JPH08262799A - Yellow toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE: To obtain the yellow toner remarkably enhanced in durability against light, while meeting fundamental characteristics such as resistance to the occurrence of toner scattering and fog by containing a thermoplastic resin and a specified benzimidazole type yellow azo pigment. CONSTITUTION: This yellow toner contains at least the thermoplastic resin and the benzimidazole type yellow azo pigment represented by the formula in which each of X and Y is a group selected from -Cl, CH3 -NO2 , -OCH3 , -COOH, -CF3 and the like; and (n) is 1 or 2. Since this benzimidazole type yellow azo pigment has low tendency to cause a photoreduction decomposition reaction browning of an image scarcely occurs, and it exhibits comparatively good dispersibility into various kinds of thermoplastic resins, and has superior fundamental characteristics, such as resistance to the occurrence of toner scattering and fog, and better dispersibility is exhibited, especially, when the thermoplastic resin to be used for the binder resin is a polyester resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to electrophotography, electrostatic recording,
The present invention relates to a yellow toner which is a one-component or two-component developer for developing electrostatic images in electrostatic printing and the like.

[0002]

2. Description of the Related Art In electrophotography, whether the method is a cascade development method (US Pat. No. 2,297,691 or 261855) using a mixed developer of toner and carrier or a magnetic brush method (US Pat. No. 2832311). ,
Alternatively, a touch-down developing method (US Pat. No. 4,121,931) and a non-magnetic one-component developing method (US Pat.
A fixed image is obtained by visualizing the electrostatic charge image or by visualizing the electrostatic charge image by reversal development. In recent years, full-color images have also been obtained by such electrostatic image development. To get a full color image,
The original is exposed by using a color separation filter, and the developing process as described above is repeated a plurality of times using color toners such as yellow, magenta, and cyan to superimpose toner images.

Conventionally, as the colorant contained in the yellow toner used in such electrostatic image development,
C.I. having a structure represented by the following chemical formulas (A) to (C).
I. Pigment Yellow 12, 13, 17 and other benzene type azo pigments are used.

[0004]

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[0005]

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[0006]

[Chemical 4]

However, these benzene type azo pigments do not have satisfactory performance in light resistance,
Further, the toner obtained by adding these is also insufficient in basic characteristics as electrophotographic characteristics such as toner scattering and fog.

[0008]

SUMMARY OF THE INVENTION Therefore, the present invention has been made in view of such a situation as described above, and satisfies the basic characteristics as electrophotographic characteristics such as toner scattering and fog, while maintaining light resistance. The purpose of the present invention is to provide a yellow toner having outstanding durability.

[0009]

The above object is achieved by an electrostatic charge developing toner containing at least a thermoplastic resin and a benzimidazole yellow azo pigment.

The present invention further shows a yellow toner for electrostatic image development, wherein the thermoplastic resin is a polyester resin.

[0011]

As described above, the yellow toner according to the present invention uses a benzimidazole yellow azo pigment as a colorant, and the benzimidazole yellow azo pigment is less likely to undergo a reductive decomposition reaction by light. Therefore, fading of the image hardly occurs. Further, the benzimidazole yellow azo pigment exhibits a relatively good dispersibility in various thermoplastic resins, and the obtained toner is excellent in basic performance such as toner scattering and fog. In particular, when the thermoplastic resin used as the binder resin is a polyester resin, it exhibits better dispersibility and can obtain more excellent basic performance.

Hereinafter, the present invention will be described in more detail based on embodiments.

The benzimidazole yellow azo pigment contained as a colorant in the yellow toner according to the present invention is a compound having a structure represented by the following general formula (I).

[0014]

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Examples of the compound having the structure of the general formula (I) include C.I. I. Pigment Yellow 120

[0016]

[Chemical 6]

C. I. Pigment Yellow 151

[0018]

[Chemical 7]

C. I. Pigment Yellow 154

[0020]

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C. I. Pigment Yellow 180

[0022]

[Chemical 9]

Examples include, but are not limited to, of course.

The compounding amount of such a benzimidazole yellow azo pigment in the yellow toner of the present invention is 2 to 8 with respect to 100 parts by weight of a thermoplastic resin as a binder resin.
Parts by weight are suitable. If the blending amount of the pigment is less than 1 part by weight, a sufficient color tone as a toner cannot be obtained, and if it exceeds 10 parts by weight, faithful gradation reproducibility of an image may be difficult and the fixability may deteriorate. Is.

The thermoplastic resin used for the yellow toner of the present invention may be the same as that used for the conventionally known toner. For example, styrene resin, (meth) acrylic resin, styrene- (meth) acrylic copolymer resin, olefin resin, polyester resin, amide resin, polycarbonate resin, polyether resin, polyvinyl acetate Resins such as resin, polysulfone resin, epoxy resin, urea resin, urethane resin and urea resin can be used alone or in combination of two or more kinds.

Of these thermoplastic resins, polyester resins are particularly preferable. That is, this is because the benzimidazole yellow azo pigment is particularly excellent in dispersibility in combination with a polyester resin and has a remarkable effect in improving toner scattering and fog.

Examples of the polyester resin include polyols such as bisphenols, ethylene glycol, triethylene glycol, 1,2-propylene glycol and 1,4-butanediol, and maleic acid, for example.
Examples thereof include those obtained by polycondensing an aliphatic unsaturated dibasic acid such as itaconic acid, a dibasic acid such as phthalic acid, terephthalic acid, isophthalic acid, malonic acid and succinic acid.

By using a modified polyester in which an unsaturated polyester is present in a polyester resin and an aromatic vinyl monomer is graft-polymerized with the unsaturated polyester, a toner having improved environmental stability can be obtained. it can. The proportion of polyester in this modified polyester is 50% by weight or more, preferably 60 to 90.
% By weight. Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, vinyltoluene, p-ethylstyrene and the like. Further, other vinyl monomers can be used in combination with the aromatic vinyl monomer, and examples thereof include methacrylic acid alkyl esters such as methyl methacrylate, butyl methacrylate, octyl methacrylate and stearyl methacrylate, ethyl acrylate, propyl acrylate. , Alkyl acrylates such as butyl acrylate and octyl acrylate, acrylonitrile, acrylamide or amino groups such as methacrylic acid dimethylaminoethyl ester, methacrylic acid diethylaminoethyl ester, acrylic acid dimethylaminoethyl ester, dimethylaminopropyl methacrylamide, etc. It is possible to use contained vinyl monomers and the like.

In the embodiment in which the yellow toner of the present invention is a translucent toner, the polyester resin has a number average molecular weight (Mn) of 2500 to 12000 and a dispersity (Mw / Mn) of 2 to 6, A glass transition point (Tg) of about 80 to 120 ° C. is suitable. If these physical properties are not satisfied, the light-transmitting property of the toner cannot be sufficiently satisfied, and the fixing property and heat resistance are deteriorated.

The yellow toner according to the present invention is not limited to the thermoplastic resin as the binder resin and the benzimidazole type yellow azo pigment as the colorant as described above, and also the conventional toners such as the charge control agent and the anti-offset agent. Various added additives may be added.

As the charge control agent, any type of positive charge or negative charge can be used. As the positive charge control agent, an amino compound, a quaternary ammonium salt,
Examples of the phosphorus compound and the like, and examples of the negative charge control agent include Saricchi acid derivative and metal salt, hydroxynaphthoic acid derivative and metal salt, and calixarene compound. Examples of the anti-offset agent include low molecular weight polyethylene, low molecular weight polypropylene, vegetable wax, carnauba wax and the like. The amount of these additives to be added is usually about 1 to 10 parts by weight per 100 parts by weight of the thermoplastic resin.

To the yellow toner according to the present invention, a fluidizing agent and a cleaning aid may be further added (typically external addition). As the fluidizing agent, silicon oxide (silica), nitric oxide (titania), aluminum oxide (alumina), zinc oxide or the like is used. The fluidizing agent may be hydrophobized with a coupling agent, a surfactant, or the like. As the cleaning aid, polystyrene fine particles, polymethylmethacrylate fine particles and the like are used. Appropriate amounts of these fluidizing agents and cleaning aids are about 0.1 to 20 parts by weight per 100 parts by weight of the toner mother particles.

Further, as a magnetic material or a magnetizable material added in a mode in which the yellow toner according to the present invention is a one-component developer (magnetic toner), conventionally known materials are used, for example, cobalt, iron, Ferromagnetic metals such as nickel, aluminum, cobalt, iron, lead,
Alloys of metals such as magnesium, nickel, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium and mixtures thereof, or metal compounds including oxides of these metals It can be illustrated. Since the toner according to the present invention is a color toner, it is preferable that the toner, such as metallic iron, hardly affects the hue of the colorant.

The method for producing the yellow toner according to the present invention is not particularly limited, and it can be produced by any conventionally known method such as a pulverizing method, an emulsion dispersion method, a suspension polymerization method and the like.

[0035]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to the examples shown below.

Production Example of Carrier Styrene consisting of styrene, methyl methacrylate, 2-hydroxyethyl acrylate and methacrylic acid
Acrylic copolymer (polymerization ratio 1.5: 7: 1.0:
0.5) 80 parts by weight, and butylated melamine resin 2
Dilute 0 parts by weight with toluene to give a solid content of 2% styrene-
An acrylic resin solution was prepared. Fired ferrite powder as core material (F-300, manufactured by Powder Tech Co., average particle size 50
μm, bulk density 2.53 g / cm ³ ) and the above styrene-acrylic resin solution was applied by a spiral coater (Okada Seiko Co., Ltd.) and dried. The obtained carrier was left in a hot air circulation type oven at 140 ° C. for 2 hours for firing. After cooling, open the ferrite powder bulk to 210 μm
And 90 μm of a screen mesh were used for crushing with a sieve shaker to obtain resin-coated ferrite powder. The coating, firing and crushing steps were repeated 3 times on the ferrite powder to obtain a resin-coated carrier.
The obtained carrier had an average particle diameter of 52 μm and an electric resistance of about 3 × 10 ¹⁰ Ω · cm.

Example 1 Component weight parts Polyester resin 100 (Mn = 3500, Mw / Mn = 2.5 Tg = 65 ° C., softening point = 95 ° C.) Yellow pigment (CI Pigment Yellow 180) 4 (Novoperm Yellow P-HGVP2066, Hoechst Japan Co., Ltd.)-Charge control agent 3 (Bontron E-84, Orient Chemical Co., Ltd.) The above materials were thoroughly mixed with a Henschel mixer, kneaded with a twin-screw extruder, and then cooled. The obtained mixture was roughly pulverized with a feather mill, and then a jet pulverizer and an air classifier were used to obtain toner particles having a particle size of 5 to 25 μm (average particle size 8.2 μm). Next, 0.3% by weight of hydrophobic silica R-974 (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed with a Henschel mixer at 1000 rpm for 1 minute to obtain a toner 1.

Example 2 The yellow pigment of Example 1 was mixed with C.I. I. Pigment Yellow 154 (Pigment Yellow 2080, manufactured by Sanyo Pigment Co., Ltd.), and Toner 2 was obtained in the same manner as in Example 1.

Example 3 Component weight parts Styrene-n-butyl methacrylate resin 100 (Mn = 8300, Mw / Mn = 2.3 Tg = 65 ° C., softening point = 98 ° C.) Yellow pigment (C.I. Pigment Yellow 180) 4 (Novoperm Yellow P-HGVP2066 Hoechst Japan Co., Ltd.)-Charge control agent 3 (P-51, Orient Chemical Co., Ltd.)-Offset inhibitor 5 (Viscor 550P, Sanyo Kasei Co., Ltd.) Then, toner particles were obtained in the same manner as in Example 1. Next, 0.1% by weight of hydrophobic silica R-974 (manufactured by Nippon Aerosil Co., Ltd.) and 0.5% by weight of hydrophobic alumina RXC (manufactured by Nippon Aerosil Co., Ltd.) were added and mixed in the same manner as in Example 1 to obtain a toner. Got 3.

Comparative Example 1 The yellow pigment of Example 1 was mixed with C.I. I. Pigment Yellow 17 (MTY-1, manufactured by Dainichiseika Co., Ltd.), and Toner 4 was obtained in the same manner as in Example 1.

Comparative Example 2 The yellow pigment of Example 3 was mixed with C.I. I. Pigment Yellow 17 (MTY-1, manufactured by Dainichiseika Co., Ltd.), and Toner 5 was obtained in the same manner as in Example 3.

Evaluation The toners 1 to 5 obtained above and the carrier were mixed at a weight ratio of 8/92 to prepare a developer. Of these developers, those containing toner 1, 2 or 4 are CF-80.
(Made by Minolta), EP containing toner 3 or 5
-5400 (manufactured by Minolta) was used to perform initial image formation. Also, the amount of charge was measured after image formation. -Fog on image Regarding the fog on the image, the toner fog on the white background image was evaluated and ranked (three-step evaluation). It can be practically used in a rank or more, but is preferably in a rank or more.・ Lightfastness of the image For the lightfastness of the image, fade meter FAL-5
(Suga Test Instruments Co., Ltd.) was used to irradiate solid areas with light for 48 hours, and rank the fading. The color difference before and after irradiation is ΔE = 0 to 3.0, ○, ΔE = 3.0 to 6.0 is Δ, Δ
E = more than 6.0 was evaluated as x. It can be practically used in a rank or more, but is preferably in a rank or more. The evaluation results are shown in Table 1 below.

[0043]

[Table 1]

[0044]

As described above, the yellow toner of the present invention not only forms an excellent image with less toner scattering and no fog, but also has less light fading because of the excellent light resistance. .

Claims (2)

[Claims] 1. A yellow toner for developing an electrostatic charge image, comprising at least a thermoplastic resin and a benzimidazole yellow azo pigment represented by the following general formula (I). Embedded image 2. The yellow toner for developing an electrostatic image according to claim 1, wherein the thermoplastic resin is a polyester resin.