JP7301572B2 - Fixing member, fixing device and electrophotographic image forming apparatus - Google Patents

Description

The present invention relates to fixing members, fixing devices, and electrophotographic image forming apparatuses.

In a fixing device used in an electrophotographic image forming apparatus (hereinafter also referred to as an "image forming apparatus") such as a copier or a laser printer, a pair of heated roller and roller, film and roller, belt and roller, belt and belt are used. , are pressed against each other. Then, a recording medium such as paper holding an image formed by unfixed toner is introduced into a pressure contact portion (hereinafter referred to as a "fixing nip portion") formed between the rotating bodies, and the unfixed toner is removed. The image is fixed on the recording medium by heating and melting. A rotating body with which an unfixed toner image on a recording medium contacts is called a fixing member, and is also called a fixing roller, a fixing film, or a fixing belt depending on its form.
In the fixing member for electrophotography, the surface layer (hereinafter referred to as "surface layer") constituting the outer surface that contacts the toner is coated with a fluororesin, specifically, a For example, a surface layer containing a copolymer of tetrafluoroethylene (-C ₂ F ₄ -) and perfluoroalkyl vinyl ether (-CF ₂ -CF(ORf)-) (hereinafter also referred to as "PFA") Sometimes used. Here, "Rf" represents a perfluoroalkyl group.
In recent years, in electrophotographic image forming apparatuses for commercial printing, it has been proposed to increase the heat fixing temperature of toner in order to achieve further speeding up of the process speed. In this case, the conventional fixing member has insufficient toner releasability, and hot offset may occur.
Here, in Patent Document 1, a layer containing a fluorine polymer such as PFA to which a compound having a perfluoropolyether (hereinafter also referred to as "PFPE") chain or a perfluoroalkyl chain is covalently bonded is formed on the outermost surface. and a fixing member provided with the liquid-repellent film.

JP 2018-22056 A

"Journal of Japan Adhesion Society", Japan Adhesion Society, 1972, Vol. 8, No. 3, p. 131-141

One aspect of the present invention is directed to providing a fixing member capable of maintaining high toner releasability over a long period of time. Another aspect of the present invention is directed to providing a fixing device that contributes to stable formation of high-quality electrophotographic images over a long period of time. Another aspect of the present invention is directed to providing an electrophotographic image forming apparatus capable of stably forming high-quality electrophotographic images over a long period of time.

According to one aspect of the present invention, there is provided an electrophotographic fixing member comprising a base layer and a surface layer provided on the outer surface of the base layer directly or via a primer layer,
The surface layer consists of a single layer,
The fixing member is characterized in that the surface layer contains a fluororesin and a fluorine oil having a perfluoropolyether structure, and the fixing member satisfies requirements (i) and (ii). :
(i) after cleaning predetermined locations on a first surface of a first surface opposite the side facing the base layer of a measurement sample taken from the fusing member and including a full thickness portion of the surface layer; At this position, the detection surface of the crystal oscillator microbalance (QCM) sensor is pressed at a pressure of 0.4 MPa at a temperature of 180 ° C. for 50 msec, and the unit area of the detection surface The mass P11 of the deposit containing fluorine oil having a perfluoropolyether structure attached to (1 cm ² ) is 1.0×10 ² ng or more and 1.0×10 ⁴ ng or less;
(ii) For the measurement sample subjected to the treatment specified in the requirement (i), after cleaning the position, place it in an environment with a temperature of 180 ° C. for 120 seconds, and then place a crystal oscillator microbalance ( QCM) A perfluoropolyether structure that adheres to a unit area (1 cm ² ) of the detection surface when the detection surface of the sensor is pressed at a pressure of 0.4 MPa at a temperature of 180 ° C. for 50 msec. is 0.5×P11 or more and 1.2×P11 or less.

According to another aspect of the present invention, there is provided an electrophotographic fixing member comprising a base layer and a surface layer provided on the outer surface of the base layer directly or via a primer layer,
The surface layer consists of a single layer,
The surface layer contains a fluorine resin and a fluorine oil having a perfluoropolyether structure,
The fixing member applies a crystal oscillator micrometer to a first surface opposite to the side facing the base layer for a measurement sample including the entire thickness portion of the surface layer taken from the fixing member. It has a perfluoropolyether structure that adheres to the unit area (1 cm ² ) of the detection surface when the detection surface of the balance (QCM) sensor is pressed at a pressure of 0.4 MPa at a temperature of 180 ° C. for 50 msec. Let P11 (ng) be the mass of the deposit containing fluorine oil,
The detection surface of a quartz crystal microbalance (QCM) sensor is placed against the second surface of the measurement sample on the side facing the base layer at a pressure of 0.4 MPa at a temperature of 180 ° C. for 50 msec. P21>P11, where P21 (ng) is the mass of a deposit containing fluorine oil having a perfluoropolyether structure, which adheres to a unit area (1 cm ² ) of the detection surface when pressed. A fixing member is provided.
Further, according to another aspect of the present invention, there is provided a fixing device including the above-described fixing member and heating means for the fixing member.
Further, according to another aspect of the present invention, there is provided an electrophotographic image forming apparatus including the fixing device described above.

According to one aspect of the present invention, it is possible to obtain a fixing member that can maintain excellent toner releasability even in long-term use. Further, according to another aspect of the present invention, it is possible to obtain a fixing device that contributes to stable formation of high-quality electrophotographic images. Furthermore, according to another aspect of the present invention, it is possible to obtain an electrophotographic image forming apparatus capable of stably forming high-quality electrophotographic images over a long period of time.

4 is a fixing member surface observation image described in Example 1. FIG. 10 is a fixing member surface observation image described in Comparative Example 4. FIG. 1 is a schematic cross-sectional view of a fixing belt that is an example of the present invention; FIG. 1 is a schematic cross-sectional view of a fixing device using a fixing belt according to the present invention; FIG. 1 is a schematic cross-sectional view showing one embodiment of an electrophotographic image forming apparatus of the present invention; FIG. FIG. 4A is a schematic cross-sectional view of the fixing member according to the present invention, and FIG. 4B is a schematic view of the amount of fluorine oil in the surface layer.

According to studies by the present inventors, it was confirmed that the fixing member according to Patent Document 1 has excellent toner releasability. Therefore, the present inventors subjected the fixing member according to Patent Document 1 to heat fixing under conditions in which the surface temperature is as high as 200° C., but the outer surface of the fixing member deteriorates due to long-term use. It has been found that the toner releasability may be lowered and hot offset may occur.
It is considered that such deterioration in toner releasability over time is caused by long exposure to high temperature conditions. That is, the chemical bonding portion between the compound having a perfluoropolyether chain or perfluoroalkyl chain and the fluororesin, which contributes to the improvement of toner releasability, is decomposed, and these compounds are released onto the outer surface of the fixing member. This is thought to be because it was lost from
Therefore, the inventors of the present invention conducted extensive studies with the aim of obtaining a fixing member that can maintain excellent toner releasability even after long-term use. As a result, the inventors have found that the fixing member according to the above-described aspects can well achieve such objects. The fixing member according to each aspect will be described in detail below.

A fixing member according to an aspect of the present invention has a base layer and a surface layer provided on the outer surface of the base layer directly or via a primer layer. The surface layer consists of a single layer and contains a fluororesin and a fluorooil having a perfluoropolyether structure. Further, the fuser member satisfies requirements (i) and (ii).
Requirement (i): For a measurement sample taken from the fusing member and including the full thickness portion of the surface layer, cleaning predetermined locations on the first surface opposite the side facing the base layer. . After that, the detection surface of the crystal oscillator microbalance (QCM) sensor is pressed against this position at a pressure of 0.4 MPa at a temperature of 180° C. for 50 msec. At this time, the mass P11 of the deposit containing fluorine oil adhering to the unit area (1 cm ² ) of the detection surface is 1.0×10 ² ng or more and 1.0×10 ⁴ ng or less.
Requirement (ii): For the measurement sample subjected to the treatment specified in requirement (i) above, clean the location. After that, it is placed in an environment at a temperature of 180° C. for 120 seconds, and then the detection surface of the QCM sensor is pressed to the position at a pressure of 0.4 MPa at a temperature of 180° C. for 50 msec. At this time, the mass P12 of the deposit containing fluorine oil adhering to the unit area (1 cm ² ) of the detection surface is 0.5×P11 or more and 1.2×P11 or less.

The treatment specified in the above requirement (i) is to remove the fluorine oil contained in the surface layer from the first surface opposite to the side of the surface layer facing the base layer (hereinafter sometimes referred to as the "outer surface"). ) is positioned as a process to shift to That is, the pressing conditions (pressure, temperature, pressing time) on the outer surface in the treatment specified in (i) above are the outer surface of the surface layer of the fixing member in the fixing nip during heat fixing in the electrophotographic image forming process. It is set as equivalent to the condition to be added to
Also, the amount of fluorine oil present on the outer surface of the fixing member can be measured using a crystal oscillator. Crystal oscillators have a sensitivity capable of measuring masses on the order of nanograms. A crystal oscillator has a structure in which both surfaces of a crystal plate of crystal are sandwiched between metal electrodes. When an alternating electric field is applied to the metal electrodes on both sides, the crystal vibrates at a certain frequency (resonance frequency) due to the reverse voltage drop of the crystal. Then, when a small amount of substance adheres to the metal electrode, the resonance frequency decreases in proportion to the amount of substance adhered. By utilizing this phenomenon, the crystal oscillator can be used as a microbalance.
The amount of change in the frequency of the crystal oscillator and the mass of the adhering substance on the metal electrode follow the following Sauerbrey formula (formula (a)).

（ΔＦ:周波数変化、Δｍ:質量変化量、Ｆ_０:基本周波数、ρ_Ｑ:水晶の密度、μ_Ｑ:水晶のせん断応力、Ａ:電極面積）
この測定方法は、水晶振動子マイクロバランス（Ｑｕａｒｔｚ Ｃｒｙｓｔａｌ Ｍｉｃｒｏｂａｌａｎｃｅ：ＱＣＭ）法とも称される。

(ΔF: frequency change, Δm: mass change, F ₀ : fundamental frequency, _ρQ : crystal density, _μQ : crystal shear stress, A: electrode area)
This measurement method is also called a Quartz Crystal Microbalance (QCM) method.

Furthermore, "cleaning" according to the above requirement (i) means placing a nonwoven fabric impregnated with ethanol at the position, applying a load of 20 kPa on the nonwoven fabric, and reciprocating the position 10 times. Subsequently, a nonwoven fabric impregnated with toluene is placed at the position, and a load of 20 kPa is applied to the nonwoven fabric, and the position is reciprocated 10 times. This mechanically removes the fluorine oil present on the outer surface. On the other hand, since ethanol and toluene do not dissolve PFPE, they do not elute PFPE present in the surface layer.
Therefore, the above requirement (i) is such that the amount of fluorinated oil existing inside the surface layer seeps out to the first surface of the surface layer due to the pressing treatment specified in requirement (i) is 1.0. x10 ² ng or more and 1.0 x 10 ⁴ ng or less. By setting P11 within the above numerical range, adhesion of toner to the outer surface of the fixing member during heat fixing can be significantly suppressed. As a result, it is possible to prevent the occurrence of toner offset during heat fixing, and it is also possible to prevent the occurrence of offset due to cohesive failure of toner caused by the viscosity of fluorine oil. Moreover, P11 is more preferably 1.0×10 ² ng or more and 5.0×10 ³ ng or less.
A method for preparing a measurement sample containing the entire thickness of the surface layer from the fixing member includes the following method. For example, when the fixing member has a structure in which a primer layer and a surface layer are sequentially laminated on a base layer, a method of cutting out a laminate of the primer layer and the surface layer and removing the primer layer from the laminate can be used. As a method for removing the primer layer from the laminate, there is a method of peeling off the primer layer from the interface with the surface layer with a knife, or a method in which the fluororesin in the surface layer does not dissolve but the resin component in the primer layer can dissolve. A method of dissolving and removing only the primer layer using a solvent can be used. For example, when the primer layer contains silicone rubber, only the primer layer can be dissolved and removed from the laminate by using a resin dissolving agent (trade name: eSolv 21RS, manufactured by Kaneko Chemical Co., Ltd.).

Next, in the treatment according to requirement (ii), the measurement sample in which the fluorine oil contained in the surface layer is transferred to the first surface of the surface layer by the treatment according to requirement (i) is subjected to requirement (i) Cleaning is performed to remove the fluorine oil that has migrated to the first surface by the treatment according to . Next, after the measurement sample has been placed in a predetermined environment, a treatment is performed to transfer fluorine oil from the inside of the measurement sample to the first surface. Here, "cleaning" refers to the same operation as "cleaning" in requirement (i). Then, in the fixing member according to this aspect, when the mass of the deposit containing fluorine oil that adheres to the unit area of the detection surface of the QCM sensor when the process according to requirement (ii) is performed is P12, P12 is It is 0.5 times or more and 1.2 times or less of P11. This means that the first surface of the surface layer can exhibit excellent toner releasability even after removing the fluorine oil that has migrated to the outer surface by the treatment according to the above requirement (i). It means that the fluorine oil can migrate from the inside of the surface layer to the outer surface.
That is, in the fixing member that satisfies the requirements (i) and (ii) above, even if the fluorine oil on the outer surface is once consumed in one heat fixing step, the fluorine oil is supplied from the inside of the surface layer to the outer surface, High toner releasability can be maintained over a long period of time.
A tack tester (trade name: TAC-1000, manufactured by Lesca Co., Ltd.), for example, can be used for the pressing treatment according to the above requirements (i) and (ii). Specifically, a crystal oscillator is placed on the stage of the testing machine. On the other hand, a measurement sample including the full thickness portion of the surface layer taken from the fixing member is fixed to the probe of the testing machine such that the first surface of the measurement sample faces the crystal oscillator. Next, the probe is brought close to the stage portion to press the first surface of the measurement sample against the crystal oscillator. The pressing conditions are as follows.
- Pressure: 0.4 MPa,
・Pressing time: 50 msec,
・Push amount constant mode,
・Pressing and lifting speed: 1.0 mm/sec,
• Probe setting temperature: 180°C.

1. Fixing Member FIG. 3 is a sectional view showing an aspect of the fixing member according to the present invention. FIG. 3 shows a fixing member having an endless belt shape (hereinafter also referred to as "fixing belt 11").
The fixing member according to FIG. 3 has a base layer 12 and a surface layer 13 directly covering the outer surface thereof. The surface layer 13 may be provided on the outer surface of the base layer 12 via a primer layer (not shown).
FIG. 6A shows the base layer 12, the surface layer 13, and the first surface (outer surface) 13a of the surface layer 13 opposite to the side facing the base layer and the base layer 13a of the fixing member according to this embodiment. is a cross-sectional view showing the relationship with the second surface 13b on the side facing the . FIG. 6B shows that when comparing the mass P11 of the fluorine oil on the first surface and the mass P21 of the fluorine oil on the second surface in the surface layer 13, P21 is larger than P11.

(1) Base Layer Materials for the base layer 12 include metals and alloys such as aluminum, iron, stainless steel and nickel, and heat-resistant resins such as polyimide.
In the fixing belt 11, as the base layer 12, a base material having an endless belt shape may be used. Materials of the base layer 12 in this case include, for example, nickel, stainless steel, and polyimide, which are excellent in heat resistance. Although the thickness of the base layer 12 is not particularly limited, it is preferably 20 μm or more and 100 μm or less from the viewpoint of strength, flexibility, and heat capacity.
The outer surface of the base layer 12 may be surface-treated in order to impart adhesiveness to the surface layer 13 . For the surface treatment, it is possible to use one or a combination of physical treatments such as blasting, lapping and polishing, and chemical treatments such as oxidation, coupling agent and primer treatments. Examples of primers used for primer treatment include paints in which a silane coupling agent, silicone polymer, hydrogenated methylsiloxane, alkoxysilane, a reaction accelerating catalyst, and a colorant such as red iron oxide are appropriately blended and dispersed in an organic solvent. be done.

(2) Surface Layer The surface layer 13 contains fluorine resin and fluorine oil having a perfluoropolyether (PFPE) structure. Then, the surface layer satisfies the requirements (i) and (ii) described above.
A fixing member that satisfies requirements (i) and (ii) can be achieved, for example, by a surface layer that contains a larger amount of fluorine oil on the base layer side than on the outer surface side in the thickness direction of the surface layer.
For example, for a measurement sample including the entire thickness portion of the surface layer taken from the fixing member, the detection surface of a quartz crystal microbalance (QCM) sensor is measured against the second surface on the side facing the base layer. is pressed at a pressure of 0.4 MPa at a temperature of 180° C. for 50 msec. At this time, when the mass P21 (ng) of the deposit containing fluorine oil having a perfluoropolyether structure that adheres to the unit area (1 cm ² ) of the detection surface, P21 and P11 are represented by the following formula (1). A fusing member exhibiting a relationship can achieve requirements (i) and (ii).

P21>P11 (1)

Since both the fluororesin and the fluorooil have small surface free energies, it was thought that it would be difficult to cause them to interact without causing phase separation. However, the present inventors have found that by bringing the fluorine oil into contact with the outer surface of the surface layer at a temperature near the melting point of the fluorine resin in the surface layer, the fluorine oil is phase-separated from the fluorine resin in the surface layer. It has been found that it can be contained without Further, when the fluorine oil is contained in the surface layer by such a method, in the thickness direction of the surface layer, the fluorine oil penetrates to the vicinity of the interface with the base layer in the surface layer, and the vicinity of the interface had a higher fluorine oil concentration than the first surface side of the surface layer.
The reason why the concentration of the fluorine oil is higher on the side of the surface layer closer to the base layer is not clear, but is presumed as follows. First, by bringing the fluoro-oil into contact with the fluoro-resin near the melting point, the fluoro-oil rapidly diffuses in the fluoro-resin and reaches the vicinity of the interface with the base layer. Next, in the process of cooling the surface layer from near the melting point of the fluororesin to room temperature, molecular contraction of the fluororesin in the surface layer occurs, and fluorine oil is released from the first surface side to the first surface of the surface layer. . As a result, it is considered that the concentration of fluorine oil in the surface layer is higher on the side of the interface with the base layer than on the first surface side of the surface layer.
By forming such a concentration gradient of the fluorine oil in the surface layer, the surface layer functions as a reservoir of the fluorine oil. Therefore, even if the fluorine oil on the first surface of the surface layer is consumed during heat fixing, the fluorine oil in the surface layer is continuously supplied to the first surface by the principle of substance diffusion, and long-term use It is considered that the toner releasability of the outer surface of the fixing member is also maintained.

The concentration difference of the fluorine oil between the first surface side and the interface side with the base layer in the thickness direction of the surface layer can be easily confirmed by, for example, infrared spectroscopy.

Any method can be used for the production of the fixing member according to this aspect as long as the fluorine oil containing the PFPE structure can be contacted and impregnated at a temperature near the melting point of the fluorine resin contained in the surface layer. The surface layer to be brought into contact with the fluorine oil may be the surface layer of the fixing member in which the base layer and the surface layer are laminated in advance. Moreover, as a contact method, for example, a dipping method can be used.
Specifically, for example, when the surface layer contains PFA as a fluororesin, it can be obtained through the following steps a) to c).
Step a) A pre-fixing member laminated with a base layer and a resin layer containing PFA is attached to a dipping device.
Step b) The pre-fixing member is immersed in a fluorine oil bath that has been preheated to near the melting point of PFA (300° C.±50° C.) and left for 5 minutes.
Step c) After removing the pre-fixing member from the fluorine oil bath, the PFPE adhering to the outer surface of the resin layer is removed, and the member is cooled to room temperature.
The temperature of the fluorine oil bath in step b) has a correlation with the amount of fluorine oil impregnated into the resin layer, and the higher the temperature, the higher the impregnation amount. Also, the contact time may be several to several tens of minutes. There are no particular restrictions on the method for removing the excess amount of PFPE adhering to the surface, but examples include cleaning with a fluorine solvent and removing with air.
The method of supplying fluorine oil to the outer surface of the resin layer is not limited to the dipping method described above. For example, as a method of supplying fluorine oil to the outer surface of the resin layer, known coating methods such as spray coating, roll coating, and beam coating can be used.

<Fluororesin>
The fluororesin is not particularly limited, and specific examples include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), Crystals of polychlorotetrafluoroethylene (PCTFE), tetrafluoroethylene-ethylene copolymer (ETFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), etc. fluororesins, and amorphous fluororesins having a cyclic perfluoropolyether structure. In particular, PFA can be preferably used from the viewpoint of heat resistance, mechanical strength, and workability.
PFA is a copolymer of perfluoroalkyl vinyl ether (hereinafter referred to as "PAVE") and tetrafluoroethylene (hereinafter referred to as "TFE"), and PAVE is perfluoromethyl vinyl ether (CF ₂ =CF- O--CF ₃ ), perfluoroethyl vinyl ether (CF ₂ =CF--O--CF ₂ CF ₃ ) and perfluoropropyl vinyl ether (CF ₂ =CF--O--CF ₂ CF ₂ CF ₃ ).

Commercially available products can be used as PFA, and specific examples are given below.
- "451HP-J", "959HP-Plus", "350-J", "950HP-Plus" (all trade names, manufactured by Mitsui Chemours Fluoro Products);
- "P-66P", "P-66PT", "P-802UP" (all trade names, manufactured by AGC);
- "AP-230", "AP-231SH", etc. (both trade names, manufactured by Daikin Industries, Ltd.);
- "6502N" (trade name, manufactured by 3M).
Regarding PFA, the impregnation amount of PFPE correlates with the PAVE content in PFA, and the impregnation increases as the PAVE content increases. It is considered that this is because the fluorine oil easily interacts with the amorphous portion of PFA, which has high molecular mobility. The content of PAVE in PFA is preferably 1 mol % or more and 5 mol % or less, more preferably 3 mol % or more and 5 mol % or less, in the molecular chain. The PAVE content can be calculated by measuring 19F NMR.
Among the above commercially available PFA, "451HP-J", "959HP-Plus", "950HP-Plus", "P-66P", "P-66PT", "AP-231SH", "6502N", "AW- Table 1 shows the PAVE content ratio of "5000L".

<Fluorine oil>
Fluorine oil has a perfluoropolyether structure, and specific examples include perfluoropolyether (PFPE) having a structure represented by the following structural formula (1). Among such PFPE, those that become oily at the melting point of the fluororesin are preferably used.

(In Structural 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 a, b, c, and d At least one is a positive integer.)
In addition, the order of existence of each repeating unit in Structural Formula (1) is not limited to the order described in Structural Formula (1). Furthermore, each repeating unit may exist at multiple locations in the PFPE represented by Structural Formula (1). That is, the PFPE represented by Structural Formula (1) may be a block copolymer or a random copolymer.
From the viewpoint of heat resistance, the molecular weight of PFPE is preferably 5,000 or more, particularly 7,000 or more, in terms of number average molecular weight. From the viewpoint of ease of interaction with the fluororesin during contact, it is preferably 100,000 or less, particularly preferably 30,000 or less. PFPE having the above molecular weight has a weight loss of less than 1% even when heated at 350° C. for 30 minutes in the air, and undergoes very little thermal decomposition even at a temperature near the melting point of the fluororesin.
The content of PFPE in the surface layer is preferably 1.0% by mass or more and 25% by mass or less with respect to the total amount of the fluororesin and PFPE. If it is less than 1% by mass, the releasability of the surface layer cannot be improved.

Specific examples of PFPE having a structure included in the structure represented by Structural Formula (1) are given below. Examples include those having at least one chemical structure selected from the group consisting of structural formulas (2) to (4).
- PFPE having a structure represented by structural formula (2) (for example, "Demnum S200" and "Demnum S100" (both trade names; manufactured by Daikin Industries, Ltd., referred to as "Demnum type")):

(In Structural Formula (2), n represents an integer of 1 or more.)
- PFPE having a structure represented by structural formula (3) (e.g., "Krytox GPL107", "Krytox GPL106", "Krytox 143AD", "Krytox VPF16256", "Krytox XHT-500", "Krytox XHT-750" , "Krytox XHT-1000" (both trade names; manufactured by Chemours, referred to as "Krytox type")):

(In Structural Formula (3), n represents an integer of 1 or more.)
- PFA represented by structural formula (4) (e.g., "Fomblin M60" and "Fomblin M30" (both trade names, manufactured by Solvay; referred to as "Fomblin type")):

(In Structural Formula (4), m and n each independently represent an integer of 1 or more.)
The perfluoropolyether impregnation amount correlates with the solubility parameter. Specifically, it can be controlled by the SP value difference (ΔHSP value) between the fluororesin and the perfluoropolyether calculated from the Hansen solubility parameter (HSP value). The smaller the ΔHSP value between the two components, the easier they are to dissolve, ie, the more miscible they are, and the higher the pick-up.
The ΔHSP value can be calculated using the 3rd Edition 3.1.14 of "HSPiP" calculation software with a database developed and sold by the Hansen Group. When the present inventors calculated the ΔHSP values of PFA and PFPE, Krytox type = 2.8, Demnum type = 3.6, Fomblin type = 5.4, and the affinity with PFA differs depending on the chemical structure of PFPE I found out. That is, when PFPE of each chemical structure is brought into contact with PFA under the same conditions, the Krytox type is most compatible with PFA.
The thickness of the surface layer 13 is 3.0 μm or more, preferably 5.0 μm or more, and particularly preferably 10 μm or more, from the viewpoint of suppressing wear of the surface during use of the fixing member. In addition, from the viewpoint of suppressing a decrease in thermal conductivity in the thickness direction of the fixing member, the thickness is preferably 50 μm or less, particularly 40 μm or less.

2. Thermal Fixing Device A thermal fixing device according to an aspect of the present invention includes a heating rotator and a pressurizing rotator arranged so as to form a fixing nip portion with the heating rotator. . Examples of a combination of a heating rotating body and a pressing rotating body include, for example, a heating roller and an elastic pressure roller disposed opposite to the heating roller, and a heating film and a heating film disposed in contact with the heating roller. An elastic pressure roller can be mentioned. Other examples of the combination of the heating rotator and the pressurizing rotator include a heating belt and an elastic pressure roller arranged in contact with the heating belt, and a heating belt and an elastic pressure roller arranged in contact with the heating belt. An elastic pressure belt or the like can be used.

FIG. 4 is a cross-sectional view in a direction perpendicular to the longitudinal direction of the thermal fixing device including the fixing belt 11 for heating and the elastic pressure roller 19. As shown in FIG.
The fixing belt 11 is a fixing belt according to one aspect of the present invention. The fixing belt 11 is loosely fitted around the belt guide member 16 . The pressurizing rigid stay 18 is inserted inside the belt guide member 16 . The belt guide member 16 is made of, for example, heat-resistant and heat-insulating resin.
A ceramic heater 17 as a heat source is provided at a position where the belt guide member 16 and the inner surface of the fixing belt 11 are in contact with each other. The ceramic heater 17 is fitted into a groove provided along the longitudinal direction of the belt guide member 16 and fixed. The ceramic heater 17 is energized by a means (not shown) to generate heat.
The elastic pressure roller 19 has, for example, an elastic layer 19b containing cured silicone rubber on the peripheral surface of a metal core 19a made of stainless steel. A surface layer 19c containing a fluororesin is provided on the peripheral surface of the elastic layer 19b. The thickness of the surface layer 19c is, for example, 50 μm.
By compressing pressure springs (not shown) between both ends of the pressurizing rigid stay 18 and spring receiving members (not shown) on the device chassis side, a downward force is applied to the pressurizing rigid stay 18 . ing. As a result, the lower surface of the ceramic heater 17 arranged on the lower surface of the belt guide member 16 and the upper surface of the elastic pressure roller 19 are pressed against each other with the fixing belt 11 interposed therebetween to form a predetermined fixing nip portion N. FIG. That is, the lower surface of the ceramic heater 17 is arranged in contact with the inner peripheral surface of the fixing belt 11 .
The recording medium P to be heated, on which an image is formed by the unfixed toner G in the fixing nip portion N, is nipped and conveyed at a conveying speed V. As shown in FIG. This heats and presses the toner image. As a result, the toner image is fused and color-mixed, and then cooled to fix the toner image on the recording medium P. FIG.

3. Image Forming Apparatus Image forming apparatuses include multi-function machines, copiers, facsimiles, and printers using an electrophotographic system. Here, using a color laser printer as an example, the general configuration of the image forming apparatus will be briefly described.
FIG. 5 is a schematic cross-sectional view of a laser printer 40 according to one aspect of the invention. The laser printer 40 shown in FIG. 5 includes electrophotographic photosensitive drums 39 (hereinafter referred to as “photosensitive drums”) rotating at a constant speed for each of yellow (Y), magenta (M), cyan (C), and black (K). (referred to as "drum 39"). It also has an intermediate transfer member 38 which holds the color image developed in the image forming section and multiple-transferred, and further transfers it onto the recording medium P fed from the feeding section.
The photosensitive drums 39 (39Y, 39M, 39C, 39K) are driven to rotate counterclockwise as shown in FIG. 5 by driving means (not shown).
Around the photosensitive drum 39, charging devices 21 (21Y, 21M, 21C, 21K) for uniformly charging the surface of the photosensitive drum 39 are arranged in order according to the rotation direction of the photosensitive drum 39, and a laser beam is irradiated based on image information. , a scanner unit 22 (22Y, 22M, 22C, 22K) that forms an electrostatic latent image on the photosensitive drum 39, a developing unit 23 (23Y, 23M, 23C, 23K), primary transfer rollers 24 (24Y, 24M, 24C, 24K) that transfer the toner image on the photosensitive drum 39 onto the intermediate transfer member 38 at the primary transfer portion T1, and remaining on the surface of the photosensitive drum 39 after transfer. A cleaning unit 25 (25Y, 25M, 25C, 25K) having a cleaning blade for removing residual toner is arranged.

During image formation, a belt-like intermediate transfer member 38 stretched around rollers 26, 27 and 28 rotates, and each color toner image formed on each photoreceptor drum 39 is superimposed on the intermediate transfer member 38 to form a primary image. A color image is formed by being transferred.
The recording medium P is conveyed to the secondary transfer portion T2 by the conveying means so as to be synchronized with the primary transfer onto the intermediate transfer member . The conveying means has a feed cassette 29 containing a plurality of recording media P, a feed roller 30 , a separation pad 31 and a registration roller pair 32 . At the time of image formation, the feed roller 30 is driven and rotated according to the image forming operation, and the recording medium P in the feed cassette 29 is separated one by one. It is conveyed to the transfer section T2.
A movable secondary transfer roller 33 is arranged in the secondary transfer portion T2. The secondary transfer roller 33 is movable substantially vertically. During image transfer, the secondary transfer roller 33 is pressed against the intermediate transfer member 38 with the recording medium P therebetween with a predetermined pressure. At the same time, a bias is applied to the secondary transfer roller 33 and the toner image on the intermediate transfer member 38 is transferred to the recording medium P.
Since the intermediate transfer member 38 and the secondary transfer roller 33 are driven respectively, the recording medium P sandwiched between them is transported at a predetermined transport speed V in the direction of the left arrow shown in FIG. The belt 34 conveys the sheet to the fixing section 35 which is the next step. The fixing unit 35 applies heat and pressure to fix the transferred toner image on the recording medium P. FIG. The recording medium P is discharged onto a discharge tray 37 on the upper surface of the apparatus by a discharge roller pair 36 .
By applying the fixing device of the present invention illustrated in FIG. 4 to the fixing section 35 and the secondary transfer roller 33 of the electrophotographic image forming apparatus illustrated in FIG. An image forming apparatus capable of providing images can be obtained.

EXAMPLES The present invention will be specifically described below using examples. In addition, the present invention is not limited to the following examples.

In this example, a fixing member was manufactured using the following fluororesin and fluorooil.
(fluororesin)
PFA-1: "959HP-Plus" (trade name, manufactured by Mitsui Chemours Fluoro Products)
PFA-2: "451HP-J" (trade name, manufactured by Mitsui Chemours Fluoro Products)
PFA-3: “950HP-Plus” (trade name, manufactured by Mitsui Chemours Fluoro Products)
PFA-4: "P66P" (trade name, manufactured by AGC)
PFA-5: "AW-5000L" (trade name, manufactured by Daikin Industries, Ltd.)
(Fluorine oil)
PFPE-1: "Krytox GPL107" (trade name, manufactured by Chemours)
PFPE-2: "Krytox GPL106" (trade name, manufactured by Chemours)
PFPE-3: "Demnum S200" (trade name, manufactured by Daikin Industries, Ltd.)
PFPE-4: "Krytox 143AD" (trade name, manufactured by Chemours)
PFPE-5: "Krytox VPF16256" (trade name, manufactured by Chemours)
PFPE-6: "Krytox XHT-1000" (trade name, manufactured by Chemours)
PFPE-7: "Fomblin M60" (trade name, manufactured by Solvay)

(Example 1)
(Fabrication of pre-fixing belt)
As a base layer, a base layer having an inner diameter of 30 mm, a width of 400 mm, and a thickness of 40 μm and having an endless belt shape made of nickel electroforming was prepared. An addition-curing silicone rubber adhesive (trade name: SE1819CV, a mixture of equal amounts of “Liquid A” and “Liquid B” manufactured by Dow Corning Toray Co., Ltd.) was applied as a primer to the outer peripheral surface of this base layer to a thickness of approximately 20 μm. It was applied almost evenly so as to be about the same.
As a surface layer, a fluororesin tube (PFA-1, 20 μm thick, melting point 296° C.) whose inner surface is hydrophilically treated is covered, and the belt surface is uniformly treated from above the fluororesin tube to remove excessive addition-curable silicone rubber adhesion. The agent was drawn out from between the base layer and the fluororesin tube.
Then, a base layer having a peripheral surface covered with a fluororesin tube was placed in an electric furnace set at a temperature of 200°C. The addition-curable silicone rubber adhesive was cured by heating for 1 hour to fix the fluororesin tube on the outer peripheral surface of the base layer via a primer layer (hardened addition-curable silicone rubber adhesive). Finally, both ends were cut to obtain a pre-fixing belt with a width of 343 mm.

(Contact impregnation of fluorine oil)
Perfluoropolyether (PFPE-1) was placed in a borosilicate glass graduated cylinder. A heating wire covered with a heat insulating material was wrapped around the entire graduated cylinder and heated so that the PFPE temperature reached 285°C. The prepared pre-fixing belt was attached to a dipping device, and the entire fixing belt was immersed in heated PFPE. After 5 minutes, the pre-fixing belt was removed. After that, the pre-fixing belt was immersed in a graduated cylinder containing a separately prepared fluorinated solvent (trade name: Novec 7300, manufactured by 3M) to remove excess PFPE adhering to the surface of the fixing belt. After drying the fluorine-based solvent, the fixing belt No. 1 was produced. Fixing belt No. For 1, two sets were prepared for evaluation to be described later.
Also, fixing belt No. FIG. 1 shows a photograph of the first surface of No. 1 observed with an SEM. Aggregation of PFPE could not be observed, suggesting that PFA and PFPE are compatible with each other.

<Evaluation>
Three sets of measurement samples used for evaluations 1 to 3 were prepared as follows.
(Preparation of measurement sample)
Fixing belt No. 1, a laminate (10 mm in diameter) of the primer layer and the surface layer was cut out. Next, the laminate is immersed in a primer layer dissolving agent (trade name: e-Solv 21RS, manufactured by Kaneko Chemical Co., Ltd.) to dissolve the silicone rubber in the primer layer, thereby removing the primer layer from the laminate. A measurement sample was prepared that included a full thickness portion of the surface layer.
(Evaluation 1; measurement of fluorine oil adhesion amounts P11, P12 and P21)
The first surface of the measurement sample opposite the side facing the substrate was cleaned. That is, a nonwoven fabric impregnated with ethanol was placed on the first surface, and a load of 20 kPa was applied to the nonwoven fabric and the position was reciprocated 10 times. Subsequently, a nonwoven fabric impregnated with toluene was placed on the surface, and a load of 20 kPa was applied to the nonwoven fabric, and the position was reciprocated 10 times.
Next, the crystal oscillator is placed on the stage of a tack tester (trade name: TAC-1000, manufactured by Lesca Co., Ltd.), while the measurement sample is placed on the probe of the tack tester. It was attached so as to face the crystal unit. The probe was then brought close to the stage and pressed against the crystal oscillator against the first surface of the measurement sample. The pressing conditions are as follows.
- Pressure: 0.4 MPa,
・Pressing time: 50 msec,
・Push amount constant mode,
・Pressing and lifting speed: 1.0 mm/sec,
• Probe setting temperature: 180°C.
As a crystal oscillator, "6A202PN" (trade name, manufactured by Piezo Parts Co., Ltd.) having a fundamental frequency of about 6 MHz was used. Frequency characteristics before and after adhesion were measured using a QCM-D intermolecular interaction analysis system (Biolin Scientific AB) to measure changes in series resonance frequency Fs and frequency Fw representing loss of vibrational energy before and after pressing. The adhesion amount P11 of fluorine oil per unit area (1 cm 2 ) of the crystal oscillator was calculated from the above formula (a).
Immediately after the pressing process was completed, the measurement sample was removed from the probe and the first surface was cleaned as above. Next, after placing the measurement sample in an environment at a temperature of 180° C. for 120 seconds, the measurement sample was attached to the probe again and pressed against the crystal oscillator under the same pressing conditions as above. Then, changes in the series resonance frequency Fs and the frequency Fw representing loss of vibrational energy were measured, and the adhesion amount P12 of fluorine oil per unit area (1 cm ² ) of the crystal oscillator was calculated from the above equation (a).

(Evaluation 2: Fluorine oil content in surface layer)
The first and second surfaces of another measurement sample were cleaned. Next, this measurement sample was measured using a thermogravimetric analyzer (TGA) under the following conditions to calculate the content ratio (wt%) of the fluorine oil in the surface layer.
Apparatus: TGA851 (manufactured by METTLER TOLEDO);
Atmosphere: in air;
Temperature: 425°C.
In the measurement time-weight loss rate profile obtained by the thermogravimetric analysis, the linear least squares approximation formula is calculated from the region where the slope is constant and only PFA is decreasing (specifically after the measurement time is 3000 seconds). asked. The intercept of the linear least squares approximation formula was defined as the PFA content (wt%), and the PFPE content (wt%) was calculated as 100-PFA content.

(Evaluation 3: Relative ratio of PFPE amounts on the outermost surface side and the base layer side in the thickness direction of the surface layer)
The first and second surfaces of yet another measurement sample were cleaned. Next, using an infrared spectrometer (trade name: Frontier MIRNIR, manufactured by PerkinElmer), the measurement sample was measured by the ATR method from the first surface side and the second surface side, and the relative ratio of the PFPE amount (hereinafter referred to as "PFPE relative amount ratio") was calculated.
Specifically, from each profile obtained by infrared spectroscopic analysis, the height of peaks that appear only in PFPE (Krytox type: 986 cm ^-1 , Demnum type: 1010 cm ^-1 , Fomblin type: 1052 cm ^-1 ) , the peak ratio was calculated by dividing by the height of the peak (1146 cm ⁻¹ ) appearing only in PFA. Then, the PFPE relative amount ratio was calculated by dividing the peak ratio calculated from the measurement result of the second expression side by the peak ratio calculated from the measurement result of the first surface side.

(Evaluation 4: Evaluation of presence or absence of toner offset)
Fixing belt No. 1 was mounted on an electrophotographic image forming apparatus (trade name: imageRUNNER-ADVANCE C5051; manufactured by Canon Inc.) in which the angle of the paper separation claw was adjusted.
Then, an image forming process was performed to form a cyan solid image of 10 cm×10 cm on A4 size paper (manufactured by International Paper, basis weight 75 g/m ² ). The fixing temperature was 180° C., and the paper transport speed was 300 mm/sec.
Then, when the number of cyan solid images formed reached 1, 100, and 100,000, A4 size plain thin paper (trade name: CS-520, basis weight 52 g/m ² , Canon Co., Ltd.) was passed to form a solid cyan image of 10 cm×10 cm. The solid image formed on the plain thin paper was visually and microscopically observed and evaluated according to the following criteria.
(Evaluation criteria)
Rank A: No toner offset and no toner missing.
Rank B: A slight amount of toner offset and toner missing are confirmed. Rank C: Both toner offset and toner missing are confirmed.
Rank D: Plain thin paper sticks to the fixing belt.

(Evaluation 5: Measurement of surface free energy)
In evaluation 4, fixing belt No. 1 immediately before solid image formation on thin plain paper. The surface free energy of the outer surface of No. 1 was calculated by the "method of Kitazaki and Hata" described in Non-Patent Document 1. Specifically, fixing belt No. The contact angles of water, n-hexadecane, and diiodomethane were measured on the outer surface of No. 1 (measurement environment: temperature 23° C., relative humidity 55%).
Next, using the measurement results of each contact angle, "Extended Fowkes The surface free energy was obtained from the formula of
A contact angle meter (trade name: DM-501, manufactured by Kyowa Interface Science Co., Ltd.) was used to measure the contact angle, and analysis software (trade name: FAMAS, manufactured by Kyowa Interface Science Co., Ltd.) was used for surface free energy analysis. .

(Examples 2 to 18)
Fixing belt No. 1 according to each example was produced in the same manner as in Example 1, except that the type of fluororesin and the type of fluorooil used in the surface layer and the temperature of the fluorooil at the time of contact were changed as shown in Table 1. 2-18 were made.

(Example 19)
Fixing Belt No. 1 was prepared in the same manner as in Example 1, except that the contact time between the fixing member and fluorine oil was set to 1 minute. 19 was produced and subjected to evaluations 1 to 5.

(Example 20)
In Example 1, except that a solution obtained by diluting PFPE with a fluorine-based solvent (trade name: Novec 7300, manufactured by 3M) was spray-coated on the surface of the fixing member, and then placed in a drying oven and heated at 285° C. for 5 minutes. In the same manner as in Example 1, fixing belt No. 20 was made.

(Comparative example 1)
A pre-fixing belt was prepared by the method described in Example 1, and was used as Fixing Belt No. 1 according to this comparative example. C-1.

(Comparative example 2)
Fixing belt No. The outer surface of C-1 was coated with sodium naphthalene (trade name: Tetraetch, manufactured by Junkosha) to chemically hydrophilize the outer surface.
Next, PFPE (trade name: OPTOOL DSX, manufactured by Daikin Industries, Ltd.) whose molecular ends were modified with alkoxysilane was dissolved in a fluorine-based solvent (trade name: Novec7300, manufactured by 3M). After the solution was applied to the hydrophilic outer surface, it was baked in a drying oven heated to 120° C. for 1 hour to chemically fix the PFPE. After that, the outer surface to which the PFPE was chemically fixed was washed with the fluorine-based solvent, and fixing belt No. 1 according to this comparative example was obtained. C-2 was produced.

(Comparative Example 3)
Fixing belt no. C-3 was produced.
(Comparative Example 4)
The method described in Example 1 was used to prepare the primed substrate. The surface of the substrate was treated with excimer UV.
Two spray guns were then provided. One of the spray guns was filled with a water-based dispersion paint of PFA particles (trade name: AW-5000L, manufactured by Daikin Industries, Ltd., melting point 300°C). The other spray gun was filled with a solution of PFPE-1 dissolved in a fluorine-based solvent (trade name: Novec7300, manufactured by 3M). Using these spray guns, the surface of the base layer was coated with a PFA water-based dispersion paint and PFPE to form a 20 μm-thick coating film containing PFA particles and PFPE. At this time, the coating amount of the spray gun was adjusted so that the content of PFPE-1 in the coating film was 2.0 wt %.
Next, the coating film was heated at a temperature of 350° C. for 15 minutes to melt the PFA particles in the coating film, form a surface layer, and obtain a fixing member according to Comparative Example 5. The fluorine oil content, P11, P12, P21, and PFPE relative amount ratio in the surface layer were calculated in the same manner as in Example 1, and evaluations 1 and 2 were performed. Further, FIG. 2 shows a photograph of the outermost surface side of the surface layer observed by SEM. Aggregation of PFPE can be observed, indicating that PFA and PFPE are not compatible with each other.
Fixing belt No. 2 to 20, and fixing belt No. C-1 to C-4 were subjected to evaluation 1 to evaluation 5. The results are shown in Tables 2 and 3.

Table 3 shows the results of evaluation 1 and evaluation 2 of the fixing members produced in Examples 1 to 20 and Comparative Examples 1 to 7.

From Table 3, it was found that the fixing member according to this embodiment can maintain excellent toner releasability even after long-term use, and as a result, high-quality electrophotographic images can be formed.

11 fixing belt 12 base layer 13 surface layer

Claims (14)

An electrophotographic fixing member comprising a base layer and a surface layer provided on the outer surface of the base layer directly or via a primer layer,
The surface layer consists of a single layer,
The surface layer comprises a fluororesin, a fluorooil having a perfluoropolyether structure,
including
A fuser member characterized in that the fuser member satisfies requirement (i) and requirement (ii):
(i) after cleaning predetermined locations on a first surface of a first surface opposite the side facing the base layer of a measurement sample taken from the fusing member and including a full thickness portion of the surface layer; At this position, the detection surface of the crystal oscillator microbalance (QCM) sensor is pressed at a pressure of 0.4 MPa at a temperature of 180 ° C. for 50 msec, and the unit area of the detection surface The mass P11 of the deposit containing fluorine oil having a perfluoropolyether structure attached to (1 cm ² ) is 1.0×10 ² ng or more and 1.0×10 ⁴ ng or less;
(ii) For the measurement sample subjected to the treatment specified in the requirement (i), after cleaning the position, place it in an environment with a temperature of 180 ° C. for 120 seconds, and then place a crystal oscillator microbalance ( QCM) A perfluoropolyether structure that adheres to a unit area (1 cm ² ) of the detection surface when the detection surface of the sensor is pressed at a pressure of 0.4 MPa at a temperature of 180 ° C. for 50 msec. is 0.5×P11 or more and 1.2×P11 or less. An electrophotographic fixing member comprising a base layer and a surface layer provided on the outer surface of the base layer directly or via a primer layer,
The surface layer consists of a single layer,
The surface layer comprises a fluororesin, a fluorooil having a perfluoropolyether structure,
including
A quartz crystal microbalance (QCM) sensor is applied to a first surface opposite the side facing the base layer of a measurement sample taken from the fusing member and including a full thickness portion of the surface layer. Attachment containing fluorine oil having a perfluoropolyether structure that adheres to a unit area (1 cm ² ) of the detection surface when the detection surface is pressed at a pressure of 0.4 MPa at a temperature of 180 ° C. for 50 msec Let the mass of the kimono be P11 (ng),
The detection surface of a quartz crystal microbalance (QCM) sensor is placed against the second surface of the measurement sample on the side facing the base layer at a pressure of 0.4 MPa at a temperature of 180 ° C. for 50 msec. When P21 (ng) is the mass of the deposit containing fluorine oil having a perfluoropolyether structure, which adheres to a unit area (1 cm ² ) of the detection surface when pressed,
A fixing member characterized in that P21>P11. 3. The fixing member according to claim 1, wherein the content of the fluorine oil having a perfluoropolyether structure in the surface layer is 1.0% by mass or more and 25% by mass or less of the surface layer. The fixing member according to any one of claims 1 to 3, wherein the P11 is 1.0 x ¹⁰² ng or more and 5.0 x ¹⁰³ ng or less. The fixing member according to any one of claims 1 to 4, wherein the fluororesin is a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). The fixing member according to any one of claims 1 to 5, wherein the surface layer has a thickness of 5.0 µm or more and 50 µm or less. The fixing member according to any one of claims 1 to 6, wherein the fluorine oil is perfluoropolyether. 8. The fixing member according to claim 7, wherein the perfluoropolyether has a chemical structure represented by Structural Formula (1).

(In Structural 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 a, b, c, and d At least one represents a positive integer.) 8. The fixing member according to claim 7, wherein the perfluoropolyether has at least one chemical structure selected from structural formulas (2) to (4).

(In structural formulas (2) to (4), m and n each independently represent an integer of 1 or more.) The perfluoropolyether has the chemical structure of formula (2), the P11 is 1.0×10 ² ng or more and 5.0×10 ³ ng or less, and the content in the surface layer is 10. The fixing member according to claim 9, which is 1.0% by mass or more and 25% by mass or less of the surface layer. The fixing member according to any one of claims 1 to 10 , wherein the fixing member is a fixing belt having an endless belt shape. A fixing device comprising: the fixing member according to any one of claims 1 to 11; and heating means for the fixing member. 13. The fixing device according to claim 12, wherein the fixing member is a fixing belt having an endless belt shape, and the heating means is a heater arranged in contact with the inner peripheral surface of the fixing belt. An electrophotographic image forming apparatus comprising the fixing device according to claim 12 or 13.

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