JP2813779B2 - Electrostatic image developing toner and image forming method using the same - Google Patents

Description

The present invention relates to a dry toner for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing, and the like, 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]

As a means for developing an electrostatic image formed on an electrophotographic photosensitive member or an electrostatic recording member, a method using a liquid developer (wet development method) and a method in which a colorant is dispersed in a binder resin are used. A method using a one-component or two-component dry developer in which a toner or a toner is mixed with a solid carrier (dry development method) is generally adopted. Each of these methods has advantages and disadvantages, but at present, dry development is often used.

By the way, in the above-mentioned toner (developing powder), a desired chargeability cannot be obtained simply by dispersing a colorant such as a dye or a pigment in a binder resin. Therefore, an appropriate amount of a charge control agent is added thereto. It is usually done. Typical examples of conventional charge control agents include (i) those that give a positive charge to the toner, such as nigrosine-based oil-soluble dyes, quaternary ammonium salts, azine-based dyes having an alkyl group, and basic dyes. Lakes of basic dyes and the like that (ii) impart a negative charge to the toner include, for example, chromium-containing monoazo complexes, chromium-containing salicylic acid compound complexes, and chromium-containing organic dyes (copper phthalocyanine green, chloromonoazo dyes). Metal dyes. However, toners containing such conventional charge control agents show good development characteristics at the beginning but have a short life,
Therefore, inconvenient phenomena such as filming of the photoreceptor when used for a long time are often recognized. This is because the properties of the conventional charge control agent are not constant and lack stability. In addition, many of these conventional charge control agents tend to disperse during heat kneading in toner production, or to be easily decomposed or deteriorated due to mechanical impulses, friction, and changes in temperature and humidity conditions. Phenomena that are becoming stronger. There is also a tendency that many of the conventional charge control agents change depending on the environment. In particular, in a one-component process having at least a toner conveying member and a toner layer thickness regulating member, and forming and developing a thin toner layer on the toner conveying member, fluctuations in the toner charging property greatly affect the formability of the thin toner layer. Influence,
May cause image degradation. In any case, most of the charge control agents that have been proposed so far cannot have an appropriate chargeability over a long period of time.

[Problems to be solved by the invention]

Therefore, the present invention overcomes the above-mentioned disadvantages of the prior art, and stable frictional charging occurs between toner particles or between a toner and a charging member such as a developing sleeve or a blade in a one-component developing method, and A first object is to provide a toner having a triboelectric charge distribution that is sharp and uniform, and can be controlled to a charge amount suitable for a developing method to be used. It is a second object of the present invention to provide a toner in a one-component type dry developing material whose charge is controlled. Further, the present invention has a third object to provide a toner having not only a stable image but also a durable one. Further, the present invention is free from contamination and toner scattering and has an initial image even in continuous use. A fourth object of the present invention is to provide a toner from which a number of equivalent high-quality images can be obtained.

[Means for solving the problem]

The present inventors have conducted intensive studies, and as a result, 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.

That is, 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 (I) or (II) as a negative charge control agent. An image developing toner is provided.

In addition, there is provided an image forming method in which a toner is used in an image forming method based on a one-component developing method in electrophotography in which a thinned toner is supplied to a latent image carrier to develop a latent image. You.

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 known means. The negative charge control agent may be used alone,
Two types may be used in combination. Further, another negative charge control agent can be used in combination.

The toner of the present invention contains 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 type of the binder resin, the presence or absence of additives used as necessary, and the toner manufacturing method including the dispersion method, and is uniquely limited. Although not to be usually, usually 0.1 to 20 parts by weight to 100 parts by weight of the binder resin,
Preferably it is in the range of 0.2 to 10 parts by weight. When the amount is less than 0.1 part by weight, the negative chargeability of the toner is insufficient and is not practical.On the other hand, when the amount exceeds 20 parts by weight, the negative chargeability of the toner becomes too large, and the fluidity, transferability and image density are reduced. It is not preferable because it causes a decrease and the like.

As the colorant used in the present invention, all pigments and dyes conventionally used as toner colorants are applied. Specifically, carbon black, lamp black, pig black, ultramarine, 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, chrome yellow, quinacridone, benzidine yellow, malachite green, malachite green hexalate, oil black, azo oil black , Rose bengal, monoazo dyes, disazo dyes, trisazo dyes and mixtures thereof.

Further, as the binder resin used in the present invention, all of those which have been used as the binder resin for the toner are applied similarly to the colorant. Specifically, a homopolymer of styrene such as polystyrene, poly p-chlorostyrene, and polyvinyl toluene and a substituted product thereof: styrene-p-
Chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-acryl Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate Copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer Coalescence, styrene-acryloni Styrene-based copolymers such as ril-indene copolymer, styrene-maleic acid copolymer and styrene-maleic acid ester copolymer: polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene ,
Polyester, polyurethane, 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 And the like, and these may be used alone or as a mixture of two or more.

The toner of the present invention may optionally contain additives. Examples of the additive include a lubricant such as tetrafluoroethylene resin, zinc stearate or an abrasive such as cerium oxide or silicon carbide, or a fluidizing agent such as colloidal silica or aluminum oxide, a caking inhibitor, or a carbonaceous additive. Examples include a conductivity-imparting agent such as black and tin oxide, and a fixing aid such as low-molecular-weight polyethylene.

The toner of the present invention is particularly useful for forming an image by one-component development in electrophotography. Next, the image forming method of the present invention will be described.

The image forming method according to the present invention includes an image forming method according to a one-component developing method in electrophotography in which a thinned toner is supplied to a latent image carrier to develop a latent image, wherein the negative charge control agent is included. It is characterized by using toner.
To reduce the thickness of the toner, a toner conveying member, a toner layer thickness regulating member and a toner replenishing auxiliary member are usually provided, and the replenishing auxiliary member and the toner conveying member, and the toner layer thickness regulating member and the toner conveying member respectively correspond. This is performed using the device in contact.

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

The drawing is a schematic sectional view of an example of a developing device using a non-magnetic one-component toner useful for carrying out the method of the present invention. In the drawing, toner 6 of the present invention contained in a toner tank 7 is forcibly brought to a sponge roller (toner replenishing auxiliary member) 4 by a stirring blade (toner replenishing auxiliary member) 5, and toner is transferred to the sponge roller 4. Supplied. When the sponge roller 4 rotates in the direction of the arrow, the toner taken in by the sponge roller 4 is conveyed to the toner conveying member 2 and is rubbed and electrostatically or physically attracted. It rotates strongly in the direction of the arrow, and a uniform thin toner layer is formed by a steel elastic blade (toner thickness regulating member) 3 and is triboelectrically charged. Thereafter, the latent image is transported to the surface of the electrostatic latent image carrier 1 which is in contact with or in proximity to the toner conveying member 2, and the latent image is developed. After charging the organic photoreceptor with 800V minus DC, the electrostatic latent image
It is exposed, forms a latent image and is developed.

In such an image forming method using a one-component developing method in electrophotography, fluctuations in the chargeability of the toner greatly affect the formability of a thin layer of the toner. It shows excellent properties and is also excellent in environmental stability, so that it can be controlled to an appropriate charge amount at the time of implementation.
High quality images can be obtained.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to examples. Parts represent parts by weight.

Example 1 100 parts of styrene-n-butyl methacrylate copolymer 10 parts of carbon black 3 parts of the compound represented by the structural formula (I) 3 parts of the mixture having the above composition was sufficiently stirred and mixed in a Henschel mixer, and then 130 to 140 ° C. in a roll mill. The mixture was heated and melted at a temperature of about 30 minutes and cooled to room temperature. The obtained kneaded material was pulverized and classified to obtain a toner having a particle size of 5 to 10 μm. 0.2 part of colloidal silica was added to and mixed with 100 parts of the toner to obtain the toner of the present invention.

Using the obtained toner, an image was formed with a developing device as shown in the drawing, and a good image was obtained.
The image did not change after running 10,000 copies.

Also, when the charge amount of the toner was measured by a toner suction method from a developing roller, the initial charge amount was −12.9 μC / g, and the charge amount of the toner after running 10,000 sheets was −
It was 12.7 μC / g, which was almost the same as the initial value.

Furthermore, under high humidity environment of 35 ℃, 90% RH and 10 ℃, 15%
Even in a low humidity environment of RH, an image equivalent to that obtained by copying under a normal humidity environment was obtained, and toner filming on the photoconductor was not recognized.

Example 2 A toner of the present invention was obtained in the same manner as in Example 1 except that the compound represented by Structural Formula (II) was used instead of the compound represented by Structural Formula (I) in Example 1.

An image was formed using the obtained toner in the same manner as in Example 1. As a result, a good image was obtained, and the image did not change even after running 10,000 sheets.

When the charge amount of the toner was measured by a toner suction method from a developing roller, the initial charge amount was -13.0 μC / g, and the toner charge amount after running 10,000 sheets was −
It was 12.6 μC / g, which was almost the same as the initial value.

Furthermore, under high humidity environment of 35 ℃, 90% RH and 10 ℃, 15% RH
Even in such a low humidity environment, an image equivalent to a copy in a normal humidity environment was obtained, and toner filming on the photoreceptor was not recognized.

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.

Using the obtained toner, an image test was performed in the same manner as in Example 1. As a result, a clear image without fog was obtained at the initial stage, but an unclear image with fog was formed from about 5,000 sheets. Filming of the toner was observed on the body surface. Further, under high temperature and high humidity, 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 -10.0 μC / g, which was sufficient, but decreased to −3.9 μC / gb after running 5,000 sheets.

〔The invention's effect〕

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

Further, the toner does not change in various properties such as triboelectric charging property even when the environment such as mechanical shock and friction and temperature and humidity conditions change.

Therefore, according to the image forming method of the present invention, it is possible to obtain a high-quality image equivalent to the initial image even after continuous copying without causing background dirt or toner scattering.

Further, in the method, even under various environments,
A stable high-quality image is obtained, and filming does not occur on the photoreceptor even when used for a long time.

[Brief description of the drawings]

The drawing is a schematic cross-sectional view showing one example of a developing device using the non-magnetic one-component toner of the present invention useful for carrying out the method of the present invention. 1 .... Electrostatic latent image carrier, 2 .... Toner conveying member, 3 ....
Elastic blade, 4 sponge roller, 5 stirring blade, 6 toner, 7 toner tank.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tomoge Hagiwara 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-2-221966 (JP, A) ( 58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 9/097 G03G 15/08 507

Claims (2)

(57) [Claims] 1. A toner for developing an electrostatic image, wherein a toner comprising at least a binder resin and a coloring agent contains a zinc compound represented by the following structural formula (I) or (II) as a negative charge control agent. toner. 2. An image forming method using a one-component developing method in electrophotography in which a thinned toner is supplied to a latent image carrier to develop a latent image, wherein the toner according to claim 1 is used. Characteristic image forming method.