JP4125199B2 - Image forming method - Google Patents

Description

  The present invention relates to an image forming method in which an electrostatic image formed in a recording method such as an electrophotographic method, an electrostatic recording method, a magnetic recording method, or a toner jet recording method is developed using toner.

  Many methods of electrophotography have been known. In general, an electric latent image (electrostatic latent image) is formed on a photoreceptor by various means using a photoconductive substance, and then the latent image is developed with toner, and paper or the like is used as necessary. After the toner image is transferred to the transfer material, it is fixed by heating, pressure, heating and pressurization or solvent vapor to obtain a copy. The toner remaining without being transferred onto the photoreceptor can be obtained by various methods. After cleaning, the above steps are repeated.

  Numerous methods are known as developing methods for visualizing an electrostatic latent image using toner. As these developing methods, for example, a one-component developing method can be cited, and a developing machine having a simple structure can be used, and there are no troubles, a long lifetime, and easy maintenance, which is preferably used.

  Among the one-component development methods, the toner carrier and the electrostatic latent image carrier are arranged at a certain interval, and a thin layer of toner that does not contact the latent image carrier is formed on the toner carrier. Further, a jumping development method in which development is performed by applying an alternating electric field between the toner carrier and the latent image carrier is preferably used (see, for example, Patent Document 1). In this method, in order to prevent the toner on the developing sleeve as a toner carrier and the toner in the toner container from leaking / scattering from both ends of the developing sleeve, a seal member is provided between the developing sleeve and the toner container. It is done to install.

  Conventionally, as a seal configuration, a method of preventing toner leakage while mechanically scraping the toner on the developing sleeve with felt or the like has been used. This may cause a burden, or may cause the end of the sleeve to rise in temperature and cause toner sticking to the end.

  Therefore, some proposals have been made. For example, a magnetic brush made of toner is formed along at least a part of the circumferential surface at a predetermined distance from the developing sleeve at both end portions in the axial direction of the developing sleeve, and leakage of the toner to the end portion is sealed by the magnetic brush. (For example, refer to Patent Document 2).

  In recent years, with the increase in speed and image quality of copying machines, there have been proposals for providing a plurality of developing sleeves as toner carriers, expanding the developable area, and reducing the peripheral speed of the developing sleeve. However, such a developing method tends to increase the size of the apparatus because a plurality of developing sleeves are used. Therefore, it is often the case that a plurality of developing sleeves are arranged close to each other to be integrated. However, in such an integrated developing device in close proximity, when a developing brush is formed as a magnetic seal member, the flow of the magnetic brush interferes with the magnetic seal member of the other developing sleeve, and toner is generated between the developing sleeves. There is a problem that the toner stays, leaks, or wastes toner that does not contribute to toner fixation or development at the end of the developing sleeve.

On the other hand, in recent years, copying machines have been required to be smaller, lighter, faster, and more reliable, reflecting the changing needs of the market such as compounding and personalization. . As a result, not only the developing device but also the performance required for the toner has become more sophisticated, and further, there is a demand for a developing method that further determines the interaction between the developing device and the toner.

  From the viewpoint of preventing toner deterioration in the developing device due to repeated copying, the hardness of the toner is adjusted. As a method for adjusting the hardness of the toner, various proposals relating to a resin binder have been made (for example, see Patent Document 3). Disclosed is a toner comprising a vinyl polymer that is appropriately cross-linked by adding a binder resin cross-linking agent and a molecular weight modifier in the toner, and further a blend system that combines Tg, molecular weight, and gel content in a vinyl polymer. Toners have been proposed.

  The toner containing such a cross-linked vinyl polymer or gel has an excellent effect on the offset resistance. However, if a cross-linked vinyl polymer is used as a toner raw material in order to contain these, internal friction in the polymer becomes very large in the melt-kneading process at the time of toner production, and a large shearing force is generated in the polymer. It takes. For this reason, in many cases, the molecular chain is broken, resulting in a decrease in melt viscosity and adversely affecting the offset resistance.

  In order to solve this problem, various toners shown below have been proposed. First, there is a method in which a resin having a carboxylic acid and a metal compound are used as raw materials for the toner, and a cross-linked polymer is formed by heat reaction during melt-kneading to contain a vinyl polymer in the toner (for example, Patent Document 4). ~ 7).

  Also proposed is a method of reacting a binder having a vinyl resin monomer and a more specific monoester compound as an essential constituent unit with a polyvalent metal compound and crosslinking via a metal (for example, Patent Documents). 8 and Patent Document 9).

  Furthermore, it has a molecular weight distribution divided into two groups of a low molecular weight component and a high molecular weight component, and is crosslinked by reacting a carboxylic acid group contained on the low molecular weight side with a polyvalent metal ion (solution obtained by solution polymerization). To the toner (for example, see Patent Document 10 to Patent Document 13), the molecular weight of the low and high molecular weight components in the binder resin, the mixing ratio, the acid There have also been proposed toner binder compositions and toners in which the fixability and offset resistance are improved by controlling the value and the ratio thereof (see, for example, Patent Documents 14 to 18).

  In addition, a binder composition for toner in which two kinds of vinyl resins having different molecular weights and resin acid values are blended (for example, see Patent Document 19), a carboxyl group-containing vinyl copolymer and a glycidyl group-containing vinyl copolymer are made of metal. Toner that has been cross-linked by reacting a compound (for example, see Patent Documents 20 to 23), Toner that has reacted with a carboxyl group-containing resin and an epoxy resin to form a cross-linked structure (for example, see Patent Document 24 and Patent Document 25) ), Using a glycidyl group-containing resin as a cross-linking agent, and controlling the molecular weight distribution, gel content, acid value, epoxy value, etc., in a resin composition composed of a carboxyl group-containing resin, improving fixability and offset resistance, etc. Toner binder compositions and toners have been proposed (see, for example, Patent Document 26 to Patent Document 34).

It is a fact that the above proposal is effective in improving the fixing property and the offset resistance, although there are advantages and disadvantages. However, there are problems in ultra-high speed and high durability, and in a developing device having a plurality of developing sleeves, there is a problem that toner fusion or the like is likely to occur at the end of the developing sleeve.
Japanese Patent Publication No.58-32375 JP-A-2-262171 Japanese Patent Publication No.51-23354 JP 55-90509 A JP 57-178249 A JP 57-178250 A JP-A-60-4946 JP-A-61-1110155 Japanese Patent Laid-Open No. 61-110156 JP-A-63-214760, JP 63-217362 A JP 63-217363 A JP 63-217364 A JP-A-2-168264 Japanese Patent Laid-Open No. 2-235069 JP-A-5-173363 JP-A-5-173366 JP-A-5-241371 JP 62-9256 A Japanese Patent Laid-Open No. 3-63661 Japanese Patent Laid-Open No. 3-63662 Japanese Patent Laid-Open No. 3-63663 Japanese Patent Laid-Open No. 3-118552 JP-A-7-225491 JP-A-8-44107 JP-A-62-194260 JP-A-6-11890 JP-A-6-222612 Japanese Patent Laid-Open No. 7-20654 Japanese Patent Laid-Open No. 9-185182 JP-A-9-244295 JP-A-9-319410 Japanese Patent Laid-Open No. 10-87837 JP-A-10-90943

  An object of the present invention is to solve the above-described problems and to provide an image forming method excellent in developability and durability.

  Furthermore, an object of the present invention is to provide an image forming method having a developing step of forming a toner image by developing with a magnetic toner formed in a thin layer on a plurality of toner carriers, at both ends in the axial direction of the toner carrier. An object of the present invention is to provide an image forming method in which there is no occurrence of contamination in the apparatus due to magnetic toner leakage from a toner seal member provided along a part of the peripheral surface, and there is no toner fusion to the end of the toner carrier. .

  As a result of intensive studies, the present inventors have specific magnetic characteristics in an image forming method having a developing step of developing a toner image by developing with a magnetic toner formed in a thin layer on a plurality of toner carriers. By using a toner and providing a toner seal member along the peripheral surface of a part of both ends in the axial direction of the toner carrier, there is no occurrence of contamination in the apparatus due to magnetic toner leakage from the toner seal member, and further the toner carrying It has been found that an image forming method without toner fusion to the end of the body can be achieved.

That is, the present invention provides an image forming process having at least a developing step of developing a latent electrostatic image formed on a latent image holding member with a magnetic toner formed as a thin layer on a plurality of developing sleeves to form a toner image. In the method
The plurality of developing sleeves used in the developing step are rotating bodies, and a substantially cylindrical magnetic field generating means having a plurality of magnetic poles is fixedly disposed therein,
A toner seal member made of a magnetic material is provided along at least a part of the peripheral surface of both end portions in the axial direction of the plurality of developing sleeves ,
The toner seal member and the developing sleeve are arranged with a certain gap,
Wherein the magnetic field generated between the toner seal member and the developing sleeve within said magnetic field generating means, between the counter surface and the developing sleeve end portions peripheral surface with respect to the developing sleeve of the toner seal member, a magnetic toner A magnetic brush is formed,
The magnetic toner has toner particles containing at least a binder resin and a magnetic material, has a residual magnetization σr of 0.5 to 8.0 (Am ² / kg), and a coercive force Hc (kA / m). The image forming method, wherein the residual magnetization σr (Am ² / kg) satisfies the following formula (1):
(1) 5 ≦ Hc × σr ≦ 85

  The present invention can provide an image forming method excellent in developability and durability. Further, even when a plurality of toner carriers are used, there is no occurrence of contamination in the apparatus due to toner leakage from the toner seal member at the end of the toner carrier, and there is no toner fusion to the end of the toner carrier. Can provide.

  The image forming method of the present invention includes a developing step of developing a latent electrostatic image formed on a latent image holding member with a magnetic toner formed in a thin layer on a plurality of toner carriers to form a toner image. Have at least.

In the developing step of the image forming method of the present invention, the plurality of toner carriers are rotating bodies, and a substantially cylindrical magnetic field generating means having a plurality of magnetic poles is fixedly disposed therein.
A toner seal member formed of a magnetic substance is provided along at least a part of the circumferential surface of both end portions in the axial direction of the plurality of toner carriers,
The toner seal member and the toner carrier are arranged with a certain gap,
Due to the magnetic field generated between the toner seal member and the magnetic field generating means inside the toner carrier, between the surface of the toner seal member facing the toner carrier and the peripheral surfaces of both ends of the toner carrier, A magnetic brush made of magnetic toner is formed.

The magnetic toner used in the present invention has toner particles containing at least a binder resin and a magnetic material, and the coercive force Hc (kA / m) and the residual magnetization σr (Am ² / kg) satisfy the following formula (1). It is characterized by that.
(1) 5 ≦ Hc × σr ≦ 85
Preferably, 12 ≦ Hc × σr ≦ 85, and more preferably 25 ≦ Hc × σr ≦ 85. When Hc × σr is 5 or more and 85 or less, there is no occurrence of toner leakage from the toner seal member provided on the circumferential surface at both end portions in the axial direction of the toner carrier, and excellent developability can be maintained. .

  On the other hand, when the product (Hc × σr) of the coercive force and the residual magnetization of the magnetic toner is less than 5, it is difficult to be influenced by the magnetic field at the end seal portion, and toner leakage occurs when the toner carrier rotates at high speed. Occurs, and the inside of the machine is easily contaminated, which may cause the main body to malfunction.

  When Hc × σr exceeds 85, the toner sealability at the end seal portion is good, but the magnetic binding force from the toner carrier is increased, and the density is likely to decrease.

  The coercive force Hc of the magnetic toner is preferably 4.0 to 15.0, and the residual magnetization σr is preferably 0.5 to 8.0.

  When the magnetic toner of the present invention contains at least one metal oxide and / or metal carbide having a primary particle size of 0.05 to 3.0 μm, the fusion of the toner to the end of the toner carrier is prevented. Therefore, it is preferable because of excellent concentration stability even in long-term use.

  When the primary particle size of the metal oxide and / or metal carbide exceeds 3.0 μm, it is difficult to develop simultaneously with the magnetic toner during development, and the metal oxide and / or metal carbide accumulated in the developing device without being consumed. This tends to cause a decrease in image density. In particular, in an image forming method using a developing system having a plurality of toner carriers as in the present invention, the movement of magnetic toner in the developing unit becomes complicated, and the number of frictions between toners or between toner carriers increases. In addition, the metal oxide and / or metal carbide is likely to be liberated from the toner, and the image density is significantly lowered.

  Further, when the primary particle diameter of the metal oxide and / or metal carbide is less than 0.05 μm, the metal oxide and the metal oxide and the toner seal member provided along the circumferential surface at both ends in the axial direction of the toner carrier In other words, the amount of metal carbide passing through is increased, which is likely to cause toner leakage from the toner seal member.

  The metal oxide and / or metal carbide is an oxide, carbide, or magnesium oxide of oxygen acid containing at least one element of Ti, Ce, Al, Zn, Mg, W, Sn, Zr, and Fe. It is preferably selected from the group consisting of a salt, calcium salt, strontium salt and barium salt.

  Among them, especially from strontium titanate, magnesium titanate, calcium titanate, barium titanate, titanium oxide, cerium oxide, aluminum oxide, zinc oxide, tin oxide, iron oxide, ferrite, silica, tungsten carbide and silicon carbide It is preferably selected from the group consisting of

  When the above-mentioned substances are used as metal oxides and / or metal carbides, the magnetic toner particle hardness can be appropriately adjusted without impairing the charging stability of the magnetic toner, and since it has a suitable abrasiveness, it can be used for other than latent image holders. Only the fusion of the toner to the toner carrier can be removed without damaging the process member.

  The metal oxide and / or metal carbide is 0.1 to 8.0 parts by weight (preferably 1.0 to 8.0 parts by weight, particularly preferably 2.0 to 8.0 parts by weight based on 100 parts by weight of the toner particles. (Mass part). When the added amount of the metal oxide and / or metal carbide exceeds 8.0 parts by mass, the metal oxide and / or metal carbide is liable to be liberated from the magnetic toner, and the liberated material may damage the latent image holding member or the like. The toner tends to inhibit charging and cause a decrease in density.

  Further, when the addition amount of the metal oxide and / or metal carbide is less than 0.1 parts by mass, it is difficult to achieve the effect, and toner fusion to the toner carrier is likely to occur. It is easy to cause toner leakage from the toner.

  The metal oxide and / or metal carbide preferably used in the present invention is produced, for example, by a sintering method, mechanically pulverized, classified by air classification to obtain a desired particle size, and subjected to an appropriate post-treatment when necessary. Is.

The magnetic toner in the present invention is a magnetic toner having a particle diameter of 3 μm or more, and has 85% by number or more of particles having a circularity a represented by the following formula (2) of 0.90 or more, more preferably 90%. It is preferable to have a number% or more (90 to 100 number%).
(2) Circularity a = L ₀ / L
(In the formula, L ₀ represents the perimeter of a circle having the same area as the projected image of the particle, and L represents the perimeter of the projected image of the particle.)
In the present invention, the circularity is an index of the degree of unevenness of the magnetic toner particles, and indicates 1.00 when the magnetic toner is a perfect sphere, and the circularity becomes smaller as the surface shape becomes more complicated.

  If the content of particles having a circularity a of 0.90 or more in the magnetic toner is less than 85% by number, the shape of the magnetic toner becomes distorted, and the friction between the magnetic toner and the toner carrier increases. The carrier is easily polished. This tends to reduce the life of the toner carrier.

  In the magnetic toner of the present invention, the standard deviation SD of the circularity distribution is preferably 0.050 or less from the viewpoint of image quality and transferability. The SD of the circularity distribution in the present invention is an index of the breadth of the distribution. The smaller the numerical value, the sharper the distribution is. In the present invention, the standard deviation SD of the circularity distribution uses a value obtained by the following equation (3) from the circularity and average circularity of each particle of the magnetic toner.

(3)
The weight average particle size of the magnetic toner in the present invention is preferably 3.0 to 9.0 μm. When the weight average particle diameter of the magnetic toner is less than 3.0 μm, the adhesion force between the magnetic toners increases, the cohesiveness increases, and the fog and the like tend to increase. Further, when the weight average particle diameter of the magnetic toner exceeds 9.0 μm, the charge amount of the magnetic toner is decreased, and the image density is likely to be lowered due to durability.

  The magnetic toner in the present invention is a magnetic toner containing a magnetic material and can be used as a one-component developer. In this case, the magnetic material can also serve as a colorant. In the present invention, examples of the magnetic material used for forming the magnetic toner include metal oxides containing elements of iron, cobalt, nickel, copper, magnesium, manganese, aluminum, or silicon. Among them, those containing iron oxide as a main component such as triiron tetroxide and γ-iron oxide are preferable.

  Furthermore, the magnetic body in the present invention preferably has an octahedral shape. By having octahedral-shaped surfaces and vertices, the toner particles have good wettability with other materials and excellent dispersibility, and can be deposited on the toner particle surface moderately, and the magnetic toner has excellent charging stability. It becomes.

  Further, the apex of the octahedron shape is exposed on the surface of the toner particles, which produces a moderate polishing effect, so that it is possible to reduce the occurrence of toner fusion to the end of the toner carrier.

  These magnetic materials preferably have an average particle size of 2 μm or less, preferably about 0.1 to 0.5 μm. The amount to be contained in the toner particles is preferably 20 to 200 parts by mass, particularly preferably 40 to 150 parts by mass with respect to 100 parts by mass of the binder resin.

Furthermore, the saturation magnetization σs of these magnetic materials is 5 to 200 Am ² / kg, preferably 50 to 150 Am ² / kg, more preferably 70 to 100 Am ² / kg.

The residual magnetization σr of the magnetic material is 1 to 30 Am ² / kg, preferably 5 to 25 Am ² / kg, and more preferably 8 to 15 Am ² / kg.

  The coercive force Hc of the magnetic material is 2 to 20 kA / m, preferably 6 to 15 kA / m, and more preferably 8 to 12 kA / m.

  In the present invention, since the magnetic material has the above magnetic characteristics, the image density and the fog are balanced, and toner leakage at the end of the toner carrying member is difficult to occur. Also, a magnetic toner satisfying the above formula (1) can be obtained by using a magnetic material having the above characteristics and adjusting the amount of the magnetic material in the toner particles.

  The magnetic material having the above characteristics (magnetization characteristics, octahedral shape, average particle diameter) used in the present invention can be manufactured by the following method which is a general manufacturing method. First, an alkaline aqueous solution is added to an iron sulfate (+2) aqueous solution to obtain iron hydroxide, oxygen is fed into this aqueous solution, and an oxidation reaction is performed to obtain a magnetic substance. At this time, a magnetic material having a desired shape, particle size, and magnetic properties can be obtained by adjusting the pH, temperature, Fe concentration, and oxidation conditions of the aqueous solution.

  In addition, elements other than iron, such as Si, Mn, Zn, Ni, Cu, Al, and Ti, may be included as necessary, and similarly, pH, temperature, amount of added element, addition time, and addition method are adjusted. By doing so, the presence state of the additive element in the magnetic material can be controlled.

  In the present invention, the binder resin used for the toner particles includes a vinyl resin having a carboxyl group and a vinyl resin having an epoxy group, a vinyl resin having a carboxyl group and an epoxy group, and a vinyl resin in which the carboxyl group and the epoxy group are reacted. It is preferable that at least one vinyl resin selected from the group is contained, and the acid value of the THF soluble portion of the magnetic toner is 1 to 50 mgKOH / g.

  The magnetic toner in the present invention is hot-melt kneaded in a kneading step or the like in the toner manufacturing process, and the binder resin undergoes a crosslinking reaction by using the vinyl resin as the binder resin. At that time, it is possible to include other materials such as a magnetic substance under the crosslinking reaction of the carboxyl group and the epoxy group in the binder resin, and the affinity between the binder resin and the other material is increased, which is good in the toner particles. Can achieve high dispersibility and has an appropriate toner toughness, so that there is little occurrence of toner fusion to a plurality of toner-carrying member supporting portions, and durability can be suppressed, and detachment of magnetic materials from toner can be suppressed. As a result, the contamination of the toner carrier can be suppressed.

  The magnetic toner in the present invention can toughen the toner itself by performing a crosslinking reaction as described above, and achieves stable durability even when the copy volume increases when applied to a high-speed machine or the like. it can. The monomer constituting the vinyl resin will be described later.

  In the magnetic toner according to the present invention, the acid value of the THF-soluble component is preferably 1.0 to 50 mgKOH / g, and more preferably 1.0 to 40 mgKOH / g. Since the magnetic toner has a desired acid value, good developability and durability can be achieved.

  When the acid value of the THF soluble component of the magnetic toner is less than 1.0 mgKOH / g, the dispersibility is not improved due to the interaction between the carboxyl group and the magnetic material, and the resulting anti-detachment effect from the toner particles tends not to appear. is there. If it exceeds 50 mgKOH / g, the magnetic toner tends to absorb moisture in a high humidity environment and the density tends to decrease.

  In the present invention, the number average molecular weight is preferably 1,000 to 40,000, more preferably 2,000 to 20,000, particularly in the molecular weight distribution measured by GPC of the THF soluble component in the magnetic toner. The molecular weight is preferably 3,000 to 15,000, and the mass average molecular weight is preferably 10,000 to 10,000,000, more preferably 20,000 to 5,000,000, particularly preferably 30,000. It is good that it is -1,000,000.

When the magnetic toner used in the present invention exhibits the above average molecular weight in the GPC chromatogram of the THF-soluble component, the magnetic toner can maintain appropriate toughness, and the magnetic toner is applied to the developing portion. Even in a developing method having a plurality of toner carriers having a large share, good developability and durability can be achieved, and occurrence of toner fusion to the toner carrier can be suppressed.

  When the number average molecular weight is less than 1,000 or the mass average molecular weight is less than 10,000, the melt viscosity of the magnetic toner is lowered, resulting in a non-uniform charge distribution, deterioration of fogging, etc. It is easy to develop toner fusion to the body. When the number average molecular weight exceeds 40,000 or the mass average molecular weight exceeds 10,000,000, the compatibility between the high molecular component and the low molecular component in the binder resin deteriorates, and the binder resin itself There is a tendency that the component distribution becomes non-uniform, the material dispersibility in the toner deteriorates, and the dot reproducibility deteriorates. The high molecular weight component and low molecular weight component of the binder resin will be described later.

  Furthermore, in the present invention, the molecular weight distribution measured by GPC of the THF-soluble component in the magnetic toner preferably has a main peak in the region of molecular weight 4,000 to 30,000, more preferably molecular weight 5 Those having a main peak in the region of 20,000 to 20,000 are preferable.

  When the main peak has a molecular weight of less than 4,000, toner fusion to the toner carrier tends to occur in a high temperature environment. When the molecular weight exceeds 30,000, the material dispersibility tends to deteriorate and the dot reproducibility tends to deteriorate.

  In the molecular weight distribution, the peak area having a molecular weight of 30,000 or less is preferably 60 to 100% of the entire peak area. When the peak area having a molecular weight of 30,000 or less is within the above range, good material dispersibility can be achieved in the toner particles. When the peak area with a molecular weight of 30,000 or less is less than 60% of the total peak area, the melt viscosity of the resin increases, and it tends to be difficult to uniformly disperse with other materials during melt-kneading during magnetic toner production. is there.

  Further, the magnetic toner in the present invention preferably contains 0.1 to 60% by mass, preferably 5 to 60% by mass, more preferably 10 to 45% by mass of the THF insoluble matter. When the THF-insoluble content is within the above range, it is possible to achieve a uniform dispersibility of the material in the toner particles and to have an appropriate toughness of the magnetic toner itself, thereby achieving good developability and durability. Can be achieved.

  When the THF insoluble content exceeds 60% by mass, the melt viscosity of the binder resin increases, the dispersion state of the material in the toner particles deteriorates, and the toner becomes non-uniformly charged. Have a non-uniform charge distribution, and the dot reproducibility tends to deteriorate.

  In the present invention, the glass transition temperature (Tg) of the magnetic toner is preferably 50 to 70 ° C. When Tg is less than 50 ° C., the storage stability is deteriorated, and when it exceeds 70 ° C., the fixability tends to be deteriorated. The magnetic toner according to the present invention preferably has an epoxy value of 0.0001 to 5.0 eq / kg of the THF soluble component. When the epoxy value is less than 0.0001 eq / kg, the dielectric loss of the magnetic toner tends to decrease, and fog or the like is likely to occur due to excessive charging of some toner particles in a low humidity environment. On the other hand, when the epoxy value is 5.0 eq / kg or more, in the high humidity environment, conversely, fogging or the like easily occurs due to insufficient charge amount of some toners.

In the present invention, the magnetic toner is selected from the group consisting of a vinyl resin having a carboxyl group and a vinyl resin having an epoxy group, a vinyl resin having a carboxyl group and an epoxy group, and a resin obtained by reacting these functional groups. It is preferable to contain at least one kind of vinyl resin.

  The following are mentioned as a monomer which has a carboxyl group unit which comprises the vinyl resin which has a carboxyl group. For example, acrylic acid such as acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, cinnamic acid, vinyl acetic acid, isocrotonic acid, tiglic acid and angelic acid, their anhydrides and α- or β-alkyl derivatives, fumarate Acid, maleic acid, citraconic acid, alkenyl succinic acid, itaconic acid, mesaconic acid, dimethylmaleic acid, dimethylfumaric acid and other unsaturated dicarboxylic acids, their monoester derivatives, anhydrides and α- or β-alkyl derivatives, etc. Can be mentioned.

  A monomer having such a carboxyl group unit can be obtained alone or in combination of several kinds and copolymerized with other vinyl monomers by a known polymerization method to obtain a vinyl resin having a carboxyl group.

  Examples of other vinyl monomers include the following.

  For example, styrene; o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4 -Dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn- Styrene derivatives such as dodecylstyrene; Ethylene unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; Unsaturated polyenes such as butadiene and isoprene; Halogenation such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride Vinyls: vinyl acetate, vinyl propionate, vinyl benzoate, etc. Esters: methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, methacrylic acid (2-ethylhexyl), stearyl methacrylate, phenyl methacrylate , Α-methylene aliphatic monocarboxylic acid esters such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, acrylic acid-1 -Acrylic esters such as octyl, dodecyl acrylate, acrylic acid (2-ethylhexyl), stearyl acrylate, acrylic acid (2-chloroethyl), phenyl acrylate; vinyl methyl ether Vinyl ethers such as vinyl ethyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, etc. N-vinyl compounds of the above; vinyl naphthalenes; acrylic acid derivatives or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide. These vinyl monomers are used alone or in admixture of two or more monomers.

  Among these, a combination of monomers that becomes a styrene copolymer and a styrene-acrylic copolymer is preferable. In this case, at least a styrene copolymer component or a styrene-acrylic copolymer component in the binder resin. Is preferably 65% by mass or more from the viewpoint of mixing properties.

The acid value of the vinyl resin having a carboxyl group is preferably 0.5 to 60 mgKOH / g. When the amount is less than 0.5 mg KOH / g, the number of cross-linking reaction sites between the carboxyl group and the epoxy group decreases, so that the cross-linking component is small and the durability of the magnetic toner is hardly exhibited. In such a case, compensation can be made to some extent by using a vinyl resin having an epoxy group having a high epoxy value as a binder resin. When it exceeds 60 mgKOH / g, when applied to a positively chargeable toner, the negative chargeability of the binder resin in the toner particles becomes strong, the image density tends to decrease, and the fog tends to increase.

  The glass transition temperature (Tg) of the vinyl resin having a carboxyl group is preferably 40 to 70 ° C. When Tg is less than 40 ° C., the blocking resistance of the magnetic toner deteriorates, and when it exceeds 70 ° C., the fixability of the toner tends to deteriorate.

  In the vinyl resin having a carboxyl group, the number average molecular weight is preferably 1,000 to 40,000 in order to achieve good fixability and developability, and the mass average molecular weight is good offset resistance and blocking resistance. And 10,000 to 10,000,000 are preferable in order to achieve durability.

  The vinyl resin having a carboxyl group is desirably composed of a low molecular weight component and a high molecular weight component. The peak molecular weight of the low molecular weight component is preferably 4,000 to 30,000 in order to achieve good fixability, and the peak molecular weight of the high molecular weight component achieves good offset resistance, blocking resistance and durability. Therefore, 100,000 to 1,000,000 is preferable.

  As a method for synthesizing a high molecular weight component of a vinyl resin having a carboxyl group, a polymerization method that can be used in the present invention includes a bulk polymerization method, a solution polymerization method, an emulsion polymerization method, and a suspension polymerization method.

  Among them, the emulsion polymerization method is a method in which a monomer (monomer) almost insoluble in water is dispersed as small particles in an aqueous phase with an emulsifier, and polymerization is performed using a water-soluble polymerization initiator. In this method, the heat of reaction can be easily adjusted, and since the phase in which the polymerization is carried out (the oil phase consisting of the polymer and the monomer) and the aqueous phase are different, the termination reaction rate is low, resulting in a high polymerization concentration. A product having a high degree of polymerization is obtained. Furthermore, since the polymerization process is relatively simple and the polymerization product is fine particles, the toner can be easily mixed with colorants, charge control agents and other additives in the production of the toner. There is an advantage as a method for producing a binder resin.

  However, due to the added emulsifier, the polymer tends to be impure, and an operation such as salting out is necessary to take out the polymer, and solution polymerization and suspension polymerization are convenient to avoid this inconvenience.

  In suspension polymerization, it is good to carry out by 100 mass parts or less (preferably 10-90 mass parts) of monomers with respect to 100 mass parts of aqueous solvents. Examples of the dispersant that can be used include polyvinyl alcohol, partially saponified polyvinyl alcohol, calcium phosphate, and the like, and generally 0.05 to 1 part by mass with respect to 100 parts by mass of the aqueous solvent. The polymerization temperature is suitably 50 to 95 ° C., but is appropriately selected depending on the initiator used and the target polymer.

  In order to achieve the object of the present invention, the high molecular weight component used in the preparation of the binder resin includes a monomer used for a vinyl resin having a carboxyl group and a polyfunctional polymerization initiator exemplified below or a monofunctional It is preferable to produce | generate together with a photopolymerization initiator.

Specific examples of the polyfunctional polymerization initiator include 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,3-bis- (t-butylperoxyisopropyl) benzene, , 5-dimethyl-2,5- (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di- (t-butylperoxy) hexane, tris- (t-butylperoxy) triazine, 1,1-di-t-butylperoxycyclohexane, 2,2-di-t-butylperoxybutane, 4,4-di-t-butylperoxyvaleric acid-n
-Butyl ester, di-t-butylperoxyhexahydroterephthalate, di-t-butylperoxyazelate, di-t-butylperoxytrimethyladipate, 2,2-bis- (4,4-di-t- Multifunctional polymerization initiation having a functional group having a polymerization initiating ability such as two or more peroxide groups in one molecule such as butylperoxycyclohexyl) propane, 2,2-t-butylperoxyoctane and various polymer oxides Agents; and polymerization initiation ability of peroxide groups and the like in one molecule such as diallyl peroxydicarbonate, t-butylperoxymaleic acid, t-butylperoxyallylcarbonate and t-butylperoxyisopropyl fumarate Examples thereof include a polyfunctional polymerization initiator having both a functional group and a polymerizable unsaturated group.

  Of these, more preferred are 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-t-butylperoxycyclohexane, di-t-butylperoxyhexa Hydroterephthalate, di-t-butylperoxyazelate and 2,2-bis- (4,4-di-t-butylperoxycyclohexane) propane and t-butylperoxyallyl carbonate.

  These polyfunctional polymerization initiators are preferably used in combination with a monofunctional polymerization initiator in order to satisfy various performances required as a binder resin for toner. In particular, it is preferable to use in combination with a polymerization initiator having a half-life of 10 hours lower than the decomposition temperature for obtaining a half-life of 10 hours of the polyfunctional polymerization initiator.

  Specific examples of the monofunctional polymerization initiator include benzoyl peroxide, 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4-di (t Organic peroxides such as -butylperoxy) valerate, dicumyl peroxide, α-α'-bis (t-butylperoxydiisopropyl) benzene, t-butylperoxycumene, di-t-butylperoxide, And azo and diazo compounds such as azobisisobutyronitrile and diazoaminoazobenzene.

  These monofunctional polymerization initiators may be added to the monomer at the same time as the polyfunctional polymerization initiator. However, in order to keep the efficiency of the polyfunctional polymerization initiator properly, the polyfunctional polymerization initiator may be polyfunctional in the polymerization process. It is preferably added after the half-life indicated by the polymerizable polymerization initiator has elapsed.

  These initiators are preferably used in an amount of 0.01 to 10 parts by mass with respect to 100 parts by mass of the monomer from the viewpoint of efficiency.

  As a method for synthesizing the low molecular weight component of the vinyl resin having a carboxyl group, a known method can be used. However, in the bulk polymerization method, a low molecular weight component can be obtained by polymerizing at a high temperature to increase the termination reaction rate, but there is a problem that the reaction is difficult to control. On the other hand, in the solution polymerization method, a low molecular weight component can be easily obtained under mild conditions by utilizing the difference in chain transfer of radicals by a solvent and adjusting the amount of initiator and reaction temperature. It is preferable to obtain a low molecular weight component in the vinyl resin having a group.

  As a solvent used in the solution polymerization, xylene, toluene, cumene, cellosolve acetate, isopropyl alcohol or benzene is used. When a styrene monomer is used as the other vinyl monomer, xylene, toluene or cumene is preferable. The solvent is appropriately selected depending on the polymer to be polymerized. The reaction temperature varies depending on the solvent to be used, the polymerization initiator, and the polymer to be polymerized, but it is usually preferable to carry out at 70 to 230 ° C. In the solution polymerization, the polymerization is preferably performed with 30 to 400 parts by mass of the monomer with respect to 100 parts by mass of the solvent.

Furthermore, it is also preferable to mix other polymers in the solution at the end of the polymerization, and several types of polymers can be mixed.

  Moreover, the inside of the vinyl resin which has an epoxy group used by this invention is demonstrated. In the present invention, the epoxy group is a functional group in which an oxygen atom is bonded to two carbon atoms in the same molecule, and has a cyclic ether structure. Typical cyclic ether structures include a 3-membered ring, a 4-membered ring, a 5-membered ring, and a 6-membered ring. Among them, a 3-membered ring structure is preferable.

  The following are mentioned as a monomer which has an epoxy group unit which comprises the vinyl resin which has an epoxy group. Examples include glycidyl acrylate, glycidyl methacrylate, β-methyl glycidyl acrylate, β-methyl glycidyl methacrylate, allyl glycidyl ether, and allyl β-methyl glycidyl ether. Moreover, the glycidyl monomer represented by General formula (1) is used preferably.

(In the above general formula (1), R ₁ , R ₂ and R ₃ may be the same or different, and represent hydrogen, an alkyl group, an aryl group, an aralkyl group, a carboxyl group and an alkoxycarbonyl group.)
A monomer having such an epoxy group unit can be obtained singly or in combination, and can be copolymerized with the above-mentioned other vinyl monomers by a known polymerization method to obtain a vinyl resin having an epoxy group.

  The vinyl resin having an epoxy group has a mass average molecular weight (Mw) of preferably 2,000 to 100,000, more preferably 2,000 to 50,000, still more preferably 3,000 to 40,000. Is good. When Mw is less than 2,000, the molecular weight increases due to the cross-linking reaction in the binder resin, and there is a tendency for the molecules to be cut frequently by the kneading step, thereby deteriorating the durability. When Mw exceeds 100,000, the fixability tends to be affected.

  The epoxy value of the vinyl resin having an epoxy group is preferably 0.05 to 5.0 eq / kg. When the amount is less than 0.05 eq / kg, the crosslinking reaction does not proceed easily, the amount of high molecular weight components and THF-insoluble components generated decreases, and the toughness of the toner tends to decrease. On the other hand, if it exceeds 5.0 eq / kg, the crosslinking reaction is likely to occur, but there are many molecular breaks in the kneading step, and the dispersibility with other materials tends to deteriorate.

  When the epoxy value of the vinyl resin having an epoxy group is in the above range, the epoxy group can be uniformly dispersed in the toner particles, thereby appropriately increasing and controlling the dielectric loss of the magnetic toner. It becomes. Even in the developing device configuration having a plurality of toner carriers as in the present invention, the toner can be uniformly charged without depending on the environmental temperature change.

  The vinyl resin having an epoxy group has a mixing ratio of 0.01 to 10.0 equivalents, preferably 0.03 to 5.0 equivalents of an epoxy group with respect to 1 equivalent of a carboxyl group in the vinyl resin having a carboxyl group. It is preferable to be used.

  When the epoxy group is less than 0.01 equivalent, the number of cross-linking points in the binder resin is reduced, and the effects of the cross-linking reaction such as durability are hardly exhibited. On the other hand, when the amount exceeds 10 equivalents, the crosslinking reaction tends to occur, but on the other hand, the dispersibility deteriorates due to the generation of excess THF-insoluble matter and the like, and the grindability deteriorates and the development stability becomes a problem.

  In the present invention, it is also preferable to use a vinyl resin having a carboxyl group and an epoxy group as the binder resin. In the vinyl resin having a carboxyl group and an epoxy group, the number average molecular weight is preferably 10,000 to 40,000 in order to achieve good developability and durability. The mass average molecular weight is preferably 10,000 to 10,000,000 to achieve offset resistance, blocking resistance and durability.

  The vinyl resin having a carboxyl group and an epoxy group can be obtained by mixing a monomer having a carboxyl group unit and a monomer having an epoxy group unit, and copolymerizing it with another vinyl monomer by a known polymerization method.

In the present invention, a vinyl resin obtained by reacting a carboxyl group and an epoxy group obtained by reacting a vinyl resin having a carboxyl group and a vinyl resin having an epoxy group in advance at the time of resin production may be used. Examples of the reaction method include the following methods.
(1) A vinyl resin having a carboxyl group and a vinyl resin having an epoxy group are mixed in a solution state, and a crosslinking reaction is caused by applying heat in a reaction kettle.
(2) A vinyl resin having a carboxyl group and a vinyl resin having an epoxy group are each taken out from the reaction kettle, dry blended with a Henschel mixer, etc., and hot melt kneaded with a biaxial extruder, etc., to cause a crosslinking reaction. .

  When using the vinyl resin which the said carboxyl group and the epoxy group reacted, it is preferable to contain 0.1-60 mass% of THF insoluble matters. When the THF-insoluble content is in the above range, the binder resin itself can have an appropriate melt viscosity in the kneading step in the toner particle manufacturing step, so that uniform dispersibility of the material can be achieved.

  When the THF-insoluble content exceeds 60% by mass, the melt viscosity of the binder resin itself tends to increase and the dispersibility of the material tends to deteriorate.

  As the binder resin used in the magnetic toner in the present invention, the following polymers can also be used. For example, styrene such as polystyrene, poly-p-chlorostyrene, polyvinyltoluene, etc., and homopolymers thereof; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer , Styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl Styrene copolymers such as ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer; polyvinyl chloride, phenol Resin, natural modified pheno Resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin And petroleum-based resin can be used.

The magnetic toner used in the present invention preferably contains a charge control agent in order to maintain positive chargeability or negative chargeability.

  As the charge control agent for controlling the magnetic toner to be positively charged, there are the following substances.

  For example, modified products such as nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and phosphonium salts that are analogs thereof Onium salts and lake pigments thereof; triphenylmethane dyes and lake pigments thereof (as rake agents, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide) Metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, dicyclo Diorgano tin borate such as hexyl tin borate; guanidine compounds, imidazole compounds. These can be used alone or in combination of two or more. Among these, triphenylmethane compounds, imidazole compounds, and quaternary ammonium salts whose counter ions are not halogen are preferably used.

  In addition, as a charge control agent for controlling the toner to be negatively charged, there are the following substances.

  For example, organometallic complexes and chelate compounds are effective, and there are monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acid metal complexes, and aromatic dicarboxylic acid metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic monocarboxylic acids and aromatic polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

  As a method of incorporating a charge control agent into the magnetic toner, there are a method of adding it inside the toner and a method of adding it externally. The amount of these charge control agents used is determined by the magnetic toner production method including the type of binder resin, the presence or absence of other additives, and the dispersion method, but is not uniquely determined, but preferably Is used in the range of 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the binder resin.

  In the present invention, the following waxes are preferably contained in order to impart releasability to the magnetic toner. The melting point is 70 to 165 ° C., and the melt viscosity at 160 ° C. is 1000 mPa · s or less. Specific examples thereof include paraffin wax, microcrystalline wax, Fischer-Tropsch wax, montan wax, ethylene, propylene, butene, penten. , Homopolymers of linear α-olefins such as hexene, heptene, octene, nonene, decene, etc., branched α-olefins having a branched portion at the end thereof, and olefins having different positions of these unsaturated groups, or these And the like. In addition, alcohol wax, fatty acid wax, ester wax, and natural wax are also used.

  The melting point of the wax is represented by the temperature of the main peak value in the endothermic curve measured according to ASTM D3418-8. For example, DSC-7 manufactured by PerkinElmer or DSC2920 (manufactured by TA Instruments Japan) Can be measured at a temperature elevation rate of 10 ° C./min. The melt viscosity of the wax can be measured, for example, using a cone plate type rotor (PK-1) with VT-500 manufactured by HAAKE.

  Further, a block copolymer made of a vinyl monomer, a modified wax subjected to graft modification, or an oxidized wax subjected to an oxidation treatment may be used.

  These waxes can be added and mixed in advance in the polymer component when the magnetic toner is produced. In this case, it is preferable to preliminarily dissolve the wax and the polymer having a high molecular weight component in a solvent at the time of preparing the polymer component, and then mixing the polymer solution with the low molecular weight component. As a result, phase separation in the microscopic region is relaxed, reaggregation of the high molecular weight component is controlled, and a good dispersion state with the low molecular weight component is also obtained.

  Moreover, it is preferable that it is 0.5-10 mass parts with respect to 100 mass parts of binder resin, and, as for the addition amount of the said wax, it is more preferable that it is 1-8 mass parts. Two or more kinds of waxes may be used in combination.

  A colorant can also be used for the magnetic toner in the present invention.

  As the colorant used in the present invention, any appropriate pigment or dye may be mentioned. Examples of the pigment include carbon black, aniline black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, bengara, phthalocyanine blue, and indanthrene blue. These are used in an amount necessary and sufficient to maintain the optical density of the fixed image. The amount added is 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the binder resin. good. For the same purpose, a dye is further used. For example, there are azo dyes, anthraquinone dyes, xanthene dyes, and methine dyes, and 0.1 to 20 parts by mass, preferably 0.3 to 10 parts by mass is added to 100 parts by mass of the binder resin.

  The magnetic toner in the present invention is preferably added with fine silica powder in order to improve charging stability, developability, fluidity and durability.

Silica fine powder used in the present invention has a specific surface area by the BET method by nitrogen adsorption 30 m ² / g or more, particularly in the range of 50 to 400 m ² / g give good results. The silica fine powder is used in an amount of 0.01 to 8 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the toner particles.

  In addition, the silica fine powder used in the present invention has a silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, a silane coupling agent, and a functional group as necessary for the purpose of hydrophobization and chargeability control. It is also preferable that it is treated with a treating agent such as a silane compound, other organosilicon compounds, or a combination of various treating agents.

  Other external additives may be added to the magnetic toner in the present invention as necessary.

  Examples thereof include resin fine particles and inorganic fine particles that function as a charging aid, a conductivity imparting agent, a fluidity imparting agent, an anti-caking agent, a release agent at the time of fixing with a heat roller, a lubricant, an abrasive, and the like.

  For example, examples of the lubricant include polyethylene fluoride powder, zinc stearate powder, polyvinylidene fluoride powder, and the like. Among these, polyvinylidene fluoride powder is preferable. Examples of the abrasive include cerium oxide powder, silicon carbide powder, and strontium titanate powder. Of these, strontium titanate powder is preferable. Examples of the fluidity-imparting agent include titanium oxide powder and aluminum oxide powder, and among them, a hydrophobic one is preferable. Examples of the conductivity imparting agent include carbon black powder, zinc oxide powder, antimony oxide powder, and tin oxide powder. Furthermore, a small amount of white and black fine particles having opposite polarity can be used as a developing improver.

  In order to produce the magnetic toner in the present invention, a binder resin, a magnetic material, other additives and the like are sufficiently mixed by a mixer such as a Henschel mixer and a ball mill, and then a kneading machine such as a heating roll, a kneader, and an extruder. After kneading with cooling, solidify by cooling, pulverize and classify using a pulverizer and classifier, and if necessary, mix desired additives such as silica fine powder with a mixer such as a Henschel mixer. Thus, the magnetic toner in the present invention can be obtained.

  For example, as a mixer, Henschel mixer (made by Mitsui Mining); Super mixer (made by Kawata); Ribocorn (made by Okawara Seisakusho); Nauter mixer, turbulizer, cyclomix (made by Hosokawa Micron); Spiral pin mixer 1 (manufactured by Taiheiyo Kiko Co., Ltd.);

  As a kneading machine, KRC kneader (manufactured by Kurimoto Iron Works); Bus Co kneader (manufactured by Buss); TEM type extruder (manufactured by Toshiba Machine); TEX twin-screw kneader (manufactured by Nippon Steel) PCM kneader (manufactured by Ikegai Iron Works); three roll mill, mixing roll mill, kneader (manufactured by Inoue Seisakusho); kneedex (manufactured by Mitsui Mining Co., Ltd.); MS pressure kneader, nider ruder (manufactured by Moriyama Seisakusho); Banbury mixer (manufactured by Kobe Steel) can be mentioned. The kneader may be a heat and pressure kneader or a kneader that promotes natural heat generation of the magnetic toner.

  As a pulverizer, a counter jet mill, a micron jet, an inomizer (manufactured by Hosokawa Micron); an IDS type mill, a PJM jet pulverizer (manufactured by Nippon Pneumatic Industry Co., Ltd.); a cross jet mill (manufactured by Kurimoto Iron Works Co., Ltd.); SK Jet Oh Mill (manufactured by Seishin Enterprise Co., Ltd.); Kryptron (manufactured by Kawasaki Heavy Industries, Ltd.); Turbo Mill (manufactured by Turboe Industry Co., Ltd.) and the like.

  Classifiers include: Classy, Micron Classifier, Spedic Classifier (manufactured by Seishin Enterprise); Turbo Classifier (manufactured by Nissin Engineering); Micron Separator, Turboplex (ATP), TSP Separator (manufactured by Hosokawa Micron) ; Elbow Jet (manufactured by Nippon Steel & Mining Co., Ltd.), Dispersion Separator (manufactured by Nippon Pneumatic Engineering Co., Ltd.); YM Micro Cut (manufactured by Yaskawa Shoji Co., Ltd.), etc. Ultrasonic (manufactured by Sakae Sangyo Co., Ltd.); Resonator Sheave, Gyroshifter (Tokusu Kosakusha Co., Ltd.); Vibrasonic System (manufactured by Dalton Co., Ltd.); Soniclean (manufactured by Shinto Kogyo Co., Ltd.); ); Micro shifter (Ogino Sangyo Co., Ltd.) ); Circular vibration sieve, and the like.

Hereinafter, methods for measuring physical properties used in the present invention will be described.
<Measurement of magnetic properties of magnetic toner and magnetic material>
Using a “vibrating sample magnetometer VSM-3S-15” (manufactured by Toei Kogyo Co., Ltd.) under an external magnetic field of 7.96 × 10 ² kA / m (10 kOe), the magnetic toner and the magnetic material A hysteresis curve is measured, and values converted into saturation magnetization σs, residual magnetization σr, and coercive force Hc are obtained as magnetic characteristics.
<Measurement of weight average particle diameter of toner particles and magnetic toner>
The weight average particle diameter of the toner particles and magnetic toner in the present invention is measured by various methods such as Coulter Counter TA-II type or Coulter Multisizer (manufactured by Coulter Co.). Using Coulter Multisizer (manufactured by Coulter), an interface (manufactured by Nikka) and a PC9801 personal computer (manufactured by NEC) that output number distribution and volume distribution are connected, and the electrolyte is 1% NaCl using first grade sodium chloride. Adjust the aqueous solution. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. The measurement procedure is as follows. 100 to 150 ml of the electrolytic aqueous solution is added, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the volume distribution is calculated by measuring the volume of toner of 2 μm or more using the aperture with the Coulter Multisizer. Then, the volume-based weight average particle diameter (D4) obtained from the volume distribution of the place according to the present invention is obtained.
<Measurement of molecular weight distribution by GPC>
The molecular weight distribution by GPC using magnetic toner and binder resin THF as a solvent is measured under the following conditions.

The column is stabilized in a heat chamber at 40 ° C., and THF as a solvent is allowed to flow through the column at this temperature at a flow rate of 1 ml per minute, and about 100 μl of the THF sample solution is injected and measured. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the count value. As a standard polystyrene sample for preparing a calibration curve, for example, a product having a molecular weight of about 10 ² to 10 ⁷ manufactured by Tosoh Corporation or Showa Denko is used, and at least about 10 standard polystyrene samples are suitably used. . An RI (refractive index) detector is used as the detector. As the column, it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, combinations of shodex GPC KF-801, 802, 803, 804, 805, 806, 807, 800P manufactured by Showa Denko KK, Tosoh Corporation Made in _{TSKgel G1000H (H XL), G2000H} (H XL), G3000H (H XL), G4000H (H XL), G5000H (H X L), G6000H (H XL), G7000H (H XL), the combination of TSKgurd column Can be mentioned.

  The sample is prepared as follows.

Put the sample in THF, leave it for several hours, then shake well and mix well with THF (until the sample is no longer united), and let stand for more than 12 hours. At that time, the standing time in THF is set to 24 hours or longer. Thereafter, a sample processed filter (pore size 0.2 to 0.5 μm, for example, Mysori Disc H-25-2 (manufactured by Tosoh Corporation) can be used) is used as a GPC sample. The sample concentration is adjusted so that the resin component is 0.5 to 5 mg / ml.
<Measurement of THF-insoluble matter>
In the present invention, the THF-insoluble matter in the toner is measured as follows.

  1.0-2.0 g of toner is weighed (W1 g), cylindrical filter paper (for example, No. 86R manufactured by Toyo Roshi Kaisha Co., Ltd.) is put into a Soxhlet extractor, extracted with 200 ml of THF as a solvent, and extracted for 10 hours. After evaporating the soluble component solution obtained, it is vacuum dried at 100 ° C. for several hours, and the amount of the THF soluble resin component is weighed (W2 g). The weight of the incineration residual ash in the toner is determined (W3 g).

The incineration residual ash content is obtained by the following procedure. About 2.0 g of a sample is placed in a 30 ml magnetic crucible that has been precisely weighed in advance, and weighed accurately, and the mass (Wa) g of the sample is precisely weighed. The crucible is put in an electric furnace, heated at about 900 ° C. for about 3 hours, allowed to cool in the electric furnace, allowed to cool in a desiccator for 1 hour or more at room temperature, and the mass of the crucible is precisely weighed. Incineration residual ash content (Wb) g is calculated | required from here, and incineration residual ash content rate is calculated | required by following formula (4).
(4) (Wb / Wa) × 100 = Incineration residual ash content (mass%)
The mass (W3g) of the incineration residual ash content in the sample is determined from this content rate.

The THF-insoluble content can be obtained from the following formula (5).
(5) THF-insoluble matter = (W1- (W3 + W2)) / (W1-W3) × 100 (%)
<Measurement of acid value>
In the present invention, the acid value (JIS acid value) of the THF soluble part of the toner is determined by the following method. Basic operation conforms to JIS K-0070.
1) The sample should be used after removing the THF-insoluble matter in the binder resin of the magnetic toner in advance, or the soluble matter extracted with the THF solvent by the Soxhlet extractor obtained by the above-mentioned measurement of the THF-insoluble matter as a sample. use. 0.5 to 2.0 g of the pulverized sample is precisely weighed, and the weight of the soluble component is defined as W (g).
2) Put the sample in a 300 ml beaker, and add 150 ml of a toluene / ethanol (4/1) mixture to dissolve.
3) Titrate with 0.1 mol / l KOH ethanol solution using potentiometric titrator. (For example, automatic titration using a potentiometric titrator AT-400 (winworkstation) and ABP-410 electric burette manufactured by Kyoto Electronics Co., Ltd. can be used.) 4) The amount of KOH solution used at this time is Sml, At the same time, a blank is measured, and the amount of KOH solution used is Bml.
5) The acid value is calculated by the following formula (6). f is a factor of KOH.
(6) Acid value (mgKOH / g) = {(SB) × f × 5.61} / W
<Measurement of glass transition temperature of magnetic toner and binder resin>
A method for measuring the glass transition temperature of the magnetic toner and the binder resin in the present invention will be described below.

  The glass transition temperature (Tg) of the magnetic toner and the binder resin is measured according to ASTM D3418-82 using a differential scanning calorimeter (DSC measuring device) and DCS-7 (manufactured by Perkin Elmer).

The sample to be measured is precisely weighed 5 to 20 mg, preferably 10 mg. It is put in an aluminum pan, and an empty aluminum pan is used as a reference, and measurement is performed at room temperature and normal humidity at a temperature rising rate of 10 ° C./min within a measurement range of 30 to 200 ° C. In this temperature rising process, a specific heat change is obtained in the temperature range of 40 to 100 ° C. At this time, the intersection of the intermediate point line of the baseline before and after the change in specific heat and the differential heat curve is defined as the glass transition temperature Tg of the magnetic toner and the binder resin in the present invention.
<Measurement of epoxy value>
Basic operation conforms to JIS K-7236.
1) The sample should be used after removing the THF-insoluble content of the binder resin in the magnetic toner in advance, or the soluble component extracted with the THF solvent by the Soxhlet extractor obtained by the above-mentioned measurement of the THF-insoluble content as a sample. use. 0.5-2.0 g of the sample is precisely weighed, and its weight is defined as Wg.
2) Place the sample in a 300 ml beaker and dissolve in 10 ml chloroform and 20 ml acetic acid.

  To this solution is added 10 ml of tetraethylammonium bromide acetic acid solution. Titrate with a potentiometric titrator using 0.1 mol / l perchloric acid acetic acid solution. (For example, automatic titration can be used by using a potentiometric titrator AT-400 (win workstation) manufactured by Kyoto Electronics Co., Ltd. and an ABP-410 electric burette). The amount of perchloric acid acetic acid solution used at this time is Sml, and a blank is measured at the same time, and the amount of perchloric acid acetic acid solution used at this time is Bml.

The epoxy value is calculated by the following formula (7). f is a factor of the perchloric acid acetic acid solution.
(7) Epoxy value (eq / kg) = 0.1 × f × (SB) / W
<Measurement of specific surface area of silica fine powder>
In accordance with the BET method, the specific surface area is obtained by adsorbing nitrogen gas on the sample surface using a specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics) and calculating the specific surface area using the BET multipoint method.
<Volume average particle diameter of metal oxide / carbide>
In the present invention, the volume average particle diameter of the metal oxide or carbide represents a 50% volume particle diameter value measured by laser diffraction particle size measurement (microtrack method).
<Shape and average particle size of magnetic material>
Using a sample processed with a collodion film copper mesh with an electron microscope (Hitachi, Ltd. H-700H), the sample is photographed at a magnification of 10,000 at an applied voltage of 100 KV, and the final magnification is 30000. Thus, the shape is observed, the maximum length (μm) of each particle is measured, 100 particles are selected at random, and the average is taken as the average particle size.
<Method for Measuring SD of Circularity and Circularity Distribution of Toner Particles and Magnetic Toner>
In the present invention, measurement is performed using a flow type particle image measuring device “FPIA-1000 type” (manufactured by Sysmex Corporation), and calculation is performed using the following formula.

  Here, the “particle projected area” is the area of the binarized toner particle or magnetic toner image, and the “peripheral length of the particle projected image” is obtained by connecting the edge points of the toner particle image or magnetic toner image. It is defined as the length of the contour line. The circularity in the present invention is an index indicating the degree of unevenness of toner particles or magnetic toner, and is 1.000 when the toner particles or magnetic toner is a perfect sphere. Is a small value.

  In addition, the average circularity C and the circularity standard deviation SDc, which mean the average value of the circularity frequency distribution, can be obtained from the following equation when the circularity (center value) at the division point i of the particle size distribution is ci and the frequency is fci. Calculated.

  As a specific measuring method, 10 ml of ion-exchanged water from which impure solids have been removed in advance is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, followed by further measurement. Add 0.02 g of sample and disperse uniformly. As a means for dispersion, an ultrasonic disperser “Tetora 150 type” (manufactured by Nikka Ki Bios) is used, and a dispersion for measurement is made using a dispersion treatment for 2 minutes. In that case, it cools suitably so that the temperature of this dispersion may not be 40 degreeC or more.

  To measure the shape of toner particles and magnetic toner, the flow particle image measuring device is used, and the dispersion concentration is readjusted so that the toner particle concentration at the time of measurement is 3000 to 10,000 particles / μl. 1000 or more are measured. After the measurement, using this data, data of 3 μm or less is cut to obtain the circularity and the circularity standard deviation.

  According to the image forming method of the present invention, in a development process in which development is performed using a magnetic toner formed in a thin layer on a plurality of toner carriers, magnetic properties are provided along at least a part of the circumferential surface of both ends in the axial direction of the toner carrier. A toner seal member formed of a substance and the specific magnetic toner described above are used.

  Next, an example of a schematic configuration of an image forming apparatus used in the image forming method of the present invention will be described. However, the scope of the present invention is not limited thereto.

  FIG. 1 is a schematic diagram showing a configuration of an image forming unit of a copying machine using an electrophotographic process. In FIG. 1, a photosensitive drum 1 as a latent image holding member is rotationally driven in the direction of an arrow a, and its surface is charged to an arbitrary potential by a primary charger 2 and then an electrostatic latent image is formed by exposure L. . Thereafter, development is performed by a developing device 3 having a plurality of developing sleeves as toner carriers (two developing sleeves in FIG. 1), and the transfer material P is transferred onto the photosensitive drum 1 by a transfer charger 5. The formed toner image is transferred and heated and pressed in the fixing device 8 to fix the unfixed image on the transfer material P. Incidentally, the transfer residual toner remaining on the surface of the photosensitive drum after the toner transfer is removed by the cleaning device 7, whereby the photosensitive drum 1 is repeatedly used for image formation.

  In the present invention, the latent image holding member is not limited to the photosensitive drum, and may be a belt-like or seal-like photosensitive member.

  Similarly, in the present invention, the transfer method is not limited, and a belt transfer method or an intermediate transfer method may be used.

  Next, a magnetic one-component developing method using a plurality of developing sleeves will be described with reference to FIG. In addition, although this invention does not limit a latent image holding body, when using an a-Si type photosensitive drum, it is used suitably. In this case, both the normal development method and the reversal development method are preferably applicable according to the polarities of the photosensitive drum and the magnetic toner.

  A developing device 3 shown in FIG. 2 includes a developing container (developing device main body) 11 that stores magnetic toner, and a photosensitive drum 1 provided in an opening formed at a position facing the photosensitive drum 1 of the developing container 11. An upstream developing sleeve 12 located upstream with respect to the rotational direction, a downstream developing sleeve 13 located downstream, and a toner hopper 19 are disposed below the toner hopper 19, and magnetic toner t is fed upstream and downstream to the developing sleeve 12. , 13 and so on, which are carried to the vicinity of 13.

Here, the upstream and downstream developing sleeves 12 and 13, which are the first and second toner carriers, are disposed in close proximity to each other and are developed on both side walls of the developing container 11 as shown in FIG. The shafts 12a and 13a of the sleeves 12 and 13 are supported via a bearing 50 shown in FIG. 5, and are thereby rotatable.

  Further, the upstream and downstream developing sleeves 12 and 13 carry the carried magnetic toner out of the developing container 11 so that the magnetic toner is conveyed to the photosensitive drum 1 rotating clockwise. When the magnetic toner is carried out from above the upstream and downstream developing sleeves 12 and 13, the magnetic toner is rotated in the counterclockwise direction. In this case, the rotation direction of each developing sleeve may be the same direction or the reverse direction depending on the situation. The developing sleeves 12 and 13 may have their peripheral speeds shifted in the range of 100 to 200% with respect to the peripheral speed of the photosensitive drum 1 in some cases.

  Specifically, the peripheral speed of the developing sleeve is preferably 400 to 1000 mm / sec, more preferably 500 to 800 mm / sec.

  The amount of magnetic toner on the developing sleeve 12 is adjusted by regulating the layer thickness by a magnetic blade 16 which is a layer thickness regulating member provided in the opening of the developing container 11 in the vicinity of the developing sleeve 12. Yes.

  Further, the developing sleeves 12 and 13 are arranged with a specific interval, and the toner layer thickness on the downstream developing sleeve can be adjusted by the interval.

  The distance between each developing sleeve and the photosensitive drum is set with a specific distance, and this distance may be the same distance in the vertical direction or may be different depending on the situation.

  Further, in the present invention, the diameters of the plurality of developing sleeves may be the same or different depending on the case.

  Each of the developing sleeves 12 and 13 is preferably subjected to magnetic one-component non-contact development by applying a DC voltage and an alternating voltage. At this time, the DC voltage and the alternating voltage of each developing sleeve may be the same or different.

  Next, an example of the toner seal member provided in the developing device will be described with reference to FIGS. However, these do not limit the scope of the present invention.

  The first developing sleeve 20 shown in FIG. 4 includes a substantially cylindrical first magnet roll 20a having several magnetic poles therein as a magnetic field generating means. A substantially cylindrical second magnet roll 30a having several magnetic poles therein is provided. The number of magnetic poles is adjusted depending on the situation, and may be the same or different between the first and second developing sleeves. It is preferable in terms of development efficiency and image formation that the first developing sleeve has more magnetic poles than the second developing sleeve. In the developing device shown in FIG. 4, the first developing sleeve is represented as 5 poles, and the second developing sleeve is represented as 4 poles. The magnetic seal members 2d (2d1 and 2d2), which are toner seal members for two developing sleeves that generate a magnetic field, are close to each other along the outer circumferences of the developing sleeves 20 and 30. It is provided in the vicinity of both ends in the axial direction.

As shown in FIGS. 4 and 6, the magnetic seal member 2d is provided on the developing container side of each of the first and second developing sleeves 20 and 30 (the developing container is not shown in FIGS. 4 and 6). It has a shape that opposes the substantially half circumference of the right side). The gap between the surfaces of the developing sleeves 20 and 30 and the magnetic seal member 2d may be the same distance over the entire circumference of the developing sleeves 20 and 30, or within each developing sleeve or within each developing sleeve. The distance may be changed between the upstream side and the downstream side. The gap between the magnetic seal member and the developing sleeve is preferably 200 to 800 μm.

  The magnetic seal member 2d is a narrow member provided only at both axial ends of the developing sleeves 20 and 30 as shown in FIG. By disposing the magnetic seal member 2d at both ends of the developing sleeves 20 and 30, as shown in FIG. 6, the magnetic seal member 2d is magnetized by the magnetic force of the magnets 20a and 30a in the developing sleeves 20 and 30, and the magnet 20a. , 30a, and dense magnetic brushes 20B, 30B made of magnetic toner are formed in the gaps 20G, 30G between the magnetic seal member 2d and the developing sleeves 20, 30.

  The magnetic brushes 20B and 30B are toner seal members that block magnetic toner that enters the bearing 50 in FIG. 5 through the gap between the side wall of the developing container 21 and the developing sleeves 20 and 30 along the developing sleeves 20 and 30. As a function.

  As shown in FIG. 5, the appropriate positions of the magnetic seal member with respect to the magnets 20a and 30a are both end portions in the axial direction of the developing sleeves 20 and 30, and the outer end position of the magnetic seal member 2d and the magnet 20a, Most preferably, the positions of both ends of 30a are matched.

  If the magnets 20a and 30a protrude outward from the end of the magnetic seal member, the magnetic toner is also projected outside the both ends, so that the magnetic toner is carried from the outside by the magnetic force, causing toner leakage. easy. Further, if the magnets 20a and 30a are excessively inserted into the magnetic seal member 2d, it is not preferable because the toner layer thickness is increased at the same time as the end leakage and the dropping of the toner easily occurs.

  The developing sleeve has a magnet having a plurality of magnetic poles on the inner peripheral surface and having S poles and N poles arranged alternately. The number of magnetic poles of the magnet is set by the length of the magnetic seal member, that is, the circumferential length of the developing sleeve and the curvature of the developing sleeve, and the magnetic pole pattern of the magnets 20a and 30a installed in the developing sleeves 20 and 30.

  In the present invention, the magnetic seal member as the toner seal member is formed of a magnetic substance, and iron, lithium, calcium, magnesium, nickel, copper, zinc, cobalt, manganese, chromium, rare earth metal particles, and It is preferable to use a resin magnet obtained by mixing and dispersing magnet powder such as alloy particles, oxide particles, and ferrite using a resin binder.

  Among them, fine powders such as Fe—Ni alloy, Fe—Si alloy, Nd—Fe—B alloy, and Sm—Fe—B alloy are preferable as magnet powder because they are relatively inexpensive and provide good magnetic properties. Among these, those using a rare earth alloy fine powder such as an Nd—Fe—B alloy are preferred because they have low adhesion to the magnetic toner and are excellent in the effect of preventing fusion of the magnetic toner to the end of the developing sleeve.

  A magnetic seal member containing magnet powder in a resin binder is excellent in moldability, and it becomes possible to manufacture a member having a complicated shape, and a small and lightweight seal member can be obtained.

  As the resin binder constituting the resin magnet, polyamide resin such as nylon, polystyrene resin, polyethylene terephthalate resin, polyphenylene sulfide resin and the like can be used. Among them, polyamide resin such as nylon 6 and nylon 12, polyphenylene Sulfide resin and the like are preferable.

Hereinafter, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited thereto.
<Manufacture of binder resin for toner>
(Production Example A-1 of High Molecular Weight Component)
-Styrene 78.4 parts by mass-N-butyl acrylate 19.6 parts by mass-Methacrylic acid 2.0 parts by mass-2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane
0.8 parts by mass The above components were sufficiently replaced with nitrogen in a four-necked flask containing 200 parts by mass of xylene, and the temperature inside the container was raised to 120 ° C. while stirring, and then dropped over 4 hours. did. Further, polymerization is completed under reflux of xylene, and a resin obtained by distilling off the solvent under reduced pressure is designated as A-1.
(Production Example A-2 of High Molecular Weight Component)
-Styrene 79.7 parts by mass-N-butyl acrylate 19.9 parts by mass-Acrylic acid 0.5 parts by mass-2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane
0.8 part by mass Resin A-2 was obtained in the same manner as in Production Example A-1 using the above components.
(Production Example A-3 of High Molecular Weight Component)
-Styrene 74.4 parts-N-butyl acrylate 18.6 parts-Acrylic acid 6.0 parts-2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane
0.8 part by mass Resin A-3 was obtained in the same manner as in Production Example A-1 using the above components.
(Production Example A-4 of High Molecular Weight Component)
-Styrene 80.0 parts by mass-N-butyl acrylate 20.0 parts by mass-2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane
1.0 mass part Resin A-4 was obtained similarly to manufacture example A-1 using the said component.
(Production Example B-1 of vinyl resin having carboxyl group)
-High molecular weight component resin A-1 30 parts by mass-Styrene 55.4 parts by mass-N-butyl acrylate 13.9 parts by mass-Methacrylic acid 0.7 parts by mass-Di-t-butyl peroxide 1.4 parts by mass The above material was dropped into 200 parts by mass of xylene over 4 hours. Furthermore, polymerization is completed under reflux of xylene, and a resin obtained by distilling off the solvent under reduced pressure is designated as B-1.
(Production Example B-2 of Vinyl Resin Having Carboxyl Group)
-High molecular weight component resin A-2 30.0 parts by mass-Styrene 56.0 parts by mass-N-butyl acrylate 14.0 parts by mass-Di-t-butyl peroxide 1.4 parts by mass Using the above materials, Resin B-2 was obtained in the same manner as in Production Example B-1.
(Production Example B-3 of Vinyl Resin Having Carboxyl Group)
-High molecular weight component resin A-3 30.0 parts by mass-Styrene 52.8 parts by mass-N-butyl acrylate 13.2 parts by mass-3.0 parts by mass acrylic acid-Di-t-butyl peroxide 1.4 Mass parts Resin B-3 was obtained in the same manner as in Production Example B-1 using the above materials.
(Production Example B-4 of vinyl resin having no carboxyl group)
-High molecular weight component resin A-4 50.0 parts by mass-Styrene 40.0 parts by mass-N-butyl acrylate 10.0 parts by mass-Di-t-butyl peroxide 1.0 part by mass Using the above materials, Resin B-4 was obtained in the same manner as in Production Example B-1.
(Production Example C-1 of Vinyl Resin Having Epoxy Group)
-Styrene 79.2 parts by mass-N-butyl acrylate 19.8 parts by mass-Glycidyl methacrylate 1.0 part by mass-Di-t-butyl peroxide 5.0 parts by mass The inside of the four-necked flask was sufficiently replaced with nitrogen, heated to 120 ° C., and then dropped over 4 hours. Furthermore, polymerization is completed under reflux of xylene, and a resin obtained by distilling off the solvent under reduced pressure is designated as C-1.
(Production Example C-2 of Vinyl Resin Having Epoxy Group)
Styrene 72.0 parts by mass N-butyl acrylate 18.0 parts by mass Glycidyl methacrylate 10.0 parts by mass Di-t-butyl peroxide 5.0 parts by mass Using the above materials, Production Example C- Resin C-2 was obtained in the same manner as in Example 1.
<Method for producing toner particles>
(Production Example 1 of Toner Particles)
Biaxial kneading after 90 parts by mass of the vinyl resin having a carboxyl group obtained in Production Example B-1 and 10 parts by mass of the vinyl resin having an epoxy group obtained in Production Example C-1 were mixed using a Henschel mixer. The resultant was kneaded at 180 ° C. with an extruder, cooled and pulverized to obtain a binder resin 1.
・ Binder resin 1 100 parts by mass ・ Magnetite A
(Octahedron shape, average particle size = 0.20 μm, coercive force Hc = 9.9 kA / m, residual magnetization σr = 10.2 Am ² / kg, saturation magnetization σs = 82.9 Am ² / kg) 90 parts by mass / Fischer Tropsch wax (melting point 100 ° C.) 2 parts by mass, paraffin wax (melting point 75 ° C.) 4 parts by mass, triphenylmethane lake pigment of the following structural formula (I) 2 parts by mass

Structural formula (I)
The above materials were sufficiently premixed with a Henschel mixer and then melt kneaded with a biaxial kneading extruder set at 130 ° C. The obtained kneaded product is cooled, roughly pulverized with a cutter mill, and then finely pulverized with a fine pulverizer using a jet stream under an arbitrary condition. Classification was performed to obtain toner particles 1 having a weight average particle diameter of 7.5 μm. Of the obtained toner particles 1 having a particle size of 3 μm or more, the number of particles having a circularity a of 0.90 or more was 92.5% by number.
(Toner particle production example 2)
90 parts by mass of the vinyl resin having a carboxyl group obtained in Production Example B-2 and 10 parts by mass of the vinyl resin having an epoxy group obtained in Production Example C-1 are mixed with a Hensell mixer, and biaxial extrusion is performed. A binder resin 2 was obtained by kneading at 180 ° C. with a machine and cooling and pulverizing.

Toner particles 2 were obtained in the same manner as in Toner Particle Production Example 1 except that the binder resin 2 was changed.
(Toner particle production example 3)
95 parts by mass of the vinyl resin having a carboxyl group obtained in Production Example B-3 and 5 parts by mass of the vinyl resin having an epoxy group obtained in Production Example C-1 are mixed with a Hensell mixer, and biaxial extrusion is performed. The binder resin 3 was obtained by kneading at 200 ° C. with a machine, cooling and pulverizing.

Toner particles 3 were obtained in the same manner as in Toner Particle Production Example 1 except that the binder resin 3 was changed.
(Toner particle production example 4)
90 parts by mass of the vinyl resin containing no carboxyl group obtained in Production Example B-4 and 10 parts by mass of the vinyl resin having an epoxy group obtained in Production Example C-1 were mixed in a Hensell mixer, and biaxial Using an extruder, the mixture was kneaded at 180 ° C., cooled and pulverized to obtain a binder resin 4.

Toner particles 4 were obtained in the same manner as in Toner Particle Production Example 1 except that the binder resin 4 was changed.
(Toner particle production example 5)
90 parts by mass of the vinyl resin having a carboxyl group obtained in Production Example B-3 and 10 parts by mass of the vinyl resin having an epoxy group obtained in Production Example C-2 were mixed with a Hensell mixer, and biaxial extrusion was performed. The binder resin 5 was obtained by kneading at 200 ° C. with a machine, cooling and pulverizing.

Toner particles 5 were obtained in the same manner as in Toner Particle Production Example 1 except that the binder resin 5 was changed.
(Toner Particle Production Example 6)
Binder resin 4 100 parts by mass Magnetite B 90 parts by mass (octahedral shape, average particle size = 0.18 μm, coercive force Hc = 14.9 kA / m, residual magnetization σr = 19.0 Am ² / kg, saturation magnetization σs = 85.4 Am ² / kg)
Fischer-Tropsch wax (melting point 100 ° C.) 4 parts by mass Triphenylmethane lake pigment of the above structural formula (I) 2 parts by mass In the same manner as in toner particle production example 1, the weight average particle diameter D4 = Toner particles 6 having a circularity a of 0.90 or more and 92.4% by number of particles of 7.4 μm and 3 μm or more were obtained.
(Toner particle production example 7)
Binder resin 4 100 parts by mass Magnetite C 90 parts by mass (polygonal shape (binuclear shape), average particle size = 0.19 μm, coercive force Hc = 7.3 kA / m, residual magnetization σr = 9.2 Am ² / kg , Saturation magnetization σs = 86.2 Am ² / kg
Fischer-Tropsch wax (melting point 100 ° C.) 4 parts by mass Triphenylmethane lake pigment of the above structural formula (I) 2 parts by weight The same as the toner particle production example 1 except that the above materials were used. D4 = 7.3 μm Toner particles 7 having a circularity a of 0.90 or more and 91.7% by number of particles of 3 μm or more are obtained.
(Toner Particle Production Example 8)
Binder resin 4 100 parts by mass Magnetite D 90 parts by mass (spherical, average particle size = 0.22 μm, coercive force Hc = 5.4 kA / m, residual magnetization σr = 6.1 Am ² / kg, saturation magnetization σs = 84.0 Am ² / kg)
Fischer-Tropsch wax (melting point 100 ° C.) 4 parts by mass Triphenylmethane lake pigment of the above structural formula (I) 2 parts by weight The same as the toner particle production example 1 except that the above materials were used. Toner particles 8 having D2.8 = 7.5 μm, particles having a circularity a of 0.90 or more among particles having a particle diameter of 3 μm or more were 92.8% by number were obtained.
(Production Examples 9 to 11 of toner particles)
In toner particle production example 8, instead of magnetite D (90 parts by mass), magnetite E (spherical, average particle size = 0.24 μm, coercive force Hc = 3.6 kA / m, residual magnetization σr = 4.3 Am ² / (kg, saturation magnetization σs = 80.3 Am ² / kg) in the same manner except that 90 parts by mass is added, the production conditions are adjusted, and the circularity a in the weight average particle diameter D4 = 7.1 μm, 3 μm or more of toner particles 90.5 number of toner particles 9 having a particle size of 0.90 or more and 91.5 number% of particles having a weight average particle diameter D4 = 10.2 μm and 3 μm or more, and a circularity a of 0.90 or more. % Toner particles 10 and weight average particle diameter D4 = 10.7 μm, 3 μm or more of toner particles 11 having a circularity a of 0.90 or more and 83.8% by number.
(Toner Particle Production Example 12)
In Toner Particle Production Example 6, except that the amount of magnetite B added is changed from 90 parts by mass to 120 parts by mass, the production conditions are adjusted, and the weight average particle diameter D4 = 12.3 μm is 3 μm or more. Toner particles 12 having 80.5% by number of particles having a circularity a of 0.90 or more were obtained.
(Toner Particle Production Example 13)
In Toner Particle Production Example 8, particles having a weight average particle diameter D4 of 12.5 μm and 3 μm or more were prepared in the same manner except that the addition amount of magnetite D was changed from 90 parts by mass to 70 parts by mass. Thus, toner particles 13 having 81.3% by number of particles having a circularity a of 0.90 or more were obtained.
<Example of magnetic toner production>
(Magnetic toner production example 1)
To 100 parts by mass of toner particles 1 obtained in Production Example 1 of toner particles, 3.0 parts by mass of strontium titanate powder having a volume average particle size of 1.6 μm and silica fine powder (BET produced by a dry method) 0.8 parts by mass of hydrophobic silica fine powder treated with 20 parts by mass of amino-modified silicone oil (amine equivalent 830, viscosity 70 mm ² / s at 25 ° C.) per 100 parts by mass of specific surface area 200 m ² / g) Were mixed under arbitrary conditions, and sieved with a mesh having an opening of 150 μm to obtain magnetic toner 1. Table 1 summarizes the physical properties of the magnetic toner.
(Production Examples 2 to 14 of magnetic toner)
Magnetic toner 2 to magnetic toner 14 in the same manner as in magnetic toner production example 1 except that the toner particles and nonmagnetic metal oxide and / or metal carbide (including or not included) are changed as shown in Table 1. Got. The physical properties of the obtained magnetic toner are shown in Table 1.
(Comparative Production Examples 1 and 2 of magnetic toner)
Comparative magnetic toner 1 and comparative magnetic toner 2 were obtained in the same manner as in magnetic toner production example 1 except that toner particles 12 and 13 obtained in production examples 12 and 13 were used as toner particles 1. Table 1 shows the physical properties of the obtained magnetic toner.

[Example 1]
The magnetic toner 1 obtained was subjected to the following evaluation tests.
<Image evaluation test>
Commercially available copying machine iR105 (105 cpm, a-Si photoconductor mounted, manufactured by Canon Inc.)
The developing portion was remodeled into a developing device having two developing sleeves as shown in FIG. 2, and the process speed (peripheral speed of the photosensitive drum) was modified so as to be variable at 400 mm / sec and 600 mm / sec.

  The two developing sleeves are made by blasting an aluminum tube having an outer diameter of 20 mm with FGB # 600 and then applying Ni-B and Cr plating on the surface. The surface roughness Ra of the developing sleeve surface is 0.6 μm. It was. Further, as shown in FIG. 4, a magnet roll 20a having five poles N1, N2, N3, S1, and S2 is provided in the first developing sleeve 20 on the upstream side as a magnetic field generating means inside the developing sleeve. The second developing sleeve 30 is provided with a magnet roll 30a having four poles N1, N2, S1, and S2. The distance S-B gap between the first developing sleeve 20 and the magnetic blade 2g was set to 230 μm, and the distance SS gap between the first developing sleeve 20 and the second developing sleeve 30 was set to 500 μm. Then, the magnetic seal member is placed close to the both ends of the two developing sleeves in the axial direction along the outer periphery of the developing sleeve so that the distance between the developing sleeve and the magnetic sealing member is 400 μm along the entire circumference. .

  As the magnetic seal member, 100 parts by mass of nylon 12 (Nd—Fe—B alloy fine powder was blended so as to be 90 parts by mass, sufficiently kneaded and injection molded was used.

  The developing device is supported by the developing rail member and is pressed toward the photosensitive drum by a pressure member provided between the developing device and the image forming apparatus main body. And it installed so that the distance SD gap of a photosensitive drum and a developing sleeve might be set to 250 micrometers by the contact roller attached to the rotating shaft of both sides of a developing sleeve.

  The two developing sleeves are rotated counterclockwise at the same speed, at a speed of 480 mm / sec and 720 mm / sec, which are 120% peripheral speed with respect to the rotational speed of the photosensitive member, and a DC voltage of +300 V and Vpp 1000 V, An alternating voltage having a short waveform with a frequency of 2.7 kHz was applied as a developing bias.

  Using this modified machine, 100,000 sheets were copied in a low temperature and low humidity environment (15 ° C./10% RH) and in a high temperature and high humidity environment (32.5 ° C./90% RH), respectively. In order to clearly evaluate the influence on the toner leakage at the end of the developing sleeve, the printed image has a solid black belt with a width of 0.5 mm at both ends of the image, and the central portion has an image ratio of 6% which is a character image. Images were used.

Evaluation of image density, fogging, dot reproducibility, toner leakage from the sleeve end, fusion of the sleeve end, etc. was performed as follows.
(1) Image Density With a “Macbeth reflection densitometer” (manufactured by Macbeth), an SPI filter was used to measure the reflection density of a 5 mm diameter round image.
(2) Fog Using a reflection densitometer (reflectometer, model TC-6DS, manufactured by Tokyo Denshoku), the reflection density (Dr) of the transfer paper before image formation and a solid white image after copying The worst value of the reflection density was measured as (Ds), and the difference (Ds−Dr) was evaluated as the fog value.
(3) Dot reproducibility An image of a checkered electrostatic latent image composed of 1 dot, 2 dots, 3 dots and 4 dots formed on a photosensitive drum with a laser was used as a measurement sample. This sample is observed with a magnifying glass, and the dot reproducibility is determined by the number of dots of an image that can clearly check a checkered pattern. Smaller numbers indicate better dot reproducibility.
(4) Toner leakage at the end of the developing sleeve A copy test of 100,000 sheets in a low-temperature and low-humidity environment and a high-temperature and high-humidity environment is performed, and it is confirmed that there is no toner leakage from the end of the developing sleeve every 5,000 sheets. The evaluation was made based on the number of generated sheets. The slower the number of generated sheets, the better the toner sealability.
(5) Fusion sleeve edge fusion At 100,000 low temperature low humidity environment, high temperature high humidity environment, copy test of 100,000 sheets, and visually check the development sleeve edge for every 5,000 sheets The evaluation was made based on the number of generated sheets. The slower the number of generated sheets, the better the development sleeve fusion property.

  These image evaluation results are summarized in Tables 2 and 3.

[Examples 2 to 5]
In Example 1, the evaluation was performed in the same manner as in Example 1 except that the magnetic toner used for the evaluation was changed to the magnetic toners 2 to 5 obtained in Production Examples 2 to 5 of the magnetic toner. Table 2 shows the evaluation results.
And 3.
[Example 6]
In Example 4, except for blending the Sm-Fe-B alloy fine powder to 95 parts by mass with respect to 100 parts by mass of nylon 12, and sufficiently changing to a magnetic seal member manufactured by injection molding. Evaluation was performed in the same manner as in Example 4. The evaluation results are shown in Tables 2 and 3.
[Examples 7 to 10]
In Example 6, the evaluation was performed in the same manner as in Example 6 except that the magnetic toner used in the evaluation was changed to the magnetic toners 6 to 9 obtained in Magnetic toner production examples 6 to 9. The evaluation results are shown in Tables 2 and 3.
[Example 11]
In Example 10, it was carried out except that Ni-Fe alloy fine powder was blended to 90 parts by mass with 100 parts by mass of nylon 12 and changed to a magnetic seal member that was sufficiently kneaded and injection molded. Evaluation was carried out in the same manner as in Example 10. The evaluation results are shown in Tables 2 and 3.
[Examples 12 to 16]
In Example 11, the evaluation was performed in the same manner as in Example 11 except that the magnetic toner used for the evaluation was changed to the magnetic toner 10-14 obtained in Production Examples 10-14 of the magnetic toner. The evaluation results are shown in Tables 2 and 3.
[Comparative Example 1 and Comparative Example 2]
In Example 16, the evaluation was performed in the same manner as in Example 1 except that the magnetic toner used for the evaluation was changed to the comparative magnetic toners 1 and 2 obtained in Comparative magnetic toner production examples 1 and 2. The evaluation results are shown in Tables 2 and 3.
[Comparative Example 3]
In Example 16, evaluation was performed in the same manner as in Example 1 except that the magnetic seal member was changed to a contact-type seal member in which the flat felt felt of the flat plate 3 was interposed in the developing sleeve. It was. The evaluation results are shown in Tables 2 and 3.

1 is a schematic cross-sectional view showing a schematic configuration of an embodiment of an image forming apparatus to which an image forming method of the present invention can be applied. FIG. 3 is a schematic cross-sectional view of a developing device used in the image forming method of the present invention. FIG. 3 is a diagram illustrating a configuration of a toner carrier on the upstream side and the downstream side of the developing device used in the image forming method of the present invention. FIG. 3 is a schematic cross-sectional view showing a toner carrier and a toner seal member provided in the developing device shown in FIG. 2. FIG. 3 is a schematic cross-sectional view in the axial direction of a toner carrier provided in the developing device shown in FIG. 2. FIG. 3 is a schematic cross-sectional view showing a toner carrier and a toner seal member provided in the developing device shown in FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 3 Developing apparatus 2d Toner seal member 11 Developing container 12, 20 First developing sleeve (toner carrier)
14, 20a Magnet roll (magnetic field generating means)
12a Rotating shaft (shaft body) of first developing sleeve
13, 30 Second developing sleeve (toner carrier)
15, 30a Magnet roll (magnetic field generating means)
13a Rotating shaft (shaft body) of second developing sleeve
16, 2g Magnetic blade 50 Abutting roller t Magnetic toner

Claims (14)

In an image forming method having at least a developing step of developing a latent electrostatic image formed on a latent image holding member with a magnetic toner formed in a thin layer on a plurality of developing sleeves to form a toner image.
The plurality of developing sleeves used in the developing step are rotating bodies, and a substantially cylindrical magnetic field generating means having a plurality of magnetic poles is fixedly disposed therein,
A toner seal member made of a magnetic material is provided along at least a part of the peripheral surface of both end portions in the axial direction of the plurality of developing sleeves ,
The toner seal member and the developing sleeve are arranged with a certain gap,
Wherein the magnetic field generated between the toner seal member and the developing sleeve within said magnetic field generating means, between the counter surface and the developing sleeve end portions peripheral surface with respect to the developing sleeve of the toner seal member, a magnetic toner A magnetic brush is formed,
The magnetic toner has toner particles containing at least a binder resin and a magnetic material, has a residual magnetization σr of 0.5 to 8.0 (Am ² / kg), and a coercive force Hc (kA / m). The image forming method, wherein the residual magnetization σr (Am ² / kg) satisfies the following formula (1):
(1) 5 ≦ Hc × σr ≦ 85 2. The magnetic toner according to claim 1, wherein in the magnetic toner having a particle diameter of 3 μm or more, the magnetic toner contains 85% by number or more of particles having a circularity a of 0.90 or more obtained by the following formula (2). Image forming method.
(2) Circularity a = L ₀ / L
(In the formula, L ₀ represents the perimeter of a circle having the same area as the projected image of the particle, and L represents the perimeter of the projected image of the particle.) The image forming method according to claim 1, wherein the magnetic toner contains at least one metal oxide and / or metal carbide having a primary particle diameter of 0.05 to 3.0 μm. . The metal oxide and / or metal carbide includes at least one element of Ti, Ce, Al, Zn, Mg, W, Sn, Zr, and Fe, a carbide, and magnesium of oxygen acid of these elements 4. The image forming method according to claim 3, wherein the image forming method is selected from the group consisting of a salt, a calcium salt, a strontium salt, and a barium salt. The metal oxide and / or metal carbide includes strontium titanate, magnesium titanate, calcium titanate, barium titanate, titanium oxide, cerium oxide, aluminum oxide, zinc oxide, tin oxide, iron oxide, ferrite, silica, tungsten 5. The image forming method according to claim 3, wherein the image forming method is selected from the group consisting of carbide and silicon carbide. The image according to any one of claims 3 to 5 , wherein the metal oxide and / or metal carbide is contained in an amount of 0.1 to 8.0 parts by mass with respect to 100 parts by mass of the toner particles. Forming method. The image forming method according to claim 1, wherein the toner seal member is made of a resin binder containing rare earth magnet powder. The image forming method according to claim 1, wherein the toner seal member is made of a resin binder containing Nd—Fe—B alloy fine powder. The image forming method according to claim 1, wherein the magnetic material of the magnetic toner has an octahedral shape. The image forming method according to claim 1, wherein the magnetic toner has a weight average particle diameter of 3.0 to 9.0 μm. The binder resin is selected from the group consisting of a resin mixture comprising a vinyl resin having a carboxyl group and a vinyl resin having an epoxy group, a vinyl resin having a carboxyl group and an epoxy group, and a vinyl resin having a carboxyl group and an epoxy group reacted Containing at least one vinyl resin,
The image forming method according to any one of claims 1 to 10, wherein the magnetic toner has an acid value of 1.0 to 50 mgKOH / g in a THF-soluble component. The image forming method according to claim 1, wherein the magnetic toner contains 0.1 to 60% by mass of a THF-insoluble matter. The image forming method according to claim 1, wherein the developing sleeve has a surface moving speed of 400 to 1000 mm / sec. The image forming method according to claim 1, wherein the developing sleeve has a surface moving speed of 500 to 800 mm / sec.