JPH01164960A - Developing method - Google Patents

Abstract

PURPOSE:To sufficiently and uniformly bring a colored grain to electrification and to obtain a distinct image by mixing and using a specific colored grain and an auxiliary grain electrified to the opposite polarity against said color grain. CONSTITUTION:At the time of supplying a developer 20 to a photosensitive drum 40 and converting an electrostatic latent image to a visible image, the developer 20 which contains a colored grain obtained by containing a colorant in a resin of >=50 deg.C glass transition point and 110-160 deg.C softening point and an auxiliary grain electrified to the opposite polarity against the electrification polarity of said colored grain is used. Subsequently, a developer formed by pressing this developer 20 against the surface of a developing sleeve 30 by an elastic blade 31 is allowed to face a photosensitive drum 40, and only the colored grain is allowed to adhere electrostatically to the electrostatic latent image. In such a way, the developer can be brought to triboelectrification sufficiently and uniformly, and a distinct image can always be obtained.

Description

[Detailed Description of the Invention] [Object of the Invention] - (Industrial Application Field) The present invention is directed to improving a developing method in an electronic copying machine, etc., and more specifically, to obtain a clear image. The present invention relates to a developing method that can be used.

(Prior Art) As a developing method in electronic copying machines, etc., toner and carrier are used to visualize an electrostatic latent image formed on an electrostatic image carrier made of a photoreceptor drum or dielectric material. Developing methods using any two-component developer have been widely used.

However, although this two-component developing method has the advantage that the image quality obtained is good, it has the following drawbacks.

(a) Toner receives a triboelectric charge due to mutual friction with the carrier, but if the toner is used for a long time, the surface of the carrier becomes contaminated with the toner composition, making it impossible to receive sufficient charge, resulting in poor image quality. changes. (b) It is necessary to adjust the mixing ratio of toner and carrier to a constant ratio, but as the mixing ratio changes during long-term use, the image quality of the image changes.

(c) Since hard materials such as iron powder with an oxidized surface, glass beads, and those coated with resin are used as carriers, the surface of the photoreceptor drum is damaged by these carriers and its lifespan is shortened. descend.

Therefore, in order to eliminate these drawbacks, various development methods using one-component developers consisting only of toner have been proposed, and among them, one-component developers called magnetic toner containing magnetic powder have been proposed. A developing method using

However, even in this method, (a) magnetic toner with relatively low resistivity is used, so when the developer on the electrostatic latent image is transferred to a support member such as paper, it is necessary to transfer the developer electrostatically to a supporting member such as paper. (2) The toner contains a large amount of magnetic powder, and (2) the toner cannot retain sufficient charge and good transfer cannot be obtained, especially in a humid atmosphere. Since this magnetic powder is generally made of black magnetite, it has the disadvantage that toners of colors other than dark colors cannot be obtained.

Therefore, recently, a developing method using a one-component toner that does not contain the magnetic powder used in the above-mentioned two-component developing method and has a high specific resistance has been developed, for example, as disclosed in U.S. Pat.
895847 July 1 [1a! , No. 3152012 Mei III, Equity Publication No. 41-9475, No. 45-287
This method has been proposed in Japanese Patent No. 7 and No. 54-3624, and has been put to practical use as a touchdown method, an impression method, a jumping method, and the like.

(Problems to be Solved by the Invention) However, in the conventional one-component developing method using only toner, which has been used in the two-component developing method described above, the occurrence of triboelectric charging is insufficient. However, there was a problem in that it was difficult to form a thin toner layer.

That is, in general, in the one-component development method, the toner charges one toner carrier (developing sleeve) efficiently and in a very short time, and does not destroy the electrostatic latent image formed on the photoreceptor drum or dielectric material. Sufficient amount of charge to make an image visible on contact (for example, when using a selenium photoreceptor drum,
However, with only toner used in conventional two-component development methods, the amount of charge sufficient to create a visible image is due to frictional charging with the developing sleeve. can't get it.

In short, is it possible with the conventional two-component development method? ! In order to obtain the amount of charge necessary for image formation, frictional charging of the toner and carrier is performed over a sufficient period of time. , the triboelectric charging time is short, and the amount of charge necessary to visualize the image cannot be obtained.

In addition, in the conventional one-component development method, it is necessary to apply toner extremely thinly and evenly on the surface of the developing sleeve, but with the toner used in the two-component development method, such a thin toner layer cannot be applied. It is difficult to form uniformly.

Here, an example of the conventional process of forming a thin toner layer will be described with reference to FIG.

As shown in FIG. 2, the elastic blade 2 is connected to the developing sleeve 1.
The toner 4 in the toner container 3 is conveyed by the rotation of the developing sleeve 1 and is evenly and thinly applied to the surface of the developing sleeve 1 by the elastic blade 2. .

Therefore, the toner 4 is required to have excellent fluidity and agglomeration resistance, but if the toner 4 in the toner container 3 is not sufficiently charged, it will agglomerate during the process of being conveyed by the rotation of the developing slit 71. Since the toner particles become sticky and lumpy, there is a problem in that a thin layer of the toner 4 is not uniformly formed on the surface of the developing sleeve 1.

Furthermore, when the pressure of the elastic blade 2 is increased to increase the charging of the toner 4, the toner 4 transported by the developing sleeve 1 is suddenly subjected to high pressure at the contact area between the elastic blade 2 and the developing sleeve 1. As a result, frictional heat is generated in this area, causing the toner 4 to soften and stick to the surface of the developing sleeve 1, making it difficult to apply the toner 4 thinly (and evenly). .

Furthermore, if the softening point of the toner 4 is increased in order to solve the above problem, the fixing temperature becomes too high, making it impossible to apply it to ordinary electronic copying machines, printers, etc.

Therefore, in the conventional developing method using a one-component developer, the developer cannot be sufficiently and uniformly charged, resulting in a decrease in image density and
This method has drawbacks such as background fog, making it difficult to obtain clear images.

The present invention was achieved as a result of studies to solve the problems in the conventional developing methods described above.

Therefore, an object of the present invention is to establish a developing method that can obtain clear images.

[Structure of the Invention] (Means for Solving the Problems) That is, the developing method of the present invention supplies a developer to a photoreceptor drum on which an electrostatic latent image is formed to make the electrostatic latent image visible. In a developing method consisting of imaging, the glass transition point 5
A developer containing colored particles (A) in which a coloring agent is contained in a resin with a softening point of 110 to 160° C. at 0° C. or higher, and auxiliary particles (B) that are charged to a polarity opposite to that of the colored particles. The developer formed by pressing the developer onto the surface of the developing sleeve with an elastic blade is made to face the photoreceptor drum, and only the colored particles (A) are applied statically to the electrostatic latent image. Characterized by electrical attachment.

(Function) In the developing method of the present invention, a mixture of colored particles (A) and auxiliary particles (B) which are charged to the opposite polarity to the colored particles (A) is used as the developer. The colored particles (A) can be sufficiently and uniformly charged, and when developing an electrostatic latent image on the surface of the developing sleeve, only the colored particles (A) selectively contribute to the development.

Moreover, the particle size distribution of the auxiliary particles (B) is different from that of the colored particles (A).
), the developer can form a uniform thin layer on the developing sleeve without agglomerating.

Therefore, according to the developing method of the present invention, it is possible to triboelectrically charge the developer sufficiently and uniformly, and a clear image can always be obtained without reducing image density or background fog. be able to.

(Example) Examples of the developing method of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic sectional view of a developing device used in an embodiment of the present invention.

In the developing bag @ 10 shown in FIG. 1, the developing sleeve 30 as a developer carrying member has an elastic blade 31 of about 20 to 500 Q for forming a thin layer of developer on the circumferential surface of the developing sleeve 30.
They are pressed together at a pressure of /Cl1l.

In the toner container 21 that stores the developer 20, a supply roll 22 that supplies the developer 20 to the developing sleeve 30 is provided in contact with the developing sleeve 30, and the supply roll 22 is provided in contact with the developing sleeve 30 in the rotational direction (arrow A) of the developing sleeve 30. It is configured to rotate in the opposite direction (arrow B).

A stirring blade 23 for stirring the developer 20 contained therein is rotatably provided in the toner container 21 .

A collecting blade 32 for collecting the developer remaining on the surface of the developing sleeve 30 is in contact with the lower part of the developing sleeve 30 .

Note that between the photosensitive drum 40 on which the electrostatic latent image is formed and the developing sleeve 30, there is a power source 3 that applies a direct current bias, an alternating current bias, or a superimposed bias of direct current and alternating current.
3 is connected.

Next, the operation of this developing device 10 will be explained.

The developer 20 housed in the toner container 21 is rotated by the rotation of the stirring blade 23, and the colored particles (A) and auxiliary particles (B) constituting the developer 20 are rotated by r! 1 is rubbed against W, and is charged by friction.

In this way, the preliminarily charged developer is transported by the supply roll 22, rubbed against the developing sleeve 30, and roughly pressed into contact with the elastic blade 31, and while the layer thickness is controlled, the developer is triboelectrically charged. be done.

Then, the sufficiently charged developer 20 is transported to a position facing the photoreceptor drum 40, but the developing sleeve 30
Since, for example, an alternating current voltage is applied to the developing sleeve 30 by the power source 33, the developing sleeve 30 faces the electrostatic latent image formed on the photosensitive drum 40 while reciprocating in the direction away from and the developing sleeve 30 returning.

Colored particles (A) and auxiliary particles (B) contained in the developer 20
) have charge polarities opposite to each other, so the colored particles (A
) selectively adheres to the electrostatic latent image and development is performed.

Further, the developer remaining on the surface of the developing sleeve 30 is returned into the toner container 21 by the collection blade 32.

In the developer used in the present invention, the glass transition point for forming colored particles (A) is 50°C or higher, and the softening point is 110 to 160°C.
Examples of the resin include polystyrene, styrene copolymers such as styrene-butadiene copolymer, styrene-acrylonitrile copolymer, polyethylene, high molecular weight polyethylene, polypropylene, low molecular nail polyethylene, ethylene-vinyl acetate copolymer, Olefin polymers such as ethylene-vinyl alcohol copolymers, phenolic resins,
Aliphatic or alicyclic hydrocarbon resins such as polyamide, polyester, polymethyl methacrylate, maleic acid resin, polyacrylic acid, polyvinyl butyral, so-called petroleum resins such as aromatic hydrocarbon resins, chlorinated paraffins, waxes, and Known materials such as mixtures thereof may be used.

If the glass transition point of these resin materials is less than 50° C., it is not preferable because the storage stability of the developer decreases.

Further, if the softening point of the resin material is less than 110° C., so-called offset, in which the developer is fused to the fixing roller during fixing, tends to occur, and if it exceeds 160° C., fixing becomes difficult, which is not preferable.

Furthermore, as the coloring agent forming the colored particles (A), carbon black, Fast Yellow 01 Benzidine Yellow, Pigment Yellow, Indo First, Orange, I0 Gazin Red, Riki-min FB, Permanent Bordeaux FRR1 Pigment Orange R1 Resole Red Known materials include 2G, Lake Red 010-Damine FB, Rhodamine B Lake, Phthalocyanine Blue, Pigment Blue, Brilliant Green 81 Phthalocyanine Green and Quinacudrin.

In addition, charge control agents such as metal-containing dyes, nigrosine type and polyamine type can be added to the auxiliary particles (B) formed from these components for the purpose of controlling charge. The offset resistance can also be improved by adding wax accordingly.

Furthermore, in order to improve the fluidity and agglomeration resistance of the colored particles (A), hydrophobized colloidal fine particles having the same polarity as the developer, such as colloidal silica, are used to adversely affect the amount of charge of the developer. It can also be added to a certain extent.

On the other hand, the auxiliary particles (B), which is another component of the developer used in the present invention, include aluminum oxide, titanium oxide, silicon oxide, zinc oxide, magnesium oxide, barium titanate, calcium oxide, tin oxide, and indium oxide. , inorganic compounds such as cerium oxide and molybdenum trioxide, those whose surfaces are treated with coupling agents such as silane coupling agents and titanium coupling agents, or silicone oil, polystyrene, styrene, etc.
Styrenic copolymers such as butadiene copolymer and styrene-acrylonitrile copolymer, olefinic polymers such as polyethylene, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer, and fats such as polymethyl methacrylate. Resins such as fine powders such as group or alicyclic hydrocarbon resins, silicone resins, and Teflon resins, the surfaces of these resins treated with the above-mentioned coupling agents or silicone oils, and magnetic powders such as magnetite and ferrite. Known materials include:

Furthermore, the above-mentioned aliphatic or alicyclic hydrocarbon resin may be used as a binder, and the above-mentioned inorganic compound, fine powder, etc. may be contained therein as the auxiliary particles (B).

The amount of the auxiliary particles (B) added to the colored particles (A) is 0.
．． A range of 1 to 60% is suitable.

If the amount of the auxiliary particles (B) added is less than 0.1% by weight, a sufficient preliminary charging effect cannot be obtained in the frictional charging with the colored particles (A>), and if the amount exceeds 60% by weight, the relative This is undesirable because the concentration of the colored particles (A) becomes low, and the fluidity of the entire developer decreases, making it difficult to form a dense and averagely thin developer layer, resulting in a decrease in image density.

In addition, in the developer, the 50% weight average particle diameter of the colored particles (A) is in the range of 3 to 20 μm, and the auxiliary particles (B)
The 50% weight average particle diameter is 50% of the colored particles (A).
It is desirable that the particle diameter be in the range of 115 to 4 times the weighted average particle diameter.

Here, if the 50% weight average particle diameter of the auxiliary particles (B) is less than 115 of the 50% weight average particle diameter of the colored particles (A), the auxiliary particles (B) tend to aggregate with each other, and the developer is Auxiliary particles that have aggregated during use for a period of time get stuck between the developing sleeve 30 and the photoreceptor drum 40, inhibiting the formation of a dense and averagely thin developer layer, resulting in increased background fog and deterioration of printability. This is undesirable because it causes

Furthermore, if the 50% weighted average particle diameter of the auxiliary particles (B) exceeds four times the 50% weighted average particle diameter of the colored particles (A), the auxiliary particles may have entered between the developing sleeve 30 and the elastic blade 31. Particles (B) are not preferred because they inhibit the formation of a thin and uniform developer layer and cause problems such as streaks and background fog on images.

In addition, the 50% weighted average particle diameter as used in the present invention is.

Means the value measured by Coulter Counter manufactured by Coulter Electronics.

In the developer used in the present invention, the auxiliary particles (B) have a chargeability of opposite polarity to the colored particles (A), so the colored particles (A)! ? When triboelectrically charging, by charging itself to the opposite polarity, it is possible to promote the charging of the colored particles (A) and to strongly retain the electric charge on the colored particles (A).

Furthermore, when the colored particles (A) are brought into pressure contact with the developing sleeve 30 by the elastic blade 31 and before that, they come into contact with the auxiliary particles (B) in the developer and are triboelectrically charged. Charged fff! It can be charged more fully and reliably than in the case of I.

When developing the electrostatic latent image on the photoreceptor drum 4o, since the auxiliary particles (B) have charge polarity opposite to that of the colored particles (A), only the colored particles (A) selectively contribute to development. I will do it.

However, even if the auxiliary particles (B) adhere to the electrostatic latent image, the above characteristics make it difficult for the auxiliary particles (B) to be transferred onto the paper during the transfer process, making it difficult to obtain a clear image without background fog. be able to.

Hereinafter, specific test examples of the method of the present invention will be explained.

(Test Example 1) As a resin material, styrene-n-butyl acrylate 2
Ethylaminoethyl methacrylate copolymer (glass transition point TQ: 67°C, average molecular weight MW: 280,000, softening point:
135°C) 90 parts by weight, 5 parts by weight of carbon black (product name MA-100, manufactured by Mitsubishi Chemical Co., Ltd.) as a coloring agent, 3 parts by weight of wax (product name MA-100, manufactured by Sanyo Chemical Co., Ltd.), and a charge control agent (product name). Name N-01 (manufactured by Orient Chemical Co., Ltd.) Double J part was mixed in a pressure kneader for about 1 hour, cooled, coarsely pulverized with a hammer mill, finely pulverized with a jet mill,
Colored particles (A) were obtained by further classifying the obtained powder using an air classification method.

The 50% average particle diameter of the colored particles (A) is 12°2 μm,
The amount of triboelectric charge measured by the blow-off method is +2
It was 7.2μC/Q.

On the other hand, styrene-n-butyl methacrylate copolymer (glass transition point To: 66°C, average molecular f1MW: 9900
0, Softening point: 123°C) was finely pulverized with a jet mill to produce a 50% average particle size: 11.4 μm, triboelectric charge amount measured by blow-off method: minus 16.6 μm.
C/Q auxiliary particles (B) were obtained.

100 parts by weight of the colored particles (A) thus obtained and 5 parts by weight of the auxiliary particles (B) were combined in a V-type blender for about 1 hour to produce a -component developer.

This developer is supplied to a developing device having the structure shown in FIG. A copy image of the original was formed on the image.

As a result, a clear image with an image density of 1.35 and no background fog could be obtained.

In addition, high temperature and high humidity (temperature: 30℃,
When development was carried out in an environment with a humidity of 285%, no background fog or decrease in image density was observed, and a clear image with good transfer efficiency could be obtained.

Furthermore, when the resulting image was fixed using a heat roll fuser, both fixing and offset were good in the range of 170°C to 220°C, and even after 10,000 copies, the quality of the image was the same as the initial image. I was able to obtain an image of

(Test Example 2) Styrene-n used in Test Example 1 as the auxiliary particle (B)
60 parts by weight of butyl methacrylate copolymer and 40 parts by weight of magnetite (trade name KBG-100, manufactured by Kanto Denka Co., Ltd.) were mixed and crushed in the same manner as in Test Example 1, and the other conditions were as in Test Example 1. A -component developer was produced in the same manner.

When an image was formed using this developer in the same manner as in Test Example 1, a clear image without background fog could be obtained as in Test Example 1.

(Comparative Example 1) Using only the colored particles (A) obtained in Test Example 1, auxiliary particles (
When a copy image was formed under the same conditions using the developer obtained without mixing B), the image density was 1.1 and many background fogs occurred.

(Test Example 3) Styrene-n-butyl methacrylate copolymer (glass transition point To: 66°C, average molecular weight MW) was used as the resin material.
:990001 softening point: 123°C) and 2 small parts of N-01 (manufactured by Orient Chemical Co., Ltd.) as a charge control agent.
12.7μm1 Frictional charge B: minus 24.5μC
/Q colored particles (A) were obtained.

In addition, the styrene-n-butyl acrylate 2-ethylaminoethyl methacrylate co-vehicle combination used as the resin component of the colored particles (A) in Test Examples 1 and 2 above was pulverized in the same manner as Test Example 1, and the friction measured by the blow-off method was obtained. The auxiliary particles (B
), and the other conditions were the same as in Test Example 1 to produce a one-component developer.

This developer is applied to a copying machine equipped with positively charged selenium.
When a copy image was formed by the same method as in Test Example 1, an image of excellent quality could be obtained as in Test Examples 1 and 2 above.

[Effect of the Invention J As explained in detail above, in the developing method of the present invention, the colored particles (A) and the colored particles (A) are used as the developer.
Since a mixture of auxiliary particles (B) that is charged to the opposite polarity to A) is used, the colored particles (A) can be sufficiently and uniformly charged, and the electrostatic latent image on the surface of the developing sleeve can be When developing, only the colored particles (A) selectively contribute to the development.

Moreover, the particle size distribution of the auxiliary particles (B) is different from that of the colored particles (A).
), the developer can form a uniform thin layer on the developing sleeve without agglomerating.

Therefore, according to the developing method of the present invention, it is possible to triboelectrically charge the developer sufficiently and uniformly, and a clear image can always be obtained without reducing image density or background fog. be able to.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a developing device used in an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of the developing device for explaining a conventional developing method. 10... Developing device 20... Developer 21... Toner container 22... Supply roll 23... Stirring blade 30... ...Development sleeve 31...Elastic blade 32...Recovery blade 33...Power source 40...Photoreceptor drum

Claims (4)

[Claims] (1) A developing method comprising supplying a developer to a photoreceptor drum on which an electrostatic latent image is formed to visualize the electrostatic latent image, with a glass transition point of 50° C. or higher and a softening point of 110° C. or higher.
Colored particles (A) containing a coloring agent in a resin at 160°C
and auxiliary particles (B) that are charged in a polarity opposite to the charged polarity of the colored particles, and a developer layer formed by pressing this developer against the surface of the developing sleeve with an elastic blade, A developing method characterized in that only the colored particles (A) are electrostatically attached to the electrostatic latent image while facing the photosensitive drum. (2) The developing method according to claim (1), wherein the amount of the auxiliary particles (B) added to the colored particles (A) is in the range of 0.1 to 60% by weight. (3) The 50% weight average particle diameter of the colored particles (A) is 3 to 2
It is characterized by using a developer in which the 50% weight average particle size of the auxiliary particles (B) is in the range of 1/5 to 4 times the 50% weight average particle size of the colored particles (A). A developing method according to claims (1) and (2). (4) Developing is performed by applying an alternating current bias to the developing sleeve and reciprocating the developer particles on the surface of the developing sleeve, according to claims (1) to (3). development method.