JPH0728277A - Electrostatic charge image developing toner and its production - Google Patents

Abstract

PURPOSE:To produce an electrostatic charge image developing toner contg. carbon black, capable of ensuring the desired amt. of electric charges, having superior electric charge exchange ability, maintaining a sharp electric charge distribution even after replenishment, hardly causing sticking to a background part, excellent in durability and having stability of image quality. CONSTITUTION:This electrostatic charge image developing toner contains carbon black whose particle size distribution has at least one peak in a range of <=0.03mum and at. least one peak in the range of 0.4-0.7mum. This toner is produced by adding a bonding resin and carbon black to water and kneading them under the condition of (shear rate) X (kneading time) >=10,000.

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 manufacturing method thereof.

[0002]

2. Description of the Related Art In electrophotography, a photoconductive substance is used to form an electrostatic latent image on a photoconductor, the latent image is developed with toner, and the toner image is transferred onto paper or the like, and then heated. Alternatively, a solvent vapor is applied and fixed to obtain a copy image (US Pat. No. 2,297,691, Japanese Patent Publication No. 42-2391).
No. 0 and Japanese Patent Publication No. 43-24748). As a method for visualizing an electrostatic latent image with toner, a magnetic brush method (see US Pat. No. 2,670,403), a cascade method (see US Pat. No. 2,616,552), a powder cloud method (US Pat. No. 2,221,776) (See the book) etc. are known.

As the electrophotographic developer, a two-component developer in which a toner and a carrier are mixed is widely used. The toner is obtained by adding colorants such as carbon black and phthalocyanine blue to resins such as polystyrene, styrene-butadiene copolymer and polyester resin, melt-kneading, and then pulverizing and classifying to a particle size of 1 to 30 μm. obtain. Also,
Does the carrier have an average particle size that is approximately the same as the toner particle size?
Glass beads having a particle size of up to 0 μm, particles of iron, nickel, ferrite, etc., or obtained by coating these particles with various resins, or magnetic powder is melt-kneaded with the resin, crushed and classified. Get

Conventionally, carbon black has been used as a colorant for black toner, but the dispersibility of carbon black has a great influence on the chargeability of the toner. No. 3-18862), and defining the particle size range of the carbon black agglomerates (see Japanese Patent Application Laid-Open No. 2-103561).

[0005]

However, it is not possible to achieve both chargeability and charge exchangeability simply by making the dispersion particle diameter and the aggregate particle diameter of carbon black uniform, and in particular, the number of copies is increased. If so, there are problems that the copy density cannot be obtained and that the toner adheres to the background portion. Therefore, the present invention solves the above-mentioned problems, can secure a desired charge amount, has excellent charge exchange properties, has a sharp charge distribution even after the addition of toner, and has a toner on a background portion. It is intended to provide an electrostatic image developing toner containing carbon black, which has extremely little adherence, excellent durability, and image quality stability, and a method for producing the same.

[0006]

The present invention provides a toner for developing an electrostatic image containing a binder resin and carbon black, wherein the particle size distribution of the carbon black is 0.03 μm or less and 0.4 to 0. At least 1 in the range of 0.7 μm
A toner for developing an electrostatic charge image having two peaks, and a method for producing the toner for developing an electrostatic charge image as described above, wherein water is added to a binder resin and carbon black, and a condition satisfying the following formula is satisfied: The method for producing an electrostatic charge image developing toner is characterized by kneading with. γ × T ≧ 10000 (where γ is the share rate represented by the following formula, T is the kneading time) γ = π × D × N ÷ (h × 60) (where D is the diameter of the rotor) (Mm), N is the rotor speed (rpm), h is the tip clearance (m
m))

[0007]

The inventors of the present invention have earnestly studied carbon black-containing black toner which has both charge amount and charge exchangeability. As a result, the primary particle size distribution of carbon black has a peak of 0.03 μm or less. The aggregate peak is 0.4
By dispersing carbon black in the toner in the range of up to 0.7 μm, it is possible to achieve both a charge amount and charge exchangeability, excellent image quality, little toner adhesion to the background, and durability. The inventors have found an excellent black toner and completed the present invention.

The carbon black used in the present invention is p
It is suitable that H is 3 or less, the primary particle diameter is 20 nm or less, and the dibutyl phthalate oil absorption is 80 cc / 100 g of carbon black. If the pH of the carbon black exceeds 3 or the primary particle size exceeds 20 nm, a sufficient charge cannot be obtained, and if the dibutyl phthalate oil absorption is less than 80 cc / 100 g of carbon black, the agglomerates are not formed well. , Which causes a loss of charge exchange.

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

In the present invention, the dispersed particle size and the primary particle size of carbon black are 4500 with a transmission electron microscope.
A photograph magnified up to 30,000 times was taken and measured. In addition, the oil absorption of dibutyl phthalate is ASTEM-D241.
In 4, the pH is as measured by ASTEM-D1512.

In the black toner of the present invention, 0.2 to 2% of water is added to the above carbon black and the binder resin to adjust the value of (share rate) × (kneading time) to 10,000 or more. It is preferable to knead with a continuous mixer. Here, the share rate γ means the rotation speed N (rpm) of the rotor of the kneading machine, the tip clearance h (mm),
When the rotor diameter is D (mm), it can be expressed by γ = π × D × N ÷ (h × 60) (sec ⁻¹ ), and the kneading time T (sec) is T in the case of a continuous mixer. = (Volume of kneading part) / (supply amount) Note that (share rate) × (kneading time) is represented by γT. The amount of water added is 0.5 to 2.0 wt.
%, Preferably 0.7 to 1.3 wt%. 0.5w
If it is less than t%, the share is less likely to be applied and the dispersion tends to be insufficient. On the other hand, if it exceeds 2.0 wt%, poor kneading tends to occur, and the carbon dispersion may deteriorate.

[0012]

The present invention will be described in more detail below with reference to parts by weight, but the present invention is not limited thereto. [Example 1] Styrene-butyl acrylate copolymer 84 parts by weight (blending ratio 85:15, Mn = 3000, Mw = 300,000) Carbon black 10 parts by weight (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 components were kneaded by adding 1% of water with a continuous mixer. The temperature of the kneaded product at that time was 130 ° C.
T was 12550. Where 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 Styrene-butyl acrylate copolymer 83 parts by weight (blending ratio 85:15, Mn = 3000, Mw = 300,000) Carbon black 10 parts by weight (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. The temperature of the kneaded product at that time was 135 ° C., and γT was 10812. Here, D = 51.8 mm, N = 600 rpm, h
= 3.2 mm and T = 21.26 s. This was pulverized and classified by a usual method to obtain black particles having an average particle diameter of 8.8 μm. To the black particles, 0.5 part by weight of silica (particle size: 12 nm) treated with silicon oil was added 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 the raw material having the same composition as in Example 1 was used and kneading was performed in a continuous mixer without adding water. The temperature of the kneaded product 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, 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 product 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, T = 10.33s.

[Comparative Example 3] In Example 1, pH =
A toner was obtained in the same manner as in Example 1 except that carbon black of 8.5, primary particle size = 75 nm, dibutyl phthalate oil absorption = 70 cc / 100 g of carbon black was used. The temperature of the kneaded product in the middle was 135 ° C., and γT was 12550. Here, D = 51.8 mm, N =
It was 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 carbon black of 8.5, primary particle size = 25 nm, dibutyl phthalate oil absorption = 70 cc / 100 g of carbon black was used. The temperature of the kneaded material in the middle was 140 ° C. and γT was 12550. Here, D = 51.8 mm, N =
It was 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 of carbon black was used, and a toner was obtained in the same manner as in Example 1 except that 3% of water was added. The temperature of the kneaded product in the middle is 1
At 15 ° C., γT was 12550. Where D = 5
1.8 mm, N = 1000 rpm, h = 3.2 mm, T
= 14.8s.

(Production 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 resulting solution had an average particle size of 80 μm.
1000 parts by weight of spherical ferrite of No. 1 was added, and coating treatment was performed by a reduced pressure type kneader coater to obtain a carrier.

(Preparation of Developer) 95 parts by weight of a carrier was mixed with 5 parts by weight of each toner of Examples 1 and 2 and Comparative Examples 1 to 5 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 carry out a continuous copy test of 10,000 sheets continuously to evaluate copy density and toner adhesion to the background portion. . The copy density was measured with a Macbeth densitometer, and the toner adhesion to the background portion was determined by comparison with a 5-step sample from G1 (good) to G5 (bad).

As can be seen from Table 1, the examples of the present invention showed good results in terms of the density of the initial copy and the copies after a large number of copies, 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-mentioned constitution, since the carbon black on the small diameter side is uniformly and finely dispersed, it is possible to secure an appropriate charging property.
Since there is a large diameter carbon black aggregate, it is possible to obtain a high copy density both in the initial stage and after a large number of copies, and it is possible to consistently provide excellent image quality without adhesion to the background area. Became.

Claims (2)

[Claims] 1. An electrostatic charge image developing toner comprising a binder resin and carbon black, wherein the particle size distribution of the carbon black is 0.03 μm or less and 0.4 to 0.7 μm, respectively. A toner for developing an electrostatic charge image, which has two peaks. 2. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein water is added to the binder resin and carbon black, and the mixture is kneaded under conditions satisfying the following formula. Method for producing toner for image development. γ × T ≧ 10000 (where γ is the share rate represented by the following formula, T is the kneading time) γ = π × D × N ÷ (h × 60) (where D is the diameter of the rotor) (Mm), N is the rotor speed (rpm), h is the tip clearance (m
m))