Grease composition, heating device, and electrophotographic image forming apparatus

An electrophotographic image forming apparatus comprising a heating device, the heating device including:

• a rotating member for heating;
• an opposing member, which is arranged so as to be opposed to the rotating member, and forms a nip portion together with the rotating member;
• and
• a biasing member, which is arranged inside the rotating member, has an opposing surface with respect to an inner peripheral surface of the rotating member, and is configured to bias the rotating member to the opposing member,
• wherein the inner peripheral surface and the opposing surface are brought into contact with each other via a grease composition to form a sliding portion,
• the grease composition contains a base oil,
• the base oil contains a fluoropolymer and a perfluoropolyether,
• the fluoropolymer has a structure represented by the following formula (1):
• in formula (1), R represents an alkylene group, p and q each independently represent a positive number, and p+q is such a value that a kinematic viscosity at a temperature of 40° C. of the fluoropolymer satisfies from 1.0×103 cm2/s to 1.0×105 cm2/s;
• the perfluoropolyether
• having an evaporation loss of 0.05 to 2.0 mass % at a point of 260° C. in a thermogravimetric reduction curve obtained when the perfluoropolyether is increased in temperature from 25° C. at 10° C./min under a nitrogen atmosphere,
• having a kinematic viscosity at a temperature of 40° C. of from 0.5 cm2/s to 15 cm2/s, and
• including at least one perfluoropolyether selected from the group consisting of a perfluoropolyether having a structure represented by the following formula (2);
• a perfluoropolyether having a structure represented by the following formula (3);
• and a perfluoropolyether having a structure represented by the following formula (4):
• in formula (2), k represents a positive number, and k is such a value that the kinematic viscosity at a temperature of 40° C. of the perfluoropolyether satisfies from 0.5 cm2/s to 15 cm2/s;
• CF3—(OCF2CF2)m1—(OCF2)n1—CF3 formula (3)
• in formula (3), m1 and n1 each independently represent a positive number, and m1+n1 is such a value that the kinematic viscosity at a temperature of 40° C. of the perfluoropolyether satisfies from 0.5 cm2/s to 15 cm2/s;
• F—(CF2CF2CF2O)n2—CF2CF3 formula (4)
• in formula (4), n2 represents a positive number, and n2 is such a value that the kinematic viscosity at a temperature of 40° C. of the perfluoropolyether satisfies from 0.5 cm2/s to 15 cm2/s.

A grease composition comprising:

• a base oil containing a fluoropolymer and a perfluoropolyether,
• the fluoropolymer having a structure represented by the following formula (1):
• in formula (1), R represents an alkylene group, p and q each independently represent a positive number, and p+q is such a value that a kinematic viscosity at a temperature of 40° C. of the fluoropolymer satisfies from 1.0×103 cm2/s to 1.0×105 cm2/s;
• the perfluoropolyether
• having an evaporation loss of 0.05 to 2.0 mass % at a point of 260° C. in a thermogravimetric reduction curve obtained when the perfluoropolyether is increased in temperature from 25° C. at 10° C./min under a nitrogen atmosphere,
• having a kinematic viscosity at a temperature of 40° C. of from 0.5 cm2/s to 15 cm2/s, and
• including at least one perfluoropolyether selected from the group consisting of a perfluoropolyether having a structure represented by the following formula (2);
• a perfluoropolyether having a structure represented by the following formula (3);
• and a perfluoropolyether having a structure represented by the following formula (4):
• in formula (2), k represents a positive number, and k is such a value that the kinematic viscosity at a temperature of 40° C. of the perfluoropolyether satisfies from 0.5 cm2/s to 15 cm2/s;
• CF3—(OCF2CF2)m1—(OCF2)n1—CF3 Structural formula (3)
• in formula (3), m1 and n1 each independently represent a positive number, and m1+n1 is such a value that the kinematic viscosity at a temperature of 40° C. of the perfluoropolyether satisfies from 0.5 cm2/s to 15 cm2/s;
• F—(CF2CF2CF2O)n2—CF2CF3 Structural formula (4)
• in formula (4), n2 represents a positive number, and n2 is such a value that the kinematic viscosity at a temperature of 40° C. of the perfluoropolyether satisfies from 0.5 cm2/s to 15 cm2/s.