JPH05281776A - Positively chargeable color toner - Google Patents

Abstract

(57) [Summary] [Object] The present invention aims to provide a non-uniformity of the positive charging property caused by the constituent components of the conventional positively charging color toner, such as the positive charge control agent, the binder resin, the colorant and the fluidizing agent. sex,
Decrease in image density due to instability, increase in background fog,
The present invention provides a positively chargeable color toner that solves problems such as toner scattering and has excellent positively chargeability and a good life as a developer. [Structure] The number of CO ₂ gas adsorption is 4.0 on the surface of the colored particles containing a binder resin, a colorant and a charge control agent as main components.
Particles / nm ² or less and a specific surface area by BET method of 80
Alumina particles treated with m ² / g or more of a silane coupling agent were added in an amount of 0.1 parts by weight based on 100 parts by weight of the colored particles.
A positively chargeable color toner characterized by being fixed to ˜10.0 parts by weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positively chargeable color toner for developing an electrostatic latent image in electrophotography, electrostatic recording and the like.

[0002]

2. Description of the Related Art Nigrosine dye has been mainly used as a charge control agent used in a positively chargeable toner for electrostatic charge development. However, since the nigrosine dye is used for black toner because it is blackish brown, it cannot be used for color toners such as yellow, cyan, and magenta, and it is colorless as a charge control agent for color toners. Quaternary ammonium salts have been commonly used. However, the quaternary ammonium salt has a drawback that the dispersibility in the binder resin is poor and the chargeability is inferior to that of the nigrosine dye. On the other hand, as a binder resin for color toner, a polyester resin is preferably used because it is excellent in light transmittance and color superimposing property, but a conventional charge control agent such as a quaternary ammonium salt is used as the binder resin. The chargeability thereof was unstable under the influence of the acid group and the hydroxyl group contained in, and there was a problem in controlling the chargeability.

Further, as a colorant for color toner,
Xanthene-based magenta dyes, quinacridone-based magenta color pigments, disazo-based yellow pigments, phthalocyanine-based cyan color pigments, etc. are known, and they are essential materials for color control of color toners, but their chemical structure is The chargeability varies depending on the influence, and does not necessarily have a preferable influence on the positively chargeable toner. Furthermore, the toner needs to have fluidity due to its nature, and therefore one or more fluidizing agents are attached to the surface of the toner. Colloidal silica has been conventionally used as a fluidizing agent for such toner. However, since colloidal silica inherently has a strong negative chargeability, a positively chargeable toner using colloidal silica should be positively charged to the toner while being mixed and stirred in the developing device. There are problems that the charging property is impaired, fogging and toner scattering occur during development, and these fluidizing agents accumulate in the developer, which shortens the life of the developer.

[0004]

SUMMARY OF THE INVENTION The present invention provides a positive charge control agent such as a quaternary ammonium salt which is a constituent component of a conventional positively chargeable color toner, a polyester resin,
The above problems caused by colorants for color toners, fluidizing agents, etc. have been solved, and there are no problems such as a decrease in image density due to nonuniformity of positive charging property, an increase in background fog, and toner scattering. An object of the present invention is to provide a positively chargeable color toner having a positively chargeable property and capable of obtaining many copies.

[0005]

According to the present invention, the number of CO ₂ gas adsorption is 4.0 or less / nm ² or less on the surface of colored particles containing a binder resin, a colorant and a charge control agent as main components. In addition, 0.1 to 10.0 parts by weight of alumina particles treated with a silane coupling agent having a specific surface area by the BET method of 80 m ² / g or more are fixed to 100 parts by weight of the colored particles. Is a positively chargeable color toner.

The alumina particles used in the present invention are ultrafine particles of alumina produced by hydrolyzing anhydrous aluminum chloride at high temperature (flame), and the surface thereof is treated with a silane coupling agent. _The number of adsorbed ₂ gases is 4.0 / nm ² or less, and the specific surface area by BET method is 80 m ² / g or more. The number of CO ₂ gas adsorption and the specific surface area by the BET method can be adjusted within the numerical range specified in the present invention by selecting the alumina fine particles as the core having a small particle diameter of, for example, about 40 mμ or less. However, it is possible to adjust the amount of the silane coupling agent depending on the type thereof. Aluminium Oxide manufactured by Nippon Aerosil Co., Ltd. is used as the alumina fine particles serving as the core.
C etc. are on the market. Examples of the silane coupling agent include dimethyl silicone, methyltrimethoxysilane, (3-aminopropyl) trimethoxysilane,
(3-Aminopropyl) triethoxysilane, {3-
(2-aminoethoxy) propyl} triethoxysilane, {3- (2-aminoethoxy) propyl} trimethoxy _{silane, C 8 F 17 SO 2 NC} 2 H
₅ (CH ₂ ) ₃ Si (CH ₃ O) _{3 and the} like are not particularly limited and include dimethyl silicone,
C ₈ F ₁₇ SO ₂ NC ₂ H ₅ (CH ₂ ) ₃ Si (CH
₃ O) ₃ is particularly preferable because a stable positive charging property can be obtained.

In the present invention, the method for measuring the number of CO ₂ gas adsorption of alumina particles and the specific surface area by the BET method is a commercially available high precision automatic gas adsorption device (BELSORP28, manufactured by Nippon Bell Co., Ltd.) or the like. In this case, the specific surface area according to the BET method uses N ₂ gas which is an inert gas as the adsorption gas. Specifically, the adsorption amount Vm (cc / g) required to form a monomolecular layer on the surface of alumina particles can be measured, and the specific surface area S (m ² / g) can be determined by the following formula. S = 4.35 × Vm (m ² / g) The CO ₂ gas adsorption number can be determined by the following formula by measuring the CO ₂ gas adsorption amount.

When alumina particles having a CO ₂ gas adsorption number of more than 4.0 / nm ² are adhered to the surface of the colored particles, ambient conditions of normal temperature and normal humidity (25 ° C./60% RH) and low temperature and low humidity are set. Under the environmental conditions (10 ° C./20% RH), the triboelectric charge amount becomes high during stirring in the developing machine, resulting in a decrease in image density. In addition, high temperature and high humidity environmental conditions (35 ° C
/ 85% RH), the amount of triboelectricity is reduced due to the adsorption of water, and the problems of increased fog and toner scattering occur. When alumina particles having a specific surface area of less than 80 m ² / g according to the BET method are fixed on the surface of the colored particles, the capacity of the alumina particles as a fluidizing agent is small, and thus the positively chargeable color toner is likely to aggregate.

The colored particles constituting the present invention include a binder resin,
A colorant, a charge control agent, and other additives that are added as necessary are dry-blended into a desired composition, and this mixture is melt-kneaded using an extruder or a roll mill, and the obtained lumps are jet-milled. It is obtained by pulverizing with a mechanical pulverizing means (1) to classify into particles having an average particle diameter of 2 to 15 μm. Further, it can be obtained by a polymerization method other than the melt kneading method as described above. That is, a colorant as described above and other additives added as necessary are added to the monomers constituting the binder resin, mixed and dispersed or dissolved to obtain a polymerization composition, and the polymerization composition is polymerized. Colored particles can be formed at most. In this case, as a method for polymerizing the monomer, a suspension polymerization method,
An emulsion polymerization method or the like can be appropriately used, and when a polymerization initiator, a cross-linking agent, a polymerization catalyst, a polymerization stabilizer and the like are required for the polymerization, these can be added to the polymerization composition.

As the binder resin used for the colored particles in the present invention, those generally used as the binder resin for electrophotographic dry toner are applied, and are not particularly limited, and examples thereof include styrene resin and acryl. Examples thereof include acid ester resin, styrene-acrylic acid ester copolymer resin, vinyl chloride resin, vinyl acetate resin, vinylidene chloride resin, phenol resin, epoxy resin and polyester resin. In the present invention, since stable positive charging characteristics can be obtained by using the alumina particles, it is preferable to use a polyester resin having excellent light transmittance and color superimposing property among the binder resins.

As the above polyester resin, those obtained by polycondensation of alcohol and carboxylic acid are appropriately used and are not particularly limited. Here, as the alcohol, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol,
1,4-butanediol, neopentyl glycol,
Etherification of diols such as 1,4-butenediol, 1,4-bis (hydroxymethyl) cyclohexane, and bisphenol A, polyoxyethylenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropyleneized bisphenol A, etc. Examples include bisphenols and other dihydric alcohol monomers. Examples of the carboxylic acid include maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid. Examples thereof include anhydrides of these acids, dimers of lower alkyl esters and linoleic acid, and other divalent organic acid monomers.

As the polyester resin used in the present invention, not only the above-mentioned polymer containing only the bifunctional monomer but also a polymer containing a component containing a trifunctional or more polyfunctional monomer is preferably used. Is. Examples of the trihydric or higher polyhydric alcohol monomer that is such a polyfunctional monomer,
For example, sorbidol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentane. Triol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane,
1,3,5-trihydroxymethylbenzene and others can be mentioned. Examples of trivalent or higher polycarboxylic acid monomers include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,
2,4-cyclohexanetricarboxylic acid, 2,5,7-
Naphthalene tricarboxylic acid, 1,2,4-naphthalene tricarboxylic acid, 1,2,4-butane tricarboxylic acid,
1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra (methylenecarboxyl) methane, 1,2,5
Mention may be made of 7,8-octanetetracarboxylic acid, employer trimer acid and their acid anhydrides. In addition, in the polyester resin that can be used in the present invention, the component of the above trifunctional or higher polyfunctional monomer is 30 to 80 in each of the alcohol component or the acid component as the structural unit in the polymer. It is desirable to contain it in a ratio of mol%.

As the colorant used for the colored particles, all chromatic dyes and pigments generally used as a colorant for a dry color toner for electrophotography can be used. Examples thereof include rhodamine-based magenta dyes, quinacridone-based magenta pigments, phthalocyanine-based cyan pigments, phthalocyanine-based green pigments, disazo-based yellow pigments, monoazo-based red pigments, and anthraquinone-based dyes. The amount used is preferably 2 to 15 parts by weight with respect to 100 parts by weight of the binder resin. If the amount used is less than 2 parts by weight, coloring of the toner image will be insufficient, and if it exceeds 15 parts by weight, the fixability of the toner may be poor.

As the charge control agent used for the colored particles, a conventionally used colorless or light-colored positive charge control agent is appropriately used, but it is generally the fourth type.
Grade ammonium salts are used. Specific examples of the quaternary ammonium salt include the product name Bontron P-51 and the product name Bontron A manufactured by Orient Chemical Industry Co., Ltd.
Examples include FP-B, trade name TP-302 and trade name TP-415 manufactured by Hodogaya Chemical Co., Ltd. Furthermore, examples of the additive added to the colored particles as needed include low molecular weight polypropylene and low molecular weight polyethylene as an offset preventive agent.

The positively chargeable color toner of the present invention is obtained by fixing the above-mentioned alumina particles on the surface of the colored particles. As a method of fixing the alumina particles to the surface of the colored particles, a mixed powder in which the alumina particles 2 are dispersed and adhered to the surface of the colored particles 1 is prepared by a mixer such as a Henschel mixer, as shown in FIG. By applying this mixed powder to a surface reforming machine (Nara Machinery Co., Ltd.'s Nara Hybridization System, Hosokawa Micron's Ong Mill, etc.), and applying compression force and frictional force to the mixed powder mixture (hereinafter, Surface modification treatment), Fig. 1
As shown in (b), the colored particles are fixed so that at least a part of the alumina particles is embedded in the surface of the colored particles.
In this case, the mixing ratio of the alumina particles to the colored particles needs to be 0.1 to 10 parts by weight of the alumina particles with respect to 100 parts by weight of the colored particles. If the amount of alumina particles is less than 0.1 part by weight, toner particles having good positive chargeability cannot be obtained. On the other hand, if the amount exceeds 10 parts by weight, the positive chargeability of toner particles is excessive, that is, the charge amount is high. Not only is the image density too low to obtain sufficient image density, but since alumina particles inherently tend to be negatively charged, fog and toner scattering may occur during mixing and stirring in the developing machine. This will shorten the life of the developer.

In the present invention, a fluidization improver can be attached to the surface of the positively chargeable toner particles obtained as described above, if necessary. As the fluidization improver, hydrophobic alumina particles, hydrophobic silica, and the like, which are colorless and do not affect the hue of the color toner, can be used as necessary. As a means for adhering to the color toner, a general mixer such as a paddle type mixer, a turbine type mixer and a Henschel mixer can be used. In addition, a surface modifier such as an Ongmill manufactured by Hosokawa Micron Co., Ltd. or a hybridizer manufactured by Nara Machinery Co., Ltd. can also be applied.

When developing with the positively chargeable color toner of the present invention, it is used as a two-component developer by mixing with a carrier generally used in electrophotography. As the carrier used here, an iron powder carrier, a ferrite carrier and the like can be appropriately selected, and among them, a silicon-coated ferrite carrier is particularly preferable. This is because in the combination with the toner according to the present invention, the charging property is the best, and the life of the developer can be extended. Further, in order to obtain high image quality, the carrier current value is preferably 0.2 to 2.0 μA. When it is 0.2 μA or less, the image quality of lines and fine lines is good, but the image density of the solid part is low,
There are drawbacks such as strong edge effect. On the other hand, 2.0μ
When it is A or more, the image quality is deteriorated, and the toner development amount is too large, and the toner consumption amount becomes excessive. The method of measuring the carrier current value here is to put only the carrier in the developing device, use an aluminum drum instead of the photoconductor, and set a gap of 4 m between the aluminum drum and the developing sleeve.
The current flowing into the aluminum drum when the voltage of 200 V was applied to the developing sleeve side was measured to obtain the carrier current value.

[0018]

EXAMPLES Next, the present invention will be explained by examples. Example 1 Materials having the following composition were mixed with a super mixer, melt-kneaded with an extruder, cooled and solidified, and then pulverized and classified by a jet mill and an air classifier to prepare colored particles having an average particle diameter of 8.5 μm. -Thermoplastic polyester resin 100 parts by weight (NCP-001V manufactured by Nippon Carbide Industry Co., Ltd.)-Xanthene rhodamine dye 10 parts by weight (Oil Pink 312 manufactured by Orient Chemical Industry Co., Ltd.)-Quaternary ammonium salt 2 parts by weight (Orient Chemical Industry Co., Ltd.) Bontron P-51) -Polypropylene 5 parts by weight (Viscole 660P manufactured by Sanyo Kasei Co., Ltd.) Next, using a 20 liter Henschel mixer with the following composition, the mixture was mixed at 2000 rpm for 5 minutes to form alumina particles on the surface of the colored particles. The adhering mixed powder was produced. In addition, the alumina particles in the following composition are alumina fine particles (Aluminum Oxid manufactured by Nippon Aerosil Co., Ltd.).
e C) 1.2 parts by weight of dimethyl silicon for 100 parts by weight
5 parts by weight and C ₈ F ₁₇ SO ₂ NC ₂ H ₅ (CH ₂ ) ₃
The number of CO ₂ gas adsorbed on the surface treated with 2.5 parts by weight of Si (CH ₃ O) ₃ coupling agent is 3.3 / nm.
² has a characteristic surface area of 87 m ² / g by the BET method.・ Colored particles 100 parts by weight ・ Alumina particles 0.5 parts by weight The mixed powder obtained by the above operation was used at 6400 rpm using a hybridizer NHS-1 type manufactured by Nara Machinery Co., Ltd.
Then, a treatment for 3 minutes was performed to prepare toner particles which had been subjected to a surface modification treatment in which alumina particles were fixed to the surface of the colored particles. Further, 0.4 parts by weight of hydrophobic silica (trade name: R-972, manufactured by Nippon Aerosil Co., Ltd.) was added to 100 parts by weight of the toner particles, and the amount was 1 rpm at 3000 rpm by a Henschel mixer having a capacity of 10 liters. After stirring for a minute, silica particles were attached to the surface of the toner particles to prepare a positively chargeable color toner of the present invention.

Example 2 A positively chargeable color toner of the present invention was produced in exactly the same manner as in Example 1 except that the composition used in producing the mixed powder was changed as follows. Colored particles 100 parts by weight Alumina particles 3.1 parts by weight Example 3 The present invention was carried out in exactly the same manner as in Example 1 except that the formulation for preparing the mixed powder in Example 1 was changed as follows. A positively chargeable color toner of was prepared. Colored particles 100 parts by weight Alumina particles 8.1 parts by weight

Comparative Example 1 Using the colored particles produced in Example 1, the colored particles 10
Hydrophobic silica (trade name: R-97
2, manufactured by Nippon Aerosil Co., Ltd., 0.4 parts by weight,
Rotation speed 3 by Henschel mixer of liter capacity
The mixture was stirred at 000 rpm for 1 minute to adhere silica particles to the surface of the colored particles to prepare a positively charged color toner for comparison. Comparative Example 2 Hydrophobic silica (trade name: R-972, with respect to 100 parts by weight of colored particles obtained by subjecting the colored particles of Example 1 to the same surface modification treatment as in Example 1 without mixing the alumina particles). 0.4 parts by weight of Nippon Aerosil Co., Ltd.) was added, and the rotation speed was 3000 rpm by a Henschel mixer with a capacity of 10 liters.
The silica particles were adhered to the surface of the colored particles by agitating for 1 minute to prepare a positively charged color toner for comparison.

COMPARATIVE EXAMPLE 3 A positively chargeable color toner for comparison was prepared in the same manner as in Example 1 except that the composition used in preparing the mixed powder in Example 1 was changed as follows. Colored particles 100 parts by weight Alumina particles 17.6 parts by weight Comparative Example 4 In place of the alumina particles used in preparing the mixed powder in Example 1, the CO ₂ gas adsorption number was 5.1 particles / nm.
Except that the specific surface area by BET method at ² using alumina particles of 92m ² / g, to prepare a positively chargeable color toner for comparison in the same manner as in Example 1. Comparative Example 5 Instead of the alumina particles used in producing the mixed powder in Example 1, the number of CO ₂ gas adsorption was 4.4 particles / nm.
Except that the specific surface area by BET method at ² using alumina particles of 10 m ² / g, to prepare a positively chargeable color toner for comparison in the same manner as in Example 1.

For each of the positively chargeable color toners of Examples 1 to 3 and Comparative Examples 1 to 5 described above, using a V-type mixer (W-3 type) manufactured by Tsutsui Rikagaku Kikai Co., Ltd., the following composition was used.
The mixing operation was performed for 1 minute to prepare a positively chargeable color developer. -Positively charged color toner 5.5 parts by weight-Silicon coated ferrite carrier (FSL96-2535 94.5 parts by weight manufactured by Powdertech Co., Ltd. Carrier current value: 1.0 μA) Next, the examples and comparisons prepared by the above operations The two-component positively chargeable color developer of the example is applied under the following environmental conditions.
A copy test was performed on up to 00 sheets, and the results are shown in Table 1. Normal temperature and normal humidity (N / N) ………………………………………… 25 ℃ / 60% RH High temperature and high humidity (H / H) ………………………………… ...... 35 ℃ / 85% RH Low temperature and low humidity (L / L) ………………………………………… 10 ℃ / 20% RH The copy tester is Sharp Copier SF-830.
0 was used. The triboelectric charge amount in the table was measured by a blow-off charge amount measuring device manufactured by Toshiba Chemical Co., the image density was measured by a reflection densitometer RD-914 manufactured by Macbeth, and the fog was measured by a color difference meter TC-60S manufactured by Nippon Denshoku Co., Ltd. For the toner scattering, the scattering condition of the toner around the developing device was visually determined. The evaluation criteria were as follows: ◯: no toner scattering, Δ: small amount of toner scattering, x: large amount of toner scattering. As is clear from Table 1, in the examples according to the present invention, the image density was practically no problem, fogging was small, and toner scattering did not occur. On the other hand, in all the comparative examples, it was confirmed that the toner was scattered after 5000 sheets, the image density was lowered in the image quality, and the fog was increased.

[Table 1]

[0023]

According to the present invention, by fixing specific alumina particles on the surface of the colored particles, excellent positive chargeability can be obtained, and a positively chargeable color toner having good image characteristics and environment resistance characteristics can be obtained. Obtainable. In addition, since such a constitution can provide excellent positive chargeability, that is, a uniform and stable positive chargeability at an appropriate charge amount level, a binder resin which must be considered in the quality design of conventional color toner particles. Since the charging characteristics of the colorant and the colorant can be almost ignored, it has an excellent effect that the permissible range of selection of these materials is widened and facilitated.

[0024]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of toner particles showing a state in which alumina particles adhere to the surfaces of colored particles of the present invention.

[Explanation of symbols]

 1 colored particles 2 alumina particles

Claims (2)

[Claims] 1. The number of CO ₂ gas adsorption is 4.0 or less / nm ² and the specific surface area by BET method is 80 m on the surface of colored particles containing a binder resin, a colorant and a charge control agent as main components. A positively chargeable color toner, characterized in that 0.1 to 10.0 parts by weight of alumina particles treated with ² / g or more of a silane coupling agent are fixed to 100 parts by weight of the colored particles. 2. The silane coupling agent is dimethyl silicone or C ₈ F ₁₇ SO ₂ NC ₂ H ₅ (CH ₂ ) ₃ Si.
The positively chargeable color toner according to claim 1, which is (CH ₃ O) ₃ .