JPH06180512A - Electrophotographic toner - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic toner capable of forming a high density image without deteriorating resolution or sharpness due to a reduced particle diameter by using powdery particles having a specified average particle diameter and a specified extinction coefft. CONSTITUTION:In an electrophotographic toner made of powdery particles contg. resin particles and a colorant as essential components, powdery particles having <=7mum average particle diameter and >=3[1.g<-1>.cm<-1>] extinction coefft. per 1g of the particles are used. A known thermoplastic resin such as polyester resin, epoxy resin or polyurethane resin is used as the resin of the resin particles. The toner is most preferably produced by dyeing resin particles obtd. by dispersion polymn., suspension polymn. or other method with a disperse dye or an oil-soluble dye. The extinction coefft. of the toner particles can be set within a prescribed range by regulating the molecular extinction coefft. of the colorant, the mol.wt. of the resin and the ratio between the resin and the colorant.

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 more particularly to an electrophotographic toner capable of forming a high resolution and high density image. .

[0002]

2. Description of the Related Art In recent years, in order to achieve high image quality, high durability, and colorization of electrophotographic systems, toner particle size reduction, sharp particle size distribution, sufficient coloring power, and uniform charge control,
Transparency is required. In particular, it is known that an image with high resolution and good sharpness can be obtained by reducing the toner particle size. (Electrophotographic Society, Volume 31, 1
On the other hand, as one of methods for producing a toner having a small particle diameter, a method is known in which a thermoplastic resin and a colorant are melt-kneaded, pulverized, and then classified to produce. However, when a small particle size toner is manufactured by this method, the productivity is poor and the yield is remarkably reduced.
In addition, JP-A-4-151671 and JP-A-4-29067
No. 0, there is proposed a method for producing a toner having a small particle diameter by a dispersion polymerization method or a suspension polymerization method. The toner prepared by these methods has a drawback that the image density of the obtained copy image is low. When the toner charge amount is adjusted to increase the image density and the number of toner particles per unit area is increased, the image density increases, but the resolution and sharpness decrease, and the advantages of the small particle size toner are fully exerted. There is a problem that is not done.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a toner capable of forming a high density image with a small particle size toner without lowering resolution and sharpness. To that end.

[0004]

That is, according to the present invention,
In an electrophotographic toner comprising powder particles containing resin particles and a colorant as main components, the average particle diameter of the powder particles is 7
and the extinction coefficient is 3 μm or less per 1 g of the powder particles.
Provided is an electrophotographic toner having a particle size of [1 · g ⁻¹ · cm ⁻¹ ] or more. Further, according to the present invention, there is provided an electrophotographic toner characterized by using powder particles obtained by dyeing the resin particles with a disperse dye or an oil-soluble dye, and further, the volume of the powder particles is provided. The ratio Dv / Dp of the average particle diameter Dv and the number average particle diameter Dp is 1.00 to 1.
A toner for electrophotography is provided which is No. 15. In the present invention, it is preferable to use a dispersion polymerization method when forming the powder particles, and further to provide a surface coating layer composed of a charge control substance and a releasing substance on the surface of the powder particles. Is preferred.

As the raw material resin for the resin particles used in the present invention, various thermoplastic resins conventionally known in this kind of field, such as polyester resin, epoxy resin, polyurethane resin, and various monomers exemplified below are used. Polymers or copolymers of can be used. Specific examples thereof include styrene, parachlorostyrene, vinyltoluene, vinyl chloride, vinyl acetate, vinyl propionate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic. N-butyl acid,
Isobutyl (meth) acrylate, dodecyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, wallyl (meth) acrylate, 2-hydrochitoethyl (meth) acrylate, hydroxypropyl (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,
Examples thereof include N-vinylpyrrolidone, N-vinylpyridine, ethylene, propylene and butadiene.

As the method for producing the toner in the present invention, a method of kneading and kneading the thermoplastic resin with a colorant, a polarity control agent or the like, a method of suspension polymerization with a monomer and a colorant, a polarity control agent or the like, or There is a method of using polymerized particles obtained by a dispersion polymerization method, but in particular, resin particles obtained by a polymerization method such as a dispersion polymerization method or a suspension polymerization method are dyed with a disperse dye or an oil-soluble dye. It is preferred to use the method.

In the present invention, examples of the disperse dye or oil-soluble dye used for dyeing the resin particles include:
CI. Solvent Yellow6, 9, 17, 3
1, 35, 58, 100, 102, 103, 105, C
I. Solvent Orange2, 7, 13, 1
4, 66, CI. Solvent Red 5, 16, 1
7, 18, 19, 22, 23, 143, 145, 14
6, 149, 150, 151, 157, 158, CI.
Solvent Violet 31, 32, 33, 3
7, CI. CI. Solvent Blue 22, 6
3, 78, 83, 84, 85, 86, 91, 94, 9
5, 104, CI. Solvent Green24,
25, CI. Solvent Brown 3, CI. S
oil-soluble dyes such as olive black 3 and CI. D
isperse Yellow3, 7, 33, 42, 6
4, 82, 237, CI. Disperse Oran
ge3, 13, 29, 30, CI. Disorse
Red1, 17, 50, 54, 56, 60, 65, 7
2, 73, 88, 91, 92, 110, 135, 14
5, 156, 154, 167, 177, 207, 25
8, 283, CI. Disperse Violet
1, 4, 26, 28, 35, 38, 43, 77, CI.
Disperse Blue3, 7, 56, 60, 7
3, 79, 81, 91, 94, 96, 102, 106,
128, 139, 146, 148, 149, 165, 1
83, 186, 187, 197, 201, 205, 20
7, 214, 257, 266, 268, 291, 34
1, 354, 358, CI. Disperse Bro
wn1, CI. Disperse dyes such as Disperse Black 1 may be mentioned.

In the toner of the present invention, the extinction coefficient (ε) per 1 g of powder particles is determined by dissolving the toner powder particles in a solvent such as acetone, toluene, tetrahydrofuran, dimethylformamide, etc. (E) can be obtained and calculated from the following equation 1.

[Equation 1] (However, d is the thickness of the toner liquid layer (cm), c is the concentration of the toner solution (g / l)) Even in the case of a small particle diameter toner having an average particle diameter of 7 μm or less, 1 g of toner powder particles The extinction coefficient (ε) per hit is 3 [1
.G ⁻¹ · cm ⁻¹ ], the image density becomes low,
It cannot be used. Further, in this case, if an attempt is made to increase the image density by increasing the adhesion amount, the resolution and the sharpness are lowered, and it is not possible to achieve both high density and high image quality. As a method for producing a toner having an extinction coefficient of 3 [1 · g ⁻¹ · cm ⁻¹ ] or more per 1 g of toner powder particles, the molecular extinction coefficient of the coloring agent, its molecular weight, and the ratio of the resin to the coloring agent are used. Can be achieved by adjusting

The method for dyeing the resin particles with the oil-soluble dye or the disperse dye is as follows: the dye and the resin particles are dispersed and heated in water for dyeing, or an organic solvent which is insoluble in the resin is used. Examples include a method of dissolving a dye and dyeing the resin particles in a solvent, such as a solvent dyeing method.

In the present invention, a surface coating layer comprising a charge control agent or a releasing material can be further provided on the surface of the particles dyed in this way. As a charge control agent,
Nigrosine, an azine dye containing an alkyl group having 2 to 16 carbon atoms (JP-A-42-1627), a basic dye (for example, CI. Basic Yellow 2 (CI. 4)
1000) CI. Basic Red Yellow
3, CI. Basic Red 1 (CI.4516
0), CI. Basic Red9 (CI.4250
0), CI. Basic Violet 1 (CI.4
2535), CI. Basic Violet 3 (C
I. 42555), CI. Violet 10 (CI.
45170), CI. Basic Violet 14
(CI.42510), CI. Basic Blue
1 (CI.42025), CI. Basic Blu
e 3 (CI.51005), CI. Basic Bl
ue5 (CI.42140), CI. Basic Bl
ue 7 (CI. 42595), CI. Basic B
lue 9 (CI.52015), CI. BasicB
lue 24 (CI.52030), CI. Basic
Blue 25 (CI.52025), CI. Bas
ic Blue 26 (CI.44045), CI. B
asic Green 1 (CI.52040), C
I. Lake pigments of these basic dyes such as Basic Green 4 (CI.42000) (as the laker, phosphorus tengustenoic acid, phosphomolybdic acid, phosphotungstic acid, tannic acid iodophosphoric acid, gallic acid), CI. S
OIVENT Back 3 (CI.26150), Hansa Yellow G (CI. MordantBlack1
1, CI. Pigment Black 1 Benzoylmethyl-hexadecyl ammonium chloride, decyl trimethyl ammonium chloride, or dialkyl borate compounds such as dibutyl or dioctyl, guanidine derivatives, polyamine resins such as amino group-containing vinyl polymers and amino group-containing condensation polymers. , Japanese Examined Patent Publication Nos. 41-20153 and 43-27596.
Nos. 44-6397 and 45-26478, metal complex salts of azo dyes, JP-B-55-42
752, Japanese Patent Publication No. 54-150080, Japanese Patent Publication No. 58-
7384, JP-B-59-7385, and salicylic acid, dialkyl salicylic acid, naphthoic acid, metal complexes of dicarboxylic acids such as Zn, Al, Co, Cr and Fe, and sulfonated copper phthalocyanine pigments. . Also, as the release material, low molecular weight polyethylene,
Low molecular weight polyolefins such as low molecular weight polypropylene and polyethylene oxide, natural waxes such as beeswax, carnauba wax, montan wax, stearic acid, palmitic acid, myristic acid and other higher fats and higher fatty acid metal salts, higher fatty acid amides There are kinds. They are,
One kind or a mixture of two or more kinds can be used,
For example, low molecular weight polyolefins, particularly low molecular weight polypropylenes are preferred.

As a method for forming the coating layer containing the above-mentioned charge control substance and releasable substance, a generally known method can be adopted. For example, a method in which the dyed particles and a charge control agent or a release agent are mixed in a wet or dry manner, and mechanical energy is applied to the mixture to drive a resin coating colorant onto the surface of the powder particles to coat them, or an emulsification method. There is a method in which the charge control agent or the release agent described above is treated in a wet state to coat the surface.

[0012]

EXAMPLES The present invention will be described in detail below with reference to examples. In addition, all "parts" in the following Examples and Comparative Examples indicate parts by weight.

Example 1 100 polyester resin (Tg 58 ° C., softening point 68 ° C.)
Department, CI. Solvent Yellow 58, 12
Part, and a mixture consisting of 4 parts of 3,5-ditertiarybutylsalicylate zinc were heated and kneaded with a hot roll, pulverized and classified to obtain yellow powder particles having a volume average particle size of 6 and 5 μm.
0.5 part of silica was added to 100 parts of the powder particles to prepare a yellow toner having silica on the surface of the powder particles. The absorption spectrum of this toner was measured in an acetone solvent, and the absorbance per 1 g was determined from the absorbance at the maximum absorption value, and was 3.35. Then, 3 parts of this toner was mixed with 100 parts of an iron powder carrier to obtain a developer. This developer was set in a magnetic brush developing device, and a copying test was conducted using a digital copying machine equipped with an organic photoconductor. The image density of the copied image was 1.42, and the image had good dot reproducibility.

Example 2 55 parts of styrene and 45 parts of methyl acrylate were copolymerized in a methyl alcohol solvent in the presence of polyvinylpyrrolidone as a dispersion stabilizer to give a volume average particle diameter (D
v) 4.3 μm and the ratio D with the number average particle size (Dp)
Spherical powder particles having a narrow particle size distribution with v / Dp of 1.10 were obtained. Next, 100 parts of the powder particles are dispersed in 400 parts of methyl alcohol, and CI. Di
sperse Violet 26, 14 parts, and C
I. Solvent Red 24, 4 parts added and 50 ° C
It was stirred for 8 hours and dyed. Then, 20 parts of a 10% methanol solution of perfluoroalkyl sulfonic acid (Megafuck F-110 manufactured by Dainippon Ink and Chemicals, Inc.) was added at room temperature, stirred for 30 minutes, filtered and dried to obtain a magenta toner. Obtained. The absorbance per 1 g of this toner was found to be 5.02 in the same manner as in Example 1. Next, 3 parts of this toner was mixed with 100 parts of iron powder carrier to form a two-component developer, and an image was formed using a digital copying machine. As a result, a magenta image having an image density of 1.48 and excellent dot reproducibility was obtained. Got

Example 3 A styrene-maleic anhydride copolymer was dissolved in a mixed solvent of methyl alcohol and water, and styrene 55 was added to the solution.
And 45 parts of methyl acrylate are copolymerized to obtain a volume average particle diameter (Dv) of 3.2 μm and a number average particle diameter (Dp).
A polymerization solution containing powder particles having a ratio Dv / Dp of 1.12 was obtained. Next, C was added to this polymerization liquid at room temperature with stirring.
I. After adding 20 parts of Disperse Blue 353 and further stirring at 50 ° C. for 8 hours for dyeing,
Cyan toner was obtained by filtering and drying. The absorbance per 1 g of this toner was determined in the same manner as in Example 1.
It was 83. Next, 3 parts of this toner is used as an iron powder carrier 10
When mixed with 0 parts to form a two-component developer and image formation was carried out using a digital copying machine, the image density was 1.51.
A cyan image having excellent dot reproducibility was obtained.

Comparative Example 1 With the same monomer composition as in Example 3 and controlling the polymerization conditions, the volume average particle diameter (Dv) was 10.4 μm and the ratio Dv / Dp to the number average particle diameter (Dp) was 1.11. Polymer particles were prepared and a cyan toner was obtained in the same manner as in Example 3. The absorbance per 1 g of this toner was 6.78. Next, when a developer was formed and an image was formed in the same manner as in Example 3, the image density was 1.58, but the image was crushed and the dot reproducibility was considerably inferior to the image in Example 3.

Comparative Example 2 CI. Oil Black 803 (made by Orient Chemical Co., Ltd.) instead of Disperse Blue 353
A toner was prepared in the same manner as in Example 3 except that 4.29 g was used. The absorbance per 1 g of this toner was 1.72. Next, when a developer was prepared and an image was formed in the same manner as in Example 3, the dot reproducibility was good, but the image density was a low density of 0.97.

Example 4 60 parts of styrene, 30 parts of 2-ethylhexyl methacrylate and 10 parts of butyl acrylate were copolymerized in a methyl alcohol solvent in the presence of polyvinylpyrrolidone as a dispersion stabilizer to obtain a volume average particle size ( Dv) Spherical powder particles having a narrow particle size distribution of 5 μm and a ratio Dv / Dp to the number average particle diameter (Dp) of 1.12. Next, 100 parts of the powder particles are dispersed in 400 parts of methyl alcohol, and 12 parts of Oil Black 860 (manufactured by Orient Chemical Co.) and Macrolex Orange R (BA
3 parts by YER) was added and stirred at 50 ° C. for 8 hours for dyeing, and then 6 parts of carnauba wax emulsion (solid content 25%) was added at room temperature to form a carnauba wax layer on the surface of the black particles. . 100 parts of the powder particles and 2 parts of chromium complex dye (Orient Chemical Co., Ltd .; S-34) are mixed,
Using a hybridizer (manufactured by Nara Machinery Co., Ltd.) 10,
The toner was treated under the conditions of 000 rpm for 3 minutes to obtain a toner in which the chromium complex salt dye was adhered and immobilized on the surface. When the absorbance of this toner was determined in the same manner as in Example 1, it was 4.52. Next, 3 parts of this toner was mixed with 100 parts of iron powder carrier to prepare a two-component developer, and an image was formed using a digital copying machine. The image density was 1.52 and the dot reproducibility was excellent. A black image was obtained. Further, after repeatedly copying 50,000 sheets, the image density of the 50,000th sheet was 1.49, and clear copied images were obtained in all cases.

[0019]

The toner for electrophotography of the present invention has a small particle size and a high absorbance, so that a high density image can be obtained without deteriorating the resolution and sharpness of the image. .

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Claims (5)

[Claims] 1. An electrophotographic toner comprising powder particles containing resin particles and a colorant as main components, wherein the powder particles have an average particle diameter of 7 μm or less, and an absorption coefficient per 1 g of the powder particles. Is 3 [1 · g ^-1 · cm ^-1 ] or more, an electrophotographic toner. 2. The toner for electrophotography according to claim 1, wherein the powder particles are obtained by dyeing the resin particles with a disperse dye or an oil-soluble dye. 3. The ratio Dv / Dp of the volume average particle diameter Dv and the number average particle diameter Dp of the powder particles is 1.00 to 1.
15. The toner for electrophotography according to claim 1, wherein the toner is 15. 4. The toner for electrophotography according to claim 1, wherein the powder particles are formed by a dispersion polymerization method. 5. The toner for electrophotography according to claim 1, wherein the surface of the powder particles is provided with a surface coating layer made of a charge control substance and a releasing substance.