JP4544041B2 - Toner for electrostatic image development - Google Patents

Description

The present invention relates to a toner over the electrostatic image developing.

  With the progress of energy saving, low temperature fixing technology is being developed in the electrophotographic industry.

  In order to achieve low-temperature fixing, electrostatic charge image developing toner (hereinafter also simply referred to as toner) has the following performance requirements: prevention of offset during low-temperature fixing, anti-aggregation in toner bottles or cartridges (storage stability and Ensuring heat-resistant storage).

  In order to achieve both prevention of occurrence of offset and anti-aggregation property, a method of using a core / shell type toner structure has been considered and has been studied.

  As a method for producing a core-shell type toner, resin particles obtained by polymerizing a polymerizable monomer in a solution are aggregated and fused to form a core portion, and a resin particle solution is further added to the top of the core portion. A method for forming a shell layer is known (see Patent Documents 1 and 2).

  However, the above core / shell structure toner has a remarkable effect on the aggregation resistance due to the shell layer having a high glass transition temperature. However, the shell having the high glass transition temperature is used at the time of low-temperature fixing in high-speed printing. The effect of the release agent was weakened by the layer, which still caused the problem of offset.

  In order to prevent the occurrence of offset on the low temperature side, the effect of the release agent is tremendous.

  As the characteristics of the release agent, the melting point and the state of presence in the toner, that is, the dispersion diameter, are effective for the performance. The melting point can be adjusted by the physical properties of the release agent, but the method for controlling the dispersion diameter of the release agent in the toner has not yet been solved. Further, as a method for measuring the dispersion diameter of the release agent in the toner, there is a conventional method of measuring a cross section obtained by cutting a toner particle with a microtome by taking a transmission electron microscope (TEM) photograph (see Patent Document 3). ).

However, the particle size of the release agent particles measured by this method is not preferable because it is detected as a value different from the particle size of the release agent particles actually contained in the toner. Because, in this method, the particle size of the release agent particle on the cut surface of the toner particles is measured. For example, even in the case of spherical release agent particles having the same particle diameter, the center of the release agent particle is present on the cut surface. The particle size of the release agent particles measured is completely different between the case where it exists and the case where an end portion deviating from the center of the release agent particle exists on the cut surface. Further, in the case of release agent particles such as rugby balls, the displacement of the measured particle diameter becomes more prominent due to the difference in the cutting direction and the cutting part.
Therefore, it has been difficult to obtain a toner that solves the above problems even with a toner in which the dispersion diameter of the release agent is defined and the low-temperature fixing performance is measured by this TEM observation method.
JP 2004-109939 A JP 2002-116574 A JP 2000-305309 A

  An object of the present invention is to provide a toner that achieves both low-temperature fixability and high aggregation resistance during high-speed printing.

  The object of the present invention is achieved by adopting the following configuration.

(Claim 1)
In the electrostatic charge image developing toner containing at least a binder resin, a colorant and a release agent, the release agent is a hydrocarbon wax having a melting point of 50 to 100 ° C., and a plurality of the release agents are present in the toner. The number average particle size of the dispersed particles of the release agent in the toner is 1.0 to 1.6 μm in the binder resin dissolution method, the standard deviation is 0.05 to 0.5, and the release agent A toner for developing electrostatic images, wherein the dispersed particles have a shape factor SF-1 of 1.0 to 1.4.

(Claim 2)
The toner for developing an electrostatic charge image according to claim 1, wherein the toner for developing an electrostatic charge image has a core-shell structure produced by an emulsion association method.

(Claim 3)
Among the release agents dispersed in the electrostatic image developing toner according to claim 1, 40 to 90% by number of particles having a number average particle diameter of 1.0 to 2.0 μm are contained. The toner for developing an electrostatic charge image according to claim 1 or 2,

  The present invention has made it possible to provide a toner that achieves both low-temperature fixability during high-speed printing and cohesion resistance.

  The present inventors have studied a toner that can achieve both low-temperature fixability and high aggregation resistance during high-speed printing.

  As a result of the study, the melting point and composition of the release agent used for toner formation, the particle size, standard deviation, and shape factor of the release agent in the toner are greatly related to low-temperature fixing and anti-aggregation properties during high-speed printing. I found it.

  In the present invention, examples of a method for controlling the particle size of the release agent in the toner include a method for preparing an emulsion association method toner using a resin containing a hydrophilic resin and a hydrophobic resin.

  The hydrophilic resin is a resin containing an acid monomer (monomer) in a composition component constituting the resin. The hydrophobic resin is a resin that does not contain an acid monomer (monomer) in the component that forms the resin. Examples of the acid monomer include acrylic acid, methacrylic acid, maleic acid, itaconic acid, trans-cinnamic acid, and fumaric acid. Acrylic acid and methacrylic acid are preferable.

  When resin particles associate with each other depending on the presence or absence of hydrophilicity to water to form a toner, a resin having high hydrophilicity tends to be oriented on the toner surface, causing fluidization of the resin inside the toner particles, and a release agent. Since the dispersed particles are easily brought into contact with each other, it is estimated that the release agent dispersion diameter has increased.

  Accordingly, the particle size and particle size distribution of the release agent are determined by the difference in hydrophilicity between the hydrophilic resin and the hydrophobic resin and the melting point of the release agent.

  The shape of the release agent is controlled by the temperature and time of the aging process. As the aging temperature is higher and the time is longer, the shape becomes spherical.

  As the release agent according to the present invention, a hydrocarbon wax having a melting point of 50 to 100 ° C. is used, the number average particle size of dispersed particles of the release agent in the toner is 0.5 to 2.0 μm, and the standard deviation is 0. Controlling 0.05 to 0.5 and the shape factor SF-1 to 1.0 to 1.4 can achieve both low-temperature fixability and aggregation resistance during high-speed printing.

  Further, the toner has a core-shell structure, and a toner containing 40 to 90% by number of particles having a number average particle diameter of 1.0 to 2.0 μm of dispersed particles of a release agent in the toner. preferable.

"Release agent"
First, the mold release agent used in the present invention will be described.

  The release agent used in the present invention is a hydrocarbon wax.

  Examples of hydrocarbon waxes include petroleum-derived paraffin wax, microcrystalline wax, and synthetic waxes such as Fischer-Tropsch wax, polyethylene wax, and polypropylene wax.

  In this invention, the said mold release agent can be used individually or in combination of multiple types as needed.

  The melting point of the release agent is 50 to 100 ° C, preferably 60 to 90 ° C, more preferably 65 to 85 ° C.

  The melting point of the release agent is measured using “DSC-7 differential scanning calorimeter” (manufactured by PerkinElmer) and “TAC7 / DX thermal analyzer controller” (manufactured by PerkinElmer).

  As a measurement procedure, 4.5 to 5.0 mg of toner is precisely weighed to two decimal places, sealed in an aluminum pan (KIT No. 0219-0041), and set in a “DSC-7 sample holder”. The reference used an empty aluminum pan. The measurement conditions were a measurement temperature of 0 ° C. to 200 ° C., a temperature increase rate of 10 ° C./min, a temperature decrease rate of 10 ° C./min, and heat-cool-heat temperature control. Analysis was performed based on the data in Heat.

  The melting point of the release agent indicates the peak top temperature of the main endothermic peak in the region other than the endothermic peak of the resin as the melting point of the release agent.

  The number average particle size of the release agent in the toner is 0.5 to 2.0 μm, preferably 1.0 to 1.6 μm in the binder resin dissolution method, and the standard deviation is 0.05 to 0.5. And the shape factor SF-1 of the dispersed particles of the release agent is 1.0 to 1.4, preferably 1.1 to 1.3.

  A release agent that has a particle size that is large enough to have a particle size in the toner ensures that the amount of the release agent that elutes on the image surface during high-speed heat fixing in a high-speed printer. It is easy to prevent the occurrence of wrapping around the fixing roll and occurrence of fixing offset.

  Further, since the amount of the indefinite type of release agent is smaller than the dispersion shape of the release agent, the release agent exposed on the surface of the toner is less. As a result, the release agents exposed on the surface of each toner at the time of storage are fused with each other so that toner aggregation is difficult to occur, and good aggregation resistance can be ensured.

  Further, in the particle size distribution of the release agent particles dispersed in the toner, the number average particle diameter of 1.0 to 2.0 μm is preferably 40 to 90% by number.

  The number average particle size by the binder resin dissolution method is measured as follows.

  Dissolve the binder resin using a solvent that dissolves the binder resin of the toner but does not dissolve the release agent, apply the insoluble release agent to a centrifuge, collect the release agent floating in the solvent, and scan it. It is an average value of particle diameters observed with a scanning electron microscope (x5000 times) and measured for 100 release agent particles.

  The solvent is not particularly limited as long as it is a solvent that dissolves the toner binder resin and does not dissolve the release agent, but chloroform is preferred. Furthermore, from the viewpoint of separability between the release agent particles and the colorant, a mixed solvent capable of adjusting the specific gravity of the solvent by mixing dimethylformamide or the like with chloroform is more preferable. As a mixing ratio, it is used by adjusting an equivalent amount to 10 times the amount of chloroform.

  Specifically, 100 mg of toner is added to 10 ml of a mixed solvent of chloroform / dimethylformamide = 1/2, and it is applied to an ultrasonic disperser for 10 minutes so that the toner is familiarized with the solvent. Then, the toner binder resin is dissolved by stirring for 2 hours at 100 rpm in a roll mill.

  This binder resin solution is centrifuged three times for 5 minutes at 15000 rpm with a centrifuge “himac CF-15R” (manufactured by Hitachi, Ltd.), and the colorant is allowed to settle with the release agent particles on the liquid surface. To separate. The release agent particles floating on the liquid surface are collected and dried at room temperature to obtain release agent particles dispersed in the toner.

  The obtained release agent-dispersed particles were photographed at a magnification of 5000 using a scanning electron micrograph, and the image captured by the scanner was released with an image analyzer “Luzex AP” (manufactured by Nireco). With respect to 100 particles, the horizontal ferret diameter and the shape factor SF-1 were measured, and the average value was calculated.

Horizontal ferret diameter: Distance between two vertical lines when the release agent particles are sandwiched by two vertical lines (Formula 1)
Shape factor SF-1 = (maximum length of release agent particles) ² / (projected area of release agent particles) × (π / 4)
The standard deviation of the particle size distribution of the release agent in the toner of the present invention is 0.05 to 0.5 μm, preferably 0.1 to 0.4 μm.

  The standard deviation of the particle size distribution of the release agent in the toner is calculated by the following formula.

S. D. = (((Measured value-number average value) ² sum) / number of data) ^1/2
FIG. 1 is a schematic cross-sectional view showing an example of the toner of the present invention.

  In the toner of the present invention shown in FIG. 1, the particle size of the release agent contained in the toner is large, the shape is round, the particle size is uniform, and there is no exposure of the release agent on the surface of the toner base. If there are, there are few.

  FIG. 2 is a cross-sectional configuration diagram illustrating an example of a conventional (comparative example) toner.

  The conventional (comparative) toner shown in FIG. 2 contains a release agent having a particle diameter from a small diameter to a large diameter, has a flake shape, and a large amount of the release agent is exposed on the surface of the toner base.

  1 and 2, reference numeral 10 denotes a toner base, 11 a resin, 12 a colorant particle, and 13 a release agent particle.

The median particle diameter (D ₅₀ ) on the volume basis of the toner is preferably 3 to 8 μm, and the particle diameter of the colorant particles is preferably _{50 to} 300 nm.

  Here, the toner base is a toner before an external additive is added.

<Production of toner>
Next, a method for producing the toner of the present invention will be described.

  The toner production method is preferably a method of producing a chemical toner that can easily control the particle size, particle size distribution, and shape factor of the release agent in the toner.

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

Hereinafter, an example of a toner production method using an emulsion polymerization association method will be described in detail.
(1) Dissolution / dispersion step for dissolving or dispersing the release agent in the radical polymerizable monomer (2) Polymerization step for preparing a dispersion of resin particles (3) Resin particles and colorant particles in an aqueous medium Aggregation / fusion process for aggregating and fusing the particles to obtain associated particles (4) Aging the associated particles with thermal energy to adjust the shape, and adjusting the particle size, shape, distribution, and shape factor of the release agent, A maturing step for producing a dispersion of the toner base (5) A cooling step for cooling the dispersion of the toner base (6) A solid-liquid separation of the toner base from the cooled dispersion of the toner base, and a surface activity from the toner base (7) A drying process for drying the washed toner base, and (8) a step of adding an external additive to the dried toner base, if necessary.

  Hereinafter, each step will be described.

[Dissolution / dispersion process]
This step is a step of preparing a radical polymerizable monomer solution of the release agent by dissolving or dispersing the release agent in the radical polymerizable monomer.

[Polymerization process]
In a preferred example of this polymerization step, a radical polymerizable monomer solution in which the release agent is dissolved or dispersed is added to an aqueous medium containing a surfactant, and mechanical energy is applied to form droplets. Then, the polymerization reaction is allowed to proceed in the droplets by radicals from the water-soluble radical polymerization initiator. In addition, you may add the resin particle as a core particle in the said aqueous medium.

  By this polymerization step, resin particles having a release agent, a hydrophilic resin, and a hydrophobic resin are obtained. Such resin particles may be colored particles or non-colored particles. The colored resin particles can be obtained by polymerizing a monomer composition containing a colorant. In addition, when using uncolored resin particles, the dispersion of the colorant particles is added to the dispersion of the resin particles in the fusion and aging process described later, and the resin particles and the colorant particles are melted. By attaching it, it can be made a toner base.

[Aggregation / fusion process]
In water containing resin particles and colorant particles, a salting-out agent made of an alkali metal salt or alkaline earth metal salt is added as an aggregating agent having a critical aggregation concentration or more, and each particle is agglomerated and fused. To form associated particles. In the agglomeration / fusion step, internal additive particles such as release agent particles and charge control agents can be aggregated together with resin particles and colorant particles.

[Aging process]
Aging is preferably performed by thermal energy (heating).

  Specifically, it is a step of adjusting the shape of the associated particles by heating and stirring the liquid containing the associated particles, and adjusting the particle size, distribution, and shape of the release agent to form a toner base.

[Cooling process]
This step is a step of cooling the toner base dispersion. As a cooling treatment condition, cooling is performed at a cooling rate of 1 to 20 ° C./min. The cooling treatment method is not particularly limited, and examples thereof include a method of cooling by introducing a refrigerant from the outside of the reaction vessel, and a method of cooling by directly introducing cold water into the reaction system.

[Solid-liquid separation and washing process]
In this solid-liquid separation / washing step, a solid-liquid separation process for solid-liquid separation of the toner base from the dispersion of the toner base cooled to a predetermined temperature in the above-described step, and a solid-liquid separated toner cake (in a wet state) A cleaning process is performed to remove deposits such as a surfactant and a salting-out agent from an aggregate obtained by agglomerating a toner base in a cake form. Here, the filtration method is not particularly limited, such as a centrifugal separation method, a vacuum filtration method using Nutsche or the like, a filtration method using a filter press or the like.

[Drying process]
In this step, the washed toner cake is dried to obtain a dried toner base. Examples of the dryer used in this step include a spray dryer, a vacuum freeze dryer, and a vacuum dryer, and a stationary shelf dryer, a mobile shelf dryer, a fluidized bed dryer, and a rotary dryer. It is preferable to use a stirring dryer or the like. The moisture content of the dried toner base is preferably 5% by mass or less, and more preferably 2% by mass or less. In addition, when the toner bases subjected to the drying treatment are aggregated due to weak interparticle attraction, the aggregate may be crushed. Here, as the crushing treatment device, a mechanical crushing device such as a jet mill, a Henschel mixer, a coffee mill, a food processor, or the like can be used.

[External process]
This step is a step in which an external additive is mixed with the dried toner base as necessary to produce a toner.

  As an external additive mixing device, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used.

  The toner contains at least a binder resin, a colorant, and a release agent.

  Next, materials constituting the toner will be described.

(Binder resin)
The binder resin is formed by agglomerating resin particles and then fusing them.

  As the polymerizable monomer constituting the resin particles, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene are used. , P-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn- Styrene or styrene derivatives such as decyl styrene, pn-dodecyl styrene, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate , 2-ethylhexyl methacrylate, stearyl methacrylate Methacrylic acid ester derivatives such as lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, acrylic Acrylates such as isobutyl acid, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, olefins such as ethylene, propylene, isobutylene, vinyl chloride, vinylidene chloride, Halogenated vinyls such as vinyl bromide, vinyl fluoride and vinylidene fluoride, vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate, vinyl methyl ether, vinyl ethyl ether Vinyl ethers such as ether, vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone, N-vinyl compounds such as N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, vinyl naphthalene, vinyl pyridine, etc. Examples include vinyl compounds, acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide. These vinyl monomers can be used alone or in combination.

  Further, it is more preferable to use a combination of monomers having an ionic dissociation group as the polymerizable monomer constituting the resin. For example, it has a substituent such as a carboxyl group, a sulfonic acid group, a phosphoric acid group as a constituent group of the monomer, specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumar Acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxy And propyl methacrylate.

  Furthermore, multifunctional such as divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, etc. It is also possible to use a crosslinkable resin by using a functional vinyl.

  These polymerizable monomers can be polymerized using a radical polymerization initiator. In this case, an oil-soluble polymerization initiator can be used in the suspension polymerization method. Examples of the oil-soluble polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carbohydrate). Nitriles), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo- or diazo-based polymerization initiators such as azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate , 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- Peroxide polymerization initiator or a peroxide such as t- butylperoxy) triazine and the like polymeric initiator having a side chain.

  Moreover, when using 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 salts thereof, and hydrogen peroxide.

(Chain transfer agent)
In order to adjust the molecular weight of the resin, a commonly used chain transfer agent can be used. The chain transfer agent used is not particularly limited. For example, mercaptans such as n-octyl mercaptan, n-decyl mercaptan, tert-dodecyl mercaptan, and mercaptopropionate esters such as n-octyl-3-mercaptopropionate. , Terpinolene, carbon tetrabromide and α-methylstyrene dimer are used.

(Coloring agent)
As the colorant used in the present invention, a known inorganic or organic colorant can be used. Specific colorants are shown below.

  Examples of the black colorant include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.

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

  Examples of the colorant for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. And CI Pigment Yellow 138.

  Examples of the colorant for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15; 2, C.I. I. Pigment blue 15; 3, C.I. I. Pigment blue 15; 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment blue 62, C.I. I. Pigment blue 66, C.I. I. And CI Pigment Green 7.

  These colorants may be used alone or in combination of two or more as required. The addition amount of the colorant is set in the range of 1 to 30% by mass, preferably 2 to 20% by mass with respect to the whole toner.

(Release agent)
The release agent used in the present invention uses the above hydrocarbon wax. When the release agent is contained in an amount of 1 to 20% by mass, preferably 3 to 15% by mass, based on the whole toner, good results can be obtained.

(Charge control agent)
A charge control agent can be added to the toner according to the present invention as necessary. A known compound can be used as the charge control agent.

(External additive)
Examples of inorganic particles that can be used as an external additive include conventionally known particles. Specifically, silica fine particles, titania fine particles, alumina fine particles, and complex oxides thereof can be preferably used. These inorganic particles are preferably hydrophobic.

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

<Developer>
The toner according to the present invention can be used as a one-component developer or a two-component developer.

  When used as a one-component developer, a non-magnetic one-component developer, or a magnetic one-component developer containing about 0.1 μm to 0.5 μm of magnetic particles in the toner can be used. be able to.

  Further, it can be mixed with a carrier and used as a two-component developer. As the carrier, conventionally known magnetic particles such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead can be used. Ferrite particles are particularly preferable. The particle size of the carrier is preferably 20 to 100 μm, and more preferably 25 to 80 μm.

  The particle size 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.

The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The coating resin is not particularly limited, and for example, an olefin resin, a styrene resin, a styrene-acrylic resin, a silicon resin, an ester resin, a fluorine-containing polymer resin, or the like is used. In addition, the resin for constituting the resin-dispersed carrier is not particularly limited, and a known resin can be used. For example, a styrene-acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like is used. be able to. Among these, a coat carrier coated with styrene-acrylic resin is more preferable because it prevents external additives from being detached and ensures durability.
The toner according to the present invention is suitably used for a contact-type fixing type image forming apparatus that fixes a transfer material on which a toner image is formed by passing between heating members constituting the fixing apparatus.

  Hereinafter, the image forming apparatus and the fixing apparatus will be described.

  FIG. 3 is a cross-sectional view showing an example of an image forming apparatus used in the present invention.

  In FIG. 3, 20Y (20M, 20C, 20Bk) is an image forming unit, 21Y (21M, 21C, 21Bk) is a photosensitive drum, 22Y (22M, 22C, 22Bk) is a scorotron charger, and 23Y (23M, 23C, 23Bk). ) Is an exposure optical system, 24Y (24M, 24C, 24Bk) is a developing device, 25Y (25M, 25C, 25Bk) is a cleaning device, 34Y (34M, 34C, 34Bk) is a transfer device, 40 is a fixing device, and 115 is a transfer device. A material conveying belt, 160 is a conveying portion, and P is a transfer material.

  Hereinafter, the image forming apparatus of FIG. 3 will be described.

  In the image forming apparatus of FIG. 3, four sets of image forming units 20 </ b> Y, 20 </ b> M, 20 </ b> C, and 20 </ b> Bk are provided along the transfer material conveyance belt 115.

  Each image forming unit includes a photosensitive drum 21Y (21M, 21C, 21Bk), a scorotron charger 22Y (22M, 22C, 22Bk), an exposure optical system 23Y (23M, 23C, 23Bk), and a developer 24Y (24M, 24C, 24Bk) and a cleaning device (cleaning means) 25Y (25M, 25C, 25Bk), each toner image formed on the photosensitive drum (21Y, 21M, 21C, 21Bk) of each image forming unit is timed. The transfer material (transfer paper, OHP, etc.) P conveyed together is sequentially transferred by a transfer device 34Y (34M, 34C, 34Bk) as transfer means to form a superimposed color toner image.

  The transfer material P is transported on the transfer material transport belt 115, and is a separation member provided in the transport unit 160 at a predetermined interval with a charge eliminating action by a paper separation AC neutralizer 161 as a transfer material separating means. It is separated from the conveyor belt by the claw 210.

  Next, the transfer material P passes through the transport unit 160, and is then transported to a fixing device (fixing unit) 40 including the heating roller 41 and the pressure roller 42, and the heating roller 41 and the pressure roller 42 cause the transfer material P to be transported. The transfer material P is sandwiched by the nip portion T to be formed, and heat and pressure are applied to fix the superimposed toner image on the transfer material P, and then discharged outside the apparatus.

  As the image exposure light source, a scanning optical system using a semiconductor laser, a solid state scanner such as an LED or a liquid crystal shutter, and the like can be used as the exposure means.

  The transfer material transport belt 115 for transporting the transfer material is made conductive by adding a conductive filler such as carbon black to a polymer film such as polyimide, polycarbonate, PVdF, or a synthetic rubber such as silicon rubber or fluorine rubber. Are used, and either a drum shape or a belt shape may be used, but a belt shape is preferable from the viewpoint of the degree of freedom in device design.

  The surface of the transfer belt is preferably appropriately roughened. By setting the 10-point surface roughness Rz of the transfer belt to 0.5 to 2 μm, the adhesion between the transfer material and the transfer belt is improved, and the transfer material is prevented from swinging on the transfer belt. Transferability of the toner image to the toner can be improved.

  The transfer material used in the present invention is a support for holding a toner image and is usually called an image support, a transfer body or a transfer paper. Specifically, various transfer materials such as plain paper from thin paper to thick paper, high-quality 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. 4 is a cross-sectional view showing an example of a fixing device (a type using a pressure roller and a heating roller) used in the present invention.

  The fixing device 10 shown in FIG. 4 includes a heating roller 71 and a pressure roller 72 in contact with the heating roller 71. In FIG. 4, reference numeral 17 denotes a toner image formed on a transfer material (transfer paper) P.

  The heating roller 71 has a coating layer 82 made of a fluororesin or an elastic body formed on the surface of the cored bar 81 and includes a heating member 75 made of a linear heater.

  The cored bar 81 is made of metal and has an inner diameter of 10 to 70 mm. Although it does not specifically limit as a metal which comprises the metal core 81, For example, metals, such as iron, aluminum, copper, or these alloys can be mentioned.

  The thickness of the cored bar 81 is 0.1 to 15 mm, and is determined in consideration of a balance between a request for energy saving (thinning) and strength (depending on the 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 surface of the coating layer 82 include PTFE (polytetrafluoroethylene) and PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer).

  The thickness of the coating layer 82 made of a fluororesin is 10 to 500 μm, preferably 20 to 400 μm.

  When the thickness of the coating layer 82 made of the fluororesin is less than 10 μm, the function as the coating layer cannot be sufficiently exhibited, and the durability as the fixing device cannot be ensured. On the other hand, there is a problem that the surface of the coating layer exceeding 500 μm is easily scratched by paper dust, and toner or the like adheres to the scratched part, thereby causing image smearing.

  Further, as the elastic body constituting the covering layer 82, it is preferable to use silicon rubber, silicon sponge rubber or the like having good heat resistance such as LTV, RTV, HTV.

  The Asker C hardness of the elastic body constituting the covering layer 82 is less than 80 °, preferably less than 60 °.

  The thickness of the coating layer 82 made of an elastic body is preferably 0.1 to 30 mm, and more preferably 0.1 to 20 mm.

  As the heating member 75, a halogen heater can be preferably used.

  The pressure roller 72 is formed by forming a coating layer 84 made of an elastic body on the surface of the cored bar 83. The elastic body constituting the coating layer 84 is not particularly limited, and examples thereof include various soft rubbers such as urethane rubber and silicone rubber, and sponge rubber. The silicon rubber exemplified as the one constituting the coating layer 84 and It is preferable to use silicon sponge rubber.

  Moreover, 0.1-30 mm is preferable and, as for the thickness of the coating layer 84, 0.1-20 mm is more preferable.

  The fixing temperature (surface temperature of the pressure roller 72) is preferably 150 ° C. or less, and the fixing linear velocity is preferably 170 mm / sec. The nip width of the heating roller is set to 8 to 40 mm, preferably 11 to 30 mm.

  The heating roller may be used by applying 0.3 mg or less of silicon oil per print, but may be used without oil.

  FIG. 5 is a schematic view showing an example of a fixing device (a type using a belt and a heating roller) used in the present invention.

  The fixing device 10 in FIG. 5 is of a type using a belt and a heating roller in order to secure a nip width, and the pressure pressed against the fixing roller 601 through the fixing roller 601 and the seamless belt 11 and the seamless belt 11. The pad (pressure member) 12a, the pressure pad (pressure member) 12b, and the lubricant supply member 40 constitute a main part.

  The fixing roller 601 is formed by forming a heat-resistant elastic layer 10b and a release layer (heat-resistant resin layer) 10c around a metal core (cylindrical core) 10a. A halogen lamp 14 is disposed as a heating source. The temperature of the surface of the fixing roller 601 is measured by the temperature sensor 15, and the halogen lamp 14 is feedback controlled by a temperature controller (not shown) based on the measurement signal so that the surface of the fixing roller 601 is adjusted to a constant temperature. The seamless belt 11 is in contact with the fixing roller 601 so as to be wound at a predetermined angle, thereby forming a nip portion.

  Inside the seamless belt 11, a pressure pad 12 having a low friction layer on the surface is disposed in a state of being pressed against the fixing roller 601 via the seamless belt 11. The pressure pad 12 includes a pressure pad 12a to which a strong nip pressure is applied and a pressure pad 12b to which a weak nip pressure is applied, and is held by a holder 12c made of metal or the like.

  Further, a belt traveling guide is attached to the holder 12c so that the seamless belt 11 smoothly slides and rotates. The belt running guide is preferably a member having a low coefficient of friction because it rubs against the inner surface of the seamless belt 11, and a member having low thermal conductivity is preferred so that heat is not easily taken from the seamless belt 11.

<Transfer material>
The transfer material 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.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

<Release agent>
Hydrocarbon waxes “release agents A to J” used as release agents were prepared by thermally decomposing high-pressure polyethylene and fractionating it. The melting point, molecular weight, etc. were adjusted by variously controlling the temperature conditions for thermal decomposition.

  Table 1 shows the release agent type, melting point, and molecular weight.

  In addition, melting | fusing point is the value measured by the said measuring method. The molecular weight is a value measured by gel permeation chromatography (GPC). The peak molecular weight measurement by GPC is carried out using tetrahydrofuran as a solvent and 3 to 4 columns of “Tskel G2000” (exclusion limit 10000) manufactured by Tosoh Corporation.

<Production of toner>
<Preparation of Resin Particle A>
First stage polymerization Into a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe and nitrogen introduction device, 8 g of sodium dodecyl sulfate and 3000 g of ion-exchanged water are charged, and the internal temperature is kept under stirring at a stirring speed of 230 rpm under a nitrogen stream. The temperature was raised to 80 ° C. After heating, 10 g of potassium persulfate dissolved in 200 g of ion-exchanged water was added, the liquid temperature was again 80 ° C., the following monomer mixed solution was added dropwise over 1 hour, and then heated at 80 ° C. for 2 hours. Polymerization was carried out by stirring to prepare resin particles. This is designated as “resin particles (1A)”.

Styrene 532.0g
n-Butyl acrylate 192.0g
Methacrylic acid 76.0g
n-octyl mercaptan 16.0 g
Second stage polymerization A reaction vessel equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen introduction device was charged with a solution of 7 g of polyoxyethylene (2) sodium dodecyl ether sulfate in 800 g of ion-exchanged water and heated to 98 ° C. After heating, 260 g of the resin particles (1A) and a solution obtained by dissolving the following monomer mixed solution at 90 ° C. were added, and a mechanical disperser “CLEARMIX” having a circulation path (M Manufactured by Technic Co., Ltd.) for 1 hour to prepare a dispersion containing emulsified particles (oil droplets).

246.0 g of styrene
n-Butyl acrylate 119.0g
n-Octyl mercaptan 1.5g
Release agent A 190.0g
Next, an initiator solution in which 6 g of potassium persulfate is dissolved in 200 g of ion-exchanged water is added to this dispersion, and the system is heated and stirred at 82 ° C. for 1 hour to obtain resin particles. It was. This is designated as “resin particles (2A)”.

Third stage polymerization Further, a solution prepared by dissolving 11 g of potassium persulfate in 400 g of ion-exchanged water was added to the solution of “resin particles (2A)”, and the temperature was set to 82 ° C.
414.0 g of styrene
n-Butyl acrylate 180.0g
Methacrylic acid 6.0g
n-octyl mercaptan 1.0 g
A monomer mixture consisting of was added dropwise over 1 hour. After completion of the dropping, polymerization was carried out by heating and stirring for 2 hours, and then cooled to 28 ° C. to obtain resin particles. This is designated as “resin particle A”.

(Preparation of resin particle J)
Into a reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen introduction device, 8 g of sodium dodecyl sulfate and 3000 g of ion-exchanged water were charged, and the internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. Allowed to warm. After heating, 10 g of potassium persulfate dissolved in 200 g of ion-exchanged water was added, the liquid temperature was again 80 ° C., the following monomer mixture was added dropwise over 1 hour, and then heated at 80 ° C. for 2 hours. Polymerization was carried out by stirring to prepare resin particles. This is designated as “resin particle J”.

Styrene 570.0g
n-Butyl acrylate 165.0g
Methacrylic acid 70.0g
n-octyl mercaptan 5.5 g
<Preparation of colorant dispersion>
90 g of sodium dodecyl sulfate was dissolved in 1600 g of ion-exchanged water with stirring. While stirring this solution, 420 g of carbon black “Regal 330R” (manufactured by Cabot Corp.) is gradually added, and then dispersed by using a stirrer “Claremix” (manufactured by M Technique Co., Ltd.). A dispersion of agent particles was prepared. This is referred to as a “colorant dispersion”. The particle size of the colorant particles in this colorant dispersion was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.) and found to be 110 nm.

<Production of toner>
<Preparation of Toner Base Bk1>
(Aggregation / fusion process)
In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device, 300 g of “resin particles A” in terms of solid content, 1400 g of ion-exchanged water, 120 g of “colorant dispersion”, polyoxyethylene (2) A solution in which 3 g of sodium dodecyl ether sulfate was dissolved in 120 g of ion-exchanged water was added, the liquid temperature was adjusted to 30 ° C., and the pH was adjusted to 10 by adding a 5N aqueous sodium hydroxide solution. Next, an aqueous solution in which 35 g of magnesium chloride was dissolved in 35 g of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After holding for 3 minutes, the temperature was raised and the system was heated to 90 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 90 ° C.

In this state, the particle size of the associated particles was measured with “Coulter Multisizer III” (manufactured by Beckman Coulter), and when the volume-based median particle size (D ₅₀ ) reached 3.0 μm, “resin 260 g of “particle J” was added, and particle growth was continued as it was. When the volume-based median particle diameter (D ₅₀ ) reached 6.0 μm, an aqueous solution in which 150 g of sodium chloride was dissolved in 600 g of ion-exchanged water was added to stop particle growth, and “associated particles” were obtained.

(Aging process)
By stirring and heating the “associated particles” at a liquid temperature of 90 ° C. for 60 minutes, the shape of the associated particles is adjusted, and at the same time, the particle size, particle size distribution, and shape factor of the release agent are adjusted, and the particles having a core / shell structure are prepared. Produced.

  Thereafter, the solution was cooled to 30 ° C., hydrochloric acid was added to adjust the pH to 4.0, and stirring was stopped.

(Washing and drying process)
The particles produced in the aging step were subjected to solid-liquid separation with a basket-type centrifuge “MARK III model number 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a toner base wet cake. The wet cake was washed with water using the basket-type centrifuge until the electric conductivity of the filtrate reached 5 μS / cm, and then transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). % To dryness to produce “toner base Bk1”.

(Production of toner base Bk2-16)
The “toner base Bk2 to 16” were prepared by changing the release agent used in the preparation of the “toner base Bk1” and the aging process as shown in Table 2.

(Production of toner bases C1 to C16)
“Toner bases C1 to C16” except that 20 g of “Regal 330R” (manufactured by Cabot) used in the production of “toner bases Bk1 to Bk16” was changed to 10 g of “CI Pigment Blue 15: 3”. Was made.

(Production of toner bases M1 to M16)
“Toner bases M1 to M16” were prepared in the same manner except that 20 g of “Legal 330R” (manufactured by Cabot) used in the preparation of “toner bases Bk1 to Bk16” was changed to 17 g of “CI Pigment Red 122”. did.

(Production of toner bases Y1 to Y16)
“Toner bases Y1 to Y16” were prepared in the same manner except that 20 g of “Legal 330R” (manufactured by Cabot) used in the preparation of “toner bases Bk1 to Bk16” was changed to 18 g of “CI Pigment Yellow 74”. did.

The number average particle size, distribution, standard deviation, shape factor, and volume-based median particle size (D ₅₀ ) of “toner bases C1 to C16”, “toner bases M1 to M16”, and “toner bases Y1 to Y16” are as follows. , “Toners Bk1 to Bk16” are the same as and equivalent to those of “Toners Bk1 to Bk16”.

(External additive treatment of toner base)
Next, 1% by mass of hydrophobic silica (number average primary particle size = 12 nm, degree of hydrophobization = 68) and hydrophobic titanium oxide (number average primary particle size = 20 nm, degree of hydrophobization) are prepared on each toner base produced above. = 63) was added in an amount of 1% by mass and mixed using a “Henschel mixer” (manufactured by Mitsui Miike Chemical Co., Ltd.). Thereafter, coarse particles are removed using a sieve having an opening of 45 μm to obtain “toner Bk1 to Bk16”, “toner C1 to C16”, “toner M1 to M16”, and “toner Y1 to Y16”.

Table 2 shows the release agent used for the production of “Toners Bk1 to Bk16”, the temperature and time of the aging process, the number average particle size, the distribution, the standard deviation, the shape factor, and the median particle size (D ₅₀ ) based on volume. Show.

  The release agent dispersion diameter of “Toner Bk16” was measured by a TEM photograph observation method.

  That is, toner particles hardened with an epoxy resin adhesive are cut with a microtome to a width of about 1 μm, and the cut pieces are photographed with a transmission electron microscope (TEM) at a magnification of 5000 times to obtain release agent particles. Measurement was performed on 100 pieces, and the average value was calculated.

The number average particle size, distribution, standard deviation, shape factor, and volume-based median particle size (D ₅₀ ) of “toners C1 to C16”, “toners M1 to M16”, and “toners Y1 to Y16” are “toner”. It is the same as “Bk1 to Bk16” and is omitted.

<Preparation of developer>
To each of the toners prepared above, a ferrite carrier having a volume average particle diameter of 60 μm coated with a silicone resin is mixed so that the concentration of the toner becomes 6% by mass, and “Developers Bk1 to Bk16” and “Developer” are mixed. “Developers C1 to C16”, “Developers M1 to M16”, and “Developers Y1 to Y16”.

<Evaluation>
The following items were evaluated for the toner prepared above. A developer corresponding to each toner was used. In the evaluation, “A” and “B” indicate that there was no problem and “x” indicates that there was a problem, and “B” indicates that there was a problem.

<Aggregation resistance>
2 g of each of the toners prepared above was placed in a sample tube, shaken 500 times with a tapping denser, and allowed to stand in an environment of 55 ° C. and 35% RH for 2 hours. Next, it is put in a 48 mesh sieve, sieved under a constant vibration condition, and the ratio (mass%) of the amount of toner remaining on the mesh is measured, and this is used as the toner aggregation rate. did.

A: The toner aggregation rate is less than 15% by mass (very good aggregation resistance).
A: The toner aggregation rate is 15 to 45% by mass (good aggregation resistance)
X: The toner aggregation rate exceeds 45% by mass (coagulation resistance is poor, and it is necessary to carry out cold transport).

(Image evaluation)
As the image evaluation apparatus, the image forming apparatus shown in FIG. 3 was used, and the fixing apparatus shown in FIG. 5 was mounted. The fixing speed and the surface material of the heat roll were as follows.

Fixing speed: 280mm / sec (about 50 sheets / A4 size, landscape feed)
Heat roll surface material: PTFE
The evaluation was carried out for the following evaluation items in an environment of 20 ° C. and 50% RH by sequentially loading the toner prepared above in the evaluation apparatus.

The print is an image with a pixel rate of 10% (original image with 7% character image, human face photo, solid white image, solid black image divided into 1/4 each), A4 quality fine paper (64g / m ² ).

<Fixing strength>
The fixing strength was set such that the surface temperature of the shimless belt was set to 130 ° C., a 2.54 cm square solid fixed image having a toner adhesion amount of 0.6 mg / cm ² was prepared for all colors, and the solid image portion was 180 °. The evaluation was performed based on the peeled state of the toner image after bending.

◎: Folded toner image has no peeling and good fixing strength ○: Folded toner image has some peeling, but fixing strength has no practical problem ×: Folded toner image peels off and transfer The material is visible and there is a problem with insufficient fixing strength.

<Fixable temperature (mending tape peeling method)>
The fixable temperature was evaluated by changing the surface temperature of the seamless belt 11 from 90 to 150 ° C. in increments of 5 ° C. in an environment of normal temperature and normal humidity (20 ° C., 50% RH) to create a fixed image.

  Specifically, the fixing strength of each of the obtained fixed images was measured by a mending tape peeling method, and the fixing temperature at which a fixing rate of 90% or more was obtained was evaluated as the fixing possible temperature.

  Hereinafter, the mending tape peeling method will be described.

1) Measure absolute reflection density D ₀ of solid black 2) Lightly affix “Mending tape” (manufactured by Sumitomo 3M: No.810-3-12) to a solid black image 3) Tape at a pressure of 1 kPa 4) Peel off the tape with an angle of 180 ° C. and a force of 200 g 5) Measure the absolute reflection density D ₁ after peeling 6) Calculate the fixing rate. Fixing rate (%) = D ₁ / D ₀ × 100
For the measurement of the image density, a reflection densitometer “RD-918” (manufactured by Macbeth) was used.

  Table 3 shows the evaluation results.

As is clear from the evaluation results, “Examples 1 to 5 ” are excellent in all evaluation items, but “Comparative Examples 1 to 5” have some problems in the evaluation items.

FIG. 3 is a schematic cross-sectional view illustrating an example of the toner of the present invention. FIG. 6 is a cross-sectional configuration diagram illustrating an example of conventional (comparative example) toner. It is sectional drawing which shows an example of the image forming apparatus used for this invention. It is sectional drawing which shows an example of the fixing device (The type using a pressure roller and a heating roller) used for this invention. FIG. 2 is a schematic diagram illustrating an example of a fixing device (a type using a belt and a heating roller) used in the present invention.

Explanation of symbols

10 Toner 11 Resin 12 Colorant Particle 13 Release Agent Particle

Claims (3)

In the electrostatic charge image developing toner containing at least a binder resin, a colorant and a release agent, the release agent is a hydrocarbon wax having a melting point of 50 to 100 ° C., and a plurality of the release agents are present in the toner. The number average particle size of the dispersed particles of the release agent in the toner is 1.0 to 1.6 μm in the binder resin dissolution method, the standard deviation is 0.05 to 0.5, and the release agent A toner for developing electrostatic images, wherein the dispersed particles have a shape factor SF-1 of 1.0 to 1.4. The toner for developing an electrostatic charge image according to claim 1, wherein the toner for developing an electrostatic charge image has a core-shell structure produced by an emulsion association method. Among the release agents dispersed in the electrostatic image developing toner according to claim 1, 40 to 90% by number of particles having a number average particle diameter of 1.0 to 2.0 μm are contained. The toner for developing an electrostatic charge image according to claim 1, wherein the toner is for developing an electrostatic image.

Images