JP4886405B2 - Image forming method - Google Patents

Description

  The present invention relates to an electrostatic latent image formed on an electrostatic latent image carrier such as an electrophotographic photosensitive member or an electrostatic recording derivative in an electrophotographic, electrostatic recording, or electrostatic printing method. A developer development process for collecting toner remaining on the electrostatic latent image carrier after transfer, at the same time as forming a toner image on the electrostatic latent image carrier using a replenishment developer having The present invention relates to an image forming method including at least a transfer step of transferring a toner image on a latent image carrier to an intermediate transfer member or a transfer material.

  In the electrophotographic method, a uniformly charged image forming body is exposed to light to form a latent image, the latent image is developed into a toner image, and then the toner image is transferred to a transfer material such as recording paper. Is done. When the transfer material carrying the toner image passes through the fixing device, the toner is fixed on the transfer material. In developing a latent image, a one-component or two-component development method is used, and the development method is adopted in accordance with these characteristics. The two-component development method is said to be excellent in high image quality and high durability.

  In the normal two-component development method, the toner in the developing device is consumed, and the shortage is replenished with new toner. However, since the carrier is used continuously, the carrier deteriorates. As a result, since the development characteristics deteriorate, there is a problem that an operation of periodically replacing the developer in the developing device occurs. In response to this technical problem, there has been a proposal for a development method that replenishes replenishment toner and carrier at a fixed ratio, gradually replaces the carrier in the developing unit with a lowered development performance with a new carrier, and eliminates the need for maintenance work. (See, for example, Patent Document 1).

  However, in the developing method described in Patent Document 1, since the replenishment developer containing the carrier is replenished, there is a problem in the mixing property between the developer in the developing device and the replenishment developer. For example, when the mixing property is deteriorated, the charge amount of the developer may be uneven, and the development characteristics may be deteriorated.

  In recent years, with the development of IT, there is a demand for means for outputting further high-definition images such as lowercase letters, photographs or color originals in a wide range of fields from offices to homes. Heavy users are demanding performance (high durability) that does not deteriorate image quality even when a large number of copies or prints are made. In addition, small offices and homes are required to obtain high-quality images, and there is a demand for downsizing of the apparatus from the viewpoint of space saving.

  For example, regarding a reduction in size of the apparatus, a cleanerless system that collects and reuses transfer residual toner has been widely proposed (see, for example, Patent Document 2 and Patent Document 3). Among them, copying machines and printers that employ a so-called simultaneous development cleaning system that collects transfer residual toner in a developing device simultaneously with development have been put into practical use. In particular, since this simultaneous development cleaning system does not use a cleaning unit, dramatic progress can be seen with respect to ecology by making the apparatus compact and eliminating waste toner.

  However, when such a simultaneous development cleaning method is used, high transferability is required, and generally toner having a high average circularity (close to a true sphere) is used. Since such toner has a small contact area with the conveying member and carrier in the developing device, it is more susceptible to stress, such as various inorganic fine particles added to the toner surface for the purpose of obtaining fluidity and charging stability. Embedding occurs, and developer performance tends to deteriorate.

  Therefore, it has been proposed to lower the specific gravity of the carrier to prevent the external additive from being embedded in the toner and to extend the life of the developer. For example, a resin-impregnated ferrite carrier produced by impregnating a porous ferrite core with 5 to 25% by mass of resin instead of a conventional iron powder carrier or ferrite carrier has been proposed (see, for example, Patent Document 4). .

  The resin-impregnated ferrite carrier has a high resin content and a low specific gravity. Therefore, if the particle size distribution is appropriately controlled, it can be a carrier for a two-component developer that is excellent in durability and can form high-quality images. . However, there is a tendency that irregularly shaped particles due to generation of fine powder or coalescence of carriers are likely to exist.

  Carrier particles that are not spherical are easy to peel off the coating resin on the carrier surface, and the carrier itself is fragile. As a result, the magnetic material and broken particles adhere to the surface of the electrostatic latent image carrier, causing scratches and abrasion on the electrostatic latent image carrier, and obtaining a good image over a long period of time, such as a reduction in image density. It may not be possible. Further, in the simultaneous development cleaning method, there are cases where the residual toner on the surface of the latent electrostatic image bearing member is prevented from being collected or toner adhesion (filming) occurs.

Japanese Patent Publication No. 2-21591 Japanese Patent Laid-Open No. 5-53482 JP-A-10-307456 JP 2003-156877 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method that can cope with downsizing and simplification of a main body, can always obtain a stable image, and can form a high-quality image even during durability. To do.

The object of the present invention is achieved by the following.
(1) a charging step for charging the electrostatic latent image carrier, an electrostatic latent image forming step for forming an electrostatic latent image on the charged electrostatic latent image carrier, and a two-component containing toner and magnetic carrier The electrostatic latent image is developed using a developing unit containing a developer to form a toner image on the electrostatic latent image carrier, and at the same time, the toner remaining on the electrostatic latent image carrier after transfer In an image forming method having at least a development simultaneous recovery step for recovering the toner image and a transfer step for transferring the toner image on the electrostatic latent image carrier to an intermediate transfer member or a transfer material,
The developer is replenished with a replenishment developer containing at least replenishment toner and a replenishment magnetic carrier, and excess magnetic carrier is discharged from the developer.
The toner and the replenishing toner contain at least a binder resin and a colorant, and the binder resin is a resin having a polyester unit;
The average circularity of particles having an equivalent circle diameter of 2 μm or more of the toner and the replenishing toner is 0.950 to 0.990,
The magnetic carrier and the supplementary magnetic carrier have at least a carrier core material and a resin component, the carrier core material is a ferrite having a porous shape, and the true specific gravity of the magnetic carrier and the supplementary magnetic carrier is 2.5 to 4.2 g / cm ³ ,
An image forming method characterized by that.
(2) The toner and the replenishing toner include at least a binder resin, a colorant, and a wax, and the toner and the replenishing toner are toners that are at least surface-modified by heat treatment (1) ) Image forming method.
(3) The toner and the replenishing toner are prepared by dissolving or dispersing a toner composition containing at least a binder resin, a colorant, and a wax in an organic solvent, and suspending the prepared mixed solution in an aqueous medium. The image forming method according to (1), wherein the toner is obtained by granulating and removing the organic solvent.
(4) Any one of (1) to (3) , wherein the replenishment developer contains replenishment toner in a mass ratio of 2 to 50 parts by mass with respect to 1 part by mass of the replenishment magnetic carrier. The image forming method according to claim 1.

  According to the present invention, it is possible to provide an image forming method that can cope with downsizing and simplification of the main body, can always obtain a stable image, and can form a high-quality image even during durability. Specifically, toner adhesion (filming) does not occur on the electrostatic image bearing member over a long period of time, toner chargeability fluctuations and transfer efficiency decrease are small, dot reproducibility is good, and fog is small. An image can be obtained.

In order to solve the problems in the present invention, the inventors have intensively studied,
A two-component developer containing a charging step for charging an electrostatic latent image carrier, an electrostatic latent image forming step for forming an electrostatic latent image on the charged electrostatic latent image carrier, and a toner and a magnetic carrier The electrostatic latent image is developed using a developing unit that accommodates toner to form a toner image on the electrostatic latent image carrier, and at the same time, the toner remaining on the electrostatic latent image carrier after transfer is recovered. In an image forming method comprising at least a development simultaneous recovery step and a transfer step of transferring a toner image on an electrostatic latent image carrier to an intermediate transfer member or a transfer material,
The developer is replenished with a replenishment developer containing at least replenishment toner and a replenishment magnetic carrier, and excess carrier is discharged from the developer.
The toner and the replenishing toner contain at least a binder resin and a colorant, and the binder resin is a resin having a polyester unit;
The average circularity of particles having an equivalent circle diameter of 2 μm or more of the toner and the replenishing toner is 0.950 to 0.990,
The magnetic carrier and the replenishment magnetic carrier have at least a carrier core material and a resin component, and the true specific gravity of the magnetic carrier and the replenishment carrier is 2.5 to 4.2 g / cm ³ ,
It has been found that satisfying the above can output a stable and high-quality image over a long period of time. Details will be described below.

  In the present invention, the developing device is replenished with a replenishing developer containing at least a replenishing toner and a replenishing magnetic carrier, and excess carrier is discharged from the developing device.

  As a result, the replenishment toner and the replenishment magnetic carrier can be replenished in the developing device, and the excess toner and the deteriorated magnetic carrier can be discharged from the developing device at least as necessary. It has become possible to maintain the performance of the agent over a long period of time. Furthermore, it is possible to discharge a deteriorated magnetic carrier that easily adheres to the surface of the electrostatic latent image carrier generated by the stress received in the developing device or a toner with reduced fluidity and transferability, so that the electrostatic latent image carrier The occurrence of scratches and wear on the charging member is suppressed, the adhesion and contamination to the charging member and the like are reduced, and the recovery rate of the transfer residual toner during development can be increased.

The replenishment developer of the present invention preferably contains 2 to 50 parts by mass of replenishment toner with respect to 1 part by mass of the magnetic carrier for replenishment, more preferably 3 to 30 parts by mass, Preferably, it is contained in a mass ratio of 4 to 20 parts by mass. By using in this range, stable developer performance can be maintained over a long period of time, toner filming does not occur, toner chargeability variation is small, and an image with less fog can be obtained.

  When the mass ratio of the replenishment toner is less than 2 parts by mass, the amount of the replenishment toner is relatively small, and the charge amount of the toner in the developing device tends to be uneven. When the amount exceeds 50 parts by mass, the replenishment effect of the replenishment magnetic carrier is difficult to occur, and the performance of the developer tends to be lowered.

The present inventors provide a developing device in which a replenishing developer containing at least a replenishing toner and a replenishing magnetic carrier is replenished, and excess carrier is discharged from the developing device.
An image having a so-called cleaner-less developing method, which simultaneously forms a toner image on an electrostatic latent image carrier of the present invention and simultaneously collects toner remaining on the electrostatic latent image carrier after transfer. By using it in the forming method, the recoverability of the transfer residual toner in the simultaneous development recovery process is remarkably improved as compared with the conventional method, and the performance of the developer in the developing device is maintained for a long period of time. And found that dot reproducibility is excellent.

This is presumed that the charge distribution of the toner in the developing device is always kept constant and sharp even when used for a long period of time by the mechanism described below, and as a result, the above effect is achieved.
In general, when a two-component developer is used for a long period of time, a toner having a large surface area, a large number of contacts with the carrier, a high charge, and a small particle diameter adhere to the surface of the magnetic carrier. Such a toner having a small particle size has a large van der Waals force and a reflection force. Therefore, once attached to the carrier, it is difficult to separate from the carrier, and the carrier becomes a deteriorated carrier that cannot be efficiently charged. Since the developer containing the deteriorated carrier whose surface is contaminated also deteriorates in fluidity, the toner cannot be sufficiently charged, and toner lower than the desired charge amount is generated. As a result, the charge distribution of the entire toner becomes broad.

  For example, when a large amount of images with a small amount of toner consumption is output, toner deterioration tends to proceed and contamination on the carrier surface tends to worsen. In addition, when outputting an image with a large amount of toner consumption, a large amount of toner is supplied in a short period of time, and the toner cannot obtain a sufficient charge amount in a developer having a high ratio of deteriorated carriers. The charge distribution tends to be in a broad state.

  When the toner charge distribution in the developer is broad, not only developability deteriorates and fog is likely to occur in the development process, but transfer uniformity and transfer efficiency decrease in the transfer process, resulting in good dots. It is difficult to reproduce. Further, the charge distribution of the transfer residual toner that is not transferred from the electrostatic charge latent image carrier also becomes broad. In a system having a cleaning mechanism, such broadly charged toner is removed as waste toner.

  On the other hand, in the cleanerless development system of the present invention, in order to improve the recovery rate of the transfer residual toner, it is preferable to make the charge polarity of the transfer residual toner uniform by applying a bias or the like. If it is broad, the charge polarity may not be sufficiently uniform even when a bias is applied. As a result, the transfer residual toner is not sufficiently collected, filming and electrostatic charge latent image carrier charge failure occur, and a high quality image cannot be obtained.

Therefore, when the developing device of the present invention is used in which a replenishing developer containing at least a replenishing toner and a replenishing magnetic carrier is replenished and excess carrier is discharged inside the developing device, the deteriorated carrier is The toner is discharged together with the toner having a too high charge amount attached to the surface. On the other hand, since a developer (replenishment developer) containing a fresh magnetic carrier is always supplied, the replenishment carrier can efficiently charge the toner, and the amount of charge that causes fogging is low. Generation of toner can be suppressed. As a result, the toner charge distribution can always be constant and sharp even during long-term use. As a result, the occurrence of fog is small, transfer uniformity and transfer efficiency are excellent, and transferability of transfer residual toner in the development simultaneous recovery process is remarkably improved compared to the conventional one, and in the developing unit for a long period of time. The performance of the developer is maintained.

The toner and the replenishing toner used in the present invention are the same substance, and hereinafter, the toner and the replenishing toner are collectively referred to as toner.
The present invention is characterized in that it contains at least a binder resin and a colorant, and the binder resin is a resin having a polyester unit.

  In the present invention, development is performed while supplying a replenishment developer containing at least toner and a magnetic carrier to the developing device, and the magnetic carrier that has become excessive inside the developing device due to the replenishment is discharged from at least the developing device. . The replenishment developer is a state in which the toner and the magnetic carrier are mixed and charged in advance, but there is a difference between the chargeability and fluidity of the developer in the developing device and that of the replenishment developer, In the developing device at the time of replenishment, the chargeability and fluidity of the developer are in a non-uniform state. As a result, not only density unevenness occurs in the image and fogging occurs, but also the ratio and amount of the magnetic carrier and toner discharged excessively become unstable.

  In general, a toner using a polyester-based resin has a larger number of chargeable functional groups present on the surface of the toner (resin) than a toner using another resin such as a styrene-acrylic resin. For this reason, a toner using a polyester resin is excellent in charge rising property and has a uniform charge distribution. Therefore, the replenishment developer using the toner is stirred in the developing device immediately after replenishment. Therefore, it is considered that the developer has uniform chargeability and fluidity.

  As the binder resin of the toner used in the present invention, (a) a polyester resin, or (b) a hybrid resin having a polyester unit and a vinyl polymer unit, or (c) a hybrid resin and a vinyl polymer. Or (d) a mixture of a polyester resin and a vinyl polymer, and / or (e) a mixture of a hybrid resin and a polyester resin, and (f) a mixture of a polyester resin, a hybrid resin, and a vinyl polymer. It is resin selected from any one of these.

  In the present invention, “polyester unit” refers to a portion derived from polyester, and “vinyl polymer unit” refers to a portion derived from a vinyl polymer. Polyester monomers constituting the polyester unit include a polyvalent carboxylic acid component and a polyhydric alcohol component. The vinyl monomer constituting the vinyl polymer unit is a monomer component having a vinyl group. A monomer having a polyvalent carboxylic acid component and a vinyl group in the monomer, or a monomer having a polyhydric alcohol component and a vinyl group is defined as a “polyester unit” component.

When a polyester resin is used as the binder resin, alcohol and carboxylic acid, carboxylic acid anhydride, carboxylic acid ester, or the like can be used as a raw material monomer.
Specifically, for example, as the dihydric alcohol component, polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3) -2,2-bis ( 4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.0) -polyoxyethylene (2.0) -2,2 -Alkylene oxide adducts of bisphenol A such as bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane, ethylene glycol, diethylene glycol, triethylene glycol, 1, 2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, Opentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A And hydrogenated bisphenol A.

  Examples of the trivalent or higher alcohol component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, etc. Can be mentioned.

  Examples of the acid component include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid or anhydrides thereof; alkyl dicarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid or anhydrides thereof; Succinic acid substituted with an alkyl group or an anhydride thereof; unsaturated dicarboxylic acids such as fumaric acid, maleic acid and citraconic acid or anhydrides thereof;

  Among these, in particular, a bisphenol derivative represented by the following general formula (1) is used as a diol component, and a carboxylic acid component (for example, fumaric acid) composed of a divalent or higher carboxylic acid or an acid anhydride thereof or a lower alkyl ester thereof. A polyester resin obtained by polycondensation using acid, maleic acid, maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) as an acid component is preferable because it has good charging characteristics as a color toner. .

〔式中、Ｒはエチレン、プロピレン基であり、ｘ，ｙはそれぞれ１以上の整数であり、かつｘ＋ｙの平均値は２〜１０である。〕

[Wherein, R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 10. ]

  Examples of the trivalent or higher polyvalent carboxylic acid component for forming the non-linear polyester resin include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4, and the like. -Naphthalene tricarboxylic acid, 2,5,7-naphthalene tricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid, and anhydrides and ester compounds thereof. The amount of the trivalent or higher polyvalent carboxylic acid component is preferably 0.1 to 1.9 mol% based on the total monomer.

Further, when a hybrid resin having a polyester unit and a vinyl polymer unit is used as the binder resin, further improved release agent dispersibility, low-temperature fixability, and offset resistance can be expected.
The “hybrid resin” used in the present invention means a resin in which a vinyl polymer unit and a polyester unit are chemically bonded. Specifically, a polyester unit and a vinyl polymer unit obtained by polymerizing a monomer having a carboxylic acid ester group such as (meth) acrylic acid ester are formed by a transesterification reaction, preferably a vinyl polymer. Is used to form a graft copolymer (or block copolymer) having a backbone polymer and a polyester unit as a branch polymer.

The following are mentioned as a vinyl-type monomer for producing | generating a vinyl-type polymer. Styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-
Methyl styrene, p-phenyl styrene, p-ethyl styrene, 2,4-dimethyl styrene, pn-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, p- n-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-chlorostyrene, 3,4-dichlorostyrene, m-nitrostyrene, o-nitrostyrene, p-nitro Styrene such as styrene and its derivatives; styrene unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; unsaturated polyenes such as butadiene and isoprene; halogens such as vinyl chloride, vinyldenide, vinyl bromide and vinyl fluoride Vinyl chlorides; vinyl acetate, vinyl propionate, benzoe Vinyl esters such as vinyl; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, methacryl Α-methylene aliphatic monocarboxylic acid esters such as phenyl acid, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, acrylic acid acrylic esters such as n-octyl, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; Vinyl ethers such as ether, vinyl ethyl ether, vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone N-vinyl compounds such as: vinyl naphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide.

  In addition, unsaturated dibasic acids such as maleic acid, citraconic acid, itaconic acid, alkenyl succinic acid, fumaric acid, mesaconic acid; maleic anhydride, citraconic anhydride, itaconic anhydride, alkenyl succinic anhydride, etc. Unsaturated dibasic acid anhydride; maleic acid methyl half ester, maleic acid ethyl half ester, maleic acid butyl half ester, citraconic acid methyl half ester, citraconic acid ethyl half ester, citraconic acid butyl half ester, itaconic acid methyl half ester, Alkenyl succinic acid half ester, fumaric acid methyl half ester, mesaconic acid methyl half ester unsaturated dibasic acid half ester; dimethylmaleic acid, dimethyl fumaric acid unsaturated dibasic acid ester; acrylic acid, meta Α, β-unsaturated acids such as rillic acid, crotonic acid and cinnamic acid; α, β-unsaturated acid anhydrides such as crotonic acid anhydride and cinnamic acid anhydride, the α, β-unsaturated acid and lower fatty acids And monomers having a carboxyl group such as alkenylmalonic acid, alkenylglutaric acid, alkenyladipic acid, acid anhydrides and monoesters thereof.

  Further, acrylic acid or methacrylic acid esters such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate; 4- (1-hydroxy-1-methylbutyl) styrene, 4- (1-hydroxy-1) -Methylhexyl) Monomers having a hydroxy group such as styrene.

In the toner of the present invention, the vinyl polymer unit of the binder resin may have a crosslinked structure crosslinked with a crosslinking agent having two or more vinyl groups.
Examples of the cross-linking agent used in this case include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; examples of diacrylate compounds linked by an alkyl chain include ethylene glycol diacrylate and 1,3. -Butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6 hexanediol diacrylate, neopentyl glycol diacrylate, and those obtained by replacing acrylates of the above compounds with methacrylate Examples of diacrylate compounds linked by an alkyl chain containing an ether bond include diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, Examples include liethylene glycol # 400 diacrylate, polyethylene glycol # 600 diacrylate, dipropylene glycol diacrylate, and acrylates of the above compounds replaced by methacrylate; diacrylates linked by a chain containing an aromatic group and an ether bond. Examples of the compounds include polyoxyethylene (2) -2,2-bis (4-hydroxyphenyl) propane diacrylate and polyoxyethylene (4) -2,2-bis (4-hydroxyphenyl) propane diacrylate. And those obtained by replacing acrylates of the above compounds with methacrylates.

  As polyfunctional cross-linking agents, pentaerythritol triacrylate, trimethylol ethane triacrylate, trimethylol propane triacrylate, tetramethylol methane tetraacrylate, oligoester acrylate and acrylates of the above compounds are replaced by methacrylate; triallylcia Examples include nurate and triallyl trimellitate.

  In the present invention, it is preferable that a monomer component capable of reacting with both resin components is contained in the vinyl polymer component and / or the polyester resin component. Examples of the monomer constituting the polyester resin component that can react with the vinyl polymer include unsaturated dicarboxylic acids such as phthalic acid, maleic acid, citraconic acid, and itaconic acid, or anhydrides thereof. Among the monomers constituting the vinyl polymer component, those capable of reacting with the polyester resin component include those having a carboxyl group or a hydroxy group, and acrylic acid or methacrylic acid esters.

  As a method of obtaining a reaction product of a vinyl polymer and a polyester resin, either a polymer containing a monomer component capable of reacting with each of the vinyl polymer and the polyester resin listed above is present, or either A method obtained by polymerizing both resins is preferred.

Examples of the polymerization initiator used for producing the vinyl polymer of the present invention include 2,2′-azobisisobutyronitrile and 2,2′-azobis (4-methoxy-2,4-dimethyl). Valeronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylbutyronitrile), dimethyl-2,2′-azobisisobutyrate, 1, 1′-azobis (1-cyclohexanecarbonitrile), 2- (carbamoylazo) -isobutyronitrile, 2,2′-azobis (2,4,4-trimethylpentane), 2-phenylazo-2,4-dimethyl- 4-methoxyvaleronitrile, 2,2'-azobis (2-methyl-propane), methyl ethyl ketone peroxide, acetylacetone peroxide, cyclohexanone Ketone peroxides such as oxide, 2,2-bis (t-butylperoxy) butane, t-butyl hydroperoxide, cumene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, di -T-butyl peroxide, t-butyl cumyl peroxide, di-cumyl peroxide, α, α'-bis (t-butylperoxyisopropyl) benzene, isobutyl peroxide, octanoyl peroxide, decanoyl peroxide, Lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, m-toluoyl peroxide, di-isopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-n-pro Ruperoxydicarbonate, di-2-ethoxyethyl peroxycarbonate, di-methoxyisopropyl peroxydicarbonate, di (3-methyl-3-methoxybutyl) peroxycarbonate, acetylcyclohexylsulfonyl peroxide, t-butylperoxy Acetate, t-butylperoxyisobutyrate, t-butylperoxyneodecanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxylaurate, t-butylperoxybenzoate, t-butylperoxyisopropyl carbonate, di-t-butylperoxyisophthalate, t-butylperoxyallyl carbonate, t-amylperoxy-2-ethylhexanoate, di-t-butylperoxyhexahydro Terephthalate, di -t- butyl peroxy azelate and the like.

  Examples of the production method for preparing the hybrid resin used in the toner of the present invention include the production methods shown in the following (1) to (6).

  (1) A method in which a vinyl polymer, a polyester resin, and a hybrid resin component are blended after production. The blend is produced by dissolving and swelling in an organic solvent (for example, xylene) and then distilling off the organic solvent. The hybrid resin component is synthesized by separately producing a vinyl polymer and a polyester resin, dissolving and swelling in a small amount of an organic solvent, adding an esterification catalyst and an alcohol, and performing a transesterification reaction by heating. The ester compound used can be used.

  (2) A method of obtaining a hybrid resin having a vinyl polymer unit and a polyester unit by reacting a polyester unit component and / or a hybrid resin component in the presence of the vinyl polymer unit after the production thereof. The hybrid resin component is produced by a reaction between a vinyl polymer unit (a vinyl monomer can be added if necessary) and a polyester monomer (alcohol, carboxylic acid) and / or polyester. Also in this case, an organic solvent can be appropriately used.

  (3) A method of obtaining a hybrid resin having a vinyl polymer unit and a polyester unit by reacting a vinyl polymer unit component and / or a hybrid resin component in the presence of the polyester unit after the production of the polyester unit. The hybrid resin component is produced by a reaction between a polyester unit (a polyester monomer can be added if necessary) and a vinyl monomer and / or vinyl polymer unit. Also in this case, an organic solvent can be appropriately used.

  (4) After the production of the vinyl polymer unit and the polyester unit, the vinyl polymer unit and the polyester monomer (alcohol, carboxylic acid) are added and reacted in the presence of these polymer units, A hybrid resin having a polyester unit is manufactured. Also in this case, an organic solvent can be appropriately used.

  (5) After producing a hybrid resin component having a vinyl polymer unit and a polyester unit, by adding a vinyl monomer and / or a polyester monomer (alcohol, carboxylic acid) and performing an addition polymerization and / or a condensation polymerization reaction. A hybrid resin having a vinyl polymer unit and a polyester unit is produced. In this case, as the hybrid resin component, those produced by the production methods (2) to (4) can be used, and those produced by a known production method can be used as necessary. Furthermore, an organic solvent can be used as appropriate.

  (6) A hybrid resin having a vinyl polymer unit and a polyester unit is produced by mixing a vinyl monomer and a polyester monomer (alcohol, carboxylic acid, etc.) and continuously performing an addition polymerization and a condensation polymerization reaction. . Furthermore, an organic solvent can be used as appropriate.

In the production methods (1) to (6) above, a hybrid resin may be produced using various vinyl polymer units and / or polyester units having different molecular weights and cross-linking degrees.

A known pigment or dye can be used as the colorant contained in the toner of the present invention, and is not particularly limited. Examples of the pigment include the following.
As a colorant suitable for magenta, a pigment or a dye can be used. Specifically, examples of the color pigment for magenta toner include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 48; 2, 48; 3, 48; 4, 49, 50, 51, 52, 53, 54, 55, 57, 57; 1, 58, 60, 63, 64, 68, 81, 81; 1, 83, 87, 88, 89, 90, 112, 114, 122, 123, 144, 146, 150, 163, 166, 169, 177, 184, 185, 202, 206, 207, 209, 220, 221, 238, 254, etc., C.I. I. Pigment violet 19; C.I. I. Vat red 1, 2, 10, 13, 15, 23, 29, 35, and the like. Examples of magenta dyes include C.I. I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 52, 58, 63, 81, 82, 83, 84, 100, 109, 111, 121, 122, etc. I. Disper thread 9, C.I. I. Solvent Violet 8, 13, 14, 21, 27 etc., C.I. I. Oil-soluble dyes such as disperse violet 1, C.I. I. Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40, etc. I. Basic violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28, etc. may be mentioned, and such a pigment may be used alone. It is more preferable from the viewpoint of the image quality of a full-color image to improve the sharpness by using in combination, and these are used alone or in combination of two or more.

  As other color pigments, pigments or dyes can be used as colorants suitable for cyan. Specifically, examples of the pigment include C.I. I. Pigment Blue 1, 7, 15, 15; 1, 15; 2, 15; 3, 15; 4, 16, 17, 60, 62, 66, etc., C.I. I. Bat Blue 6, C.I. I. Acid Blue 45 and the like, and examples of the dye include C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95 etc. are mentioned, These are used alone or in combination of two or more.

  As the colorant suitable for the yellow color, a pigment or a dye can be used. Specifically, examples of the pigment include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 17, 23, 62, 65, 73, 74, 81, 83, 93, 94, 95, 97, 98, 109, 110, 111, 117, 120, 127, 128, 129, 137, 138, 139, 147, 151, 154, 167, 168, 173, 174, 176, 180, 181, 183, 191, C. I. Vat yellow 1, 3, 20 etc. are mentioned, As a dye, C.I. I. Solvent yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162 etc. are mentioned, These are used alone or in combination of two or more.

  As the black colorant, for example, carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black is used, and iron oxide such as magnetite and ferrite, or yellow / magenta / cyan / black as shown above. The thing adjusted to black using the coloring agent can be utilized.

In the toner used in the present invention, it is preferable to use a toner obtained by mixing a colorant in advance with the binder resin of the present invention to form a master batch. Then, the colorant can be favorably dispersed in the toner by melt-kneading the colorant master batch and other raw materials (binder resin, wax, etc.).

  When a colorant is masterbatched using a resin that can be used in the present invention, the dispersibility of the colorant does not deteriorate even when a large amount of colorant is used. Further, the dispersibility in the toner particles is improved, and the toner is excellent in color reproducibility such as color mixing and transparency. Further, a toner having a large covering power on the transfer material can be obtained. Further, by improving the dispersibility of the colorant, it is possible to obtain an image with excellent durability stability of toner chargeability and maintaining high image quality.

  In addition, it is preferable that the usage-amount of a coloring agent is 0.1-60 mass parts with respect to 100 mass parts of binder resin, and it is more preferable that it is 0.5-50 mass parts.

It is preferable to add a release agent such as wax as the other component to the toner of the present invention. Next, the release agent that can be used in the present invention will be described.
Examples of the release agent that can be used in the present invention include the following. Aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymers, polyolefin wax, microcrystalline wax, paraffin wax, Fischer-Tropsch wax; oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax; Alternatively, block copolymers thereof; waxes mainly composed of fatty acid esters such as carnauba wax, behenyl behenate, and montanic acid ester wax; partially or entirely deoxidized fatty acid esters such as deoxidized carnauba wax. Things. Further, saturated linear fatty acids such as palmitic acid, stearic acid, montanic acid, or long-chain alkyl carboxylic acids having a long-chain alkyl group; unsaturated fatty acids such as brandic acid, eleostearic acid, and valinal acid Saturated alcohols such as stearic alcohol, aralkyl alcohol, behenyl alcohol, carnauvir alcohol, seryl alcohol, melyl alcohol, or long-chain alkyl alcohols having a long-chain alkyl group; polyhydric alcohols such as sorbitol; linol Fatty acid amides such as acid amide, oleic acid amide, lauric acid amide; saturated fatty acids such as methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis lauric acid amide, hexamethylene bis stearic acid amide Unsaturated fatty acid amides such as samides, ethylenebisoleic acid amide, hexamethylenebisoleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide; Aromatic bisamides such as stearamide, N, N'-distearylisophthalamide; fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate, magnesium stearate (generally referred to as metal soap) Waxes grafted to aliphatic hydrocarbon waxes using vinyl monomers such as styrene and acrylic acid; partially esterified products of fatty acids and polyhydric alcohols such as behenic acid monoglyceride; by hydrogenation of vegetable oils and fats, etc. With the resulting hydroxyl group And methyl ester compounds.

  The toner of the present invention preferably contains one or more waxes. Furthermore, the toner of the present invention has one or a plurality of endotherms in a temperature range of 30 to 200 ° C. in an endothermic curve in differential scanning calorimetry (DSC) measurement from the viewpoint of achieving both low-temperature fixability and blocking resistance. It has a peak, and it is desirable that the peak temperature of the maximum endothermic peak in the endothermic peak is in the range of 60 to 110 ° C. More preferably, the maximum peak of the endothermic curve is in the range of 65 to 100 ° C. When the peak temperature of the maximum endothermic peak is less than 60 ° C., the blocking resistance of the toner may deteriorate, and conversely, when the peak temperature of the maximum endothermic peak exceeds 110 ° C., the fixability is deteriorated.

  The release agent is used in an amount of 0.5 to 10 parts by mass, preferably 2 to 8 parts by mass, per 100 parts by mass of the binder resin.

  If necessary, a charge control agent can be added to the toner of the present invention as other components. Known charge control agents can be used, and examples thereof include aromatic carboxylic acid derivatives and aromatic carboxylic acid metal compounds. For example, the metal of the aromatic carboxylic acid metal compound is preferably a divalent or higher valent metal atom.

Examples of the divalent metal include Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Pb ²⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ , Zn ²⁺ and Cu ²⁺ . As such a divalent metal, Zn ²⁺ , Ca ²⁺ , Mg ²⁺ and Sr ²⁺ are preferable. Examples of the trivalent or higher metal include Al ³⁺ , Cr ³⁺ , Fe ³⁺ , Ni ³⁺ , Ti ⁴⁺ , Zr ⁴⁺ , and Si ⁴⁺ . Among these metals, Al ³⁺ and Cr ³⁺ are preferable, and Al ³⁺ is particularly preferable. In the present invention, an aluminum compound of di-tert-butylsalicylic acid is particularly preferably used as the charge control agent.

  When the charge control agent is used in an amount of 0.1 to 10% by mass based on the mass of the toner, the initial fluctuation of the charge amount of the toner is small, and an absolute charge amount necessary for development is easily obtained. This is preferable since there is no decrease in image quality such as density reduction.

  For the purpose of improving the toner performance, the toner can use fine particles such as toner particles, a fluidizing agent, a transfer aid, a charge stabilizer, and an abrasive. It can mix with such a mixer.

  For example, fine powders added for the purpose of obtaining charging stability and fluidity include, for example, fluororesin powders such as vinylidene fluoride fine powder and polytetrafluoroethylene fine powder, titanium oxide fine powder, and alumina fine powder. Examples thereof include fine powder silica such as powder, wet process silica and dry process silica, and treated silica subjected to surface treatment with silane compounds, organosilicon compounds, titanium coupling agents, silicone oils, and the like.

The dry process silica is a fine powder produced by vapor phase oxidation of a silicon halogen compound, and is called so-called dry process silica or fumed silica, and is manufactured by a conventionally known technique. For example, a thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame is used, and the basic reaction formula is as follows.
SiCl ₄ + 2H ₂ + O ₂ → SiO ₂ + 4HCl

  In this production process, it is also possible to obtain a composite fine powder of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride or titanium chloride together with silicon halogen compounds. . The average primary particle size is preferably in the range of 0.001 to 2 μm, particularly preferably silica fine powder in the range of 0.002 to 0.2 μm. .

  As the titanium oxide fine powder, fine particles of titanium oxide obtained by a low-temperature oxidation method (thermal decomposition, hydrolysis) of sulfuric acid method, chlorine method, volatile titanium compounds such as titanium alkoxide, titanium halide and titanium acetylacetonate are used. . As the crystal system, any of anatase type, rutile type, mixed crystal type thereof, and amorphous type can be used.

In addition, the alumina fine powder includes the buyer method, improved buyer method, ethylene chlorohydrin method, underwater spark discharge method, organoaluminum hydrolysis method, aluminum alum pyrolysis method, ammonium aluminum carbonate pyrolysis method, aluminum chloride Alumina fine powder obtained by flame decomposition method is used. As the crystal system, α, β, γ, δ, ζ, η, θ, κ, χ, ρ type, mixed crystal type or amorphous type of these can be used. Α, δ, γ, θ, mixed crystal A mold or an amorphous material is preferably used.

  Further, as the silica subjected to the above surface treatment, those obtained by chemical or physical treatment with an organosilicon compound that reacts or physically adsorbs with inorganic fine powders are used. Specifically, silica fine powder produced by vapor phase oxidation of a silicon halogen compound is treated with an organosilicon compound. Examples of such organosilicon compounds include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchloro. Silane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, Dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisilo And xylene, 1,3-diphenyltetramethyldisiloxane, and dimethylpolysiloxane having 2 to 12 siloxane units per molecule and having one hydroxyl group in each of the Si units located at the terminal. These are used alone or in a mixture of two or more.

  Further, the above-described dry process silica may be used after being treated with a coupling agent having an amino group or silicone oil.

  Examples of particles having a polishing effect (hereinafter referred to as abrasives) that are added for the purpose of removing charged products on the surface of the latent electrostatic image bearing member include strontium titanate, barium titanate, and calcium titanate. , Cerium oxide, silicon carbide, titania, alumina and the like, and the composition thereof is not particularly limited, but strontium titanate is preferable in terms of the shape and hardness of the fine particles.

  The content of the various fine powder particles is preferably 0.01 to 8.0 parts by mass, and more preferably 0.1 to 4.0 parts by mass with respect to 100 parts by mass of the toner.

  Further, in the molecular weight distribution measured by gel permeation chromatography (GPC) of the THF-soluble matter in the toner, it is preferable to have at least one main peak in the region of molecular weight 10,000 to 100,000. By having at least one main peak in this range, a toner excellent in developability and fixability can be obtained. In addition, the strength of the toner is increased and toner deterioration in the developing device is reduced. When the main peak molecular weight is less than 10,000, the fixability is improved, but the storage stability and the stress resistance in the developing device are weakened, and the developability may be lowered, which is not preferable. When the main peak molecular weight exceeds 100,000, the fixing property is deteriorated, which is not preferable.

Further, the toner used in the present invention is characterized in that the average circularity of particles having an equivalent circle diameter (number basis) of 2 μm or more is 0.950 to 0.990. The toner used in the present invention can be manufactured within the above-mentioned range by performing a spheroidizing treatment described later. Preferably, it is 0.950-0.985, More preferably, it is 0.955-0.980. When the thing of the said range is used, it is preferable when making transferability and developability compatible. When the average circularity of the toner is lower than 0.950, the transfer uniformity is lowered, and the dot reproducibility tends to deteriorate under a high temperature and high humidity environment. In addition, desired fluidity is difficult to obtain, and the charge rising property may be reduced. When the average circularity of the toner is higher than 0.990, the contact area with the conveying member and magnetic carrier in the developing device is small, so that the surface of the toner is more susceptible to stress and has the purpose of obtaining fluidity and charging stability. Embedding of various inorganic fine particles added to the toner tends to cause toner deterioration.

  The toner of the present invention preferably has a weight average diameter (D4) of 3.0 μm to 11.0 μm, more preferably 4.0 μm to 10.0 μm, and still more preferably 4.5 μm to 9. 0 μm. When the weight average diameter (D4) of the toner in the replenishment developer is within this range, an image with good dot reproducibility can be obtained. When the weight average diameter (D4) of the toner is less than 3.0 μm, the specific surface area of the toner is increased, and the surface existing amount on the carrier in the replenishment developer is increased. As a result, when replenished into the developing device, the mixing with the carrier in the developing device is deteriorated and the uniformity is deteriorated. On the other hand, when the weight average diameter (D4) of the toner exceeds 11.0 μm, the dot reproducibility is deteriorated and it is difficult to improve the image quality.

The magnetic carrier and the replenishing magnetic carrier used in the present invention are the same substance. Hereinafter, the magnetic carrier and the replenishing magnetic carrier are collectively referred to as a magnetic carrier.
The magnetic carrier used in the present invention has at least a carrier core material and a resin component, and the magnetic carrier has a true specific gravity of 2.5 to 4.2 g / cm ³ . The true specific gravity of the magnetic carrier is preferably 2.7 to 4.1 g / cm ³ , more preferably 3.0 to
4.0 g / cm ³ . When the true specific gravity of the magnetic carrier is within this range, an image with good dot reproducibility can be obtained over a long period of time. A carrier in this range can be produced by appropriately adjusting the amount of the carrier core and the resin contained, or by appropriately selecting the fine particles to be blended. If it is less than 2.5 g / cm ³ , it becomes easy to develop on the electrostatic latent image carrier during development,
May cause carrier adhesion. If it exceeds 4.2 g / cm ³ , dot reproducibility during development deteriorates, and further, stress on the developer in the developing device increases, which may deteriorate the magnetic carrier. Further, the specific gravity difference from the toner becomes large, and the magnetic carrier tends to segregate in the replenisher, so that stable replenishment becomes difficult. The carrier core material refers to a magnetic body and a resin constituting the carrier core.

  The magnetic carrier preferably has an average circularity of 0.850 to 0.950, more preferably 0.870 to 0.930, and still more preferably 0.880 to 0.920. . When the average circularity is 0.850 to 0.950, the magnetic carrier of the present invention has sufficient carrier strength, excellent chargeability to the toner, hardly damages the toner, and has a toner spent. Less likely to occur and excellent durability. When the average circularity is less than 0.850, it means that the particles have an irregular shape. In this case, the charge imparting property to the toner may be deteriorated, which is not preferable. On the other hand, when the average circularity exceeds 0.950, the specific surface area of the magnetic carrier becomes small, and the charge imparting property may be lowered.

The magnetic carrier preferably contains 90% by number or more of particles having an average circularity of 0.800 or more. When 90% by number or more of particles having a circularity of 0.800 or more are contained, it is preferable because the toner has a uniform charge imparting property. If it is less than 90% by number, the charge imparting property is deteriorated and further the mixing property in the developing device is deteriorated, which is not preferable.

Further, the magnetic carrier preferably has a 50% particle size (D50) based on volume distribution of 15 to 70 μm, more preferably 20 to 70 μm, and further preferably 25 to 60 μm. When the 50% particle size (D50) based on the volume distribution of the magnetic carrier is within this range, an image with good dot reproducibility can be obtained over a long period of time. When the thickness is less than 15 μm, the specific surface area of the magnetic carrier is increased and the mixing property with the toner is improved, but the magnetic carrier may adhere to the electrostatic latent image bearing member during development. When the thickness exceeds 70 μm, the stress applied to the toner increases, and the developability may be deteriorated.

The magnetic carrier is not particularly limited as long as the above physical properties are satisfied. For example, a magnetic material-dispersed resin carrier in which a magnetic material is dispersed in a resin may be used, or a so-called resin-impregnated carrier in which a porous magnetic material (including porous ferrite) is impregnated with a resin may be used. .

  Among the above magnetic carriers, from the viewpoint of average circularity, a magnetic material-dispersed resin carrier in which a magnetic material is dispersed in a resin is preferably used.

As a method for producing the magnetic material-dispersed resin carrier, there is a method in which a monomer constituting a resin and a magnetic material are mixed and the monomer is polymerized in the presence of the magnetic material.
At this time, as monomers used for polymerization, in addition to vinyl monomers, bisphenols and epichlorohydrin for forming epoxy resins; phenols and aldehydes for forming phenol resins; urea resins are formed Urea and aldehydes for forming; melamine and aldehydes for forming melamine resin are used.
For example, as a method for producing a magnetic material-dispersed resin carrier using a phenol resin, a magnetic material is contained in an aqueous medium, and the phenols and aldehydes are polymerized in the presence of a basic catalyst in the aqueous medium. A resin carrier can be obtained.

  Phenol resin is preferable as the resin for forming the magnetic material-dispersed resin carrier used in the present invention. As phenols for producing the phenol resin, m-cresol, p-tert-butylphenol, o- in addition to phenol. Examples include alkylphenols such as propylphenol, resorcinol and bisphenol A, and compounds having a phenolic hydroxyl group such as benzene nuclei or halogenated phenols in which some or all of the alkyl groups are substituted with chlorine atoms or bromine atoms. Of these, phenol (hydroxybenzene) is more preferable.

  Examples of aldehydes for producing the phenol resin include formaldehyde and furfural in the form of either formalin or paraaldehyde. Of these, formaldehyde is particularly preferable.

  The molar ratio of aldehydes to phenols is preferably 1 to 4, particularly preferably 1.2 to 3. When the molar ratio of aldehydes to phenols is less than 1, particles are difficult to generate, and even if they are generated, the resin does not easily cure, so the strength of the generated particles tends to be weak. On the other hand, when the molar ratio of aldehydes to phenols is larger than 4, unreacted aldehydes remaining in the aqueous medium after the reaction tend to increase.

  Examples of the basic catalyst used in the condensation polymerization of phenols and aldehydes include those used in the production of ordinary resol type resins. Examples of such basic catalysts include aqueous ammonia, hexamethylenetetramine, and alkylamines such as dimethylamine, diethyltriamine, and polyethyleneimine. The molar ratio of these basic catalysts to phenols is preferably 0.02 to 0.30.

  As another method for producing the above magnetic material-dispersed resin carrier, a vinyl-type or non-vinyl-type thermoplastic resin, a magnetic material, and other additives are sufficiently mixed by a mixer, and then a heating roll, a kneader, and an extruder. There is a method in which a magnetic material-dispersed resin core is obtained by melting and kneading using a kneader such as the above, cooling it, and then crushing and classifying it. At this time, it is preferable that the obtained magnetic material dispersed resin core is thermally or mechanically spheroidized and used as a magnetic material dispersed resin carrier.

  Further, the magnetic material-dispersed resin carrier may be used by replacing a part of the magnetic material with a non-magnetic inorganic compound in order to adjust the true specific gravity and magnetic characteristics.

In the magnetic material-dispersed resin carrier, the magnetic material is preferably magnetite fine particles or magnetic ferrite fine particles containing at least an iron element. The nonmagnetic inorganic compound is preferably hematite (α-Fe ₂ O ₃ ) fine particles in order to make the dispersibility in the carrier uniform and adjust the magnetic properties and true specific gravity of the carrier.

  The number average particle diameter of the magnetic material is preferably 0.02 to 2 μm from the viewpoint of making the state of the particle surface of the magnetic carrier uniform. The nonmagnetic inorganic compound preferably has a number average particle size of 0.05 to 5 μm, and the particle size of the nonmagnetic inorganic compound is 1.1 times or more larger than the particle size of the magnetic material. It is preferable for increasing the surface resistance value.

  The surface of the magnetic material-dispersed resin carrier is preferably coated with various resins. As a resin for forming the coating material, an insulating resin is preferably used. The insulating resin that can be used in this case may be a thermoplastic resin or a thermosetting resin. Furthermore, the coating material may contain particles having conductivity and particles having charge controllability.

Further, as the magnetic carrier used in the present invention, a resin-impregnated carrier containing a ferrite component having a porous shape can also be preferably used.
A preferred resin-impregnated carrier core in the present invention is a ferrite core. Although depending on the composition of the core, the true specific gravity of the ferrite core is usually about 5.0 g / cm ³ . Therefore, in order to achieve a desired true specific gravity using a ferrite core, it is necessary to increase the ratio of the resin to be contained. In the ferrite carrier, the surface shape can be made any shape from smooth to porous by controlling the degree of sintering growth on the particle surface during the production of the core or by using a foaming agent or the like. The polar score here is a core having pores inside or on the surface of the core. The production method can be obtained by suppressing crystal growth by lowering the temperature during firing, or by generating pores in the core by adding a pore-forming agent such as a foaming agent.

  In this way, the ferrite core can easily control the surface shape, and a magnetic carrier having a desired true specific gravity can be obtained by adjusting various cores and the amount of resin contained.

  As a foaming agent, it is a substance that generates gas upon vaporization or decomposition at 60 to 180 ° C., for example, a foaming azo type such as azobisisobutyronitrile, azobisdimethylvaleronitrile, azobiscyclohexanecarbonitrile, etc. Polymerization initiators, metal hydrogen carbonates such as sodium and potassium, ammonium hydrogen carbonate, ammonium carbonate, ammonium nitrate, azide compounds, 4,4'-oxybis (benzenesulfohydrazide), allylbis (sulfohydrazide), diaminobenzene and the like It is done.

In the present invention, examples of the ferrite component contained in the magnetic carrier include ferrite having magnetism represented by the following formula (1) or (2).
MO · Fe ₂ O ₃ (1)
M · Fe ₂ O ₄ (2)
(In the formula, M represents a trivalent, divalent or monovalent metal ion.)
Examples of M include Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Nb, Mo, Sn, Ba, and Li. These can be used alone or in combination.

Specific examples of the metal compound particles having magnetism include, for example, Zn—Fe ferrite, Mn—Zn—Fe ferrite, Ni—Zn—Fe ferrite, Mn—Mg—
Examples thereof include iron-based oxides such as Fe-based ferrite, Ca-Mn-Fe-based ferrite, Ca-Mg-Fe-based ferrite, Li-Fe-based ferrite, and Cu-Zn-Fe-based ferrite.

  A well-known method can be employ | adopted for the manufacturing method of a ferrite core. For example, a pulverized ferrite composition is mixed with a binder, water, a dispersant, an organic solvent, and the like, and particles are formed using a spray dryer method or a fluidized granulation method, and then 700 to 1400 in a rotary kiln or a batch-type firing furnace. There may be mentioned a method in which the carrier core is obtained by firing at a temperature in the range of ° C., preferably 800 to 1200 ° C., and then classifying by sieve to control the particle size distribution. Further, the surface property of the carrier core can be controlled by controlling the oxygen partial pressure in the firing stage or adding oxidation / reduction treatment to the surface of the particles after firing.

  The resin component that constitutes the magnetic carrier is a resin that coats the surface of the magnetic carrier core or a resin that is impregnated with a porous material, but the resin component is not particularly limited. Specifically, for example, acrylic resin such as polystyrene and styrene-acrylic copolymer, vinyl chloride, vinyl acetate, polyvinylidene fluoride resin, fluorocarbon resin, perfluorocarbon resin, solvent-soluble perfluorocarbon resin, polyvinyl alcohol, polyvinyl acetal, Polyvinyl pyrrolidone, petroleum resin, cellulose, cellulose derivative, novolac resin, low molecular weight polyethylene, saturated alkyl polyester resin, aromatic polyester resin, polyamide resin, polyacetal resin, polycarbonate resin, polyethersulfone resin, polysulfone resin, polyphenylene sulfide resin, poly Ether ketone resin, phenol resin, modified phenol resin, maleic resin, alkyd resin, epoxy resin, acrylic resin, anhydrous male Unsaturated polyester obtained by polycondensation of acid, terephthalic acid and polyhydric alcohol, urea resin, melamine resin, urea-melamine resin, xylene resin, toluene resin, guanamine resin, melamine-guanamine resin, acetoguanamine resin, gliptal Examples thereof include resins, furan resins, silicone resins, polyimide resins, polyamideimide resins, polyetherimide resins, and polyurethane resins. Alternatively, a resin obtained by modifying these resins may be used.

  Of these, fluorine-containing resins such as polyvinylidene fluoride resins, fluorocarbon resins, perfluorocarbon resins, and solvent-soluble perfluorocarbon resins, acrylic-modified silicone resins, and silicone resins are preferable because of their high releasability.

  More specifically, the silicone resin may be any conventionally known silicone resin, such as a straight silicone resin consisting only of an organosiloxane bond represented by the following formula and an alkyd, polyester, epoxy, urethane, etc. Examples thereof include modified silicone resins.

上記式中Ｒ_１は、水素原子、炭素数１〜４のアルキル基又はフェニル基、Ｒ_２及びＲ_３は水素原子、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、フェニル基、炭素数２〜４のアルケニル基、炭素数２〜４のアルケニルオキシ基、ヒドロキシ基、カルボキシル基、エチレンオキシド基、グリジニル基又は下記で示される基である。
上記式中Ｒ_４及び下記式中Ｒ_５は、ヒドロキシ基、カルボキシル基、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、炭素数２〜４のアルケニル基、炭素数２〜４のアルケニルオキシ基、フェニル基、フェノキシ基を表し、ｋ、ｌ、ｍ、ｎ、ｏ、ｐは１以上の正数を示す。

In the above formula, R ₁ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a phenyl group, R ₂ and R ₃ are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, phenyl Group, an alkenyl group having 2 to 4 carbon atoms, an alkenyloxy group having 2 to 4 carbon atoms, a hydroxy group, a carboxyl group, an ethylene oxide group, a glycinyl group, or a group shown below.
R _{4 in the} above formula and R ₅ in the following formula are a hydroxy group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, and 2 to 2 carbon atoms. 4 represents an alkenyloxy group, a phenyl group, or a phenoxy group, and k, l, m, n, o, and p are each a positive number of 1 or more.

  Each of the above substituents may have a substituent such as an amino group, a hydroxy group, a carboxyl group, a mercapto group, an alkyl group, a phenyl group, an ethylene oxide group, or a halogen atom in addition to an unsubstituted group. For example, commercially available straight silicone resins include KR271, KR255, KR152 manufactured by Shin-Etsu Chemical Co., Ltd., SR2400, SR2405 manufactured by Toray Dow Corning Co., Ltd., and modified silicone resins include KR206 (alkyd modified) manufactured by Shin-Etsu Chemical Co. There are KR5208 (acrylic modification), ES1001N (epoxy modification), KR305 (urethane modification), SR2115 (epoxy modification) and SR2110 (alkyd modification) manufactured by Toray Dow Corning.

  In the present invention, a silicone resin is preferably used from the viewpoints of adhesion to the core, prevention of spent, and film strength. The silicone resin can be used alone, but is preferably used in combination with a coupling agent. It is also preferable to use a plurality of resins in combination from the viewpoint of improving the coating strength.

Suitable coupling agents include silane coupling agents, titanium coupling agents, aluminum coupling agents and the like. Examples of the silane coupling agent preferably used in the present invention include γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, and γ-methacryloxypropyltrimethoxysilane. N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxy Silane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, hexamethyldisilazane, γ-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] an Nitric chloride, γ-chloropropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane (made by Torre Silicone), allyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltri Examples include methoxysilane, dimethyldiethoxysilane, 1,3-divinyltetramethyldisilazane, and methacryloxyethyldimethyl (3-trimethoxysilylpropyl) ammonium chloride (manufactured by Chisso Corporation).

  Of these, aminosilane is preferably used as the coupling agent. As a result, an amino group having positive chargeability can be introduced on the surface of the magnetic carrier, and negative charge characteristics can be imparted to the toner satisfactorily. Furthermore, the presence of the amino group activates both the lipophilic agent preferably treated with the metal compound and the silicone resin, thereby further improving the adhesion of the silicone resin to the magnetic carrier core, and at the same time, By promoting the curing, a stronger coating layer can be formed. In addition, a coating layer here means the below-mentioned resin layer and / or coat layer.

  In addition, the magnetic carrier having a resin component preferably has a resin layer of 5.0 to 25.0% by mass with respect to the mass of the carrier core in order to make the true specific gravity of the magnetic carrier a desired value. More preferably, it is 7.0-20.0 mass%, More preferably, it is 9.0-15.0 mass%. Further, the carrier surface may be coated separately from the resin layer. In that case, the components of the resin layer and the coat layer may be the same or different.

  In the magnetic carrier of the present invention, particles are preferably added to the coating layer. By adding particles to the coating layer, fine surface irregularities that do not appear as average circularity can be formed on the surface of the magnetic carrier. Due to the unevenness, the toner and the magnetic carrier can be efficiently contacted, and peeling of the resin coating layer of the magnetic carrier can be suppressed.

  The particles added to the coating layer preferably have a primary number average particle diameter of 10 to 500 nm. When these particles are coated, they have the effect of improving the rising of the toner in order to form minute irregularities present on the carrier surface. In addition, the presence of unevenness improves the spent resistance, and the durability can be maintained. The average particle size of the more preferable particles is 50 to 200 nm.

Further, as the particles to be used, particles having a specific resistance of 10 ¹² Ω · cm or more are preferable. By using such particles, the charge imparting property of the magnetic carrier surface is maintained without being affected by the environment, and the environmental fluctuation of the developer is reduced.

Examples of the particles include a polymer (resin fine particles) homopolymerized or copolymerized using alumina or a polymerizable monomer exemplified below.
Examples of the polymerizable monomer include styrene monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methoxystyrene, p-ethylstyrene, α-methylstyrene, and p-tertiarybutylstyrene; acrylic Acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, n-propyl acrylate, isobutyl acrylate, octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, Acrylic esters such as phenyl acrylate; methacrylic acid, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, methacrylic acid 2 Methacrylic acid esters such as ethylhexyl, stearyl methacrylate, phenyl methacrylate, dimethylaminomethyl methacrylate, diethylaminoethyl methacrylate; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, etc .; vinyl Derivatives, specifically alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl ether, isobutyl ether, β-chloroethyl vinyl ether, phenyl vinyl ether, p-methylphenyl vinyl ether, p-chlorophenyl vinyl ether, p -Bromophenyl vinyl ether, p-nitrophenyl vinyl ether, p-methoxyphenyl vinyl Ether, 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, N- vinylpyrrolidone, 2-vinylimidazole, N- methyl-2-vinylimidazole, N- vinylimidazole, it may be mentioned butadiene. In particular, polymethyl methacrylate (PMMA) and melamine resin are more preferable. Known PMMA particles can be used, and materials necessary for the intended electrophotographic developing toner can be selected, but cross-linked PMMA particles are preferably used.

  In addition, as a method for granulating the resin fine particles used in the present invention, a method of pulverizing the above polymer, a particle polymerization method such as emulsion polymerization, soap-free emulsion polymerization, suspension polymerization, dispersion polymerization, or the like may be used. it can.

  The amount of resin fine particles added is preferably 0.1 to 50% by mass with respect to the resin layer coated on the magnetic carrier core. More preferably, a better effect can be imparted at 1.0 to 45% by mass.

  As a method of coating the resin surface on the carrier surface, it is common to dilute the resin in a solvent and coat the surface of the magnetic carrier core. The solvent used here should just be a thing in which each resin is soluble. When the resin is a resin soluble in an organic solvent, examples of the organic solvent include toluene, xylene, butyl cellosolve acetate, methyl ethyl ketone, methyl isobutyl ketone, and methanol. When the resin is a water-soluble resin or emulsion type, Water may be used. The magnetic carrier core surface is coated with a resin diluted with a solvent by a coating method such as dipping, spraying, brushing, fluidized bed, and kneading, and then the solvent is volatilized. In addition, it is also possible to coat the resin carrier fine particles on the surface of the magnetic carrier core by a dry method instead of a wet method using such a solvent. Further, when the resin coating is applied, it is more preferable to apply the coating resin component twice, since the adhesion of the coating resin is increased and a uniform coating layer is obtained on the carrier surface. The coating method may be the method exemplified in the above coating method. When the coating is applied twice, the same method or different methods may be used.

  When the resin core is coated and then baked, either an external heating method or an internal heating method may be used. For example, a stationary or fluid electric furnace, a rotary electric furnace, a burner furnace, or a microwave baking may be used. The baking temperature varies depending on the resin to be used, but a temperature higher than the melting point or glass transition point is necessary, and in the case of a thermosetting resin or a condensation type resin, it is necessary to raise it to a temperature at which the curing proceeds sufficiently.

  Thus, after the resin is coated and baked on the surface of the carrier core, it is cooled, crushed and subjected to particle size adjustment to obtain a resin-coated carrier.

The resin fine particles may be present on the carrier surface. However, as a method of inclusion, it is preferable to disperse the resin fine particles in a solvent at the time of resin coating and to disperse the resin fine particles together with the carrier coating resin. As the solvent to be dispersed at this time, it is preferable to select a solvent in which the resin fine particles do not swell.

Next, a method for producing the toner of the present invention will be described.
As a method for producing toner particles, a binder resin, a colorant, and other internal additives are melt-kneaded, and after cooling the kneaded product, pulverization and classification are performed. Method to produce, monomer is soluble, polymer obtained is insoluble In dispersion polymerization method to produce toner particles directly using aqueous organic solvent, or direct polymerization in the presence of water-soluble polar polymerization initiator And a production method by an emulsion polymerization method typified by a soap-free polymerization method for producing toner particles. Further, the toner particles obtained by various production methods for controlling the shape of the toner can be spheroidized by any of a mechanical method, a dry method of treating with hot air, and a wet method using a solvent. .

The toner used in the present invention is preferably a toner that contains at least a binder resin, a colorant, and a wax, and has been subjected to surface modification by at least heat treatment.

  When the surface of the toner is modified by heat treatment, in the case of a toner containing a release agent such as wax, the release agent oozes out near the toner surface or on the toner surface. Thereby, the releasability at the time of fixing is good, and the low-temperature fixing property and the offset resistance are improved. Furthermore, by smoothing the fine irregularities on the surface of the toner, segregation and embedding of various fine powders added for the purpose of fluidity and charging stability are suppressed, and the effect is maximized. . Further, the addition amount can be reduced, and stable chargeability can be obtained even under various environments. Various fine powders added to the toner may be added before the heat treatment or after the heat treatment.

  On the other hand, the toner whose surface has been modified by heat treatment may cause the toner particles to coalesce with each other, or the cohesiveness may be increased, resulting in toner aggregation. However, according to the method of the present invention, it is presumed that even if the united toner or aggregate is present in the developer, it floats on the upper surface of the developer reservoir and is preferentially discharged.

A toner manufacturing procedure in the pulverization method will be described.
In the raw material mixing step, a predetermined amount of at least a binder resin, a colorant, and a release agent are weighed and mixed as an internal toner additive. Examples of the mixing device include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, and a Nauter mixer.

  Further, the toner raw materials blended and mixed as described above are melt-kneaded to melt the binder resin, and the colorant and the like are dispersed therein. In the melt-kneading step, for example, a batch kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used. In recent years, single-screw or twin-screw extruders have become mainstream due to the advantage of being capable of continuous production. For example, KTK type twin screw extruder manufactured by Kobe Steel, TEM type twin screw extruder manufactured by Toshiba Machine Co., Ltd. In general, a twin-screw extruder manufactured by Kay Sea Kay, a co-kneader manufactured by Buss, or the like is used. Furthermore, the colored resin composition obtained by melt-kneading the toner raw material is rolled by a two-roll roll after melt-kneading, and then cooled through a cooling step of cooling by water cooling or the like.

In general, the cooled colored resin composition obtained above is then pulverized to a desired particle size in a pulverization step. In the pulverization step, first, coarse pulverization is performed with a crusher, a hammer mill, a feather mill or the like, and further, pulverization is performed with a kryptron system manufactured by Kawasaki Heavy Industries, Ltd., a super rotor manufactured by Nisshin Engineering Co., Ltd. or the like. After that, if necessary, classification is performed using a classifier such as an inertia class elbow jet (manufactured by Nippon Steel & Mining Co., Ltd.), centrifugal class turbo plex (manufactured by Hosokawa Micron Co., Ltd.), and the weight average particle size 3 to 11 μm toner base particles are obtained.

  If necessary, surface modification (spheronization treatment) may be performed in the surface modification step. Examples of the apparatus for spheroidizing the toner include heat treatment apparatuses such as surffusion (manufactured by Nippon Pneumatic Co., Ltd.) for hot-melting the particle surface and spheroidizing apparatus (manufactured by Hosokawa Micron Co., Ltd.). . Alternatively, there are a hybridizer (manufactured by Nara Machinery Co., Ltd.), a turbo mill (manufactured by Turbo Industry Co., Ltd.), a kryptron (manufactured by Kawasaki Heavy Industries Co., Ltd.), a mechano-fusion system (manufactured by Hosokawa Micron Co., Ltd.) and the like.

  In the present invention, a mixed solution prepared by dissolving or dispersing a toner composition containing at least a binder resin, a colorant, and a wax in an organic solvent is suspended and granulated in an aqueous medium. A toner obtained by removing the organic solvent is also preferably used.

A toner production procedure in the dissolution suspension granulation method will be described.
In the dissolution suspension granulation method, monomers are polymerized in advance, and the polymerization temperature and polymerization time are adjusted so that a desired molecular weight distribution is obtained. After adding magnetic metal fine particles, release agent, colorant, polymerizable monomer and polymerization initiator to this, it is suspended by applying mechanical shear force in the presence of inorganic or organic dispersant. After that, the toner particles are formed by obtaining polymer particles by applying thermal energy while applying stirring shear.

  When the toner and the magnetic carrier are mixed and used as a two-component developer in the developing device, the mixing ratio of the toner and the magnetic carrier is 2 to 15% by mass as the toner concentration in the developer, preferably When it is 4 to 13% by mass, good results are usually obtained. If the toner concentration is less than 2% by mass, the image density tends to decrease, and if it exceeds 15% by mass, fogging or in-machine scattering tends to occur.

In the present invention, when adjusting the replenishment developer, a predetermined amount of toner and magnetic carrier are weighed and mixed in a mixer. The mixing ratio (mass ratio) of toner and magnetic carrier in the replenishment developer is as described above. Examples of the mixing device include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, and a Nauter mixer. Among these, the V-type mixer is preferable in consideration of the dispersibility of the magnetic carrier and the charge rising of the toner.

The image forming method of the present invention will be described in detail.
An example of a simultaneous development cleaning method using the image forming method of the present invention is shown in FIG. In FIG. 1, an electrophotographic photosensitive member 1 serving as an electrostatic latent image carrier rotates in the b direction. The photosensitive member 1 is charged by a charging device 2 as a charging unit, and a laser beam L is projected onto the charged surface of the photosensitive member 1 by an exposure device 3 as an electrostatic latent image forming unit to form an electrostatic latent image. . Thereafter, the electrostatic latent image is visualized as a toner image by the developing device 4 that is a developing unit, and is transferred to the transfer material P by the transfer device 5 that is a transfer unit. In this transfer unit, the untransferred toner remaining on the surface of the photosensitive member without being transferred passes through the above-described charging unit and electrostatic latent image forming unit, and is again used for development or collected by the developing device.

Here, each step of the image forming method of the present invention will be described in more detail.
The charging step is not particularly limited as long as it is a means for charging the surface of the photoconductor to charge the electrophotographic photoconductor. As the charging means, a device for charging the electrophotographic photosensitive member without contact with the electrophotographic photosensitive member, such as a corona charging means, or an electrophotographic photosensitive member by contacting a conductive roller or blade with the electrophotographic photosensitive member. Devices that charge the body can be used.

  In the present invention, the contact charging method is preferable from the viewpoint of the charged product. Corona discharge, which is a conventional non-contact charging method, generates a large amount of ozone that reacts with nitrogen in the air to form nitrogen oxides (NOx), and these nitrogen oxides react with moisture in the air to form nitric acid. It adheres to the surface of the photoreceptor and tends to reduce the resistance of the surface of the photoreceptor. On the other hand, in the contact charging method, the amount of ozone generated is remarkably small, and the change in the resistance of the photoreceptor surface due to the charged product is small. Further, the contact charging method is more preferable because the charged product that causes the image flow can be efficiently removed by the polishing action of the inorganic fine particles contained in the transfer residual toner in the contact area with the photoreceptor.

  The contact charging method includes a discharge charging mechanism such as a roller charging method and a direct injection charging mechanism such as a magnetic brush charging method.

  The discharge charging mechanism is a mechanism in which the surface of the member to be charged is charged by a discharge phenomenon that occurs in the gap between the contact charging member and the member to be charged. Since the discharge charging system has a constant discharge threshold value for the contact charging member and the member to be charged, it is necessary to apply a voltage larger than the potential of the member to be charged to the contact charging member. In addition, the amount of generation is much smaller than that of a corona charger, but in principle, a charged product is generated.

As a contact charging member by discharge, a roller charging method (roller charging device) using a conductive roller (charging roller) is preferable in terms of discharge stability and is widely used. The discharge charging roller may be formed in a roller shape using a conductive or medium resistance rubber material or foam as a base layer, and the surface thereof may be made of a high resistance layer. In this configuration, the discharge phenomenon occurs in a gap of several tens of μm that is slightly away from the contact portion between the roller and the member to be charged. Therefore, in order to stabilize the discharge phenomenon, a layer on the roller surface (hereinafter referred to as a surface layer) is flat, has an average surface roughness Ra of 1.0 μm or less, and has a surface with high roller hardness. Preferably it is. In addition, the roller charging due to the discharge has a high applied voltage, and if there is a pinhole (exposed substrate due to damage to the film to be charged), a voltage drop and a charging failure are likely to occur around it. Accordingly, the surface resistance of the surface layer is preferably 10 ¹¹ Ω or more from the viewpoint of preventing a voltage drop.

  The direct injection charging mechanism is a charging mechanism that charges (charges) the surface of a member to be charged by directly transferring and receiving charges by contacting the contact charging member and the member to be charged at the molecular level. It is also called direct charging or injection charging.

  As the contact charging member by injection, a magnetic brush charging method (magnetic brush charging device) using a magnetic brush is preferably used. The magnetic brush charging uses a member having a magnetic brush portion formed in a brush shape by magnetically constraining conductive magnetic particles with a magnet roll or the like as a contact charging member, and the magnetic brush portion is contacted with a photosensitive member as a charged body. Then, a predetermined charging bias is applied to charge the photoreceptor surface to a predetermined polarity and potential.

  It is preferable to perform direct injection charging uniformly by using particles having an average particle diameter of 5 to 50 μm on a number basis as the conductive magnetic particles constituting the magnetic brush portion and providing a sufficient speed difference from the photoreceptor. Magnetic brush charging also has problems such as complicated equipment configuration and conductive magnetic particles constituting the magnetic brush portion falling off and adhering to the photoreceptor.

  The average particle size of the conductive magnetic particles is determined by randomly extracting 300 or more conductive magnetic particles having a particle size of 0.1 μm or more with a scanning electron microscope (100 to 5000 times), and using a digitizer as a particle size with a horizontal ferret diameter. Measure and calculate the number average particle diameter of the conductive magnetic particles.

In the direct injection charging mechanism, the potential difference between the contact charging member and the member to be charged is about several volts to several tens of volts. The charging potential is equal to the applied voltage, and there is no voltage difference that causes discharge. In addition, the voltage required for charging can be kept low. Since this direct charging system does not involve the generation of ions, no adverse effects caused by the discharge products occur. That is, it is a charging method that is excellent in terms of low power without generating ozone.

  As the mechanism of the contact charging method, the above two methods can be mentioned, but neither of them generates a large amount of ozone in the conventional non-contact charging method using corona discharge, from the viewpoint of suppression of charged products and low power. Preferably used.

  In the electrostatic latent image forming step, a known exposure apparatus can be used as the exposure means. For example, a semiconductor laser or a light emitting diode is used as the light source, and a scanning optical system unit including a polygon mirror, a lens, and a mirror can be used.

In the development process, a two-component development method is used.
As a two-component developing method, a magnetic brush of a two-component developer having toner and a magnetic carrier is formed on a developer carrier (developing sleeve) containing a magnet, and the magnetic brush is used as a developer layer thickness regulating member. After coating to a predetermined layer thickness, the film is transported to a developing area facing the photoconductor, where the magnetic brush is exposed to light while applying a predetermined developing bias between the photoconductor and the developing sleeve. In this method, the electrostatic latent image is visualized as a toner image by being brought close to or in contact with the body surface.

  As described above, by bringing the magnetic brush close to or in contact with the surface of the photoconductor, the deposits on the surface of the photoconductor can be reduced, and the surface of the photoconductor can be reduced by the inorganic fine particles contained in the toner. This is preferably used because it can effectively remove the deposits.

  Magnetic carriers that can be used in such two-component developers include conventional iron powder carriers, ferrite carriers, magnetic fine particle dispersed resin carriers in which magnetic fine particles are dispersed in a binder resin, and porous magnetic materials impregnated with resin. Resin impregnated carriers and the like. In the iron powder carrier, since the specific resistance of the carrier itself is low, the charge of the electrostatic latent image leaks through the carrier, and the electrostatic latent image may be disturbed, thereby causing an image defect. Also, in the ferrite carrier, although the specific resistance of the carrier itself is relatively high, the magnetic brush tends to be stiff due to the large saturation magnetization, and the magnetic brush has uneven spots on the toner image. There is. For this reason, a magnetic fine particle-dispersed resin carrier in which magnetic fine particles are dispersed in a binder resin and a resin-impregnated carrier in which a porous magnetic material is impregnated with a resin are preferably used. The magnetic fine particle-dispersed resin carrier and the resin-impregnated carrier have a relatively higher specific resistance than that of a ferrite carrier, a smaller saturation magnetization, and a smaller true specific gravity. Also, since the magnetic brush does not become rigid, it is preferable in that a good toner image can be formed without image defects and unevenness in the stitches.

  In the transfer process, the toner image on the surface of the photoconductor is transferred to the transfer material without contact with the photoconductor, such as corona transfer means, or a roller or an endless belt-shaped transfer member is brought into contact with the photoconductor. There are methods for transferring a toner image on the body surface onto a transfer material, and any method can be used.

  In the present invention, as in the charging step, a contact-type transfer roller, a resin belt, or an elastic belt-like transfer member is used from the viewpoint of no generation of a large amount of ozone, suppression of charged products, and low power. Preferably used.

Further, in the image forming method of the present invention, as shown in FIG. 2, the transfer residual toner on the photoconductor is leveled after the transfer and before the charging step, thereby improving the recovery rate of the transfer residual toner during development. To make
That is, it is preferable to further include a leveling step 6 having a bias applying means for the purpose of uniformizing the charging polarity of the transfer residual toner.

  In the leveling step 6, when the toner is negatively charged, it is preferable to apply a bias for negatively charging the transfer residual toner to reduce adhesion of the transfer residual toner to the charging member in the charging step. This improves the recovery rate of the transfer residual toner during development. Further, as the leveling member, a brush-like member is preferably used. Furthermore, it is preferable to provide a plurality of such leveling members because the transfer residual toner adheres to the charging member and the recovery rate of the transfer residual toner during development increases.

  Hereinafter, methods for analyzing and measuring other physical properties related to the present invention will be described.

<Measurement of toner particle size distribution>
As a measuring device, Coulter Counter TA-II or Coulter Multisizer II (manufactured by Coulter Inc.) is used. As the electrolytic solution, an about 1% NaCl aqueous solution is used. As the electrolytic solution, an electrolytic solution prepared using primary sodium chloride or, for example, ISOTON (registered trademark) -II (manufactured by Coulter Scientific Japan) can be used.

  As a measurement method, 0.1 to 5 ml of a surfactant (preferably alkylbenzenesulfone hydrochloride) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is dispersed for about 1 to 3 minutes with an ultrasonic disperser, and the volume and number of the sample are measured for each channel by the measuring apparatus using a 100 μm aperture as the aperture. Volume distribution and number distribution are calculated. From these obtained distributions, the weight average particle diameter (D4) of the sample is determined. As channels, 2.00 to 2.52 μm; 2.52 to 3.17 μm; 3.17 to 4.00 μm; 4.00 to 5.04 μm; 5.04 to 6.35 μm; 6.35 to 8. 00 μm; 8.00 to 10.08 μm; 10.08 to 12.70 μm; 12.70 to 16.00 μm; 16.00 to 20.20 μm; 20.20 to 25.40 μm; 25.40 to 32.00 μm; 13 channels of 32.00-40.30 μm are used.

<Measurement of average circularity of toner>
The equivalent circle diameter, circularity, and frequency distribution of the toner are used as a simple method for quantitatively expressing the shape of the toner particles. In the present invention, the flow type particle image measuring apparatus “FPIA-2100 type” is used. ”(Manufactured by Sysmex Corporation), and calculation is performed using the following formulas (1) to (2).
(1): equivalent circle diameter = (particle projected area / π) ^1/2 × 2
(2): Circularity = (perimeter of a circle having the same area as the particle projection area) / (perimeter of the particle projection image)

Here, the “particle projected area” is the area of the binarized toner particle image, and the “peripheral length of the particle projected image” is the length of the contour line obtained by connecting the edge points of the toner particle image. Define.
In the present invention, the circularity is an index indicating the degree of unevenness of the toner particles, and is 1.000 when the toner particles are completely spherical. The more complicated the surface shape, the smaller the circularity.
The average circularity C, which means the average value of the circularity frequency distribution, is calculated from the following equation (3), where the circularity (center value) at the division point i of the particle size distribution is ci and the frequency is fci. .

  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 Co., Ltd.) is used, and dispersion treatment is performed for 2 minutes to obtain a dispersion for measurement. 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 the toner particles, the flow type particle image measuring device is used, and the concentration of the dispersion is readjusted so that the color toner particle concentration at the time of measurement is 3000 to 10,000 particles / μl. Measure more than one. After the measurement, this data is used to cut data less than 2 μm, and the average circularity of the toner particles is obtained.

<Measurement of molecular weight by GPC (toner)>
The molecular weight of the chromatogram by gel permeation chromatograph (GPC) is measured under the following conditions.
Resin with stabilized column in a heat chamber at 40 ° C., tetrahydrofuran (THF) as a solvent was allowed to flow through the column at this temperature at a flow rate of 1 ml / min, and the sample concentration was adjusted to 0.05 to 0.60% by mass. Measurement is performed by injecting 50 to 200 μl of a THF sample solution. An RI (refractive index) detector is used as the detector. As a column, in order to accurately measure a molecular weight region of 10 ^{3 to} 2 × 10 ⁶ , it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, μ-styragel 500, 103, 104, 105 manufactured by Waters And combinations of shodex KA-801, 802, 803, 804, 805, 806, and 807 manufactured by Showa Denko KK are preferable.

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 number of counts. As a standard polystyrene sample for preparing a calibration curve, for example, Pressure Chemical
Co. Manufactured by Toyo Soda Kogyo Co., Ltd., with molecular weights of 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ ,
It is appropriate to use 1.1 × 10 ⁵ , 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ , and use at least about 10 standard polystyrene samples. It is.

<Measurement of maximum endothermic peak of wax>
The maximum endothermic peak of the wax and toner can be measured according to ASTM D3418-82 using a differential scanning calorimeter (DSC measuring device) and DSC2920 (TA Instruments Japan).

  As a measuring method, 5 to 20 mg, preferably 10 mg of a measurement sample is accurately weighed. This is put in an aluminum pan, and an empty aluminum pan is used as a reference, and measurement is performed at a temperature rising rate of 10 ° C./min and normal temperature and normal humidity within a measurement temperature range of 30 to 200 ° C. In this temperature raising process, an endothermic peak in the temperature range of 30 to 200 ° C. is obtained. When there are a plurality of peaks, the highest endothermic peak is the one having the highest height from the baseline in the region above the endothermic peak due to the resin.

<Carrier particle size distribution and circularity>
The particle size distribution and average circularity of the carrier are preferably volume-based average circularity. The volume-based average circularity is measured as follows using a multi-image analyzer (manufactured by Beckman Coulter).

A solution obtained by mixing about 1% NaCl aqueous solution and glycerin at 50% by volume: 50% by volume is used as the electrolytic solution. Here, the NaCl aqueous solution may be prepared using primary sodium chloride, and may be, for example, ISOTON (registered trademark) -II (manufactured by Coulter Scientific Japan). Glycerin may be a special grade or first grade reagent.
To the electrolytic solution (about 30 ml), 0.1 to 1.0 ml of a surfactant (preferably alkylbenzenesulfone hydrochloride) is added as a dispersant, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is dispersed for about 1 minute with an ultrasonic disperser to obtain a dispersion.
Using a 200 μm aperture and a 20 × lens as the aperture, the equivalent circle diameter and circularity are calculated under the following measurement conditions.
Average luminance within measurement frame: 220 to 230, measurement frame setting: 300, SH (threshold): 50, binary level: 180
The electrolytic solution and the dispersion liquid are put into a glass measuring container, and the concentration of carrier particles in the measuring container is set to 5 to 10% by volume. Stir the contents of the glass measuring container at the maximum stirring speed. The sample suction pressure is 10 kPa. When the carrier specific gravity is large and the sedimentation is likely to occur, the measurement time is 15 to 30 minutes. Further, the measurement is interrupted every 5 to 10 minutes to replenish the sample solution and the electrolytic solution-glycerin mixed solution.

The number of measurements is 2000. After the measurement is finished, the main body software removes a defocused image, aggregated particles (multiple simultaneous measurements), etc. on the particle image screen.
The circularity and equivalent circle diameter of the carrier are calculated by the following formulas (4) and (5).

Circularity = (4 × Area) / (MaxLength ² × π) (4)
Equivalent circle diameter = √4 · Area / π (5)

  Here, “Area” is the projected area of the binarized carrier particle image, and “MaxLength” is defined as the maximum diameter of the carrier particle image. The equivalent circle diameter is represented by the diameter of a perfect circle when “Area” is the area of the perfect circle. The equivalent circle diameter is divided into 4 to 100 μm in 256, and is used by logarithmically displaying on a volume basis. Using this, the 50% particle size (D50) based on volume distribution is obtained.

<True specific gravity of carrier>
The true specific gravity of the carrier particles of the present invention can be measured based on a gas phase substitution method using a dry automatic densimeter autopycnometer (manufactured by Yuasa Ionics).

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

<Example of manufacturing magnetic carrier>
(Example of manufacturing magnetic carrier 1)
MnO and 28.5mol%, MgO and 3.1 mol%, _Fe 2 _{O 3} the 67.5Mol% and SrCO ₃ to 5 hours triturated with 0.9 mol% wet ball mill, and mixed, dried, 3 at 900 ° C. Temporary firing was performed after holding the time. This was pulverized with a wet ball mill for 7 hours to 2 μm or less. To this slurry, 3.0% by weight of binder (polyvinyl alcohol) was added, and then granulated and dried with a spray dryer to obtain a granulated product having a volume average particle size (D50) of about 40 μm. This granulated product was put in an electric furnace, and held at 1100 ° C. for 3 hours in a mixed gas in which the oxygen concentration in nitrogen gas was adjusted to 2.0 vol%, followed by firing. Thereafter, it was crushed and further sieved to obtain a magnetic carrier core A having a volume average particle size of 40 μm. When this core surface was observed with an SEM, grooves were found on the core surface.

Straight silicone (KR255 (solid content conversion) manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts by mass Silane coupling agent (γ-aminopropylethoxysilane) 10 parts by mass Carbon black (number average particle size 30 nm, DBP oil absorption 50 ml / 100 g)
10 parts by mass The above components were mixed with 300 parts by mass of xylene to obtain a magnetic carrier resin coating solution. While stirring using a fluidized bed heated to 70 ° C. using this resin coating solution, a general application using a fluidized bed and a magnetic carrier core A so as to be 13.0% by mass based on the straight silicone resin and Solvent removal operation such as heating was performed. Furthermore, the magnetic carrier 1 was obtained by performing a treatment for 2.5 hours at 230 ° C. using an oven, crushing, and classifying with a sieve. Table 1 shows the physical properties of the obtained magnetic carrier.

(Example of manufacturing magnetic carriers 2 and 3)
Magnetic carriers 2 and 3 were obtained in the same manner as magnetic carrier 1 except that the amount of the coating resin for coating the magnetic carrier was changed from 13.0% by mass to 18.0% by mass and 7.0% by mass, respectively. Table 1 shows the physical properties of the obtained magnetic carrier.

(Example of manufacturing magnetic carrier 4)
A magnetic carrier core B was obtained in the same manner as the magnetic carrier core A except that the temperature of the main firing was changed from 1100 ° C. to 1400 ° C. When this core surface was observed by SEM, there were few grooves on the core surface, and the surface property was smoother than that of the magnetic carrier core A.
A magnetic carrier 4 was obtained in the same manner as the magnetic carrier 1 except that the magnetic carrier core B was used. Table 1 shows the physical properties of the obtained magnetic carrier.

(Example of manufacturing magnetic carrier 5)
4.0 mass% silane coupling agent (3%) with respect to the magnetite powder having a number average particle size of 0.30 μm and (magnetization strength of 75 Am ² / kg under a magnetic field of 10,000 / 4π (kA / m)) -(2-aminoethylaminopropyl) trimethoxysilane) was added, and the mixture was stirred and mixed at a high speed at 100 ° C. or higher in the container to treat the fine particles.

・ Phenol 13 parts ・ Formaldehyde solution 6 parts (formaldehyde 40%, methanol 10%, water 50%)
-Treated magnetite 81 parts by mass The above material, 5% by mass of 28% ammonia water, and 20 parts by mass of water are placed in a flask, and the temperature is raised and maintained at 85 ° C. for 30 minutes while stirring and mixing, and polymerized for 3 hours. The resulting phenolic resin was cured. Thereafter, the cured phenol resin was cooled to 30 ° C., water was further added, the supernatant was removed, the precipitate was washed with water, and then air-dried. Subsequently, this was dried under reduced pressure (5 mmHg or less) at a temperature of 60 ° C. to obtain a spherical magnetic material-dispersed resin carrier core C in which a magnetic material was dispersed.

As a coating material, a copolymer of methyl methacrylate and perfluorooctyl acrylate (copolymerization ratio (mass% ratio) 8: 2, weight average molecular weight 45,000) is used, and this is the magnetic material dispersed resin carrier core C at the time of coating. A carrier coat solution containing 10% by mass of a copolymer of methyl methacrylate and perfluorooctyl acrylate was prepared using a mixed solvent of methyl ethyl ketone and toluene as a solvent so as to be 1 part by mass with respect to 100 parts by mass. In addition, 0.5 parts by mass of melamine resin (number average particle size 0.2 μm) and 1.0 part by mass of carbon black (number average particle size 30 nm, DBP oil absorption 50 ml / 100 g) may be added to the carrier coat solution using a homogenizer. Mix. Next, the magnetic material-dispersed resin carrier core C is added to the mixed solution, and a solvent is volatilized at 70 ° C. while continuously applying a shear stress to the mixed solution. Copolymers with perfluorooctyl acrylate were coated.

The resin-coated magnetic material-dispersed resin carrier core C coated with a copolymer of methyl methacrylate and perfluorooctyl acrylate is heat-treated by stirring at 100 ° C. for 2 hours, and then cooled and crushed. Classification was performed to obtain a magnetic carrier 5 having a number average particle diameter of 29 μm, a true specific gravity of 2.8 g / cm ³ and an average circularity of 0.916. Table 1 shows the physical properties of the magnetic carrier 5 obtained.

(Example of manufacturing magnetic carrier 6)
A magnetic material dispersed resin carrier core D was obtained in the same manner as the magnetic material dispersed resin carrier core C except that the following raw material composition was changed.
・ Phenol 20 parts by mass ・ Formaldehyde solution 10 parts by mass (formaldehyde 40%, methanol 10%, water 50%)
-Treated magnetite 70 parts by mass Further, a magnetic carrier 6 was obtained in the same manner as the magnetic carrier 5 except that the magnetic material-dispersed resin carrier core D was used. Table 1 shows the physical properties of the magnetic carrier 6 obtained.

(Example of manufacturing magnetic carrier 7)
A mixture of Fe ₂ O ₃ ; 80 mol%, MnO; 4.0 mol%, MgO; 16 mol% was mixed for 10 hours using a ball mill. The obtained mixture was calcined at 800 ° C. for 2 hours, and the calcined mixture was pulverized with a ball mill. The average particle size of the obtained pulverized product was 0.2 μm.
Water (300% by mass with respect to the pulverized product), polyvinyl alcohol (10% by mass with respect to the pulverized product) and CaCO ₃ (5% by mass with respect to the pulverized product) are added to the obtained pulverized product, and further a spray dryer. Was granulated. The granulated material was sintered at 980 ° C. for 10 hours, then pulverized and further classified to obtain Mn—Mg ferrite carrier core E. The average particle diameter (D50) of this Mn—Mg ferrite carrier core E was 44 μm.

  T unit in which all organic groups are methyl groups: 12 parts by mass of siloxane formulated so that D units in which all organic groups are methyl groups = 85: 15, and 0.3 parts by mass of γ-aminopropyltrimethoxysilane, A mixed liquid of 200 parts by mass of toluene was added to 100 parts by mass of the carrier core E, and the solvent was removed by drying under reduced pressure while stirring and mixing with a solution vacuum kneader. The obtained particles were baked at 140 ° C. for 2 hours to obtain a magnetic carrier 7. Table 1 shows the physical properties of the magnetic carrier 7 obtained.

Next, the toner used in the present invention will be described.
<Example of binder resin production>
(Example of hybrid resin production)
As a vinyl copolymer, 2.00 mol of styrene, 0.23 mol of 2-ethylhexyl acrylate, 0.15 mol of fumaric acid, 0.02 mol of dimer of α-methylstyrene, and 0.07 mol of dicumyl peroxide are put into a dropping funnel. . In addition, 7.0 mol of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane; 0 mol, 3.0 mol of terephthalic acid, 1.5 mol of trimellitic anhydride, 5.0 mol of fumaric acid and 0.2 g of dibutyltin oxide are placed in a 4-liter four-necked flask made of glass, a thermometer, a stirring rod, a condenser and nitrogen The introduction tube was installed and placed in a mantle heater. Next, after the inside of the flask was replaced with nitrogen gas, the temperature was gradually increased while stirring, and while stirring at a temperature of 145 ° C., the monomer of the vinyl resin, the crosslinking agent and the polymerization initiator were added from the previous dropping funnel. It was dripped over 4 hours. Next, the temperature was raised to 200 ° C. and reacted for 4 hours to obtain a hybrid resin (Mw: 3.1 × 10 ⁴ , Mn: 2.9 × 10 ³ ).

<Example of toner production>
(Production example of toner 1)
・ Hybrid resin 100 parts by mass ・ Wax (normal olefin, DSC peak temperature: 76 ° C., Mn: 580)
5 parts by mass · 1,4-di-t-butylsalicylic acid aluminum compound 1 part by mass · Cyan pigment (Pigment Blue 15: 3) 5 parts by mass Preliminarily mixed with a Henschel mixer with the above formulation, twin screw extrusion kneader The material temperature was melt-kneaded at 130 ° C., cooled, and roughly crushed to about 1 to 2 mm using a hammer mill, and then finely pulverized to a particle size of 15 μm or less by an air jet type pulverizer. Further, the obtained finely pulverized product was classified by an inertia class elbow jet, and then subjected to spheronization treatment at 170 ° C. with a hot air spheronizer (manufactured by Hosokawa Micron Corporation), with an average circularity of 0.965 and a weight average Toner particles 1 (Mw: 3.6 × 10 ⁴ , Mn: 3.1 × 10 ³ ) having a particle diameter (D4) of 5.5 μm were obtained.

To 100 parts by mass of the toner particles 1, 1.0% by mass of acicular titanium oxide fine powder (BET specific surface area = 62 m ² / g, treated with 10% by mass of isobutylsilane coupling agent) was externally added by a Henschel mixer. Thus, Toner 1 was obtained. Table 2 shows the physical properties of the obtained toner.

(Production example of toner 2)
Toner particles 2 having an average circularity of 0.982 and a weight average particle diameter (D4) of 5.7 μm were obtained in the same manner as toner 1 except that the temperature condition of the spheroidizing treatment was changed to 190 ° C.
Toner 2 is obtained by externally adding 1.0% by mass of acicular titanium oxide fine powder (BET = 62, isobutylsilane coupling agent 10% by mass treatment) to 100 parts by mass of toner particle 2 using a Henschel mixer. . Table 2 shows the physical properties of the obtained toner.

(Production example of toner 3)
In the toner 1 production example, instead of using a hot-air spheronizer, a mechanofusion system (manufactured by Hosokawa Micron Corporation) is used to perform spheronization by mechanical impact treatment, with an average circularity of 0.954 and a weight average particle size. In (D4), 5.4 μm toner particles 3 were obtained.
Toner 3 is obtained by externally adding 1.0% by mass of acicular titanium oxide fine powder (BET = 62, isobutylsilane coupling agent 10% by mass treatment) to 100 parts by mass of toner particle 3 using a Henschel mixer. . Table 2 shows the physical properties of the obtained toner.

(Production example of toner 4)
Into a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, 720 parts by mass of bisphenol A ethylene oxide 2-mole adduct, 270 parts by mass of isophthalic acid and 2 parts by mass of dibutyltin oxide were added. The reaction was continued for 5 hours at a reduced pressure of 10 to 15 mmHg, followed by cooling to 160 ° C., and 31 parts by mass of phthalic anhydride was added thereto and reacted for 2 hours. Subsequently, it cooled to 80 degreeC and reacted with 188 mass parts of isophorone diisocyanate in ethyl acetate for 2 hours, and the polyester prepolymer (A) which has an isocyanate group was obtained.
Next, 270 parts by mass of prepolymer (A) and 15 parts by mass of isophoronediamine were reacted at 50 ° C. for 2 hours to obtain a urea-modified polyester resin (i) having a weight average molecular weight of 65,000.
In the same manner as above, 724 parts by mass of bisphenol A ethylene oxide 2-mole adduct and 276 parts by mass of terephthalic acid were subjected to polycondensation at 230 ° C. for 8 hours under normal pressure, and then reacted for 5 hours at a reduced pressure of 10 to 15 mmHg. A polyester (a) which was not modified was obtained.
200 parts by mass of urea-modified polyester resin (i) and 800 parts by mass of unmodified polyester (a) are dissolved and mixed in 2000 parts of a mixed solvent of ethyl acetate / MEK (1/1), and acetic acid in the toner binder (1). An ethyl / MEK solution was obtained. Part of the mixture was dried under reduced pressure to isolate toner binder (1).

In a beaker, 240 parts by mass of the ethyl acetate / MEK solution of the toner binder (1), 20 parts of pentaerythritol tetrabehenate (melting point: 81 ° C., melt viscosity: 25 mpa · s), C.I. I. Pigment Blue 15: 3 raw pigment (5 parts by mass) was added, stirred at 12000 rpm with a TK homomixer at 60 ° C., and uniformly dissolved and dispersed to obtain a toner material solution.
In another beaker, 706 parts by mass of ion-exchanged water, 294 parts by mass of hydroxyapatite 10% suspension (Superite 10 manufactured by Nippon Chemical Industry Co., Ltd.), and 0.2 parts by mass of sodium dodecylbenzenesulfonate were uniformly dissolved. . Next, the temperature was raised to 60 ° C., and the toner material solution was added and stirred for 10 minutes while stirring at 12000 rpm with a TK homomixer. The mixture was then transferred to a Kolben equipped with a stirrer and a thermometer, and the temperature was raised to 98 ° C. to remove the solvent, followed by filtration, washing, drying, air classification, average circularity of 0.986, and weight average Toner particles 4 (Mw: 8.4 × 10 ³ , Mn: 3.2 × 10 ³ ) with a particle size (D4) of 5.6 μm were obtained.

  Toner 4 is obtained by externally adding 1.0% by mass of acicular titanium oxide fine powder (BET = 62, isobutylsilane coupling agent 10% by mass treatment) to 100 parts by mass of toner particle 4 using a Henschel mixer. . Table 2 shows the physical properties of the obtained toner.

(Production example of toner 5)
・ Styrene-n-butyl acrylate copolymer resin (copolymerization ratio 80:20, Mw 14,000) 50 parts by massStyrene-n-butyl acrylate copolymer resin (copolymerization ratio 80:20, Mw 300,000) 50 parts by mass・ C. I. Pigment blue 15: 3 5 parts by mass Fischer-Tropsch wax having a melting point of 105 ° C. 2.5 parts by mass, paraffin wax having a melting point of 78 ° C. 2 parts by mass Preliminarily mixed with a Henschel mixer in the above formulation, and using a twin screw extruder kneader The material temperature was melt-kneaded at 150 ° C., and after cooling, coarsely pulverized to about 1 to 2 mm using a hammer mill, and then finely pulverized to a particle size of 15 μm or less with an air jet type pulverizer. Further, the obtained finely pulverized product was classified by an inertia classification type elbow jet, and then subjected to spheronization treatment at 240 ° C. by a hot air spheronizer (manufactured by Hosokawa Micron Corporation), with an average circularity of 0.995 and a weight average Toner particles 5 having a particle diameter (D4) of 6.2 μm (Mw: 2.1 × 10 ⁵ , Mp: 1.2 × 10 ⁴ ) were obtained.
Toner 5 is obtained by externally adding 1.0% by mass of acicular titanium oxide fine powder (BET = 62, treatment with 10% by mass of isobutylsilane coupling agent) to 100 parts by mass of toner particle 5 using a Henschel mixer. . Table 2 shows the physical properties of the obtained toner.

(Production example of toner 6)
In the toner 5 production example, instead of using a hot-air spheronizer, a mechano-fusion system (manufactured by Hosokawa Micron) is used to perform spheronization by mechanical impact treatment, with an average circularity of 0.951 and a weight average particle size. (D4) gave toner particles 6 of 5.8 μm.
Toner 6 is obtained by externally adding 1.0% by mass of acicular titanium oxide fine powder (BET = 62, treated with 10% by mass of isobutylsilane coupling agent) to 100 parts by mass of the toner particles 6 using a Henschel mixer. . Table 2 shows the physical properties of the obtained toner.

(Production example of toner 7)
In the production example of the toner 1, toner particles 7 having an average circularity of 0.920 and a weight average particle diameter (D4) of 5.9 μm were obtained in the same manner as the toner 1 except that the spheroidizing treatment was not performed. .
Toner 7 is obtained by externally adding 1.0% by mass of acicular titanium oxide fine powder (BET = 62, treatment with 10% by mass of isobutylsilane coupling agent) to 100 parts by mass of toner particle 7 using a Henschel mixer. . Table 2 shows the physical properties of the obtained toner.

<Example 1>
A developer 1 was prepared by adding 93 parts by mass of magnetic carrier 1 and 7 parts by mass of toner 1 and mixing them with a V-type mixer. On the other hand, 15 parts by mass of magnetic carrier 1 and 85 parts by mass of toner 1 were added and mixed with a V-type mixer to obtain replenishment developer 1.

The obtained developer 1 and replenishment developer 1 are converted to Canon full color copier iRC3200 (provided with a developer discharge port inside the developer so that excess developer can be discharged to the outside) The development contrast was adjusted so that the initial image density was 1.40 in each environment, and image output evaluation was performed in a single color mode. The image density is measured by the method described later.
As an evaluation mode, an original document with an image area of 5% is first used using A4 paper (CLC80g paper, manufactured by Canon Sales) in a normal temperature and low humidity environment (N / L) (23 ° C./5% RH). A durability test of 50,000 sheets was conducted. Thereafter, the evaluation machine is placed under a high-temperature and high-humidity environment (H / H) (30.
0 ° C./80% RH), and an endurance test of 50,000 sheets was performed using an original document having an image area of 20% using A4 paper (CLC 80 g paper, manufactured by Canon Sales Co., Ltd.).
Similarly, under normal temperature and humidity (N / N) (23 ° C., 50% RH), A4 paper (CLC)
A durability test of 200,000 sheets was performed using an original document having an image area of 5% using 80 g paper (manufactured by Canon Sales Co., Ltd.).
Table 4 shows the respective measurement conditions and evaluation criteria, and the obtained evaluation results (1) to (5).

(1) Fusion and filming After the image output in a high-temperature and high-humidity environment is completed, a 30H image is formed, the image and the surface of the photoreceptor are visually observed, and the reproducibility of the solid uniformity of the image. Was evaluated with the following indicators. Note that the 30H image is a halftone image when 256 gradations are displayed in hexadecimal, 00H is solid white, and FFH is solid.
A: There are no streaks or unevenness on the image, and there is no fusion or filming on the surface of the photoreceptor.
B: There are no streaks or unevenness, but slight fusing and filming are observed on the surface of the photoreceptor.
C: Slight streaks / unevenness is observed, and fusion and filming are observed on the surface of the photosensitive member (lower limit for practical use).
D: There are many streaks and irregularities, and remarkable fusion and filming of the photoreceptor surface are observed (impractical level).

(2) Durability and stability After image output under normal temperature and low humidity environment and high temperature and high humidity environment, measure the density of solid image (initial density: 1.40), respectively. Was calculated. This density difference was used as an index of the durability stability of the toner. The image density was measured with the above-described X-Rite color reflection densitometer (X-rite 500 Series, manufactured by X-rite), and an average value of 6 points was used.
A: Very good (less than 0.08)
B: Good (0.08 or more, less than 0.15)
C: Normal (0.15 or more, less than 0.25)
D: Bad (over 0.25)

(3) Transfer efficiency In a normal temperature and normal humidity environment, the potential contrast of the photoconductor is adjusted so that the amount of applied toner on the photoconductor is 0.55 mg / cm ² after the initial and image output. The image density of the image transferred on the transfer paper and the transfer residual image on the photosensitive member were measured using an X-Rite color reflection densitometer.
In the measurement, the transfer residual toner of the image on the transfer paper and the image portion on the photosensitive member was collected using a polyester tape (manufactured by Nichiban Co., Ltd.), and the image density of the tape stuck on the paper was measured. From the obtained image density, the loading amount of the developer on the transfer paper and the photoconductor was converted to obtain the transfer efficiency onto the transfer paper. The transfer current used was adjusted to maximize transfer efficiency. D1 is the image density obtained by taping the remaining transfer portion of the photoreceptor and sticking it on the paper, and D2 is the image density obtained by taping on the developer transferred onto the paper and sticking it on the paper. Efficiency was calculated.
Transfer efficiency (%) = D2 / (D1 + D2) × 100
The obtained transfer efficiency was evaluated based on the following evaluation criteria.
A: Very good (transfer efficiency 94% or more)
B: Good (transfer efficiency 90% or more, less than 94%)
C: Normal (transfer efficiency 85% or more, less than 90%)
D: Poor (transfer efficiency less than 85%)

(4) Dot reproducibility Initially and after image output is completed in a room temperature and humidity environment, a 30H image is formed, and this image is visually observed. The dot reproducibility of the image is evaluated based on the following criteria. did.
A: Smooth and smooth.
B: I don't feel a lot of rustling.
C: Although there is a slight feeling of roughness, it is at a level where there is no practical problem.
D: There is a feeling of roughness and is a problem.

(5) Fog After the image output in the initial stage, room temperature and low humidity environment, and high temperature and high humidity environment was finished, the image was left for 3 days, and then fog was confirmed. The whiteness of each of the paper on which the solid white image was output and the same unused white paper was measured, and the fog was calculated from the difference in whiteness. The whiteness is a reflectometer equipped with a color filter (“REFLECTOMETER made by Tokyo Denshoku Co., Ltd.).
MODEL TC-6DS "), and an average value of 6 points was used.
A: Very good (less than 1.0%)
B: Good (1.0% or more and less than 2.0%)
C: Normal (2.0% or more, less than 3.5%)
D: Poor (3.5% or more)

<Examples 2 to 8, Reference Example 9 > and <Comparative Examples 1 to 5>
(1) Same as Example 1 with the combination and mass ratio of magnetic carrier and toner shown in Table 3
Evaluation of (5) was performed.
Table 4 shows the evaluation results of (1) to (5).

It is a schematic diagram showing an example of an image forming apparatus using the image forming method of the present invention. It is a schematic diagram showing an example of an image forming apparatus using the image forming method of the present invention.

Explanation of symbols

L. Laser light P.P. 1. Transfer material 1. electrophotographic photosensitive member 2. Charging device 3. Exposure apparatus 4. Development device 5. Transfer device Leveling member

Claims (4)

A two-component developer containing a charging step for charging an electrostatic latent image carrier, an electrostatic latent image forming step for forming an electrostatic latent image on the charged electrostatic latent image carrier, and a toner and a magnetic carrier The electrostatic latent image is developed using a developing unit that accommodates toner to form a toner image on the electrostatic latent image carrier, and at the same time, the toner remaining on the electrostatic latent image carrier after transfer is recovered. In an image forming method comprising at least a development simultaneous recovery step and a transfer step of transferring a toner image on an electrostatic latent image carrier to an intermediate transfer member or a transfer material,
The developer is replenished with a replenishment developer containing at least replenishment toner and a replenishment magnetic carrier, and excess magnetic carrier is discharged from the developer.
The toner and the replenishing toner contain at least a binder resin and a colorant, and the binder resin is a resin having a polyester unit;
The average circularity of particles having an equivalent circle diameter of 2 μm or more of the toner and the replenishing toner is 0.950 to 0.990,
The magnetic carrier and the supplementary magnetic carrier have at least a carrier core material and a resin component, the carrier core material is a ferrite having a porous shape, and the true specific gravity of the magnetic carrier and the supplementary magnetic carrier is 2.5 to 4.2 g / cm ³ ,
An image forming method characterized by that.   2. The toner according to claim 1, wherein the toner and the replenishing toner include at least a binder resin, a colorant, and a wax, and the toner and the replenishing toner are at least surface-modified by heat treatment. Image forming method.   The toner and the replenishing toner dissolve or disperse a toner composition containing at least a binder resin, a colorant, and a wax in an organic solvent, and the prepared mixed solution is suspended and granulated in an aqueous medium. The image forming method according to claim 1, wherein the toner is obtained by removing the organic solvent. According to any one of claims 1 to 3, characterized in that it comprises a weight ratio of from 2 to 50 parts by weight of the replenishment toner to refill the magnetic carrier 1 part by mass the replenishment developer Image forming method.

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