Polyester resin for toner, toner, developer, and image formation device

Abstract

A polyester resin for a toner, the polyester resin including: a segment derived from an alcohol component; and a segment derived from a carboxylic acid component, wherein the alcohol component includes a trivalent or higher aliphatic alcohol, and wherein the polyester resin satisfies Expressions (1) to (3) below: 500 ≤ Weight ⁢ ⁢ average ⁢ ⁢ molecular ⁢ ⁢ weight ⁢ ⁢ ( Mw ) ( Valence ⁢ ⁢ of ⁢ ⁢ the ⁢ ⁢ trivalent ⁢ ⁢ or higher ⁢ ⁢ aliphatic ⁢ ⁢ alcohol ) × ( Amount ⁢ ⁢ of ⁢ ⁢ the ⁢ ⁢ trivalent ⁢ ⁢ or higher ⁢ ⁢ aliphatic ⁢ ⁢ alcohol ) ≤ 4 , 000 ; Expression ⁢ ⁢ ( 1 ) 4,000≦Weight average molecular weight (Mw)≦25,000   Expression (2); and 0.5≦(Amount of the trivalent or higher aliphatic alcohol)≦6.5   Expression (3), where, in the Expressions (1) and (3), the Amount of the trivalent or higher aliphatic alcohol denotes a percent by mole of the trivalent or higher aliphatic alcohol relative to the alcohol component.

Dependencies are inferred from the claim text.