JP-2026075429-A - Method for manufacturing toner resin

Abstract

[Problem] The present invention relates to a method for producing a toner resin that can form a printed coating film with excellent adhesion to PET film and excellent pencil hardness as an indicator of scratch resistance, a toner containing the toner resin obtained by the method for producing the toner resin, and a method for producing the toner. [Solution] A method for producing a toner resin, comprising subjecting an alcohol component, a carboxylic acid component, and polyethylene terephthalate to a polycondensation reaction to obtain an amorphous polyester resin A, wherein the polycondensation reaction is carried out in the presence of an antifoaming agent, and the amount of antifoaming agent added is 0.01 parts by mass or more and 0.3 parts by mass or less per 100 parts by mass of the total of the alcohol component, the carboxylic acid component, and polyethylene terephthalate. [Selection Diagram] None

Inventors

• 相馬 央登

Assignees

• 花王株式会社

Dates

Publication Date

20260508

Application Date

20241022

Claims (7)

1. A method for producing a toner resin, comprising subjecting an alcohol component, a carboxylic acid component, and polyethylene terephthalate to a polycondensation reaction to obtain an amorphous polyester resin A, The polycondensation reaction is carried out in the presence of an antifoaming agent. A method for producing a toner resin, wherein the amount of defoaming agent added is 0.01 parts by mass or more and 0.3 parts by mass or less per 100 parts by mass of the total of the alcohol component, carboxylic acid component, and polyethylene terephthalate.
2. A method for producing a toner resin according to claim 1, wherein the amount of polyethylene terephthalate added is 20 moles or more and 70 moles or less relative to 100 moles of the total amount of alcohol component and polyethylene terephthalate.
3. A method for producing a toner resin according to claim 1 or 2, wherein the defoaming agent includes a silicone-based defoaming agent.
4. The method for producing a toner resin according to claim 3, wherein the silicone-based defoaming agent is dimethyl silicone.
5. A method for producing a toner resin according to claim 1 or 2, wherein the alcohol component contains an alkylene oxide adduct of an aromatic diol.
6. A method for manufacturing toner, comprising the following steps 1 and 2. Step 1: A step in which an alcohol component, a carboxylic acid component, and polyethylene terephthalate are subjected to a polycondensation reaction in the presence of an antifoaming agent to obtain amorphous polyester resin A. However, the amount of antifoaming agent added is 0.01 parts by mass or more and 0.3 parts by mass or less per 100 parts by mass of the total of the alcohol component, carboxylic acid component, and polyethylene terephthalate. Step 2: A step in which resin particles containing amorphous polyester resin A obtained in Step 1 are aggregated and fused in an aqueous medium.
7. A method for manufacturing toner, comprising the following steps 1 and 2. Step 1: A step in which an alcohol component, a carboxylic acid component, and polyethylene terephthalate are subjected to a polycondensation reaction in the presence of an antifoaming agent to obtain amorphous polyester resin A. However, the amount of antifoaming agent added is 0.01 parts by mass or more and 0.3 parts by mass or less per 100 parts by mass of the total of the alcohol component, carboxylic acid component, and polyethylene terephthalate. Step 2: A step in which the amorphous polyester resin A obtained in Step 1 is melt-kneaded and pulverized.

Description

This invention relates to a method for manufacturing a toner resin used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, etc., toner, and a method for manufacturing toner. The diversification of printing media has led to a growing demand for electrophotographic printing on media other than paper. For example, in the field of commercial label printing used for product packaging and advertising, plastic films such as polyethylene terephthalate (PET) are used as printing media due to their water resistance and durability. However, unlike paper, plastic films have a smooth surface, making it difficult for an anchoring effect to occur between the image (printed coating) and the film. Therefore, images tend to peel off the plastic film or be easily damaged by scratching. As a technology to improve image adhesion to plastic films, for example, Patent Document 1 describes a method for producing a resin composition, a toner, a powder coating, and an ink, with the aim of providing a printing film that exhibits excellent adhesion to PET and PP films and excellent storage stability, as well as a method for producing the same. This method includes a step of heating a mixture of a specific polymer (A) and a polyester resin (B) at a temperature above the flow initiation temperature of the polymer (A). Japanese Patent Publication No. 2021-161177 [Manufacturing method for toner resin] The present invention provides a method for producing a toner resin, comprising subjecting an alcohol component, a carboxylic acid component, and polyethylene terephthalate to a polycondensation reaction in the presence of an antifoaming agent to obtain an amorphous polyester resin A, wherein the amount of antifoaming agent added is 0.01 parts by mass or more and 0.3 parts by mass or less per 100 parts by mass of the total of the alcohol component, carboxylic acid component, and polyethylene terephthalate. The present invention provides a toner resin that can produce a toner capable of forming a printed coating film with excellent adhesion to PET film and pencil hardness as an indicator of scratch resistance. The reason why the effects of this invention are obtained is not entirely clear, but it can be inferred as follows. In the polycondensation reaction between an alcohol component, a carboxylic acid component, and PET, PET undergoes depolymerization through hydrolysis by water produced during the esterification reaction between the alcohol component and the carboxylic acid component, while simultaneously being incorporated into the polyester resin chain through transesterification. Even after depolymerization, PET does not become completely randomized, and molecular chains that can be called PET segments exist in the resulting amorphous polyester resin. However, if hydrolysis occurs excessively and the PET structure disappears, the constituent units derived from ethylene glycol and terephthalic acid become randomly arranged in the amorphous polyester resin, resulting in the loss of properties derived from the PET segments. In this invention, an alcohol component, a carboxylic acid component, and PET are subjected to a polycondensation reaction in the presence of an antifoaming agent. The water (water vapor) generated during the esterification reaction tends to remain in the reaction system because it cannot break the foam film formed by the high-viscosity amorphous polyester resin. However, the presence of an antifoaming agent makes it easier for the foam film to disappear, allowing the water (water vapor) to be released from the reaction system. As a result, excessive hydrolysis of PET is suppressed, and PET segments can be effectively contained in the resulting amorphous polyester resin. PET segments have high cohesive force, improving the strength of the printed coating. Furthermore, because of its high affinity with PET film having the same structure, toner containing the toner resin (amorphous polyester resin A) obtained by the toner resin manufacturing method of this invention exhibits excellent adhesion to PET film, and the printed coating formed with this toner is considered to have excellent pencil hardness. The definitions of various terms used in this specification are shown below. In this specification, the carboxylic acid component of the polyester resin includes not only the compound itself, but also anhydrides that decompose during the reaction to produce carboxylic acids, and alkyl esters of each carboxylic acid (alkyl group having 1 to 3 carbon atoms). Whether a resin is crystalline or amorphous is determined by its crystallinity index. The crystallinity index is defined as the ratio of the resin's softening point to its maximum endothermic peak temperature (softening point (°C) / maximum endothermic peak temperature (°C)) in the measurement method described in the examples below. A crystalline resin is one in which the crystallinity index is 0.6 or higher and 1.4 o