JP3111385B2 - Manufacturing method of electrophotographic toner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing an electrophotographic toner.

(Prior Art) Conventionally, toners used in electrophotographic methods use a pigment as a colorant and a fine colored powder in which a charge control agent for controlling electric charge is dispersed in a resin as a binder. Have been. For example, in a magnetic brush developing method that is currently widely used, a two-component developer in which iron powder called a carrier and toner are mixed is used. In the case of such a two-component developer, in order to maintain good development, it is necessary to stabilize the charging performance of the toner. For this reason, it is necessary to take measures against contamination of the carrier and fluctuations in the toner concentration in the developer, and maintenance and adjustment are complicated.

On the other hand, the developed toner image is transferred from a photoreceptor to recording paper to form a permanent image, and is then called “fixing”.
Is performed. As the fixing method, there is a method of performing pressure, but generally, a method of heat is used. Among these methods of fixing by heat, the method using heat roll fixing is widely used because of simplification of the apparatus, low risk of scorching of the recording paper, and excellent adhesion of the toner to the paper. . However, in this heat roll fixing method, so-called offset is likely to occur because the toner directly contacts the heat roll.

These problems of stabilizing charging performance and offset resistance are often caused by dispersion of a binder resin, a colorant, and a charge control agent, which are toner compositions. JP-A-56-94363 discloses a ball mill / spray dryer, JP-A-56-1950 discloses a kneader, JP-A-55-539 discloses a hot roll,
Japanese Patent Application Laid-Open No. 1-50624 discloses a technique for producing a toner using an extruder.

(Problems to be solved by the present invention) However, in the kneading machine used in the above-mentioned conventional technology, the ball mill / spray dryer, the kneader and the hot roll have problems in safety and economy, and the extruder has a problem in safety and economy. Although it has solved problems such as economy, it has not been possible to obtain dispersibility enough to dramatically improve charging performance and offset resistance.

SUMMARY OF THE INVENTION An object of the present invention is to stabilize the charging characteristics of a toner by efficiently dispersing the toner composition uniformly, to provide an image of excellent quality, and to improve the prevention of offset during fixing.

(Means for Solving the Problems) The present inventors have conducted intensive studies to solve the above problems, and as a result, have reached the present invention.

That is, the present invention relates to a method for producing an electrophotographic toner containing a binder, a colorant, and a charge control agent, wherein the composition containing the binder, the colorant, and the charge control agent is rotated in directions opposite to each other. It has two-axis rotors (I) and (II), the number of blades A of the rotor (I) and the number B of blades of the rotor (II)
And kneading with a kneading machine in which the ratio of the number of rotations of the rotor (I) to the number of rotations of the rotor (II) is B: A.

 Next, the details of the present invention will be described.

The toner of the present invention is obtained by melting and heating a toner composition comprising at least a resin for a binder, a colorant, and a charge control agent by a kneader that rotates in two directions in different directions, each having a different cross section. Colorant or charge control agent is dispersed in it, and finely dispersed by high pressure air jet mill,
Classification was performed in a high-speed air stream. The cross-section of this variant rotor has a different number of rotor blades of the kneading machine, and the product of the number of blades and the number of rotations of the blades is equal, so that even if each shaft meshes, it rotates smoothly. When the specific resin is used as a binder, the colorant and the charge control agent are uniformly dispersed. The situation is the first
Shown in the figure. In FIG. 1, reference numerals 1 and 2 denote four wings,
The toner composition 3 before the kneading zone is a rotor of the blade, enters the kneading zone, is compressed (composition 4), and is sheared by the blades of the rotor 1, and becomes the toner composition 5 after kneading.

Examples of the resin for the binder used in the present invention include polystyrene, styrene-butadiene, epoxy, polyamide, polyarylene, polyester graft resins thereof, styrene- (meth) acrylate graft resins thereof, polyesters, styrene- ( (Meth) acrylic acid esters, polyester-grafted styrene- (meth) acrylic acid esters and styrene- (meth) acrylic acid ester-grafted polyesters.

These resins have a melt viscosity of 5 × 10 ⁴ PO in a temperature range of 90 to 170 ° C. from the dispersibility during kneading and the offset performance of the toner.
It shows ISE and preferably has a glass transition point of 50 to 70 ° C., and has a melt viscosity of 5 × 10 ⁴ POISE in a temperature range of 100 to 170 ° C.
And those having a glass transition point of 55 to 70 ° C are more preferable.

The colorant used in the present invention is not particularly limited, and black pigments such as carbon black and magnetite, and dyes and pigments as colorants for color can be used.

It is preferable that the binder resin used in the present invention should pass at least 5 mm mesh. That is, when a resin having a mesh size of 5 mm or more is used, the dispersion state of the toner composition deteriorates, and when the toner is formed into a toner, the charging performance is not stabilized, so-called fogging that stains the background of the image occurs, and the toner scatters from the developing machine. To stain the inside of the machine and degrade the image quality. For this reason, when using a binder resin of 5 mm or more,
It is necessary to crush the material in advance, and it is preferable that the material pass through a 3 mm mesh.

(Example) An example of the present invention will be described below. “Parts” simply means parts by weight.

Example 1 A 2-axis kneader having three rotors / four blades each having a rotor diameter of 30 mm and an L / D of 6.5 in a different direction (a kneader manufactured by Moriyama Seisakusho Co., Ltd.) CM60 ”), the rotor speed of each rotor was set to 168 rpm / 126 rpm, the kneading temperature was set to 100 ° C., and the following toner composition (toner composition 1) was supplied at 10 kg / hour and kneaded. The toner was pulverized by a jet mill and further classified by an air classifier to prepare a toner having an average particle diameter of 10 μm.

Toner composition 1 resin 93 parts of styrene / acryl graft polyester 5 × 10 ⁴ poise at 90 ° C. Glass transition point 50 ° C. Charge control agent Bontron E-84 2 parts (manufactured by Orient Chemical Co., Ltd.) Colorant KET Blue 106 CIPig.No B-15-4 (manufactured by Dainippon Ink and Chemicals, Inc.) 5 parts Example 2 In the kneading machine of Example 1, the wings of each rotor were changed to 2 wings / 3 wings, and each rotor was changed. The number of revolutions was set to 168 rpm / 112 rpm, and the kneading temperature was set to 105 ° C., and the following toner composition (toner composition 2) was melted and kneaded.
A toner having an average particle size of 10 μm was prepared in the same manner as described above.

Toner composition 2 Resin 90 parts of styrene / acryl graft polyester 5 × 10 ⁴ at 100 ° C. POSE glass transition point 62 ° C. Viscol 550P 2 parts (manufactured by Sanyo Chemical Industries, Ltd.) Charge control agent Bontron E-84 2 parts Colorant KET Red 309 CIPig.No R-122 (manufactured by Dainippon Ink and Chemicals, Inc.) 6 parts Example 3 In the kneader of Example 1, the rotation speed of each rotor was 128 rpm / 96 rpm, and the kneading temperature was 130 ° C. And the following toner composition (toner composition 3) was melt-kneaded, and a toner having an average particle diameter of 10 μm was prepared in the same manner as in Example 1.

Toner composition 3 Resin Polypropylene ester graft styrene / acrylic copolymer resin 89 parts 5 × 10 ⁴ poise at 135 ° C 63 ° C Glass transition point 63 ° C Viscol 550P 2 parts Charge control agent Bontron S-34 1 part (Orient Chemical Co., Ltd.) Colorant Carbon Black Elftex 8 (manufactured by Cabot Corporation) 8 parts Example 4 In the kneading machine of Example 1, the rotation speed of each rotor was set to 128 rpm / 96 rpm and the kneading temperature was set to 140 ° C. The toner composition (toner composition 4) was melt-kneaded, and a toner was prepared in the same manner as in Example 1.

Toner Composition 4 Resin Styrene / acrylic copolymer resin 92 parts 5 × 10 ⁴ poise glass transition at 170 ° C. 68 ° C. Charge control agent Bontron S-34 2 parts Colorant carbon black Elftex 8 8 parts Comparative Example 1 Rotor A 2-axis kneader with the same number of blades, using a PCM-30 (manufactured by Ikegai Iron Works Co., Ltd.) rotating in the same direction with a rotor diameter of 29 mm and an L / D of 25, and rotating the rotor at 200 rpm ,
The toner composition 1 was melt-kneaded at a kneading temperature of 100 ° C., and a toner having an average particle diameter of 10 μm was prepared in the same manner as in Example 1.

Comparative Example 2 The toner composition 2 was melt-kneaded at the kneading temperature of 105 ° C. using the same kneading machine as in Comparative Example 1, and a toner having an average particle diameter of 10 μm was prepared in the same manner as in Example 1.

Comparative Example 3 Toner composition 3 was melted and kneaded at the kneading temperature of 130 ° C. using the same kneading machine as in Comparative Example 1, and the average particle size was obtained in the same manner as in Example 1.
A 10 μm toner was prepared.

Comparative Example 4 Toner composition 4 was melted and kneaded at the kneading temperature of 140 ° C. using the same kneading machine as in Comparative Example 1, and the average particle size was obtained in the same manner as in Example 1.
A 10 μm toner was prepared.

The dispersion state of the toner composition, the offset performance, and the charging performance of these toners were compared in the following manner, and as a result, all the toners of the example obtained better results than the toner of the comparative example.

(Dispersion state of toner composition) The dispersion state of the toner composition was evaluated by microscopic observation. (The kneaded material is heated and dissolved on a slide glass to form a thin film, and observed at × 200) (Offset performance) Heat roll external fixing device with a load of 20 kg and a speed of 150 mm / s (Teflon / silicone is used for the upper roll / lower roll. However, in the toner composition 2, the silicone oil is applied to the upper roll / lower roll for both Examples and Comparative Examples. The offset performance was evaluated.

In the toner manufactured according to the present invention, no offset occurred even at a temperature higher than 10 ° C. as compared with the toner of the comparative example.

(Change of charge amount) Iron oxide powder (DSP-
O-58: Dowa Iron Powder Co., Ltd.) 100 parts by weight and 4 parts by weight of each toner are mixed in a 100 ml plastic container, and the mixing time is determined by a blow-off charge amount measuring device manufactured by Toshiba Chemical Co., Ltd. The change in charge amount was measured.

The toner produced according to the present invention had little change in the amount of charge due to the mixing time, and the toner had stable charging characteristics.

(Effect of the Invention) According to the present invention, the toner composition can be efficiently and uniformly dispersed, so that the charging characteristics of the toner can be stabilized to provide an image of excellent quality, and the effect of preventing offset during fixing can be provided. Is significantly improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state where a toner composition is kneaded by a kneader used in the present invention. A: 4 blade kneading rotor B: 3 blade kneading rotor C: toner composition before kneading zone D: toner composition in kneading zone E: toner composition after kneading zone

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-156759 (JP, A) JP-A-61-215557 (JP, A) JP-A-63-58356 (JP, A) JP-A-59-1985 123520 (JP, A) JP-A-59-147629 (JP, A) JP-A-57-18746 (JP, A) JP-A 47-26365 (JP, U) JP-A 60-179408 (JP, U)

Claims (2)

(57) [Claims] 1. A method for producing an electrophotographic toner containing a binder, a colorant and a charge controlling agent, wherein a binder resin passing through 5 mm mesh is used as a binder, and the binder resins rotate in opposite directions to each other. It has two-axis rotors (I) and (II), the number of blades A of the rotor (I) is different from the number B of blades of the rotor (II), and the rotation speed of the rotor (I) and the rotor ( 2. A method for producing an electrophotographic toner, which comprises kneading with a kneading machine having a ratio of B: A to the number of rotations of II). 2. A method for producing an electrophotographic toner containing a binder, a colorant, and a charge control agent, wherein a binder resin passing through 3 mm mesh is used as a binder, and the binder resins rotate in directions opposite to each other. It has two-axis rotors (I) and (II), the number of blades A of the rotor (I) is different from the number B of blades of the rotor (II), and the rotation speed of the rotor (I) and the rotor ( 2. A method for producing an electrophotographic toner, which comprises kneading with a kneading machine having a ratio of B: A to the number of rotations of II).