JPH0792724A - Developer and developing device using the developer - Google Patents

Abstract

PURPOSE:To provide a developer which is difficult to be influenced by environment. CONSTITUTION:The first inorganic oxide which is hydrophobically processed and has the mean particle diameter of 5 to 20nm and the second inorganic oxide which is hydrophobically processed and has the mean particle diameter of 20nm to 2mum are mixedly added into a toner composed of at least a binding resin and a coloring agent. Since the second inorganic oxide which is large in the mean particle diameter and hydrophobically processed is mixedly added, the occurrence of a liquid bridge can be prevented, and since the first inorganic oxide which is small in the mean particle diameter and hydrophobically processed is mixedly added, the fluidity of the toner can be secured.

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 charge image (hereinafter referred to as "developer") used for developing an electrostatic charge image by an electrophotographic method and a developing apparatus using the toner.

[0002]

2. Description of the Related Art In developing an electrostatic image by electrophotography, a toner needs to have a high chargeability in order to form a good visible image. A charge control agent is uniformly dispersed in the above to give the required chargeability.

By using a polyester resin as the binder resin, a sufficient negative charge can be obtained without using a charge control agent. Further, by using the polyester resin and the charge control agent in combination, it is possible to obtain a toner having a good rise of charging even in the one-component developing method with a low charging probability. Therefore, polyester resin is also used as the binder resin.

[0004]

However, when the binder resin which is the main component of the toner particles is a polyester resin, the polyester resin has an ester bond in the main chain and a polar group such as a hydroxyl group or a carboxyl group at the end. Therefore, it has a drawback that it easily absorbs moisture and easily causes image quality deterioration such as fog on the image and the surface of the photoreceptor due to a decrease in charge amount in a high temperature and high humidity atmosphere and a liquid bridge phenomenon with the charging member or the surface of the photoreceptor. It was

Conventionally, hydrophobized silicon dioxide may be used in order to secure the fluidity of the toner, but since the average particle diameter is as small as about 5 to 20 nm, a liquid bridge occurs. Could not be prevented.

Therefore, the present invention has been made in view of the above circumstances, and an object thereof is to provide a developer which is not easily influenced by the environment, and also to provide a developing device which is hard to cause deterioration of image quality. With the goal.

[0007]

In order to achieve the above object, a developer according to claim 1 is a toner comprising at least a binder resin and a colorant, which is an inorganic oxide hydrophobized and has an average particle size. The present invention is characterized in that a first inorganic oxide having a diameter of 5 to 20 nm and a second inorganic oxide having an average particle diameter of 20 nm to 2 μm are mixed and externally added.

Further, in the developer according to a second aspect, the binder resin is a polyester resin.

According to the third aspect of the present invention, the ratio of the first inorganic oxide to the toner is 0.05 to 3 parts by weight, and the ratio of the second inorganic oxide is 0.1 to 5 with respect to the toner. It is a part by weight.

The developer according to claim 4 is the developer according to the first aspect.
The mixing ratio of the inorganic oxide and the second inorganic oxide is 1/4 to 4.

According to a fifth aspect of the present invention, in a developing device, a toner including at least a binder resin and a colorant is a hydrophobically treated inorganic oxide having an average particle diameter of 5 to 20 nm.
Average particle diameter of the first inorganic oxide of 20 nm to 2 μm
Storage means for storing the developer mixed and externally added with the second inorganic oxide, supply means for supplying the developer stored in the storage means, and supply means provided so as to face the image carrier. Developing means for developing the electrostatic latent image formed on the image bearing member by using the developer supplied by the above.

[0012]

According to the developer described in claim 1, fog is apt to occur on an image or on the surface of a photoconductor in a high temperature and high humidity atmosphere. When the distance is less than a certain distance, a bridge of water is formed and the liquid bridge force is larger than the Coulomb force or the Van der Waals force. It is considered that the cause is that the toner remains on. Therefore, by mixing and externally adding the second inorganic oxide having a large average particle size and being hydrophobized, the distance between the toner surface and the other surface can be secured and the occurrence of liquid bridge can be prevented. Further, the fluidity of the toner can be ensured by mixing and externally adding the first inorganic oxide having a small average particle size and having been subjected to the hydrophobic treatment. The average particle size of the first inorganic oxide is 5
If it is less than nm, the fluidity of the toner becomes too good, and the charge amount distribution becomes broad, which causes an increase in fog. When the average particle diameter of the second inorganic oxide is larger than 2 μm, when it remains on the photoconductor, it becomes difficult to scrape it with a cleaning blade, resulting in poor cleaning, and fine particles filming on the photoconductor. Occurs. Therefore, the average particle diameters of the first and second inorganic oxides are set within the above range.

According to the developer of the second aspect, by using the polyester resin as the binder resin, sufficient negative charge can be obtained without using the charge control agent.

According to the third aspect of the developer, when the mixing amount of the first inorganic oxide is less than 0.05 parts by weight or exceeds 3 parts by weight, proper toner fluidity is ensured. It becomes difficult to do so, and the image quality is deteriorated. Also,
If the mixing amount of the second inorganic oxide is less than 0.1 parts by weight, the effect of preventing liquid bridge cannot be obtained, and if it exceeds 5 parts by weight, deterioration of image quality due to deterioration of fluidity will be caused. Therefore, the first
By setting the mixing amount of the second inorganic oxide within the above range, proper toner fluidity can be secured, liquid bridge can be prevented, and image quality deterioration can be prevented.

According to the developer of claim 4, by setting the mixing ratio of the first and second inorganic oxides within the above range, deterioration of image quality such as fog on the image and on the surface of the photoconductor is prevented. it can.

According to the developing device of the fifth aspect, by using the developer, it is possible to prevent image quality deterioration such as fog on the image and on the surface of the photoconductor.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a copying machine as a developing device of the present invention.

A toner container for accommodating a non-magnetic toner 5 (hereinafter abbreviated as toner 5) as a developer of the embodiment of the present invention in a developing device main body 1 (hereinafter abbreviated as main body 1) of the present embodiment. 3 (hereinafter abbreviated as container 3). Further, in the container 3, a mixer 7 for stirring the toner 5 is provided rotatably in the direction of arrow a. Further, the main body 1 has three rotators rotatable in the directions of the arrows, namely, the photosensitive drum 9, the developing roller 11, and the toner supply roller 13.
Are provided adjacent to each other. The photoconductor drum 9 has a rotary base 8 inside and a negatively chargeable organic photoconductor 10 on its surface. When the organic photoconductor 10 is irradiated with an original image as a light signal by a laser, an electrostatic latent image is generated. An image carrier on which an image is formed. The photosensitive drum 9 is connected to the ground. Next to the photosensitive drum 9, there is a developing roller 11 for attaching the charged toner 5 onto the electrostatic latent image on the photosensitive drum 9 to form a toner image. Developing roller 1
1 is covered with a member having both conductivity and elasticity. Next to the developing roller 11, there is a toner supply roller 13 for supplying the toner 5 contained in the container 3 onto the developing roller 11. A blade 15 having a function of restricting the amount of toner 5 supplied to the developing roller 11 and at the same time frictionally charging the toner 5 and a blade holder 17 for supporting the blade 15 are fixedly attached to the upper portion of the developing roller 11. ing. Further, below the developing roller 11, there is provided a recovery blade 19 having a function of recovering the toner 5 not used for development among the toner 5 supplied to the developing roller 11 and returning it to the container 3. Below the photoconductor drum 9 is a transfer device 21 for moving the toner image formed on the photoconductor 10 onto a transfer material.

The developing process in the developing device having such a structure is as follows. First, the toner 5 in the container 3 is sent to the toner supply roller 13 while being stirred by the mixer 7. Next, the toner 5 is supplied to the supply roller 13
To a developing roller 11 to form a thin layer of toner 5 on the surface of the developing roller 11. When forming a thin layer, the toner supply amount from the blade 15 to the developing roller 11 is regulated, and at the same time, the toner on the developing roller 11 is removed
The resulting flattening creates friction between the lamina and the blade. Due to this friction, the toner 5 is charged. By the way, the surface of the negatively chargeable organic photoconductor 10 on the photoconductor drum 9 is uniformly charged to about -500 to -550V by a charger (not shown). When the original image is directly irradiated onto the charged organic photoconductor 10 as a light image, the resistance of the organic photoconductor 10 in the irradiated part is lowered, and the charge in this part flows to the ground, and the surface potential approaches 0V. An electrostatic latent image is formed. In the reversal development method in which toner adheres to the electrostatic latent image and development is performed, a negatively chargeable toner is used as the toner.
Therefore, when the developing roller 11 having a thin layer of toner 5 negatively charged on its surface and the photosensitive drum 9 are rotated in opposite directions, the elastic force of the developing roller 11 causes the thin layer to become a photosensitive member 1.
It is slid on 0. The toner 5 adheres to the electrostatic latent image by the mechanical conveyance force and the electrostatic attraction force of the charges on the photoconductor and the charges of the toner, and the development is performed. On the other hand, although not shown, the main body 1 is provided with a paper supply tray for supplying paper. The paper supplied from this tray is sent between the photosensitive drum 9 and the transfer device 21 as a transfer material for transferring the toner image formed by development. When an electric charge having the same sign as that of the toner is applied to the back side of the fed paper by the transfer device, the toner image moves onto the paper by the force of the electric field. Further, while being supplied to the developing roller 11, it is not used for development, and the residual toner 5 is recovered again into the developing device through the recovery blade 19.

The developer of this embodiment accommodated in the above-described developing device is 94 parts by weight of a polyester resin as a binder resin, and carbon black as a colorant (MA-100: manufactured by Mitsubishi Kasei Co., Ltd.). ) 3 parts by weight,
A toner comprising 1 part by weight of a chromium dye (S-34: manufactured by Orient Chemical Co., Ltd.) as a charge control agent and 2 parts by weight of a wax (Viscole 66OP: manufactured by Sanyo Kasei Co., Ltd.) as a release agent is subjected to hydrophobic inorganic treatment. And a total amount of the first inorganic oxide having an average particle diameter of 5 to 20 nm and the second inorganic oxide having an average particle diameter of 20 nm to 2 μm is 0.5 wt% with respect to the toner. It is a mixture externally added.

The first inorganic oxide is silicon dioxide,
Aluminum oxide or the like can be used. Further, as the second inorganic oxide, silicon dioxide, titanium oxide, zinc oxide, tin oxide, barium titanate, strontium titanate or the like can be used. In this embodiment, silicon dioxide (silica) is used for both the first and second inorganic oxides.

Further, the first inorganic oxide having a small average particle diameter and subjected to the hydrophobizing process has a role of ensuring the fluidity of the toner.

Further, the second inorganic oxide having a large average particle size has a role of ensuring a distance between the toner surface and the other surface to prevent the occurrence of a liquid bridge. That is, in a high-temperature and high-humidity atmosphere, fogging is likely to occur on the image and the surface of the photoreceptor. This is because when the distance between the toner surfaces or the distance between the toner surface and the surface of the photoconductor approaches a certain distance or less, a water bridge is formed, and the liquid bridge force is larger than the Coulomb force or the Van der Waals force. It is considered that the cause is that the toner remains on the surface of the photoconductor where it should not be developed. Therefore, this problem is solved by mixing and externally adding a second inorganic oxide having a large average particle diameter and which has been subjected to a hydrophobic treatment.

Therefore, in order to achieve the role of the above-mentioned first inorganic oxide, its average particle diameter is set to 5 nm to 20 nm, and its ratio to the toner is set to 0.05 to 3 parts by weight. That is, when the average particle size is smaller than 5 nm,
The fluidity of the toner becomes too good, and the charge amount distribution becomes broad, which causes an increase in fog. Further, when the mixing amount of the first inorganic oxide is 0.05 parts by weight or less, or 3
If the amount exceeds the weight part, it becomes difficult to secure proper toner fluidity, which causes deterioration of image quality.

In order to achieve the role of the second inorganic oxide, its average particle diameter is set to 20 nm to 2 μm, and its ratio to the toner is set to 0.1 to 5 parts by weight.
That is, if the average particle size is larger than 2 μm, if the particles remain on the photoconductor, it becomes difficult to scrape them off with a cleaning blade, resulting in poor cleaning and fine particles filming on the photoconductor. Become. Further, if the amount of the second inorganic oxide mixed is less than 0.1 parts by weight, the effect of preventing liquid bridge cannot be obtained, and if it exceeds 5 parts by weight, deterioration of image quality due to deterioration of fluidity will be caused.

Accordingly, by setting the content of the first and second inorganic oxides within the above range, proper toner fluidity can be secured and liquid bridge can be prevented, so that deterioration of image quality can be prevented. The first inorganic oxide is 0.1 to 1.5 parts by weight, and the second
It is more preferable that the amount of the inorganic oxide is 0.2 to 2 parts by weight for improving the image quality.

Further, the mixing ratio of the first inorganic oxide and the second inorganic oxide is preferably 1/4 to 4 in order to prevent deterioration of image quality.

Next, a method for manufacturing the developer of the present embodiment having the above structure will be described.

First, polyester resin 9 is used as a binder resin.
4 parts by weight, carbon black as a colorant (MA-10
0: Mitsubishi Kasei Co., Ltd.) 3 parts by weight, 1 part by weight of a chrome dye (S-34: Onent Chemical Co., Ltd.) as a charge control agent, and 2 parts by weight of wax (Viscole 660P: Sanyo Kasei Co., Ltd.) as a release agent. To do. These are melt-kneaded using a continuous kneader or the like. Next, the product obtained by kneading is cooled, then coarsely crushed by a hammer mill or the like and classified to obtain a toner chip having an average particle size of 2 mm or less. The toner chips are finely pulverized with a jet mill or the like to have an average particle size of 11.0.
To obtain a toner of μm. Further, for the finely pulverized toner, the sum of the second silica (second inorganic oxide) having a large average particle diameter and the first silica (first inorganic oxide) having a small average particle diameter is Mix so as to be 0.5% by weight, and mix and adhere with a Henschel mixer or the like. In this way, the developer of this embodiment is obtained.

The effects of the developer of this embodiment having the above-described structure will be described with reference to Table 1.

[0032]

[Table 1]

Table 1 shows the image quality (fog on the image, fog on the photoconductor (drum), black solid followability, and image roughness) when the mixing ratio of the first silica and the second silica is changed. It shows the results of evaluation at the initial stage and after the 20,000-sheet life.
Sample No. A, B, C and D are the developers of this embodiment, and the mixing ratio of the second silica and the first silica was 4: 1, 3: 2, 2: 3, 1: 4, respectively. It is a thing. Sample No. E and F are comparative developers, and the mixing ratios of the first silica and the second silica are 5: 0 and 0: 5, respectively.
It is what

As is clear from Table 1, for example, only the second inorganic oxide having a large average particle diameter is used (Sample No.
F): When the toner fluidity is extremely deteriorated and a solid black solid image is printed, there is a drawback that the toner supply to the developing sleeve cannot catch up and the density of the latter half of the image becomes thin. On the other hand, the sample No. Since A, B, C, and D were externally mixed with the first inorganic oxide having a hydrophobization treatment of 5 to 20 nm, the fog on the image was 0.02% or less in the high temperature and high humidity atmosphere as well as the entire environment. Fog on body surface 0.65%
Good results could be obtained by comparing the following with other samples (No. E, F). That is, the sample No.
A, B, C, and D were obtained by additionally mixing and externally adding the first inorganic oxide having a small average particle size together with the second inorganic oxide, and therefore, the toner fluidity was prevented while preventing the occurrence of a liquid bridge at high temperature and high humidity. I was able to secure it. As a result, it was possible to obtain a developer in which the fogging on the image and the surface of the photoconductor in the entire environment was good and the density of the latter half of the black solid image on the whole surface was good.

The present invention is not limited to the above embodiment,
Various modifications can be made without changing the gist of the invention.

[0036]

According to the present invention described in detail above, the following effects can be obtained.

According to the invention of the developer described in claim 1, since the second inorganic oxide having a large average particle diameter and being hydrophobized is mixed and externally added, the occurrence of a liquid bridge is prevented. In addition, since the first inorganic oxide having a small average particle diameter and being hydrophobized is mixed and externally added, the fluidity of the toner can be secured. Therefore, it is possible to provide a developer that is not easily affected by the environment.

According to the second aspect of the invention, since the binder resin is a polyester resin, sufficient negative charge can be obtained.

According to the third aspect of the invention, since the mixing amount of the first and second inorganic oxides is within the above range, proper toner fluidity can be secured and liquid bridge can be prevented. It is possible to prevent deterioration of image quality.

According to the fourth aspect of the invention, since the mixing ratio of the first and second inorganic oxides is within the above range, deterioration of image quality such as fog on the image and on the surface of the photoconductor is prevented. It can be prevented.

According to the invention of the developing device of claim 5, since the developing agent is used, it is possible to provide a developing device in which image quality deterioration such as fog on the image and on the surface of the photosensitive member does not easily occur. .

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a copying machine as a developing device of the present invention.

[Explanation of symbols]

 1 Development device body 5 Non-magnetic toner (developer)

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Claims (5)

[Claims] 1. A first inorganic oxide having an average particle size of 5 to 20 nm and an average particle size of 20 nm to 2 μm, which is a hydrophobically treated inorganic oxide of a toner including at least a binder resin and a colorant. And a second inorganic oxide mixed with and externally added. 2. The developer according to claim 1, wherein the binder resin is a polyester resin. 3. The toner according to claim 1, wherein the ratio of the first inorganic oxide is 0.05 to 3 parts by weight and the ratio of the second inorganic oxide is 0.1 to 5 parts by weight with respect to the toner. The described developer. 4. The mixing ratio of the first inorganic oxide and the second inorganic oxide is 1/4 to 4,
The described developer. 5. A toner comprising at least a binder resin and a colorant, which is a hydrophobically treated inorganic oxide having a first inorganic oxide having an average particle diameter of 5 to 20 nm and an average particle diameter of 20 nm to 2 μm. Storage means for storing the developer mixed and externally added with the second inorganic oxide, supply means for supplying the developer stored in the storage means, and supply means provided so as to face the image carrier. A developing unit that develops the electrostatic latent image formed on the image carrier using the developer supplied by the developing device.