JP3458166B2 - Magenta toner for developing electrostatic latent images - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel toner for developing an electrostatic charge image in electrophotography, electrostatic recording, etc., and particularly to a magenta toner suitable for color electrophotography.

[0002]

2. Description of the Related Art An electrophotographic system for developing a visible image by developing an electric latent image with a developer forms an electric latent image on a photoconductor made of a photoconductive material and then develops the latent image with a developer. After development, the image is transferred to a paper or the like with a developer, if necessary, and then fixed by heating, pressing, or the like to obtain a visible image. In particular, in order to obtain a multicolor image of color, the original is exposed using a color separation filter, or the image read by a scanner is written and exposed by a laser, and the above steps are performed using a yellow, magenta, and cyan color developer. To form a color image by superposing the toner images. A conventional magenta toner for electrophotography is obtained by kneading and pulverizing a pigment such as quinacridone and a charge control agent together with a thermoplastic resin. In such a magenta toner, the pigment that is the colorant is dispersed as particles in the toner,
The dispersed particles scatter light and reduce the transparency of the toner. Therefore, an image in which a plurality of color toners are superposed has poor color reproducibility, and an image in which light is projected by being transferred and fixed onto a transparent sheet such as OHP has a drawback that it is dark and has low saturation. ing. On the other hand, JP-A-3-23465 and JP-A-4-3172 have proposed that an azo dye is used instead of a pigment, and JP-A-2-511165, JP-A-2-108068, JP-A-2-207272 and the like. Has a proposal using an anthraquinone dye. Since these dyes can be dispersed in the toner at a molecular size, the resulting image has excellent transparency, but on the other hand,
It was difficult to obtain the same excellent magenta color tone as when using a pigment such as quinacridone.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks, that is, in a magenta toner using a conventional dye, it has a spectral reflection characteristic for compensating its color tone and is transparent. The present invention provides a good magenta toner for electrophotography.

[0004]

The present invention SUMMARY OF], in the toner for developing an electrostatic latent image as a main component a thermoplastic resin and a dye,
The absorption maximum of the spectral absorption spectrum of the dye is 500 nm ~
Dye (D1) at 560 nm and 530 nm-550
absorption peaks at nm and 560 nm to 590 nm
And the maximum absorbance (Ema ) at 480 nm to 580 nm of the spectroscopic absorption spectrum.
x) and the minimum absorbance at 480 nm to 580 nm (Em
in) ratio (Emin / Emax) is 0.3 to 1.0
Der Rutotomoni, Emin provide magenta toner for developing an electrostatic latent image, wherein it is 0.4 to 2.0 in terms of per weight of the toner ^{[l ·} g ^{-1 · cm} -1] To do. In a preferred embodiment of the present invention, the D2 dye is an anthraquinone dye.

That is, in the present invention, the problem of poor transparency seen in the conventional pigment-based coloring agent is solved by using the dye-based coloring agent, and the magenta color tone which cannot be solved by the dye-based coloring agent is realized. , Revealing the optimal properties in the absorption spectrum of the toner or dye,
And it was made possible by realizing it.

As the dye of the present invention, any of known water-soluble dyes, oil-soluble dyes and disperse dyes can be used, and a dye capable of being dyed is selected depending on the type of resin used in the toner. In particular, oil-soluble dyes and disperse dyes are preferable because they do not cause image bleeding due to the attachment of water droplets.

In order to obtain a good magenta color tone, it must have a sufficient color tone with an appropriate dye concentration. Specifically, it is preferable that the minimum absorbance in the wavelength range of 480 nm to 580 nm is 0.4 to 2.0 in terms of the weight of the toner. If the minimum absorbance per toner weight is less than 0.4, a color image having a satisfactory density cannot be obtained. Further, if the minimum absorbance per weight of the toner is larger than 2.0, the color balance among cyan, yellow and black is lost, which is not preferable. It is not preferable to increase or decrease the addition amount of the dye in order to adjust the image density, because the thermal characteristics and the like are adversely affected.

The absorbance per toner weight is a value obtained by dividing the absorbance measured by a spectral absorption spectrum in an acetone solvent by the toner concentration. The measurement sample was prepared by precisely weighing the toner, dissolving it in acetone, and then adjusting the concentration with a measuring flask or the like.

Further, the magenta color tone has a strong absorption over the entire range of 480 nm to 580 nm in the spectral absorption spectrum, and the smaller the absorption in the wavelength range other than 480 nm to 580 nm, the more preferable. That is, 480 nm to 580
The ratio (Emin / Emax) of the maximum absorbance (Emax) and the minimum absorbance (Emin) in nm is 0.3 to
When it is 1.0, a satisfactory color tone is obtained. Emin / E
When the max is 0.3 or less, the deviation of the absorbance at each wavelength is large, and the color tone is strong blue or yellowish, and a satisfactory magenta image cannot be obtained.

A good magenta toner having excellent spectral reflection characteristics has an absorption maximum value of a spectral absorption spectrum of 500 nm or more.
D1 dye at 560nm and 530nm-550nm
And a D2 dye having absorption peaks at two wavelengths of 560 nm to 590 nm in combination. D1 dye,
One type of D2 dye may be used, but two or more types of each dye may be used in combination. D
The ratio of 1 dye and D2 dye to be used depends on the spectral characteristics of each dye, but preferably D1: D2 =
3: 1 to 1: 5, and more preferably D1: D2.
= 2: 1 to 1: 3.

The D1 and D2 dyes are used in such amounts that the total amount of the D1 and D2 dyes is 0.5 to 5 parts by weight based on 100 parts by weight of the thermoplastic resin, based on the weight of the toner. It is preferable that the absorbance is 0.4 or more. Some of the commercially available dyes have a dispersant added, but the ratio here is the value in the bulk dye. If the total amount of D1 dye and D2 dye is outside this range, 480
The absorbance at the minimum absorption wavelength in the wavelength range of nm to 580 nm is 0.4 to 2.0 [l · g per toner weight].
⁻¹ · cm ⁻¹ ] .

Examples of the D1 dye include CI. Sol
Vent Red 18, CI. Solvent Red
24, CI. Solvent Red 27, CI. So
lvent Red111, CI. Solvent R
ed145, CI. Solvent Red 146, C
I. Solvent Red 149, CI. Solve
nt Red155, CI. Solvent Red1
77, CI. Disperse Red 60, CI. D
isperse Red 88, CI. Disperse
Red5, CI. Disperse Red73, C
I. Disperse Red 127, CI. Disp
erse Red 145, CI. Disperse R
ed146, CI. Disperse Red 166,
CI. Disperse Red 184, CI. Dis
Perse Red 283 and the like. As the D1 dye, an azo dye is preferable.

As the D2 dye, for example, MAC
ROLEX Red VioletR, Sumipla
st Bordeanx HBL, Palanil Br
iliant Violet4REL, Kayal
on PolyesterRed VioletFBL
Is mentioned. As the D2 dye, anthraquinone dye is preferable.

As a method for obtaining the magenta toner of the present invention, a D1 dye, a D2 dye, a thermoplastic resin, a polarity control agent, etc.
There are a method of kneading and pulverizing with a dye, and a method of dyeing a polymerized toner such as suspension polymerization, emulsion polymerization and dispersion polymerization with D1 dye and D2 dye. To achieve high image quality, it is desirable that the toner has a small particle size and a narrow particle size distribution. Specifically, the toner has a volume average particle diameter (Dv) of 3 to 9 μm and a ratio (Dv) to the number average particle diameter (Dp). / Dp) is preferably in the range of 1.00 to 1.15. A dispersion polymerization method is preferable as a method for producing such a toner having a small particle diameter and a narrow particle size distribution, and a method of dyeing resin particles is preferable for improving transparency.

As the thermoplastic resin used for the powder particles of the toner of the present invention, conventionally known thermoplastic resins can be widely used. For example, styrene, parachlorostyrene, vinyltoluene, vinyl chloride, vinyl acetate, vinyl propionate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate. , Isobutyl (meth) acrylate, tert-butyl (meth) acrylate, dodecyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
Lauryl (meth) acrylate, (meth) acrylic acid 2-
Droxyethyl, glycidyl (meth) acrylate,
Hydroxypropyl (meth) acrylate, benzyl (meth) acrylate, furfuryl (meth) acrylate,
2-Chloroethyl (meth) acrylate, (meth) acrylonitrile , (meth) acrylamide, (meth) acrylic acid, vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl methyl ketone , N-vinyl pyrrolidone , Polymers of monomers such as N-vinylpyridine and butadiene, copolymers of two or more kinds of these monomers, and a mixture thereof. Other polyesters, polyurethanes, polyamides, epoxy resins, rosins, modified rosins, terpene resins, phenol resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins and the like can be used alone or in combination.

If desired, a charge control agent, a release agent, etc. may be added to the toner of the present invention. As the charge control agent, in the case of a negatively chargeable toner, for example, a metal chelate of alkylsalicylic acid or hydroxynaphthoic acid, JP-A-5-58
Examples thereof include the fluorine-based compounds described in JP-A-5-76353 and JP-A-3-213877. Further, in the case of a positively chargeable toner, quaternary ammonium salts, alkyl metal oxides described in JP-A-56-164350 and the like can be mentioned.

As the release agent, low molecular weight polyethylene,
Low molecular weight polyolefins such as low molecular weight polypropylene and polyethylene oxide, beeswax, carnauba wax,
Natural waxes such as montan wax, higher fatty acids such as stearic acid, palmitic acid and myristic acid, metal salts of higher fatty acids, and higher fatty acid amides can be used. By forming a thin layer of the release agent on the toner surface, an excellent effect can be obtained with a small addition amount, which is preferable.

When a carrier is used in the developer using the toner of the present invention, conventionally known materials such as surface-oxidized or unoxidized metals such as iron, nickel, copper, zinc, cobalt, manganese, and chromium, and The alloys or oxides thereof and ferrite composed of the above metals can be used . The surface of the carrier may be coated with resin or the like.

Further, a developer using the toner of the present invention is
Flowability modifiers such as colloidal silica can be used. The addition amount of the fluidity modifier is 0.0 with respect to the toner.
About 1 to 3 parts by weight is preferable.

[0020]

Example 1 A styrene-maleic anhydride copolymer was dissolved in a mixed solvent of methyl alcohol and water, and 55 parts of styrene and 45 parts of methyl acrylate were copolymerized therein. The obtained polymer had a volume average particle diameter (Dv) of 4.7 μm and a ratio Dv / Dp to the number average particle diameter (Dp) of 1.12. Next, CI. Disperse Red6
0, 0.67 parts, and Kayalon Polyeste
1.33 parts of rRedViolet FBL (dye bulk powder) was added with stirring at room temperature. Next, this solution was stirred at 50 ° C. for 3 hours to dye the resin, then filtered and dried to obtain magenta colored particles. Then, the dyed particles 100
Parts were redispersed in 300 parts of a water-methanol (1: 1) mixed solvent, 2 parts of perfluoroalkylphosphoric acid were added and mixed by stirring, and the solvent was removed by a spray dryer to obtain a magenta toner. 0.04 g of this toner was precisely weighed, dissolved in acetone to 50 ml, and a spectrophotometer (manufactured by Shimadzu; U
V-3100) was used to measure a spectral absorption spectrum at a wavelength of 350 nm to 700 nm, which is shown in FIG. In all wavelength ranges of 480 nm to 580 nm of the toner, the absorbance per weight of the toner was 0.45 or more. Further, Emin / Emax was 0.51. Three parts of this toner was mixed with 100 parts of iron powder carrier to prepare a two-component developer. The obtained developer was put in a magnetic brush developing device and subjected to a copying test using a digital electrophotographic device having an organic photoconductor. As a result, a magenta image having excellent dot reproducibility and good spectral characteristics was obtained. When the developer was transferred and fixed on a polyester film using a digital copying machine, the haze of the image was 12.7. This image is taken from an overhead projector (OH
When projected in P), a clear magenta image was projected.

Comparative Example 1 CI. Disperse Red 60, 1.
Part 2 and Kayalon Polyester Red V
ioletFBL, CI. Disp
Example 1 except that only 2 parts of erse Red 60 were used.
A toner was prepared in the same manner as in . The spectrum of the toner is shown in FIG . Absorbance at 580nm is 0.15
Thus, Emin / Emax was 0.16. When a developer was prepared using this toner and evaluated in the same manner as in Example 1, the obtained image was red and had a color tone lacking bluish tint.

Comparative Example 2 The CI. Disperse Red 60, 1.
Part 2 and Kayalon Polyester Red V
Kayolon instead of ioletFBL, 5.4 parts
Polyester Red Violet FBL,
A toner was prepared in the same manner as in Example 1 except that only 2 parts were used. The spectral spectrum of the toner is shown in FIG. 480
Absorbance at nm is 0.21, Emin / Emax
Was 0.32. A developer was prepared from this toner in the same manner as in Example 1 and evaluated. As a result, the obtained copied image had a reddish purple color, a strong blue tint, and insufficient redness.

Example 2 Magenta particles 10 polymerized and dyed in the same manner as in Example 1
0 part was redispersed in 300 parts of water-methanol (1: 1) mixed solvent, 2 parts of perfluoroalkylphosphoric acid and 2 parts of carnauba wax emulsion were added and mixed with stirring, and the solvent was removed by a spray dryer. Then, a magenta toner was obtained. Next, 3 parts of this toner is used as an iron powder carrier 100.
When a digital copying machine equipped with a fixing roller which does not use oil such as silicone oil is used as a two-component type developer by mixing with a toner image, a fixing temperature of 150 is obtained.
A magenta image having excellent dot reproducibility and good spectral characteristics was obtained without causing paper wrapping or an offset phenomenon in the range of up to 210 ° C. The haze value measured in the same manner as in Example 1 was 13.5.

Example 3 Polyester resin (Tg 58 ° C., softening point 68 ° C.) 100
Department, CI. Solvent Red27, 1 copy, MAC
ROLEX Red VioletR , Part 2, and 3 ,
5 - The ditertiary butyl salicylic acid zinc 4 parts mixture comprising heating and kneading by a hot roll, pulverized to prepare a toner having a volume average particle diameter of 8.5μm and classified. When the spectral absorption spectrum of this toner was measured in the same manner as in Example 1, the absorbance per weight of the toner was 0.59 or more in all wavelength ranges of 480 nm to 580 nm. Also, the maximum absorbance Emax at 480 nm to 580 nm
Is 0.885 [l · g ⁻¹ · cm ⁻¹ ] (λ = 53
8.8 nm), and the minimum absorbance Emin is 0.48.
It was [l · g ⁻¹ · cm ⁻¹ ] (λ = 480 nm). From this result, the ratio (Emin / Emax) of the absorbance at the maximum absorption wavelength and the absorbance at the minimum absorption wavelength was calculated to be 0.54. To 100 parts of this toner, 0.5 part of silica was added to prepare a magenta toner having silica on the surface of particles. Next, 3 parts of this toner was mixed with 100 parts of the iron powder carrier to prepare a developer. This developer was placed in a magnetic brush developing device and a copying test was conducted using a digital electrophotographic device having an organic photoconductor to obtain a clear magenta color copied image having good spectral characteristics. When the haze of the copied image transferred to the polyester film was measured, it was 14.9 and the transparency was excellent.

Example 4 60 parts of styrene, 30 parts of n-butyl methacrylate, 10 parts of lauryl methacrylate, CI. Solvent
Red24 , 0.8 copy, MACREX Red V
ioletR , 2.4 parts, 2-hydroxy-3-naphthoic acid 4 parts, azobisisobutyl nitrile 2 parts, and styrene-acrylic acid copolymer (copolymerization ratio, 95: 5) 5 parts were dispersed using a ball mill. . Then, it was added to 300 parts of a 2% aqueous solution of polyvinyl alcohol and uniformly dispersed using a homogenizer to carry out suspension polymerization to obtain a magenta toner having an average particle diameter of 8 μm. The spectral absorption spectrum of this magenta toner was measured in the same manner as in Example 1, and the result was 480.
Absorbance per weight of the toner is 0.57 or more in all wavelength ranges from nm to 580 nm, and Emin / Emax
Was 0.51. To 100 parts of this magenta toner, 0.3 part of silica was added to prepare a magenta toner having silica on the particle surface.
A developer was prepared by mixing 3 parts with 00 parts. This developer was placed in a magnetic brush developing device and a copying test was conducted using a digital electrophotographic device having an organic photoconductor to obtain a clear magenta color copied image having good spectral characteristics. When the haze of the copied image transferred to the polyester film was measured, it was 15.4, indicating excellent transparency.

Example 5 The CI. Disperse Red 60, 1.
Part 2 and Kayalon Polyester Red V
ioletFBL, CI. Dosp
ersed Red 127, 0.5 copy, MACROLE
A toner was prepared in the same manner as in Example 1 except that 1.5 parts of X RedVioletR was used. In the spectral absorption spectrum of this toner, the minimum value Emin of the absorbance per weight of the toner in the wavelength range of 480 nm to 580 nm is 0.45 [l · g ⁻¹ · cm ⁻¹ ] (λ = 480 nm).
Thus, Emin / Emax was 0.38. A developer was prepared from this toner in the same manner as in Example 1 and evaluated. As a result, the copy image obtained was magenta color tone having excellent dot reproducibility and good spectral characteristics.

Example 6 The CI. Disperse Red 60, 1.
Part 2 and Kayalon Polyester Red V
BAYSCRI instead of ioletFBL, 5.4 parts
PT SPECIAL RedT , 1.8 copies, MACR
A toner was prepared in the same manner as in Example 1 except that 5.4 parts of OLEX Red VioletR was used. The spectral absorption spectrum of this toner is the minimum value E of the absorbance per weight of the toner in the wavelength range of 480 nm to 580 nm.
min is 1.81 [l · g ⁻¹ · cm ⁻¹ ] (λ = 48
At 0 nm), Emin / Emax was 0.46.
A developer was prepared from this toner in the same manner as in Example 1 and evaluated. As a result, the copy image obtained was magenta color tone having excellent dot reproducibility and good spectral characteristics.

Comparative Example 3 The CI. Disperse Red 60, 1.
Part 2 and Kayalon Polyester Red V
ioletFBL, instead of 5.4 parts, Disper
se Red60, 3 copies, MACROLEX Red
A toner was prepared in the same manner as in Example 1 except that 3 parts of VioletR was used. The spectral absorption spectrum of this toner shows that the minimum value Emin of the absorbance per weight of the toner in the wavelength range of 480 nm to 580 nm is 2.16 [l.
g ⁻¹ · cm ⁻¹ ] (λ = 580 nm), Emin /
Emax was 0.55. When a developer was prepared from this toner in the same manner as in Example 1 and evaluated, the obtained copy image was a magenta image having low lightness.

[0029]

Since the magenta toner of the present invention has high transparency and excellent spectral reflection characteristics as described above, an image copied onto an OHP sheet or the like has good transparency and a clear and excellent projected image is obtained. be able to.

[Brief description of drawings]

FIG. 1 is a diagram showing a spectral absorption spectrum of a toner of Example 1.

FIG. 2 is a diagram showing a spectral absorption spectrum of a toner of Comparative Example 1.

3 is a diagram showing a spectral absorption spectrum of a toner of Comparative Example 2. FIG.

[Explanation of symbols]

1 Emax 2 Emin

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-2-264969 (JP, A) JP-A-4-13664 (JP, A) JP-A-4-301649 (JP, A) JP-A-8- 69128 (JP, A) JP-A-2-27964 (JP, A) JP-A-6-208248 (JP, A) JP-A-6-175401 (JP, A) JP-A-3-213876 (JP, A) JP-A-59-26757 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/09

Claims (2)

(57) [Claims] 1. A spectral absorption spectrum of a dye in an electrostatic latent image developing toner containing a thermoplastic resin and a dye as main components.
Dye with an absorption maximum of 500 nm to 560 nm (D
1) and 530 nm to 550 nm and 560 nm to 5
And a dye (D2) having two absorption peaks at 90 nm.
And having a spectral absorption spectrum of 480 nm to 580 n
Maximum absorbance at m (Emax) and 480 nm-580
The ratio with the minimum absorbance (Emin) in nm (Emin /
Emax) is 0.3 to 1.0 der Rutotomoni, Emin is converted per weight of the toner 0.4-2.0 [l · g
⁻¹ · cm ⁻¹ ] . A magenta toner for developing an electrostatic latent image. 2. The magenta toner for developing an electrostatic latent image according to claim 1 , wherein the D2 dye is an anthraquinone dye.