JPS59200276A - Color developing method - Google Patents

Abstract

PURPOSE:To obtain a vivid and bright image by satisfying specific conditions in the relation between the quantity of a magnetic material in a toner and the particle size of the magnetic material. CONSTITUTION:A latent image holding body holding a latent image on the surface and a toner carrier carrying an insulating toner are arranged a certain gap apart from each other in a developing part. The toner is applied to the toner carrier by a magnetic means, and this applied layer has the thickness controlled to a value smaller than the gap of the toner carrier and is carried to the developing part, and the image is developed while applying an alternating electric field to the toner carrier. In this case, the relation between wt% magnetic material quantity Y in the toner and a particle size Xmum is selected to satisfy Y<=60X<1.23> (0.01<=X<=5). As the result, a vivid and bright picture is obtained with an ultrafine magnetic material satisfying the relation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color developing method used in electrophotography, electrostatic recording, and the like.

As a conventional electrophotographic method, U.S. Patent No. 2,297,691
specification, Japanese Patent Publication No. 42-23910 (U.S. Pat. No. 3,666,363) and Japanese Patent Publication No. 43-24748
Although many methods are known, such as those described in U.S. Pat. After forming an electrical latent image and transferring the toner image to a transfer material such as paper if necessary, it is fixed by heating, pressure, etc. to obtain a complex H image.

Various developing methods are also known in which an electrostatic latent image is visualized using toner. For example (d) the magnetic brush method described in U.S. Pat. No. 2,874,063;
A large number of developing methods are known, such as the cascade developing method described in Ministry of Specification No. 2, the powder cloud method described in Specification No. 2221776, the fur brush development method, and the liquid development method. Among these developing methods, a magnetic brush method, a cascade method, a liquid developing method, and the like, which use a developer mainly consisting of toner and carrier, have been widely put into practical use. All of these methods are excellent methods that can obtain good images relatively stably, but on the other hand, they may cause deterioration of the carrier,
A common drawback associated with two-component developers is variation in the toner to carrier mixing ratio.

In order to avoid such drawbacks, developing methods using a one-component developer consisting of toner have been proposed, but among these, a method using a developer consisting of magnetic toner particles is superior. There are many.

U.S. Pat. No. 3,909,258 proposes a developing method using an electrically conductive magnetic toner. In this system, a conductive magnetic developer is supported on a cylindrical isoelectric sleeve having magnetism inside, and is brought into contact with an electrostatic image to develop it. In addition, in the developing section, toner particles form a conductive path between the surface of the recording medium and the sleeve surface, and through this conductive path, charges are conducted from the sleeve to the toner particles, and between them and the image area of the electrostatic image. Due to the Coulomb force, toner particles stick to the image area and are developed. This developing method using conductive magnetic toner is an excellent method that avoids the problems associated with conventional two-component developing methods. It has the disadvantage that it is difficult to transfer electrostatically to the final support member.

JP-A-52-94140 (West German Patent No. 2704361) discloses a developing method using dielectric polarization of toner particles as a developing method using high-resistance magnetic toner that can be electrostatically transferred. It is shown. However, such a method has drawbacks such as the inherently slow development speed and the difficulty in obtaining a developed image with sufficient density, making it difficult to use in practice.

Other developing methods using high-resistance magnetic toner include
A method is known in which toner particles are triboelectrically charged by friction between toner particles or between toner particles and a sleeve or the like, and then brought into contact with an electrostatic image holding member and developed.

However, in these methods, the number of times of contact between the toner particles and the rubbing member is small and frictional charging tends to be insufficient, and the Coulomb force between the charged toner particles and the sleeve is strong, causing them to aggregate on the sleeve. It has the disadvantage of being easy to clean, and is difficult in practice.

However, Japanese Patent Application Laid-Open No. 54-43027.

In JP-A-55-18656, etc., a new developing method which eliminates the above-mentioned drawbacks has been proposed. This involves applying a very thin layer of magnetic toner onto the sleeve, triboelectrically charging it, and then bringing it very close to the electrostatic image to develop it. According to this method, by coating the magnetic toner extremely thinly on the sleeve, the chances of contact between the sleeve and the toner are increased, and the toner is supported by magnetic force, which makes it possible to achieve a sufficient friction f4% band 'IB'. By moving the magnet and toner relative to each other, the toner particles are prevented from agglomerating each other, and the sleeve is sufficiently abraded, and the toner is supported by magnetic force to prevent ground force blurring. The result is a clear image.

On the other hand, conventional magnetic powders for magnetic toner include ferromagnetic elements and alloys and compounds containing them, such as magnetite, hematite, ferrite, etc., iron, cobal (...), nickel,
Compounds containing manganese, zinc, etc. are known. The properties required for such magnetic powder include (1) specific electrical resistivity, and (4) practically sufficient black porosity.
C51 is known for its excellent moisture resistance and (6) good mixability with resins. Usually, magnetite, which is called iron black and is widely used as a pigment, is often used for magnetic toner, and there are many examples described in patent documents.

This magnetite generally satisfies the above requirements, but for use in insulating magnetic toner, its properties must be carefully examined in terms of miscibility with resin, toner cohesiveness, triboelectric charging properties, and durability. It is said that

When developing a one-component magnetic toner by supporting it magnetically and facing an electrostatically charged image without contacting it and applying an alternating electric field and a bias electric field during development, the uneven developer particles Coulomb force between the electrostatic charge image and force due to the magnetic Bucha alternating electric field between the magnetic brush forming magnet and the like act. Particles on which the Coulomb force is strong are attracted to the electrostatic charge image, and particles on which a large -force difference air force acts are attracted toward the developing sleeve, thereby achieving development according to the electrostatic charge image. Furthermore, when the magnetic toner developed on the photoreceptor is transferred onto transfer paper, a corona discharge with the same polarity as the electrostatic latent image is generated from the back side of the transfer paper, which has the opposite polarity to the charge polarity of the magnetic toner. ig) to suck the toner image onto the surface of the transfer paper. At this time, if the charge on the toner particles easily escapes and disappears, this may cause blurring of the transferred image or a decrease in transfer efficiency. That is, since magnetic toner contains an overwhelmingly large amount of magnetic powder as its constituent component, it is strongly required that the magnetic powder has a special property to stably hold an electric charge.

Conventional one-component toners contain 20 to 80% by weight of magnetic material, and therefore have the disadvantage that the toner cannot be fixed to copy paper by heat fixing or pressure fixing.

On the other hand, recently, the purposes of use have become more diverse, and there are compact and inexpensive multi-color copying machines that can produce images with desired colors as required. It is not possible to moderate the color tone of the magnetic material simply by adding it to the binder resin.Also, in the method of applying white pigment to magnetic powder by chemical treatment, magnetic powder "1i" or dyes and pigments that do not have a negative effect on the development characteristics cannot be used. Within the range of the amount, simply applying a chemical treatment to coat the magnetic material was insufficient to moderate the color tone of the magnetic material and had little effect.In order to obtain a toner with the desired color tone using the above method, it is necessary to apply the magnetic material tt. It is possible to reduce the amount of color pigment more than necessary or increase the amount of color pigment, but if the amount of magnetic material is reduced too much, developability will decrease, and if the amount of color pigment is increased too much, developability will decrease and fixing ability will decrease. It was difficult to produce a magnetic toner that satisfied all the characteristics such as two-tone developability and fixability.

SUMMARY OF THE INVENTION An object of the present invention is to provide a color developing method using magnetic toner with a rich variety of colors.

A further object of the present invention is to provide a color developing method using magnetic toner that produces high-density, clear, and minimally fogged images.

A further object of the present invention is to provide a magnetic toner with excellent fixing properties.

In the present invention, a latent image holder that holds an m image on its surface and a toner carrier that carries an insulating toner are combined into jμ[/J1 part (
Then, the toner was placed with a certain gap f-7L, and the toner was applied to the toner Ji[i special holiday by means of air, and the thickness of the laminated fabric layer was regulated to be thinner than the gap -C. Currently, in the color development method in which the toner carrier is conveyed to a separate section and developed while applying a constant electric field to the toner carrier, the relationship between the amount of magnetic material in the toner and the particle size of the magnetic material Xprn is determined. This is a color actual method characterized by adding 71:'a to the following formula.

￥≦60 It was discovered that the image is 141 times larger.

In other words, if the size of the magnetic material is less than 0.01μ, the specific surface area is extremely large, so it will not be activated and there is a risk of rapid oxidation, combustion, or explosion at room temperature, so all of the above The process must be carried out in an inert gas or nitrogen atmosphere or in a vacuum. Also, 5 μ: What to include: ゛d
If the amount added to the binder is not increased, the magnetic properties of the magnetic toner will remain unsatisfactory, and good development will not be possible. Sweet.

This relational expression is shown in FIG. ;l) Figure 1 shows the factor average particle diameter (μm) of the (1'A substance) and its content in the binder - (5iy (wt
%), and the present invention limits the vivid color range.

As a toner binder, polystyrene, HoIJ
Homopolymers of styrene and its feffi substitutes, such as p-chlorostyrene, polyvinyltoluene, styrene-p-chlorostyrene copolymers, and styrene-vinyltoluene copolymers, and copolymers thereof; styrene-methyl acrylate copolymers, Both styrene and ethyl acrylate! 1↓7
Copolymer of styrene and acrylic acid ester such as styrene-acrylic l'Nn-butyl copolymer; styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-methacrylic CRn-butyl Co-11 copolymer of styrene and methacrylic ester of Kyoji Togo Taijo; multi-component copolymer of styrene and acrylic acid ester and methacrylic acid ester; other styrene-acrylonitrile copolymer, styrene vinyl methyl needle copolymer, Styrene-based Koia polymers of styrene and other vinyl monomers such as styrene-butadiene copolymer, styrene-vinyltoluene copolymer, styrene-acrylohenitrile-intene copolymer, and styrene-maleic acid ester copolymer; polymethyl methacrylate , polybutyl methacrylate, polyvinyl acetate, polyester, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid, phenol resin, aliphatic or alicyclic hydrocarbon resin, petroleum resin, chlorinated paraffin, etc. alone or in combination. Can be used.

Also for toner used in pressure fixing methods! As the binder resin, low molecular weight polyethylene, low molecular weight polypropylene, ethylene vinyl acetate copolymer, ethylene acrylate copolymer, higher fatty acid, polyamide resin, polyester resin, etc. can be used alone or in combination.

Desirable results can be obtained when the polymer, copolymer, or polymer blend used contains a vinyl aromatic or acrylic monomer represented by styrene in an amount of 40 wt'% or more.

The magnetic powder used in the present invention is a substance that is magnetized when placed in a magnetic field, such as powder of ferromagnetic metals such as iron, cobalt, and nickel, or magnetite, hematite,
There are alloys and compounds such as ferrite. Recently 0.0
There are also Fe-Ni alloys with a thickness of 3 μm and 0.03 μm, O, partially oxidized γ-Fe, and 03 with a size of 1 μm or less.

Furthermore, if necessary, a charge control agent may be added to the magnetic toner.
Coloring agents, fluidity modifiers may be added, charge control agents,
The fluidity modifier may be used by being mixed (externally added) with the toner. As this material, metal-containing dyes, nigrosine, etc. can be used, conventionally known dyes and pigments can be used as coloring agents, and colloidal silica as fluidity modifiers. , fatty acid metal salts, etc.'iJS
be.

Further, for the purpose of increasing the amount, a filler such as charcoal calcium, finely ground silica, etc. can be blended into the magnetic toner in an amount of 0.5 to 20w1%. Furthermore, in order to prevent toner particles from coagulating with each other and improve their fluidity, a crushability improver such as fine Teflon powder may be added to improve the releasability during hot roll fixing. Low molecule 'X4 for the purpose of;
It is also possible to add waxy substances such as ethylene, low molecular weight polypropylene, microcrystalline wax, carnano (wax, sasol wax) in an amount of about 0.5 to 5 wt4.

When the toner is used as a magnetic color toner, a coloring agent may be added as necessary, and known pigments or dyes can be used as the coloring agent. For example, dyes include
C.I. Direct Red L, C, 1, Direct Red 4. C,1, Acid Red 1, C,1, Basic Red 1. C.I. Modern Tread 30. C,1
, Direct Blue-1°C, 1, Direct Blue 2.
C, 1, Acid) 9, C, 1, Acid Blue
15. C, 1, Basic Blue 3. C.I. Basic Blue-5, C, I. Mordand Bruer, C, 1, Direct Blue 6°C9■, Benock Green 4
, C,1, Basic Clean 6, etc. Pigments include yellow lead, cadmium yellow, and mineral fast yellow.

Nee Full Yellow, Naphthol Yellow S, No1n the Yellow G, Noku-Manent Yellow NCG.

Tartrazine Lake, Red Yellow Lead, Monoden Orange, Permanent Orange GTR, Pyrasolone Orange, Henshishin Orange Gl Cadmium Red, Permanent Red 4R, Watching V Tudo Calcium Salt, Eosin Lake.

Brilliant Carmino 3B, Manganese Purple, Fast Violet B, Methyl Violet Lake, Navy Blue, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Fast Sky Blue, Indan Stremburu-BC, Chrome Clean, Chromium Oxide, Pigment There are Green B, Malachite Green Lake, Final Yellow Green G, etc.

Examples are shown below.

[Example 1] Styrene-acrylic copolymer 100 parts by weight Fe-C
o (0.02 μHc = 2300 oersted)
o3'Mi part Phthalocyanine blue 5 parts by weight Trichlene 5 parts by weight The above mixture was heated at 70° C. while the trichlene was evaporated. Next, this solid material was passed through a hammer mill and a jet pulverizer, and then passed through a classifier to obtain particles of 5 to 20 microns.

Next, 0.5 parts of hydrophobic silica powder was externally added to 100 parts by weight of the particles to obtain a developer. A colorful blue image has been reproduced.

[Example 2] Fe N1 (0,0
When the same treatment as in Example 1 was carried out using 4 parts by weight (3μ+Hc=1300 oersted), the same results as in Example 1 were obtained.

[Example 3] The same treatment as in Example 1 was performed except for Example 1.
Similar results were obtained.

[Example 4] When the same process as in Example 1 was performed except that the phthalocyanine blue of actual TFafAN was changed to benzidine yellow, a yellow image was reproduced.

[Example 5] The Fe-Co powder of Example 1 was transformed into cubic Fe,
The same results as in Example 1 were obtained by carrying out the same treatment as in Example 1, except that 3 parts by weight of 03 μm 04 powder was used.

[Example 6] Sintering the Fe, -Co powder of Example 1 Fe 30 < Powder 2
The same results as in Example 1 were obtained when the same treatment as in Example 1 was performed except that 10 parts of the μm material was used.

[Comparative Example 1] The same treatment as in Example 5 was carried out except that 15 parts of the magnetic powder of Example 5 was used. The scales were spread unevenly on the developing sleeve and the coating was uneven.

[Comparative Example 2] When the same treatment as in Example 1 was performed except that 0.5 parts by weight of the magnetic powder of Example 1 was used, the same results as in Comparative Example 1 were obtained.

[Brief explanation of the drawing]

Figure 1 shows the number average particle diameter of the magnetic material and the @4
1-Graph showing the relationship with quantity.

Claims (1)

[Claims] A latent image holding member that holds a latent image on its surface and a toner carrying member that carries insulating toner are arranged with a certain gap in a developing section, and the toner is transferred to the toner carrying body by magnetic means. In a color development method, the coated layer is regulated to a thickness thinner than the gap, conveyed to a developing section, and developed while applying an alternating electric field to the toner carrier.
A color developing method characterized in that the relationship between Y weight factor and magnetic particle size X11m satisfies the following formula. Y≦60X”23 However, 0.01≦X≦5 (μm)