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JP-7855765-B2 - toner

JP7855765B2JP 7855765 B2JP7855765 B2JP 7855765B2JP-7855765-B2

Inventors

  • 上倉 健太
  • 浦谷 梢
  • 福留 航助
  • 衣松 徹哉
  • 水口 卓哉
  • 小宮 友太

Assignees

  • キヤノン株式会社

Dates

Publication Date
20260508
Application Date
20250515
Priority Date
20201225

Claims (5)

  1. A toner having binder resin and ester compound A in toner particles and an external additive , The binder resin contains a styrene-acrylic resin having a unit represented by the following formula (1), The ester compound A is an ester compound represented by the following formula (2) or formula (3), The external additive contains hydrotalcite, A toner characterized in that the absolute difference between the SP value of the styrene-acrylic resin, SPb (J/ cm³ ) 1/2 , and the SP value of the ester compound A, SPw1 (J/ cm³ ) 1/2 , is 1.00 or more and 2.00 or less. (In formula (1), R1 represents a hydrogen atom or a methyl group, and R2 represents a linear alkyl group having 10 to 14 carbon atoms.) (In formulas (2) and (3), R11 to R14 and R21 to R26 each independently represent a linear alkyl group having 15 to 21 carbon atoms.)
  2. The toner according to claim 1, wherein the styrene-acrylic resin contains 1% by mass or more and 15% by mass or less of the unit represented by formula (1).
  3. The toner particles contain ester compound B, The ester compound B is an ester compound represented by the following formula (4), formula (5), or formula (6), The toner according to claim 1 or 2, wherein the absolute value of the difference between SPb (J/ cm³ ) 1/2 and SPw2 (J/ cm³ ) 1/2 , which is the SP value of the ester compound B, is 2.10 or less. (In formulas (4), (5), and (6), R 31 and R 41 each independently represent an alkylene group having 2 to 8 carbon atoms, and R 32 , R 33 , R 42 , R 43 , R 51 , and R 52 each independently represent a linear alkyl group having 14 to 24 carbon atoms.)
  4. The toner according to any one of claims 1 to 3, wherein the ester compound A is an ester compound represented by the following formula (2') or the following formula (3'). (In formulas (2') and (3'), R11 to R14 and R21 to R26 each independently represent a linear alkyl group having 17 to 21 carbon atoms.)
  5. The toner according to claim 4, wherein the ester compound A is the ester compound represented by formula (2').

Description

This invention relates to toner used in recording methods utilizing electrophotography, electrostatic recording, and toner jet recording. In recent years, electrophotographic image formation has expanded its application from office use to commercial printing. While the image quality requirements for commercial printing vary, the field of photographic printing in particular demands high print density and high gloss output at high speed. To achieve high print density and high gloss image output at high speed, toner requires excellent melting properties that allow it to become sufficiently low viscosity even with short heating times. To meet these demands, various studies are being conducted on binder resins used in toners. Among these studies, styrene-acrylic resins incorporating long-chain alkyl (meth)acrylates are being investigated as binder resins with excellent melting properties. Patent Document 1 discloses a toner for developing electrostatic images, characterized by containing a styrene-acrylic resin as a binder resin, which has structural units derived from alkyl (meth)acrylate monomers with 8 to 22 C1 of the alkyl group, and structural units derived from alkyl (meth)acrylate monomers with 1 to 7 C1 of the alkyl group, and containing a crystalline ester compound. It also discloses that pentaerythritol tetrabehenate can be used as a wax. Patent Document 1 improves the melting characteristics of the toner by controlling the affinity between the crystalline ester compound and the binder resin using a styrene-acrylic resin. However, when high-print-density images were continuously output using the toner from Patent Document 1, a problem with image stacking became apparent, where the images stuck together. Furthermore, no improvement in image stacking was observed when pentaerythritol tetrabehenate was used as a wax in the toner from Patent Document 1. On the other hand, Patent Document 2 discloses a toner binder resin containing a vinyl copolymer formed by copolymerizing monomer components: 10 to 30% by mass of an alkyl (meth)acrylate monomer with 8 or more carbon atoms in the alkyl group, and 0.2 to 2% by mass of an alkyldiol diacrylate monomer with 6 or more carbon atoms in the alkylene group, and Fischer-Tropsch wax. The binder resin described in Patent Document 2 has a crosslinked structure formed by the alkyldiol acrylate monomer with 6 or more carbon atoms, which increases the viscosity of the image surface after fixing, suppressing image adhesion. However, the method described in Patent Document 2 has the problem of not being able to obtain sufficient image gloss in high-speed processes. Thus, toners using styrene-acrylic resins incorporating long-chain alkyl acrylates as the binder resin can achieve high image gloss, but they have issues with image stacking. Therefore, there was a need to achieve a high level of balance between these two aspects. Japanese Patent Publication No. 2014-035506Japanese Patent Publication No. 2007-322477 In this invention, unless otherwise specified, the notation "○○ to ××" representing a numerical range means a numerical range that includes the lower and upper limits. The toner of the present invention is a toner having toner particles having a binder resin and an ester compound A, The binder resin contains a styrene-acrylic resin having a unit represented by the following formula (1), The ester compound A is an ester compound represented by formula (2) or formula (3), The present invention is characterized in that the absolute value of the difference between the SP value of the styrene-acrylic resin, SPb (J/ cm³ ) 1/2 , and the SP value of the ester compound A, SPw1 (J/ cm³ ) 1/2 , is 1.00 or more and 2.00 or less. In formula (1), R1 represents a hydrogen atom or a methyl group, and R2 represents a linear alkyl group having 10 to 14 carbon atoms. In formulas (2) and (3), R11 to R14 and R21 to R26 each independently represent a linear alkyl group having 15 to 21 carbon atoms. Although the exact factors that enabled the toner of this invention to achieve both high image gloss and image stacking performance are unclear, the inventors speculate as follows. The unit shown in formula (1) (hereinafter also referred to as the "long-chain acrylate moiety") has high molecular chain mobility. Therefore, resins containing long-chain acrylate moieties have a high degree of freedom during melting and are easily made low-viscosity. Thus, when used as a binder resin for toner, the image surface after fixing tends to be smooth, and high image gloss can be obtained. On the other hand, because the long-chain acrylate moieties present on the image surface after fixing have high molecular chain mobility, the parts that come into contact with the next printed paper tend to stick, and this can cause image sticking, especially when printing at high print density and high speed. Generally, reducing the mobility of molecular chains is effective in suppressing image adhesion. Specifically, a