JPH0784409A - Dry developer - Google Patents

Abstract

PURPOSE:To enable a dry developer to provide a stable electrostatic property for a long period of time and a good picture quality. CONSTITUTION:In the dry developer containing the toner containing the colorant consisting of a chromatic dye or pigment, a binder resin and an antistatic agent, and a coated carrier, the binder resin is the polyester resin having 90-110 deg.C softening point, the antistatic agent is the magnetic salt of benzilic acid deriv. expressed by the formula (In the formula, M is lithium, sodium or potassium.), moreover, a coating material is the silicone resin or acrylic resin dispersing conductive powder.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a dry developer, and more particularly to a dry developer useful for electrophotography, electrostatic recording, electrostatic printing and the like.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
An electrophotographic process involves uniformly charging a photoconductive insulating layer, then exposing the layer to dissipate the charge on the exposed areas to form an electrostatic latent image, which is then further exposed. The image is visualized by adhering a finely charged powder, called toner, on the image (developing process), and the resulting visible image is transferred to a transfer material such as transfer paper (transfer process), and then heated. There is known one in which permanent fixing is carried out by pressure or other suitable fixing method (fixing step) (US Pat. Nos. 2,221,776 and 2297).
691 and 2357809).

The developing method applied to the electrophotographic process is roughly classified into a dry developing method and a wet developing method. The former includes a method using a one-component developer and a method using a two-component developer. Furthermore, depending on the type of toner transport system, a magnetic brush development method that uses magnetic powder as a carrier by using magnetic force, a cascade development method that uses a somewhat rough bead carrier, and a glass fiber method can be used for a two-component developer. There is a fur brush developing method to be used.

As the toner applied to these developing methods, fine powder in which a coloring agent such as a dye or a pigment is dispersed in a natural or synthetic thermoplastic resin has been conventionally used.

In the case of a method using a two-component developer, the toner is usually mixed with carrier particles such as glass beads and iron powder, and at that time, the electrostatic latent image is held on the carrier by electrostatic attraction generated by friction. Is transported to the surface. The polarity of the toner chargeability is determined by the charge polarity of the electrostatic latent image, and positive or negative clear polarity and an appropriate charge amount are required. In order to make the toner retain a desired charge, the triboelectrification property of the carrier and the material of the surface thereof and the resin which is a component of the toner can be utilized. However, only this method can reduce the charge amount of the toner, and However, it is difficult to quickly reach the desired charge amount. In such a case, the image obtained by development is apt to cause background fog, and
It becomes unclear. Therefore, in order to impart a desired amount of charge to the toner quickly, a charge control agent for controlling the charging property is added.

On the other hand, as the color toner, those obtained by dispersing or dissolving various dyes and pigments in a binder resin are used. In the toner for reproducing a full-color image by using a color toner, especially three primary color toners, not only all of the basic performance including the charging property described above are good, but also in order to reproduce the color of the original image, It is important to reproduce black with extremely low saturation because the spectral reflection characteristics of each color are close to the ideal curve. Further, not only the spectral reflection characteristics but also the projection reproducibility of images and colors transferred and fixed on the transparency for an overhead projector (OHP), that is, the transparency and the spectral transmittance are required to be good.

However, when the above charge control agent is used, a change in hue and a decrease in saturation occur due to coloring of the charge control agent,
Further, since the dispersibility of the charge control agent in the binder resin is deteriorated, the transparency is lowered, and there is a problem that a clear full-color image cannot be obtained particularly when used for OHP.

Therefore, it has been desired to develop a dry developer which retains stable chargeability even after long-term storage, exhibits excellent maximum density and halftone reproducibility, and provides good transparency.

[0009]

DISCLOSURE OF THE INVENTION As a result of intensive studies made by the present inventors in view of such circumstances, the present invention contains a toner containing a specific binder resin and a charge control agent, and a carrier coated with a specific coating material. The present inventors have found that a dry developer has stable chargeability over time and provides excellent image quality, and completed the present invention.

That is, according to the present invention, in a dry developer containing a toner containing a coloring material composed of a chromatic dye or pigment, a binder resin and a charge control agent, and a coated carrier, the binder resin has a softening point of 90. It is a polyester-based resin of ~ 110 ° C, and the charge control agent is represented by the following general formula (1)

[0011]

[Chemical 2]

(Wherein M represents lithium, sodium or potassium), which is a metal salt of a benzylic acid derivative, and the coating material is a silicone resin or acrylic resin in which conductive powder is dispersed. It provides a dry developer.

In the present invention, the polyester resin contained in the toner as the binder resin is synthesized by a polycondensation reaction of a polyvalent carboxylic acid and a polyhydric alcohol. Examples of polycarboxylic acids include fumaric acid, maleic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, 3-isodecenyl-1,2,5,6-hexanetetracarboxylic acid, and succinic acid. , Carboxylic acids such as isooctyl succinic acid and adipic acid, carboxylic acid anhydrides, lower alkyl esters of carboxylic acids, and the like can be used. On the other hand, examples of the polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, neopentyl glycol, polyoxyeletin (2.2) -2,2'-bis (4-hydroxyphenyl). ) Propane, polyoxypropylene (2.2) -2,
2'-bis (4-hydroxyphenyl) propane, hydrogenated bisphenol A, glycerin, trimethylolpropane and the like are used. Furthermore, if necessary, monocarboxylic acids and monoalcohols can be added as polyester raw materials.

Ring-and-ball method of the above polyester resin (JIS
K-2207) softening point (SP) 90 ° C or higher 11
Must be below 0 ° C. When SP exceeds this, the molecular weight of the binder resin becomes too large, and the property of sharply dissolving due to the entanglement of polymer chains is impaired, resulting in lack of transparency and only an image with a dull color tone with low saturation can be obtained. . In particular, those having SP exceeding 130 ° C. are not preferable.
If the SP is less than 90 ° C., the molecular weight of the binder resin becomes too small and the glass transition point is lowered, so that blocking of the toner easily occurs and the storage stability deteriorates.

The benzylic acid derivative metal salt represented by the general formula (1), which is the charge control agent contained in the toner in the present invention, is preferably a sodium salt or a potassium salt,
Particularly, potassium salt is preferable.

As the colorant contained in the toner in the present invention, known chromatic dyes or pigments can be used. For example, for yellow, C.I. I. Solvent Yellow 21, C.I. I. Solvent Yellow 11
4, C.I. I. Solvent Yellow 77, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 1
4, C.I. I. Disperse Yellow 164 etc. I. Solvent Red 49, C.I. I. Sorbet Red 128, C.I. I. Pigment red
48.2, C.I. I. Disperse Red 11, etc., C.I. I. Solvent Blue 25, C.I. I. Solvent Blue 94, C.I. I. Pigment Blue 15
・ 3 etc.

The toner used in the present invention is prepared by mixing the above polyester resin with a charge control agent, a colorant, and if necessary, various additives such as wax, and dispersing them.
It is preferable that the particles are pulverized to about 30 μm.

As the carrier used in the present invention, known carriers can be used, and examples thereof include magnetic materials such as iron, ferrite, steel, magnetite and nickel.

The coating material used for coating the carrier in the present invention is a silicone resin or an acrylic resin.

When the coating material is a silicone-based resin, more preferably, after coating the carrier with a silicone varnish, 1
It is preferable to thermally cure at a temperature of 80 ° C. or higher. The silicone varnish is a straight silicone resin, for example, KR-114, KR-220, KR-2.
51, KR-255 (all manufactured by Shin-Etsu Silicone Co., Ltd.) and the like. Further, a silicone resin modified with a urethane resin, an epoxy resin, or the like can be used alone or as a mixture with the above straight silicone.

On the other hand, when the coating material is an acrylic resin, examples of the base monomer of the resin include methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate and butyl methacrylate. Further, a copolymer of the above acrylic monomer and a styrene monomer such as styrene, p-methylstyrene, or pt-butylstyrene can also be used.

As the conductive powder dispersed in the silicone resin or acrylic resin, carbon black, conductive tin oxide, conductive titanium oxide or the like can be used.

In the present invention, in order to coat the above-mentioned coating material on the carrier, for example, ferrite fluidized in a fluidized bed is sprayed with a silicone resin solution in which carbon black or the like is dispersed under heating, and then dried. Heat treatment may be performed accordingly.

The dry developer of the present invention can be produced by mixing the toner and the coated carrier by a kneader, a V-type blender or the like according to a conventional method.

[0025]

The dry developer of the present invention has a line image print density,
OHP with excellent surface print density and less fog
The image developed to transparency has good transparency, the light-transmitted image shows vivid coloration, and shows stable charging property for a long period against changes in temperature and humidity environment.

[0026]

EXAMPLES The present invention will be described below in greater detail by giving Examples, but the present invention is not limited thereto. In addition,
"Parts" shown below indicate "parts by weight".

Synthesis Example 1 Propylene glycol 149.1 parts, ethylene glycol 52.1 parts, and dimethyl terephthalate 410.2 were placed in a reaction vessel equipped with a stirrer, a reflux dehydration pipe for cooling and removing reaction product water, and a nitrogen blowing pipe. Parts, charged at 220 ° C. for demethanol condensation reaction, and at the end of the distillation of methanol, 55.3 parts of trimellitic anhydride were added and further reacted to obtain a softening point (SP) of 104.5 ° C., glass A polyester resin having a transition point (Tg) of 62.4 ° C. was obtained.

Synthesis Example 2 In the same reactor as in Synthesis Example 1, 350.0 parts of polyoxypropylene (2.2) -2,2 '-(4-hydroxyphenyl) propane, 116.0 parts of fumaric acid, Charge 0.2 parts of hydroquinone monomethyl ether, gradually raise the temperature, and perform a dehydration condensation reaction at 210 ° C to obtain a softening point of 101.6.
A polyester resin having a Tg of 61.5 ° C. was obtained.

Production Example 1 Ferrite (F-1530) 1, manufactured by Powder Tech Co., Ltd.
000 parts was fluidized in a fluidized bed and heated to 60 ° C., and carbon black (capsule equivalent) was added to 10 parts (resin content) of a silicone resin (KR-251, Shin-Etsu Silicone Co., Ltd.) dissolved in 5% with toluene. Black Co., MOGULL) 1
The liquid in which the parts were dispersed was sprayed, dried for another 20 minutes, and then heat-treated at 200 ° C. for 30 minutes in an electric furnace to obtain a silicone resin-coated carrier.

Production Example 2 Ferrite (F-1530) 1, manufactured by Powder Tech Co., Ltd.
000 parts was fluidized in a fluidized bed, 10 parts of a styrene-acrylic resin dissolved in 5% with toluene (resin content conversion) was sprayed onto the place heated to 60 ° C., and dried for 20 minutes to obtain acrylic. A resin-coated carrier was obtained.

Example 1 The following composition

[0032]

[Table 1] Polyester resin of Synthesis Example 1 100.0 parts C.I. I Pigment Yellow 14 5.0 parts Potassium salt of benzylic acid derivative 1.0 part Viscole 550P (manufactured by Sanyo Kasei Co., polypropylene wax) 2.0 parts

After mixing with a blender, the mixture was melt-kneaded with a twin-screw extrusion type kneader, coarsely pulverized with a cutter mill, and then pulverized and classified with an air jet mill to have an average particle size of 5 to 20 μm. Hydrophobic silica R97 is added to 100 parts of the fine particles.
2 parts (manufactured by Nippon Aerosil Co., Ltd.) were mixed to obtain a yellow toner. 40 parts of the yellow toner and 960 parts of the silicone-coated carrier of Production Example 1 were mixed with a V-type blender to obtain a developer. When the developing property of this developer was evaluated by a general-purpose copying machine equipped with a commercially available OPC, a high-concentration image having a charge amount of -16.5 μc / g in the initial stage and having no fog was obtained. Even after continuous copying of 10,000 sheets, the charge amount was -17.6 μc / g, and an image of good quality with no difference from the initial image was obtained. Further, the image copied on the OHP sheet had good transparency, and the image projected on the OHP had a good yellow color.

Comparative Example 1 The following composition

[0035]

[Table 2] Tuffton NE1110 (Kao Corporation, polyester resin
SP130 ° C) 100.0 parts Potassium salt of benzylic acid derivative 1.0 part C.I. I. Solvent Red 49 2.0 parts Viscole 550P (manufactured by Sanyo Kasei) 2.0 parts

Magenta toner (1) was manufactured in the same manner as in Example 1. Then the magenta toner 40.0
Parts and 960 parts of the silicone-coated carrier of Preparation Example 1 were mixed to prepare a developer.

Example 2 The following composition

[0038]

Table 3 Polyester resin of Synthesis Example 1 100.0 parts Potassium salt of benzylic acid derivative 1.0 part C.I. I. Solvent Red 49 2.0 parts Viscole 550P (manufactured by Sanyo Kasei) 2.0 parts

A magenta toner of No. 1 was manufactured in the same manner as in Example 1. Then the magenta toner 40.0
Parts and 960 parts of the silicone-coated carrier of Preparation Example 1 were mixed to prepare a developer.

Example 3 The following composition

[0041]

Table 4 Polyester resin of Synthesis Example 1 100.0 parts Potassium salt of benzylic acid derivative 1.0 part C.I. I. Pigment Blue 15.3 5.0 parts Viscor 550P (manufactured by Sanyo Kasei) 2.0 parts

The cyan toner of was produced in the same manner as in Example 1. Next, 40.0 parts of the cyan toner and 960 parts of the acrylic resin-coated carrier of Production Example 2 were mixed to produce a developer.

Example 4 The following composition

[0044]

[Table 5] Polyester resin of Synthesis Example 2 100.0 parts Potassium salt of benzylic acid derivative 1.0 part C.I. I. Solvent Yellow 162 2.0 parts Viscole 550P (manufactured by Sanyo Kasei Co.) 2.0 parts

The yellow toner of No. 1 was manufactured in the same manner as in Example 1. Next, 40.0 parts of the yellow toner and 960 parts of the acrylic-coated carrier of Production Example 2 were mixed to produce a developer.

Example 5 The following composition

[0047]

Table 6 Polyester resin of Synthesis Example 2 100.0 parts Potassium salt of benzylic acid derivative 1.0 part C.I. I. Pigment Red 13 5.0 parts Viscole 550P (manufactured by Sanyo Kasei) 2.0 parts

The magenta toner of was produced in the same manner as in Example 1. Then the magenta toner 40.0
Parts and 960 parts of the silicone-coated carrier of Preparation Example 1 were mixed to prepare a developer.

Example 6 The following composition

[0050]

Table 7: Polyester resin of Synthesis Example 2 100.0 parts Potassium salt of benzylic acid derivative 1.0 part C.I. I. Pigment Blue 15.3 5.0 parts Viscor 550P (manufactured by Sanyo Kasei) 2.0 parts

The cyan toner of was produced in the same manner as in Example 1. Next, 40.0 parts of the cyan toner and 960 parts of the silicone resin coated carrier of Production Example 1 were mixed to produce a developer.

Comparative Example 2 The following composition

[0053]

[Table 8] Polyester resin of Synthesis Example 2 100.0 parts Potassium salt of benzylic acid derivative 1.0 part C.I. I. Pigment Yellow 14 5.0 parts Viscor 550P (manufactured by Sanyo Kasei) 2.0 parts

The yellow toner of was produced in the same manner as in Example 1. Next, 40.0 parts of the yellow toner and an uncoated ferrite carrier (F-
1530) and 960 parts were mixed to produce a developer.

Comparative Example 3 The following composition

[0056]

[Table 9] Polyester resin of Synthesis Example 1 100.0 parts C.I. I. Pigment Red 13 5.0 parts Viscole 550P (manufactured by Sanyo Kasei) 2.0 parts

The magenta toner (1) was manufactured in the same manner as in Example 1. Then the magenta toner 40.0
Parts and 960 parts of the silicone-coated carrier of Preparation Example 1 were mixed to prepare a developer.

Comparative Example 4 The following composition

[0059]

[Table 10]

The cyan toner of was produced in the same manner as in Example 1. Next, 40.0 parts of the cyan toner and 960 parts of the acrylic resin-coated carrier of Production Example 2 were mixed to produce a developer.

The developing properties of the developers obtained in Examples 2 to 7 and Comparative Examples 1 to 4 were evaluated in the same manner as in Example 1. These results are shown in Table 11 together with the results of Example 1 above.

[0062]

[Table 11]

As is clear from the results shown in Table 11, the products of the present invention (Examples 1 to 7) were all comparative products (Comparative Example 1).
~ 4), both in the initial and after repeated use,
It showed a good charge amount, was clear and free of fog, and gave a high-density image. Furthermore, OHP
The image reproduced on the sheet showed good transparency.

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Claims (1)

[Claims] 1. A dry developer containing a toner containing a colorant composed of a chromatic dye or pigment, a binder resin and a charge control agent, and a coated carrier, wherein the binder resin has a softening point of 90 to 110 ° C. It is a polyester resin and the charge control agent is represented by the following general formula (1): (Wherein M represents lithium, sodium or potassium), a metal salt of a benzylic acid derivative, and the coating material is a silicone resin or an acrylic resin in which conductive powder is dispersed. Characteristic dry developer.