resin particle dispersion A”.

  The resin particles obtained had a particle size of 15 nm, a glass transition point (Tg) of 58 ° C., and a weight average molecular weight (Mw) of 11,500. The solid content concentration of the resin particle dispersion was 20% by mass.

(Preparation of resin particle dispersion B)
In a heat-dried three-necked flask, 30.0 parts by mass of ethylene glycol, 20.1 parts by mass of sodium dimethyl 5-sulfoisophthalate, 60 parts by mass of dimethyl sulfoxide, and 0.03 parts by mass of dibutyltin oxide as a catalyst (Wako Pure Chemical Industries, Ltd.) After that, the air in the container was brought into an inert atmosphere with nitrogen gas by depressurization, and stirred at 180 ° C. for 3 hours by mechanical stirring. Dimethyl sulfoxide was distilled off under reduced pressure, 77.1 parts by mass of dimethyl sebacate (manufactured by Wako Pure Chemical Industries, Ltd.) was added under a nitrogen stream, and the mixture was stirred at 180 ° C. for 1 hour. Thereafter, the temperature was gradually raised to 220 ° C. under reduced pressure, and the mixture was stirred for 30 minutes. When it became viscous, it was air-cooled to stop the reaction, and a crystalline polyester resin was synthesized.

  The weight average molecular weight (Mw) of the obtained crystalline polyester resin was 9100 and the number average molecular weight (Mn) was 5400 by molecular weight measurement (polystyrene conversion) by gel permeation chromatography (GPC).

  When melting | fusing point (Tm) of the obtained crystalline polyester resin was measured using the differential scanning calorimeter (DSC), it had a clear peak and the temperature of the peak top was 71 degreeC. Moreover, when the NMR spectrum of the obtained crystalline polyester resin was measured, the content ratio of the copolymer component (5-sulfoisophthalic acid component) and the sebacic acid component was 7.5: 92.5.

  Next, 200 parts by mass of the crystalline polyester resin obtained above was put into 800 parts by mass of distilled water, and mixed and stirred with a homogenizer “Ultra Turrax T50” (manufactured by IKA) while heating to 85 ° C. Resin particle dispersion B ”was prepared.

(Preparation of colorant particle dispersion)
60 g of yellow pigment “CI Pigment Yellow 74”
Anionic surfactant "Emar E27C" (manufactured by Kao Corporation) 13g
240g of ion exchange water
After the above components are mixed, they are mixed for 10 minutes using a homogenizer “Ultra Turrax T50” (manufactured by IKA), and then dispersed by an SC-mill to disperse a colorant having an average particle size of 250 nm. A “colorant particle dispersion” was prepared.

(Preparation of wax dispersion A)
Stearyl stearate 100g
Cationic surfactant "Sanisol B50" (manufactured by Kao Corporation) 5g
240g of ion exchange water
The above components were mixed for 10 minutes in a round stainless steel reaction vessel using a homogenizer “Ultra Turrax T50” (manufactured by IKA), and then dispersed three times with a pressure discharge type homogenizer. “Wax Dispersion A” in which wax particles of 20 μm were dispersed was prepared.

(Preparation of wax dispersion B)
Stearyl stearate 88g
3g behenyl behenate
Behenyl stearate 6g
Stearyl behenate 4g
Cationic surfactant "Sanisol B50" (manufactured by Kao Corporation) 5g
240g of ion exchange water
The above components were mixed for 10 minutes in a round stainless steel reaction vessel using a homogenizer “Ultra Turrax T50” (manufactured by IKA), then dispersed once with a pressure discharge homogenizer, and the average particle size was 0. “Wax dispersion B” in which wax particles of 90 μm were dispersed was prepared.

(Preparation of toner particle dispersion)
Resin fine particle dispersion A 234 parts by weight Colorant particle dispersion 30 parts by weight Wax dispersion A 7 parts by weight Wax dispersion B 33 parts by weight Magnesium chloride (manufactured by Ako Kasei Co., Ltd.) 8 parts by weight After mixing and dispersing, the reaction vessel was heated to 90 ° C. with a heating device while stirring.

  While confirming the volume average particle diameter, the mixture was continuously heated, 33 parts of sodium chloride was added at a volume average particle diameter of 6.2 μm to stop the particle diameter growth, and “Toner Particle Dispersion 1” was prepared.

<Toner particle dispersion 2>
Similar to “Toner Particle Dispersion 1” except that the cyan pigment “CI Pigment Blue 15: 3” was used instead of the yellow pigment “CI Pigment Yellow 74” of “Toner Particle Dispersion 1”. “Toner particle dispersion 2” was prepared.

<Toner particle dispersion 3>
“Toner Particles” is the same as “Toner Particle Dispersion 1” except that the magenta pigment “CI Pigment Red 122” was used instead of the yellow pigment “CI Pigment Yellow 74” of “Toner Particle Dispersion 1”. Dispersion 3 ”was prepared.

<Toner particle dispersion 4>
“Toner Particles” is the same as “Toner Particles Dispersion 1” except that carbon black “Regal 330R” (manufactured by Cabot) is used instead of the yellow pigment “CI Pigment Yellow 74” of “Toner Particles Dispersion 1”. Dispersion 3 ”was prepared.

<Toner particle dispersion 5>
“Toner particle dispersion 1” except that the mass part of wax dispersion A in “toner particle dispersion 1” was changed from 7 parts by mass to 14 parts by mass, and the mass part of wax dispersion B was changed from 33 parts by mass to 26 parts by mass. "Toner particle dispersion 5" was prepared in the same manner.

<Toner particle dispersion 6>
“Toner particle dispersion 2” except that the mass part of wax dispersion A in “toner particle dispersion 2” was changed from 7 parts by mass to 14 parts by mass, and the mass part of wax dispersion B was changed from 33 parts by mass to 26 parts by mass. "Toner particle dispersion 6" was prepared in the same manner.

<Toner particle dispersion 7>
“Toner particle dispersion 3” except that the mass part of wax dispersion A in “toner particle dispersion 3” was changed from 7 parts by mass to 14 parts by mass, and the mass part of wax dispersion B was changed from 33 parts by mass to 26 parts by mass. "Toner particle dispersion 7" was prepared in the same manner.

<Toner particle dispersion 8>
“Toner particle dispersion 4” except that the mass part of wax dispersion A of “toner particle dispersion 4” was changed from 7 parts by mass to 14 parts by mass, and the mass part of wax dispersion B was changed from 33 parts by mass to 26 parts by mass. "Toner particle dispersion 8" was prepared in the same manner.

<Toner particle dispersion 9>
A “toner particle dispersion 9” was prepared in the same manner as the “toner particle dispersion 1” except that the resin particle dispersion A of the “toner particle dispersion 1” was changed to 7 parts by mass of the resin particle dispersion B.

<Toner particle dispersion 10>
A “toner particle dispersion 10” was prepared in the same manner as the “toner particle dispersion 2” except that the resin particle dispersion A of the “toner particle dispersion 2” was changed to 7 parts by mass of the resin particle dispersion B.

<Toner particle dispersion 11>
A “toner particle dispersion 11” was prepared in the same manner as the “toner particle dispersion 3” except that the resin particle dispersion A of the “toner particle dispersion 3” was changed to 7 parts by mass of the resin particle dispersion B.

<Toner particle dispersion 12>
A “toner particle dispersion 12” was prepared in the same manner as the “toner particle dispersion 4” except that the resin particle dispersion A of the “toner particle dispersion 4” was changed to 7 parts by mass of the resin particle dispersion B.

<Toner particle dispersion 13>
“Toner particle dispersion 1” except that the mass part of wax dispersion A in “toner particle dispersion 1” was changed from 7 parts by mass to 40 parts by mass, and the mass part of wax dispersion B was changed from 33 parts by mass to 0 mass. "Toner particle dispersion 13" was prepared in the same manner.

<Toner particle dispersion 14>
“Toner particle dispersion 2” except that the mass part of wax dispersion A in “toner particle dispersion 2” was changed from 7 parts by mass to 40 parts by mass, and the mass part of wax dispersion B was changed from 33 parts by mass to 0 mass. "Toner particle dispersion 14" was prepared in the same manner.

<Toner particle dispersion 15>
“Toner particle dispersion 3” except that the mass part of wax dispersion A in “toner particle dispersion 3” was changed from 7 parts by mass to 40 parts by mass, and the mass part of wax dispersion B was changed from 33 parts by mass to 0 mass. "Toner particle dispersion 15" was prepared in the same manner.

<Toner particle dispersion 16>
“Toner particle dispersion 4” except that the mass part of wax dispersion A in “toner particle dispersion 4” was changed from 7 parts by mass to 40 parts by mass, and the mass part of wax dispersion B was changed from 33 parts by mass to 0 mass. "Toner particle dispersion 16" was prepared in the same manner.

  Table 1 shows the composition of the resin particle dispersion for preparing the toner particle dispersion.

<Solid particle-liquid separation>
The “toner particle dispersions 1 to 16” produced above were separated into solid and liquid using a rotary cylindrical dehydrator “MARK III model number 60 × 40” (Matsumoto Machine Co., Ltd.) equipped with a filter to produce a toner cake. . The produced toner cake was washed with water in a rotary cylindrical dehydrator, scraped off with a scraper inserted into the machine, discharged from the machine, and stored in a container. Thereafter, the stored toner cake is supplied to a dryer “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.) and dried until the water content of the toner particles reaches 0.5% by mass. Was made.

  Table 2 shows the wax domain diameter and the like of the toner obtained.

<External additive addition process>
100 parts by mass of the “toner particles 1 to 16” produced above were each 0.8 parts by mass of rutile titanium oxide (average primary particle size = 20 nm, n-decyltrimethoxysilane treatment), monodispersed spherical silica (sol-gel method) The silica sol obtained in HMDS was subjected to HMDS treatment, dried and pulverized, and 1.8 parts by mass of a volume average particle diameter D50 = 140 nm) was mixed with a mixer “Henschel mixer” (peripheral speed 30 m / s) (Mitsui Miike Chemical Industries). For 15 minutes. Thereafter, coarse particles were removed using a sieve having an opening of 45 μm to obtain “Toners 1 to 16”.

<Print image formation>
Using the above “toners 1 to 16”, image formation is performed by the image forming apparatus of FIG. 3 to which the fixing device of FIG. 1 is mounted, and print images of “Inventions 1 to 3” and “Comparative Examples 1 and 2” are created. did.

  The fixing device of “Comparative Example 2” produced a print image by using an image forming apparatus equipped with a fixing device having a uniform nip pressure shown in FIG.

《Print image evaluation》
<Glossiness>
Using art paper (manufactured by Mitsubishi Paper Industries Co., Ltd., special diamond art) as a recording medium, printed solid images of Y, M, C, R, G, and Bk were converted into a commercially available glossiness measuring device (incident angle 75 ±). 0.1 °).

Evaluation Criteria A: Excellent with a glossiness of 60% or more B: Good with a glossiness of 40-60% x: A glossiness of less than 40% and inferior utility.

<Gloss angle dependence>
Using art paper (manufactured by Mitsubishi Paper Co., Ltd., special diamond art) as a recording medium, a printed solid image of Y, M, C, R, G, and Bk is displayed in front, oblique 45 ° forward light, oblique 45 Evaluation was made by viewing (observation) from the backlight of °.

Evaluation criteria ◎: Impression does not change even when viewed from the front, 45 ° diagonal light, and 45 ° backlight. ○: High gloss when viewed from the front, but when viewed from 45 ° diagonal light. When viewed from an oblique 45 ° backlight, the glossiness is slightly different.

  X: The glossiness is clearly different when viewed from the front and when viewed from the oblique 45 ° forward light and the oblique 45 ° backlight.

<Dot deformation and color shift>
With a printer that printed 200,000 sheets, the deformation and color misregistration of unfixed and fixed images were evaluated using a loupe.

Evaluation Criteria A: The dot is similar between the unfixed image and the fixed image, and both the color shift is excellent and the color shift is excellent. ○: In the fixed image, the dot is somewhat stretched or shrunk in the transport direction, but the color shift is good. In the fixed image, dots were observed to expand or contract in the transport direction, and color misregistration occurred.

<Color gamut>
The fixing temperature of each image forming apparatus is set to 140 ° C., and each primary color of magenta (M), cyan (C), and yellow (Y) and each primary color are superposed in a 1: 1 ratio. , Blue (B) and green (G) were output. Art paper (Mitsubishi Paper Co., Ltd., Tokuhishi Art) and Fuji Xerox Office Supply Co., Ltd. C2r (smoothness 28) were used as recording media. Japan Color (Japan Color) was selected as a standard color in Japan by the Japan National Committee of the International Organization for Standardization Printing Technology Committee (ISO / TC130). The selection is made by collecting one piece each of the most common sheet-fed lithographic process inks from eight representative ink manufacturers in Japan, and measuring the color values of each color developed under the same conditions. The selected Japan Color (Japan Color) was submitted to the International Organization for Standardization (ISO) in 1990 and is now the color standard in Japan. Standard color swatches are supplied by the Japan National Committee of the International Organization for Standardization Printing Technology Committee (ISO / TC130) and are readily available.

A: Color gamut equivalent to that of Japan Color was exhibited. O: Color reproducibility close to that of Japan Color was possible, but strictly, it did not reach the color gamut of Japan Color. X: The color gamut was significantly narrower than that of Japan Color. It is had.

  Table 3 shows glossiness, gloss angle dependency, dot deformation and color shift. The gamut evaluation results are shown.

  As is clear from the evaluation results in Table 3, any of the evaluation items of the present inventions 1 to 3 was a good result.

1 is a cross-sectional configuration diagram showing an example of a form of a fixing device used in the present invention. 2 shows the result of examining the belt nip pressure distribution of the fixing device shown in FIG. 1. FIG. 2 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus that forms a full-color image equipped with the fixing device of FIG. 1. 1 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus that forms a full-color image equipped with a fixing device having a uniform nip pressure.

Explanation of symbols

100 Fixing roller 100a Metal core (cylindrical core)
100b Heat resistant elastic layer 100c Release layer (heat resistant resin layer)
110 Endless belt 120 Pressure pad (pressure member)
120a Pressure pad to which a strong nip pressure is applied 120b Pressure pad to which a weak nip pressure is applied 120c Holder made of metal, etc. 140 Halogen lamp 400 Lubricant supply member 410 Lubricant holding member 420 Lubricant permeation amount regulating film

Claims (5)

In an image forming method using a fixing device that fixes a toner image by setting a fixing pressure on a paper discharge side to be stronger than that on a paper supply side, the toner image is a toner that satisfies the following conditions (a) and (b): An image forming method characterized in that the image forming method is used.
(A) A wax having a domain diameter of 0.05 to 0.25 μm is contained in an amount of 1.5 to 26.0% based on the number.
(B) 18.6 to 99.8% of wax having a domain diameter of 0.31 to 1.22 μm is contained on a number basis. 2. The image forming method according to claim 1, wherein the fixing pressure on the paper discharge side is maximized in the vicinity of an exit of a nip formed by the fixing pressure member and the fixing heating member. The image forming method according to claim 1, wherein the toner includes toner particles having a polyester domain. The image forming method according to claim 1, wherein the image forming method is performed using a toner having the following properties (a) to (c).
(A) The average value of circularity is 0.979-0.996
(B) The volume average particle size is 4.4 to 9.8 μm.
(C) An endothermic peak measured by DSC is present at 58 to 73 ° C., and the endothermic amount is 12.6 to 24.5 J / mg. The image forming method according to claim 1, wherein the image forming method performs toner image formation by a non-magnetic one-component development method.

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