JP2805653B2 - Non-magnetic one-component developer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a developer and a developing method used for an electrophotographic copying machine or an electrostatic recording apparatus, and more particularly, to image density, resolution, The present invention relates to a non-magnetic one-component developer excellent in image characteristics such as gradation, and a developing method using the developer.

[Conventional technology]

As a developing method used in an electronic copying machine or an electrostatic recording apparatus, a method of transporting a developer by a transport member and visualizing an electrostatic latent image formed on a photoconductor by the developer is well known. .

In this developing method, a one-component developer composed of only a toner or a two-component developer composed of a toner and a carrier is generally used.

In recent years, various types of developing methods using a one-component developer consisting of toner alone have been proposed because of the advantages that the apparatus can be downsized and maintenance is easy (US Pat. No. 3,909,25).
No. 8, U.S. Pat. No. 4,121,931).

By the way, as a one-component developer, there is a magnetic one-component developer containing a magnetic powder. However, since a magnetic toner having a relatively small specific resistance is used, a developed image on an electrostatic latent image is transferred to plain paper or the like. It is difficult to transfer electrostatically to the support member of
Further, since a large amount of magnetic powder is contained in the toner, a color toner cannot be obtained.

Therefore, recently, a developing method using a non-magnetic one-component developer having a large specific resistance without containing magnetic powder has attracted attention.
This non-magnetic one-component developer usually contains a binder resin and a colorant such as carbon black, which is advantageous for colorization.

Non-magnetic one-component developer (hereinafter also referred to as non-magnetic toner)
Is carried out, for example, as follows using a developing device shown in FIG.

That is, a developing roll 3 and a toner replenishing roll 4 are provided in pressure contact with the photoreceptor 1 in a toner container 2 installed near the photoreceptor 1, and a developing bias is applied to the developing roll 3 by a power supply 5. Has been applied.

The toner container 2 contains a one-component developer 6 made of a non-magnetic toner, and the toner 6 supplied to the surface of the toner supply roll 4 is rotated by the rotation of the toner supply roll 4.
Is transported to the contact surface with the developing roll 3. Further, the non-magnetic toner is carried to the photoconductor 1 side with the rotation of the developing roll 3 so that the electrostatic latent image formed on the surface of the photoconductor 1 is developed.

In this developing method, it is important to form a non-magnetic toner layer having a uniform thickness and a small thickness on the developing roll 3. For this reason, the thickness of the non-magnetic toner layer adhering to the surface of the developing roll 3 must be reduced. A layer thickness regulating member 7 that regulates uniformly is provided.

However, in this developing method, when a toner composed of a binder resin and a colorant, which has been conventionally used for a two-component developer, is used as a one-component developer, toner replenishment is unstable, and a thin uniform It is extremely difficult to form a toner layer, sufficient triboelectric charging does not occur, and only a poor image with a low image density and a lot of background stains can be obtained.

[Problems to be solved by the invention]

An object of the present invention is to provide a stable toner replenishment, obtain a thin and uniform toner layer on a developing roll, and reproduce a sufficient amount of toner with respect to an electrostatic latent image on a photoreceptor from the developing roll. Accordingly, it is an object of the present invention to provide a non-magnetic one-component developer having high image density and free from defects such as background stain.

Another object of the present invention is to provide a developing method using a non-magnetic one-component developer having such excellent characteristics.

Another object of the present invention is to provide a developing method using a reversal developing method in which the polarity of the toner is the same as the polarity of the electrostatic latent image on the photoconductor, and / or the development roller and the electrostatic latent image on the photoconductor. To provide a developing method for directly contacting and developing.

The present inventors have conducted intensive studies to overcome the problems of the prior art and found that the shape, particle size, particle size distribution, charge amount, etc. of the non-magnetic toner can be controlled to a specific limited range. As a result, the present inventors have found that the above object can be achieved, and have completed the present invention based on the findings.

[Means for solving the problem]

Thus, according to the present invention, the electrostatic latent image formed on the photoconductor is developed by the developing device including the developing roll and the developing blade for uniformly regulating the layer thickness of the developer supplied on the developing roll. (B) volume average particle diameter (dv) in the range of 5 to 15 μm; and (b) volume average particle diameter (dv). The ratio (dv / dn) of dv) to the number average particle size (dn) is in the range of 1.00 to 1.40, and (c) the area (Sc) of a circle whose diameter is the absolute maximum length of the particle is the actual projected area of the particle. The value (Sc / Sr) divided by (Sr) is 1.00
And (d) the product (A * dn *) of the specific surface area (A) (m ² / g), the number average particle diameter (dn) (μm), and the true specific gravity (D) according to the BET method.
D) is substantially spherical in the range of 5 to 10;
/ A) is in the range of 15 to 70.

Further, according to the present invention, there is provided a developing method as described above, wherein the nonmagnetic one-component developer is used as a developer.

In particular, as the developing method, a method of developing by a reversal developing method in which the polarity of the electrostatic latent image on the photoconductor and the polarity of the non-polar one-component developer are the same, There is provided a method of developing by directly contacting a developing roll.

Further, the substantially spherical non-magnetic one-component developer is
It can be produced by polymerizing a homogeneous mixture containing a vinyl monomer and a colorant by a suspension polymerization method.

Here, the method and apparatus for measuring the physical properties of the developer in the present invention are as follows.

Sc / Sr is a value measured and analyzed by an image processing analyzer under the following conditions.

Image processing analyzer: Luzex IID (manufactured by Nicole Corp.) Area ratio of particles to frame area: Max 2% Total number of processed particles: 1000 (Sc / Sr values are indicated by the number average of 1,000) BET The specific surface area (A) is a value measured using a specific surface area automatic measuring apparatus Model 2200 manufactured by Shimadzu Corporation. The volume average particle diameter (dv) and the number average particle diameter (dn) are measured with a Coulter counter (model TA). -II type, manufactured by Nikkaki Co., Ltd.), and the true specific gravity is a value measured by a Beckman hydrometer.

 Hereinafter, the present invention will be described in detail.

(Non-magnetic one-component developer) Conventionally, a toner is generally prepared by melting and kneading a mixture containing a binder resin and a colorant, then cooling, pulverizing with a pulverizer, and classifying to uniform particle diameters. Was. However, the toner obtained by such a pulverization method is
The particle shape is irregular, and the value (Sc / Sr) obtained by dividing the area (Sc) of a circle whose diameter is the absolute maximum length of the particle by the actual projected area (Sr) of the particle generally exceeds 1.3. Also, BE
T method specific surface area (A) increases, specific surface area (A) (m ² /
g), number average particle diameter (dn) (μm) and true specific gravity (D)
The value of the product (A * dn * D) exceeds 10.

The toner having the shape and properties as described above has fluidity,
On the other hand, when used as a developer in the developing method, the toner layer supplied on the developing roll becomes non-uniform, resulting in an image having a low image density and having a lot of density unevenness and background stain.

On the other hand, in the non-magnetic toner of the present invention, the area (Sc) of a circle having the absolute maximum length of the particle as the diameter is calculated as the substantial projected area (Sr) of the particle.
(Sc / Sr) is in the range of 1.00 to 1.30, and the specific surface area (A) (m ² / g), number average particle diameter (dn) (μm), and true specific gravity (D ) Product (A * dn *)
Since D) is a substantially spherical particle in the range of 5 to 10, the fluidity thereof is extremely good.

Further, among the above substantially spherical toners, the volume average particle diameter (dv) is in the range of 5 to 15 μm, and the ratio of the volume average particle diameter (dv) to the number average particle diameter (dn) (dv / dn). Is 1.00-1.4
0, preferably in the range of 1.00 to 1.25, and the blow-off method (carrier TEFV150 / 250, toner concentration 5%, 150 rpm
(Measured after mixing and stirring for 30 minutes by rotation)
When a toner having a characteristic (Q / A) of (μc / g) and specific surface area (A) in the range of 15 to 70, preferably 20 to 60 is used as a developer in the above-mentioned developing method, the toner on the developing roll Since a uniform thin toner layer is formed on the surface of the photoreceptor, the toner can easily ride on the latent image, and the charge on the particle surface is constant and uniform. As a result, a clear image having a high image density and having no dust and unevenness is formed. However, the charge amount (Q) and the ratio (Q /
A) shows the absolute value.

Further, when the non-magnetic toner of the present invention is used, the frictional charging property between the developing roller and the toner layer thickness regulating member becomes constant and uniform, and the electrostatic latent image on the photoconductor is brought into direct contact with the developing roller. Even if the developing method is adopted, background stain does not occur.

In a cleaning process using a blade or the like after the transfer process of transferring the developed image on the photoconductor onto a support such as paper,
The non-magnetic toner of the present invention is mostly removed from the photoreceptor, and the toner remaining on the photoreceptor without being slightly removed is also removed by the developing roll at the same time as the development in the next development step, so that the long-term continuous development However, a stable and good image can be obtained.

These excellent effects can be obtained for the first time as a result of the shape, particle size, particle size distribution, charge amount, and the like of the nonmagnetic toner particles being mutually balanced.

If particles that do not satisfy the conditions of the shape factor (Sc / Sr) and cough (A * dn * D) are used as the toner, the transfer efficiency is low, the image density is insufficient, and the background stain and image unevenness occur. .

With a non-magnetic toner having a volume average particle diameter (dv) of less than 5 μm or more than 15 μm, uniformity of the toner layer on the developing roll cannot be obtained, or transfer efficiency deteriorates, and sufficient image density cannot be obtained.

The ratio of the volume average particle diameter (dv) to the number average particle diameter (dn) (dv / d
If the particle size distribution is so wide that n) exceeds 1.40, toner replenishment becomes extremely unstable during long-term continuous development.

Ratio (Q / A) of charge amount (Q) (μc / g) and specific surface area (A)
If less than 15 or more than 70 toner is used,
A sufficient image density cannot be obtained, or the image has a lot of background stains. Also, in the cleaning step after the transfer, the toner is too strongly adhered to the photoreceptor, so that it is not sufficiently removed by a cleaning blade or the like, and a problem such as generation of a ghost image occurs.

(Production Method of Non-Magnetic One-Component Developer) The non-magnetic toner of the present invention can be obtained by polymerizing a homogeneous mixture containing a vinyl monomer and a colorant by a suspension polymerization method.

As a specific suspension polymerization method, for example, a uniform mixture is prepared by uniformly dispersing a mixture containing a vinyl monomer, a colorant, a radical polymerization initiator, and various additives as required by a ball mill or the like. Then, this homogenous mixed solution is finely dispersed in water by high decoction and stirring to form an aqueous dispersion,
Usually, there is a method of performing suspension polymerization at a temperature of 30 to 200 ° C.

Examples of the vinyl monomer used here include, for example,
Styrene monomers such as styrene, vinyltoluene and α-methylstyrene; acrylic acid, methacrylic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate, Derivatives of acrylic acid or methacrylic acid such as propyl metal acrylate, butyl methacrylate, 2-ethylhexyl methacrylate, dimethylaminoethyl methacrylate, acrylonitrile, and acrylamide; ethylenically unsaturated monoolefins such as ethylene, propylene and butylene; vinyl chloride; Vinyl halides such as vinylidene chloride and vinyl fluoride; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl methyl ketone and methyl Vinyl ketones such as isopropenyl ketone; 2-vinylpyridine, 4-vinylpyridine, N-
Nitrogen-containing vinyl compounds such as vinylpyrrolidone and the like. These vinyl monomers may be used alone,
A plurality of monomers may be used in combination for copolymerization.

In addition, along with these vinyl monomers, an optional crosslinking agent, for example, divinylbenzene, aromatic divinyl compounds of divinylnaphthalene and derivatives thereof; ethylene glycol dimethacrylate, diethylenically unsaturated carboxylic acid esters such as diethylene glycol methacrylate;
Divinyl compounds such as N, N-divinylaniline and divinyl ether, and compounds having three or more vinyl groups can be used alone or in combination of two or more.

Examples of the colorant used in the present invention include, for example, carbon black, aniline black, crystal violet, rhodamine B, malachite green, nigrosine,
Pigments and dyes such as copper phthalocyanine and azo dyes can be used alone or in combination of two or more.

Further, nigrosine dye, monoazo dye, metal-containing dye, zinc hexadecyl succinate, alkyl ester or alkyl amide of naphthoic acid, nitrohumic acid,
N, N'-tetramethyldiaminebenzophenone, N, N'-
One or more kinds of strongly polar substances called charge control agents in this field, such as tetramethylbenzidine, triazine and metal salicylate complex, may be contained.

Further, the non-magnetic toner of the present invention has a chargeability, conductivity,
Various additives for controlling the fluidity or adhesion to the photoreceptor or the fixing roll may be contained, or may be externally added.

Examples of additives include release agents such as low molecular weight polyethylene, low molecular weight polypropylene, various waxes, and silicone oil; inorganic fine powders such as carbon black, silica, alumina, titanium oxide, zinc oxide, cerium oxide, and calcium carbonate; And the like.

(Developing Method) The non-magnetic toner of the present invention is formed on a photoreceptor surface by a developing device provided with a developing roll and a developing blade for uniformly controlling a layer thickness of a developer supplied on the developing roll. Used in a method of developing a latent image with a developer.

In this case, it is preferable that the developing is performed by a reversal developing method in which the polarity of the electrostatic latent image on the photoconductor and the polarity of the non-magnetic one-component developer are the same.

Further, it is preferable that the electrostatic latent image on the photoreceptor is brought into direct contact with the developing roll for development.

〔The invention's effect〕

According to the present invention, as compared with the prior art, a developing device provided with a developing roll and a developing blade for uniformly regulating the layer thickness of a developer supplied on the developing roll has a static electricity formed on a photoreceptor. When used in a method of developing an electro-latent image with a developer, the toner rides on the latent image well, and the transfer efficiency of the toner in the transfer process is high, so that the image density is high, and there is no An image is formed, and a toner having good image quality without background smear is provided.

Further, even in long-term continuous development, a decrease in image density,
The present invention provides a non-magnetic toner capable of obtaining a stable image quality without an increase in background stain, generation of a ghost image, and the like, and a developing method using the toner.

〔Example〕

Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to only these Examples. In the following examples, parts and percentages are by weight unless otherwise specified.

[Example 1] 70 parts of styrene, 30 parts of butyl methacrylate, 4 parts of low molecular weight polypropylene, 10 parts of carbon black (trade name: PRINTEX 150T), Cr-based dye (trade name: Bontron-3)
4) 1.0 part and 2,2'-azobis (2,4-dimethylvaleronitrile) 2 parts were subjected to ball mill dispersion to obtain a uniform mixed solution.

Next, the above mixture was added to 305 parts of pure water in which 3 parts of calcium phosphate was finely dispersed to obtain an aqueous dispersion.

The aqueous dispersion was subjected to high-blow stirring with a rotor-stator-type homomixer under the condition of pH 9 or more, and the mixed liquid was finely dispersed in water and dispersed.

Next, this aqueous dispersion is put into a reactor equipped with a stirring blade,
Polymerization was carried out with stirring at 65 ° C. for 4 hours.

The polymer dispersion thus obtained was thoroughly washed with acid and water, then separated and dried to obtain a toner material.

To 100 parts of the above toner material, 0.2 parts of hydrophobic silica was externally added as a fluidizing agent to obtain a non-magnetic toner.

The non-magnetic toner thus obtained was substantially spherical particles having the properties shown in Table 1.

Next, an apparatus using the above non-magnetic toner and having basically the configuration shown in FIG. 1, wherein an organic photoreceptor is used as the photoreceptor 1, and a developing roll 3 is provided around a metal core conductive support Image evaluation was carried out by using a device provided with a rubber-based toner carrying layer on the surface thereof and using a device having a contact-developing type developing machine using urethane-based rubber as the toner layer thickness regulating member 7.

The resulting image has a high image density, background stain, dust,
The image was clear without unevenness, and stable image quality was obtained even in continuous development of 20,000 sheets.

Example 2 In Example 1, a Cr-based dye (trade name: Bontron S-
34) The procedure of Example 1 was repeated except that 0.3 parts of a Cr-based dye (trade name: Spiron Black TRH) was used instead of 1.0 part, and 400 parts of pure water in which 6 parts of calcium phosphate were finely dispersed were used as a dispersion medium. In a similar manner, a toner material having a smaller volume average particle diameter (dv) than in Example 1 was obtained.

To 100 parts of the toner material, alumina 0.5 was used as a fluidizing agent.
Was added externally to obtain a non-magnetic toner. The obtained non-magnetic toner is a substantially spherical particle having a volume average particle diameter (dv) as fine as 5.9 μm, a narrow particle diameter distribution (dv / dn ratio) of 1.20, and having the characteristics shown in Table 1. there were.

Next, using the above magnetic toner, image evaluation was performed using the same apparatus as in Example 1.

The resulting image has a high image density, background stain, dust,
There was no unevenness and the gradation and resolution were extremely excellent.

[Example 3] Same as Example 1 except that 5 parts of carbon black (trade name PRINTEX 150T) and 3.0 parts of a Cr-based dye (trade name Bontron S-34) were used as the colorant. In this way, a toner material having a higher Q / A ratio than that of Example 1 was obtained.

0.6 parts of hydrophobic silica was externally added as a fluidizing agent to 100 parts of the toner material to obtain a non-magnetic toner. The obtained non-magnetic toner was substantially spherical particles having the characteristics shown in Table 1.

Next, image evaluation was performed using the above non-magnetic toner with the same apparatus as in the example.

The resulting image has a high image density, background stain, dust,
It was clear without unevenness.

Comparative Example 1 100 parts of a styrene-butyl methacrylate copolymer (styrene: butyl methacrylate ratio = 70: 30), 10 parts of carbon black (trade name: Cabot BPL), 1 part of Cr-based dye (trade name: Bontron S-34) After melt-kneading 4 parts of low molecular weight polypropylene with a kneader, the mixture was pulverized with a jet mill, and further subjected to air classification to obtain a toner material.

To 100 parts of the above toner material, 0.2 parts of hydrophobic silica was externally added as a fluidizing agent to obtain a non-magnetic toner. The obtained non-magnetic toner has a shape factor (Sc / Sr) as shown in Table 1.
The particles were amorphous particles having a size of 1.53 and a product (A * dn * D) of 14.6.

Next, using the above-mentioned non-magnetic toner, image evaluation was performed using the same apparatus as in Example 1.

With the above non-magnetic toner, the thickness of the toner layer on the developing roll became nonuniform, the image density was low, the background was stained a lot, and the image was uneven in density.

When the continuous development was performed on 20,000 sheets, the image density decreased and the background stain increased extremely with the lapse of time, and the toner was unusable in the present development system.

[Comparative Example 2] In Example 1, a Cr-based dye (trade name: Bontron S-
A toner material was obtained in the same manner as in Example 1 except that 34) was not used.

To 100 parts of the above toner material, 0.2 parts of hydrophobic silica was externally added as a fluidizing agent to obtain a non-magnetic toner.

The non-magnetic toner thus obtained was a substantially spherical toner as shown in Table 1, but the charge amount (Q) (μ
c / g) and the specific surface area (A) (Q / A) were as small as 13.

Next, using the above-mentioned non-magnetic toner, image evaluation was performed using the same apparatus as in Example 1.

The obtained image had a low image density, was stained on the entire surface, and had many irregularities.

[Comparative Example 3] In Example 1, a Cr-based dye (trade name: Bontron S-
34) A non-magnetic toner was obtained in the same manner as in Example 1, except that 5.0 parts of a Cr-based dye (trade name: Spiron Black TRH) was used instead of 1.0 part.

The non-magnetic toner thus obtained was a substantially spherical toner as shown in Table 1, but the charge amount (Q) (μ
c / g) and the specific surface area (A) were as large as 79 (Q / A).

Next, an image evaluation was performed using the above non-magnetic toner with the same apparatus as in Example 1.

The obtained image had a low image density, a large amount of dust, and a high ghost image due to high adhesion to the toner photoreceptor.

[Brief description of the drawings]

FIG. 1 is a schematic diagram (partial sectional view) showing a configuration example of a developing device using a non-magnetic one-component developer of the present invention. DESCRIPTION OF SYMBOLS 1 ... Photoreceptor, 5 ... Bias power supply, 2 ... Toner container, 6 ... Toner, 3 ... Developing roll, 7 ... Toner layer thickness regulating member, 4 ... Toner supply roll.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Jun Saito 1-2-1 Night Light, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture, Japan Zeon Corporation Research and Development Center (56) References JP-A-61-279864 (JP, A) JP-A-62-223765 (JP, A) JP-A-63-38947 (JP, A) JP-A-1-158459 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9/08

Claims (5)

(57) [Claims] An electrostatic latent image formed on a photoreceptor is developed with a developer by a developing device having a developing roll and a developing blade for uniformly regulating a layer thickness of the developer supplied on the developing roll. In the developer used in the method,
The developer contains a binder resin and a colorant, (a) the volume average particle diameter (dv) is in the range of 5 to 15 μm, and (b) the ratio of the volume average particle diameter (dv) to the number average particle diameter (dn). (Dv / dn) is in the range of 1.00 to 1.40, and (c) the value (Sc / Sr) obtained by dividing the area (Sc) of the circle having the absolute maximum length of the particle as the diameter by the actual projected area (Sr) of the particle. Is 1.00
And (d) the product (A * dn *) of the specific surface area (A) (m ² / g), the number average particle diameter (dn) (μm), and the true specific gravity (D) according to the BET method.
D) is substantially spherical in the range of 5 to 10;
/ A) is in the range of 15 to 70. 2. A composition obtained by polymerizing a homogeneous mixture containing a vinyl monomer and a colorant by a suspension polymerization method.
A non-magnetic one-component developer as described in the above. 3. An electrostatic latent image formed on the surface of a photoreceptor is developed with a developer by a developing device having a developing roll and a developing blade for uniformly regulating a layer thickness of the developer supplied on the developing roll. A developing method, wherein the non-magnetic one-component developer according to claim 1 is used as a developer. 4. The developing method according to claim 3, wherein the developing is performed by a reversal developing method in which the polarity of the electrostatic latent image on the photosensitive member and the polarity of the non-magnetic one-component developer are the same. 5. The developing method according to claim 3, wherein the development is performed by directly contacting the electrostatic latent image on the photosensitive member with the developing roll.