JP2532058B2 - Toner for electrostatic charge development - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electrostatic charge developing toner used in the fields of electrophotography and the like.

(Problems to be solved with conventional technology) Conventionally, as a developer for developing an electrostatic charge image formed on a latent image holding surface of an electrophotographic photoreceptor or the like, a two-component system developer including a carrier and a toner is used. A one-component developer (magnetic toner) that does not require a developer and a carrier is known.

The toner particles constituting these developers are usually resin,
It is colored fine particles containing a colorant or the like as a component. In the one-component developer, magnetic fine particles having magnetism are used as a coloring agent.

When the developer composed of these toner particles is repeatedly used in a PPC (plain paper copying machine) or the like, the following problems occur in practical use.

(1) Since the toner has a high insulating property, excessive triboelectric charges are accumulated in the developer, and defects such as a decrease in image density and image unevenness are likely to occur.

(2) On the surface of the photoconductor or the two-component developer, a film of toner is formed on the surface of the carrier, impairing its function and promoting deterioration.

In order to improve these problems, there is a method in which a carbon black having conductivity is attached to the toner. In the case of this method, it becomes possible to leak the excess electric charge in the developer. However, since carbon black is a powder having a strong cohesive property, it is difficult to add it uniformly, and even if it is added uniformly, the amount of electrostatic charge of the developer is greatly reduced and the toner is scattered. It becomes violent and easily contaminates the inside of the copying machine. In addition, it has a drawback that it cannot prevent the formation of a toner film on the surface of the photoreceptor or the carrier surface of the two-component developer because of poor durability.

On the other hand, a method of adding a metal oxide such as SiO ₂ or TiO ₂ to the toner is also known, but in this method, although it has the effect of preventing the formation of a toner film, it cannot prevent the accumulation of excess charges. Therefore, when it is repeatedly used, defects such as a decrease in image density are likely to occur.

Therefore, the toners containing these conventional additives each have merits and demerits in their performance, and the above-mentioned problems cannot be completely solved.

(Means for Solving Problems) The object of the present invention is as follows.

(1) To provide an electrostatic charge developing toner capable of leaking an excessively charged charge generated in a developer and maintaining a stable charge amount of the developer.

(2) To provide a toner for electrostatic charge development, which can favorably prevent a toner film formed on the surface of a photoreceptor or a carrier surface in a two-component developer.

Therefore, as a result of the inventors of the present invention, as a result of earnest research to solve the problems of the conventional toner in repeated use, the specific ratio of the nonstoichiometric compound of titanium oxide to titanium nitride was determined. The present inventors have found that a toner satisfying the above-mentioned object can be obtained by adding the fine powder of the additive to the outside of the toner or by including the fine powder in the toner. That is, the gist of the present invention is to provide at least a resin, a colorant and the following general formula mTiOx-nTiN (m is an arbitrary value within the range of 0.95 to 0.70, n is 0.05 to 0.30, where m + n = 1, and x is x). And an arbitrary value in the range of 1.00 to 1.50.), Which is a solid solution of a nonstoichiometric compound of titanium oxide and titanium nitride.

 Hereinafter, the present invention will be described in detail.

Various known components can be used as the resin component in the toner of the present invention. For example, styrene resin, epoxy resin, polyester resin and the like. A styrene resin is particularly preferable, and specifically, polystyrene, a styrene-acrylate copolymer, a styrene-methacrylate copolymer, or the like can be used alone or in combination. The weight average molecular weight is 1,000 to 500,000,
The range of 10,000 to 300,000 is preferable.

Examples of the colorant include inorganic pigments such as carbon black and dark blue; organic pigments such as azo and phthalocyanine; and dyes such as triphenylmethane and anthraquinone. These are contained in the toner in an amount necessary for obtaining a clear visible image, but usually,
20 parts by weight or less, preferably 10 parts by weight or less, relative to 100 parts by weight of the resin. In the case of a one-component developer, that is, a so-called magnetic toner, an alloy or compound containing a magnetic element such as iron, cobalt and nickel including magnetite and ferrite is contained as the magnetic powder in the toner. The average particle size of these magnetic powders is 0.1-3μ
m is suitable. The content is preferably in the range of 25 to 60% by weight based on the total weight of the toner.

The additive fine powder that can be used in the present invention is represented by the following general formula mTiOx-nTiN (m is an arbitrary value in the range of 0.95 to 0.70, n is 0.05 to 0.30, where m + n = 1 and x is 1.00 to 1.50). , Any non-stoichiometric compound of titanium oxide (TiOx)
It is a solid solution composed of titanium nitride (TiN) and a specific ratio. The ratio of TiOx and TiN must be within the above range. TiO
When the ratio of x is more than the above range or when TiOx is used alone, it is not preferable because the stability to the environment is poor and the durability is poor. Further, when the ratio of TiOx is smaller than the above (in other words, when the ratio of methane nitride is large), the hardness of the additive particles increases, and the degree of wear of the photoconductor tends to become severe, which is not preferable.

The average particle size of the additive fine powder according to the present invention is usually 3 μm.
The following is preferably 0.01 to 1 μm.

The electric resistance is 10 ⁶ Ωcm or less, preferably 10 ³ Ωcm
The following is good. When the electric resistance value is larger than the above-mentioned value, the ability to leak an excessive electric charge in the developer is remarkably inferior, or the ability to blink is lost, which is not preferable.

About 200 kg / cm ²
It is compression-molded into a columnar shape (diameter: 2.0 cm, thickness: about 0.5 cm) under pressure, and electrodes are attached above and below it, and a voltage of 10 V / cm is applied between the electrodes for measurement.

The additive fine powder according to the present invention gives good results both when it is added to the outside of the toner and when it is contained in the toner. In particular, the range of 0.01 to 2% by weight, preferably 0.05 to 1% by weight, per unit weight of toner is good. When it is contained in the toner, the amount is preferably 3 to 30% by weight, and more preferably 5 to 20% by weight, per unit weight of the toner. When added to the inside of the toner, the additive fine powder of the present invention usually has a vivid black appearance, so a coloring effect can be expected.

The additive fine powder according to the present invention is titanium dioxide (TiO ₂ ).
Is obtained by reducing fine powder of the above with a metal such as carbon or zinc in the presence of nitrogen at a high temperature. Structurally, a so-called penetration, in which a nitrogen atom enters the crystal lattice of a nonstoichiometric compound of titanium oxide, It forms a mold solid solution.

Specific examples of these additive fine powders include titanium black 12S, 20M (all of which are manufactured by Mitsubishi Metals Co., Ltd., trade names), and m = 0.9, n = n in the following general formula mTiOx-nTiN. It has a composition represented by 0.1 and x = 1.0.

A known charge control agent may be added to the electrostatic charge developing toner of the present invention, if necessary. Examples of positively chargeable charge control agents include nigrosine dyes, polyamine resins, amino group-containing styrene resins, and quaternary ammonium salts. Further, as a negatively chargeable charge control agent, C
Examples thereof include complex salt azo dyes containing r, Fe, Co and the like. The amount used is preferably 10 parts by weight or less based on 100 parts by weight of the resin.

In addition, various internal or external additives such as a low molecular weight olefin polymer for improving fixability may be added as a constituent component of the electrostatic charge developing toner of the present invention. It should be such that it does not interfere with the purpose.

Further, as a method for producing a toner, the above components may be kneaded with a kneader or the like, cooled, pulverized and classified, and externally added by a stirrer or the like as necessary. The average particle size of the toner is preferably 5 to 20 μm.

Carriers that can be mixed with the electrostatic charge developing toner of the present invention to form a developer in a two-component developer include, for example, iron powder, ferrite powder, and magnetite powder, all of which can be preferably used. Further, it may be a so-called coating carrier coated with various resins for the purpose of improving durability during continuous use. The average particle size of the carrier is preferably 10 to 200 μm. The mixing weight ratio of the carrier and the toner is preferably 100: 1 to 10.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist. In the examples, "part" is "part by weight".
Indicates. The charge amount was measured using a blow-off charge amount measuring device, and a reflection densitometer and a Hunter whiteness meter were used to measure image density and fog, respectively.

Example 1 As a resin, 100 parts of a styrene-butyl acrylate resin having a weight average molecular weight of about 70,000, 2 parts of carbon black as a colorant, 3 parts of a Cr-containing complex salt azo dye as a charge control agent, and magnetite as magnetic powder (average particle size) Diameter 0.3μ
m) 70 parts of magnetic toner A was obtained.

The toner is produced by kneading the above toner components with an extrusion kneader, cooling and then pulverizing and classifying to obtain an average particle size of about 11 μm.
Magnetic toner A of No.

Next, as an additive fine powder to the magnetic toner A, titanium black 12S (TiO-TiN, composition ratio 0.9: 0.1; average particle diameter about 0.05 μm)
m, electric resistance (10 Ωcm) 0.3 wt% is externally added,
Toner samples were prepared.

This toner sample was subjected to a continuous copying test using a plain paper copying machine using Se (selenium) as a photoconductor.

As a result, there was almost no change in the image even after the actual shooting of about 20,000 images.

Further, as shown in Table 1, the variations in the charge amount, the image density and the fog at this time were small.

Further, the photoconductor after the actual copying was observed, but no film of toner was found on the surface.

Comparative Example 1 A toner sample was prepared in the same manner as in Example 1 except that the magnetic toner A prepared in Example 1 was used and 0.3% by weight of carbon black was externally added instead of titanium black 12S as an additive fine powder. Then, a continuous copy test was performed.

As a result, as the number of copies increases, the contamination of the optical system and other parts inside the device due to toner scattering progresses, and
With 10,000 sheets, the fog caused by them increased remarkably and became almost unusable.

The changes in the charge amount, image density and fog at this time were unstable as shown in Table 2.

Further, when the surface of the photoconductor at that time was observed, the toner was found to be attached in a film shape.

Example 2 As a resin, 100 parts of a styrene-butyl acrylate resin having a weight average molecular weight of about 70,000, 1 part of carbon black as a colorant, 3 parts of a Cr-containing complex salt azo dye as a charge control agent, and magnetite as magnetic powder (average particle size) System 0.3μ
m) 70 parts, 2 titanium powder 12S as additive fine powder
Using 0 parts, these were uniformly mixed, kneaded by an extrusion kneader, cooled, pulverized and classified to prepare a toner sample having an average particle diameter of about 13 μm.

Using this toner sample, a continuous copying test was conducted in the same manner as in Example 1 to evaluate its performance.

As a result, good results almost similar to those of Example 1 were obtained even after about 20,000 sheets.

Table 3 shows changes in the charge amount, image density and fog at this time.

Example 3 As a resin, styrene having a weight average molecular weight of about 100,000 was used.
Toner B was obtained by using 100 parts of butyl methacrylate resin, 5 parts of carbon black as a colorant, and 3 parts of nigrosine dye as a charge control agent.

The toner was prepared in exactly the same manner as in Example 1. The average grain size of Toner B was about 13 μm.

Next, 0.1% by weight of titanium black 12S as an additive fine powder was externally added to Toner B to prepare a toner sample.

A developer was prepared by mixing 5 parts of this toner sample with 100 parts of an iron powder carrier having an average particle size of about 100 μm.

Furthermore, a continuous copying test was conducted on this developer using a plain paper copying machine using OPC (organic photoconductor) as a photoconductor.

As a result, there was almost no change in the image quality from the beginning to about 40,000 sheets, and the fluctuations in the charge amount, image density and fog at this time were extremely small as shown in Table 4.

On the other hand, no toner film was found on the surface of the photoreceptor even after 40,000 sheets, and the formation of the toner film on the surface of the carrier was very slight, which was not a problem in practical use.

Comparative Example 2 Using the toner B prepared in Example 3, as the additive fine powder, SiO ₂ fine powder R-9 was used instead of the titanium black 12S.
A toner sample was prepared in exactly the same manner as in Example 3 except that 0.1% by weight of 72 (manufactured by Nippon Aerosil Co., Ltd.) was externally added.
A continuous copy test was performed.

As a result, a good image was obtained from the initial stage up to about 10,000 sheets, but after that, the charge amount increased sharply, and the decrease in image density became noticeable. At about 20,000 sheets, a large decrease in image density was observed, and it was almost useless.

Table 5 shows changes in the charge amount, image density, and fog at this time.

(Effects of the Invention) As described above, the electrostatic charge developing toner of the present invention is
It has both the effect of keeping the charge amount of the developer stable and the effect of preventing the formation of a toner film on the surface of the photoreceptor. Therefore, if a developer is formed using the electrostatic charge developing toner of the present invention, a so-called long-life developer with little change in physical properties and image quality over a long period of time can be obtained.

Claims (5)

(57) [Claims] 1. A resin, a colorant, and mTiOx-nTiN (m is 0.95 to 0.70, n is an arbitrary value in the range of 0.05 to 0.30, where m + n = 1 and x is 1.00 to 1.50). The toner for electrostatic charge development is characterized by comprising an additive fine powder which is a solid solution of a nonstoichiometric compound of titanium oxide and titanium nitride. 2. The electrostatic charge developing toner according to claim 1, wherein the additive fine powder represented by the general formula has an average particle diameter of 3 μm or less. 3. The toner for electrostatic charge development according to claim 1, wherein the additive fine powder represented by the general formula has an electric resistance of 10 ⁶ Ωcm or less. 4. The electrostatic charge developing according to claim 1, wherein the additive fine powder represented by the general formula is added to the outside of the toner in an amount of 0.01 to 2% by weight. toner. 5. A toner for electrostatic charge development according to claim 1, wherein the additive fine powder represented by the general formula is contained in the toner in an amount of 3 to 30% by weight. .