Three layered toner for electrophotography

Claim 2

Toner for the development of electrostatic latent images comprising a core particle comprising at least styrene-acrylic copolymer, an intermediate layer coating the core particle and comprising at least styrene-acrylic copolymers, and an outermost surface layer coating the intermediate layer and comprising at least styrene-acrylic copolymers, an absolute value (%) of the difference between S 0 (%) and S 1 (%) represented by the formula (|S 0 -S 1 |) in which S 0 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the core particle is formed, and S 1 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the intermediate layer is formed, being 10% or more, and an absolute value (%) of the difference between S 1 (%) and S 2 (%) represented by the formula (|S 1 -S 2 |) in which S 1 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the intermediate layer is formed and S 2 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the outermost surface is formed, being 5% or more, and the relationship among S 0 , S 1 and S 2 satisfies the following formula; S.sub.0 >S.sub.1 >S.sub.2 or S.sub.0 <S.sub.1 <S.sub.2.

Claim 3

Toner of claim 1, in which S 0 is within the range of between 30% and 90%.

Claim 4

Toner of claim 1, wherein S 1 is at least 5%.

Claim 5

Toner of claim 1, wherein S 0 , S 1 and S 2 satisfy the relationship of |S 0 -S 1 |>|S 1 -S 2 |.

Claim 6

Toner of claim 1, wherein when S 0 , S 1 and S 2 satisfy the relationship of S 0 >S 1 >S 2 , the toner is positively chargeable.

Claim 7

Toner of claim 1, wherein when S 0 , S 1 and S 2 satisfy the relationship of S 0 <S 1 <S 2 , the toner is negatively chargeable.

Claim 8

Toner of claim 1, wherein the outermost surface layer contains a charge controlling agent.

Claim 9

Toner of claim 7, wherein the content of the charge controlling agent is 0.1 to 10 parts by weight on the basis of 100 parts by weight of the resins of which the outermost surface layer is formed.

Claim 10

Toner of claim 1, wherein the acrylic monomer component of the styrene-acrylic copolymer resins of which the outermost surface layer is formed contains a nitrogen-containing polar group or a fluorine atom.

Claim 11

Toner of claim 1 having a coefficient of variation of less than 20% in particle size of the toner.

Claim 12

Toner for the development of electrostatic latent images comprising a core particle comprising at least polyester resins, an intermediate layer coating the core particle and comprising at least styrene-acrylic copolymers, and an outermost surface layer coating the intermediate layer and comprising at least styrene-acrylic copolymers, an absolute value (%) of the difference between S 1 (%) and S 2 (%) represented by the formula (|S 1 -S 2 |) in which S 1 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the intermediate layer is formed and S 2 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the outermost surface is formed, being 5% or more.

Claim 13

Toner for the development of electrostatic latent images comprising a core particle comprising at least polyester resins, an intermediate layer coating the core particle and comprising at least styrene-acrylic copolymers, and an outermost surface layer coating the intermediate layer and comprising at least styrene-acrylic copolymers, an absolute value (%) of the difference between S 1 (%) and S 2 (%) represented by the formula (|S 1 -S 2 |) in which S 1 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the intermediate layer is formed and S 2 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the outermost surface is formed, being 5% or more.

Claim 14

Toner of claim 11, wherein S 1 and S 2 satisfy the relationship of S 1 >S 2 .

Claim 15

Toner of claim 12, wherein S 1 is within the range of between 10 and 100%.

Claim 16

Toner of claim 12 being positively chargeable.

Claim 17

Toner of claim 11, wherein S 1 and S 2 satisfy the relationship of S 1 <S 2 .

Claim 18

Toner of claim 15, wherein S 1 is within the range of between 0 and 90%.

Claim 19

Toner of claim 15 being negatively chargeable.

Claim 20

Toner of claim 11, wherein the outermost surface layer contains a charge controlling agent

Claim 21

Toner of claim 11, wherein the acrylic monomer component of the styrene-acrylic copolymer resins of which the outermost surface layer is formed contains a nitrogen-containing polar group or a fluorine atom.

Claim 22

Toner for the development of electrostatic latent images comprising a core particle comprising at least styrene-acrylic copolymer, an intermediate layer coating the core particle and comprising at least styrene-acrylic copolymers, and an outermost surface layer coating the intermediate layer and comprising at least styrene-acrylic copolymers, an absolute value (%) of the difference between S 0 (%) and S 1 (%) represented by the formula (|S 1 -S 0 |) in which S 0 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the core particle is formed, and S 1 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the intermediate layer is formed, being 10% or more, and an absolute value (%) of the difference between S 1 (%) and S 2 (%) represented by the formula (|S 2 -S 1 |) in which S 1 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the intermediate layer is formed and S 2 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the outermost surface is formed, being 10% or more, and the relationship among S 0 , S 1 and S 2 satisfying the following formula; S.sub.0 >S.sub.1 and S.sub.1 <S.sub.2, or S.sub.0 <S.sub.1 and S.sub.1 >S.sub.2, and a coloring agent being contained in the core particle and/or the intermediate layer, and the coloring agent-containing layer being formed of styrene-acrylic copolymers having the lowest viscosity.

Claim 23

Toner for the development of electrostatic latent images comprising a core particle comprising at least styrene-acrylic copolymer, an intermediate layer coating the core particle and comprising at least styrene-acrylic copolymers, and an outermost surface layer coating the intermediate layer and comprising at least styrene-acrylic copolymers, an absolute value (%) of the difference between S 0 (%) and S 1 (%) represented by the formula (|S 1 -S 0 |) in which S 0 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the core particle is formed, and S 1 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the intermediate layer is formed, being 10% or more, and an absolute value (%) of the difference between S 1 (%) and S 2 (%) represented by the formula (|S 2 -S 1 |) in which S 1 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the intermediate layer is formed and S 2 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the outermost surface is formed, being 10% or more, and the relationship among S 0 , S 1 and S 2 satisfying the following formula; S.sub.0 >S.sub.1 and S.sub.1 <S.sub.2, or S.sub.0 <S.sub.1 and S.sub.1 >S.sub.2, and a coloring agent being contained in the core particle and/or the intermediate layer, and the coloring agent-containing layer being formed of styrene-acrylic copolymers having the lowest viscosity.

Claim 24

Toner of claim 20, wherein S 0 is within the range of between 30% and 90%.

Claim 25

Toner of claim 20, wherein S 0 is larger than S 1 , S 1 is lower than S 2 and the toner is negatively

Claim 26

Toner of claim 20, wherein S 0 is lower than S 1 , S 1 is larger than S 2 and the toner is positively chargeable.

Claim 27

Toner for the development of electrostatic latent images comprising core particles comprising at least thermoplastic resin and having a means particle size of 1 to 20 μm, an intermediate layer comprising at least styrene-acrylic copolymers and having a layer thickness of 0.05 to 4 μm, an outermost surface layer comprising at least styrene-acrylic copolymers and a charge controlling agent, and having a layer thickness of 0.05 to 4 μm, an absolute value (%) of the difference between S 1 (%) and S 2 (%) represented by the formula (|S 1 -S 2 |) in which S 1 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the intermediate layer is formed and S 2 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the outermost surface is formed, being 5% or more, and a coloring agent being contained in the core particles and/or the intermediate layer.

Claim 28

Toner for the development of electrostatic latent images comprising core particles comprising at least thermoplastic resin and having a means particle size of 1 to 20 μm, an intermediate layer comprising at least styrene-acrylic copolymers and having a layer thickness of 0.05 to 4 μm, an outermost surface layer comprising at least styrene-acrylic copolymers and a charge controlling agent, and having a layer thickness of 0.05 to 4 μm, an absolute value (%) of the difference between S 1 (%) and S 2 (%) represented by the formula (|S 1 -S 2 |) in which S 1 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the intermediate layer is formed and S 2 is a content (%) of styrenic monomer component in the styrene-acrylic copolymers of which the outermost surface is formed, being 5% or more, and a coloring agent being contained in the core particles and/or the intermediate layer.

Claim 29

Toner of claim 24, wherein the layer containing the coloring agent is comprised of resin having the temperature (Tf) of 60° to 150° C. at which the viscosity of the resin reaches about 10 6 poise.