JP2917366B2 - Magenta toner for full-color electrostatic image development - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magenta toner for developing a full-color electrostatic image for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing and the like.

(Prior Art) In an electrophotographic method, an electrostatic latent image is usually formed on an electrostatic latent image carrier made of a photoconductive photoreceptor by charging and exposing the same, and then the electrostatic latent image is placed in a binder resin. In this method, a visible image is formed by developing with a toner composition containing a colorant and transferring and fixing the obtained toner image to a support such as transfer paper.

As a toner composition for obtaining such a visible image, generally, a composition in which a black colorant such as carbon black is dispersed in a binder resin is often used.
In recent years, a color toner in which a cyan pigment, a magenta pigment, or a yellow pigment is dispersed in a binder has been used. Among these, there are color toners used for obtaining a multicolor image by an electrophotographic method, and generally, cyan, magenta and yellow color toners are used.

In the case of such a color toner, it is also required that a color image obtained by transferring and fixing the color image onto an overhead projector (hereinafter, referred to as an OHP) sheet is printed on a screen by OHP transmission light. .

Generally, the composition of a color toner is composed of the main components of a binder resin and a colorant, and various additives. As the binder resin, polystyrene, styrene- (meth) acrylate copolymer, styrene-butadiene copolymer, polyester, epoxy resin, coumarone indene resin and the like are generally used.

In order to obtain a multi-color image of this color, an electrostatic latent image is formed as described above using light of each color obtained by separating a document by a color separation filter, and yellow, magenta, A method of repeatedly developing using a cyan or other color toner and transferring and fixing the developed toner on paper or the like has been used.

Conventionally, many techniques have been disclosed for such color toners, and particularly for magenta or red color toners, Japanese Patent Application Laid-Open No. 51-24234 discloses a technique relating to a magenta toner using a quinacridone pigment. JP-A-59-165069 and JP-A-62-296167 disclose technologies relating to a magenta toner using various monoazo pigments.

(Problems to be Solved by the Invention) However, it is difficult for these magenta toners of the prior art to maintain a stable charge amount under conditions such as low temperature and low humidity or high temperature and high humidity, and the image characteristics are not affected by environmental changes. It had the disadvantage of being extremely unstable.

Further, a transfer image obtained by repeatedly developing a magenta, cyan, or yellow color toner and transferring it to paper or the like is generally required to have an image quality close to a natural color. For that purpose, it is important that each of the single-color toners of magenta, cyan and yellow has excellent coloring power and good color reproducibility, and improvement for that purpose has been demanded.

An object of the present invention is to provide excellent color reproducibility, a small change in the amount of charge with respect to environmental changes from low-temperature and low-humidity to high-temperature and high-humidity, to provide a good and stable transfer image quality, and a yellow pigment-containing toner. It is an object of the present invention to provide a magenta toner which provides a clear transfer image quality that is very close to a natural color in so-called multicolor superposition using a blue pigment-containing toner in combination.

(Means for Solving the Problems) As a result of intensive studies for solving the above problems, the present inventors have completed the present invention.

That is, the present invention relates to a magenta toner for developing full-color electrostatic images, wherein the naphthol-based organic pigment is represented by the following structural formula in a magenta toner for full-color electrophotography using a naphthol-based organic pigment as a coloring component.

Structural formula: Next, the present invention will be described in detail.

The magenta toner for developing a full-color electrostatic image of the present invention essentially contains the naphthol-based organic pigment having the above structure, and the binder resin is not limited, but is used in the present invention. Depending on the resin, there is a resin that significantly improves the effects of the present invention, and these may be selectively used.

That is, as a binder resin generally used for toner,
Examples include polystyrene, styrene- (meth) acrylate copolymer, styrene-butadiene copolymer, polyester, epoxy resin, butyral resin, xylene resin, and coumarone indene resin. In order to satisfy OHP translucency and fixing strength, it is desired that the resin viscosity at the time of fixing the toner is lower than the resin viscosity of black toner for general copiers. Specifically, polyester resin, epoxy resin Is preferred.

However, the polyester resin and the epoxy resin have a large number of hydrophilic groups such as a carboxyl group and a hydroxyl group in the molecule, and therefore, these resins are used in the most commonly used polystyrene and styrene-acryl copolymer resins. As a result, the hygroscopicity tends to be higher, and as a result, the charge amount with respect to environmental changes tends to fluctuate.

In order to avoid this, a vinyl ester described in JP-A-1-156759 in which a specific amount of an aromatic vinyl monomer and an amino group-containing vinyl monomer is graft-polymerized to an unsaturated polyester comprising at least an unsaturated aliphatic dibasic acid and a polyhydric alcohol. Modified polyesters are more preferred.

That is, a vinyl-modified polyester resin obtained by graft-polymerizing a specific amount of an aromatic vinyl monomer and an amino group-containing vinyl monomer onto an unsaturated polyester resin having many hydrophilic groups such as a carboxyl group and a hydroxyl group is not unsaturated before the graft polymerization. Compared with a saturated polyester resin, the content of hydrophilic groups is low, and the hygroscopicity is low. As a result, the vinyl-modified polyester resin maintains a good full-color reproducibility, OHP translucency, and an appropriate fixing strength, which are characteristics of the polyester resin, and has a small change in the amount of charge with respect to an environmental change.

The amino group-containing vinyl monomer is used to obtain a stable charge amount of the toner. That is, when the content of the vinyl monomer is in the range of 0.1 to 2.0% by weight with respect to the whole vinyl-modified polyester resin, the polyester is negatively charged. The positive charge of the amino group is imposed on the toner, and the toner as a whole becomes uncharged or weakly positively charged. Further, the use of a negative charge control agent can provide an advantage that a desired charge amount can be obtained. .

Furthermore, if the binder resin that can be used in the present invention is laid, a preferred binder resin for achieving the object of the present invention is:
(1) 0.2% of aliphatic unsaturated dibasic acid in polyester resin
(2) 30 to 90 parts by weight of a polyester resin having a weight average molecular weight of 5,000 to 12,000, which comprises a polyvalent carboxylic acid contained so as to be 2.0% by weight and a diol having a propylidene diphenyl group in the molecule; Graft polymerization of 70 to 10 parts by weight of a vinyl monomer containing 50% by weight or more of an aromatic vinyl monomer and 1 to 30% by weight of an amino group-containing vinyl monomer, having a weight average molecular weight of 8,000 to 20,000 and melting at 100 ° C It is a graft polymer having a viscosity of 10 ⁴ to 10 ⁶ poise and a glass transition temperature of 50 to 75 ° C.

Examples of the aliphatic unsaturated dibasic acid include maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic acid and the like. Other polycarboxylic acids include phthalic anhydride, terephthalic acid, isophthalic acid, orthophthalic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, cyclohexanedicarboxylic acid, methylcyclohexanedicarboxylic acid, succinic acid, malonic acid, glutaric acid, adipine Acid, azelaic acid, sebacic acid, carbon number 4
And dibasic acids such as -18 alkyl or alkenyl succinic acids.

Diols having a propylidene diphenyl group in the molecule include hydrogenated bisphenol A and bisphenol A
And propylene oxide adduct of bisphenol A and the like. The average number of moles of propylene oxide and ethylene oxide added in the oxide adduct is suitably 2 to 7, and an adduct to which both propylene oxide and ethylene oxide are added can also be used.

As the polyol component, a polyol other than the above-mentioned bisphenol-type diol may be added as long as it is about 10 mol% or less of the total polyol component. Such polyols include, for example, ethylene glycol, propylene glycol, neopentyl glycol, 3,3,5-trimethyl-2,4-pentanediol, and the like.

In addition to the above components, trimellitic anhydride, glycerin,
It is also preferable to use a trifunctional compound such as trimethylolpropane in combination as long as the polyester resin does not gel. Monofunctional compounds such as benzoic acid, p-tert-butylbenzoic acid, and cyclohexanol can also be used as appropriate as molecular weight regulators for polyester resins. The weight average molecular weight of the polyester resin is 5,000 to 12,00
A range of 0 is appropriate. If the molecular weight of the resin is less than 5,000, the resin becomes excessively brittle and the durability as a toner deteriorates. On the other hand, if it exceeds 12,000 and becomes too large, gelation tends to occur during graft polymerization, and a suitable graft polymer cannot be obtained. Among the components constituting the polyester resin, the aliphatic unsaturated dibasic acid is an important component in terms of becoming a graft active site and introducing a partially crosslinked structure into the graft polymer. If the aliphatic unsaturated dibasic acid is less than 0.2% by weight, graft polymerization becomes difficult to perform,
In addition, gelation exceeding 2% by weight becomes easy. As the aliphatic unsaturated dibasic acid, maleic anhydride is particularly optimal.

The polyester resin can be produced by polycondensing a carboxylic acid component and a diol component at a temperature of 180 to 250 ° C. in an inert gas atmosphere. At this time, a commonly used esterification catalyst such as zinc oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate or the like can be used to accelerate the reaction. Further, it can be manufactured under reduced pressure for the same purpose.

30-90 parts by weight of the polyester resin thus obtained, preferably 50-90 parts by weight, of vinyl monomer 70
The graft polymer is obtained by graft polymerizing 10 parts by weight, preferably 500〜1010 parts by weight. If the amount of the polyester resin is less than 30 parts by weight, a toner exhibiting good fixability and leveling (surface smoothness), which is the object of the present invention, cannot be obtained. On the other hand, if the amount of the polyester resin exceeds 90 parts by weight, the negative chargeability of the polyester is strong, and it is difficult to control the toner mainly composed of the vinyl-modified polyester resin and the colorant to an appropriate charge amount with a negative charge control agent.

Examples of the amino group-containing vinyl monomer which is an essential component of the vinyl monomer include dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, and dimethylaminopropyl methacrylamide. The amount of the amino group-containing vinyl monomer is 1 to 30% by weight, preferably 1 to 20% by weight in the vinyl monomer. If the amount of the amino group-containing vinyl monomer is less than 1% by weight in the vinyl monomer, the entire vinyl-modified polyester resin becomes negatively charged, and as described above, it becomes difficult to control the amount of charge by the negatively charge controlling agent. On the other hand, if the amount exceeds 30% by weight, the positive chargeability is too strong, and it becomes impossible to make the whole toner negative chargeability.

Examples of the aromatic vinyl monomer which is an essential component of the vinyl monomer include styrene, α-methylstyrene, vinyltoluene, and p-ethylstyrene. Other vinyl monomers include methacrylic acid alkyl esters such as methyl methacrylate, butyl methacrylate, octyl methacrylate and styaryl methacrylate; alkyl acrylates such as ethyl acrylate, propyl acrylate, butyl acrylate and octyl acrylate And acrylonitrile, acrylamide and the like.

The graft polymerization reaction is performed by solution polymerization or suspension polymerization. In the case of the solution polymerization method, a vinyl monomer and a polymerization initiator are added to a polyester resin dissolved in a solvent such as xylene or toluene, and the resulting mixture is reacted with an inert gas atmosphere in an atmosphere of 60 to 150.
Polymerizes at a temperature of ° C. In the case of suspension polymerization, a polyester resin and a polymerization initiator are dissolved in a vinyl monomer, then suspended and dispersed in water containing a suspension stabilizer, and polymerized in the same manner. Azo initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile are suitable as polymerization initiators.

Weight average molecular weight of graft polymer is 8,000 to 20,000
And a chain transfer agent such as dodecyl mercaptan or thiophenol can be used if necessary.
If the weight average molecular weight of such a polymer is less than 8,000, it will be excessively brittle as a binder resin, resulting in poor durability as a toner, and if it exceeds 20,000, it will provide good fixing properties and leveling which is the object of the present invention. A toner composition cannot be obtained.

The glass transition temperature of the graft polymer determined by differential thermal analysis is preferably from 50 to 75 ° C, more preferably from 55 to 70 ° C. If the glass transition temperature is too low, the toner tends to block, and if it is too high, the definition becomes poor. The glass transition temperature represents an endothermic peak temperature in differential thermal analysis.

The melt viscosity of the graft polymer measured by a flow tester method is 10 ⁴ to 10 ⁶ poise at 100 ° C., preferably 5 × 10 ⁴ to 10 ⁴
5 × 10 ⁵ poise is appropriate. If the melt viscosity is too low, the offset resistance deteriorates, and if it is too high, when used for OHP, the transmitted light is scattered due to poor leveling of the toner layer fixed on the OHP sheet, resulting in darkening and saturation. Light transmission image.

(Example) Next, an example of the present invention will be described. In addition, "parts" in the compounding amount
Is based on weight.

<Examples of resin production> 64 parts of 2,2'-bis [p- (2-hydroxyethoxy) -phenyl] propane, 16 parts of isophthalic acid, 16 parts of terephthalic acid, 0.6 part of maleic anhydride, 0.0 parts of dibutyltin oxide
Six parts were charged into a flask, and the reaction was continued at 230 ° C. for 24 hours under a nitrogen atmosphere and taken out.

The weight average molecular weight of the obtained polyester resin is 7,600
(This polyester resin is hereinafter referred to as “resin A”.) 50 parts of this polyester resin and 50 parts of xylene were charged into a flask and dissolved. Raise the temperature until xylenes reflux,
Under refluxing xylene, a solution prepared by dissolving 0.4 parts of azobisisobutyronitrile in 13 parts of styrene and 0.3 part of diethylaminoethyl methacrylate was added dropwise in about 30 minutes under a nitrogen atmosphere. After the dropwise addition, the temperature was maintained for 3 hours, and xylol was distilled under reduced pressure, and then the resin was taken out. (This vinyl-modified polyester resin is hereinafter referred to as “resin B”.) Resin A has a weight average molecular weight of 12,0.
The melt viscosity at 00 and 100 ° C. was 5 × 10 ⁴ poise, and the glass transition temperature was 62 ° C.

However, the melt viscosity was measured by Shimadzu Flow Tester CFT-5.
It is a value measured using 00 as a condition of a nozzle diameter of 1 mm, a nozzle length / mm, a load of 30 kg, and a heating rate of 3 ° C./min.

(Example 1) <Production of Toner> 97 parts of resin A produced in the resin production example and 3 parts of the naphthol pigment in the present invention were mixed in a ball mill, kneaded with a heating roll, cooled, and then jet milled. The toner was finely pulverized and classified to prepare a toner having an average particle size of 11 μm (hereinafter, referred to as “toner (1)).

<Adjustment of Developer> A developer was prepared by frictionally mixing 4 parts of the toner (1) and 96 parts of a carrier “Ferrite Carrier F-150” manufactured by Powder Tech.

<Measurement of charge amount> The adjusted developer is subjected to three different environments of high temperature and high quality (40 ° C, 90% RH), normal temperature and normal humidity (20 ° C, 50% RH), and low temperature and low humidity (10 ° C, 20RH). After leaving for 1 hour, the charge amount was measured immediately after that.

The charge amount variation width provided by environmental changes was calculated and evaluated. The results are shown in Table 1.

<Reproducibility of red> Disazo yellow pigment "Symuler Fast Yellow 5GP" manufactured by Dainippon Ink and Chemicals, Inc. as a yellow pigment, and copper phthalocyanine pigment "Fastogen Blue GNPT" manufactured by Dainippon Ink and Chemicals, Inc. as a cyan pigment. A yellow developer and a cyan developer were prepared in the same manner as in <Preparation of Toner> and <Adjustment of Developer>, except for using.

Using a copier "BD-3504" manufactured by Toshiba Corp., a full-color copy was performed by superimposing three colors together with the developer adjusted using the toner (1), and red reproducibility was visually evaluated. The results are shown in Table 1.

<Hue and color characteristics> In <Red Reproducibility>, a full-color copy and a red copy are used as a color difference meter “Minolta CM-” manufactured by Minolta Camera Co., Ltd.
Using "1000 spectral colorimetry", lightness (indicated by "L ^* " in Table 1), hue (indicated by "a ^* , b ^* " in Table 1), and saturation ("a ^* " in Table 1) , b ^* ”) were measured. Table 1 shows the results.
It was shown to. Note that L ^* means a lightness coordinate axis in color tone coordinates, a ^* is a red-green coordinate axis of hue / saturation coordinates, and b ^*
* Means the yellow-blue coordinate axes of the hue / saturation coordinates, respectively.

<Evaluation of Coloring Power> The density of an image portion of an image portion having a toner adhesion amount of 1 mg / cm ² was measured with a Macbeth reflection densitometer on a printed material developed with the developer adjusted using the toner (1). The results are shown in Table 1.

(Example 2) <Preparation of Toner> 94 parts of resin B produced in the resin production example, 3 parts of naphthol-based pigment in the present invention, and “Bontron E-81” as a negative charge control agent (Orient Chemical Industry Co., Ltd.) )
From three parts, a toner (hereinafter, referred to as “toner (2)”) was produced in the same manner as in (Example 1).

<Adjustment of Developer> A developer was adjusted in the same manner as in (Example 1) except that the toner (2) was used.

<Measurement of Charge Amount> For the adjusted developer, charge amounts of three kinds of developers were measured in the same manner as in (Example 1), and a charge amount fluctuation width accompanying environmental change was calculated and evaluated. The results are shown in Table 1.

<Red reproducibility> Disazo yellow pigment "Symuler Fast Yellow 5GP" manufactured by Dainippon Ink and Chemicals, Inc. as a yellow pigment, or copper phthalocyanine pigment "Fastogen Blue GNPT" manufactured by Dainippon Ink and Chemicals, Inc. as a cyan pigment. A yellow developer and a cyan developer were prepared in the same manner as in <Preparation of Toner> and <Adjustment of Developer>, except for using.

A full color copy was performed by superimposing three colors using a copying machine “BD-3504” manufactured by Toshiba Corporation with the developer adjusted using the toner (2), and red reproducibility was visually evaluated. The results are shown in Table 1.

<Hue and hue characteristics> Lightness, hue and chroma were measured in the same manner as in (Example 1). The results are shown in Table 1.

<Evaluation of coloring power> The image density of the image area where the toner adhesion amount was 1 mg / cm ² was measured with a Macbeth reflection densitometer on the printed matter developed with the developer adjusted using the toner (2). The results are shown in Table 1.

(Example 3) <Preparation of toner> 95 parts of an epoxy resin “Epiclon-450” manufactured by Dainippon Ink and Chemicals, 3 parts of a naphthol pigment of the present invention, and “Bontron E- 81 "
(From Orient Chemical Co., Ltd.) from 2 parts (Example 1)
A toner (hereinafter, referred to as “toner (3)”) was prepared in the same manner as described above.

<Adjustment of Developer> The charge amounts of the three types of developers were measured in the same manner as in (Example 1) except that the toner (3) was used, and the charge amount fluctuation width that was subjected to environmental changes was calculated and evaluated. did. The results are shown in Table 1.

<Red reproducibility> Disazo yellow pigment "Symuler Fast Yellow 5GF" manufactured by Dainippon Ink and Chemicals, Ltd. as a yellow pigment, and copper phthalocyanine pigment "Fastogen Blue GNPT" manufactured by Dainippon Ink and Chemicals, Ltd. as a cyan pigment. A yellow developer and a cyan developer were prepared in the same manner as in <Preparation of Toner> and <Adjustment of Developer>, except for using.

Using a copier "BD-3504" manufactured by Toshiba Corp., a full-color copy was performed by superimposing three colors together with the developer adjusted using the toner (3), and the red reproducibility was visually evaluated.
The results are shown in Table 1.

<Hue and hue characteristics> Lightness, hue and chroma were measured in the same manner as in (Example 1). The results are shown in Table 1.

<Evaluation of coloring power> The image density of an image portion having a toner adhesion amount of 1 mg / cm ² was measured with a Macbeth reflection densitometer on a printed material developed with the developer adjusted using the toner (3). The results are shown in Table 1.

(Comparative Example 1) <Production of Toner> A toner (hereinafter referred to as “toner (4)” was prepared in the same manner as in (Example 1) from 97 parts of resin A produced in Resin Production Example and 3 parts of an azo lake pigment represented by the following structural formula. ) Was prepared.

<Adjustment of Developer> A developer was prepared in the same manner as in (Example 1) except that the toner (4) was used.

<Measurement of Charge Amount> For the adjusted developer, the charge amounts of three kinds of developers were measured in the same manner as in (Example 1), and the charge amount fluctuation width subjected to environmental changes was calculated and evaluated. The results are shown in Table 1.

<Red reproducibility> Disazo yellow pigment "Symuler Fast Yellow 5GF" manufactured by Dainippon Ink and Chemicals, Ltd. as a yellow pigment, and copper phthalocyanine pigment "Fastogen Blue GNPT" manufactured by Dainippon Ink and Chemicals, Ltd. as a cyan pigment. A yellow developer and a cyan developer were prepared in the same manner as in <Preparation of Toner> and <Adjustment of Developer>, except for using.

Using a copier "BD-3504" manufactured by Toshiba Corp., a full-color copy was performed by superimposing three colors together with the developer adjusted using the toner (4), and the red reproducibility was visually evaluated. The results are shown in Table 1.

<Hue and hue characteristics> Lightness, hue and chroma were measured in the same manner as in (Example 1). The results are shown in Table 1.

<Evaluation of coloring power> The image density of an image portion having a toner adhesion amount of 1 mg / cm ² was measured with a Macbeth reflection densitometer on a printed material developed with the developer adjusted using the toner (4). The results are shown in Table 1.

(Comparative Example 2) <Production of Toner> Resin B94 produced in Resin Production Example, JP-A-51-24234
Quinacridone pigment Pigment Red 12
2 ”, 3 parts of“ Bontron E-81 ”(manufactured by Orient Chemical Industry Co., Ltd.) as a negative charge control agent, and 3 parts of toner (hereinafter“ toner (5) ”) in the same manner as in Example 1. ) Was prepared.

<Adjustment of Developer> A developer was adjusted in the same manner as in (Example 1) except that the toner (5) was used.

<Measurement of Charge Amount> For the adjusted developer, the charge amounts of three kinds of developers were measured in the same manner as in (Example 1), and the charge amount fluctuation width subjected to environmental changes was calculated and evaluated. The results are shown in Table 1.

<Red reproducibility> Disazo yellow pigment "Symuler Fast Yellow 5GF" manufactured by Dainippon Ink and Chemicals, Ltd. as a yellow pigment, and copper phthalocyanine pigment "Fastogen Blue GNPT" manufactured by Dainippon Ink and Chemicals, Ltd. as a cyan pigment. A yellow developer and a cyan developer were prepared in the same manner as in <Preparation of Toner> and <Adjustment of Developer>, except for using.

A full color copy was performed by superimposing three colors using a copying machine “BD-3504” manufactured by Toshiba Corporation with the developer adjusted using the toner (5), and the red reproducibility was visually evaluated. 1 is shown.

<Hue and hue characteristics> Lightness, hue and chroma were measured in the same manner as in (Example 1). The results are shown in Table 1.

<Evaluation of coloring power> The image density of the image area where the toner adhesion amount was 1 mg / cm ² was measured with a Macbeth reflection densitometer on the printed matter developed with the developer adjusted using the toner (5). The results are shown in Table 1.

(In the table, LL is the environmental condition of 10 ° C temperature and 20% humidity, MM is the temperature of 20%
Environmental conditions at 50 ° C and humidity of 50%, HH are environmental conditions at temperature of 40 ° C and humidity of 90%, and environmental differences are values obtained by subtracting LL or HH. (Effects of the Invention) According to the present invention, it is possible to obtain a stable image quality by suppressing a change in the charge amount of the toner to a small degree with respect to an environmental change from a low temperature and a low humidity to a high temperature and a high humidity, and a large coloring power. Particularly for full-color applications, it is possible to obtain an image quality with good red reproducibility.

Claims (1)

(57) [Claims] 1. A magenta toner for developing a full-color electrostatic image using a naphthol-based organic pigment as a coloring component, wherein the naphthol-based organic pigment is represented by the following structural formula. Structural formula: