JPH02154277A - Toner for developing electrostatic images - 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 [Technical Field] The present invention relates to a toner for developing an electrostatic image, particularly a dry toner for developing an electrostatic image whose charge is controlled to be negative.

[Prior art]

Conventionally, in dry toners, desired chargeability cannot be obtained by simply dispersing colorants such as dyes and *colorants in a binder resin, and an appropriate amount of a charge control agent has been added. Metal-containing dyes such as chromium-containing monoazo complexes and chromium-containing salicylic acid complexes can be used to impart negative charge to toner, but their charge control properties are insufficient and it is difficult to obtain a sufficient amount of charge by using them alone. In particular, in a method in which toner is developed by forming a thin layer, such as a -component development process, it is difficult to obtain a sufficient band 'Iuffi. Furthermore, when a toner containing a salicylic acid metal salt and/or a salicylic acid derivative metal salt disclosed in JP-A-62-145255 is used in the above process, it is possible to obtain the required amount of charge, but the stability of the toner There were problems such as adhesion to the developing roller, and there were still unsatisfactory points.

〔the purpose〕

The present invention overcomes the conventional drawbacks, provides stable negative charge control over a long period of time, provides stable images at all times, and in particular does not cause filming on the developing sleeve or photoreceptor even after long-term continuous use. An object of the present invention is to provide a one-component to two-component dry toner for developing electrostatic images.

〔composition〕

As a result of intensive research to achieve the above object, the present inventors have found that in a toner comprising at least a binder resin and a colorant, (i) a metal salt of salicylic acid and/or a metal salt of a salicylic acid derivative as a charge control agent; It has been found that the above object can be achieved by providing an electrostatic image developing toner characterized by containing (it) a chromium-containing monoazo dye.

The metal salt of salicylic acid or a salicylic acid derivative used as a charge control agent in the present invention can be represented by the following general formula (1).

(However, R1, R2 and R3 are hydrogen or have 1 to 10 carbon atoms.
is an alkyl group or an aryl group, and an alkyl group or an aryl group having hydrogen or carbon atoms of 1 to 6 is particularly preferable.

Here, R1, R'' and R3 may be the same or different at the same time. Me is any metal selected from zinc, nickel, cobalt, button, and chromium, and zinc is particularly preferred.) The metal salt represented by the general formula is CLARK.

J, L., Kao, H. (1948) J., Amer, C.
hem, Soc, 70, 2151. For example, 2
A zinc salt can be obtained by adding and mixing 1 mol of sodium salicylic acid salt (including sodium salts of salicylic acid derivatives) and 1 mol of zinc chloride, followed by heating and stirring. This metal salt is a white crystal and does not show any coloring even when dispersed in a toner binder. Metal salts other than zinc salts can also be produced according to the above method. These metal salts may be used alone or in combination of two or more.

The basic skeleton of the chromium-containing monoazo dye used in combination with salicylic acid or a metal salt of a salicylic acid derivative represented by the general formula (1) is represented by the following general formula (ii).

In the above general formula (■), (A) to (D) represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group, a halogen atom, etc., and each may be the same or different, and further, There may be two groups other than hydrogen atoms substituted on each benzene ring. Furthermore, Xo represents a hydrogen ion, a sodium ion, a potassium ion, an ammonium ion, an aliphatic ammonium ion, or the like.

As mentioned above, it is not clear why a single toner containing a combination of the above two types of compounds can solve the purpose, but by containing a metal salt of salicylic acid and/or a metal salt of a salicylic acid derivative, the toner can be given a high negative chargeability. Furthermore, by containing a chromium-containing monoazo dye, the highly negative chargeability is stabilized even during long-term continuous use, and the toner itself is prevented from firmly adhering to the developing sleeve and photoreceptor. However, it is thought that it will be effective in maintaining a stable image at all times.

The mixing weight ratio of the metal salt of salicylic acid or salicylic acid derivative represented by the general formula (1) and the chromium-containing monoazo dye represented by the general formula (ii) is generally 1:9 to 9:
1 is appropriate.

Further, the amount of the charge control agent consisting of a combination of these added to the toner is generally 0.5 to 10% by weight.

As the binder resin used in the present invention, all binder resins that have been used hitherto as binder resins for toners can be used. Specifically, polystyrene, styrene-acrylic acid copolymer,
Including styrene resins such as styrene-methacrylic acid copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, and styrene-butadiene copolymer, saturated polyester resin, unsaturated polyester resin, Examples include epoxy resin, phenol resin, maleic acid resin, coumaron resin, chlorinated paraffin, xylene resin, vinyl chloride resin, polypropylene, and polyethylene. It goes without saying that two or more of these binder resins may be appropriately mixed and used. Among these, it is advantageous to use polystyrene, styrene resin, and epoxy resin.

In addition to the above-mentioned components, the toner of the present invention contains various plasticizers (dibutyl phthalate, dioctyl phthalate, etc.), resistance adjusters ( It is also possible to add auxiliary agents such as tin oxide, lead oxide, antimony oxide, etc.).

Furthermore, in the present invention, toner particles (5 to 20 μn+)
After the production of Tie□, 1120. The fluidity of the toner is improved by adding fine powders such as , Sin, etc. and coating the surface of the toner particles, and the deterioration of the photoreceptor is prevented by adding zinc stearate, phthalic acid, etc. It is also effective to do so.

As described above, the toner of the present invention is a one-component type fJ1. It can be used as a ff1R agent.

It can be used as a normal one-component toner by adding and dispersing a magnetic material (such as magnetite powder), and it can also be mixed with a carrier and used as a two-component developer.

As a carrier, a core material with a particle size of about 50 to 300 μm (
Styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, acrylic ester polymer, methacrylic ester polymer, silicone resin, A coating coated with polyamide resin, ionomer resin, polyphenylene sulfide resin, or a mixture of these resins is used.

In particular, when a specific metal salt (a compound such as a zinc salt of salicylic acid and/or a zinc salt of a salicylic acid derivative) is added to the toner of the present invention, it is possible to obtain a more desired amount of the metal salt. From the top of giving stable negative charge,
As the coating resin for the carrier, it is advantageous to use a silicone resin or a silicone resin in which conductive fine powder is dispersed.

The amount of toner used is generally 1 to 10 parts by weight per 100 parts by weight of the carrier.

EXAMPLES The present invention will now be explained in more detail with reference to the following Examples, but the present invention is not limited thereto.

Example 1 Polystyrene 86 carbon black 10 was coarsely ground using a chromium-containing monoazo dye mill. The obtained fine powder is divided into 5 parts.
A toner was obtained with a particle size of ~20 μm.

3.5 parts of this toner and 100 parts by weight of a carrier (spherical ferrite powder having a silicone coat layer with a thickness of about 1 μm and a particle size of about 100 μm) were mixed to prepare a two-component dry developer. The charge amount of this by blow-off method is -21.5(
μc/g).

When this developer was used for development with Coby FT5050 manufactured by Ricoh, a clear image without fogging was obtained.

Furthermore, even though 100,000 sheets were continuously copied, the image quality did not change and good quality was maintained. Furthermore, the amount of charge at this point was -20.8 (μc/g).

Example 2 In Example 1, using chromium salt instead of zinc salt,
Further, a chromium-containing monoazo dye was added to the above-mentioned binding margin (ii), (^) part: cn- (p position) (B) part: -0CH3 (o
position) (C) part: CQ''-(p position) (D) part: -0CR
A two-component dry developer was prepared in the same manner as in Example 1 except that the number was replaced with No. 3 (position 0). The amount of charge measured by the blow-off method was -19.5 (μc/g). When similar evaluations were conducted using this developer, clear images were obtained, and even after 100,000 sheets were continuously copied, the image quality did not change and good quality was maintained. The 4F current amount at this point was -18.8 (μc/g).

Comparative Example 1 A two-component dry developer was prepared in the same manner as in Example 2, except that the chromium-containing monoazo dye was not contained.

The charge amount of this by blow-off method is -17.1 (μc/
g). A clear image was obtained by the same method using this developer.

Further, when 50,000 copies were made continuously, no change in image quality was observed, but at the time of 100,000 copies, toner staining occurred on the background portion.

Comparative Example 2 Same as Example 2 except that 3,5-ditertiary-butylsalicylic acid chromium salt was not contained and the chromium-containing monoazo dye used in Example 2 was contained in an amount of 3 parts by weight. A two-component dry developer was prepared.

The charge amount of this by blow-off method is -18.0 (μc/
g). A clear image was obtained by the same method using this developer.

A further 50,000 copies were made continuously.

No change in image quality was observed, but too, oo.

At the time of printing, toner staining occurred on the background area.

Example 3 100 parts by weight of the toner prepared in Example 1 was thoroughly mixed with 0.2 parts by weight of colloidal silica using a Henschel mixer to obtain a one-component toner.

When this toner was used to produce an image using an electrophotographic copying machine that uses a touchdown development method (Ricoh's reversal developing machine Miricopy M-5), the amount of toner charge on the developing sleeve was -16.2 (μc/g). ), clear images with no fog were obtained. Even if you make so many copies continuously,
No deterioration in copy quality was observed (value of toner charge amount here.

(This value was determined from the amount of charge flowing when suctioned from above the developing sleeve and the weight of suctioned toner).

Comparative Example 3 As in Example 3, 0.2 parts by weight of colloidal silica was sufficiently mixed with 100 parts by weight of the toner prepared in Comparative Example 1 using a Henschel mixer to obtain a toner. When this toner was evaluated in the same manner as in Example 3, it was found that the toner band was 1ft.
is -14.0 (μc/g), a clear image can be obtained, and 3
At the time of continuous copying of 0,000 sheets, the image was the same as at the start, but at the time of continuous copying of 0,000 sheets, toner was filmed on the developing sleeve and streaks appeared on the image.

Comparative Example 4 0.2 parts by weight of colloidal silica was added to 100 parts by weight of the toner used in Comparative Example 2 using a Henschel mixer in the same manner as in Example 3, and six toners were prepared into a toner using the same method as in Example 3. When evaluated, the toner charge amount was -10.0 (μc/g) and a clear image was obtained.
At the time of continuous copying of 0,000 sheets, the amount of charge was -4.0 (μc/
g), and toner began to adhere to the background.

〔effect〕

By containing the two types of compounds shown in the claims as charge control agents in 1-Q, a stable charge amount is maintained even during long-term use, and the toner on the developing sleeve, photoreceptor, etc. Since filming does not occur, stable images can always be maintained.

Claims (1)

[Claims] 1. A toner comprising at least a binder resin and a colorant, which contains (i) a metal salt of salicylic acid and/or a metal salt of a salicylic acid derivative, and (ii) a chromium-containing monoazo dye as a charge control agent. A toner for developing electrostatic images.