JPH04101158A - Electrostatic latent image developing toner - Google Patents

Abstract

PURPOSE:To obtain a stable and high image density and to prevent the splashing of the toner inside the device by adhering organic nonconductive particles and inorganic conductive fine particles on the surface of the toner mother particle. CONSTITUTION:On the surface of the toner mother particle incorporating a binder resin, the organic nonconductive fine particles and inorganic conductive fine particles are adhered at a quantity of totally 0.5-4.0wt.% of the toner mother particle. In this case, those two kinds of fine particles are necessary to be adhered on the surface of the toner mother particle and when the toner mother particle and those fine particles are only mixed in powder state, the desired effect is not obtained. Thus the stable and high image density is obtained and the splashing of the toner inside the device is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a toner for developing electrostatic latent images used in development processes such as electrophotography, electrostatic recording, and electrostatic printing.

The conventional electrophotographic method is widely known, and a visible image is formed through the following steps, for example.

■ The photoconductive insulating layer is uniformly charged by corona discharge, etc., and then light is selectively irradiated by image exposure or laser beam scanning exposure, and the charge on the irradiated area is dissipated to form an electrostatic latent image. .

■ This latent image is visualized using a developer called toner to form a visible image (development process).

■ A visible image is transferred directly or onto another substrate such as paper (transfer process) and then fixed (fixing process).

Also known is a method in which electrostatic latent images are formed by selectively charging with pin electrodes.

In either case, the developer is required to have strict characteristics because it has a great influence on the success or failure of the development process, transfer process, and fixing process, and in turn determines image characteristics, running costs, etc. of the device.

Developers are roughly divided into two component developers, which are two-component developers consisting of toner and carrier, and one-component developers, in which the toner itself functions as a carrier. It is broadly divided into a regular development method in which toner is attached to the latent image bearing portion of the photoreceptor, and a reversal development method in which toner is attached to the non-latent image bearing surface, but in both cases, the charging characteristics of the toner and its stability are important. Control becomes an important issue.

There have been no reports on adjusting or improving toner properties such as the amount of charge by electrostatically adsorbing non-conductive particles, conductive particles, charge control agents, pigments, etc. to toner base particles. However, each has its advantages and disadvantages,
The problem to be solved and the technical idea are different from the present invention.

JP 1-112255, JP 1-113761, JP 1-113762, JP 1-113764
Publication: Organic fine particles such as an acrylic polymer and inorganic fine particles such as silica are mixed and adhered to the surface of toner particles to improve charging properties, fixing properties, etc.

JP-A-58-68048: Conductive organic fine powder is attached to the surface of toner particles, and inorganic fine powder is further attached to this surface to increase the resistance of the toner and improve fluidity and anti-blocking properties. Improve.

Japanese Patent Publication No. 59-826: A conductive toner with high image density is obtained by attaching a specific carbon black to the surface of toner particles.

JP-A-56-81853: On the surface of toner particles,
Melts and adheres fine particles of fluid resin such as silicone resin and fluororesin to improve fluidity.

JP-A-57-129444: Electroconductive fine particles such as carbon black are attached to the surface of magnetic toner particles by a high-speed fluidization stirring method, and a magnetic toner with less fog can also be obtained by an insulating magnetic roll development method.

JP-A No. 62-246073: Melting point is 45-135
Fine particles as toner components such as magnetic material and charge control agent are attached to the surface of toner particles containing crystalline polymer at ℃, and mechanical impact force is applied to the particles to drive the fine particles onto the surface of the toner particles and hold them. This improves fixing properties such as offset properties.

JP-A-62-246074: Fine particles as toner components such as a magnetic material and a charge control agent having a specific particle size range are attached to the surface of toner particles for pressure fixing, and mechanical impact force is applied to the particles. By applying fine particles to the surface of the toner particles and holding them therein, the pressure fixing properties of the toner are improved.

JP-A-62-246075: By attaching conductive fine particles to magnetic toner particles and applying a mechanical impact force thereto, the conductive particles are implanted into the surface layer of the toner particles and held therein. As a result, a conductive magnetic toner suitable for dielectric development is obtained.

Problems to be Solved by the Invention The present invention provides a toner that prevents excessive charge from being accumulated in the toner and allows stable high-density images to be obtained even during continuous printing.

A piece of stick to Kikun 1.

The toner for developing electrostatic latent images of the present invention is:

(A) organic non-conductive fine particles and (B) inorganic conductive fine particles are added to the surface of toner base particles containing a binder resin in a total amount of 0.5 to 4.0 weight relative to the toner base particles. It is characterized by being fixed in an amount of %.

The present invention will be explained in more detail below.

In the present invention, both (A) organic non-conductive fine particles and (B) inorganic conductive fine particles are fixed to the surface of toner base particles containing a binder resin.

Chargeable (A) organic non-conductive fine particles and conductive (B)
By adhering it to the surface of toner base particles in combination with inorganic conductive fine particles, appropriate chargeability can be imparted to the toner. In addition, CB) Inorganic conductive fine particles are fixed and stably present on the toner surface, forming a kind of conductive path between the toner particle surface and inside, preventing unnecessary charge-up of the toner, so it can last for a long time. The toner has stable charging characteristics and stable image density. Furthermore, since the electrostatic cohesive force is relaxed, sleeve adhesion is prevented.

As a result, high image density can be stably obtained.

Moreover, toner with less scattering can be obtained.

(A) The organic non-conductive fine particles are used to control the chargeability of the toner, and depending on the characteristics required of the toner, positively chargeable or negatively chargeable particles are used. (A) As the organic non-conductive fine particles, spherical resin beads with a particle size of 0.2 μm or less are suitable, and specifically, polystyrene, styrene copolymers, acrylic resins such as polymethyl methacrylate, various Acrylic copolymers, nylon, polyethylene, polypropylene, fluororesins, crosslinked products thereof, and the like can be used. Regarding the charging level and polarity, desired levels of polarity and charging can be obtained by changing the material, polymerization catalyst, surface treatment, etc.

(B) As the inorganic conductive fine particles, carbon black, SnO, conductive Tie2, etc. are used. Conductive T i O2 is obtained by coating the surface of Ti○2 fine particles with a transparent conductive film such as ITO.

(B) Inorganic conductive fine particles have a resistance of 102Ω・Cl1
The particle size is preferably 1 or less, and the particle size is preferably 0.2 μm or less.

The total amount of both fine particles (A) and (B) is 0.5 to 4.0% by weight, preferably 1.0% by weight, based on the toner base particles.
It is fixed in an amount of 5 to 4.0% by weight. This amount of adhesion is 0.
When the amount is less than 5% by weight, the coverage of the additive particles on the surface of the base particles is small, and the addition effect is insufficient. On the other hand, 4
If it exceeds % by weight, it will be added excessively to the surface of the base particles, and unfixed particles will be likely to occur.

In addition, the adhesion ratio of both (A) and (B) fine particles is (A)
Although it depends on the chargeability of the organic non-conductive fine particles and the conductivity and specific gravity of the (B) inorganic conductive fine particles, the weight ratio is (A)/
(B) is preferably in the range of 0.15 to 5.0.

In the present invention, it is necessary to fix both (A) and (B) fine particles to the surface of the toner base particles, and simply mixing the toner base particles and these fine particles in powder form will not produce the desired effect. Therefore, it is not possible to obtain a stable high image density and prevent toner from scattering inside the machine.

The adhesion of these fine particles to the surface of the toner base particles is caused by, for example,
Toner base particles, (A) organic non-conductive fine particles and (B
) Inorganic conductive fine particles are mixed uniformly at the same time, these fine particles are electrostatically attached to the surface of the toner base particles, and then a mechanical impact force is applied to drive these fine particles into the toner base particles to fix them. This is done by These fine particles are not completely embedded in the toner base particles, but are fixed so that a portion thereof protrudes from the toner base particles. In addition, fine particles can also be fixed to the surface of toner base particles by the methods described in the publications listed in the "Prior Art" section.

Alternatively, first, (A) organic non-conductive fine particles may be mixed and fixed to the toner base particles, and then (B) inorganic conductive fine particles may be fixed thereon. After fixing the fine particles, (A) organic non-conductive fine particles may be fixed. Preferably, both of the fine particles are fixed simultaneously, or (A) the organic non-conductive fine particles are fixed, and then (B) the inorganic conductive fine particles are fixed.

The toner base particles of the present invention have the same structure as general non-magnetic toner particles, and may contain, for example, a binder resin, a colorant, a charge control agent, an anti-offset agent, and the like.

Further, as the toner base particles of the present invention, magnetic particles to which a magnetic material is added can also be used.

As the binder resin, vinyl resins typified by polystyrene resins such as styrene-acrylic copolymers, polyester resins, etc. are used.

Polystyrene resins include homopolymers of styrene threads such as styrene, α-methylstyrene, and α-chlorostyrene; copolymers of these styrene monomers; and other monomers copolymerizable with styrene monomers. Examples include copolymers of Other copolymerizable monomers include propylene, butadiene, vinyl chloride, vinyl acetate,
Maleic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate,
Phenyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-methacrylate
Examples include acrylic esters or methacrylic esters such as ethylhexyl and phenyl methacrylate.

The polyester resin is obtained by condensation polymerization or cocondensation polymerization of an alcohol component and a carboxylic acid component, and specific examples of each component used include the following.

Examples of divalent or trivalent or higher alcohol components include the following.

1) Diols: ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1°3-propylene glycol, 1,4
-Butanediol, neopentyl glycol, ■.

4-butynediol, 1,5-bentanediol, 1,
6-hexanediol, 1°4-cyclohexane dimetatool, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc.

2) Bisphenols: etherified bisphenols such as bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, and polyoxypropylenated bisphenol A.

3) Trihydric or higher alcohols; sorbitol.

1.2,3.6-hexanetetrol, 1゜4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2.4-butanetriol, 1,2.5-pentanetriol, glycerol, di glycerol, 2-methylpropanetriol,
2-methyl-1,2゜4-butanetriol, trimethylolethane, trimethylolpropane, 1,3゜5-
trihydroxymethylbenzene etc.

As the divalent or trivalent or higher carboxylic acids, divalent or trivalent carboxylic acids, their acid anhydrides, or their lower alkyl esters are used, and the following are exemplified as the carboxylic acids.

4) Divalent carboxylic acids; maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid,
Succinic acid, adipic acid, sepacic acid, azelaic acid, malonic acid, or n-butylsuccinic acid, n-butenylsuccinic acid, isobutylsuccinic acid, isobutenylsuccinic acid,
n-octylsuccinic acid, n-octenylsuccinic acid, n-
Alkyl or alkenyl succinic acids such as dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid, isododecenyl succinic acid, etc.

5) Trivalent or higher carboxylic acids; 1,2.4-benzenetricarboxylic acid (trimellitic acid), 1.2.5-benzenetricarboxylic acid, 2°5.7-naphthalenetricarboxylic acid, 1°2.4- Naphthalene tricarboxylic acid, 1°2.
4-butanetricarboxylic acid, 1,2゜5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2
-methylenecarboxypropane, 1,2.4-cyclohexanetricarboxylic acid, tetra(methylenecarboxyl)methane, 1,2,7.8-octanetetracarboxylic acid, pyromellitic acid, Empol trimer acid, etc.

As colorants, various pigments including carbon black,
Dyes; charge control agents such as quaternary ammonium compounds, nigrosine, nigrosine base, crystal violet, 1,2 type chromium alloy complex dyes; anti-offset agents and fixing aids such as low molecular weight polypropylene, low molecular polyethylene; Alternatively, olefin waxes such as modified products thereof can be used.

The toner base particles of the present invention can be obtained by a conventional method, for example, by melting and blending each component using a twin-screw extruder, kneader, etc., and then pulverizing and classifying the melt using a jet mill or the like. The average particle diameter of the toner base particles is preferably about 5 to 12 μm.

The toner of the present invention can be used as a one-component developer or as a two-component developer when mixed with a carrier, but it is particularly suitable for use as a non-magnetic one-component or two-component developer. preferable.

According to the toner of the present invention, (A
) By fixing organic non-conductive fine particles and (B) inorganic conductive fine particles, a stable high image density can be obtained even after printing a large number of sheets, and furthermore, toner scattering within the machine can be prevented.

Sue outside Example 1 After mixing the above mixture, it was pulverized with a jet mill.

The particles were classified to obtain toner base particles having an average particle size of 10 μm.

The following fine particles were thoroughly mixed with the toner base particles using a Henschel mixer and uniformly electrostatically adhered to the surface of the toner base particles.

Polystyrene beads (particle size 0.05μ) 3
Weight% Then, using a surface treatment device (Hybritizer, manufactured by Nara Machinery Co., Ltd.), these fine particles were fixed to the surface layer of the toner base particles by mechanical impact force to obtain the toner of Example 1.

Example 2 The following fine particles were immobilized on the surface of the same toner base particles as in Example 1 in the same manner. The charge amount of the obtained toner was about 4 μC/g lower than that of Example 1.

Polystyrene beads (particle size 0.05μm)
A toner was obtained by adding 3% by weight.

Example 3 The following fine particles were immobilized on the base particles of Example 1 in the same manner as in Example 1 to obtain a toner with a charge amount comparable to that of Example 1.

Polystyrene beads (particle size 0.05μ■) 3
Weight% Comparative Example 1 The following fine particles were similarly fixed on the surface of the same base particles as in Example 1 to obtain a toner of Comparative Example 1.

Polystyrene beads (particle size 0.05μ+m)
3wt%5i02
0.5% by weight Sio2 has a chargeability of opposite polarity to that of the polystyrene beads, so that the amount of charge of the toner was set to be the same as in Example 1.

Comparative Example 2 After immobilizing 3% by weight of the same polystyrene beads as in Example 1 onto the mother particles of Example 1, carbon black (E
Mixing Comparative Example 3 with external addition of 0.5 wt% of C) 3 wt% of the same polystyrene beads as in Example 3 were similarly immobilized on the base particles of Example 1, and then 3 wt% of the same conductive beads as in Example 3 were fixed.
A toner of a comparative example was obtained by externally adding and mixing 0.5% by weight of O2 (T-1).

Next, 4 parts by weight of the toner of the above example or comparative example was added to 100 parts by weight of ferrite carrier having an average particle size of 60 μm.
By adding parts by weight to make a two-component developer, Kyocera HHF-8
After repeated printing using a 00 laser beam printer, the image density was measured with a Macbeth densitometer, and the results are shown in FIG. Additionally, toner scattering inside the machine was visually observed.

As shown in FIG. 1, in the toners of Examples 1 and 2,
Although a slight decrease in density was observed, it was at a level that caused no problems, and there was no toner scattering. Note that in Example 2, the amount of charge was lower and an image with higher density was obtained.

In Example 3, almost the same results as in Example 1 were obtained.

Comparative Example 1 had a high initial concentration, but the concentration decreased significantly, and the concentration was low as with Comparative Examples 1 and 3.

In Comparative Example 2, the concentration was high and the concentration change was stable, but there was a lot of scattering.

Example 4 The following fine particles were immobilized on the base particles of Example 1 in the same manner to produce a toner.

Polystyrene beads (particle size 0.05μ) 2
It is a graph showing a change in weight percentage.

When this toner was evaluated in the same manner as above, good results similar to those of Example 1 were obtained.

[Brief explanation of the drawing]

Claims (1)

[Claims] 1. On the surface of toner base particles containing a binder resin, (A) organic non-conductive fine particles and (B) inorganic conductive fine particles are added in a total amount to the toner base particles. A toner for developing electrostatic latent images, characterized in that the toner is fixed in an amount of 0.5 to 4.0% by weight. 2. (B) The inorganic conductive fine particles are carbon black,
The toner for developing electrostatic latent images according to claim 1, which is tin oxide or conductive titanium oxide.