JP2004177423A - Electrostatic charge image developing toner and method for developing electrostatic charge image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide high durability to a developer using a dry toner comprising at least inorganic fine particles, and to improve start-up of electrostatic charge of a replenished toner. <P>SOLUTION: When image formation is carried out with the developer using a dry toner comprising at least inorganic fine particles and 5,000 sheets are outputted, ≥80% of the initial inorganic fine particles remain on the surface of the toner in a developing machine. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a toner for developing an electrostatic image and an electrostatic image developing method used in an electrophotographic method, an electrostatic recording method, and an electrostatic printing method, and more particularly, to a charge control of the toner.
[0002]
[Prior art]
With the use of IT technology as an important technology worldwide, the use of personal computers (PCs) in offices has become common, and the age of individuals has become one. A document created on a PC is distributed and viewed as electronic data, or printed or copied as paper information, and becomes common information for many people. As printers and copiers generally used for outputting, distributing, and circulating paper information in such offices, network-type printers and copiers are used so that all PCs can output the information.
[0003]
Many of such electronic data output devices used as a network type use an electrophotographic type, and in the electrophotographic process, waste toner is generated due to its characteristics. On the other hand, in a two-component developing system used in many electrophotographic systems, a carrier for imparting chargeability to a toner used for development has a life and has to be collected, reproduced, or discarded. If it is recycled, it will be environmentally friendly, but if it is discarded, it is expected that it will pose a serious problem as polluting the global environment.
[0004]
From such a background, a global environment-friendly electronic data output device is desired in the future. As a method that does not use a carrier, there is a one-component development method, but a large amount of waste toner remains after transfer (the same applies to two-component development), which is not preferable for the environment. There is also a problem that it is not suitable for high-speed printing.
[0005]
In recent years, there has been a shift from a conventional monochrome machine to a full-color machine as a high-speed output device. In a full-color printer, monochrome and full-color printers are often used in combination, so that the area ratio may vary greatly depending on the document to be printed. The area ratio of only about 7% with ordinary text information alone may be 80% or more for materials used for photographs and presentations. The fact that the area ratio varies greatly depending on the output image means that the used toner amount varies depending on the image. In addition, the fact that the amount of toner used at one time changes means that the amount of toner supplied into the developing device differs depending on the image. In other words, the amount of toner greatly changes for a fixed amount of carrier to be charged, and it is necessary to always maintain the same charging characteristics of the replenished toner even if it changes. However, it has been difficult to maintain the same state until now. Because the characteristics of the carrier that charges the toner change over time, or the toner itself changes in the developing unit, the state difference from the replenishment toner becomes very large, and the average charge amount is given to the replenishment toner. This is because it is no longer possible. This is a situation in which the life of the toner and the carrier is shortened, and it cannot be said that it is environmentally friendly.
[0006]
The cause of shortening the life of the carrier is that the toner composition adheres to the carrier and hinders the inherent charging performance of the carrier. Examples of the toner composition adhering to the carrier include additives such as silica, titania, and zinc stearate present on the surface of the toner, a resin constituting the toner base, a wax, and a charge control agent.
[0007]
Japanese Patent Application Laid-Open No. 9-274368 (Patent Document 1) describes that the additive is prevented from adhering to the developer carrier from the charging performance of the additive and the toner. I'm not sure. Japanese Patent Application Laid-Open No. 2000-267354 (Patent Document 2) describes that when an additive is mixed with a toner, the additive is mixed at a temperature higher than room temperature to fix the additive on the toner surface. . In this method, some toner particles can fix the additive by a temperature effect, but it is impossible to make the presence state of the additive the same in all toners. Further, Japanese Patent Application Laid-Open No. 2000-267333 (Patent Document 3) discloses that an attempt is made to immobilize an additive using ultrasonic waves. However, also in this case, it is difficult to keep all additives in the same state and prevent the transfer of the additives to the carrier. Further, in the inventions described in JP-A-3-76035 (Patent Document 4) and JP-A-7-92727 (Patent Document 5), a toner in which a half additive is buried and a toner which is not buried exist, and the charge amount is increased. It is difficult to maintain uniformity, and sufficient durability cannot be obtained.
[0008]
On the other hand, Japanese Patent Application Laid-Open No. H10-221937 (Patent Document 6) describes that the shape of a screw in a developing unit is defined for the charging property of a replenishment toner. According to this, although a desired effect can be obtained with a certain combination of toner and carrier, it cannot be satisfied with all combinations of toner and carrier. Particularly when the additive present on the toner surface does not exist in a desirable state, it is difficult to obtain sufficient charging characteristics.
[0009]
[Patent Document 1]
JP-A-9-274368 [Patent Document 2]
JP 2000-267354 A [Patent Document 3]
JP 2000-267333 A [Patent Document 4]
JP-A-3-76035 [Patent Document 5]
JP-A-7-92727 [Patent Document 6]
Japanese Patent Application Laid-Open No. Hei 10-221937
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and has as its object to improve the durability of a developer and to improve the charge build-up of a replenishment toner.
[0011]
[Means for Solving the Problems]
The present inventors have made intensive studies on the above problems, and as a result, have found that the following objects can be achieved by the following means, and have reached the present invention. That is, according to the present invention,
First, in a developer using a dry toner containing at least inorganic fine particles, an image is formed using the developer, and when the 5000 sheets are output, the inorganic fine particles are 80% or more of the initial amount on the toner surface in the developing machine. There is provided a toner for developing an electrostatic image, wherein the toner remains.
[0012]
Secondly, in a second aspect, in the toner for developing an electrostatic image according to the first aspect, when the toner is put in a transparent polypropylene container, the toner does not lower the transmittance of the container to 50% or less. A toner for developing an electrostatic image is provided.
[0013]
Thirdly, according to a third aspect of the present invention, in the toner for developing an electrostatic image according to the first aspect, a coverage of the inorganic fine particles on the toner when the toner is not output is 100% or less. An image developing toner is provided.
[0014]
Fourthly, according to a fourth aspect, in the toner for developing an electrostatic image according to any one of the first to third aspects, the inorganic fine particles are silica having a particle diameter of 0.1 μm or less. A developing toner is provided.
[0015]
Fifthly, in the fifth aspect, in the electrostatic image developing toner according to the first aspect, after the toner is charged with a carrier, the toner is attached to a polycarbonate, and another toner particle is attached to one toner particle. When the distance is approached to 5 μm, a toner for developing an electrostatic charge image is provided, wherein the toner particles repel each other and the toner particles do not adhere to each other.
[0016]
Sixth, a sixth aspect of the present invention provides the toner for developing an electrostatic image according to the first aspect, wherein the toner contains a compound having a melting point of 2% or more and the average charge amount when the compound is 5 μm. The toner for developing an electrostatic image is provided, the value of which is smaller than the absolute value of the average charge amount of the toner by 5 (μc / g).
[0017]
Seventhly, according to a seventh aspect, in the toner for developing an electrostatic charge image according to the sixth aspect, 1000 of the toner particles are arranged on a slide glass, and after being placed at 100 ° C. for 10 minutes in that state, optically Provided is a toner for developing an electrostatic image, wherein the number of toners observed under a microscope is 990 or more.
[0018]
Eighthly, according to the eighth aspect, in the toner for developing an electrostatic image according to the first aspect, after outputting 10,000 sheets using the toner, when the surface composition of the toner is measured by photoelectron spectroscopy, Provided is a toner for developing an electrostatic image, wherein the toner does not contain a substance not contained in the toner.
[0019]
Ninthly, in the ninth aspect, when development is performed by using a toner according to any one of the first to eighth aspects with a developing unit having a developing sleeve, the developing sleeve is a developing sleeve having a cleaning mechanism. An electrostatic image developing method is provided.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
As described above, the present invention provides a dry toner in which at least 80% of the initial amount of the inorganic fine particles remains on the toner surface when 5,000 sheets are output in a developer using a dry toner using inorganic fine particles. It has been found that it is possible to reduce scattering and background dirt. When the state of the additive on the toner surface changes, the charging performance changes, and when new toner is replenished, the charging performance is greatly affected, and the charge amount is reduced. If it is only reduced, only toner scattering is required, but if the charge is reversed, background staining will occur. In such a case, according to the present invention, for example, by immobilizing the additive on the toner surface, excessive stress is not applied to the additive, and the amount of buried is suppressed. This is presumably because many additives remained on the toner surface.
[0021]
In the present invention, the measurement of the residual ratio of the inorganic fine particles remaining on the toner surface is as follows: (1) First, the toner is fixed on a sample stage of a scanning electron microscope (SEM) by a conductive tape. {Circle over (2)} The surface of the toner placed on the sample table is observed with an SEM, and after storing the image in an image file, the toner base and the inorganic fine particles present on the surface are separated by image processing software. {Circle around (3)} The ratio existing on the surface is calculated by software and defined as a residual ratio.
[0022]
To make the residual ratio 80% or more, (1) Add 0.5 parts by weight or more of an additive having a primary particle diameter of 40 nm or more to the toner surface. (2) The inorganic fine particles are immobilized on the toner surface by applying a high shearing force to the inorganic fine particles present on the toner surface (high-speed mixing with a Henschel mixer). (3) The stress applied to the toner by the developing unit in which the toner and the carrier coexist is reduced. Specifically, no magnetic pole is disposed immediately below the doctor blade.
[0023]
When the toner is manufactured, the toner may be put in a transparent polypropylene container such as a transparent polypropylene bag for temporary storage. At this time, it was found that when the inorganic fine particles adhered to the bag surface and the transmittance of the transparent bag was reduced to 50% or less, the background stain increased. When manufacturing a toner, it is necessary to determine the method of mixing the additives and the order of mixing in accordance with the charge control level of the toner. This method differs depending on the base toner and cannot be uniquely determined. However, if the transmittance of the bag does not decrease to 50% or less when the toner is put in the bag made of polypropylene, the toner does not scatter or the background becomes dirty. The transmittance of the transparent polypropylene container is measured by using a spectrophotometer on the container, and the transmittance of the container before the toner is charged is calculated as 100%.
[0024]
In addition, by setting the coverage of the inorganic fine particles present on the toner on the toner at 100% or less, it becomes possible to suppress background contamination. When the coverage of the additive exceeds 100%, excellent charging performance is initially exhibited, but the toner is scattered and the background is stained with time. The coverage of the inorganic fine particles on the toner can be measured by the above-described SEM method.
[0025]
Furthermore, it was also found that when the inorganic fine particles mixed with the toner are silica having a particle size of 0.1 μm or less, appropriate fluidity can be obtained and background stain and toner scattering can be reduced.
[0026]
Further, after the toner is charged with the carrier, only the toner is deposited on the polycarbonate, and when one toner particle is brought closer to a distance of 5 μm to another toner particle, the toner does not repel and adhere to each other. As a result, background contamination and toner scattering were suppressed. When toners that do not repel each other were used, toner scattering increased. The toner and the carrier are charged by a usual method, for example, by mixing with a turbula mixer or the like. To deposit the charged toner on the polycarbonate, an electrode is placed on the back surface of the polycarbonate, developed, and further deposited. After one layer is adhered, the toner is manipulated under a microscope to approach the adjacent toner. This can be performed with a microscope and a fine movement XY stage. If the toner is non-uniform (for example, it occurs when toner having a different adhesion state of the inorganic fine particles is generated in a manufacturing process), the toner does not repel.
[0027]
Recently, low molecular weight compounds such as wax have been used for imparting oilless properties to toners. When the toner contains a compound having a melting point of 2% or more and the compound having the melting point is 5 μm, the absolute value of the average charge amount is 5 (μc / g) smaller than the absolute value of the average charge amount of the toner. Dirt was suppressed. If the charge amount is higher than the charge amount of the toner, it is considered that the melting point holding substance adheres to the carrier or the like, so that the toner cannot have an appropriate charge amount. The average charge amount of the compound having the above melting point is measured by pulverizing the compound to a toner size, mixing this with a carrier, charging the compound, and measuring the charge amount.
[0028]
In order to prevent the charging performance of the toner from deteriorating with time, 1,000 toners were placed on a slide glass, placed in that state at 100 ° C. for 10 minutes, and then observed under an optical microscope. It is also important that the number is 990 or more. When the number of toners becomes 989 or less, the amount of charge decreases with time, which seems to cause background contamination and toner scattering. As a simple method of disposing the toner on the slide glass, the toner is dispersed in water, cast on the slide glass to form a thin film, and the water is evaporated to form a single layer of the toner. At this time, it is not necessary to arrange 1000 pieces exactly, and it is sufficient to arrange 1000 pieces or more and specify 1000 pieces on an image.
[0029]
In the case of the pulverized toner, if the dispersion of the wax is not sufficient, single particles of the wax appear in the toner as the toner. Therefore, the wax is sufficiently dispersed, and the production conditions are set so that the dispersion diameter of the kneaded wax is 1 μm or less in the dispersed state. If it is 1 μm or more, it becomes 989 or less.
[0030]
Further, when the toner which stains the background was examined, it was found that the toner contained a substance not contained in the initial toner when the surface composition of the toner was measured by photoelectron spectroscopy. Therefore, it is also important to prevent substances not included in the initial toner from being included in the toner over time. The substance not included in the initial toner may be that the coat film of the carrier is peeled off and is present on the toner surface, or that the photoreceptor surface is peeled off and remains on the toner surface.
[0031]
Furthermore, it has been found that a mechanism for cleaning the developing sleeve must be provided in the developing unit in order to always keep the charge level of the toner in the same state. If the cleaning is not sufficiently performed, the charge level is reduced.
[0032]
As described above, by controlling the presence state of the external additive added to the toner and combining it well with the charge level of the toner base, the charge build-up at the time of toner replenishment is good, no background contamination occurs, and toner scattering occurs. It was possible to obtain a toner capable of achieving a highly durable developer.
[0033]
【Example】
Next, the present invention will be described in more detail by way of examples. However, the present invention is not limited by the following examples.
[0034]
Example 1
A kneading method using a screw kneader comprising 65 parts by weight of a low molecular weight polyester resin, 30 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. , Followed by rolling and cooling, and then coarsely pulverized toner was pulverized with a jet mill. Finally, a pneumatic classifier was used to obtain a toner having a volume average particle size of 5.2 μm and a number average particle size of 4.9 μm.
Similarly, for magenta, cyan, and yellow, color toners were obtained using only the pigment.
Next, 0.5 part by weight of titania and 0.5 part by weight of silica were added to 100 parts by weight of each of the obtained toners, and the mixture was mixed twice for 1 minute using a Henschel mixer. Thereafter, 0.5 parts by weight of silica was added, and a mixing treatment was performed three times for one minute.
[0035]
Using the obtained toner, an image was formed by a Ricoh color printer Ipsio 8000 without an oil application mechanism. An image with good fine lines and solid images could be formed. The transfer rate was measured to be 98%. Further, the life of the developer did not need to be replaced up to 250K sheets. The rise of the charge was good, the toner was not scattered, and the background was not stained even when the toner was replenished under high-speed printing conditions.
[0036]
SEM confirmed that 95% of the initial amount of the inorganic fine particles remained on the toner surface when 5000 sheets were output. When the produced toner was placed in a polypropylene bag, the inorganic fine particles did not adhere to the inner surface of the bag, and the transmittance of the transparent bag was 80%. The inorganic fine particles used were silica having a particle size of 0.1 μm. High-speed video observation also confirmed that when the toner was charged with a carrier and then deposited on polycarbonate and one toner particle was brought close to another with a distance of 5 μm, the toner repelled and did not adhere to each other. Was done. Further, the coverage of the inorganic fine particles present on the toner on the toner was 95%. In addition, 1000 toners were placed on a slide glass, and after being placed at 100 ° C. for 10 minutes in that state, the number of toners observed under an optical microscope was 999. After outputting 10,000 sheets, the surface composition of the toner was measured by photoelectron spectroscopy. As a result, it was confirmed that the toner did not contain substances that were not included in the initial toner.
[0037]
However, when the toner was manufactured in the same manner as above except that the mixing amount of silica was added by 0.2 part by weight, the transmittance was 40% when the toner was put in a polypropylene bag. . When an image was formed in the same manner as described above, an image having good fine lines and solid images could be formed. The transfer rate was measured to be 90%. However, the life of the developer was 50K sheets. When the toner was replenished, background soiling occurred and toner scattering was observed.
[0038]
Example 2
A kneading method using a screw kneader comprising 65 parts by weight of a low molecular weight polyester resin, 30 parts by weight of a high molecular weight styrene acrylic resin, 5 parts by weight of carbon black, 4 parts by weight of carnauba wax, and 2 parts by weight of a charge control agent E-84. The mixture was cooled by rolling, and then cooled and rolled. The coarsely pulverized toner was pulverized by a jet mill, and finally a toner having a volume average particle size of 5.6 μm and a number average particle size of 4.8 μm was obtained by an airflow classifier.
Similarly, for magenta, cyan, and yellow, color toners were obtained using only the pigment.
Next, 0.5 part by weight of titania and 0.3 part by weight of silica were added to 100 parts by weight of the obtained toners, and the mixture was mixed twice with a Henschel mixer for 1 minute. Thereafter, 0.5 parts by weight of silica was added, and a mixing treatment was performed three times for one minute.
[0039]
Using the obtained toner, an image was formed by a Ricoh color printer Ipsio 8000 without an oil application mechanism. An image with good fine lines and solid images could be formed. The measured transfer rate was 95%. Further, the life of the developer did not need to be replaced up to 270K sheets. The rising of the charge was good, there was no scattering of the toner, and no background smear occurred even when the toner was replenished under high-speed printing conditions.
[0040]
SEM confirmed that 90% of the initial amount of the inorganic fine particles remained on the toner surface when 5000 sheets were output. When the produced toner was placed in a polypropylene bag, the inorganic fine particles did not adhere to the inner surface of the bag, and the transmittance of the transparent bag was 70%. The inorganic fine particles used were silica having a particle size of 0.1 μm. High-speed video observations have shown that when the toner is charged with the carrier, the toner is deposited on the polycarbonate, and when one toner particle has another toner particle approaching a distance of 5 μm, the toner repels and the toner does not adhere to each other. Was. The coverage of the inorganic fine particles present on the toner on the toner was 93%. After 1,000 toners were placed on a slide glass and kept at 100 ° C. for 10 minutes in that state, the number of toners observed under an optical microscope was 996. After the output of 100 million sheets, the surface composition of the toner was measured by photoelectron spectroscopy. As a result, it was confirmed that the toner did not contain substances that were not contained in the initial toner.
[0041]
However, in the above toner production, the toner was produced in the same manner except that the mixing process was performed once by adding 0.6 parts by weight of the additive, and the toner surface of the inorganic fine particles after printing 5,000 sheets was obtained. The residual ratio was 40%. When the image was formed in the same manner as described above, the life of the developer was 40K sheets. When the toner was replenished, background soiling occurred and toner scattering was observed.
[0042]
【The invention's effect】
As described above, according to the toner for developing an electrostatic image of claim 1, when 5000 sheets are output, 80% or more of the initial amount of the inorganic fine particles remains. It is possible to obtain a highly durable developer that does not generate stain and does not cause toner scattering.
[0043]
According to the toner for developing an electrostatic image of claim 2, since the toner does not lower the transmittance of the container to 50% or less when placed in a transparent container made of polypropylene, the developer does not cause toner scattering and background contamination. Can be obtained.
[0044]
According to the toner for developing an electrostatic image according to the third aspect, since the covering ratio on the toner at the time of no output is 100% or less, it is possible to obtain a toner which does not cause toner scattering and background stain not only in the initial stage but also with time. be able to.
[0045]
According to the electrostatic image developing toner of the fourth aspect, since the inorganic fine particles are silica, appropriate fluidity of the toner can be obtained, and background stain and toner scattering can be reduced.
[0046]
According to the toner for developing an electrostatic image of claim 5, when the toner particles are brought close to a predetermined distance, the particles repel each other and the toner does not adhere to each other. It is possible to obtain a toner that does not occur.
[0047]
According to the toner for developing an electrostatic image of claim 6, since the absolute value of the average charge amount of the compound having the melting point is smaller than the absolute value of the average charge amount of the toner by 5 (μc / g), the background stain and the spent Thus, it is possible to obtain a toner capable of suppressing the problem of filming.
[0048]
According to the electrostatic image developing toner of the present invention, the number of toner particles hardly decreases on the slide glass left at 100 ° C. for 10 minutes, so that the charging performance is not deteriorated with time, and the charging of the carrier is not performed. A toner that does not deteriorate the performance can be obtained.
[0049]
According to the toner for developing an electrostatic image of claim 8, since the toner does not contain a substance not included in the initial toner from the measurement of the surface composition of the toner after output of 10,000 sheets, occurrence of a background stain is generated. No developer can be obtained.
[0050]
According to the electrostatic image developing method of the ninth aspect, when the developing is performed using the toner with the developing unit having the developing sleeve, the developing sleeve is a developing sleeve having a cleaning mechanism. And the charge level of the toner can always be kept the same.

Claims (9)

In a developer using a dry toner containing at least inorganic fine particles, an image is formed using the developer, and when the 5000 sheets are output, 80% or more of the initial amount of the inorganic fine particles remains on the toner surface in the developing machine. A toner for developing an electrostatic charge image, comprising: 2. The electrostatic image developing toner according to claim 1, wherein the toner is a toner that does not reduce the transmittance of the transparent container to 50% or less when placed in a transparent polypropylene container. For toner. The toner for developing an electrostatic image according to claim 1, wherein a coverage of the inorganic fine particles on the toner when the toner is not output is 100% or less. 4. The electrostatic image developing toner according to claim 1, wherein the inorganic fine particles are silica having a particle diameter of 0.1 [mu] m or less. 2. The toner for developing an electrostatic image according to claim 1, wherein the toner is charged on a carrier and then attached to a polycarbonate, and when one toner particle has another toner particle approaching a distance of 5 μm, the toner particles are separated from each other. Wherein the toner particles are repelled so that the toner particles do not adhere to each other. 2. The toner for developing an electrostatic image according to claim 1, wherein the absolute value of the average charge amount when the toner contains a compound having a melting point of 2% or more and the compound is 5 μm is the absolute value of the average charge amount of the toner. A toner for developing an electrostatic image, wherein the toner is smaller than the value by 5 (μc / g). 7. The toner for developing an electrostatic charge image according to claim 6, wherein 1000 toner particles are arranged on a slide glass, and after being placed at 100 ° C. for 10 minutes in that state, 990 toner particles are observed under an optical microscope. The toner for developing an electrostatic charge image as described above. The toner for developing an electrostatic image according to claim 1, wherein after outputting 10,000 sheets using the toner, when the surface composition of the toner is measured by photoelectron spectroscopy, it contains a substance that is not contained in the initial toner. A toner for developing electrostatic images, characterized in that it is not used. 9. An electrostatic image developing method, wherein the developing sleeve is a developing sleeve having a cleaning mechanism when developing is performed using the toner according to claim 1 by a developing unit having the developing sleeve.