JP2788935B2 - Positively chargeable toner - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positively chargeable toner used for developing an electrostatic latent image in electrophotography or electrostatic printing.

2. Description of the Related Art In general, a toner for developing an electrostatic latent image is a binder resin such as a styrene-based resin, an epoxy-based resin, or a polyester-based resin, a coloring agent such as a dye or a pigment, and a charge for imparting positive or negative chargeability. After dispersing the control agent, it is finely pulverized to an average particle size of about 10 to 15 μm and adjusted.

In addition, as a special production method, a method of applying a pigment or a charge control agent by applying a mechanochemical reaction to the surface of particles made of a binder resin, or a method of applying a pigment or a charge control agent to a monomer which is a raw material of the binder resin. A method of producing a spherical toner by a suspension polymerization reaction after dispersing the toner is also known.

Conventionally, as a charge control agent added to a positively charged toner, a nigrosine dye, a quaternary ammonium salt, a metal salt of a higher fatty acid, and the like are known.

Further, as an example in which an imidazole compound is used in a toner for developing an electrostatic latent image, use of 2-aminobenzimidazole as a negative charge control agent (JP-A-61-2170)
No. 55, No. 61-25965), a method of using vinylimidazole for the outer shell of a capsule toner (JP-A-59-187350).
JP-A-61-294461 and JP-A-62-242960, when an epoxy resin is used as a binder resin of a toner and an imidazole compound is used as a curing agent.
Publication).

Problems to be Solved by the Invention Among the conventionally known positive charge control agents, nigrosine dyes have poor charge control effect persistence and are black, so they are not suitable for color toners other than black.

A quaternary ammonium salt or a metal salt of a higher fatty acid is advantageous for a color toner because it is white or light-colored. However, since a charge control effect is inferior, a higher charge amount cannot be obtained with a small amount of addition. Was.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a positively chargeable charge control agent which is white or light-colored and is suitable for color printing, and which can provide a high charge control effect with a small amount of addition, in addition to a black printing toner.

Means for Solving the Problems The present inventors have conducted various tests and studies in view of such circumstances, and as a result, as a charge control agent, the following general formula having an alkyl group having 11 to 17 carbon atoms at the 2-position: In the case of using an inorganic acid salt or an organic acid salt of an imidazole compound represented by, it was found that it has excellent charge control performance,
The present invention has been accomplished.

Inorganic acid salts or organic acid salts of imidazole with an alkyl group at the 2-position suitable for the practice of the present invention, (designated below C ₁₁ Z) 2-undecyl imidazole, 2-heptadecyl imidazole (hereinafter C ₁₇ Z and any one with inorganic acids or organic acids Show) and 2-undecyl-4-methylimidazole (hereinafter C ₁₁ to display 4MZ), were stirred and mixed with water or solvent, precipitating the reaction product by cooling And easily obtained by filtering the crystals,
The inorganic acid salt or organic acid salt of a typical 2-alkyl imidazoles, C ₁₁ Z, hydrochloride C ₁₇ Z and C ₁₁ 4MZ, hydrobromide, sulfate, nitrate, phosphate, nitrite Phosphate, laurate, palmitate, stearate, glycolate, lactate, oxalate, malonate, succinate, adipate, maleate, fumarate, tartrate, Paranitrobenzoate, isophthalate, terephthalate, trimellitate, pyromellitic acid, etc., especially C ₁ Z hydrochloride (mp95-103
° C.], C ₁₇ Z sulfate (2: 1) [Mp80～180 ° C.], C ₁₇ Z stearate [Mp80～108 ° C.], C ₁₇ Z oxalate (1: 1)
[Mp148～154 ° C.], C ₁₇ Z oxalate (2: 1) [mp120
-152 ° C.], C ₁₇ Z Fumamu salt (1: 1) [mp140~148
° C.], C ₁₇ Z fumarate (2: 1) [Mp87～105 ° C.], C
₁₇ Z trimellitate (mp 168-177 ° C), C ₁₇ Z pyromellitate (mp 180-193 ° C.), C ₁₁ Z phosphate (mp14
4.5-146 ° C), C ₁₁ Z oxalate (mp 146-150 ° C), C
₁₁ Z fumarate [Mp120～143 ° C.], C ₁₁ Z trimellitic acid salt [Mp140～159 ° C.], C ₁₁ 4MZ oxalate [mp12
4-126 ° C) and C ₁₁ 4MZ trimellitate (mp 125-137
° C] is preferred.

The inorganic acid salt or organic acid salt of 2-alkylimidazole in the positively charged toner of the present invention is 0.1 to 0.1% in the toner.
To 10% by weight, preferably 0.5 to 5.0% by weight. When the amount of these components is small, the charge amount of the toner becomes insufficient, and when the amount is too large, the charge amount of the toner changes with time. As a result, the charge control effect becomes unstable. In the practice of the present invention, an inorganic or organic acid salt of 2-alkylimidazole is used in combination with a positive charge control agent such as a conventionally used nigrosine dye, a quaternary ammonium salt or a metal salt of a higher fatty acid. You may.

Representative of the binder resin suitable for the practice of the present invention is a copolymer resin of styrene and acrylic acid ester, other polystyrene resin, polypropylene resin, polyethylene resin, polyamide resin, polyurethane resin, phenol resin, polyester Resins, polycarbonate resins, and the like, and mixtures of two or more thereof can be used.

As the coloring agent, various known coloring agents can be used. For example, carbon black or nigrosine dye for black toner, rhodamine pigment or quinacridone pigment for red toner, copper phthalocyanine pigment or anthracene derivative dye for blue toner, and benzidine yellow for yellow toner. The use of colorants is possible.

Further, the positively chargeable toner of the present invention can be used as a magnetic toner by containing a magnetic material. The magnetic material added to the magnetic toner is a metal such as iron oxide such as magnetite, hematite, or ferrite, iron, cobalt, or nickel, or an alloy containing these. These magnetic materials preferably have an average particle size of about 0.1 to 2 μm, and the amount contained in the toner is suitably from 40 to 150 parts by weight based on 100 parts by weight of the binder resin component.

In practicing the present invention, known additives for improving image characteristics can be blended in addition to the compounds described above. For example, a fluidizing agent such as colloidal silica, an abrasive such as strontium titanate and silicon carbide, a lubricant such as metal stearate, and a conductivity imparting agent such as tin oxide can be added.

The preparation of the positively chargeable toner of the present invention can be performed by a known method. The most common method is to appropriately mix a salt of 2-alkylimidazole, a colorant, and other additives into a binder resin, and then sufficiently knead, crush, and pulverize using a hot roll, a kneader, or an extruder. And collecting particles having a particle size of 45 μm or less, preferably 4 to 20 μm, to produce a toner having an average particle size of 10 to 15 μm.

Hereinafter, the present invention will be specifically described with reference to Examples, Reference Examples, and Comparative Examples.

Reference Example 1 C ₁₇ Z12.3g (0.040 mol) of oxalic acid dihydrate 5.0 g (0.
040 mol) and 150 ml of ethanol were heated under reflux with stirring for about 10 minutes, cooled with water, and the precipitated crystals were collected by filtration, and recrystallized from ethanol to give a melting point of about 148 to 1.
C ₁₇ Z · oxalic acid (1: 1) as colorless scaly crystals at 54 ° C
13.7 g (0.0345 mol, 86% yield) of the salt were obtained.

Reference Example 2 17.8 g (0.080 mol) of C ₁₁ Z, 9.3 g (0.080 mol) of fumaric acid, 200 ml of water and 10 ml of ethanol were heated and refluxed for about 10 minutes with stirring, and then cooled with ice to precipitate crystals. It was filtered and recrystallized from a water-ethanol mixed solvent.
C ₁₁ Z · fumarate 25.1g as a colorless microcrystals, mp about one hundred and twenty to one hundred forty-three ° C. (0.074 mol, 93% yield).

Reference Example 3 Trimellitic anhydride 11.5 g (0.060 mol), water 500 ml
Into the solution consisting of C ₁₁₄
14.2 g (0.060 mol) of MZ was added little by little, and after the addition was completed, stirring was maintained at the same temperature for another 30 minutes. After completion of the reaction was cooled, and the precipitate was washed with water and filtered off, melting point of about one hundred twenty-five to one hundred and thirty-seven ° C. colorless powder C ₁₁ 4MZ. Trimellitic acid salt 22.3 g (0.050 mol,
(83% yield).

Hereinafter, inorganic or organic acid salts of various imidazole compounds were obtained by the same method.

Examples 1 to 39 and Comparative Examples 1 to 3 A styrene-acrylate copolymer resin (Fujikura Kasei Co., Ltd .: S-708F) was used as a binder resin.
Carbon black # 40 (manufactured by Mitsubishi Kasei Kogyo Co., Ltd., neutral type) [hereinafter referred to as CB] or Lionol Blue FG7330 (Toyo Ink Co., Ltd., phthalocyanine blue pigment) [hereinafter referred to as F] Use)
As the charge controlling agent, the inorganic acid salt or the organic acid salt of imidazole shown in Reference Example was used, and in Comparative Example, a commercially available white quaternary ammonium salt type positively charged charge controlling agent (Orient Chemical Industry Co., Ltd.) BONTRON P-
51), the binder resin, the colorant and the charge controlling agent are blended in the weight ratios shown in Table 1, dry-blended by a small mixer, and then heated at a temperature of 130 to 160 ° C. using a twin-screw extruder. After kneading, extruding, cooling and plate-shaped, crushed in a mortar, finely crushed while cooling using a desktop crusher, and then stainless steel mesh 44 μm
To make a sample.

1g of the sample and carrier (iron powder or ferrite)
25 g was placed in a polyethylene container (capacity: 100 ml), stirred and shaken on a rotating roll of a roll mill for 5 minutes or 30 minutes, and then the charge amount was measured using a blow-off type charge amount measuring machine.

The carrier is iron powder (DS manufactured by Dowa Iron Powder Co., Ltd.)
P-128B) or ferrite (F-1 manufactured by Nippon Iron Powder Co., Ltd.)
50) was used.

The method for measuring the charge amount is a mixture of the sample and the carrier.
200mg, blow pressure 1 kg / cm ^2, a measurement time of 25 seconds, the unit of measurement is displayed in [mu] C (10 ^-6 coulomb) per sample 1g.

The test results of Examples and Comparative Examples were as shown in Table 2.

Effect of the Invention According to the present invention, a high charge control effect can be obtained by adding a small amount of a charge control agent, and the charge control agent is white or light-colored.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-264066 (JP, A) JP-A-2-73368 (JP, A) JP-A-2-87163 (JP, A) JP-A-2- 87162 (JP, A) JP-A-2-87161 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9/097 CA (STN)

Claims (1)

(57) [Claims] 1. A charge control agent represented by the following general formula:
-A positively chargeable toner, comprising either an inorganic acid salt or an organic acid salt of alkyl imidazole.