JP3332697B2 - Image forming method and image forming toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

More specifically, an electronic device having a charging step of charging by bringing a charging member to which a voltage is applied from the outside into contact with a latent image holding member (photoreceptor) and a developing step of developing an electrostatic latent image using toner. The present invention relates to an image forming method used for a photographic method.

[0003]

2. Description of the Related Art Conventionally, a corona discharger has been known as a charging means in an electrophotographic apparatus or the like. However, corona dischargers have to apply a high voltage, so
There is a problem that a large amount of ozone is generated.

Recently, the use of contact charging means without using a corona discharger has been studied. JP 63
In JP-A-149668 and JP-A-63-149669, a voltage is applied to a conductive roller as a charging member, and the roller is brought into contact with a photoreceptor as a member to be charged to bring the surface of the photoreceptor to a predetermined potential. It is charged. If such a contact charging unit is used, the voltage can be reduced as compared with a corona discharger, and the amount of ozone generated decreases. When such a contact charging device is used, the charging member is used by applying a DC voltage or a DC voltage with an AC voltage superimposed thereon,
At this time, in the vicinity of the contact portion between the charging member and the photosensitive drum, abnormal charging of the residual toner, which is particularly small and light in weight, and repetition of flying motion are repeated. The embedding is easily performed, which is very different from the case where a non-contact charging means using a conventional corona discharger is used.

On the other hand, in recent years, small and inexpensive personal use copying machines and laser printers have emerged. In these small machines, a cartridge system in which a photoconductor and a cleaning device are integrated from a maintenance-free standpoint is used. It is desirable to use a one-component developer because the structure of the developing device can be simplified as the toner.

In such a method using a one-component toner, many studies have been made in order to obtain a high quality image having high fixing performance and anti-offset property, excellent reproducibility of fine lines, and stable and good images. I have.

For example, in order to prevent the toner from adhering to the surface of the fixing roller, the roller surface is formed of a material such as a fluorine-based resin which is excellent in releasability from the toner.
An anti-offset liquid such as silicone oil is further supplied to the surface to coat the roller surface with a thin film of the liquid. Although this method is extremely effective in preventing toner offset, it generates odor by heating the offset prevention liquid,
Further, since a device for supplying the liquid for preventing offset is required, the mechanism of the copying apparatus becomes complicated, and high precision is required to obtain a stable result, so that the copying apparatus becomes expensive. There is a disadvantage that.

Further, conventionally, there is known a technique in which a low-melting substance is contained in a toner to improve the fixing property and the offset resistance.

However, when a toner containing a low-melting substance having a relatively low melting point, which is particularly effective in improving the fixing property among the low-melting substances, is used in an image forming apparatus having a contact charging device, The present inventors have found that the toner easily fuses to the photoreceptor surface.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method and an image forming toner which solve the above-mentioned conventional problems.

That is, an object of the present invention is to provide an image forming method and an image forming toner which are excellent in fixing property and offset resistance.

Another object of the present invention is to provide an image forming method and an image forming toner in which toner fusion does not or hardly occur on a photosensitive member in an image forming method having a contact charging step.

Another object of the present invention is to provide a high image density,
An object of the present invention is to provide an image forming method and an image forming toner capable of obtaining a good image.

[0014]

According to the present invention, there is provided a charging step of charging a latent image holding member by bringing a charging roller, charging blade or charging brush to which an external voltage is applied into contact with the latent image holding member. A step of forming a charge image, a step of developing an electrostatic latent image formed on the latent image holder with toner disposed on a toner carrier to form a developed image, and a step of forming the latent image holder Provided to apply pressing force to
An image forming method having a transfer step of forming a transfer image by transferring a toner image on the latent image holding member to a material to be transferred by a transfer charger to which a bias is applied , wherein the toner contains at least a binder resin and A low-melting substance having a melting point of 120 ° C. or less is added in an amount of
Mass part of the toner, the latent image holding member is an organic photoreceptor, and in the developing step, the latent image holding member and the toner holding member T ₁ times the toner from the latent image bearing member a voltage of flying from the voltage and the toner carrying member to pull back the toner carrying member to the latent image bearing member to the toner carrying member during, after applying at least once, with respect to the image portion by ejecting toner, is applied T ₂ hours the direction of a voltage pull back the toner to the toner carrying member to the non-image portion, the image, wherein the ratio of T ₂ / T ₁ is 0.2 to 10 With respect to a forming method and an image forming toner, the above problem can be solved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of an image forming method according to the present invention will be specifically described using the image forming apparatus shown in FIG.

In FIG. 1, the surface of the photosensitive member 1 is charged by a primary charger 7. In the present invention, a charging device that performs charging by contacting as a primary charger is used.

As a contact charging method, there is a method using a roller, a blade, or a brush. Among these, a method using a roller is particularly preferable.

The charging roller is basically composed of a central core metal and a conductive elastic layer forming the outer periphery thereof.
The charging roller 7 is pressed against the surface of the photoconductor 1 with a pressing force, and is rotated by the rotation of the photoconductor 1. When a bias is applied to the charging roller 7, the surface of the photoconductor 1 is charged to a predetermined polarity and potential. Next, an electrostatic image is formed by image exposure, and is sequentially visualized as a toner image by a developing unit. As a preferable process condition when the charging roller is used, the contact pressure of the roller is 0.5
When a voltage obtained by superimposing an AC voltage on a DC voltage is used, the AC voltage is 0.5 to 5 kV _pp , the AC frequency is 50 to 5 kHz, and the DC voltage is ± 0.2 to ± 1.
5 kV. The contact pressure is calculated by the following formula.

[0019]

(Equation 1)

A release film may be provided on the surface of the charging roller. Nylon resin, PVD
F (polyvinylidene fluoride), PVDC (polyvinylidene chloride) and the like are applicable. The charging roller includes a central metal core and a conductive elastic layer forming an outer periphery. The conductive elastic layer is formed of urethane or ethylene-propylene-diene-based terpolymer in which a conductive material such as carbon is dispersed ( E
It is made of an elastic material such as PDM) having a volume resistance of about 10 ⁴ to 10 ⁸ Ω · cm.

The organic photoreceptor used in the present invention may be a so-called single layer type in which the photosensitive layer contains a charge generating substance and a substance having a charge transporting property in the same layer, and the charge transporting layer and the charge generating layer are composed of components. May be used. A laminated photoreceptor having a structure in which a charge generation layer and a charge transport layer are laminated on a conductive substrate in this order is one of preferred examples.

The embodiment of the organic photoreceptor used in the present invention will be described in detail below.

Examples of the conductive substrate include metals such as aluminum and stainless steel, aluminum alloys and indium oxide.
Cylindrical cylinders and films of plastic having a coating layer of a tin oxide alloy or the like, paper impregnated with conductive particles, plastic, plastic having a conductive polymer, and the like are used.

On these conductive substrates, the adhesion of the photosensitive layer is improved, the coating properties are improved, the substrate is protected, defects on the substrate are covered,
An undercoat layer may be provided for the purpose of improving the charge injection property from the substrate, protecting the photosensitive layer against electrical destruction, and the like. The undercoat layer is made of polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenol resin, casein, polyamide, copolymerized nylon, glue,
It is formed of a material such as gelatin, polyurethane, and aluminum oxide. The film thickness is usually 0.1 to 10 μm,
Preferably it is about 0.1 to 3 μm.

The charge generation layer is made of an azo pigment, a phthalocyanine pigment, an indigo pigment, a perylene pigment, a polycyclic quinone pigment, a squarylium dye, a pyrylium salt, a thiopyrylium salt, a triphenylmethane dye, selenium,
A charge generating substance such as an inorganic substance such as amorphous silicon is dispersed in an appropriate binder and formed by coating or vapor deposition. The binder can be selected from a wide range of binder resins, for example, polycarbonate resin, polyester resin, polyvinyl butyral resin, polystyrene resin, acrylic resin, methacryl resin, phenol resin, silicone resin, epoxy resin, vinyl acetate resin, etc. Is mentioned. The amount of the binder contained in the charge generation layer is 80% by mass.
Hereinafter, it is preferably selected from 0 to 40% by mass. Further, the thickness of the charge generation layer is preferably 5 μm or less, particularly preferably 0.05 to 2 μm.

The charge transport layer has a function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting them. The charge transporting layer is formed by dissolving a charge transporting material in a solvent together with a binder resin if necessary, and applying the solution. The film thickness is generally 5 to 40 μm, preferably 10 to 30 μm. Examples of the charge transport substance include polycyclic aromatic compounds having a structure such as biphenylene, anthracene, pyrene, or phenanthrene in a main chain or a side chain; nitrogen-containing cyclic compounds such as indole, carbazole, oxadiazole, and pyrazoline; hydrazone compounds; Styryl compounds, selenium, selenium-tellurium, amorphous silicon,
Cadnium sulfide and the like can be mentioned.

The binder resin for dispersing these charge transporting substances includes polycarbonate resin, polyester resin, polymethacrylate, polystyrene resin, and the like.
Examples include resins such as acrylic resins and polyamide resins, and organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene.

Among these binder resins, polycarbonate resin, polyester resin, and acrylic resin are particularly preferable in the case of the image forming method according to the present invention because of their good cleaning properties, poor cleaning and fusion of toner to the photosensitive member. In addition, filming of the external additive hardly occurs. The amount of the binder resin in the charge transport layer is preferably from 40 to 70% by mass.

A latent image is formed on the uniformly charged photoreceptor by exposure 8, and is developed by the developing unit 2. that time,
Applying a bias between the toner carrier and the latent image carrier,
The toner is made to fly on the drum to visualize the latent image.

In the present invention, the voltage between the latent image carrier and the toner carrier as a bias is used to draw the toner from the latent image carrier to the toner carrier and the voltage for causing the toner to fly from the toner carrier to the latent image carrier. after applying at least time T ₁ at least once carrier, for the image portion causes the toner to fly, applying T ₂ hours the direction of a voltage pull back the toner to the toner carrying member for the non-image portion. Moreover, T ₂ /
T ₁ is 0.1 or more.

The reason why the use of this special bias can prevent the toner from being fused to the organic photoreceptor, which is a latent image holding member, even when a toner containing a low melting point substance is used is considered as follows.

By the force of the developing electric field applied to the developing area,
The toner flies from the toner carrier toward the photoconductor, which is a latent image holding member, and collides with the photoconductor surface. It is considered that the heat generated by the impact of the collision causes the resin component / low-melting substance component in the vicinity of the toner surface to melt, thereby causing fusion on the surface of the photoconductor.

The impact force of the toner on the photoreceptor surface depends on the magnitude of the developing electric field applied to the developing area, which is determined by the magnitude of the voltage (peak-to-peak) of the AC component of the bias applied to the toner carrier. It is almost decided by. However, the voltage of the AC component needs to have a certain magnitude in order to obtain a sufficient image density, and cannot be reduced more than necessary in order to prevent fusion of toner on the surface of the photoconductor.

However, the discontinuous AC component of the developing electric field used in the present invention has a smaller number of times that the toner collides with the photoreceptor surface per unit time than the continuous AC component generally used in the related art. Since the time during which the toner is pressed against the surface of the photoreceptor by the strong electric field is short, the amount of heat generated by the collision and the chance of fusing are small, and it is considered that toner fusion to the surface of the photoreceptor can be prevented. I have.

In the present invention, T ₁ / T ₂ ≧ 0.1, furthermore, 0.2 ≦ T ₂ / T ₁ ≦ 10, furthermore, 0.3 ≦ T ₂ / T ₁ ≦
6 is preferable. When T ₂ / T ₁ <0.1, there is no effect of preventing fusion of the toner to the photoconductor.

The magnitude of the electric field of the AC component superimposed in the developing area (V _pp / SD) (the peak-to-peak voltage value of the bias applied to the gap between the latent image carrier and the toner carrier / the latent image carrier) The gap between the toner carriers is 4.0.
× 10 ⁶ ≦ V _pp /SD≦8.0×10 ⁶ (V / m), and further, 5.0 × 10 ⁶ ≦ V _pp /SD≦8.0×10 ⁶ (V / m)
The present invention is particularly effective when it is in the range of m).
In the case of 4.0 × 10 ⁶ > V _pp / SD (V / m), a sufficient image density cannot be obtained, and 8.0 × 10 ⁶ <V _pp
In the case of / SD (V / m), leakage to the photoconductor is likely to occur.

As the developing electric field used in the present invention, in addition to the DC component, the frequency (f) of the superimposed discontinuous AC component
Is preferably 100 <f <3000 (Hz).

The time T ₁ is 0.15 to
It is preferably 2.5 msec.

The developed toner is transferred to a transfer material by a transfer charger 4. In the present invention, a system using a transfer roller is preferable. The transfer roller has a basic configuration including a central core metal and a conductive elastic layer that forms the outer periphery thereof. The transfer roller 4 is pressed against the surface of the photoconductor 1 with a pressing force, and is rotated at a constant speed with respect to the peripheral speed of the photoconductor 1 or with a difference in the peripheral speed.

The transfer material is conveyed between the photoreceptor 1 and the transfer roller 4, and at the same time, a bias having a polarity opposite to that of the toner is applied to the transfer roller 4 from a transfer bias current 10. The image is transferred to the front side of the transfer material.

As the material of the transfer rotary member applicable to the present invention, the same material as that of the charging roller can be used. The preferable transfer process condition is that the contact pressure of the roller is 0.5 to 5.0. 50 kg / m, DC voltage is ±
0.2 to 10 kV.

Next, the toner used in the image forming method of the present invention will be described.

In the image forming method of the present invention, the melting point is 120 ° C.
A toner containing the following low-melting substance is used. By using a low melting point substance having a melting point of 120 ° C. or lower, high fixability and good offset resistance can be obtained.

The low melting point substance used in the present invention includes:
Examples thereof include a crystalline resin, a fatty acid compound, and a wax.

Examples of the crystalline resin include a crystalline polyester resin and a silicone resin.

As fatty acid compounds, stearic acid,
Fatty acids such as palmitic acid and lauric acid, and their metal salts, esters, amides, and the like.

Examples of the wax include paraffin wax and its derivatives, montan wax and its derivatives, microcrystalline wax and its derivatives, Hisher Tropsch wax and its derivatives, polyolefin wax and its derivatives, carnauba wax, candelilla wax, and other natural waxes. And their derivatives, etc.
Derivatives include oxides, block copolymers with vinyl monomers, and graft-modified products.

In addition, alcohols, fatty acids, acid amides,
Esters, ketones, hydrogenated castor oil and derivatives thereof, vegetable waxes, animal waxes, mineral waxes, petrolactam and the like can also be used.

In the present invention, the low-melting substance is preferably contained in an amount of 0.2 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, based on 100 parts by mass of the binder resin of the toner.

The melting point of the low-melting substance according to the present invention is measured by a high-precision internal heating type input compensation type differential scanning calorimeter. For example, DSC-7 manufactured by PerkinElmer can be used. The measuring method is performed according to ASTM D3418-82. The DSC curve used in the present invention was obtained by raising the temperature once and taking a pre-history, then at a temperature rate of 10 ° C./min and a temperature of 0 to 2 °.
DS measured when the temperature is lowered and raised in the range of 00 ° C
Use the C curve. The endothermic peak temperature is a peak temperature in the positive direction in the DSC curve, that is,
The point at which the differential value of the peak curve becomes 0 when the value changes from positive to negative.

The kind of the binder resin used in the present invention includes, for example, a homopolymer of styrene such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene and a substituted product thereof; styrene-p-chlorostyrene copolymer. Copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene- Acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile- Styrene copolymers such as indene copolymers Coalescence; polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin , Polyvinyl butyral, terpene resin, cumarone indene resin, petroleum resin and the like can be used. Further, a crosslinked styrene resin is also a preferable binder resin.

Examples of comonomers for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and the like.
Such as dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, etc. A monocarboxylic acid having a heavy bond or a substituted product thereof;
For example, a dicarboxylic acid having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate, and the like; and vinyl chloride;
Vinyl esters such as vinyl acetate, vinyl benzoate and the like, for example, ethylene olefins such as ethylene, propylene, butylene and the like; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone;
For example, vinyl monomers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; and the like, or a vinyl monomer such as vinyl monomers, may be used alone or in combination. Here, as the cross-linking agent, a compound having two or more polymerizable double bonds is mainly used, for example, an aromatic divinyl compound such as divinylbenzene, divinylnaphthalene or the like; for example, ethylene glycol diacrylate, ethylene glycol Dimethacrylate,
Carboxylic esters having two double bonds such as 1,3-butanediol dimethacrylate; divinyl compounds such as divinylaniline, divinylether, divinylsulfide, divinylsulfone; and compounds having three or more vinyl groups; Can be used alone or as a mixture.

Examples of the binder resin for toner used for pressure fixing include low molecular weight polyethylene, low molecular weight polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, higher fatty acid and polyamide. Resins and polyester resins. These are preferably used alone or as a mixture.

It is also preferable to include the following waxes in the toner from the viewpoint of improving the releasability from the fixing member during fixing and improving the fixing property. Paraffin wax and its derivatives, microcrystalline wax and its derivatives, Fischer-Tropsch wax and its derivatives, polyolefin wax and its derivatives, carnauba wax and its derivatives, etc., and the derivatives include block copolymers with oxides and vinyl monomers, Including graft-modified products.

In addition, alcohols, fatty acids, acid amides,
Esters, ketones, hydrogenated castor oil and derivatives thereof, vegetable waxes, animal waxes, mineral waxes, petrolactam and the like can also be used.

The toner used in the present invention is most preferably in the form of a magnetic toner containing a magnetic substance. As the magnetic material to be used, an alloy or compound powder containing a ferromagnetic element is preferably used. For example, alloys and compounds such as iron, cobalt, nickel, manganese, and zinc, such as magnetite, maghemite, and ferrite, and other ferromagnetic alloys, which are conventionally known as magnetic materials, can be used.

In the toner of the present invention, it is preferable to use a charge control agent in the toner particles by mixing (internal addition) or mixing with the toner particles (external addition). The charge control agent makes it possible to control the amount of charge optimally according to the development system.

The following substances control the toner to be negatively charged.

For example, organic metal complexes and chelate compounds are effective, and examples thereof include monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid-based metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

The following substances are controlled to be positively charged.

Modified products such as nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate and tetrabutylammonium tetrafluoroborate, and phosphonium salts which are analogs thereof Onium salts such as, for example, these lake pigments, triphenylmethane dyes and these lake pigments (as the lacking agent, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanic acid) , Ferrocyanide, etc.), metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, dicyclohexyl Diorgano tin borate such as Suzuboreto; can be used in combination singly or two or more kinds.

The charge control agents described above are preferably used in the form of fine particles. In this case, the number average particle size of these charge control agents is particularly preferably 4 μm or less, more preferably 3 μm or less. When these charge control agents are internally added to the toner, it is preferable to use 0.1 to 20 parts by mass based on 100 parts by mass of the binder resin.

As the colorant that can be further added to the toner of the present invention, conventionally known carbon black, copper-phthalocyanine and the like can be used.

The toner of the present invention has a charge stability,
In order to improve developability, fluidity, and storage stability, it is preferable to add an inorganic fine powder such as a fine silica powder, titanium oxide, or aluminum oxide.

For example, such a silicic acid fine powder is a so-called dry method produced by a vapor phase oxidation of a silicon halide or alkoxide, or a dry silica called fumed silica, and a so-called dry method produced from water glass or silicon alkoxide. Both wet silica can be used, but there are few silanol groups on the surface and inside the silica fine powder,
Further, dry silica such as Na ₂ O, SO ₃ ^2- or the like which has a small production residue is more preferable.

In the case of dry silica, a fine composite powder of silica and another metal oxide can be obtained by using another metal halide such as aluminum chloride and titanium chloride together with a silicon halide in the production process. It is possible and encompasses them. Fine silica powder used in the present invention is the specific surface area by nitrogen adsorption measured by BET method 30 m ² / g or more, particularly 50 to 400 m ² /
A range of g gives good results, and it is preferable to use 0.01 to 8 parts by mass, preferably 0.1 to 5 parts by mass of silica powder with respect to 100 parts by mass of the toner. Further, the silica fine powder used in the present invention, if necessary, for the purpose of hydrophobicity, charge control and the like, silicone varnish, silicone oil,
Various modified silicone oils, silane coupling agents, silane coupling agents having a functional group, and other treating agents such as an organosilicon compound, or can be treated in combination with various treating agents, and is preferable. .

The toner of the present invention includes a lubricant powder such as Teflon powder, zinc stearate powder and polyvinylidene fluoride powder, an abrasive such as cerium oxide, silicon carbide and strontium titanate; A fluidizing agent, an anti-caking agent, or a conductivity-imparting agent such as carbon black, zinc oxide, and tin oxide may be used.

To prepare the toner according to the present invention, a binder resin, a low-melting substance, a metal salt or a metal complex, a pigment or dye as a colorant, a magnetic substance, a charge control agent, Additives, etc. are thoroughly mixed with a mixer such as a Henschel mixer or a ball mill, and then melt-kneaded using a heat kneader such as a heating roll, kneader, extruder, and the like. The toner according to the present invention can be obtained by dispersing or dissolving a pigment, a dye, and a magnetic material, and solidifying by cooling and then pulverizing and classifying.

[0069]

【Example】

 [Example 1] Styrene-butyl acrylate copolymer 100 parts by mass Magnetic substance (magnetite) 100 parts by mass Monoazo iron complex (negative charge control agent) 2 parts by mass Aliphatic alcohol wax (endothermic peak temperature: about 105 ° C) 4 Parts by mass

The above materials were mixed in a blender,
Melted and kneaded with a twin-screw extruder heated to ℃, coarsely pulverized the cooled kneaded material with a hammer mill, finely pulverized the coarsely pulverized material with a jet mill, and multi-divided the obtained finely pulverized material using the Coanda effect The toner particles were strictly classified by a machine. To the obtained toner particles, dry silica hydrophobized with 1.2% by mass of hexamethyldisilazane was added and mixed with a mixer to have a volume average particle size (D ₄ ) of 7.0 μm.
m of toner A was obtained.

In the configuration of FIG. 1, the primary charging roller 7
As a rubber roller (diameter 12 mm, contact pressure 5 kg / m) with dispersed conductive carbon coated with nylon resin
DC voltage: -700V, AC voltage: 2.2k
V is applied to charge the organic cylindrical photoreceptor 1 (OPC drum) having a diameter of 30 mm, the outermost layer of which is formed from a styryl compound and a polycarbonate resin, and the dark portion potential V _D = −700 V by laser exposure. Potential V _L = −150
V. A developing sleeve in which a resin layer having the following configuration was formed on a 16φ aluminum cylinder as the toner carrier 9 was formed.

Phenol resin 100 parts by mass Graphite (particle size: about 7 μm) 90 parts by mass Carbon black 10 parts by mass

Next, the gap between the photosensitive drum and the developing sleeve was set to 200 μm, and the developing magnetic pole was 7 Tesla (700 G).
1.0mm thickness, 10m free length as toner regulating member
m of urethane rubber blade was contacted with a linear pressure of 1.5 kg / m. The peripheral speed of the latent image carrier was 96 mm / sec, and the developing bias was the waveform bias shown in FIG. 2B (DC bias component V _dc = -500 V, maximum development promoting voltage = -1100 V, maximum pullback voltage = 100 V, T
₁ = _0.56msec, using _{T 2 / T 1 = 2.0)} .
The photosensitive member cleaning blade 6 has a thickness of 2.0 mm,
2.5 kg urethane rubber blade with 8 mm free length
/ M linear pressure. Using magnetic toner A as a toner, images were continuously formed under an environment of 23 ° C. and 65% RH.

As a result, no toner fusion occurred on the photosensitive member. In addition, the image density was high, and a good quality image was obtained.

Examples 2 to 5, Comparative Example 1 An experiment was performed in the same manner as in Example 1 except that T ₂ / T ₁ in the image forming apparatus used in Example 1 was changed as shown in the table. Done. Table 1 shows the experimental results.

[Embodiments 6 to 8] The peak-to-peak voltage value (V _pp ) of the bias applied to the gap between the latent image carrier and the toner carrier in the image forming apparatus used in the first embodiment.
The experiment was performed in the same manner as in Example 1 except that the values were changed as shown in Table 2. Table 2 shows the experimental results.

[Embodiments 9 to 10] The same as the embodiment 1 except that the gap (SD) between the latent image carrier and the toner carrier in the image forming apparatus used in the embodiment 1 is changed as shown in Table 2. An experiment was performed similarly. Table 2 shows the experimental results.

[Example 11] Carnauba wax (melting point 82 ° C) was used as the developer in Example 1 to reduce the hydrocarbon low melting point substance.
A toner B was obtained in the same manner as in Example 1 except that the toner was changed to the above, and an experiment was performed in the same manner as in Example 1. Table 2 shows the experimental results.

Example 12 Magnetic iron oxide 80 parts by mass Styrene-butyl acrylate copolymer 100 parts by mass Triphenylmethane dye (positive charge control agent) 2 parts by mass Aliphatic alcohol wax (endothermic peak temperature: about 105 ° C) 4 parts by mass

The above materials were mixed in a blender,
Melted and kneaded with a twin-screw extruder heated to ℃, coarsely pulverized the cooled kneaded material with a hammer mill, finely pulverized the coarsely pulverized material with a jet mill, and multi-divided the obtained finely pulverized material using the Coanda effect The toner was strictly classified by a machine to obtain toner particles having a volume average particle diameter of 7.8 μm. Dry silica (B) hydrophobized with 0.8% by mass of an aminosilane coupling agent and hexamethyldisilazane was used for the obtained toner particles.
ET specific surface area 100 m ² / g) was added and mixed with a mixer to obtain magnetic toner C.

In the configuration of FIG. 1, a rubber roller (diameter: 12 mm, contact pressure: 5 kg / m) in which conductive carbon coated with nylon resin is dispersed is used as a primary charging roller. : 2.2 kV
And apply an organic cylindrical photoreceptor (OPC) having a diameter of 30 mm.
Drum) and the dark area potential V _D by a halogen lamp.
= −700 V, and the bright potential V _L = −150 V. As a toner carrier, the surface with an outer diameter of 16φ is Arundum # 4
The surface was roughened by a blast treatment of 00 to produce an aluminum cylindrical sleeve.

Next, the gap between the photosensitive drum and the toner carrier was set to 200 μm, and the developing magnetic pole was 7 Tesla (700 G).
1.0mm thick, 10mm free length as toner regulating member
The urethane rubber blade was contacted with a linear pressure of 1.0 kg / m. The peripheral speed of the latent image carrier is 96 mm / sec, the peripheral speed of the toner carrier is 150 mm / s, and the waveform bias shown in FIG. 2B (DC bias component V _dc = −200 V, maximum development acceleration) Voltage = + 400V,
The maximum pull-back voltage = -800V, T ₁ = 0.56mse
c, T ₂ / T ₁ = 2.0).

A urethane rubber blade having a thickness of 2.0 mm and a free length of 8 mm was brought into contact with the photosensitive member cleaning blade at a linear pressure of 2.5 kg / m.

Using the above magnetic toner C as a toner,
Images were continuously output under an environment of 23 ° C. and 65% RH.
Table 3 shows the results.

Comparative Example 2 Evaluation was performed in the same manner as in Example 12 except that T ₂ / T ₁ of the developing bias in Example 12 was 0. Table 3 shows the results.

[0086]

[Table 1]

[0087]

[Table 2]

[0088]

[Table 3] In the evaluation of fusion, no ○ is generated on the photoreceptor. O is slightly generated on the photoreceptor, but is not generated on the image. X indicates that fusion was conspicuous on the image. In the evaluation of density, a solid black image was used. The waveform biases of Comparative Examples 1 and 2 are as shown in FIG.

[0089]

According to the present invention, even when a toner containing a low-melting substance is used, fusion of the toner to the photoreceptor can be prevented by using the special bias as described above, and the fixing property and the resistance to toner can be improved. An image forming method with excellent offset properties can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of an image forming method of the present invention.

2A is a schematic diagram of a developing bias waveform of a comparative example, and FIG. 2B is a schematic diagram of a developing bias waveform of an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoreceptor (latent image holding body) 2 Developing device 4 Transfer charger 6 Cleaning blade 7 Primary charger 8 Exposure 9 Toner carrier 10 Voltage applying means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-53969 (JP, A) JP-A-60-53968 (JP, A) JP-A-60-134262 (JP, A) 160013 (JP, A) JP-A-7-104496 (JP, A) JP-A-7-175317 (JP, A) JP-A-3-233480 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/08 G03G 9/08 365

Claims (11)

(57) [Claims] 1. A charging roller or belt to which a voltage is externally applied.
A charging step of charging an electrostatic blade or a charging brush by contacting the latent image holding member, a step of forming an electrostatic charge image on the charged latent image holding member, and a step of forming an electrostatic latent image formed on the latent image holding member. A developing step of forming a developed image by developing with toner disposed on the toner carrier, and pressing force on the latent image holder
Bias is applied to provide
An image forming method comprising a transfer step of transferring a toner image on the latent image holding member to a transfer material by a transfer charger to form a transfer image, wherein the toner has at least a binder resin and a melting point of 120 ° C. or less. A toner having a low-melting substance in an amount of 0.2 to 15 parts by mass with respect to 100 parts by mass of the binder resin, wherein the latent image carrier is an organic photoreceptor; In the developing area of the toner carrier opposed to the toner carrier, a voltage between the latent image carrier and the toner carrier is used to return the toner from the latent image carrier to the toner carrier and a voltage for causing the toner to fly from the toner carrier to the latent image carrier. After applying to the carrier at least once for T ₁ hour,
A voltage is applied to the toner carrier for a period of T ₂ for causing the toner to fly to the image portion and pulling the toner back to the non-image portion, and the ratio of T ₂ / T ₁ is 0.2 to 10. An image forming method comprising: 2. A voltage value for returning toner from the latent image carrier to the toner carrier between the latent image carrier and the toner carrier and a voltage for causing the toner to fly from the toner carrier to the latent image carrier in the developing step. (V _pp ) divided by the gap (SD) between the latent image holding member and the toner holding member is from 4.0 × 10 ⁶ to 8.
2. The method according to claim 1, wherein the voltage is 0 × 10 ⁶ (V / m).
2. The image forming method according to 1., 3. The image forming method according to claim 1, wherein a thickness of the toner layer disposed on the toner carrier is smaller than a gap between the latent image carrier and the toner carrier. 4. In the developing step, a developing bias in which a discontinuous alternating current component is superimposed on a direct current component is applied to the toner carrier to develop an electrostatic image with toner disposed on the toner carrier. The image forming method according to claim 1, wherein: 5. The frequency (f) of the discontinuous AC component is 10
5. The image forming method according to claim 4, wherein the frequency is higher than 0 Hz and lower than 3000 Hz. 6. A transfer roller, wherein the transfer charger is a transfer roller.
The pressing force of the roller on the latent image holding member is 0.5 to 50 kg / m.
The method according to any one of claims 1 to 5, wherein
Image forming method. 7. A charging roller or belt to which a voltage is externally applied.
A charging step of charging an electrostatic blade or a charging brush by contacting the latent image holding member, a step of forming an electrostatic charge image on the charged latent image holding member, and a step of forming an electrostatic latent image formed on the latent image holding member. A developing step of forming a developed image by developing with toner disposed on the toner carrier, and pressing force on the latent image holder
Bias is applied to provide
A transfer charger for transferring the toner image on the latent image holding member to a transfer material by a transfer charger to form a transfer image; wherein the latent image holding member is an organic photoreceptor; A voltage is applied between the latent image carrier and the toner carrier to return the toner from the latent image carrier to the toner carrier in the developing area of the carrier and the toner carrier opposed thereto, and the toner flies from the toner carrier to the latent image carrier. After applying the voltage to be applied to the toner carrier at least once for T ₁ hour,
A voltage is applied to the toner carrier for a period of T ₂ for causing the toner to fly to the image portion and pulling the toner back to the non-image portion for T ₂ , and the ratio of T ₂ / T ₁ is 0.2 to 10. An image forming toner for use in an image forming method, wherein the toner contains at least a binder resin and a low-melting substance having a melting point of 120 ° C. or less per 100 parts by mass of the binder resin. An image forming toner having a mass part. 8. The voltage between the latent image holding member and the toner carrier in the developing step, wherein the toner pulls the toner from the latent image holding member to the toner carrier and the toner flies from the toner carrier to the latent image holding member. The value obtained by dividing the difference (V _pp ) of the voltages to be applied by the gap (SD) between the latent image holding member and the toner holding member is 4.0 ×
The image forming toner according to claim 7 , wherein the toner is used in an image forming method of 10 ^{6 to} 8.0 × 10 ⁶ (V / m). 9. The image forming method according to claim 1, wherein the thickness of the toner layer disposed on the toner carrier is smaller than a gap between the latent image carrier and the toner carrier. the image forming toner according to claim 7 or 8. 10. In the developing step, a developing bias in which a discontinuous AC component is superimposed on a DC component is applied to the toner carrier in the developing step, and an electrostatic image is formed by the toner disposed on the toner carrier. The image forming toner according to any one of claims 7 to 9 , which is used in an image forming method for developing. 11. The transfer charging device is a transfer roller,
The pressing force of the roller against the latent image holding member is 0.5 to 50 kg / m.
The method according to any one of claims 7 to 10, wherein
The toner for image formation according to the above.