JP3250977B2 - Non-magnetic one-component developer and contact developing method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel nonmagnetic 1
The present invention relates to a component developer and a contact developing method using the same.

[0002]

2. Description of the Related Art In a contact developing method using a so-called non-magnetic one-component developer in which a magnetic carrier is not contained and toner particles themselves are also non-magnetic, a developer is first arranged near a photoreceptor. It is electrostatically attached to the surface of the developing sleeve. Next, the layer of the non-magnetic one-component developer is formed on the surface of the developing sleeve by passing between the developing sleeve and the regulating blade in contact with the surface. Contact the surface. Then,
The electrostatic latent image formed on the surface of the photoconductor is visualized as an image of toner particles.

[0003] Non-magnetic 1 used in the above-described contact developing method
The component developer is usually formed by externally adding silica fine particles or other inorganic fine particles to toner particles in order to adjust the fluidity, chargeability and the like. Further, in the above-mentioned contact developing method, a non-magnetic 1
The regulating blade used to form the layer of the component developer is currently composed of a plate-like rigid member such as a glass plate, and the smooth surface thereof is pressed against the surface of the developing sleeve. There are known types such as those of which the edge is pressed against the surface of the developing sleeve and those which are made of an elastic material such as urethane rubber and the edge of which is pressed against the surface of the developing sleeve. Have been.

[0004]

However, when a regulating blade of the type described above, of which the edge is pressed against the surface of the developing sleeve, is combined with the above-mentioned conventional non-magnetic one-component developer, the following is obtained. It has been clarified that various image defects may occur. That is, in the above combination, the thickness of the layer of the developer formed on the surface of the developing sleeve after passing through the regulating blade becomes uneven, or the thickness of the layer becomes insufficient, resulting in the formation of an image. The image density may be reduced.

Further, in the above-mentioned combination, so-called fogging, that is, the blank portion of the formed image is stained by the developer, is likely to occur. In particular, when developing conditions such as a bias voltage applied between the photoreceptor and the developing sleeve are adjusted during the development of the electrostatic latent image in order to prevent the image density from being reduced as described above, the margins are accordingly adjusted. There is also a problem that the fog density becomes high.

Further, among the regulating blades used in the above-mentioned combination, a regulating blade made of a particularly rigid material has a greater stress applied to the developer during layer formation than other regulating blades, so that image formation is repeated. During this time, the toner particles in the developer partially fuse to the edge of the regulating blade. As a result, a white streak-like image defect in which toner particles are stripped out occurs in the formed image, or the non-magnetic one-component developer layer becomes thinner in that portion, and the regulating blade Fog may occur as a result of the fact that triboelectric charging is less likely to occur.

An object of the present invention is to provide a non-magnetic one-component developer capable of forming an image having good image quality without causing the above-mentioned various image defects, and a contact developing method using the same. Is to do.

[0008]

In order to solve the above-mentioned problems, the inventors of the present invention have proposed a constitution of a conventional non-magnetic one-component developer, in particular, silica fine particles and other inorganic fine particles combined with toner particles as an external additive. The configuration was discussed. As a result, the thickness of the developer layer formed on the surface of the developing sleeve becomes uneven or the thickness becomes insufficient. The average particle diameter of the silica fine particles is 5 to improve the quality of the formed image.
About 20 n for toner particles of about 15 μm or less
It is presumed that the main cause is that the fluidity of the developer is excessively improved because it is less than about m, and it is easy to slip through the gap between the developing sleeve and the regulating blade during layer formation.

Further, one of the causes of fogging of the formed image is that the average particle size of the silica fine particles is too small as described above. That is, in the developer to which silica fine particles having an average particle diameter of less than 20 nm are externally added, the fluidity of the developer is excessively improved as described above, and the toner particles are formed in the gap between the developing sleeve and the regulating blade during layer formation. Of the toner particles without rolling, the toner particles are not sufficiently charged due to frictional charging with the regulating blade, and fogging occurs.

Therefore, as a result of studying the use of silica fine particles having a larger particle diameter than before,
When silica fine particles having an average particle diameter of 20 nm or more are used, when combined with a regulating blade of a type in which the edge is pressed against the surface of the developing sleeve as described above, a developer having an appropriate fluidity can be formed. (A) A layer of a developer having an appropriate thickness and a uniform thickness is formed on the surface of the developing sleeve to improve the image density of a formed image. (B) Toner particles are generated when the layer is formed. Rolling through the gap between the control blade and
The toner particles are sufficiently charged by the frictional charge with the regulating blade to prevent the occurrence of fogging, and the effect of preventing fogging can be exhibited.In addition, the polishing action of the silica fine particles allows the toner particles to adhere to the regulating blade described above. It has been found that the occurrence of white streaks and fogging due to fusion can also be suppressed.

Another cause of fogging of the formed image is due to inorganic fine particles. That is, when the resistance value of the inorganic fine particles externally added to the toner particles to adjust the charging property is far lower than the resistance value of the toner particles, or when the average particle size is too small, When the surface resistance becomes too low, fogging occurs in the formed image.

In order to prevent this, the resistance value of the inorganic fine particles is at least 0.01 times the resistance value of the toner particles, and the average particle size thereof is larger than the average particle size of the silica fine particles used in combination. I found that I had to use a big one. Further, according to this configuration, in the relationship with the bias voltage of the developer, the range of the bias voltage capable of keeping the fog density of the margin portion of the formed image within a practically allowable range is determined before the addition of the inorganic fine particles. It is also clear that the image density can be further increased, thereby suppressing an increase in fog density in the formed image and further improving the image density.

Based on these findings, the inventors further studied the range of the external addition amount of the specific silica fine particles and inorganic fine particles to the toner particles, and as a result, the present invention was completed. Reached. That is, the non -magnetic one-component developer of the present invention is a non-magnetic one-component developer.
The surface of the developing sleeve where the developer is placed near the photoconductor
And then pressed against the surface of the developing sleeve.
Between the regulating blade edge and the developing sleeve.
By passing through, the non-magnetic
After forming a one-component developer layer, this layer is
Contact with the surface of the photoreceptor to form an electrostatic latent
Non-magnetic one-component developer used in a contact developing method for developing an image
A is, with respect to the average particle diameter of toner particles 100 parts by weight of the nonmagnetic 5 to 15 [mu] m, (a) an average particle diameter of 20~60nm silica particles 0.5 parts by weight or more and, (b) resistance However, 0.1 parts by weight or more of inorganic fine particles having a resistance value of 0.01 times or more of the toner particles and an average particle diameter larger than the average particle diameter of the silica fine particles are externally added. Things.

Further, in the contact developing method of the present invention, the above-mentioned non-magnetic one-component developer is attached to the surface of a developing sleeve disposed in the vicinity of a photoreceptor, and then the regulating blade is pressed against the surface of the developing sleeve. By passing between the edge and the developing sleeve, on the surface of the developing sleeve,
After forming the non-magnetic one-component developer layer, the layer is brought into contact with the surface of the photoreceptor to develop an electrostatic latent image formed on the surface of the photoreceptor. .

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a non-magnetic one-component developer of the present invention will be described. As described above, the non-magnetic one-component developer of the present invention comprises (a) silica fine particles having an average particle diameter of 20 nm or more per 100 parts by weight of non-magnetic toner particles having an average particle diameter of 5 to 15 μm. 0.5 parts by weight or more, (b)
It is constituted by externally adding 0.1 parts by weight or more of inorganic fine particles whose resistance value is 0.01 times or more of the resistance value of the toner particles and whose average particle diameter is larger than the average particle diameter of the silica fine particles. Is done.

Among the above, the average particle diameter of the silica fine particles is 20
As described above, when silica fine particles having an average particle size of less than 20 nm are used, the fluidity of the developer becomes too high, and the edge thereof is particularly limited to the surface of the developing sleeve. When combined with a pressure-regulating type regulating blade, the image density of the formed image decreases,
In the formed image, the fogging density in the margin becomes high, and the polishing effect is not obtained, so that the fusion of the toner particles to the regulating blade and the occurrence of white streaks and fogging in the formed image due to the fusing density cannot be prevented. Because.

The average particle size of the silica fine particles is preferably within the above range, particularly preferably 60 nm or less.
More preferably, it is from 55 to 55 nm. When the average particle size of the silica fine particles exceeds 60 nm, the fluidity of the developer may be insufficient, and when added in a large amount to secure the fluidity, the fixability of the toner is reduced. There is a risk.

On the other hand, the reason why the resistance value of the inorganic fine particles is limited to 0.01 times or more of the resistance value of the toner particles as described above is that when the resistance value is less than this range, the surface resistance of the toner particles is more than necessary. Too low, and the fog density of the blank portion of the formed image increases, and the effect of adding the inorganic fine particles with respect to the bias voltage described above cannot be obtained.
This is because it becomes difficult to improve the image density while suppressing an increase in the fog density in the formed image.

The resistance value of the inorganic fine particles is preferably within the above range, particularly preferably 100 times or less, more preferably 0.1 to 10 times the resistance value of the toner particles. The resistance value of the inorganic fine particles is 100 times the resistance value of the toner particles.
If the value exceeds twice, the surface resistance of the toner particles may be too high, and the image density of the formed image may be reduced.

As the inorganic fine particles, any fine particles made of various inorganic materials whose resistance value falls within a range satisfying the above relationship with respect to the resistance value of the toner particles can be used. Suitable inorganic fine particles include, for example, fine particles of alumina, titanium oxide, zinc oxide, silica and the like. As described above, the average particle size of the inorganic fine particles is limited to a range larger than the average particle size of the silica fine particles. This is because, when the average particle diameter of the inorganic fine particles is equal to or less than the average particle diameter of the silica fine particles used in combination, the surface resistance of the toner particles becomes unnecessarily low as in the previous case, and the marginal portion of the formed image becomes This is because, as the fog density increases, the effect of adding the inorganic fine particles with respect to the bias voltage cannot be obtained, and it becomes difficult to improve the image density while suppressing an increase in the fog density in the formed image.

As described above, the average particle size of the inorganic fine particles may be larger than the average particle size of the silica fine particles used in combination. To make the effect of adding the inorganic fine particles described above more effective, The average particle size of the inorganic fine particles is preferably 50 nm or more. When silica fine particles are used as the inorganic fine particles, the average particle size is preferably within the above range, particularly preferably 60 nm or more.

The upper limit of the average particle size of the inorganic fine particles is not particularly limited, but is preferably about 600 nm. When the average particle diameter of the inorganic fine particles exceeds the above range, the fluidity of the developer is reduced, or, particularly, in the case of inorganic fine particles having high hardness, the surface of the photoreceptor is worn out early. There is a possibility that. In addition, the average particle diameter of the inorganic fine particles is particularly in the above range,
More preferably, it is 300 to 500 nm.

The reason why the external addition amount of the silica fine particles is limited to 0.5 parts by weight or more and the external addition amount of the inorganic fine particles is limited to 0.1 parts by weight or more based on 100 parts by weight of the toner particles is as follows. On the other hand, if it is out of the above range, the effect of adding both fine particles described above becomes insufficient, and the above-described various image defects occur in the formed image.

The external addition amount of both fine particles is preferably within the above-mentioned range, and particularly preferably 3 parts by weight or less. If any one of the external addition amounts of both fine particles is out of the above range, the excessive fine particles may hinder the fixing of the toner particles to the paper and cause a new image defect such as a defective fixing of the formed image. There is. The external addition amount of the silica fine particles is preferably in the range of 1.0 to 2.0.
The amount is more preferably 0 part by weight, while the external addition amount of the inorganic fine particles is preferably in the range of 0.2 to 0.7.
More preferably, it is parts by weight.

The developer of the present invention can be supplied to the developing sleeve more smoothly, especially when developing a solid black image longer than the outer circumference of the photosensitive member.
In order to prevent the decrease of the image density of the solid black portion after the circumference and improve the image density, in order to finely adjust the fluidity, in addition to the above both fine particles, an average particle diameter is less than 20 nm, preferably 7 nm. Silica fine particles having a fine particle size of about 16 nm may be externally added.

However, if the silica fine particles having such a fine particle size are added in a large amount, the fluidity of the developer becomes too high as described above, causing various problems. Therefore, the external addition amount is limited to 100 parts by weight of the toner particles. 0.005-0.
It is preferable to use a very small amount of about 1 part by weight, particularly about 0.03 to 0.08 part by weight. Non-magnetic toner particles to which the above-mentioned silica fine particles, inorganic fine particles, or silica fine particles having a fine particle diameter are externally added,
Its average particle size is limited to the range of 5 to 15 μm.

The reason is that the average particle size of the toner particles is 5 μm.
When the average particle diameter is less than 15 μm, the image density of the formed image becomes insufficient or the image density becomes uneven, and a good image cannot be obtained. This is because it is not suitable for improving the image quality of an image. The average particle size of the toner particles is preferably within a range from 7 to 12 μm, and is preferably from 7.5 to 8.5 μm.
m is more preferable.

The above-mentioned toner particles are constituted in the same manner as in the prior art. That is, a mixture obtained by blending a colorant and other components with a fixing resin and uniformly premixing the mixture with a dry blender, a Henschel mixer, a ball mill, or the like is used. After being uniformly melted and kneaded using a kneading device such as kneading, the obtained kneaded material is cooled and pulverized, and if necessary, classified, a so-called pulverization method is preferably used. In addition, substantially spherical toner particles produced by a production method utilizing a suspension polymerization method, a dispersion polymerization method, or the like can also be used. However, since the toner particles having a shape close to a sphere can easily slip through between the developing sleeve and the regulating blade, some means may be used in the post-manufacturing process or during the manufacturing process to prevent the above-described various image defects from occurring. It is preferable to use the product after it is deformed.

The fixing resin constituting the toner particles produced by the above-mentioned pulverization method includes, for example, polystyrene,
Chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-
Vinyl chloride copolymer, styrene-vinyl acetate copolymer,
Styrene-maleic acid copolymer, styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-
Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc., styrene-methacrylate copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate) Copolymers, styrene-butyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, etc.), styrene-α-methyl methyl acrylate copolymer, styrene-acrylonitrile-acrylate copolymer, etc. Resin (homopolymer or copolymer containing styrene or a substituted styrene), polyvinyl chloride, low molecular weight polyethylene, low molecular weight polypropylene, ethylene-ethyl acrylate copolymer, polyvinyl butyral, ethylene-vinyl acetate copolymer, Rosin-modified maleic resin Phenol resins, epoxy resins, polyester resins, ionomer resins, polyurethane resins, silicone resins, ketone resins, xylene resins, and polyamide resins can be mentioned, they are alone or 2,
Used as a mixture of more than one species.

As the coloring agent, various conventionally known dyes and pigments can be used. In the case of black toner particles, carbon black is mainly used. As the carbon black, various conventionally known carbon blacks such as channel black, roller black, disk black, gas furnace black, oil furnace black, thermal black, and acetylene black can be used.

The amount of the carbon black to be mixed with the fixing resin is not particularly limited. However, since the carbon black itself has conductivity, it also has a role as a means for controlling electric characteristics related to charging of toner particles. Play. Therefore, it is preferable to set a preferable range of the compounding amount in accordance with the performance of the target toner particles (especially, the above-described resistance value and the like). Although not limited thereto, it is preferable that the compounding amount of carbon black is about 1 to 10 parts by weight based on 100 parts by weight of the fixing resin in view of the chargeability of the developer.

Examples of other components to be added to the fixing resin together with the colorant include a charge control agent, a release agent (offset preventing agent), and various stabilizers. As the charge control agent, one of two charge control agents for positive charge control and negative charge control is used depending on the charge polarity of the toner particles. Among these, as the charge controlling agent for controlling positive charges, for example, a basic dye, an aminopyrine, a pyrimidine compound, a polynuclear polyamino compound, an organic compound having a basic nitrogen atom, such as aminosilanes, and surface-treated with each of the above compounds Examples include a filler and a charge control resin (CCR) such as a styrene-dimethylaminoethyl methacrylate copolymer.

The charge controlling agent for controlling the negative charge includes
Examples thereof include a compound having a carboxyl group such as an alkyl salicylate metal chelate, a metal complex dye, a fatty acid soap, a resin acid soap, a metal salt of naphthenic acid, a nigrosine base (C.I. 26150), an oil-soluble dye such as Bontron S or Spiron Black, or a charge controlling resin (CC such as styrene-styrenesulfonic acid copolymer).
R) and the like.

The charge control agent is added in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the fixing resin. Examples of the release agent (anti-offset agent) include aliphatic hydrocarbons, aliphatic metal salts,
Examples include higher fatty acids, fatty acid esters or partially saponified products thereof, silicone oil, various waxes and the like. Among them, aliphatic hydrocarbons having a weight average molecular weight of about 1,000 to 10,000 are preferred. Specifically, one or a combination of two or more of low-molecular-weight polypropylene, low-molecular-weight polyethylene, paraffin wax, and a low-molecular-weight olefin polymer having an olefin unit having 4 or more carbon atoms is suitable.

The release agent is added in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the fixing resin. Next, the contact developing method of the present invention will be described. FIG. 1 shows an example of a developing device for carrying out the contact developing method of the present invention.

The developing device 1 includes a developing sleeve 11 and
A regulating blade 12 having a substantially L-shaped cross section made of a rigid material and having an edge of the L-shape pressed against the surface of the developing sleeve 11 as shown in the figure, A replenishing roller 13 pressed against the surface of the developing sleeve 11, a stirring means 14 disposed behind the replenishing roller 13, and the above-described components are built in and filled with a non-magnetic one-component developer (not shown). The image forming apparatus includes an apparatus main body 10 and is arranged such that the surface of the developing sleeve 11 is pressed against the surface of the photoconductor 2.

As the developing sleeve 11, the one whose at least its surface is formed of a soft urethane rubber or the like is preferably used as in the prior art. The developing sleeve 11 having such a flexible surface does not damage the surface of the photoconductor 2. The developing sleeve 11
As the regulating blade 12 to be brought into contact with, the member made of various rigid materials can be used.
Considering durability against ozone generated during image formation, workability into an L-shape, and the like, those formed of stainless steel are preferably used.

The regulating blade 12 is pressed against the developing sleeve 11 by pressing means (not shown) (for example, a spring).
Is pressed against the surface with a predetermined pressing force. The developing sleeve 11 is pressed against the surface of the photoconductor 2 with a predetermined pressing force by pressing means (also a spring or the like) not shown. The contact development of the electrostatic latent image using the developing device 1 is performed in the following procedure.

That is, first, the photosensitive member 2 and the developing sleeve 1
1. The replenishing roller 13 and the stirring means 14 are each rotated at a predetermined rotational speed in the direction of the arrow shown in the figure. Then, the developer agitated by the agitating means 14 and supplied to the surface of the developing sleeve 11 by the replenishing roller 13 is charged and held by friction with the developing sleeve 11, and the held amount is controlled by the regulating blade 12. The developer is adhered to the surface of the developing sleeve 11 by the action of the mirror image of the regulating blade 12, and a layer of the developer having a predetermined thickness is formed on the surface of the developing sleeve 11. .

On the other hand, an electrostatic latent image corresponding to the formed image is formed on the surface of the photosensitive member 2 through the steps of charging and exposure. Then, the electrostatic latent image on the surface of the photoreceptor 2 comes into contact with the layer of the developer on the surface of the developing sleeve 11, and the developer is charged on the photoreceptor 2 in accordance with the charge distribution in the electrostatic latent image. Electrostatic adhesion to the surface, whereby the electrostatic latent image is visualized as an image of toner particles, completes one step of contact development.

As described above, the contact developing method of the present invention proceeds in substantially the same steps as the conventional method. However, since the above-described non-magnetic one-component developer of the present invention is used as the developer, A good image can be formed without causing image defects such as a decrease in image density, an increase in fog density, and generation of white streaks. In the contact development method, a photoreceptor and a toner that are charged to the same polarity are combined, and the toner is selectively attached to a portion of the surface of the uniformly charged photoreceptor whose potential has been reduced by exposure to light. Combine so-called negative-positive reversal development, which forms an image, with a photoreceptor and toner charged to opposite polarities, and select the part of the surface of the uniformly charged photoreceptor whose potential did not decrease due to exposure There is so-called positive-positive development in which a toner image is formed by adhering toner in a specific manner. The contact development method of the present invention can be applied to any of these methods.

[0042]

EXAMPLES << Preparation of Toner Particles >> The following components were mixed, melted, kneaded, pulverized and classified to obtain an average particle size of 8.3 μm and a resistance value of 2.86 × 10 ¹⁰ Ω. Non-magnetic toner particles were produced. Incidentally, the resistance value of the toner particles, a predetermined amount of toner particles were compressed and pelletized under heating,
This is a value measured by sandwiching a sample having a certain thickness between a pair of electrodes and applying an electric field having a frequency of 1 KHz.

(Components) (parts by weight) Fixing resin Polyester resin 100 Colorant carbon black 6 Charge control agent Chromium complex 2 Wax Low molecular weight polypropylene 2.5 << Examination of silica fine particles >> Preparation of above toner particles I got it,
To 100 parts by weight of non-magnetic toner particles, silica fine particles of types A to H shown in Table 1 below are externally added at a ratio shown in Tables 2 and 3 described below, and a negatively charged non-magnetic one-component developer is added. And

The amount of charge in Table 1 was such that 0.1 g of each silica fine particle was charged with a non-coated ferrite carrier 5.
After mixing with a tumbler mixer together with 0 g, 0.1 g of the mixture was added.
This is a value measured by a blow-off method using 1 g as a sample. Nitrogen gas was used as the compressed gas for the measurement, and the measurement conditions were as follows:
cm ³ and the spraying time was 1 minute.

[0045]

[Table 1]

Next, each non-magnetic one-component developer is provided with a developing device 1 having a structure shown in FIG. 1 in which a developing sleeve 11 made of urethane rubber and a regulating blade 12 made of stainless steel are combined. Was replaced with a negatively charged organic photoreceptor and used in a non-magnetic one-component contact developing type plain paper facsimile machine [modified TC-720 manufactured by Mita Kogyo Co., Ltd. Sheets, and the image density ID of each formed image and the fogging density FD of the margin are measured by a reflection densitometer [TC-TC manufactured by Tokyo Denshoku Co., Ltd.].
6D], and the respective average values were determined.
In addition, the thickness of the developer layer formed on the surface of the developing sleeve 11 during the image formation was measured. Further, the image having the image density ID of 1.35 or more and the fog density FD of 0.005 or less was excellent in the formed image (（). ).

Tables 2 and 3 show the above results.

[0048]

[Table 2]

[0049]

[Table 3]

From the above tables, it is preferable that the silica fine particles have an average particle diameter of 20 nm or more.
Moreover, it was confirmed that when the external addition amount was 0.5 parts by weight or more based on 100 parts by weight of the toner particles, an image having good image quality could be formed. In each of the above examples,
(1) 100 parts by weight of toner particles, 0.1 parts by weight of silica fine particles (average particle size: 40 nm) of type F, a developer externally added; (2) 100 parts by weight of toner particles, the same type 2.0 parts by weight of silica fine particles of F, a developer externally added, and (3) 100 parts by weight of toner particles,
Using a non-magnetic one-component developer of 2.0 parts by weight of silica fine particles of class C (average particle diameter of 16 nm) and a developer externally added to the above plain paper facsimile machine, 8,000 sheets were used. When continuous image formation was performed, white streaks occurred in the images after the 1,000th sheet with the developer of (1) and in the images after the 5,000th sheet with the developer of (3). ) Developer
White streaks did not occur in the continuous image formation of 8,000 sheets.
When the inside of the apparatus was observed after continuous image formation, (1)
When the developer of (3) was used, fusion of toner particles was observed at the edge portion of the regulating blade, but when the developer of (2) was used, such fusion was not observed.

From this, it can be seen that the average particle size is 20 nm.
When the above silica fine particles are externally added at a ratio of 0.5 part by weight or more with respect to 100 parts by weight of the toner particles, the fusion of the toner particles to the regulating blade and the formation of white streaks on the resulting image are caused. It was confirmed that generation could be prevented. << Investigation of Inorganic Fine Particles I >> Silica fine particles of types F to H among the suitable silica fine particles described above were added to 100 parts by weight of the toner particles obtained in the preparation of the toner particles,
5 and the following types a to d
0.4 parts by weight of each inorganic fine particle was externally added to obtain a negatively charged non-magnetic one-component developer.

(Type of inorganic fine particles) a: Alumina average particle diameter 500 nm Resistance value 1.0 × 10 ¹⁰ Ω Magnification of resistance value 0.35 times b: Titanium oxide average particle diameter 50 nm Resistance value 5.5 × 10 ⁸ Ω Resistance value magnification 0.02 times c: Magnetite average particle diameter 270 nm Resistance value 4.2 × 10 ⁶ Ω Resistance value magnification 1.47 × 10 ^-4 times d: Zinc oxide average particle diameter 20 nm Resistance value 5.0 × the 10 ⁸ Omega magnification 0.017 times the resistance and the non-magnetic one-component developer, the plain paper facsimile apparatus [Mita Industrial Co., Ltd. TC-720 modified machine]
Is actually used to form 10 continuous black-and-white images, and the image density ID of each formed image and the fog density FD of the margin are measured using a reflection densitometer [TC-6 manufactured by Tokyo Denshoku Co., Ltd.]
D], and the respective average values were determined. In addition, the image having the image density ID of 1.35 or more and the fog density FD of 0.005 or less was excellent in the formed image (○). ).

Tables 4 and 5 show the above results.

[0054]

[Table 4]

[0055]

[Table 5]

From the above tables, it is preferable that the inorganic fine particles have a resistance value of 0.01 times or more of the resistance value of the toner particles and an average particle diameter of 50 nm or more. It was confirmed that an image having good image quality could be formed when combined with silica fine particles having an average particle diameter of 20 nm or more. Further, in Table 3 and Tables 4 and 5, the image density and fog of the developers of the respective examples in which the type and the external addition amount of the silica fine particles are the same and the difference is whether or not inorganic fine particles are contained. Comparing the densities, it was confirmed that by externally adding inorganic fine particles having a resistance value and an average particle diameter within the above ranges, the image density can be further improved while suppressing an increase in fog density.

In each of the above examples, (4) Toner particles 10
0 parts by weight of silica fine particles of type F (average particle size 4
0 nm), 0.4 parts by weight of inorganic fine particles of type a (average particle diameter 500 nm, resistance value 1.0 × 10 ¹⁰ Ω), and a developer externally added, and (5) Of these, two types of non-magnetic one-component developers, in which inorganic fine particles were not externally added, were used in the plain paper facsimile machine described above, and were used between the photosensitive member and the developing sleeve during the development of the electrostatic latent image. An image was formed while changing the applied bias voltage stepwise, and a range of a bias voltage capable of keeping the fog density of the marginal portion of the formed image within the range of 0.005 or less was obtained. Did not (5)
Developer, the bias voltage range is from 250 to 45.
In contrast to 0 V, inorganic fine particles were externally added (4)
Developer, the bias voltage range is from 250 to 55
It was confirmed that the voltage spread to 0V. From this, it was also confirmed that by externally adding inorganic fine particles having a resistance value and an average particle diameter within the above-mentioned ranges, the image density can be further improved while suppressing an increase in fog density in a formed image.

Further, in Tables 4 and 5, the developer of each example using the silica fine particles of type F (average particle diameter of 40 nm) and the silica fine particles of type G (average particle diameter of 40 nm)
Was added to the developer of each example using silica fine particles (average particle diameter: 16 nm) of the type C as the fine silica particles having the above-mentioned fine particle diameter of 0.01% per 100 parts by weight of toner particles.
As shown in Tables 6 and 7 below, it was confirmed that the image density was further improved by the addition of the silica fine particles having the fine particle diameter as shown in Tables 6 and 7 below.

[0059]

[Table 6]

[0060]

[Table 7]

<< Investigation of Inorganic Fine Particles II >> The addition amount of carbon black was 7.5 parts by weight (toner particles 2) or 10.
Non-magnetic toner particles 2 having an average particle diameter of 8.3 μm and a resistance value of 5.3 × 10 ⁸ Ω were prepared in the same manner as in the preparation of the toner particles except that the amount was 0 parts by weight (toner particles 3). And an average particle size of 8.3 μm and a resistance value of 1.4 × 10 ⁸ Ω.
In this way, non-magnetic toner particles 3 were prepared.

Next, to 100 parts by weight of each of the toner particles, 1.0 part by weight of the above-mentioned preferable silica fine particles of the type G silica (average particle size: 40 nm) was externally added, and at the same time, inorganic fine particles (a) (average particle diameter 500 nm, resistance value 1.0 × 10 ¹⁰ Ω, magnification of resistance value for toner particles 2 18.9 times, magnification of resistance value for toner particles 3 71.4 times), or type b Inorganic particles (average particle diameter 50 nm, resistance value 5.5 × 10 ⁸ Ω, magnification of resistance value to toner particle 2 1.04 times, toner particle 3
(A magnification of 3.93 times the resistance value to the above) was added externally in an amount of 0.4 part by weight to obtain a negatively charged nonmagnetic one-component developer.

Then, each non-magnetic one-component developer was applied to the above-mentioned plain paper facsimile machine [TC-72 manufactured by Mita Kogyo KK].
No. 0 remodeling machine] to actually form 10 continuous black-and-white images, and measure the image density ID of each formed image and the fog density FD of the margin portion with a reflection densitometer [Tokyo Denshoku Co., Ltd.] And the average value of each was determined. In addition, the image having the image density ID of 1.35 or more and the fog density FD of 0.005 or less was excellent in the formed image (○). ).

Table 8 shows the results.

[0065]

[Table 8]

From the table, it was confirmed that an image having good image quality could be formed if the magnification of the resistance value of the inorganic fine particles to the toner particles was 100 times or less.

[0067]

As described above, according to the present invention, a non-magnetic one-component developer capable of forming an image having good image quality without causing various image defects and a contact developing method using the same are disclosed. Can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an apparatus for carrying out a contact developing method of the present invention.

[Explanation of symbols]

 11 developing sleeve 12 regulating blade 2 photoreceptor

Continuation of the front page (56) References JP-A-6-167827 (JP, A) JP-A-7-43930 (JP, A) JP-A 8-69127 (JP, A) JP-A 8-240925 (JP, A) JP-A-6-202374 (JP, A) JP-A-8-234479 (JP, A) JP-A-4-140758 (JP, A) JP-A-7-168388 (JP, A) JP-A-9-43895 (JP, A) JP-A-9-6038 (JP, A) JP-A-11-61245 (JP, A) JP-A-4-338977 (JP, A) JP-A-3-294864 (JP, A A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 9/08

Claims (7)

(57) [Claims] A non-magnetic one-component developer is disposed near a photoreceptor.
Adheres to the surface of the placed developing sleeve.
The edge of the regulating blade pressed against the surface of the sleeve,
By passing between the developing sleeve and the developing sleeve,
A layer of the non-magnetic one-component developer was formed on the surface of the
Then, this layer is brought into contact with the surface of the photoreceptor,
Contact developing method to develop electrostatic latent image formed on the surface of
(A) 0.5 parts by weight or more of silica fine particles having an average particle diameter of 20 nm or more with respect to 100 parts by weight of nonmagnetic toner particles having an average particle diameter of 5 to 15 μm. (B) externally adding 0.1 parts by weight or more of inorganic fine particles whose resistance value is 0.01 times or more of the resistance value of the toner particles and whose average particle size is larger than the average particle size of the silica fine particles. A non-magnetic one-component developer, characterized in that: 2. The non-magnetic one-component developer according to claim 1, wherein the average particle diameter of the silica fine particles is 60 nm or less. 3. The non-magnetic one-component developer according to claim 1, wherein the resistance value of the inorganic fine particles is 100 times or less the resistance value of the toner particles. 4. The non-magnetic one-component developer according to claim 1, wherein the average particle diameter of the inorganic fine particles is 600 nm or less. 5. The non-magnetic one-component developer according to claim 1, wherein the external addition amount of the silica fine particles is 3 parts by weight or less based on 100 parts by weight of the toner particles. 6. The non-magnetic one-component developer according to claim 1, wherein the external addition amount of the inorganic fine particles is 3 parts by weight or less based on 100 parts by weight of the toner particles. 7. The non-magnetic 1 according to claim 1,
The component developer is adhered to the surface of the developing sleeve disposed near the photoconductor, and then passed between the edge of the regulating blade pressed against the surface of the developing sleeve and the developing sleeve, thereby forming the developing sleeve. Forming a layer of the non-magnetic one-component developer on the surface of the photosensitive member, and then contacting the layer with the surface of the photosensitive member to develop an electrostatic latent image formed on the surface of the photosensitive member. Contact development method.