Zeon Corporation

Nof Corporation

Ryuji Ohta

Azusa Masuda

Munehiro Yamada

Norifumi Itako

Ryosuke Uemura

Provided is a yellow toner that has excellent pigment dispersibility, and thus gives a high image density and causes little fog. A yellow toner of the present invention includes at least a binder resin and a yellow pigment, wherein the binder resin is a copolymer that contains 67 to 88% by mass of a styrene-based monomer unit and 12 to 33% by mass of a alkyl (meth)acrylate monomer unit, wherein a content of the yellow pigment is 3 to 15 parts by mass with respect to 100 parts by mass of the binder resin; and wherein a interfacial tension of a mixed solution of 9 parts by mass of the yellow pigment, 72 parts by mass of styrene and 28 parts by mass of n-butyl acrylate with respect to water, is 5 to 19 mN/m.

Yellow toner

There is provided a toner for developing electrostatic images, including an external additive and colored resin particles containing a binder resin, a colorant and softening agents. The colored resin particles contain a monoester compound A represented by formula (1) and a monoester compound B represented by formula (2) as softening agents. A content of the monoester compound A is in the range from 95 to 99% by mass, a content of the monoester compound B is in the range from 1 to 5% by mass, and a content of the softening agents is in the range from 10 to 30 parts by mass, with respect to 100 parts by mass of the binder resin. Formula (1) is R&#x2014;COO&#x2014;R. Formula (2) is R&#x2014;COO&#x2014;R.

Toner for developing electrostatic images

Provided is a toner that is excellent in heat-resistant shelf stability and low-temperature fixability, has durability, and causes less occurrence of fogging in high temperature and high humidity environments. The toner comprising at least a binder resin, a colorant, a release agent, a retention aid and a charge control resin. The binder resin is a copolymer containing a styrene-based monomer unit 67 to 78% by mass and a (meth)acrylic acid alkyl monomer unit 22 to 33% by mass. The content of the retention aid is 1 to 4 parts by mass with respect to 100 parts by mass of the binder resin, and the content of the charge control resin is 0.1 to 20 parts by mass with respect to 100 parts by mass of the binder resin.

Toner

The present invention is to provide a toner which has an excellent balance between heat-resistant storage stability and low-temperature fixability and which is excellent in printing durability even under a wide range of temperature and humidity environments from a low temperature and low humidity environment to a high temperature and high humidity environment. Disclosed is a toner for developing electrostatic images, containing colored resin particles containing a binder resin, a colorant, a softening agent and a retention aid, and an external additive, wherein the retention aid is a copolymer of at least one of acrylic acid ester and methacrylic acid ester and at least one of acrylic acid and methacrylic acid, and wherein the copolymer has an acid value of 0.5 to 7 mgKOH/g, a weight average molecular weight Mw of 6,000 to 50,000, and a glass transition temperature of 60 to 85&#xb0; C.

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Tokyo, Japan

Ryuji Ohta