JPH02284160A - Electrostatic charge image developing toner and image forming method using the same - Google Patents

Abstract

PURPOSE:To ensure stable triboelectrification between a negative charge control ler and a charge imparting member and a sharp and a uniform distribution of triboelectrification amount by incorporating a specified zinc compound as the negative charge controller. CONSTITUTION:The toner contains as the negative charge controller the zinc compound represented by formula I or II, and this is synthesized by the known methods, and may be used alone or in a combination. This toner is composed essentially of a binder resin, a colorant, and the negative charge controller and the content of the controller depends on the manufacturing method of the toner, such as the kind of the binder resin, the presence or absence of additives to be added when needed, and a dispersion process, thus permitting the triboelectrification with the charge imparting member to be kept stable and negative in polarity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dry toner for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc., and an image forming method using the same. More specifically, the present invention relates to an electrostatic image developing toner containing a specific compound as a negative charge control agent and an image forming method using the same.

[Conventional technology]

There are two methods for developing electrostatic images formed on electrophotographic photoreceptors and electrostatic recording materials: a method using a liquid developer (wet development method), and a method using a colorant dispersed in a binder resin. A method (dry development method) using a toner or a one-component type or two-component type dry developer in which the toner is mixed with a solid carrier is generally adopted. Although each of these methods has its own advantages and disadvantages, the dry developing method is currently widely used.

By the way, in the above-mentioned toner (developer powder), desired charging properties cannot be obtained if colorants such as dyes and pigments are simply dispersed in a binder resin, so an appropriate amount of a charge control agent is added to the toner (developer powder). It is normal that this is done. Typical examples of conventional charge control agents include (i) agents that impart a positive charge to toner, such as nigrosine-based oil-soluble dyes;
Quaternary ammonium salts, azine dyes with alkyl groups, basic dyes, basic dye lakes, etc.

(ii) As a substance that imparts a negative charge to the toner, for example, a chromium-containing monoazo complex, a chromium-containing salicylic acid compound complex,
Examples include metal-containing dyes such as chromium-containing organic dyes (copper butalocyanine green, chloromonoazo dyes). However, although toners containing conventional charge control agents exhibit good development characteristics initially, they have a short lifespan, and therefore, when used for long periods of time, they often cause inconvenient phenomena such as filming on the photoreceptor. It recognized. This is due to the fact that the properties of conventional charge control agents are inconsistent and lack stability. In addition, many of these conventional charge control agents are easily dispersed during thermal kneading during toner production, or decomposed or deteriorated due to mechanical impulses, friction, changes in temperature and humidity conditions, etc. This is making the phenomenon of decline even stronger. Furthermore, there is a tendency that many of the conventional charge control agents change depending on the environment. In particular, in a one-component process that includes at least a toner transport member and a toner layer thickness regulating member and develops by forming a thin toner layer on the toner transport member, fluctuations in toner chargeability have a large effect on the ability to form a thin toner layer. may cause image deterioration. In any case, most of the charge control agents that have been proposed so far cannot maintain appropriate chargeability over a long period of time.

[Problem to be solved by the invention]

Therefore, the present invention overcomes the drawbacks of the above-mentioned prior art, and provides stable frictional charging that occurs between toner particles or between a toner and a charge-imparting member such as a developing sleeve or blade in a component-based development system. Our first objective is to provide a toner that has a sharp and uniform triboelectric charge distribution and can be controlled to a charge amount suitable for the developing method used.
A second object of the present invention is to provide a toner in a one-component type dry developing material that is negatively charged over a long period of time without becoming excessively triboelectrically charged.

Furthermore, the third objective of the present invention is to provide a toner that not only always provides stable images but also has durability, is free from stains and toner scattering, and maintains the same initial image quality even during continuous use. A fourth object is to provide a toner that allows a large number of equally high-quality images to be obtained.

[Means to solve the problem]

As a result of extensive research, the present inventors have found that a toner containing a specific zinc compound as a negative charge control agent is suitable for the above purpose, and have completed the present invention.

Namely, according to the present invention, a toner comprising at least a binder resin and a colorant contains a zinc compound represented by the following structural formula (1) or (II) as a negative charge control agent. An image developing toner is provided.

Further, there is provided an image forming method using the toner described above, in an image forming method using a one-component development method in electrophotography, in which a thin layer of toner is supplied to a latent image carrier to develop a latent image. Ru.

In the toner of the present invention, the zinc compound represented by the above structural formula used as a negative charge control agent is synthesized by a known method. The negative charge control agent may be used alone, or two
Seeds may also be used. Moreover, other negative charge control agents can also be used together.

The toner of the present invention includes a binder resin, a colorant, and the negative charge control agent as essential components. The content of the negative charge control agent in the toner is determined by the toner manufacturing method, including the type of binder resin, the presence or absence of additives used as necessary, and the dispersion method. Although not necessarily limited, it is usually in the range of 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the binder resin. 0
．． If it is less than 1 part by weight, the negative chargeability of the toner will be insufficient, making it impractical; if it exceeds 20 parts by weight, the negative chargeability of the toner will become too large, resulting in decreased fluidity, decreased transferability, and decreased image density. This is undesirable as it causes deterioration of the temperature.

As the colorant used in the present invention, all pigments and dyes conventionally used as colorants for toners can be used. Specifically, carbon black, lamp black, iron black, ultramarine blue, nigrosine dye, aniline blue, calco oil blue DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, phthalocyanine green, hand yellow G, rhodamine 6C lake, chromium. Yellow, quinacridone, benzidine yellow, malachite green, malachite green hexalate, oil black, azo oil black, rose bengal, monoazo dyes and pigments, disazo dyes and pigments, trisazo dyes and pigments, and mixtures thereof.

Further, as for the binder resin used in the present invention, all the binder resins that have been used hitherto as binder resins for toners can be used, similarly to the colorant described above. Specifically, polystyrene,
Monopolymers of styrene and its substituted products such as poly-P-chlorostyrene and polyvinyltoluene: styrene-p-chlorostyrene copolymers, styrene-propylene copolymers,
Styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer.

Styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, Styrenic copolymers such as styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, and styrene-maleic acid ester copolymer: polymethyl methacrylate ,
Polybutyl methacrylate.

Polyvinyl chloride, polyvinyl acetate, polyethylene.

Polypropylene, polyester, polyurethane.

Examples include polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. These may be used alone or in combination of two or more.

Note that additives may be mixed with the toner of the present invention as necessary. Examples of additives include lubricants such as tetrafluoroethylene resin and zinc stearate, abrasives such as cerium oxide and silicon carbide, fluidizing agents such as colloidal silica and aluminum oxide, anti-caking agents, and carbon. Examples include conductivity imparting agents such as black, tin oxide, and fixing aids such as low molecular weight polyethylene.

The toner of the present invention is particularly useful for image formation using a one-component development method in electrophotography, and the image forming method of the present invention will be described next.

The image forming method of the present invention is an image forming method using a one-component development method in electrophotography in which a thin layer of toner is supplied to a latent image carrier to develop a latent image, and the image forming method contains the above-described negative charge control agent. It is characterized by using toner. Note that toner thinning is usually achieved by providing a toner conveying member, a toner layer thickness regulating member, and a toner replenishment auxiliary member, and the replenishing auxiliary member and toner transporting member, and the toner layer thickness regulating member and toner transporting member, respectively. It is carried out using equipment that is in contact with the

The image forming method of the present invention will be explained in more detail with reference to the drawings.

The drawing is a schematic cross-sectional view of an example of a developing device using a non-magnetic-component toner useful in carrying out the method of the present invention. In the drawing, the toner 6 of the present invention contained in a toner tank 7 is forcibly brought to a sponge roller (toner replenishment auxiliary member) 4 by a stirring blade (toner replenishment auxiliary member) 5; Supplied. Then, as the sponge roller 4 rotates in the direction of the arrow, the toner taken into the sponge roller 4 is carried to the toner conveying member 2, where it is rubbed, electrostatically or physically attracted, and the toner conveying member 2 It rotates strongly in the direction of the arrow, and a uniform thin layer of toner is formed by the steel elastic blade (toner thickness regulating member) 3 and is charged by friction. Thereafter, the toner is transported to the surface of the electrostatic latent image carrier 1 that is in contact with or in close proximity to the toner transport member 2, and the latent image is developed. The electrostatic latent image is created by charging the organic photoreceptor with a negative DC charge of 800 V, and then exposing it to light to form a latent image, which is then developed.

In such an image forming method using a one-component development method in electrophotography, fluctuations in the chargeability of the toner greatly affect the ability to form a thin layer of the toner. ? Since it exhibits IF conductivity and has excellent environmental stability, it is possible to control the amount of charge to an appropriate level during implementation.

The method of the invention provides high quality images over a long period of time.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that 1 part represents part by weight6 Example 1 Carbon black 10 parts Compound represented by structural formula (I) 3 parts The mixture having the above composition was thoroughly stirred and mixed in a Henschel mixer, and then heated in a roll mill at 130 to 140°C. The mixture was melted by heating at a temperature of about 30 minutes, and then cooled to room temperature. The obtained mixed material was pulverized and classified to obtain toner having a particle size of 5 to 104. 0.2 parts of colloidal silica was added to 100 parts of this toner and mixed to obtain the toner of the present invention.

When the obtained toner was used to form an image using a developing device as shown in the drawing, a good image was obtained, and the image did not change even after running 10,000 copies.

In addition, when the toner charge amount was measured by the toner suction method from the developing roller, the initial charge amount was -12.9μC/
The charge amount of the toner after running 10,000 sheets was -12.7 μC/g, which was almost unchanged from the initial value.

Furthermore, under a high humidity environment of 35℃ and 90% RH, and at 10℃
Even in a low humidity environment of 15% RH, an image equivalent to that obtained in a normal temperature environment was obtained, and no toner filming on the photoreceptor was observed.

Example 2 Except for using the compound represented by structural formula (n) instead of the compound represented by structural formula (1) in Example 1,
A toner of the present invention was obtained in the same manner as in Example 1.

When an image was produced using the obtained toner in the same manner as in Example 1, a good image was obtained, and the image did not change even after running 10,000 copies.

In addition, when the amount of charge on the toner was measured using the toner suction method from the developing roller, the initial amount of charge was -13.0μC/
The charge amount of the toner after running 10,000 sheets was -12.6 μC/g, which was almost the same as the initial value.

Furthermore, under a high humidity environment of 35°C and 90% RH, and at 10°C,
Even in a low humidity environment of 15% RH, an image equivalent to that obtained in a normal humidity environment was obtained, and no toner filming on the photoreceptor was observed.

Comparative Example A comparative toner was obtained in the same manner as in Example 1, except that copper phthalocyanine green was used instead of the compound represented by the structural formula (1) in Example 1.

When an image test was conducted using the obtained toner in the same manner as in Example 1, a clear image with no fog was obtained at the beginning, but after about 5,000 copies, the image became unclear with fog, and the photosensitive Toner filming was observed on the body surface. Furthermore, under high temperature and high humidity conditions, the image density was as low as 0.9. When the charge amount was measured in the same manner as in Example 1, the initial charge amount was -10.07zC/g, which was sufficient, but after running 5,000 sheets, it decreased to -3.9μC/g. .

〔Effect of the invention〕

The toner for developing an electrostatic image according to claim (1) contains the zinc compound represented by the structural formula (1) or (■) as a negative charge control agent, so that the toner and the developing sleeve or blade can be charged. Frictional charging with the member can be maintained at a stable negative polarity.

Further, the toner does not change its various performances such as triboelectric charging properties even if the environment such as mechanical impact, friction, temperature and humidity conditions, etc. change.

Therefore, with the image forming method of claim (2), it is possible to obtain a high-quality image equivalent to the initial image even after continuous copying without background smudge or toner scattering.

Moreover, in this method, stable high-quality images can be obtained even under various environments, and there is no filming on the photoreceptor even after long-term use.

[Brief explanation of drawings]

The drawing is a schematic sectional view showing an example of a developing device using the non-magnetic component toner of the present invention useful for carrying out the method of the present invention. l... Electrostatic latent image carrier, 2... Toner transport member, 3
... Elastic blade, 4... Sponge roller, 5.
... Stirring blade, 6... Toner, 7... Toner tank. Patent applicant Rico Co., Ltd.

Claims (2)

[Claims] (1) In a toner consisting of at least a binder resin and a colorant, the negative charge control agent may be of the following structural formula (I) or (II).
) A toner for developing an electrostatic image, characterized by containing a zinc compound represented by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (2) An image forming method using a one-component development method in electrophotography, in which a thin layer of toner is supplied to a latent image carrier to develop a latent image, characterized by using the toner according to claim (1). image forming method.