JPS6340171A - Developing method for electrostatic latent image - Google Patents

Abstract

PURPOSE:To enable formation of a sharp image having excellent resolution and tone reproductions by forming a developer layer to be formed on a developer conveying body as a thin layer and using a resin coated carrier formed by coating a resin contg. a fluoroplastic on magnetic material particles as a carrier. CONSTITUTION:The developer layer to be formed on the developer conveying body is formed as the thin layer and the resin coated carrier formed by coating the rein contg. at least >=30wt% fluoroplastic on the magnetic material particles is used as the carrier. More specifically, the fluoroplastic has the characteristic of small critical surface tension; therefore, the carrier provides the smooth surface condition and the possibility of generating the 'toner-filming' to retard the frictional charge characteristic of the carrier by sticking of the toner material; for example, coloring material such as carbon black or release agent or the like to the carrier surface is decreased in the frictional charge of the carrier and the toner. The frictional charge of the polarity and charge quantity adequate for the toner is thus stably imparted to the toner. The generation of the weakly charged toner is thereby considerably decreased and the carrier and toner are stably held on the developer conveying body. The good image is thus formed without generating the fogging.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for developing an electrostatic latent image, and in particular to a method for developing an electrostatic latent image formed on a latent image carrier in electrophotography, electrostatic recording, electrostatic printing, etc. The present invention relates to a method for developing an electrostatic latent image using a two-component developer.

[Background of the invention]

At present, as a method for forming a visible image from certain image information, methods using electrostatic latent images, such as electrophotography, electrostatic recording, and electrostatic printing, are widely used.

The developer used to develop such an electrostatic latent image is a so-called two-component developer, which is a mixture of toner and carrier, and a magnetic toner, which is used alone without being mixed with a carrier. There is a one-component developer.

In the former method of developing an electrostatic latent image using a two-component developer, the toner is frictionally charged by mechanically stirring the toner and carrier, so the characteristics of the carrier, stirring conditions, etc. are selected. By doing so, it is possible to control the charge polarity and charge amount of the toner to a considerable extent.
Furthermore, the range of colors that can be applied to the toner is wide, and in these respects it is superior to the latter method of developing an electrostatic latent image using a one-component developer.

Conventionally, in the method of forming a fixed image through a process of developing an electrostatic latent image using a two-component developer, it has been difficult to improve the resolution and gradation reproducibility of the fixed image, or to improve the resolution and gradation reproducibility of the fixed image. From the viewpoint of improving image quality, technical means have been proposed to reduce the diameter of both the carrier and the toner.

For example, Japanese Patent Application No. 58-577446, No. 58-9690
No. 0, No. 58-96901, No. 58-96902,
In the specifications such as No. 58-96903 and No. 58-97973, latent image A technical means for developing an electrostatic latent image formed on a carrier using a non-contact development method is disclosed. In this non-contact development method, a developer layer made of toner and carrier supported on a developer transport carrier is supplied to a development area in a state where the developer layer is not in direct contact with the latent image carrier. This is a method to do this.

However, when using a small-diameter carrier like this, the fluidity of the carrier tends to decrease as the diameter becomes smaller, making it difficult to achieve sufficient frictional charging between the toner and the carrier. The electrostatic and physical bonding force of the carrier to the toner is reduced, and the carrier is normally conveyed while being attached to the developer conveying rod by magnetic force. If the carrier has a small diameter, its magnetic adhesion to the developer transport carrier is low, and in the process of performing these image formation processes, the carrier or toner may scatter and contaminate the inside of the device, or the latent image may be There are problems such as toner or carrier adhering to the non-image area of the carrier, causing fog, and carrier adhering to the latent image carrier, making the image unclear.

On the other hand, when increasing the particle size of the carrier to prevent carrier scattering, etc., it becomes difficult to form a thin developer layer on the developer transport carrier, and the thickness of the developer layer increases. As a result, undesirable phenomena such as image unevenness or missing images occur in the finally obtained fixed image, resulting in the problem that a clear image cannot be obtained.

In addition, when the development process is repeated many times, in the process of forming a thin layer of developer on the developer transport carrier, a thin layer forming member such as a blade is placed on the developer transport carrier with an elastic layer. When controlling the thickness of the developer layer by applying pressure to the carrier, strong pressure is applied to the developer, which increases the so-called filming development in which the toner substance physically adheres strongly to the carrier. The frictional electrification between the toner and the carrier deteriorates, resulting in fogging due to weakly charged toner, toner scattering, or carrier with toner substance attached to the electrostatic latent image. Furthermore, carriers may adhere to the electrostatic latent image, resulting in a decline in image quality, and furthermore, it may become difficult to form a good Fi layer on the developer transport carrier. This causes various problems and ultimately makes it impossible to obtain a clear image.

On the other hand, in order to prevent the occurrence of fog, it is conceivable to increase the minimum value of the gap between the latent image carrier and the developer transport carrier in the development area, that is, the development gap. However, if the gap is large, the opposing electrode effect during development is reduced, and the developability, that is, the adhesion of the toner to the electrostatic latent image, is reduced, making it difficult to achieve good development.

In addition, developing performance can be improved by increasing the developing gap and forming a large oscillating electric field in the developing area. However, when forming a large oscillating electric field with a large developing gap, There are problems in that toner adhesion to non-image areas of the body increases, causing fog, and carrier scattering increases, contaminating the inside of the apparatus. Furthermore, since a large oscillating electric field is formed, it is necessary to sufficiently electrically insulate the developing device, making the design of the device considerably difficult.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to prevent contamination of the inside of the device due to toner and carrier scattering, and to avoid fogging. It is an object of the present invention to provide a developing method that allows good development to be carried out using component developers, thereby making it possible to form clear images with excellent resolution and gradation reproducibility.

Another object of the present invention is to provide a developing method that can form a clear image without image unevenness or missing images.

Still another object of the present invention is to be able to stably form a thin developer layer on a developer transport carrier even when the development process is repeated many times, and as a result, to maintain good performance over a long period of time. An object of the present invention is to provide a developing method that enables stable formation of images.

[Means for solving problems]

In the developing method of the present invention, a developer layer of a two-component developer consisting of toner and carrier is formed on a developer transporting carrier, and this developer layer is supplied to a development area in which an oscillating electric field is generated. In a developing method for developing an electrostatic latent image on an image carrier,
The developer layer formed on the developer transport carrier is a thin layer,
The carrier is characterized in that a resin-coated carrier is used in which magnetic particles are coated with a resin containing at least 30% by weight of a fluororesin.

[Function and effect of the invention]

According to the developing method of the present invention, the carrier constituting the two-component developer is a resin-coated carrier formed by coating magnetic particles with a resin containing a fluororesin in a specific proportion or more, and the fluororesin has a critical surface tension. Due to the small characteristics, the surface of the carrier becomes smooth, and when the carrier is charged by friction between the toner and the toner, toner substances such as coloring agents such as carbon black or release agents adhere to the surface of the carrier, causing the carrier to become smooth. There is little risk of so-called toner filming phenomenon that inhibits triboelectric charging properties, and triboelectric charges of appropriate polarity and charge amount can be stably imparted to the toner. Therefore, the generation of weakly charged toner is considerably reduced, and the carrier and toner are stably held on the developer transport carrier, making it possible to form good images without fogging. In addition, it is possible to prevent contamination within the apparatus due to toner scattering and carrier scattering.

In addition, fluororesin has the most negative triboelectrification ranking among resins, and a carrier coated with a resin containing the fluororesin has excellent negative chargeability. In the toner used, it is no longer necessary to use a charge control agent such as a dye or a particulate additive to impart positive chargeability.
As a result, it is possible to prevent adverse effects when using such a charge control agent. Since the amount of triboelectric charging of the toner can be controlled to a considerable extent by selecting the content of the fluororesin in the coating resin, it is possible to obtain a developer optimal for the developing method of the present invention.

As mentioned above, since the carrier has a smooth surface condition, sufficient fluidity of the developer can be obtained even when the diameter of the carrier is reduced, and the developer can be uniformly formed on the carrier for carrying the developer. It becomes possible to form a thin developer layer, and since the development process is carried out while applying the action of the oscillating electric field to the thin developer layer in the development area where the oscillating electric field is formed, the latent image is The adhesion of the toner to the static -1s layer image on the carrier becomes good, and as a result, it becomes possible to form a good image without image unevenness or image missing.

As mentioned above, since the carrier has a smooth surface, the surface of the carrier has good releasability, and therefore, a thin layer forming member such as a blade is attached to the developer transporting carrier, for example, elastically. Even when a thin layer of developer is formed by pressure contact, carriers can be prevented from adhering to the thin layer forming member and inhibiting the thickness adjustment function of the thin layer forming member. Even when subjected to strong pressure, the carrier is prevented from physically adhering to the toner, and a thin developer layer can be stably formed on the developer transport carrier. This prevents the toner filming phenomenon in which toner substances adhere, and creates a good friction zone between the toner and the carrier.
Stable conductivity is exhibited, and clear images can be repeatedly formed many times without contaminating the inside of the device due to fog, toner scattering, or carrier scattering.

[Specific structure of the invention]

In the present invention, a developer layer of a two-component developer consisting of toner and carrier is formed on a developer transport carrier, and this developer layer is supplied to a development area where an oscillating electric field is generated to form a latent image. In a developing method for developing a static M on a carrier, a latent image,
The developer layer formed on the developer transport carrier is a thin layer, and a resin-coated carrier is used as the carrier, which is made by coating magnetic particles with a resin containing at least 30% by weight of a fluororesin.

In the present invention, the developer layer on the developer transport carrier needs to be a thin layer, and the thickness of the thin layer is 2000p.
It is preferably less than m, more preferably 100
0n or less, particularly preferably 10 to 500 al.

The developer layer thus formed into a fairly thin layer is conveyed to a developing area in which an oscillating electric field is formed, in a state in which it is in contact with the latent image carrier, preferably not in contact with the latent image carrier, and the oscillating electric field is applied to the developer layer. to perform the development process. The minimum value of the gap between the latent image carrier and the developer transport carrier in the development area (hereinafter also referred to as "development gap") is such that the developer layer is preferably not in contact with the latent image carrier during development. It is preferable that the development gap be as small as possible within the range that can be conveyed to the area. Specifically, the development gap is, for example, 1
It is preferable to select from within the range of 00 to 1000 m.

Here, the development area refers to an area where the toner conveyed by the developer conveyance carrier can be transferred to the electrostatic latent image on the latent image carrier under electrostatic force. The development gap refers to the closest distance between the latent image carrier and the developer transport carrier in this development area.

Further, the carrier used in the present invention is a resin-coated carrier formed by coating magnetic particles with a resin containing at least 30% by weight or more of a fluororesin, and the thickness of the coating layer is, for example, 0.1 to ion on average. It is preferable to make it as thin as 0.3 to 4, and more preferably as thin as 0.3 to 4.
It is more preferable to set it as 3-2n. By reducing the thickness of the coating layer in this way, it becomes possible to form the developer layer on the developer transport carrier into a sufficiently thin layer.

The developer transport carrier for transporting the thin developer layer to the development area is not particularly limited, but for example, one having the same structure as the conventional one to which a bias voltage can be applied can be used. In particular, a structure in which a cylindrical developing sleeve carrying a developer layer and a magnetic roll having a plurality of magnetic poles is preferably used. In a developer transporting carrier having such a structure, the rotation of the magnetic roll causes the developer layer supported on the surface of the developing sleeve to move in an undulating manner, so that new developer is transported one after another. Moreover, even if there is some unevenness in the thickness of the developer layer on the surface of the developing sleeve, the effect of this is sufficiently covered by the above-mentioned wavy undulations so that it does not become a problem in practice.

In the present invention, the developer layer formed on the developer transport carrier is an Fi layer, but in order to develop the electrostatic latent image with maximum efficiency using the thin developer layer, (a) magnetic Measures such as rotating the roll at high speed, (b) applying an alternating current bias voltage to the developing sleeve, and (c) reducing the closest distance between the latent image carrier and the developing sleeve, that is, the developing gap, etc. It is preferable to adopt it.

In the present invention, either a non-contact development method or a contact development method can be employed, and the non-contact development method is particularly preferably employed. That is, by making the developer layer on the developer transport carrier thin as described above, the development gap can be made sufficiently small, and the oscillating electric field required to fly the toner in the image area can be reduced. The bias voltage required for formation can be lowered. In this way, a sufficient oscillating electric field can be formed with a relatively low bias voltage, which also reduces toner scattering and prevents leakage of bias voltage from the surface of the developing sleeve. There are advantages. Furthermore, when the development gap is made smaller, the electric field strength formed in the development area by the electrostatic latent image formed on the latent image carrier increases, and as a result, subtle changes in gradation and small It also becomes possible to develop patterns well.

However, when the developer layer supported on the developer transporting carrier is formed into a thin layer, the amount of l/toner transported to the developing area is usually reduced, and as a result, the amount of l/toner carried on the latent image carrier is reduced. There is a risk that the amount of toner adhering to the latent image may decrease.

In order to avoid this, it is preferable to rotate the developing sleeve at high speed, thereby increasing the amount of toner conveyed to the developing area. However, when the linear velocity of the developing sleeve exceeds 10 times the linear velocity of the latent image carrier, the velocity component parallel to the developing surface of the latent image carrier becomes large in the toner conveyed to the development area. ,
Directionality may appear in the formed image, resulting in a decrease in image quality.

Considering these circumstances, it is assumed that at least 0.04 mg of toner is contained in the developer layer supported on the developing sleeve.
It is preferable that it exists at a ratio of approximately 1/cm".

For example, the linear velocity of the developing sleeve is V s (mm/s
), the linear velocity of the latent image carrier is Vd (mm/s),
The amount of toner per unit area in the developer layer supported on the developing sleeve is mL (mg / (m 2
), then l Vs/ Va l ·mt ≧0.
4 (mg/cm")lV5/Val≦10.

In order to further increase the development efficiency, l Vs/ Val ・mu ≧ 0.5 (
mg/cm”) IV!/V, +1 ≦8. Furthermore, from experimental facts, l Vs
/Val −mt ≧0.5 (mg/cm”)lvi
It was found that it is more preferable to set /vai≦5.

In addition, ML A (mg/0m3) per unit volume of toner constituting the developer layer carried on the developing sleeve
) and the total surface area B (cs+2) of the carrier, the ratio A/B is preferably 0.5 to 2.

When the developing process is performed under the above-mentioned preferable conditions, the toner in the developer layer carried on the developing sleeve can be efficiently (adhered to the electrostatic latent image on the layered image carrier). It is possible to perform stable development,
In the end, it is possible to form an image of significantly superior quality.

The means for forming the above-mentioned thin developer layer on the developing sleeve is not particularly limited, and various configurations can be used. Specifically, a means for regulating the thickness of the developer layer by elastically pressing an 'iij layer forming member such as a blade onto the developing sleeve, preferably a regulating plate made of a magnetic material is placed in constant contact with the developing sleeve. A means for regulating the thickness of the developer layer by placing a magnetic rod at a gap, for example, a means for disposing a magnetic rod close to the developing sleeve and regulating the thickness of the developer layer by a rotating magnetic field generated by the magnetic rod, or other means. Conventionally known means can be used.

In particular, from the viewpoint of preventing impurities such as dust, fibers, paper dust, toner or carrier aggregates contained in the developer from entering the development area, a pressure contact plate is made in a light elastic contact with the development sleeve. A thin layer forming member consisting of the following can be preferably used. This thin layer forming member is preferably an elastic plate that is pressed against the developing sleeve so that its tip faces upstream in the rotational direction of the developing sleeve, and the developer is transferred between the elastic plate and the developing sleeve. A thin developer layer can be formed by passing the developer through the developer.

Figure 4 shows the gap between the tip of the elastic plate and the developing sleeve (proportional to the opening area) and the amount of developed material carried on the developing sleeve per unit area when such an elastic plate is used. It is a diagram showing the relationship with the dosage amount.

As can be understood from the figure, when the gap between the tip of the elastic plate and the developing sleeve exceeds a certain value, the amount of developer carried on the developing sleeve per unit area varies depending on the size of the gap. It will show a stable value without any fluctuation. In such a stable state, a sufficient amount of toner can be transported to the development area for developing the electrostatic latent image.

As can be understood from the results shown in Figure 4, by setting the gap between the tip of the elastic plate and the developing sleeve to 0.08n++w or more, even if there are variations in accuracy or mechanical accuracy, the installation can be performed with a certain amount of Toner can be stably transported to the development area. Further, it is preferable to set the gap between the tip of the elastic plate and the developing sleeve to 0.1 mm or more, since this further increases stability.

However, in order to form a thin developer layer, there is a preferable upper limit for the gap between the tip of the elastic plate and the developing sleeve, and specifically, it is preferably 51 or less. If the gap exceeds 51, the thickness of the developer layer may become non-uniform.

FIG. 1 is an explanatory diagram showing an example of a suitable developing device that can be used to carry out the developing method of the present invention.

In the figure, 20 is a latent image carrier in the form of a rotating drum, 2 is a housing, 3 is a developing sleeve, and 4 is a total of 8 magnetic poles in which N and S poles are alternately arranged along the circumference. The developing sleeve 3 and the magnetic roll 4 constitute a developer transport carrier. 5 is a thin layer forming member, 6 is a fixing member of the thin layer forming member 5, 7 is a Nu-th stirring member, and 8 is a second stirring member. 9 and IO are rotating shafts of the stirring members 7 and 8, 11 is a replenishment toner container, 12 is a toner replenishment roller, 13 is a developer reservoir, 14
15 is a bias power supply, 15 is a development area, T is a toner, and D is a developer.

In such a developing device, the developer pool in the developer reservoir 13 is divided into a first stirring member 7 that rotates in the direction of the arrow, and a second stirring member that rotates in the opposite direction so that the stirring areas overlap without colliding with each other. The developer is sufficiently agitated and mixed by the member 8, and is adhered to the surface of the developing sleeve 3 by the conveying force of the developing sleeve 3 rotating in the direction of the arrow and the magnetic roll 4 rotating in the opposite direction.

A plate-shaped thin layer forming member 5 made of an elastic material is held in pressure contact with the surface of the developing sleeve 3 on one side near the tip thereof. The thin layer forming member 5 is held by a fixing member 6 extending from the housing 2. The thickness of the developer layer conveyed to the development area 15 is regulated by the layer forming member 5, and the developer layer is formed into a thin layer.

The developer layer thus formed into a thin layer preferably faces the electrostatic latent image formed on the latent image carrier 20 rotating in the direction of the arrow with a small gap therebetween, so to speak, in a non-contact manner. The toner in the developer layer is conveyed to the development area 15 in such a state that only the toner in the developer layer is selectively formed into an electrostatic latent image while being acted on by an oscillating electric field generated by a bias electrode a14 containing an alternating current component in the development area 15. electrostatically adheres to
A toner image is thus formed.

Note that the thickness of the developer layer can be measured, for example, as follows. In other words, using a "Nikon Profile Projector" (manufactured by Nippon Kogaku), the positions of the image projected onto the screen of the developing sleeve and the image projected onto the screen with a thin developer layer formed on the developing sleeve were compared. The thickness of the layer can be determined by

The thin layer forming member 5 is fixed at one end by a fixing member 6 and given elasticity, and can be formed of, for example, magnetic or non-magnetic metal, metal compound, plastic, rubber, etc., and its thickness is extremely thin. It is preferable that
Preferably, the thickness is uniform. Specifically, the thickness is preferably 50 to 500 pl.

The thin layer forming member 5 is elastically pressed against the developing sleeve 3 on one side near its tip, and carriers are preferably passed one by one at the contact position between the thin layer forming member 5 and the developing sleeve 3. Do it like that! General shipping amount will be regulated. Impurities in the developer solution, Q1 substances in the carrier or toner, etc. are prevented from entering the development area 15 by the thin layer forming member 5, and therefore the developer layer conveyed to the development area 15 is in a thin layer form. The thickness becomes uniform and stable.

In the developing method of the present invention, a resin-coated carrier coated with a resin containing a fluororesin in a specific proportion or more is used, so even if the carrier has a small diameter, it has good fluidity due to the good surface condition of the coating layer. Therefore, the thickness regulating function of the thin layer forming member 5 is sufficiently well exhibited, and the developer layer conveyed to the image formation area 15 can be made into a sufficiently uniform and thin layer. Furthermore, since the release property of the carrier coating layer is good, for example, even if the developer is subjected to strong pressure by the thin layer forming member 5, the so-called filming phenomenon in which toner substances adhere to the carrier does not occur. Prevented.

Furthermore, the amount of developer conveyed to the developing area 15 can be sufficiently controlled by changing the pressing force and contact angle of the thin layer forming member 5 against the sleeve 3.

In general, the toner and carrier constituting the developer are advantageous in that the smaller the diameter, the higher the resolution of the resulting image and the better the gradation reproducibility. For example, even when using a two-component developer composed of a toner with a weight average particle size of 5μ or less and a carrier with a weight average particle size of 50μ or less, or even 30μ or less, the triple layer forming member 5 It is possible to automatically remove impurities, agglomerates, etc. from the developer, and form a uniform and thin developer layer. Furthermore, even when using a carrier with a small diameter having a weight average particle size comparable to that of the toner, the thin layer forming member 5 eliminates the contamination of impurities in the same way as described above, and forms a uniform and thin developer layer. can be formed.

On the other hand, in order to prevent the carrier from adhering to the latent image carrier 20, it is recommended to use a carrier with a large average particle diameter so that the carrier is held on the developer transport carrier by strong magnetic force. Therefore, it is preferable.

Taking these circumstances into consideration, it is advantageous to use a carrier with a weight average particle diameter of about 50 to 100 μm. In this case, the thin layer forming member 5 forms a sufficiently uniform and thin developer layer. can be formed, and carrier adhesion to the latent image carrier 20 can be sufficiently prevented. On the other hand, when a carrier with an excessively large weight average particle size is used, the height of the brush-like ears (magnetic brush) due to the carrier in the developer layer increases, the layer becomes rougher, and the developability decreases. do.

In addition, in order to make the carrier capable of receiving strong magnetic force despite its small diameter, the magnetization of the carrier is preferably 5 to 200 eta/g, more preferably 10 to 10,100 e/g. It is particularly preferably 15 to 30 eIlu/g.

When the magnetization of the carrier is too small, a good magnetic blank may not be formed, and when the magnetization is too large, the effect of the oscillating electric field may not be sufficiently exerted, making it difficult to form a good image. .

FIGS. 2A and 2B are an explanatory perspective view and an explanatory front view showing an example of a specific structure of the stirring members 7 and 8. FIG.

In the figure, 7a, 7b, and 7c are stirring blades of the first stirring member 7, and 8a, 8b, and 8c are stirring blades of the second stirring member 8, and their specific form is not particularly limited, but
For example, it is preferable to select a form such as a square plate blade, a disc blade, or an elliptical plate blade. These stirring blades are fixed to rotating shafts 9 and 10, respectively, at different angles and/or positions.

These two stirring members 7 and 8 are configured so that the stirring areas overlap without the stirring blades colliding with each other, so that sufficient stirring can be performed in the left and right directions in FIG. Since each of the stirring blades is fixed in a tilted state with respect to the rotor, stirring in the front and rear directions in FIG. 1 can be sufficiently performed. Therefore, the toner T replenished from the replenishment toner container 11 via the replenishment roller 12 is uniformly mixed into the developer solution in a short time.

The toner and carrier are sufficiently triboelectrically charged by the stirring members 7 and 8 as described above, and these developers are adhered and held onto the developing sleeve 3 by magnetic force, and then the thin layer forming member 5 develops a thin layer. It is considered to be an agent layer.

This developer layer is conveyed in one direction by the rotation of the developing sleeve 3, and is subjected to a magnetic bias having a vibration component by the rotation of the magnetic roll 4 in the opposite direction, while being transported in a complex manner such as rolling on the developing sleeve 3. Therefore, when the developer layer conveyed to the development area 15 is subjected to the action of an oscillating electric field, preferably in a non-contact manner with respect to the electrostatic latent image formed on the latent image carrier 20, , toner adhesion to the electrostatic latent image can be performed satisfactorily.

In the present invention, the thickness of the developer layer is preferably 10 to 10.
Since it is made into an extremely thin layer of about 500 μm, the development gap between the latent image carrier 20 and the developing sleeve 3 can be reduced to, for example, about 500 trm, and development by a so-called non-contact development method is possible. I can do it well.

When the development gap is made small in this way, the electric field strength in the development area 15 becomes large, so that sufficient development can be performed even if the bias voltage applied to the development sleeve 3 is made small. This has the advantage of reducing voltage leakage, etc.

Furthermore, since the contrast of the electrostatic latent image is increased, the resolution or quality of the image obtained by development is generally improved.

In addition, in the present invention, when developing is performed using a non-contact development method, only the toner is selectively flown toward the electrostatic latent image surface and developed, so that the development is performed by selectively flying toward the electrostatic latent image surface. Adhesion of the carrier is prevented, and as a result, deterioration in image quality can be prevented. In addition, since the magnetic brush does not rub the electrostatic latent image surface, there is a risk that the surface of the latent image carrier may be damaged or a phenomenon called "brush marks" (patterns that look like they have been swept with a broom) may occur. As a result, the resolution and gradation reproducibility are good, and a sufficient amount of toner can be attached to the electrostatic latent image.

Furthermore, the developing method of the present invention can be preferably applied to multicolor development in which development is repeatedly performed on a latent image carrier on which a toner image is formed.

The developer used in the present invention is a two-component developer comprising a toner and a resin-coated carrier formed by coating magnetic particles with a resin containing at least 30% by weight of a fluororesin.

A toner is a powder particle containing toner components such as a colorant in a binder resin.

As the binder resin for the toner, for example, polyester resin, styrene-acrylic resin, etc. can be preferably used.

The polyester resin preferably used as the binder resin of the toner is obtained by condensation polymerization of an alcohol monomer and a carboxylic acid monomer, and the alcohol monomers used include, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1.2-propylene glycol, 1.3-propylene glycol, 1
, 4-butanediol, neopentyl glycol, 1.
Diols such as 4-butynediol, 1,4-bis(hydroxymethyl)cyclohexane, and etherified bisphenols such as bisphenol A1 hydrogenated bisphenol A1 polyoxyethylenated bisphenol A1 polyoxypropylenated bisphenol A, etc. dihydric alcohol monomers. Examples of carboxylic acid monomers include maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, cepatic acid, Examples include malonic acid, anhydrides of these acids, dimers of lower alkyl esters and ruic acid, and other divalent organic acid monomers.

As the polyester resin preferably used as the binder resin of the toner, not only the above-mentioned polymers made only of difunctional monomers but also polymers containing components made of trifunctional or higher polyfunctional monomers may be used. suitable. Examples of such polyfunctional monomers, such as trivalent or higher polyhydric alcohol monomers, include sorbitol, 1.2, 3.6-
Hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol,
■, 2゜5-pentanetriol, glycerol, 2-
Methylpropanetriol, 2-methyl-1,2,4-
Mention may be made of butanetriol, trimethylolethane, trimethylolpropane, 1,3.5-trihydroxymethylhensen, and others.

In addition, examples of heavy polyvalent carboxylic acids of trivalent or higher valence include 1,2.4-benzenetricarboxylic acid, 1°3.5-
Benzenetricarboxylic acid, 1,2.4-cyclohexanetricarboxylic acid, 2,5.7-naphthalenetricarboxylic acid, 1,2.4-naphthalenetricarboxylic acid, 1,2.
4-butanetricarboxylic acid, 1.2.5-hexanetricarboxylic acid, 1.3-dicarboxyl-2-methyl-2
-methylenecarboxypropane, tetra(methylenecarboxy)methane, 1,2,7.8=octanetetracarboxylic acid, Empol trimer acid and anhydrides of these acids, and others.

As the above-mentioned styrene-acrylic resin, for example, α is described in JP-A-50-134652.

Contains β-unsaturated ethylenic monomer as a structural unit,
and the weight average molecule (jlM- and the ratio M of Mn to the number average molecule)
A resin having a w/Mn value of 3.5 or more can be preferably used. Specific examples of such α,β-unsaturated ethylenic monomers include styrene, O-methylstyrene,
m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p -n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, p-methkinstyrene, p-phenylstyrene, p-chlorostyrene,
3. Aromatic vinyl monomers such as 4-dichlorostyrene; for example, methyl acrylate, methyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, acrylic acid Acrylic acid esters such as lauryl, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacrylate n-butyl acrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylamino methacrylate Methacrylic ester acids such as ethyl and diethylaminoethyl methacrylate; Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl fluoride; Vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, etc. Vinyl esters; others can be mentioned.

Note that the values of number average molecule 1Mn and weight average molecular weight M- in a polymer can be measured by various methods, and there are slight variations depending on the measurement method, but in this specification, the values of number average molecule fiMn and weight Average molecular weight M
- is defined as the value obtained by the following measurement method.

That is, each of these values is a value measured by gel permeation chromatography (GPC) under the conditions described below.

At a temperature of 40 DEG C., a solvent (tetrahydrofuran) is flowed at a flow rate of 1.2 d/min, and 3n+g of a tetrahydrofuran sample solution with a concentration of 0.2 g/20- is injected as a sample weight to perform measurements. When measuring the molecular weight of a sample, select measurement conditions in which the molecular weight of the sample falls within a range in which the logarithm of the molecular weight and the count number of a calibration curve created using several types of monodispersed polystyrene standard samples form a straight line.

The reliability of the measurement results is determined by the N
B5706 Boristyrene standard 1! Since the sample has a weight average molecular weight Mw = 28.8 x 10', the average molecular weight IMn =
This can be confirmed by calculating 13.7 x 10'.

Further, any GPC column may be used as long as it satisfies the above conditions.

Specifically, for example, TSK-GEL, GMH (manufactured by Toyo Soda Co., Ltd.), etc. can be used.

The binder resin used in the toner preferably has a softening point Tsp of 80 to 160°C, particularly preferably 100 to 150°C. Also, the glass transition point Tg is 40
It is preferably ~80°C, particularly preferably 50~
The temperature is 70°C. By using such a binder resin, it is possible to obtain a toner that has excellent low-temperature fixing properties and excellent adhesion properties, and as a result, it is possible to achieve good development and to form images at high speed. becomes possible.

Unless otherwise stated, the softening point Tsρ is measured using a flow tester rCFT-500 model (manufactured by Konsei Seisakusho).
Measurement conditions: load 20kg/cm2, nozzle diameter 1mm
, nozzle length lnv+, preheated at 80°C for 10 minutes,
! When measuring and recording sample "tlcn+" (weight expressed as intrinsic specific gravity sawoh
When , the temperature is h/2.

In addition, the glass transition point Tg is the differential scanning calorimeter "low temperature D
Using SCJ (manufactured by Rigaku Denki Co., Ltd.), the heating rate was 10℃/
The temperature at the intersection of the extension line of the Hass line below the glass transition point of the DSC thermogram in the glass transition region and the tangent line showing the maximum slope from the rising part of the peak to the top of the peak when measured in minutes. This is the value defined as the glass transition point.

The toner used in the present invention contains a colorant and other toner components added as necessary in a binder resin.

As a coloring agent, carbon black, nigrosine dye (
C, 1, 50415 B'), Aniline Blue (C
,I.

m 50405), Calco Oil Blue (C, 1, N
n azoicBIue3), chrome yellow (c, +
, 14090), ultramarine blue (Cj,
Kan 77103), DuPont Oil Red (C91, N
26105), quinoline yellow (C, 1, 47005), methylene blue chloride (C, IJ
&152015), Phthalocyanine Blue (C,1,1
Ik174160), malachite green offsalate (C,I.

Floor 42000) - Lamp blank (C, 1, magnetic 7726
6), Rose Hengar (C, 1, ll & L45435)
, mixtures thereof, and others. These colorants are preferably contained in a sufficient proportion to form a visible image with sufficient brightness, and usually the toner contains 10
The amount is preferably about 1 to 20 parts by weight relative to 0 parts by weight.

Further, it is preferable that the toner contains various release agents in order to prevent toner substances from adhering to the carrier.

Examples of such mold release agents include polyolefins, fatty acid metal salts, fatty acid esters, partially saponified fatty acid esters,
Examples include higher fatty acids, higher alcohols, liquid or solid paraffin waxes, amide waxes, polyhydric alcohol esters, silicone varnishes, aliphatic fluorocarbons, etc., especially when measured by the ring and ball method specified in JIS K2531-1960. Softening point of 80-18
A temperature of 0°C is preferable, and a temperature of 70 to 160°C is particularly preferable. These mold release agents can be used alone or in combination of two or more.

Examples of the polyolefin include polypropylene,
Resins such as polyethylene and polybutene can be used.

Examples of the fatty acid metal salts include metal salts of maleic acid and zinc, magnesium, calcium, etc.; metal salts of stearic acid and zinc, cadmium, barium, lead, iron, nickel, cobalt, copper, aluminum, magnesium, etc. Salt; dibasic lead stearate; oleic acid and zinc;
Metal salts of magnesium, iron, cobalt, copper, lead, calcium, etc.; metal salts of balmitic acid, aluminum, calcium, etc.; lead caprylate; lead caproate; metal salts of linoleic acid, zinc, cobalt, etc. Calcium ricinoleate; Metal salts of ricylinic acid and zinc, cadmium, etc., and mixtures thereof, etc. can be used.

As the fatty acid ester, for example, ethyl maleate, butyl maleate, methyl stearate, butyl stearate, cetyl palmitate, ethylene glycol monchnic acid ester, etc. can be used.

As the partially saponified fatty acid ester, for example, a partially saponified calcium monocitric acid ester can be used.

Examples of the higher fatty acids include dodecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, ricinoleic acid, arachidic acid, behenic acid, lignoceric acid, ceracoleic acid, and mixtures thereof. Can be done.

As the higher alcohol, for example, dodecyl alcohol, lauryl alcohol, myristyl alcohol, valmityl alcohol, stearyl alcohol, aracyl alcohol, hehenyl alcohol, etc. can be used.

Examples of the paraffin wax include natural paraffin, microcrystalline wax, synthetic paraffin,
Chlorinated hydrocarbons and the like can be used.

As the amide wax, for example, stearic acid amide, oleic acid amide, palmitic acid amide, lauric acid amide, behenic acid amide, methylene bis stearamide, ethylene bis stearamide, etc. can be used.

As the polyhydric alcohol ester, for example, glycerin stearate, glycerin resolute, glycerin monobehenate, sorbitan monostearate, propylene glycol monostearate, sorbitan triolate, etc. can be used.

As the silicone varnish, for example, methyl silicone varnish, phenyl silicone varnish, etc. can be used.

As the aliphatic fluorocarbon, for example, a low polymer compound of tetrafluoroethylene or hexafluoropropylene, or a fluorine-containing surfactant described in JP-A-53-124428 can be used.

The proportion of these mold release agents used is preferably 1 to 10 parts by weight based on 100 parts by weight of the binder resin.

Examples of other toner components include fluidizing agents such as silica particles, titania particles, and alumina particles; abrasives such as cerium oxide; lubricants such as zinc stearate; and charge control agents such as pigments or dyes. can.

The toner used in the present invention preferably has a weight average particle diameter of less than 201, particularly preferably 1 to 15x. By using a toner having such a particle size, it is possible to form an image with even better image quality.

On the other hand, if a toner with an excessively large weight average particle size is used, the resolution tends to decrease and gradation reproducibility may deteriorate, while if a toner with a too small weight average particle size is used, the toner may scatter. This may cause fogging and the like to reduce the clarity of the image.

In the present invention, the carrier constituting the two-component developer together with the toner contains at least three fluororesins, as described above.
This is a resin-coated carrier formed by coating magnetic particles with a resin containing 0% by weight or more.

Such a fluorine resin is not particularly limited, but it is preferably one that is soluble in a solvent and can be applied to the surface of the magnetic particles by a conventional coating method.

Specifically, the following can be preferably used.

(1) Vinylidene fluoride-tetrafluoroethylene copolymer (2) A polymer consisting of one vinyl coatel jIL (-CH, -CH± 0-R) with a fluorine atom substituted in the side chain represented by the following general formula .

(However, R7 is an alkyl group or an aralkyl group substituted with at least one fluorine atom.) (3) A polymer consisting of a vinyl ketone II form represented by the following general formula+CHz CHsCo-R.

(However, Rt is an alkyl group or an aralkyl group substituted with at least one fluorine atom.) (4) Two or more resins selected from the resins (1) to (3) above The fluororesin used to form the coating layer of the blended polymer carrier is as follows:
The above fluororesins may be used alone or in combination, or a mixture of the above fluororesins and other resins may be used. The other resin is preferably one that is highly compatible with the fluororesin, such as acrylic resin,
Examples include styrene resin, epoxy resin, urethane resin, polyamide resin, polyester resin, acetal resin, polycarbonate resin, phenol resin, vinyl chloride resin, vinyl acetate resin, cellulose resin, polyolefin resin, copolymer resins of these resins, blended resins, etc. be able to.

The content of the fluororesin in the coating resin is at least 30% by weight, preferably 40 to 100% by weight, and particularly preferably 50 to 100% by weight. If the content of fluororesin is less than 30% by weight,
The good properties of the fluororesin are not fully exhibited, and the triboelectric charging properties tend to become unstable.

In the resin-coated carrier used in the present invention, the magnetic particles as the core material to be coated are materials that are strongly magnetized in the direction of magnetic fields, such as ferrite, magnetite, iron, nickel, cobalt, etc., which exhibit ferromagnetic properties. Metals, alloys or compounds containing these metals, alloys that do not contain ferromagnetic elements but become ferromagnetic through appropriate heat treatment, such as Heusler alloys such as manganese-copper-aluminum or manganese-copper-tin. Particles made of a type of alloy called chromium dioxide or chromium dioxide can be used.

Note that ferrite herein is a general term for magnetic oxides containing iron, and is not limited to spinel-type ferrite represented by the chemical formula MO-FetOsCM (a divalent metal). Ferrite is particularly preferable for obtaining a carrier suitable for the purpose of the present invention because various magnetic properties can be obtained by changing the composition of the metal components contained in ferrite. In addition, since ferrite powder is an oxide, its specific gravity is smaller and lighter than metal powders such as iron powder and nickel powder, making it easier to mix and stir with toner, resulting in a uniform toner concentration in the developer. It is also suitable for optimizing the amount of charge of the toner. Moreover, ferrite powder has a specific resistance of 1
08 to 101 zΩ・cm, which is larger than iron powder, nickel powder, cobalt powder, etc., so even when the resin coating layer on the carrier surface is made as thin as about 0.5 trm, a high bias voltage is required in the development gap. It has the advantage that it is possible to obtain an insulating carrier that can be sufficiently used in a developing method that applies .

The ferrite preferably has a saturation magnetization of 10 to 40 emu/g in an external magnetic field for 10000 seconds, a coercive force of 0.1 to 1000 g, and a specific resistance of lXl0' to lXl0''Ω·c+++, Specific gravity is 4
．． It is preferable that the porosity is 0 to 5.5% and the porosity is 1.0 to 10%.

In manufacturing the resin-coated carrier used in the present invention, a solution in which a fluororesin is dissolved in a solvent, or a solution in which another resin is added and dissolved, is used, for example, by a dipping method.
It is applied to the surface of magnetic particles by a method such as a spray method or a fluidized bed method, then heated and dried to volatilize and remove the solvent, and the coated layer is cured during or after drying to form a coating layer.

Other additives may be added to the coating solution for forming the coating layer, if necessary. The solvent is not particularly limited as long as it dissolves the fluororesin or other resin added, but examples include aromatic hydrocarbons such as toluene and xylene; ketones such as acetone and methyl ethyl ketone; tetrahydrofuran, dioxane, and high-grade Alcohol or a mixed solvent thereof can be used.

It is preferable that the heating temperature required for curing the coating layer is usually 100 to 350°C.

Further, in order to accelerate drying or curing, a drying accelerator or curing accelerator made of an organic metal such as zinc octylate or dibutyltin oxide can also be used.

The thickness of the coating layer thus obtained is, for example, 0.1 to 10
It is preferable that it is μ, more preferably 0.3~
The amount is 4 μl, particularly preferably 0.3 to 2 n.

The resin-coated carrier used in the present invention is preferably spherical and has a weight average particle diameter of 100 u or less, particularly preferably 5 to 50 n. Resin wave I having such a preferred weight average particle size
By using a W carrier, resolution can be improved and tone reproducibility can be improved.

When using a carrier with an excessively large weight average particle size, it may be difficult to form a thin layer of developer on the developer transporting carrier, resulting in decreased image quality and image quality. There is a risk. On the other hand, if a carrier having a too small weight average particle diameter is used, there is a risk that the developability, triboelectric charging property, fluidity, etc. will be reduced, and there is also a risk that carrier scattering will occur.

Further, the resin-coated carrier used in the present invention has a specific resistance of 108 Ω·cvA or more, preferably 10'3 Ω.
・It is preferable that the insulating carrier has a resistance of 011 or more, more preferably 10” Ω. It is possible to sufficiently prevent the carrier from adhering to the surface of the body or the charge forming the electrostatic latent image from disappearing.

In the present invention, the weight average particle diameter of toner and carrier refers to a value measured with a "Coulter Counter" (manufactured by Coulter Inc.).

In addition, the specific resistance of magnetic particles and resin-coated carrier particles is determined by placing the sample particles in a container with a cross-sectional area of 0.50 cm and tapping the sample particles, and then placing 1k on the packed sample particles.
g/cm" load body to a thickness of approximately 1 mm, and a voltage of 10" to 10' V is applied between the load body and the bottom electrode.
It can be determined by applying an electric field of /cm and measuring the current value flowing at that time.

When preparing the two-component developer used in the present invention,
The mixing ratio of toner and carrier is preferably such that the total surface area of the toner and the total surface area of the carrier are approximately the same. For example, the weight average particle size of toner is 1 On.
When the weight average particle diameter of the carrier is 20 m, the toner concentration (weight ratio of toner to the entire developer) is preferably 5 to 40% by weight, particularly 8 to 2% by weight.
Preferably it is 5% by weight. That is, in the two-component developer used in the present invention, rather than the conventional developer in which many small-diameter toners are attached to the outer periphery of a large-diameter carrier, a small-diameter carrier equivalent to the toner is used. It is preferable to prepare a two-component developer by mixing the toner and the carrier at a ratio such that the total surface area of the toner and the total surface area of the carrier are approximately equal.

[Specific embodiments of the invention]

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

<Embodiment 1> FIG. 3 is an explanatory diagram schematically showing an example of an image forming apparatus that can be used to carry out the developing method of the present invention. The optical image of the original is irradiated onto the latent image carrier 20 through the mirror 22 and the lens 23, and an electrostatic latent image corresponding to the original is formed on the latent image carrier 20. The developing device A has a configuration as shown in FIG. 1, for example, and develops the electrostatic latent image formed on the latent image carrier 20, thereby forming a toner image.

The thus obtained toner image is neutralized by the exposure lamp 28 to make it easily transferable, and then transferred to the recording paper P by the transfer electrode 29.

The recording paper P is separated from the latent image carrier 20 by the separation electrode 30 and undergoes a fixing process in the fixing device 31, thereby forming a fixed image. On the other hand, the latent image carrier 20 is charge-eliminated by the removing electrode 32, and its surface is cleaned by the cleaning device 33.

The cleaning device 33 in this example includes a cleaning blade 34, and the toner scraped off by the cleaning blade 34 is collected by a roller 36.

A test was conducted to form an image by actually applying the developing method according to the present invention using the image forming apparatus shown in FIG.

Charcoal Prisoner 11 Shif Shihi I Installation (1) Carrier A Vinylidene fluoride-tetrafluoroethylene copolymer (copolymerization molar ratio = 80:20, intrinsic viscosity = 0.95
d! /g, manufactured by Daikin Industries, Ltd.) 26g was mixed with acetone-methyl ethyl ketone (mixed weight ratio = 1:1) mixed solvent 800 g.
- to prepare a coating solution.

This coating solution was applied to copper-zinc ferrite particles (particle size distribution range = is ~ 607/l, weight average particle size = 35p recommended) using a "Subira Coater" (Okada Seikosha!!), and the temperature A carrier having a coating layer containing a fluororesin was obtained by heat treatment at 100°C.

The thickness of the coating layer was 1.0μ layer. This will be referred to as "Career A."

The characteristics of this carrier A are as follows.

Weight average particle size: 3511N Magnetization: 20 emu/g (Measurement magnetic field: 1000
0e) Specific resistance, 1QIaΩ・C- or more (2) Carrier B In manufacturing carrier A, vinylidene fluoride-
A carrier having a coating layer containing a fluororesin having a thickness of 1.0μ and processed in the same manner except that a polymer made of a monomer represented by the following formula was used instead of the tetrafluoroethylene copolymer. I got it.

This will be referred to as "Career B."

(-CH2-CH± COCH2CHZ OCF z CF z H (however, the intrinsic viscosity of the polymer=0.59 dl/g) The characteristics of this carrier B are as follows.

Weight average particle size: 401 Magnetization: 20 emu/g (Measurement magnetic field: 1000
0e) Specific resistance, IQ 14Ω・C11 or more (3) Carrier C In the manufacture of carrier A, vinylidene fluoride
In place of the tetrafluoroethylene copolymer, a blend polymer of polymer (a) and polymer (b) shown below (weight ratio -7 = 3) was used, but the same process was performed to obtain a thickness of 1. ．．
A carrier having a coating layer containing On fluororesin was obtained. This will be referred to as "Carrier C."

Polymer (a): Vinylidene fluoride dotetrafluoroethylene copolymer (copolymerization molar ratio -80220, intrinsic viscosity -0.95a4/g) Polymer (b): Methyl methacrylate copolymer [acrylic Pet MFj (manufactured by Mitsubishi Rayon Co., Ltd.) The characteristics of this carrier C are as follows.

Weight average particle size: 42 μ Theoretical magnetization: 20 emu/g (Measurement magnetic field: 1000
0e) Specific resistance: 1O14Ω·0111 or more (4) Comparative carrier a The copper-zinc ferrite particles used in the manufacture of the carrier were used as the carrier. This will be referred to as "comparison carrier a."

The characteristics of this comparison carrier a are as follows.

Weight average particle size: 38μ Magnetization: 22 ea+u/g (Measurement magnetic field: 100
00e) Specific resistance, 1QloΩ・cam or more (5) Comparative carrier b In the manufacture of carrier A, vinylidene fluoride-
Instead of the tetrafluoroethylene copolymer, styrene resin (weight average molecular weight 1Mw: 71,000, number average molecular weight n: 32,000, glass transition mole g:
A carrier having a coating layer of 1.01 mm thick made of styrene resin was obtained by the same treatment except that 125'C) was used. This will be referred to as "comparison carrier b."

The characteristics of this comparative carrier b are as follows.

Weight average particle size: 30p ■ 6ff: 20 emu/g (Measurement magnetic field: 10
000s) Specific resistance: 10"Ω・C11 or more (6) Comparative carrier C In the manufacture of carrier A, vinylidene fluoride
Methyl methacrylate resin (weight average molecular iMw: 73,0
00, number average molecular weight Mn: 33,000, and glass transition point Tg: 121°C), the same treatment was performed to obtain a carrier having a coating layer of 1.0 μm thick made of methyl methacrylate resin. This is called “Comparative Career C”
”.

The characteristics of this comparison carrier C are as follows.

Weight average particle size: 40n Magnetization: 18 emu/g (Measurement magnetic field: 1000
0e) Specific resistance: to14Ω・clI or higher (1) Black toner A Styrene-acrylic resin rR-54 (manufactured by Block Chemical Co., Ltd.)
100 parts by weight, polypropylene "Viscol 660 P"
J (Sanyo Chemical Industries, Ltd.')A) 31tl part,
Carphone black "Mogul LJ (manufactured by Kabonoto) 10 parts by weight, positively chargeable charge control agent rP-51J (
After mixing 2 parts by weight (manufactured by Orient Chemical Co., Ltd.) using a Henschel mixer, the mixture was thoroughly kneaded at a temperature of 140°C using three rolls, then cooled and coarsely pulverized, then finely pulverized using a 7-mill mill, and further classified. Therefore, the particle size distribution range is 6~
A positively chargeable black toner powder having a weight average particle size of 30 μm and a weight average particle size of 10 μm was obtained.

To 100 parts by weight of this black toner powder, 0.6 parts by weight of hydrophobized titania fine particles rT-805J (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed in a Henschel mixer to form a positively chargeable black toner. Obtained. This is referred to as "black toner A". The quietness density of this black toner A was 0.38 g/cm3.

Note that quietness density is an indicator of fluidity,
The higher the quietness density, the higher the fluidity.

(2) Yellow Toner B A yellow toner having a weight average particle size of 11 μm was obtained by carrying out the same procedure as above except that a yellow pigment rPigsent Yellow J was used instead of carphone black in the production of a black toner. This is called [Yellow Toner BJ]. The quietness density of this yellow toner B is 0.288
/cmff.

(3) Magenta Toner C In the production of black toner, magenta pigment rPer+*anent Carmin is used instead of carbon black.
A magenta toner having a weight average particle size of llx was obtained by the same treatment except that "e F-5B" was used. This is called "Magenta Toner C". The quietness density of this magenta toner C was 0.29 g/cm3.

(4) Cyan Toner D In the production of black toner, cyan pigment r Pig+ment Rlue I J is used instead of carbon blank.
The process was carried out in the same manner except that the weight average particle size was 1 bn.
+ cyan toner was obtained. This is called "Cyan Toner D". The quietness density of this cyan toner D is 0.27g/
cm". Preparation of Developer Developers L to 3 and Comparative were prepared by combining each of the carriers A-C and comparative carriers a"-c with black toner, each having a toner concentration of 12% by weight. Developers 1 to 3 were prepared.

Also, yellow toner B1 magenta toner 〇.

Color developers 1 to 3 each having a toner concentration of 12% by weight were prepared by combining each of cyan toner D and carrier A.

A test was conducted to form 30,000 copies of images using each of these developers under the development conditions shown below. The toner charge amount, fog, carrier adhesion to the latent image carrier, image missing, image unevenness, and toner substance adhesion to the carrier surface (toner spent) were investigated. The results are shown in Table 1 below.

[Development conditions (reverse development)]

0 latent image carrier: drum-shaped photoreceptor made of selenium with a diameter of 100 mm, O&? l Speed: 100 +nm/sO surface position: +800V (non-image area) ~ OV (image area) 0 Diameter of developing sleeve: 25 mm Linear speed of O developing sleeve 4250 mm/S (forward direction) 0 Number of magnetic roll poles : 8 poles 0 Rotation speed of magnetic roll: 120 Orpm O Thin layer forming member: An elastic plate made of urethane rubber with a thickness of 3 cm is elastically pressed against the surface of the developing sleeve 0 Development gap = 500 μm 0 Thickness of developer layer 2400 m (maximum value) O Toner concentration in developer = 12% by weight 0 Toner content in developer layer formed on developing sleeve = 0.3 mg/cm'' 0 DC bias voltage: 600 to 700 vO AC Bias voltage: 20.5 to 2 kV (frequency: 2 kHz, peak-to-peak value) The evaluation methods are as follows.

Taki 1ヱ It was measured by a known blow-off method.

Yubuyu The fixed image was visually judged.

Carrier adhesion to latent image carrier The surface of the latent image carrier was visually judged.

Image missing The fixed image was visually judged.

Image unevenness The fixed image was visually judged.

Adhesion of toner substances to the carrier (toner spelling) The determination was made by observing the carrier particles using an optical microscope.

As can be understood from the results in Table 1, when the developing method according to the present invention is applied using Developers 1 to 3, the toner exhibits an appropriate amount of charge, does not cause fogging, and does not carry latent images. There is no carrier adhesion to the body, and no image missing or unevenness occurs, resulting in the formation of clear images with high resolution and good gradation reproducibility.

Furthermore, even after 30,000 sheets have been formed, if the developing method according to the present invention is applied using Developers 1 to 3, the change in the amount of charge of the toner is small, and images as clear as in the initial stage of image formation can be obtained. can be formed.

Furthermore, when the degree of contamination inside the device was examined, it was found that contamination by toner and carrier was extremely small. this is,
The fluororesin used as the resin for forming the coating layer of the carrier used in the present invention has a lower critical surface tension than the other resins used in the manufacture of the comparative carrier, and therefore the toner material is less likely to be attached to the carrier surface. This is because adhesion is less likely to occur. Further, the developing effect due to the bias voltage was sufficiently developed.

On the other hand, when Comparative Developer 1 was used,
Even in the initial stage of image formation, the amount of charge was low, and the resulting images were foggy, uneven, and unclear. After forming 30,000 sheets, the amount of charge of the toner further decreased, and the above-mentioned drawback became even more significant. In addition, carrier adhesion to the latent image bearing member was observed, and missing images also occurred.

In addition, when Comparative Developer 2 was used, the amount of charge was slightly low at the initial stage of image formation, and the resulting image was unclear with image blanking and image unevenness. After 30,000 sheets have been formed, the amount of charge on the toner further decreases, and the above-mentioned drawbacks become even more significant.
Furthermore, significant fogging occurred, and some carrier adhesion to the latent image bearing member was observed.

Further, when Comparative Developer 3 was used, in the early stage of image formation, image blanking and image unevenness were observed in the resulting image, and carrier adhesion to the latent image bearing member was observed. After forming 30,000 sheets, the amount of charge of the toner was significantly reduced, and the resulting images had significant fog, and were unclear with missing images and unevenness. Further, some carrier adhesion to the latent image bearing member was also observed.

3) Recreation i Next, a test was conducted in the same manner as in Actual Test 1 above, except that the developing conditions were changed as shown below, and the same results as in Actual Test 1 were obtained.

[Development conditions (regular development)]

0 latent image carrier: diameter 1 comprising an organic photoconductive photosensitive layer
40mm drum-shaped photoreceptor 0 linear speed: 60ffil/S Q surface potential knee 700V (image area) ~ -50■ (non-image area) 0 Development sleeve diameter: 201W 0 Development sleeve linear speed: 250! +l+I/S
(Forward direction) Number of magnetic rolls: 28 poles Rotation speed of the magnetic roll: 101,000 rp A 0.1 mm thick elastic plate made of thin layer forming member Nilin bronze plate is elastically pressed against the surface of the developing sleeve 0 Development Thickness of developer layer: 400 m (maximum value) 0 Toner concentration in developer: 12-layer bag part 0 Toner content in developer layer formed on developing sleeve: 0. 4 mg/am” 0 DC bias voltage Knee 100 to -200 ■O AC bias voltage = 0.5 to 2.5 kV (Frequency: 2 kHz
z, peak-to-peak value) (Example 2) FIG. 5 is an explanatory diagram schematically showing another example of an image forming apparatus that can be used to carry out the developing method of the present invention. The illumination light source l, mirror 22, lens 23, and -dimensional color CCD photographing element 24 are integrated into a unit, and the image input section IN is connected to the drive device (
(not shown) in the direction of arrow X, and the CCD photographing element 24 reads the document. Note that the image input section IN may be fixed and the document 25 may be moved by moving the document table.

The image information read by the image input section IN is sent to the image processing section T.
R is used to convert the data into data suitable for recording.

The laser optical system 26 forms an electrostatic latent image on the latent image carrier 20 in the following manner based on the above image data.

That is, the surface of the latent image carrier 20 is uniformly charged by the scorotron charge electrode 27, and then the surface is charged by the laser optical system 26.
A light image of the original according to the recorded data is irradiated onto the latent image carrier 20 through the lens, thereby forming an electrostatic latent image corresponding to the original on the latent image carrier 20.

This electrostatic latent image is first developed by the developer bag fiA in which yellow toner B is stored. The latent image carrier 20 on which the toner image of yellow toner B has been formed is uniformly charged again by the scorotron charging electrode 27 and is irradiated with an original light image according to recording data of another color component.

The static fifh fl image thus formed is developed by a developing device B containing magenta toner 〇.

As a result, a two-color toner image of yellow toner B and magenta toner C is formed on the latent image carrier 20. Subsequently, in the same manner as described above, a toner image of cyan toner D and a toner image of black toner A are sequentially superimposed, thereby forming four color toner images on the latent image carrier 20. Note that the developing devices A, B, C, and D all have the same configuration as the developing device shown in FIG.

The thus obtained multicolor toner image is neutralized by the exposure lamp 28 to be easily transferred, and then transferred to the recording paper P by the transfer electrode 29. The recording paper P is separated from the latent image carrier 20 by the separation electrode 30,
A fixing process is performed by the fixing device 31, thereby forming a fixed image. On the other hand, the latent image carrier 20 is charge-eliminated by the removing electrode 32, and its surface is cleaned by the cleaning device 33.

The cleaning device 33 in this example includes a cleaning blade 34 and a fur brush 35.

These are the latent image carrier 20 during the image forming process.
When the final multicolor toner image is formed on the latent image carrier 20, during this process the leaning field 34 and the fur brush 35 are kept in a non-contact state with the latent image carrier 20. When contacted, the toner remaining on the latent image carrier 20 is scraped off after the toner image is transferred. Thereafter, the cleaning blade 34 separates from the latent image carrier 20, and a little later, the fur brush 35 separates from the latent image carrier 20. The fur brush 35 has a function of removing toner remaining on the latent image carrier 20 when the cleaning blade 34 leaves the latent image carrier 20. , 36 are rollers that collect the toner scraped off by the blade 34.

A specific example of the laser optical system 26 is shown in FIG.

In the figure, 37 is a semiconductor laser oscillator, 38 is a rotating polygon mirror, and 39 is an rθ lens.

In addition, in such an image forming apparatus, in order to align each image, an optical mark is placed on the latent image carrier 20, and the timing for starting exposure is determined by reading it with an optical sensor or the like. It is preferable to do so.

Using the image forming apparatus shown in FIG. 5, a test was conducted in which 30,000 copies of images were actually formed using the developing method according to the present invention. After that, the toner charge amount, fog, carrier adhesion to the latent image carrier, image missing, and image unevenness were investigated. The results are shown in Table 2 below.

In addition, in this live-action test, based on the conditions shown below, a development method using the reversal development method as shown in FIG. 6 was adopted, and the operation timing shown in FIG. The image forming process was carried out based on the following.

To explain FIG. 6, FIG. 6 shows changes in the surface potential of the latent image carrier, and is an example in which the charging polarity is positive. PH indicates the exposed area of the latent image carrier, DA indicates the unexposed area of the latent image carrier, and DUP indicates the increase in potential caused by the attachment of the positively charged toner T1 to the exposed area PH during the first development.

The latent image carrier is uniformly charged by a scorotron charger, and has a constant positive surface potential E as shown in FIG. Next, a first image exposure is performed by an exposure source such as a laser, a cathode ray tube, or an LED, and as shown in FIG. The electrostatic latent image thus formed is developed by development=2 to which a positive bias voltage approximately equal to the surface potential E of the unexposed area is applied. As a result, the positively charged toner T1 adheres to the exposed portion PH, which has a relatively low potential, and a first toner image is formed, as shown in FIG. The area where this toner image is formed has a potential increased by DUP due to the attachment of the positively charged toner T1, but does not have the same potential as the unexposed area DA. Next, the surface of the latent image carrier on which the first toner image has been formed is charged a second time by a charger, and as a result, the toner T
Regardless of the presence or absence of I, the surface potential E is uniform.

A second image exposure is performed on the surface of this latent image carrier, and
An electrostatic latent image is formed as shown in FIG. This electrostatic latent image is developed with the positively charged toner T2 of a different color from the toner T1 in the same manner as described above, and a second toner image is formed as shown in FIG.

By repeating the above process, a multicolor toner image is formed on the latent image carrier. Next, this multicolor toner image is transferred to a recording paper, and then heated or pressurized to fix it, thereby obtaining a multicolor recorded image. The latent image carrier is then cleaned of residual toner and charges on its surface, and then used for forming the next multicolor image. It is also possible to apply a method of directly fixing a multicolor toner image onto a latent image carrier. In the developing method shown in FIG. 6, it is preferable that the process shown in FIG.

[Development conditions (reversal development) and other conditions] 0 Latent image carrier: 140 m in diameter comprising a selenium-tellurium photosensitive layer
m drum-shaped photoreceptor 0 linear velocity: 60nuw/s O surface type position: +700V (non-image area) to +50V (image area) O exposure light source: semiconductor laser (wavelength: 7B0n)
m, tgN density: 16 dots/mm) 0 Configuration of developing device A-D Diameter of developing sleeve: 20111+1 Linear speed of developing sleeve: 250 mm/S (forward direction) Number of magnetic roll poles: 8 poles Rotational speed of magnetic roll : 800rpm thin layer forming member:
An elastic plate made of urethane rubber with a thickness of 3IIIfR is placed in elastic pressure contact with the surface of the developing sleeve.Developing gap: 0.3 mm Maximum magnetic flux density on the surface of the developing sleeve: 700 g
auss Developer layer thickness: 250 ttm (maximum value) Toner content in the developer layer formed on the development sleeve: 0
．． 3 mg/cm" DC bias voltage during development: +5oov AC bias voltage during development: 1.2kV (frequency: 2kHz
, peak-to-peak value) DC bias voltage when not developing:
o ■ AC bias voltage when not developing: 0.3 kV or more (frequency: 2kllz, peak-to-peak value) (when not developing, the magnetic roll and developing sleeve are stopped. Also, the developing sleeve is electrically floating) ) o Current fill: (Yellow) = (Magenta) = (Cyan) - (Black) 0 Transfer process: Corona discharge method o Fixing process: Heat roll method 0 Cleaning process: Blade and fur brush Table 2 As can be understood from the results, when the developing method according to the present invention is applied, the toner is suitable for band 7! j, I
J! , there is no capri, no carrier adhesion to the latent image carrier, and no image missing or unevenness, resulting in the formation of clear color images with high resolution and good gradation reproducibility. be able to.

Further, even after forming 30,000 sheets, a clear color image can be formed as in the initial stage of image formation. Furthermore, when the degree of contamination inside the device was examined, it was found that contamination by toner and carrier was extremely small.

<Embodiment 3> FIG. 8 is an explanatory diagram schematically showing another example of an image forming apparatus that can be used to carry out the developing method of the present invention. This image forming apparatus is configured to be able to form multicolor toner images all at once. Note that the only differences from the image forming apparatus shown in FIG. 5 are as follows.

(1) Charge electrodes 27A, 27B, 27C127D and helium-neon laser optical systems 26A, 26B, 26C126D are provided between each developing device A-D, and the development process using toner of each color is sequentially and continuously performed. I made it possible.

(2) The cleaning device 33 includes a cleaning blade 34 and a toner collecting roller 36, and the cleaning blade 34 is always placed in pressure contact with the latent image carrier 20.

(3) The conveyance path of the recording paper P is different.

In such an image forming apparatus, when forming a four-color image, for example, when the linear velocity of the latent image carrier 20 is the same, the image forming apparatus shown in FIG.
A fixed image can be formed approximately four times faster.

A test was conducted to form 30,000 copies of images by actually applying the developing method of the present invention using the image forming apparatus shown in FIG. When the toner charge amount, fogging, carrier adhesion to the latent image carrier, image blanking, and image unevenness were later investigated, good results similar to those of the actual photographic test 3 described above were obtained.

In this actual photographic test, the image forming process was carried out under the conditions shown below.

[Development conditions (reverse development) and other conditions] 0'/l
1iI image carrier: Drum-shaped photoreceptor with a diameter of 140 mm and provided with an AstSez photosensitive layer 0 linear velocity: 200 mm/s O surface type position near 00V (non-image area) to 50V (image area)
0 light source for exposure: helium-neon laser (wavelength: 6
32.8n, recording density = 16 dots/mn) 0 Configuration of developing device A-D Diameter of developing sleeve 720 mm Linear velocity of developing sleeve: 500e+m/s (forward direction) Number of magnetic roll poles: 8 rotation of magnetic roll Speed: 1500 rpm Thin layer forming member: An elastic plate made of urethane rubber and having a thickness of 3111 mm is elastically pressed against the surface of the developing sleeve.Developing gear, gear: 500n.Maximum magnetic flux density on the surface of the developing sleeve: 700g.
auss Thickness of developer layer = 400 μm (maximum value) Toner content in developer layer formed on developing sleeve 9: 0.4
B/cm2 DC bias voltage during development: 600 to 700 ■AC bias voltage during development: 0.5 to 2 kV (frequency: 2
kHz, peak-to-peak value) DC bias voltage when not developing: Ov AC bias voltage when not developing: 0.3 kV or more (frequency: 2 kHz, peak-to-peak value) (When not developing, magnetic roll and The developing sleeve stops. Also, the developing sleeve may be electrically floating.) 0 Development order: (Yellow) - Kumazenta) → (Cyan)
= (Black) 0 Transfer process: Corona discharge method 0 Fixing process: Heat roll method 0 Cleaning process: Blade method In addition, in this live-action test 4, the color development order is (black) - (yellow) with black first. The order may be - (magenta) - (cyan).

Although specific embodiments of the present invention have been described above, the developing method of the present invention is also preferably applicable to an apparatus capable of forming a multicolor toner image by performing image exposure once on a latent image carrier. can do.

In one example of such a device, a latent image carrier is preferably provided with a conductive member, a photoconductive layer, and an insulating layer including a filter layer made of a plurality of different types of filters. In this way, a multicolor toner image is formed.

That is, by charging the surface of the latent image carrier and performing imagewise exposure, an image is formed depending on the magnitude of the charge density at the interface between the insulating layer and the photoconductive layer, and by exposing the entire surface of the image to specific light, A potential pattern is formed on the filter layer of the latent image carrier, and the potential pattern is developed by a developing device containing toner of a specific color, thereby forming a monochrome toner image.

Subsequently, the latent image carrier is charged to smooth the potential pattern, and then the entire surface is exposed to a specific light different from the specific light to form a potential pattern on the filter layer of the latent image carrier. Developing is performed by a developing device containing toner of a specific color different from the toner color, whereby a toner image of a second color is formed on the latent image carrier in a state superimposed on the toner image of the first color. In carrying out this development process, it is necessary to use a non-contact development method for at least the second and subsequent development processes.

Thereafter, by repeating the above process as many times as necessary, toners of different colors can be attached to each filter layer of the latent image carrier, and as a result, a multicolor image can be formed. It is possible (Special application 1982-
No. 83096, No. 59-187044, No. 59-18
5440, 60-229524).

According to such a multicolor image forming apparatus, only one image exposure is required, so there is no possibility of color shift occurring.

In addition, the latent image carrier has a structure in which a filter is provided on the conductive substrate side and image exposure and full-surface exposure are performed from the filter side (
(See Japanese Patent Application No. 59-199547) or other configurations (see Japanese Patent Application No. 59-201.084). .

Furthermore, the photosensitive layer is not limited to a single layer, and may have a functionally separated structure consisting of a charge ordering layer and a charge transfer layer (Japanese Patent Application No. 1983
-245178).

The latent image carrier has a structure in which the photosensitive layer has a color separation function (Japanese Patent Application No. 59-201085, Japanese Patent Application No. 60-2451).
(see specification of No. 77).

[Brief explanation of drawings]

FIG. 1 is an explanatory sectional view showing an example of a developing device that can be used in carrying out the present invention, and FIG. 2E (a) and (b)
3 is a schematic diagram illustrating an example of a monochromatic image forming apparatus, and FIG. 4 is a diagram illustrating a developer thin layer forming member and a developer transport carrier. A graph showing the relationship between the gap and the amount of developer conveyed, FIG. 5 is a schematic diagram showing an example of a multicolor image forming apparatus, FIG. 6 is a flowchart for explaining the multicolor image forming process, and FIG. 7 8 is a schematic diagram showing another example of the multicolor image forming apparatus, and FIG. 9 is a schematic diagram showing an example of a laser optical system. . 3...Developing sleeve 4...Magnetic roll 5...
- Thin layer forming members 7, 8... Stirring member 14...
Bias electrode #15...Development area 20...Latent image carrier 21...Illumination light source 25...Document
28... Exposure lamp 29... Transfer electrode
30... Separation electrode 31... Fixing device 3
2... Static elimination electrode 33... Cleaning device P...
・Recording paper 34...Cleaning blade 26.26A, 26B, 26C, 26D...Laser optical system 27.27A, 27B, 27C, 27D...Charger A, B, C, D...Developing device $3 Zuko 4m Nogi! Buddha data table 1 tea 1 shiji (mm) 夛村 9 figure

Claims (1)

[Scope of Claims] 1) A developer layer of a two-component developer consisting of toner and carrier is formed on a developer transport carrier, and this developer layer is supplied to a development area where an oscillating electric field is generated. In a developing method for developing an electrostatic latent image on a latent image carrier, the developer layer formed on the developer transport carrier is a thin layer, and the carrier is a resin containing at least 30% by weight of a fluororesin. A method for developing an electrostatic latent image, comprising using a resin-coated carrier formed by coating magnetic particles. 2) The thickness of the developer layer is 2000 μm or less, preferably 1
The method for developing an electrostatic latent image according to claim 1, characterized in that the thickness is 000 μm or less, particularly preferably 10 to 500 μm. 3) The method for developing an electrostatic latent image according to claim 1, wherein the minimum value of the gap between the latent image carrier and the developer transport carrier in the development area is 100 to 1000 μm.