JP4293885B2 - 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 can use the same toner as the replenishment toner and the initial toner in the two-component developer, and can stably form an image over time even when a large amount of printing is performed. The present invention relates to an electrostatic charge image developer that can be used.

  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 developer used in the two-component development system has a toner containing a binder resin and a colorant, and a carrier such as iron powder and ferrite powder, but since the carrier is not consumed during development, the consumed toner It is necessary to replenish only.

The toner used for the two-component developer is the same as the toner (initial toner) present in the developing device with the carrier at the beginning and the toner replenished with the consumption of the initial toner (replenishment toner). Depending on the charging characteristics, there may be a problem that stable image density formation is difficult to obtain. For this reason, it is necessary to optimize the toner used in the conventional two-component developer with different characteristics as the initial toner and the replenishment toner. For example, toners having different triboelectric charge amounts are used (for example, patent documents). 1) and using different types and / or amounts of charge control agents (see, for example, Patent Document 2).
JP-A-8-62886. JP-A-9-288382.

  In such a method, it is necessary to manufacture an initial toner and a replenishing toner, respectively, and the manufacturing efficiency is lowered, and the composition of the toner changes with time, so that the image stability is insufficient. Was a problem. For this reason, there has been a demand for a developer that uses the same initial toner and replenishment toner, and that always provides a stable image even when continuous printing is performed. However, it is clear how this can be achieved. It was not.

The present invention has been made in view of the above-described prior art. Accordingly, it is an object of the present invention to provide the following electrostatic image developer for two-component development.
(1) As a developer for two-component development, stable image formation is possible even when substantially the same toner as the initial toner is supplied.
(2) Even when continuous printing is performed, stable changes in image formation are possible because changes over time in various characteristics such as toner chargeability are small.
(3) Even when continuously printed, the white background fog is stable and less.
(4) Even when continuous printing is performed, the toner consumption is stable.
(5) Even in the case of continuous printing, the image density is stable and the solid uniformity is stable.
(6) Even when continuous printing is performed, there is no stable carrier pulling.

As a result of diligent studies to solve such problems, the present inventor has found that the above problems can be solved by including a specific component together with toner and carrier as a developer for two-component development, and the present invention has been completed. It came to do.
That is, the gist of the present invention is an electrostatic charge image developer having a toner in which externally added fine particles are externally added to the surface of mother particles containing at least a binder resin and a colorant, a carrier, and a resistance adjusting agent. The volume specific electric resistance (A) is 10 ¹¹ to 10 ¹⁷ Ω · cm, and the volume specific electric resistance (B) of the resistance adjuster contained in the electrostatic charge image developer is 10 ³ to 10 ¹⁰ Ω · cm. And an electrostatic charge image developer characterized in that the ratio satisfies 10 ⁴ ≦ A / B ≦ 10 ¹¹ .

According to the present invention, an electrostatic charge image developer capable of forming a stable image even when substantially the same toner as the initial toner is supplied as a developer for two-component development is provided.
In addition, according to the present invention, the electrostatic charge image development is excellent in white background fogging, toner consumption, image density, solid uniformity, and carrier drawing characteristics, and these performances are stable over time even when continuously printed. An agent is provided.

The electrostatic image developer of the present invention has at least a toner containing at least a binder resin and a colorant, a carrier, and a resistance adjusting agent.
As the carrier used in the present invention, known ones used for two-component developers can be used, and examples thereof include ferromagnetic metals such as iron, cobalt and nickel, alloys and compounds such as magnetite, hematite and ferrite. . In addition, a magnetic dispersion resin that is a composite of these magnetic substances and resins can be used as a carrier. Examples of the binder resin used for the magnetic material-dispersed resin include vinyl resins, polyester resins, epoxy resins, phenol resins, urea resins, polyurethane resins, polyimide resins, cellulose resins, polyether resins, and mixtures thereof. Can be mentioned.

  The carrier used in the present invention is preferably coated on the surface with a resin from the viewpoint of durability. Examples of the resin that forms the coating layer include polyolefin resins such as polyethylene, polypropylene, chlorinated polyethylene, and chlorosulfonated polyethylene, polystyrene, acrylic (for example, polymethyl methacrylate), polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, Polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinylidene resins such as polyvinyl biketone and polyvinylidene resins, vinyl chloride-vinyl acetate copolymers, silicone resins such as dimethyl silicone or modified products thereof, polytetrafluoroethylene, polyhexafluoropropylene, Fluororesin such as polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene, polyamide, polyester, polyurethane, polyester Carbonates, urea - amino resins such as formaldehyde resins, epoxy resins, and the like. Two or more kinds of the above carrier coating resins may be used in combination.

  Among these, in order to prevent toner spent, the surface tension γ at 20 ° C. is preferably 30 mN / m or less, more preferably 10 to 25 mN / m. It is desirable because it can suppress a decrease in ability due to the resistance adjusting agent firmly adhering to the carrier and improve durability. 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 that coats the 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, alkyl groups such as methyl, ethyl, propyl, and butyl groups, phenyl groups, and phenols And an organopolysiloxane (dimethylsilicone), an organopolymetallosiloxane, an organopolysilazane, an organopolysilmethylene, an organopolysilphenylene having an aryl group such as a group, styryl group and 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 carrier coating resin may contain a coupling agent such as a silane coupling agent or a titanium coupling agent for the purpose of improving adhesion or improving dispersibility of the conductivity imparting agent. .

As a method for forming the resin layer for coating, a conventionally known method, for example, a coating layer forming solution may be applied to the surface of the particles serving as the core of the carrier by means of spraying, dipping, or the like and dried. Although the thickness of this coating layer is not limited, 0.1-20 micrometers is preferable.
Among these, it is preferable in terms of magnetic properties to use a carrier in which iron powder, ferrite, or magnetite is coated with a silicone resin or a modified product thereof.

The carrier used in the present invention usually has a saturation magnetization in a magnetic field of 23 ° C. and 7.96 × 10 ⁴ A / m (= 1000 Oe) of 30 to 250 Am ² / kg, preferably 50 to ²⁰⁰ Am ² / kg. As a result, the magnetic binding force of the developer on the developing sleeve in the developing region is increased, so that the development of the carrier on the photosensitive member is effectively prevented and a good image is obtained.

The carrier in the present invention has a weight average particle diameter of 20 to 100 μm, preferably 20 to 80 μm, so that the toner concentration of the developer layer in the development region can be increased. In this case, a good image with high image density can be obtained.
The carrier content in the developer of the present invention is not limited, but is usually 1 part by weight or more, preferably 3 parts by weight or more, and usually 30 parts by weight or less, preferably 20 parts by weight or less with respect to 100 parts by weight of the developer. It is.

A feature of the present invention is that it contains a resistance adjusting agent together with the carrier and the toner described later. In the present invention, the resistance adjusting agent means a substance that can be adjusted so that the volume specific electric resistance value of the developer is lowered by being mixed in the developer.
In the resistance adjuster of the present invention, the ratio (A / B) of the volume specific electrical resistance (A) of the toner described later and the volume specific electrical resistance (B) of the resistance adjuster is 10 ⁴ or more, preferably 10 ⁵ or more. , More preferably 10 ⁶ or more, 10 ¹¹ or less, preferably 10 ¹⁰ or less, more preferably 10 ⁹ or less. By including such a resistance adjuster in the developer, even when a carrier with high charging characteristics such as iron powder is used, the initial toner having an unnecessarily high charge amount generated from the carrier is suppressed. As a result, the image density is stabilized over a long period of time, and an excellent effect that the toner substantially the same as the initial toner can be used as the replenishing toner can be exhibited.

The resistance modifier in the present invention has a volume specific electrical resistance (B) at 25 ° C. of usually 10 ³ Ω · cm or more, preferably 10 ⁴ Ω · cm or more, more preferably 10 ⁵ Ω · cm or more. In general, it is 10 ¹⁰ Ω · cm or less, preferably 10 ⁹ Ω · cm or less, more preferably 10 ⁸ Ω · cm or less. It is desirable that the developer containing a resistance adjusting agent having a volume specific electric resistance within the above range may suppress a decrease in image density due to the initial high charge of the developer. In addition, although the general method can be used for the measurement of volume specific 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 put 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 100 V was applied from above the upper electrode using a weight with a weight of 1 kg, and this was measured by measuring the resistance value with an insulation resistance meter and converting it to a volume resistivity value.

The compound that can be used as the resistance adjusting agent is not limited as long as it has the volume specific electrical resistance characteristics as described above, and among these, magnetic particles are preferably used. The magnetic particles are magnetic substances exhibiting ferrimagnetism or ferromagnetism at the use environment temperature (around 0 ° C. to 60 ° C.) of a copying machine, 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 ; where M is Mn, Fe, Co, Ni, Cu, Mg, Zn, Cd, or a mixed crystal system thereof Spinel ferrite, hexagonal ferrite such as BaO · 6Fe ₂ O ₃ and SrO · 6Fe ₂ O ₃ , garnet type oxide such as Y ₃ Fe ₅ O ₁₂ and Sm ₃ Fe ₅ O ₁₂ , rutile type oxidation such as CrO ₂ Materials, metals such as Fe, Mn, Ni, Co, Cr, and other ferromagnetic alloys, etc. that exhibit ferromagnetism and ferrimagnetism around 0 ° C. to 60 ° C. It not, can also be used in combination of two or more. Among these, magnetite, maghematite, an intermediate between magnetite and maghematite, and the like are preferable, and magnetite is particularly preferable.

  When magnetic particles are used as the resistance adjusting agent, the shape of the magnetic particles is not limited, and may be, for example, a cubic (hexahedron), octahedron, or polyhedron of 10 or more, and also a spherical shape or a needle. It may be in the shape of a scaly, scaly, or indefinite shape. Among them, magnetic particles having a shape with less anisotropy are preferable in terms of fluidity, and in particular, spherical, octahedral, cubic, and polyhedral magnetites of decahedron are preferable in terms of saturation magnetization characteristics. The shape of such magnetic particles can be confirmed by observation with a scanning electron microscope or the like.

The number average particle diameter of the resistance adjuster is usually 0.01 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, and usually 2 μm or less, preferably 1 μm or less, more preferably 0.00. The thing of 5 micrometers or less is used. By using a resistance adjusting agent having a number average particle diameter in the above range, it can be uniformly dispersed in the developer.
The content of the resistance adjuster is usually 0.01 parts by weight or more, preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and usually 3 parts by weight with respect to 100 parts by weight of the developer. The amount is preferably 1 part by weight or less, more preferably 0.5 part by weight or less. It is preferable to include a resistance adjusting agent in the above-mentioned range in the developer because the image density is stable over a long period of time.

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 as long as it is conventionally used in toners. Examples thereof include titanium oxide, zinc white, alumina white, calcium carbonate, bitumen, various carbon blacks, and lamp black. , Phthalocyanine blue, aniline blue, calcoil blue, ultramarine blue, methylene blue chloride, phthalocyanine green, Hansa yellow G, rhodamine dyes, chrome yellow, quinacridone, benzidine yellow, quinoline yellow, rose bengal, dupont oil red, tri Allylmethane dyes, anthraquinone dyes, monoazo and disazo dyes / pigments can be used alone or in admixture as appropriate. The content of the colorant may be an amount sufficient for the obtained toner to form a visible image by development. For example, the content is preferably 3 to 20 parts by weight with respect to 100 parts by weight of the binder resin. In addition, it is preferable to use a colorant that contains as little volatile impurities as possible.

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.
In the present invention, known magnetic particles may be used as the colorant, or may be used in combination with the colorant. As the magnetic particles that can be contained in the toner as the colorant, particles composed of the same compound as the magnetic particles that can be used as the resistance adjusting agent can be used, and two or more kinds can be used in combination. Among these, magnetite, maghematite, an intermediate between magnetite and maghematite, and the like are preferable, and magnetite is particularly preferable.

  The shape of the magnetic particles contained in the toner is not limited, and may be, for example, cubic (hexahedron), octahedron, or polyhedron of 10 or more, and also spherical, needle-like, scaly, and irregular. It may be. Among them, magnetic particles having a shape with little anisotropy are preferable for increasing the image density. In particular, spherical, octahedral, cubic, and polyhedral magnetites having an icosahedral shape are preferable in terms of saturation magnetization characteristics.

The saturation magnetization of the magnetic particles contained in the toner in a magnetic field of 23 ° C. and 7.96 × 10 ⁴ A / m (= 1000 Oe) is usually 60 Am ² / kg or more, preferably 65 Am ² / kg or more, more preferably. Is 70 Am ² / kg or more, and it is usually desirable to use 100 Am ² / kg or less, preferably 95 Am ² / kg or less, more preferably 90 Am ² / kg or less. Use of magnetic particles having a magnetic force in the above-mentioned range is preferable because it has an appropriate magnetic force, and thus characteristics such as toner scattering and fogging may be improved.

  When the magnetic particles are contained in the toner, the content of the magnetic particles is usually 0.05 parts by weight or more, preferably 0.1 parts by weight or more, more preferably 0.5 parts by weight with respect to 100 parts by weight of the binder resin. It is usually 20 parts by weight or less, preferably 10 parts by weight or less, more preferably 5 parts by weight or less. By containing the magnetic particles in the toner within the above range, the toner has an appropriate magnetic force, and therefore, characteristics such as toner scattering and fogging may sometimes be improved.

  The toner constituting the developer of the present invention can improve the characteristics such as toner scattering and fog by adjusting the magnetic characteristics. In order to optimize the magnetic properties of the toner, it is important to balance the magnetic properties of the magnetic particles contained in the toner and the content thereof. As a toner, the toner has stable magnetic properties and balance of electrical resistance. It is desirable to adjust so as to maintain a stable charge amount.

Further, the volume specific electric resistance at 25 ° C. of the magnetic particles contained in the toner is usually 10 ³ Ω · cm or more, preferably 10 ⁴ Ω · cm or more, more preferably 10 ⁵ Ω · cm or more, Usually, it is desirable to use a material having a viscosity of 10 ¹⁰ Ω · cm or less, preferably 10 ⁹ Ω · cm or less, more preferably 10 ⁸ Ω · cm or less. Use of magnetic particles having a volume specific electric resistance in the above range is preferable because a balanced and stable charge amount may be maintained.

  The number average particle diameter of the magnetic particles contained in the toner is usually 0.01 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, and usually 3 μm or less, preferably 2 μm or less. More preferably, a thickness of 1 μm or less is used. Use of magnetic particles having a number average particle size in the above range is preferable because the dispersibility in the toner is good and the charging performance may be uniform.

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 and an emulsifier, and the polymerizable monomer is polymerized with stirring. A primary particle emulsion is produced, and then the polymer primary particle emulsion is agglomerated by adding a coloring agent and other components such as a charge control agent and a wax added as necessary to the obtained polymer primary particle emulsion. Thus, primary particle aggregates are formed, 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 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 all 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 with respect to 100 parts by weight of the toner base particles. The amount is not more than parts by weight, preferably not more than 6 parts by weight, more preferably not more than 4 parts by weight. 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.

  In the present invention, the above-mentioned resistance adjusting agent may be used as the external additive fine particles of the toner, or the inorganic or organic fine particles and the resistance adjusting agent may be used in combination as the external additive fine particles. Also, two or more resistance adjusting agents used as externally added fine particles can be used in combination. The resistance adjusting agent used as the external additive fine particles is selected from the above-described resistance adjusting agent and is not limited, but among them, magnetite, maghematite, an intermediate between magnetite and maghematite, etc. are particularly preferable. Magnetite is preferred.

  In addition, when magnetic particles are used as the resistance adjusting agent used for the externally added fine particles, the shape of the magnetic particles is not limited. For example, a cubic (hexahedron), octahedron, decahedron or more polyhedron may be used. Moreover, it may be spherical, acicular, scaly, or indeterminate. Among them, magnetic particles having a shape with little anisotropy are preferable. In particular, in the case of a hexahedron or octahedron shape, the surface of the photoconductor drum is polished by polishing the ozone layer generated when the photoconductor drum is charged. May be preferable in that it can always be kept fresh (polishing effect).

  The resistance adjusting agent used as the externally added fine particles may be appropriately adjusted by coating the surface of the compound with a resin or the like. Examples of the resin forming the coating layer include polyolefin resins such as polyethylene, polypropylene, chlorinated polyethylene, and chlorosulfonated polyethylene, styrene resins, acrylic (eg, polymethyl methacrylate) resins, styrene acrylic resins, polyacrylonitrile, Polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinylidene-based resins such as polyvinyl biketone, vinyl chloride-vinyl acetate copolymer, silicone resin or a modified product thereof, polytetrafluoroethylene, Fluorine resin such as polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene, polyamide resin, polyester resin, polyurethane resin, polycarbonate DOO resins, urea - amino resins such as formaldehyde resins, epoxy resins, and the like. Two or more kinds of the above-mentioned coating resins may be used in combination.

The coating resin is preferably a resin capable of making the resistance adjusting agent used as externally added fine particles positive (positively charged). In this respect, a styrene acrylic resin is particularly preferable.
The amount of the resistance adjusting agent used as the external additive fine particles is included in the total amount of the external additive fine particles, and is usually 0.05 parts by weight or more, preferably 0.1 parts by weight or more, based on 100 parts by weight of the toner base particles. More preferably, it is 0.5 parts by weight or more, usually 10 parts by weight or less, preferably 5 parts by weight or less, more preferably 3 parts by weight or less. It is preferable to have the resistance adjusting agent in the above range since the charging stability of the toner may be improved.

The volume specific electrical resistance at 25 ° C. of the resistance adjusting agent used as the externally added fine particles is usually 10 ⁷ Ω · cm or more, preferably 10 ⁸ Ω · cm or more, more preferably 10 ⁹ Ω · cm or more. It is desirable to use 10 ¹³ Ω · cm or less, preferably 10 ¹² Ω · cm or less, more preferably 10 ¹¹ Ω · cm or less. Use of magnetic particles having a volume specific electric resistance in the above range may be preferable because it is easy to adjust the resistance of the toner by the amount of external addition. In order to make the volume specific electric resistance within the above range, it can be easily achieved by surface treatment of the magnetic particles with a resin or the like.

  Further, the charging characteristics of the resistance adjusting agent used as the externally added fine particles are preferably opposite in polarity to the chargeability of the finally obtained toner. By doing so, the charging stability may be improved, which is preferable. The charging characteristics of the resistance adjusting agent can be adjusted by surface treatment of the resin for resin described above. The charging characteristics can be examined with a surface potential meter.

Further, the number average particle diameter of the resistance adjusting agent used as the externally added fine particles is usually 0.01 μm or more,
The thickness is preferably 0.05 μm or more, more preferably 0.1 μm or more, and it is usually 3 μm or less, preferably 2 μm or less, more preferably 1 μm or less. Use of a resistance adjuster having a number average particle size in the above range is preferable because it may provide appropriate charging stability without hindering the fluidity of the toner.

  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.

Further, the toner in the present invention has a volume specific electric resistance (A) at 25 ° C. of usually 10 ¹¹ Ω · cm or more, preferably 10 ¹² Ω · cm or more, more preferably 10 ¹³ Ω · cm or more, Usually, it is 10 ¹⁷ Ω · cm or less, preferably 10 ¹⁶ Ω · cm or less, more preferably 10 ¹⁵ Ω · cm or less. It is desirable that the volume specific electrical resistance of the toner is in the above range because the chargeability may become stable.

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 toner in the present invention can form the best image when used as a two-component developer mixed with the carrier and the resistance adjusting agent. However, only the toner is used as a one-component developer. It is also possible to use it.

The electrostatic image developer of the present invention is obtained by mixing at least the toner, carrier and resistance adjusting agent with a V-type mixer or the like, and is usually used in an image forming apparatus of a two-component development system. A good image is obtained.
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 two-component contact development 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.

When iron powder is used as the carrier, the photosensitive member and the developing sleeve rotate in the same direction, that is, in a place where the photosensitive member and the developing sleeve are close to each other, both are moved in the opposite direction. It is preferable from the viewpoint.
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 toner constituting the electrostatic charge image developer of the present invention can be used as both an initial toner and a replenishing toner when an image is formed using a two-component developing type developing device. The toner of the present invention can be used for only one of the replenishing toners.
As described above, since the electrostatic charge image developer of the present invention has good charge amount stability, it is stable even when the toner substantially the same as the initial toner is replenished as a developer for two-component development. Image formation is possible, and stable image formation is possible even when continuous printing is performed.

  A preferred embodiment of the present invention is exhibited by employing a specific toner resin and a specific resin-coated carrier and combining with the resistance adjusting agent of the present invention. That is, the toner resin has a molecular weight distribution of a low molecular weight substance and a high molecular weight substance. The low molecular weight substance has a molecular weight of 10,000 or less, and preferably has at least one molecular weight peak at 3000 to 7000. Is a multi-peak resin having at least one molecular weight peak at 100,000 or more, preferably 300,000 to 1,000,000, and having a surface tension γ (mN / m) at 20 ° C. of 10 to 25 as a coating resin for a carrier This is a case where a resin is used in combination. In this case, when the toner is used, the toner resin has both a flexible portion and a tough portion as the strength. In such a case, the presence of the resistance adjusting agent of the present invention is not completely buried in the toner. It is not easily released from the surface of the toner, it can exist with an appropriate adhesion strength to the toner, and there is no decrease in ability due to the resistance adjusting agent firmly adhering to the carrier due to the releasing action of the coated carrier. By these actions, the present invention can maintain a stable image quality over a long period of time, so that the durability is very high.

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.
<Example 1>
100.0 parts of binder resin, 7.0 parts of colorant 1, 2.0 parts of colorant 2, 1.0 part of wax 1, 1.0 part of wax 2, and 1 charge control agent are shown below. 0.0 part was mixed using a Henschel mixer and then kneaded using a twin-screw kneader (Ikegai PCM-87), pulverized and classified using a jet mill, and a toner base having an average particle size of 10.0 μm Particles were obtained.

-Binder resin: Styrene / methacrylic acid / butyl acrylate copolymer
(Non-crosslinked, weight average molecular weight 290,000, number average molecular weight 3200,
GPC peaks: 5000 and 320,000,
(Sp = 130 ° C., Tg = 58 ° C.)
Colorant 1: Carbon black (manufactured by Cabot, Regal 330R)
Colorant 2: Magnetite (manufactured by Toda Kogyo Co., EPT1000,
Number average particle size = 0.3 μm, saturation magnetization = 82 Am ² / kg)
Wax 1: Polyethylene wax (Hoechst PE130)
・ Wax 2: Polypropylene wax (manufactured by Mitsui Chemicals, NP505)
-Charge control agent: Metal-containing azo dye (negatively charged)
Based on 100.0 parts of the obtained toner base particles, 0.4 parts of the externally added fine particles 1 shown below, 0.5 parts of the externally added fine particles 2 and 1.5 parts of the externally added fine particles 3 were added to a Henschel mixer. And mixed to obtain a toner. The toner had a Sp of 130 ° C., a Tg of 57 ° C., a volume specific electric resistance of 1 × 10 ¹⁴ Ω · cm, and was negatively charged. This toner was used as both the initial toner and the replenishment toner of the two-component developer.

External fine particles 1: Silica (made by Nippon Aerosil Co., Ltd., 972D,
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)
Externally added fine particles 3: magnetite (positive chargeability, number average particle size = 0.5 μm,
Volume specific electrical resistance = 1 × 10 ¹⁰ Ω · cm,
Coated with styrene / aminoacrylate copolymer)
7.5 parts of the toner obtained above, 92.5 parts of the carrier shown below, and 0.3 part of the resistance adjuster were mixed using a V-type mixer manufactured by Tokuju Seisakusho, and two-component A developer was used. Using the developer, image density, fogging, solid uniformity and carrier pulling characteristics were evaluated by the following methods, and the results shown in Table 2 were obtained.

Carrier: iron powder (weight average particle size = 50 μm,
Surface coating with dimethyl silicone resin with a surface tension of 19 mN / m)
Resistance adjusting agent: magnetite (manufactured by Kanto Denka Kogyo Co., Ltd., KBC100-60,
Number average particle size = 0.4 μm,
Volume specific electrical resistance = 1 × 10 ⁶ Ω · cm)

[Evaluation of image density (ID)]
As an image forming apparatus, an image forming apparatus of a two-component contact development system (the photosensitive member is a drum type organic photosensitive member, and the photosensitive member and the developing sleeve rotate in the same direction in a place where the photosensitive member and the developing sleeve come close to each other) And the developing sleeve move in the opposite direction), the fixing method is by a thermocompression roll), and an image pattern with a solid black solid part is printed on white A4 plain paper, The black solid part was measured with a Macbeth densitometer, and the average value of five locations was judged according to the following criteria.

The image density was measured at the initial stage of printing and at the time of printing 6000 sheets. During the printing of 6000 sheets, the same toner as the initial toner was replenished once as a replenishing toner.
○: 1.40 or more: It means that the solid part is sufficiently black.
Δ: 1.31-1.39: It means that the solid part is slightly thin.
X: 1.30 or less: It means that it is too thin to endure use.

[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.

[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 measured using an image at the initial stage of printing.
○: Uniform over the entire solid range.
Δ: Slightly uneven.
X: Unevenness is remarkable and cannot be used.

[Carrier pulling characteristics]
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 number of white spots due to carrier pulling on a solid black (the carrier being transferred onto plain paper) was determined according to the following criteria. The carrier pulling characteristic was measured using an image at the initial stage of printing.
○: 0 to 1 △: 2 to 4 ×: 5 or more

<Example 2>
Toner base particles were produced in the same manner as in Example 1 except that the colorant 2 was not used in the production of toner base particles. Using the obtained toner base particles, a negatively chargeable toner and developer were obtained in the same manner as in Example 1. The results of evaluating the obtained developer in the same manner as in Example 1 are shown in Tables 1 and 2.

<Example 3>
In the production of the toner, a negatively chargeable toner was produced in the same manner as in Example 1 except that the amount of the external additive fine particles 3 was changed to 0.8 part. A developer was obtained using the obtained toner in the same manner as in Example 1. The results of evaluating the obtained developer in the same manner as in Example 1 are shown in Tables 1 and 2.

<Example 4>
In the production of the toner, a negatively chargeable toner was produced in the same manner as in Example 1 except that the amount of the external additive fine particles 3 was changed to 2.2 parts. A developer was obtained using the obtained toner in the same manner as in Example 1. The results of evaluating the obtained developer in the same manner as in Example 1 are shown in Tables 1 and 2.

<Comparative Example 1>
In the adjustment of the developer, a developer was obtained in the same manner as in Example 1 except that the resistance adjuster was not used. The results of evaluating the obtained developer in the same manner as in Example 1 are shown in Tables 1 and 2.
<Comparative example 2>
Toner base particles were produced in the same manner as in Example 1 except that the colorant 2 was not used in the production of toner base particles. A negatively chargeable toner was produced in the same manner as in Example 1 except that the obtained toner base particles were used and the externally added fine particles 3 were not used. A developer was obtained in the same manner as in Example 1 except that the obtained toner was used and no resistance adjusting agent was used. The results of evaluating the obtained developer in the same manner as in Example 1 are shown in Tables 1 and 2.

  In any of Examples 1 to 4, the image density is stable and stable from the initial printing to after printing 6000 sheets, and the fogging, solid uniformity, and carrier pulling characteristics are also stable from the initial printing to after printing 6000 sheets. It was good. In Comparative Examples 1 and 2 using a developer not containing a resistance adjuster, not only the image density was low in the initial printing stage, but also the change in the image density was remarkable during the printing process of 6000 sheets. Furthermore, the carrier pulling characteristics were poor, and there was a tendency for fog and solid uniformity.

  As a developer for two-component development, it can be used as an electrostatic charge image developer capable of supplying substantially the same toner as the initial toner. Further, it can be used as an electrostatic charge image developer that can be used in a printing machine or a copying machine that performs a large amount of electrostatic development at high speed.

Claims (12)

An electrostatic charge image developer comprising a toner having externally added fine particles added to the surface of mother particles containing at least a binder resin and a colorant, a carrier, and a resistance adjusting agent, wherein the toner has a volume specific electrical resistance (A). 10 ¹¹ to 10 ¹⁷ Ω · cm, and the volume specific electrical resistance (B) of the resistance adjuster contained in the electrostatic charge image developer is 10 ³ to 10 ¹⁰ Ω · cm, and the ratio is 10 ^4. An electrostatic charge image developer satisfying ≦ A / B ≦ 10 ¹¹ . The electrostatic charge image developer according to claim 1, wherein the resistance adjusting agent has a number average particle diameter of 0.01 to 2 μm. The electrostatic image developer according to claim 1 or 2, wherein the resistance adjusting agent is magnetite. Toner, electrostatic image developer according to any one of claims 1 to 3, characterized in that those containing the magnetic particles to mother particles of the toner. The electrostatic charge image developer according to claim 4 , wherein the saturation magnetization of the magnetic particles contained in the toner base particles is 60 to 100 Am ² / kg. Toner, electrostatic image developer according to any one of claims 1 to 5, characterized in that resistance adjusting agent to the mother particle surfaces of the toner is what is externally added. 7. The electrostatic charge image developer according to claim 6 , wherein the resistance specific additive externally added to the surface of the toner base particles has a volume specific electric resistance of 10 ⁷ to 10 ¹³ Ω · cm. 8. The electrostatic charge image developer according to claim 6 or 7 , wherein the charging property of the resistance adjusting agent externally added to the surface of the toner base particles has a polarity opposite to that of the toner. The electrostatic image developer according to any one of claims 1 to 8, characterized in that the charging characteristics of the toner is negatively charged. The electrostatic image developer according to any one of claims 1 to 9 carrier is characterized in that it contains the iron powder. An image forming method using the electrostatic image developer according to any one of claims 1 to 10, upon supplying toner consumed by development, digested costs toner substantially to replenish the same toner An image forming method. Replenishment toner, which is a toner and substantially the same composition used in the electrostatic image developer according to any one of claims 1 to 10.