JPH01253780A - Image forming method - Google Patents

Abstract

PURPOSE:To electrostatically transfer a toner image on an electrostatic image holding body onto transfer material under the negative ratio of a primary electrified field to a transfer electrified field by employing negatively electrified toner and one-component developer which includes resin particles possessing a prescribed particles diameter and triboelectrification characteristic. CONSTITUTION:A primary charger 2 negatively charges the surface of a photosensitive drum 1, and a latent image is formed with light from a light source or laser beam by exposure 5 and reversely developed with the negatively electrified toner and the one-component magnetic developer 13 including the resin particles possessing a mean particle diameter of 0.1-1.0mum and a triboelectrification characteristic of +50-+60muc/g by means of a developing device 9. When in this developing part, a bias is impressed between the drum 1 and a sleeve 4 to carry a transfer paper P to a transfer charger 3, it positively electrifies the back of the transfer paper P (opposite to the drum 1) to electrostatically transfer the negatively charged toner on the drum 1 onto the transfer paper P. After the charger 3 passes by, a destaticizing brush 10 destaticizes charges on the surface to separate the transfer paper P.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to an image forming method using a one-component developer containing a negatively chargeable toner and positively chargeable resin particles. The present invention relates to an image forming method including a step of successfully transferring a toner image to a transfer material.

[Background technology]

2. Description of the Related Art Conventionally, in electrophotographic apparatuses, a normal development method in which a non-exposed area is developed is generally used. This is because the reflected light from the original is optically processed and then projected onto the photoreceptor.
Development is performed on non-exposed areas (character areas of the original) where there is no reflected light.

Recently, electrophotographic systems have been used not only for copying images but also for printers used for computer output. For printer applications, the light emitter (
semiconductor laser, etc.) is turned on and off (such as a semiconductor laser) according to the image signal.
ON-OFF), and the light is projected onto the photoreceptor.

At this time, the printing rate (ratio of printing area per page) is usually less than 30%, and the method of exposing the character part (
Reversal development) is advantageous in terms of luminescent life.

In addition, reversal development is used in devices that output positive and negative images from the same original (for example, microfilm output devices), and in the same summer, it is used to develop two or more colors within the device. Official! It has come to be used in devices that combine reversal development and reversal development.

However, reversal development has the following problems. The transfer electric field in normal development (hereinafter referred to as "positive development") has the same polarity as the primary charging, and even if the transfer electric field is applied onto the photoreceptor after passing through the image carrier (hereinafter referred to as paper, etc.), its effect is It is erased at (as shown in Figure 1).

On the other hand, the transfer electric field in reversal development has a polarity opposite to that of the primary charge, and when the transfer electric field is applied even after passing through the paper, a charge of the opposite polarity occurs on the photoreceptor, which cannot be erased by erase exposure, and the image becomes dark and dark. Hail. This is a "paper trail"
This is a phenomenon called.

As a countermeasure against paper traces, there are measures such as lowering the transfer current after the paper has passed, as shown in Japanese Patent Application Laid-Open No. 60-256173. This increases the complexity of the apparatus and increases the cost of the apparatus.Also, it is possible to consider means to lower the transfer electric field to a range in which charging of opposite polarity does not occur on the photoreceptor.

However, this method lowers the transfer efficiency, resulting in a reduction in image quality due to poor transfer. Another example of juxtaposition in the reversal development method is that the photoconductor and paper, etc. are charged with opposite polarities, so when charged with a strong electric field, the photoconductor and paper, etc. electrostatically attract each other, causing transfer. Even after the process is completed, the paper does not separate, and paper etc. enters the next process (cleaning process, etc.), causing paper jams. This is a phenomenon called "wrapping". As a countermeasure against wrapping, there is a means to prevent the photoreceptor from coming into close contact with paper, etc., as seen in Japanese Patent Laid-Open No. 56-60470. However, this method is not necessarily effective in reversal development. That is, this is considered to be because the close contact during separation in the transfer process of reversal development is stronger than that of normal development. Another method is U.S. Patent 3,357,400.
As seen in the specifications, there are devices equipped with separation charging or belt separation as auxiliary means for separation. This is because this charging is smaller than transfer charging and does not affect the potential on the photoreceptor.

Another method is to reduce the electrostatic adsorption force by lowering the transfer electric field, but this method is likely to cause image quality deterioration due to poor transfer as described above. In addition, lowering the transfer electric field results in a decrease in transfer efficiency, which is disadvantageous for postcards and OH
Unable to meet diverse needs such as P film. Also, when the transfer electric field is lowered, images such as outlines and line drawings, etc.
In areas where developer tends to concentrate (etch development areas), ``transfer voids'', which are part of transfer defects, occur. This is thought to be because the etch development area contains more developer than the normal area (glue, developer aggregation is more likely to occur), and the response to the transfer electric field decreases.As a result, high-quality images that are faithful to the latent image can be obtained. The problem is that it becomes difficult to

[Purpose of the invention]

An object of the present invention is to provide an image forming method that solves the above-mentioned problems.

An object of the present invention is to provide a transfer process that allows a high-quality image that is faithful to the latent image to be obtained regardless of the conditions of the transfer carrier in an image forming method that requires transfer using a low transfer electric field, such as a reversal development method. Image forming method: Provides an image forming method that uses a developer that produces images without or with suppressed phenomena such as "paper marks,""wrapping," and "transfer missing."It's about doing.

Furthermore, the object of the present invention is to develop an image using a negatively charged magnetic component developer that is stable against environmental changes such as high temperature and high humidity, temperature and low humidity, and can always exhibit good characteristics. The object of the present invention is to provide a forming method.

A further object of the present invention is to provide an image forming method using a negatively charged magnetic-component developer suitable for developing digital latent images used in digital copiers, laser beam printers, and the like.

An object of the present invention is to provide an image forming method that does not cause hollowing even under a low transfer electric field as in a reversal developing device and has good durability.

[Summary of the invention]

The present invention relates to an image forming method in which an electrostatic charge image on an electrostatic image carrier is developed with a one-component developer, and a toner image formed on the electrostatic image carrier is electrostatically transferred to a transfer material. A chargeable toner and an average particle size of 0.1 to 1.0 μm and +
A one-component developer containing at least resin particles having tribocharging characteristics of 50 to +600 tt e/g is used, and the ratio #(vtr/■, r) of the primary charging electric field to the transfer charging electric field Vtr is negative. The present invention relates to an image forming method characterized by electrostatically transferring a toner image on an electrostatic image carrier to a transfer material under the following conditions.

[Detailed description of the invention]

The present inventors have discovered that by adding positively chargeable resin particles to a one-component developer, satisfactory results can be obtained in the transfer process in reversal development.

The positively chargeable resin fine particles added to the developer used in the image forming method of the present invention have an average particle size of 0.1 to 1 μm, and a tribocharge amount of +50 μc/g to +600 uc/
gs preferably +100 μc/g to +600 μc7
g is used. These resin particles are fixed to the surface of the toner particles in the developer by electrostatic force, forming voids between the toner particles and between the toner particles and the surface of the photoreceptor, reducing adhesion and improving electrostatic transfer. It is thought that it can be done.

If the average particle size is smaller than 0.1 μm, no improvement in transfer efficiency will be observed, while if it is larger than 1 μm, it will not be stably fixed on the surface of the toner particles, so it will be released and cause a decrease in density, black spots, fog, etc. Problems occur during development. Furthermore, if the charge amount is lower than +50μc/g, the toner particles will not be stably fixed on the surface of the toner particles, resulting in the above-mentioned development problem.On the other hand, if the charge amount is higher than +600μc/g, the toner particles will not be stably fixed on the surface. However, due to the high chargeability, problems in development such as narrowing of lines occur.

When the amount of positively charged resin particles added was 100 parts by weight of toner, no improvement in transfer efficiency was observed, and when the axis β was 3.0 parts by weight, excess resin particles were present in the developer, causing problems in development. It happens. The amount of charge on the resin particles is measured as follows. 0.2 g of fine resin particles left overnight in an environment of 25°C and 950 to 60% RH and carrier iron powder (not coated with resin) with a main particle size of 200 to 300 mesh.
For example, EFV200/300 manufactured by Nippon Iron Powder Co., Ltd.) 99.8
g in the above environment in an aluminum pot with a volume of approximately 200 c, c, and mixed for 60 minutes,
Using an aluminum cell with a 400 mesh screen, the charge amount of the resin particles is measured by the blow-off method at a blow pressure of 0.5 kg/crd. The average particle diameter of the resin particles is measured using a Coulter Counter N4 (manufactured by Nikkaki Corporation) in a state in which they are dispersed in a solvent using ultrasonic waves.

In addition, substantially monodispersed particles obtained by polymerization or the like may be measured by scanning electron micrographs (S, E, M, images).

The resin particles used in the present invention are characterized in that they behave together with the developer, and by acting together they adjust the adsorption force between the developer and the photoreceptor. This is completely different from the method disclosed in Japanese Patent Application Laid-Open No. 56-60470, in which particles are actively placed on non-images to reduce the adsorption force between the transfer material and the photoreceptor.

According to the method disclosed in JP-A-56-60470, it is possible to improve wrapping development without lowering the transfer electric field, but it is not effective against paper trace development (and it is not effective to reduce the transfer rate under a low transfer electric field. It has no effect on improving it.

The transfer process used in the present invention includes an electrostatic transfer method using an electric field generated by a corona discharge charger, a contact roller charger, or the like. Transfer conditions are measured as follows. Referring to FIG. 1 of the accompanying drawings, the cleaning device 8. Developing device9. The transfer charger 3 and the like are removed, and the photoreceptor (photosensitive drum) 1, which is an electrostatic image holder, is charged with the negative charger 2. After substantially completely shielding leaked light and charging one revolution of the photoreceptor I, the surface potential of the photoreceptor is measured with a surface electrometer.

Let the value of the surface potential at this time be V, , (V). Next, after wiping the surface of the photoconductor with a cloth impregnated with alcohol to remove static electricity from the surface of the photoconductor, the negative charger 2 is removed, and the transfer charger 3 is attached to charge one revolution of the photoconductor L. After that, the surface potential of the photoreceptor is measured.

Let the value of the surface potential at this time be vke [v]. In the present invention, the value of VIr/Vp- is preferably negative. If the absolute value is less than 0.5, the transfer electric field is too low and image deterioration is likely to occur during transfer.
On the other hand, if the absolute value exceeds 1.6, the transfer electric field is too strong and the photoreceptor is likely to be positively charged (paper trail phenomenon and wrapping phenomenon are likely to occur). It is.

The present invention is effective for an image forming method (apparatus) using an organic photoreceptor (hereinafter referred to as an OPC photoreceptor), and the OPC photoreceptor is a laminated layer composed of multiple layers having a small number (of both a charge generation layer and a charge transport layer). The present invention is particularly effective in contrast to a reversal development type image forming method using type OPC, since this tendency is more pronounced in OPC and paper marks are more likely to occur.

The values of Vpr used in the present invention include -300 to -t,
ooo (v) is preferred, especially 1: m -500 to -9
00 (V) is preferred. If it is less than -300 (V), it is difficult to secure a potential difference during development, and the image tends to become unclear (on the other hand, if it exceeds -1,000 (V),
Dielectric breakdown of the photosensitive layer occurs due to the electric field, and image quality deterioration such as black spots is likely to occur. -500 to -900 (from durability etc.)
V) is particularly preferred.

The image forming method of the present invention is an image forming method in which a transfer material is separated from a photoreceptor using the elastic force of the transfer material (paper, etc.), the curvature of the photoreceptor, a static eliminating brush, etc., without using mechanical separation means. It is particularly effective against (devices). The separation state in devices that do not have a mechanical separation mechanism depends on the transfer conditions.
The present invention is particularly effective because the windings are prone to cracking.

The present invention is based on the diameter of the photoreceptor 1 ("φ" in FIG. 1 is 50 mm).
It is particularly effective for image forming methods (apparatus) using the following photoreceptors. Devices that use photosensitive drums with a diameter of 50 mm or less are intended to be miniaturized, and the number of parts must be reduced. Usually, the separation process consists of separation using only the elastic force of paper and a static elimination brush 7, etc. has been done (
(See Figure 2).

At this time, the static electricity removal process only removes static electricity from paper, etc.
Usually, it does not affect the surface potential of the photoreceptor.

The image forming process will be explained with reference to FIG.

- A developing device comprising a magnetic blade 11 and a developing sleeve 4 containing a magnet; In a container 9, the latent image is reversely developed using a one-component magnetic developer 13. In the developing section, a bias is applied between the photosensitive drum 1 and the developing sleeve 4 by a bias applying means. The transfer paper P is conveyed to the transfer section (then the transfer charger 3 charges the transfer paper P
The negatively charged toner image on the surface of the photosensitive drum is positively charged from the back side (the side opposite to the photosensitive drum side) of the spring transfer paper P.
electrostatically transferred onto the top. Immediately after passing through the transfer charger 3, the transfer paper P is separated from the photosensitive drum 1 by curvature separation while the charges on the back surface of the transfer paper are eliminated by the charge removal brush 1O. The transfer paper P separated from the photosensitive drum l by curvature separation is
The toner image on the transfer paper P is fixed by the heating and pressure roller fixing device 7.

Further, the one-component developer remaining on the photosensitive drum after the transfer process is removed by a cleaning device having a cleaning blade.
will be removed. After cleaning, the photosensitive drum 1 is neutralized by erase exposure 6, and the process starting from the charging process by the negative charger 2 is repeated again. Next, the negatively charged toner used in the present invention will be described.

In the present invention, examples of the binder resin for the toner include polystyrene and poly-p-chlorostyrene.

Monopolymers of styrene and its substituted products such as polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid methyl copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer.

Styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-alpha-chloromethyl methacrylate copolymer Polymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinylethyl nityl copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer Combination, styrene-acrylonitrile-
Styrenic copolymers such as indene copolymers; polyvinyl chloride, polyvinyl acetate.

Polyethylene, polypropylene, silicone resin.

polyester, epoxy resin, polyvinyl butyral,
Rosin, modified rosin, terpene resin, phenolic resin,
Xylene resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins.

Paraffin wax and the like can be used alone or in combination.

In the present invention, among these resins, styrene-
Acrylic copolymers are preferably used, particularly styrene-n-butyl acrylate (St-nBA) copolymer, styrene-n-butyl methacrylate (St-nB
M A ) copolymer, styrene-n-butyl acrylate-2-ethylhexyl methacrylate (S t -n
B A -2E HMA ) copolymer and the like are preferably used.

Further, as coloring materials that can be added to the toner according to the present invention, conventionally known carbon black, copper phthalocyanine,
Iron black etc. can be used.

As the magnetic fine particles contained in the magnetic toner according to the present invention, substances that are magnetized by being placed in a magnetic field are used, such as powders of ferromagnetic metals such as iron, cobalt, and nickel, or magnetite, γ-Fe2O3° Alloys and compounds such as ferrite can be used.

These magnetic fine particles preferably have a BET specific surface area of 2 to 20 d/g, especially 2.5 to 12 rd/g, measured by nitrogen adsorption method.
g, and magnetic powder having a Mohs hardness of 5 to 7 is preferred. The content of this magnetic powder is preferably 10 to 70% by weight based on the toner m.

Further, the toner of the present invention may contain a charge control agent if necessary, such as a metal complex salt of a monoazo dye; salicylic acid;
A negative charge control agent such as a metal complex salt of alkyl salicylic acid, dialkyl salicylic acid or naphthoic acid is used.

Furthermore, the magnetic toner according to the present invention has a volume resistivity of 10
It is preferably 10 Ω·cm or more, particularly 10 12 Ω·cm or more from the viewpoint of triboelectric charge and electrostatic transferability. The volume resistivity referred to here is determined by molding the toner at a pressure of 100 kg/crrr and applying an electric field of 100 V/cm to it.
It is defined as a value converted from the current value one minute after application.

The negatively charged magnetic toner used in the present invention must have a tripocharge amount of 18 μc/g to 120 μc/g. When it is less than -8 μc/g, the image density tends to be low, and the effect is particularly noticeable under high humidity. Also -20μc/
If it exceeds g, the toner charge will be too high, resulting in thin line images and poor images especially under low humidity.

The negatively chargeable toner particles of the present invention are 950 to 6 at 25°C.
10 g of toner particles left overnight in an environment of 0% RH and 90 g of carrier iron powder (for example, EFV200/300 manufactured by Nippon Iron Powder Co., Ltd.), which is not coated with resin and has a main particle size of 200 to 300 mm. were thoroughly mixed in an aluminum pot having a volume of approximately 200 c, c, under the above-mentioned environment (hand-held and blotted up and down approximately 50 times), and placed in an aluminum cell with a 400 mesh screen. The amount of tribocharge of toner particles is measured using a conventional blow-off method.

By this method, toner particles whose measured triboelectric charge is negative are defined as negatively charged toner particles.

Further, the volume average particle diameter of the toner particles is preferably 5 to 30 μm, preferably 7 to 15 μm. 4 μm in number distribution
The following content is 2% to 20%, preferably 2 to 18%
is good.

A Coulter Counter TA-n model (manufactured by Coulter Co., Ltd.) is used as a measuring device for toner particle size, an interface (manufactured by Nikkaki) that outputs the number average distribution and volume average distribution, and a CX-1 personal computer (Canon Co., Ltd.) are used. ), and the electrolyte is 1st class sodium chloride.
% NaCl aqueous solution is prepared. As a measurement method, 0.1 of a surfactant, preferably an alkylbenzenesulfonate salt, is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution.
Add ~5 ml, and further add 0.5 to 50 mg of the measurement sample. The electrolyte solution in which the sample is suspended is mixed with an ultrasonic disperser for approximately 1 to 3 minutes.
The Coulter counter TAI
Type I is volumetrically manufactured using a 100μ aperture as the aperture to measure the particle size distribution of particles from 2 to 40μ.

(2) Uniformly disperse the binder resin and optionally the dye/pigment as the magnetic material 9 coloring agent using a mixer such as a Henschel mixer.

(2) Melt and knead the dispersion obtained above using a Nigu, extruder, roll mill, or the like.

■After coarsely pulverizing the kneaded material with a cutter mill, hammer mill, etc., finely pulverizing it with a jet mill, etc.

■Use a zigzag classifier to uniform the particle size distribution of the finely pulverized material and classify it into toner.

Other toner manufacturing methods that can be used include a polymerization method and a capsule method. An outline of these manufacturing methods will be described below.

(polymerized toner) ■Polymerizable monomer, polymerization initiator if necessary.

A coloring agent, etc. is granulated in an aqueous dispersion medium.

(2) Classifying the granulated monomer composition particles into appropriate particle sizes.

(2) Polymerizing the monomer composition particles having a specified particle size obtained by the above classification.

(2) After removing the dispersant through appropriate treatment, the polymerization product obtained above is filtered, washed with water, and dried to obtain a toner.

(Capsule toner) ■Knead resin and, if necessary, magnetic powder etc. using a kneader or the like to obtain a toner core material in a molten state.

■Pour toner core material into water and stir vigorously to create fine particle core material.

(2) Put the core material fine particles into the shell material solution, drop a poor solvent while stirring, and cover the core material surface with the shell material to encapsulate it.

(2) The capsules obtained above are filtered and dried to obtain a toner.

Next, a method for producing resin particles having an average particle size of 0.1 to 1.0 μm will be described. The insulating resin used for the resin particles in the present invention can be the same as the binder resin used for the above-mentioned toner, such as spray drying method, suspension polymerization method, emulsion polymerization method,
Soap-free polymerization method, seed polymerization method 9 mechanical crushing method, etc.
Any method that can produce spherical fine particles can be used. Among these, the soap-free polymerization method is particularly suitable, as it has the advantage of not inhibiting the toner's chargeability and producing a polymer with a narrow particle size distribution because there is no residual emulsifier. However, there are no particular limitations.

In particular, the resin particles used in the present invention include methyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, N-methyl-N-
Phenylaminoethyl methacrylate, diethylaminoethyl methacrylamide, dimethylaminoethyl methacrylamide.

8. Using resins from compositions containing monomers It is preferable.

It is essential that the resin particles are charged with a polarity opposite to that of the toner particles, and the particles may be subjected to surface treatment if necessary. Iron is the method of surface treatment.

Methods of surface treatment of metals such as nickel, cobalt, copper, zinc, gold, and silver by vapor deposition or plating methods, or ion adsorption or external addition of the above metals, magnetic materials, and metal oxides such as conductive zinc oxide. Alternatively, pigments or dyes, or organic compounds capable of triboelectric charging such as polymer resins may be supported by coating or external addition.

In any case, the specific resistance is l O'-1014Ω・cm (
7) Spherical fine particles are preferable. Specific resistance is 108
If it is lower than Ω·cm, the amount of charge on the toner particles will be significantly reduced, especially in a high temperature and high humidity environment, resulting in a decrease in image density, which is not preferable. Furthermore, if a resistivity higher than 1014 Ω·cm is used, “black spots” fogging due to flying toner particles is likely to occur in non-image areas on paper. This can be considered to be because the amount of charge of the spherical fine particles of opposite polarity increases significantly, and the toner particles existing near the fine particles are electrostatically attracted and reverse development is performed, but the details are not clear.

The particle size of the resin particles needs to be smaller than the toner particle size because it is necessary to have a large contact area with the toner particles, and for toner particles of about 12 μm, it is necessary to
Preferably, it is in the μm range.

Further, it is advantageous for the spherical fine particles to be as close to a true sphere as possible in terms of developer fluidity and uniform charging.

The amount of spherical fine particles added is 0.1 to the insulating magnetic toner.
~3% by weight, more preferably 0.3~0.5% by weight. If the amount is less than 0.1% by weight, no effect will be obtained, while if it is more than 3% by weight, the image density will decrease, which is not preferable.

The measurement of volume resistivity in the present invention is carried out using, for example, the apparatus shown in FIG. In the figure, 31 is a pedestal. 32 is a pressing means, which is connected to the hand press and has a pressure gauge 3.
3 is included. 34 is a hard glass cell with a diameter of 3.100 cm, into which a sample 35 is placed. 36 is a brass press ram, diameter 4, 266 cm, area 1
4.2857c rd037 is a stainless steel push rod,
Radius 0, 397 cm, area 0.496 c rd
Then, pressure from the press ram 36 is applied to the sample 35. 3
8 is a brass stand, 39 and 40 are Bakelite insulating plates. 41 is a resistance meter connected to the press ram 36 and the stand 38, and 42 is a dial gauge.

In the device shown in Figure 3, the hand press has a hydraulic pressure of 20 kg/
crr? When a pressure of 576 kg/kg is applied to the sample,
crrf pressure is applied. The resistance is read from the resistance meter 41, multiplied by the cross-sectional area of the sample, and divided by the height of the sample read from the dial gauge 42 to obtain the volume resistivity.

The developer used in the image forming method of the present invention preferably further contains hydrophobic silica fine powder.

In the case of a negatively chargeable magnetic component developer, the negatively chargeable magnetic toner 100 contains negatively chargeable hydrophobic silica fine powder and positively chargeable resin fine particles treated with a silane coupling agent and/or silicone oil. The silica o, oi to 3 parts by weight based on the weight part and the resin fine particles 0.0
The content is preferably 2 to 3 parts by weight.

The fine silica powder used in the present invention is so-called dry silica or fumed silica, which is produced by vapor phase oxidation of a silicon halide compound, and whose surface has been treated with a silane coupling agent and/or silicone oil. It is a fine silica powder.

A preferred silane coupling agent includes hexamethyldisilazane (HMDS). Further, as a preferable silicone oil, one having a viscosity of about 50 to 00 centistokes at 25°C is used,
For example, dimethyl silicone oil.

Preferable examples include methylphenyl silicone oil, α-methylstyrene-modified silicone oil, chlorphenyl silicone oil, and fluorine-modified silicone oil.

For the purpose of the present invention, -OH group, -COOH group.

Silicone oil containing a large amount of -NH2 groups, etc. is not preferred.

Known techniques are used for the silicone oil treatment; for example, fine silica powder and silicone oil may be directly mixed using a mixer such as a Henschel mixer, or silicone oil may be injected onto the base silica. It's also good. Alternatively, it may be prepared by dissolving or dispersing silicone oil in a suitable solvent, mixing it with the base silica fine powder, and removing the solvent.

The degree of hydrophobicity of fine silica powder in the present invention uses a value measured by the following method. Of course, other measurement methods can also be applied while referring to the measurement method of the present invention.

100mI of pure water in a sealed container! Add 1 g of sample and shake for 10 minutes using a shaker. After shaking, let stand for a few minutes to separate the silica powder layer and water layer, collect the water layer, and measure the transmittance at a wavelength of 500 nm using blank pure water without fine silica powder as a reference. The transmittance value is determined as the degree of hydrophobicity of the treated silica.

The degree of hydrophobicity of the silica fine powder in the present invention is 90% or more (more preferably 93% or more).

If the degree of hydrophobicity is less than this, a high-quality image cannot be obtained due to moisture adsorption of the silica fine powder under high humidity.

Further, the fine silica powder is negatively chargeable.

The tribo value of negatively charged silica fine particles is measured by the following method. That is, 2 g of fine silica powder left overnight in an environment of 25° C. and 50 to 60% RH and a non-resin-coated carrier iron powder having a main particle size of 200 to 300 mesh (for example, Nippon Iron Powder Co., Ltd.) Manufactured by EFV200/300
) and 98 g were thoroughly mixed in an aluminum pot having a volume of approximately 200 c, c, under the above-mentioned environment (by holding it in the hand and rotating it up and down approximately 50 times), and having a 400 mesh screen. The amount of triboelectric charge of silica fine particles is measured by the usual blow-off method using an aluminum cell.

Silica particles whose measured triboelectric charge becomes negative by this method are defined as negatively charged silica particles. In the present invention, the tribocharge amount is 1100゛μc/g to -300
Silica microparticles of μc/g are used.

The above silica fine particles are 0% per 100 parts by weight of toner particles.
．． The effect is exhibited when the amount is 0.01 to 3 parts by weight, and particularly preferably, a developer having excellent stability is provided when added in an amount of 0.05 to 2 parts by weight.

If it is less than 0.01 parts by weight, it causes a decrease in image density, and if it exceeds 3 parts by weight, fogging cannot be suppressed, which is not preferable.

A preferable addition form is 0.000000000000000000000000000000000000000000000,000. It is preferable that 2.5 parts by weight of O2N treated silica fine particles be attached to the surface of the toner particles.

The ratio of parts by weight of the silica and the resin particles used in the present invention is silica:resin particles=1:0.1 to 1:1.
A ratio of 0.00 is preferred. If the ratio of resin fine particles to the amount of silica (l) is less than 0.1, there is almost no effect on fogging. Moreover, if the ratio of resin fine particles to 1 of silica exceeds 100, this is undesirable as it causes a decrease in concentration.

Hereinafter, the present invention will be further explained with reference to Examples.

The above mixture was melted and kneaded in a two-screw ruder heated to 160°C, cooled, and the cooled material was crushed into a mesh with an opening diameter of 2 mm to the level of a bath using a hammer mill (mechanical crusher). Grind, then use a jet mill (wind-powered grinder) to
It was finely ground to about 0g. The finely pulverized product was classified using a DS classifier (wind classifier) so that the volume average particle diameter measured with a Coulter counter was 11.5 μm to prepare a negatively charged insulating magnetic toner.

The insulating magnetic toner had a triboelectric charge amount of -13 μc/g with respect to the iron powder carrier as measured by a blow-off method.

To 100 parts by weight of the negatively charged magnetic toner, spherical positively charged resin particles (average diameter 0.5 μm) of a copolymer mainly composed of structural units derived from methyl methacrylate monomer were added.
m,) ribocharge amount +450μC/g, sphericity approximately 1.0° Contains nitrogen-containing compound, specific electrical resistance value 6.5X1011Ω
・cm; Silica fine powder (BET specific surface area 130 rr?
/g of dry silica was treated with hexamethyldisilazane and then treated with dimethyl silicone; hydrophobicity degree 95
%, tribocharge amount -190 μc/g) was added and mixed in a Henschel mixer to obtain a -component developer.

The obtained developer was subjected to reversal development using a commercially available copying machine FC-5 (manufactured by Canon Corporation; OPC laminated type negatively charged photoreceptor, curvature separation type using a drum diameter of φ30, static elimination needle applied with a bias of -1.0 kV). Under the transfer conditions (Vtr = +700V) modified for use with 1.0, a gap was set so that the developer layer on the photosensitive tram and the developing drum (with magnet included) did not contact each other, and an alternating current bias (f = 1,800 Hz) was applied.

V,,=1,600V) and DC bias (Voc=
-500V) was applied to the developing drum while image formation was performed.

The toner fixed image produced and fixed by a heating and pressure roller was evaluated as follows. The results are shown in Table 1.

(1) Image density: Normal copying machine plain paper (75g/r&
) Evaluation was made by maintaining image density when 1,000 sheets were passed.

○ (Good) + 1.35 or more, △ (Acceptable): 1
．． 0 to 1.34゜× (not allowed): 1.0 or less (2) Transfer condition: Strict transfer conditions, 120 g/r
r? A thick piece of paper was passed through the paper, and transfer removal was evaluated based on the condition.

O: Good, Δ: Practical, ×: Not Practical (3) Wrapping condition: 1,000 sheets of 50 g/rrr thin paper were passed through and the occurrence of paper jams was evaluated.

○: Less than 1 time/1,000 sheets, △: 2-4 times/1,
000 pieces.

X: 5 times or more 71,000 sheets (4) Paper trace: All solid images were output and evaluated based on their uniformity.

○: Density difference 0.0 x 2 0.16 or more (5) Image quality: Toner scattering, roughness, etc. were visually evaluated.

○: Good, △: Practical, ×: Not Practicable" 1 The same procedure as Example 1 was carried out except that the transfer conditions were changed so that the ratio of Vtr/v, r was -0.5. I made an image. The results are shown in Table 1.

Image printing was carried out in the same manner as in Example 1, except that the transfer conditions were changed so that the ratio of V tr / V pr was -1.6. The results are shown in Table 1.

Image printing was carried out in the same manner as in Example 1, except that the transfer conditions were changed so that the ratio of V I- / V p was -2.0. The results are shown in Table 1.

Developed in the same manner as in Example 1, except that spherical resin particles having an average particle diameter of 0.1 μm and a triboelectric charge amount of +450 μc/g were used as positively chargeable resin particles. A sample was prepared, imaged and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Illusion u A developer was prepared in the same manner as in Example 1, except that spherical resin particles having an average particle diameter of 1.0 μm and a triboelectric charge amount of +380 μc/g were used as positively chargeable resin particles. was prepared, imaged and evaluated in the same manner as in Example 1. The results are shown in Table 1.

On a tributary] A developer was prepared in the same manner as in Example 1, except that spherical resin particles having an average particle diameter of 0.4 μm and a triboelectric charge amount of +50 μc/g were used as positively chargeable resin particles. was prepared, imaged and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Developed in the same manner as in Example 1, except that spherical resin particles having an average particle size of 0.4 μm and a triboelectric charge amount of +600 μc/g were used as positively chargeable resin particles. A sample was prepared, imaged and evaluated in the same manner as in Example 1. The results are shown in Table 1.

The true male side 1 except that 0.1 part by weight of spherical resin particles with an average particle diameter of 0.4 μm and a triboelectric charge amount of +400 μc/g were used as positively chargeable resin particles. A developer was prepared in the same manner as in Example 1, and images were produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

9m A developer was prepared in the same manner as in Example 1, except that the amount of positively chargeable resin particles added was 2.0 parts by weight, and images were formed and evaluated in the same manner as in Example 1. did. The results are shown in Table 1.

Comparison 1 A developer was prepared in the same manner as in Example 1, except that positively chargeable resin particles were not used, and images were formed and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 1 except that 0.4 parts by weight of spherical resin particles having an average particle diameter of 0.05 μm and a triboelectric charge amount of +800 μc/g were used as positively chargeable resin particles. A developer was prepared in the same manner as in Example 1, and images were produced and evaluated in the same manner as in Example 1.

The results are shown in Table 1.

Examples except that 0.4 parts by weight of spherical resin particles having an average particle size of 1.5 μm and a tribocharge amount of +30 μc/g were used as positively charged resin particles. A developer was prepared in the same manner as in Example 1, and images were produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 1 - The above materials were kneaded and crushed into 1 classification to obtain a volume average particle size of 12 μm.
Negatively charged one-component magnetic toner (tribocharge amount -10μ
c/g) was obtained.

The toner contains spherical resin fine particles (PMMA, particle size 0.4μ,
Specific resistance 109Ω・cm, triboelectric charge +450μC/g
) and 0.4 parts by weight of silicone oil-treated silica (tribocharged 1-200 μc/g) were mixed in a Henschel mixer to obtain a negatively charged one-component magnetic developer. This is a commercially available reversal development method, and V tr /
Using an LBP-SX (manufactured by Canon) laser beam printer with a V pr of -1.0 te, the
A durability test of 4,000 printouts was conducted at 4,000 sheets (65% RH). The results are shown in Table 2.

Example 1 except that the charge amount of the resin particles was +300μc/g
A printout durability test was conducted using the same developer as in Example 1. The results are shown in Table 2.

1JJLL Example 1 except that the charge amount of the main resin fine particles was +100 μc/g
The same developer as in Example 1 was used. The results are shown in Table 2.

Table 2 (described) Hollowness was evaluated by looking at the blankness of characters on cardboard (postcards).

Large "L carp" A The above materials are melted, kneaded, crushed and classified into 2 parts with a volume average particle size of 1.
111m negatively charged magnetic component toner (tribocharge amount)
1lt1c/g). A composition was prepared from 100 parts by weight of the toner, 0.4 parts by weight of fine silica powder (hydrophobicity 98%, tribocharging @ -200 μc/g) treated with dimethyl silicone oil, and a composition containing methyl methacrylate monomer as a main component. Resin fine particles (triboelectric charge +350
0.2 parts by weight (μc/g + average particle size 0.5 μm) were added and mixed to obtain a negatively chargeable one-component developer.

The developer was applied to a commercially available laser beam printer LBP-SX.
(manufactured by Canon) at normal temperature and humidity (20℃, 60% RH).
), low temperature and low humidity (15℃, 10%RH), high temperature and high humidity (
Evaluations were conducted under various environments (35° C., 85% RH). As a result, a good, durable image without cardboard fog and environmental dependence was obtained.

A developer was obtained in the same manner as in Example 14, except that the amount of resin fine particles added was changed to the same amount as in Example 14.

Silica fine powder treated with olefin-modified silicone oil instead of the silica fine particles of Example 14 (hydrophobicity 99%,
A developer similar to Example 14 was obtained except that 0.5 part of triboelectric charge amount -150 μc/g) was added.

Table 3

[Brief explanation of the drawing]

Among the accompanying drawings, FIG. 1 is a diagram schematically showing an image forming apparatus used in an embodiment of the present invention, and FIG. 2 shows a transfer portion where an AC bias and a DC bias are applied to the static elimination brush. An enlarged view is shown, and FIG. 3 is a diagram schematically showing a measuring device for measuring the specific electrical resistance value of powder. l・・・・・・・・・・・・・・・Photosensitive drum 2...
・・・・・・・・・・・・・・・Fukiyose Denki 3・・・・・・
・・・・・・・・・Transfer charger 4・・・・・・・・・
・・・Developing sleeve 5・・・・・・・・・・・・
・・・・・・River・Exposure 6・・・・・・・・・・・・・・・Erase exposure 7・・・・・・・・・Heating and pressure roller fixing device 8 ・・・・・・・・・・・・Blade cleaning device 9・・・・・・・・・・・・・・・Developer lO・・・・・・・・・River・River・・・・・・Static elimination brush 11... River... River... River... River... F12...... Bias application means Fig. 1 A

Claims (2)

[Claims] (1) In an image forming method in which an electrostatic charge image on an electrostatic image carrier is developed with a one-component developer, and the toner image formed on the electrostatic image carrier is electrostatically transferred to a transfer material, the electrostatic charge image is negatively charged. A one-component developer containing at least a toner and resin particles having an average particle size of 0.1 to 1.0 μm and a tribocharging property of +50 to +600 μc/g is used, and the primary charging electric field V_p_r and transfer charging are Electric field V_
An image forming method comprising electrostatically transferring a toner image on an electrostatic image carrier to a transfer material under conditions where the ratio (V_t_r/V_p_r) to t_r is negative. (2) Primary charging electric field V_p_r and transfer charging electric field V_t_
The absolute value of the ratio with r (V_t_r/V_p_r) is 0.5
The image forming method according to claim 1, wherein the toner image is electrostatically transferred to a transfer material under the conditions of 1.6 to 1.6.