JPH07128911A - Electrophotographic color developer - Google Patents

Abstract

PURPOSE:To provide an electrophotographic full-color developer for forming a full-color picture good in transferability, cleanability and charge retainability. CONSTITUTION:This color developer consists of plural color toners contg. a binde resin and an org. pigment and is used to form a full-color picture. The developer contains a color toner contg. the magenta org. pigment and yellow org. pigment surface-treated with 0.1-5wt.% of the abietic acid, its isomer, their metallic salts or modified material. The toner is produced by previously dispersing the surface-treated magenta or yellow org. pigment in the resin by flashing, melting and kneading the obtained pigment-dispersed resin with a binder resin and cracking the molten mixture.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic full-color developer for forming a full-color image using a plurality of developers.

[0002]

2. Description of the Related Art Conventionally, there are three types of magenta, yellow and cyan.
Considering color development and color reproducibility, for each toner, a developer that displays full color by color and a developer that displays two solid colors such as black and red, blue or green
The type and amount of the colorant are determined mainly by giving priority to the color tone. By the way, each colorant has a conjugated double bond having a π electron for coloring, an electron-donating group, an electron-withdrawing group, and the like, and may be positively or negatively positively charged. Mostly. Therefore, a charge control agent is added to the toner so that the toner has a desired chargeability.

[0003]

However, since a satisfactory color copy cannot be obtained only by adding the charge control agent, an external additive which adheres to the outermost layer of the toner and exerts a strong influence on the chargeability is used. It is common practice to adjust the chargeability of each developer by its type and amount. However, when a full-color copy is obtained by using the same developing system, transfer system, cleaning system, and fixing system using three-color full-color developers, the amount of charge and the type of external additive are different between the toners of each color. Differences in powder characteristics due to the blending amount, differences in adhesion force due to the image force with the photoconductor, and the like occur, causing a problem that all three colors do not behave the same. That is, transfer failure, cleaning failure, etc. occur. Therefore, Japanese Patent Application No. 5-90
As proposed in No. 567, a method of adjusting the charging property by changing the type of the charge control agent has been tried.
In this case, it is possible to make the initial chargeability equal, but due to the increase in the types of charge control agents and the change in type of charge control agents, the deterioration behavior after long-term use will differ, and There is a problem that it is difficult to maintain the same chargeability of each color. The present invention has been made for the purpose of improving the above problems. That is, an object of the present invention is to provide a full-color developer for electrophotography for forming a full-color image having good transferability, cleaning property and charge retention property. Another object of the present invention is to provide a method for producing a color toner for a full color developer for electrophotography.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to improve the above-mentioned problems in which the type and amount of external additive differ for each color, and as a result, surface treatment with an abietic acid derivative was conducted. It has been found that by using a toner containing an organic pigment, transfer failure, cleaning failure, charge retention failure, etc. can be prevented without significantly changing the external additive composition of the toner and without changing the carrier type. The present invention has been completed.

The present invention provides a full-color developer for forming a full-color image composed of a plurality of color toners containing at least a binder resin and an organic pigment.
A color toner containing a magenta organic pigment surface-treated with 5 wt% of abietic acid or its isomer, a metal salt or modified product of abietic acid or its isomer, and 0.1-5 wt% of abietic acid or Its isomer,
The present invention is characterized by containing a color toner containing a yellow organic pigment surface-treated with a metal salt or modified product of abietic acid or its isomer.

The color toner for full color developer used in the present invention is 0.1 to 5 relative to the color toner.
A pigment dispersion obtained by previously dispersing a magenta organic pigment or a yellow organic pigment surface-treated with a weight% amount of abietic acid or an isomer thereof, a metal salt thereof or a modified product thereof in a resin by a flushing method. It is preferably produced by melt-kneading a resin with a binder resin and pulverizing.

The present invention will be described in detail below. Examples of the binder resin that constitutes the color toner in the present invention include styrene and homopolymers of styrenes such as vinyltoluene, α-methylstyrene, chlorostyrene, aminostyrene or copolymers with other monomers. , Homopolymers of methacrylic acid and methacrylic acid esters such as methyl methacrylate, ethyl methacrylate and butyl methacrylate, or copolymers with other monomers, acrylic acid and methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate Homopolymers of acrylic acid esters such as or copolymers with other monomers, butadiene, dienes such as isoprene, acrylonitrile, vinyl ethers, maleic acid, maleic acid esters, maleic anhydride, vinyl chloride, Vinyl acetate, etc. Homopolymers of vinyl monomers or copolymers with other monomers, homopolymers of olefins such as ethylene and propylene or copolymers with other monomers, and further polyesters, polyamides, polyurethanes Etc., and these can be used alone or in the form of being mixed with other resins.

Among these binder resins, polyester resin can be preferably used. The polyester resin can be produced by reacting a polyhydric alcohol with a polybasic carboxylic acid or its reactive derivative. Examples of the polyhydric alcohol constituting these polyester resins include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol,
1,3-propylene glycol, 1,4-butanediol, neopentylene glycol, cyclohexanedimethanol and other diols, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropyleneated bisphenol A and other bisphenol A alkylenes Examples thereof include oxide addition compounds and other dihydric alcohols. Further, as the polybasic carboxylic acid,
For example, malonic acid, succinic acid, adipic acid, sebacic acid, alkylsuccinic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, cyclohexanedicarboxylic acid, isophthalic acid, terephthalic acid and other two bases. Carboxylic acid or a reactive derivative such as an acid anhydride, an alkyl ester or an acid halide thereof.

In addition to these carboxylic acids, a polyhydric alcohol having a valence of 3 or more and / or a polybasic carboxylic acid having a valence of 3 or more is added in order to make the polymer non-linear to the extent that tetrahydrofuran insoluble matter is not produced. Good. Examples of trihydric or higher polyhydric alcohols include sorbitol, 1,
2,3,6-hexanetetraol, 1,4-sorbitan, pentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin,
2-methylpropanetriol, 2-methyl-1,2,
4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trimethylolbenzene, etc. can be mentioned. Examples of the tribasic or higher polybasic carboxylic acid include 1,2,4-butanetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid,
1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid and the like can be mentioned. Among these polyester resins, polycondensates containing aromatic polycarboxylic acid and bisphenol A as main monomer components, for example, linear obtained from terephthalic acid-ethylene oxide adduct of bisphenol A-cyclohexanedimethanol Polyester having a softening point of 90 to 150 ° C., a glass transition point of 50 to 70 ° C., a number average molecular weight of 2000 to 6000, a weight average molecular weight of 8000 to 150,000, an acid value of 5 to 30,
Those having a hydroxyl value of 25 to 45 are particularly preferably used.

On the other hand, examples of the organic pigment contained in the color toner include C.I. I. Pigment Red 48:
1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 12, C.I. I.
Pigment Yellow 17, C.I. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 3 and the like can be illustrated as typical ones.

In the present invention, among these organic pigments, the magenta organic pigment and the yellow organic pigment are abietic acid or its isomers, their metal salts or modified products (hereinafter, these are referred to as abietic acid derivatives). The surface is treated. Examples of the isomers of abietic acid include structural isomers such as levopimaric acid and dextropimaric acid. The metal salt of abietic acid or its isomers includes calcium salt, sodium salt, potassium salt,
Magnesium salt etc. can be mentioned. As modified forms of abietic acid or its isomers, ester gum,
Examples thereof include maleated resins and hydrogenated substances.
In the present invention, the surface treatment with these abietic acid derivatives is carried out so that the content of the magenta organic pigment or yellow organic pigment to be treated is 0.1 to 5% by weight.

In the present invention, the abietic acid derivative, which is a surface treatment agent for organic pigments, is used as a vehicle by (1) preventing pigment crystal growth, (2) preventing aggregation during drying, and (3) making the pigment surface lipophilic. Of the abietic acid derivative has a strong negative chargeability when the treatment amount exceeds 5% by weight, for example, when it is used in the range of 10 to 20% by weight. In addition, it becomes necessary to adjust the amount of processing among the color toners.
That is, due to the strong negative chargeability of the abietic acid derivative, if the amount of use differs among the color toners, the effect on the chargeability of the color toners also varies, resulting in a difference in toner chargeability. However, in the present invention, since the treatment amount is 0.1 to 5% by weight, such a problem does not occur. On the other hand, the amount of surface treatment is
If it is less than 0.1% by weight, the effect of addition for the above (1) to (3) is lost.

Further, in the present invention, the content of the organic pigment is preferably in the range of 2 to 8 parts by weight with respect to 100 parts by weight of the binder resin. When the content of the organic pigment is less than 2 parts by weight, the coloring power is weakened, and when it is more than 8 parts by weight, the transparency of the color toner is deteriorated. Especially 3
In the range of up to 5.5 parts by weight, the graininess (image) of the halftone portion of the color toner is remarkably improved, which is preferable.

Next, a method for producing the color toner of the present invention will be described. In the color toner of the present invention,
When a magenta organic pigment and a yellow organic pigment are used, the desired amount of the above-mentioned abietic acid derivative is present during the coupling reaction of the organic pigment or in the slurry after the completion of the reaction, whereby the surface-treated magenta organic pigment and yellow An organic pigment is obtained. The magenta organic pigment and the yellow organic pigment which have been surface-treated are mixed with a resin in a wet cake state after removing water to perform a flushing treatment. That is, a mixture of an organic pigment wet cake and a resin is heated and kneaded in a pressure heating kneader to obtain a pigment dispersion in which the organic pigment is dispersed. In this case, the resin used is preferably the same or the same kind as the binder resin to be mixed thereafter. The obtained pigment dispersion is then melt-kneaded with the binder resin, pulverized and classified. It is possible to obtain a color toner in which the organic pigment is dispersed in the state of primary particles. The particle size of the color toner is generally set in the range of 3 to 12 μm. Particularly preferably, it is in the range of 5 to 9 μm.

In the present invention, in order to improve the charge level of the color toner, a colorless charge control agent such as a salicylic acid metal salt, a metal-containing azo compound, nigrosine or a quaternary ammonium salt may be added. In addition, low molecular weight polypropylene and low molecular weight polyethylene,
Other known components such as an offset preventive agent such as wax may be added. Further, the color toner may contain an external additive. Fine powders added as external additives include TiO ₂ , SiO ₂ , Al ₂ O ₃ , and Mg.
O, CuO, ZnO, SnO ₂ , CeO ₂ , Fe
₂ O ₃ , BaO, CaO, K ₂ O, Na ₂ O, Zr
O ₂ , CaO · SiO ₂ , K ₂ O (TiO ₂ ) n, Al
₂ O ₃ · ₂ SiO ₂ , CaCO ₃ , MgCO ₃ , BaS
Inorganic fine powders such as O ₄ , MgSO ₄ , MoS ₂ , silicon carbide, boron nitride, carbon black, graphite, and fluorinated graphite, and polymer fine powders such as polystyrene, polycarbonate, polymethylmethacrylate, and polyvinylidene fluoride are listed. These may be used alone or in combination of two or more. Among these fine powders, inorganic fine powders such as TiO ₂ and SiO ₂ are preferably used. The fine powder preferably has a particle size of 0.1 μm or less. When these external additives are used, it is preferable that the compositions of the external additives are substantially the same among the color toners.

The color toner may be used as a two-component developer using a carrier. The carrier may be a resin carrier prepared by kneading and pulverizing magnetic powder and a binder resin, a non-coated carrier made of iron powder or steel shot, or a carrier having a core (iron powder, steel shot, ferrite powder, etc.) coated with resin. Good. It may also be used as a one-component developer that does not use a carrier.

[0017]

In the present invention, the above-mentioned abietic acid derivative, which is a surface treatment agent for organic pigments, comprises (1) prevention of pigment crystal growth,
(2) Prevents agglomeration during drying, and (3) improves the wettability of the vehicle by making the pigment surface lipophilic, but the treatment amount should be reduced to the range of 0.1 to 5% by weight. As a result, the strong negative charging property of the abietic acid derivative does not affect the charging property. In the production of color toner, the binder resin is preliminarily dispersed by using a flushing method, and then kneaded and dispersed with the binder resin to achieve almost primary dispersion of the pigment crystals. ) To (3) can improve the deterioration of the color characteristics due to the aggregation of the coloring material, which is an important factor for achieving the purpose,
A small amount of the abietic acid derivative can be treated. Further, each of the organic pigments, as its chemical structure shows, shows different charging properties from each other, but by dispersing them into primary particles by a flushing method, the coloring power can be increased and the amount of pigment used can be reduced, Further, by making the particle size smaller, the exposure of the toner surface is significantly reduced, and as a result, the influence on the charging property of the color toner can be reduced. As described above, in the present invention, by adopting the two means of temporarily dispersing the coloring material of the organic pigment having a small particle diameter and using a small amount of the abietic acid derivative, a further effect can be obtained and the color characteristics are deteriorated. It is possible to remarkably reduce the difference between charged colors without performing the above.

[0018]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples. In addition, the following "part" means a weight part. Example 1 A. Production of magenta developer i) Preparation of pre-dispersed colorant (a) Polyester resin 70 parts (ethylene oxide adduct of bisphenol A-terephthalic acid; Tg: 65 ° C, Mn: 3500, Mw: 10000) (b) C.I. I. Pigment Red 57: 1 wet cake 30 parts (treated with calcium salt of abietic acid) (excluding water) C. of (b) above. I. Pigment Red 57: 1 (treated with calcium salt of abietic acid) was subjected to surface treatment by allowing the calcium salt of abietic acid to be present in the coupling reaction so as to have the following composition. (D) C.I. I. Pigment Red 57: 1 95 parts (e) Calcium abietic acid salt 5 parts The above components (a) and (b) are mixed and subjected to a color material predispersion treatment in a pressure heating kneader at 100 ° C. for 30 minutes. ,
(C) A pre-dispersed magenta coloring material was obtained. (Flushing treatment step) ii) Preparation of magenta toner (a) Polyester resin (same as above) 83.3 parts (c) Pre-dispersed magenta coloring material 16.7 parts The above materials are kneaded with an extruder and pulverized with a jet mill. After that, classification was performed by air classification to obtain toner particles having an average particle size of 9 μm. On the other hand, 100 g of crystalline titania having an average particle diameter of 15 nm was stirred with 10 g of orthomethoxydecylsilane in methanol for 30 minutes, filtered, dried, and then crushed with a pin mill to obtain a first external additive. Further, dry silica having an average particle diameter of 40 nm (OX50; manufactured by Nippon Aerosil Co., Ltd.) was treated with 15 g of hexamethyldisilazane to obtain a second external additive. A magenta toner was prepared by adding 0.8 parts of a first external additive and 0.8 part of a second external additive to 100 parts of the toner particles and mixing them with a Henschel mixer. iii) Preparation of magenta developer To 100 parts of Cu-Zn ferrite having a particle size of 80 μm, a solution of 0.1 part of γ-aminopropyltriethoxysilane in methanol was added and mixed with a kneader, and then methanol was evaporated, and at 120 ° C. The silane was completely cured by heating for 2 hours. 1.0 part of a dimethylaminoethylmethacrylate-styrene-methylmethacrylate (2:20:78) copolymer was added to the carrier coated with the charge control layer of the first layer, mixed with a kneader, and then mixed at 110 ° C. for 1 hour. A two-layer coated carrier coated with the surface coating layer of the second layer was prepared by heating for a period of time. To 100 parts of this carrier, 5 parts of the magenta toner are mixed with a paint shaker,
A magenta developer was produced.

B. Production of yellow developer i) Preparation of predispersed yellow coloring material (a) Polyester resin (same as above) 70 parts (f) C.I. I. Pigment Yellow 17 wet cake 30 parts (abietic acid-treated product) (excluding water) (f) C.I. I. Pigment Yellow 17 (treated with abietic acid) was prepared by adding abietic acid to the slurry after synthesis so as to have the following composition, and treating in a slurry state to perform surface treatment. (H) C.I. I. Pigment Yellow 17 98 parts (i) Abietic acid 2 parts A pre-dispersed yellow coloring material was obtained in the same manner as above using the above components. ii) Preparation of yellow toner (a) Polyester resin (same as above) 83.3 parts (g) Pre-dispersed yellow color material 16.7 parts A yellow toner was prepared in the same manner as for magenta. iii) Preparation of yellow developer A yellow developer was produced by the same method as that for the magenta developer. C. Production of cyan developer I. Pigment 15: 3 and a cyan developer was produced in the same manner as the yellow toner except that it was not treated with abietic acid.

Comparative Example 1 A. Manufacturing Magenta Developer (d) C.I. I. Pigment Red 57: 1 80 parts (e) Abietic acid calcium salt 20 parts Except that the amounts of the component (d) and the component (e) are changed to the above amounts.
A magenta developer was manufactured in the same manner as in the example. B. Production of yellow developer (h) C.I. I. Pigment Yellow 17 90 parts (i) Abietic acid 10 parts Except that the amounts of the component (h) and the component (i) are changed to the above amounts.
A yellow developer was manufactured in the same manner as in the example. C. Production of cyan developer A cyan developer was produced in the same manner as in the example.

Comparative Example 2 A. Preparation of Magenta Developer i) Preparation of Predispersed Magenta Coloring Material (d) C.I. I. Pigment Red 57: 1 83.3 parts (e) Abietic acid calcium salt 16.7 parts Except that the amounts of the component (d) and the component (e) are changed to the above amounts.
A pre-dispersed magenta coloring material was prepared in the same manner as in the example. ii) Preparation of magenta toner (a) Polyester resin (the same as above) 80 parts (b) Pre-dispersed magenta colorant 20 parts Toner particles 1 obtained by melt-kneading, pulverizing and classifying the above components
To 00 parts, 0.2 parts of the same first external additive and 0.4 parts of the second external additive, which were the same as in Example 1, were added and mixed with a Henschel mixer to produce a magenta toner. iii) Production of Magenta Developer A magenta developer was produced in the same manner as in the example. B. Production of yellow developer i) Preparation of pre-dispersed yellow coloring material (d) C.I. I. Pigment Red 57: 1 90.9 parts (i) abietic acid 9.1 parts except that the amounts of the component (d) and the component (i) are changed to the above amounts.
A pre-dispersed yellow coloring material was prepared in the same manner as in the example. ii) Preparation of yellow toner (a) Polyester resin (same as above) 81.7 parts (b) Pre-dispersed yellow coloring material 18.3 parts Toner particles 1 obtained by melt-kneading, pulverizing and classifying the above components
To 100 parts, 0.6 parts of the same first external additive and 0.6 part of the same second external additive as in Example 1 were added and mixed with a Henschel mixer to produce a magenta toner. iii) Production of Yellow Developer A yellow developer was produced in the same manner as in the example. C. Production of Cyan Developer A cyan developer was prepared in the same manner as in Example 1.

The three-color developers prepared in Example 1 and Comparative Examples 1 and 2 were mixed with an FX full-color copying machine (Acolo).
r; manufactured by Fuji Xerox Co., Ltd.) and copied, and the characteristics of the obtained color copy were investigated. The evaluation results are shown in Table 1.

[0023]

[Table 1]

[0024]

INDUSTRIAL APPLICABILITY In the present invention, since the magenta and yellow organic pigments surface-treated with 0.1 to 5% by weight of the abietic acid derivative as described above are used, the composition and amount of the external additive and the charge control agent It is possible to adjust the difference in the charge amount between the color toners without changing the type. In other words, it is possible to achieve more favorable color characteristics and transparency (suitability for overhead projector) without affecting the powder characteristics, transfer characteristics, cleaning characteristics, charge maintaining characteristics, etc. between the color toners. Furthermore, the color toner in the present invention is taken out in the form of a slurry or a wet cake after synthesizing an organic pigment, and using a flushing method,
The organic pigment is dispersed in primary particles because it is kneaded with the binder resin, preliminarily dispersed, and further kneaded with the above binder resin, pulverized, and classified. Therefore, surface treatment with an abietic acid derivative is required. It is possible to further exert the above excellent effects obtained by the above.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location G03G 9/08 381 (72) Inventor Budoo 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Co., Ltd. (72) Inventor Yura Ishihara 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture Fuji Xerox Co., Ltd.

Claims (2)

[Claims] 1. A full-color developer for forming a full-color image composed of a plurality of color toners containing at least a binder resin and an organic pigment, in an amount of 0.1 to 5% by weight.
Of abietic acid or its isomer, a color toner containing a magenta organic pigment surface-treated with a metal salt or modification thereof, and an amount of 0.1-5% by weight of abietic acid or its isomer, a metal salt thereof Alternatively, a full-color developer containing a color toner containing a yellow organic pigment surface-treated with a modified product. 2. A magenta organic pigment or a yellow organic pigment surface-treated with 0.1 to 5% by weight of abietic acid or an isomer thereof, a metal salt thereof or a modified product thereof is previously flushed into a resin by a flushing method. A method for producing a color toner for a full-color developer, which comprises melt-kneading the obtained pigment-dispersed resin with a binder resin and pulverizing after dispersing. [0001]