JPS60177359A - Developer - Google Patents

Abstract

PURPOSE:To obtain an image having a clear color and high resolving power by using a developer consisting essentially of a toner which is conveyed without being brought into contact with an image carrying body and visualizes a latent image under an oscillating electric field and a carrier contg. a coloring component. CONSTITUTION:A developer is constituted of a toner and a carrier formed by dispersing magnetic material powder and coloring agent in a resin and forming the mixture into particles. The developer D in a developing device 2 is agitated by an agitating plate 5 to generate electric charge and bias is applied to the sleeve 7 of a magnetic roller 6 from a DC bias source 10 and an AC bias source 11 to develop a latent image under the oscillating electric field without bringing a developer layer 9 into contact with the surface of a photosensitive drum 1. The image having a clear color and high resolving power is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developer used in electrophotography and electrostatic recording, and more particularly to a so-called color developer for obtaining chromatic images.

[Prior art]

A method for developing an electrostatic latent image obtained by electrophotography or the like involves covering a magnet with a rotatable non-magnetic sleeve and magnetically adsorbing a developer onto the sleeve to form a so-called magnetic brush. The most widely used method is the magnetic brush method, in which toner is adhered to an image area by rubbing the surface of an image carrier carrying an electrostatic latent image with this magnetic brush. There are two types of magnetic brush methods: one uses a one-component developer, which uses toner containing a magnetic substance to form a developer, and the other uses a two-component developer, which is made of a mixture of magnetic powder and toner, called porridge. However, in general, the magnetic brush development method using a two-component developer is relatively easy to control triboelectrification of toner particles, prevents toner particles from agglomerating, and allows the magnetic brush to stand up well. It has excellent abrasion properties on the surface of the carrier and has sufficient cleaning effects even when used for cleaning. It is used. This developing method conventionally uses magnetic carrier particles with an average particle size of several tens to several hundred μm and magnetic carrier particles with an average particle size of several tens of μm.
Developers are used that consist of non-magnetic toner particles, and because the toner particles and even carrier particles are coarse, high image quality that reproduces delicate lines, dots, and differences in shading is difficult. The problem is that it is difficult to obtain images.

In order to obtain high-quality images in such a developing method, it is necessary to make toner particles and carrier particles finer. However, toner particles with an average particle size of 20μ
If the particle size is smaller than 10 μm, in particular, smaller than 10 μm, the van der Waals force will be affected by the Coulomb force during development, and so-called capri will occur where the toner particles will adhere to the ground area of the image background. Also, it is difficult to prevent fog by applying a DC bias voltage to the developer transport carrier. Further, as the carrier particles are made finer, the carrier particles also come to adhere to the electrostatic image portion of the image carrier. The reason for this is considered to be that the force of the magnetic bias is reduced and the carrier particles adhere to the image bearing member together with the toner particles. Note that as the bias voltage increases, carrier particles will also adhere to the ground portion of the image background.

Magnetic carriers are usually particles of magnetic substances such as iron or triiron tetroxide, their surfaces coated with various resins such as styrene, or fine particles of magnetic substances dispersed and pulverized in resin. However, since all the magnetic materials that are normally used are black or a substance with a color close to black,
The magnetic carrier obtained usually also has a mostly black color.

During development, if such carrier mixes with toner and adheres to the surface of the image carrier, the color of the image becomes dark, not only in the case of black images but also in the case of color images, and furthermore, black capricorns appear in the background. This results in an extremely unfavorable situation in practice.

These drawbacks are such that the thickness of the developer layer on the developer transport carrier during development is thinner than the gap between the developer transport carrier and the image carrier carrying the electrostatic latent image to be developed. This can be greatly improved by using a non-contact development method, generally called jumping development, which prevents direct contact between the developer and forms an oscillating electric field between the image carrier and the developer transport carrier. Under such conditions, the toner on the developer transport carrier vibrates due to the action of the oscillating electric field, flies to the latent image area on the image carrier, and develops. However, the developer layer itself directly touches the surface of the image carrier. Since there is no rubbing of the carrier, adhesion of the carrier to the surface of the image carrier is significantly reduced.

However, when the carrier particles are made even finer to improve image quality, it becomes difficult to completely prevent the adhesion of bull yaria to the image bearing surface even if a non-contact development method is used, and when a two-component color developer is used. It was not possible to prevent color deterioration.

[Purpose of the invention]

An object of the present invention is to provide a two-component developer for non-contact development that provides images with clear colors and high resolution.

[Structure of the invention]

The purpose is to convey the latent image without contacting the image carrier and place it under an oscillating electric field, thereby making the latent image visible. This was achieved using a developer whose main components are toner and a carrier containing a coloring component. That is, in the present invention, the carrier is colored by adding a coloring agent, and even if some carrier is mixed into the toner forming the image or attached to the background part of the recording medium, the tone of the image will not deteriorate.
The purpose is to avoid noticeable fog, and it is preferable that the color of the colorant be similar to the toner used in the mixture. A white toner may be used regardless of the color of the toner to be used.

The carrier used in the electrophotographic developer of the present invention (hereinafter simply referred to as developer) preferably contains a magnetic material, and in this case, the carrier may be coated with a magnetic material with a resin containing a colorant. However, it is more preferable to disperse fine magnetic powder and a colorant in a resin and form particles.

The magnetic materials used in the magnetic carrier include metals such as iron, chromium, niranal, and cobalt, as in conventional magnetic carriers, or compounds and alloys thereof, such as triiron tetroxide, ferric oxide, and dioxide. Known ferromagnetic materials such as chromium, manganese oxide, ferrite, and manganese-copper alloy can be used, and colored magnetic materials may also be used to improve color clarity.

Suitable colored magnetic materials include tim for red color.
iron oxide (red iron), N1 surface coated with copper oxide,
Cadmium red adsorbed on N1, cobalt and its compounds for blue color, iron oxide, N for yellow color.
There are materials in which cadmium yellow is adsorbed on L. Transparent magnetic materials containing rare earth elements can also be used.

The resin constituting the carrier is phenolic resin,
Polyester, polystyrene, algide resin, polyacrylic, polyethylene, polycarbonate, polyester, polyamide, polyether, polyolefin, polystyrene, styrene-acrylic acid copolymer, styrene-
Methacrylic acid copolymer, styrene-ethylenically unsaturated monoolefin copolymer, styrene-vinyl ester copolymer, styrene-vinyl ether copolymer, styrene-
Acrylonitrile copolymer, styrene-methacrylonitrile copolymer, styrene-acrylamide copolymer,
Examples include styrene-vinylidene halide copolymer, polyvinyl acetate, copolymers of two or more of these, and mixtures of these polymers.

In addition, the coloring agents that make up the magnetic carrier include inorganic pigments,
Examples include organic pigments, direct dyes, acid dyes, basic dyes, mordants, acid mordant dyes, disperse dyes, and oil-soluble dyes. These specific examples include carbon black, black pigment,
Acetylene black, lamp black, graphite, mineral black, aniline black, cyanine black, etc.
Yellow pigments include yellow lead, lead yellow, barium chromate, cadmium yellow, lead cyanamide, calcium leadate, naphthol yellow 3. Hansa Yellow 10G.

Hansa Yellow 5G, Hansa Yellow 3G, Hansa Yellow 〇, Hansa Yellow GR, Hansa Yellow A, Hansa Yellow R
N1 Hansa Yellow R1 Pigment Nilkan 7 Asto Yellow 5G, Palkan Fast Yellow R, Tartrazine Lake, Quinoline Yellow Lake, Anthragen Ero-6GL
, Permanent Yellow FGL, Permanent Yellow H1Off, Permanent Yellow HR, Anthrapyrimidine Yellow, red pigments include red pigment, red lead,
Silver vermilion, cadmium red, permanent red 4R1 para red, 7 fire red, western vermilion, parachlororthonitroaniline red, resol fast scarlet G, brilliant 77 scarlet, brilliant carmine BS, permanent red F2R, permanent red F4R, permanent red FRL, Permanent Red FRL, I, , Permanent Red F4
RH, Fast Scarlet VD.

Palkanphatrupine B1 Eosin Lake, Roguemin Lake, Rhodamine Lake Y1 Alizarin Lake, Thioindigo Red B1 Thioindigo Maroon, Permanent Red FGR% Pv Carmine HR, etc. Blue pigments include ultramarine, navy blue, cobalt flu, alkali blue lake, Peacock Blue Lake.

Examples include Victoria Blue Lake, metal-free phthalocyanine blue, 7-thalocyanine blue, 7-asto sky blue, Indan Stremburu-R81 Indan Stremble-BS, and Indigo. Index) Direct Yellow 9B, C, 1, Direct Yellow 89, C, 1, Direct Yellow 88
(Direct dyes above), C, 1, Acid Yellow 1, C
,I.

Acid yellow 3. C,1, Acid Yellow 7 (all acid dyes), C,1, Basic Yellow 1, C,1
, Basic Yellow 2, C,1, Basic Yellow 11 (all basic dyes), C,1, Modern Toy Yellow-26 (mordant, acidic mordant dye), C,1, Disperse Yellow 1, C,1, Dis Perth yellow 3. C,I
.

Disperse Yellow 4 (disperse dyed R), C, I.

Solvent yellow 2. C, 1, Solvent Yellow 6
, C,1, Solvent Yellow 14 (all oil-soluble dyes), etc. As red dyes, C,1, Direct Red 1. C,I
.

Direct Red 2. C,1, Direct Red 4 (all direct dyes), C,1, Acid Red 8, C,I.

Acid Red 13, CJ, Acid Red 14 (all acid dyes), C,1, Basic Red 2, CJ, Basic Red 14, C,1, Basic Red 27 (
Basic dye), C, 1, Modern Tread 21 (mordant, acidic mordant dye), C,! , Dispersed Red 1,
C, I・Dispersed thread 4. As a blue dye, C,1, Disperse Red 5 (disperse dye), C,1, Solvent Red 1, C,R, Solvent Red 3, C,1, Solvent Red 8 (oil-soluble dye), etc. 1, Direct Blue 1, C,
I.

Direct Blue 6, C,1, Direct Blue n (all direct dyes), C,1, Acid Blue 1, C,I.

Acid Blue, C,1, Acid Blue 22 (more than acidic dye), C,1, Basic Proof, C,1, Basic Blue 9, C,1, Basic Blue 19 (more than basic dye), C,1, Modern Top Blue 48 (mordant, acidic mordant dye), C, 1, Disperse Blue 1.
C.I.

Dispers Blue 3, C, 1, Dispers Blue 5
(disperse dye), C,1, Solvent Blue-2, C,
1, Solvent Blue 11. Examples of white pigments include titanium oxide, zinc oxide, antimony oxide, barium sulfate, zinc sulfide, lithopone, etc., which are used in the carrier according to the present invention. The colorant is not limited to these, and colorants with various tones can be selected as necessary. In addition to being used alone, a plurality of types of coloring may be used in combination.

The magnetic carrier preferably used in the developer of the present invention is prepared by thoroughly premixing the above-mentioned magnetic fine powder, resin, and coloring agent in a ball mill, etc., melting and kneading with an extruder under equal pressure, cooling, and then using a pulverizer. Finely pulverize
Furthermore, it can be obtained by fractionating particles of an appropriate particle size using a wind classifier or the like. Further, the obtained carrier may be made into a spherical shape by a method such as hot air treatment.

Any known apparatus, method, etc. used for producing the magnetic carrier can be used.

The content of the magnetic material in the magnetic carrier is from (%) to ω percent of the weight of the magnetic carrier, and the content of the colorant is from 5 to 15%.
A range of percentages is preferred.

Further, the average particle size of the carrier is preferably less than (capital) μm, and it is particularly preferable that the particle size is in the range of 5 to 100 μm, and furthermore, the magnetization thereof is (2) to 70 emu/μm.
Ji' is preferable, and it is desirable that it has a high resistivity of about 10'4 Ω. Incidentally, the average particle diameter is a weight average particle diameter and is a value measured using an Omnicon Alpha (manufactured by Bossiero Gosha) and a Coulter Counter (manufactured by Coulter Corporation). The resistivity was determined after the particles were placed in a container with a cross-sectional area of 0.50 crIl and tapped (the amount of particles was y
1kl on the packed particles so that the layer thickness after pinging is about 1mm! This value is obtained by applying a load of /ffl and reading the current value when applying a voltage that generates an electric field of 100 OV/cnL between the load and the bottom electrode. Note that if this resistivity is low, when a bias voltage is applied to the developer transport carrier, charges will be injected into the carrier particles, making it easier for the carrier particles to adhere to the surface of the image carrier, or causing breakdown of the bias voltage. is likely to occur.

The toner that is mixed with the above-mentioned magnetic carrier to constitute the developer is a color toner mainly composed of a resin and a colorant, and the resin and colorant used for the carrier are those listed above. be able to. The particle size of the toner is preferably less than 1 μm, and the voltage is preferably 5 to 10 μm.
It is preferable to use a resistivity as high as about 1014 Ωα.

In order to adjust the triboelectricity of the above-mentioned toner, for example, a nigrosine-based electron-donating dye is used as a positive agent.
Other metal salts of hepthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salts, alkylamides,
Chelates, pigments, fluoride treatment activators, etc.

Charge control agents such as electron-accepting organic complexes, low chlorinated paraffins, chlorinated polyesters, polyesters with excess acid groups, sulfonylamines of copper phthalocyanine, and hydrophobic agents to improve toner fluidity and cleaning properties. Various known additives commonly used in toners may be added, such as synthetic silica, fatty acid metal salt rings, or polyethylene, polypropylene, and wax for improving fixing properties.

These toners are mixed with the magnetic carrier to form a developer. It is desirable that the colorant used in the toner and carrier used in combination be the same colorant, but they may be different types as long as they have similar colors. Further, a carrier using a white colorant can be used in combination with toner of any color.

The mixing ratio of toner and magnetic medium in the developer is preferably in the range of 5:95 to 50:50 by weight.

The developer according to the present invention can be used in various image recording devices equipped with a developing device capable of non-contact development as described above, and there are no special restrictions regarding the type of electrostatic image carrier and the exposure method. It is not something that is received. It can also be used in various known color image recording apparatuses equipped with a plurality of developing devices to form multicolor images.

EXAMPLES The present invention will be specifically explained below with reference to Examples.

[Example 1] A blue toner and carrier using blue pigment #i7 talocyanine as a colorant were prepared as follows.

(Toner) Mix the raw materials of the above recipe, melt and melt with an extruder.
The kneaded mixture was cooled, then finely pulverized using an air classifier to reduce the average particle size to 15.
It is classified to have a particle size of 0.0 μm, and hydrophobic silica is used as a fluidizing agent.
．． Add 2 parts by weight of blue toner T.

I got it.

(Carrier) A blue-colored carrier cB having an average particle diameter of about 1 μm was obtained using the raw materials of the above formulation and following almost the same process as in the case of the toner. The magnetization of No. Yaria cB is Seki emu / 1
1. The resistivity was 1014Ω or more.

In addition, for comparison experiments, copper phthalocyanine was removed from the carrier formulation described above, and the other components were the same.
-I was prepared. The contrast carrier Cc had almost the same properties as the blue carrier cB except for its black appearance.

Said blue toner TB20 parts by weight, blue medium Yaria Cn80
A blue developer DB-1 of the present invention was prepared by mixing parts by weight, and a contrast blue developer D3B- was prepared by mixing blue toner TB and contrast carrier Cc in the same proportions with the developer DB-I.
II was prepared.

The samples were loaded alternately into an electrophotographic copying machine equipped with a developing device for non-contact development using the two types of developer described above and used as a photoreceptor, and a photocopying test was conducted using a test chart. White paper was used as the transfer material.

FIG. 1 is a schematic diagram of the developing section of the electrophotographic copying machine used in the test.

In the figure, 1 is the image carrier S@photosensitive drum, and arrow C
Rotate in the direction of. 2 is a developing device in which a developer is loaded. The consumed toner is sequentially replenished from the toner hopper 3 by a toner supply roller 4. The developer in the developing device 2 is stirred by the stirring plate 5, and the toner particles are charged. 6 is an 8-pole magnetic roller, 7 is a magnetic roller
-) 6 is a non-magnetic sleeve which is an ff15 developer transport carrier and rotates in the directions of arrows A and B, respectively. A regulating plate 8 regulates the thickness of the developer layer 9 formed on the sleeve 7, and the thickness of the developer layer 9 is regulated to be thinner than laa between the image carrier surface and the developer transport carrier.

Therefore, the surface of the photosensitive drum 1 which is an image carrier and the developer layer 9
Development occurs without contact. 10 is sleeve 7
It is a DC bias power supply that gives a DC bias to 11
is an AC bias power supply for performing development under an oscillating electric field. R is a protective resistance.

The specifications of the device were as follows.

Photosensitive drum diameter 120tx Sleeve diameter: 30 Drum linear speed: 120 degrees/second Number of magnetic roller poles: 8 Magnetic flux density on sleeve surface 800G The developing conditions during the test were as follows.

Drum charging potential 600 V DC bias voltage ioo v AC bias voltage (effective value) 1 to 2.5 I (V AC bias frequency 2 KHz Drum-sleeve gap d 1,0 mm Developer layer thickness 0.5 tm m3 1 rotation Continuous speed: 120 degrees/second Magnetic low rotation speed: 100 Orpm Toner charge amount -10 μe/Jil As a result of testing under the above conditions, in the case of the developer DB-I of the present invention using carrier cB, clear blue images were obtained. While a copy was obtained, the image obtained when the contrast developer DB-II was used was a slightly darker blue image, and some capri was also observed in the background.

[Example 2] Yellow toner and yellow gearia were prepared according to the following formulations.

(Tosu - ) (Carrier) For each, a process similar to that performed on the toner or carrier in [Example 1] was performed to produce yellow toner T.
Y, yellow carrier CyY was obtained. The average particle size of the toner TY was about 15 μm, and the average particle size of the toner TY was about m μm.

In addition, the dry average particle size of the carrier was prepared using the same carrier cy except for chrome yellow from the above carrier formulation.
A yellow developer DY-■ and a contrast yellow developer nY-II were prepared by preparing a black contrast carrier cc-n and mixing 85 parts by weight of rear CC-n, each of which was similar to that used in the example. The sample was loaded into an electrostatic copying machine and a copying test was conducted under the following conditions.

AC bias voltage (effective value) 2 KV AC bias frequency 1 to 4 KHz Drum/sleeve gap d O, 511111 Developer layer B
O.2 Magnetic roller rotation speed 40 rpm Toner charge amount -15 μa/9 All other conditions were the same as in Example 1.

As a result of the experiment, in the case of the developer Dy-I according to the present invention using carrier Cy'&, a copy with a clear yellow image was obtained, whereas in the case of using the contrasting yellow developer DY-II, the image area was , the background part also had a dark tone, which was judged to be practically impossible.

[Example 3] Red toner and white gearia (tos -) Polyester side 100 parts by weight Rhodamine lake 5 Charge control agent 1 (Carrier) Polyester resin 60 parts by weight Ferrite powder 4o Titanium oxide 5 Charge control agent 1.

The toner and carrier were each treated in the same manner as in Example 1 to obtain red toner TR and white carrier C.
wFt? Obtained. The average particle diameters of toner TR and gearia Cw were 10 μm and I μm, respectively.

A red developer Dn-I according to the present invention was prepared by mixing 30 parts by weight of the red toner TR and parts by weight of the carrier CW. In addition, the toner Tn and the contrast carrier C obtained in Example 2
A contrast red developer DR-II was prepared by mixing c-IF in the same ratio as in DR-I.

Developers DR-I and DR-II were each loaded into an electrostatic copying machine similar to that used in Example 1, and a copying test was conducted under the following conditions.

AC bias voltage (effective value) 1 to 4 KV AC bias frequency 3 KHz Drum-sleeve gap 0.3 u Developer layer thickness 0.2 Crane magnetic roller fine rotation Orpm Toner band 111: t -10tt c/1 Other conditions were all the same as in Example 1. As a result of the experiment, in the case of the developer Dn-I of the present invention using the carrier Cw, a copy with a clear red image was obtained, whereas the image in the case of using the contrasting red developer DR-II, and the background were both blackish and gave a dark impression.

In the above examples, the toner image was transferred to white transfer paper, but if blue transfer paper was used, for example,
It has been confirmed that when a carrier colored blue is used, an image can be obtained in which the carrier 3 attached to the background area is not noticeable.

[Example 4] Using the developers obtained in Examples 1 to 3, a test was conducted using a multicolor laser printer equipped with three developing devices. Second
The figure is a schematic diagram of a color printer used in the test. This printer uses a laser as an exposure light source and uses a photosensitive drum coated with OPC (organic photoconductor) as an image carrier. In the figure, 21 is a photosensitive drum using OPC as a photosensitive layer, the entire surface of which is charged by a charging electrode.
The laser beam L is modulated by the image signal of the first image and sent through a rotating polygon mirror and an imaging lens.
B is scanned and exposed to form an electrostatic latent image of the first image. Since this electrostatic latent image is of negative type, the first development g
925a is set to the reversal development condition, and the first
Obtain a toner image of The photosensitive drum carrying this toner image is charged again by the charging electrode a, scanned and exposed with a laser beam modulated by the second image signal, and reversely developed by the second developing device 25b, superimposed on the first image. A second toner image is formed. Further, the same process is repeated to form a third electrostatic latent image, which is developed by the third developing device 25e to form a third toner image.

After all the toner images are thus formed on the photosensitive drum 21, the pre-transfer exposure lamp is irradiated, the transfer electrode is activated, and the recording paper P (its This toner image is transferred onto the path (the path is indicated by a broken line).

The recording paper is heated and fixed by a fixing device constituted by at least one heated roller, and then discharged outside the machine.

On the other hand, the photoreceptor drum 1, whose transfer has been completed 1-, has been neutralized by the static eliminator 4, which was not in use during the toner image formation, and the excess toner remaining on the surface is removed during the toner image formation. It is removed by the cleaning device 30.

All of the three developing units have the n-shape shown in FIG. 1, and while one of them is performing a developing operation, the other two are at rest. In the figure, 31 is a separation electrode for separating the recording paper from the drum.

Developing units 25m, 25b, 2 of the above multicolor laser printer
5a, the developer Di obtained in Examples 1 and 2.3, respectively.
-I, DY-I, and DB-I were loaded, and an image consisting of three colors was recorded.

The three times of development were carried out under the following conditions.

DC bias 500v AC bias voltage (effective value) 1.5KV AC bias frequency 2 KHz Drum sleeve gap 0.5cm Developer layer thickness 0.3mm Sleeve rotational linear speed Same as drum linear speed Magnet roller rotational speed 40Orpm The obtained recorded image had a clear color tone, almost no background capri was observed, and was of extremely high quality. On the other hand, when the contrasting developers DB-II, Dy1I, and DR-II were loaded in each developing device and the images were recorded, the tones were dark and the background was darkened, and the images were clearly inferior. .

〔Effect of the invention〕

By using the developer of the present invention, it is possible to prevent fogging in image areas and background areas due to the miniaturization of carriers, and to obtain recorded images with high image quality and clear colors.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the developing device, and FIG. 2 is a schematic diagram of the configuration of the multicolor laser 7 link. 1.21-...Photosensitive drum 2r2S*, 2Bb, 25
a-・Developer 6...Magnetic roller 7...Sleeve 9
...Developer layer 10...DC bias power supply 11...
・AC bias power supply agent Patent attorney Noda 6 parents Figure 1

Claims (1)

[Scope of Claims] (1) The carrier is transported without contacting with the image carrier carrying the latent image and placed in an oscillating electric field, whereby the color of the colored component contained in the latent (2) carrier changes to that of the latent image. 2. The developer according to claim 1, wherein the developer has a color similar to that of the toner to be mixed with the carrier. (3) The developer according to claim 1, wherein the coloring component contained in the carrier is white in color.