JPH08220874A - Image forming method - Google Patents

Abstract

PURPOSE: To provide an image forming method which has excellent dot reproducibility and property to prevent splashing of toner and by which images having high image quality are obtainable. CONSTITUTION: A developer carrier has at least a base body and coating layer. The base body surface is coated with this coating layer. The coating layer is formed of the coating layer contg. (i) a mixture composed of a solid lubricant, conducting agent or solid lubricant and the conducting agent, (ii) spherical particles having a number average grain size of 0.3 to 30μm and (iii) a binder resin. The toners to be used are formed of a compsn. contg. at least a polymer component and charge control agent and have silica A and silica B subjected to a silicone oil treatment. The silica A and silica B subjected to the silicone oil treatment satisfy the following conditions; a) the average particle size of the silica is 10A<=B, b) the treating amt. of the silicone oil is 2A<=B, c) the amt. (by weight) of the silica to be added to the toners is A>=3B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method for visualizing an electrostatic charge image formed by an electrophotographic method, an electrostatic printing method or the like.

[0002]

2. Description of the Related Art US Pat.
Although a number of methods are known as described in JP-A-7-691, Japanese Patent Publication No. 42-23910 and Japanese Patent Publication No. 43-24748, generally, a photoconductive substance is used, An electric latent image is formed on the photoconductor by various means, then the latent image is developed with toner, and the toner image is transferred to a transfer material such as paper, if necessary, followed by heating, pressure and heating. The toner is fixed by pressure or solvent vapor to obtain a copy, and the toner remaining on the photosensitive member without being transferred is cleaned by various methods, and the above steps are repeated.

In recent years, such a copying machine has become smaller and smaller.
Lighter weight, higher speed, and higher reliability have been rigorously pursued. At the same time, higher definition and higher image quality are required, but it is difficult to obtain a high quality image while satisfying the above performance.

Various developing methods are known in which an electrostatic latent image is visualized using toner. For example, US Pat. No. 2,87
The magnetic brush method described in US Pat. No. 4,063, the cascade developing method described in US Pat. No. 2,618,552 and the US Pat. No. 2,221,776 US Pat. Many developing methods such as powder cloud method, fur brush developing method and liquid developing method are known. Among these developing methods, a magnetic brush method, a cascade method, a liquid developing method, and the like, which use a developer mainly composed of toner and carrier, have been put into practical use. All of these methods are excellent methods in which a good image can be obtained relatively stably, but on the other hand, they have problems associated with a two-component developer, such as carrier deterioration and variation in the mixing ratio of toner and carrier.

In order to solve such a problem, various developing methods using a one-component developer composed of only toner have been proposed. Among them, most of them are excellent in the method of using a developer composed of magnetic toner particles.

US Pat. No. 3,909,258 proposes a developing method using a magnetic toner having electrical conductivity. This is a method in which a conductive magnetic toner is supported on a cylindrical conductive sleeve having magnetism inside, and this is brought into contact with an electrostatic image carrier having an electrostatic image for development. At this time, in the developing section, a conductive path is formed by the toner particles between the surface of the recording material and the surface of the sleeve,
Electric charges are introduced from the sleeve to the magnetic toner particles through the conductive path, and the toner particles adhere to the image portion and are developed by the cloning force between the image portion of the electrostatic image and the magnetic toner particles. This developing method using a conductive magnetic toner is an excellent method that avoids the problems associated with the conventional two-component developing method, but on the other hand, since the toner is conductive, the electrostatic image bearing member having a toner image is transferred to a plain paper. However, there is a problem that it is difficult to electrostatically transfer to a final support member such as.

As a developing method using a high resistance insulating magnetic toner, a magnetic toner having a triboelectric charge by frictionally charging the magnetic toner particles by friction between the magnetic toner particles or friction between the magnetic toner particles and the sleeve is used. A method of developing an electrostatic image is known. However, these methods have a problem that the number of contacts between the magnetic toner particles and the friction member is small and triboelectric charging tends to be insufficient, and the charged magnetic toner particles tend to aggregate on the sleeve due to an increased cloning force between the magnetic toner particles and the sleeve. Have a point.

In Japanese Patent Laid-Open No. 55-18656 (corresponding US Pat. Nos. 4395476 and 4473627), a new jumping developing method which eliminates the above-mentioned problems is proposed. This involves applying a very thin coating of magnetic toner on a sleeve, tribocharging it, and then developing the magnetic toner layer on the sleeve close to the electrostatic image. This method increases the chance of contact between the sleeve and the magnetic toner by applying the magnetic toner very thinly on the sleeve, and enables sufficient triboelectrification of the magnetic toner. By relatively moving the magnetic toner and the magnetic toner, the magnetic toner particles are prevented from aggregating with each other and sufficiently rubbed with the sleeve, and so on, an excellent image can be obtained.

However, even in the above method, the image density may be low due to insufficient charge imparting to the toner of the sleeve or insufficient chargeability between the toners in the initial stage of development, or repeated development for a long time may be continued. When the developer and the sleeve are deteriorated, sufficient triboelectrification cannot be obtained and the electrification becomes non-uniform, which easily causes problems of image quality such as scattering and deterioration of dot reproducibility.

On the other hand, in the transfer step, in the image forming apparatus including the step of electrostatically transferring the transferable toner image formed on the surface of the latent image carrier to a sheet-like transfer material mainly made of paper, An endless image carrier such as a rotating cylinder or an endless belt is used. A transfer device to which a bias is applied is brought into pressure contact with the transfer device to pass a transfer material between them, so that the toner image on the image carrier side is transferred. A device configured to transfer to a transfer material, for example, an apparatus as disclosed in JP-A-59-46664 has already been proposed (see FIG. 1).

Such an apparatus adjusts the pressure contact force of the transfer roller to the image carrier by adjusting the pressure contact force of the transfer roller to the image carrier, as compared with the transfer means using corona discharge which has been widely used in the past. The adsorption area can be expanded, and the transfer material is positively pressed and supported at the transfer site. For this reason, there is little risk of synchronization failure due to the transfer material conveying means and transfer deviation due to loops, curls, etc. existing in the transfer material, and the shortening of the transfer material conveying path accompanying the recent miniaturization of this type of image forming apparatus It is easy to meet the demands for smaller diameter support.

On the other hand, however, in an apparatus which performs transfer by contact, since a transfer current is supplied from the contact area, it is necessary to apply a certain amount of pressure to the transfer apparatus. When the contact pressure is applied, the toner image on the latent image carrier is also applied with pressure and agglomerated.

Further, when the surface of the latent image carrier is made of resin, the toner agglomerates and the latent image carrier also come into close contact with each other, and as a result, the toner is transferred onto the surface of the latent image carrier or transferred. The phenomenon of sticking to the surface of the abutting member of the device may occur.

When such a phenomenon occurs, a defect occurs in the latent image formation of the latent image carrier or a transfer omission occurs,
This will result in defective image copying.

Further, the image quality has been considerably improved by using a transfer means using a transfer roller.
However, toner scattering, dot reproducibility, and the like are inevitably deteriorated during the transfer process, and therefore improvements are still needed to pursue high image quality.

A developer carrier used in the dry development method is proposed in, for example, JP-A-57-66455. It is known that a metal such as aluminum, nickel or stainless steel or an alloy compound is molded into a cylindrical shape and the surface thereof is treated with a means such as electrolysis, blasting or sanding so as to have a predetermined surface roughness. There is.

While the above-described developer carrying member is inexpensive and relatively stable to obtain a high-quality image, in the case of using a one-component developer which is charged by the developer carrying member, Although it is difficult to adjust the toner charge and various measures have been taken by the developer, the problem relating to the non-uniformity of charging has not been completely solved.

As disclosed in JP-A-61-180267, the surface of the developer carrier is coated with a conductive coating agent containing a texturing agent, or the developer carrier is made of the same material as the coating agent. Is proposed.

However, even in these methods,
It has not been sufficiently solved for a one-component magnetic developer.

The reason for this is that the developer contains a substance such as a magnetic material having a relatively low resistance, the charge easily escapes, and the charge tends to become non-uniform. Since such an inorganic substance is contained, it is difficult to stabilize the image quality because the abrasion of the coating film is promoted.

The above phenomenon is described in Japanese Patent Application Laid-Open No. 52-119.
As can be seen in Japanese Patent No. 651, it is particularly remarkable in the manufacturing method in which the coating layer is formed with a liquid or paste paint.

In the case of a liquid or paste, there is a time (pigment dry period) during which the pigment can move inside the coating film, and the surface of the developer carrier tends to be smooth due to surface tension and compatibility of the materials. It is due.

In Japanese Patent Laid-Open No. 60-80876,
It has been proposed that the surface of the developer carrier be coated with a conductive coating agent or be made of the same material as the coating agent.

However, even with these methods, the image quality is not sufficiently stabilized against the durable number of sheets. Image density rises (higher) as the durability test progresses
Or, it was observed that the image quality was lowered (decreased), the image density was unstable, and the image quality was deteriorated.

It is considered that this is because the protruding state of the conductive pigment on the surface of the coating layer changes.

In the initial state of the developer carrier, the protrusion of the pigment is relatively small due to the surface tension of the material and the compatibility of the material, but when the durability test proceeds, the surface layer of the developer carrier is scraped by the developer, and It is thought that this is due to the formation of a smooth surface. On the other hand, it is recognized that the above phenomenon can be alleviated by using a substance having a destructive property such as graphite as the pigment. It is considered that this is because the surface state of the substance is quickly stabilized due to the destructive property of the substance.

However, the addition of graphite causes the following problems.

(1) Since graphite is usually in the form of flakes, even a material having an average particle size of several μm has a width of several tens μm in the direction of the major axis (breaking surface). ing.
Even when the ratio of the conductive surface (pigment surface) to the insulating surface (resin surface) is stable when viewed macroscopically on the developer carrier surface, it is non-uniform when viewed microscopically (developer size level). However, the ability of the developer carrying member to impart charge to the toner becomes uneven. As a result, the thickness of the toner coat layer locally changes, and the density changes.

(2) Since the surface of the broken surface is flat, the toner sticking phenomenon is likely to occur.

According to the above phenomenon, the coating layer is formed by the method described in JP-A-52-11.
In the method described in Japanese Patent No. 9651, it becomes particularly remarkable in a manufacturing method in which a liquid or paste paint is used.

In these methods, there is a time (pigment dry time) when the pigment in the liquid or pasty coating material can move inside the coating film, and the surface of the developer carrier is bound by the surface tension and the compatibility of the materials. This is because the surface of the resin is likely to appear.

On the other hand, as the toner, the fluidity of the toner, the charging property, the environment resistance, and the treatment of various inorganic oxide fine powders have been studied for the purpose of high image quality.

For example, JP-A-49-42354,
Japanese Patent Publication No. 55-26518 discloses that powder of silica or the like is treated with silicone oil to improve the toner fluidity.

Further, JP-A-58-60754 discloses a toner containing wet silica treated with silicone oil, and JP-A 61-277964 discloses a toner containing silica treated with silicone oil and having a hydrophobicity of 90% or more. It has been disclosed and shown to improve toner fluidity and charging properties, respectively.

However, the toner external additive having the above structure is not sufficient for the high image quality, high transferability, high durability and environmental resistance required in recent years. In particular, there are problems in dot reproducibility in terms of image quality, prevention of toner scattering, and further, toner charging stability in high-speed printing and environmental stability.

[0036]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for forming an image which is capable of obtaining a high quality image excellent in dot reproducibility and toner scattering prevention, by greatly improving the problems of the prior art. To do.

A further object of the present invention is to provide an image forming method which is less affected by temperature and humidity due to the environment and which is capable of obtaining stable toner chargeability even over a long period of time.

A further object of the present invention is to provide an image forming method in which toner charging is fast.

[0039]

According to the present invention, the developer carrier has at least a substrate and a coating layer, and the surface of the substrate is coated with the coating layer. The coating layer comprises (i) Formed by a coating agent containing a solid lubricant, a conductive agent or a mixture of a solid lubricant and a conductive agent, (ii) spherical particles having a number average particle diameter of 0.3 to 30 μm, and (iii) a binder resin. The toner to be used is formed of a composition containing at least a polymer component and a charge control agent, and has at least silicone oil-treated silica A and silica B. The silicone oil-treated silica A And silica B satisfy the following conditions: a) the average particle diameter of silica is 10A ≦ B b) the amount of silicone oil treated is 2A ≦ B c) the addition amount (weight ratio) to the toner satisfies A ≧ 3B. Characterized image On the formation method.

Further, according to the present invention, a thin layer of magnetic toner is formed on a developer carrying member which is arranged with a certain gap from the electrostatic latent image carrying member, and further the developer carrying member and the latent image are formed. The present invention relates to an image forming method including a step of developing an electrostatic latent image on an electrostatic latent image carrier with the magnetic toner while applying an alternating current between the carriers.

Further, in the present invention, the average particle size of the silicone oil-treated silica A is 0.1 μm or less, and the average particle size of the silicone oil-treated silica B is 0.5 μm or more 50.
The present invention relates to an image forming method characterized by having a thickness of not more than μm.

Further, in the present invention, the oil treatment amount of the silicone oil treated silica A is 1 to 30% by weight based on the treated silica, and the oil treatment amount of the silicone oil treated silica B is 30 to 30% based on the treated silica. 90% by weight relates to an image forming method.

Furthermore, in the present invention, the amount of the silicone oil-treated silica A added to the toner is 0.3 to 3.0% by weight.
And the amount of the silicone oil-treated silica B added to the toner is 0.005 to 0.5% by weight.

The present invention further relates to an image forming method, wherein the treated oil viscosity of the silicone oil treated silicas A and B is 10A≤B.

Furthermore, the present invention relates to an image forming method, wherein the solid lubricant of the developer carrying member is graphite.

Further, the present invention relates to an image forming method, wherein the conductive agent of the developer carrying member is carbon black.

Further, the present invention relates to an image forming method, wherein the spherical particles of the developer carrying member are a methyl methacrylate resin (PMMA).

According to the present invention, the above-mentioned object is achieved because the oil-treated silica A maintains the toner fluidity and the oil-treated silica B improves the chargeability between toners to make the charge amount uniform. it is conceivable that.

On the other hand, by using a developer carrier whose coating layer is formed of a solid lubricant, a conductive agent or a mixture of a solid lubricant and a conductive agent, spherical particles and a binder resin, Stable chargeability of the toner can be obtained for a long period of time, and stable charge impartment to the toner can be obtained with little influence of temperature and humidity on the environment.

Therefore, by combining the developer carrier and the developer as described above, the dot reproducibility is better and the toner scattering is smaller and the image quality is higher than that in the conventional structure. Images can be obtained.

Further, with the above-mentioned constitution, the rise of the toner charge is accelerated, and an image having a high and stable density can be obtained even in the initial stage of the durability test.

The spherical particles of the coating layer of the developer carrying member are added in order to prevent the broken surface of graphite from becoming smooth, and in particular, the coating layer of the developer carrying member becomes worn. Even in the case of being added, it is added to maintain a uniform surface roughness. If the number average particle diameter of the spherical particles is less than 0.3 μm, there is no effect of surface roughness, and if the number average particle diameter exceeds 30 μm, the particles protrude from the coating film and undesired development is likely to occur only in that portion, which is not preferable. The term “spherical” in the present invention means that the ratio of major axis / minor axis of particles is 1.0 to 1.5.
(Preferably 1.0 to 1.2) is preferable. Particularly, spherical particles are preferable.

Regarding the particle size of the oil-treated silica, it is necessary to use oil-treated silicas A and B having a particle size difference of 10 times or more.

The preferable average particle size of the oil-treated silica A is 0.1 μm or less (more preferably 0.002 to 0.
05 μm), the preferable average particle size of the oil-treated silica B is 0.5 to 50 μm (more preferably 3 to 20 μm), and the respective particle sizes must satisfy the relation of 10A ≧ B. The difference in particle size between oil-treated silica A and B is 10
If it is less than twice, the compatibility between the fluidity of the toner and the charging property is deteriorated.

Regarding the oil treatment amount, it is necessary that the oil treatment silica B having a large particle size has an oil treatment amount which is twice or more that of the oil treatment silica A having a small particle size. .

Also, the amount added to the toner (weight ratio)
However, it is necessary to have the oil-treated silica A having a small particle diameter in an amount of 3 times or more that of the oil-treated silica B having a large particle diameter. If the amount added to the toner does not satisfy the relationship of A ≧ 3B, the toner fluidity decreases.

The oil treatment amount of the oil-treated silica (small particle size) A is preferably 1 to 30% by weight based on the treated silica, and the oil treatment amount of the oil-treated silica (large particle size) B is the treated silica. 30 to 90% by weight (more preferably 40 to 65% by weight) is preferable. If there is no difference in the oil treatment outside the above range, the compatibility between the chargeability and the fluidity of the toner decreases.

The preferable range of the amount of the oil-treated silica A added to the toner is 0.3 to 3.0% by weight, and the amount of the oil-treated silica B added to the toner is 0.005 to 0.5% by weight. Preferably there is.

Further, it is preferable that the viscosity of the treated oil of the oil-treated silica B having a large particle size is 10 times or more the viscosity of the oil of the oil-treated silica A having a small particle size.

Furthermore, the oil-treated silica A has an oil viscosity of 1 to 1000 cSt, and the oil-treated silica B is
More preferably, the oil viscosity of is from 3000 to 100,000 cSt.

The silica in the developer used in the present invention is
Both so-called dry process or fumed silica, which is called fumed silica, produced by vapor phase oxidation of a silicon halogen compound, and so-called wet silica produced from water glass or the like can be used. As the matrix of the oil-treated silica A having a small particle size, dry silica having a small amount of silanol groups on the surface and inside the silicic acid fine powder and having no production residue of Na ₂ O, SO ₃ ^2-, etc. is preferable. .

For dry silica, it is also possible to obtain a fine composite powder of silica and another metal oxide by using another metal halogen compound such as aluminum chloride or titanium chloride together with a silicon halogen compound in the manufacturing process. Yes, and include them.

The silica used in the present invention (particularly the base silica of the oil-treated silica A) is preferably treated in advance with a silane coupling agent or the like. As the silane coupling agent, a general formula

[0064]

[Equation 1] , Typically dimethyldichlorosilane,
Trimethylchlorosilane, allyldimethylchlorosilane, hexamethyldisilazane, allylphenyldichlorosilane, benzyldimethylchlorosilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, divinylchlorosilane, dimethylvinyl Chlorosilane etc. can be mentioned.

The silane coupling agent treatment of silica is a dry treatment in which silica is made into a cloud shape by stirring or the like and a vaporized silane coupling agent is reacted, or
The treatment can be carried out by a generally known method such as a wet method in which a silane coupling agent in which silica is dispersed in a solvent is reacted dropwise.

The silicone oil used in the present invention is
Generally, it is shown by the following formula,

[0067]

Embedded image R: C _{1 to} C ₃ alkyl group R ′: alkyl, halogen modified alkyl, phenyl, modified phenyl or other silicone oil modifying group R ″: C _{1 to} C ₃ alkyl group or alkoxy group

Examples thereof include dimethyl silicone oil, alkyl-modified silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone oil.

A known technique is used for the method of treating the silicone oil. For example, fine silica powder and silicone oil may be directly mixed using a mixer such as a Henschel mixer, or the base silica may be sprayed with the silicone oil. It depends on the method. Alternatively, it may be prepared by dissolving or dispersing silicone oil in an appropriate solvent, mixing with the silica fine powder of the base, and then removing the solvent.

The reason why the charging polarity of the spherical particles in the coating layer of the developer carrying member is not clear at present, but a positively chargeable substance is preferable from the viewpoint of image density. Examples of the substance exhibiting a positive charge include resin compounds such as phenol resin, methyl methacrylate resin (PMMA), styrene-butadiene copolymer, and nitrogen-containing resin; metal oxides such as alumina and zinc oxide, but especially methyl. Methacrylate resin (PMMA) is preferred.

The positive chargeability is measured by a usual charge measuring method. For example, mixing spherical particles and metal powder such as iron powder,
It is determined by measuring the triboelectric charge of spherical particles by the blow-off method.

Examples of the binder resin used for the coating layer on the developer carrying member of the present invention include resins such as phenol resin, epoxy resin and polycarbonate resin. Generally, a resin that imparts triboelectric charge to the toner in a positive polarity can be preferably used as the binder resin.

Of these, thermosetting resins are preferable from the viewpoint of manufacturing and durability. A phenol resin is most preferably used because of the charging stability of the toner. Phenolic resins include pure phenolic resins produced from phenol and formaldehyde, and modified phenolic resins in which ester gum and pure phenolic resins are combined, and both can be used. Phenolic resin is preferably used because it forms a dense three-dimensional crosslinked structure by a thermosetting reaction and can form a very hard coating film as compared with other thermosetting resins (polyurethane, polyamide, etc.).

Metal and alloy compounds can be preferably used as the base material of the developer carrying member used in the present invention. In addition, non-metallic materials can also be used.

However, in the configuration of the present invention, since the developer carrying member (developing sleeve) is used as an electrode, a non-metal substance,
For example, when a plastic molded product is used, it is necessary to have a structure capable of energizing. For example, a metal may be adsorbed on the surface of the developer carrier by vapor deposition, or a resin having conductivity may be used.

The solid lubricant used in the present invention is preferably graphite. Both natural products and man-made products can be used as graphite.

As described above, the particle size of graphite is scaly in shape, and cannot be specified in a glance. As will be described later, it is difficult to indicate the range of the particle size of graphite due to the change in shape when dispersed by a stirring means such as a sand mill. The width in the surface direction) is preferably 100 μm or less.

As the measuring method, the method of directly observing the sample with a microscope is the most preferable method. As a simple method, there is a method of obtaining the maximum value by measuring with a normal particle size distribution meter (electric resistance type, sedimentation type, centrifugal type, laser scattering type, etc.).

The degree of graphitization of graphite is 60%.
It is preferable that it is above. This is because the degree of graphitization is a characteristic that affects the susceptibility to breakage, and is a characteristic that is considered to affect the difference between the initial state and the durable state in the film characteristics.

There are various methods for measuring the crystallinity, but evaluation by X-ray diffraction is general and good in reproducibility.

The conductive agent used in the present invention is preferably carbon black. As the carbon black, either a furnace type or a channel type can be used. Of these, low resistance substances are preferable in consideration of the film characteristics,
In particular, the resistance value under pressure of 120 kg / cm ² is
Carbon black of 0.5 Ω · cm or less is preferable.

The addition amount W of carbon black is expressed by the formula W = [{100 / (carbon black oil absorption amount)} × 10 with respect to 100 parts by weight of the binder resin.
It is preferable that 0] × a is satisfied.

However, the oil absorption of carbon black was determined as in Sample 10.
Oil absorption of dibutyl phthalate relative to 0 g [cc / 10
0 g] (ASTM No. D-2414-79), and the coefficient a indicates 0.3 to 3. It is possible to use several kinds of carbon black together, and the oil absorption amount in that case is obtained by actually measuring the mixture.

If the coefficient a is less than 0.3, the effect of adding carbon black is not recognized, and if the coefficient a exceeds 3, the coating hardness decreases, which is not preferable.

The amount of carbon black added is more preferably such that the coefficient a satisfies 0.5 to 2.

Next, the method for producing the developer carrying member of the present invention will be described.

The coating agent used in the present invention has a solid content of 5 in a solvent soluble in a binder resin, for example, phenol resin and an alcohol solvent such as methanol or propyl alcohol.
The raw material of the coating agent is added so that the content of the coating agent becomes about 50 wt%, and the pigment component is dispersed by a stirrer such as a sand mill, a ball mill or an attritor to obtain a coating agent stock solution. A solvent is added to the undiluted solution of the film-forming agent to adjust the solid content to a value suitable for the production method to prepare a coating solution. This coating solution is applied on a developer carrier substrate and dried by touch, and then the coating layer is cured by heating or exposure,
A developer carrier is produced. As a coating method, a spray method, a dipping method, a roller coating method, a bar coating method, or an electrostatic coating method is used.

Next, the composition ratio of each component used in the developer carrying member of the present invention will be described. The following are particularly preferable ranges.

In the present invention, the weight ratio of (graphite) / (binder resin) is in the range of 2/1 to 1/3, which gives particularly preferable results. If it is more than 2/1, the film strength is reduced, and if it is less than 1/3, there is a high possibility that the developer is improperly coated due to the influence of the binder resin.

The addition amount of the spherical particles in the present invention gives a particularly preferable result in the range of 1 to 20 wt% based on the weight of the binder resin. If it is less than 1 wt%, the effect of adding spherical particles is small, and if it exceeds 20 wt%, the development characteristics may be adversely affected.

In the present invention, the following additive substances may be added to the coating. A conductive material may be added to adjust the resistance of the coating. Conductive carbon such as acetylene black or oil black as the conductive substance;
Metal powders such as iron, lead and tin; metal oxides such as tin oxide and antimony oxide. The amount of addition is such that the ratio of added substance / binder resin is in the range of 2/1 to 1/3.

A charge control agent used for the toner may be added to the coating in order to make the charge of the toner more stable. For example, nigrosine, quaternary ammonium salt, boric acid compound,
Examples thereof include phosphoric acid compounds. In each case,
By adding the spherical particles having a particle diameter of 0.3 to 30 μm in the present invention, a stable developer carrier surface can be held.

The roughness of the surface of the developer carrying member in the present invention is in the range of 0.2 to 5.0 (preferably 0.3 to 3) μm as an area average value (hereinafter, Ra), and the surface due to durability is Roughness change rate (after endurance / initial) 0.5-
It is in the range of 2.0. When the surface roughness is less than 0.2 μm, the carrying ability is lowered, which is not preferable. When the surface roughness exceeds 5.0 μm, the developer coating layer becomes thick and scattering and irregular development become conspicuous, which is not preferable. The rate of change in roughness is measured to confirm that the change in surface roughness due to the durability achieved by the present invention is small.

For the surface of the developer-carrying member, the relationship between the average pitch of roughness (Sm), which is the average interval of irregularities on the surface of the coating film, and the average particle diameter (d _av ) of the toner of the developer is Sm / d _av. = 1/10 to 10, preferably 1/5 to 5
And the roughness (Ra) of the coating surface is 0.3 to 3 μm,
It is preferably 0.5 to 3 μm.

Length direction (Sm value) and height direction (Ra value)
These two points were used as the representative values of the surface condition. Where Sm / d _av
If the value is smaller than 1/10, the roughening effect does not appear, and if it is larger than 10, the surface becomes close to a smooth surface with respect to the toner size, and thus the roughening effect does not appear.

In the present invention, the center line average roughness (Ra)
Is measured using a surface roughness measuring device (Surfcoder SE-30H, Kosaka Laboratory Ltd.) based on JIS surface roughness (BO601). Specifically, the center line roughness (R
a) is the measured length a from the roughness curve in the direction of its center line.
A 2.5 mm portion is extracted, the center line of the extracted portion is the X axis, the vertical magnification direction is the Y axis, and the roughness curve is y = f.
When expressed by (x), the value obtained by the following equation is
It is expressed in micrometers (μm).

[0097]

[Equation 2]

In the present invention, the uneven average spacing (S
m) is Sm = L / n (where L is the reference length,
2.5 mm, and n indicates the number of peaks). The number of peaks n is two peak average levels (± 0.21 μm) provided on the center line of the roughness curve, and between the two points where the lower peak count level and the curve intersect, the upper peak count level. When there is a point at which the level and the curve intersect one or more times, it is regarded as one mountain, and this number of mountains n is used as a reference length (2.
5 mm).

A substance having a low surface energy may be added in order to accelerate the release of the developer from the surface of the developer carrying member. For example, fluorine compounds, boron nitride, graphite, etc. may be mentioned.

On the other hand, as the binder resin (polymer component) of the toner according to the present invention, a homopolymer of styrene such as polystyrene and polyvinyltoluene or a substitution product thereof; styrene-propylene copolymer, styrene-vinyltoluene copolymer Polymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer,
Styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene-methylmethacrylate copolymer, styrene-ethylmethacrylate copolymer, styrene-butylmethacrylate copolymer, Styrene-dimethylaminoethyl methacrylate copolymer, styrene-vinyl methyl ether copolymer,
Styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer, etc. Styrene-based copolymers; polymethylmethacrylate, polybutylmethacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral,
Silicone resin, polyester resin, polyamide resin, epoxy resin, polyacrylic resin, rosin, modified rosin, tempel resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, paraffin wax, carnauba wax, etc. Can be used alone or in combination.

As the charge control agent for the toner according to the present invention, in the case of a negative charge control agent, a positive charge control agent such as a metal complex salt of a monoazo dye, a metal complex salt of salicylic acid, an alkylsalicylic acid, a dialkylsalicylic acid or a naphthoic acid is used. In this case, a nigrosine dye, an azine dye, a triphenylmethane dye or pigment, an imidazole compound, a quaternary ammonium salt or a polymer having a quaternary ammonium salt in its side chain can be used alone or in combination.

To prepare the toner of the present invention, the polymer component of the present invention and the pigment, dye or magnetic material as a colorant, charge control agent, other additives, etc. are thoroughly mixed by a mixer such as a ball mill. Then, using a heat kneader such as a heating roll, a kneader, or an extruder, the pigments or dyes are dispersed or dissolved in the resin, which is melted, kneaded, and kneaded to make the resins compatible with each other, and crushed after cooling and solidification. And the toner according to the present invention can be obtained by performing strict classification.

As another method for obtaining the toner according to the present invention, the toner can be manufactured by a polymerization method. This suspension polymerization method toner comprises a polymerizable monomer, the charge control agent of the present invention, a pigment or dye, magnetic iron oxide, a polymerization initiator (and a crosslinking agent and other additives, if necessary).
In a continuous phase (for example, water) containing a dispersion stabilizer after uniformly dissolving or dispersing the above to prepare a monomer composition. Are dispersed by using a suitable stirrer, and at the same time, a polymerization reaction is performed to obtain toner particles having a desired particle diameter.

An example of the image forming apparatus is schematically shown in FIG. 1, and the image forming method will be described based on it.

Reference numeral 1 denotes a rotary drum-shaped electrostatic latent image carrier, around which a primary charging device 2, an exposure optical system 3, a developing device 4 having a toner carrier 5, a transfer device 9 and a cleaning device 11 are provided. It is arranged.

In this image forming apparatus, the surface of the electrostatic latent image carrier 1, which is a photoconductor, is uniformly charged by the primary charging device 2, and the electrostatic latent image carrier is imagewise exposed by the exposure optical system 3. An electrostatic latent image is formed on the surface of 1.

Then, on the surface of the toner carrier 5 containing a magnet, a toner layer thickness regulating member 6 was used to form a toner coat layer (in the present invention, 1.05 to 2.8 mg per 1 cm ² ). (More preferably 1.23 ~
2.45 mg) is preferred. ) Is formed, and an alternating bias, a pulse bias and / or a DC bias are applied by the bias applying means 8 between the conductive substrate of the electrostatic latent image carrier 1 and the toner carrier 5 in the developing section, The electrostatic latent image formed on the latent image carrier 1 is developed.

The developed toner image is electrostatically transferred onto the transfer paper P by carrying the transfer paper P, applying a charge having a polarity opposite to that of the toner from the back surface of the transfer paper P by the transfer device 9 and the voltage applying means 10. .

The transfer paper P on which the toner is transferred is passed through the heating and pressure roller fixing device 12 to obtain a fixed image.

The magnetic toner remaining on the latent image carrier after the transfer step is removed by the cleaning device 11, and the steps of primary charging and below are repeated again.

[0111]

EXAMPLES The present invention will be described below with reference to specific examples, but the present invention is not limited thereto.

[Production Example of Oil-treated Silica (A-1)]
Silica fine powder synthesized by dry method (specific surface area 200 m ²
/ G) 100 parts by weight of hexamethyldisilazane 10
1 part by weight, then 10 parts by weight of dimethyl silicone oil (100 cSt) was diluted with hexane, and then heated from room temperature to about 250 ° C. and heat-treated to obtain oil-treated silica A-1. . The average particle size was 0.02 μm.

The average particle size in the present invention was calculated from the true specific gravity and specific surface area of treated silica according to the following formula.

[0114]

(Equation 3)

The average particle diameter calculated from the specific surface area is not good for a porous material, but the oil-treated silica of the present invention can be adapted by oil-treating the surface of the silica particles and can be measured by observation. Matches well.

The specific surface area was determined according to the BET method by using a specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics Co., Ltd.) to adsorb nitrogen gas on the sample surface, and calculating the specific surface area using the BET multipoint method.

The average particle size in the present invention is measured by
Scanning electron microscope (SE
M) and a transmission electron microscope (TEM) may be used.

[Production Example of Oil-treated Silica (B-1)]
Silica fine powder synthesized by wet method (specific surface area 110 m ²
40 parts by weight of dimethyl silicone oil (12 g / g)
It was treated with 60 parts by weight of 500 cSt) to obtain oil-treated silica B-1.

The average particle size of the oil-treated silica B-1 was about 8 μm.

[Production Example of Oil-Treated Silicas A-2 to A-4] A-2 to A-in the same manner as the oil-treated silica A-1.
4 oil-treated silica was obtained. The formulation and physical properties are shown in Table 1.

[Production Example of Oil-treated Silica B-2 to B-4] B-2 to B-in the same manner as the oil-treated silica B-1.
4 oil-treated silica was obtained. The formulation and physical properties are shown in Table 1.

[0122]

[Table 1]

(Toner Production Example 1) Styrene acrylic copolymer 100 parts by weight Magnetic iron oxide 100 parts by weight Negative charge control agent (the following formula) 2 parts by weight

[0124]

Embedded image

The above mixture was melt-kneaded with a twin-screw extruder heated to 140 ° C., the cooled kneaded product was coarsely pulverized with a hammer mill, and the coarsely pulverized product was finely pulverized with a jet mill. The powder was classified by a fixed wall type air classifier to produce classified powder. Furthermore, the weight-average particle diameter (D ₄ ) is obtained by strictly classifying the obtained classified powder at the same time by strictly classifying and removing ultrafine powder and coarse powder with a multi-division classifier utilizing the Coanda effect (Elbow Jet classifier manufactured by Nittetsu Mining Co., Ltd.). 6.8 μm, density 1.7
A negatively chargeable magnetic toner of 5 g / cm ³ was obtained.

100 parts by weight of this magnetic toner, 1.2 parts by weight of oil-treated silica A-1, oil silica B-1
Magnetic toner (Toner No. A) was prepared by mixing 0.1 part by weight of the toner with a Henschel mixer.

(Toner Production Examples 2-5, Comparative Examples 1-5) Toner B having the toner constitution shown in Table 2 in the same manner as in Example 1-
I got J.

[0128]

[Table 2]

(Production Example of Developing Sleeve) Production Example-a Graphite 100 parts by weight (Showa Denko KK; UFG-10, graphitization degree 100%, major axis diameter 5 μm, thickness 0.5 μm or less) Resol type phenol resin 100 parts by weight PMMA (Positive charging, average particle size 2 μm) 4 parts by weight

The above coating material was added to 76 parts by weight of butyl alcohol, mixed, and then dispersed for 10 hours in a ball mill containing balls having a diameter of 200 μm as media particles. Then, the balls were separated using a 64 mesh sieve to obtain a stock solution (solid content: 24 wt%). This stock solution is called stock solution-a.

20 parts by weight of butyl alcohol was added to the stock solution-a to prepare a coating solution (solid content 20 wt%). A coating film of 10 μm is formed on an Al carrier substrate (aluminum cylinder) having a diameter of 20 mm by using the coating solution by a dipping method, and then the coating film is heated in a hot air drying oven to cure at 150 ° C./30 minutes and a developer carrier (sleeve). Was prepared.

The surface roughness (Ra) of the coating layer formed on the aluminum substrate was 2.5 μm.

Production Example-b Graphite 100 parts by weight (Showa Denko KK; UFG-10, major axis diameter 5 μm) Epoxy resin 100 parts by weight Spherical alumina particles 5 parts by weight (Positive charging, number average particle size 0.3 μm, Sphericity S1.0)

The above material was used as normal propyl alcohol 7
After adding 5 parts by weight and mixing, dispersion was carried out with a sand mill filled with steel balls having a diameter of 1 mm, and after the dispersion, the steel balls were removed to obtain a stock solution (solid content 25 wt%).

This stock solution is designated as stock solution-b.

A developer carrying member was obtained in the same manner as in Production Example-1 except that the stock solution-b was applied as it was by a spray method and cured by ultraviolet rays.

Comparative Production Example-c The surface was roughened by sandblasting in order to provide the same surface roughness (Ra = 2.5 μm) as in Production Example-a on an aluminum carrier substrate having a diameter of 20 mm.

Comparative Production Example-d A developer carrying member was prepared in the same manner as in Production Example-a except that the number average particle diameter of PMMA resin particles was 40 μm among the materials in Production Example-a.

Comparative Production Example-e A developer carrying member was prepared in the same manner as in Production Example-b except that the spherical alumina particles among the materials in Production Example-b had a particle size of 0.02 μm.

<Examples 1 to 6 and Comparative Examples 1 to 8> Using the toners A to J and the sleeves a to e described above, a laser beam printer LBP-A309G II manufactured by Canon was used in a high temperature and high humidity environment (35 ° C./90° C.). % RH) and the image formation was evaluated.

The evaluation method is as follows, and the results are shown in Table 3.

(1) Dod reproducibility The pattern shown in FIG. 2 was printed out and its dot reproducibility was evaluated.

⊚: Very good (2 defects or less / 100 defects) ◯: Good (3 to 5 defects / 100 defects) Δ: Normal (6 to 10 defects / 100 defects) ×: Worse than normal ( 11 or more defects / 100 defects)

(2) Scattering Scattering of toner in the printed image was visually evaluated.

⊚: Very good O: Good Δ: Normal ×: Poor than normal

(3) Toner chargeability Only in the developing device portion, the peripheral speed of the sleeve is set to 150 at a high temperature and high humidity environment.
Rotation at a speed of 3 mm / sec. After 5 hours. Then, after leaving (5 days), after leaving for another 3 min. It was measured later.

For the measurement of the tribovalue on the developer carrying member, a measuring container having a cylindrical filter paper was used, a metal suction port was attached along the shape of the surface of the developer carrying member, and immediately after image formation (within 5 minutes). Is preferable), and the developer is sucked by adjusting the suction pressure so that the developer layer on the surface of the developer carrier can be sucked uniformly without excess or deficiency. The developer weight sucked at this time is M
(G) and calculated by Qm = CV / M.

[0148]

[Table 3]

[0149]

As described above, according to the present invention, the coating layer is composed of a solid lubricant, a conductive agent, a spherical particle having a defined particle size and a binder resin, and at least a particle size. By using a toner to which two kinds of different silicone oil-treated silicas, whose oil treatment amount and addition amount to the toner are specified, are used, high image quality (dot reproducibility, prevention of toner scattering) can be achieved.

Furthermore, the influence of temperature and humidity is small, and stable toner chargeability can be obtained over a long period of time.

Furthermore, it is possible to achieve an image forming method in which the toner charge rises quickly.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an example of an image forming apparatus used in an image forming method of the present invention.

FIG. 2 is an illustration of a checkered pattern for testing toner development characteristics.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Latent image carrier 2 Primary charging device 3 Exposure optical system 4 Developing device 5 Toner carrier (developing sleeve) 6 Toner layer thickness regulating member 7 Toner stirring means 8 Developing bias power source 9 Transfer device 10 Transfer current generating device 11 Cleaning means 12 Fixing device 13 Toner

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 5, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0143

[Correction method] Change

[Correction content]

⊚: Very good (2 or less defects / 100 defects) ○: Good (3 to 5 defects / 100 defects) Δ: Normal (6 to 10 defects / 100 defects) Δ ×: Slightly worse than normal (11 to 15 defects / 100 defects) x: Bad ( 16 defects or more / 100 defects)

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0145

[Correction method] Change

[Correction content]

⊚: Very good O: Good Δ: Normal Δx: Slightly worse than normal ×: Bad

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0148

[Correction method] Change

[Correction content]

[0148]

[Table 3]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nahokuni Kobori 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (9)

[Claims] 1. A developer carrier has at least a substrate and a coating layer, and the surface of the substrate is coated with the coating layer. The coating layer comprises (i) a solid lubricant, a conductive agent or a solid lubricant. And (ii) a number average particle diameter of 0.3 to 3
The toner used is formed of a coating material containing spherical particles of 0 μm and (iii) a binder resin. The toner used is formed of a composition containing at least a polymer component and a charge control agent, and contains at least silicone. Having oil-treated silica A and silica B,
The silicone oil-treated silica A and silica B
However, the following conditions a) The average particle diameter of silica is 10 A ≦ B b) The amount of silicone oil treated is 2 A ≦ B c) The addition amount (weight ratio) to the toner satisfies A ≧ 3 B Image forming method. 2. A thin layer of magnetic toner is formed on a developer carrying body which is arranged with a certain gap from the electrostatic latent image carrying body, and the developer carrying body and the latent image carrying body are further formed. The image forming method according to claim 1, further comprising a step of developing the electrostatic latent image on the electrostatic latent image carrier with the magnetic toner while applying an alternating current therebetween. 3. The silicone oil-treated silica A has an average particle diameter of 0.1 μm or less, and the silicone oil-treated silica B has an average particle diameter of 0.5 μm or more and 50 μm or less. The image forming method described in 1 .. 4. The oil treatment amount of the silicone oil-treated silica A is 1 to 30% by weight based on the treated silica,
The method for forming an image according to claim 1, wherein the amount of oil treated with the silicone oil-treated silica B is 30 to 90% by weight with respect to the treated silica. 5. The amount of the silicone oil-treated silica A added to the toner is 0.3 to 3.0% by weight, and the amount of the silicone oil treated silica B added to the toner is 0.005 to 0.5% by weight. The image forming method according to claim 1, wherein 6. The image forming method according to claim 1, wherein the treated oil viscosity of the silicone oil-treated silicas A and B is 10A ≦ B. 7. The image forming method according to claim 1, wherein the solid lubricant of the developer bearing member is graphite. 8. The image forming method according to claim 1, wherein the conductive agent of the developer carrying member is carbon black. 9. The image forming method according to claim 1, wherein the spherical particles of the developer carrying member are a methyl methacrylate resin (PMMA).