JPH03217855A - Toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To obtain the toner for developing electrostatic charge images which is less deteriorated in image quality by lapse of time and is less deteriorated by environment and has excellent electrostatic charge characteristics by making combination use of a nigrosine dye and an imidazole deriv. expressed by specific constitutional formula. CONSTITUTION:Various known nigrosine dyes are usable as the nigrosine dye. On the other hand, the imidazole deriv. is the compd. expressed by general formula I. In the formula, R<1>, R<2> and R<3> respectively denote a hydrogen atom, 1 to 20C alkyl group or aryl group. This toner exhibits particularly excellent properties as a positive charge control agent if the nigrosine dye and the imidazole deriv. are used in combination in such a manner.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a toner for developing electrostatic images used in fields such as electrophotography.

<Prior Art> Toner for developing electrostatic images used in electrophotographic methods such as electronic copying machines is once attached to an image carrier such as a photoreceptor on which an electrostatic image is formed during the development process. Then, in the transfer process, it is transferred from the photoreceptor to the transfer paper, and then in the fixing process, it is fixed on the copy paper surface. At this time, the toner-containing developer is a two-component developer consisting of carrier and toner. A one-component developer (magnetic toner) that does not require a developer or a carrier is known.

Chargeability agents such as nigrosine dyes, quaternary ammonium salts, and triphenylmethane dyes, carrier coating agents, and the like have been known for imparting chargeability to developers.

Problems to be Solved by the Invention> However, these conventional charging agents do not necessarily have a satisfactory charging effect. It is difficult to obtain toner that exhibits a favorable change over time, and problems have arisen in that image stains such as fog occur under high temperature and high humidity conditions or during continuous copying, or that stable copy density cannot be obtained. .

As a result of intensive studies to solve these problems, the present inventors have found that by using a nigrosine dye and an imidazole derivative represented by a specific structural formula in combination, the present inventors can achieve preferable charging properties.
In particular, it has been discovered that a toner exhibiting preferable chargeability as a positively chargeable toner and having excellent image quality can be obtained, and has arrived at the present invention.

That is, an object of the present invention is to provide a toner for developing electrostatic images with excellent charging characteristics and less deterioration of image quality over time and environment.

Means for Solving the Problems> Accordingly, the object of the present invention is to provide a static dye characterized by containing at least a resin, a colorant, a nigrosine dye, and an imidazole derivative represented by the following general formula (I). This can be easily achieved using a toner for developing charged images.

Ra (In the formula, R1, R2 and R3 each represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group.)
Effect> The present invention will be explained in detail below.

Various known nigrosine dyes can be used as the nigrosine dye used in the present invention, such as Orient Chemical Co., Ltd., Bontron N series, Orient Spirit Buranok AB, Orient Spiritotoburanok SB, Solvent Black # 5. Solvent Blasok #7, Spirit Blasok NO. manufactured by Sumitomo Chemical Co., Ltd. 850, Spinot Blasok No. 900 etc. are mentioned.

On the other hand, as the imidazole derivative, the above-mentioned general (I)
Compounds synthesized by various known methods represented by the following are typical examples:

In general formula (I), substituents Rl, R2, and R3 include a hydrogen atom; a branched group such as a methyl group, an ethyl group, a probyl group, a hexyl group, a nonyl group, an undecyl group, a dodecyl group, a hebutadecynole group, etc. Good alkyl groups include aryl groups such as phenyl, naphthyl, anthryl, phenanthryl, and birenyl.

When the above-mentioned nigrosine dye and imidazole derivative are used in combination, they exhibit particularly excellent properties as a positive charge control agent, but whether the chargeability is positive or negative depends on the chargeability of other charge control agents and the frictional charging partner. Therefore, the present invention is not limited only to positively chargeable toner.

As the resin component that can be used in the present invention, various known resin components suitable for toners for developing electrostatic images can be used. For example, styrene resin, styrene acrylic copolymer resin,
There are polyester resins, epoxy resins, mixed resins thereof, and resins having amine groups in their alkyl side chains, among which styrene resins or styrene/acrylic copolymer resins are preferred.

The content of the compound represented by general formula (I) in the toner is:
It is preferable that the amount is 0.01 to 5 parts by weight and the nigrosine dyeing is 0.01 to 5 parts by weight, and the total of both is 6 parts or less, based on 100 parts by weight of the resin.

The colorant used in the present invention is not particularly limited as long as it has been conventionally used in toners, and carbon black or the like may be used. The content of colorant is
The amount is preferably 3 to 20 parts by weight per 100 parts by weight of the resin.

Furthermore, in addition to the nigrosine dye and the imidazole derivative, the toner of the present invention may contain other charging agents, including known ones, such as quaternary ammonium salts, triphenine methane dyes, polyamine resins, etc. may be contained.

In addition, additives such as a low molecular weight olefin polymer and finely powdered silica may be added internally or externally to the toner of the present invention in order to improve fixing properties and fluidity.

Furthermore, in some cases, bases such as titanium oxide fine particles or hydrotacites whose surface is coated with a tin oxide and antimony monoxide mixture are used to prevent toner scattering and fogging, or to improve image density uniformity. Magnesium and aluminum. Hydroxy carbonate hydrate (MgpAl, (OH) r(CO3) s-mH
20 (in the formula, p+ q+ r+ and S are 2p+3q=
It represents an integer that satisfies r+2s, and m represents any integer. )) Powder or magnetic powder such as magnetite may be added.

The toner can be produced by kneading the above-mentioned components in a seconder or the like, cooling, pulverizing and classifying.

In addition to the two-component developer, the toner of the present invention is also applicable to one-component developers (magnetic toner and non-magnetic toner) such as encapsulated toner, polymerized toner, and toner containing magnetic powder such as magnetite. be able to.

The average particle size of the toner is 5 to 20 I. lm is preferred.

The carrier to be mixed with the toner of the present invention to form a developer is not particularly limited, but may be 10 to 200 liters. Iron powder, ferrite, and magnetite carriers having an average particle size of Im can be used.

Furthermore, coated carriers coated with fluorine resin or the like can also be used as these carriers for the purpose of improving durability during continuous use and adjusting carrier resistance. In addition, resin canoa in which magnetic powder is kneaded into resin can also be used. It is preferable to use 5 to 100 parts by weight of these carriers per 1 part by weight of the toner.

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. In addition, only 1 part in the following examples.
All references to "parts by weight" are taken to mean "parts by weight."

(Example 1) - 100 parts of styrene resin SBM-600 (manufactured by Sanyo Chemical Co., Ltd.) - Carpon Black #40 (manufactured by Mitsubishi Chemical Co., Ltd.)
Co., Ltd.) 5 parts Nigrosine dye n-04 (
Orient Chemical Co., Ltd.) 2 parts imidazole derivative (
Compound-1) was blended, kneaded, pulverized, and classified to obtain an average particle size of 10μ. A black toner was obtained. 4 parts of the obtained toner and an average particle size of about 1
A developer was prepared by mixing with 100 parts of ferrite carrier coated with 00 pm silicone resin and stirring.

Next, this developer was processed at 30 to 35°C, 780 to 85% RH, using a copying machine using an organic photoconductor as a photoreceptor.
A 50,000-shot photo test was conducted under high temperature/high humidity environmental conditions.

Furthermore, the replenishment toner used in the actual photography test had the same composition as the toner used in the developer described above.

As a result of the live-action test, even after 50,000 sheets were printed, there was no increase in fog, which is dirt on the white background of copies, and the black background was uniform and had a high density, making it highly durable even in harsh environments of high temperature and humidity. The toner and developer were

(Examples 2 to 6) The same procedure as in Example 1 was carried out except that the nigrosine dye and imidazole derivative used, as well as their types and amounts used were as shown in the table below. A developer with no decrease in density can be obtained (
Example 7) Polyester resin HP − instead of styrene resin
Example 1 was carried out in exactly the same manner as in Example 1 except that 313 (manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.) was used, and a developer was obtained that did not cause fogging or decrease in image density even after a 50,000-sheet photographic test.

(Comparative Example-1) Exactly the same composition as in Example 1 except that the nigrosine dye N-04 used in Example-1 was not used.
As a result of conducting a live-action test on 00 sheets, there were problems in use, such as increased fogging.

(Comparative Example-2) The imidazole derivative (compound-
A photographic test was conducted on 50,000 sheets using the same composition as in Example 1, except that 1) was not used, and as a result, there were problems in use such as increased fog.

Effects of the Invention The toner for developing electrostatic images of the present invention has good charging properties, such as always showing moderate and stable charging properties, and can be used under high temperature and high humidity conditions or during continuous copying, which has been a problem in the past. It provides good images regardless of the conditions of use, such as less copying stains and less loss of density, and provides numerous industrial benefits.

Claims (1)

[Claims] (1) A toner for developing electrostatic images characterized by containing at least a resin, a colorant, a nigrosine dye, and an imidazole derivative represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, R^1, R^2 and R^3 each represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group.)