JPH03212650A - Two-component toner for electrophotography - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a small particle size electrophotographic two-component toner with improved flowability.

BACKGROUND OF THE INVENTION Toners used in electrophotography include two-component toners, which are used in combination with a carrier, and one-component toners, which are developed using only toner, depending on the development method. As toner is consumed, toner is replenished to the developer in the former case, and toner is replenished onto the developing sleeve in the latter case. Conventionally, various methods have been considered for toner replenishment, but in order to replenish toner smoothly in any of the methods, it is desirable that the toner has good fluidity. Also,
Toner is prone to blocking and caking during storage, which impairs image quality or, in severe cases, renders it unusable. Such a phenomenon is particularly likely to occur in toners with small particle diameters or toners produced for the purpose of lowering the fixing temperature.

For example, it has been well known that inorganic fine powder is added to toner to improve its fluidity and cohesiveness, but depending on the type of toner, mixing with fine powder may not be uniform. Fluidity increases by increasing the amount of fine powder added, but
Fixing properties are reduced. Furthermore, the fixing performance is also reduced when the toner is coated with infusible fine powder. It is known that the addition of fatty acid metal salts improves fluidity and cohesiveness, but it is not effective unless added in large amounts, and if added in large amounts, it may impair other physical properties of the toner, such as charging properties. This is often the case.

Problems to be Solved by the Invention As described above, in the conventional configuration, there was a problem in that the physical properties of the toner were impaired depending on the type of fluidizing agent and the amount added externally.

The present invention solves these problems by improving the fluidity and cohesiveness of small-particle electrophotographic toner, thereby improving replenishment and storage stability, and preventing deterioration in fixability. The object of the present invention is to provide a small particle size electrophotographic toner that provides stable and good print quality.

Means for Solving the Problem In order to solve this problem, the present invention uses a low molecular weight polyolefin pulverized to about 1/1 QO of the particle size of the toner attached to the surface of the toner. be.

Function By performing the surface treatment of the toner with the finely ground low molecular weight polyolefin in this way, the solid lubricating effect of the polyolefin still causes the toner particles to repel each other due to the strong charging property of the polyolefin. , the fluidity of the toner is improved and the cohesion is improved.

Further, there is no need to add multiple hydrophobic silicas or fatty acid metal salts to improve fluidity, and various physical properties as a toner, such as fixability and charge amount, can be maintained.

Examples (Example 1) 100 parts by weight of styrene-acrylic copolymer (manufactured by Priorytom CL Gutdeyer), carbon black (M
After mixing and stirring 6 parts by weight of Chromium-containing oil-soluble dye (Bontron S-34° Orient Kagaku Kogyo type) in a Henschel mixer,
After melting and kneading in a heating kneader, it is cooled and solidified, and then pulverized and classified using a jet pulverizer and an air classifier.
The volume-based integrated 50% diameter with a calibration distribution of 20 μm is 8
A μm toner was obtained. To 100 parts by weight of the obtained toner, 0.3 parts by weight of hydrophobic silica powder (Aerosil R-972, manufactured by Nippon Aeronol Co., Ltd.) and about 1/1 of the particle size of the toner.
00 finely ground low molecular weight polypropylene (Visco-I
V550-P, manufactured by Sanyo Chemical Industries, Ltd.) was added and mixed and stirred for 1 minute using a Henschel mixer at a rotation speed such that the peripheral speed of the blade was 25 m/s to perform surface treatment of the toner. Ta.

Two parts by weight of the obtained toner were transferred to a ferrite carrier (LC).
OO2 (manufactured by TDK) and mixed and stirred using a V-type blend to obtain a two-component developer.

(Example 2) A two-component developer was obtained in the same manner as in Example 1, except that 0.5 parts by weight of low molecular weight polypropylene was added.

(Example 3) In Example 1, instead of low molecular weight polypropylene, 1 part by weight of low molecular weight polyethylene (Sunwax LKL250 pulverized to about 1/1 oO of the toner particle size, manufactured by Sanyo Chemical Industries, Ltd.) was added. Other than that, a two-component developer was obtained in the same manner as in Example 1.

(Comparative Example 1) A two-component developer was obtained in the same manner as in Example 1, except that the low molecular weight polypropylene finely ground in Example 1 was not added.

(Comparative Example 2) A two-component developer was obtained in the same manner as in Example 1 except that 0.6 parts by weight of hydrophobic silica powder was added in Comparative Example 1.

Using the toners and developers obtained in the Examples and Comparative Examples as described above, a printing test was conducted using a laser printer equipped with a negatively charged organic photoreceptor.

The laser printer includes a photoconductor, a sleeve containing a magnet roller disposed opposite to the photoconductor, and a packet in which a developer blade and toner are mixed and charged by friction.

The writing speed is 10 pages/minute on A4 paper.

The printing results are shown in Table 11 and Table 2.

(Left below) Marks Also, regarding replenishment and storage stability, see Examples 1 to 3.
There are no problems with Comparative Example 2 and Comparative Example 1.
During the printing test, toner accumulated near the wall of the toner hopper, causing problems with replenishment.

Effects of the Invention The present invention improves the replenishment and storage stability of small-particle toner by surface-treating the toner with finely pulverized low-molecular-weight polyolefin. Even without addition, it is possible to realize an excellent two-component toner for electrophotography with a small particle size that can provide good and stable printing quality.

Claims (3)

[Claims] (1) A two-component toner for electrophotography, which is a two-component toner containing at least a resin and a colorant, and characterized in that a polyolefin is attached to the surface of the toner. (2) The two-component toner for electrophotography according to claim 1, wherein the polyolefin is low molecular weight polypropylene or low molecular weight polyethylene. (3) The volume-based integrated 50% diameter of the above toner is 7.0 to 9.
．． 0 μm, toner of 4 μm or less is 3% by weight or less, 16
2. The two-component toner for electrophotography according to claim 1, wherein the toner having a particle size of μm or more has a particle size distribution of 1% by weight or less.