JP-7855465-B2 - Toner for developing electrostatic images

Inventors

• 伊丹 隆浩
• 古瀬 大輝

Assignees

• 花王株式会社

Dates

Publication Date

20260508

Application Date

20220913

Claims (11)

1. A toner for developing electrostatic images containing a binder resin, an ester composition (E), and a colorant, wherein the ester composition (E) is An ester composition (E1) containing a condensate of a carboxylic acid component (E1-ac) containing 55 mol% or more of an aliphatic monocarboxylic acid compound having 10 to 30 carbon atoms, and an alcohol component (E1-al) containing 80 mol% or more of a divalent or higher aliphatic alcohol having 2 to 14 carbon atoms, and an ester composition (E2) containing a condensate of an alcohol component (E2-al) containing 55 mol% or more of aliphatic monoalcohol having 10 to 30 carbon atoms, and a carboxylic acid component (E2-ac) containing 80 mol% or more of a divalent or higher aliphatic carboxylic acid compound having 2 to 14 carbon atoms. One or more types selected from, A toner for developing electrostatic images, wherein the sum of the acid value and hydroxyl value of the ester composition (E) is 70 mg KOH/g or more and 400 mg KOH or less, the acid value of the ester composition (E1) is 0.1 mg KOH/g or more and 40 mg KOH/g or less, and the hydroxyl value is 30 mg KOH/g or more and 360 mg KOH or less, and the acid value of the ester composition (E2) is 80 mg KOH/g or more and 200 mg KOH/g or less, and the hydroxyl value is 0.1 mg KOH/g or more and 20 mg KOH/g or less .
2. The toner for developing electrostatic images according to claim 1, wherein the ester composition (E) is the ester composition (E1).
3. The toner for developing electrostatic images according to claim 1, wherein the ester composition (E) is ester composition (E2).
4. The toner for developing electrostatic images according to claim 2, wherein the hydroxyl value of the ester composition (E1) is 70 mgKOH/g or more and 360 mgKOH or less.
5. The toner for developing electrostatic images according to claim 1 , wherein the weight-average molecular weight of the ester composition (E) is 2,000 or less.
6. The toner for developing electrostatic images according to claim 1 , wherein the ester composition (E) is a crystalline ester composition having a melting point, and the melting point is 30°C or higher and 90°C or lower.
7. The toner for developing electrostatic images according to claim 1 , wherein the binder resin contains an amorphous polyester resin.
8. The toner for developing electrostatic images according to claim 1 , wherein the content of the ester compound (E) is 0.5% by mass or more and 15% by mass or less of the total amount of the binder resin and the ester compound (E).
9. The toner for developing electrostatic images according to claim 1 , wherein the coloring agent is a pigment.
10. The toner for developing electrostatic images according to claim 9, wherein the pigment is at least one selected from the group consisting of azo pigments, quinacridone pigments, isoindolinone pigments, naphthol pigments, anthraquinone pigments, and lake pigments.
11. A method for producing electrostatic image developing toner according to any one of claims 1 to 10, comprising the steps of: melt-kneading a mixture containing a binder resin, an ester composition (E), and a colorant to obtain a melt-kneaded product; and crushing and classifying the melt-kneaded product to obtain toner particles.

Description

This invention relates to an electrostatic image developing toner used for developing latent images formed in methods such as electrophotography, electrostatic recording, and electrostatic printing, and to a method for manufacturing the same. In recent years, the market has shifted from office printing to commercial printing, resulting in an increased demand for higher resolution and reliability in printed materials. For example, Patent Document 1 describes an ester composition containing a condensate of a colorant, a resin composition obtained by condensing an amorphous polyester resin (A) having an acid group with an amine compound, and an ester composition containing a condensate of a carboxylic acid component (CI-ac) containing 20 mol% or more of an aliphatic monocarboxylic acid compound having 10 to 30 carbon atoms and an alcohol component (CI-al) containing 90 mol% or more of a divalent or higher aliphatic alcohol having 2 to 14 carbon atoms; or an ester composition containing a condensate of an alcohol component (CII-al) containing 20 mol% or more of aliphatic monoalcohol having 10 to 30 carbon atoms and a carboxylic acid component (CII-ac) containing 90 mol% or more of a divalent or higher aliphatic carboxylic acid compound having 2 to 14 carbon atoms, or both of these. Japanese Patent Publication No. 2021-47403 The electrostatic image developing toner of the present invention (hereinafter also simply referred to as "the toner of the present invention") is an electrostatic image developing toner containing a binder resin, an ester composition (E), and a colorant, wherein the ester composition (E) is one or more selected from ester compositions (E1) containing a condensate of a carboxylic acid component mainly composed of an aliphatic monocarboxylic acid compound with a predetermined number of carbon atoms and an alcohol component mainly composed of an aliphatic alcohol with a predetermined number of carbon atoms and a carboxylic acid component mainly composed of an aliphatic monoalcohol with a predetermined number of carbon atoms and a carboxylic acid component mainly composed of an aliphatic carboxylic acid compound with a predetermined number of carbon atoms and a carboxylic acid component with a predetermined number of carbon atoms and a carboxylic acid compound with a predetermined number of carbon atoms and a carboxylic acid component, and is characterized in that the sum of the acid value and the hydroxyl value is within a predetermined range. According to the toner of the present invention, printed materials can be obtained that have good color development of yellow pigments and magenta pigments, as well as good image abrasion resistance. The detailed reasons why the effects of this invention are obtained are not entirely clear, but they can be thought to be as follows. The toner of the present invention contains an ester composition (E) containing a long-chain monoalcohol or monocarboxylic acid in its molecular chain. This ester composition (E) has a high affinity for the hydrophobic surface of the colorant and contributes to the dispersion of the colorant as a wetting agent. Furthermore, by having a predetermined amount of carboxylic acid terminus, hydroxyl group terminus, or both, the ester composition (E) also has good affinity for the hydrophilic surface of the pigment and exhibits extremely high pigment dispersibility compared to conventional ester compositions. It is also presumed that having a predetermined amount of carboxylic acid terminus, hydroxyl group terminus, or both contributes to dispersion stabilization in the binder resin, suppressing localization on the image surface during heating and thus suppressing deterioration of image abrasion resistance. In this invention, the binder resin is not particularly limited as long as it is a resin used as a binder resin for toner. Examples include polyester resin, vinyl resins such as styrene-acrylic resin, epoxy resin, polycarbonate, polyurethane, and composite resins containing two or more of these resins. However, in this invention, from the viewpoint of fixation, it is preferable to include a polyester resin, such as a polyester resin or a composite resin having a polyester resin and a styrene resin. The polyester resin is preferably amorphous, and as the amorphous polyester resin, amorphous polyester resin is preferred. The crystallinity of a resin is expressed by a crystallinity index, which is defined by the ratio of the softening point to the maximum endothermic peak temperature measured by a differential scanning calorimeter, i.e., the value of [softening point / maximum endothermic peak temperature]. The crystalline resin is a resin having a crystallinity index of 0.6 or higher, preferably 0.7 or higher, more preferably 0.9 or higher, and 1.4 or lower, preferably 1.2 or lower, more preferably 1.1 or lower. On the other hand, amorphous resins are those in which no endothermic peak is observed, or, if observed, those with a crys