JP2003076059A - Toner for developing electrostatic image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease waste toner, to realize higher durability of developer and to make the rise of the electrification of supplied toner excellent. SOLUTION: The size of a main body device having at least two or more developing units, connected to a network and used for the printing of an electrophotographic system having size <=2,000 mm which is the size of the total sum of length, width and height. The toner for developing an electrostatic image is characterized in that silica particulates exist on the surface of toner used in the main body device and are stuck to the toner by a force of >=100 nN.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic latent image formed in an electrophotographic method, an electrostatic recording method or an electrostatic printing method, and more particularly to charge control.

[0002]

2. Description of the Related Art As IT technology is used as an important technology worldwide, PCs (P
The use of C) has become commonplace, and the time has come for each individual. A document created by a PC becomes shared information for many people by being distributed and viewed as electronic data, or printed or copied as paper information. As a printer or a copying machine generally used for outputting, distributing, and circulating as paper information in such an office, a network type is used so that it can be output from all PCs. Most of the electronic data output devices used as the network type are of the electrophotographic type, and waste toner is generated in the electrophotographic process due to its characteristics.

On the other hand, in the two-component development, which is a developing system used in many electrophotographic systems, the carrier for imparting the charging property to the toner used for the development has a life,
It had to be collected, reclaimed or discarded. Once played,
Although it is friendly to the environment, it is expected to become a major problem as global environmental pollution when it is discarded. Many countries and companies are making various efforts to protect the global environment. They are, for example,
Resource recycling, pollution-free, zero waste, energy saving,
Measures against global warming, clean energy, etc. can be mentioned.

From such a background, an electronic data output device which is friendly to the global environment is desired in the future. One method that does not use a carrier is a one-component developing method, but a large amount of waste toner remains after transfer (two-component developing is the same), which is not preferable for the environment. Also,
There is also a problem that it is not suitable for high-speed printing. From the above points, there is a demand for a high-speed output device of electronic data which is friendly to the global environment and will become an important part of the IT industry in the future.

In recent years, as a high-speed output device, a conventional monochrome machine is shifting to a full-color machine. In a full-color machine, since monochrome use and full-color use are often used together, the area ratio may vary greatly depending on the document to be printed. With normal text information alone, there are about 7
While the area ratio is about%, the material used for photographs and presentations may have an area ratio of 80% or more. The large difference in the area ratio depending on the output image means that the amount of toner used changes depending on the image. The change in the amount of toner used at one time means that the amount of toner replenished in the developing device differs depending on the image. In other words, the amount of toner changes greatly with respect to a fixed amount of carrier that is charged, and even if it changes, the charging characteristics of the replenishment toner must always be maintained in the same state. However, it has been difficult to maintain the same state until now. This is because the carrier characteristics that give the toner charge change with time. This shortens the life of the carrier and is not environmentally friendly.

The cause of shortening the carrier life is as follows:
For example, the toner composition may adhere to the carrier to impair the original charging performance of the carrier. Examples of the toner composition that adheres to the carrier include additives such as silica, titania, or zinc stearate present on the toner surface, a resin that constitutes the toner base, wax, and a charge control agent. Japanese Patent Application Laid-Open No. 9-274368 describes that the additive is prevented from adhering to the developer carrying member from the charging performance of the additive and the toner, but the adhering to the carrier is not clear. Further, Japanese Patent Laid-Open No. 2000-267354 describes that an additive is fixed on the surface of the toner by mixing the additive at a temperature higher than room temperature when the additive is mixed with the toner. However, some toner particles can fix the additive due to the temperature effect, but it is impossible to make the additive existing state in all toners the same. In addition, JP 2000-2
Japanese Patent No. 67333 attempts to immobilize the additives by using ultrasonic waves, but it is difficult to prevent all the additives from being transferred to the carrier by keeping all the additives in the same state. Also,
According to the methods described in JP-A-3-76035 and JP-A-7-92727, there is a toner in which a half additive is buried and a toner in which half additive is not buried, and sufficient durability cannot be obtained.

On the other hand, regarding the charging property of the replenishment toner, JP-A-10-221937 defines the shape of the screw in the developing unit. The desired effect is obtained with some toner and carrier combinations, but is not satisfactory with all toner and carrier combinations. In particular, if the additive present on the toner surface is not present in a desired state, it is difficult to obtain sufficient charging characteristics.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above prior arts, and its object is to reduce the waste carrier, and another object is to improve the durability of the developer. To improve the charging of the replenishment toner.

[0009]

As a result of earnest research, the present inventors have found that silica particles are present at least on the toner surface.
Since the silica fine particles adhere to the toner with a force of 100 nN or more, the waste carrier can be reduced, a developer having high durability can be manufactured, and the charging performance of the replenishment toner can be improved. It was

That is, the above-mentioned problem is solved by (1) of the present invention.
"A network with at least two development units
Main unit used for electrophotographic printing that can be connected to a printer
The total size of vertical, horizontal and height is 2000.
mm or less, on the surface of the toner used for the main body device
Silica fine particles are present, and the silica fine particles are 100 nN
Electrostatically characterized by adhering to toner with the above force
Toner for package image development ", (2)" When the toner is manufactured
In addition, 1 cm for the toner to which the additive is externally added. ^TwoI
Characterized in that it does not apply a force of 11 kgf or more
Toner for developing electrostatic image according to item (1) ", (3)
"The toner having silica fine particles attached to the toner surface is
Shearing force when the toner is compacted with a bulk density of 0.6 or more
Silica particles do not detach from the toner when exposed
The electrostatic image development according to item (1), characterized in that
Toner ", (4)" The toner is mixed with a carrier.
Characterized in that silica does not migrate to the carrier when
The toner for developing an electrostatic charge image according to the item (3),
(5) “Titanium oxide is used as an additive in the toner.
The electrostatic as described in the above item (4), characterized in that
Toner for image development, "(6)" As an additive to the toner
Characterized by the combined use of zinc stearate
The toner for developing an electrostatic charge image according to the item (4) ”,
(7) “For the toner, silica is used in a Henschel mixer.
After mixing, collect it in a bottle once,
The method described in the above item (6) is characterized in that the mixture is put in a mixer.
The toner for developing the electrostatic charge image, ”(8)“ the toner is
When mixing with the Henschel mixer again,
Characterized by pouring air below 40 ° C into the kisa
The toner for developing an electrostatic charge image according to claim 7, '' (9)
"The silica has a primary particle size of 0.04 microns or less
The electrostatic charge image according to the item (1), wherein
Development toner ", (10)" The toner is negatively charged
It is a toner, and the peak of the charge amount distribution in its charge amount
Item (1) above, characterized in that there is only one
Toner for developing electrostatic images ", (11)" Use the toner
Mixed with a carrier to prepare a developer.
Even when the image area is 10% or less
Even if it is more than 60%,
In the distribution of the amount of charge of the toner that exists from the
The value of the black position is more than doubled on the developing sleeve.
The electrostatic charge image expression according to item (1) above.
"Image toner", (12) "The replenishment toner is used as a developer.
Before replenishing, make sure that it is charged to -5 μc / g or more.
The electrostatic charge image developing tool described in the item (11), characterized in that
(13) "The carrier has a volume average particle diameter.
Before 30 μm or more and 70 μm or less
The toner for developing an electrostatic charge image according to item (11), (1
4) “The carrier coat material of the carrier is silicon.
The above-mentioned first characterized in that it is made of resin and acrylic resin.
Toner for developing electrostatic image according to item (11) ", (15)
"As a characteristic of the developer, the toner and the carrier are mixed.
Within 15 seconds, the saturated charge amount may reach 60%.
The electrostatic image development according to item (11), characterized in that
"Toner for".

From the viewpoint of designing an environment-friendly device,
The key words are energy saving, resource saving, space saving, recycling, and long life. As described above, a developer used in a copying machine or a printer is required to have a long life in order to reduce waste. On the other hand, it is desired that the copier and the printer main body are properly arranged in a limited office. For that purpose, it becomes necessary to reduce the space used by the device to save space. If the space used by the equipment is reduced, it is inevitable that the developing unit, the photoconductor, the fixing unit, the cleaning unit, and the like, which constitute the electrophotographic process, must be downsized. For example, if the developing unit is downsized, it is necessary to downsize the developing roller and the developer stirring unit used therein. If these are made smaller, the rising speed of charging will be faster than ever in order to make the toner have an appropriate charging amount.

For that purpose, it becomes necessary to more appropriately present a material for imparting charge as a material constituting the toner in the toner or on the toner surface.
Examples of the material that imparts charge include a charge control agent, a resin, a pigment, and an external additive. For example, in the case of an external additive, if it is not properly present on the toner surface, the charging characteristics may be adversely affected. This is because when the external additive adheres to the toner surface with a weak adhesive force, it transfers to and adheres to the carrier or the developing sleeve to delay the charging start of the toner, or the toner charge amount distribution becomes unfavorable. I have something to do. Therefore, when the total size of the copying machine or the printer is 2000 mm or less, it is necessary that the additive is present on the toner surface.

The total size of copiers and printers is 2,
If it is 000 mm or more, there is a margin for the size of each unit that constitutes the electrophotographic process. Therefore, when focusing on the developing unit, it is not necessary to strictly control the rising characteristics of charging, which is one of the characteristics of the developer.
There is no necessity of prescribing to "force of 100 nN or more of silica particles".

The explanation of "100 nN or more" in the present invention is shown below. The force (F) acting between the toner and silica can be expressed by the following equation (1).

## EQU1 ## F = Fv + (αq ₁ q ₂ / 4πε ₀ r ² ) (1) where the first term Fv on the right side is the Van der Waals force, and the second term on the right side indicates the Coulomb force. α: constant depending on the dielectric constant of the toner q: charge r: toner radius ε ₀ : dielectric constant of vacuum

It is generally known that the adhesive force of the toner acting on the carrier and the photosensitive member is approximately several tens of nN. On the other hand, the size of the additive added to the toner is about three orders of magnitude smaller than that of the toner. If the additive q is about the same as the toner, the force F becomes a large value because the radius of silica is three orders of magnitude smaller than that of the toner. However, experimentally, additives such as silica present on the toner surface are not always present on the toner surface, and a phenomenon in which so-called floating silica migrates to the carrier surface, the inside of the developing device, the photoreceptor surface, etc. Can be seen. It is considered that this is not the case with all additives such as silica, but there is a distribution in the force of adhesion due to the additives, and as a result, some additives such as silica float.

As described above in the section of the prior art, there is a description of the method of immobilizing the additive on the toner surface and the burial. There is no evidence of power. In terms of immobilization and burial, adhesion may be small or large. When actually trying to measure,
There is a distribution in the adhesive force of the additives present on the toner surface,
It was found that the toner adhered to the toner surface with a small adhesive force.

On the other hand, in the present invention, the adhesive force of the additive adhering to the toner surface is clarified, and the force is 100 nN.
By the above, it was possible to develop a highly durable environment-friendly developer. The force can be measured by a separately developed impact force measuring device using an impact method. The basic principle is that toner with additives is mixed with a carrier to prepare a developer, and a force with an acceleration is applied from the back surface of the substrate while the developer is attached to the substrate, and the toner is removed from the carrier. To detach. It is possible to observe the number of toners and additives released due to the difference in acceleration. The toner can be counted with an optical microscope, and the number of the additives can be counted by dispersing them in a liquid. The adhesive force at that time can be measured from the number of detached pieces, the size, and the acceleration.

The measuring method will be described in detail below.
Adhesive force is measured by adhering the fine particles to be measured to the object-to-be-measured carrier having a uniform plane, and moving the carrier at high speed while applying a constant electric field to the particles to form powder. Give any power. Specifically, the object-supporting body is a solid solid material that is regarded as a rigid body, and moves and stops at high speed. By moving the carrier in the direction perpendicular to the carrier surface, the powder adhered to the carrier plane can be accelerated in the direction perpendicular to the carrier plane. The force acting on the powder can be obtained by obtaining the acceleration due to this high-speed displacement and the mass of the powder. The adhesive force of the particles can be obtained by detaching the particles from the supporting surface at various accelerations and counting the number of particles before and after the detachment. Further, when the flat plate and the particles are triboelectrically charged, or when the flat plate is regarded as a conductor substantially, the electrostatic attractive force between the flat plate and the particles cannot be ignored. This is because the electrostatic adhesion force reaches farther than other proximity forces such as van der Waals or liquid bridging force, as described above.
This is because the particles that have once desorbed may be pulled back to the flat plate again due to the image-induced force induced by the counter-charge of the particles or the charge of the particles. Therefore, desorption of the particles is performed under a constant electric field. As a result, the charged particles are quickly desorbed from the supporting surface, and the deprived particles can be specified by observing the supporting surface before and after desorption. In order to perform the measurement accurately, the electric field needs to be constant during the high-speed displacement of the object carrier, and the particles are preferably carried in the electrodes held in parallel.

It has been found that the performance can be further improved by not applying a force of 11 kgf or more per cm ² to the externally added toner when the toner is produced. The force applied during toner production is 1 cm
It is preferable that a force of 11 kgf or more per ² is not applied, and the lower limit is preferably 0.1 kgf. If the force is less than or equal to the lower limit, the manufacturing cost will be significantly increased, which is substantially impossible. When a force of 11 kgf or more per 1 cm ² is applied to the toner,
This is because it was found that even if silica adheres to the toner with a force of 100 nN or more, the target toner cannot be obtained because the silica is detached during the toner filling process, the conveying process, and the like.

As described above, the additive added to the toner adheres to the toner with a certain force or more to obtain the intended toner. More preferably, it has been found that a higher performance toner can be obtained because the additive does not detach from the toner when an external force is applied. This means that it is important that the adhesive force does not separate from the external force even if it exceeds a certain value.

Further, this can be obtained also by the fact that the silica fine particles adhered to the surface of the toner does not detach from the toner when the toner is subjected to a shearing force in a compacted state having a bulk density of 0.6 or more. There was found.
The silica fine particles adhering to the surface of the toner have no problem in charging performance as long as they do not move to the carrier even if they are detached from the toner. However, it has been found that the transfer of the carrier makes the charge control of the toner unstable. In the present invention,
It was also found that the effect is further improved by using titanium oxide or zinc stearate as an additive in addition to the silica for charge control.

The above-mentioned toner can be manufactured by various methods, but it can be manufactured more effectively by mixing the toner with silica in a Henschel mixer, collecting the toner once in a bottle, and then again applying it to the Henschel mixer. is there. Further, when the mixture is mixed in the Henschel mixer again, the effect can be enhanced by flowing air at 40 ° C. or lower into the Henschel mixer.

The effect of the silica is enhanced when the primary particle diameter is 0.04 micron or less.

Further, in the toner obtained by the above-mentioned method, when a developer is prepared by mixing with a carrier and an image is produced by this developer, even if the image area is 10% or less, it is 60% or more. Even in such a case, it is possible to make the peak position value of the charge amount distribution of the replenishment toner and the charge amount distribution of the toner existing from the beginning more than twice as great on the developing sleeve.

In order to further improve the effect of the above-mentioned contents, it is possible to make the amount of pre-charge of the replenishment toner to be replenished to the developer to be -5 μc / g or more.

[0026]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but these are only one aspect of the present invention and are not limited thereto. [Example 1] 50 parts by weight of a low molecular weight polyester resin, 50 parts by weight of a high molecular weight styrene acrylic resin, 5 parts by weight of carbon black, 5 parts by weight of carnauba wax, and 1 part by weight of a charge control agent E-84 were mixed by a conventional kneading method. After kneading by the method, followed by rolling and cooling, the coarsely pulverized toner was pulverized with a jet mill, and finally, a toner having a volume average particle diameter of 7.2 μm and a number average particle diameter of 6.8 μm was obtained by an air stream classifier. . Similarly, color toners were obtained by changing the pigments for magenta, cyan, and yellow.

Next, 0.5 part by weight of titania and 0.5 part of zinc stearate are added to 100 parts by weight of each color toner obtained.
A part by weight was added and the mixture was mixed twice for 1 minute with a Henschel mixer. A mixer tank capacity of 100 L was used, and mixing processing was performed at a rotation speed of 1000 rpm. After that, 2 parts by weight of silica was added and mixed for 1 minute three times. Transfer the obtained toner to another tank once,
It was again charged into the Henschel mixer, and the treatment was carried out for 3 minutes. It was possible to produce 50 kg of toner at one time. The adhesive force between the toner and silica was 103 nN. The force applied to the toner at the time of manufacture was 8 kgf per cm ² .

Using the toner thus obtained, a Ricoh color printer Ipsio 8000 without an oil coating mechanism is used.
The image formation was carried out. Images with good fine lines and solid images could be formed. When the transfer rate was measured, it was 98%. Further, the life of the developer did not need to be replaced up to 250K sheets. The rise of charge was good, and no background stain occurred even when toner was replenished under high-speed printing conditions.

[Second Embodiment] In the first embodiment, 50 k at a time
When g toner was manufactured, 100 kg of toner was manufactured at one time. The adhesion between the toner and silica was 110 nN. The force applied to the toner during manufacturing was 10 kgf per cm ² . When images were printed out in the same manner as in Example 1, fine lines and solid images could be formed. When the transfer rate was measured, it was 98%. Further, the life of the developer did not need to be replaced up to 250K sheets. The rise of charge was good, and no background stain occurred even when toner was replenished under high-speed printing conditions.

Comparative Example 1 A toner was manufactured in the same manner as in Example 1. The method of mixing the additives was different from that of Example 1, and 500 kg was manufactured at one time. Adhesion between toner and silica is 88n
It was N. The force applied to the toner during manufacturing is 1 cm ²
It was 13 kgf. Images were printed in the same manner as in Example 1. Images with good fine lines and solid images could be formed. When the transfer rate was measured, it was 63%.
Further, the life of the developer is up to 50K sheets, and the developer needs to be replaced. Due to the poor rise of charging, scumming occurred from 10K under high temperature and high humidity environment. Also, at 50K, scumming occurred even in normal use.

[0031]

As is clear from the detailed and specific description above, by appropriately controlling the existence state of the external additive added to the toner, the charging rise at the time of toner replenishment is good, and It was possible to obtain a toner capable of achieving a highly durable developer that does not generate stains.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akihiro Koban             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Shinichi Kuramoto             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Minoru Masuda             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Kazuhiko Umemura             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F term (reference) 2H005 AA08 AB10 CA30 CB07 CB13                       EA05 EA10

Claims (15)

[Claims] 1. The size of the main body apparatus used for electrophotographic printing capable of connecting to a network having at least two developing units is 2000 mm or less in total length, width and height. A toner for developing an electrostatic charge image, characterized in that silica particles are present on the surface of the toner used in the main body device, and the silica particles adhere to the toner with a force of 100 nN or more. 2. The electrostatic charge image developing device according to claim 1, wherein when the toner is manufactured, the additive does not apply a force of 11 kgf or more per 1 cm ² to the externally added toner. toner. 3. The toner having silica fine particles adhered to the surface of the toner is characterized in that the silica fine particles are not detached from the toner when a shearing force is applied in a compacted state of the toner having a bulk density of 0.6 or more. Item 1. The toner for developing an electrostatic image according to Item 1. 4. The toner for developing an electrostatic charge image according to claim 3, wherein silica does not migrate to the carrier when the toner is mixed with the carrier. 5. The toner for developing an electrostatic charge image according to claim 4, wherein titanium oxide is used as an additive in the toner. 6. The toner for developing an electrostatic charge image according to claim 4, wherein zinc stearate is also used as an additive in the toner. 7. The toner for developing an electrostatic charge image according to claim 6, wherein the toner is prepared by mixing silica with a Henschel mixer, collecting the toner once in a bottle, and then again using the Henschel mixer. 8. The toner for developing an electrostatic charge image according to claim 7, wherein when the toner is mixed in the Henschel mixer again, air at 40 ° C. or lower is flown into the Henschel mixer. 9. The toner for developing an electrostatic charge image according to claim 1, wherein the silica has a primary particle diameter of 0.04 μm or less. 10. The toner for developing an electrostatic charge image according to claim 1, wherein the toner is a negatively charged toner, and there is only one peak of a charge amount distribution in the charge amount. 11. A developer is prepared by mixing the toner with a carrier, and an image is produced by the developer,
Regardless of whether the image area is 10% or less or 60% or more, the peak position value in the charge amount distribution of the replenishment toner and the charge amount distribution of the toner existing from the beginning are different by more than two times on the developing sleeve. The toner for developing an electrostatic charge image according to claim 1, wherein the toner does not exist. 12. The toner for developing an electrostatic charge image according to claim 11, wherein the replenishment toner is charged to −5 μc / g or more before being replenished with the developer. 13. The toner for developing an electrostatic charge image according to claim 11, wherein the carrier has a volume average particle diameter of 30 μm or more and 70 μm or less. 14. The toner for developing an electrostatic charge image according to claim 11, wherein the carrier coat material of the carrier is made of a silicone resin and an acrylic resin. 15. As a characteristic of the developer, a saturated charge amount of 60 is obtained within 15 seconds after the toner and the carrier are mixed.
%, The toner for developing an electrostatic charge image according to claim 11.