JPH06295104A - Electrophotographic developer - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a developer for electrophotography, which prevents filming on the surface of a carrier and a photoconductor and has good triboelectric charging characteristics of toner and image quality when copying a large number of sheets. The purpose is to [Structure] A toner containing a binder resin and a silicone resin, and N- [3- (trimethyoxysilil)
and a magnetic carrier coated with a silicone resin containing Benzenamine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic developer for developing an electrostatic charge image formed by electrophotography, electrostatic printing, electrostatic recording or the like.

[0002]

2. Description of the Related Art Conventionally, as charge control agents used in toners constituting electrophotographic developers, metal-containing dyes such as azo metal complex salts and chromium complex salts for negatively chargeable toners, and positively charged toners. Examples of suitable toners include nigrosine dyes and quaternary ammonium salts. These charge control agents are melt-kneaded together with a binder resin, a colorant, a fixing offset preventive agent, etc., and then pulverized and classified to an average particle size of about 5 to 15 μm to be a toner and contained in the toner.
However, most of the above charge control agents are in the raw material stage before being made into toner, and the primary particle diameter thereof is the toner particle diameter or more. For this reason, the charge control agent itself is pulverized in the pulverizing and classifying step and mixed into the toner as a single substance, the charge control agent is dispersed unevenly in individual toner particles, or mixed with the carrier. There was a phenomenon in which the charge control agent was detached from the toner particles. Due to such a phenomenon, the triboelectric charge distribution becomes broad and the triboelectric charging characteristics become unstable, and the charge control agent filmed on the carrier or the surface of the photoconductor to improve the triboelectric chargeability of the toner to the carrier. As a result, the problems occur that the image density becomes low and background fog occurs while making a large number of copies. In particular, in toners that can be fixed at low temperature and low pressure due to the recent energy saving, use a low-molecular weight binder resin or a soft-viscosity binder resin such as a binder resin having a low glass transition temperature and a low softening point. Therefore, the above phenomenon appears remarkably, and improvement of the above problems has been strongly demanded.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional electrophotographic developer, prevents filming on the surface of the carrier and the photosensitive member, and allows toner to be used when copying a large number of sheets. The present invention provides an electrophotographic developer having good triboelectric charging characteristics and image quality.

[0004]

The present invention relates to a toner containing a binder resin and a silicone resin, and N- [3- (tr
imoxyxysil) propyl] -Ben
A developer for electrophotography, which comprises a magnetic carrier coated with a silicone resin containing zenamine.

The silicone resin contained in the toner constituting the present invention is a silicone resin having a polysiloxane structure as the main chain of its constituent molecules. A typical example of such a silicone resin is the following general formula (1). And a polysiloxane structure represented by Further, it may contain an organopolysiloxane having a three-dimensional network structure having a Si—O—Si bond as a main chain as represented by the general formulas (2) and (3). Furthermore, in order to improve properties such as triboelectrification characteristics, compatibility with the binder resin, and fluidity of the resin, a modified silicone resin may be used if necessary. By thus containing the silicone resin in the toner, there is an effect that the triboelectricity with the carrier is improved.

[0006]

[Chemical 1]

[0007]

[Chemical 2]

[0008]

[Chemical 3]

The content of the silicone resin in the toner is preferably 1 to 10% by weight. When the content of the silicone resin is less than 1% by weight, it is difficult to maintain the triboelectric charging property of the toner well, and it is difficult to obtain the releasing effect on the heat fixing roller, and when the content is more than 10% by weight, the fixing strength of the toner on the transfer paper is high. Is insufficient and the cost increases.

As the binder resin contained in the toner, styrene resin, styrene-acrylic acid ester copolymer resin, styrene-butadiene copolymer resin, polyester resin, epoxy resin and the like can be used. In addition, a silicone resin may coexist with a monomer during the synthesis of the binder resin and polymerized to be used as the binder resin component of the toner. As other constituent components of the toner constituting the present invention, a colorant,
A charge control agent, and other additives as required, are included.The toner is prepared by mixing these materials with the silicone resin and the binder resin in a desired composition, melt-kneading, cooling, solidifying and pulverizing. Obtained by classifying. Further, it may be obtained as a so-called polymerization method toner prepared by mixing the above-mentioned material and a silicone resin at the time of polymerization of the binder resin. Examples of colorants include carbon black, monoazo red pigments, disazo yellow pigments, quinacridone magenta pigments, anthraquinone dyes, and the like, and charge control agents include nigrosine dyes, quaternary ammonium salts, and monoazo metals. Complex salt dyes and the like can be mentioned. Other additives added as necessary include polyolefins such as polypropylene as a release agent, and hydrophobic silica and colloidal silica as a fluidizing agent.

Further, since the present invention has a remarkable effect on an electrophotographic developer using a toner which can be fixed at a low temperature and a low pressure, the melting start temperature of the toner is 100.
It is preferable to set the temperature to not more than ° C. The melting start temperature in the present invention means a value measured by the following measuring machine and measuring conditions. The melting start temperature refers to the temperature at which the plunger starts to fall. Measuring instrument; Shimadzu's advanced flow tester CF-500 Measuring condition: Plunger: 1 cm ² Die diameter: 1 mm Die length: 1 mm Load: 20 KgF Preheating temperature: 80 ° C Preheating time: 300 sec Temperature rising rate: 6 ° C / min

In order to set the melting start temperature of the toner to 100 ° C. or lower, it is preferable to use a silicone resin having a low softening point. It is also effective to use a resin having a low molecular weight, for example, a resin having a weight average molecular weight of 100,000 or less as the binder resin. However, when a binder resin having an extremely low molecular weight, for example, a binder resin having a weight average molecular weight of 1,000 or less is used, the amount of oligomers increases and the glass transition temperature of the binder resin component as a whole decreases, resulting in poor heat resistance after toner formation. It is particularly preferable to add a low molecular weight compound such as hydrogenated castor oil because problems occur and productivity of the binder resin is poor. Further, the glass transition temperature of all the binder resins of the toner is preferably kept at about 60 ° C. or higher due to the problem of blocking resistance.

The carrier constituting the present invention is N- [3-
(Trimethyloxysilil) propyl]-
The coating agent containing Benzenamine in the silicone resin exemplified in the toner is iron powder,
A core material is formed by coating a magnetite, a ferrite and a so-called resin carrier in which a magnetic material is dispersed in a binder resin. N- [3- (trimetho
xysilil) propyl] -Benzenami
The inclusion of ne increases the positive chargeability of the carrier in friction with a negatively chargeable toner, and in combination with the effect of the silicone resin making the toner negatively chargeable, there is no need to mix a charge control agent in the toner. However, good triboelectric chargeability can be secured. Further, a carrier using a silicone resin as a coating agent has less contamination of the carrier surface with toner than a carrier using another resin as a coating agent, and less deterioration over time due to abrasion of the coating agent. N- [3- (trim in silicone resin
ethoxysilil) propyl] -Benze
The content of namine is preferably 3 to 20% by weight. Three
If it is less than 20% by weight, it is difficult to obtain the effect of improving the triboelectrification characteristics, and if it is more than 20% by weight, the abrasion of the silicone resin increases and the moisture resistance deteriorates, which is not preferable.

[0014]

In the electrophotographic developer of the present invention, the coating agent for the toner and carrier contains a silicone resin to prevent filming on the surface of the carrier and the photoreceptor and to contain the silicone resin. Since it is difficult to obtain the necessary and sufficient triboelectrification properties by itself, N- [3- (trim
ethoxysilil) propyl] -Benze
Namine is contained so that the triboelectrification characteristics between the toner and the carrier can be favorably maintained.

[0015]

EXAMPLES The present invention will be described below based on examples. In the examples, “part” means “part by weight”. Example 1

[Chemical 4] The above raw materials were mixed with a super mixer, melt-kneaded, and then pulverized and classified to obtain negatively chargeable toner particles having an average particle diameter of 11 μm. Then, with respect to 100 parts of the toner particles, hydrophobic silica (trade name of R-97 manufactured by Nippon Aerosil Co., Ltd.) is used.
2) 0.3 part was attached to the surface by a Henschel mixer to obtain a toner. The melting start temperature of this toner is 98 ° C.
Met. The average particle size is 75 μm and the saturation magnetization is 55.
For emu / g ferrite carrier core material, N- [3- (trimethth
oxysilil) propyl] -Benzenam
The electrophotographic developer of the present invention was prepared by mixing 100 parts of the carrier coated with the coating agent prepared so that the ine content was 3% by weight with 4 parts of the toner.

Example 2 │

[Chemical 5] A toner was prepared from the above raw materials in the same manner as in Example 1.
The melting start temperature of this toner was 97 ° C. And
The core material of a ferrite carrier having an average particle diameter of 75 μm and a saturation magnetization of 55 emu / g is N- [3- (trimethoxysilil) in dimethyl silicone resin.
Propyl] -Benzenamine content is 5
The electrophotographic developer of the present invention was prepared by mixing 100 parts of the carrier coated with the coating agent prepared so as to have a weight% with 4 parts of the toner.

Example 3

[Chemical 6] A toner was prepared from the above raw materials in the same manner as in Example 1.
The melting start temperature of this toner was 96 ° C. And
The core material of a ferrite carrier having an average particle diameter of 75 μm and a saturation magnetization of 55 emu / g is N- [3- (trimethoxysilil) in dimethyl silicone resin.
Propyl] -Benzenamine content is 5
The electrophotographic developer of the present invention was prepared by mixing 100 parts of the carrier coated with the coating agent prepared so as to have a weight% with 4 parts of the toner.

Example 4 A toner was manufactured by using the same raw material and manufacturing method as in Example 3. Then, as a core material of a ferrite carrier having an average particle diameter of 75 μm and a saturation magnetization of 55 emu / g, N- [3- (trimethoxysil) in dimethyl silicone resin is used.
il) propyl] -Benzenamine was mixed with 100 parts of the carrier coated with the coating agent prepared so that the content thereof was 10% by weight, and 4 parts of the above toner were mixed to prepare the electrophotographic developer of the present invention.

Comparative Example 1 A comparative electrophotographic developer was prepared in the same manner as in Example 4, except that the carrier was not coated with a ferrite carrier having an average particle size of 75 μm and a saturation magnetization of 55 emu / g.

Comparative Example 2 Comparative electrophotographic development was carried out in the same manner as in Example 4, except that the carrier was replaced with a ferrite carrier having an average particle size of 75 μm and a saturation magnetization of 55 emu / g coated with dimethyl silicone resin. An agent was prepared.

Comparative Example 3 A toner was prepared from the above raw materials in the same manner as in Example 1.
The melting start temperature of this toner was 99 ° C. And
A comparative electrophotographic developer was prepared in the same manner as in Example 4 except that the above toner was used instead of the toner.

Next, a commercially available copying machine (trade name of Toshiba Corp.) using the electrophotographic developers obtained in the above Examples and Comparative Examples is used.
BD-9110) was used to conduct a continuous copy test up to 50,000 sheets, and the triboelectric charge amount, image density and background fog were measured at the initial stage and after 50,000 sheets, and the results are shown in Table 1. The copied original is of A4 size with a black portion of 10%, the triboelectrification amount is measured by a blow-off triboelectrification amount measuring device manufactured by Toshiba Chemical Co., and the image density is a reflection densitometer RD- manufactured by Macbeth. 914, and for ground fog, a color difference meter MODEL Z-1001DP manufactured by Nippon Denshoku Industries Co., Ltd. was used.

[0023]

[Table 1]

As is clear from the results shown in Table 1, Example 1
The electrophotographic developers of the present invention Nos. 4 to 4 provide good and stable triboelectrification characteristics even though no charge control agent is used in the toner, and the initial image is obtained even after the copying of 50,000 sheets. An image characteristic equivalent to the characteristic was obtained. On the other hand, in the comparative example, the image density or background fog after copying 50,000 sheets was poor. Especially N- [3- (tri
methodoxy] propyl] -Benz
In Comparative Example 2 in which a carrier coated with a silicone resin containing no enamine was used, the triboelectric charge amount was −10.6 μc / g in the initial stage and after 50,000 sheets −
It was a low value of 9.7 μc / g. Further, when the surface of the carrier and the photoconductor after the copying of 50,000 sheets was observed, filming occurred on the surface of the carrier used in Comparative Example 1, and filming also occurred on the surface of the photoconductor used in Comparative Example 3. However, the carrier and the photoconductor used in Examples 1 to 4 did not have such a phenomenon. In addition,
The surface temperature of the heat fixing roller of the copying machine was set to 160 ° C. to fix a solid image, and a cotton pad was rubbed on the solid image. It has been confirmed that the electrophotographic developer has sufficient fixing strength on the transfer paper without the toner adhering to the cotton pad. At this time, it was also confirmed that the low temperature offset did not occur, and it was also confirmed that the high temperature offset did not occur even if the solid image was fixed by setting the surface temperature of the heat fixing roller to 200 ° C.

[0025]

EFFECT OF THE INVENTION The electrophotographic developer of the present invention has an effect that the toner has excellent triboelectric charging characteristics and image quality even if it does not contain a charge control agent, and there is no problem with other characteristics such as fixing strength. Play.

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Claims (4)

[Claims] 1. A toner containing a binder resin and a silicone resin, and N- [3- (trimethyoxysili).
1) A developer for electrophotography, comprising: a magnetic carrier coated with a silicone resin containing 1) propyl] -Benzenamine. 2. The electrophotographic developer according to claim 1, wherein the content of the silicone resin in the toner is 1 to 10% by weight. 3. The electrophotographic developer according to claim 1, wherein the melting start temperature of the toner is 100 ° C. or lower. 4. N- [3- (trimethoxy) in a silicone resin coating a magnetic carrier.
silil) propyl] -Benzenamine
The developer for electrophotography according to claim 1, wherein the content of 3 to 20% by weight.