JP3328013B2 - Electrostatic image developer and multicolor image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer for an electrostatic image and a method for forming a multicolor image.

[0002]

2. Description of the Related Art Conventionally, as a technique for forming a good multicolor image without color misregistration by using a small and low-cost multicolor image forming apparatus, the surface of a uniformly charged image forming body has been developed. By spot exposure with a laser beam or the like to form an electrostatic latent image, and repeatedly developing the electrostatic latent image on the image forming body in a non-contact manner with a two-component developer including a color toner, A method is known in which a plurality of color toner images of different colors are formed by superimposing on the image forming body, and then the plurality of color toner images are collectively transferred and fixed to form a multicolor image. I have.

However, the technique for forming a multicolor image as described above has the following problems.

When forming a multicolor image continuously, it is difficult to maintain the toner charge amount of each color within a certain range, and the toner charge amount tends to change as the formation of the multicolor image is repeated. When the toner charge amount of each color changes, the developing toner amount controlled by the change also changes, and the ratio of each developing toner amount (superposition ratio) in a plurality of color toner images to be superimposed.
Changes with time. As a result, the color tone of the formed multicolor image changes over time.

A color toner constituting a developer used for forming a multicolor image has a relatively high charge retention.
Therefore, when a multi-color image is formed continuously, aggregation of toner particles occurs due to the action of the accumulated charges, and the fluidity is reduced. And when the liquidity decreases,
An appropriate amount of toner cannot be stably conveyed to the development area by the developer conveyance carrier, and good developability cannot be exhibited. In addition, image defects such as uneven image density and image unevenness are caused.

[0006] Since development is performed in a non-contact state with respect to the image forming body, the developability is easily hindered by the physical adhesion between the toner and the carrier. I can't get it.

[0007] Since a plurality of color toner images formed on the image forming body are collectively transferred, the time from development to transfer (contact time between the toner and the image forming body) becomes longer. In this case, the electrostatic or physical adhesion of the toner to the image forming body increases. For this reason, the transfer rate of the color toner image formed by the development to the transfer body is reduced, which also causes a reduction in image density.

[0008] In order to solve the above-mentioned problem, the following technique may be adopted.

(1) As an external additive of a developer used for forming an image, a silica to be treated with fine powder having an average primary particle size of 1 to 30 nm and an inorganic oxide having an average particle size of 150 to 5000 nm are used in combination. Technology (see JP-A-57-179866).

(2) As an external additive of a developer used for forming an image, a low charge (20 μC / g or less) and a large particle size (B
(ET specific surface area: 30 to ²⁰⁰ m ² / g), a hydrophilic inorganic fine particle, a highly charged (50 μC / g or more) and small particle size (BE)
A technique in which a negative hydrophobic inorganic oxide having a T specific surface area of 80 to 300 m ² / g) is used in combination (see JP-A-4-3073).

(3) A technique for improving fluidity and developability by using inorganic fine particles having an average particle diameter of 7 to 20 nm by a BET method as an external additive of a developer used for forming an image (Japanese Patent Laid-Open Publication See JP-A-62-182775).

However, in the technique (1), since the particle diameter of the inorganic oxide and the particle diameter ratio to the finely powdered silica are too large, the finely powdered silica and the inorganic oxide are toner (colored). Particles)
Sarezu, Therefore charge distribution becomes wider, leading to image deterioration and toner scattering. Further, these are separated from the surface of the colored particles, and the free inorganic fine particles cause in-machine contamination and surface contamination of the image forming body. Furthermore, as a result of the surface of the inorganic oxide (large-diameter particles) being covered with the fine-powder-treated silica (small-diameter particles), the chargeability of the toner is inhibited.

In the technique (2), since the low-charge large-diameter hydrophilic inorganic fine particles and the high-charge small-particle negative hydrophobic inorganic oxide are used in combination, the charge amount over time can be reduced. The image change is so large that a stable image cannot be formed over a long period of time.

According to the technique (3), the developability can be improved to some extent in the initial stage of image formation. However, the average particle diameter of the inorganic fine particles is 7 to 2
Since it is relatively small, that is, 0 nm, the inorganic fine particles may be buried in the surface of the colored particles due to an external impact force as the formation of a multicolor image is repeated. As a result, the surface of the colored particles comes into direct contact with the surface of the carrier, the charge amount of the toner is affected, and the developability decreases over time, so that stable developability over a long period of time cannot be exhibited.

As described above, the above-mentioned problems (1) to (3) cannot be effectively solved even by the techniques such as the above (1) to (3).

[0016]

SUMMARY OF THE INVENTION The present invention has been made based on the above circumstances. A first object of the present invention is to form a plurality of color toner images having different colors on the image forming body by superimposing the electrostatic latent image on the image forming body in a non-contact state. When the method is applied to a multicolor image forming method in which a plurality of superimposed color toner images are collectively transferred, a change with time of a developing toner amount is small, and good developing property is stably exhibited. A stable multi-color image with good image quality and color tone can be formed for a long period of time without causing a decrease in image density due to insufficient image quality, a decrease in image density due to transfer failure, and an image failure due to a decrease in fluidity. To provide a developer for electrostatic images that can be used. A second object of the present invention is to provide a multicolor image forming method capable of stably forming a multicolor image having good image quality and color tone over a long period of time.

[0017]

According to the present invention, there is provided a developer for an electrostatic image, wherein at least colored particles containing a colorant and a binder resin contain large-sized inorganic fine particles L and small-sized inorganic fine particles S. A toner in which at least one kind of inorganic fine particles is externally added,
It comprises a carrier, and the large-diameter inorganic fine particles L and the small-diameter inorganic fine particles S satisfy the following conditions . <Conditions> The maximum volume distribution particle size of the large particle size inorganic fine particles L is D _L (n
m), 50 ≦ D _L <150.
The maximum volume distribution particle size of the small particle size inorganic fine particles S is D _S (nm)
That case, it is 10 ≦ D _S ≦ 50. The ratio of the maximum volume distribution particle size D _{L to} the maximum volume distribution particle size D _S is
1.5 ≦ (D _L / D _S ) <5.0. The triboelectric charge of the large-diameter inorganic fine particles L and carrier material Q _L,
The amount of triboelectric charge between the small-sized inorganic fine particles S and the carrier material is Q
When the _S, the frictional charge amount Q with respect to the triboelectric charge quantity Q _L
The absolute value of the ratio of _S (Q _S / Q _L) is 0 to 0.5. When the amount of the large-diameter inorganic fine particles L is
The surface coverage of the colored particles by the fine particles L is 10 to 60%.
The amount must be Addition amount of small-sized inorganic fine particles S
Is the surface coating of the colored particles with the small-sized inorganic fine particles S.
The amount must be 5 to 40%. Large particle size inorganic fine
When the total amount of the particles L and the small-sized inorganic fine particles S is
In which the surface coverage of the colored particles is 90% or less.
That.

Further, according to the multicolor image forming method of the present invention, the developer layer formed on the developer carrying carrier is transported to the developing area in a non-contact state with respect to the image forming body, and an AC bias is applied. By repeatedly developing the electrostatic latent image on the image forming body under the oscillating electric field obtained by applying, a plurality of color toner images of different colors are superimposed on the image forming body, and then formed. In a multicolor image forming method including a step of collectively transferring a plurality of color toner images, each developer for forming the plurality of color toner images is the developer for an electrostatic image described above. I do.

[0019]

The inorganic fine particles L having a large particle diameter constituting the developer of the present invention.
Is hard to be buried in the surface of the colored particles even when subjected to an external impact. Therefore, the chargeability can be stabilized, and good developability can be exhibited over a long period of time. Further, the fluidity can be improved by the small-sized inorganic fine particles S constituting the developer of the present invention. As will be understood from the results of examples described later, the maximum volume distribution particle diameter D _L of the large particle inorganic fine particles L, the maximum volume distribution particle diameter D S of the small particle inorganic fine particles _S , and the large particle inorganic fine particles L
The absolute value of the particle size ratio (D _L / D _S ) between the small particle size inorganic fine particles S and the large particle size inorganic fine particle S (Q _S / Q _L ) Only by controlling to a specific range, it is possible to stabilize developability, fluidity, and transferability, and to stably form a multicolor image having good image quality and color tone over a long period of time. It becomes possible.

Hereinafter, the present invention will be described in detail. The developer of the present invention is characterized in that high-charge large-diameter inorganic fine particles L and low-charge small-particle inorganic fine particles S are contained as external additives of the toner.

[Diameter of Large-Diameter Inorganic Fine Particles L] The maximum volume distribution particle diameter D _L of the large-diameter inorganic fine particles L is 50 nm or more and 1
It is less than 50 nm. The value of the maximum volume distribution particle diameter D _L is 5
When the thickness is less than 0 nm, the inorganic fine particles are buried in the surface of the colored particles, causing a change in the amount of charge with time, and in particular, in non-contact development, the physical adhesion between the toner and the carrier becomes excessive. As a result, the developing property is hindered, the amount of developing toner decreases, and the image density decreases. Further, when the transfer is performed collectively, the transfer rate is reduced, which is not preferable. On the other hand, when the value is 150 nm or more, the balance between the self-weight of the inorganic fine particles and the physical adhesive force is poor. It is not preferable because the inside of the apparatus is contaminated or the surface of the image forming body is contaminated.

The value of the maximum volume distribution diameter D _S of [small-diameter inorganic fine particles S particle size] small-diameter inorganic fine particles S is 10nm or more 5
0 nm or less. The value of the maximum volume distribution diameter D _S is 10
When the particle diameter is less than nm, such inorganic fine particles having a very small particle size cover the surface of the inorganic fine particles L having a large particle size, and thus the chargeability is lowered. On the other hand, when this value exceeds 50 nm, the fluidity cannot be sufficiently improved, and in non-contact development, sufficient developability cannot be achieved from the initial stage.

Here, "maximum volume distribution particle size D
_“L (D _s )” refers to the particle size giving the maximum value (peak value) in the range of 5 to 500 nm in the volume particle size distribution of the inorganic fine particles. Further, the "maximum volume distribution diameter D _L (D _S)" is a transmission electron microscope "LEM-20
00 "(manufactured by Topcon Corporation), 50 fields of view were photographed at a magnification of 20,000 times, and measured from the projection surface of 200 or more particles.

[0024] [particle size ratio (D _L / D _S)] ratio of the maximum volume distribution diameter D _L to the maximum volume distribution diameter D _S (D _L /
D _S ) is 1.5 or more and less than 5.0. When the value of this ratio is less than 1.5, the large-diameter inorganic fine particles L
Is not preferred because the small particles of the inorganic fine particles S impair the charging property. On the other hand, when the value of this ratio is 5.0 or more, the large-sized inorganic fine particles L and the small-sized inorganic fine particles S
However, the particles are not uniformly attached to the surface of the colored particles, the charge amount distribution is widened, image deterioration and toner scattering are caused, and the surface of the large-sized inorganic fine particles L is covered with the small-sized inorganic fine particles S, It is not preferable because the chargeability is reduced.

[Ratio of triboelectric charge (Q _S / Q _L )] The chargeability of the toner is governed by the outermost inorganic fine particles in contact with the carrier surface, and the chargeability of the toner is controlled by the charge of the surface of the inorganic fine particles. This can be done by controlling the properties.
The large-sized inorganic fine particles L constituting the present invention are high-charged fine particles that govern the chargeability of the toner, while the small-sized inorganic fine particles S are low-charged fine particles. Therefore, the small-sized inorganic fine particles S (low-chargeability) used in combination with the large-size inorganic fine particles L (high-chargeability) do not substantially contribute to the chargeability, and are mainly used for improving the fluidity. It will contribute.

In the present invention, the triboelectric charge between the large-sized inorganic fine particles L and the carrier material is Q _L , and the small-sized inorganic fine particles S
And a triboelectric charge quantity of the carrier material when the Q _S, the ratio of the triboelectric charge quantity Q _S for the triboelectric charge quantity Q _L (Q _S /
The absolute value of Q _L) is 0 to 0.5. When the absolute value of the ratio of the triboelectric charge exceeds 0.5, the change in the charge over time is large, and a stable image cannot be formed over a long period of time.

Here, "the triboelectric charge amount Q with the carrier material Q"
_“L (Q _S )” refers to the triboelectric charge between a carrier material (eg, iron powder) and inorganic fine particles. Triboelectric charge quantity value Q _L (Q _S) is a carrier material (e.g. iron powder) and inorganic fine particles 50: 1 was filled into a sample bottle of 20cc at a weight ratio of (filling rate 50%), which Is shaken for 20 minutes (200 times / minute, arm length 15 cm, swing angle 45).
Degree), measured by the blow-off method.

[Materials of Inorganic Fine Particles] The constituent materials of the large-diameter inorganic fine particles L and the small-diameter inorganic fine particles S are not particularly limited. Examples of the material include silica, alumina, titanium oxide, and zirconium oxide. Among these, silica fine particles are preferable as the constituent material of the high-charge large-diameter inorganic fine particles L, and titanium oxide, alumina, zirconium oxide, and the like are preferable as the constituent materials of the low-charge small-particle inorganic fine particles S. Is preferred. In addition, from the viewpoint of further improving the fluidity of the toner constituting the developer of the present invention,
Inorganic fine particles other than the large-sized inorganic fine particles L and the small-sized inorganic fine particles S may be added and contained.

[Control of Charging Properties of Inorganic Fine Particles] The controlling of the charging properties of the inorganic fine particles can be performed by selecting the type of the inorganic fine particles or a surface treating agent (for example, a titanium coupling agent, a silane coupling agent, etc.) ) Can be done.

[Amount of Inorganic Fine Particles] The amount of the large-sized inorganic fine particles L added is such that the surface coverage of the colored particles with the large-sized inorganic fine particles L is 10 to 60% .
It is said. The surface coverage by the large-diameter inorganic fine particles L is 10
%, The image density of the formed image tends to change with time. On the other hand, when the surface coverage is 6
If it exceeds 0%, the adhesion of the colored particles to the surface is reduced, and the inside of the apparatus may be contaminated by the released large-sized inorganic fine particles L.

The amount of the small-sized inorganic fine particles S added is such that the surface coverage of the colored particles with the small-sized inorganic fine particles S is 5 to 40.
% . If the surface coverage by the small-sized inorganic fine particles S is less than 5%, the obtained developer cannot exhibit sufficient developability and sufficient fluidity. On the other hand, when the surface coverage exceeds 40%, the small-sized inorganic fine particles S are not uniformly attached to the surface of the colored particles.

The total amount of the large-sized inorganic fine particles L and the small-sized inorganic fine particles S is set so that the surface coverage of the colored particles by these becomes 90% or less . This surface coverage is 90
%, The adhesion of the colored particles to the surface is reduced, and the inside of the apparatus may be contaminated by the released inorganic fine particles.

Here, the “surface coverage of the colored particles” is defined as the projected area of the colored particles calculated from the volume average particle diameter, the BET
Means the value obtained from the projected area of the inorganic fine particles calculated by the method.

[Colored Particles] The colored particles constituting the developer of the present invention are particles containing at least a colorant and a binder resin (colorant-containing resin particles).

The binder resin constituting the colored particles is not particularly limited. For example, a styrene resin, an acrylic resin,
Styrene-acrylic resin, polyester resin and the like can be mentioned. Of these, polyester resins are preferred. In addition, a resin having a side chain that does not participate in cross-linking between main chains is preferable because burying of inorganic fine particles can be suppressed by its buffering property.

The coloring agent constituting the colored particles is not particularly limited, and various dyes and pigments can be used. The content ratio of the coloring agent is set to 1 because it has sufficient coloring properties and can prevent contamination due to separation or the like.
It is preferably from 10 to 10% by weight.

The coloring particles may optionally contain an internal additive such as a charge control agent. Here, examples of the charge control agent include metal complex dyes, nigrosine dyes, and ammonium salt compounds.

[Carrier] The developer for an electrostatic image of the present invention comprises a toner in which specific inorganic fine particles are externally added to colored particles, and a carrier. Here, the carrier is not particularly limited, for example,
A magnetic carrier composed of magnetic particles such as iron, ferrite, magnetite, a resin-coated carrier in which the surfaces of these magnetic particles are coated with a resin, and a magnetic substance dispersion type in which magnetic particles are dispersed and contained in a binder resin. A carrier etc. can be illustrated. Preferred examples of the coating resin for forming the resin-coated carrier include a styrene-acrylic resin, a silicone resin, and a fluorine resin.

[Multicolor Image Forming Method] The multicolor image forming method of the present invention uses the above-described developer for an electrostatic image (the developer of the present invention).
A developer layer formed on the developer carrying carrier, and transporting the developer layer formed on the developer carrying carrier to the developing area in a non-contact state with respect to the image forming body; By repeatedly developing the electrostatic latent image on the image forming body under an oscillating electric field obtained by applying a plurality of color toner images of different colors on the image forming body,
This is a method including a step of transferring a plurality of color toner images collectively.

FIG. 1 is a schematic view showing an example of a multicolor image forming apparatus which can be used in the method of the present invention. In this figure, reference numeral 1 denotes a negatively charged O having a carrier transport layer as an upper layer.
An image forming body made of a PC photoreceptor rotates in the direction of the arrow. Reference numeral 2 denotes an image input unit. The image input unit 2 includes an illumination light source 3, a color separation filter 4 composed of, for example, blue, green, red, and ND filters, each of which is replaceable; a reflection mirror 5; And a one-dimensional CCD image sensor 7. 8 is an image processing unit including an inverter for converting color separation information into complementary color information, 9 is a multicolor original, L is a laser beam output from a laser optical system 10, 11 is a negative charging charger composed of a scorotron band electrode, 12 is a corona discharger for transfer, 13 is a separation electrode, 14 is a fixing device, 15 is a static eliminator before cleaning, 16 is a cleaning device, and a cleaning device 16 is a cleaning blade 17 and a fur brush 1.
8 and a toner collecting roller 19.
A, B, C, and D are yellow, magenta, cyan,
This is a non-contact reversal developing device in which black developers are stored.

When the image input section 2 having the illumination light source 3 is moved in the direction of arrow X by a driving device (not shown), the multi-color original 9 is optically scanned. After being separated by the separation filter 4 and passed through the reflection mirror 5 and the lens 6, the color separation information is read by the CCD image sensor 7 and converted into an electric signal. This electric signal is converted by the image processing unit 8 into image data suitable for recording.

In the first rotation of the image forming body 1, the laser beam L according to, for example, the recording data of the yellow component of the image data is transmitted by the laser optical system 10.
Irradiation is performed on the image forming body 1 whose surface is uniformly negatively charged by the negative charging charger 11, and an electrostatic latent image corresponding to the recording data is formed on the image forming body 1. This electrostatic latent image is developed by a developing unit A containing yellow toner. In the second rotation of the image forming body 1,
Image forming body 1 on which toner image formed by yellow toner is formed
Is uniformly charged again by the negative charging charger 11,
The image forming body 1 is irradiated with a laser beam L according to recording data of another color component, for example, a red component, and an electrostatic latent image is formed. This electrostatic latent image is developed by the developing device B containing magenta toner, and as a result, two color toner images are formed on the image forming body 1 by yellow toner and magenta toner. Similarly to the above, in the third and fourth rotations of the image forming body 1,
A toner image of cyan toner and a toner image of black toner are formed on the image forming body 1 respectively. As a result, yellow, magenta, cyan,
The black toner images are superimposed to form four multicolor toner images.

The multicolor toner image thus obtained is collectively transferred onto the recording paper P by the corona discharger 12 for transfer, and the recording paper P is separated from the image forming body 1 by the separation electrode 13. After the fixing, the fixing device 14 performs a fixing process to form a multicolor image. On the other hand, after the transfer of the multicolor color toner image, the image forming body 1
Then, the toner is removed by the cleaning device 16 and used for forming the next multicolor image.

In the cleaning device 16, the cleaning blade 17, fur brush 18 and toner collecting roller 19 constituting the cleaning device 16 are kept in non-contact with the image forming body 1 during the execution of the image forming process. When the final multicolor toner image is formed on the body 1,
The cleaning blade 17 and the fur brush 18 come into contact with the image forming body 1. After the toner remaining on the image forming body 1 after the transfer of the toner image is scraped off by the cleaning blade 17, the cleaning blade 17 separates from the image forming body 1 and the fur brush 18 moves from the image forming body 1 with a slight delay. Leave. When the cleaning blade 17 separates from the image forming body 1, the fur brush 18
This is for removing the toner remaining on the top.
The toner scraped by the cleaning blade 17 is efficiently collected by the toner collecting roller 19.

FIG. 2 is an explanatory diagram showing an example of the laser optical system. In this figure, 20 is a semiconductor laser transmitter, 21 is a rotary polygon mirror, and 22 is an fθ lens.

In such an image forming apparatus, an optical mark is formed on the image forming body 1 for alignment of each surface image, and the mark is read by an optical sensor or the like, so that exposure is started. It is preferable to do so.

FIG. 3 is a schematic view showing an example of a developing device of a multicolor image forming apparatus which can be used in the method of the present invention. In this figure, 23 is a developing sleeve that rotates in the direction of the arrow, and 24 is a magnetic roll that rotates in the opposite direction to the developing sleeve 23.
4 constitute a developer carrying carrier. The magnetic rolls 24 may rotate in the same direction as the developing sleeve 23, or may be fixed to each other. The developing sleeve 23 is preferably made of a non-magnetic material such as copper, aluminum, and magnesium.
Is made rough by sand blasting or the like as necessary, and is made to have a high resistance as necessary. The magnetic roll 24 has a configuration in which N poles and S poles are alternately arranged along the inner periphery of the developing sleeve 23, and the number of these magnetic poles is appropriately selected within a range of 4 to 20. It is preferable that the number be 6 or more in order to convey the image uniformly.
The strength (magnetic flux density) of the magnetic pole in the development region K of the magnetic roll 24 is set to 500 to 1500 gauss. 25
Reference numeral denotes a plate-shaped developer amount regulating body made of an elastic body, which is pressed against and held by the developing sleeve 23 on one surface side near the front end thereof. The pressing force applied to the developing sleeve 23 by the developer amount regulating body 25 is preferably set in the range of 0.1 to 5 g / cm. A 500 μm thin layer of developer is formed. Reference numeral 26 denotes a first stirring member, and 27 denotes a second stirring member. These members are structured so as to rotate so that the stirring areas overlap without colliding in opposite directions as indicated by arrows. 28 is a toner supply container, 29 is a toner supply roller, 30 is a developer pool, 3
1 is a bias power supply.

In this developing device, the developer reservoir 30
The developer inside is sufficiently stirred and mixed by the stirring members 26 and 27, and the developer is transferred to the surface of the developing sleeve 23 by the transport force of the developing sleeve 23 rotating in the direction of the arrow and the magnetic roll 24 rotating in the opposite direction. Adheres to The thickness of the developer adhered to the surface of the developing sleeve 23 is regulated by the developer amount regulating body 25 to form a thin layer. The developer layer thinned by the developer amount regulating body 25 is kept in a non-contact state with the electrostatic latent image formed on the image forming body 1 rotating in the direction of the arrow in the developing region K. Transported to In the developing area K, the gap between the image forming body 1 rotating in the direction of the arrow and the developing sleeve 23 is larger than the particle diameter of the developer, and is set within a range that enables non-contact reversal development under an oscillating electric field. And usually within a range of 100 to 1000 μm. Then, in the development region K, the frequency is usually 100 Hz to 10 kHz by the bias power supply 31.
z, preferably 0.2 to 3.0 kV at 1 to 5 kHz
(PP), preferably 1.0 to 2.0 kV (PP)
And a DC bias close to the latent image potential is applied to remove fog. With the oscillating electric field formed in this manner, the electrostatic latent image on the image forming body 1 is developed by the thin developer layer, thereby forming a toner image.

[0049]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. In the following, “parts” indicates “parts by weight”.

The following were used as the binder resin and the colorant constituting the colored particles, and as the carrier. (1) Binder resin Binder resin 1: Polyester resin Binder resin 2: Styrene-acrylic resin (2) Colorant (pigment) Yellow pigment: C.I. I. Pigment Yellow 17 magenta pigment: C.I. I. Pigment Red 122 Cyan Pigment: C.I. I. Pigment Blue 15: 3 (3) Carrier A resin-coated carrier in which the surfaces of spherical ferrite particles (average particle size: 48 μm) are coated with a styrene-acrylic resin.

Further, in the following Examples and Comparative Examples, the measurement of the maximum volume distribution particle size, the measurement of the triboelectric charge, and the measurement of the surface coverage were performed according to the methods described above.

Example 1 100 parts of binder resin 1 and 3.5 parts of cyan pigment were melt-kneaded, pulverized, and classified to obtain colored particles A having a weight average particle size of 8.5 μm. . According to the formulation shown in Table 1, with respect to 100 parts of the colored particles A,
Hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle size: 75 nm, triboelectric charge with iron powder:
2.1 parts of hydrophobic titanium oxide surface-treated with a silane coupling agent (maximum volume distribution particle size: 30 nm, triboelectric charge amount with iron powder: 2.0 μC / g)
The toner is prepared by adding 0.7 parts by weight (absolute value of the charge amount ratio: 0.10), and the toner and the carrier are mixed at a ratio where the toner concentration becomes 7.0% by weight. Was prepared.

Example 2 100 parts of the binder resin 1 and 4.0 parts of the magenta pigment were melt-kneaded, pulverized and classified to obtain colored particles B having a weight average particle size of 8.5 μm. . According to the prescription shown in Table 1, 100 parts of the colored particles B were added to hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle size: 50 nm, triboelectric charge with iron powder: -40 μC / g). ) 1.4 parts and hydrophobic titanium oxide surface-treated with a silane coupling agent (maximum volume distribution particle size 30 nm, triboelectric charge amount with iron powder: 2.0 μC /
g) was added to prepare a toner (absolute value of charge amount ratio: 0.05), and developer B of the present invention was produced in the same manner as in Example 1 except that this toner was used. did.

Example 3 100 parts of binder resin 1 and 3.5 parts of cyan pigment were melt-kneaded, pulverized and classified to obtain colored particles C having a weight average particle size of 8.5 μm. . According to the formulation shown in Table 1, with respect to 100 parts of the colored particles C,
Hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle size 50 nm, triboelectric charge with iron powder:
−40 μC / g) and 1.4 parts of hydrophobic titanium oxide (maximum volume distribution particle size: 12 nm, triboelectric charge amount with iron powder: 10 μC)
/ G) to prepare a toner (absolute value of charge amount ratio: 0.25). The same procedure as in Example 1 was repeated except that this toner was used. Manufactured.

Example 4 100 parts of the binder resin 1 and 6.0 parts of the magenta pigment were melt-kneaded, pulverized and classified to obtain colored particles D having a weight average particle size of 8.7 μm. . According to the prescription shown in Table 1, 100 parts of the colored particles D were treated with hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle size: 75 nm, triboelectric charge with iron powder: -20 μC / g). ) 2.1 parts and hydrophobic titanium oxide (maximum volume distribution particle size 50 nm, triboelectric charge with iron powder: 0)
(C / g) (1.17 parts) to prepare a toner (absolute value of the charge amount ratio: 0), and the developer D of the present invention was produced in the same manner as in Example 1 except that this toner was used. did.

Example 5 100 parts of binder resin 1 and 6.0 parts of yellow pigment were melt-kneaded, pulverized and classified to obtain colored particles E having a weight average particle size of 8.6 μm. . According to the formulation shown in Table 1, 100 parts of the colored particles E were added to hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle size: 75 nm, triboelectric charge with iron powder: triboelectric charge: − 3.15 parts of 20 μC / g) and hydrophobic titanium oxide surface-treated with a silane coupling agent (maximum volume distribution particle size 30 nm, triboelectric charge amount with iron powder: 0)
μC / g) to prepare a toner (absolute value of the charge amount ratio: 0), and the developer E of the present invention was produced in the same manner as in Example 1 except that this toner was used. did.

Example 6 100 parts of binder resin 1 and 6.0 parts of yellow pigment were melt-kneaded, pulverized and classified to obtain colored particles F having a weight average particle size of 8.6 μm. . According to the formulation shown in Table 1, 100 parts of the colored particles F were added to hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle size: 75 nm, triboelectric charge with iron powder: -20 μC / g). ) 2.1 parts and a hydrophobic titanium oxide surface-treated with a silane coupling agent (maximum volume distribution particle size 30 nm, triboelectric charge amount with iron powder: -10 μC /
g) was added to prepare a toner (absolute value of charge amount ratio: 0.50), and developer F of the present invention was produced in the same manner as in Example 1 except that this toner was used. did.

Example 7 100 parts of binder resin 2 and 5.0 parts of magenta pigment were melt-kneaded, pulverized and classified to obtain colored particles G having a weight average particle size of 8.6 μm. . According to the formulation shown in Table 1, 100 parts of the colored particles G were added to hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle size: 75 nm, triboelectric charge with iron powder: -20 μC / g). ) 2.1 parts and hydrophobic titanium oxide surface-treated with a silane coupling agent (maximum volume distribution particle size 30 nm, triboelectric charge amount with iron powder: 2.0 μC /
g) was added to prepare a toner (absolute value of charge amount ratio: 0.10), and developer G of the present invention was produced in the same manner as in Example 1 except that this toner was used. did.

Example 8 100 parts of the binder resin 1 and 3.5 parts of the cyan pigment were melt-kneaded, pulverized and classified to obtain colored particles H having a weight average particle size of 8.5 μm. . According to the formulation shown in Table 1, with respect to 100 parts of the colored particles H,
Hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle size: 75 nm, triboelectric charge with iron powder:
2.1 parts of hydrophobic alumina surface-treated with a silane coupling agent (maximum volume distribution particle size: 30 nm, triboelectric charge amount with iron powder: 3.0 μC / g).
6 parts were added to prepare a toner (absolute value of the charge amount ratio: 0.15), and a developer H of the present invention was produced in the same manner as in Example 1 except that this toner was used.

Example 9 100 parts of binder resin 1 and 5.0 parts of yellow pigment were melt-kneaded, pulverized and classified to obtain colored particles I having a weight average particle size of 8.5 μm. . According to the formulation shown in Table 1, 100 parts of the colored particles I were treated with hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle size: 50 nm, triboelectric charge with iron powder: -40 μC / g). ) And hydrophobic alumina surface-treated with a silane coupling agent (maximum volume distribution particle size: 30 nm, triboelectric charge with iron powder: 3.0 μC /)
g) to obtain a developer I of the present invention in the same manner as in Example 1 except that the toner was prepared by adding 0.4 parts by weight (absolute value of the charge amount ratio 0.075). did.

[Comparative Example 1] 100 parts of binder resin 1 and 4.0 parts of magenta pigment were melt-kneaded, pulverized and classified to obtain colored particles a having a weight average particle size of 8.5 µm. . According to the recipe shown in Table 2, 100 parts of the colored particles a were treated with a hydrophobic titanium oxide surface-treated with a silane coupling agent (maximum volume distribution particle size 30 nm, triboelectric charge amount with iron powder: 2.0 μC). / G) 0.7 parts and hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle diameter 16 nm, triboelectric charge amount with iron powder: -200 μC /
g) was added to prepare a toner (absolute value of charge amount ratio: 100), and a developer a for comparison was produced in the same manner as in Example 1 except that this toner was used.

Comparative Example 2 100 parts of the binder resin 1 and 4.0 parts of the magenta pigment were melt-kneaded, pulverized and classified to obtain colored particles b having a weight average particle size of 8.5 μm. . According to the prescription shown in Table 2, 100 parts of the colored particles b were added to hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle size: 75 nm, triboelectric charge amount with iron powder: -20 μC / g) ) 2.1 parts and hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle size: 8 nm, triboelectric charge amount with iron powder: -250 μC / g)
0.22 parts was added to prepare a toner (the absolute value of the charge amount ratio was 12.5), and a developer b for comparison was produced in the same manner as in Example 1 except that this toner was used.

Comparative Example 3 100 parts of the binder resin 1 and 4.0 parts of the magenta pigment were melt-kneaded, pulverized and classified to obtain colored particles c having a weight average particle size of 8.6 μm. . According to the prescription shown in Table 2, 100 parts of the colored particles c were added to a hydrophobic titanium oxide surface-treated with a silane coupling agent (maximum volume distribution particle size: 150 nm, triboelectricity with iron powder: -20 μC / g) 3.8 parts of hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle size 30 nm, triboelectric charge amount with iron powder: -20 μC /
g) was added to prepare a toner (absolute value of charge ratio: 1.0), and a developer c for comparison was produced in the same manner as in Example 1 except that this toner was used. did.

Comparative Example 4 100 parts of the binder resin 1 and 4.0 parts of the magenta pigment were melt-kneaded, pulverized and classified to obtain colored particles d having a weight average particle size of 8.5 μm. . According to the formulation shown in Table 2, 100 parts of the colored particles d were treated with hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle size: 16 nm, triboelectric charge with iron powder: -200 μC / g). ) 0.45 part and hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle size 8 nm, triboelectric charge with iron powder: -250 μC /
g) was added to prepare a toner (absolute value of charge amount ratio: 1.25), and a developer d for comparison was produced in the same manner as in Example 1 except that this toner was used. did.

Comparative Example 5 100 parts of the binder resin 1 and 4.0 parts of the magenta pigment were melt-kneaded, pulverized and classified to obtain colored particles e having a weight average particle size of 8.6 μm. . According to the formulation shown in Table 2, 100 parts of the colored particles e were added to hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle size: 75 nm, triboelectric charge amount with iron powder: -20 μC / g). ) 2.1 parts and hydrophobic titanium oxide surface-treated with a silane coupling agent (maximum volume distribution particle diameter 75 nm, triboelectric charge amount with iron powder: -15 μC /
g) to prepare a toner by adding 1.75 parts of the toner (absolute value of charge amount ratio 0.75), and using the same toner as in Example 1 to produce a developer e for comparison. did.

Comparative Example 6 100 parts of the binder resin 1 and 4.0 parts of the magenta pigment were melt-kneaded, pulverized and classified to obtain colored particles f having a weight average particle size of 8.5 μm. . According to the prescription shown in Table 2, 100 parts of the colored particles f were added to a hydrophobic alumina surface-treated with a silane coupling agent (maximum volume distribution particle size: 30 nm, triboelectric charge amount with iron powder: -200 μC / g). ) 0.6 part and hydrophobic silica surface-treated with a silane coupling agent (maximum volume distribution particle diameter 16 nm, triboelectric charge amount with iron powder: 3.0 μC /
g) was added to prepare a toner (absolute value of the charge amount ratio: 0.015), and a developer f for comparison was produced in the same manner as in Example 1 except that this toner was used. .

<Actual photo test 1> Developers A to I of the present invention
For each of (Examples 1 to 9) and comparative developers a to f (Comparative Examples 1 to 6), a non-contact type multicolor image forming apparatus “DC9028” (manufactured by Konica Corporation) was used. A color toner image (a single color of yellow, magenta, or cyan) is formed on the photoreceptor, the color toner image is transferred to a transfer paper, and then fixed to form a single-color image. Then, the following items were evaluated.
The actual test was performed under normal temperature and normal humidity environment (temperature 20 ° C,
(55% relative humidity).

[Evaluation Items] (1) Time-dependent change in the amount of developed toner (stability of image density)
A solid toner image of 50 mm × 50 mm is formed, and this toner image is collected with an adhesive tape before being subjected to a transfer process, and the difference in tape weight before and after collection (toner weight W) is used to determine the amount of developing toner per unit area [W / 10 (mg / cm ² )].

(2) Temporal change of transfer rate (stability of image density) At the initial stage of image formation and after 30,000 times, a solid toner image similar to the above is formed on a photoreceptor, and this solid toner image is transferred onto a transfer paper. After the transfer, the toner weight W ′ remaining on the photoreceptor after the transfer was measured, and the transfer rate was determined by the following equation. Transfer rate = [(W−W ′) / W] × 100 (%)

(3) Fog (improper image caused by scattering of toner) The density of the non-image portion was measured every 100 times using a Macbeth densitometer “Macbeth RD918” (manufactured by Macbeth), and the density was 0.02 or more. The point at which fog occurred was regarded as fogging, and the number of copies at that point was measured.

(4) White Streak (Image Defect Caused by Contamination of Charged Wire) The formed solid copy image is visually observed, and the presence or absence of white streak caused by discharge unevenness due to contamination of the charged wire is examined. The number of copies at the time of occurrence of was observed.

The above evaluation results are shown in Tables 1 and 2 below. In Table 1-2, "D _L" represents the maximum volume distribution diameter of the large-diameter inorganic fine particles L a (nm), "D _S" is
The maximum volume distribution particle size of the small particle size inorganic fine particles S represents (nm). "Q _L" represents the quantity of triboelectricity of the large-diameter inorganic fine particles L and iron powder, "Q _S" represents the quantity of triboelectricity of the small-diameter inorganic fine particles S and iron powder.

[0073]

[Table 1]

[0074]

[Table 2]

<Actual photo test 2> The multicolor image forming apparatus "DC9028" (manufactured by Konica Corporation) was used in combination with the developers of the present invention in accordance with the prescription shown in Table 3 below.
The yellow, magenta and cyan colors on the photoreceptor
A multicolor toner image in which color toner images are superimposed is formed, the multicolor toner image is collectively transferred to transfer paper, and then fixed and a multicolor image is formed over 30,000 times. did.

[0076]

[Table 3]

As a result, a multicolor copy image having a faithful color tone with respect to the original image can be obtained at the initial stage of image formation and at the time of 30,000 times of formation, regardless of any of the above combination prescriptions. No occurrence of the image density or a decrease in the image density over time was observed.

[0078]

According to the developer for an electrostatic image of the present invention, the change of the amount of the developing toner with time is small, and the excellent developing property and the excellent transferring property are stably exhibited. There is no occurrence of a decrease in image density due to a decrease in image density, a decrease in image density due to transfer failure, or a defect in image due to a decrease in fluidity. Therefore, by repeating the non-contact development on the image forming body, a plurality of color toner images having different colors are formed on the image forming body in a superimposed manner, and the superposed plural color toner images are formed. When applied to a multicolor image forming method for batch transfer, it is possible to stably form a multicolor image having excellent image quality in a color tone faithful to a document over a long period of time.

According to the multicolor image forming method of the present invention, it is possible to stably form a multicolor image having excellent image quality in a color tone faithful to a document for a long period of time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a multicolor image forming apparatus that can be used in the multicolor image forming method of the present invention.

FIG. 2 is an explanatory diagram illustrating an example of a laser optical system.

FIG. 3 is a schematic diagram illustrating an example of a developing device of a multicolor image forming apparatus that can be used in the multicolor image forming method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image forming body 2 Image input part 3 Illumination light source 4 Color separation filter 5 Reflection mirror 6 Lens 7 CCD image sensor 8 Image processing part 9 Multicolor original 10 Laser optical system 11 Negative charging charger 12 Transfer corona discharger 13 Separation Electrode 14 Fixing unit 15 Static eliminator before cleaning 16 Cleaning device 17 Cleaning blade 18 Fur brush 19 Toner collecting roller 20 Semiconductor laser oscillator 21 Rotating polygon mirror 22 fθ lens 23 Developing sleeve 24 Magnetic roll 25 Developer amount regulating body 26 First stirring Member 27 Second stirring member 28 Toner supply container 29 Toner supply roller 30 Developer reservoir 31 Bias power supply A Yellow toner developing device B Magenta toner developing device C Cyan toner developing device D Black toner developing device K Development area L laser Beam P recording paper

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Ryuji Kitani 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Corporation (56) References JP-A-3-203743 (JP, A) JP-A-4-204749 ( JP, A) JP-A-62-174772 (JP, A) JP-A-2-126266 (JP, A) JP-A-4-348354 (JP, A) JP-A 4-204658 (JP, A) JP-A-5-119519 (JP, A) JP-A-3-110580 (JP, A) JP-A-3-100660 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9 / 08

Claims (2)

(57) [Claims] 1. A method according to claim 1, wherein the colored particles containing at least a colorant and a binder resin include large-sized inorganic fine particles L and small-sized inorganic fine particles S
And a carrier obtained by externally adding two or more types of inorganic fine particles containing: the large-sized inorganic fine particles L and the small-sized inorganic fine particles S
Satisfies the following conditions (1) to (4): <Conditions> The maximum volume distribution particle size of the large particle size inorganic fine particles L is D _L (n
When the m), the maximum volume distribution diameter of 50 ≦ D _L <small-diameter inorganic fine particles S that is 0.99 D _S (n
When the _{m), 10 ≦ D S ≦} 50 maximum volume distribution diameter D to the maximum volume distribution diameter D _S that is
The ratio of _L is 1.5 ≦ (D _L / D _S ) <5.0 The amount of triboelectric charge between the large-diameter inorganic fine particles L and the carrier material is Q _L , and the small-diameter inorganic fine particles S and the carrier material are triboelectrification amount when the Q _S, triboelectric charge ratio of the triboelectric charge quantity Q _S for _{Q L (Q S / Q L} ) of the large-diameter inorganic fine particles that absolute value is 0 to 0.5 and The amount of L added is
The surface coverage of the colored particles by the particles L is 10 to 60%.
Amount of the inorganic fine particles S having a small particle diameter.
The surface coverage of the colored particles by the particles S is 5 to 40%.
The total amount of the large-sized inorganic fine particles L and the small-sized inorganic fine particles S
The amount of addition is such that the surface coverage of the colored particles is 90%.
The amount must be 2. The method according to claim 1, wherein the developer layer formed on the developer carrier is transported to a developing area in a state where the developer layer is not in contact with the image forming body, and an image is formed under an oscillating electric field obtained by applying an AC bias. By repeatedly developing the electrostatic latent image on the formed body, a plurality of color toner images having different colors are superimposed on the image formed body, and then the plurality of color toner images are collectively transferred. In the multicolor image forming method including the step of performing, each developer for forming the plurality of color toner images,
A method for forming a multicolor image, comprising the electrostatic image developer according to claim 1.