JP4233989B2 - Electrostatic image developer - Google Patents

Description

  The present invention relates to an electrostatic charge image developer that can be suitably used in electrophotographic methods, particularly two-component development type copying machines and printers. More specifically, the present invention relates to an electrostatic charge image developer in which the chargeability of a toner is stable, there is no scattering in the developing device, and an image having good image density and no fog is obtained.

  In general, dry development methods used in electrophotography include a two-component development method in which a carrier and a toner are mixed and a one-component development method in which a carrier is not used. Of these, the two-component development method can impart functions such as stirring, transporting, and charging of the developer to the carrier, so that the function sharing with the toner is clear, so that the controllability of the developer performance is good. There are advantages. In particular, a developer using a carrier in which the surface of core particles is coated with a resin is considered to be excellent in charge controllability, and preferable in terms of environmental dependency and stability over time.

On the other hand, since the carrier in the two-component developer is used permanently without being consumed at the time of development, it is indispensable to achieve a long life and high durability. Therefore, conventionally, when using a resin-coated carrier, it is preferable that the carrier has a high coverage, and a developer using a carrier having a resin coverage of 90% or more has been disclosed ( For example, see Patent Document 1 and Patent Document 2.)
Japanese Patent Application Laid-Open No. 5-100492. JP-A-7-234548.

  However, the present inventor has confirmed that a new problem arises when such a high resin coverage carrier is used. Normally, the toner receives a constant charge by contact with the carrier, but due to variations in the toner particle size, circularity, and the amount of external additive attached, the toner particles higher than the average toner charge amount are one. May occur. Such highly charged toner particles have a strong interaction (attraction force) with the carrier, resulting in the result that the toner particles remain attached to the carrier surface, and as a result, the carrier or toner that cannot perform its original function. It turns out that there is a problem that occurs.

In addition, when a carrier having a high resin coverage is used, the physical properties of the carrier (resistance value, charge imparting property, etc.) greatly vary with time due to the peeling of the coating resin, which causes a problem that the image characteristics are not stable.
Furthermore, such a carrier with a high resin coverage is likely to cause an increase in the charge amount when stirring for a long time because there is no portion that leaks the charge, especially when the life of the developer is to be extended, and the charge is high and the developability is poor. It tends to cause toner accumulation. As a result, there is a problem that the quality of the developer is deteriorated due to the strong adhesion of the toner to the carrier, or the in-machine scattering is likely to occur due to insufficient charging of the replenishment toner.

However, in the past, it was clear how the carrier with the excessively charged toner is not covered, the toner is not scattered into the developing device, and an image having a high image density can be stably obtained. There wasn't.
Furthermore, in recent years, there has been a tendency to use a carrier having a smaller particle diameter than before in order to improve image quality, in particular, to obtain a uniform image without unevenness. For example, when a carrier having an average particle diameter of 75 μm or less is used. It has been found that the above-described problems occur more remarkably. However, in the past, even in a two-component developer using a carrier having a relatively small particle size, there is no carrier coating with excessively charged toner, and there is no scattering of toner into the developing device, It was not clear whether an image with high image density could be obtained stably.

  The present invention has been made in view of the above-described prior art. Therefore, the present invention has no toner scattering into the developing device, stable image density and solid uniformity, no fog, and continuous. It is an object of the present invention to provide an electrostatic charge image developer for two-component development, which is capable of forming a stable image since the change with time of these characteristics is small even when printed.

（式中、ｘ＋ｙ＋ｚ＝１００ｍｏｌ％であり、ＭｎＯ、ＭｇＯ及びＦｅ _２ Ｏ _３ の一部がＳｒＯで置換されている） As a result of diligent investigations to solve such problems, the present inventor has used a carrier coated with a resin having a smaller particle size and a specific ratio than a carrier generally used in the past as a carrier used in a two-component developer. Surprisingly, it has been found that the above problems can be solved, and the present invention has been completed.
That is, the gist of the present invention is an electrostatic charge image developer having a toner and a carrier containing at least a binder resin and a colorant, and the carrier has a weight average particle diameter of 75 μm or less, and the following general formula (1 And at least the core particle surface is coated with the coating resin at a ratio of 80% or less, and the toner contains silica fine particles having a number average particle diameter of 20 nm or more. An electrostatic charge image developer characterized by comprising .

(In the formula, x + y + z = 100 mol%, and MnO, MgO and part of Fe ₂ O ₃ are substituted with SrO)

  According to the present invention, as a developer for two-component development, there is no scattering of toner into the developing device, image density and solid uniformity are stable, and these characteristics change over time even when continuously printed. There is provided an electrostatic charge image developer which is small and can form a stable image.

The electrostatic image developer of the present invention has a toner and a carrier containing at least a binder resin and a colorant.
The carrier used in the present invention has at least core particles and a coating resin provided on the surface of the core particles.
The material of the core particle is not limited as long as it functions as a carrier for the two-component developer. However, the core particle is a magnetic substance that exhibits ferrimagnetism or ferromagnetism at a use environment temperature of a copying machine or the like (around 0 ° C to 60 ° C). For example, magnetite (Fe ₃ O ₄ ), maghematite (γ-Fe ₂ O ₃ ), an intermediate between magnetite and maghematite, M _X Fe _{3 -X} O ₄ ;
Spinel ferrite such as Fe, Co, Ni, Cu, Mg, Zn, Cd, Sr or mixed crystals thereof, hexagonal ferrite such as BaO.6Fe ₂ O ₃ , SrO.6Fe ₂ O ₃ , Y ₃ Fe ₅ Garnet type oxides such as O ₁₂ , Sm ₃ Fe ₅ O ₁₂ , Gd ₃ Fe ₅ O ₁₂ , rutile type oxides such as CrO ₂ , iron neodymium oxide (NdFeO ₃ ), iron lanthanum oxide (LaFeO ₃ ), iron oxide Of lead (PbFe ₁₂ O ₁₉ ), iron barium oxide (BaFe ₁₂ O ₁₉ ), or composites thereof, metals such as Fe, Mn, Ni, Co, Cr, and other ferromagnetic alloys, etc., 0 ° C. to 60 ° C. Examples include ferromagnetism and ferrimagnetism in the vicinity, and are not limited to being used alone, but may be used in combination of two or more. Of these, ferromagnetic metals such as iron, cobalt, nickel, lithium and manganese, and alloys and compounds such as magnetite, hematite and ferrite are preferred.

As the core particles, granulated particles can be used as they are, but aggregates obtained by agglomerating particles having a small particle diameter can also be used as the core particles. The particle shape of the magnetic substance is not particularly limited, and may be, for example, a cubic (hexahedron), octahedron, or polyhedron of 10 or more planes, and may be spherical, acicular, scaly, or irregular. It may be.
More preferably, it is desirable that the core particle is a compound represented by the following general formula (1). In this case, the electric resistance of the particles is lowered, and excessive charge of the toner can be appropriately leaked. Further, since the specific gravity of the carrier is reduced, the load on the toner particles is reduced and the life of the developer can be improved.

(In the formula, x + y + z = 100 mol%, and MnO, MgO and part of Fe ₂ O ₃ are substituted with SrO)
In general formula (1), x, y and z are all 0.5 mol% or more, preferably 1 mol% or more, more preferably 3 mol% or more. In particular, 10 to 40 mol% of MnO, MgO and 3~25mol%, it is desirable to Fe ₂ O ₃ are those containing 40~87mol%. Further, preferably 30～75Mol% composition of MnO with respect to Fe ₂ O _3, preferably 4～35Mol% composition of MgO relative to Fe ₂ O _3, the composition of MgO relative to MnO, preferably 12~50mol%.

Furthermore, the amount of SrO substituted in the general formula (1), that is, the ratio of SrO to the total amount of MnO, MgO, Fe ₂ O ₃ and SrO is preferably 0.05 mol% or more, more preferably 0.1 mol%. More preferably, it is 0.3 mol% or more, preferably 5 mol% or less, more preferably 3 mol or less. When the content of SrO in the core particle is in the above range, it is preferable in terms of giving an appropriate magnetic force to the carrier.

Even when the core particle is a compound represented by the general formula (1), it may contain other components as long as the effects of the present invention are not impaired. In addition, the other components also mean components that are contained as impurities of the raw material for producing the core particles and remain in the core particles. Examples of such components include Al ₂ O ₃ , Cr ₂ O ₃ , Ce ₂ O ₃ , NiO, CaO, SiO ₂ , TiO ₂ , Na ₂ O, K ₂ O, Cu, Sn, Zn, Pb, Cb, Mo, V ₂ O, P ₂ O, Cl and the like can be mentioned, and it is usually 5% by weight or less, preferably 2% by weight or less of the core particles.

An example of a method for producing core particles is as follows. First, each oxide having an elemental composition corresponding to a target composition is blended and finely pulverized by a ball mill, a sand mill, a vibration mill or the like in a wet or dry manner. The average particle size of the finely pulverized product at this time is usually 15 μm or less, preferably 5 μm or less, more preferably 2 μm or less. If necessary, a dispersant, an antifoaming agent, a binder or the like is added to the pulverized product and granulated and dried. In the case of wet granulation, usually, a finely pulverized product is made into a slurry and granulated while being heated and dried with a spray dryer or the like. The dispersant, binder, and the like are selected from materials that are decomposed or burned and scattered in a firing step described later and do not adversely affect the generation of core particles. Examples of the binder include polyvinyl alcohol, Polyacrylamide, polycarboxylate, polyisobutylene, alkylnaphthalene sulfonate and the like are used. Note that the binder may be added to the granulated particles after granulation. The granulated and dried product is usually spherical and generally called a granule, and the granule is filled in an alumina container or the like and fired. For the firing of the granules, a tunnel electric furnace or the like is usually used, the firing temperature is usually 900 to 1400 ° C., and the firing time is usually 1 to 30 hours. The atmosphere of the firing process is preferably an inert atmosphere having an oxygen concentration of 0.1% by volume or less, preferably 0.05% by volume or less. In addition, in order to control electric resistance as a carrier, it may be preferable to perform the cooling process after firing in the same inert atmosphere. The shape of the surface of the core particles can be controlled by adjusting the firing temperature. The higher the temperature, the smoother the surface, and the lower the surface, the more uneven the surface. In this firing step, a solid phase chemical reaction occurs to obtain core particles having a desired composition. The fired product thus obtained is crushed and classified to adjust to a desired particle size. Furthermore, saturation magnetization and volume electrical resistance can be adjusted by subjecting the core particles to surface oxidation treatment in the air or under control of oxygen concentration.

  Further, as the core particles, a magnetic material-dispersed resin that is a composite of a magnetic substance and a resin can also be used. The binder resin used for the magnetic material-dispersed resin is not limited. For example, vinyl resins, polyester resins, epoxy resins, phenol resins, urea resins, polyurethane resins, polyimide resins, cellulose resins, polyether resins, and these Mention may be made of mixtures. By using a magnetic material-dispersed resin as the core particles, the affinity with the surface coating resin may be improved, and peeling of the coating resin may be suppressed.

  In the present invention, the resin for coating the surface of the core particles is not limited, but a known resin can be appropriately selected and used depending on the chargeability of a desired developer. For example, polyolefin resin such as polyethylene, polypropylene, chlorinated polyethylene, chlorosulfonated polyethylene, (meth) acrylic resin, styrene resin, styrene- (meth) acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl Polyvinyl and polyvinylidene resins such as butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, and polybiliketones, silicone resins such as vinyl chloride-vinyl acetate copolymer, dimethyl silicone or modified products thereof, polytetrafluoroethylene, polyhexafluoro Fluorine resins such as propylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene, polyamide resins, polyester resins (polyethylene Talates, polycarbonates, etc.), polyurethane resins, polycarbonates, unsaturated polyester resins, urea-formaldehyde resins and other amino resins, epoxy resins, etc., among them styrene resins, styrene- (meth) acrylic resins, A silicone resin or a modified product thereof, or a fluorine resin is preferred. Two or more kinds of the coating resins may be used in combination.

  Among these, particularly when the surface tension γ at 20 ° C. is coated with a resin adjusted to preferably 30 mN / m or less, more preferably 10 to 25 mN / m, the toner adheres firmly to the carrier surface. This is desirable because the durability of the developer may be improved. In this respect, silicone resins such as dimethyl silicone or modified products thereof, and fluorine resins such as polytetrafluoroethylene and polyhexafluoropropylene are preferable, and silicone resins or modified products thereof are particularly preferable. The surface tension can be measured by appropriately selecting from general measuring methods such as Wilhelmi method (plate method), pendant drop method, bubble pressure method, and contact angle method.

  The silicone resin for coating the core particle surface of the carrier is not limited as long as it contains a silicon atom in the main chain skeleton of the molecule. For example, an alkyl group such as a methyl group, an ethyl group, a propyl, or a butyl group, a phenyl group And organopolysiloxane (dimethylsilicone), organopolymetallosiloxane, organopolysilazane, organopolysilmethylene, organopolysilphenylene and the like having an aryl group such as a phenol group, a styryl group and a benzyl group in the side chain. These compounds have side chains or molecular ends, for example, amino groups, epoxy groups, mercapto groups, carboxyl groups, hydroxyl groups, alkoxysilyl groups, carbinol groups, alkoxy groups, alkyl groups, aralkyl groups, polyethers, etc. It may be modified, or may be halogenated and modified such as fluorinated or chlorinated. Furthermore, it may be a block copolymer or graft copolymer composed of a chain containing a silicon atom in the main chain skeleton of the molecule and a chain not containing a silicon atom in the main chain skeleton of the molecule. Among these, dimethylpolysiloxane (dimethylsilicone) or modified dimethylpolysiloxane is preferable. Further, in addition to the linear structure, it may be cyclic or network-like, that is, partially crosslinked.

In the carrier used in the present invention, a conductivity imparting material may be dispersed in the coating resin in order to control the volume resistivity. The conductivity imparting material to be dispersed may be a conventionally known material, and examples thereof include metals such as iron, gold and copper, iron oxides such as ferrite and magnetite, and carbon black.
In addition, the coating resin can contain additives for adjusting the characteristics of the resin coat, such as silica, alumina, carbon black, and fatty acid metal salt, if necessary. A coupling agent such as a silane coupling agent or a titanium coupling agent may be contained for the purpose of improving adhesiveness or improving the dispersibility of the conductivity-imparting agent.

  Among these, it is particularly preferable from the viewpoint of charging stability and durability that a compound represented by the following general formula (1) is used as the core particle and a silicone resin or a modified product thereof is used as the coating resin.

(In the formula, x + y + z = 100 mol%, and MnO, MgO and part of Fe ₂ O ₃ are substituted with SrO)
The carrier used in the present invention is characterized in that the core particle surface is coated with a coating resin at a ratio of 80% or less, preferably 78% or less, more preferably 71% or less. The coverage is usually 20% or more, preferably 30% or more, and more preferably 40% or more. By using a carrier in which the surface of the core particle is coated with a resin in the above range, the charge imparting performance to the toner is good, and generation of excessively charged toner by appropriately leaking the charge can be prevented. It is possible to prevent the deterioration of the developer due to the strong adhesion of the toner to the surface and the scattering due to the charging failure of the replenishing toner. As a result, since the toner in contact with the carrier is constantly updated, the carrier can impart an appropriate amount and stable chargeability to the toner, and good image formation can be performed. This is presumably because the surface of the core particles in the carrier is coated with an appropriate amount of the resin as described above, so that it has both a portion that retains charge and a portion that leaks excessive charge.

As a method for setting the resin coverage on the surface of the core particles in the above range, for example, it can be achieved by optimizing the coating conditions described later.
The coverage of the resin covering the surface of the core particle is determined by the following. First, the carrier particle is reflected by a scanning electron microscope (SEM). And is photographed at a magnification such that 10 to 25 carriers fit on one screen, and the obtained photograph is used with an image analyzer, for example, WinR00F manufactured by Mitani Corporation. It shall be calculated by analyzing as follows. The image of the carrier particle part is divided into 256 gradation contrasts, and the areas of the exposed part of the core particle and the resin-coated part are obtained with 70 gradations from the dark side as a boundary, and the total area of the carrier on the image is calculated. The ratio of the area of the coating resin portion was defined as the coverage (%). An average value of at least 5 points per sample was used.

  The core particle part and the coating resin part divided by the difference in contrast are confirmed by elemental composition and molecular structure by measuring, for example, micro infrared spectroscopy (micro IR), micro Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), etc. , It can be identified as a corresponding part. Note that image contrast adjustment is not performed in, for example, an image capturing device or an analysis device other than SEM observation conditions (diaphragm, acceleration voltage, etc.) and photography conditions (time, etc.).

The coating method of the coating resin on the surface of the core particles is appropriately selected from conventionally known methods such as mechanical mixing method, spraying method, dipping method, fluidized bed method, rolling bed method and the like. I can do it.
The coating resin can be melted directly on the core particle surface for coating, or a thermosetting monomer can be directly polymerized on the core particle surface for coating, but it can be dissolved in an organic solvent. Or it is common to coat | cover by disperse | distributing the coating resin solution to the surface of the core particle, and distilling a solvent off. As a method of coating by distilling off the solvent, a method of coating by spraying a resin solution while using a fluidized bed coating apparatus while floating the core particles, and a spraying method (spray drying method) are particularly suitable. is there. Examples of the solvent include aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as trichloroethylene and perchloroethylene, ketones such as acetone and methyl ethyl ketone, cyclic ethers such as tetrahydrofuran, methanol, and ethanol. And alcohols such as isopropanol.

  When the coating rate is adjusted to the above range by applying a coating resin dissolved or dispersed in an organic solvent or the like to the surface of the core particle and distilling off the solvent, the optimal condition depends on the type and mechanism of the device used, the type of solvent, etc. Although the conditions are different, it can be achieved by appropriately setting and adjusting the resin concentration in the solvent, the ratio of the resin amount to the carrier, the temperature and time of solvent evaporation, the method of solvent evaporation, and the like.

  The carrier used in the present invention is not limited in the coating amount of the resin, but is usually 0.05% by weight or more, preferably 0.1% by weight or more in the carrier, usually 20% by weight or less, preferably 10% by weight or less. It is desirable that The amount of the coating resin can be confirmed by the amount of carbon dioxide when the carrier is burned using a total carbon concentration meter (manufactured by Horiba, Ltd.). In the case of using a magnetic material-dispersed resin as the core particle, it can be confirmed by analyzing the resin component after dissolving the carrier in an organic solvent or the like.

  The carrier used in the present invention has a weight average particle diameter of 75 μm or less, preferably 70 μm or less, more preferably 65 μm or less, and further preferably 60 μm or less. Moreover, it is usually 20 μm or more, preferably 25 μm or more, more preferably 30 μm or more. By setting the weight average particle diameter of the carrier in the above range, the uniformity of the image can be improved. Here, the weight average particle diameter of the carrier is measured by a laser diffraction method (for example, Loss & Rhodes, Sympatex).

The carrier content in the developer of the present invention is not limited, but is usually 70 parts by weight or more, preferably 80 parts by weight or more, more preferably 90 parts by weight or more, and usually 99 parts by weight with respect to 100 parts by weight of the developer. Hereinafter, it is preferably 97 parts by weight or less.
The carrier used in the present invention has a saturation magnetization in a magnetic field of 23 ° C. and 7.96 × 10 ⁴ A / m (= 1000 Oe) usually 30 to 150 Am ² / kg, preferably 50 to 90 Am ² / kg. Preferably, the magnetic binding force of the developer to the developing sleeve in the developing region is increased by setting the speed to 55 to 70 Am ² / kg, so that the development of the carrier on the photosensitive member is effectively prevented and a good image is obtained. can get.

Further, the carrier used in the present invention has an electric resistance at 25 ° C. of usually 10 ⁵ Ω or more,
Preferably it is 10 ⁶ Ω or more, usually 10 ¹¹ Ω or less, preferably 10 ¹⁰ Ω or less.
It is desirable that the electric resistance of the carrier is in the above range because image uniformity is improved and charging of the developer is stabilized. In addition, although a general method can be used for the measurement of electrical resistance, it was as follows in this invention. That is, in an environment of 25 ° C. and 60% RH, 5 g of a measurement substance is placed in a cylindrical measurement cell having an inner diameter of 2 cm, and the measurement substance is sandwiched between two electrodes having an electrode area of 3.14 cm ^{2 and is} placed in the direction of gravity. A DC voltage of 1000 V was applied from above the upper electrode using a weight with a weight of 1 kg, and the resistance value was measured with an insulation resistance meter and converted into a volume resistivity value.

The toner used in the present invention contains at least a binder resin and a colorant, and if necessary, external additive fine particles adhere to toner base particles containing wax, a charge control agent, other additives, and the like. It has been done.
As the binder resin constituting the toner, various known resins suitable for the toner can be used. For example, styrene resin, polyester resin, epoxy resin, polyurethane resin, vinyl chloride resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, silicone resin, rosin-modified maleic acid resin, phenol resin, ketone resin, ethylene-ethyl acrylate There are a copolymer, a xylene resin, a polyvinyl butyral resin, and the like. Preferred resins for use in the present invention include styrene resins and polyester resins.

  These resins are not limited to being used alone, but two or more of them can be used in combination. Further, the binder resin in the present invention can be used as a non-crosslinked resin, a crosslinked resin, or a mixture thereof depending on the fixing method of the image forming apparatus. As a method for producing the binder resin, there are bulk polymerization, solution polymerization, interfacial polymerization, suspension polymerization, emulsion polymerization and the like, but they can be used regardless of the polymerization method.

  Examples of styrene resins include polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene- Vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, Styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-acrylic ester-acrylic acid copolymer (styrene-methyl acrylate-acrylic acid copolymer, styrene-ethyl acrylate- Acrylic acid copolymer, styrene-butyl acrylate Acrylic acid copolymer, styrene-octyl acrylate-acrylic acid copolymer, styrene-phenyl acrylate-acrylic acid copolymer, etc.), styrene-acrylic acid ester-methacrylic acid copolymer (styrene-methyl acrylate- Methacrylic acid copolymer, styrene-ethyl acrylate-methacrylic acid copolymer, styrene-butyl acrylate-methacrylic acid copolymer, styrene-octyl acrylate-methacrylic acid copolymer, styrene-phenyl acrylate-methacrylic acid Copolymer), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-octyl methacrylate copolymer). , Styrene-phenyl methacrylate copolymer ), Styrene-methacrylic acid ester-acrylic acid copolymer (styrene-methyl methacrylate-acrylic acid copolymer, styrene-ethyl methacrylate-acrylic acid copolymer, styrene-butyl methacrylate-acrylic acid copolymer) Styrene-octyl methacrylate-acrylic acid copolymer, styrene-phenyl methacrylate-acrylic acid copolymer, etc.), styrene-methacrylic acid ester-methacrylic acid copolymer (styrene-methyl methacrylate-methacrylic acid copolymer) Styrene-ethyl methacrylate-methacrylic acid copolymer, styrene-butyl methacrylate-methacrylic acid copolymer, styrene-octyl methacrylate-methacrylic acid copolymer, styrene-phenyl methacrylate-methacrylic acid copolymer, etc.) , Styrene-α-Chloracryl Methyl methacrylate copolymer and styrene - acrylonitrile - homopolymers or copolymers containing styrene or styrene derivatives such as acrylic acid ester copolymer. These may be a mixture thereof.

  Among them, styrene-acrylic acid ester copolymer, styrene-acrylic acid ester-acrylic acid copolymer, styrene-acrylic acid ester-methacrylic acid copolymer, styrene-methacrylic acid ester copolymer, styrene-methacrylic acid ester- At least one binder resin selected from an acrylic acid copolymer and a styrene-methacrylic acid ester-methacrylic acid copolymer is excellent in terms of toner fixing property and durability, and also has toner charge stability. (Especially negative chargeability) is improved, which is more preferable. In addition, although the ester group in acrylic acid ester or methacrylic acid ester is not limited, methyl ester, ethyl ester, butyl ester, octyl ester, phenyl ester, etc. are mentioned.

  As the polyester-based resin, those obtained by polycondensation of a polyhydric alcohol component and a polyvalent carboxylic acid component are preferable. Among the polyhydric alcohol components, examples of the dihydric alcohol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1 , 4-Butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polytetramethylene glycol and other diols, bisphenol A, hydrogenated bisphenol A, etherified bisphenols such as polyoxyethylenated bisphenol A and polyoxypropylenated bisphenol A, and other alcohol monomers, and those containing bisphenol A are preferred. It is use.

  Among the polyvalent carboxylic acid components, examples of the divalent carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, and diphenic acid. , Cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, n-dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic acid, isododecyl succinic acid, n-octenyl succinic acid, isooctenyl succinic acid Examples include acids, n-octyl succinic acid, isooctyl succinic acid, and anhydrides or lower alkyl esters of these acids. Among them, those containing isophthalic acid are preferably used.

  Moreover, it is preferable that the binder resin in the present invention contains a trivalent or higher alcohol component and / or a trivalent or higher carboxylic acid component. Examples of the trivalent or higher alcohol component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol. 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, etc. Is mentioned.

  Examples of the trivalent or higher carboxylic acid component include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid, naphthalenetricarboxylic acid, butanetricarboxylic acid, hexanetricarboxylic acid, 1 , 3-dicarboxyl-2-methyl-2-methylenecarboxypropane, cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, octanetetracarboxylic acid, pyromellitic acid, embol dimer acid, and anhydrides of these acids, And lower alkyl esters.

  When using these trihydric or higher alcohol components and / or trihydric or higher carboxylic acid components, it is preferably contained in an amount of 0.01 to 30 mol% in all monomers constituting the polyester resin. When a trivalent or higher valent alcohol component and / or a trivalent or higher carboxylic acid component is included, the low temperature fixability required for low energy fixing and the durability required for image stability during continuous shooting are both preferable. There is.

  Furthermore, monofunctional alcohols and monofunctional carboxylic acids such as benzoic acid, salicylic acid, myristic acid, palmitic acid and stearic acid can also be included. Moreover, it can also have a urethane bond in the structure of a polyester resin, and can obtain it by using a diisocyanate compound etc. as a raw material. By having a urethane bond, the durability of the toner may be improved.

  When the binder resin is a polyester resin, the acid value thereof is preferably 2 to 50 KOHmg / g, more preferably 3 to 30 KOHmg / g. When the acid value is less than the above range, the dispersibility of the colorant, the charge control agent and the like may be lowered. When the acid value exceeds the above range, the toner charge amount stability may be impaired. The acid value of the polyester resin can be calculated from a value obtained by dissolving a resin sample in a solvent such as toluene and titrating it with an indicator.

  The softening point (hereinafter referred to as Sp) of the binder resin is usually 150 ° C. or lower, preferably 140 ° C. or lower, for low energy fixing. The Sp is preferably 80 ° C. or higher, and more preferably 100 ° C. or higher from the viewpoint of high temperature offset resistance and durability. Here, the Sp is a flow tester (CFT-500 manufactured by Shimadzu Corporation), in which 1.0 g of a sample is a nozzle 1 mm × 10 mm, a load of 30 kg, a preheating time of 50 ° C. for 5 minutes, and a heating rate of 3 ° C./minute. Can be obtained as the temperature at the midpoint of the strand from the start to the end of the flow.

  The glass transition point (hereinafter referred to as Tg) of the binder resin is usually 65 ° C. or lower, preferably 60 ° C. or lower, for low energy fixing. The Tg is preferably 35 ° C. or higher, more preferably 50 ° C. or higher from the viewpoint of blocking resistance. Here, the Tg is obtained by drawing a tangent line at the start of transition (inflection) of a curve measured at a temperature rising rate of 10 ° C./min in a differential scanning calorimeter (DTA-40 manufactured by Shimadzu Corporation). It can be determined as the temperature of the intersection of

The Sp and Tg of the binder resin in the present invention can be adjusted to the above range by adjusting the type and composition ratio of the resin, the molecular weight, and the like. Can be used.
When the styrenic resin is used as the binder resin, the binder resin has a number average molecular weight in gel permeation chromatography (hereinafter referred to as GPC) of preferably 2,000 or more, more preferably 2,500 or more, and even more preferably. Is 3,000 or more, preferably 50,000 or less, more preferably 40,000 or less, and further preferably 35,000 or less. Further, the binder resin has a weight average molecular weight obtained in the same manner of preferably 50,000 or more, more preferably 100,000 or more, further preferably 200,000 or more, preferably 2 million or less, more preferably 1 million. In the following, it is more desirable that it is 500,000 or less. When the number average molecular weight and the weight average molecular weight of the styrenic resin are in the above ranges, the durability, storage stability, and fixability of the toner are improved.

  The binder resin is preferably composed of a low molecular weight body and a high molecular weight body. Among the peak molecular weights in GPC, the molecular weight of the low molecular weight body is preferably 10,000 or less, more preferably at least one in 3000 to 7000. It has a peak, and the molecular weight of the high molecular weight body is preferably 100,000 or more, more preferably at least one molecular weight peak at 200,000 to 1,000,000. When the peak molecular weight by GPC of the styrene resin is in the above range, it is desirable because the durability, storage stability, and fixing property of the toner become good. Here, as the peak molecular weight, a value converted to polystyrene is used, and components insoluble in a solvent are excluded in measurement.

  The colorant used in the present invention is not particularly limited, and various inorganic and organic dyes and pigments generally used as a toner colorant are used. Specifically, for example, iron Powder, metal powder such as copper powder, metal oxide such as bengara, inorganic pigment such as carbon represented by carbon black such as furnace black and lamp black, azo type such as benzidine yellow and benzidine orange, quinoline yellow, Acid dyes, basic dyes such as alkali blues, precipitates of rhodamine, magenta, macalite green, etc. dyes such as tannic acid, phosphomolybdic acid, etc. Acid dyes, basic dyes, metal salts of hydroxyanthraquinones Mordant dyes such as phthalocyanine blue, phthalocyanine series such as copper phthalocyanine sulfonate Organic pigments such as quinacridone red and quinacridone violet, organic pigments such as quinacridone and dioxane, aniline black, azo dyes, naphthoquinone dyes, indigo dyes, nigrosine dyes, phthalocyanine dyes, polymethine dyes, di- and triallylmethane dyes, etc. These can be used in combination.

  Colorants used in full-color toners include yellow azo pigments (insoluble monoazo, insoluble disazo, condensed azo, etc.), polycyclic pigments (isoindoline, isoindolinone, slen, quinophthalone, etc.) Azo pigments (azo lakes, insoluble monoazos, insoluble disazos, condensed azos, etc.), polycyclic pigments (quinacridone pigments, perylene pigments, etc.) and the like for magenta Examples include phthalocyanine pigments and selenium pigments. The combination of the colorants may be appropriately selected in consideration of the hue and the like. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. At least one selected from CI Pigment Yellow 155 is C.I. I. Pigment red 238, C.I. I. Pigment red 269, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 48: 2, C.I. I. At least one selected from CI Pigment Red 122 is C.I. I. Pigment blue 15, C.I. I. At least one selected from CI Pigment Blue 15: 3 is preferable as furnace black carbon as the black colorant.

The content of the colorant is preferably 1 to 20 parts by weight, more preferably 2 to 15 parts by weight, and particularly 3 to 10 parts by weight with respect to 100 parts by weight of the binder resin. Is good. When two or more colorants are used in combination, the total amount is preferably within the above range.
The colorant may have magnetism, and the magnetic colorant is a magnetic substance that exhibits ferrimagnetism or ferromagnetism at a use environment temperature (around 0 ° C. to 60 ° C.) of a copying machine or the like. For example, magnetite (Fe ₃ O ₄ ), maghemite (γ-Fe ₂ O ₃ ), an intermediate between magnetite and maghematite, M _X Fe _{3 -X} O ₄ ; where M is Mn, Fe, Co, Ni, C
Spinel ferrite such as u, Mg, Zn, Cd, etc. or mixed crystals thereof, hexagonal ferrite such as BaO.6Fe ₂ O ₃ , SrO.6Fe ₂ O ₃ , Y ₃ Fe ₅ O ₁₂ , Sm ₃ Fe ₅ O ₁₂ , Gd ₃ F
garnet-type oxides such as e ₅ O _12, rutile-type oxide such as CrO _2, iron oxide neodymium (NdFeO _3), iron oxide, lanthanum (LaFeO _3), oxide Tetsunamari (PbFe ₁₂ O _19), barium iron oxide ( BaFe ₁₂ O ₁₉ ) or composites thereof, metals such as Fe, Mn, Ni, Co, and Cr, and other ferromagnetic alloys, etc. exhibiting ferromagnetism and ferrimagnetism around 0 ° C. to 60 ° C. It is mentioned, It can also use together 2 or more types not only using alone. Among these, magnetite, maghematite, an intermediate between magnetite and maghematite, and the like are preferable.
The shape of the magnetic particles is not limited, and may be, for example, a cubic (hexahedron), octahedron, or polyhedron of 10 or more planes, and may be spherical, acicular, scaly, or irregular. There may be. When added from the viewpoint of preventing scattering and charging control while maintaining the characteristics as a non-magnetic toner, the addition amount is usually 0.5 to 10 parts by weight, preferably 0, relative to 100 parts by weight of the binder resin. 0.5 to 8 parts by weight, more preferably 1 to 5 parts by weight.

In order to add conductivity to the toner in the present invention, conductive carbon black as the colorant component and other conductive materials may be added. The addition amount of the conductive substance is usually preferably about 0.05 to 15 parts with respect to 100 parts by weight of the binder resin, and the addition amount may be adjusted in accordance with the desired toner conductivity.
The toner used in the present invention may further contain other components if desired. For example, when it is desired to impart chargeability to the toner, a known positively or negatively chargeable charge control agent may be used alone or in combination. The charge control agent is not limited. Examples of the positive charge control agent include negatively charged charge control agents such as nigrosine dyes, quaternary ammonium salts, triaminotriphenylmethane compounds, imidazole compounds, and polyamine resins. Examples thereof include metal-containing azo dyes such as Cr, Co, Al, and Fe, salicylic acid metal compounds, curixarene compounds, and alkylsalicylic acid metal compounds. Also in the selection of the charge control agent, it is preferable to use one that does not contain volatile impurities as much as possible.

  The amount of the charge control agent used varies depending on the target charge amount, but is usually 0.05 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the binder resin. If the content of the charge control agent is less than the above range, an effect of improving the chargeability cannot be expected. If the content exceeds the above range, a free charge control agent is generated, and the chargeability of the toner is reduced, and fogging or the like is caused. It may be a cause.

  The toner used in the present invention may contain a wax in order to improve characteristics such as offset resistance. Examples of such wax include polyethylene wax, polypropylene wax, paraffin wax, carnauba wax, rice wax, sazol wax, montan ester wax, Fischer-Tropsch wax, higher fatty acid, fatty acid amide, metal soap, etc. Two or more of these can also be used in combination.

The content of the wax is usually 0.1 to 30 parts by weight, preferably 0.5 to 15 parts by weight, with respect to 100 parts by weight of the binder resin. Since it can improve, it is preferable.
The wax can also be contained in advance in the binder resin. By including the wax in the binder resin, the dispersibility of the wax in the toner base particles is improved, and the offset resistance may be improved.

The toner in the present invention may contain other additives. Examples thereof include silicon oil, fluorine-based oil, low molecular weight polyolefin, paraffins, and the like, and a plurality of these may be used in combination.
The method for producing the toner base particles used in the present invention is not limited, and any production method such as a pulverization method, a polymerization method such as a suspension polymerization method or an emulsion polymerization aggregation method, or a solvent precipitation method can be used.

  When the toner base particles in the present invention are produced by a pulverization method, it can be carried out according to a conventionally known method. That is, usually, first, a binder resin, a colorant, and other components such as a charge control agent and wax added as needed are uniformly dispersed and mixed by a mixer, and then the mixture is sealed in a kneader or uniaxial or biaxial. Melt and knead with a shaft extruder, etc., cool, coarsely pulverize with a crusher, hammer mill, etc., then finely pulverize with a jet mill, high-speed rotor rotary mill, etc., and wind classifier (for example, inertia class elbow jet The toner base particles are obtained by a method of classification using a centrifugal classification microplex, DS separator, or the like.

When the toner base particles in the present invention are produced by the suspension polymerization method, it can be carried out according to a conventionally known method. That is, the disperser usually contains a polymerizable monomer, a polymerization initiator, a colorant, and other components such as a charge control agent and a wax that are added as necessary in the aqueous medium. After dispersing and dispersing to an appropriate particle size using a dispersing machine such as the above, the polymerizable monomer is polymerized to obtain toner mother particles.

  Further, when the toner base particles in the present invention are produced by an emulsion polymerization aggregation method, it can be carried out according to a conventionally known method. That is, usually, the polymerizable monomer constituting the binder resin is emulsified in an aqueous medium containing a polymerization initiator, an emulsifier, and optionally other components such as wax, and the polymerizable monomer is stirred. First, a polymer primary particle emulsion is produced, and then, the resulting polymer primary particle emulsion is added with a colorant and other components such as a charge control agent and wax added as necessary. The polymer primary particles are added to aggregate to form primary particle aggregates, and the primary particle aggregates are aged by heating to produce toner base particles.

Furthermore, the toner base particles obtained by the suspension polymerization method or the emulsion polymerization aggregation method can be coated with a resin to form a capsule toner.
The weight average particle diameter of the toner base particles thus obtained is preferably 4 to 15 μm, more preferably 6 to 11 μm. Here, the particle size can be measured using a multisizer (manufactured by Coulter).

After these steps, it is preferable to add externally added fine particles to the toner base particles in order to improve fluidity, charging stability, anti-blocking property at high temperature, and the like. The externally added fine particles to be externally added to the surface of the toner base particles can be appropriately selected from various inorganic or organic fine particles.
Examples of inorganic fine particles include silicon carbide, boron carbide, titanium carbide, zirconium carbide, hafnium carbide, vanadium carbide, tantalum carbide, niobium carbide, tungsten carbide, chromium carbide, molybdenum carbide, calcium carbide, and other carbides, boron nitride, titanium nitride. Various nitrides such as zirconium nitride and silicon nitride, various borides such as zirconium boride, various oxides such as titanium oxide, calcium oxide, magnesium oxide, zinc oxide, copper oxide, aluminum oxide, cerium oxide, silica and colloidal silica , Various titanate compounds such as calcium titanate, magnesium titanate, strontium titanate, phosphate compounds such as calcium phosphate, sulfides such as molybdenum disulfide, fluorides such as magnesium fluoride and fluorocarbon, aluminum stearate , Various metal soaps such as calcium stearate, zinc stearate, and magnesium stearate, talc, bentonite, various carbon blacks and conductive carbon blacks, magnetic particles that can be used as the colorant, and the like can be used. As the organic fine particles, fine particles such as styrene resin, acrylic resin, epoxy resin, and melamine resin can be used.

  Among these externally added fine particles, silica, titanium oxide, alumina, zinc oxide, various carbon blacks and conductive carbon black are particularly preferably used. Further, the externally added fine particles are obtained by applying the surface of the inorganic or organic fine particles to a silane coupling agent, a titanate coupling agent, a silicone oil, a modified silicone oil, a silicone varnish, a fluorine silane coupling agent, a fluorine silicone oil, What has been subjected to surface treatment such as hydrophobization with a treating agent such as a coupling agent having an amino group or a quaternary ammonium base can also be used. Two or more kinds of the treatment agents can be used in combination.

The inorganic or organic fine particles have a number average particle size of usually 0.001 to 3 μm, preferably 0.005 to 1 μm, and a plurality of particles having different particle sizes can be blended. The average particle diameter of the externally added fine particles can be determined by observation with an electron microscope.
In addition, the inorganic or organic fine particles may be used in combination of two or more different types, such as using a surface-treated and non-surface-treated one or a combination of different surface-treated ones. In addition, a positively chargeable one and a negatively chargeable one can be used in appropriate combination.

  The total amount of the externally added fine particles is usually 0.1 parts by weight or more, preferably 0.3 parts by weight or more, more preferably 0.5 parts by weight or more, and usually 10 parts by weight with respect to 100 parts by weight of the toner base particles. Hereinafter, it is preferably 6 parts by weight or less, more preferably 4 parts by weight or less. When the total amount of the externally added fine particles is within the above range, the charging stability and fluidity of the toner may be improved, which is preferable.

  The toner used in the developer of the present invention works most suitably in terms of image density and charging stability when it has externally added fine particles having a number average particle diameter of 20 nm or more. As the external additive fine particles having a number average particle diameter of 20 nm or more, those according to the purpose can be appropriately used from among the external additive fine particles, and silica is preferably used among them. In order to make the effect of the externally added fine particles more effective, the additive amount of the externally added fine particles having a number average particle diameter of 20 nm or more is 0.4% by weight or more, preferably 0.7% by weight or more based on the toner. Preferably it is 0.9 weight% or more.

  As a method for externally adding the externally added fine particles to the toner base particles, for example, mixing is performed by using a mixer such as a Henschel mixer, a super mixer, a nauter mixer, a V-type mixer, a double cone mixer, or a drum type mixer. The Among them, it is preferable to use a high-speed agitation type mixer such as a Henschel mixer or a super mixer, and appropriately stir and mix by appropriately setting the blade shape, the number of revolutions, the time, the number of times of driving and stopping, and the like.

  It can also be fixed by a device that can apply compressive shear stress or a device that can melt the particle surface. The compression shearing apparatus generally has a narrow gap composed of a head surface and a head surface, a head surface and a wall surface, or a wall surface and a wall surface that move relative to each other while maintaining a gap. By forcibly passing through the gap portion, compressive stress and shear stress are applied to the particle surface without being substantially pulverized. Examples of the compression shearing apparatus used include a mechanofusion apparatus manufactured by Hosokawa Micron Corporation. In general, the particle surface melting apparatus is configured so that a mixture of base fine particles and externally added fine particles can be instantaneously heated to a melting start temperature of the base fine particles or higher by using a hot air stream or the like to fix the externally added fine particles. Examples of the particle surface melting apparatus used include a surfing system manufactured by Nippon Pneumatic Co., Ltd.

The toner used in the present invention thus obtained has a weight average particle diameter of preferably 4 to 15 μm, more preferably 6 to 11 μm.
The Sp used in the toner of the present invention is usually 150 ° C. or lower, preferably 140 ° C. or lower, for low energy fixing. Further, the Sp is preferably 80 ° C. or higher, preferably 100 ° C. or higher from the viewpoint of high temperature offset resistance and durability. The Tg of the toner is usually 65 ° C. or lower, preferably 60 ° C. or lower, for low energy fixing. The Tg is preferably 35 ° C. or higher, more preferably 50 ° C. or higher from the viewpoint of blocking resistance.

  Since the Sp and Tg of the toner used in the present invention are greatly affected by the type and composition ratio of the binder resin, it can be adjusted by optimizing it appropriately. It can also be adjusted by the type and blending amount of low melting point components such as wax. In addition, the binder resin used for setting the Sp and Tg of the toner in the present invention in the above ranges can be appropriately selected from commercially available resins.

The charging characteristics of the toner may be negatively charged or positively charged, and can be set according to the system of the image forming apparatus using the developer of the present invention. The charging characteristics of the toner can be adjusted by the selection and composition ratio of toner base particle components such as a charge control agent, the selection and composition ratio of externally added fine particles, and the like.
The electrostatic charge image developer of the present invention is obtained by mixing at least the toner and the carrier with a V-type mixer, a ball mill, or the like, and a good image is obtained when used in an image forming apparatus of a two-component development system. It is done.

  In the image forming method using the electrostatic image developer of the present invention, the developing method is not limited, and may be contact development or non-contact development, but the contact development method is preferable. The structure of the photoreceptor is not limited, and may be a belt type or a drum type. Also, the material of the photoreceptor is not limited and may be an inorganic compound or an organic compound, but an organic photoreceptor is preferred.

In the image forming method using the electrostatic charge image developer of the present invention, there is no limitation on the transfer method and the fixing method, but thermocompression fixing is preferable.
The electrostatic image developer of the present invention can be suitably used for any development using black toner, color toner, and full color toner.
As described above, since the electrostatic charge image developer of the present invention has good toner charge amount stability, there is no scattering of toner into the developing device as a developer for two-component development, and image density and solidity. Uniformity is stable, and it has excellent performance that stable image formation is possible even when continuous printing is performed.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples unless it exceeds the gist. “Parts” means “parts by weight” unless otherwise specified.
[Manufacture of carriers]
<Carrier 1>
A resin solution in which a dimethyl silicone resin is dissolved in a toluene solvent is flowed with respect to core particles having a composition of a weight average particle size of 70 μm, MnO 23 mol%, MgO 3.5 mol%, SrO 0.5 mol%, Fe ₂ O ₃ 73 mol%. The core material was coated on the floor and then baked at 250 ° C. for about 3 hours to obtain a carrier 1 having a resin coverage of 77.9%. The saturation magnetization of the carrier 1 was 66 Am ² / kg, and the electric resistance at 25 ° C. was 1 × 10 ⁸ Ω. An observation example of the carrier 1 with an electron microscope is shown in FIG.
<Carrier 2>
Carrier 2 was obtained with the same composition as carrier 1 except that the amount of the resin solution relative to the core particles was changed and the resin coverage was 70.2%. The saturation magnetization of the carrier 2 is 66 Am ² / kg,
The electric resistance at 25 ° C. was 8 × 10 ⁷ Ω.
<Carrier 3>
Carrier 3 having the same composition as that of carrier 1 was obtained except that the amount of the resin solution relative to the core particles was changed and the resin coverage was 82.8%. The saturation magnetization of the carrier 3 is 63 Am ² / kg,
The electric resistance at 25 ° C. was 4 × 10 ⁸ Ω.
<Carrier 4>
Carrier 4 was obtained by the same production method as carrier 1 except that the weight average particle size was 60 μm. The resin 4 coverage of the carrier 4 was 75.4%, the saturation magnetization was 66 Am ² / kg, and the electric resistance at 25 ° C. was 2 × 10 ⁸ Ω.
<Carrier 5>
Carrier 5 was obtained by the same production method as carrier 1 except that the weight average particle size was 80 μm. The resin coverage of the carrier 5 was 85.1%, the saturation magnetization was 65 Am ² / kg, and the electric resistance at 25 ° C. was 3 × 10 ⁸ Ω.
<Carrier 6>
Carrier 6 was obtained by the same production method as carrier 1 except that core particles having a composition of MnO 35 mol%, MgO 14.5 mol%, SrO 0.5 mol%, and Fe ₂ O ₃ 50 mol% were used. The resin coverage of the carrier 4 was 77.0%.
<Example 1>
After mixing 100.0 parts of binder resin, 10 parts of colorant, 1 part of wax, and 2 parts of charge control agent using a Henschel mixer, as shown below, a twin-screw kneader (manufactured by Ikegai Co., Ltd.) PCM-30), and pulverized and classified with a jet mill to obtain toner base particles having an average particle size of 8.0 μm.

Binder resin: terephthalic acid, isophthalic acid, bisphenol A (propylene
Oxide adduct and ethylene oxide adduct)
Polyester resin
(Non-crosslinked, weight average molecular weight 14,000, number average molecular weight 2600,
(GPC peak: 8000, Sp = 110 ° C., Tg = 64 ° C.)
Colorant: Pigment Blue PB15: 3 40% master batch processed product Wax: Polyethylene wax (Hoechst PE130)
・ Charge control agent: metal complex of salicylic acid (negative charge)
To 100.0 parts of the obtained toner base particles, 0.5 part of the external additive fine particles 1 and 0.3 part of the external additive fine particles 2 shown below were mixed using a Henschel mixer to obtain a toner. The amount of externally added fine particles having a particle diameter of 20 nm or more in the toner was 0.57% by weight, and the toner had a Sp of 110 ° C. and a Tg of 65 ° C.

External fine particle 1: Silica (manufactured by Nippon Aerosil Co., Ltd., R972D,
Number average particle size 16 nm, dimethyldichlorosilane-treated silica)
Externally added fine particles 2: Silica (manufactured by Nippon Aerosil Co., Ltd., NAX50,
Number average particle size 40 nm, hexamethylene disilazane-treated silica)
95 parts of the toner obtained above and 5 parts of carrier 1 were mixed using a V-type mixer to obtain a two-component developer.

Using this developer, the image density, solid uniformity, toner leakage and fogging were evaluated by the following methods, and the results shown in Table 1 were obtained.
<Example 2>
A two-component developer was obtained in the same manner as in Example 1 except that 1.0 part of the external additive fine particle 2 was used as the external additive fine particle. The amount of externally added fine particles having a particle diameter of 20 nm or more in the toner was 1.3% by weight, and the toner had a Sp of 110 ° C. and a Tg of 65 ° C. Using this developer, the image density, solid uniformity, toner leakage and fogging were evaluated by the following methods, and the results shown in Table 1 were obtained.
<Examples 3-5, Comparative Examples 1-2>
A two-component developer was obtained in the same manner as in Example 1 except that the carrier 1 was replaced with the carrier shown in Table 1. Using this developer, the image density, solid uniformity, toner leakage and fogging were evaluated by the following methods, and the results shown in Table 1 were obtained.
[Evaluation of image density (ID)]
As an image forming apparatus, an image forming apparatus of a two-component contact development type (photosensitive member is a drum type organic photosensitive member, and a fixing method is by a thermocompression roll), and an image pattern with a solid solid portion is white A4 normal It printed on paper, the solid printing part was measured with the Macbeth densitometer, and the average value of five places was judged on the following references | standards. The image density was measured at the initial stage of printing and at the time of printing 20000 sheets.

○: 1.35 or more: It means that the solid part is sufficiently dark.
Δ: 1.21 to 1.34: It means that the solid part is slightly thin.
X: 1.20 or less: It means that it is too thin to endure use.
[Solid uniformity]
Similar to the evaluation of the image density, a rectangular solid image of 25 cm × 19 cm was printed on white A4 plain paper. The uniformity of the printed solid image was visually confirmed and judged according to the following criteria. The solid uniformity was evaluated using an image at the initial printing stage.

○: Uniform over the entire solid range.
Δ: Slightly uneven.
X: Unevenness is remarkable and cannot be used.
[Toner leakage]
In the same manner as the evaluation of the image density, the inside of the apparatus after printing 20000 sheets on A4 plain paper was visually observed and evaluated according to the following criteria.

○: There is almost no toner leakage in the machine. (No hindrance to use)
Δ: Slight toner leakage. (Available level)
X: Toner leakage occurred remarkably. (Usage prohibited)
[Fog]
In the same manner as the image density evaluation, a white background pattern was output on white A4 plain paper. For the fog printed on the white background image, the difference in whiteness before and after the actual shooting was measured using a Hunter whiteness meter (manufactured by Nippon Denshoku). The fog property was measured using an image at the initial stage of printing.

○: 0.5 or less: Almost no stain on the printed image can be visually confirmed.
(Triangle | delta): 0.6-1.1: Although slight dirt is confirmed, it is satisfactory practically.
X: 1.2 or more: Dirt can be judged at a glance.

  As shown in Table 1, in Examples 1 to 5, image density, solid uniformity, toner leakage, and fogging were all good without problems. In Comparative Example 1 using a carrier having a high resin coverage, there was no problem in image density and solid uniformity, but it was confirmed that toner leakage occurred remarkably and could not be used. In Comparative Example 2 using a carrier having a large particle size, there was no problem in image density, but solid uniformity was lowered, toner leakage and fogging were remarkable, and it was confirmed that the image could not be used.

A developer was prepared in the same manner as in Example 1 except that the colorant in Example 1 was changed to magenta, yellow, and black (carbon black) and evaluated in the same manner as in Example 1. A good image having no problems with density, solid uniformity, toner leakage and fogging was obtained. Further, a full-color developer was prepared using four color toners including the cyan toner of Example 1, and evaluated in the same manner as in Example 1. However, there were problems with image density, solid uniformity, toner leakage, and fogging. A good image was obtained.

  It is useful as an electrostatic charge image developer that can be used in printing machines and copying machines that perform large-scale electrostatic development at high speed and require uniform high image quality over a long period of use.

It is the figure which showed the example of observation of the carrier 1 with the electron microscope.

Claims (4)

An electrostatic charge image developer having a toner and a carrier containing at least a binder resin and a colorant, the carrier having a weight average particle size of 75 μm or less and a compound represented by the following general formula (1): An electrostatic charge comprising at least a core particle and a coating resin, the surface of the core particle being coated with the coating resin at a ratio of 80% or less, and the toner including silica fine particles having a number average particle diameter of 20 nm or more. Image developer.

(In the formula, x + y + z = 100 mol%, and MnO, MgO and part of Fe ₂ O ₃ are substituted with SrO)   The electrostatic charge image developer according to claim 1, wherein the coating resin is a silicone resin. In the general formula (1), x, y and z are all 0.5 mol% or more, and a part of MnO, MgO and Fe ₂ O ₃ is substituted with 0.05 to 5 mol% of SrO. the electrostatic image developer according to claim 1 or 2, characterized in that. The electrostatic charge image developer according to any one of claims 1 to 3 , wherein the toner contains 0.4% by weight or more of silica fine particles having a number average particle diameter of 20 nm or more.

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