JPS62119548A - Electrophotographic toner - Google Patents

Abstract

PURPOSE:To reduce fogging and scattering of a toner by mixing a resin with a mixture of an electrostatic charge imparting material and a hydrophobic silica, and then, melting and kneading said material, said silica, and said binder. CONSTITUTION:The electrostatic charge imparting material can be uniformly dispersed into the binder resin powder by mixing the hydrophobic silica with said material pulverized into <=5mum diameter to prevent agglomeration of said material and improving fluidity. The silica attaches to the surface of each particle of the material, and functions like ball bearings because of its small size, enhancing fluidity of the material and contributing to uniform dispersion of the material, thus permitting stains in the device due to scattering of the toner to be reduced, and superior printing performance without fogging to be exhibited.

Description

[Detailed Description of the Invention] [Summary of the Invention] A charge imparting agent and hydrophobic silica are mixed in a stage in which a binder resin is mixed,
The toner for electrophotography is manufactured by melting and kneading the toner, which reduces fog and toner fly (111).

[Industrial application field]

The present invention relates to an electrophotographic toner, and more particularly to an electrophotographic toner with less fog and less toner scattering.

[Conventional technology and problems]

Conventional toner for electrophotography (I finely crush the materials such as IIj agent, binder resin, coloring agent, etc. ↑5), mix at an appropriate mixing ratio, stir, and then mix. It was produced by melting and mixing in a kneader, cooling, and then crushing and classifying.
If the dispersibility of the charge H'j in the binder resin is poor during mixing (heating and kneading), the individual toner particles 6Z, l,
This causes a variation in the amount of J”P agent.
- Fogging and toner scattering are likely to occur due to variations in toner specific charge depending on the individual toner. Since the viscosity of the binder resin ' during heating lIi kneading was high, it was difficult to uniformly disperse the charge imparting agent11.

Therefore, an object of the present invention is to uniformly disperse a charge-imparting agent in a binder resin, to reduce variations in toner specific charge, and to provide an electrophotographic toner with less scattering and toner scattering.

[Failure to solve the problem]

] - According to the present invention, the problem is that the charge imparting agent and the hydrophobic 1?
A toner for electrophotography, characterized in that after mixing 1 and 11 parts, a binder resin is mixed therein, and then the particulate material, hydrophobic silica, and a binder resin are melt-kneaded. , lmi is solved.

In other words, the present invention takes advantage of the fact that by mixing hydrophobic silica with a charge imparting agent pulverized to 5 μm or less, it is charged, the agent is deagglomerated, and fluidity is improved, and the charge imparting agent is mixed into a binder resin powder. It is made to be uniformly dispersed.

In this case, the hydrophobic silica adheres to the surface of each charge imparting agent, and since its particle size is small, it acts like a ball/blank, improving the fluidity of the charge imparting agent and increasing the uniformity of the charge imparting agent. It is considered that

Electronic toner is usually charged by the friction of a carrier material (carrier) such as iron powder, etc. is called the toner specific charge.Toner with a low specific charge:: Since the electrostatic attraction with the carrier is small, the toner has a low electrostatic attraction with the carrier in the developing device. , there is a problem that the toner is blown away and the area around the developing device is l'j, and that a mist of T→・- is deposited on the printed background area, causing a smearing phenomenon.On the other hand, the toner specific gravity is 6; Toners with high toner ratios have the problem of making it difficult to increase the print density. Therefore, if toners with low toner specific charges and toners with high toner specific charges are mixed, the above problems are likely to occur, and the variation in toner specific charges is desired to be small.

However, there is currently no known reliable method for measuring variations in toner specific charge. What is generally called the 1-ri m-specific charge is the average value of the 1-li-1 specific gravity 4::f of the entire toner, ignoring variations in the 1-li'- and IL charges. Therefore, the present inventors estimated the variation in toner specific charge using the method shown below.In general, toner has a charge (
As shown in Figure 1, when a charge imparting agent is added, the to-no-specific charge increases as the amount of the charge imparting agent increases;
When the amount of the charge imparting agent added exceeds a certain value, the toner specific charge tends to be saturated. Therefore, it is considered that when a charge imparting agent is contained in an individual toner in an amount exceeding a certain amount, the specific charge of the toner hardly becomes high. Therefore, as shown in FIGS. 2A and 2B, when the variation in the amount of charge imparting agent among individual toners is large, the average toner specific charge becomes smaller than when the variation is small. For the above reasons, in the case of toners having the same composition, by measuring the average toner specific charge, it is possible to infer variations in the toner specific charge.

Example 1 Nigrosine dye (oil black BY) as a charge imparting agent
, Orient Kagaku Kogyo @), and pulverized with a Gento mill (PJM crusher, Nippon New Matisoku Kogyo @), and the results were fi+'+white and -2 below Fiptm. Next, add 0.9 g of hydrophobic 1 raw silica (RO5IL 17972, 1 bottle of Ael': 1 silica), 2 pieces of polyethylene
01, and then add the dye into it: IO
+l I+? +h and ball milled for 30 minutes. Next, as a binder resin - ζ epoxy resin (Epicron 40
60.Using a human "Ippon Ink Kagaku Kogyo■)", it was ground with a Rotoplex grinder (Albine), and then re-pulverized with a jet mill to obtain particles of 20 pm or less.Next, dye 300 mixed with hydrophobic silica was ground. g, 9,400 g of the above epoxy resin powder, and a new carbon blank (Branokbars, Kinakobot Co., Ltd.) 3001 (ball milled for 30 minutes using a bot. The obtained ?fX compound was
The mixture was kneaded for 1 hour using a pressure kneader (DIO-20, Todide Seisakusho) heated to 00°C. After kneading, the cooled toner mass is crushed into 0.1 to 1 m by a Rotoplex pulverizer.
The coarse toner was prepared as follows. The obtained Ill toner was finely pulverized using a jet mill, and the pulverized product was classified using an air classifier (Albine Co., Ltd.) to obtain a toner with a diameter of 5 to 20 μm. This l・ner and 1′-p rear are iron powder (
fil? A developer consisting of V250 (manufactured by Nippon Steel Powder) was adjusted to a toner concentration of 4%, and printing was performed using an F-671500 laser printer (manufactured by Fuji JM). Note that the toner specific charge at this time was 16 μc/g. As a result of the printing test, clear printing without fogging was obtained up to 100,000 sheets, and at the same time, there was almost no staining inside the device due to toner scattering.

Example 2 A printing test was conducted using N1psil 5S-50 (Rohon Silica T-gyo ■) as the hydrophobic silica, and using a toner in the same manner as in Example 1 except for the above. The results were the same as in Example 1.

Example 3 A toner was prototyped in the same manner as in Example 1 except that AERO5IL R8]1 (Nippon Aerosil (■)) was used as the hydrophobic silica, and a printing test was conducted.The results were the same as in Example 1. Ta.

Comparative Example I A toner was experimentally produced in the same manner as in Example 1 except that no liquid was used.

Comparative Example 2 A toner was produced in the same manner as in Example 1, except that the particle size of the nigrosine dye used in Example 1 was 10 μm or less (including 5 μm or more).

Comparative Example 3 Example 1 except that an epoxy resin (Epicron 7IO [io, manufactured by Dainippon Ink & Chemicals, Ltd.) pulverized into 301 zm or less (including 2071 m or more] -) was used.
In the same way, we made a prototype of Tosu・-.

Comparative Example 4 Before melt-kneading, mix and mix Evo 1-shi resin (Epicron 4060) and Nige 1:I Shin Somesaiko 1.
A prototype was made in the same manner as in Example 1, except that the test was not carried out.

Table F shows the results of four types of 1/J-1 1/1 charges and printing tests produced as comparative examples.

From the above results, it was found that the toners of the four types of comparative examples had lower toner specific charges than the toners of the two types of examples.

Since the toner composition is the same in both Examples and Comparative Examples, the dispersibility of the charge-imparting agent in Comparative Examples is poorer.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to reduce the variation in toner specific charge, so that there is less dirt inside the device due to toner scattering, and excellent printing performance without fogging can be exhibited.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the amount of charge imparting agent added and the specific charge of the toner, FIG. 2A is a graph showing the relationship between the charge imparting agent content l and the number of toner particles, and FIG. 2B is a graph showing the relationship between the amount of charge imparting agent added and the toner specific charge. 7 is a graph showing the relationship between toner specific charge and the number of toner particles. Addition amount of charge imparting agent Figure 1 Content of charge imparting agent Figure 2A

Claims (1)

[Claims] 1. A charge imparting agent and hydrophobic silica are mixed, a binder resin is mixed therein, and then the charge imparting agent, hydrophobic silica, and binder resin are melt-kneaded. Toner for electrophotography. 2. The electrophotographic toner according to claim 1, wherein the charge imparting agent has a particle size of 5 μm or less. 3. The electrophotographic toner according to claim 1, wherein the hydrophobic silica has a particle size of 1 μm or less. 4. The electrophotographic toner according to claim 1, wherein the binder resin has a particle size of 20 μm or less.