Magnetic carrier, two-component developer, replenishing developer, and image forming method
A magnetic carrier including a magnetic carrier particle having a magnetic carrier core and a resin coating layer formed on a surface of the magnetic carrier core, wherein the resin coating layer includes a resin component including a resin A and a resin B, the resin A is a copolymer of monomers including (a) a (meth)acrylic acid ester monomer having an alicyclic hydrocarbon group and (b) a specific macromonomer, the resin B is a copolymer of monomers including (c) a styrene-based monomer and (d) a specific (meth)acrylic acid ester monomer, and in a molecular weight distribution of a THF soluble component of the resin component contained in the resin coating layer, a peak derived from the resin B is present in a molecular weight range of from 1000 to 9500.
1. A magnetic carrier including a magnetic carrier particle having a magnetic carrier core and a resin coating layer formed on a surface of the magnetic carrier core, wherein
the resin coating layer includes a resin component including a resin A and a resin B,
the resin A is a copolymer of monomers including
(a) a (meth)acrylic acid ester monomer having an alicyclic hydrocarbon group, and
(b) a macromonomer containing a polymer portion and a reactive portion bound to the polymer portion, wherein
the polymer portion has a polymer of at least one monomer selected from the group consisting of methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate, and
the reactive portion has a reactive C—C double bond,
the resin B is a copolymer of monomers including
(c) a styrene-based monomer, and
(d) a (meth)acrylic acid ester monomer represented by a following formula (1), and
in a molecular weight distribution of a tetrahydrofuran soluble component of the resin component contained in the resin coating layer, a peak derived from the resin B is present in a molecular weight range of from 1000 to 9500,
in the formula (1), R 1 represents H or CH 3 , and n represents an integer of from 2 to 8.
2. The magnetic carrier according to claim 1 , wherein in the molecular weight distribution of a tetrahydrofuran soluble component of the resin component contained in the resin coating layer, which is determined by gel permeation chromatography, a peak derived from the resin A is present in a molecular weight range of from 25,000 to 70,000.
3. The magnetic carrier according to claim 1 , wherein a weight average molecular weight Mw of the macromonomer determined by gel permeation chromatography is from 1000 to 9500.
4. The magnetic carrier according to claim 1 , wherein when, among the monomers for forming the resin A, a ratio of the (meth)acrylic acid ester monomer having an alicyclic hydrocarbon group is denoted by Ma (% by mass), and a ratio of the macromonomer is denoted by Mb (% by mass), Ma and Mb satisfy the following relationships:
0≤Ma≤90.0, and
10.0≤Mb≤50.0.
5. The magnetic carrier according to claim 1 , wherein when, among the monomers for forming the resin B, a mass-based ratio of the (meth)acrylic acid ester monomer represented by the formula (1) is denoted by Mc (ppm), Mc satisfies the following relationship:
5≤Mc≤6000.
6. The magnetic carrier according to claim 1 , wherein when the content ratio of the resin A in the resin coating layer is denoted by MA (% by mass) and the content ratio of the resin B in the resin coating layer is denoted by MB (% by mass), the MA and MB satisfy the following relationships:
10.0≤MA≤99.0 and
1.0≤MB≤90.0.
7. The magnetic carrier according to claim 1 , wherein the magnetic carrier core is a magnetic body-dispersed resin particle or a porous magnetic core particle.
8. A two-component developer comprising a toner having a toner particle including a binder resin, and a magnetic carrier, wherein
the magnetic carrier includes a magnetic carrier particle having a magnetic carrier core and a resin coating layer formed on a surface of the magnetic carrier core, wherein
the resin coating layer includes a resin component including a resin A and a resin B,
the resin A is a copolymer of monomers including
(a) a (meth)acrylic acid ester monomer having an alicyclic hydrocarbon group, and
(b) a macromonomer containing a polymer portion and a reactive portion bound to the polymer portion, wherein
the polymer portion has a polymer of at least one monomer selected from the group consisting of methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate, and
the reactive portion has a reactive C—C double bond,
the resin B is a copolymer of monomers including
(c) a styrene-based monomer, and
(d) a (meth)acrylic acid ester monomer represented by a following formula (1), and
in a molecular weight distribution of a tetrahydrofuran soluble component of the resin component contained in the resin coating layer, a peak derived from the resin B is present in a molecular weight range of from 1000 to 9500,
in the formula (1), R 1 represents H or CH 3 , and n represents an integer of from 2 to 8.
9. An image forming method comprising:
a charging step of charging an electrostatic latent image bearing member;
an electrostatic latent image forming step of forming an electrostatic latent image on a surface of the electrostatic latent image bearing member;
a developing step of developing the electrostatic latent image by using a two-component developer to form a toner image;
a transfer step of transferring the toner image to a transfer material with or without an intermediate transfer member; and
a fixing step of fixing the transferred toner image to the transfer material, wherein
the two-component developer comprises a toner having a toner particle including a binder resin, and a magnetic carrier, wherein
the magnetic carrier is the magnetic carrier according to claim 1 .
10. A replenishing developer for use in an image forming method which comprises:
a charging step of charging an electrostatic latent image bearing member;
an electrostatic latent image forming step of forming an electrostatic latent image on a surface of the electrostatic latent image bearing member;
a developing step of developing the electrostatic latent image by using a two-component developer in a developing device to form a toner image;
a transfer step of transferring the toner image to a transfer material with or without an intermediate transfer member; and
a fixing step of fixing the transferred toner image to the transfer material, and
in which the replenishing developer is replenished to the developing device in accordance with a reduction in toner concentration in the two-component developer in the developing device, wherein
the replenishing developer includes a magnetic carrier and a toner having a toner particle including a binder resin,
the replenishing developer includes from 2 parts by mass to 50 parts by mass of the toner with respect to 1 part by mass of the magnetic carrier, and
the magnetic carrier is the magnetic carrier according to claim 1 .
11. An image forming method which comprises:
a charging step of charging an electrostatic latent image bearing member;
an electrostatic latent image forming step of forming an electrostatic latent image on a surface of the electrostatic latent image bearing member;
a developing step of developing the electrostatic latent image by using a two-component developer in a developing device to form a toner image;
a transfer step of transferring the toner image to a transfer material with or without an intermediate transfer member; and
a fixing step of fixing the transferred toner image to the transfer material, and
in which a replenishing developer is replenished to the developing device in accordance with a reduction in toner concentration in the two-component developer in the developing device, wherein
the replenishing developer includes a magnetic carrier and a toner having a toner particle including a binder resin,
the replenishing developer includes from 2 parts by mass to 50 parts by mass of the toner with respect to 1 part by mass of the magnetic carrier, and
the magnetic carrier is the magnetic carrier according to claim 1 .