JPH0844195A - Toner carrier and developing device - Google Patents

Abstract

PURPOSE:To electrostatically charge a toner to the fullest extent without generating an afterimage or leaving or accumulating electric charges on the surface of a toner carrier, to transfer the toner enough for a process and to give a stable high quality image by forming the surface of the toner carrier with a nitrile rubber-resin mixture. CONSTITUTION:The surface of a core metal 51 is coated with an electric conductor layer 52 to obtain the objective toner carrier 5. A known metal may be used as the core metal 51 and the electric conductor layer 52 is made of a nitrile rubber-resin mixture. The nitrile rubber means a rubberlike substance obtd. by copolymerizing butadiene with acrylonitrile. Fluororesin or silicone resin is preferably used as the resin from the viewpoint of releasability, heat and wear resistances and environmental resistance. The ratio of the nitrile rubber to the resin is preferably 1-1.5. In the case of >1.5, an afterimage occurs owing to excessively high volume resistivity. In the case of <1, surface characteristics deteriorate and the filming of a toner is caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner carrier and a developing device in electrophotography, and more particularly to a toner carrier and a developing device using a one-component toner.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electronic copying machine, a printer or a facsimile, which forms an electrostatic latent image on an electrostatic latent image holder and visualizes it with a developer to obtain a recorded image, a powdery powder is used. A dry type developing device using a developer is widely adopted. As the powdery developer, there are a two-component developer having a toner and a carrier, and a one-component developer containing no carrier, and the two-component developing method using the former two-component developer is Although a relatively stable and good image can be obtained, it has the drawback that carrier deterioration and fluctuations in the mixing ratio of toner and carrier are likely to occur, maintenance of the device is complicated, and the size of the entire device tends to increase. ing.

From this point of view, a one-component developing system using a one-component developing agent which does not have the above-mentioned drawbacks has been receiving attention. The one-component developer is classified into a toner consisting only of toner, a toner externally added with an auxiliary agent, and a toner mixed with the auxiliary agent, if necessary. As the toner, there are a magnetic toner in which magnetic powder is kneaded in the toner particles themselves and a non-magnetic toner containing no magnetic powder. Here, since the magnetic substance is generally opaque, when a color image including full color and multi-color is formed by magnetic toner, the developed visible image becomes unclear and a vivid color image cannot be obtained. Therefore, especially for color development, it is desirable to adopt the one-component development method using non-magnetic toner.

By the way, in a developing device adopting a one-component developing system, a one-component developer is carried on a developer carrier (toner carrier) and conveyed, and the toner carrier and the electrostatic latent image carrier are carried. The electrostatic latent image formed on the electrostatic latent image holding member is visualized by the developer in the developing area where and are opposed to each other. However, it is sufficient to obtain a high-quality visible image of a predetermined density. It is necessary to convey a sufficient amount of charged toner to the developing area and to visualize the electrostatic latent image with such toner.

Conventionally, as a method of developing an electrostatic latent image using a non-magnetic one-component toner, a toner carrier (developing roller,
The toner on the developing belt, etc.) is thinned by a layer thickness regulating member, that is, a blade-shaped or roll-shaped member, and is applied to an electrostatic latent image holding member (that is, a photoconductor) holding an electrostatic latent image. A method of developing by contact is known. In this method, the toner carrier is (1) toner replenishment,
(2) Toner charging, (3) Toner thin layer formation, (4)
The cycle of toner conveyance, (5) development, (6) elimination of residual charge is repeated, but when the developing roller or developing belt makes one cycle and enters the next cycle, the developing roller or developing belt does not Countercharge occurs due to frictional charging with toner, and the distribution charge from the photoconductor remains on the surface and inside of it, so the charging characteristics and developing characteristics of toner deteriorate with repeated use, and the so-called afterimage phenomenon occurs. was there. For this reason,
Conventionally, various methods of removing electricity from a toner carrier have been studied, and, for example, a method of bringing a low resistance material such as a metal brush or a conductive sponge into contact with the surface of the toner carrier has been proposed.

However, when a metal brush is used,
Since the contact with the surface of the toner carrier is uneven, streaky stripes may be formed on the image, and when a conductive sponge is used, the afterimage disappearing effect is not sufficient. Further, these methods have a drawback that the effect of static elimination is extremely poor because they are methods of contacting the toner carrier through the thin toner layer. As described above, various attempts have been made to improve the charge removal effect, such as the material and density of the brush and the number of conductive sponge rollers installed, but the afterimage has not completely disappeared. It's a reality. On the other hand, due to such improvements from the developing system side, it is very easy to initialize, in other words, a toner carrier in which no electric charge remains is being developed.

As such a toner carrier, there is generally one that is made conductive by dispersing conductive powder such as carbon black or fine metal powder in resin or rubber. However, such a particle dispersion system lacks uniformity and causes variations. Also, 10 ⁸ to 10 ¹²
It is very difficult to adjust the semiconductive region of Ω · cm. Various studies have been made to uniformly disperse this problem, but it is still not sufficient, and many of them are not practical because the structure is complicated. Therefore, a method of controlling the resistance value by using epichlorohydrin-ethylene oxide copolymer rubber, nitrile rubber or the like, which itself is 10 ⁸ to 10 ¹¹ Ω · cm, is used as in JP-A-64-52180.

However, this epichlorohydrin-
Since ethylene oxide copolymer rubber and nitrile rubber have poor releasability on the surface, it is difficult to completely prevent the occurrence of so-called toner filming in which the toner is fused when used as a toner carrier. In the developing process, the toner generally has a charge amount of 5 to 30 μc / g (preferably 15 to 25 μc / g) on the toner carrier.
g), and the adhesion amount is adjusted to 0.3 to 0.5 mg / cm ² . However, in order to obtain a sufficient image density, 0.8 to 1.2 mg / cm ² of toner is required on the transfer paper, and therefore the toner carrier is 2 to 4 times as large as the latent image carrier. The toner amount is covered by driving at the speed. However, in this case, there is a difference in speed between the toner carrying member and the latent image holding member, so that so-called "from the toner rear end" occurs in which the toner approaches the rear end of the image. This is noticeable in solid images. Further, this is a particular problem in full-color development in which colors are overlapped. Therefore, in order to prevent this development, it is required to bring the speed of the toner carrier closer to the latent image carrier. For this purpose, it is necessary to increase the amount of toner attached on the toner carrier. Specifically, 0.7
It is necessary to attach toner of about 1.5 mg / cm ² . That is, in the full-color developing device, it is required to improve the charging property of the toner carrier.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned problems and to prevent residual charge from accumulating on the surface of the toner carrier and, as a result, to not generate an afterimage.
Provided is a toner carrier suitable for imparting a sufficient amount of charge to toner, conveying a sufficient amount of toner, and obtaining a stable high-quality image, and a developing device having the toner carrier. To do.

[0010]

The first aspect of the present invention is to provide a toner carrier for forming the toner supplied to the surface into a uniform thin layer by means of a toner layer thickness regulating member and using the toner for developing an electrostatic latent image. In the above, the surface is formed by mixing at least the nitrile rubber (A) and the resin (B). A second aspect of the present invention is a developing device including the above-mentioned toner carrier.

The present inventors have studied the toner carrier from various angles, and as a result, have found that the above object can be achieved by mixing the nitrile rubber (A) with the resin (B). The present invention is based on this.

The present invention will be described in more detail below.
FIG. 1 is a schematic view of a developing device of the present invention, in which 1 is a container, 2
Is a toner, 3 is an agitator, 4 is a replenishing roller, 5 is a toner carrier, 6 is a toner layer thickness regulating member, and 7 is an electrostatic latent image holder (photoconductor). The container 1 contains the non-magnetic one-component toner 2. Toner 2 is agitator 3
Is conveyed to a toner storage portion formed by the replenishing roller 4 and the toner carrier 5 and carried on the surface of the toner carrier 5. Further, the toner carried on the surface of the toner carrier 5 forms a uniform thin layer by the toner layer thickness regulating member 6 and is triboelectrically charged to a predetermined polarity. The thin toner layer is carried to a developing area where the electrostatic latent image carrier 7 and the toner carrier 5 come into contact with each other, where the toner 2 is electrostatically transferred from the toner carrier 5 to the electrostatic latent image carrier 7. , The latent image is visualized.

In this process, the toner 2 and the toner carrier 5 are electrostatically coupled by triboelectric charging. After the toner 2 moves to the electrostatic latent image carrier 7, the toner carrier 5 is A counter charge is generated in the, and if it remains until the next stroke, a so-called afterimage is generated. In addition, if the releasing property of the surface of the toner carrier is poor, the toner 2
Will be fused to the surface of the toner carrier 5 and the chargeability and transportability of the toner 2 will be deteriorated. The present invention employs the toner carrier 5 having the above-described specific structure in order to quickly leak such a counter charge and to provide a developing device having a good toner chargeability and transportability.

FIG. 2 shows an example of the toner carrier according to the present invention.
Shown in The toner carrier 5 has a structure in which a conductor layer 52 is coated on a cored bar 51. A conventionally known metal or the like can be used for the cored bar 51. The conductor layer 52 is made of nitrile rubber (A)
And a resin (B).

The nitrile rubber as referred to in the present invention means a rubber-like substance obtained by copolymerization of butadiene and acrylonitrile.

The resin used in the present invention has a reduced surface releasability, wear resistance, and the like, which occur when nitrile rubber is used alone.
It is used to eliminate defects such as environmental resistance.

The resin used in the present invention is easily compatible with nitrile rubber, and can improve the reduction in releasability, abrasion resistance, and environmental resistance that occur when nitrile rubber is used alone. Also, nitrile rubber (A) and resin (B)
The volume resistance can be easily adjusted by changing the mixing ratio of.

As such resin, alkyd resin,
Examples thereof include chlorinated polyether, chlorinated polyethylene, epoxy resin, fluororesin, phenol resin, polyamide, polycarbonate, polyethylene, methacrylic resin, polypropylene, polystyrene resin, polyurethane, polyvinyl chloride, polyvinylidene chloride and silicone resin.

In the present invention, it is preferable to use a fluororesin or a silicone resin from the viewpoints of releasability, heat resistance, abrasion resistance and environment resistance.

Examples of the fluororesin include polyfluoroethylene, polytetrafluoroethylene, polyvinyl fluoride and the like.

A modified silicone resin is preferably used as the silicone resin, and specific examples thereof include alkyd-modified silicone resin, acrylic-modified silicone resin,
Examples thereof include epoxy-modified silicone resin, urethane-modified silicone resin, melamine-modified silicone resin, phenol-modified silicone resin and polyester-modified silicone resin.

The mixing ratio of the nitrile rubber (A) and the resin (B) is preferably (A) / (B) = 1/1 to 1 / 1,5. If (B) is more than this range, the volume resistance will be too high and an afterimage will occur. On the other hand, if (A) is more than this range, the surface characteristics will deteriorate and toner filming will occur.

Further, in the present invention, when a modified silicone resin is used as the resin (B), the environment resistance can be effectively improved by further adding a silane coupling agent. The silane coupling agent includes, for example, an olefin functional silane, an epoxy functional silane, a methacrylic functional silane, an amino silane, a mercapto functional silane, and an isocyanate functional silane. In particular, when an aminosilane coupling agent is used, the triboelectric chargeability with a negatively chargeable toner can be effectively improved.

Examples of aminosilane coupling agents include
The following are examples. (1) (CH₃CH₂O)₃Si (CH₂) NH₂ (2) (CH₃O)₃Si (CH₂)₃NH₂  (5) (CH₃O)₃Si (CH₂)₃NHPh (Pb: F
(Enyl) (6) (CH₃O)₃Si (CH₂)₃NHCH₃ (7) (CH₃O)₃Si (CH₂)₃N (CH₃)₂ (8) (CH₃O)₃Si (CH₂)₃NH (CH₂)₂NH
₂   (10) (CH₃CH₂O)₃Si (CH₂)₃NH (CH₂)
₂NH₂ (11) (CH₃O)₃Si (CH₂)₃NH (CH₂)₆NH
₂ (12) (CH₃O)₃Si (CH₂)₂XCH₂NH (CH₂)₂N
H₂(X: phenylene group)

According to the research conducted by the present inventors, it has been found that the silane coupling agent reacts with the residual functional hydroxyl group in the cross-linking reaction of the modified silicone resin to improve the environmental resistance. It was also found that the charging property is more effectively exhibited by reacting with the modified silicone resin. Therefore, it is preferable to select a silane coupling agent having higher reactivity with the modified silicone resin used. The addition amount of the silane coupling agent is set to a necessary minimum, and if it is added more than that, unreacted silane coupling agent remains and the environment resistance is deteriorated. Furthermore, when an organometallic catalyst is added to these at the same time, the reactivity between the modified silicone resin and the silane coupling agent is increased, and the environment resistance and the charging property are further improved. The organometallic catalyst includes inorganic or organic substances containing Sn, Zn, Pb, Fe, Co, Ti, Al and the like, and those having good reactivity are appropriately selected and used.

In the conductor layer of the toner carrier of the present invention, silica, calcium carbonate, and
An inorganic filler such as calcium oxide, magnesium oxide or zinc oxide, or a charge control agent such as a nigrosine dye or a chromium-containing azo dye may be contained. The toner carrier of the present invention can be manufactured by a usual method such as spray coating, press molding, dipping, injection molding, and extrusion molding. The thickness of the conductor layer 52 is not particularly limited, but it is preferably 20 μm or more in order to form a stable layer.

The structure of the toner carrier in the present invention is not limited to the above-mentioned structure, and it is sufficient that the toner carrier has at least the surface of the conductive layer described in detail above, and may have a multi-layer structure if necessary. Further, the shape is not limited to the roller shape.

[0028]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. Both parts and% are based on weight.

Example 1 An Al cored bar roller was spray-coated with the following components for forming a conductor layer, cured and dried at 150 ° C. for 1 hour to form a dielectric layer having a thickness of about 30 μm. It was used as a carrier (Fig. 2). (Conductor layer forming component) Nitrile rubber 5% toluene solution 220S: 100 parts manufactured by Nippon Synthetic Rubber Co., Ltd. 100 parts fluorocopolymer resin resin 10 parts (Lumiflon 601C: manufactured by Asahi Glass Co., Ltd.) Coronate EH (curing agent for Lumiflon) 4 parts Toluene 100 Department

Example 2 A toner carrier was prepared in the same manner as in Example 1 except that 10 parts of silicone resin (SR2411: manufactured by Toray Dow Corning Silicone Co., Ltd.) was used instead of 10 parts of the fluororesin. It was

Examples 3 to 8 Acrylic-modified silicone resin (KR9706C solid content 50%) in place of the fluororesin in Example 1 (manufactured by Shin-Etsu Chemical Co., Ltd.) was used in the same manner except that the formulation shown in Table 1 was used. , A toner carrier was prepared.

[0032]

[Table 1]

[0033] Example 9 Example 6 In a further, acryl functional silane coupling agent _{((CH 3 O) 3 Si} (CH 2) 3 O-CO-CH 2 CH 3)
A toner carrier was prepared in the same manner except that 1 part of was added.

Example 10 The procedure of Example 3 further includes an epoxy functional silane coupling agent. In the same manner, a toner carrier was prepared.

Comparative Example 1 A toner carrier was prepared in the same manner as in Example 1 except that the fluororesin was not used.

The following evaluations were carried out on the above Examples and Comparative Examples using the developing apparatus shown in FIG. At this time, the drive speed ratio (linear speed ratio) between the electrostatic latent image carrier and the toner carrier was set to 1: 2.5. (Measurement of Toner Charge Amount) The toner on the toner carrier was measured by the blow-off method using a negatively chargeable black toner having the following composition. (Toner composition) Styrene acrylic resin 100 parts Carbon 10 parts Chromium-containing monoazo dye 2 parts After melt-kneading, pulverized and classified, 0.5 parts of hydrophobic silica was mixed with a mixer to obtain a toner. . (Measurement of Toner Adhesion Amount) The amount of toner on the developing roller was measured by tape transfer. (Evaluation of Image Retention) A pattern image as shown in FIG. 3 was output to evaluate image retention. That is, after developing the black solid area,
The halftone dot is developed, and the image density of the halftone dot corresponding to the position of the black solid area (ID ₁ ) and the image density of the halftone dot other than the black solid area (ID _h ) are measured by a Macbeth densitometer. Ratio (I
It was to evaluate the persistence of vision by D _l / ID _h). That is, if the ratio is 1, no afterimage is generated and it is good, but the more it deviates from 1, the worse the afterimage is. (Evaluation of releasability) The state of the surface of the toner carrier after 10,000 images were output was evaluated according to the following criteria. Rank A: Toner on the roller surface can be easily removed by air blow. Rank B: A small amount of toner remains partially by air blow. Rank C: It cannot be completely removed by air blow, and a thin layer of toner remains. Rank D: The molten toner is strongly adhered to the roller surface.

(Evaluation of environmental resistance) These evaluations are 10
℃ / 15% RH, 20 ℃ / 50% RH, 30 ℃ / 90%
It was carried out under the conditions of RH. The evaluation results are summarized in Table 2.

[0038]

[Table 2]

Example 11 A toner carrier was prepared in the same manner as in Example 3 except that 1 part of the aminosilane coupling agent (the above structural formula (1)) was added.

Example 12 A toner carrier was prepared in the same manner as in Example 3 except that 1 part of the aminosilane coupling agent (the above structural formula (8)) was added.

Example 13 A toner carrier was prepared in the same manner as in Example 13 except that 0.1 part of Pb-based catalyst was further added.

Comparative Example 2 The toner carrier of Example 1 was used.

Comparative Example 3 A toner carrier was prepared in the same manner as in Comparative Example 2 except that 1 part of the aminosilane coupling agent (the above structural formula (8)) was added.

Comparative Example 4 A toner carrier was prepared in the same manner as in Comparative Example 3 except that the amount of the aminosilane coupling agent was changed to 2 parts.

Comparative Example 5 A toner carrier was prepared in the same manner as in Comparative Example 3 except that 0.1 part of Pb type catalyst was further added.

In the developing device shown in FIG. 1, the following cyan toners were used to perform the same evaluations for the above examples and comparative examples. At this time, the driving speed ratio between the electrostatic latent image holding member and the toner carrying member was set to 1: 1.02. (Toner composition) Polyol resin 100 parts Salicylic acid derivative Zn salt 4 parts Copper phthalocyanine 3 parts A mixture was melt-kneaded, then pulverized and classified, and 0.75 parts of hydrophobic silica was mixed with a mixer to obtain a toner.

The evaluation results of these toner carriers are summarized in Table 3.

[0048]

[Table 3]

Further, when a color image was output by full-color copying using the developing device equipped with the toner carrier of Example 11, a high-quality image with good image density and no toner trailing edge was obtained. It was High quality images were similarly obtained when the toner carriers of Examples 12 and 13 were used.
On the other hand, when the developing device equipped with the toner carrier of Comparative Examples 2 to 5 was used, the image density was low and the background image was a bad image.

[0050]

According to the first aspect of the present invention, that is, by using the toner carrier composed of the nitrile rubber and the resin mixed with each other, a high quality image free from afterimage and toner filming is provided. It can be a developing device. According to the second aspect of the invention, it is possible to obtain a toner carrier having a volume resistance in an appropriate range and further improved surface characteristics. According to the invention of claim 3, particularly, by using a fluororesin or a silicone resin as the resin, excellent environment resistance can be obtained. According to the invention of claim 4, when a modified silicone resin is used, a silane coupling agent is used together with the modified silicone resin, whereby the environment resistance can be further improved. Further, the use of the aminosilane coupling agent improves the chargeability with the negatively chargeable toner. According to the invention of claim 5, it is possible to provide a developing device capable of obtaining a stable high-quality image.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a developing device of the present invention.

FIG. 2 is a diagram showing an example of a toner carrier of the present invention.

FIG. 3 is a diagram showing a pattern image for evaluating residualness.

[Explanation of symbols]

 1 Container 2 Toner 3 Agitator 4 Replenishing Roller 5 Toner Carrier 6 Toner Layer Thickness Controlling Member 7 Electrostatic Latent Image Holder 51 Core Bar 52 Conductor Layer

Claims (5)

[Claims] 1. A toner carrier for making the toner supplied to the surface a uniform thin layer by means of a toner layer thickness regulating member, the toner carrying member for developing the electrostatic latent image, the surface having at least the nitrile rubber (A). And a resin (B) are mixed, and a toner carrier. 2. The toner carrier according to claim 1, wherein the mixing ratio of the nitrile rubber (A) and the resin (B) is (A) / (B) = 1/1 to 1/15. 3. The toner carrier according to claim 1, wherein the resin (B) is a fluororesin or a silicone resin. 4. The toner carrier according to claim 3, wherein when the resin (B) is a silicone resin, it also contains a silane coupling agent. 5. A developing device comprising the toner carrier according to claim 1, 2, 3, or 4.