JP3227627B2 - Electrostatic image developing toner and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a black toner for developing an electrostatic latent image and a method for producing the same.

[0002]

2. Description of the Related Art In electrophotography, an electrostatic latent image is formed on a photoreceptor using a photoconductive substance, developed with toner, and a toner image is transferred to paper or the like as necessary. Alternatively, a copy image is obtained by fixing by applying a solvent vapor (US Pat. No. 2,297,691; Japanese Patent Publication No. 42-2391).
No. 0 and JP-B-43-24748). Methods for visualizing the electrostatic latent image with toner include a magnetic brush method (see US Pat. No. 2,670,063), a cascade method (see US Pat. No. 2,616,552), and a powder cloud method (see US Pat. No. 2,221,776). Etc.) are known.

As a developer for electrophotography, a two-component developer in which a toner and a carrier are mixed is widely used. Toner is prepared by adding a colorant such as carbon black and phthalocyanine blue to resins such as polystyrene, styrene-butadiene copolymer, and polyester resin, melt-kneading, pulverizing to a particle size of 1 to 30 μm, and classifying. obtain. Also,
The carrier should have an average particle size approximately equal to the toner particle size.
Glass beads having a particle size of up to 0 μm, particles of iron, nickel, ferrite, or the like, or obtained by coating these particles with various resins, or by melting and kneading a magnetic powder with a resin, pulverizing and classifying. Get it.

Conventionally, carbon black has been used as a colorant for a black toner. However, since the dispersibility greatly affects the chargeability of the toner, the dispersed particle size of the carbon black can be made uniform (Japanese Patent Laid-Open Publication No. It has been proposed to specify the particle size range of the carbon black aggregate (see Japanese Patent Application Laid-Open No. 2-103561).

[0005]

The present invention SUMMARY OF THE INVENTION, in the toner for developing electrostatic images comprising a binder resin and carbon black, the particle size distribution of the carbon black is 0.03 microns m
Wherein the toner for developing an electrostatic image and the method for producing the toner for developing an electrostatic image described above have at least one peak in the range of 0.4 to 0.7 μm. 0.5 to water on carbon black
A method for producing a toner for developing an electrostatic image, characterized by adding in an amount of 2.0 wt% and kneading under conditions satisfying the following formula. γ × T ≧ 10000 (where γ is a shear rate represented by the following formula, and T is a kneading time.) γ = π × D × N ÷ (h × 60) (where D is the diameter of the rotor (Mm), N is the number of rotations of the rotor (rpm), h is the tip clearance (m
m))

[0006]

According to the present invention, there is provided a toner for developing an electrostatic image comprising a binder resin and carbon black, wherein the particle size distribution of the carbon black is 0.03 .mu. .7 μm each with at least one
The toner for electrostatic image development characterized by having three peaks, and the method for producing a toner for electrostatic image development described above, wherein water is added to the binder resin and carbon black, and the conditions satisfy the following formula: And a method for producing a toner for developing an electrostatic image. γ × T ≧ 10000 (where γ is a shear rate represented by the following formula, and T is a kneading time.) γ = π × D × N ÷ (h × 60) (where D is the diameter of the rotor (Mm), N is the number of rotations of the rotor (rpm), h is the tip clearance (m
m))

[0007]

The present inventors have conducted intensive studies on a carbon black-containing black toner having both a charge amount and a charge exchange property. As a result, the peak of the particle size distribution of the primary particles of carbon black is 0.03 μm or less. Aggregate peak 0.4
By dispersing the carbon black in the toner so as to be within a range of about 0.7 μm, it is possible to achieve both the charge amount and the charge exchange property, and the image quality is excellent, the toner is hardly attached to the background portion, and the durability is improved. They found an excellent black toner and completed the present invention.

[0008] The carbon black used in the present invention is p
Suitable are those having an H of 3 or less, a primary particle diameter of 20 nm or less, and a dibutyl phthalate oil absorption of 80 cc / 100 g of carbon black. If the pH of the carbon black exceeds 3 or the primary particle diameter exceeds 20 nm, a sufficient amount of charge cannot be obtained, and if the oil absorption of dibutyl phthalate is less than 80 cc / 100 g of carbon black, aggregates are not formed well. , Which may impair the charge exchange property.

The above-mentioned carbon black is preferably incorporated in the toner particles in an amount of 5 to 15% by weight, particularly preferably 7 to 12% by weight. If it is less than 5% by weight, a desired image density cannot be obtained, and if it exceeds 15% by weight, the conductivity becomes too large to obtain a desired charge amount.

In the present invention, the dispersed particle size and the primary particle size of the carbon black are determined to be 4500 by a transmission electron microscope.
A photograph magnified by ３０30000 times was taken and measured. The dibutyl phthalate oil absorption was ASTEM-D241.
At 4, the pH was measured with ASTEM-D1512.

The black toner of the present invention is prepared by adding 0.2 to 2% of water to the above carbon black and the binder resin, and adjusting the value of (share rate) × (kneading time) to 10,000 or more. It is preferred to knead with a continuous mixer. Here, the shear rate γ is the rotation speed N (rpm) of the rotor of the kneader, the chip clearance h (mm),
When the diameter of the rotor is D (mm), γ = π × D × N ÷ (h × 60) (sec ⁻¹ ), and the kneading time T (sec) is as follows: = (Volume of kneading part) / (supply amount). Note that (share rate) × (kneading time) is represented by γT. The amount of water added is 0.5-2.0 wt
%, Preferably 0.7 to 1.3 wt%. 0.5w
If it is less than t%, it is difficult to obtain a share, and the dispersion tends to be insufficient. On the other hand, when the content exceeds 2.0 wt%, kneading failure is likely to occur, and carbon dispersion may be deteriorated.

[0012]

EXAMPLES The present invention will be described in more detail with reference to parts by weight, but the present invention is not limited by these. [Example 1] 84 parts by weight of a styrene-butyl acrylate copolymer (compounding ratio 85:15, Mn = 3000, Mw = 300,000) 10 parts by weight of carbon black (pH = 2.5, primary particle size = 13 nm, dibutyl) Phthalate oil absorption 91 cc / 100 g carbon black) Polypropylene wax 6 parts by weight (molecular weight: 3000) The above-mentioned components were kneaded by adding 1% of water with a continuous mixer. The temperature of the kneaded material at that time was 130 ° C., and γ
T was 12550. Here, D = 51.8 mm,
N = 1000 rpm, h = 3.2 mm, T = 14.8 s
Met. This was pulverized and classified by an ordinary method to obtain black particles having an average particle size of 9.2 μm. 0.4 parts by weight of hydrophobic silica (particle size: 12 nm) was added to the black particles and mixed with a Henschel mixer to obtain a toner.

Example 2 83 parts by weight of styrene-butyl acrylate copolymer (mixing ratio 85:15, Mn = 3000, Mw = 300,000) 10 parts by weight of carbon black (pH = 2.5, primary particle size = 13 nm, dibutyl phthalate oil absorption 80 cc / 100 g carbon black Charge control agent (metal-containing azo compound) 1 part by weight Polypropylene wax 6 parts by weight (molecular weight: 3000) The above components were kneaded in the same manner as in Example 1. At that time, the temperature of the kneaded material was 135 ° C., and γT was 10812. Here, D = 51.8 mm, N = 600 rpm, h
= 3.2 mm, T = 21.26 s. This was pulverized and classified by an ordinary method to obtain black particles having an average particle size of 8.8 μm. 0.5 parts by weight of silica (particle diameter: 12 nm) treated with silicon oil was added to the black particles and mixed with a Henschel mixer to obtain a toner.

Comparative Example 1 A toner was obtained in the same manner as in Example 1 except that raw materials having the same composition as in Example 1 were kneaded using a continuous mixer without adding water. The temperature of the kneaded material in the middle was 165 ° C., and γT was 1255.
It was 0. Here, D = 51.8 mm, N = 1000
rpm, h = 3.2 mm, and T = 14.8 s.

Comparative Example 2 A toner was obtained in the same manner as in Example 1 except that the conditions were as follows.
The temperature of the kneaded material in the middle was 145 ° C., and γT was 875.
It was 5. Here, D = 51.8 mm, N = 1000
rpm, h = 3.2 mm, and T = 10.33 s.

Comparative Example 3 In Example 1, pH =
A toner was obtained in the same manner as in Example 1 except that 8.5 was used, the primary particle size was 75 nm, and the oil absorption of dibutyl phthalate was 70 cc / 100 g of carbon black. The temperature of the kneaded material in the middle was 135 ° C., and γT was 12,550. Here, D = 51.8 mm, N =
1000 rpm, h = 3.2 mm, and T = 14.8 s.

Comparative Example 4 In Example 1, pH =
A toner was obtained in the same manner as in Example 1 except that 8.5 was used, the primary particle size was 25 nm, and the oil absorption of dibutyl phthalate was 70 cc / 100 g of carbon black. The temperature of the kneaded material in the middle was 140 ° C., and γT was 12,550. Here, D = 51.8 mm, N =
1000 rpm, h = 3.2 mm, and T = 14.8 s.

Comparative Example 5 In Example 1, pH =
2.5, primary particle size = 24 nm, dibutyl phthalate oil absorption = 55 cc / carbon black 100 g was used, and a toner was obtained in the same manner as in Example 1 except that water was added at 3%. The temperature of the kneaded material in the middle is 1
At 15 ° C., γT was 12550. Here, D = 5
1.8 mm, N = 1000 rpm, h = 3.2 mm, T
= 14.8 s.

(Preparation of carrier) 10 parts of a styrene-n-butyl acrylate copolymer (compounding ratio: 80:20) was dissolved in 100 parts by weight of toluene, and the solution was treated to have an average particle size of 80 μm
Of a spherical ferrite was added, and a coating treatment was performed by a reduced pressure kneader coater to obtain a carrier.

(Preparation of Developer) To 5 parts by weight of each of the toners of Examples 1 and 2 and Comparative Examples 1 to 5, 95 parts by weight of a carrier were mixed by a V blender to obtain a developer.

(Continuous Copy Test) The above developer was applied to a copying machine (FX5031, manufactured by Fuji Xerox Co., Ltd.) to conduct a continuous copy test of 10,000 sheets, and the copy density and toner adhesion to the background portion were evaluated. . The copy density was measured with a Macbeth densitometer, and the adhesion of the toner to the background was determined by comparing it with a five-stage sample from G1 (good) to G5 (bad).

As is clear from Table 1, the examples of the present invention show better results with respect to the density of the initial copy and the copy after copying a large number of sheets and the adhesion to the background portion as compared with the comparative example. It can be seen that the maintainability is excellent.

[0023]

[Table 1]

[0024]

According to the present invention, by adopting the above structure, the carbon black on the small diameter side is uniformly and finely dispersed, so that an appropriate charging property can be secured.
Because of the presence of carbon black aggregates on the large diameter side, a high copy density can be obtained both at the initial stage and after multiple copying, and it is possible to stably provide excellent image quality without adhesion to the background. Became.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-103561 (JP, A) JP-A-5-19537 (JP, A) JP-A-59-101655 (JP, A) JP-A-2-103 144553 (JP, A) JP-A-2-291568 (JP, A) JP-A-5-34978 (JP, A) JP-A-3-149567 (JP, A) JP-A-1-304467 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 9/08

Claims (2)

(57) [Claims] 1. A binder resin and the toner for developing electrostatic images comprising a carbon black, the particle size distribution of the carbon black and the less 0.03μ m 0.4~0.7μm
Characterized by having at least one peak in each of the following ranges: 2. The method for producing a toner for developing an electrostatic image according to claim 1, wherein water is added to the binder resin and the carbon black.
A method for producing a toner for developing an electrostatic image, characterized by adding in a range of 0.5 to 2.0 wt% and kneading under conditions satisfying the following formula. γ × T ≧ 10000 (where γ is a shear rate represented by the following formula, and T is a kneading time.) γ = π × D × N ÷ (h × 60) (where D is the diameter of the rotor (Mm), N is the number of rotations of the rotor (rpm), h is the tip clearance (m
m))