JP2646279B2 - Image forming method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image forming method in electrophotography. More specifically, the present invention relates to an image forming method having 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.

[Prior Art] Conventionally, a corona discharger is known as a charging means in an electrophotographic apparatus or the like, but the corona discharger has problems such as a high voltage application and a large amount of ozone generated. doing.

Therefore, recently, the use of contact charging means without using a corona discharger has been studied. More 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 charged member 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, in Japanese Patent Publication No. 50-13661, a low voltage can be applied when charging a photosensitive member by using a roller having a core covered with a dielectric material made of nylon or polyurethane rubber.

However, in the above conventional example, when the core metal is coated with nylon, there is no elasticity of rubber or the like, so that sufficient contact with the member to be charged cannot be maintained, and poor charging occurs.
On the other hand, when the core metal is coated with polyurethane rubber, the softening agent impregnated in the rubber-based material exudes, and when the photoreceptor is used as the charged body, the charging member sticks to the photoreceptor when the photoreceptor stops at the contact portion. I do. Alternatively, there has been a problem that the area causes image blur. Also, when the softener in the rubber material of the charging member seeps out and adheres to the surface of the photoreceptor,
When the resistance of the photoreceptor is reduced and image flow occurs, the use of the photoreceptor becomes unusable at times. In other cases, toner remaining on the surface of the photoreceptor 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 affected.

On the other hand, when a developing process using a non-magnetic color toner having a negative charge 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 negatively charged hydrophobic silica used as a fluidity imparting agent.

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. Also, because it is strongly charged and adheres to the photoconductor,
Cleaning failure is likely to occur.

The toner that cannot be completely removed in these cleaning steps adheres to the charging member, causing a reduction in charging ability and filming of the photoconductor.

On the other hand, if the particle diameter is small, the toner has many contact points with each other, so that the fluidity of the toner deteriorates. Therefore, aggregation of the toner occurs in the cleaning step, 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 under high humidity is remarkably reduced, and image density unevenness and fog are caused. 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, the charge amount is too low, or sufficient fluidity 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 plasticizer contained in the conductive rubber of the charging member is adhered to the member to be charged, thereby preventing the toner from sticking to the surface of the charging member, thereby preventing charging failure and uneven charging due to filming of the toner on the member to be charged. A charging step that does not occur, a high-resolution, high-definition image can be obtained, and after the development, transfer, and cleaning steps, very little remains on the member to be charged. It is another object of the present invention to provide an image forming method including a developing step, a transferring step and a cleaning step using a toner which does not cause sticking.

[Means and Actions for Solving the Problems] The present invention provides a charging step in which a charging member to which an external voltage is applied is brought into contact with a member to be charged to perform charging, a developing step in which the member to be charged is developed with a color toner, In the image forming method having a transfer step and a cleaning step, the charging member is provided with a conductive rubber layer, and a releasability provided at least at a portion outside the conductive rubber layer and in contact with the member to be charged. A surface layer of a coating film, wherein the toner is an insulating negatively-chargeable non-magnetic color toner having at least a non-magnetic colorant-containing polyester-based resin particle and a fluidity improver, The colorant-containing polyester-based resin particles have a volume average diameter in the range of 4 to 10 μm, the components are mainly composed of a diol component and a dicarboxylic acid component, and at least a part of —COOH contains N. It contains a polyester resin substituted by a functional group, and at least one of the fluidity improvers, when frictionally charged with a carrier, has an absolute value of the charge amount of 10 μc / g or less. The present invention relates to an image forming method.

The present inventors have conducted intensive studies on the charging stability and the prevention of charge-up of the negatively chargeable non-magnetic color toner for electrostatic charge development. As a result, at least a part of the residual -COOH of the polyester was converted to N, such as amine, azine or pyridinium salt. It has been found that by substituting with a functional group containing, charging stability can be achieved over a long period of time in a wide range of environments.

That is, by replacing at least a part of -COOH with a functional group containing N, the toner becomes less likely to absorb moisture under high humidity, and at the same time, the effect of accelerating the rise of charging rather than rubbing with the functional group containing N is produced. . As a result, a decrease in charging under high humidity can be suppressed to some extent.

In general, the negative charge of a polyester resin tends to be excessive under low humidity. However, by treating with a modifier containing N, the positive charge ability of the modifier is appropriately reduced. The charge is neutralized, which is very effective in suppressing the charge-up, and at the same time, the cleaning property is improved.

Furthermore, in order to make the present invention more effective, the sum of the acid value and the hydroxyl value is 3 to 20 mgKOH / g, preferably 4 to 1 mgKOH / g.
When the amount is 5 mgKOH / g, a toner having sufficient environmental stability of charging and a color toner having good dispersibility of a colorant are achieved, which is desirable.

Replacing at least a part of the -COOH with a functional group containing N is disclosed in JP-A-61-14644 and the like, but these are intended only for a positively chargeable toner. This is a completely different invention from the negatively chargeable color toner used in the invention.

JP-A-62-195676, JP-A-62-195678, JP-A-62-195676
According to JP-A-195680, JP-A-62-195681 and JP-A-62-195682, it is stated that if the amount of terminal groups, especially the amount of carboxyl groups, is excessively reduced, the charge amount of the polyester resin is reduced. The inventor has found that the amount of charge takes a sufficient value by containing a suitable charge control agent which is preferable in forming a toner. Further, according to the above-mentioned publication, it is described that the ratio between the hydroxyl value and the acid value is adjusted to 1.2 or more for the purpose of improving the fluidity and lowering the minimum fixing temperature, but the present inventor uses the additives described below. As a result, it has been found that a stable fixing performance can be obtained because a proper fluidity and a proper filling state of the toner layer on the transfer material can be achieved.

In the present invention, in order to replace at least a part of -COOH with a functional group containing N, a functional group NH reactive with -COOH is used.
_A modifier having ₂ , NHR, NR ₂ or the like may be treated after the polyester polymerization reaction.

As the diol component of the polyester resin used in the present invention, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3
-Butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, pentaerythritol diallyl ether, trimethylene glycol, 2-ethyl-1,3-hexane A diol, hydrogenated bisphenol A, or a bisphenol derivative represented by the following formula; (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 to 2)
It is 10. ) And the like.

Further, as the dicarboxylic acid component, fumaric acid, maleic acid, citraconic acid, unsaturated dicarboxylic acids such as itaconic acid, or acid anhydrides thereof, succinic acid, adipic acid,
Examples thereof include dicarboxylic acids such as sebacic acid and azelaic acid, and anhydrides thereof, and aromatic dicarboxylic acids such as phthalic acid and terephthalic acid.

As the diol component used in the present invention, 40 to 60 mol
%, Preferably 45 to 5 mol%, as the dicarboxylic acid component
It is desirably 60 to 40 mol%, preferably 55 to 45 mol%.

Examples of the N-containing modifier used in the present invention include diethanolamine, dimethylaminoethanol, triethanolamine, polyalkyleneamine, diethylenetriamine, and triethylenetetramine.

 The method for producing the polyester resin is as follows.

Under an inert gas atmosphere (often in the presence of nitrogen gas)
The reaction is carried out at normal pressure to reduced pressure (0~-760mmH ₂ O). While stirring, the temperature is raised to 60-270 ° C, preferably 80-220 ° C,
Incubate for 30 hours. Water or alcohols produced by the condensation polymerization are continuously discharged out of the system together with the inert gas while supplying the inert gas into the system, so that the condensation polymerization proceeds. For example, an acid and an alcohol are charged into a reaction vessel equipped with a stirrer, a condenser, a thermometer and an inert gas introduction pipe. Next, gas replacement is performed by introducing an inert gas. After the completion of the gas replacement, the inert gas is kept flowing, the reaction temperature is raised to a predetermined temperature, and the condensation polymerization reaction is performed with stirring for 10 to 30 hours. Water or alcohol produced by the condensation polymerization reaction is condensed and recovered by a condenser outside the system. At the end of the reaction, a modifier is added to treat the -COOH group.

After the completion of the reaction, the generated water or the residual modifier in the case where the added modifier is excessive is evaporated under reduced pressure and condensed by a condenser outside the system and collected. Thereafter, the temperature is lowered to room temperature to obtain a polyester resin.

Here, the polyester resin in the present invention preferably has a total of the acid value and the hydroxyl value of 3 to 20 mgKOH / g due to its properties, and if it exceeds 20 mgKOH / g, the number of carboxyl groups or hydroxyl groups increases, and Environmental dependency is increased, and restrictions on usable coloring agents, external additives, and the like are increased.

On the other hand, if it is less than 3 mgKOH / g, the dispersion of the colorant dispersed in the resin tends to be non-uniform, which may cause adverse effects such as toner scattering and fog.

The method for measuring the acid value and the hydroxyl value used in the present invention will be described below.

For the measurement of the acid value, 2 to 10 g of a sample are weighed in a 200 to 300 ml Erlenmeyer flask, and about 50 ml of a mixed solvent of methanol: toluene = 30: 70 is added to dissolve the resin. If the solubility is poor, a small amount of acetone may be added. Using a mixed indicator of 0.1% bromthymol blue and phenol red, titrate with a previously standardized N / 10 potassium hydroxide-alcohol solution, and calculate the acid value from the consumption of the alcohol potassium solution by the following formula (I). Ask.

Acid value = KOH (ml number) × N × 56.1 / sample weight (I) (where N is a factor of N / 10 KOH) The hydroxyl value is measured by heating the sample with an excess acetylating agent such as acetic anhydride. After performing acetylation and measuring the saponification value of the produced acetylated product, the acetylation is calculated according to the following formula (II).

(However, A represents the saponification value after acetylation, and B represents the saponification value before acetylation.) The toner according to the present invention may contain a charge control agent in order to stabilize 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.
Examples of the negative charge control agent at that time include an organic metal complex such as a metal complex of an alkyl-substituted salicylic acid (for example, a chromium complex or a zinc complex of di-tert-butylsalicylic acid). When the negative charge control agent is blended in the toner, 0.1 to 10 parts by weight, preferably 0.5 to 100 parts by weight of the binder resin.
It is better to add up to 8 parts by weight.

When preparing a two-component developer by mixing with the toner according to the present invention, the mixing ratio is as a toner concentration in the developer,
Good results are usually obtained at 2.0 to 10% by weight, preferably 3 to 9% by weight. If the toner concentration is less than 2.0% by weight, the image density is low and it becomes impractical. If the toner concentration exceeds 10% by weight, fog and scattering in the machine are increased, and the useful life of the developer is shortened.

As the colorant used in the present invention, 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 widely used. The content thereof is 12 parts by weight or less, preferably 0.5 to 9 parts by weight with respect to 100 parts by weight of the binder resin so as to be sensitively reflected on the permeability of the OHP film.

It is necessary that the fluidity improver used in the present invention contains at least one of those having an absolute value of a charge amount of 10 μc / g or less when frictionally charged with a carrier.

In the present invention, as a preferable constitution of the fluidity improver, the absolute value of the charge amount when frictionally charged with the carrier is 10
It is preferable to use particles having a weak chargeability of μc / g or less and a negatively chargeable inorganic oxide having an absolute value of a charge amount of 50 μc / g or more when frictionally charged with a carrier. As a more preferred constitution of the fluidity improver, the absolute value of the triboelectric charge amount with the carrier is 10μc / g or less and the specific surface area by the BET method is 30 to 20.
0 m ² / g hydrophilic inorganic oxide, the absolute value of the triboelectric charge amount with the carrier is 50 μc / g or more and the specific surface area by the BET method is 80 to 30
0 m ² / g of the negatively charged hydrophobic inorganic oxide 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 for the characteristics, the charge tends to be excessive particularly under low humidity, and as a result, the cleaning property of the toner is impaired. This tendency becomes more remarkable as the particle size of the toner is reduced and the amount of the fine silica powder is increased.

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

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 fluidity-imparting agent 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 the amount of addition 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 is more than 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 properties of the toner are not impaired. Examples of such additives include Teflon, zinc stearate, and lubricants such as polyvinylidene fluoride. Alternatively, there are fixing aids (eg, low molecular weight polyethylene, low molecular weight polypropylene, 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 color toner of the present invention will be described. In the following description regarding the particle size distribution of the color toner, “non-magnetic colorant-containing polyester resin particles” are referred to as “toner particles”.

In the present invention, the color toner has a volume average particle size of 6
1010 μm, containing 15 to 40% by number of toner particles having a particle size of 5 μm or less, containing 0.1 to 5.0% by volume of toner particles having a particle size of 12.7 to 16.0 μm, and forming particles having a particle size of 16 μm or more. 1.0% by volume or less of toner particles having a diameter,
The toner particles having a particle diameter 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 a photoreceptor, and is excellent in reproducing a minute dot latent image such as a halftone dot and a digital image. An image excellent in gradation and resolution of the part is provided. 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 color toner of the present invention is not necessarily clear, but is presumed as follows.

Conventionally, in a color toner, toner particles having a particle size of 5 μm or less are difficult to control the charge amount, impair the fluidity of the toner, and are components that cause fogging of an image as a component that scatters toner and contaminates a machine. As
It was thought that aggressive reduction was necessary.

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 and a carrier having a particle size distribution ranging from 0.5 μm to 30 μm, the surface potential on the photoreceptor is changed, and a large development potential contrast in which many 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 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 the toner particles having a particle size of about 5 μm are smoothly supplied to the development of the latent image on the photoreceptor, the toner is faithful to the latent image, and an image with excellent reproducibility can be obtained without protruding from the latent image. It is.

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 have found that the state of existence of the particle size distribution most suitable for achieving the object as shown in 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, 1.0
It is preferable that the content be as small as possible by volume.

The configuration of the present invention will be described in more detail. 5μ
The number of toner particles having a particle size of m or less 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, if it is less than 0.1% by volume,
The image density decreases 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 6 to 10 μm, preferably 7 to 9 μm, and this value cannot be considered separately from the above-mentioned respective constituent elements.
When the volume average particle diameter is less than 6 μm, in applications having a high image area ratio such as a graphic image, there is a problem that the amount of applied toner on the transfer paper is small and the image density is low.
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.
If the volume average particle size is 10 μm or more, the resolution is not good, and if the use is continued at the beginning of copying, the image quality is likely to deteriorate.

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 humidity. 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. Further, since sufficient fluidity is obtained, aggregation in the cleaner is small, and cleaning failure due to toner aggregation can be prevented. Further, since a sufficient charge amount can be secured even under high humidity, scattering and fogging do not occur.

Although the particle size distribution of the toner can be measured by various methods, in the present invention, the measurement was performed using a Coulter counter.

That is, as a measuring device, Coulter Counter TA-II
Using an interface (manufactured by Coulter) and an interface (manufactured by Nikkaki) that outputs the number distribution and volume distribution and a CX-1 personal computer (manufactured by Canon), 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 2 to 20 mg of a measurement sample is further added.
The electrolyte solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the Coulter Counter TA-II was used, and a 100-μm aperture was used as an aperture. The particle size distribution was measured and the values according to the invention were determined therefrom.

The color toner of the present invention can be applied to both the one-component development method and the two-component development method.

When the color toner of the present invention is used as a two-component developer, an electrically insulating resin is used as a coating resin on the surface of the carrier, 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 a polyester resin particle having a high negative chargeability is used as a toner material, it is preferable to further form a copolymer with a styrene-based monomer for the purpose of stabilizing charging, and the copolymerization weight ratio of the styrene-based monomer is used. Is preferably 5 to 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.
~ 35,000, preferably 17,000-24,000, weight average molecular weight is 2
It is preferably between 5,000 and 100,000, preferably between 49,000 and 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, metals such as iron, nickel, copper, zinc, cobalt, manganese, chromium, rare earth and the like, and their alloys or oxides, whose surface is oxidized or not oxidized, can be used. Also, there is no particular restriction on the manufacturing method.

 Hereinafter, the measurement method according to the present invention will be described.

Measurement of triboelectric charge: The measurement method will be described in detail with reference to the drawings.

FIG. 1 is an explanatory view of an apparatus for measuring a triboelectric charge amount of a toner. First, a mixture of a fluidity improver and a carrier in a weight ratio of 1:49 to be measured for a triboelectric charge amount in a metal measuring container 2 having a 500-mesh screen 3 at the bottom is prepared for 50 to 10 minutes.
Place in a 0 ml polyethylene bottle, shake by hand for about 10 to 40 seconds, add about 0.5 to 1.5 g of the mixture (developer) and close the metal lid 4. At this time, the weight of the entire measurement container 2 is weighed and defined as W ₁ (g). Next, in the suction device 1 (at least the portion in contact with the measurement container 2 is an insulator), the pressure of the vacuum gauge 5 is adjusted to 250 m
mAq. In this state, suction is sufficiently performed, preferably for 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). Further, the weight of the whole measurement container after suction is weighed to be W ₂ (g). The triboelectric charge of this toner (μ
c / g) is calculated as follows.

(However, the measurement conditions are 23 ° C. and 60% RH.) The carrier used for the measurement is EFV200 / 300 (manufactured by Powder Tech).

Next, specific examples of the contact charging step applicable to the present invention will be 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. 2, 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 the metal core 14a,
Further, a surface layer 14c as a release coating was provided on the peripheral surface.
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. 3 can be used. Although a blade-shaped contact charging material is used here, the metal supporting member 14'a to which a voltage is supplied is also used.
By supporting the conductive rubber 14'b by the above and providing a surface layer which is a release coating at a 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-based resins PVDF (polyvinylidene fluoride) and PVDC (polyvinylidene chloride) can be used for the release coating. 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.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples (Examples of producing a polyester resin and Examples of a toner using the resin).

Resin production example 1 The above compounds were mixed at a molar ratio of 1: 1 and placed in a two-volume, four-necked round-bottomed flask equipped with a thermometer, a Teflon-coated stirring blade, a glass nitrogen inlet tube, a condenser, and a decompression device. After the by introduction of nitrogen gas reactor than the glass inlet tube an inert atmosphere, by adjusting the opening of the pressure reducing control valve and a nitrogen gas inlet valve, maintaining the system inside -750mmH ₂ O. Thereafter, the reactor was placed in a mantle heater, and a condensation reaction was performed at 170 ° C. for 20 hours. The pressure at this time was also kept at -750mmH ₂ O.

 This is designated as resin A.

 Thereafter, acetic acid was added to the system to obtain resin B.

Further, diethanolamine was added to the system to obtain a modified polyester resin C.

Separately, triethanolamine was added instead of diethanolamine to obtain a modified polyester resin D. Table 1 shows the acid value and the hydroxyl value of the resins A to D.

Example 1 The mixture is sufficiently premixed with a Henschel mixer, melt-mixed at least twice with a three-roll mill, cooled, coarsely pulverized to about 1 to 2 mm using a hammer mill, and then finely pulverized by an air jet pulverizer. did. Further, the obtained finely pulverized material was classified to select a particle size of 2 to 10 μm so as to have a flow rate distribution of the present invention, thereby obtaining colorant-containing resin particles.

100 parts by weight of the above colorant-containing resin particles were treated with 0.5 parts by weight of hexamethyldisilazane and treated with 0.5 parts by weight of hexamethyldisilazane (triboelectric charge amount of -50 μc / g, BET specific surface area of 230 m ² / g) and 0.5 parts by weight of alumina fine powder ( Triboelectric charge amount 1.7μc / g, BET specific surface area 100m ² /
g) was added externally to obtain a cyan toner.

This cyan toner Met.

A copolymer (number average molecular weight: 21,250, weight average molecular weight: 52,360) composed of 50% styrene, 20% methyl methacrylate, and 30% 2ethylhexyl acrylate was added to 5 parts by weight of the cyan toner.
%, Cu-Zn-F having a particle size distribution of 35-40 μm, 9.5%
An e-ferrite carrier was mixed with a 0.5% coated carrier in a total amount of 100 parts by weight to prepare a developer.

Using this developer, the charging device of a commercially available plain paper color copying machine (Color Laser Copier 500, manufactured by Canon Inc.) was modified to have the configuration shown in FIG. Second
In the figure, the outer diameter of the charging roller 14 is 12 mmφ, the conductive rubber layer 14b is made of EPDM, and the surface layer 14c is made of a 10 μm thick nylon resin. The hardness of the charging roller 14 is 54.5 (ASKE
RC).

 The developing voltage was adjusted so that the developing contrast was 290V at 23 ° C / 65%, 350V at 20 ° C / 10%, and 250V at 30 ° C / 80%.

As a result, the image density was stable at 1.45 to 1.55 in each environment,
It was clear with no fog. Further, no cleaning failure occurred and no decrease in charging efficiency was observed.

Experimental Example 1 Example 1 was repeated except that resin B was used.
When the image was formed in the same manner as described above, a slight contamination of the charging roller was observed after 15,000 sheets of the endurance sheet at 15 ° C./10%, filming occurred on the photoreceptor, and image deterioration occurred. The image density was 1.30, which was slightly lower than that of Example 1.

Comparative Example 1 An image was formed in the same manner as in Example 1 except that the surface layer 14c was not provided in the charging device of Example 1, and toner fusion occurred on the photoconductor. This is considered to be due to the softening agent for the rubber of the charging roller.

Example 2 The same procedure as in Example 1 was carried out except that the surface layer 14c was made of PVdF resin in the charging device of Example 1, and good results were obtained.

Example 3 Example 1 except that resin D was used instead of resin C.
The image density was reduced by 0.05 at 15 ° C / 10%, and the image density was slightly higher at 30 ° C / 80% by 0.10 at 30 ° C / 10%. A good image was obtained without poor cleaning and no filming of the photoreceptor.

Example 4 In Example 1, BET was used instead of alumina fine powder.
The same procedure as in Example 1 was carried out except that 0.4 parts by weight of TiO ₂ fine powder having a surface area of 80 m ² / g according to the method and a triboelectric charge amount with the carrier of −10 μc / g was used. The result was obtained.

Comparative Example 2 When image formation was performed in the same manner as in Example 1 except that the alumina fine powder was not used, filming occurred on the photoconductor during durability, and image deterioration occurred.

Experimental Example 2 In Example 1, BET was used instead of alumina fine powder.
Except using 0.4 parts by weight of TiO ₂ fine powder (T-805: manufactured by Nippon Aerosil Co., Ltd.) whose surface area by the method is 50 m ² / g and the triboelectric charge amount with the carrier is -12.5 μc / g. When performed in the same manner as in Example 1, the image density was 1.3 at 20 ° C./10%.
0 to 1.35, filming occurred on the photoreceptor during running, and the image deteriorated as compared with Example 1.

Example 5 Using the cyan toner of Example 1, a developing device of a commercially available color copying machine (Color Laser Copier 500, manufactured by Canon Inc.) was modified so as to have the configuration shown in FIG. I did it.

That is, in FIG. 4, reference numeral 22 denotes a sleeve (coat layer thickness: 13 μm) formed by coating a phenol resin in which 40 parts by weight of molybdenum disulfide is dispersed on the surface of an aluminum cylinder. 24 is a urethane sponge roller. The developer coating blade 25 is in contact with the sleeve 22 at a linear pressure of 80 g / cm. In addition, the gap between the developer carrier and the latent image
m and the thickness of the toner layer was regulated to 50 μm. All other conditions are set in the copying machine.

As a result of endurance test of 5,000 sheets under each environment of 20 ° C / 10%, 23 ° C / 60%, 50 ° C / 80%, no sleeve contamination and sleeve fusion were observed in each environment, and the image density was low. A clear image with a stable 1.40 to 1.55 and no fog was obtained.

[Effects of the Invention] In the present invention, in the image forming method having the above-described charging step, development is performed in the development step using the toner obtained by improving the resin particles and the flowability improver. Very little toner remains on the charged member, and no fixation occurs on the surface of the charging member or the surface of the charged member, so that a high-resolution and high-definition image can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an apparatus for measuring a triboelectric charge amount of a toner, FIGS. 2 and 3 are explanatory views of a charging apparatus suitable for the present invention, and FIG. 4 is a developing apparatus suitable for the present invention. It is explanatory drawing of an apparatus.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location G03G 15/08 507 G03G 9/08 374 (56) References JP-A-1-204081 (JP, A JP-A-2-83551 (JP, A) JP-A-61-105562 (JP, A) JP-A-1-306860 (JP, A)

Claims (4)

(57) [Claims] An image forming method comprising: a charging step of charging a member to be charged by contacting a charging member to which an external voltage is applied, a developing step of developing the charged member with toner, a transfer step, and a cleaning step. The charging member has a conductive rubber layer, and a surface layer of a release coating provided at least in a portion outside the conductive rubber layer and in contact with the member to be charged. The toner is an insulating negatively-chargeable non-magnetic color toner having at least a non-magnetic colorant-containing polyester resin particle and a fluidity improver, and the colorant-containing polyester resin particle has a volume A polyester resin having an average diameter in the range of 4 to 10 μm, the constituents of which are mainly composed of a diol component and a dicarboxylic acid component, and at least a part of —COOH is substituted by a functional group containing N. An image forming method, comprising: when at least one of the fluidity improvers is frictionally charged with a carrier, the absolute value of the charge amount is 10 μc / g or less. 2. The negatively chargeable nonmagnetic color toner has a volume average diameter in the range of 6 to 10 μm and contains 15 to 40% by number of colorant-containing polyester resin particles having a particle diameter of 5 μm or less. Containing 0.1 to 5.0% by volume of a colorant-containing polyester resin particle having a particle size of 12.7 to 16.0 μm,
The colorant-containing polyester-based resin particles having a particle diameter of 6.35 to 10.1 μm containing the colorant-containing polyester-based resin particles having a particle diameter of not less than 1.0% by volume have the following formula: 2. The image forming method according to claim 1, wherein the following condition is satisfied. 3. The fluidity improver, when triboelectrically charged with a carrier, has an absolute value of an electric charge of 50 μc / g or less, and when frictionally charged with a carrier, has an absolute value of an electric charge of 50 μc / g or less.
The image forming method according to claim 1, further comprising a negatively chargeable inorganic oxide of μc / g or more. 4. As a fluidity improver, a hydrophilic inorganic oxide having an absolute value of a charge amount of 20 μc / g or less and a specific surface area of 30 to 200 m ² / g by a BET method when frictionally charged with a carrier. When frictionally charged with a carrier, the absolute value of the charge amount is 50μ
0.3 to ² % by weight, based on the colorant-containing polyester resin particles, of a negatively chargeable hydrophobic inorganic oxide having a specific surface area of at least c / g and a BET method of 80 to 300 m ² / g. The image method according to claim 1, wherein: