JPH0266563A - Color toner for electrophotography and production thereof - Google Patents

Abstract

PURPOSE:To enable the formation of an image having superior color developability and light resistance by kneading a resin binder having a specified average mol. wt. with a yellow pigment belonging to C.I. pigment No. yellow 17 at a temp. below the softening point of the resin binder. CONSTITUTION:A resin binder having >=100,000wt. average mol. wt. is kneaded with a yellow pigment belonging to. C.I. pigment No. yellow 17 at a temp. below the softening point of the resin binder by 30-65 deg.C. Since high shearing force is applied at the time of kneading, the yellow pigment firmly aggregated to secondary particles is crushed and dispersed as nearly primary particles. The occurrence of cracks around the pigment is suppressed at the time of cooling, the dispersibility of the pigment in the resin binder and the dispersion strength are considerably improved and satisfactory color developability and light resistance are ensured for the resulting yellow toner. Even when images are formed many times, the liberation of the yellow pigment from the toner particles is suppressed and stable color images can be formed without causing fogging, toner scattering or defective cleaning.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color toner for electrophotography and a method for producing the same.

[Technical Background] In electrophotography, generally, a latent image carrier (hereinafter also referred to as "photoreceptor J") having a photosensitive layer made of a photoconductive material is used.

), an electrostatic latent image is formed on the surface of the paper by charging and imagewise exposure, and then this electrostatic latent image is developed with toner, which is a colored particle, and the resulting toner image is usually printed on a recording material such as paper. After being transferred, it is fused to form a visible image. On the other hand, the photoreceptor after the transfer is neutralized, and then the toner remaining on the photoreceptor without being transferred is cleaned, and then the next image is formed.

Electrophotographic color toners used for forming color images are generally composed of a binder resin containing various chromatic dyes or pigments dispersed therein.

However, dye-based color toners generally have good color development and can form clear color images, but on the other hand,
There is a problem with poor light resistance.

Pigment-based color toners generally have excellent light resistance, but on the other hand, the dispersibility of the pigment in the binder resin is poor, resulting in poor color development and toner durability.

On the other hand, yellow toner is indispensable in forming multicolor images. Examples of yellow pigments used in such yellow toners include those described in Japanese Patent Application Laid-Open No. 60-553.
As described in Japanese Patent No. 58, C.1 is used because the pigment itself has particularly excellent coloring properties.

Pigment No. A yellow pigment of Yellow 17 is useful.

(Problem to be solved by the invention) However, C. I. Pigment No. The yellow pigment in Yellow 17 has extremely poor dispersibility and dispersion strength in the binder resin, and as a result, sufficient color development cannot be obtained as a yellow toner, and when images are formed many times, the yellow pigment separates from the toner particles. This gradually contaminates the surfaces of the carrier and photoreceptor, causing problems such as poor cleaning, fogging, and toner scattering.

The present invention has been made based on the above-mentioned circumstances, and its purpose is to prevent pigment from being released from toner particles even when images are formed many times, and to prevent pigment from being released from toner particles due to contamination of the photoreceptor, etc. An object of the present invention is to provide a color toner for electrophotography that can form images with excellent color development and light fastness without causing image defects, and a method for producing the same.

[Means to solve the problem]

In order to achieve the above object, the color toner for electrophotography of the present invention contains a binder resin having a weight average molecular weight of 100,000 or more and a yellow pigment of C, T, Pigment No., and Yellow 17 as essential components. The color toner is 30 to 65"C higher than the softening point of the binder resin.
It is characterized in that the pigment is dispersed and contained in the binder resin by kneading at a low temperature.

The method for producing a color toner for electrophotography of the present invention includes a binder resin having a weight average molecular weight Mw of 100,000 or more, C, t
, Pigment No. The yellow pigment of Yellow 17 and other toner components used as necessary are kneaded at a temperature 30 to 65° C. lower than the softening point of the binder resin, pulverized, and classified.

[Function] A binder resin having a weight average molecular weight of 100,000 or more, and a C.I.
I. The yellow pigment of Pigment No. Yellow 17 is
When kneaded at a temperature 30 to 65° C. lower than the softening point of the binder resin, a strong secondary a group is produced due to the high shearing force applied during kneading.1. Pigment N
The yellow pigment of o Yellow 17 is crushed and dispersed to almost the primary particle size, and furthermore, since it is difficult for a crank to enter the vicinity of the pigment during cooling, the dispersibility and dispersion strength of the yellow pigment in the binder resin are significantly improved.

Therefore, the yellow toner has sufficient color development and light fastness, and a clear color image can be formed. In addition, even when images are formed many times, it is difficult for the yellow pigment to be released from the toner particles (fogging,
Stable color images can be formed without toner scattering or poor cleaning.

[Specific structure of the invention]

Hereinafter, the configuration of the present invention will be specifically explained.

The color toner for electrophotography of the present invention basically comprises a binder resin having a weight average molecular weight Mw of 100,000 or more, and a C.I.
I. Pigment No. The yellow pigment of Yellow 17 is an essential component, and these components are kneaded at a temperature 30 to 65° C. lower than the softening point of the binder resin, so that the yellow pigment is dispersed and contained in the binder resin.

The binder resin needs to have a weight average molecular weight M- of 100,000 or more. If the molecular weight Mw is less than 100,000, the toner particles themselves are likely to be crushed, making it difficult to sufficiently prevent the generation of free pigment due to crushing, and the surfaces of photoreceptors, carriers, etc. will be contaminated at an early stage.

Here, the value of the weight average molecular NM circle can be determined by various methods, and there are slight differences depending on the measurement method, but in the present invention, the value determined according to the measurement method below is Define.

That is, the weight average molecular weight M- is measured by gel vermiculture chromatography (GPC) under the conditions described below. At a temperature of 40'C, a solvent (tetrahydrofuran) is flowed at a flow rate of 1 or 2 ml per minute, and a sample solution of 3 mg of tetrahydrofuran with a concentration of 0.2 g/20 ml is injected as a sample weight, and measurement is performed. When measuring the molecular weight of a sample, select measurement conditions in which the molecular weight of the sample falls within a range in which the logarithm of the molecular weight and the count number of a calibration curve created using several types of monodispersed polystyrene 411 samples form a straight line.

The reliability of the measurement results is determined by the N
B5706 polystyrene standard sample has a weight average molecular weight M
By becoming w = 28.8XIO', T11! can be approved.

Moreover, any column may be used as the GPC column as long as it satisfies the above conditions. Specifically, for example, TSK-GEL, GMH, (manufactured by Toyo Soda Co., Ltd.), etc. can be used.

Note that the solvent and measurement temperature are not limited to the conditions described, and may be changed to appropriate conditions.

Specific examples of the binder resin are not particularly limited, and various resins can be used. Specifically, examples include styrene resins, acrylic resins, styrene-acrylic copolymer resins, epoxy resins, and polyester resins. These resins may be used in combination.

The styrene-acrylic copolymer resin used as the binder resin is a resin made of a copolymer of a styrene monomer and an acrylic monomer.

Specific examples of styrenic monomers include styrene,
0-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene,
2,4-dimethylstyrene, p-n-butylstyrene,
p-tart-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n decylstyrene, p-n-dodecylstyrene, p-methoxystyrene, p-phenyl styrene,
Examples include p-chlorostyrene and 3,4-dichlorostyrene, and these monomers may be used alone or in combination.

Specific examples of acrylic monomers include acrylic acid, methyl acrylate, ethyl acrylate, and acrylic acid n.
-Butyl, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, α-chloroacrylic acid Methyl, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate , phenyl methacrylate, dimethylaminoethyl methacrylate,
Examples include diethylaminoethyl methacrylate, acrylonitrile, methacyclonitrile, acrylamide, and others, and these monomers may be used alone or in combination.

A polyester resin as a binder resin is obtained by polycondensation of a polyhydric alcohol monomer and a polyhydric carboxylic acid monomer.

Examples of polyhydric alcohol monomers include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-furandiol, neopentyl glycol, and 1,4-butynediol. , polyoxypropane (2,2) 2,1-bis(4-hydroxyphenyl)
Diols such as propane, etherified bisphenols such as 1,4-bis(hydroxymethyl)cyclohexane, bisphenol A, hydrogenated hisphenol A, polyoxyethylated bisphenol A, polyoxypropylenated bisphenol A, and other Mention may be made of dihydric alcohol monomers.

In addition to the above-mentioned divalent monomers, polyvalent monomers of trivalent or higher valence may also be used, if necessary.

Examples of trihydric or higher polyhydric alcohol monomers include sorbitol, 1,2,3,6-hexanetetrol, 1,
4-Sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, SidL 1
, 2.4-butanetriol, 1,2.5-pentanetriol, chrycerol, 2-methylpropanetriol, 2-methyl-12,4-butanetriol, trimethylolethane, trimethylolpropane, 1.3゜5
-trihydroxymethylbenzene, and others.

Examples of polycarboxylic acid monomers include maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, Examples include cepatic acid, malonic acid, anhydrides or lower alkyl esters of these acids, dimers of liluic acid, and other divalent organic acid monomers.

In addition, examples of trivalent or higher polyvalent carboxylic acid monomers include 1,2.4-benzenetricarboxylic acid, 1.3.5-
Benzenetricarboxylic acid, 1.2゜4-cyclohexanetricarboxylic acid, ■, 2.5-cyclohexanetricarboxylic acid, 2,5.7-naphthalenetricarboxylic acid, l,
2.4-butanetricarboxylic acid, 1.2.5-hexanetricarboxylic acid, 1.3-dicarboxyl-2-methyl-2-methylene tricarboxylic acid, tetra(methylenecarboxy)methane, 1,2,7. Mention may be made of 8-octane tetracarboxylic acid, embol trimer acid, anhydrides of these acids, and others.

In the present invention, C. I.
Pigment No. A yellow pigment of Yellow 17 (see Color Index 3rd Edition 1971 Supplement 1975) is used.

Preferred commercially available yellow pigments include, for example, those listed below.

・KET-Yellow 403 (manufactured by Dainippon Ink) ・Irgalite Yellow2 CP (manufactured by Nippon Ciba Geigy) 1lostaprint Yellow G G31
(Manufactured by Hoechst) Sumikaprine Fast
Yellow G B F N (manufactured by Sumima Kagaku Co., Ltd.) The proportion of the yellow pigment is preferably about 1 to 20 parts by weight based on 100 parts by weight of the binder resin.

Other toner components that may be used as necessary include, for example, a charge control agent, a fixability improving agent, and the like.

The charge control agent is preferably colorless or white in order not to impair the coloring properties of the color toner.

Examples of fixability improvers include polyolefins, fatty acid metal salts, fatty acid esters, partially saponified fatty acid esters,
Examples include higher fatty acids, higher alcohols, liquid or solid paraffin waxes, amide waxes, polyhydric alcohol esters, silicone resins, aliphatic fluorocarbons, etc. In the present invention, the above-mentioned binder resins and the above-mentioned yellow Pigments and other toner components used as necessary are added to the softening point T of the binder resin.
Kneading at a temperature 30 to 65 ° C lower than sp.
It is necessary to disperse and contain the yellow pigment in the binder resin.

When the kneading temperature is higher than the above temperature, high shearing force is not applied during kneading, and the yellow pigment, which has strong agglomeration properties, cannot be dispersed to almost the primary particles. Because of this tendency, the dispersibility of the yellow pigment in the binder resin is reduced, and free pigment is likely to be produced during repeated use. Also,
If the kneading temperature is lower than the above-mentioned temperature, the resin will not be in a molten state during kneading and kneading will not be substantially possible, or the shearing force at the rake edge will be so low that the pigment will hardly be dispersed.

Here, the softening point Tsp is the elevated flow tester rC
FT-500 model (manufactured by Shimabara Seisakusho), the measurement conditions were: load 20 kg/cI112, nozzle diameter 1 mm.
, nozzle length 1 mm, preheating at 80°C for 5 minutes, heating rate 6°C/min, sample fi1cm" (intrinsic specific gravity x
When measured and recorded as (weight expressed in 1 cm'),
When the height of the S-curve in the flow tester's plunger drop-temperature curve (softening flow curve) is h, h
/2.

Next, the method for producing color toner of the present invention will be specifically explained.

In the present invention, the above-mentioned binder resin, the above-mentioned yellow pigment, and other toner components used as necessary are premixed, each component is uniformly dispersed, and the softening point Tsp of the binder resin is These are sufficiently kneaded at a temperature 30 to 65 degrees Celsius lower, and then, after cooling, they are coarsely ground. Color toner with desired particle size distribution is produced by li grinding and classification.

The zero particle size of the color toner is usually preferably about 5 to 2 On.

Further, in order to improve the fluidity of the color toner, non-alkaline fine particles may be added and mixed into the toner from the outside.

Such inorganic fine particles include, for example, silica, alumina,
Titanium oxide, barium titanate, magnesium titanate, carunium titanate, strontium titanate, zinc oxide, chromium oxide, cerium oxide, antimony trioxide,
Examples include fine particles of zirconium oxide, silicon carbide, and the like. Particularly preferred are silica particles.

Commercially available silica fine particles include Aerosil R-
972, Aerosil R-974, Aerosil R-805
, Aerosil R-812 (manufactured by Nippon Aerosil Co., Ltd.)
etc. can be mentioned.

The addition ratio of the inorganic fine particles is preferably 0.1 to 1 dbw of the toner.

The color toner of the present invention can be applied to either a one-component developer or a two-component developer.

The carriers used in combination when forming a two-component developer are not particularly limited, and include, for example, uncoated carriers made of only magnetic particles, resin-coated carriers made of magnetic particles whose surfaces are coated with resin, Examples include magnetic material-dispersed carriers in which magnetic materials are dispersed and contained in resin particles.

〔Example〕

Examples of the present invention will be specifically described below, but the present invention is not limited to these Examples.

[Example 1] <Manufacture of binder resin> Styrene 72 parts by weight n-butyl methacrylate 18 parts by weight or more of monomers were used, and the weight average molecule i1 Mw was 158.000.
, a styrene-acrylic copolymer resin with a softening point Tsp of 132°C was synthesized. This is referred to as binder resin (1).

<Manufacture of toner> - 100 parts by weight of the above binder resin (1) - Yellow pigment (KET-Yellow 403
．． Dainippon Ink@) 3
Parts by weight of wax (Viscol 660 P, manufactured by Kochu Kasei Kogyo Co., Ltd.) At least 3 parts by weight of the materials are premixed, then thoroughly kneaded at a temperature of 95°C, cooled, coarsely ground, and then finely ground. ,
Then, it was classified to obtain a powder with an average particle size of 12 μm.

Furthermore, silica fine particles (Aerosil R-9
72. (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed in a proportion of 0.4% by weight to produce a yellow toner.

[Example 2] Production of binder resin> 248 parts by weight of trimellitic acid, 143 parts by weight of terephthalic acid, 350 parts by weight of bisphenol A, propylene oxide, and 271 parts by weight or more of bisphenol A and ethylene oxide. The average molecular weight M is 123.
000 and a softening point Tsp of 140'C was synthesized. This is referred to as binder resin (2).

<Manufacture of toner> 100 parts by weight of the above binder resin (2), yellow pigment (llostaprint Yellow
w GG31+ Manufactured by Hoechst)
3 parts by weight of wax (Viscol 6 (IO P, manufactured by Kochu Kasei Kogyo Co., Ltd.) 3 parts by weight or more of the substance are premixed, then thoroughly kneaded at a temperature of 90°C, cooled, coarsely pulverized, and further It was pulverized and then classified to obtain a powder with an average particle size of 12μ.

Furthermore, silica fine particles (Aerosil R-9
72. (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed in a proportion of 0.4% by weight to produce a yellow toner.

[Comparative Example 1] <Manufacture of toner> - Binder resin (2) of Example 2 100 parts by weight Yellow pigment 01 ostaprint Yellow
0031. (manufactured by Hoechst) 3
Parts by weight of wax (Viscol 660 P, manufactured by Kochu Kasei Kogyo Co., Ltd.) At least 3 parts by weight of the materials are premixed, then thoroughly kneaded at a temperature of 130'C, cooled, coarsely ground, and then finely ground. ,
It was then classified to obtain a powder with an average particle size of 12 μl.

Furthermore, silica fine particles (Aerosil R-9
72. (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed at a ratio of o.4 times ff% to produce a yellow toner.

(Comparative Example 2) <Manufacture of binder resin> - Using monomers of 90 parts by weight of styrene and 10 parts by weight or more of n-butyl acrylate, the weight average molecular weight M- is 75.0 parts by weight.
00, a styrene-acrylic copolymer resin having a softening point Tsp of 103°C was synthesized.9 This was used as a binder resin (3).

Production of toner> - 100 parts by weight of the above binder resin (3) - Yellow pigment (KET-Yellow 40
3. Manufactured by Dainippon Ink) 3
Parts by weight Wax (Viscol 660 P, manufactured by Kochu Kasei Kogyo Co., Ltd.) 3 parts by weight or more of the materials are premixed, then thoroughly kneaded at 80°C 4 times, cooled, coarsely ground, and then finely ground. , and then classified to obtain a powder with an average particle size of 12 μm.

Furthermore, silica fine particles (Aerosil R-9
72. (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed in a proportion of 0.4% by weight to produce a yellow toner.

[Comparative Example 3] A yellow toner was produced in the same manner as in Comparative Example 2 except that the kneading temperature was changed to 65°C.

A summary of the composition of each of the above toners is shown in Table 1 below.

[Evaluation] (1)! II Material Dispersity Regarding the toners obtained in each of the above Examples and Comparative Examples,
The degree of dispersion of the pigment was investigated. The method for measuring the degree of dispersion is as follows.

The toner plate after melt-kneading is cut into a thin section using a microtome, and the thin section is observed using a transmission optical microscope to determine the degree of dispersion based on the number of pigment aggregates per unit area.

The results of the degree of dispersion are shown in Table 1 below. In the table, ◯ indicates that the degree of dispersion is sufficient, Δ indicates that the degree of dispersion is slightly inferior but still at a practical level, and × indicates that the degree of dispersion is poor and has a practical problem.

(2) Running test over 20,000 times Each developer was prepared by mixing each toner obtained in each of the above Examples and Comparative Examples with a resin-coated carrier so that the toner concentration was 5%. Photocopy machine' U-Bix 2800J
(manufactured by Konica ■) was used to conduct a running test in which color images were continuously formed 20,000 times, and the following items were evaluated.

The resin-coated carrier is produced using a fluidizing bed device.
The surface of ferrite particles (F-150, manufactured by Nippon Tetsuko Kogyo Co., Ltd.) was coated with styrene/methyl methacrylate copolymer resin (
60: This is a carrier coated with a film thickness of about 1 μm using 40). The weight average particle size of this carrier is 80 μl.

(Evaluation Items) ■ Judgment was made by measuring the relative density of the white background of the copy image using Capri "Sakura Densitometer" (manufactured by Konica ■), which is caused by the release of pigment. At this time, the determination was made by measuring the reflection density of blue light using a blue filter. If this concentration is usually 0.01 or less, there will be no practical problem.

■ The interior of the copying machine was visually observed to check for contamination due to toner scattering due to pigment release. In addition, the copied images were visually observed to check for the presence or absence of image stains due to toner scattering.

(2) Poor cleaning caused by pigment release The surface of the photoreceptor was visually observed to determine whether there was a filming phenomenon caused by poor cleaning.

The above results are shown in Table 2 below.

As can be understood from the results in Table 2, the yellow toner of the present invention has an extremely good dispersion degree of the yellow pigment, and since cranks are less likely to occur at the pigment/resin interface, the dispersion strength is high. In addition, the yellow toner has sufficient color development properties, and the pigment is less likely to be released from the toner particles, making it possible to form color images stably over many times without fogging, toner scattering, or poor cleaning.

On the other hand, in the yellow toner of Comparative Example 1, the kneading temperature was too high, so the degree of dispersion of the yellow pigment was low, and the dispersion strength was low because cracks were likely to occur at the pigment/resin interface. was easily released, causing fogging, toner scattering, and poor cleaning to occur at an early stage.

In the yellow toner of Comparative Example 2, the weight average molecular IM- of the binder resin is 100,000 or less, and the crosstalk temperature is too high, so the pigment is likely to be released from the toner particles, resulting in fogging, toner scattering, and poor cleaning. occurred early.

In the yellow toner of Comparative Example 3, the weight average molecule 1Mw of the binder resin is 100,000 or less, so when images are formed many times, the pigment is likely to be released from the toner particles, resulting in fogging, toner scattering, and poor cleaning. It happened early.

(Effects of the Invention) As described above in detail, the electrophotographic color toner of the present invention includes a binder resin having a weight average molecular weight of 100,000 or more, and a yellow pigment of C.I. Pigment No. Yellow 17. The yellow pigment is dispersed and contained in the binder resin by kneading at a temperature 30 to 65 degrees Celsius lower than the softening point of the binder resin, so the dispersibility of the yellow pigment in the binder resin is significantly improved. In addition, since cranks are less likely to occur at the pigment/resin interface, the color development as a yellow toner is sufficient, and even when images are formed multiple times, the yellow pigment is less likely to be released from the toner particles, reducing fogging. According to the manufacturing method of the present invention, a stable color image can be formed without causing toner scattering or poor cleaning. The toner component used in
Since the color toner is produced by kneading, pulverizing, and classifying at a low temperature of 0 to 65°C, it is possible to produce a color toner with excellent color development and durability.

Claims (2)

[Claims] (1) A binder resin having a weight average molecular weight of 100,000 or more, and a C.I. I. Pigment No. A color toner for electrophotography containing a yellow pigment of Yellow 17 as an essential component, wherein the pigment is dispersed in the binder resin by kneading at a temperature 30 to 65 degrees Celsius lower than the softening point of the binder resin. A color toner for electrophotography characterized by containing: (2) a binder resin having a weight average molecular weight Mw of 100,000 or more; and a C.I. I. Pigment No. For electrophotography, the yellow pigment of Yellow 17 and other toner components used as necessary are kneaded at a temperature 30 to 65°C lower than the softening point of the binder resin, pulverized, and classified. Method of manufacturing color toner.