JPH08160670A - Electrophotographic toner and image forming method - Google Patents

Abstract

PURPOSE: To provide a full-color toner excellent in electrification stability in particular in serious consideration of endurance stability and causing no cleaning defect and no toner filming on a photoreceptor by specifying the electrification control agent quantity contained in toner grains in the range of fixed quantities for the internal layer and the internal surface layer respectively. CONSTITUTION: A resin, a colorant, and an electrification control agent are fused, crushed, and classified to obtain this toner, the electrification control agent quantity (a) is set to 3-10 pts.wt. against the toner of 100 pts.wt., and an equation a/b=2-10 is satisfied, where (b) is the electrification control agent quantity existing on the surface layer of toner grains. This toner is used in the image forming method having the cleaning process constituted of a cleaning blade made of urethane rubber with the rubber hardness of 67 deg. or above. The equation a/b=2-10 indicates the state that the electrification control agent in the toner grains is uniformly dispersed and the dispersion concentration of the electrification control agent on the internal surface layer of the toner grains is high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner and an image forming method in an electrophotographic method, and more particularly to a full color toner capable of suitably embodying the image forming method of a full color copying machine, and stabilizing the charge of the toner and the toner. The present invention relates to a full-color toner suitable for preventing filming.

[0002]

2. Description of the Related Art Conventionally, many methods are known as electrophotography, but generally, a photoconductive substance is used to form an electric latent image on a photoconductor by various means, and then, The latent image is developed with toner, and the toner image is transferred to a transfer material such as paper, if necessary, and then fixed by heating, pressure, solvent vapor or the like to obtain a copy. In this case, the residual toner on the photoconductor that has not been transferred onto the transfer material is generally removed by a cleaning mechanism composed of a regulation blade or a fur brush.

A large number of developing methods are known for such an electrophotographic method, but in particular, a magnetic brush method, a cascade method and the like using a two-component developer mainly composed of toner and carrier are widely put into practical use. . All of these methods are excellent methods in which a good image can be obtained relatively stably, and are often composed of full-color toners that require sharp and faithful color reproducibility, but on the other hand, the carrier surface There are common defects associated with two-component developers, such as toner spent on toner and fluctuations in the mixing ratio of toner and carrier.

As described above, in the toner for developing an electric latent image, various charge control agents are used from the viewpoint of improving durability, particularly in order to achieve stabilization of charging characteristics. Currently, negatively charged color toners are mainly used in full-color copying machines on the market. Generally, when a negative charge is imparted to the toner by using the charge control agent, a metal-containing dye is often used. When producing a toner using these metal-containing dyes, in order to obtain a uniform dispersion in the toner, it is necessary to carry out melt-kneading at a very high temperature, and at this time the dye may undergo thermal decomposition. There are many cases where the color tone changes. Further, when the carrier and the toner are mixed in the developing device, the electric charges applied due to mechanical friction and impact become non-uniform, causing unevenness in image density and fogging, resulting in deterioration of image quality.

As a means for solving these problems, as disclosed in JP-A-57-167033, after treating a metallizable azo compound with a metal-imparting agent by a known method, an acidic or mineral acid or the like is used. It was made possible to obtain a negatively chargeable toner having stable charging characteristics by using an azo metal complex obtained by diluting with water containing water to cause precipitation and filtering.

However, even in a toner using a charge control agent such as an azo metal complex as described in the above publication,
It has been found that good results cannot always be obtained in the case of a sharp melt binder resin used for full-color toner and the like. Specifically, the charge becomes excessive, and it becomes difficult for the toner to be transferred from the photoconductor to the final stage in the process from development to transfer, and the amount of residual toner on the photoconductor increases and toner that cannot be collected by the cleaning mechanism. Causes filming or defective cleaning. Further, it becomes difficult to uniformly charge the toner, and the toner that is not sufficiently charged or the toner that is charged in the opposite polarity is generated, and the fog is generated in the background portion of the obtained visible image.

On the other hand, in Japanese Unexamined Patent Publication No. 4-21862, the amount ratio of the charge control agent present in the surface layer of the toner particles and the amount ratio of the charge control agent present in the entire toner particles are specified. Achieved stabilization of the triboelectric chargeability of the toner. However, the charge control agent present in the surface layer acts as a means to be fixed from the outside of the toner particles by electrostatic force or mechanical impact force, and therefore, when subjected to a durability test in a long-term range, the charge control agent is not Deterioration of the toner particle surface due to mixing (detachment of adhered matter due to toner spent, impact, etc.) is conceivable. Even after frictional charging within a suitable range after preparation of the developer, the charge gradually becomes unstable, resulting in image density. Of the electrophotographic characteristics such as a drastic change in image quality and fog.

Further, the charge control agent present in the surface layer and the inner layer in the publication shows a suitable result for surely obtaining stable chargeability, but the charge control agent in the above means is used. When the toner is adhered to the surface layer of the toner particles, the charge control agent may also exist on the outer surface layer of the toner particles, so that some scratches or nuclei of residual toner may be present on the photoreceptor. The charge control agent is likely to be trapped in the core portion, which may impair the image quality after copying such as toner slipping from the cleaning blade and occurrence of toner filming.

Further, Japanese Laid-Open Patent Publication No. 60-118851 proposes a method of uniformly dispersing a charge control agent in a color toner using a negative polyester resin so that a part of the charge control agent is exposed on the toner surface. , In this publication, resin 1
The content of the charge control agent with respect to 100 parts by weight (mass part) is very small at 0.05 to 0.7 parts by mass (mass part), and a significant difference in the abundance ratio amount inside the particles and in the vicinity of the surface layer is obtained. It is difficult to apply and it is difficult to obtain the intended effect.

Further, in JP-A-61-36757,
It is assumed that 10 to 70% (preferably 30 to 60%) of the charge control agent is on the surface by using the surface dye concentration obtained by extraction with methanol, but the premixing must be performed by a V-type mixer or the like where shearing force does not act. For example, it is difficult to take this form, and uniform dispersion of the charge control agent cannot be expected without sufficient premixing, and if many charge control agents are present in the vicinity of the particle surface layer when the dispersion is poor, the reverse The presence of charge control agents released when toner particles are formed through a pulverizing process, etc., in addition to causing adverse effects such as fogging and lowering of image density by exhibiting unstable chargeability due to uneven accumulation May increase, which may cause filming.

Further, in Japanese Patent Application Laid-Open No. 3-31857, the ratio of the dye concentration on the toner surface to the total dye concentration is specified, but a styrene-acrylic copolymer is used as the binder resin, and it is sufficiently melted. It is difficult to match full-color toner that superimposes colors in a colored state to produce highly saturated colors, and the content is 5 parts by weight (parts by weight)
Because of the following, filming may be likely to occur as in JP-A-61-36757.

On the other hand, in a black toner using carbon black as a colorant for a full-color toner, since the pigment itself has a low resistance, the dispersion of the pigment in the resin and the balance of the content are not good. If such a toner is used, the charge stability of the toner is deteriorated, and the image quality is lowered, and the copy quality such as sweeps and variations in color tone are deteriorated. Therefore, the charge stabilization by the charge control agent is required.

[0013]

The present inventors believe that the above-mentioned problems of the prior art are caused by the following factors.

Conventionally, the factors that determine the triboelectric chargeability of the non-magnetic toner itself are mainly the polarity of the binder resin, the polarity of the colorant, and the charge control agent that plays a role of adjusting the pure chargeability obtained by them. However, in order for the individual components to sufficiently exert their functions, it is difficult to obtain a desired charge amount unless they are uniformly present in the toner.

For example, even if a charge control agent having a relatively high performance is used as the charge imparting member, if the state of dispersion of the charge control agent is not good in the process of manufacturing the toner (kneading-pulverization-classification), the toner of that toner I think that the charging characteristics will also become unstable. In addition, they are not only caused by the manufacturing technology, but are greatly influenced by the melting characteristics of the binder resin which is the base of the dispersion.

As disclosed in the above publication, there is also a means for indicating the dispersed state by defining the ratio of the amount of charge control agent on the surface layer of toner particles and the amount of charge control agent on the inner layer. By concentrating it, it becomes possible to achieve more stable charging, but in this means, the charge control agent is concentrated on the surface layer of the toner particles by mechanical impact, so it is called a surface layer. Also adheres to the surface layer mainly, and if they are dropped or separated from the toner surface, the toner may slip through the cleaning member or the toner filming on the photoconductor may occur.

Therefore, it is an object of the present invention to provide a toner for electrophotography and an image forming method, which solves the problems of the prior art as described above, and in particular, a full color toner capable of suitably embodying the image forming method of a full color copying machine. More specifically, it is an object of the present invention to provide a full-color toner that is particularly excellent in charging stability in terms of durability stability and does not cause cleaning failure or toner filming on the photoconductor.

[0018]

The above objects are achieved by the following inventions. That is, in the present invention, in a toner obtained by melt-kneading at least a resin, a colorant, and a charge control agent, crushing and classifying the toner, the amount (a) of the charge control agent is 3 to 10 parts by weight with respect to 100 parts by weight of the toner. When the amount of charge control agent present in the toner particle surface layer is (b), the following formula is satisfied, and the toner has a rubber hardness of 6:
It is characterized in that it is used in an image forming method having a cleaning step constituted by a cleaning blade made of urethane rubber having an angle of 7 ° or more.

A / b = 2 to 10

First, what the formula intends is to show a state where the charge control agent in the toner particles is uniformly dispersed and the dispersion concentration of the charge control agent in the inner surface layer of the particle is high. That is, it is possible to increase the saturated charging speed of the toner particles and to maintain the saturated charge amount stably. That is, by making the dispersion concentration of the charge control agent existing in the inner layer of the toner particles different from that in the inner surface layer, the chargeability is stalled when mixed with the carrier particles in the two-component system in addition to the usual charging. The effect that it becomes easy to cover is obtained. In the present invention, it was found that this effect can be obtained by having a higher charge control concentration in the inner surface layer than in the inner layer. Further, in this case, the charge control agent is not attached (fixed) to the outer surface layer by external means or the like.

The definitions of the inner layer and the inner surface layer here are as follows.
As shown in FIG. 1, all show the state of the inner layer from the surface layer of one toner particle toward the center of the particle, and the state where other fine particles and the like adhere to the surface layer or the surface layer exposed to the outside air is In this case, it is defined as the outer surface layer. More specifically, the inner layer shows the total integral in one toner particle, and the inner surface layer shows the volume integral within 50Å in the depth direction from the surface of the toner particle.

That is, in the present invention, as means for increasing the dispersion concentration of the charge control agent in the inner surface layer of the toner particles rather than in the inner layer of the toner particles, the toner particles are preliminarily sheared without being embedded by mechanical impact. A charge control agent is uniformly dispersed on the surface of the binder resin, which is one of the raw materials used, using a high-power mixer, and then the state is created by melting, pulverizing, and classifying by a method to obtain a weak share. I found that.

Further, since the use of the means does not cause the charge control agent to adhere to the surface of the toner particles by mechanical impact, it is possible to prevent the charge control agent from being lost or free charge control agent from being easily generated at the stage after the steps such as pulverization. Can be derived. By deriving the state, a low friction condition such as a cleaning blade made of urethane rubber having a rubber hardness of 67 ° or more (preferably 70 ° or more) in a cleaning process for removing the residual toner on the photoconductor. However, the synergistic effect that fusion on the drum, which is seen in filming and the like, does not occur can be obtained. This is because scratches on the surface of the photoconductor are greatly reduced by reducing the frictional resistance generated between the cleaning blades that are directly in contact with the photoconductor. The strong adhesion of the substance onto the surface of the photoreceptor is due to the background that it must be prevented as much as possible.

Derivation of a state in which a large amount of charge control agent is present in the inner surface layer of toner particles as described above can be achieved by creating the following state.

First, the charge control agent is preliminarily mixed and adhered to the surface of the main binder resin particles in a uniformly dispersed state, and then the colorant is further added and kneading is performed in a state where the mechanical load during melting is weak. As a result, the charge control agent in the kneaded material is present in a mesh shape (see FIG. 2), and locally dispersed portions having a high dispersion concentration of the charge control agent (the dispersion concentration is high). However, uneven distribution of the charge control agent itself is not confirmed). Then, when finely divided through a pulverizing step, the kneaded material is likely to crack at the interface with a high dispersion concentration,
The toner particles as proposed in the present invention will be obtained. In this case, it is generally preferable to use a mixer capable of acting on shear stress for premixing, and a Henschel mixer, a super mixer, a ball mill or the like is suitable, but a Henschel mixer is more preferable. The reason is that by attaching the charge control agent relatively strongly to the resin surface, it is possible to maintain the network structure during the subsequent kneading and pulverization steps, and the free charge control agent is reduced. This is because the toner filming does not occur.

As the charge control agent used in the above manufacturing process, a colorless or pale color charge control agent that does not affect the color tone of the color toner is preferable, and examples thereof include metal complexes of alkyl-substituted salicylic acid (for example, di-tert-butyl). Examples thereof include organometallic complexes such as a salicylic acid chromium complex or an aluminum complex). On the other hand, a color-based charge control agent such as that found in dyes affects the color tone of the resulting toner, or causes thermal decomposition at the time of melt kneading at a high temperature, so that it is not preferable as a color toner. Absent.

In the present invention, the amount of the charge control agent present in the toner particle inner layer is the total amount contained in one toner particle, and the measuring means and the like are not limited. For example, fluorescent X-rays may be used and calculated from the X-ray intensity, or any means may be used that actually extracts and quantifies the corresponding charge control agent.

On the other hand, the amount of the charge control agent present in the toner particle inner surface layer is determined by XPS. First, the number of atoms of each material constituting the toner is calculated, and then the number of atoms existing in the toner particle inner surface layer is calculated. The mass ratio of the charge control agent is calculated by converting from these values and the molecular structure.

In the present invention, as shown in the above formula, toner 1
The ratio of the amount of the charge control agent contained in the particles to the amount of the charge control agent present in the surface layer of one toner particle is regulated.
When the value in the formula is less than 2, the charge amount immediately after the developer is prepared is relatively stable, but the charge amount sharply decreases as the number of copies increases, and toner scattering and background fog occur. The problem arises. On the other hand, when the ratio exceeds 10, the charge amount of the toner particles becomes excessive and the image density lowers, resulting in a marked deterioration of image quality.

The effect represented by the above formula is useful when the content of the charge control agent is 3 to 10 parts by mass relative to 100 parts by mass of the toner, and when it is less than 3 parts by mass, the dispersion concentration in the surface layer is low. Therefore, a stable charge amount cannot be obtained. Further, if the amount exceeds 10 parts by mass, the charge control agent is unevenly distributed inside the toner particles, and the charging becomes nonuniform, and image unevenness is likely to occur in an image with many halftones.

Further, the toner according to the present invention can exhibit its performance regardless of using the following photoconductors. As its form, a photosensitive layer and a protective layer are provided on a conductive support, and at least the surface layer contains fluorine atom-containing resin fine particles in order to reduce the friction resistance of the surface of the photosensitive member, and The surface layer is mechanically polished, and the average surface roughness of the surface layer is JIS B06.
It is 0.1 μm or more and 2.5 μm or less, preferably 0.1 μm or more and 1.5 μm or less, which is represented by 10-point average surface roughness R _Z (hereinafter simply referred to as average surface roughness) defined by 1. Is.

When the average surface roughness is larger than 2.5 μm, a gap is formed between the surface of the photosensitive member and the cleaning blade, and residual toner having a small particle diameter after transfer remains as a result of poor cleaning. If the average surface roughness is 1.5 μm to 2.5 μm, the cleaning characteristics are good, but the latent image has a slight irregularity due to the rough surface, especially in the case of an original image such as a photo original, highlight reproduction etc. Will be slightly inferior.

When the average surface roughness is 1.5 μm or less, friction between the cleaning blade and the surface of the photosensitive member is sufficiently small, and image defects do not appear even after repeated use, and highlight reproduction is also possible. It will be very good.

If the average surface roughness is less than 0.1 μm, the friction between the cleaning blade and the surface of the photosensitive member is hardly alleviated, and the effect of reducing the friction by allowing the fluorine atom-containing resin fine particles themselves to appear on the surface is obtained. unacceptable.
Therefore, cleaning failure due to reversal of the cleaning blade, chipping of the blade edge, etc. is caused by the average surface roughness of the surface of the photoreceptor containing the fluorine atom-containing resin fine particles in the surface layer or the protective layer of 0.1 μm to 2.5 μm. Therefore, it can be prevented.

Further, in order to make the above effects preferable, by using a member made of urethane rubber having a rubber hardness of 67 ° or more (more preferably 70 ° or more) as the cleaning blade contacting the photosensitive member, the above effects are obtained. In addition, by using the toner having the above-mentioned configuration, it is possible to prevent a cleaning failure represented by toner slipping at the contact portion and obtain stable cleaning characteristics.

In this case, the material of the cleaning blade is generally selected from well-known materials such as urethane or a resin coating blade using urethane rubber as a base material. We proposed a type in which nylon is coated on the surface of urethane rubber to improve the slipperiness (Japanese Patent Application No. 6-51553), but in the future full-color copying machines will have a longer life of developers and photoconductors as the copy volume increases. In consideration of the situation of progressing to the above, there is a possibility that the surface of the photoreceptor may be scraped by the nylon coat blade, and further improvement has been desired. Therefore, by increasing the hardness of the blade member, the strength of the blade member itself is increased, and even if any cleaning means is used, the effect of preventing the rubber material from cracking due to its behavior can be obtained. The situation in which such an effect can be exhibited without any problems can be achieved by controlling the toner constitution that obtains stable charging characteristics as represented by the present invention, and thereby fusion with the surface of the photoconductor is also eliminated. It is possible to assist the extension of the life of the developer and the photoconductor with a good cleaning system.

As the binder resin used in the toner of the present invention, various material resins conventionally known as electrophotographic toners are used. For example, polyethylene, ethylene,
Examples thereof include vinyl acetate copolymers, ethylene copolymers such as ethylene / vinyl alcohol copolymers, phenolic resins, epoxy resins, acrylic phthalate resins, polyamide resins, polyester resins, maleic acid resins, and the like. In addition, the manufacturing method and the like of each resin are not particularly limited.

Among these resins, particularly when a polyester resin having a high negative chargeability is used, the effect of the present invention is extremely large. That is, while polyester-based resins have excellent fixability and are suitable as color toners, conventionally, they have a strong negative charging ability and tend to be excessively charged. However, the polyester resin is useful for maintaining the dispersion state of the charge control agent as shown in the present invention, whereby the above-mentioned adverse effects are ameliorated and a more excellent full-color toner can be obtained.

The following pigments or dyes may be mentioned as colorants for color toners suitable for the purpose of the present invention. Preferred pigments are disazo yellow, insoluble azo pigment,
There are copper phthalocyanine, etc., basic dyes,
Oil-soluble dyes are suitable.

Particularly preferred as a pigment is C.I. I. Pigment Yellow 17; C.I. I. Pigment Yellow 15;
C. I. Pigment Yellow 13; C.I. I. Pigment Yellow 14; C.I. I. Pigment Yellow 12; C.I.
I. Pigment Red 5; C.I. I. Pigment Red 3; C.I. I. Pigment Red 2; C.I. I. Pigment Red 6; C.I. I. Pigment Red 7; C.I. I. Pigment Blue 15; C.I. I. Pigment Blue 16 or a copper phthalocyanine pigment having a structural formula (I) shown below, in which the phthalocyanine skeleton is substituted with 2 to 3 substituents, and carbon black.

[0041]

Embedded image

[Wherein X ₁ , X ₂ , X ₃ and X ₄ are

[0043]

Embedded image

Or H is shown. However, the case where all of X _{1 to} X ₄ are -H is excluded. ]

On the other hand, preferred dyes include C.I. I. Solvent Red 49; C.I. I. Solvent Red 52;
C. I. Solvent Red 109; C.I. I. Basic Red 12; C.I. I. Basic Red 1; C.I. I. Basic Red 3b can be mentioned.

Regarding the content of yellow toner, which is sensitively reflected in the transparency of the OHP film,
The amount is preferably 12 parts by mass or less, and more preferably 0.5 to 7 parts by mass with respect to 100 parts by mass of the binder resin.

For the other magenta and cyan color toners, 15 parts by weight or less, more preferably 0.1 to 9 parts by weight is desirable based on 100 parts by weight of the binder resin, and 2 to 10 parts by weight for the black toner, Preferably 3 to
7 parts by mass is desirable. This is because, if the value deviates from the range, the visible image may be rough, image density may be reduced, toner may be scattered, and fogging may occur.

The toner of the present invention is preferably used in combination with a carrier as a two-component developer. Examples of the carrier include surface-oxidized or unoxidized iron, nickel, copper,
Metals such as zinc, cobalt, manganese, chromium, and rare earths, alloys or oxides thereof, and magnetic ferrite can be used.

A system in which the surface of the carrier is immersed in a resin or the like is particularly preferable. As the method, a method of dissolving or suspending a coating material such as a resin in a solvent to apply the coating material to a carrier, and a method of simply mixing as a powder,
Any conventionally known method can be applied.

An electrically insulating resin is used as a substance adhered to the surface of the carrier and is appropriately selected according to the toner material and the carrier core material. In this case, at least one monomer selected from acrylic acid (or its ester) monomer and methacrylic acid (or its ester) monomer is contained in order to improve the adhesiveness with the carrier core material surface. It is necessary to. In particular, when polyester resin particles having a high negative chargeability are used as the toner material, it is preferable to use a copolymer with a styrene-based monomer for the purpose of stabilizing the charge. Is preferably 5 to 70% by mass.

Examples of usable carrier core material coating resin monomers include, for example, styrene monomers, chlorostyrene monomers, α-methylstyrene monomers, styrene-chlorostyrene monomers, and acrylic monomers such as acrylic acid. There are ester monomers (methyl acrylate monomer, ethyl acrylate monomer, butyl acrylate monomer, octyl acrylate monomer, phenyl acrylate monomer, 2-ethylhexyl acrylate monomer), etc., and methacrylic acid ester monomers (methyl methacrylate monomer, methacrylic acid monomer). Ethyl monomer, butyl methacrylate monomer, phenyl methacrylate monomer) and the like.

The coating materials for these carriers are relatively suitable for the toner of the present invention, but are not necessarily limited thereto, and the surface energy considered to be useful for preventing the toner from being spent on the carrier such as fusion of the toner. It does not matter even if a resin having a low For example, fluororesin, silicone resin and the like can be mentioned, but since these have poor adhesion to the carrier core material, the effect cannot be obtained unless the toughness of the coating is enhanced by using various additives together. In particular, when coating the silicone resin, by adding water to the coating resin diluting solvent used, the durability and charging characteristics of the obtained coated carrier are further improved. This is because the crosslinking point of the curable silicone resin and the hydrolysis of the silane coupling agent are promoted, the curing reaction proceeds further, and the surface energy of the silicone resin increases for a short time, and This is because the adhesion is improved.

The coating amount of the coating resin seen above on the carrier core material is such that the resin solid content is 0.05 to 10% by mass,
It is preferably 0.1 to 5 mass%. If it is less than 0.05% by mass, the coating effect is not sufficient with the resin of the carrier core material, and the coating amount exceeding 10% by mass is meaningless, and there is a case in which an excessive resin alone is present from the viewpoint of production, Not preferable.

The average particle size of these carriers is 27-
It is desirable to have 100 μm, preferably 25 to 70 μm, and more preferably 25 to 65 μm, and the measurement is equipped with a laser diffraction particle size distribution measuring device HELOS (made by JEOL Ltd.) and a dry dispersion device RODOS (made by JEOL Ltd.). Then, each sample was measured three times under a dispersion pressure of 3.0 bar, and the average thereof was taken to measure the average particle size of the carrier. The average particle size at this time was 50%.

When a two-component developer is prepared by mixing the toner according to the present invention with the carrier of the above-mentioned form, the mixing ratio is 1 to 12% by mass, preferably 2 to 9% by mass as the toner concentration in the developer. %, Usually good results are obtained. When the toner concentration is less than 1% by mass, the image density is low and it becomes unpractical, and when it exceeds 12% by mass, fog and scattering in the machine are increased and the useful life of the developer is shortened.

As the fluidity improver used in the present invention, any fluidity improver can be used as long as the fluidity can be increased before and after the addition. Examples thereof include hydrophobic colloidal silica fine powder, colloidal silica fine powder, hydrophobic titanium oxide fine powder, titanium oxide fine powder, hydrophobic alumina fine powder, alumina fine powder, and mixed powder thereof.

Further, if necessary, a fatty acid metal salt as a lubricant, such as zinc stearate or aluminum stearate, or a fine powder containing fluorine, such as polytetrafluoroethylene, polyvinylidene fluoride or the like and tetrafluoroethylene-vinylidene fluoride. A fine powder of a ride copolymer or a conductivity-imparting agent such as tin oxide or zinc oxide may be added.

Further, a release agent may be further contained as a fixing aid. For example, an aliphatic hydrocarbon wax, an oxide of an aliphatic hydrocarbon wax, a wax containing a fatty acid ester as a main component, a saturated linear fatty acid, an unsaturated fatty acid, a saturated alcohol, a polyhydric alcohol, a fatty acid amide. And saturated fatty acid bisamides, unsaturated fatty acid amides, aromatic bisamides, and the like. In this case, the amount of the release agent is 0.1 to 20 parts by mass, preferably 0.5 to 10 parts by mass per 100 parts by mass of the binder resin. This is because if the amount of the releasing agent is more than 20 parts by mass, the blocking resistance and the high temperature offset resistance are poor, and if it is less than 0.1 parts by mass, the releasing effect is not obtained.
Further, these release agents usually dissolve the resin in a solvent,
It is desirable that the binder resin be contained in the binder resin by raising the temperature of the resin solution and adding and mixing it with stirring, or by mixing with the kneaded product.

[0059]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. In addition, all "parts" and "%" in a sentence are "mass parts" and "mass%."

Example 1 Polyester resin A shown below 100 parts Phthalocyanine pigment 3.5 parts Di-tert-butylsalicylic acid chromium complex 8 parts After sufficiently premixing with a Henschel mixer,
The mixture was melt-kneaded while applying a relatively weak shear in a twin-screw extruder, cooled, and coarsely crushed to a particle size of about 1 to 2 mm using a hammer mill. Then, it was finely pulverized by an air jet type fine pulverizer, and the obtained fine pulverized product was classified by a multi-division classifier to obtain blue resin particles having an average particle diameter of 6.0 μm.

(Resin A) 2 mol of terephthalic acid, 1.09 mol of dodecenyl succinic anhydride, 3.4 mol of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane and dibutyltin oxide.
01 g was placed in a glass 2-liter four-necked flask, and a thermometer, a stirring rod, a condenser, and a nitrogen introduction tube were attached and placed in a mantle heater. Next, after the inside of the flask was replaced with nitrogen gas, the temperature was gradually raised with stirring to 1
React at 70 ° C for 5 hours, then raise to 190 ° C,
Allowed to react for 4 hours.

Then, 0.2 mol of trimellitic anhydride
And 0.08 g of dibutyltin oxide were added, and the mixture was reacted at 190 ° C. for 3 hours, further heated to 200 ° C. and reacted for 5 hours to complete the reaction to obtain a polyester resin (A) used in the present invention.

100 parts of the above colored resin particles and 1.0 part of a hydrophilic titanium oxide synthesized from titanium chloride which was subjected to a hydrophobic treatment in the presence of water (BET 90 m ^{2 /} g) were combined with the cyan toner of the present invention. did. Further, the cyan toner is surface-coated with a silicone resin to form Cu-Zn-Fe.
The system ferrite carrier particles were mixed so as to have a toner concentration of 6% to obtain a cyan developer.

The amount of the charge control agent contained in the cyan toner was detected by fluorescent X-rays for Cr (a), and XP was used.
When the mass ratio (b) of the charge control agent converted from the number of atoms existing in the internal surface layer (about 50Å in the depth direction) was calculated using S, the value of (a) / (b) was 3.8. there were.

Further, using the above cyan developer, a commercially available color copying machine (CLC-800, manufactured by Canon Inc.) was equipped with a urethane rubber blade having a rubber hardness of 77 ° as a cleaner, and an image was evaluated. Even in the durability test of 50,000 sheets, the image density was as high as 1.7 to 1.8 in Macbeth density, filming did not occur, and there was no initial fluctuation in charging property between about -30 to -35 mC / kg. It remained stable. In addition, no scratch was confirmed on the surface of the photoconductor, and the image quality was not hindered.

On the other hand, except that the colorant used was changed to carbon black, black toner was obtained with the same material and the same manufacturing method, and the same evaluation was carried out (a) /
(B) is 4.2 and the charge amount is also about -25 to -30 mC / k.
In the range of g, stable and good results were obtained from the initial stage.

Example 2 Polyester resin B shown below 100 parts Carbon black 3.5 parts Di-tert-butylsalicylic acid chromium complex 8 parts were melt-kneaded, pulverized and classified in the same manner as in Example 1 to obtain an average particle size of 6 Black resin particles of 0.0 μm were obtained.

(Resin B) 1.8 mol of isophthalic acid, 1.06 mol of dodecenyl succinic anhydride and 3.5 mol of polyoxypropylene (2.0) -2,2-bis (4-hydroxyphenyl) propane were mixed with resin A. The reaction was carried out in a nitrogen atmosphere in the same manner as in the case. Next, 0.16 mol of trimellitic anhydride and 0.
09 g was added and the reaction was carried out at 180 ° C. for 5 hours to obtain the polyester resin (B) used in the present invention.

Using the above black resin particles, a black developer was prepared and evaluated in the same manner as in Example 1. The value of (a) / (b) was 4.1, which was generally Although the dispersion state of the carbon black particles in the binder resin adversely affects the electrophotographic characteristics, the dispersibility of the charge control agent is improved and a large amount of the charge control agent is concentrated on the internal surface layer. The density was stable at around 1.8, the total amount of charge was -25 mC / kg, comparable to the color toner, and there was almost no change in the initial stage of durability evaluation. As a more preferable result, there was no fog and filming on the drum surface was not confirmed.

Example 3 The binder resin used in Example 1 is a polyester resin shown in C below, and the colorant is C.I. I. Pigment Yellow 17 was used in the same manner as in Example 1 except that Pigment Yellow 17 was used.
The value of / (b) shows 4.2, and the image density is 1.8-1.
It showed a high value of 9 and exhibited good electrophotographic characteristics without fog and filming.

(Resin C) 2 mol of terephthalic acid, 1.15 mol of octyl succinic acid and polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl)
3.8 mol of propane was reacted in the same manner as in Resin A in a nitrogen atmosphere. Next, 0.21 mol of trimellitic anhydride and 0.08 g of dibutyltin oxide were added and the reaction was carried out at 180 ° C. for 5 hours to obtain a polyester resin (C) used in the present invention.

Example 4 The charge control agent used in Example 1 was di-tert.
A blue toner and a developer were prepared in the same manner except that the aluminum complex of -butylsalicylic acid was used, and the same evaluation was carried out. As a result, (a) / (b) was 5.3, and other electrophotographic characteristics were also obtained. Good results have been obtained.

Example 5 The charge control agent used in Example 2 was di-tert.
A black toner and a developer were prepared in the same manner except that 1.5 parts of high molecular weight polypropylene was added as a release agent, which was a zinc complex of butylsalicylic acid, and the same evaluation was performed. The value of (b) was 4.5, and other electrophotographic characteristics were also good.

Example 6 In the step of preparing a pigment masterbatch, the polyester resin A and the phthalocyanine pigment in Example 1 were pre-kneaded in a kneader at a ratio of 7/3 and then the kneaded product was passed twice through three rolls. Then, the masterbatch, the polyester resin for dilution A, and a chromium complex of di-tert-butylsalicylic acid were used to obtain a cyan toner in the same manner as in the production method described in Example 1, and the same evaluation was performed below (a The value of) / (b) was 4.3, and good image quality was obtained without causing cleaning failure.

Comparative Example 1 Polyester Resin A shown in Example 1 100 parts Phthalocyanine pigment 3.5 parts Di-tert-butylsalicylic acid chromium complex 8 parts After premixing with a V-type blender, a twin-screw extruder was used. The mixture was melt-kneaded while applying mechanical shear, cooled, and then coarsely pulverized to a particle size of about 1 to 2 mm using a hammer mill.
Then, finely pulverized by an air jet type fine pulverizer, and the finely pulverized product obtained was further classified by a multi-division classifier to obtain blue resin particles having an average particle diameter of 6.0 μm.

A cyan toner was prepared by combining 100 parts of the above colored resin particles with 1.0 part of a hydrophilic titanium oxide synthesized from titanium chloride which was subjected to a hydrophobic treatment in the presence of water (BET 90 m ^{2 /} g). Further, the cyan toner was mixed with Cu—Zn—Fe ferrite carrier particles whose surface was coated with an acrylic resin so that the toner concentration became 6% to obtain a cyan developer.

The abundance of the charge control agent contained in the cyan toner was converted into Cr by detection with fluorescent X-rays (a), and the number of atoms present in the internal surface layer (about 50Å in the depth direction) was further measured using XPS. When the mass ratio (b) of the charge control agent converted from was calculated, the value of (a) / (b) was 10.2.

Further, the above-mentioned cyan color developer was used to perform image evaluation with a commercially available color copying machine (CLC-800, manufactured by Canon Inc.). In the durability test, the initial Macbeth density was 1.7 to 1. Although the image density was as high as 0.8, the density decreased to 1.2 to 1.4 after passing about 500 sheets. Further, after about 1000 sheets, filming occurred on the photoconductor and the image quality was remarkably deteriorated.

It is speculated that the reason why the above results were reached was that the charge control agent, which had a relatively large content, was not sufficiently dispersed in the premixing stage.

Comparative Example 2 A black toner and a developer were prepared in the same manner as in Example 1 except that the chromium complex of di-tert-butylsalicylic acid was 2 parts, and the same evaluation was carried out. Although the density was 1.5, the toner was scattered after 1500 sheets were passed. (A) / (b) at that time
The value of was 4.3. It is speculated that the reason why the toner scattering occurred in the evaluation was that the charging rate up to the desired charging amount became difficult to follow at the toner replenishment stage during the durability evaluation because the amount of the charge control agent was small. It

Comparative Example 3 During the production process of the masterbatch in Example 6, di-
A cyan toner was obtained by incorporating 8 parts of a chromium complex of tert-butylsalicylic acid, and then the masterbatch and the polyester resin A for dilution were obtained in the same manner as in the production method described in Example 1, and the same evaluation was performed. (A) /
The value of (b) was 1.5, which was noticeable in the image evaluation after 2,000 sheets were passed, and the transfer rate was remarkably reduced particularly in the halftone portion. Further, the charge amount from the initial stage was as low as around -15 mC / kg, and violent toner scattering occurred after about 700 sheets were passed.

The cause of the above results is that the charge control agent was contained in the masterbatch, so the dispersibility in the toner particles was too high, and there was a difference in the dispersion concentration between the inner layer and the inner surface layer. It is caused by the disappearance of the charge and the state that the charge apparently leaks.

Comparative Example 4 The same evaluation was carried out except that the cleaning blade used in the evaluation means in Example 1 was a nylon-coated blade having a rubber hardness of 65 °. In addition, a crack was generated at the blade end, and the toner slipped from the location, causing back stain.

[0084]

As described above, according to the present invention, the charge control agent amount contained in the toner particles is regulated within a fixed amount range in each of the inner layer and the inner surface layer, so that the chargeability is excellent. In addition, the effect of not causing toner filming on the photoconductor was obtained.

Further, by using urethane rubber having a rubber hardness of 67 ° or more as the material of the cleaning blade, cleaning failure can be eliminated, and thereby the life of the developer and the photosensitive member can be extended.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a particle cross-sectional layer of a toner of the present invention.

FIG. 2 is a schematic explanatory diagram of a state in which a charge control agent is dispersed in a network in a kneaded material.

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Claims (4)

[Claims] 1. A toner obtained by melt-kneading at least a resin, a colorant and a charge control agent, pulverizing and classifying the mixture,
The charge control agent amount (a) is 3 with respect to 100 parts by mass of the toner.
The amount of the charge control agent present in the toner particle surface layer is (b), and the electrophotographic toner satisfies the following formula. a / b = 2 to 10 2. The toner for electrophotography according to claim 1, wherein the resin component is a polyester resin. 3. The toner for electrophotography according to claim 1, wherein the charge control agent is a colorless or light-colored charge control agent. 4. The toner according to claim 1, wherein a cleaning member composed of a cleaning blade made of urethane rubber having a rubber hardness of 67 ° or more is used in the cleaning step for removing the residual toner on the photosensitive member. developing,
An image forming method characterized by repeating a transfer step.