JPH01310360A - Electrophotographic toner - Google Patents

Abstract

PURPOSE:To obtain a sharp distribution of an electric charge amount and humidity resistance and storage stability by incorporating a specified tin compound as a charge controller in the electrophotographic toner. CONSTITUTION:The electrophotographic toner contains one of the compounds represented by formula I in which each of R and R' is alkyl, aryl, aralkyl, cycloalkyl, or alkylene alkyl ester, each of them optionally substituted and independent of each other. Said compound serves as the negative charge controller and the toner containing it is high in specific chargeability, and good in storage stability because the said compound has a good solubility to the binder resin, thus permitting a sharp image to be stably obtained by an electrostatic recording image formation process by using the toner stored for a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to toners used for developing static latent images in electrophotography, electrostatic recording, and the like.

Conventional technology Image forming processes such as electrostatic recording and electrostatic photography that utilize static electricity are obtained by coating photoconductive substances such as selenium, cadmium sulfide, and amorphous silicon on substrates such as aluminum and paper. In the two-component development method, the toner is transferred to a carrier (iron powder, ferrite powder). etc.), and the component-based development method consists of a process in which the toner is directly charged and then applied to an electrostatic layer/image to make it visible. Note that the toner needs to be charged with a charge corresponding to the polarity of the electrostatic latent image formed on the photoreceptor, that is, either positive or negative charge.

Colored fine particles, generally called toner, are composed of a binder resin and a colorant as essential components, and other materials such as magnetic powder as required. As a method of imparting charge to the toner, it is possible to utilize the charging characteristics of the binder resin itself without using a charge control agent, but this method has poor stability over time and moisture resistance, making it impossible to obtain good image quality. A charge control agent is added for the purpose of charge retention and charge control of the toner.

The quality characteristics required for toner include chargeability, fluidity,
One example is that it has excellent fixing properties, but these quality characteristics are greatly influenced by the charge control agent used in the toner.

Charge control agents conventionally added to toners include (1) 2:1 type metal-containing acetate dyes as colored negative charge control agents (e.g., Japanese Patent Publication No. 45-26478, Japanese Patent Publication No. 41-20153;
1) Fudalocyanine pigment (e.g., JP-A-52-45931
) Also, as an example of a colorless negative charge control agent, Japanese Patent Publication No. 59-73
84 or JP-A No. 61-3149, etc.; (2) As positive charge control agents, nigrosine dyes, various quaternary ammonium salts (Journal of the Society of Electrostatics, 198
0th 41st! No. 3 P-114) are known, but toners containing these as charge control agents do not fully satisfy the quality characteristics required of toners, such as chargeability and stability over time. Known as an electrical control agent 2
Although toners containing type 1 metal acetate dyes have a certain level of charge, type 2 :1 metal acetate dyes generally have a drawback of poor dispersibility in binder resins. Therefore, the toner is not uniformly distributed in the binder resin, and the resulting toner has a poor charge distribution and lacks sharpness, resulting in images with low gradation and poor image forming ability.

Furthermore, since the 2:1 type metal-containing acetate dye has a hue centered on black, it has the disadvantage that it can only be used in toners with a limited hue based on black. An example of a nearly colorless negative charge control agent is a metal acid form of aromatic guicarboxylic acid (Japanese Patent Publication No. 59-7384), but this substance has the disadvantage that it cannot be completely colorless and has problems with its dispersibility. be. Furthermore, as a colorless negative charge control agent, there is a compound introduced in JP-A No. 61-3149, but since this compound has a low melting point, it has poor thermal stability during toner production, making it difficult to produce a stable toner. It has the disadvantage of being.

Problems to be Solved by the Invention The charge control agent has good dispersibility in the binder resin,
It is desired to develop a toner that is uniformly distributed in the toner and provides an image with high tonality.

Means for Solving the Problems The inventors of the present invention have made earnest efforts to improve the above-mentioned problems. As a result, by incorporating the compound of the following formula (1) into the toner, the charge amount distribution of the toner becomes sharp and the charge is increased. The present invention was completed by discovering that the characteristics were significantly improved.

(However, in formula (1), R and R' are each independently a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group,
Represents an aralkyl group, cycloalkyl group, alkylene alkyl ester or allyl group.

The compound (2) (1) works as a negative charge control agent, and it has good compatibility with the binder resin, and because it is included, the toner has a high specific charge amount and has good stability over time. Therefore, even if the toner is stored for a long period of time, it can provide stable and clear images in electrostatic recording image formation.

In the present invention, the formula (
Specific examples of the compound 1) include the following.

(Specific Examples of Compounds) (lO) These compounds can be synthesized by a known method, for example, by reacting residual tin sulfate with a carboxylic acid or maleic anhydride and alcohol.

As a method for producing a toner containing the compound of formula (1) above, a mixture consisting of the compound of formula (1), a colorant, and a binder resin is mixed into a binder using an apparatus capable of heat mixing such as a heating nider or two rolls. A method in which the resin is kneaded in a melted state, then cooled and solidified, and then ground to a particle size of 1 to 30μ using a grinder such as a jet mill or a ball mill.The colorant, binder resin, and compound of formula (1) are mixed in a solvent. (e.g., acetone, ethyl acetate), stirred, poured into water to re-precipitate, filtered, dried,
There is a method of obtaining the particles by pulverizing them to a particle size of 1 to 30 μm using a pulverizer such as a ball mill.

In this case, the binder resin is usually 99-65%, preferably 98-85%, the colorant is 1.0-15%, more preferably 1.5-10%, and the charge control agent is more preferably 0.1-30%. It is used in a proportion of 0.5 to 5% (all weight ratios).

Examples of colorants used in the electrophotographic toner of the present invention include carbon black, inorganic pigments such as ultramarine, CI, P
IGMENT YELLOW 1, CI, PIGM
ENT RED 9, CI, PIGMENT B
LUE 15 etc. AAA fee, CI.

5OLVENT YELLOW 93, CI, 5O
LVENT RED 146, CI, 5OLVEN
T BLUE 35, CI, DISPERSE
YELLOW 42, CI, DISPERSE RE
D59, CI, DISPERSE BLUE
Conventionally known colorants such as oil-soluble dyes such as 81 (CI is an abbreviation for color index; the same shall apply hereinafter) can be used. In addition, binder resins include polystyrene, styrene-acrylic acid copolymer, styrene-propylene copolymer, styrene-acrylonitrile copolymer, acrylic resin, styrene-maleic acid copolymer, polyvinyl chloride polyvinyl acetate, and olefin resin. , polyester resin,
Polyurethane resin, epoxy resin, etc. can be used alone or in combination.

Further, to the electrophotographic toner of the present invention, a flow agent such as silicon oxide, an antifoggant such as mineral oil, various magnetic substances for use in the -component system, a conductivity imparting agent such as zinc oxide, etc. may be added as necessary. You can.

The toner obtained in the present invention is mixed with iron powder (carrier) of, for example, about 200 sesh in a weight ratio of 3 to 8:97 to 92 (toner diiron powder) and used as a developer in the developing process in electrophotography. It is used.

The electrophotographic toner described herein has a sharper charge amount distribution and better stability over time than toners using conventional charge control agents. As a result, an image with high tonality can be obtained, and the repeatable image forming ability is extremely good.

Example The present invention will be specifically explained below using Examples.

In the examples, parts represent parts by weight unless otherwise specified.

Example 1 Styrene-butyl acrylate copolymer (binder)
100 parts low molecular weight polyethylene 3 parts C1, DISPERSE
Y [! 1.2 parts of LLOga 164 (coloring agent) The above specific example (
1.5 parts of the compound 1) was then coarsely pulverized using a coarse pulverizer, finely pulverized using a jet mill pulverizer, and further classified using an air classifier to obtain a toner with a particle size of 8 to 20μ. .

The obtained toner is mixed with about 200 mesh iron powder carrier and 3
:97 (toner: iron powder carrier) to obtain developer A. The initial specific charge amount of this developer A was measured using a 0-order blow-off charge amount measuring device, and it was -26.3μ.
c/g. Further, when this developer A was used for copying with a copying machine, a clear yellow image with excellent tonality and without interfering with the original hue of the colorant was obtained. Further, when a stability test over time (charge amount change over time test, charge amount moisture resistance over time stability test) was conducted using developer A, the results shown in Table 1 below were obtained.

Table 1 As shown in the above results, development A had extremely excellent stability over time.

The temporal stability test was carried out by the following method.

Charge amount change over time test Developer (mixture of toner and iron powder carrier) A was weighed into a plastic container, charged in a ball mill rotating at 100 rpm for 6 hours, and the charge amount of the toner was measured at each hour. Measure.

Charge amount humidity resistance and aging stability After charging in a plastic container for 1 hour using the above charge amount aging test method, the plastic container was left in an oven for 1 week in a humid atmosphere (room temperature) to test the toner. Measure the amount of charge.

Example 2 Polyester resin (binder) 100 parts Carbon blank (coloring agent) 6.0 parts Compound of the above specific example (2) 1.5 parts A mixture of the above composition was melt-mixed in a Ni-Goo adjusted to 160°C ( 10 minutes), cooled and solidified, then coarsely crushed using a coarse crusher, finely crushed using a jet mill, and further classified using an air classifier to obtain particles with a particle size of 8 to 20μ.
I got the toner.

The obtained toner is mixed with about 200 mesh iron powder carrier and 3
:97()ner:iron powder carrier) to obtain developer B.The initial specific charge amount of developer B was measured using a 0-order blow-off charge amount measuring device, and it was -17.3 μc/
It was g. Furthermore, when copies were made using a copying machine using this developer B, clear black images with excellent tonality were obtained.

Further, when a temporal stability test was conducted using developer B in the same manner as in Example 1, the results shown in Table 2 below were obtained.

Table 2 As shown in the above results, developer B had excellent stability over time.

Example 3 Styrene-acrylic acid methyl ester copolymer (binder) 100 parts Low molecular weight polypropylene 3 parts CI 5
OIVENT BIDE 111 (colorant) 1.5
1.5 parts of the compound of Example (13) The above mixture was dissolved in 1000 parts of a mixed solvent of ascent and ethyl acetate, and stirred at room temperature for 1 hour.

Next, this mixed solution was dropped into 10,000 parts of water while stirring to cause reprecipitation. The generated crystals were filtered and dried to obtain a toner with coarse particles.Then, the powder was finely pulverized using a jet mill, and further classified using an air classifier to obtain a toner having a particle size of 8 to 20 .mu.m.

The obtained toner was mixed with approximately 200 mesh of iron powder carrier at a weight ratio of 3:97 (toner m: iron powder carrier) to obtain developer C. Then, the initial ratio of developer C was determined using a blow-off charge measuring device. When the amount of charge was measured, it was -23,
It was 2 μc/g. Further, when copies were made using a copying machine using this developer C, a clear blue image with excellent tonality and without interfering with the original hue of the colorant was obtained.

Further, when a temporal stability test was carried out in the same manner as in Example 1 using Developer C, the results shown in Table 3 below were obtained.

Table 3 As shown in the above results, the stability over time of developer C was extremely excellent.

Example 4 Epoxy resin (binder) 100 parts C1 [1 ISPER5E RED 60 (colorant) 1
．． Part 2 CI DISPER5E VIOIET 17
(Coloring agent) 0.3 parts Compound of specific example (14)
2.0 parts The mixture having the above composition was melted and mixed using two rolls adjusted to 100°C, then naturally cooled and solidified.Then, the mixture was coarsely ground using a coarse grinder, and then finely ground using a jet mill grinder. The mixture was further classified using an air classifier to obtain toner having a particle size of 8 to 20 μm.

0.3 colloidal silica per 100 parts of the obtained toner
parts were mixed in a Henschel mixer. About 20 of this stuff
0Mesh iron powder carrier was mixed at a weight ratio of 3:97 (toner: iron powder carrier) to obtain a developer.

Next, the initial specific charge of this developer was measured using a blow-off charge measuring device and found to be -21.8 .mu.c/g. Further, when copies were made using a copying machine using this developer, a clear red image with excellent tonality and without interfering with the original hue of the colorant was obtained. Further, when a stability test over time was conducted in the same manner as in Example 1 using a developer, the results shown in Table 4 below were obtained.

Table 4 As shown in the above results, the development stability over time was extremely excellent.

Examples 5-20 Compounds and “colorants” shown in the “Compound” column of Table 5
A developer was prepared in the same manner as in Example 1 using the colorant shown in the column, the initial specific charge amount was measured for each of the obtained toners, and a stability test over time was conducted in the same manner as in Example 1. did.

Toners using any of the compounds showed little change in specific charge weight, and the stability of the developer over time was excellent. Furthermore, when copies were made using a copying machine, all of the developers had excellent tonality, and clear images with the original hue of the colorant were obtained.

*C12Co1orIndex, SIL:5olven
t, DIS:Disperse circle G: circle-mt, B
: Blw, R: Red, Y: Yellow
Effects of the Invention The electrophotographic toner obtained by the present invention has a sharper charge distribution, moisture resistance, and stability over time than toners using conventional charge control agents.

As a result, an image with extremely high tonality can be obtained, and it is characterized by an extremely good ability to repeatedly form images. Furthermore, since the charge control agent itself is essentially colorless, it is possible to select any colorant according to the hue required for the color toner, and it does not interfere with the original hue of the dye or pigment. Another characteristic is that there is nothing to do.

Patent applicant: Nippon Kayaku Co., Ltd.

Claims (1)

[Claims] 1. An electrophotographic toner characterized by containing a compound represented by the following formula (1) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (1) (However, formula (1) R, R' are each independently a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group,
Represents an aralkyl group, cycloalkyl group, alkylene alkyl ester or allyl group. )