JP2646284B2 - Negatively chargeable non-magnetic color toner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a negatively chargeable nonmagnetic color toner in electrophotography.

[Related Art] Conventionally, a corona discharger has been known as a charging unit in an electrophotographic apparatus or the like. However, corona dischargers have problems such as the need to apply a high voltage and the generation of a large amount of ozone.

Therefore, recently, the use of contact charging means without using a corona discharger has been studied. Specifically, a voltage is applied to a conductive roller serving as a charging member, and the roller is brought into contact with a photosensitive member serving as a member to be charged to charge the surface of the photosensitive member to a predetermined potential. If such a contact charging means is used, the voltage can be reduced as compared with a corona discharger, and the amount of generated ozone can be reduced.

For example, Japanese Patent Publication No. Sho 50-13661 discloses that a low voltage can be applied when charging a photoreceptor by using a roller having a core covered with a dielectric made of nylon or polyurethane rubber. However, in the above conventional example, when the core metal is coated with nylon, it is not possible to maintain sufficient contact with the member to be charged because there is no elasticity such as rubber.
Poor charging may occur. On the other hand, when the core metal is coated with polyurethane rubber, the softener impregnated in the rubber-based material exudes, and when the photosensitive member is used as the charged member, the charging member contacts the photosensitive member when the photosensitive member stops at the contact portion. There is a problem that the image is fixed or the image blur occurs in the area. Also, when the softening agent in the rubber material of the charging member exudes and adheres to the surface of the photoreceptor, the resistance of the photoreceptor decreases, causing image deletion, and in severe cases, becomes unusable or remains on the surface of the photoreceptor. In some cases, the toner adheres to the surface of the charging member, causing a filming phenomenon. When a large amount of toner adheres to the surface of the charging member, the surface of the charging member is insulated, the charging ability of the charging member is lost, the charging of the surface of the photoreceptor becomes nonuniform, and the image is adversely affected.

On the other hand, when the developing process using the non-magnetic color toner is combined, various problems occur in addition.

In many cases, the toner does not contain a magnetic substance and does not contain a conductive substance such as carbon black from the viewpoint of color saturation. For this reason, there is no portion where the charge leaks, especially under low temperature and low humidity, and the charge tends to be excessively large as compared with the normal toner. In particular, this tendency is remarkable for negatively charged color toners. This is largely due to hydrophobic silica used as a flow improver.

In recent years, there has been a strong demand for higher image quality of copying machine images. On the other hand, the toner particle size is reduced to achieve high image quality. However, even if the toner particle size is reduced, the surface area of the toner increases, so that the charge amount increases.
It tends to be too large.

As described above, when the charging is excessive, it is difficult to transfer the toner from the photoconductor, and the amount of the residual toner on the photoconductor increases. Further, since the toner is strongly charged and adhered to the photoreceptor, defective cleaning is likely to occur. The toner that cannot be removed in these cleaning steps adheres to the charging member, causing a reduction in charging ability and filming of the photoconductor.

Also, if the particle size is small, there are many contact points between toners,
The fluidity of the toner deteriorates. Therefore, aggregation of toner occurs in the cleaning process, and cleaning failure occurs.

In order to prevent excessive charging, addition of conductive powder, addition of a low-charging substance, addition of a reverse polarity substance, and the like have been performed, but each has a disadvantage.

First, when the conductive powder is added, the amount of charge at a high temperature is remarkably reduced, which causes image density unevenness and fogging. Further, since the conductive powder is generally colored, it adversely affects the color of the color toner.

Further, addition of a low-charge material (for example, see JP-A-56-9254)
No. 5, JP-A-60-217368), in order to obtain a sufficient fluidity-imparting effect, a large amount of addition is required, and the charge amount is lowered too much, or In many cases, the effect of imparting properties cannot be obtained.

In addition, when the opposite polarity substance is added, if coarse particles are contained in the opposite polarity substance, the toner aggregates around the center, and a toner mass of the opposite polarity may be generated. This toner mass is
It is developed in the non-image area, and deteriorates the image quality. Therefore, a step of removing coarse particles or toner lumps is required.

[Problems to be Solved by the Invention] The present invention has been made in view of the above points, and can sufficiently maintain contact between a charging member and a member to be charged, and prevent sticking between the charging member and the member to be charged. Further, the present invention is used in an image forming method having a charging step for preventing a plasticizer contained in the conductive rubber of the charging member from adhering to the member to be charged, so that a high-resolution and high-definition image can be obtained, and a developing, transferring and cleaning step. It is an object of the present invention to provide a toner which hardly remains on the member to be charged after passing through, and as a result, does not adhere to the surface of the charging member or the surface of the member to be charged.

Means and Action for Solving the Problems The present invention is a charging step of charging by bringing a charging member to which a voltage is applied from the outside into contact with a member to be charged, and includes a conductive rubber layer and a conductive rubber. A charging step of contacting a charging member having a surface layer of a release coating on at least a portion of the layer which is in contact with the member to be charged and applying a voltage from outside to charge the member; A toner used in an image forming method having a phenomenon step in which a charged body is performed using a toner; a transfer step; and a cleaning step, wherein the toner has non-magnetic colorant-containing resin particles and a negative charge property having a fluidity improver. A non-magnetic color toner,
The negatively chargeable nonmagnetic color toner has a volume average particle diameter of 6
~ 10μm, and as a fluidity improver,
Absolute value of the triboelectric charge amount with the carrier is 10 μc / g or less and the specific surface area by the BET method is 30 to 200 m ² / g, and the absolute value of the triboelectric charge amount with the carrier is 50 μc / g.
g or more and a specific surface area by a BET method of 80 to 300 m ² / g, and 0.3 to ² % by weight based on the colorant-containing resin particles. The present invention relates to a negatively chargeable nonmagnetic color toner.

The present inventors provide a charging step in which a charging member to which a voltage is applied from the outside is brought into contact with a member to be charged to perform charging, wherein the charging member is a conductive rubber layer and the conductive rubber layer is outside the conductive rubber layer. In addition, in adopting a charging step in which a charging member having a release coating at least in a portion in contact with the member to be charged is brought into contact with the member to be charged and an external voltage is applied to perform charging, a negatively chargeable non-charging member is used. Magnetic color toner has high resolution,
After examining what is needed to enable high-definition and high-quality images and not to have an excessive charge amount even under low humidity, and to have sufficient fluidity, a specific fluidity improver was added to the toner. It has been found that by adding and further defining the particle size distribution of the toner, it is possible to provide a toner meeting the above-mentioned object.

Hereinafter, the negatively chargeable non-magnetic color toner of the present invention will be described.

In the present invention, as a flow improver, the frictional charge between the carrier and the hydrophilic inorganic oxide having a specific surface area of 30 to 200 m ² / g according to the BET method with an absolute value of a triboelectric charge amount of 10 μc / g or less with the carrier. A hydrophobic inorganic oxide having an absolute value of the charge amount of 50 μc / g or more and a specific surface area of 80 to 300 m ² / g by the BET method is used in an amount of 0.3 to ² % by weight based on the colorant-containing resin particles.

As in the present invention, even if the chargeability as a binder resin is stabilized, the use of a silica fine powder or the like generally used as a flowability improver alone improves the flowability, but the chargeability is improved. As characteristics, charging tends to be excessive particularly under low humidity, and as a result, adhesion of the toner to the photoreceptor is strengthened, and transfer efficiency is deteriorated and cleaning failure occurs.
This tendency becomes more remarkable as the particle size of the toner is reduced and the amount of the fluidity improver used is increased.

However, by incorporating at least one fluidity improver having a weak chargeability as in the present invention as a fluidity improver, it was possible to achieve both chargeability and fluidity.

Examples of the fluidity improver include the following, but are not necessarily limited thereto. For example, Al ₂ O ₃ ,
Metal oxides such as TiO ₂ , GeO ₂ , ZrO ₂ , Sc ₂ O ₃ , HfO ₂ , SiC, Ti
There are carbides such as C and W ₂ C, and nitrides such as Si ₃ N ₄ and Ge ₃ N ₄ ,
Among them, Al ₂ O ₃ , TiO ₂ , Sc ₂ O ₃ , ZrO ₂ , GeO ₂ , HfO ₂ are preferable because they are colorless or white and used for color toner without adversely affecting color. It is. Also especially Al
₂ O ₃ , TiO ₂ , and ZrO ₂ are more preferable because they can be easily produced with a suitable particle size by a gas phase method. Further, a hydrophobic treatment may be performed. The finer the particle size of the particles to be added, the better.In the present invention, the specific surface area measured by the BET method is 30 m.
^A flow improver in the range of ² / g to 200 m2 / g is used. More preferably, the particle size is 50 m ² / g or more, and the smaller the particle size, the better the flow characteristics of the toner.

In particular, as the above-mentioned hydrophobic inorganic oxide, it is more preferable to use a treated silica fine powder obtained by subjecting a silica fine powder produced by gas phase oxidation of a silicon halide compound to a hydrophobic treatment. It is particularly preferable that the treated silica fine powder is obtained by treating the silica fine powder such that the degree of hydrophobicity measured by a methanol titration test shows a value in the range of 30 to 80.

Hydrophobization is applied by reacting with silica fine powder or chemically treating it with an organic silicon compound that physically adsorbs.

As a preferred method, silica fine powder produced by vapor phase oxidation of a silicon halide is treated with an organosilicon compound.

Examples of such organosilicon compounds are hexamethyldisilazane, trimethylsilane, trimethylchlorosilane,
Trimethylethoxysilane, dimethyldichlorosilane,
Methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α
-Chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane,
Triorganosilyl mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane,
Dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 2 to 12 siloxane units per molecule with terminal positions For example, dimethylpolysiloxane containing a hydroxyl group bonded to one Si unit may be used for each unit. These are used in one kind or in a mixture of two or more kinds.

Commercial products include Taranox-500 (Talco),
Aerosil R-972 (Nippon Aerosil) and the like. The addition amount is 0.3 to 2% by weight based on the resin particles.

Although this addition amount is related to the particle size distribution of the resin particles described below, if it is less than 0.3% by weight, it is difficult to achieve appropriate fluidity, and if it exceeds 2% by weight, adverse effects such as toner scattering and fogging are likely to occur.

Additives may be added to the toner of the present invention as needed as long as the toner characteristics are not impaired. Examples of such additives include Teflon, zinc stearate, a lubricant such as polyvinylidene fluoride, or Fixing aid (for example, low molecular weight polyethylene, low molecular weight polypropylene, etc.)
Etc.

In the production of the toner of the present invention, the components are thoroughly kneaded by a hot kneader such as a hot roll, a kneader, an extruder, and then mechanically pulverized and classified. Or a method of obtaining a toner by dispersing such materials and spray-drying, or by mixing a predetermined material with a monomer to constitute a binder resin and then polymerizing this emulsion suspension to obtain a toner. Each method such as a toner manufacturing method can be applied.

Next, a preferred particle size distribution of the negatively chargeable nonmagnetic color toner of the present invention will be described. In the following description regarding the particle size distribution of the negatively chargeable non-magnetic color toner, the “colorant-containing resin particles” will be referred to as “toner particles”.

In the present invention, the negatively-chargeable nonmagnetic color toner has a volume average particle diameter in the range of 6 to 10 μm, contains 15 to 40% by number of toner particles having a particle diameter of 5 μm or less, and has a
0.1 to 5.0% by volume of toner particles having a particle size of 16.0 μm, 1.0% by volume or less of toner particles having a particle size of 16 μm or more, and toner particles having a particle size of 6.35 to 10.1 μm are represented by the following formula: The effect is more pronounced when having a particle size distribution that satisfies

The toner having the above particle size distribution can faithfully reproduce a latent image formed on the photoreceptor, and is excellent in reproducing a minute dot latent image such as a halftone dot and a digital image. Image with excellent gradation and resolution. Furthermore, high image quality can be maintained even when copying or printing out is continued, and even in the case of high density images, good development can be performed with less toner consumption than conventional non-magnetic toner. It also has advantages in terms of performance and miniaturization of the copier or printer body.

The reason why such an effect is obtained in the toner of the present invention is not necessarily clear, but is presumed as follows.

Conventionally, toner particles having a particle size of 5 μm or less
It is considered difficult to control the charge amount, impair the fluidity of the toner, and actively reduce it as a component that scatters the toner and contaminates the machine, as well as a component that causes image fogging. Had been.

However, according to the study of the present inventors, it has been found that toner particles of about 5 μm are essential components for forming high quality image.

For example, using a two-component developer having a non-magnetic toner having a particle size distribution ranging from 0.5 μm to 30 μm and a carrier, the surface potential on the photosensitive member is changed, and a large development potential contrast is obtained in which a large number of toner particles are easily developed. From halftone to halftones, and then to latent images of small dots where only a few toner particles are developed. Was collected and the toner particle size distribution was measured.
It was found that there were many toner particles having a particle size of m or less, especially about 5 μm on the latent image of fine dots. That is,
When toner particles having a particle size of about 5 μm are smoothly supplied to the development of the latent image on the photoreceptor, the latent image is faithful to the latent image, and an image with excellent reproducibility can be obtained without protruding from the latent image. is there.

Further, the toner particles of 12.7 μm to 16.0 μm are related to the necessity of the existence of toner particles having a particle size of about 5 μm.
Non-magnetic toner particles having a particle size of m or less certainly have the ability to faithfully reproduce the latent image of fine dots, but themselves have considerably high cohesiveness, which may impair the fluidity of the toner.

The present inventors have proposed the above-mentioned 2 for the purpose of improving fluidity.
By adding more than one kind of inorganic oxide, further improvement in fluidity was attempted.However, only means for adding an inorganic additive are not enough to satisfy all conditions such as image density, toner scattering, and fog. Was confirmed to be narrow. Therefore, the present inventors further studied the particle size distribution of the toner, and found that the toner particles having a particle size of 5 μm or less
It has been found that fluidity is further improved and high image quality can be achieved by containing 0.1% to 5.0% by volume of toner particles of 12.7 to 16.0 μm after containing 40% by number. That is,
It is considered that the toner particles in the range of 12.7 to 16.0 μm have a moderately controlled fluidity with respect to the toner particles of 5 μm or less, and as a result, high-resolution images are obtained even when copying or printing is continued. This provides a sharp image with excellent characteristics and gradation.

Further, for the toner particles of 0.35 to 10.1 μm, between the volume% (V), the number% (N) and the volume average particle size (v), It is further desirable that the color toner of the present invention satisfies the following relationship.

The present inventors have studied the state of the particle size distribution and the development characteristics and found that there is a state of existence of the particle size distribution most suitable for achieving the object as shown by the above formula.

In other words, when the particle size distribution is adjusted by general air classification, the above value is large, which means that toner particles of about 5 μm that faithfully reproduce a minute dot latent image increase, and that the above value is small. It is understood that this indicates that toner particles of about 5 μm are reduced.

Therefore, when v is in the range of 6 to 10 μm and the above relational expression is further satisfied, good toner fluidity and faithful latent image reproducibility are achieved.

For toner particles having a particle size of 16 μm or more, 1.
It is preferable that the content is 0 volume% or less and the amount is as small as possible.

The configuration of the present invention will be described in more detail. 5 μm
The number of toner particles having the following particle size is preferably 15 to 40% by number of the total number of particles, and more preferably 20 to 35% by number.
When the number of toner particles having a particle size of 5 μm or less is 15% by number or less, the amount of non-magnetic toner particles effective for high image quality is small.
As the toner is used by continuing to copy or print out, the effective toner particle component decreases,
The balance of the particle size distribution of the toner deteriorates, and the image quality gradually decreases. On the other hand, if the content is more than 40% by number, toner particles are likely to aggregate with each other, resulting in a toner mass larger than the original particle size, resulting in rough image quality, reduced resolution, or an edge portion of a latent image. The density difference between the image and the inside becomes large, and the image tends to be slightly hollow.

Further, the particle size in the range of 12.7 to 16.0 μm is preferably 0.1 to 5.0% by volume, and more preferably 0.2 to 3.0% by volume. Five.
If the content is more than 0% by volume, the image quality is deteriorated, and the development is performed more than necessary, that is, the toner is excessively applied, which causes an increase in toner consumption. On the other hand, when the content is less than 0.1% by volume, the image density is reduced due to the decrease in fluidity.

Further, the content of toner particles having a particle diameter of 16 μm or more is preferably 1.0% by volume or less, more preferably 0.6% by volume or less. Due to the existence of coarse toner particles of 16 μm or more protruding on the thin layer surface of the toner particles developed on the photoconductor, the delicate adhesion between the photoconductor and the transfer paper through the toner layer is irregular. As a matter of fact, it is likely to cause a change in the transfer condition and to cause a transfer failure image.

Further, the volume average diameter of the toner is from 6 to 10 μm, preferably from 7 to 9 μm (this point also applies to the colorant-containing fine particles), and this value cannot be considered separately from the above-mentioned respective constituent elements. It is. If the volume average particle diameter is less than 6 μm, in applications having a high image area ratio such as a graphic image, a problem that the amount of toner deposited on the transfer paper is small and the image density is low tends to occur. This is considered to be due to the same reason as described above for lowering the density inside the edge portion of the latent image. Volume average particle size 10μm
When the number of copies exceeds 1, the resolution is not good, and at the beginning of copying, image quality is liable to be reduced if the use is continued at best.

As described above, by using this toner, a high-resolution, high-definition, high-quality copy image can be obtained, and the charge amount can be prevented from becoming excessive even under low quality. As a result, the transfer efficiency is increased, the residual toner on the photoreceptor is reduced, and the adhesive force between the residual toner and the photoreceptor is reduced, so that cleaning failure and leakage from the cleaner can be prevented. In addition, since sufficient fluidity is obtained, aggregation in the cleaner is small, and poor cleaning due to toner aggregation can be prevented. Further, since a sufficient charge amount can be ensured even under low humidity, scattering and fogging do not occur.

As the binder substance used for the colorant-containing resin particles, various material resins conventionally known as toner binder resins for electrophotography are used.

For example, styrene-based copolymers such as polystyrene, styrene-butadiene copolymer, styrene-acrylic copolymer, and ethylene-based copolymers such as polyethylene, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer Phenolic resin, epoxy resin, acrylic phthalate resin, polyamide resin, polyester resin, maleic acid resin and the like. Further, the production method and the like of any resin are not limited.

Among these resins, polyester resins are suitable for the present invention. Polyester resins have excellent fixing properties and are suitable for color toners, but have a strong negative charging ability and tend to be excessively charged. Therefore, when the polyester resin is used in the present invention, adverse effects are improved, and an excellent toner is obtained.

In particular, (Wherein R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2
~ 10. A) a carboxylic acid component comprising a divalent or higher carboxylic acid or an acid anhydride thereof or a lower alkyl ester thereof (for example, fumaric acid, maleic acid, maleic anhydride, phthalic acid) Acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) are more preferred because they have sharp melting properties.

As the coloring agent, known dyes and pigments, for example, phthalocyanine blue, induslen blue, peacock blue, permanent red, lake red, rhodamine lake, Hansa yellow, permanent yellow, benzidine yellow and the like can be used widely. The content thereof is 12 parts by weight or less, preferably 0.5 to 9 parts by weight, based on 100 parts by weight of the binder resin so as to be sensitive to the light transmittance of the OHP film.

The toner according to the present invention may contain a charge control agent for stabilizing the charge characteristics. At that time, a colorless or light-colored charge control agent that does not affect the color tone of the toner is preferable.
In the present invention, when the present invention is used as a negatively chargeable color toner, the present invention becomes more effective. In this case, as a negative charge controlling agent, for example, a metal complex of an alkyl-substituted salicylic acid (for example, a chromium complex of di-tert-butyl salicylic acid or Organometallic complexes such as zinc complex).
When compounding the negative charge control agent with the toner, the binder resin 100
It is preferable to add 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight based on parts by weight.

As the carrier used by mixing with the toner of the present invention,
An electrically insulating resin is used as a coating resin for the carrier core material, and is appropriately selected depending on a toner material and a carrier core material. In the present invention, at least one monomer selected from at least an acrylic acid (or an ester thereof) monomer and a methacrylic acid (or an ester thereof) monomer in order to improve the adhesion to the carrier core material surface. Must be contained. In particular, when polyester resin particles having a high negative chargeability are used as a toner material, it is preferable to further form a copolymer with a styrene monomer for the purpose of stabilizing charging, and the copolymerization weight ratio of the styrene monomer is preferable. To 5
Preferably it is 70% by weight.

The average molecular weight of the copolymer, the number average molecular weight is 10,000 in consideration of the uniformity of the coating of the carrier core material surface, the coating strength.
335,000, preferably 17,000-24,000, and a weight average molecular weight of 25,000-100,000, preferably 49,000-55,000.

As the monomer for the coating resin of the carrier core material that can be used in the present invention, examples of the styrene-based monomer include a styrene monomer, a chlorostyrene monomer, an α-methylstyrene monomer, and a styrene-chlorostyrene monomer. For example, acrylate monomers (methyl acrylate monomer, ethyl acrylate monomer, butyl acrylate monomer,
Octyl acrylate monomer, phenyl acrylate monomer, 2-ethylhexyl acrylate monomer) and the like, and methacrylate ester monomers (methyl methacrylate monomer, ethyl methacrylate monomer, butyl methacrylate monomer, phenyl methacrylate monomer).

As the magnetic particles used in the present invention, for example, surface oxidized or unoxidized iron, nickel, copper, zinc, cobalt,
Metals such as manganese, chromium, rare earths, and alloys or oxides thereof can be used. In addition, there is no particular limitation on the manufacturing method.

Next, the contact charging step applicable to the present invention will be specifically described.

The charging device in the present invention is, for example, as shown in FIG. Reference numeral 13 denotes a photosensitive drum which is a member to be charged, and rotates in the direction of the arrow. Reference numeral 14 denotes a charging roller which is a charging member brought into contact with the photosensitive drum 13 at a predetermined pressure.
E is a power supply unit that applies a voltage to the charging roller 14 and supplies a predetermined voltage to the metal core 14 a of the charging roller 14. In FIG. 1, E indicates a DC voltage, but may be obtained by superimposing an AC voltage on a DC voltage.

In the present invention, a conductive rubber layer 14b is provided on a metal cored bar 14a, and a surface layer 14c which is a release coating is provided on a peripheral surface thereof. The reason is that a softening agent from the conductive rubber does not exude to a portion which comes into contact with the photoreceptor which is a charged member by providing a release coating outside the conductive rubber layer. Therefore, when the softener adheres to the photoreceptor, image flow due to lowering of the resistance of the photoreceptor and a decrease in charging ability due to filming of residual toner on the photoreceptor can be prevented, and a decrease in charging efficiency can be suppressed.

Furthermore, by using a conductive rubber layer for the charging roller, sufficient contact between the charging roller and the photoconductor can be maintained, and no charging failure occurs.

In the present invention, a charging device as shown in FIG. 2 can be used. Here, a blade-shaped contact charging member acts, but the metal supporting member 14 ′ to which a voltage is also supplied.
By supporting the conductive rubber 14'b with a and providing a surface layer which is a release coating on the contact portion with the photosensitive drum 13, the same operation and effect as in the above example can be obtained.

In the above-described example, a roller-shaped or blade-shaped charging member is used. However, the present invention is not limited to this, and the present invention can be applied to other shapes.

Further, in the above-described example, the charging member is formed of the conductive rubber layer and the release coating, but the invention is not limited to this, and a high resistance is provided between the conductive rubber layer and the surface of the release coating to prevent leakage to the photoconductor. It is preferable to form a layer, for example, a hydrin rubber layer having small environmental fluctuation.

Nylon resins PVDF (polyvinylidene fluoride) and PVDC (polyvinylidene chloride) can be used for the release coating. Further, as the photoconductor, OPC, amorphous silicon, selenium, ZnO, or the like can be used. In particular, when amorphous silicon is used for the photoconductor, compared to the case where other materials are used, even if the softening agent of the conductive rubber layer adheres to the photoconductor even to a small extent, the image flow becomes severe, so The effect of the insulating coating is great. Further, the charging device of the present invention can be used for transfer.

Hereinafter, each of the measuring methods (1) and (2) relating to the characteristic value of the toner used in the present invention will be described.

(1) Particle size distribution measurement: Coulter counter TA-II type (manufactured by Coulter) was used as a measuring device, and an interface (manufactured by Nikkaki) for outputting a number average distribution and a volume average distribution and a CX-1 personal computer (manufactured by Canon) ) And the electrolyte is 1
Prepare a 1% aqueous NaCl solution using graded sodium chloride.

As a measurement method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the aqueous electrolytic solution, and 0.5 to 50 mg of a measurement sample is further added.

The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes by an ultrasonic disperser, and a 100 μm aperture was used as the aperture by the Coulter Counter TA-II.
The volume average distribution and the number average distribution are obtained by measuring the particle size distribution of the particles of up to 40 μm.

From the obtained volume average distribution and number average distribution, values of volume average particle diameter, number average distribution of 5.04 μm or less, and volume average distribution of 16.0 μm or more are obtained.

(2) Measurement of Friction Charge Amount FIG. 3 is an explanatory view of a friction charge amount measuring device. First, a mixture of particles to be measured and a carrier is prepared. The mixing ratio is 2 parts by weight for 98 parts by weight of the magnetic particles in the case of the fluidity imparting agent.

The particles to be measured and the magnetic particles are placed in a measurement environment, left for 12 hours or more, then put into a polyethylene bottle, and mixed and stirred sufficiently.

Next, a mixture of particles and magnetic particles whose triboelectric charge amount is to be measured is placed in a metal measuring container 2 having a conductive screen 3 of 500 mesh (which can be appropriately changed to a size that does not allow magnetic particles to pass) at the bottom. A metal lid 4 is provided. The weight of the entire measurement container 2 at this time is defined as a scale W ₁ (g). Next, the suction device 1 (at least a portion in contact with the measurement container 2 is an insulator)
In the above, the pressure of the vacuum gauge 5 is set to 250 mmAq by adjusting the air volume control valve 6 by suctioning through the suction port 7. In this state, suction is performed sufficiently (about 2 minutes) to remove the toner by suction. The potential of the electrometer 9 at this time is set to V (volt). Here, reference numeral 8 denotes a capacitor, whose capacity is C (μF). The weight of the whole measurement container after suction is defined as a scale W ₂ (g). This triboelectric charge amount T (μC / g) is calculated as in the following equation.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples. A charging device and a toner were prepared.

Charging device: The configuration shown in FIG. 1, and the outer diameter of the charging roller 14 is 12 mmφ
The conductive rubber layer 14b is EPDM, and the surface layer 14c is 10 μm thick.
m of nylon resin was used. Hardness of charging roller 4 5
4.5 ゜ (ASKER-C).

toner: After sufficient premixing with a Henschel mixer,
The mixture was melt-kneaded at least twice with a three-roll mill, cooled, and coarsely ground to a particle size of about 1 to 2 mm using a hammer mill. Next, it was pulverized by a pulverizer using an air jet method. Further, the obtained finely pulverized product was classified to obtain colorant-containing resin particles.

Alumina fine powder having a specific surface area by BET method of 100 m ² / g and a triboelectric charge of 1.7 μc / g in 100 parts of the colorant-containing resin particles.
0.3 parts and the specific surface area by the BET method is 250 m ² / g, and the triboelectric charge amount −55 μ that has been hydrophobized with hexamethyldisilazane
A cyan toner was prepared by externally adding 0.5 parts of c / g silica fine powder.

 The particle size distribution of this toner was as follows.

Toner: 100m ² / g specific surface area by BET method as a fluidity improver
The toner was prepared in the same manner as the toner, except that only 0.8 parts of silica fine powder having a triboelectric charge of -26 μc / g subjected to hydrophobic treatment with dimethyldichlorosilane was used.

toner: , Using a volume average particle size of 7.2 μm
Red powder was obtained. BE as a fluidity improver
0.4 parts of fine alumina powder having a specific surface area of 95 m ² / g and a triboelectric charge of 2.1 μc / g by the T method, and a specific surface area of 150 m ² / g by the BET method
g of a silica fine powder having a triboelectric charge of -58 μc / g, which had been subjected to hydrophobic treatment with dimethyldichlorosilane, was externally added to obtain a toner.

Toner: 40m ² / g specific surface area by BET method as a fluidity improver
And a triboelectric fine powder having a triboelectric charge of 2.0 μc / g hydrophobized with octyltrimethoxysilane and a triboelectric charge with a specific surface area of 250 m ² / g by BET method and hydrophobized with hexamethyldisilazane. A toner was prepared in the same manner as the toner, except that it was used in combination with a silica fine powder having an amount of -61 μc / g.

Toner: As a fluidity improver, specific surface area by BET method is 150 m ² / g
The toner was prepared in the same manner as the toner, except that only 0.7 part of a silica fine powder having a triboelectric charge of −31 μc / g, which had been hydrophobized with dimethyldichlorosilane, was used.

Toner: As a fluidity improver, the specific surface area by the BET method is 50 m ² / g
0.4 parts of titanium oxide fine powder (T-805: manufactured by Nippon Aerosil Co., Ltd.) having a triboelectric charge of -12.5 μc / g, and a specific surface area of 250 m ² / g by a BET method. The toner was prepared in the same manner as the toner except that 0.5 part of silica fine powder having a triboelectric charge of -55 μc / g subjected to hydrophobic treatment was used.

To these parts of toner, 94 parts of Cu-Zn-Fe-based ferrite particles whose surface was coated with a styrene-acrylic acid-ethyl methacrylate 2-ethylhexyl copolymer were mixed to prepare a developer.

Example 1 A charging device of a commercially available copying machine (CLC-500, manufactured by Canon Inc.) was modified so as to have the same configuration as that of the first embodiment, and images were output. Adjust the applied voltage so that the contact pressure on the photoreceptor is 50g / cm and the development contrast is 270V at 23 ° C / 65%, 330V at 20 ° C / 10%, 250V at 30 ° C / 80%. And a developer using a toner was charged.

As a result, in each environment, the image density was stable at 1.40 to 1.55 and was clear without fog. Further, the charging roller after image formation was hardly stained, no filming occurred on the photoreceptor, and no reduction in charging efficiency was observed.

Example 2 A printing durability test was performed using the same copying machine as in Example 1 using a developer using a toner. As a result, the decrease in charging efficiency was small, the contamination of the charging roller, and the filming of the photoconductor were also reduced. Did not occur.

Example 3 A printing durability test was performed using a developer using a toner and the same copying machine as in Example 1, and a high-quality image having a sufficient image density was obtained. Also, no contamination of the charging roller and no filming of the photosensitive member occurred.

Comparative Example 1 A printing durability test was performed using the same copying machine as in Example 1 using a developer using a toner. After 1500 sheets of durability, the charging roller was dirty, and filming also occurred on the photoreceptor. Also, the image density decreased as printing was performed.

Comparative Example 2 A printing durability test was performed using the same copying machine as in Example 1 using a developer using a toner. After 1,500 sheets of durability, the charging roller was stained, and the image density was reduced as printing was performed.

Experimental Example 1 A printing durability test was performed using the same copying machine as in Example 1 using a developer containing a toner. At 20 ° C./10%, the charging roller was stained during printing, and the image density was reduced as compared with Example 1 as printing was performed.

[Effects of the Invention] According to the present invention, the contact between the charging member and the member to be charged can be sufficiently maintained, the sticking between the charging member and the member to be charged can be prevented, and the contamination of the charging member and the member to be charged can be prevented. In addition to preventing filming, it has made it possible to obtain high-resolution, high-definition images.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an outline of a charging roller of the present invention, FIG. 2 is an explanatory view showing an outline of a blade according to another embodiment of the present invention, and FIG. FIG. 13 Photoconductor drum 14, 14 'Charging member E Power

Claims (2)

(57) [Claims] An electrification step in which an electrification member to which a voltage is applied from the outside is brought into contact with an object to be electrified to conduct electrification. A charging step in which a charging member having a surface layer of a release coating on a portion in contact with the charged body is charged to apply a voltage from outside by contacting the charged body; a developing step performed by using the toner with the charged body A toner for use in an image forming method having a transfer step; and a cleaning step; the toner is a negatively chargeable nonmagnetic color toner having nonmagnetic colorant-containing resin particles and a fluidity improver;
The negatively chargeable nonmagnetic color toner has a volume average particle diameter of 6 to
A hydrophilic inorganic oxide having a range of 10 μm, and as a fluidity improver, an absolute value of a triboelectric charge amount with a carrier of 10 μc / g or less and a specific surface area by a BET method of 30 to 200 m ² / g. And the absolute value of the triboelectric charge amount with the carrier is 50μc / g
A negatively-charged hydrophobic inorganic oxide having a specific surface area of 80 to 300 m ² / g as determined by the BET method is added to the colorant-containing resin particles in an amount of 0.3 to 2% by weight. Negatively chargeable non-magnetic color toner. 2. The negatively chargeable nonmagnetic color toner has a volume average diameter in the range of 6 to 10 μm, contains 15 to 40% by number of colorant-containing resin particles having a particle diameter of 5 μm or less, and contains 12.7%.
0.1 to 16.0 μm colorant-containing resin particles having a particle size of 0.1 to
It contains 5.0% by volume and contains 1.0% by volume or less of colorant-containing resin particles having a particle size of 16 μm or more.
The colorant-containing resin particles having a particle size of μm are represented by the following formula: 2. The negatively chargeable non-magnetic color toner according to claim 1, wherein the following formula is satisfied.