JPH1152625A - Dry magenta toner for electrophotography - Google Patents

Abstract

(57) [Problem] To provide a dry magenta toner for electrophotography which satisfies all of color tone, coloring degree, light fastness, heat resistance, triboelectric charging property, carrier contamination prevention and transparency. SOLUTION: In a dry magenta toner for electrophotography containing a binder resin and a colorant as main components, C.I. I. Pigment Red 48: 2 and / or
Or C.I. I. Pigment Red 48: 3, and a red pigment having a b * value of −5 or less in the L * a * b * color system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner used as a developer in an electrophotographic copying machine, a laser printer, a facsimile, and the like, and relates to a magenta electrophotographic dry toner suitable for forming a color image. It is about.

[0002]

2. Description of the Related Art In an electrophotographic system in which a visible image is formed by developing an electric latent image with a developer, an electric latent image is formed on a photoconductor made of a photoconductive substance, and then the latent image is formed into a toner. The toner image is developed by developing with a developer containing, and if necessary, the toner image is transferred to paper or the like, and then fixed by heating, pressing, or the like to obtain a fixed image. Also, in order to obtain full-color images by electrophotography,
For example, light from a document is exposed on a photoreceptor through a color separation filter, or an image read by a scanner is written and exposed with a laser to form an electric latent image of a yellow image portion on the photoreceptor, and the A yellow toner image obtained by developing the electric latent image with yellow toner is transferred to a transfer material such as paper, and then magenta toner image and cyan toner image obtained using magenta toner and cyan toner in the same process. May be sequentially superimposed on the yellow toner image.

Conventionally, in an electrophotographic system, a toner obtained by kneading a pigment as a colorant, a charge controlling agent, and the like together with a thermoplastic resin and pulverizing the mixture is generally used. In this case, particularly in a magenta toner, since a pigment as a colorant is hardly dispersed, a problem that dispersed particles scatter light and lower the transparency of the toner is likely to occur. For this reason,
The color reproducibility of a multicolor image formed by superimposing a plurality of color toners is poor, and the projected image of an image formed by transferring and fixing to a transparent sheet for an overhead projector (OHP) is dark and has low saturation. Had the disadvantage of becoming Further, the magenta toner has a drawback that the degree of coloring is low or the color tone does not become an ideal magenta color.

To solve these problems, improvement of pigments and dyes mainly used for magenta toners and improvement by using pigments and dyes in combination have been proposed. For example, Japanese Unexamined Patent Publication No.
No. 7 discloses that a clear magenta toner can be obtained by using a quinacridone pigment and a xanthene dye in combination, light resistance is improved, and there is no dyeing on a silicone rubber roller. Further, Japanese Patent Laid-Open No. 2-139
No. 68 discloses that a clear color image can be obtained without contaminating a copying machine by using a quinacridone pigment and a methine pigment in combination.

[0005] However, even with these proposals,
1) excellent spectral reflection characteristics for color reproduction and having a clear magenta color; 2) good dispersibility of the colorant in the resin and high coloring; 3) good light fastness; ) It has heat resistance that does not cause dyeing deterioration of the surface of the heat-fixing roller made of silicon rubber or the like. 5) It has stable triboelectric charging characteristics in the environment. 6) Prevents carrier contamination of toner, so-called spent phenomenon.
No magenta toner for electrophotography has been obtained which sufficiently satisfies all the required characteristics such as good transparency.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve such problems and to satisfy all of color tone, coloring degree, light resistance, heat resistance, triboelectric charging characteristics, carrier contamination prevention and transparency. To provide a magenta toner for electrophotography.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to provide a dry magenta toner for electrophotography containing a binder resin and a colorant as main components. I. Pi
gment Red 48: 2 and / or C.I. I. Pig
Ment Red 48: 3 red pigment and L
This is achieved by a dry magenta toner for electrophotography, comprising a red pigment having a b * value of −5 or less in a * a * b * color system.

According to the present invention, it is possible to obtain a dry magenta toner for electrophotography which satisfies all of the color tone, coloring degree, light fastness and transparency, and has good heat resistance to a heat fixing roller and the like. It is possible to obtain a dry magenta toner for electrophotography which has stable triboelectrification characteristics in the environment and can prevent carrier contamination, so-called spent phenomenon.

In the present invention, C.I. I. Pigment
Red 48: 2 and / or C.I. I. Pigment
Red 48: 3 red pigment and L * a * b
This is because the dry magenta toner for electrophotography having the above characteristics can be obtained by using a red pigment having a b * value of -5 or less in the * color system in combination. That is, according to the study of the present inventors, when the dispersion of the colorant in the binder resin is insufficient, the degree of coloring of the obtained toner is low and the transparency is inferior. The reproducibility of the color tone when the image is formed is significantly reduced, and it is preferable to sufficiently disperse the colorant in the binder resin in order to improve the degree of coloration and transparency of the toner. In particular, it was found that the average dispersion diameter of the colorant in the binder resin is preferably 1 μm or less.

C. I. Pigment Red 48:
2 and / or C.I. I. Pigment Red 48:
The red pigment classified into Class 3 is excellent in dispersibility in the binder resin, and the obtained toner has good coloring degree and transparency, but the color tone shifts toward the yellow direction and forms an image such as a full color. There is a problem in the reproducibility of the color tone in the case where
By using a red pigment having a b * value of −5 or less in the * b * color system in combination, a good color tone as a magenta color for a full-color image can be exhibited. Further, since the dispersibility of the red pigment in the binder resin is excellent, the average dispersion diameter of the red pigment in the binder resin is 1 μm.
It is possible to obtain the following. By doing so, it is possible to obtain a dry magenta toner for electrophotography having particularly good coloring degree and transparency.

Further, the dry magenta toner for electrophotography has not only color tone, coloring degree and transparency but also light resistance,
It has good heat resistance against a heat fixing roller and the like, has a stable triboelectric charging characteristic in an environment, and is excellent in preventing carrier contamination, a so-called spent phenomenon.

In the dry magenta toner for electrophotography of the present invention, C.I. I. Pigment Red 48: 2 and / or C.I. I. Pigment Red 48: 3, the content of the red pigment is preferably larger than the content of the red pigment having the b * value of −5 or less in the L * a * b * color system, and L * a * b * The b * value in the color system is-
The content of the red pigment of 5 or less is 2 to 30 w
It is particularly preferable to set it to t%. If it is less than 2% by weight, the effect of color tone correction will be insufficient, and if it exceeds 30% by weight, C.I. I. Pigment Red 48: 2 and / or
Or C.I. I. Pigment Red 48: 3 is particularly preferable because excellent properties such as dispersibility, coloring degree, and transparency of the red pigment classified into Pigment Red 48: 3 are not sufficiently exhibited.

The b * value in the L * a * b * color system is -5.
Representative examples of the following red pigments include C.I. I. Pigme
nt Red 122, C.I. I. Pigment Re
d150, C.I. I. Pigment Red 238,
C. I. Pigment Red 57: 1, C.I. I. P
Pigment Red 147, C.I. I. Pigmen
t Red 184, C.I. I. Pigment Vio
let 19 red pigment.

The L * a * b * value in the present invention is a value defined as a CIE LAB value at a portion where the magenta density of the magenta toner image transferred to the transfer paper is 1.0 ± 0.1. B in the L * a * b * color system
* Specifically, the value can be easily measured by using, for example, X-Rite 938 spectral colorimetric densitometer manufactured by X-Rite.

Further, in the dry magenta toner for electrophotography according to the present invention, in order to obtain excellent color reproducibility in an image such as a full-color image and to obtain a bright and high-saturation image when projecting using a transparent sheet such as an OHP, It is more preferable that the haze degree as an index is 20% or less.

The b * value in the L * a * b * color system is -5.
By mixing the following red pigments at a ratio of 2 to 30 wt% with respect to all the pigments, the haze degree as an index of transparency can be reduced to 20% or less relatively easily as compared with the case where a conventional magenta pigment is used. Can be adjusted. Further, other materials added to the electrophotographic dry magenta toner in addition to the binder resin and the colorant as the main components, for example, a charge control agent,
By appropriately selecting a release agent, other additives, and the like, the haze can be relatively easily reduced to 20% or less as compared with the case where a conventional magenta pigment is used.

The content of the colorant in the dry magenta toner for electrophotography of the present invention is usually preferably from 1 to 25% by weight, particularly preferably from 2 to 20% by weight, based on the binder resin. The average dispersion diameter of the colorant in the binder resin is 1
μm or less is particularly preferable, whereby a dry magenta toner for electrophotography having a high degree of coloring even when the colorant concentration in the toner is low, and having excellent light transmittance and excellent transparency can be obtained. By using a toner, an image having excellent color tone reproducibility can be formed.

The average dispersion diameter of the colorant in the binder resin is:
For example, after the binder resin and the colorant are kneaded, they are rolled and cooled, and then cooled and thinned by a thin film cutting device (Microtome MT-600).
0, R. M. C. Inc. Sliced to a thickness of 1000 mm using a transmission electron microscope (JSM-880,
Observation with JEOL Ltd.) and an image analyzer (LUZEX50) via a scanning converter unit
(Manufactured by Nireco Co., Ltd.).

As the binder resin in the dry magenta toner for electrophotography of the present invention, conventionally known resins can be used alone or in combination of two or more, or those modified or polymerized can be used as appropriate. Specific examples of the binder resin include, for example, polystyrene, polychlorostyrene, polyvinyl toluene styrene-vinyl toluene copolymer, styrene-vinyl naphthalene copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, Styrene-based polymers and styrene-based copolymers such as styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic acid ester copolymer, acrylic resin, vinyl resin, ethylene resin, polyamide resin , A polyester resin, a phenol resin, a silicon resin, a polyamide resin, a xylene resin, an epoxy resin, a terpene resin, a rosin and a modified rosin.

In order to obtain a dry magenta toner having higher transparency particularly suitable for forming a full-color image, at least three substances of a bisphenol A type epoxy resin, a bisphenol and an alkylene oxide-modified epoxy resin are used as binder resins. It is preferable to use a polyol type resin having the above.

In the dry magenta toner for electrophotography of the present invention, additives such as various charge control agents, fluororesins such as vinylidene fluoride fine powder, fatty acid metal salts such as zinc stearate, zinc oxide, etc. Metal oxides, silica, aluminum oxides, titanium oxides, and the like can be added. When the main purpose is to impart higher fluidity to the colored particles mainly composed of a binder resin and a colorant, the average primary particle size is 0.001 to 1 μm.
m, preferably 0.005-0.1 μm, of hydrophobically treated silica or rutile-type fine particle titanium oxide is added, and it is particularly preferred to add organosilane surface-treated silica or titanium oxide. The amount of the silica or titanium oxide to be added is usually from 0.1 to 5% by weight, preferably from 0.2 to 2% by weight, based on the colored particles.
Is preferred.

The charge control agent is a substantially colorless or white compound, and is preferably a substance which does not impair the color tone of the pigment used in combination, especially in the case of a full-color toner, because transparency can be improved. Examples of such charge controlling agents include, for example, organic acids such as salicylic acid and derivatives thereof, metal salts such as zinc and aluminum, fluorinated quaternary ammonium salt compounds, calixarene compounds, and polymers having functional groups such as sulfonic acid. Compounds of the type can be exemplified.

The dry magenta toner for electrophotography of the present invention can be used as a two-component dry toner or a one-component dry toner. When used as a two-component dry toner, the carrier used as a mixture is glass,
Powder having a particle size of about 30 to 1000 μm containing iron, ferrite, nickel, zircon, silica, or the like as a main component, or a styrene-acrylic resin, a silicon resin, a polyamide resin, or a polyvinylidene fluoride based on the powder as a core material. Those coated with a resin or the like are exemplified.

When a magnetic powder is added to the one-component dry toner, the magnetic powder may be, for example, a ferromagnetic material such as iron, cobalt, or nickel, or an alloy or compound such as magnetite, hematite, or ferrite. Can be used, but is preferably used within a range that does not impair the transparency of the toner.

[0025]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto.

Example 1 92 parts by weight of a polyester resin (polycondensate having a glass transition point of about 58 ° C. and a softening point of about 109 ° C.), 2 parts by weight of a negative charge control agent (a zinc salt of a salicylic acid compound), and azo lake Magenta pigment (CI Pigment Red 48:
2) 4 parts by weight of a quinacridone magenta pigment (C.I.
I. Pigment Red 122) is mixed, melt-kneaded by a twin-screw kneader, solidified by cooling, coarsely pulverized by a hammer mill, and pulverized with a 2 mm pass (M1).
1) was obtained. Next, this pulverized material (M11) was added to IDS-2.
A finely pulverized product (M21) was obtained by pulverizing with a type jet pulverizer (manufactured by Nippon Pneumatic Industries, Ltd.) so that the volume average particle diameter became about 7.0 μm. Then, the finely pulverized product (M21) is finely classified by an airflow classifier, and the colored particles (M31) having a volume average particle size of about 7.6 μm and a number content of fine powder of 5 μm or less of about 18% (M31) I got 10 g (0.5 wt%) of surface-treated silica was added to 2 kg of the colored particles (M31), and then mixed with a 20-liter Henschel mixer to obtain a dry magenta toner for electrophotography (M41).

Example 2 The quinacridone magenta pigment (C.I.
I. Pigment Red 122) is a monoazo-based magenta pigment (CI Pigment Red 184).
A pulverized product (M12) having a 2 mm pass was obtained in the same manner as in Example 1, except that the pulverized product (M12) was pulverized and classified in the same manner as in Example 1, and the volume average particle diameter was about 7 μm. .5
μm, and the number content of fine powder of 5 μm or less is about 18%
Colored particles were obtained. Then, in the same manner as in Example 1, surface-treated silica was added to the colored particles and mixed to obtain a dry magenta toner for electrophotography (M42).

Example 3 The azo lake type magenta pigment (CI Pigment Red) was prepared by changing the ratio of the magenta pigment in Example 1.
48: 2) The volume average particle diameter is 7.3 to 7.7 μm in the same manner as in Example 1 except that 5 parts by weight and 1 part by weight of a quinacridone-based magenta pigment (CI Pigment Red 122) are used. Colored particles having a number content of fine powder of 5 μm or less of 16 to 19% were obtained. Example 1
In the same manner as described above, surface-treated silica is added to the colored particles and mixed, and a dry magenta toner for electrophotography (M4
3) was obtained.

Example 4 Polyol resin (bis-A-type diglycidyl ether, diglycidyl compound of bisphenol A-type propylene oxide adduct, bisphenol F and p-cumylphenol) having a glass transition point of about 60
C., 92 parts by weight of a condensation polymer having a softening point of about 110.degree. C., 2 parts by weight of a negative charge control agent (a zinc salt of a salicylic acid compound), and an azo lake magenta pigment (CI Pigment R)
ed 48: 2) The volume average particle diameter was about 7.5 μm, and 5 μm or less in the same manner as in Example 1 except that 5 parts by weight and 1 part by weight of a quinacridone-based magenta pigment (CI Pigment Red 122) were used. The colored particles having a number content of fine powder of about 18% were obtained. Then, in the same manner as in Example 1, surface-treated silica was added to the colored particles and mixed to obtain a dry magenta toner for electrophotography (M44).

Example 5 92 parts by weight of a styrene-acrylic acid alkyl ester resin (glass transition point: about 58 ° C., softening point: about 112 ° C.), 2 parts by weight of a negative charge control agent (zinc salt of a salicylic acid compound), azo lake Magenta pigment (CI Pigment R)
ed 48: 2) 4 parts by weight and a quinacridone-based magenta pigment (CI Pigment Red 122) 1
A pulverized product (M15) having a 2 mm pass was obtained in the same manner as in Example 1 except that the parts by weight were used, and then the pulverized product (M15) was pulverized and classified in the same manner as in Example 1 to obtain a volume average particle diameter. Colored particles having a particle content of 7.4 to 7.7 μm and a number content of fine powder of 5 μm or less of 15 to 19% were obtained. Example 1
In the same manner as described above, the fluorinated silane surface-treated silica was added to the colored particles and mixed to obtain a dry magenta toner for electrophotography (M45).

Example 6 A dry magenta toner for electrophotography was obtained in the same manner as in Example 4, except that a chromium complex of an azo compound was used in place of the zinc salt of the salicylic acid compound as the charge controlling agent. .

Comparative Example 1 In Example 1, an azo lake type magenta pigment (C.I.
I. Pigment Red 48: 2) (4 parts by weight) and a quinacridone-based magenta pigment (CI Pigmen)
t Red 122) 2 parts by weight of an azo lake type magenta pigment (CI Pigment Red 4)
A dry magenta toner for electrophotography was obtained in the same manner as in Example 1 except that 8: 2) alone was used in an amount of 6 parts by weight.

Comparative Example 2 In Example 1, a quinacridone-based magenta pigment (C.I.
I. Pigment Red 122) and a monoazo magenta pigment (CI Pigment Red 14).
A dry magenta toner for electrophotography was obtained in the same manner as in Example 1 except that 6) was used. The L * of the monoazo magenta pigment (CI Pigment Red 146)
The b * value in the a * b * color system is -1.95.

Comparative Example 3 In Example 2, an azo lake type magenta pigment (C.I.
I. Pigment Red 48: 2) and 4 parts by weight of a monoazo magenta pigment (CI Pigment).
Red 184) A dry magenta toner for electrophotography was obtained in the same manner as in Example 2 except that 6 parts by weight of a monoazo magenta pigment (CI Pigment Red 184) was used alone instead of 2 parts by weight.

5 parts by weight of the dry magenta toner for electrophotography of each of the examples and comparative examples obtained above were mixed with 95 parts by weight of a silicon resin-coated carrier having a particle size of about 80 μm under stirring and mixed. Each two-component developer containing a dry magenta toner was prepared, and 10,000 copies were continuously copied using a full-color electrophotographic copying machine (Pretail 550, manufactured by Ricoh Co., Ltd.) using each two-component developer. As described above, 1) color tone (brightness), 2) coloring degree, 3) light resistance, 4) heat resistance to a heat fixing roller, 5) stability over time of triboelectric charging in a copying machine, and 6) carrier spent development. An evaluation was performed. Table 1 shows the results.

(1) Color Tone (Vividness) JAPAN COLOR Based on the difference between the magenta color tone (saturation) and the color tone (saturation) of a magenta image, the color tone (saturation) was evaluated according to the following criteria. A: Excellent (difference is less than 1). ：: good (the difference is 1 or more and less than 3). Δ: somewhat good (difference of 3 or more and less than 6).

(2) Degree of Coloring The image density was measured with an X-Rite 938 spectrocolorimetric densitometer, and the degree of coloring was evaluated by 、: excellent, ：: good, Δ: slightly good, ×: poor.

(3) Light fastness The image was irradiated with a XENONTESTER XW-150 (manufactured by Shimadzu Corporation) at 10,000 lux for 24 hours, and the light fastness was evaluated according to the following criteria. A: Almost no change. ：: slightly changed. Δ: slightly changed. X: It changes considerably.

(4) Heat Resistance to Heat Fixing Roller (Fixing Roller Contamination) The surface dyeing of the heat fixing roller after 10,000 continuous copies was observed, and the heat resistance to the heat fixing roller was evaluated according to the following criteria. A: Almost no surface staining. ：: slight surface staining Δ: Some surface dyeing occurs. X: The surface is considerably dyed.

(5) Stability over time of frictional charging in the copying machine The charging potential (-μC / g) of the initial developer was measured by frictional charging using a ball mill type stirring device.
Next, the charging potential of the developer after the continuous copying of 10,000 sheets was measured. The smaller the measured value is, the more excellent the stability over time of the triboelectric charging is.

(6) Carrier Spent Development The developer after continuous copying of 10,000 sheets was observed with a Wick-integrating sphere turbidimeter, and carrier spent development was evaluated according to the following criteria. A: Almost no turbidity. ：: slightly cloudy Δ: slightly cloudy X: considerably cloudy

Further, the haze degree (%) of a sample obtained by fixing each of the dry magenta toners for electrophotography to a commercially available OHP sheet at an adhesion amount of about 1 mg / cm 2 was measured using a haze degree measuring device ( HGM manufactured by Suga Test Machine Co., Ltd.
-2DP). Table 1 shows the results. The lower the value of the haze (%), the better the transparency.

In the above Examples and Comparative Examples, the binder resin, the colorant, and the negative charge system controlling agent were melt-kneaded by a twin-screw kneader, cooled and solidified, and then rolled. R.M.C.Inc.), And sliced to a thickness of 1000 mm.
Observation with SM-880 (manufactured by JEOL Ltd.), and further through a scanning converter unit, an image analysis device LU.
By measuring the particle size with ZEX500 (manufactured by Nireco), the average dispersion diameter (μm) of the colorant in the binder resin was obtained. Table 1 shows the results.

[0044]

[Table 1]

As is clear from Table 1, when the dry magenta toner for electrophotography of the example was used, it was excellent in color tone, coloring degree, light resistance, heat resistance to a heat fixing roller and prevention of carrier spent development. It also has excellent stability over time and the haze (transparency) of triboelectric charging in a copying machine, or shows a level that causes no practical problem.

[0046]

According to the present invention, the color tone, the degree of coloring, the light resistance and the transparency are excellent, the heat resistance to a heat fixing roller and the like is good, the frictional charging characteristics are stable in the environment, and the carrier is excellent. It is possible to obtain a dry magenta toner for electrophotography which can prevent the so-called spent phenomenon. Further, according to the present invention, by setting the average dispersion diameter of the colorant in the binder resin to 1 μm or less, the colorant has a high degree of coloration even at a low colorant concentration, and has excellent light transmittance.
A dry magenta toner for electrophotography, which is excellent in color tone reproducibility and can form an image, can be obtained.

Claims (7)

[Claims] 1. An electrophotographic dry magenta toner containing a binder resin and a colorant as main components, wherein C.I. I. Pigment Red 48: 2 and / or
Or C.I. I. Pigment Red 48: 3. A dry magenta toner for electrophotography, comprising a red pigment having a b * value of -5 or less in an L * a * b * color system. 2. The b * value in the L * a * b * color system is-
The content of the red pigment of 5 or less is 2 to 30 w
2. The dry magenta toner for electrophotography according to claim 1, wherein the toner is t%. 3. The b * value in the L * a * b * color system is-
5 or less red pigments are C.I. I. Pigment Red
122, C.I. I. Pigment Red 150, C.I.
I. Pigment Red 238, C.I. I. Pig
mentRed 147, C.I. I. Pigment R
ed 57: 1, C.I. I. Pigment Red
184, and C.I. I. Pigment Violet
3. The dry magenta toner for electrophotography according to claim 1, wherein the toner is a pigment selected from the group consisting of: 4. The dry magenta toner for electrophotography according to claim 1, wherein the haze is 20% or less. 5. The binder resin according to claim 1, wherein the binder resin is a polyol type resin having at least three substances of bisphenol A type epoxy resin, bisphenols and alkylene oxide modified resin as constituent elements.
3. The dry magenta toner for electrophotography according to 3 or 4. 6. The dry magenta toner for electrophotography according to claim 1, further comprising a substantially colorless or white compound as a charge control agent. 7. The colorant average dispersion diameter in the binder resin is 1 μm.
The following is characterized in that:
The dry magenta toner for electrophotography according to 4, 5 or 6.