Magnetic carrier, two-component developer, and developer for replenishment

A two-component developer comprising:

• a toner;
• and
• a magnetic carrier,
• wherein the magnetic carrier includes a magnetic carrier particle including a magnetic core and a resin coating layer configured to coat a surface of the magnetic core,
• wherein the resin coating layer contains a coating resin,
• the coating resin contains
• a resin A having a fluorine polymer moiety, and
• a resin B having a third repeating structure represented by formula (10):
• where R5 represents hydrogen or a methyl group, and R6 represents an alicyclic hydrocarbon group,
• wherein a content ratio of the resin A in the coating resin is 3 mass % or more and 20 mass % or less, and
• wherein the resin coating layer has an average thickness of 50 nm or more,
• wherein when a concentration of a nitrogen atom, a concentration of a silicon atom, a concentration of a fluorine atom, a concentration of a carbon atom, a concentration of a titanium atom, a concentration of a strontium atom, a concentration of a tin atom, a concentration of an aluminum atom, and a concentration of an oxygen atom detected at a position at a depth of x nm from a surface of the magnetic carrier particle by X-ray photoelectron spectroscopy are represented by dN(x), dSi(x), dF(x), dC(x), dTi(x), dSr(x), dSn(x), dAl(x), and dO(x), respectively, a ratio F(x) (atomic %) of the fluorine atom represented by equation (A) satisfies formula (1) and formula (2), and
• wherein when x represents an integer of 0 or more and 20 or less, F (x) satisfies formula (3):
• F(x)=dF(x)/[dN(x)+dSi(x)+dF(x)+dC(x)+dTi(x)+dSr(x)+dSn(x)+dAl(x)+dO(x)]×100 (A)
• 5.0≤F(0)≤15 (1)
• F(20)≤5.0 (2)
• |F(x+1)−F(x)|≤7.5 (3).

A developer for replenishment for use in an image-forming method including:

• charging an electrostatic latent image-bearing member;
• forming an electrostatic latent image on a surface of the electrostatic latent image-bearing member;
• developing the electrostatic latent image with a two-component developer in a developing unit to form a toner image;
• transferring the toner image onto a transfer material through or without through an intermediate transfer member;
• and
• fixing the transferred toner image onto the transfer material,
• the developer for replenishment being replenished into the developing unit in accordance with a reduction in toner concentration of the two-component developer in the developing unit,
• the developer for replenishment comprising:
• a magnetic carrier for replenishment;
• and
• a toner,
• wherein the magnetic carrier for replenishment is a magnetic carrier including a magnetic carrier particle including a magnetic core and a resin coating layer configured to coat a surface of the magnetic core,
• wherein the resin coating layer contains a coating resin,
• the coating resin contains
• a resin A having a fluorine polymer moiety, and
• a resin B having a third repeating structure represented by formula (10):
• where R5 represents hydrogen or a methyl group, and R6 represents an alicyclic hydrocarbon group,
• wherein a content ratio of the resin A in the coating resin is 3 mass % or more and 20 mass % or less, and
• wherein the resin coating layer has an average thickness of 50 nm or more,
• wherein when a concentration of a nitrogen atom, a concentration of a silicon atom, a concentration of a fluorine atom, a concentration of a carbon atom, a concentration of a titanium atom, a concentration of a strontium atom, a concentration of a tin atom, a concentration of an aluminum atom, and a concentration of an oxygen atom detected at a position at a depth of x nm from a surface of the magnetic carrier particle by X-ray photoelectron spectroscopy are represented by dN(x), dSi(x), dF(x), dC(x), dTi(x), dSr(x), dSn(x), dAl(x), and dO(x), respectively, a ratio F(x) (atomic %) of the fluorine atom represented by equation (A) satisfies formula (1) and formula (2), and
• wherein when x represents an integer of 0 or more and 20 or less, F (x) satisfies the following formula (3):
• F(x)=dF(x)/[dN(x)+dSi(x)+dF(x)+dC(x)+dTi(x)+dSr(x)+dSn(x)+dAl(x)+dO(x)]×100 (A)
• 5.0≤F(0)≤15 (1)
• F(20)≤5.0 (2)
• |F(x+1)−F(x)|≤7.5 (3).