JP3536401B2 - Toner composition for electrostatic image development and image forming method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner composition for developing an electrostatic image for use in a copying machine, a printer or the like to which an electrophotographic technique is applied, and an image forming method using the same, and particularly to suppressing environmental dependence. Further, the present invention relates to a toner composition for developing an electrostatic charge image and an image forming method capable of obtaining excellent image stability.

[0002]

2. Description of the Related Art Currently, the dry developing methods in various electrostatic copying methods which have been put to practical use include a one-component developing method using a toner containing a magnetic substance inside the toner and a two-component developing method using a carrier such as toner and iron powder. It is roughly divided into the component development method.
The one-component development method using magnetic toner makes the apparatus compact because it does not require an automatic density adjuster used in a two-component development type developing machine. No maintenance required. Therefore, the one-component development method is applicable not only to low-speed small copiers and printers, but also to medium-speed copiers and printers.
It is also used in plotters, and further improvement in its performance is expected.

In recent years, digitization has progressed not only in the field of printers but also in the field of copying machines, and it has become possible to form latent images with higher precision and to express subtle gradations with small Kanji and dots. It was In particular, even for plotters for large drawings, a smaller device that uses the one-component development method has been developed, and the line width of the drawing can be faithfully and stably reproduced by digitization to achieve high accuracy. A latent image with high accuracy can be formed. However, a technique for obtaining a high-quality image by directly developing the high-precision latent image thus formed has not been sufficiently realized.
As described above, the one-component image system has various excellent features, but there are problems to be solved in order to achieve high-quality development. That is, during development, magnetic particles contained in the toner cause agglomeration of the toner particles, the toner particles become coarse, it is difficult to faithfully develop the latent image, and magnetic fine particles that are not fixed from the magnetic toner are generated. There's a problem.

On the other hand, in the two-component developing system, the carrier shares the functions of stirring, conveying, charging, etc. of the developer, and since the functions are separated as the developer, it is easy to control. Currently widely used, in particular, a developer using a resin-coated carrier has excellent charge controllability,
Although it is easier to improve the environmental dependence and the stability with time as compared with the one-component developing method, the problems have not been completely solved. Generally, silica fine powder is often added to improve charge control and powder fluidity, but a part of the added silica fine powder is detached from the toner, causing various obstacles to members other than the toner. . For example, filming of desorbed silica on the photoconductor causes image defects such as white spots on the image. This problem is a common problem to be solved regardless of the one-component or two-component development method. In order to suppress such environmental dependence of silica, it has been proposed to treat the silica surface with silicone oil (Japanese Patent Laid-Open No. 2-287459). However, the toner to which such surface-treated silica is added has a problem that the offset resistance is lowered. Whether it is magnetic or non-magnetic, the toner may be offset by the toner that adheres to the heating roll when applied to the heating roll fixing method and stains the next copy, or by a finger that separates the paper after passing through the heating roll. A low molecular weight polyolefin wax is contained in order to improve the generation of finger marks that destroy the fixed image. This low molecular weight polyolefin wax exudes its effect by exuding to the toner surface at the time of fixing, but when the silicone oil-treated silica powder is present on the toner surface, the silica powder functions as a filler when the polyolefin wax exudes. As a result, the viscosity of the polyolefin wax increases and the releasing effect of the wax decreases.

On the other hand, although the polyolefin wax-added toner has good releasability from the heating roller and good offset resistance, it has a low compatibility between the polyolefin wax and the binder resin, so that the polyolefin wax has a large domain in the resin. When the toner is produced, the domain is easily crushed and the polyolefin wax is easily exposed on the surface of the toner. Further, if the diameter of the toner is reduced to achieve high image quality, the amount of wax on the surface is further increased. When the magnetic one-component developing method is used to develop with such toner, the polyolefin wax migrates to the developing sleeve and the photoconductor to cause uneven toner conveyance and contamination of the photoconductor, resulting in lower density and deterioration of image quality. As a solution to the above-mentioned secondary obstacles due to the polyolefin wax, it has been proposed to regulate the amount of surface wax (Japanese Patent Laid-Open No. 2-87159). There is a problem that the fixing property is deteriorated, such as deterioration of offset resistance.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems in the prior art, and an object thereof is to suppress filming in a charging member such as a developing sleeve and a carrier and a photoconductor. It is also an object of the present invention to provide a one-component magnetic toner composition for developing an electrostatic charge image and a two-component toner composition capable of obtaining a stable image, and an image forming method using these toner compositions.
Another object of the present invention is to provide a one-component magnetic toner composition and a two-component toner composition having excellent dot reproducibility, fine line reproducibility, and gradation that faithfully reproduces a digital latent image. Still another object of the present invention is to provide a toner composition for developing an electrostatic charge image having a practically wide fixing latitude.

[0007]

In order to achieve the above object, the present inventors have succeeded in suppressing the environmental dependence of a wax-containing toner, without causing a decrease in density particularly under high temperature and high humidity. As a result of diligent research to make the fixing latitude sufficiently wide for practical use, a silica fine particle containing a low molecular weight polyolefin wax, further defining the toner rheology and the wax exposure amount on the toner surface within a specific range and treating with a silicone oil was used. It has been found that an excellent electrostatic charge image developing toner composition can be obtained by adding a powder, and the present invention has been completed.

That is, the toner composition for developing an electrostatic image of the present invention comprises toner particles containing a binder resin, a colorant and a low molecular weight polyolefin wax, and an external additive. As 150 ℃, load 2160
melt index (MI) of 10 g /
The amount of exposure is 10 minutes or less, the low-molecular-weight polyolefin wax is polyethylene and / or polypropylene, and the exposure amount x on the toner particle surface x
(% By weight) satisfies 20 <x <40, and is characterized in that silica particles treated with silicone oil are used as an external additive. The image forming method of the present invention comprises a step of forming an electrostatic image on a latent image carrier, a step of developing the electrostatic latent image with a developer, a step of transferring the formed toner image onto a transfer body, and a transfer. An image forming method having a step of heating and fixing a toner image on a body is characterized by using the above-mentioned toner composition for developing an electrostatic image as a developer.

The present invention will be described in detail below.
First, the toner composition of the present invention will be described. The toner particles in the toner composition of the present invention are composed of a binder resin containing a colorant and a low molecular weight polyolefin wax. As the binder resin used in the toner of the present invention, known synthetic resins and natural resins can be used. For example, homopolymers or copolymers of one or more vinyl monomers can be used. Typical vinyl monomers include, for example, vinyl aromatic compounds such as styrene, p-chlorostyrene, and vinylnaphthalene, ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene, such as vinyl chloride.
Vinyl esters such as vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl formate, vinyl stearate, vinyl caproate, for example, methyl acrylate, ethyl acrylate, acrylic acid n-
Butyl, isobutyl acrylate, dodecyl acrylate,
Ethylenic monocarboxylic acids such as n-octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl-α-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and their esters such as acrylonitrile and methacrylic acid. Ethylenic carboxylic acid substitution products of ronitrile, acrylamide, etc., for example, ethylenic carboxylic acids such as dimethyl maleate, diethyl maleate, dibutyl maleate and the like, and their esters, for example vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone. Vinyl ketones such as vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether and the like vinyl ethers such as vinylidene chloride and vinylidene chloride fluoride. Benzylidene halides, such as N-
Examples thereof include N-vinyl compounds such as vinylpyrrole, N-vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone.

In the present invention, the binder resin is 15
The melt index (MI) under the conditions of 0 ° C. and a load of 2160 g needs to be 10 g / 10 minutes or less. By reducing the MI to 10 g / 10 minutes or less, hot offset is improved, a small amount of polyolefin wax needs to be added, and contamination of the charging member by the polyolefin wax can be suppressed. The factors that control the MI of the binder resin include the glass transition temperature (Tg), the molecular weight distribution, the monomer composition, and the like. For example, in the case of a binder resin showing a two-peak distribution in the molecular weight distribution, MI can be controlled by changing the molecular weight or the high / low molecular ratio. That is, by increasing the molecular weight on the high molecular side or by increasing the high / low molecular ratio, the MI of 10 g / 10
It can be reduced to less than a minute.

In the present invention, the low molecular weight polyolefin wax is made of polyethylene and / or polypropylene, and low molecular weight polyethylene or low molecular weight polypropylene having a softening point of 80 to 160 ° C. is preferably used. These polyolefins may be modified. In the present invention, the low molecular weight polypropylene wax and the low molecular weight polyethylene wax are
Either one may be contained, but it is preferable to use both in combination. When both are used together, the offset resistance is good, and when the toner image after fixing is rubbed with a white paper, the phenomenon that a part of the toner image is broken and it shifts to a rubbed white paper (smudge phenomenon) is improved. There is an advantage that can be done.

The above low molecular weight polyolefin wax is
The amount of exposed wax x (% by weight) on the toner particle surface is 20
It is necessary to mix them so as to be in the range of <x <40. When the wax exposure amount x is 20% or less, hot offset, finger marks, etc. occur and the fixing property of the image is deteriorated. On the other hand, when x is 40% or more, the polyolefin to the developing sleeve and the carrier is reduced. Causes wax migration. Controlling the amount of wax exposed on the surface of the toner particles includes addition of low molecular weight polyolefin wax, control of particle size of wax dispersion, post-treatment of toner particle surface, etc. However, in the case of a toner having a small particle diameter, there arises a problem that free polyolefin wax is generated, for example, toner particles formed of only a domain portion of the polyolefin wax are formed. Further, if the wax dispersion particle size is too large, the domain portion of the polyolefin wax is easily crushed during the production of toner particles, and the wax exposure amount increases. As a method of controlling the particle diameter of the wax dispersion particles, for example, temperature control during toner kneading can be adopted. For example, by kneading at a temperature not higher than the softening point of the polyolefin wax, the polyolefin wax portion in the slab also has a kneading share, and the wax dispersed particle diameter can be reduced to some extent. In the present invention, the wax dispersion particle size is usually preferably in the range of 0.01 to 3 μm.

As the colorant, any known colorant used for toner can be used.
For example, carbon black, organic pigments and dyes can be used as appropriate. The amount of colorant added is usually 1 to 20% by weight.
It is preferably in the range of. Also, the toner particles include
Various substances can be added for the purpose of charge control, electric resistance control, and the like. For example, fluorine-based surfactants, chromium salicylate complexes, azo-based metal complex dyes, polymeric acids such as copolymers containing maleic acid as a monomer component, quaternary ammonium salts, azine dyes such as nigrosine, and carbon black. Etc. can be added.

When the toner composition of the present invention is used in a one-component developing system, it may contain a magnetic fine powder. Magnetic fine powder may be used instead of the colorant.
As the magnetic fine powder, known magnetic substances such as metals such as iron, cobalt, nickel and alloys thereof, Fe ₃ O
₄ , γ-Fe ₂ O ₃ , metal oxides such as cobalt-added iron oxide, various ferrites such as MnZn ferrite and NiZn ferrite, magnetite, hematite, and the like.
Further, those whose surface is treated with a surface treating agent such as a silane coupling agent or a titanate coupling agent, or those whose surface is coated with a polymer can be used. When these magnetic fine powders are contained, the mixing ratio thereof is preferably in the range of 30 to 70% by weight, more preferably 35 to 65% by weight, based on the whole toner particles. If the amount of magnetic fine powder is less than 30% by weight, the force of the toner holding the magnet by the magnet of the toner carrier is reduced,
The problem of toner scattering occurs. On the other hand, if the amount exceeds 70% by weight, the reproducibility of the concentration is lowered.
The toner particles in the present invention can be produced by heating and kneading the above components by a conventional method, cooling, pulverizing and classifying.

To the toner composition of the present invention, it is necessary to add silica fine particles treated with silicone oil as an external additive. The silica fine particles treated with silicone oil may be synthesized by either a dry method or a wet method. Further, the silicone oil used in the present invention is generally represented by the following formula.

[Chemical 1] (R: alkyl group having 1 to 3 carbon atoms R ': silicone oil modifying group such as alkyl, alkyl halide, phenyl, substituted phenyl group R ": alkyl group having 1 to 3 carbon atoms or alkoxy group n and m: respectively (Integer from 0 to 10000)

Specific examples include, but are not limited to, dimethyl silicone oil, methylphenyl silicone oil, and alkyl-modified silicone oil substituted with an ethyl group, a propyl group, and the like.
The primary particle size of the silica fine particles treated with these silicone oils is preferably in the range of 5 to 50 nm. Further, the blending amount with respect to the toner particles is preferably in the range of 0.1 to 3% by weight.

In addition to the above silica fine particles, inorganic fine particles such as titania and alumina can be added to the toner composition of the present invention. In order to prepare the toner composition of the present invention, the silica fine particles and, if necessary, other external additives are added to the toner particles and mixed by a Henschel mixer or the like.

When the toner composition of the present invention is used as a two-component developer, it is mixed with a carrier. In that case, as the carrier, a magnetic powder dispersion type carrier or a coating type carrier having a binder resin and magnetic powder can be used. The magnetic powder-dispersed carrier has an average particle size in the range of 20 to 150 μm and a volume resistivity of 10 ¹⁰ to.
It is preferably 10 ¹⁵ Ωcm. As the binder resin, all the same resins as those used for the above toner can be used. As the magnetic powder, usually used fine particles of ferromagnetic material can be used, and specific examples thereof include triiron tetraoxide, various ferrites, chromium oxide, and various metal powders. Furthermore, a charge control agent or the like can be contained if necessary. The amount of the magnetic powder compounded in the carrier is about 30 to 95% by weight, preferably 45 to 90% by weight, based on the whole carrier.

The magnetic powder-dispersed carrier is prepared by kneading, pulverizing, and classifying the above components. The above components are dissolved in an appropriate solvent or liquefied by heating and granulated by spray drying or the like. It can also be produced by converting into The coated carrier has a resin coating on the surface of the magnetic core and has an average particle size of 4
Volume resistivity of 10 ⁸ to 10 ^{16 in} the range of 0 to 200 μm
The range of Ωcm is desirable. As a magnetic core,
It is possible to use fine particles of ferromagnetic material that are commonly used,
Specifically, various ferrites such as ferric tetroxide, γ-iron sesquioxide, MnZn ferrite, NiZn ferrite, and chromium oxide can be used. Further, as a resin for coating these magnetic cores, polyvinylidene fluoride, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, acrylic acid ester polymer and copolymer Examples thereof include methacrylic acid ester polymers and copolymers. These resins are usually used in the range of 0.05 to 3.0% by weight with respect to the magnetic core. The coating can be performed by a conventional method, for example, a solution in which a resin is dissolved in an organic solvent is added to the magnetic core, and the magnetic core can be coated with a fluid coating device.

Next, the image forming method of the present invention will be described. The image forming method of the present invention includes a latent image forming step of forming a latent image on a latent image bearing member, a developing step of developing a latent image on the latent image bearing member, and a toner image transfer member on the latent image bearing member. And a fixing step of thermally fixing the toner image on the transfer body. In the latent image forming step, a conventionally known method can be applied, and by an electrophotographic method or an electrostatic recording method,
The electrostatic latent image may be formed on the latent image carrier such as the photosensitive layer or the dielectric layer. Then, the formed latent image is visualized in the developing step by using the above-mentioned electrostatic image developing toner composition of the present invention. The visualized toner image is transferred onto a transfer body such as paper by a conventional method in the transfer step, and then heat-fixed in the fixing step.

In the present invention, the particle size of the toner is a value measured by a particle size measuring device TA-II manufactured by Coulter Counter Co., Ltd. with an aperture diameter of 100 μm. Further, the exposure amount x of the low molecular weight polyolefin wax on the surface of the toner particles (hereinafter, referred to as “surface wax amount”) is E
SCA (XPS) [ElectronSpectros
copy for Chemical Analysis
s (X-ray Photoelectron Spe
It can be measured by elemental analysis of the surface by means of c. That is, the elemental composition ratio is determined by measuring with the element ESCA present in the surface layer (within 5 nm) of the toner particles, and then it is present in various compounds such as the binder resin, low molecular weight polyolefin wax, and magnetic powder, which are the toner components. The elemental composition ratio is determined, and the amount of the polyolefin wax present in the toner surface layer is calculated from the elemental composition ratio and the specific gravity, and the value is expressed in% by weight. In addition, the melt index (MI) of the binder resin is measured using a melt indexer (manufactured by Toyo Seiki Seisakusho) according to JIS K-72.
The value is based on 10. In the following, the unit will be omitted.

[0022]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to these. (Example 1) Styrene-n-butyl acrylate copolymer 47.3 parts by weight (copolymerization ratio 80:20, high / low molecular ratio 70:30, polymer side maximum value 1,600,000) (Mw = 290,000, MI = 4.0, Tg = 59 ° C.) Magnetic substance A (hexahedral magnetite, particle size = 0.19 μm) 50 parts by weight Negative charge control agent (azo Cr dye) 0.7 parts by weight Low molecular weight Polypropylene (660P, manufactured by Sanyo Chemical Industry Co., Ltd.) 2.0 parts by weight The above materials were powder-mixed with a Henschel mixer, and the mixture was heat-kneaded with an extruder. After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a 50% volume diameter D50 of 6.5 μm. This is further classified and D50 = 7.3μ
As a result, a classified product having a number distribution of m, 5 μm or less and 30% was obtained. The amount of surface wax of the obtained toner particles was 30%.
On the other hand, as an external additive, silica fine particles a obtained by treating colloidal silica (R972, manufactured by Nippon Aerosil Co., Ltd.) with dimethyl silicone oil to 20% by weight are used. 1.0 part by weight was added to parts by weight and mixed by a Henschel mixer to obtain a toner composition 1.

(Example 2) Styrene-n-butyl acrylate copolymer 46 parts by weight (copolymerization ratio 80:20, high / low molecular ratio 60:40, polymer side maximum value 1,600,000) (Mw = 250,000, MI = 9.2, Tg = 59 ° C.) Magnetic substance B (octahedral magnetite, particle size = 0.22 μm) 50 parts by weight Negative charge control agent (salicylic acid-based Cr dye) 2.0 parts by weight Low Molecular weight polypropylene (660P, manufactured by Sanyo Kasei Co., Ltd.) 2.0 parts by weight The above materials were powder-mixed with a Henschel mixer, and this was heat-kneaded with an extruder. After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a 50% volume diameter D50 of 7.6 μm. Further classify this, D50 = 8.5μ
m, 5 μm or less, the number distribution was 15%, and a classified product was obtained. The amount of surface wax of the obtained toner particles was 31%.
On the other hand, as the external additive, the same silica fine particles a as in Example 1 were used, and 1.0 part by weight of this silica fine particle a was added to 100 parts by weight of the above-mentioned toner and mixed by a Henschel mixer to obtain toner composition 2. Obtained.

(Example 3) Styrene-n-butyl acrylate copolymer 47.3 parts by weight (copolymerization ratio 80:20, high / low molecular ratio 70:30, polymer side maximum value 1,300,000) (Mw = 260,000, MI = 9.5, Tg = 59 ° C.) Magnetic substance A (hexahedral magnetite, particle size = 0.19 μm) 50 parts by weight Negative charge control agent (azo Cr dye) 0.7 parts by weight Parts Low molecular weight polypropylene (660P, manufactured by Sanyo Kasei Co., Ltd.) 1.5 parts by weight Low molecular weight polyethylene (softening point = 122 ° C.) 0.5 parts by weight The above materials are powder-mixed by a Henschel mixer and heated by an extruder. Kneaded After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a 50% volume diameter D50 of 7.3 μm. Further classify this, D50 = 8.0μ
m was 5 μm or less and the number distribution was 18% to obtain a classified product. The surface wax amount of the obtained toner particles was 33%.
On the other hand, as an external additive, silica fine particles b obtained by treating colloidal silica (R972, manufactured by Nippon Aerosil Co., Ltd.) with methylphenyl silicone to a concentration of 20% by weight are used. 0.8 parts by weight was added to parts by weight and mixed by a Henschel mixer to obtain a toner composition 3.

Example 4 Styrene-n-butyl acrylate copolymer 46.9 parts by weight (copolymerization ratio 80:20, high / low molecular ratio 70:30, polymer side maximum value 1,600,000) (Mw = 290,000, MI = 4.0, Tg = 59 ° C.) Magnetic substance A (hexahedral magnetite, particle size = 0.19 μm) 50 parts by weight Negative charge control agent (azo Cr dye) 0.7 parts by weight Parts Low molecular weight polypropylene (660P, manufactured by Sanyo Kasei Co., Ltd.) 2 parts by weight Low molecular weight polyethylene (softening point = 122 ° C.) 0.4 parts by weight The above materials were powder-mixed with a Henschel mixer, and heat kneaded with an extruder. . After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a 50% volume diameter D50 of 7.5 μm. Further classify this, D50 = 8.3μ
m, 5 μm or less, the number distribution was 15%, and a classified product was obtained. The surface wax amount of the obtained toner particles was 38%.
On the other hand, as the external additive, the same silica fine particles a as in Example 1 were used, and 1.0 part by weight of this silica fine particle a was added to 100 parts by weight of the above-mentioned toner and mixed by a Henschel mixer to obtain toner composition 4. Obtained.

Example 5 Styrene-n-butyl acrylate copolymer 48 parts by weight (copolymerization ratio 80:20, high / low molecular ratio 70:30, maximum value on polymer side 1,600,000) (Mw = 290,000, MI = 4.0, Tg = 59 ° C.) Magnetic substance A (hexahedral magnetite, particle size = 0.19 μm) 50 parts by weight Negative charge control agent (azo Cr dye) 0.7 parts by weight Low molecular weight Polypropylene (660P, manufactured by Sanyo Kasei Co., Ltd.) 1 part by weight Low molecular weight polyethylene (softening point = 122 ° C.) 0.3 parts by weight The above materials were powder-mixed with a Henschel mixer, and the mixture was heat-kneaded with an extruder. After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a 50% volume diameter D50 of 8.0 μm. Further classify this, D50 = 8.8μ
As a result, a classified product having a number distribution of m, 5 μm or less and 10% was obtained. The amount of surface wax of the obtained toner particles was 21%.
On the other hand, as the external additive, the same silica fine particles a as in Example 1 were used, and 1.0 part by weight of this silica fine particle a was added to 100 parts by weight of the above-mentioned toner and mixed by a Henschel mixer to obtain a toner composition 5. Obtained.

(Comparative Example 1) Styrene-n-butyl acrylate copolymer 46 parts by weight (copolymerization ratio 80:20, high / low molecular ratio 60:40, polymer side maximum value 1,400,000) (Mw = 220,000, MI = 11.0, Tg = 59 ° C.) Magnetic material B (octahedral magnetite, particle size = 0.22 μm) 50 parts by weight Negative charge control agent (salicylic acid-based Cr dye) 2.0 parts by weight Low Molecular weight polypropylene (660P, manufactured by Sanyo Kasei Co., Ltd.) 2.0 parts by weight The above materials were powder-mixed with a Henschel mixer, and this was heat-kneaded with an extruder. After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a 50% volume diameter D50 of 7.4 μm. Further classify this, D50 = 8.3μ
m was 5 μm or less, and a classified product having a number distribution of 16% was obtained. The amount of surface wax of the obtained toner particles was 28%.
On the other hand, as the external additive, the same silica fine particles a as in Example 1 were used, and 1.0 part by weight of this silica fine particle a was added to 100 parts by weight of the above toner, and mixed by a Henschel mixer to obtain a toner composition 6. Obtained.

Comparative Example 2 Styrene-n-butyl acrylate copolymer 47.3 parts by weight (copolymerization ratio 80:20, high / low molecular ratio 50:50, maximum value on polymer side 1,600,000) ( Mw = 200,000, MI = 10.2, Tg = 59 ° C.) Magnetic substance A (hexahedral magnetite, particle size = 0.19 μm) 50 parts by weight Negative charge control agent (azo-based Cr dye) 0.7 parts by weight Low-molecular-weight polypropylene (660P, manufactured by Sanyo Kasei Co., Ltd.) 2.0 parts by weight The above materials were powder-mixed by a Henschel mixer, and this was heat-kneaded by an extruder. After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a 50% volume diameter D50 of 6.6 μm. This is further classified, D50 = 7.4μ
As a result, a classified product having a number distribution of m, 5 μm or less and 28% was obtained. The amount of surface wax of the obtained toner particles was 31%.
On the other hand, as the external additive, the same silica fine particles a as in Example 1 were used, and 0.8 parts by weight of this silica fine particles a was added to 100 parts by weight of the above-mentioned toner and mixed by a Henschel mixer to obtain toner composition 7. Obtained.

(Comparative Example 3) Styrene-n-butyl acrylate copolymer 46.3 parts by weight (copolymerization ratio 80:20, high / low molecular ratio 70:30, maximum value on polymer side 1,600,000) ( Mw = 290,000, MI = 4.0, Tg = 59 ° C.) Magnetic substance A (hexahedral magnetite, particle size = 0.19 μm) 50 parts by weight Negative charge control agent (azo Cr dye) 0.7 parts by weight Low molecular weight polypropylene (660P, manufactured by Sanyo Kasei Co., Ltd.) 3 parts by weight The above materials were powder-mixed with a Henschel mixer, and the mixture was heat-kneaded with an extruder. After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a 50% volume diameter D50 of 6.2 μm. Further classify this, D50 = 7.0μ
m, 5 μm or less, the number distribution was 33%, and a classified product was obtained. The surface wax amount of the obtained toner particles was 41%.
On the other hand, as the external additive, the same silica fine particles a as in Example 1 were used, and 1.0 part by weight of this silica fine particle a was added to 100 parts by weight of the above-mentioned toner and mixed by a Henschel mixer to obtain a toner composition 8. Obtained.

Comparative Example 4 Styrene-n-butyl acrylate copolymer 48.3 parts by weight (copolymerization ratio 80:20, high / low molecular ratio 70:30, maximum value on polymer side 1,600,000) ( Mw = 290,000, MI = 4.0, Tg = 59 ° C.) Magnetic substance A (hexahedral magnetite, particle size = 0.19 μm) 50 parts by weight Negative charge control agent (azo Cr dye) 0.7 parts by weight Low-molecular-weight polypropylene (660P, manufactured by Sanyo Kasei Co., Ltd.) 1 part by weight The above materials were powder-mixed with a Henschel mixer, and this was heat-kneaded with an extruder. After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a 50% volume diameter D50 of 7.7 μm. Further classify this, D50 = 8.5μ
m, 5 μm or less, the number distribution was 15%, and a classified product was obtained. The surface wax amount of the obtained toner particles was 18%.
On the other hand, as the external additive, the same silica fine particles a as in Example 1 were used, and 1.0 part by weight of this silica fine particle a was added to 100 parts by weight of the above-mentioned toner and mixed by a Henschel mixer to obtain a toner composition 9. Obtained.

Comparative Example 5 A classified product was obtained in the same manner as in Example 1. To 100 parts by weight of the obtained toner particles, colloidal silica (R972, manufactured by Nippon Aerosil Co., Ltd.)
0 parts by weight was added and mixed with a Henschel mixer to obtain a toner composition 10.

Toner composition 1 obtained as described above
10 is used as a developer in the magnetic one-component developing method, and the printer PC-PR1000 manufactured by NEC
Copy 000 sheets, measure the image density of the copied image,
Also, the presence or absence of image quality defects was confirmed. Furthermore, the offset generation temperature was evaluated using a printer PC-PR1000 modified by NEC. The results are shown in Table 1.
In the table, ◯ means a level at which there is no problem in actual use, and x means a level at which it cannot be used.

[0033]

[Table 1]

Example 6 Styrene-n-butyl acrylate copolymer 85 parts by weight (copolymerization ratio 80:20, high / low molecular ratio 70:30, maximum value on polymer side 1,600,000) (Mw = 290,000, MI = 4.0, Tg = 59 ° C.) Carbon black (R-330, manufactured by Cabot) 10 parts by weight Negative charge control agent (TRH, manufactured by Hodogaya Chemical Co., Ltd.) 1 part by weight Low molecular weight polypropylene (660P) 4 parts by weight of the above materials were powder-mixed with a Henschel mixer, and this was heat-kneaded with an extruder. After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a 50% volume diameter D50 of 6.8 μm. Further classify this, D50 = 7.6μ
m, 5 μm or less, the number distribution was 34%, and a classified product was obtained. The surface wax amount of the obtained toner particles was 32%.
On the other hand, as the external additive, the same silica fine particles a as in Example 1 were used, and 1.0 part by weight of this silica fine particle a was added to 100 parts by weight of the above toner, and mixed by a Henschel mixer to obtain toner composition 11. Obtained.

Example 7 Styrene-n-butyl acrylate copolymer 84 parts by weight (copolymerization ratio 80:20, high / low molecular ratio 60:40, maximum value on polymer side 1,600,000) (Mw = 250,000, MI = 9.2, Tg = 59 ° C.) Carbon black (BPL, manufactured by Cabot) 10 parts by weight Negative charge control agent (TRH, manufactured by Hodogaya Chemical Co., Ltd.) 1 part by weight Low molecular weight polypropylene (660P, Sanyo) 5 parts by weight of the above materials were powder-mixed with a Henschel mixer, and this was heat-kneaded with an extruder. After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a 50% volume diameter D50 of 7.9 μm. Further classify this, D50 = 8.8μ
m, 5 μm or less, the number distribution was 15%, and a classified product was obtained. The surface wax amount of the obtained toner particles was 39%.
On the other hand, as the external additive, the same silica fine particles a as in Example 1 were used, and 1.0 part by weight of this silica fine particle a was added to 100 parts by weight of the above-mentioned toner and mixed by a Henschel mixer to form a toner composition 12. Obtained.

Example 8 Styrene-n-butyl acrylate copolymer 86 parts by weight (copolymerization ratio 80:20, high / low molecular ratio 70:30, maximum value on polymer side 1,300,000) (Mw = 260,000, MI = 9.5, Tg = 59 ° C.) Carbon black (BPL, manufactured by Cabot) 10 parts by weight Negative charge control agent (TRH, manufactured by Hodogaya Chemical Co., Ltd.) 1 part by weight Low molecular weight polypropylene (660P, Sanyo) 3 parts by weight The above materials were powder-mixed with a Henschel mixer, and this was heat-kneaded with an extruder. After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a 50% volume diameter D50 of 7.6 μm. Further classify this, D50 = 8.2μ
m was 5 μm or less, and a classified product having a number distribution of 14% was obtained. The amount of surface wax of the obtained toner particles was 21%.
On the other hand, as the external additive, the same silica fine particles a as in Example 1 were used, and 1.0 part by weight of this silica fine particle a was added to 100 parts by weight of the above toner, and mixed with a Henschel mixer to form toner composition 13. Obtained.

Comparative Example 6 Styrene-n-butyl acrylate copolymer 84 parts by weight (copolymerization ratio 80:20, high / low molecular ratio 60:40, maximum value on polymer side 1,400,000) (Mw = 220,000, MI = 11.0, Tg = 59 ° C.) Carbon black (BPL, manufactured by Cabot) 10 parts by weight Negative charge control agent (TRH, manufactured by Hodogaya Chemical Co., Ltd.) 1 part by weight Low molecular weight polypropylene (660P, Sanyo) 5 parts by weight of the above materials were powder-mixed with a Henschel mixer, and this was heat-kneaded with an extruder. After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a 50% volume diameter D50 of 8.0 μm. Further classify this, D50 = 8.6μ
As a result, a classified product having a number distribution of m, 5 μm or less and 10% was obtained. The amount of surface wax of the obtained toner particles was 30%.
On the other hand, as the external additive, the same silica fine particles a as in Example 1 were used, and 1.0 part by weight of the same was added to 100 parts by weight of the above toner, and mixed by a Henschel mixer to form a toner composition 14. Obtained.

Comparative Example 7 83 parts by weight of styrene-n-butyl acrylate copolymer (copolymerization ratio 80:20, high / low molecular ratio 50:50, maximum value on polymer side 1,600,000) (Mw = 200,000, MI = 10.2, Tg = 59 ° C.) Carbon black (R-330, manufactured by Cabot) 10 parts by weight Negative charge control agent (TRH, manufactured by Hodogaya Chemical Co., Ltd.) 1 part by weight Low molecular weight polypropylene (660P) 6 parts by weight of the above materials were powder-mixed with a Henschel mixer, and this was heat-kneaded with an extruder. After cooling, coarse pulverization and fine pulverization were performed to obtain a pulverized product having a 50% volume diameter D50 of 6.9 μm. Further classify this, D50 = 7.7μ
m, 5 μm or less, the number distribution was 24%, and a classified product was obtained. The surface wax amount of the obtained toner particles was 43%.
On the other hand, as the external additive, the same silica fine particles a as in Example 1 were used, and 1.0 part by weight of this silica fine particle a was added to 100 parts by weight of the above-mentioned toner and mixed by a Henschel mixer to obtain a toner composition 15. Obtained.

(Comparative Example 8) A classified product was obtained in the same manner as in Example 6. To 100 parts by weight of the obtained toner particles, colloidal silica (R972, manufactured by Nippon Aerosil Co., Ltd.)
0 parts by weight was added and mixed with a Henschel mixer to obtain a toner composition 16. The toner compositions 11 to 16 obtained in the above Examples and Comparative Examples were used as a two-component developer, and image evaluation was performed. The carrier used and the compounding amount at that time were as follows.

(Manufacturing method of carrier) A ferrite core containing Cu-Zn in an irregular shape, a flat shape, and a spherical shape (particle size: 80 μm)
m) was coated with vinylidene fluoride-hexafluoropropylene copolymer (80/20). Using dimethylformamide as a solvent, 80% by weight of the above copolymer was added to a ferrite core for coating (coating amount 3%). The coated ferrite core was dried at 130 ° C. to obtain a carrier.

97 parts of the carrier and 3 parts of each toner composition were mixed by a V blender to prepare a two-component developer.

By using these developers, a copying machine (Ab
le3301α remodeling machine, made by Fuji Xerox Co., Ltd. 1
Copy 10,000 copies, measure the image density,
The presence or absence of image quality defects was confirmed. Further, the offset generation temperature was evaluated. The results are shown in Table 2. In the table, ◯ means a level at which there is no problem in use, and x means a level at which it cannot be used.

[0043]

[Table 2]

[0044]

As described above, the toner composition for developing an electrostatic image of the present invention defines the addition of silicone oil-treated silica fine particles, the MI of the binder resin and the exposed amount of the low molecular weight polyolefin wax on the toner particle surface. As a result, the maintainability of image quality over time becomes excellent, and filming on the charging member such as the developing sleeve and the carrier and the photoconductor is suppressed, and the offset phenomenon can be improved. Further, according to the image forming method of the present invention, it is possible to form an image excellent in dot reproducibility, fine line reproducibility, and gradation, and it is possible to faithfully reproduce a digital latent image, and at the same time, to fix the fixing latitude. It can be expanded.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuji Sato 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture, Fuji Zelocks Co., Ltd. (72) Inventor Takatoshi Fujii 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (56) References JP-A-4-191864 (JP, A) JP-A-5-249734 (JP, A) JP-A-5-341560 (JP, A) JP-A-2-87159 (JP, A) JP-A-6 -342224 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (2)

(57) [Claims] 1. A toner composition for developing an electrostatic charge image comprising toner particles containing a binder resin, a colorant and a low molecular weight polyolefin wax, and an external additive, wherein the binder resin has a temperature of 150 ° C. and a load of 2160 g. The melt index (MI) under the conditions is 10 g / 10 min or less, the low molecular weight polyolefin wax is polyethylene and / or polypropylene, and the exposure amount x (% by weight) on the toner particle surface is 20 <x <
40, and a toner composition for developing an electrostatic charge image, characterized in that silica particles treated with silicone oil are used as an external additive. 2. A step of forming a latent image on a latent image carrier, a step of developing the latent image with a developer, a step of transferring the developed toner image onto a transfer body, and a toner on the transfer body. An image forming method comprising a fixing step of heating and fixing an image, comprising the toner composition according to claim 1 as the developer.