JPH06250436A - Magnetic developer and image forming method - Google Patents

Abstract

PURPOSE:To obtain a developer with high durability and high reproducibility without splashing by fixing inorg. fine particles to the surface of a magnetic material and satisfying specified conditions so that the developer is not deposited on the developer carrier body. CONSTITUTION:Ths developer is used for an image forming device in which a developer carrier body has <1.0mum JIS center line average roughness (Ra) and the AC voltage applied on the developer carrier body is >=1500V Vpp with >=2100Hz frequency. The absolute difference (Vcont.) between the DC voltage (Vdc) and the charged voltage (Vd) of the latent image carrier body is <=250V. The developer contains at least a binder resin and a magnetic material. Inorg. fine particles by 0.2-5wt.% of the magnetic material is fixed to the surface of the magentic material. The specific surface area (A) [m<2>/g] of the magentic material, the change of specific surface area (B) [m<2>/g] after inorg. fine particles are fixed to the surface of the magentic material, and the added amt. C (wt.%) of inorg. fine particles to the magnetic material are in the relation of 1<=B/A<=0.8 and B<30XC.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic charge developing developer and an image forming method for visualizing an electrostatic charge image in an image forming method such as electrophotography and electrostatic printing.

[0002]

2. Description of the Related Art Conventionally, many electrophotographic methods are known, but generally, a photoconductive substance is used to form an electric latent image on an electrostatic latent image carrier by various means. Then
Then, the latent image is developed with a developer to form a visible image, and if necessary, the developer image is transferred to a transfer material such as paper, and then the developer image is fixed on the transfer material by heat or pressure. To obtain a copy.

In recent years, in addition to conventional copying machines, there have been many printers, facsimile machines, and the like using electrophotographic methods. Particularly in printers and facsimiles, a developing device using a one-component developer is often used because it is necessary to reduce the size of the copying device. An image forming apparatus using a conventional one-component developer has a structure as shown in FIG. 1, for example. In FIG. 1, reference numeral 100 denotes an electrostatic latent image carrier, around which a primary charging roller 117, a developing device 140, a transfer charging device 114, a cleaner 116, a register roller 12 are provided.
4 etc. are provided. Then, the electrostatic latent image carrier 100 is charged by the primary charging roller 117.

The electrostatic latent image carrier 100 is exposed by irradiating the laser beam 123 with the laser beam 123 by the laser generator 121. The electrostatic latent image on the electrostatic latent image carrier 100 is developed with a one-component magnetic developer by the developing device 140 and transferred onto the transfer material by the transfer charging device 114. The transfer material bearing the developer image is conveyed to the fixing device 126 by the conveyor belt 125 or the like and fixed on the transfer material.

As shown in FIG. 2, the developing device 140 is arranged in the vicinity of the electrostatic latent image carrier 100 and is a cylindrical developer carrier 102 (hereinafter referred to as a developer carrier) made of a non-magnetic metal such as aluminum or stainless steel. (Hereinafter referred to as “electrostatic latent image carrier 10”)
The gap between 0 and the developer carrier 102 is about 300 due to a developer carrier / electrostatic latent image carrier gap holding member (not shown).
It is maintained at μm. A magnet roller 104 is concentrically fixed to the developer carrier 102 in the developer carrier.
It is arranged. However, the developer carrying member 102 is rotatable. The magnet roller 104 is provided with a plurality of magnetic poles as shown in the figure. S1 influences development, N1 regulates the amount of developer, S2 influences the taking in / conveying of the developer, and N2 influences the prevention of the blowing of the developer. The elastic blade 103 is provided as a member for controlling the amount of the magnetic developer attached to the developer carrier 102 and conveyed, and the developer conveyed to the developing area by the contact pressure of the elastic blade 103 against the developer carrier 102. The dose is controlled. In the developing area, a developing bias as shown in FIG. 3 is applied between the electrostatic latent image carrier 100 and the developer carrier 102, and the developer on the developer carrier electrostatically corresponds to the electrostatic latent image. It flies on the latent image carrier 100 to form a visible image.

Unlike the two-component method, the one-component developing method does not require carrier particles such as glass beads and iron powder, so that the developing apparatus itself can be made compact and lightweight. Further, since the two-component developing system needs to keep the toner concentration in the carrier constant, a device for detecting the toner concentration and supplying a required amount of toner is required. Therefore, also in this case, the developing device becomes large and heavy. Such a device is not necessary in the one-component developing system, and it is preferable because it can be made small and light.

In the copying machine, there is always a demand for higher speed and stabilization. Especially for medium to high speed machines, the two-component developing method is the mainstream. This is because the stability of the copied image with respect to long-term use at high speed becomes more important than the problem of the size and weight of the developing device in such a large machine. Generally, the two-component developing type toner is colored with carbon black or the like, and the other components are mostly composed of a binder resin.

Therefore, since the toner particles are light and have no force to adhere to the carrier particles other than the electrostatic force, the toner is scattered especially at high-speed development, and the optical lens, the original glass, and the transport section are contaminated by long-term use. May occur, and the stability of the copied image may be impaired. Therefore, a developing method has been put into practical use, in which the developer is made to contain a magnetic material to make the developer heavy and to be attached to the magnetic carrier particles by magnetic force as well as electrostatic force so as to prevent the developer from scattering. As described above, the image forming method using the one-component magnetic developer is becoming more and more important.

In addition, LED and LBP printers have become the mainstream of the market in recent years as the printer apparatus, and the direction of technology has become higher resolution, that is, 400, 600, 800 dpi instead of 240, 300 dpi in the past. There is. Therefore, the developing system is also required to have higher definition. Further, the copiers are also becoming more sophisticated, and as a result, they are moving toward digitalization. In this direction, the method of forming an electrostatic charge image with a laser is the main method, so it is also advancing toward high resolution, and here too, as with printers, high resolution and high definition development methods are required. Japanese Patent Laid-Open No. 1-112253,
JP-A-2-284158 proposes a developer having a small particle size. Further, as the LBP becomes smaller and has higher durability, it is necessary to extend the life of the small-diameter developer carrier / small-diameter electrostatic latent image carrier.

In order to prolong the life of the electrostatic latent image bearing member, it is preferable not only to improve the surface layer of the electrostatic latent image bearing member but also to keep the charging potential low. For this purpose, development is performed with a low potential contrast. I need to do it. Further, particularly in a binary small LBP, it is preferable that the slope (γ) of the potential contrast-density curve (VD curve) is raised from the viewpoint of density stability. In order to achieve low-potential development, thin layer coating of developer by a developer carrier having a low JIS center line average roughness (Ra) / contact blade / upper peripheral speed of developer carrier / high Vpp / high frequency preferable.

However, when the weight average particle diameter of the developer becomes fine particles (generally 9 μm or less), the specific surface area of the developer increases, so that the charged developer and fine powder are subjected to a force such as a mirroring force to cause the developer carrier. It becomes difficult to peel off the developer adhered on the developer carrier by firmly adhering to the upper part and applying the electric field force. These developers give an excessive electric potential to the developer carrying member to adversely affect the development and deteriorate the image quality.

Further, thin coating, using a blade in contact with the developer carrier as the developer layer regulating member, and increasing the peripheral speed of the developer carrier are all in the direction of promoting the above fixation. Some measures are required to achieve high durability. Furthermore, under high Vpp / high frequency development conditions, the collision force and the probability of the developer / developer and the developer / developer carrier also increase, so that more effective measures are required at present. .

Considering the above-mentioned development conditions, it is considered that the dispersed state of the magnetic material is a major factor that causes a problem when a magnetic developer is used. That is, when a large amount of magnetic substance aggregates and the like are present in the developer, causing poor dispersion,
As a result, the amount of magnetic substance existing on the surface of or inside the developer causes a large difference between the developer particles. If this amount is large, the resistance is reduced and sufficient electric charge cannot be obtained, resulting in a decrease in developing power. On the other hand, when the amount is small, charge-up is likely to occur, which causes sticking to the developer carrier. further,
When these non-uniform developer particles are mixed and developed, the fog and scattering on the image increase remarkably and the image quality deteriorates remarkably. is necessary.

[0014]

In view of the above-mentioned problems of the prior art, the object of the present invention is to make the developer substantially adhere to the developer carrier even under the developing conditions for achieving low potential development. To provide a highly durable and highly reproducible developer that does not scatter and an image forming method. To provide a developer and an image forming method capable of obtaining a high-density image without fogging through durability. It is in.

[0015]

[Means and Actions for Solving the Problems] The above object is to achieve a developer carrier having a JIS center line average roughness (Ra) of 1.0 μm.
m or less, Vpp of the alternating voltage applied to the developer carrying member is 1500 V or more, the frequency is 2100 Hz or more, and the difference between the DC voltage (Vdc) and the charging potential (Vd) of the electrostatic latent image carrying member. The developer used in the image forming apparatus having a developing device having an absolute value (Vcont.) Of 250 V or less contains at least a binder resin and a magnetic material,
Inorganic fine particles are fixed on the surface of the magnetic substance in the range of 0.2 wt% to 5 wt% with respect to the amount of the magnetic substance, and the specific surface area (A) [m ² / g] of the magnetic substance and Amount of change in specific surface area (B) [m ² / g] after fixing treatment of fine particles
And an amount (C) [% by weight] of the inorganic fine particles added to the magnetic substance is in the range of the following formulas (1) and (2). I found it.

0.1 ≦ B / A ≦ 0.8 Formula (1) B <30 × C Formula (2) Here, the electrostatic latent image carrier of the present invention and a developer carrier carrying a developer layer. In the developing section, it is preferable that the development is performed with the development gap which is larger than the thickness of the developer layer being held and facing each other. Vd is preferably negatively charged, and its absolute value is preferably 500 V or less (more preferably 200 V or more and 400 V or less). Further, it is preferable that the peripheral velocity of the developer bearing member with respect to the electrostatic latent image bearing member is 105% or more from the viewpoint of maintaining the image density.

In the present invention, it is possible to improve the dispersion of the magnetic substance by adding the inorganic fine particles to the magnetic substance and fixing it on the surface of the magnetic substance by mechanical pressure.

When this treatment is carried out, the addition amount of the inorganic fine particles is in the range of 0.2% by weight to 5% by weight with respect to the amount of the magnetic substance, and the specific surface area (A) [m ² / g of the magnetic substance]. ]
And the amount of change in specific surface area (B) [m ² / g] after immobilizing the inorganic fine particles on the surface of the magnetic substance, and the amount (C) [% by weight] of the inorganic fine particles added to the magnetic substance are as follows: It is necessary to be in the range of Expression (1) and Expression (2).

0.1 ≦ B / A ≦ 0.8 Formula (1) (Preferably 0.3 ≦ B / A ≦ 0.6) B <30 × C Formula (2) (Preferably B <20 × C , And more preferably B <15
C) If the addition amount of the inorganic fine particles is less than 0.2% by weight or the value of the formula (1) is less than 0.1, there is no effect, and if the addition amount exceeds 5% by weight or the formula (1) If the value exceeds 0.8, fogging and fly-off will be worsened, image density will be lowered, and the melt viscosity of the developer will be too high, and the fixability will be deteriorated.

Further, when the B value of the formula (2) is 30 × C or more, it is considered that extremely fine inorganic fine particles are used, or fine crushed substances are generated in the coagulation and crushing step. To be In the former case, the aggregation of the inorganic fine particles is severe and it is difficult to uniformly disperse and fix them on the magnetic body, and it is difficult to obtain a homogeneous magnetic body. In the latter case, a large number of crushed materials are mixed, which causes a decrease in image density, fog, and deterioration in fixing property.

Further, when the inorganic fine particles are attached to the magnetic substance by a mechanical treatment, the addition amount (C) [% by weight] of the inorganic fine particles to the magnetic substance and the specific surface area (D) [m of the inorganic fine particles are used.
² / g] and (B) are preferably in the range of the following formula.

0.4 ≦ B / (0.01 × C × D) ≦ 2.5 Formula (3) (further preferably, within 0.6 to 1.8) The value of Formula (3) is 0. If it is less than 0.4, the strength of the mechanical treatment is weak and the inorganic fine particles are not attached to the surface of the magnetic substance and are released, or the strength of the mechanical treatment is too strong and the inorganic fine particles are buried in the surface of the magnetic substance. The situation is likely to be. When the magnetic material in such a state is used for the toner, it is difficult to obtain the desired performance. Further, when the value of the formula (3) exceeds 2.5, it is considered that the inorganic fine particles or the magnetic substance is crushed by the extreme mechanical pressure and finely pulverized. It will be a factor.

Further, it is possible to create a strong adhered state in which the inorganic fine particles are not released even when friction or pressure is repeatedly applied between the magnetic bodies or between the toner and other members while the toner is used. Is also a feature of the present invention.
The immobilization of the inorganic fine particles on the surface of the magnetic material as referred to in the present invention means such a strong adhered state. The strength of such an adhered state is, for example, that the treated magnetic substance is dispersed in a dispersion medium such as water, ultrasonic cleaning is performed to promote the release of the inorganic fine particles on the surface, and the amount of change of the inorganic fine particles by fluorescent X-rays or the like It can also be confirmed by measuring. If 95% or more of the inorganic fine particles are detected as compared with those before washing, it is considered that they are not released at all in consideration of measurement error and the like.

Further, the above-described effect of using the magnetic developer according to the present invention is an image forming apparatus comprising a combination with a developer carrier having a radius of curvature of 20 mm or less and / or an electrostatic latent image carrier having a radius of curvature of 50 mm or less. It is particularly well used when used for. This is because if the diameter is small, the number of rotations in the same number of prints (copies) increases and the adverse effect is greater.

Further, good results were obtained when the weight average particle diameter of the developer according to the present invention was 4 to 10 μm, particularly 4.5 to 9 μm. If the weight average particle diameter is less than 4 μm, the developer is significantly adhered to the development carrier, which causes a problem in image quality. If it exceeds 10 μm, the dot latent image or fine line of 100 μm or less is not sufficiently reproduced.

The surface roughness of the developer carrying member used in the present invention is 1.0 μm in terms of JIS center line average roughness (Ra).
The following is preferable.

When Ra exceeds 1.0 μm, the developer coating layer on the developer carrying member becomes thick and uniform charging is hindered, so that fogging is likely to occur on the image.

The surface of the developer carrying member is preferably a metal or metal oxide surface which has not been roughened by blasting or the like, or one whose surface is coated with a resin layer containing conductive fine particles. A particularly preferred range is Ra of 0.4 μm or less on the surface of metal or metal oxide which is not roughened by blasting, and R of the surface coated with a resin layer containing conductive fine particles.
a is 0.2 to 1.0 μm. As the conductive fine particles contained in the resin layer to be coated, carbon black, graphite, conductive metal oxides such as conductive zinc oxide and metal complex oxides are preferably used alone or in combination of two or more. Further, as the resin in which the conductive fine particles are dispersed, a phenol resin, an epoxy resin, a polyamide resin, a polyester resin, a polycarbonate resin,
Known resins such as polyolefin resins, silicone resins, fluorine resins, styrene resins, and acrylic resins are used. A thermosetting or photocurable resin is particularly preferable.

In the developer of the present invention, the member for regulating the developer on the developer carrying member is regulated by the elastic member which is in contact with the developer carrying member via the developer. Is particularly preferable from the viewpoint of uniformly charging the toner.

Vp of the alternating voltage applied to the developer carrying member
p is 1500 V or more, and preferably 1800 V or more when the waveform is a sine wave or a waveform close to a sine wave.

If Vpp of the present invention is less than 1500 V or the peripheral speed of the developer carrying member is less than 105%, the image density is insufficient. The frequency of the applied alternating voltage is preferably 2100 Hz or more and 6000 Hz or less.

The specific surface area of the magnetic material of the present invention (after the adhesion of the inorganic fine particles) was determined by the BET method using a specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics) by nitrogen adsorption. Further, the specific surface area (A) of the magnetic substance before the adhesion of the inorganic fine particles was calculated by the following formula. Further, the amount of change (B) in the specific surface area due to the adhesion treatment of the inorganic fine particles was obtained from these differences.

A = 6 / (ρ × d ₁ ) × E A: Specific surface area (g /
m ² ) ρ: Density of magnetic material (= 5.2) d ₁ : Number average particle diameter (μm) of magnetic material after inorganic fine particle adhesion treatment (photograph of magnetic material by TEM, The length was measured and determined.) Here, the coefficient E uses the following numerical value depending on the value of the sphericity ψ of the magnetic material.

When ψ ≧ 0.8 1.35 When ψ <0.8 1.70 The sphericity in the present invention is calculated by the following equation.

[0035]

[Equation 1] For the sphericity ψ, 100 magnetic particles are arbitrarily selected from the TEM photograph, the maximum length and the minimum length are measured, and then the calculated values are averaged.

On the other hand, as the binder resin of the developer according to the present invention, homopolymers of styrene such as polystyrene and polyvinyltoluene and their substitution products; styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene. −
Vinyl naphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer Polymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate 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 Styrenic copolymers such as polymers; Methyl methacrylate, polybutyl methacrylate, polyvinyl acetate, and the like vinyl resins may be used alone or in combination.

Further, polyester resin may be used as the binder resin. The monomer used in that case is
As alcohol, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol,
1,4-butanediol, neopentyl glycol,
Diols such as 1,4-butenediol, 1,4-bis (hydroxymethyl) cyclohexane, and etherified bisphenols such as bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropyleneated bisphenol A , And other dihydric alcohols, and examples of the carboxylic acid include maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid,
Examples thereof include divalent organic acids such as adipic acid, sebacic acid, malonic acid, anhydrides of these acids, and dimers of lower alkyl esters and lileic acid.

Further, as a polyhydric alcohol having a valence of 3 or more, for example, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,2. 4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane,
1,3,5-trihydroxymethylbenzene and the like can be mentioned. In addition, examples of trivalent or higher polyvalent carboxylic acids include 1,2,4-benzenetricarboxylic acid, 1,2,5-
Benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,
4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2
-Methylene carboxy propane, tetra (methylene carboxyl) methane, 1,2,7,8-octane tetracarboxylic acid, empor trimer acid, and their acid anhydrides.

As magnetic materials to be combined with the inorganic fine particles of the present invention, iron such as ferrite and magnetite,
A metal made of a ferromagnetic element such as cobalt or nickel, or an alloy or compound containing the same, or an alloy which does not contain an element having a strong magnetic property but exhibits ferromagnetism by an appropriate heat treatment, such as manganese- Examples include alloys of the type called Heusler alloys containing manganese and copper, such as copper-aluminum or manganese-copper-tin, or chromium dioxide. Further, the shape of the magnetic body is not particularly limited, and a magnetic body having any shape such as a sphere, an octahedron or a hexahedron can be used. The content ratio of the fine powder of these magnetic materials is 100
The amount can be 30 to 150 parts by weight, preferably 40 to 120 parts by weight. The magnetic fine particles can also be used as a black or brown pigment.

The inorganic fine particles added to the magnetic material in the present invention include, for example, silica fine powder, titania fine powder, alumina fine powder, zirconium oxide fine powder, magnesium oxide fine powder, zinc oxide fine powder, cerium oxide fine powder and the like. Inorganic oxide, boron nitride fine powder, aluminum nitride fine powder, carbon nitride fine powder, and other nitrides, but are not necessarily limited thereto.

These inorganic fine particles may be surface-treated within a range that does not affect the characteristics of the present invention. Various oils and various coupling agents can be used as the surface treatment agent.

Examples of the oil treatment include treatment with dimethyl silicone oil, methylhydrogen silicone oil, alkyl modified silicone oil, α-methylstyrene modified silicone oil, chlorophenyl silicone oil, fluorine modified silicone oil and the like. Further, as the coupling agent treatment, for example, dimethyldichlorosilane, trimethylchlorosilane, allyldimethylchlorosilane, hexamethyldisilazane, allylphenyldichlorosilane, benzyldimethylchlorosilane, vinyltrimethoxysilane, γ-methacryloxypropyltrisilane. Treatment with methoxysilane, vinyltriacetoxysilane, divinylchlorosilane, dimethylvinylchlorosilane and the like can be mentioned.

The surface treatment method is not particularly limited, and a known method can be used. For example, as a method for oil treatment, inorganic fine particles and oil may be directly mixed using a mixer such as a Henschel mixer, or a method of spraying oil on the inorganic fine particles may be used. Alternatively, it may be produced by removing the solvent after forming a varnish and mixing it with the inorganic fine particles.

Similarly, as a method for treating the coupling agent, for example, dry treatment in which the vaporized silane coupling agent is reacted with inorganic fine particles formed into a cloud by stirring or the like, or silane cup in which the inorganic fine particles are dispersed in a solvent The treatment can be carried out by a generally known method such as a wet method in which a ring agent is subjected to a drop reaction.

The degree of hydrophobicity is often used as a method of indicating the degree of treatment when such surface treatment is carried out. The degree of hydrophobicity of the inorganic fine particles in the present invention is measured by the following method. . Surface treated inorganic fine particles 0.2g
Is added to 50 ml of water in an Erlenmeyer flask with a volume of 250 ml. Methanol is titrated from the burette until the total amount of inorganic particulates is wet. At this time, the solution in the flask is stirred with a magnetic stirrer. The end point is observed by the fine silica powder suspended in the solution, and the degree of hydrophobization is expressed as the percentage of methanol in the mixture of methanol and water when the end point is reached.

The method of fixing the inorganic fine particles on the surface of the magnetic material of the present invention by mechanical treatment is not particularly limited as long as the physical properties described in the claims are satisfied. That is, methods such as a ball mill, a roll mill, a batch kneader, a Nauta mixer, and a mix muller are used.

In the toner of the present invention, in addition to the above-mentioned binder resin component, the following compounds are contained in a ratio smaller than the content of the binder resin component within a range not adversely affecting the effect of the present invention. Good.

For example, silicone resin, polyurethane,
Polyamide, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin such as low molecular weight polyethylene or low molecular weight polypropylene, aromatic petroleum resin,
Examples include chlorinated paraffin and paraffin wax.

A colorant may be added to the toner according to the present invention, and generally known dyes and pigments can be used.

As the charge control agent contained in the toner according to the present invention, a conventionally known charge control agent is selected. Specific examples of the positive charge control agent generally include nigrosine and 2 carbon atoms.
Azine dyes containing 16 to 16 alkyl groups (Japanese Examined Patent Publication No.
1627), basic dyes (for example, CI Bas
ic Yellow 2 (C.I. 41000), C.I.
I. Basic Yellow 3, C.I. I. Basi
c Red 1 (C.I. 45160), C.I. I. Ba
sic Red 9 (C.I. 42500), C.I. I.
Basic Violet 1 (CI.4253
5), C.I. I. Basic Violet 3 (C.
I. 42555), C.I. I. Basic Violet
10 (C.I. 45170), C.I. I. Basic
Violet 14 (C.I. 42510), C.I. I. B
asic Blue 1 (C.I. 42025), C.I.
I. Basic Blue 3 (C.I. 5100
5), C.I. I. Basic Blue 5 (C.I.4
2140), C.I. I. Basic Blue 7 (C.
I. 42595), C.I. I. Basic Blue 9
(C.I. 52015), C.I. I. Basic Blu
e 24 (C.I. 52030), C.I. I. Basic
Blue 25 (C.I. 52025), C.I. I. B
asic Blue 26 (C.I. 44025),
C. I. Basic Green 1 (C.I. 420
40), C.I. I. Basic Green 4 (C.
I. 42000), etc., and lake pigments of these basic dyes (as a laking agent, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, ferrocyanide, etc.) , C.I. I. Sovent Blac
k 3 (C.I. 26150), Hansa Yellow G
(C.I. 11680), C.I. I. Mordant
Black11, C.I. I. Pigment Black
1 etc. are mentioned.

Or, for example, a quaternary ammonium salt such as benzolmethyl-hexadecyl ammonium chloride or decyl-trimethyl ammonium chloride or a vinyl resin containing an amino group, a polyamide resin such as a condensation polymer containing an amino group, etc. may be mentioned. Preferred are nigrosine, quaternary ammonium salts, triphenylmethane-based nitrogen-containing compounds, polyamides, and the like.

Further, specific examples of the negative charge control agent include the monoazo compounds described in JP-B Nos. 41-20153, 42-27596, 44-6397 and 45-26478. Metal complexes of dyes, and further nitramic acid and salts thereof described in JP-A-50-133338 or C.I. I. Dyes and pigments such as 14645, JP-B-55-42752, JP-B-5
No. 8-41508, Japanese Patent Publication No. 58-7384,
Zn, Al, and C of salicylic acid, naphthoic acid, and dicarboxylic acid described in JP-B-59-7385.
Examples thereof include metal complexes of o, Cr and Fe, sulfonated copper phthalocyanine pigments, nitro groups, halogen-introduced styrene oligomers and chlorinated paraffins. Particularly, from the viewpoint of dispersibility, metal complex salts of monoazo dyes, metal complexes of salicylic acid, alkylsalicylic acid, naphthoic acid, and dicarboxylic acid are preferable. The amount of these charge control agents added keeps good triboelectric chargeability as described above, while minimizing the adverse effects such as a reduction in developing power and a reduction in environmental stability due to contamination of the developing sleeve surface by the charge control agents. To 100 parts by weight of resin, 0.1
Amounts of up to 3 parts by weight are preferred.

An ethylene olefin polymer may be used as a fixing aid in the toner of the present invention together with a binder resin.

The ethylene-based olefin homopolymer or ethylene-based olefin copolymer used herein includes polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer. There are coalesced products, ionomers having a polyethylene skeleton, and the like, and the above copolymer preferably contains 50 mol% or more (more preferably 60 mol% or more) of an olefin monomer.

Further, in the developer of the present invention, colloidal silica or other fine powder of metal oxide may be externally mixed in order to improve fluidity and adjust charging property.

[0056]

EXAMPLES The basic structure and features of the present invention have been described above. The method of the present invention will be specifically described below with reference to production examples and examples. However, the embodiments of the present invention are not limited to these. The number of parts in the examples is parts by weight.

(Magnetic Material Production Example 1) BET Specific Surface Area 6.5
m ² / g commercially available spherical magnetite (φ = 0.93, 1
0.8 wt% of silica fine powder having a BET specific surface area of 350 m ² / g was mixed with δ _s = 65.6 emu / g in K Oerstedd by a mix muller and fixed on the surface of magnetite to produce magnetic substance No1. Table 1 shows the physical properties and the like of the obtained magnetic material No1.

30 g of the magnetic material No1 was placed in an Erlenmeyer flask, 200 cc of water was added and well stirred, and then ultrasonic cleaning was performed for 3 minutes, and the cleaning liquid was discarded while using a magnet to prevent the magnetic material No1 from flowing out. After that, 200 cc of water was added again and the mixture was well stirred, and the cleaning liquid was discarded in the same manner as the previous time.
After repeating this again, the magnetic substance No1 was dried and the amount of silica on the surface was quantified by fluorescent X-ray measurement. As a result, 95% or more of silica was detected as compared with that before washing, and it was confirmed that silica was fixed on the magnetite surface.

(Magnetic Material Production Example 2) BET Specific Surface Area 150
A magnetic substance No. 2 was produced in the same manner as in the magnetic substance production example 1 except that 2.0% by weight of m ² / g silica fine powder was added and the mixing conditions were slightly weakened. Obtained magnetic material No2
Table 1 shows the physical properties and the like. Magnetic material No. 2 was used as the magnetic material manufacturing example 1.
As a result of washing in the same manner as above and quantifying silica, 95% or more of silica before washing was detected, and it was confirmed that the silica was fixed on the surface of magnetite.

(Magnetic Material Production Example 3) 2.5% by weight of silica fine powder having a surface-treated hydrophobicity of 68% and a BET specific surface area of 110 m ² / g was added, except that the mixing conditions were slightly weakened. Magnetic material No. 3 was produced in the same manner as in Magnetic Material Production Example 1. Table 1 shows the physical properties and the like of the obtained magnetic material No3.
The magnetic substance No. 3 was washed with methanol in the same manner as in the magnetic substance production example 1 and the amount of silica was quantified. As a result, 95% or more of the silica before washing was detected, and the silica was fixed on the magnetite surface. It was confirmed.

(Magnetic Material Production Example 4) BET Specific Surface Area 120
Magnetic Material Production Example 1 except that 2.0% by weight of m ² / g of alumina fine powder was added and a ball mill was used as a mixing device.
Magnetic material No. 4 was produced in the same manner as in. Table 1 shows the physical properties and the like of the obtained magnetic material No. 4.

The magnetic substance No. 4 was washed in the same manner as in the magnetic substance production example 1 to quantify the amount of alumina.
% Or more of alumina was detected, and it was confirmed that alumina was fixed on the surface of magnetite.

(Comparative Magnetic Material Production Example 1) Commercially available spherical magnetite having a BET specific surface area of 6.5 m ² / g (δ _s at 1K Oersted = 65.6 emu / g) used in Magnetic Material Production Example 1 (φ = 0.93) was used as the comparative magnetic material No1. Table 1 shows the physical properties of the comparative magnetic body No. 1.

Comparative Magnetic Material Production Example 2 Comparative magnetic material No. 2 was produced in the same manner as in Magnetic Material Production Example 1 except that the amount of fine silica powder added was 3.0% by weight. Table 1 shows the physical properties and the like of the obtained comparative magnetic body No2.

[0065]

[Table 1]

(Developer Production Example 1) Styrene-n-butyl acrylate copolymer 100 parts (Copolymerization weight ratio 8: 2 Mw = 260,000) Magnetic material No1 100 parts Negative charge control agent (monoazo dye-based iron complex) 0.8 parts Ethylene-propylene copolymer (Mw = 6000) 3 parts The above mixture was melt-kneaded with a twin-screw extruder heated to 140 ° C., the kneaded product was cooled, and then coarsely crushed with a hammer mill to obtain a coarse mixture. The pulverized product was finely pulverized by a jet mill, and the finely pulverized product was classified by wind force to obtain a weight average particle diameter (D4) of 7.0μ.
m negatively chargeable magnetic developer was obtained. A mixture obtained by adding 1.0 part of hydrophobic silica fine powder (hexamethyldisilazane treated BET value 200 m ^{2 /} g) to 100 parts of this developer was mixed with a Henschel mixer to obtain a developer (1).

(Developer Production Example 2) A developer (2) was produced in the same manner as in Developer Production Example 1 except that the magnetic material No. 2 was used.

(Developer Production Example 3) A developer (3) was produced in the same manner as in Developer Production Example 1 except that the magnetic material No. 3 was used.

(Developer Production Example 4) A developer (4) was produced in the same manner as in Developer Production Example 1 except that the magnetic material No. 4 was used.

(Comparative Developer Production Example 1) Comparative developer (1) was produced in the same manner as in Developer Production Example 1 except that Comparative Magnetic Material No. 1 was used.

Comparative Developer Production Example 2 Comparative developer (2) was produced in the same manner as in Developer Production Example 1 except that Comparative Magnetic Material No. 2 was used.

Example 1 The image forming apparatus shown in FIGS. 1 and 2 was used. However, as the electrostatic latent image carrier, an OPC electrostatic latent image carrier having a diameter of 30 mm was used, and the dark portion potential Vd = −400.
V and bright part potential VL = -30V. The gap between the electrostatic latent image bearing member and the developer bearing member is 350 μm, the developer bearing member is a resin layer having a layer thickness of about 7 μm and Ra of 0.8 μm, and the surface is a mirror surface with a diameter of 16 mm. Using a developer carrier formed on an aluminum cylinder,
50 gauss, 15 mm / cm urethane blade with a thickness of 1.0 mm and a free length of 10 mm as a developer regulating member
It was made to contact by the linear pressure.

Phenol resin 100 parts Graphite (particle size: about 7 μm) 90 parts Carbon black 10 parts Next, as the developing bias shown in FIG. 3, a DC bias component Vdc = −230V and an AC bias component Vpp = −2.
A sine wave of 100 V and a frequency of 2400 Hz was used, and the developer (1) of Production Example 1 was used as the developer at a peripheral velocity of the developer carrier of 110% with respect to the electrostatic latent image carrier at 23 ° C. 65.
Images were printed on 10000 sheets in an environment of% RH.

As a result, a good image without scattering was obtained even after continuous printing of 10,000 sheets. Also,
After removing the developer on the sleeve with air, visual observation was conducted, but no developer adhered on the sleeve. The amount of fog at this time was measured using a reflection densitometer (reflectometer TC-6DS manufactured by Tokyo Denshoku Co., Ltd.) (the worst value of the reflection density of the white background after printing was Ds, and the average reflection density of the paper before printing was Dr. (Ds-Dr is the fogging amount)
As a result, it was good at 1.4% (a fog amount of 2% or less is a good image having substantially no fog, and a fog amount of more than 5% is an unclear image with remarkable fog). Also,
The resolution of a 1-dot latent image of 80 μm was also sufficient.

Example 2 In Example 1, Ra was 0.1 μm as a developer carrying member.
A fogging amount of 1.5 was obtained when the same procedure as in Example 1 was carried out except that an aluminum mirror-finished cylindrical sleeve of m was used.
%, A good image without scattering was obtained. Further, after the developer on the sleeve was removed by air, visual observation was carried out, but no developer adhered to the sleeve at all.

Example 3 Example 1 was repeated except that the developer (2) was used in Example 1.
When carried out in the same manner as above, the fog amount was 1.6%, a good image without scattering was obtained, and the developer was not fixed to the sleeve at all.

Example 4 Example 1 except that the developer (3) is used in Example 1.
When carried out in the same manner as above, the fogging amount was 1.5%, a good image without scattering was obtained, and the developer was not fixed to the sleeve at all.

Example 5 Example 1 except that the developer (4) is used in Example 1.
When carried out in the same manner as above, the fog amount was 2.2%, a good image without scattering was obtained, and the developer did not stick to the sleeve at all.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the comparative developer (1) was used, but the fog amount was deteriorated to 5.1%, and the image was conspicuous. . Further, the developer was fixed on the sleeve surface.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the comparative developer (2) was used, and the fog amount was deteriorated to 5.5%, and the image was remarkably scattered.

[0081]

According to the present invention, in the image forming apparatus having the above-mentioned developing step, by using the developer in which the inorganic fine particles are fixed on the surface of the magnetic material, the developer is carried on the developer carrier. It is possible to obtain a high-quality image without fogging or scattering and good durability.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an example of an image forming apparatus using a one-component developer.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is an explanatory diagram of a developing bias.

[Explanation of symbols]

 100 Electrostatic latent image carrier 102 Developer carrier 103 Elastic blade 104 Magnet roller 114 Transfer charger 117 Primary charging roller 121 Laser generator 123 Laser light 125 Conveyor belt 126 Fixer 140 Developer Vdc DC power supply voltage Vd Electrostatic latent Dark part potential on the image carrier VL Bright part potential on the electrostatic latent image carrier f Frequency of alternating voltage Vpp Voltage between peaks of alternating voltage

(72) Inventor Manabu Ono 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masayoshi Kato 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (2)

[Claims] 1. The JIS centerline average roughness (Ra) of the developer carrying member is 1.0 μm or less, the alternating voltage Vpp applied to the developer carrying member is 1500 V or more, and the frequency is 2100 Hz or more. , The absolute value (Vcon) of the difference between the DC voltage (Vdc) and the charging potential (Vd) of the electrostatic latent image carrier.
t. Is 250 V or less, and a developer used in an image forming method having a developing step of developing with a developer, which contains at least a binder resin and a magnetic substance, and is 0.2 with respect to the amount of the magnetic substance. In the range of 5% by weight to 5% by weight, the inorganic fine particles are fixed on the surface of the magnetic substance, and the specific surface area (A) [m ² / g] of the magnetic substance and the inorganic fine particles on the surface of the magnetic substance are fixed. The change amount (B) [m ² / g] of the specific surface area and the addition amount (C) [% by weight] of the inorganic fine particles to the magnetic substance are expressed by the following formulas (1) and (2) 0.1 ≦ B / A ≦ 0.8 Formula (1) B <30 × C The formula (2) is satisfied. 2. The JIS center line average roughness (Ra) of the developer carrying member is 1.0 μm or less, the alternating voltage Vpp applied to the developer carrying member is 1500 V or more, and the frequency is 2100 Hz or more. , The absolute value (Vcon) of the difference between the DC voltage (Vdc) and the charging potential (Vd) of the electrostatic latent image carrier.
t. ) Is 250 V or less, and an image forming method having a developing step of developing with a developer, the developer contains at least a binder resin and a magnetic substance, and 0.2 wt% to 5 wt% relative to the amount of the magnetic substance. Inorganic fine particles are fixed on the surface of the magnetic substance in the range of wt%, and the specific surface area (A) [m ² / g] of the magnetic substance and the change of the specific surface area after the fixing treatment of the inorganic fine particles on the surface of the magnetic substance are performed. The amount (B) [m ² / g] and the addition amount (C) [% by weight] of the inorganic fine particles to the magnetic substance are expressed by the following formulas (1) and (2): 0.1 ≦ B / A ≦ 0.8 Formula (1) B <30 × C An image forming method characterized by using a magnetic developer in the range of Formula (2).