JP2002351145A - Developer for positive charge cyan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developer for positive charge cyan which does not give rise to another problems while preventing charge-up. SOLUTION: The developer for magenta consisting of toners prepared by adding and mixing conductive inorganic particulates with coloring resin particles containing at least a binder resin and 'C.I. Pigment Blue 15:35 or 15:4' as a coloring agent and carriers consisting of core particles and resin coats disposed on the surface of the core particles, in which the coverage of the resin coats on the surfaces of the core particles is 60 to 90% and the amount of the conductive inorganic particles to be added is 0.2 to 2.0 wt.% per 100 wt.% colored resin particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic latent image such as an electrophotographic method, and more particularly, to a cyan developer used in a full-color image forming apparatus such as a full-color copying machine.

[0002]

2. Description of the Related Art In recent years, electrophotographic image forming apparatuses such as copiers and printers use three primary color toners of yellow, magenta and cyan in addition to a conventional monochrome image using only black toner. Further, a full-color copying machine, a full-color printer, and the like, which enable various color reproductions by appropriately overlapping the color toner and the black toner, are often found in the market.

[0003] Among them, C.I. I. Pigment Blue 15: 3 or 15: 4 is often used. This pigment has a strong positive charge property, and when a toner is prepared using this pigment as a colorant, the charge amount increases due to frictional stirring of the toner and the carrier, particularly in a two-component developing method, but the resistance between the carrier and the toner is high at that time. In this case, a problem of positive charge-up in which the charge amount increases without leaking the charge easily occurs.

In order to improve this problem, for example, carbon is added to the resin coat of the carrier, inorganic fine particles are added and mixed (externally added) to the toner, and a negative charge control agent is added. Have been addressed.

[0005]

However, even if the above-described method can suppress the positive charge-up, other problems are likely to occur. That is,
In the method of adding carbon to the resin coat of the carrier,
Since the hue of cyan is hindered, a good image cannot be formed in full-color image formation. In addition, in the method of externally adding inorganic fine particles to the toner, a certain amount of addition is required. However, in this case, the hue is easily inhibited, and the transparency is adversely affected. Further, in the method of adding the negative charge system charge control agent, the amount of the oppositely charged toner increases, so that fogging is likely to occur.

As described above, although there is a method of improving the charge-up itself, other problems easily occur, and it is difficult to obtain a satisfactory developer for cyan.

The present invention has been made in view of the above problems, and has as its object to provide a positively charged cyan developer which prevents charge-up and does not cause other problems. Is what you do.

[0008]

According to the present invention, at least a binder resin and C.I. I. Pigment Blue 15: 3 or 15: 4 as a colorant, a toner in which conductive inorganic fine particles are added and mixed, and a carrier having core particles and a resin coat provided on the surface of the core particles. In the developer for positively charged cyan, the resin coating coverage on the surface of the core particles is 60 to 90%, and the amount of the conductive inorganic fine particles is 0.2 to 2.0% by weight based on 100% by weight of the colored resin particles. % Of a positively charged cyan developer.

As a result of intensive studies, the present inventors have found that C.I. I. When Pigment Blue 15: 3 or 15: 4 is used, by adding a specific amount of conductive inorganic fine particles and setting the resin coating coverage of the carrier to a specific value, charge-up can be suppressed over a long period of time and uniform charging can be achieved. It has been found that the toner can be imparted with no adverse effect on hue and transparency.

The amount of the conductive inorganic fine particles is 0.2% by weight.
90% or below
Is exceeded, charge-up occurs and the image density decreases. If the resin coating coverage of the carrier is less than 60%, the surface of the carrier core is exposed too much, so that the charge imparting property to the toner is not uniform, and problems such as fogging occur.
If the amount of the conductive inorganic fine particles exceeds 2.0%, the hue and the transparency are remarkably reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A carrier is mainly made of the following materials.

[Core Particles] The core particles used in the present invention are generally made of a known magnetic material such as sintered ferrite, magnetite, lithium, manganese or iron powder.

The particle size of the core particles is generally 20 to 200 μm, particularly 3
Those having a thickness of 0 to 150 μm are generally used.

As the magnetic powder used for the production of the core particles, any of magnetic powders known per se can be used. For example, iron trioxide (Fe ₃ O ₄ ), iron sesquioxide (γ -Fe ₂ O ₃ ), ferromagnetic iron oxide, zinc oxide (ZnFe ₂ O ₄ ), yttrium iron oxide (Y ₃ Fe ₅ O)
₁₂ ), cadmium oxide (CdFe ₂ O ₄ ), gadolinium iron oxide (Gd ₃ Fe ₅ O ₁₂ ), copper iron oxide (CuFe ₂ O ₄ ),
Lead iron oxide (PbFe ₁₂ O ₁₉ ), neodymium iron oxide (Nd
FeO ₃ ), barium iron oxide (BaFe ₁₂ O ₁₉ ), iron manganese oxide (MnFe ₂ O ₄ ), lanthanum iron oxide (LaF
eO ₃ ) or ferrites such as composites thereof,
Alternatively, ferromagnetic metals or alloys such as iron powder (Fe), cobalt powder (Co) and nickel powder (Ni) can be used alone or in combination. The particle shape of the magnetic material is not particularly limited, and may be any shape such as a spherical shape, a cubic shape, and an irregular shape.

[Resin Coat] As the resin used for the resin coat for coating the core particles used in the present invention, for example, (meth) acrylic resin, styrene resin, styrene- (meth) acrylic resin, olefin resin (polyethylene) , Chlorinated polyethylene, polypropylene, etc.), polyester resin (polyethylene terephthalate, polycarbonate, etc.), unsaturated polyester resin, vinyl chloride resin, polyamide resin, polyurethane resin, epoxy resin, silicone resin, fluorine resin (Polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, etc.), phenolic resins, xylene resins, diallyl phthalate resins, and the like. The above resins may be used alone or in combination of two or more.

The resin coat may contain a small amount of an additive such as silica, alumina, or a fatty acid metal salt for adjusting the properties of the resin coat, if necessary.

As a method for coating the core particles with a resin, any of a method such as a mechanical mixing method, a spraying method, a dipping method, a fluidized bed method and a tumbling bed method can be adopted.

Examples of the solvent for resin coating include aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as trichloroethylene and perchloroethylene, ketones such as acetone and methyl ethyl ketone, and cyclic ethers such as tetrahydrofuran. And alcohols such as methanol, ethanol and isopropanol.

The carrier of the present invention is used at a resin coating coverage of 60 to 90%, preferably 6 to 90%.
5 to 85%.

The toner is mainly made of the following materials. [Binder Resin] As the fixing resin used in the present invention, for example, polystyrene, chloropolystyrene, poly-α-
Methylstyrene, styrene-chlorostyrene copolymer,
Styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-
Vinyl acetate copolymer, styrene-maleic acid copolymer,
Styrene-acrylic acid copolymer (styrene-acrylic acid copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer Polymer, styrene-phenyl acrylate copolymer), styrene-methacrylic acid copolymer (styrene-methacrylic acid copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene- Butyl methacrylate copolymer, styrene-octyl methacrylate copolymer, styrene-phenyl methacrylate copolymer), styrene-α-methyl methacrylate copolymer, styrene-acrylonitrile-acrylate copolymer and the like. Styrene resin (including styrene or styrene-substituted Polymer or copolymer), polyvinyl chloride, low molecular weight polyethylene, low molecular weight polypropylene, ethylene-ethyl acrylate copolymer, polyvinyl butyryl, ethylene-vinyl acetate copolymer, rosin-modified maleic resin, phenolic resin, Epoxy resin,
Examples thereof include a polyester resin, an ionomer resin, a polyurethane resin, a silicone resin, a ketone resin, a xylene resin, and a polyamide resin. These may be used alone or as a mixture of two or more.

[Conductive Inorganic Fine Particles] The conductive inorganic fine particles used in the present invention include titanium oxide, aluminum oxide (alumina), zinc oxide, zirconium oxide, cerium oxide, magnesium oxide, magnetite, iron oxide, tin oxide, and tin. Antimony and the like.

The conductive inorganic fine particles of the present invention are used in an amount of 0.2 to 2.0% by weight, preferably 0.4 to 1.8% by weight. Further, two or more kinds of conductive inorganic fine particles may be added. In this case, the total amount of the conductive inorganic fine particles may be in the range of 0.2 to 2.0% by weight. Further, it may be used in combination with non-conductive inorganic fine particles such as silica. However, the added amount of the non-conductive inorganic fine particles is not calculated in the range of the added amount of the conductive inorganic fine particles.

[Charge Control Agent] In order to control the toner charge, a known charge control agent is used depending on the charge polarity of the toner. For example, metal complex dye, metal naphthenate, fatty acid metal soap, resin acid soap,
A charge controlling agent such as acrylic acid or methacrylic acid ester resin is used if necessary.

[Releasing Agent] In the present invention, a releasing agent is blended and dispersed in the fixing resin in order to ensure offset resistance. Examples of such a releasing agent include paraffin wax and petroleum wax. , Polyethylene wax, polypropylene wax, aliphatic hydrocarbon wax such as oxidized polyethylene wax, montan wax, carnauba wax, beeswax, wood wax, or oleyl palmitoamide, stearyl ercamide, 2-stearamide ethyl stearate, ethylene Fatty acid amides such as bisfatty acid amides and silicone oils can be mentioned. Generally, an aliphatic hydrocarbon wax is preferred, and most preferably, a polyolefin wax such as polyethylene wax or polypropylene wax or carnauba wax can be used. From the viewpoint of dispersibility, a release agent having a lower melting point than the fixing resin is particularly preferably used.

[0025]

EXAMPLES The toners and two-component developers of Examples 1 to 18 and Comparative Examples 1 to 24 were produced as follows.

According to the following formulation, each component was mixed with a mixer, and then melt-kneaded with a twin-screw extruder to prepare a resin composition for toner.

B. Fixing resin (styrene-acrylate copolymer) 100 parts by weight I. Pigment Blue 5 parts by weight Charge control agent (polyacrylate) 5 parts by weight Release agent (polyolefin wax) 5 parts by weight C.I. I. Pigment Blue 15: 3 or 15:
No. 4 is as described in Tables 1 to 5 described below.

The obtained resin composition for toner was finely pulverized by an air-flow type pulverizer and classified by an air classifier to obtain toner core particles having an average particle size of 8 μm on a volume basis.

To 100% by weight of the toner core particles, alumina or titanium oxide was added in the amounts shown in Table 1 and mixed with a Henschel mixer to obtain a toner composition for cyan developer.

Next, a spherical ferrite (with an average particle size of 60 μm)
m) 100 parts by weight of the core material composed of Si, when the coating resin of the carrier described in Tables 1 to 5 is Si, 1 part by weight of the silicone resin is dispersed in toluene; When the coating resin was F, 1 part by weight of a fluororesin was dispersed in tetrahydrofuran to prepare a resin solution (coating solution). This resin solution is subjected to heat treatment at 300 ° C. for about 30 minutes in a fluidized bed after spray coating the above core material using a fluid coating apparatus using a fluid coating apparatus.
Carriers having a resin coating coverage as shown in Table 2 were produced. 5 parts by weight of the above toner composition was mixed with 100 parts by weight of the carrier thus obtained in a 3 L container ball mill to obtain developers of Examples and Comparative Examples.

With respect to the developers of the above Examples and Comparative Examples,
30 using a modified machine of S3500 (manufactured by Kyocera Corporation)
A print test was performed on 000 sheets, and the print performance before and after the test was compared. The image is cyan only and no other colors are used. As the performance, hue, transparency, ID (image density), FD (fog density = density of a portion where no image is formed), and toner charge amount are measured. ID is 1.
If it is 4 or more, there is no problem. FD is 0.008
If it is less than this, there is almost no problem as an image, but the closer to 0, the better. If the charge amount of the toner is about 13 (μC / g) or less, a problem easily occurs. This is because the lower the charge amount of the toner, the higher the FD. As long as the FD is not increased, a small amount of toner charge does not cause much problem.
The transparency is a problem if it is less than 80%, and the hue is a problem as an image because the hue of cyan is impaired if ΔE is 2 or more.

The numerical values of the two-component developers of the above Examples and Comparative Examples were measured by the following methods.

(ID, FD) Measured with a digital reflection densitometer manufactured by Tokyo Denshoku Co., Ltd.

(Charge Amount of Toner) Measured by a blow-off charge amount measuring device manufactured by Toshiba Corporation.

(Transparency) A solid image (0.5 mg / cm ² ) of a sample toner was transferred onto an OHP film, and the visible light region (380 nm) was measured using an ultraviolet / near infrared spectrophotometer manufactured by Hitachi.
The transparency was evaluated by measuring the maximum transmittance at ７780 nm).

(Hue) The hue was measured with SE2000 manufactured by Nippon Denshoku Industries Co., Ltd. under the conditions of a light source C and a visual field of 2 degrees. In this measurement, the difference between the hue of the toner after addition of the external additive and the reference hue was defined as ΔE based on the hue of the toner to which no external additive was added for each of the examples and comparative examples. It is described in.

(Resin coating coverage)
After observing the M-photograph, the photograph was analyzed by an image analyzer, and the difference in contrast caused the resin-coated portion on the smooth portion of the core particle, the resin-coated portion on the void portion of the core particle, The area of each of the non-coated portion on the smooth portion and the non-coated portion on the void portion of the core particle was determined, and the resin coating coverage was determined from the ratio.

Tables 1 to 5 are as follows.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

[Table 5]

[0044]

As described in detail above, by using the developer for positively charged cyan of the present invention, it is possible to prevent charge-up, to prevent hue and transparency, and to prevent fog for a long period of time. An image having a density can be formed.

Claims (1)

[Claims] (1) a binder resin and C.I. I. Pigment Blue 15: 3 or 15: 4 as a coloring agent, a toner in which conductive inorganic fine particles are added and mixed, and a carrier having core particles and a resin coat provided on the surface of the core particles. In the developer for positively charged cyan, the resin coating coverage on the surface of the core particles is 60 to 90%, and the amount of the conductive inorganic fine particles is 100% by weight of the colored resin particles.
0.2 to 2.0% by weight of the developer for positively charged cyan.