JP2008180938A - Toner for electrostatic charge image development, method for manufacturing the same, and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner for electrostatic charge image development which achieves low-temperature fixing of the toner, prevents phenomena liable to occur in the case of using a low-temperature fixable toner, such as toner blocking in storage and transport, and improves fold fixability of a toner image after fixing, a method for manufacturing the toner for electrostatic charge image development, and an image forming method. <P>SOLUTION: The toner for electrostatic charge image development has a core having a sea-island structure in which a vinyl polymer resin (island resin) formed from a vinyl polymerizable monomer including a polycarboxylic acid is dispersed in a sea resin of a vinyl copolymer, wherein a glass transition temperature TgA of the sea resin, a glass transition temperature TgB of the island resin and a glass transition temperature TgC of a resin for a shell have the relationship of the formula: TgB<TgA<TgC. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a toner for developing an electrostatic image, and more particularly to a core. The present invention relates to a toner for developing an electrostatic image having a shell structure, a manufacturing method thereof, and an image forming method.

  In recent years, from the viewpoint of consideration for the global environment, a technique for reducing the power consumption of an image forming apparatus has been studied, and polymerized toner has attracted attention as a means for solving this problem. As an example, a technique has been developed that can form a fixed image at a lower temperature than conventional ones using a polymerized toner containing a wax having a low melting point (for example, Patent Document 1).

  On the other hand, toner for developing an electrostatic charge image that can be fixed at a low temperature (hereinafter, also simply referred to as toner) tends to have a problem in thermal stability, and blocking (= aggregation) in which toners adhere to each other during storage or transportation. ) May occur. Further, in order to perform stable image formation, it is necessary to design the toner so that components such as a colorant and wax are not exposed from the toner surface.

  In view of such needs, a so-called core-shell toner is proposed in which a core particle surface in which a colorant and a wax are contained in a resin having a low softening point is coated (for example, Patent Document 2). reference).

  Furthermore, as a technique for producing a toner having a core-shell structure, the above-described improved techniques have been developed, and as a method for producing particles, for example, the surface of core particles produced by associating and fusing resin fine particles and a colorant Techniques have also been developed in which resin particles are fused to form a core-shell structure (see, for example, Patent Documents 3 to 5).

However, since the toner of the core-shell structure is covered with a shell layer having a high glass transition point (Tg), the affinity with the transfer paper due to the resin having a high Tg is deteriorated. When the toner image is folded, an image defect (= deterioration of the crease fixing property) that the toner image at the crease part is broken and peeled off easily occurs. Such a problem has not been sufficiently solved.
JP 2001-42564 A JP 2002-116574 A International Publication No. 98/25185 Pamphlet JP 2004-191618 A JP 2004-271638 A

  An object of the present invention is to solve various problems that are likely to occur in the above-described low-temperature fixing toner, particularly a low-temperature fixing toner having a core-shell structure. That is, at the same time as achieving low temperature fixing of the toner, it prevents the phenomenon such as toner blocking during storage or transportation, which is likely to occur when using low temperature fixing toner, and further fixes the crease of the toner image after fixing. An electrostatic charge image developing toner improved, and a method for producing the electrostatic charge image developing toner and an image forming method.

  As a result of intensive studies, the inventors of the present invention have found that the core portion of the core-shell structure is composed of a sea-island structure, and the glass transition point of the core sea-structure is TgA, The present inventors have found that the relationship between the glass transition point of the island structure TgB and the glass transition point of the shell structure TgC is an important factor, thereby completing the present invention.

That is, the object of the present invention is achieved by adopting the following configuration.
(1) In an electrostatic image developing toner having a core-shell structure having a shell on the surface of a core containing at least a resin and a colorant,
The core has a sea-island structure in which a vinyl-based polymer resin (= island resin) formed from a vinyl-based polymerizable monomer containing a polyvalent carboxylic acid is dispersed in a vinyl-based copolymer sea resin. The glass transition point of the sea resin is TgA, the glass transition point of the island resin is TgB, and the glass transition point of the shell resin is TgC. Toner for charge image development.

TgB <TgA <TgC
(2) The toner for developing an electrostatic charge image according to 1 above, wherein the TgA is 35 ° C. ± 5 ° C., the TgB is 20 ° C. ± 5 ° C., and TgC−TgA ≧ 10 ° C.
(3) Through the process of agglomerating the sea resin particles, the island resin particles, and the colorant particles to produce core particles having a sea-island structure, and the step of fusing the shell resin particles to the surface of the core particles, A method for producing a toner for developing an electrostatic charge image, comprising producing a toner having a core-shell structure having a sea-island structure.
(4) An image forming method in which an electrostatic latent image formed on a photosensitive member is transferred to a recording material by a developer containing an electrostatic charge image developing toner, and the toner image is heated and fixed in a fixing device. 3. The image forming method according to claim 1, wherein the electrostatic image developing toner is the electrostatic image developing toner according to 1 or 2, and a printing speed is 300 mm / sec or more.

  According to the present invention, it is possible to provide an electrostatic charge image developing toner that achieves low-temperature fixability, improved toner blocking, and improved crease fixability, a manufacturing method thereof, an image forming method, and an image forming apparatus.

[Technical idea of the present invention]
The electrostatic image developing toner of the present invention is an electrostatic image developing toner having a core-shell structure having a shell on the surface of a core containing at least a resin and a colorant. The core has a sea-island structure in which a vinyl-based polymer resin (= island resin) formed from a vinyl-based polymerizable monomer containing a polyvalent carboxylic acid is dispersed in a vinyl-based copolymer sea resin. Yes. When the glass transition point of the sea resin is TgA, the glass transition point of the island resin is TgB, and the glass transition point of the shell resin is TgC, these glass transition points have the relationship of the above formula.

  The toner of the present invention can achieve the above-described effects of the present invention by having the above relationship among the glass transition points TgA, TgB, and TgC.

  The present invention basically has a core-shell structure, which has a structure that ensures thermal stability such as prevention of toner blocking and achieves low-temperature fixability with the core structure. It has a great feature in the relationship between glass transition points TgA, TgB, and TgC. That is, by making the core structure a sea-island structure and achieving the relationship between the glass transition points TgA, TgB, and TgC, in addition to the above effects, crease fixability can be improved at the same time.

  That is, by containing a monomer having a polyvalent carboxylic acid in the island resin, the affinity between the toner particles and the transfer material is increased due to the presence of a plurality of carboxylic acids which are polar groups in the resin. It is estimated that the crease fixability is improved.

  Further, by lowering the Tg of the island resin relative to the sea resin, the island resin is easily diffused into the core particle of the toner, and the effect of the island resin is enhanced, and the solubility of the island resin is improved. It is presumed that it is faster than the resin, the island resin is likely to exist between the transfer material and the toner particles, and the effect of the affinity with the transfer material is further enhanced.

The core-shell structure in the present invention is a core-shell structure in which 90% or more of core particles are covered with a shell (shell layer). The sea-island structure of the present invention is a structure in which a binder resin for toner is phase-separated ( It has a sea-island structure) and has a phase separation structure of sea resin (medium resin) and island resin (dispersed resin) dispersed in the sea resin (medium resin).

[Glass transition point (glass transition temperature) Tg]
In the toner of the present invention, the glass transition point of the sea resin is TgA, the glass transition point of the island resin is TgB, and the glass transition point of the shell resin is TgC. These glass transition points are measured as follows. .

  The glass transition point can be determined using a DSC-7 differential scanning calorimeter (Perkin Elmer) or a TAC7 / DX thermal analyzer controller (Perkin Elmer).

  As a measurement procedure, 4.5 to 5.0 mg of a sample (resin to be evaluated, resin particles, toner, etc.) is precisely weighed to two digits after the decimal point, sealed in an aluminum pan (KITNO.0219-0041), DSC- 7 Set in the sample holder.

  The reference used an empty aluminum pan. As measurement conditions, the measurement temperature is 0 to 200 ° C., the temperature increase rate is 10 ° C./min, the temperature decrease rate is 10 ° C./min, and the heat-cool-heat control is performed. went.

  The glass transition point (glass transition temperature) is the intersection of the baseline extension before the rise of the first endothermic peak and the tangent line indicating the maximum slope between the rise of the first peak and the peak apex. Is shown as the glass transition point.

  The glass transition point of the sea resin is TgA, the glass transition point of the island resin is TgB, the glass transition point of the shell resin is TgC, and the type, amount and molecular weight of the copolymer component of the resin constituting them are appropriately selected. Can be controlled.

  In addition, said TgA, TgB, TgC, etc. show the glass transition point of resin containing the polymerization initiator contained in these resin components, a mold release agent, etc. at the time of preparation of these resins.

  The present invention has the glass transition points TgA, TgB, TgC and the like as described above. The glass transition point (Tgt) of the toner combining these glass transition points is 30 ° C. ± 5 ° C., and the softening point Tsp of the toner is A range of 80 ° C to 105 ° C is preferred.

  Hereinafter, components used for the toner, such as a resin used in the core-shell structure of the present invention, will be described.

[Toner material used in the present invention]
(1) Binder resin Core resin (sea resin)
In the present invention, examples of the monomer component to form the sea resin include vinyl aromatic monomers, vinyl ester monomers, vinyl ether monomers, olefin monomers, and the like. Among these, it is preferable to contain a radical polymerizable monovalent carboxylic acid (hereinafter also referred to as “radical polymerizable monovalent carboxylic acid”) component as a monomer component.

  This is because the presence of a carboxyl group, which is a polar group, allows the polymerization for obtaining a sea resin to proceed stably in an aqueous medium and ensures high dispersion stability of the resin fine particles in the aqueous medium in the sea resin. This is because the degree of polarity can be greatly different from that of the island resin described in detail later, and a sea-island structure can be obtained with certainty.

  Examples of the radical polymerizable monovalent carboxylic acid include methacrylic acid and acrylic acid.

  Moreover, as a content rate of the radically polymerizable monovalent | monohydric carboxylic acid in the whole monomer which should form sea resin, it is preferable that it is 3-20 mass%, More preferably, it is 5-10 mass%.

  Examples of vinyl aromatic monomers include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-methoxy styrene, p-phenyl styrene, p-ethyl styrene, pn-butyl styrene, p. -Tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2,4-dimethyl styrene, 3, Mention may be made of styrene monomers such as 4-dichlorostyrene and derivatives thereof.

  Examples of the vinyl ester monomers include vinyl acetate, vinyl butyrate, vinyl propionate, vinyl benzoate, and the vinyl ether monomers include vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl, and the like. And phenyl ether.

  Examples of the olefin monomer include monoolefin monomers such as ethylene, propylene, isobutylene, 1-butene, 1-pentene and 4-methyl-1-pentene; diolefin monomers such as butadiene, isoprene and chloroprene. The body is mentioned.

  Other radical polymerizable monomers other than the above include acrylic ester monomers such as ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; methyl methacrylate, ethyl methacrylate, butyl methacrylate, and the like. Methacrylic acid ester monomers; N-alkyl-substituted acrylamides such as N-methylacrylamide and N-ethylacrylamide; Nitrile monomers such as acrylonitrile and methacrylonitrile; Divinylbenzene, ethylene glycol (meth) acrylate, trimethylolpropane Examples include tri (meth) acrylate.

  Also, for example, as a monomer component to form a sea resin, a crosslinkable vinyl monomer having two or more unsaturated bonds such as divinylbenzene, divinylnaphthalene, divinyl ether, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, etc. The body may further be contained.

  The mass average molecular weight of the sea resin is preferably 10,000 to 50,000, more preferably 15,000 to 35,000.

  When the mass average molecular weight of the sea resin is 10,000 to 50,000, the sea resin has a low content of oligomer components, so there is little adverse effect on heat resistance and the entanglement of polymer chains. Thus, it is possible to ensure high gloss and smoothness in an image obtained without causing a significant increase in elasticity without being formed and without reducing heat resistance.

  The mass average molecular weight of the sea resin can be measured by gel permeation chromatography (GPC). Specifically, using an apparatus “HLC-8220” (manufactured by Tosoh Corporation) and a column “TSKguardcolumn + TSKgelSuperHZM-M3 series” (manufactured by Tosoh Corporation), while maintaining the column temperature at 40 ° C., tetrahydrofuran (THF) was used as a carrier solvent. The sample was flowed at a flow rate of 0.2 ml / min, and the measurement sample was dissolved in tetrahydrofuran to a concentration of 1 mg / ml under a dissolution condition in which treatment was performed for 5 minutes using an ultrasonic disperser at room temperature. A sample solution is obtained by processing with a filter, and 10 μL of this sample solution is injected into the apparatus together with the above carrier solvent, detected using a refractive index detector (RI detector), and the molecular weight distribution of the measurement sample is monodispersed. This is calculated using a calibration curve measured using polystyrene standard particles. Ten polystyrenes were used for calibration curve measurement.

  The glass transition temperature TgA of the sea resin is preferably 35 ° C. ± 5 ° C. When the glass transition temperature TgA of the sea resin is in the above range, it is possible to reliably obtain the effect that the formed image has sufficient glossiness and smoothness.

In order to configure the glass transition point TgA of the sea resin within the above range, the glass transition point (Tg) of a copolymer such as propyl acrylate, propyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, and the like is added to the styrene-acrylic copolymer resin. It is preferable to copolymerize a polymerizable monomer that lowers the above.
[Island resin]
In the present invention, the island resin is an island obtained by polymerization from a radically polymerizable monomer containing at least a radically polymerizable polyvalent carboxylic acid (hereinafter also referred to as “radical polymerizable polyvalent carboxylic acid”) component. The radically polymerizable monomer is made of a resin, and in addition to the radically polymerizable polyvalent carboxylic acid component, for example, the vinyl aromatic monomers listed as monomers used in the above-mentioned sea resin, vinyl Examples include ester monomers, vinyl ether monomers, and olefin monomers.
[Radically polymerizable polycarboxylic acid]
Examples of the radical polymerizable polycarboxylic acid forming the island resin include dicarboxylic acids such as itaconic acid and maleic acid, and itaconic acid is particularly preferable.

  Since the carboxyl group is a very polar functional group, since the radical polymerizable polycarboxylic acid has two or more carboxyl groups in one molecule, the island resin can be efficiently used with a small amount of the radical polymerizable polycarboxylic acid. Thus, the surface of the fine particles formed can be brought into a state of high polarity. As a result, the sea resin and the island resin can be in a phase-separated state (incompatible state) that is independent from each other, and the island resin increases the affinity between the transfer material and the toner particles, and has good crease fixability. Can be expressed.

  The content ratio of the radical polymerizable polycarboxylic acid in the polymerizable monomer composition forming the island resin is preferably 3 to 20% by mass, and more preferably 5 to 10% by mass.

  When the content ratio of the radically polymerizable polyvalent carboxylic acid in the polymerizable monomer composition is in the above range, the resin fine particles by the sea resin are high without aggregation between the resin fine particles by the island resin in the toner manufacturing process. A uniform mixed state can be obtained, and the degree of polarity with the sea resin can be made very different, and a sea-island structure can be obtained without being compatible with the sea resin, and the effect can be exhibited more remarkably. it can.

  In the toner of the present invention, the particle diameter of the island resin to be dispersed in the sea resin constituting the toner particles is preferably in the range of 50 to 600 nm.

  When the particle diameter of the island resin is in the range of 50 to 600 nm, the island resin and the sea resin can be aggregated with higher uniformity when toner particles are formed in the salting-out and aggregation processes described later. Since the island resin can be dispersed in the toner particles without being localized, the effect can be exhibited more remarkably.

  The particle size of the island resin in the toner particles can be determined by observing the cross section of the toner particles using a transmission electron microscope (TEM). A transmission electron microscope observes the internal structure of a substance by transmitting an electron beam through a sample and obtaining electrons scattered and diffracted by atoms in the sample as an electron diffraction pattern or transmission electron microscope image. In the present invention, a transmission electron microscope image (TEM image) of a sample obtained by cutting toner particles to a thickness of 0.2 μm by a microtome was taken at a magnification of 100,000 times, and the average value of the diameters of 100 toner particles was obtained. Is the particle size of the island resin.

  The island resin preferably has a mass average molecular weight of 10,000 to 50,000, more preferably 15,000 to 35,000.

  When the island resin has a mass average molecular weight of 10,000 to 50,000, the island resin has a low content of oligomer components, so there is little adverse effect on heat resistance and entanglement of polymer chains. Thus, it is possible to ensure high gloss and smoothness in an image obtained without causing a significant increase in elasticity without being formed and without reducing heat resistance.

  The mass average molecular weight of the island resin can be measured by the same method as the method for measuring the mass average molecular weight of the sea resin described above.

  The glass transition temperature TgB of the island resin is preferably 20 ° C. ± 5 ° C.

  When the glass transition temperature TgB of the island resin is in the above range, it is possible to surely obtain an effect that sufficient fixing separation property can be obtained in the fixing step.

  In order to configure the glass transition point of the island resin within the above range, the glass transition point of a copolymer such as propyl acrylate, propyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate is added to the styrene-acrylic copolymer resin ( It is preferable to copolymerize more polymerizable monomers that lower Tg) than in the case of sea resins.

  In the toner of the present invention, the content of the island resin is preferably 3 to 30% by mass, and more preferably 5 to 20% by mass with respect to the entire binder resin.

  When the content of the island resin is 3 to 30% by mass with respect to the total mass of the binder resin, the obtained toner surely has both excellent meltability and sufficient fixing separation performance. It becomes.

  The binder resin for the core may include a resin made of a compound other than the sea resin and the island resin (hereinafter also referred to as “other resin”). However, the total of the sea resin and the island resin is 50% by mass or more with respect to the total binder resin. These other resins may be contained in both the sea resin and the island resin, or may be contained in both, and different types of other resins may be contained in the sea resin and the island resin, respectively. . Examples of other resins include polyester resins.

Shell Resin The glass transition temperature TgC of the shell resin is preferably higher by 10 ° C. or more than the sea resin of the core resin. In order to form such a shell resin, a styrene-acrylic copolymer resin is preferred. Moreover, it is preferable to copolymerize the monomer for producing resin for shells with the polymerizable monomer which raises the glass transition point (Tg) of copolymers, such as styrene, methyl methacrylate, and methacrylic acid.

In the present invention, the toner shell refers to a portion that exists outside the core and covers 90% or more of the surface of the core particle. (In addition to the binder resin, the shell may contain various additives as necessary, but it does not contain a colorant (release agent).)
The mass average molecular weight of the shell resin is preferably 10,000 to 50,000, and more preferably 10,000 to 25,000.

  The mass average molecular weight of the shell resin can be measured by the same method as the above-described method for measuring the mass average molecular weight of the sea resin.

  The thickness of the shell of the present invention is preferably from 50 to 500 nm, more preferably from 100 to 300 nm, from the viewpoints of both the heat dependency of the core particles having a low Tg characteristic and the low-temperature fixability. The film thickness of the shell is measured by the following 8-point average film thickness.

  FIG. 1 is a schematic diagram of a toner having a core-shell structure. In FIG. 1, A shows the sea structure of the core, B shows the island structure of the core, and C shows the shell structure.

[Measurement method of 8-point average film thickness of shell]
The film thickness of the shell in the toner of the present invention is measured from a photograph obtained by photographing a cross-sectional layer of the toner with a transmission electron microscope. As a transmission electron microscope, a model well known to those skilled in the art is usually sufficiently observed. For example, LEM-2000 type (Topcon Corporation), JEM-2000FX (JEOL Ltd.) and the like are used.

  Specifically, the toner particles are first sufficiently dispersed in a room temperature curable epoxy resin, then embedded, dispersed in styrene fine powder having a particle size of about 100 nm, and then subjected to pressure molding. After the necessary blocks were dyed with ruthenium tetroxide or osmium tetroxide, a flaky sample was cut out using a microtome with diamond teeth, and a transmission electron microscope (TEM) was used. Then, the photograph is taken at a magnification (about 10,000 times) in which the cross section of one toner enters the field of view.

  Next, in the above photograph, the boundary line that becomes the interface between the core particle and the shell is clarified while visually confirming the existence region of the colorant, wax, and the like.

  Next, as shown in FIG. 1, straight lines are drawn toward the surface from the center of gravity F of the toner particles at intervals of 45 °, D is a point where each straight line intersects the core particle surface, and E is a point where each straight line intersects the shell layer surface. The distance between them (that is, the thickness of the shell) is measured at 8 points, and the average value of the 8 points is taken as the film thickness of the shell of one toner particle.

  The 8-point average film thickness of the present invention is shown as the average value of the 8-point average film thickness for 100 toner particles.

  When the minimum thickness of the shell layer was as close to 0 as possible, the thickness was measured as 10 nm.

    Next, materials other than the binder resin used for producing the toner will be described.

(2) Colorant As the colorant used in the toner of the present invention, carbon black, a magnetic material, a dye, a pigment, and the like can be arbitrarily used. As the carbon black, channel black, furnace black, acetylene black, thermal black Lamp black or the like is used. Magnetic materials include ferromagnetic metals such as iron, nickel and cobalt, alloys containing these metals, compounds of ferromagnetic metals such as ferrite and magnetite, alloys that do not contain ferromagnetic metals but exhibit ferromagnetism by heat treatment, For example, a kind of alloy called Heusler alloy such as manganese-copper-aluminum, manganese-copper-tin, chromium dioxide, or the like can be used.

  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 etc. can be used, and a mixture thereof can also be used. Examples of the pigment include C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122, 139, 144, 149, 166, 177, 178, 222, C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment Yellow 14, 17, 93, 94, 138, 156, 158, 180, 185, C.I. I. Pigment green 7, C.I. I. Pigment Blue 15: 3, 60, etc. can be used, and a mixture thereof can also be used. The number average primary particle diameter varies depending on the type, but is preferably about 10 to 200 nm.

  As a method for adding the colorant, the resin fine particles are added at the stage of agglomeration by the addition of the flocculant to color the polymer. The colorant can be used by treating the surface with a coupling agent or the like.

(3) Wax (release agent)
Examples of the wax that can be used in the toner according to the present invention include conventionally known waxes. Specifically, polyolefin waxes such as polyethylene wax and polypropylene wax, long-chain hydrocarbon waxes such as paraffin wax and sazol wax, dialkyl ketone waxes such as distearyl ketone, carnauba wax, montan wax, and trimethylolpropane. Tribehenate, pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, trimellit Ester waxes such as acid tristearyl and distearyl maleate, ethylenediamine dibehenyl amide, trimellitic acid tristearyl amide, etc. Such as amide waxes.

  Examples of the ester wax compound preferably used in the present invention are shown below.

  The melting point of the wax is usually 40 to 160 ° C, preferably 50 to 120 ° C, more preferably 60 to 90 ° C. By setting the melting point within the above range, the heat-resistant storage stability of the toner is ensured, and stable toner image formation can be performed without causing cold offset or the like even when fixing at a low temperature. Further, the wax content in the toner is preferably 1% by mass to 30% by mass, and more preferably 5% by mass to 20% by mass.

  The polymerization initiator, chain transfer agent, and surfactant that can be used in the toner production method will be described.

(4) Radical polymerization initiator usable in the present invention The resin constituting the core and shell constituting the toner according to the present invention is produced by polymerizing the aforementioned polymerizable monomer, but is used in the present invention. Possible radical polymerization initiators include the following. Specifically, as the oil-soluble polymerization initiator, 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane) -1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile and other azo or diazo polymerization initiators, benzoyl peroxide, methyl ethyl ketone peroxide , Diisopropylperoxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis- ( 4,4-t-butylperoxycyclohexyl) propane Tris - like the like (t-butylperoxy) polymeric initiator having a side chain a peroxide-based polymerization initiator or a peroxide, such as triazines.

  Moreover, when forming resin particles by an emulsion polymerization method, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, hydrogen peroxide and the like.

  Generally used chain transfer agents can be used for the purpose of adjusting the molecular weight of the resin constituting the composite resin particles.

  The chain transfer agent is not particularly limited, and examples thereof include mercaptans such as octyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, n-octyl-3-mercaptopropionate, terpinolene, carbon tetrabromide and α-methyl. Styrene dimer or the like is used.

(5) Dispersion stabilizer It is also possible to use a dispersion stabilizer in order to appropriately disperse the polymerizable monomer and the like in the reaction system. Dispersion stabilizers include tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate , Bentonite, silica, alumina and the like. Furthermore, those generally used as surfactants such as polyvinyl alcohol, gelatin, methylcellulose, sodium dodecylbenzenesulfonate, ethylene oxide adduct, and higher alcohol sodium sulfate can be used as the dispersion stabilizer.

(6) Surfactant The surfactant used in the present invention will be described.

  In order to perform polymerization using the above-mentioned radical polymerizable monomer, it is necessary to perform oil droplet dispersion in an aqueous medium using a surfactant. Although it does not specifically limit as surfactant which can be used in this case, The following ionic surfactant can be mentioned as an example of a suitable thing.

  Examples of ionic surfactants include sulfonates (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate, 3,3-disulfonediphenylurea-4,4-diazo-bis-amino-8-naphthol-6 Sodium sulfonate, ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-6-sodium sulfonate, etc.), sulfuric acid Ester salts (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salts (sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate) Beam, calcium oleate and the like).

  Nonionic surfactants can also be used. Specifically, polyethylene oxide, polypropylene oxide, combination of polypropylene oxide and polyethylene oxide, ester of polyethylene glycol and higher fatty acid, alkylphenol polyethylene oxide, ester of higher fatty acid and polyethylene glycol, ester of higher fatty acid and polypropylene oxide, sorbitan ester Etc.

(6) Charge Control Agent The toner particles constituting the toner of the present invention may contain a charge control agent as necessary. Various known compounds can be used as the charge control agent.

  As a method for incorporating the charge control agent into the toner particles, a method similar to the method for incorporating the above-mentioned release agent can be employed.

(7) Chain transfer agent In the polymerization step, a chain transfer agent generally used can be used for the purpose of adjusting the molecular weight of the sea resin and the island resin. The chain transfer agent is not particularly limited, and examples thereof include mercaptans such as 2-chloroethanol, octyl mercaptan, dodecyl mercaptan, and t-dodecyl mercaptan, and styrene dimers.

[Method for producing toner for developing electrostatic image]
Next, a method for producing an electrostatic charge image developing toner according to the present invention will be described.
<Toner production method>
As a method for producing the above toner, as long as it is a method for producing a sea resin and a toner particle in which core particles containing island resin dispersed in a fine particle form in the sea resin are coated with a shell resin layer, It is not particularly limited.

  For example, when the toner according to the present invention is manufactured, first, resin particles and colorant particles are associated and fused to produce core particles (hereinafter referred to as core particles). Next, resin particles are added to the core particle dispersion, and the resin particles are aggregated and fused on the surface of the core particles to coat the surface of the core particles to produce colored particles having a core-shell structure. As described above, the toner according to the present invention is a toner having a core-shell structure in which resin particles are added to a core particle dispersion prepared by various manufacturing methods and fused to the core particles.

  Specific toner production methods include emulsion polymerization aggregation method, miniemulsion polymerization aggregation method, suspension polymerization method, dispersion polymerization method, dissolution suspension method, melting method, kneading and pulverization method, among these, Since the island resin can be easily introduced into the sea resin, a toner production method by a miniemulsion polymerization aggregation method or an emulsion polymerization aggregation method is preferable.

  The toner according to the present invention is produced, for example, through the following steps.

A specific example of a method for producing toner by the miniemulsion polymerization aggregation method is as follows:
(1) a monomer solution preparation step for obtaining a radically polymerizable monomer solution containing a release agent as required;
(2) A polymerization step in which a radical polymerizable monomer solution is converted into oil droplets in an aqueous medium, and a dispersion of binder resin particles (sea resin and island resin resin particles) is prepared by performing a miniemulsion polymerization treatment;
(3) Aggregation / fusion process for aggregating the binder resin particles together with other core particle constituent resin particles such as colorant fine particles in an aqueous medium to obtain associated particles;
(4) a first aging step of aging associated particles with thermal energy to adjust the shape and obtaining core particles;
(5) A shell forming step of adding resin particles for the shell to the core particle dispersion and aggregating and fusing the shell particles on the surface of the core particles to form colored particles having a core-shell structure;
(6) a second aging step of aging the colored particles of the core-shell structure with thermal energy to adjust the shape of the colored particles of the core-shell structure;
(7) A washing step for solid-liquid separation of the colored particles from the cooled colored particle dispersion and removing the surfactant from the colored particles,
(8) A drying step of drying the washed colored particles,
Also, if necessary after the drying process,
(9) a step of adding an external additive to the dried colored particles,
Consists of

In the toner production method using the miniemulsion polymerization aggregation method, the island resin can be introduced in the following step (I) or (II).
(I) A method of introducing in the above (2) polymerization step. Specifically, the following methods (I-a) to (I-c) are exemplified.
(II) A method of introducing in the above-mentioned (3) aggregation / fusion process. Specific examples include the following methods (II-a) and (II-a).
(I-a) When performing the mini-emulsion polymerization process in the above (2) polymerization step, fine particles of an island resin previously polymerized to oil droplets of a radical polymerizable monomer solution to form a sea resin are added, Introducing into the center of toner particles.
(I-i) In the above (2) polymerization step, first, a radical polymerizable monomer solution for forming an island resin is converted into oil droplets in an aqueous medium and subjected to a miniemulsion polymerization treatment to obtain fine particles by the island resin. Then, the method of introducing by carrying out emulsion polymerization with a radically polymerizable monomer that should form a sea resin.
(I-C) After performing the mini-emulsion polymerization process for the sea resin in the (2) polymerization step, emulsion polymerization (multi-stage polymerization) is performed using the radical polymerizable monomer solution that should form the island resin. To introduce the toner particles near the surface of the toner particles.

Of these, the method of incorporating (I-a) is preferred.
(II-A) In the above (3) agglomeration / fusion process, island resin particles (island resin particles) are added simultaneously with addition of sea resin particles (sea resin particles) in an aqueous medium. A method of introducing them by aggregating them.
(II-i) In the above (3) aggregation / fusion process, after the aggregation of the sea resin particles in the aqueous medium is started, the island resin particles are added and aggregated in the middle of the aggregation process before the aggregation is completed. How to introduce by.

  Here, the “aqueous medium” refers to a medium composed of 50 to 100% by mass of water and 0 to 50% by mass of a water-soluble organic solvent. Examples of the water-soluble organic solvent include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran, and alcohol-based organic solvents that do not dissolve the resulting resin are preferable.

  The particle diameter of the toner of the present invention is preferably 4 to 8 μm, and more preferably 6 to 8 μm, for example, on a volume basis median diameter. When the toner production method is, for example, an emulsion polymerization aggregation method, the particle size is controlled by the concentration of the coagulant (salting out agent) used, the amount of organic solvent added, the fusing time, and the polymer composition. can do.

  When the particle size of the toner is in the above range, the transfer efficiency is increased, the image quality of halftone is improved, and the image quality of fine lines and dots is improved.

  The volume-based median diameter of the toner is measured and calculated using a device in which a computer system for data processing (Beckman Coulter) is connected to “Coulter Multisizer 3” (Beckman Coulter). is there.

  Specifically, 0.02 g of toner is added to 20 ml of a surfactant solution (for example, a surfactant solution obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing the toner). Then, ultrasonic dispersion was performed for 1 minute to prepare a toner dispersion, and this toner dispersion was measured in a beaker containing an electrolytic solution “ISOTONII” (manufactured by Beckman Coulter) in a sample stand. Pipette until the displayed concentration of the device is 5-10%. Here, a reproducible measurement value can be obtained by setting the concentration range. In the measuring device, the measurement particle count is 25,000, the aperture diameter is 50 μm, the frequency range is calculated by dividing the measurement range of 1 to 30 μm into 256, and the volume integrated fraction is 50% from the largest. The particle diameter (volume D50% diameter) is defined as the volume-based median diameter.

  Further, the glass transition temperature (Tgt) of the toner is preferably 20 to 45 ° C., and more preferably 25 to 35 ° C. This is because, by setting the glass transition point temperature of the toner as a whole in this range, good meltability of the toner can be obtained at the time of fixing, and therefore sufficient low-temperature fixability can be obtained.

  Further, the softening point Tsp of the toner is preferably 80 to 105 ° C. This is because, by setting the softening point temperature of the toner as a whole to this range, good melting property of the toner can be obtained at the time of fixing, and therefore sufficient low-temperature fixing property can be obtained.

  A method for measuring the softening point of the toner of the present invention will be described.

In an environment of 20 ± 1 ° C. and 50 ± 5% RH, 1.1 g of toner is put in a petri dish and flattened and left for 12 hours or more, and then 3820 kg / cm with a molding machine SSP-A (manufactured by Shimadzu Corporation). Pressure is applied for 30 seconds with a force of ² to produce a circular mold sample with a diameter of 1 cm.

In an environment of 24 ± 5 ° C. and 50 ± 20% RH, the above molded sample was loaded with a load of 196 N (20 kgf), a starting temperature of 60 ° C., a preheating time of 300 seconds, and a heating rate of 6 with a flow tester CFT-500D (manufactured by Shimadzu Corporation). Extruded from the end of preheating using a 1 cm diameter piston through a cylindrical die hole (1 mm x 1 mm) under the condition of ° C / min, and measured at a setting of an offset value of 5 mm by the melting temperature measurement method of the temperature rising method. The offset method temperature Toffset was used as the softening point of the toner.
<External additive>
The above toner particles can constitute the toner of the present invention as they are, but in order to improve fluidity, chargeability, cleaning properties, etc., a fluidizing agent that is a so-called post-treatment agent is added to the toner particles. An external additive such as a cleaning aid may be added to constitute the toner of the present invention.

  As the post-treatment agent, for example, inorganic oxide fine particles composed of silica fine particles, alumina fine particles, titanium oxide fine particles, etc., inorganic stearate compound fine particles such as aluminum stearate fine particles, zinc stearate fine particles, or strontium titanate, titanium Inorganic titanic acid compound fine particles such as zinc acid are listed. These can be used individually by 1 type or in combination of 2 or more types.

  These inorganic fine particles are preferably subjected to surface treatment with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil or the like in order to improve heat-resistant storage stability and environmental stability.

The total amount of these various external additives added is 0.05 to 5 parts by mass, preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the toner. In addition, various external additives may be used in combination.
(Developer)
The toner of the present invention can be used as a magnetic or non-magnetic one-component developer, but may be mixed with a carrier and used as a two-component developer. When the toner of the present invention is used as a two-component developer, the carrier is made of a conventionally known material such as a metal such as iron, ferrite, or magnetite, or an alloy of such a metal with a metal such as aluminum or lead. Magnetic particles can be used, and ferrite particles are particularly preferable. Further, as the carrier, a coat carrier in which the surface of the magnetic particles is coated with a coating agent such as a resin, a binder type carrier in which a magnetic fine powder is dispersed in a binder resin, or the like may be used.

  The coating resin constituting the coat carrier is not particularly limited, and examples thereof include olefin resins, styrene resins, styrene-acrylic resins, silicone resins, ester resins, and fluorine resins. Moreover, it does not specifically limit as binder resin which comprises a binder type carrier, A well-known thing can be used, For example, a styrene-acrylic resin, a polyester resin, a fluororesin, a phenol resin etc. can be used.

  The carrier preferably has a volume-based median diameter of 20 to 100 μm, more preferably 20 to 60 μm, since a high-quality image is obtained and carrier fogging is suppressed. The volume-based median diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

  Preferred carriers include a coated carrier using a silicone resin, a copolymer resin (graft resin) of an organopolysiloxane and a vinyl monomer or a polyester resin as a coating resin from the viewpoint of spent resistance. Coat carrier coated with resin obtained by reacting isocyanate with copolymer resin (graft resin) of organopolysiloxane and vinyl monomer from the viewpoint of durability, environmental stability and spent resistance Are preferable. The vinyl-based monomer forming the above coat carrier is a monomer having a substituent such as a hydroxyl group reactive with isocyanate.

[Image Forming Method and Image Forming Apparatus According to the Present Invention]
The toner according to the present invention may be used as a one-component developer or a two-component developer, but is particularly preferably used as a two-component developer.

  Next, an image forming method in which the toner according to the present invention can be used will be described. The toner according to the present invention is preferably used, for example, in a high-speed image forming apparatus having a printing speed (= linear speed of the photoreceptor) of 300 mm / sec (output performance of 50 sheets / min in terms of A4 paper). The Specifically, a printer that can produce a large amount of documents on demand in a short time can be used. Further, the present invention can be applied to an image forming method in which the temperature of the fixing roller is set to 150 ° C. or lower, preferably 130 ° C. or lower.

  This is because the toner according to the present invention has sufficient durability even though the shell covering the surface is thin, and the shell can fix the toner in a short time. It is called.

  FIG. 2 is an example of an image forming apparatus capable of using the toner according to the present invention, and shows a cross-sectional view thereof.

  The image forming apparatus shown in FIG. 2 collects toner remaining on the photosensitive member after the transfer step by a cleaning unit, and supplies a recovered toner to the developing device again to recycle and use a collected toner conveyance path corresponding to a toner recycling unit. An image forming apparatus.

  In FIG. 2, reference numeral 10 denotes a photosensitive drum which is an electrostatic latent image carrier, which is, for example, an organic photosensitive member (OPC photosensitive member) applied on a conductive drum and is grounded and rotated clockwise. Reference numeral 11 denotes a scorotron charger for negatively charging the circumferential surface of the photosensitive drum 10 by corona discharge to give a potential of VH. Before charging by the scorotron charger 11, it is necessary to neutralize the photosensitive member surface in order to remove the history of the photosensitive member up to the previous print, and the photosensitive member peripheral surface is exposed by the PCL 11A corresponding to the pre-charging exposure means. Remove the charge.

  After uniform charging of the photosensitive drum 10 by the scorotron charger 11, image exposure based on the image signal is performed by the laser writing device 12 corresponding to the image exposure means. In this image exposure, an image signal input from a computer or an image reading device is processed by an image signal processing unit, and then input to a laser writing device 12 to perform image exposure, and an electrostatic latent image is formed on the photosensitive drum 10. Form.

  The laser writing device 12 uses a laser diode (not shown) as a light source, performs main scanning by a plurality of reflecting mirrors 12d through a rotary polygon mirror 12a, an fθ lens 12b, etc., and performs sub-scanning by rotation of the photosensitive drum 10. As a result, an electrostatic latent image is formed. In this embodiment, the image portion is exposed based on the image signal, and the exposure portion forms a reverse latent image having a low potential absolute value VL.

  On the periphery of the photosensitive drum 10, a developing device 14 corresponding to a developing unit incorporating a two-component developer composed of a negatively charged conductive toner according to the present invention and a magnetic carrier is provided. In the developing device 14, the developer is held by a built-in magnet body, and reverse development is performed by a rotating developing sleeve, so that a toner image is formed on the photosensitive drum 10. Further, the toner image formed on the photosensitive drum 10 is transferred onto the transfer material P by a transfer roller 16a corresponding to a transfer unit.

  Next, the transfer material P to which the toner image has been transferred is neutralized by the pointed electrode 16c arranged with a slight gap, separated from the circumferential surface of the photosensitive drum 10, and conveyed to the fixing device 17 corresponding to the fixing means. The In the fixing device 17, the toner image is melted and fixed on the transfer material P by heating and pressing of the heating roller 17 a and the pressure roller 17 b, and then discharged onto the tray portion 54 by the discharge roller.

  The transfer roller 16a is retracted away from the circumferential surface of the photosensitive drum 10 after the transfer material P passes through until the next toner image is transferred.

  On the other hand, the photosensitive drum 10 on which the toner image is transferred to the transfer material P is subjected to charge removal by the charge eliminator 19 using an AC corona discharger, and then the residual toner is removed by the cleaning device 20 corresponding to the photoreceptor cleaning means. Done. That is, the residual toner on the peripheral surface is scraped into the cleaning device 20 by the cleaning blade 20a made of a rubber material in contact with the photosensitive drum 10, and the recovered toner thus scraped off is transported to the recovered toner containing a screw or the like. It is sent to the developing device 14 through the path 21.

  The photosensitive drum 10 from which the residual toner has been removed by the cleaning device 20 is exposed to light by the PCL 11A and then uniformly charged by the charger 11, and then enters the next image forming cycle.

  FIG. 3 is a cross-sectional view showing an example of the fixing device 17 that can be used in the image forming apparatus shown in FIG. 2, and includes a heating roller 17a and a pressure roller 17b that abuts the heating roller 17a. In FIG. 3, T is a toner image formed on a transfer paper (image forming support) P.

  In the heating roller 17a, a coating layer 171 made of a fluororesin or an elastic body is formed on the surface of the cored bar 172, and includes a heating member 173 made of a linear heater.

  The metal core 172 is made of metal and has an inner diameter of 10 mm to 70 mm. Although it does not specifically limit as a metal which comprises the metal core 172, For example, metals, such as iron, aluminum, copper, or these alloys can be mentioned.

  The wall thickness of the cored bar 172 is set to 0.1 mm to 15 mm, and is determined in consideration of a balance between a request for energy saving (thinning) and strength (depending on constituent materials). For example, in order to maintain the same strength as that of a cored bar made of iron of 0.57 mm with a cored bar made of aluminum, the wall thickness needs to be 0.8 mm.

  Examples of the fluororesin constituting the coating layer 171 include PTFE (polytetrafluoroethylene) and PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer).

  The thickness of the coating layer 171 made of a fluororesin is 10 μm to 500 μm, preferably 20 μm to 400 μm. Examples of the elastic body constituting the coating layer 171 include silicone rubber and silicone sponge rubber having good heat resistance such as LTV, RTV, and HTV. The Asker C hardness of the elastic body constituting the coating layer 171 is less than 80 °, preferably less than 60 °. The thickness of the coating layer 171 made of an elastic body is 0.1 mm to 30 mm, and preferably 0.1 mm to 20 mm.

  As the heating member 173, a halogen heater can be preferably used.

  The pressure roller 17 b is formed by forming a coating layer 174 made of an elastic body on the surface of the cored bar 175. The elastic body constituting the covering layer 174 is not particularly limited, and examples thereof include various soft rubbers such as urethane rubber and silicone rubber, and sponge rubber, and the silicone rubber and the silicone sponge rubber exemplified as those constituting the covering layer 174. Is preferably used. The Asker C hardness of the elastic body constituting the coating layer 174 is less than 80 °, preferably less than 70 °, and more preferably less than 60 °. The thickness of the covering layer 220 is 0.1 mm to 30 mm, preferably 0.1 to 20 mm.

  Although it does not specifically limit as a material which comprises the metal core 175, Metals, such as aluminum, iron, copper, or those alloys can be mentioned.

  The contact load (total load) between the heating roller 17a and the pressure roller 17b is usually 40N to 350N, preferably 50N to 300N, and more preferably 50N to 250N. This contact load is defined in consideration of the strength of the heating roller 17a (the thickness of the cored bar 110). For example, a heating roller having a cored bar made of iron of 0.3 mm should be 250 N or less. Is preferred.

  Further, from the viewpoint of offset resistance and fixing property, the nip width is preferably 4 mm to 10 mm, and the surface pressure of the nip is preferably 0.6 × 10 5 Pa to 1.5 × 10 5 Pa.

  FIG. 4 is a cross-sectional view showing an example of a fixing device using a belt and a heating roller.

  The fixing device 17 includes a heating roller 17a that is in contact with one surface of the recording material P on which a toner image is formed, an end pressing member 17d3, belt guide members 17d1 and 17d2, these end pressing members 17d3, and a belt guide member 17d1. An endless fixing belt 17d stretched around 17d2 and a pressure rotating body 17c including a pressure contact mechanism 177 disposed inside the fixing belt 17d. The heating roller 17a and the heating roller 17a A nip portion N is formed by a pressure contact portion between the pressure rotating body 17c and the pressure contact mechanism 177.

  The heating roller 17a incorporates a heating member 173 made of, for example, a halogen heater having a rated power of 600 W, and includes a metal core 172 in which the heating member 173 is disposed, and an outer periphery of the core 172. It is composed of a cylindrical roll composed of a heat-resistant elastic body layer 171a formed on the surface and a release layer (not shown) formed on the outer peripheral surface of the heat-resistant elastic body layer 171a. It is rotated at a linear velocity of 194 mm / sec.

  The core bar 172 constituting the heating roller 17a is made of a metal having high thermal conductivity such as iron, aluminum, stainless steel (SUS), and the outer diameter is, for example, 30 mm, and the thickness is, for example, 1.8 mm. The length is, for example, 360 mm.

  The heat-resistant elastic body layer 171a is made of an elastic body having high heat resistance, and it is particularly preferable to use an elastic body such as rubber or elastomer having a JIS-A hardness of 15 to 45 °, such as silicone rubber or fluororubber. Specifically, for example, a silicone HTV rubber having a JIS-A hardness of 35 ° can be coated on the metal core 172 with a thickness of 600 μm.

  As the release layer, for example, a heat-resistant resin such as a silicone resin or a fluororesin is used, and it is particularly preferable to use a fluororesin from the viewpoint of mold release properties and abrasion resistance with respect to the toner. Examples of the fluororesin include tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP). The thickness of the release layer is preferably 5 to 30 μm, and the surface thereof is preferably in a mirror state.

  In addition, a temperature sensor 176 is disposed in contact with the surface of the heating roller 17a. Based on a temperature measurement value by the temperature sensor 176, a control unit (not shown) of the image forming apparatus controls the heating member 173. By controlling the turning-on / off, the surface temperature of the heating roller 17a is maintained at a predetermined set temperature (for example, 175 ° C.).

  The fixing belt 17d constituting the pressure rotator 17c is formed of an endless belt having a seam formed in a cylindrical shape so that an image defect caused by a seam does not occur in an output image. A pressure contact pad 177a and an end pressure contact member 17d3, belt guide members 17d1 and 17d2 constituting a pressure contact mechanism 177 disposed inside the belt 17d, and an edge guide member (not shown) disposed at a side end of the fixing belt 17d. Z)) is supported in a freely circulating manner. In the nip portion N, the heat roller 17a is circulated and moved.

  The fixing belt 17d includes a base layer and a release layer formed on the outer peripheral surface or both surfaces of the base layer. The base layer is formed of thermosetting polyimide, thermoplastic polyimide, polyamide, polyamideimide, etc., and the thickness thereof is 30 to 200 μm, preferably 50 to 125 μm, more preferably 75 to 100 μm. The release layer is made of, for example, a fluororesin such as PFA, PTFE, FEP, and the thickness thereof is 5 to 100 μm, preferably 10 to 30 μm. An example of the fixing device 17 includes a configuration in which a release layer made of PFA having a thickness of 30 μm is laminated on a base layer made of thermosetting polyimide having a peripheral length of 94 mm, a thickness of 75 μm, and a width of 320 mm. it can.

  The press contact mechanism 177 constituting the pressurizing rotating body 17c is composed of a press contact pad 177a and an end press contact member 17d3. The press contact pad 177a constituting the press contact mechanism 177 includes a heating roller 17a by a spring or an elastic body. It is supported by the holder while being pressed with a load of about 350N.

  The pressure contact mechanism 177 is arranged inside the fixing belt 17d in a state of being pressed against the heating roller 17a via the fixing belt 17d, whereby a nip portion N is formed by the pressure contact portion with the heating roller 17a. Has been.

  A pre-nip member 177b is disposed at the inlet of the pressure contact mechanism 177, that is, the inlet side (upstream side) portion of the pressure contact pad 177a in order to ensure a wide nip portion.

  As the pressure contact pad 177a and its pre-nip member 177b, an elastic body such as silicone rubber or fluorine rubber, a leaf spring or the like can be used, and the surface of the pre-nip member 177b on the heating roller 17a side follows the outer peripheral surface of the heating roller 17a. It is formed by a concave curved surface. Specifically, as the prenip member 177b, for example, silicone rubber having a width of 10 mm, a thickness of 5 mm, and a length of 320 mm can be used. By providing the pre-nip member 177b as described above, the nip portion N can be configured to be wide, so that stable fixing performance can be ensured.

  Further, a low friction sheet is provided on the surface of the pressure contact pad 177a on the heating roller 17a side in order to reduce the sliding resistance between the inner peripheral surface of the fixing belt 17d and the pressure contact pad 177a. .

  The end pressure contact member 17d3 constituting the pressure contact mechanism 177 smoothes the surface of the toner image by locally pressing the surface of the heating roller 17a to impart image gloss, and also distorts (dents) the surface of the heating roller 17a. The recording material P is provided to form a down curl, and is disposed on the exit side of the nip portion N.

  The end pressure contact member 17d3 is made of heat-resistant resin such as polyphenylene sulfide (PPS), polyimide, polyester, polyamide, or a metal such as iron, aluminum, SUS, and the shape of the end pressure contact member 17d3 is as follows. The outer surface shape of the nip portion N is formed as a convex curved surface having a constant radius of curvature. The end pressure contact member 17d3 is disposed at a position where the fixing belt 17d is wrapped around the heating roller 17a by a pressure contact mechanism 177 at a winding angle of about 40 °, thereby forming a nip portion N having a width of about 10 mm. Has been.

  In such a fixing device 17, in the vicinity of the exit of the nip portion N, the recording material P separated from the heating roller 17 a by the end pressure contact member 17 d 3 is completely separated from the heating roller 17 a and guided to the paper discharge path. A separation assisting member (separation claw) is provided. For example, the peeling assisting member is held and arranged by the baffle holder in a state of being close to the heating roller 17a so that the peeling baffle is in a direction (counter direction) opposite to the moving direction on the surface of the heating roller 17a.

  Further, in such a fixing device 17, a lubricant application member is disposed along the longitudinal direction of the fixing device 17. Specifically, the lubricant application member is disposed in contact with the inner peripheral surface of the fixing belt 17d, and the lubricant is applied to the sliding portion between the fixing belt 17d and the low friction sheet by supplying an appropriate amount of lubricant. The sliding resistance between the fixing belt 17d and the pressure contact mechanism 177 supplied through the low friction sheet is reduced, and smooth circulation movement of the fixing belt 17d is achieved. Further, wear on the inner peripheral surface of the fixing belt 17d and the surface of the low friction sheet is suppressed.

  As the lubricant, those having durability against long-term use under a fixing temperature environment and capable of maintaining the wettability with the inner peripheral surface of the fixing belt 17d within an appropriate range are suitable. Liquid oil such as fluorine oil, grease in which a solid substance and a liquid are mixed, or a combination of these can be used. Examples of the silicone oil include dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, carboxy-modified silicone oil, silanol-modified silicone oil, and sulfonic acid-modified silicone oil.

  In the fixing device 17 as described above, when the heating roller 17a is connected to a drive motor (not shown) and rotated in the direction of arrow C, the fixing belt 17d is a contact portion with the heating roller 17a following this rotation. The toner image on the recording material P acts on the nip portion N when the recording material P is moved in the same direction at the nip portion N and is transferred to the nip portion N and passes through the nip portion N. Is fixed by the applied pressure and the heat supplied from the heating roller 17a.

  The image forming apparatus according to the present invention may use an induction heating type fixing device instead of the heating roll type fixing device.

  The transfer material P used in the present invention is a support for holding a toner image, and is usually called an image support, a recording material, or transfer paper. Specifically, various transfer materials such as plain paper and fine paper from thin paper to thick paper, coated printing paper such as art paper and coated paper, commercially available Japanese paper and postcard paper, plastic film for OHP, cloth, etc. However, it is not limited to these.

  FIG. 5 is a cross-sectional configuration diagram of a color image forming apparatus in which the toner according to the present invention can be used.

  This color image forming apparatus is called a tandem type color image forming apparatus, and includes four sets of image forming units (image forming units) 10Y, 10M, 10C, and 10Bk, an endless belt-shaped intermediate transfer body unit 7, and a feeding unit. It comprises a paper conveying means 21 and a fixing means 24. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  The image forming unit 10Y that forms a yellow image includes a charging unit (charging step) 2Y, an exposure unit (exposure step) 3Y, and a developing unit disposed around a drum-shaped photoconductor 1Y as a first image carrier. A unit (developing step) 4Y, a primary transfer roller 5Y as a primary transfer unit (primary transfer step), and a cleaning unit 6Y. An image forming unit 10M that forms a magenta image includes a drum-shaped photosensitive member 1M as a first image carrier, a charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, It has a cleaning means 6M. An image forming unit 10C for forming a cyan image includes a drum-shaped photoreceptor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a primary transfer roller 5C as a primary transfer unit. It has cleaning means 6C. The image forming unit 10Bk that forms a black image includes a drum-shaped photoreceptor 1Bk as a first image carrier, a charging unit 2Bk, an exposure unit 3Bk, a developing unit 4Bk, a primary transfer roller 5Bk as a primary transfer unit, and a cleaning unit. 6Bk.

  The four sets of image forming units 10Y, 10M, 10C, and 10Bk include charging means 2Y, 2M, 2C, and 2Bk that rotate around the photosensitive drums 1Y, 1M, 1C, and 1Bk, and image exposure means 3Y, 3M, 3C and 3Bk, rotating developing means 4Y, 4M, 4C and 4Bk, and cleaning means 5Y, 5M, 5C and 5Bk for cleaning the photosensitive drums 1Y, 1M, 1C and 1Bk.

  The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the colors of toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different, and the image forming unit 10Y is taken as an example in detail. explain.

  The image forming unit 10Y has a charging unit 2Y (hereinafter simply referred to as a charging unit 2Y or a charger 2Y), an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 5Y (around a photosensitive drum 1Y as an image forming body). Hereinafter, the cleaning means 5Y or the cleaning blade 5Y) is simply disposed, and a yellow (Y) toner image is formed on the photosensitive drum 1Y. In the present embodiment, in the image forming unit 10Y, at least the photosensitive drum 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 5Y are provided so as to be integrated.

  The charging unit 2Y is a unit that applies a uniform potential to the photosensitive drum 1Y. In the present embodiment, a corona discharge type charger 2Y is used for the photosensitive drum 1Y.

  The image exposure means 3Y performs exposure based on the image signal (yellow) on the photosensitive drum 1Y given a uniform potential by the charger 2Y, and forms an electrostatic latent image corresponding to the yellow image. As the exposure means 3Y, the exposure means 3Y includes an LED in which light emitting elements are arranged in an array in the axial direction of the photosensitive drum 1Y and an imaging element (trade name; Selfoc lens), or A laser optical system or the like is used.

  The image forming apparatus of the present invention is constructed by integrally combining the above-described photosensitive member and components such as a developing device and a cleaning device as a process cartridge (image forming unit). It may be configured to be detachable. In addition, at least one of a charging device, an image exposure device, a developing device, a transfer or separation device, and a cleaning device is integrally supported together with a photosensitive member to form a process cartridge (image forming unit), which is detachable from the apparatus main body. A single image forming unit may be detachable using guide means such as a rail of the apparatus main body.

  The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk as primary transfer means. Thus, a synthesized color image is formed. A transfer material P as a transfer material (a support for carrying a fixed final image: for example, plain paper, a transparent sheet, etc.) housed in the paper feed cassette 20 is fed by a paper feed means 21 and a plurality of intermediates. After passing through rollers 22A, 22B, 22C, 22D and registration roller 23, they are conveyed to a secondary transfer roller 5b as a secondary transfer means, and are secondarily transferred onto a transfer material P to transfer a color image all at once. The transfer material P onto which the color image has been transferred is subjected to fixing processing by the fixing unit 24, is sandwiched between paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus. Here, a transfer support for a toner image formed on a photosensitive member such as an intermediate transfer member or a transfer material is collectively referred to as a transfer medium.

  On the other hand, after the color image is transferred to the transfer material P by the secondary transfer roller 5b as the secondary transfer means, the residual toner is removed by the cleaning means 6b from the endless belt-shaped intermediate transfer body 70 in which the transfer material P is separated by curvature. The

  During the image forming process, the primary transfer roller 5Bk is always in contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C are in contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5b contacts the endless belt-shaped intermediate transfer body 70 only when the transfer material P passes through the secondary transfer roller 5b.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10Bk and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10Bk are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the drawing. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, primary transfer rollers 5Y, 5M, 5C, 5Bk, and cleaning means 6b. Consists of.

  EXAMPLES The present invention will be described below with reference to examples, but of course the present invention is not limited to these embodiments. In addition, the following "part" represents a "mass part".

<Preparation of sea resin particle A1 dispersion>
(1) First-stage polymerization In a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen introducing device, 105 parts of styrene, 59 parts of n-butyl acrylate, 12 parts of methacrylic acid, n-octyl mercaptan A monomer solution [1] was prepared by adding 70 parts of paraffin wax “HNP-57” as a release agent to a monomer composition consisting of 8 parts, and heating and dissolving at 80 ° C.

On the other hand, a surfactant solution in which 1.5 parts of an anionic surfactant (polyoxy (2) dodecyl ether sulfate sodium salt) is dissolved in 650 parts of ion-exchanged water is heated to 90 ° C. and then has a circulation path. The monomer solution [1] was mixed and dispersed for 3 hours using a mechanical disperser “CLEAMIX” (manufactured by M Technique Co., Ltd.) to prepare a dispersion containing emulsified particles having a dispersed particle diameter of 210 nm. Next, 700 parts of ion-exchanged water heated to 90 ° C. was added to the dispersion, and an initiator aqueous solution in which 3 parts of a polymerization initiator (KPS) was dissolved in 120 parts of ion-exchanged water was added. After setting to 82 ° C., polymerization (first stage polymerization) was carried out by heating and stirring for 3 hours to prepare a dispersion of resin fine particles [a1] (resin fine particle dispersion [a1]).
(2) Second-stage polymerization: Formation of outer layer An initiator aqueous solution in which 3 parts of a polymerization initiator (KPS) is dissolved in 120 parts of ion-exchanged water is added to the above resin fine particle dispersion [a3], Under temperature conditions
Styrene (St) 205.6 parts n-butyl acrylate (n-BA) 92.4 parts n-octyl mercaptan (NOM) A monomer solution [3.0] consisting of 3.0 parts was added dropwise over 1 hour. After completion of the dropwise addition, polymerization (second stage polymerization) was performed by heating and stirring for 3 hours, and then cooled to 28 ° C. to obtain a sea resin particle A1 dispersion having a composite resin fine particle structure having a multilayer structure.

  The glass transition temperature (TgA) of the sea resin particles A1 constituting the sea resin particle A1 dispersion was 33.0 ° C.

<Preparation of sea resin particle A2-A4 dispersion>
In the preparation of the sea resin particle A1 dispersion, the monomer solution, mold release agent type and n-octyl mercaptan amount during the first stage polymerization, and the monomer solution and n-octyl mercaptan amount during the second stage polymerization are shown. 1 except that the contents described in 1 were changed to obtain sea resin particle dispersions A2 to A4.

  Table 1 shows the glass transition point (TgA) and molecular weight of these sea resin particles.

<Preparation of island resin particle B1 dispersion>
Surfactant in which 3.0 parts of an anionic surfactant (Structural Formula 1) shown below is dissolved in 2800 parts of ion-exchanged water in a 5 L reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introducing device The solution was charged, and the internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream.

(Structural Formula 1) C ₁₀ H ₂₁ (OCH ₂ CH ₂ ) ₂ SO ₃ Na
on the other hand,
Methyl methacrylate 390 parts n-butyl acrylate 330 parts Itaconic acid 80 parts n-octyl mercaptan 2 parts were mixed and heated to 78 ° C. to dissolve itaconic acid to prepare a monomer solution.

Next, an initiator aqueous solution in which 10 parts of a polymerization initiator (potassium persulfate: KPS) is dissolved in 400 parts of ion-exchanged water is added to a 5 L reaction vessel, and the above monomer mixture is dropped over 2 hours. The system was heated at 80 ° C. for 2 hours,
By stirring, the island resin particle B1 dispersion was obtained.

  The glass point transition point (TgB) of the island resin particle B1 constituting the island resin particle B1 dispersion was 20 ° C. and the molecular weight was 100,000.

<Preparation of dispersion of island resin particles B2 to B6>
In the same manner as in the preparation of the island resin particle B1 dispersion, the type and composition ratio of 800 parts of monomer constituting the monomer solution and the amount of n-octyl mercaptan were changed as shown in Table 2. Resin particles B2 to B6 were obtained as a dispersion.

  Table 2 shows the glass transition point (TgB) and molecular weight of these island resin particles.

<< Resin particles for shell layer >>
<Preparation of Resin Particle C1 Dispersion for Shell>
A surfactant solution in which 2.0 parts of an anionic surfactant (Structural Formula 1) is dissolved in 3000 parts of ion-exchanged water is charged into a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device. The internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream.

  To this surfactant solution was added an initiator solution prepared by dissolving 10 parts of a polymerization initiator (potassium persulfate: KPS) in 200 parts of ion-exchanged water, 528 parts of styrene, 176 parts of n-butyl acrylate, methacrylic acid. A monomer mixture comprising 120 parts of acid and 22 parts of n-octyl mercaptan (= NOM) was dropped over 3 hours, and the system was polymerized by heating and stirring at 80 ° C. for 1 hour. Resin particles were prepared. This is referred to as “shell resin particle C1”.

<Preparation of Resin Particle C2 Dispersion for Shell>
In the preparation of “shell resin particle C1”, polymerization was carried out in the same manner except that a monomer mixture was used in which 556 parts of styrene, 148 parts of n-butyl acrylate, and 14 parts of n-octyl mercaptan were used. Resin particles were prepared. This is designated as “shell resin particle C2”.

<Preparation of Resin Particle C3 Dispersion for Shell>
In the preparation of “shell resin particles C1”, a monomer mixed solution in which styrene is changed to 516 parts, n-butyl acrylate is changed to 204 parts, methacrylic acid is changed to 100 parts, and n-octyl mercaptan is changed to 16 parts is used. Were similarly polymerized to prepare resin particles. This is designated as “shell resin particles C3”.

<Preparation of resin particle C4 dispersion for shell>
In the preparation of “shell resin particles C1”, a monomer mixed solution in which 452 parts of styrene, 236 parts of n-butyl acrylate, 140 parts of methacrylic acid, and 22 parts of n-octyl mercaptan were used was used. Were similarly polymerized to prepare resin particles. This is designated as “shell resin particles C4”.

  Table 3 shows the glass transition temperature (TgC) and molecular weight of the shell resin particles C1 to C4.

<Production of toner>
Toners 1 to 13 were produced as follows.

<Preparation of Toner 1>
<Preparation Example 1 of Colorant Dispersion>
C. A solution obtained by stirring and dissolving 90 parts of sodium dodecyl sulfate in 1600 parts of ion-exchanged water was stirred under C.I. I. 420 parts of Pigment Blue 15: 3 was gradually added, and then dispersed using a stirrer “CLEARMIX” (manufactured by M Technique Co., Ltd.) to obtain a colorant dispersion [1]. As a result of measuring the particle diameter of the colorant in the colorant dispersion [1] using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the mass average diameter was 110 nm.

(Salting out / fusion (association / fusion) process) (core formation)
In a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction device, 405 parts of sea resin particle A1 dispersion in terms of solids and 45 parts of island resin particle B1 dispersion in terms of solids Then, 1100 parts of ion-exchanged water and 100 parts of the colorant dispersion [1] were charged and the liquid temperature was adjusted to 30 ° C., and then the pH was adjusted to 10.0 by adding a 5N aqueous sodium hydroxide solution. Next, an aqueous solution in which 60 parts of magnesium chloride was dissolved in 60 parts of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. Thereafter, the temperature was raised after being allowed to stand for 3 minutes, and the temperature of the system was raised to 80 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 80 ° C. In this state, the particle size of the associated particles was measured with “Coulter Counter TA-II” (manufactured by Coulter Co.). When the particle median system (D50) reached 5.5 μm, 40.2 parts of sodium chloride was added. An aqueous solution dissolved in 1000 parts of ion-exchanged water is added to stop the particle size growth, and further, the fusion is continued by heating and stirring at a liquid temperature of 70 ° C. for 1 hour as a ripening treatment. Formed.

  The circularity of “Core 1” was measured by “FPIA 2000” (manufactured by Systex) and found to be 0.912.

(Formation of shell layer) (Shelling operation)
Next, 50 parts of “shell resin particles C1” were added at 65 ° C. in terms of solid content, and an aqueous solution in which 2 parts of magnesium chloride hexahydrate was dissolved in 1000 parts of ion-exchanged water was added over 10 minutes. Thereafter, the temperature was raised to 70 ° C. (shelling temperature) and stirring was continued for 1 hour to fuse the particles of “resin particle 1 for shell layer 1” to the surface of “core part 1”, and then 75 ° C. Aged for 20 minutes to form a shell layer.

  Here, 40.2 parts of sodium chloride was added, cooled to 30 ° C. under the condition of 8 ° C./min, and the generated fused particles were filtered and repeatedly washed with 45 ° C. ion-exchanged water. By drying with warm air, “Toner 1” having a shell layer on the surface of the core portion was obtained.

<Preparation of Toners 2 to 11>
The sea resin particles A1, island resin particles B1, and shell resin particles C1 used in the production of “Toner 1” were changed to the types and proportions of the sea resin particles, island resin particles, and shell resin particles described in Table 4. Except for the above, “Toners 2 to 11” were prepared in the same manner as in Preparation of Toner 1.

Of the resin compositions in Table 4, mass% is the total amount of resin composition for each toner, and the proportion of each resin is changed by mass%. For example, the sea resin particle A2 of the toner 2 is 84% in terms of mass%, and the amount represents 500 × 0.84 = 420 parts.
《External treatment process》
1% by weight of hydrophobic silica (number average primary particle size = 12 nm, degree of hydrophobicity = 68) and hydrophobic titanium oxide (number average primary particle size = 20 nm, degree of hydrophobicity) were prepared in the above “Toners 1 to 11”. = 63) was added in an amount of 1.2% by mass and mixed with a Henschel mixer to prepare "Toners 1 to 11".
<< Preparation of developer >>
Next, a ferrite carrier having a volume average particle diameter of 50 μm coated with a silicone resin was mixed with each of the prepared toners to prepare “Developers 1 to 11” having a toner concentration of 6%.

Evaluation Commercially available color multifunction peripheral “bizhubPRO C500” employing the electrophotographic method and having the configuration shown in FIG. 5 (manufactured by Konica Minolta Business Technologies, Inc .: Tandem color machine for intermediate transfer belt: linear speed of 300 mm / sec) Was used as an evaluator, and the developers 1 to 11 were mounted on the evaluator, and the following evaluation was performed with a single color of cyan toner. The results are shown in Table 4.

<Heat resistant storage>
The heat-resistant storage property is that the amount of agglomerates (percentage) remaining on the sieve after 100 parts of the toner prepared above were allowed to stand for 24 hours at 55 ° C. and 90% RH and then sieved with a sieve having an opening of 45 μm. ).

Evaluation Criteria A: The amount on the sieve is less than 5% by mass and the agglomeration amount is very low, and the heat-resistant storage property is excellent (there is no agglomeration even if transported in summer without any heat insulating packing material)
○: The amount on the sieve is 5 to 30% by mass, and the amount of aggregation is small and the heat-resistant storage property is good.
X: The amount on the sieve is more than 30% by mass, the amount of aggregation is large, and there is a practical problem (need to carry out cold transport).

(Low temperature fixability)
The surface temperature of the heating roller of the fixing device is changed so as to change in increments of 10 ° C. within the range of 80 ° C. to 150 ° C., and the A4 size POD gloss coated paper (manufactured by Oji Paper Co., Ltd.) at each temperature in the transport direction. In addition, a live-action test in which a 5 cm wide betacyan belt image (toner adhesion amount of 10 to 11 g / m ² ) formed in the vertical direction is conveyed by vertical feeding is performed, and cold offset does not occur (offset does not occur on the low temperature side) ) Evaluation was made based on the fixing temperature (minimum fixing temperature). The fixing temperature was measured by measuring the surface temperature of the heating roller with a temperature sensor.
If the minimum fixing temperature was less than 130 ° C., the test was accepted.
(Crease fixing)
The crease fixability was evaluated using a betacyan strip image (toner adhesion amount of 10 to 11 g / m ² ) obtained at a fixing temperature 20 ° C. higher than the minimum fixing temperature obtained in the low temperature fixability evaluation.

  A crease is made in the fixed image with a load of 100 g using a folding machine, and then the air layer is blown onto the crease portion to remove the separated toner layer, and then the crease portion is visually observed.

<Evaluation criteria>
(Double-circle): There is no crack and an image does not have a defect (good).

  ○: The toner image is cracked, but the toner layer is slightly peeled off, and there is no problem in performance (practicality is possible).

  Δ: Cracks are generated in the toner image, and a line due to the paper surface is not observed at the crease part, but the toner layer is peeled off and there is a problem in performance (improvement is necessary for practical use).

  X: The toner layer is severely peeled, and a white line due to the paper surface is observed at the crease portion (no practicality).

  As apparent from Table 5 above, the toners 1 to 4 and toners 6 to 8 in the present invention show good characteristics in all of the heat-resistant storage property, the low-temperature fixability, and the crease fixability. 5 and 9 to 1 show that there is a problem with at least one of the characteristics.

FIG. 3 is a schematic diagram of a toner having a core-shell structure. FIG. 3 is a cross-sectional view of an image forming apparatus in which the toner according to the present invention can be used. FIG. 3 is a cross-sectional view illustrating an example of a heating roll type fixing device. It is a sectional view showing an example of a fixing device of a type using a belt and a heating roller. 1 is a cross-sectional configuration diagram of a color image forming apparatus in which a toner according to the present invention can be used.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Photosensitive drum 11 Scorotron charger 11A Pre-charge exposure means 12 Laser writing device T Toner A Core sea structure B Core island structure C Shell structure D The point where each straight line intersects with the core particle surface E Each straight line and the shell layer surface Intersection

Claims (4)

In an electrostatic charge image developing toner having a core-shell structure having a shell on the surface of a core containing at least a resin and a colorant, the core is a vinyl polymer containing a polyvalent carboxylic acid in a sea resin of a vinyl copolymer. It has a sea-island structure in which a vinyl polymer resin (= island resin) formed from a functional monomer is dispersed, the glass transition point of the sea resin is TgA, the glass transition point of the island resin is TgB, and the shell resin A toner for developing an electrostatic charge image, wherein the glass transition point is TgC, and these glass transition points have the following relationship:
TgB <TgA <TgC The toner for developing an electrostatic charge image according to claim 1, wherein the TgA is 35 ° C. ± 5 ° C., the TgB is 20 ° C. ± 5 ° C., and TgC-TgA ≧ 10 ° C. Through the steps of agglomerating the sea resin particles, the island resin particles, and the colorant particles to produce core particles having a sea-island structure, and the step of fusing the shell resin particles to the surface of the core particles, the sea-island structure is obtained. A method for producing a toner for developing an electrostatic charge image, comprising producing a toner having a core-shell structure. In the image forming method, the electrostatic latent image formed on the photosensitive member is transferred to a recording material with a developer containing an electrostatic charge image developing toner, and the toner image is transferred to a recording material and heated and fixed in a fixing device. An image forming method, wherein the electrostatic image developing toner is the electrostatic image developing toner according to claim 1, wherein the printing speed is 300 mm / sec or more.

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