Fixing rotating member, fixing apparatus and electrophotographic image forming apparatus, and method for producing fixing rotating member
Provided is a fixing rotating member capable of maintaining high toner releasability over longer periods of time than in conventional instances and that is capable of maintaining abrasion resistance against paper; the fixing rotating member comprises a base layer, an elastic layer, and a surface layer, in this order; the surface layer containing a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and a perfluoropolyether; the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer having pores formed therein; the surface layer has pores with openings at a first surface thereof, and constituting an outer surface of the fixing rotating member; at least part of the pores containing the perfluoropolyether; a content of the perfluoropolyether in the surface layer is 20 mass % to 60 mass %; and a degree of orientation A of molecules of the tetrafluoroethylene-perfluoroalkyl vinyl ether in a direction perpendicular to a circumferential direction of the surface layer is 35 to 75%.
1. A fixing rotating member comprising a base layer, an elastic layer and a surface layer, in this order,
the surface layer containing a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and a perfluoropolyether,
the surface layer having pores with openings at a first surface thereof, and constituting an outer surface of the fixing rotating member, and
at least part of the pores containing the perfluoropolyether,
wherein a content of the perfluoropolyether in the surface layer is 20 to 60 mass %, and
a degree of orientation A of molecules of the tetrafluoroethylene-perfluoroalkyl vinyl ether in a direction perpendicular to a circumferential direction of the surface layer is 35 to 75%.
2. The fixing rotating member according to claim 1 , wherein:
when a first observation region 8 μm long×11 μm wide is placed on the first surface of the surface layer after removing the perfluoropolyether in the pores, and a ratio of a total sum of areas of the openings observed in the first observation region relative to an area of the first observation region is defined as P1; and
when a second observation region 8 μm long×11 μm wide is placed in a cross section of the surface layer after removing the perfluoropolyether in the pores, the cross section including an entire thickness portion of the surface layer along a circumferential direction of the fixing rotating member, and a ratio of a total sum of areas of the pores observed in the second observation region relative to an area of the second observation region is defined as P2,
P2/P1 is 1.3 or higher.
3. The fixing rotating member according to claim 2 , wherein P2/P1 is 5.0 or higher.
4. The fixing rotating member according to claim 2 , wherein P2/P1 is 20.0 or lower.
5. The fixing rotating member according to claim 1 , wherein an average opening diameter of the openings in the outer surface is 1 nm to 5 μm.
6. The fixing rotating member according to claim 1 , wherein a thickness of the surface layer is 12 to 100 μm.
7. The fixing rotating member according to claim 1 , wherein the perfluoropolyether has a structure represented by formula (1):
wherein in the formula (1), a, b, c, d, e and f are each independently 0 or a positive integer, satisfy 1≤a+b+c+d+e+f≤600, and at least one from among a, b, c and d represents a positive integer.
8. The fixing rotating member according to claim 1 , wherein the perfluoropolyether has at least one structure selected from the group consisting of formulae (2) to (5):
wherein in the formula (2), n is a positive number such that PFPE viscosity at a temperature of 40° C. is 30 to 500 mPa·s;
wherein in the formula (3), n′ is a positive number such that PFPE viscosity at a temperature of 40° C. is 10 to 2500 mPa·s;
wherein in the formula (4), n″ and m are each independently a positive number, m/n″ is a number from 0.5 to 2, and n″+m is a number such that PFPE viscosity at a temperature of 40° C. is 20 to 1400 mPa·s; and
wherein in the formula (5), n′″ and m′ are each independently a positive number, m′/n′″ is a number from 20 to 1000, and n′″+m′ is a number such that PFPE viscosity at a temperature of 40° C. is 20 to 1200 mPa·s.
9. The fixing rotating member according to claim 1 , wherein the fixing rotating member is a fixing belt having an endless belt shape.
10. A fixing apparatus, comprising a fixing rotating member, and heater for heating the fixing rotating member, wherein:
the fixing rotating member comprises a base layer, an elastic layer and a surface layer, in this order;
the surface layer contains a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and a perfluoropolyether;
the surface layer has pores with openings at a first surface thereof, and constituting an outer surface of the fixing rotating member;
at least part of the pores contains the perfluoropolyether;
a content of the perfluoropolyether in the surface layer is 20 to 60 mass %; and
a degree of orientation A of molecules of the tetrafluoroethylene-perfluoroalkyl vinyl ether in a direction perpendicular to a circumferential direction of the surface layer is 35 to 75%.
11. The fixing apparatus according to claim 10 , wherein:
the fixing rotating member is a fixing belt having an endless belt shape; and
the heater is disposed in contact with an inner peripheral surface of the fixing belt.
12. An electrophotographic image forming apparatus comprising the fixing apparatus according to claim 10 .
13. A method for producing a fixing rotating member, wherein
the fixing rotating member comprises a base layer, an elastic layer, and a surface layer, in this order,
the surface layer contains a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and a perfluoropolyether,
the surface layer has pores with openings at a first surface thereof, and constituting an outer surface of the fixing rotating member;
at least part of the pores contains the perfluoropolyether,
a content of the perfluoropolyether in the surface layer is 20 to 60 mass %, and
a degree of orientation A of molecules of the tetrafluoroethylene-perfluoroalkyl vinyl ether in a direction perpendicular to a circumferential direction of the surface layer being 35 to 75%,
the method comprises the steps of:
(i) providing a resin tube comprising a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, wherein
a degree of orientation A of molecules of the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer is 35 to 75%;
(ii) providing a layered body comprising
a base layer having an endless belt shape or a roller shape,
an elastic layer on an outer peripheral surface of the base layer, and
the resin tube on an outer peripheral surface of the elastic layer;
(iii) immersing the layered body in a first perfluoropolyether at a temperature from 25° C. to below Tp, where Tp (° C.) is a melting point of the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, to impregnate the resin tube with the perfluoropolyether;
(iv) removing, with a solvent, at least part of the perfluoropolyether within the resin tube of the layered body obtained in step (iii), to form, in the resin tube, pores with openings in an outer peripheral surface of the resin tube; and
(v) incorporating a second perfluoropolyether into at least part of the pores, to obtain a fixing rotating member having a surface layer comprising the second perfluoropolyether in at least part of the pores.
14. The method for producing a fixing rotating member according to claim 13 , wherein viscosity of the first perfluoropolyether at a temperature of 40° C. is 10 to 350 mPa·s.
15. The method for producing a fixing rotating member according to claim 13 , wherein the solvent is a solvent dissolving the first perfluoropolyether but not dissolving the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer.
16. The method for producing a fixing rotating member according to claim 13 , wherein viscosity of the second perfluoropolyether at a temperature of 40° C. is 300 to 2500 mPa·s.