JPH08220798A - Image forming method - Google Patents

Abstract

PURPOSE: To provide an image forming method by which rising for electrification of a toner is fast and an image of high image quality can be obtd. CONSTITUTION: This image forming method includes a process to form a toner layer on a toner holding body which faces an electrostatic latent image holding body and to develop an electrostatic latent image on the electrostatic latent image holding body. The coating amt. w (mg) of the toner layer per unit area (1cm<2> ) formed on the toner holding body and the absolute density of the toner ρ(g=/cm<3> ) and in the relation of w/ρ=0.2 to 0.8. The toner holding body is moved by 1.05-3.0 times as fast as the moving rate of the surface of the electrostatic latent image holding body. Two kinds of silica (A) and (B) are used to satisfy that (a) the average particle diameter is 10A<=B, (b) the amt. of silicone oil used to treat silica is 2A<=B, and (c) the amt. of silica added to the toner (weight ratio) is A>=3B.

Description

Detailed Description of the Invention

[0001]

The present invention relates to electrophotography, electrostatic printing,
The present invention relates to an image forming method such as magnetic recording.

[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.

As the developing method, a one-component developing method is preferably used from the viewpoints of downsizing, weight saving and maintenance-free of the apparatus.

Among them, the toner carrier and the electrostatic latent image carrier are arranged with a certain gap therebetween, and a thin layer of magnetic toner which does not come into contact with the latent image carrier is formed on the toner carrier, and further the toner is formed. A jumping development method in which an alternating electric field is applied between a carrier and a latent image carrier to perform development (Japanese Patent Publication No. 58-3
2375 gazette) are preferably used.

This method increases the chances of contact between the sleeve and the toner by applying the magnetic toner very thinly on the sleeve, and enables sufficient triboelectrification. The magnetic toner supports the magnetic toner and the magnet is used. By relatively moving the toner, the toner particles are prevented from agglomerating with each other and sufficiently rubbed with the sleeve, and the like, whereby an excellent image can be obtained.

Further, since the thin toner layer of the toner carrier is not in contact with the latent image carrier, the life is long even when an organic photoconductor which is inexpensive and easy to mass-produce is used, and it is suitable for speeding up. You can

On the other hand, as a toner, treatment of various fine inorganic oxide powders has been studied for the purpose of improving the fluidity of the toner, the charging characteristics, and the environmental resistance 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 insufficient for the high image quality, high transferability, high durability and environmental resistance required in recent years. In particular, it is insufficient in terms of further reduction of fog in terms of image quality and high transferability.

Further, JP-A-61-249059 discloses a magnetic developer carrying hydrophobic silica and silicone oil-treated hydrophilic silica on the toner surface.
AC applying a toner containing inorganic oxide particles and the specific surface area of 100 m ² / g or more inorganic oxide particles is a specific surface area of 10 to 100 m ² / g surface treated with a silicone oil in JP-A-4-264453 A structure for reducing fogging by using the developing method is disclosed.

However, within the range of the above configuration, there are the same problems as those described above. Further, there are problems in toner charging stability and environmental stability in high-speed printing.

It is required to find a toner that solves the above problems, an image forming system that fully utilizes the characteristics of the toner, and appropriate image forming conditions.

[0014]

SUMMARY OF THE INVENTION It is an object of the present invention to significantly improve the drawbacks of the prior art, to achieve high image quality, high transferability,
An object of the present invention is to provide an image forming method having high durability and excellent environmental stability.

It is a further object of the present invention to provide an image forming method which achieves a long life of the toner and each member in contact with the toner in order to increase the speed of the apparatus which is required in recent years.

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

[0017]

SUMMARY OF THE INVENTION According to the present invention, a toner layer is formed on a toner carrier facing the electrostatic latent image carrier to develop the electrostatic latent image on the electrostatic latent image carrier. In the image forming method having the step of: a coating amount per unit area of the toner layer formed on the toner carrier is w / ρ = 0.2 to 0.8 w; toner per 1 cm ² of the surface of the toner carrier. Coat weight (mg) ρ; set so as to satisfy toner true density (g / cm ³ ), and the moving speed of the toner carrier surface in the developing region is 1.05 with respect to the electrostatic latent image carrier surface moving speed. .About.3.0 times the speed, and the toner is
It 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, and the silicone oil-treated silica A and silica B have the following conditions: ) The average particle diameter of silica is 10 A ≤ B b) The treatment amount of silicone oil is 2 A ≤ B c) The addition amount (weight ratio) to the toner satisfies A ≥ 3 B, and the present invention relates to an image forming method.

Further, the present invention is characterized in that the toner is a magnetic toner, the electrostatic latent image carrier and the toner carrier have a certain gap, and development is performed while applying an alternating electric field. It relates to a forming method.

Further, in the present invention, the toner coat amount is w / ρ.
= 0.3 to 0.7, the present invention relates to an image forming method.

Further, the present invention relates to an image forming method characterized in that the magnification of the moving speed of the surface of the toner carrying member with respect to the moving speed of the surface of the electrostatic latent image carrying member in the developing area is 1.1 to 2.5 times.

The present invention further relates to an image forming method characterized in that the average roughness Ra of the surface of the toner carrier is 1.5 or less.

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.

Further, in the present invention, the addition amount of the silicone oil-treated silica A 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.

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

A toner containing two kinds of silica treated with silicone oil, A and B, having the above-mentioned constitution is used, and the supply amount of the toner to the toner carrier is w / ρ = 0.2 to 0.8.
(Preferably 0.3 to 0.7), the moving speed of the toner carrier surface in the developing area is 1.05 to 3.0 times the moving speed of the electrostatic latent image carrier surface ( By setting it as high as possible (preferably 1.1 to 2.5 times), the rise of charging is fast, the influence of the environment of temperature and humidity is small, and a stable toner coat layer having a high charge amount can always be obtained, and a latent image can be obtained. It is possible to obtain a high-quality image that is faithful and sharp in development, has improved transfer reproducibility, is free from fog, has a high image density, and has a long-term durability.

Even when the constitution of the present invention is applied at a high process speed, deterioration due to toner fusion to the toner carrier or electrostatic latent image carrier or deterioration of the toner itself is small, and it is very stable. Shows the durability.

By using the toner having the above-mentioned structure, since adhesion is unlikely to occur in terms of surface energy and the toner has an appropriate sliding property, the mechanical load applied to the toner is dispersed, and the characteristic that it is hard to fix is obtained. Even under severe operating conditions such as rotating the toner carrier at a high speed with a small amount of toner supplied, deterioration of the toner itself or deterioration of the toner itself due to toner fusion to the toner carrier or electrostatic latent image carrier, filming, etc. Since the amount is small, the toner supply amount on the toner carrier is w / ρ = 0.2 to 0.8 (preferably 0.3 to 0.7).
And the moving speed of the toner carrier surface in the environmental region is 1.05 to 3.0 times (preferably 1.1 to 2.5 times) the moving speed of the electrostatic latent image carrier surface. It is possible to set a high value, and under this condition, the charge amount of the toner is high and the distribution is narrow, the rise of the charge is fast, the latent image is faithful and sharp, and the transfer reproducibility is improved. .

The relationship between the coat amount per unit area of the toner thin layer formed on the toner carrier and the true density of the toner w /
If ρ is less than 0.2, if there is a portion requiring a large amount of toner for development over a wide area, such as solid black,
The toner supply amount to the latent image is insufficient and the image density becomes low. In addition, toner sticking to the toner carrier may occur, which is not preferable. On the other hand, when it exceeds 0.8, the distribution of the toner charge amount becomes wide in the constitution of the present invention, and the fog easily occurs. In addition, the reproducibility during development and transfer is reduced.

As the true density of the toner, data measured by a dry automatic densimeter "Acupic 1330" manufactured by Shimadzu Corporation was used.

If the moving speed of the surface of the toner carrying member is less than 1.05 times the moving speed of the surface of the electrostatic latent image carrying member, the reproducibility of development transfer is not sufficient, and it is often used for development over a wide area such as solid black. If there is a part that requires the toner amount of
The toner supply amount to the latent image is insufficient and the image density becomes low.
If it exceeds 3.0, the toner may be deteriorated or adhered to the toner carrier, which is not preferable.

In order to achieve the toner coating amount w / ρ of the present invention, the average roughness Ra of the surface of the toner carrier is preferably 1.5 or less, and when Ra exceeds 1.5, the present invention is It becomes difficult to control the coating amount range per unit area of the magnetic toner thin layer formed on the toner carrier.

Here, the center line average roughness (Ra) is JIS
It is measured based on the surface roughness (BO601) using a surface roughness measuring device (Surfcoder SE-30H, Kosaka Laboratory Ltd.). Specifically, center line roughness (Ra)
Is the measured length a2.5 from the roughness curve in the direction of its center line.
Remove the part of mm and set the center line of this part to X
When the axis and the direction of longitudinal magnification are represented by the Y axis and the roughness curve is represented by y = f (x), the value obtained by the following formula is represented by micrometer (μm).

[0034]

[Equation 1]

As the toner carrier used in the present invention, a cylindrical or belt-shaped member made of, for example, stainless steel, aluminum or the like is preferably used. If necessary, the surface may be coated with metal, resin, etc.
A resin in which fine particles such as resin, metals, carbon black, and charge control agent are dispersed may be coated.

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 average particle size of oil-treated silica A is 0.1
If it exceeds μm, sufficient toner fluidity cannot be obtained, which adversely affects the toner charging property and the like. If the average particle size of the oil-treated silica B is less than 0.5 μm, the reproducibility during development and transfer will be insufficient. When the difference in particle size between the oil-treated silicas A and B is less than 10 times, the balance between the fluidity of the toner and the reproducibility during development and transfer is poor.

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. .

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 amount of oil processed outside the above range, the fluidity of the toner and development,
The balance with the reproducibility at the time of transfer becomes poor.

Further, the addition amount (weight ratio) to the toner
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 becomes insufficient.

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 diameter is 10 times or more the viscosity of the oil of the oil-treated silica A having a small particle diameter.

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

If it is out of the above range, the effect of the present invention is not sufficiently exhibited.

As a more preferred structure of the present invention, the atomic ratio of the Si atoms originating from the silicone oil to the Si atoms originating from the matrix silica (oil Si / silica Si) on the surface of the oil-treated silica B is 1 ≦ oil Si. / Silica Si ≦ 10 is preferable.

The above atomic ratio represents the amount of oil on the surface of the oil-treated silica B, and the Si atomic ratio (oil Si
/ Silica Si) is less than 1, the effect of the present invention is not sufficiently exhibited, and conversely, when it is more than 10, the toner fluidity is deteriorated and the image durability is adversely affected. In the present invention, the Si atomic ratio (oil Si / silica Si) was measured by XPS under the following conditions.

XPS measuring device; ESCALA manufactured by VG
B, 200-X type X-ray photoelectron spectrometer X-ray source; Mg Kα (300 W) analysis region; 2 × 3 mm

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 possible to obtain a composite fine 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

[0051]

[Equation 2] , Typically dimethyldichlorosilane,
Trimethylchlorosilane, allyldimethylchlorosilane, hexamethyldisilazane, allylphenyldichlorosilane, benzyldimethylchlorosilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, divinylchlorosilane, dimethylvinyl Chlorosilane etc. can be mentioned.

The above-mentioned silica treatment with a silane coupling agent 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,

[0054]

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.

On the other hand, as the binder resin (polymer component) of the toner according to the present invention, homopolymers of styrene such as polystyrene and polyvinyltoluene and their substitution products; 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.

The toner of the present invention preferably contains a charge control agent, and in the case of a negatively chargeable toner, a negative charge 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. A control agent is used. In the case of the positively charged toner, a positively charged control agent such as 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 is used.

Further, the toner of the present invention is preferably a magnetic toner, and the magnetic toner contains a magnetic material although it may serve as a colorant. The magnetic material contained in the magnetic toner of the present invention includes magnetite and γ-
Iron oxides such as iron oxides, ferrites, and iron-rich ferrites;
Metals such as iron, cobalt, nickel or these metals and aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium. Examples include alloys of various metals and mixtures thereof.

In some cases, the magnetic material used in the magnetic toner of the present invention may be treated with a silane coupling agent, a titanium coupling agent, a titanate, an aminosilane or an organosilicon compound.

If desired, the toner of the present invention may be mixed with other additives (internal additive or external additive). As the coloring agent, conventionally known dyes and pigments can be used, and usually 0.5 to 100 parts by weight of the binder resin.
~ 20 parts by weight may be used. Examples of other additives (external additives) include lubricants such as zinc stearate, abrasives such as cerium oxide and silicon carbide, and conductivity imparting agents such as carbon black and tin oxide.

For the purpose of improving releasability at the time of fixing, wax-like substances such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, sazol wax and paraffin wax are contained in an amount of about 0.5 to 5% by weight. Addition to the toner is also one of the preferable modes of the present invention.

To prepare the toner of the present invention, the polymer component of the present invention and pigments, dyes or magnetic materials as colorants, charge control agents, 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 a preferable form of 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, a toner coat layer is formed on the surface of the toner carrier 5 containing a magnet by the toner layer thickness regulating member 6 according to the constitution of the present invention, and the electrostatic latent image carrier 1 is electrically conductive in the developing portion. The electrostatic latent image formed on the electrostatic latent image carrier 1 is developed while applying an alternating bias, a pulse bias and / or a DC bias by the bias applying means 8 between the conductive substrate and the toner carrier 5.

The developed toner image is electrostatically transferred onto the transfer paper P by carrying the transfer paper P and 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 has been 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.

[0072]

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 diameter in the present invention was calculated from the true specific gravity and specific surface area of treated silica according to the following equation.

[0075]

(Equation 3)

The average particle diameter calculated from the specific surface area is not satisfactory 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.

The surface of the oil-treated silica B-1 was analyzed by XPS, and it was found that the ratio of Si atoms derived from silicone oil to Si atoms derived from the matrix silica (oil Si / silica Si) = 4.5. there were.

[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 and B-3] Similar to the oil-treated silica B-1, B-2 and B-
3 oil-treated silica was obtained. The formulation and physical properties are shown in Table 2.

[0083]

[Table 1]

[0084]

[Table 2]

(Toner Production Example) Styrene-acrylic copolymer 100 parts by weight Magnetic iron oxide 100 parts by weight Ethylene-propylene low molecular weight wax 3 parts by weight Negative charge control agent (the following formula) 2 parts by weight

[0086]

Embedded image

The above mixture was melt-kneaded with a twin-screw extruder heated to 140 ° C., cooled and solidified, then finely pulverized with a jet mill, and then ultrafine powder was obtained with a multi-division classifier (elbow jet classifier manufactured by Nittetsu Mining Co., Ltd.). The powder was simultaneously classified and removed to obtain negatively chargeable magnetic toner particles having a weight average particle diameter (D ₄ ) of 6.5 μm.

100 parts by weight of the magnetic toner particles are shown in Table 3.
Magnetic additives A to H were obtained by mixing the external additives as shown in (1) with a Henschel mixer.

[0089]

[Table 3]

<Example 1> Using magnetic toner A, laser beam printer LBP-A4304G manufactured by Canon Inc.
The image was evaluated by modifying II to have the following settings.

As the toner carrier, a sleeve (center line average roughness Ra = 0.
5), an elastic blade made of urethane was brought into contact with the sleeve at a linear pressure of 20 g / cm to regulate the toner layer thickness. In addition, 1 cm of the toner thin layer on the toner carrier at the initial stage
The toner coat amount per ² was set to 0.7 mg, and w / ρ at that time was 0.4.

An OPC drum is used as the electrostatic latent image carrier, the peripheral speed thereof is 110 mm / sec, and the peripheral speed of the developing sleeve set with a gap of 250 μm from the OPC drum is set to 165 mm / sec. The peripheral speed was 1.5 times.

The photosensitive drum is primary charged to V _D = -600 V, and the surface thereof is scanned with a laser beam of a minute spot according to an image pattern to form an electrostatic latent image of V _L = -170 V, and an AC bias is applied. f = 1800 Hz, Vp
p = 1400V, and DC bias V _DC = -450V
Was applied to the developing sleeve carrying toner to develop the electrostatic latent image on the surface of the OPC to form a magnetic toner image.

The formed magnetic toner image is transferred by applying a positive charge from the back of the transfer paper by a transfer device in which a transfer roller having a conductive elastic layer is brought into contact with an OPC drum at a contact pressure of 50 g / cm, Further, a fixed image was obtained by passing through a heating and pressure roller fixing device.

Under the above setting conditions, low temperature and low humidity (15 ° C / 1
0% RH environment and high temperature and high humidity (32.5 ° C / 85%
In a (RH) environment, a durability image output test was performed intermittently for 2 sheets / 20 sec. In a low temperature and low humidity environment, 20,000 sheets were printed while replenishing toner successively, and in a high temperature and high humidity environment, 5,000 sheets were printed, then left in the same environment for 2 days, and further 5,000 sheets were printed. .

In this durability test, evaluation was performed as follows.

(1) Image Density Rise In the durability of each environment, a solid black image was printed at the initial stage and when 100 sheets were printed, and the difference between the image densities was evaluated according to the following criteria.

⊚ (Excellent): Density difference of 0.03 or less ○ (Good): Density difference of 0.05 or less Δ (Fair): Density difference of 0.1 or less × (Not possible): Density difference of Δ Less than

(2) Durability Stability (Image Density, Fog) In each environment durability, every 1000 sheets, nine 5 mm square solid blacks (three rows and three rows), full solid black, all white images are printed. Then, the image density and fog were measured and evaluated as follows. The image density was evaluated by using the "Macbeth reflection densitometer" (manufactured by Macbeth Co., Ltd.) to measure the relative density of a white background portion having a document density of 0.00 with respect to the printed image, and evaluated according to the following criteria. For the fog, the whiteness of the transfer paper before printing was measured in advance using a reflectometer (manufactured by Tokyo Denshoku Co., Ltd.), and the value at one point where the difference between the whiteness and the whiteness was the maximum was measured. , The maximum value was recorded throughout the endurance.

Criteria for image density durability stability: ⊚ (excellent): 5 mm square, solid black density is 1.4 or more throughout durability ○ (Good): 5 mm square, solid black density is 1.35 throughout durability Above Δ (normal): Image density through durability is 5 mm square 1.
35, whole solid black 1.3 or more × (bad): Image density is below the level of Δ

(3) Image Quality 100 μm, which is more likely to scatter than the scatter on the character lines at the initial stage and at the time of 10,000 sheets, in the durability of each environment.
A grid pattern (interval of 1 cm) on the (latent image) line was printed, and the scattering and the sharpness of the line were enlarged by an optical microscope and visually evaluated.

⊚ (excellent): Lines are very sharp and hardly scattered ○ (Good): Lines are slightly sharp and lines are relatively sharp △ (Normal): Lines are slightly scattered and the lines look dull X (bad): Less than the level of △

On the other hand, after the printout test was completed, the state of sticking of the residual toner on the surface of the developing sleeve and the influence on the printout image were visually evaluated.

⊚: Very good (not generated) ◯: Good (nearly generated) Δ: Normal (fixed but little influence on image) ×: Poor (many fixed and uneven image)

Similarly, the occurrence of scratches on the surface of the photosensitive drum and the adhesion of residual toner and the influence on the printout image were visually evaluated.

⊚: Very good (not generated) ◯: Good (slightly scratched, but does not affect the image) Δ: Normal (fixed or scratched, but has little effect on the image ) ×: Poor (many fixed, causing vertical stripe image defects)

The above results are summarized in Table 4.

<Examples 2 and 3> The toner coating amount w / ρ is adjusted as shown in Table 4 by changing the free length of the elastic blade (the length from the contact point with the sleeve to the end). Was evaluated in the same manner as in Example 1.

<Examples 4 and 5> Evaluations were made in the same manner as in Example 1 except that the peripheral speed ratio of the toner carrier / latent image carrier was changed as shown in Table 4.

Examples 6 to 8 Table 4 shows the toner carrier / latent image carrier peripheral speed ratio and toner using an aluminum tube sleeve (center line average roughness Ra = 0.2) as the toner carrier. Evaluation was performed in the same manner as in Example 1 except that the changes were made as shown.

Table 4 is a summary of the above results.

The results of Examples 1 to 8 all have sufficient toner fluidity, excellent development fidelity and transfer reproducibility.
Moreover, even in each environment, the concentration durability was excellent, and the good result with a low fog level was shown.

Contamination such as toner adhesion to the sleeve and drum was at a level without problems.

<Comparative Example 1> As a toner carrier, an aluminum sleeve having a blasted surface was coated with a resin (center line average roughness Ra = 1.8), and the toner coating amount w / ρ was used.
Evaluation was performed in the same manner as in Example 1 except that

Comparative Examples 2 to 6 The toner coating amount w / ρ, the toner carrier / latent image carrier peripheral speed ratio, and the toner are adjusted as shown in Table 4 by changing the free length of the elastic blade. The evaluation was performed in the same manner as in Example 1 except for the above.

The results are summarized in Table 4.

The results of Comparative Examples 1 to 6 are as follows: toner fluidity, development fidelity, transfer reproducibility, density durability in any environment, fogging, stains such as toner sticking to the sleeve / drum. At least one item was a bad result.

[0118]

[Table 4]

[0119]

As described above, the present invention uses a toner to which two kinds of silicone oil-treated silica having at least a particle size, a silicone oil treatment amount, and an addition amount with respect to the toner are specified, and is used on a toner carrier. By defining the coating amount w / ρ of the magnetic toner thin layer formed per unit area per unit area and the moving speed ratio between the toner carrier surface and the electrostatic latent image carrier surface in the developing area, sufficient toner fluidity and development can be obtained. , The transfer reproducibility is excellent, and the deterioration due to the toner fusion to the toner carrier and the electrostatic latent image carrier,
There is little deterioration of the toner itself, enabling long-term durability, environmental stability, and reduction of fog.

[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.

[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

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[Procedure amendment]

[Submission date] July 21, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0118

[Correction method] Change

[Correction content]

[0118]

[Table 4]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location G03G 9/08 101 (72) Inventor Masaichiro Katada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation

Claims (10)

[Claims] 1. An image forming method comprising a step of forming a toner layer on a toner carrier facing the electrostatic latent image carrier to develop the electrostatic latent image on the electrostatic latent image carrier. The coating amount per unit area of the toner layer formed on the carrier is: w / ρ = 0.2 to 0.8 w; toner coat weight (cm) ρ per 1 cm ^{2 of} toner carrier surface ρ; toner true density (G / cm ³ ) is satisfied, and the moving speed of the toner carrier surface in the developing area is 1.05 to 3.0 times the moving speed of the electrostatic latent image carrier surface, The toner 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, and the silicone oil-treated silica A and silica B are , The following conditions a) An image forming method characterized in that the average particle diameter of silica is 10 A ≦ B b) The amount of silicone oil treated is 2 A ≦ B c), and the addition amount (weight ratio) to the toner satisfies A ≧ 3 B. 2. The toner is a magnetic toner, the electrostatic latent image carrier and the toner carrier have a certain gap, and development is performed while applying an alternating electric field.
The image forming method described in 1 .. 3. The toner coating amount is w / ρ = 0.3 to
The image forming method according to claim 1, wherein the image forming method is 0.7. 4. The ratio of the moving speed of the surface of the toner carrying member to the moving speed of the surface of the electrostatic latent image carrying member in the developing area is 1.
The image forming method according to claim 1, which is 1 to 2.5 times. 5. The image forming method according to claim 1, wherein the average roughness Ra of the surface of the toner carrier is 1.5 or less. 6. 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 .. 7. The silicone oil-treated silica A has an oil treatment amount of 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. 8. 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 9. The silicone oil treated silica A and B
2. The image forming method according to claim 1, wherein the viscosity of the treated oil is 10 A ≦ B. 10. The atomic ratio of the Si atoms originating from the silicone oil and the Si atoms originating from the base silica (oil Si / silica Si) on the surface of the silicone oil-treated silica B is 1 ≦ oil Si / silica Si ≦ 10. The image forming method according to claim 1, wherein