JP2744790B2 - Electrophotographic development method and its developer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a triboelectric charging member having a function of applying triboelectric charging to an electrostatic image developing toner used in electrophotography, electrostatic printing, and the like. For example, the present invention relates to an electrophotographic developing method using a carrier for imparting frictional charge to toner, a transfer regulating member such as a sleeve or a doctor blade, or another frictional charge imparting member, and a developer thereof.

(Prior art)

Generally, when an inorganic hard fine powder such as colloidal silica, metal oxide powder, or ceramic is added to the toner, the fluidity of the toner is improved, and the toner replenishability is improved. Since these fine powders have very good triboelectrification, sufficient charge can be obtained without using a charge control agent. Further, they have a polishing effect on the surface of the carrier and the surface of the photoreceptor, and thus contribute to prevention of spent of the carrier and prevention of filming of the photoreceptor. However, since these fine powders are hygroscopic in a high-humidity atmosphere, the toner to which they are added has a higher amount of charge at high humidity than low humidity and normal humidity, regardless of the frictional charging member used. There was a disadvantage that it was greatly reduced.

〔Purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic developing method which overcomes the conventional disadvantages, prevents a decrease in the charge amount of a toner in a high humidity atmosphere, and improves the durability of a developer, and to provide the developer. .

〔Constitution〕

The present inventors have conducted intensive studies to achieve the above object, and as a result, use a toner containing inorganic hard fine powder, and use a triboelectric charging member coated with a silicone resin containing an aminosilane coupling agent. A developing method characterized by providing a toner containing inorganic hard fine powder and a developer containing carrier particles obtained by coating core particles with a silicone resin containing an aminosilane coupling agent as a main component. It has been found that the purpose can be achieved.

According to the developing method of the present invention, the charge amount hardly decreases in a high humidity atmosphere.

The inorganic hard fine powder in the present invention is, for example, colloidal silica, alumina, titanium dioxide, barium titanate, calcium titanate, zinc oxide, magnesium oxide, tin oxide and the like. The particle size of these fine powders is desirably 3 μm or less. In general, the amount of the inorganic hard fine powder added to the toner is preferably 0.01 to 3% by weight.

The frictional charging member is a carrier core member that imparts frictional charging to the toner, a transfer regulating member such as a sleeve or a doctor blade, or another frictional charging member.

Further, various thermoplastic resins can be used as the toner. For example, polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer Copolymer, styrene-maleic acid copolymer, styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-acrylic acid Octyl copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylate copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer,
Styrene-based resins (styrene or styrene-butyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, etc.), styrene-α-methyl methyl acrylate copolymer, styrene-acrylonitrile-acrylate copolymer, etc. (Homopolymer or copolymer containing styrene substituent), vinyl chloride resin, styrene-vinyl acetate copolymer, rosin-modified maleic resin, epoxy resin, polyester resin, polyethylene, polypropylene, ionomer resin, polyurethane resin, ketone resin And heat-fusible resins such as ethylene-ethyl acrylate copolymer, xylene resin and polyvinyl butyral, and waxes such as natural or synthetic wax. These are used alone or in combination.

The toner may contain a colorant or a magnetic material. Colorants include carbon black, chromium-containing monoazo dye, nigrosine dye, aniline blue, calco oil blue,
Examples thereof include chrome yellow, ultramarine, quinoline yellow, methylene blue chloride, monastral blue, malachite green oxalate, lamp black, rose bengal, monastral red, Sudan black BM, and mixtures thereof. Metal powders such as Co, Fe, Ni, etc. as magnetic materials; alloys or mixtures of metals such as Al, Co, Cu, Fe, Pb, Ni, Mg, Sn, Zn, Au, Ag, Se, Ti, W, Zr A metal oxide such as iron oxide and nickel oxide, or a metal compound containing the same; a ferromagnetic ferrite; or a mixture thereof.

The triboelectric charging member according to the present invention is coated with a silicone resin containing an aminosilane coupling agent. In general, the amount of the aminosilane coupling agent added to the silicone resin is preferably 0.1 to 10% by weight.

Aminosilane coupling agent used in the present invention have the general formula, provided that R _m SiY _n, R is an alkoxy group or a chlorine atom, Y is a hydrocarbon group containing an amino group, _m is an integer of 1 to 3, _n May be a silane coupling agent represented by an integer of 3 to 1. In particular, a preferred aminosilane coupling agent to be used in the present invention is represented by the following structural formula.

H ₂ NCH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ , H ₂ NCH ₂ CH ₂ CH ₂ Si (OC ₂ H ₅ ) ₃ , H ₂ NCONHCH ₂ CH ₂ CH ₂ Si (OC ₂ H ₅ ) ₃ , H ₂ NCH ₂ CH ₂ NHCH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ , H ₂ NCH ₂ CH ₂ NHCH ₂ CH ₂ NHCH ₂ CH ₂ CH ₂ · Si (OCH ₃ ) ₃ , H ₅ C ₂ OCOCH ₂ CH ₂ NHCH ₂ CH ₂ CH ₂ · Si (OCH ₃ ) ₃ , H ₅ C ₂ OCOCH ₂ CH ₂ NHCH ₂ CH ₂ NHCH ₂ CH ₂ · CH ₂ · Si (OC
H ₃ ) ₃ , H ₅ C ₂ OCOCH ₂ CH ₂ NHCH ₂ CH ₂ NHCH ₂ CH ₂ · NHCH ₂ CH ₂ NHCH ₂ CH _{2
· CH 2 · Si (OCH 3} ) 3, H 3 COCOCH 2 CH 2 NHCH 2 CH 2 NHCH 2 CH 2 CH 2 · Si (OCH 3) 3, (C ₄ H ₉ ) ₂ NCH ₂ CH ₂ CH ₂ .Si (OCH ₃ ) ₃ , (C ₄ H ₉ ) ₂ NCH ₂ CH ₂ CH ₂ .Si (OC ₂ H ₅ ) _{3 and the} like.

The alkoxy group of the above compound may be a chlorine atom. These silane coupling agents may be used alone or in a mixture of two or more.

As the silicone resin containing the aminosilane coupling agent, any conventionally known silicone resin may be used, such as straight silicone and alkyd, polyester, which consist only of an organosiloxane bond.
A silicone resin modified with epoxy, urethane, or the like may be used.

In the above formula, R ₁ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a phenyl group, R ₂ and R ₃ are a hydrogen group, a carbon atom 1
An alkyl group of 4 to 4, an alkoxy group having 1 to 4 carbon atoms,
Phenyl group, phenoxy group, alkenyl group having 2 to 4 carbon atoms, alkenyloxy group having 2 to 4 carbon atoms, hydroxy group, carboxyl group, ethylene oxide group, glycidyl group or R ₄ and R ₅ are a hydroxy group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, and 2 to 2 carbon atoms.
4, an alkenyloxy group, a phenyl group, a phenoxy group,
k, l, m, n, o, and p represent an integer of 1 or more.

Each of the above substituents may have a substituent such as an amino group, a hydroxy group, a carboxyl group, a mercapto group, an alkyl group, a phenyl group, an ethylene oxide group, a glycidyl group, and a halogen atom, in addition to the unsubstituted one. .

For example, straight silicone resin as a commercial product,
There are KR271, KR255, KR152 made by Shin-Etsu Chemical, SR2400, SR2406 made by Toray Silicone, etc. The modified silicone resin is KR206 (alkyd-modified), KR5208 (acrylic-modified), ES1001N (epoxy-modified), KR305 (urethane Denatured), Toray Silicon SR2115 (epoxy modified), SR
2110 (alkyd denaturation).

As the carrier core material, any known carrier core material can be used, and iron, nickel, a metal or alloy such as aluminum, particles of a metal oxide or a metal compound containing these, and further, glass, silicon carbide, etc. Particles are used.

Further, as a base material of the triboelectric charging member in the form of a sleeve or a doctor blade, a conventionally used sleeve or doctor blade such as a metal or alloy such as iron, aluminum, and stainless steel, a nonmetallic compound such as plastic, and rubber can be used. . Incidentally, as a method of coating the surface of the triboelectric charging member with a silicone resin containing aminosilane,
Aminosilane is added to a silicone resin, these are dissolved in a solvent, and then applied to the base material of the triboelectric charging member by dipping, spraying, brushing, or the like, and dried.

In addition, in silicone resin, for reinforcement and friction prevention,
Metal oxides such as silica, silicon carbide and titanium oxide, carbon, carbon fibers, glass and the like may be contained.

Next, a specific production example of the friction band imparting member used in the developing method of the present invention will be described below.

Production Example 1 Silicone resin (SR2406, Toray silicone) 100 parts by weight Aminosilane (H ₂ NCH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ ) 1 part by weight Toluene 100 parts by weight The above mixture was stirred with a homomixer for 15 minutes and coated. A layer forming liquid was prepared.

This liquid was applied to the surface of a spherical iron powder having an average particle size of 100 μm using a fluidized bed type coating device, and then baked at 200 ° C. for 5 hours to obtain a coated carrier having an average film thickness of 1.0 μm.

Production Example 2 Silicone resin (KR250, Shin-Etsu Chemical Co., Ltd.) 100 parts by weight aminosilane ((C ₄ H ₉ ) ₂ NCH ₂ CH ₂ CH ₂ Si (OC
H ₃ ) ₃ ) 2 parts by weight Toluene 100 parts by weight The above mixture was stirred for 15 minutes with a homomixer to prepare a coating layer forming liquid.

This solution is applied to the surface of ferrite particles having an average particle size of 70 μm,
After coating using a fluidized bed coating apparatus, the coating was baked at 250 ° C. for 2 hours to obtain a coated carrier having an average film thickness of 1.2 μm.

Production Example 3 Using the same coating layer forming liquid as used in Production Example 1, a film having an average film thickness of 5 μm was formed on the toner conveying member 2 shown in FIG. 1 by dipping. Then 250 ° C
For 5 hours to obtain the toner conveying member 2 shown in FIG.

Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 Styrene-n-butyl methacrylate copolymer 90 parts Carbon black 10 parts After kneading them, they were pulverized and classified to obtain an average particle diameter of 12.0 μm.
And hydrophobic silica R972 (manufactured by Nippon Aerosil Co., Ltd.)
Was externally added and mixed to obtain a toner. Using this carrier, a developer having a toner concentration of 2 wt% was prepared using the carrier of Production Example 1.

This developer was conditioned at low temperature and low humidity (10 ° C., 20%) and high temperature and high humidity (30 ° C., 90%) for 5 hours, and the charge amount was examined. The charge amounts were −25.3 μc / g and −23.1, respectively. μc / g. Therefore, in each environment, Ricoh FT60
When the image was displayed using 80, normal temperature and normal humidity (20
(° C, 60%).

When a running test was performed on 100,000 sheets at room temperature and normal humidity, the charge amount did not decrease even after 100,000 sheets were obtained, and high image quality was obtained without background contamination.

Comparative Example 1 A coated carrier having an average film thickness of 1.0 μm was obtained in exactly the same manner as in Production Example 1 except that no aminosilane was contained.

Using this carrier, high humidity,
The charge amount at low humidity was examined. As shown in Table 1, the results showed that the decrease in charge amount at high humidity was large. Further, when an image was taken out in each environment, the image at high humidity was very soiled.

Example 2 One part of titanium oxide P25 (manufactured by Nippon Aerosil Co., Ltd.) was externally mixed with the toner having an average particle diameter of 12.0 μm produced in Example 1 to obtain a toner. Using this toner, a developer having a toner concentration of 3 wt% was prepared using the carrier of Production Example 2.

In the same manner as in Example 1, a test under high humidity and low humidity and a running test of 100,000 sheets under normal humidity were performed using FT6080. As shown in Table 1, the decrease in charge amount at high humidity was extremely small, and the image quality was the same as the initial image after running 100,000 sheets.

Comparative Example 2 A coated carrier having an average film thickness of 1.2 μm was obtained in exactly the same manner as in Production Example 2 except that no aminosilane was contained.

Using this carrier, high humidity,
The charge amount at low humidity was examined.

As shown in Table 1, the results showed that the charge amount under high humidity was significantly reduced. Further, when an image was taken out in each environment, the image at high humidity was very soiled.

Example 3 A developer having a toner concentration of 2% by weight was prepared using the toner used in Example 1 and the carrier of Production Example 2.

Table 1 shows the results of the high and low humidity tests and the running test at normal humidity.

Comparative Example 3 A coated carrier having an average film thickness of 1.2 μm was obtained in exactly the same manner as in Production Example 2 except that no aminosilane was contained.

Using this carrier, high humidity,
The charge amount at low humidity was examined. As shown in Table 1, the results showed that the decrease in charge amount at high humidity was large.

Example 4 The toner used in Example 1 was put into the electrophotographic one-component developing apparatus shown in FIG. 1 and conditioned at high humidity and low humidity for 5 hours each. After suction, the charge amount of the toner was examined. -15.1μc / at high humidity
g and -16.3 μc / g at low humidity.

Also, when running 100,000 sheets at normal temperature and humidity,
As shown in Table 1, there was almost no decrease in the charge amount, and high image quality without background dirt, which was the same as in the initial stage, was maintained.

Comparative Example 4 A toner transport member 2 for a one-component developing device shown in FIG. 1 was prepared in exactly the same manner as in Production Example 3 except that no aminosilane was contained. The same experiment as in Example 4 was performed by putting the toner used in Example 2 into this one-component developing device.
As shown in Table 1, the charge amount decreased at high humidity as shown in Table 1.
The image at high humidity was very dirty.

Comparative Example 5 A toner was prepared in exactly the same manner as in Example 1 except that hydrophobic silica R972 was not added, and a developer having a toner concentration of 2 wt% was prepared using the carrier of Production Example 1. This developer is
After adjusting the humidity for 5 hours at low temperature and low humidity (10 ° C, 20%) and high temperature and high humidity (30 ° C, 90%), the charge amount was measured.
It was 2.6 μc / g and −7.1 μc / g (charge reduction ratio 44%). When images were displayed using Ricoh's FT6080 in each environment, soiling occurred even at low temperatures,
The dirt at high temperatures was even worse.

Comparative Example 6 Instead of the aminosilane coupling agent, γ-glycidoxypropyltrimethoxysilane of the following structural formula was used. Using the same method as in Production Example 1 to obtain an average film thickness of 1.0 μm.
m of coated carriers were prepared.

The same toner as in Example 1 was used for this carrier, and a developer was prepared in exactly the same manner as in Example 1. When the charge amount at high humidity and low temperature was examined, it was -23.1
μc / g and −12.3 μc / g (charge reduction ratio 47%).
When an image was taken out in each environment, high image quality was obtained at a low temperature, but background soiling was severe at a high temperature.

[Effect] By using a toner containing inorganic hard fine powder and using a triboelectric charging member coated with a silicone resin containing an aminosilane coupling agent, it is possible to prevent a decrease in the charge amount of the toner at high humidity. In addition, the life of the developer can be extended.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an electrophotographic developing apparatus used in Example 4 and Comparative Example 4 of the present invention. DESCRIPTION OF SYMBOLS 1 ... Electrostatic latent image carrier, 2 ... Toner conveying member 3 ... Elastic blade, 4 ... Sponge roller 5 ... Agitating blade, 6 ... Toner, 7 ... Toner tank

Claims (2)

(57) [Claims] 1. An electrophotographic development method using a toner containing inorganic hard fine powder and using a triboelectric charging member coated with a silicone resin containing an aminosilane coupling agent. 2. An electrophotographic developer comprising, as main components, a toner containing an inorganic hard fine powder and carrier particles obtained by coating core particles with a silicone resin containing an aminosilane coupling agent.