JP2019015841A - Manufacturing method of fixing member - Google Patents

Abstract

To shape a fixing member in which a hole portion is isotopically formed on an elastic layer 4b without leaving flow hysteresis on a liquid rubber in the inner part of a mold 11 in the manufacturing method of a fixing member comprising the elastic layer and a substrate 4a composed of a rubber elastic material having a hole portion 4b1 which are manufactured by forming the hole portion in the inner part of the rubber composition heated and cured by evaporating water from the rubber composition and by heating the mold in a state that both end parts of the mold are opened by removing mold terminal members 6, 12, 7, and 13 which are mounted on one end side and the other end side of the mold after injecting the liquid rubber composition containing water into the inner part of the mold in which the substrate is held using the mold capable of holding, in an inner part 53, a substrate 4a of the fixing member 4 used in an image fixing device 10, heating the mold, and thereby heating and curing the rubber composition.SOLUTION: When a mold is heated and a rubber composition is heated and cured, a mold portion between a mold terminal member of one end side and the other end side of the mold is heated first before a mold portion between a mold terminal member one end side and the other end side of the mold is heated.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a fixing member used in an image fixing apparatus mounted on an image forming apparatus such as a copying machine, a printer, or a facsimile machine.

  2. Description of the Related Art An electrophotographic image forming apparatus includes a fixing device that fixes a toner image on a sheet by heating and pressing a toner image formed on a recording material (hereinafter referred to as a sheet). This fixing device includes a fixing member such as a heating roller (heating belt) or a pressure roller (pressure belt), and performs a fixing process at a position where the members are pressed against each other (fixing nip portion). ing.

  An example of the fixing device is a film (belt) heating type device. This apparatus has a heater as a heating member (heating source) having a heating resistor on a ceramic substrate. The heater has a fixing film as a heating member that rotates while making contact with the heater. A pressure roller (pressing rotating body) is provided as a nip portion forming member that presses the fixing film to form a nip portion and rotationally drives the fixing film.

  In such a fixing device, in order to shorten the “rise time” required to reach a predetermined temperature sufficient for heat-fixing the toner image, the heat capacity / thermal conductivity of the pressure roller is reduced. . For example, the rise time is shortened by forming the rubber elastic layer of the pressure roller into a porous elastic layer having a large number of pores and reducing the amount of heat transmitted to the pressure roller.

  In Patent Document 1, in order to form a large number of pores in the rubber elastic layer, a water-absorbing polymer that has absorbed water is emulsified and dispersed in a liquid silicone rubber, and the pores are formed by dehydrating the rubber after curing. Forming.

  Patent Document 2 discloses a technique for molding a rubber elastic layer of a pressure roller. Specifically, the core metal is set in the mold, and liquid rubber is injected between the inner surface of the mold and the outer surface of the core metal (hereinafter, casting method).

JP 2002-114860 A JP-A-4-158801

  However, according to verification by the present inventors, when trying to mold a porous elastic roller by a casting method using a liquid rubber composition in which water is emulsified and dispersed, the following problems may occur. found.

  When the sandwiching piece molds and cylindrical molds at both ends are heated uniformly from the outer surface, the liquid rubber inside moves from the vicinity of the longitudinal center of the cylindrical mold due to the influence of the piece mold having a large heat capacity on the outer surface area. Curing begins when the temperature rises. The fitting part between the two ends of the cylindrical mold and the piece that sandwiches it is easy to flow in a state where the liquid viscosity of the liquid rubber is low due to slow curing, and the expansion pressure from the longitudinal center part where the thermal expansion is large As a result, the liquid rubber slightly flows out from the gap between the fitting portions at either end. It has been found that the outflow of the liquid rubber gives a biased anisotropy to the emulsified and dispersed state of water after the rubber is cured by leaving a flow history in the liquid rubber inside the mold.

  In such a state, the porous elastic roller formed by evaporating and dewatering water to form a hole is used as a rotating body for pressing and driving such as a pressing roller in a fixing device of a film (belt) heating system, for example. When used, the following events are likely to occur. That is, the fixing film that rotates while being driven by the roller tends to come to one end portion of the roller, and the film is easily damaged and damaged by rubbing with the flanges that are both end restricting members of the film.

  An object of the present invention is to mold a fixing member in which pores are formed isotropically in an elastic layer without leaving a flow history in the liquid rubber inside the mold.

  In order to achieve the above object, a typical structure of a fixing member manufacturing method according to the present invention uses a mold capable of holding a fixing member base used in an image fixing apparatus, and the base is held by the base. A liquid rubber composition containing water is injected into the mold and the mold is heated to cure the rubber composition and then attached to one end and the other end of the mold. The inside of the rubber composition is heated and cured by evaporating water from the rubber composition by heating the mold in a state where both ends of the mold are opened with the mold terminal member being removed. In a method for producing a fixing member having an elastic layer made of a rubber elastic body having pores and a substrate, which is produced by forming pores in the substrate, the mold is heated to form the rubber composition. When heat-curing, the mold on one end side and the other end side of the mold Characterized by heating the mold terminal member before the mold parts of one end and the other end between the end members.

  According to the present invention, it is possible to mold a fixing member in which pores are formed isotropically in the elastic layer without leaving a flow history in the liquid rubber inside the mold.

It is a perspective view of the metal mold | die and the heating metal disc | board for heating it on both sides of it. 1 is a schematic cross-sectional view illustrating a configuration of a fixing device according to an embodiment. (A) is a perspective view which shows the whole structure of a pressure roller, (b) is an expansion perspective schematic diagram of the sample cut out from the elastic layer. It is a schematic diagram of an acicular filler. It is composition explanatory drawing of a metal mold | die. It is a form figure of the injection hole provided in the one end side piece type. It is explanatory drawing of the arrangement | positioning point of the roller base | substrate with respect to a metal mold | die. It is a schematic sectional drawing of the metal mold | die after a mold assembly. 1 is a schematic configuration diagram of an example of an electrophotographic image forming apparatus.

<< Embodiment >>
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, as a fixing member according to the present invention, a pressure roller as a porous elastic roller used in an image fixing apparatus will be described in detail as an example.

[Image forming apparatus]
FIG. 9 is a schematic configuration diagram of an example of an image forming apparatus. This image forming apparatus is an electrophotographic image forming apparatus, and includes a rotating electrophotographic photosensitive member 101. The image forming apparatus includes a charging device 102 and image exposure means 103 as electrostatic latent image forming means for the photosensitive member 101, and developing means 104 for developing the electrostatic latent image on the photosensitive member 101 as a toner image (developer image). The image forming apparatus includes a transfer unit 105 that transfers a toner image on the photoreceptor 101 to a sheet-like recording material (hereinafter referred to as paper or paper) P. The image forming apparatus includes a cleaning unit 106 that cleans the surface of the photosensitive member 101 after the transfer of the toner image, a fixing device 10 as a fixing unit that fixes the toner image T on the paper P, and the like.

[Fixing device]
FIG. 2 is a schematic cross-sectional view showing a schematic configuration of the fixing device 10 in the present embodiment. In the following description, regarding the fixing device and the members constituting the fixing device, the axial direction is a direction orthogonal to the paper transport direction on the surface of the paper. The length is an axial dimension.

  The fixing device 10 is a film (belt) heating type fixing device. A ceramic heater (hereinafter referred to as a heater) 1 as a heating body and a film guide (hereinafter referred to as a belt guide) 2 also serving as a heating body support member are provided. Further, an endless (cylindrical) flexible and heat resistant fixing film (hereinafter referred to as a fixing belt) 3 is provided as a heating member (fixing member). Further, a pressure roller 4 is provided as a nip portion forming member that forms a nip portion (fixing nip portion) N in pressure contact with the fixing belt 3.

  The heater 1 is an elongated plate-like member along the longitudinal direction of the fixing belt 3 (perpendicular to the drawing), and has a heat source such as a resistance heating element that generates heat when energized by power supply means (not shown). The temperature rises sharply due to power supply. The temperature of the heater 1 is detected by a temperature detection unit (not shown), and the detected temperature information is input to a control unit (not shown). The control means controls the power supplied from the power supply means to the heat generation source so that the detection temperature input from the temperature detection means is maintained at a predetermined fixing temperature, thereby adjusting the temperature of the heater 1 to a predetermined temperature.

  The heater 1 is supported by a belt guide 2 formed in a saddle shape having a substantially semicircular cross section by a rigid heat resistant material. More specifically, a groove 2a is provided on the outer surface of the belt guide 2 along the length of the guide, and the heater 1 is fitted into the groove 2a.

  The fixing belt 3 has an annular (cylindrical) base material 3a and a belt elastic layer 3b (herein referred to as a belt elastic layer in order to distinguish from an elastic layer 4b of a pressure roller 4 described later) from the inside to the outside. A surface layer 3c is provided. The fixing belt 3 is an endless belt whose inner peripheral surface is rubbed against the heater 1 and the belt guide 2 in a rotating state. The fixing belt 3 is externally fitted on the outer periphery of the belt guide 2 that supports the heater 1 with a margin in circumference. Yes.

  As will be described later, the heater 1 and the pressure roller 4 are in pressure contact with each other with the fixing belt 3 interposed therebetween, and a nip portion N is formed between the fixing belt 3 and the pressure roller 4. The pressure roller 4 is rotationally driven at a predetermined peripheral speed in a counterclockwise direction indicated by an arrow R4 by a rotation driving device M such as a motor. The fixing belt 3 rotates in the clockwise direction indicated by the arrow R3 while the inner surface of the fixing belt 3 is in close contact with the surface of the heater 1 and slides in accordance with the rotational driving of the pressure roller 4. Both ends in the longitudinal direction of the fixing belt 3 are rotatably supported by flanges (not shown) which are restricting members fixed to the fixing device 10.

  The holder 2 functions as a support member for the heater 1 and also functions as a rotation guide member for the fixing belt 3. Lubricant (grease) is applied to the inner peripheral surface of the fixing belt 3 in order to ensure slidability with the heater 2 and the holder 2. In the present specification, the term “belt” includes a film.

  The pressure roller 4 includes, from the inside to the outside, a solid round bar (columnar) or cylindrical (pipe) base 4a, an elastic layer 4b, and a release layer 4c. The pressure roller 4 is rotationally driven by a rotational driving device M such as a motor when the device is used. Therefore, both end portions in the axial direction of the base body 4a are rotatably supported by a fixed portion (not shown) such as a frame of the fixing device 10 via a bearing member.

  The pressure roller 4 is disposed at a position facing the heater 1 supported by the belt guide 2 and the fixing belt 3. Then, by applying a predetermined pressure to the pressure roller 4 and the fixing belt 3 by a pressure mechanism (not shown), the pressure roller 4 and the fixing belt 3 are brought into pressure contact with each elastic layer (3b, 4b) is elastically deformed. As a result, a nip portion N having a predetermined width is formed between the pressure roller 4 and the fixing belt 3 in the paper conveyance direction A (recording material conveyance direction).

  The pressing contact between the fixing belt 3 serving as a heating member and the pressure roller 4 serving as a nip forming member is configured such that the pressing roller 4 is pressed against the fixing belt 3 with a predetermined pressure. The structure which press-contacts to may be sufficient. Alternatively, the fixing belt 3 side and the pressure roller 4 may be pressed against each other with a predetermined pressure.

  When the pressure roller 4 is rotationally driven by the rotational driving device M, the pressure roller 4 conveys the paper P while pinching it at the nip portion N between the pressure roller 4 and the fixing belt 3 that rotates. The fixing belt 3 is heated by the heater 1 until the surface reaches a predetermined temperature (for example, 200 ° C.). In this state, the sheet P carrying the unfixed toner image T is introduced into the nip portion N and is nipped and conveyed, whereby the unfixed toner T on the sheet P is heated and pressurized. Then, since the unfixed toner T is melted / color mixed, the toner image is fixed on the paper P as a fixed image by cooling it thereafter.

[Fixing belt]
The fixing belt 3 will be described. As shown in FIG. 2, the fixing belt 3 is provided with a belt elastic layer 3b on the outer periphery of the substrate 3a and a surface layer 3c on the outer periphery of the belt elastic layer 3b. Considering that the base material 3a requires heat resistance and bending resistance, for example, a heat resistant resin such as polyimide, polyamideimide, polyetheretherketone (PEEK) or the like is used.

  If the thermal conductivity is also taken into consideration, the base material 3a may use a metal such as stainless steel (SUS), nickel, or a nickel alloy having higher thermal conductivity than the heat resistant resin. And since the base material 3a needs to make a mechanical strength high, while making heat capacity small, it is desirable that the thickness of the base material 3a shall be 5-100 micrometers, Preferably it is 20-85 micrometers.

  The belt elastic layer 3b is a silicone rubber layer that covers the outer periphery of the substrate 3a. The belt elastic layer 3 b uniformly applies heat to the unfixed toner T so as to wrap the unfixed toner T on the sheet P when the sheet P passes through the nip portion N. Since the belt elastic layer 3b functions in this manner, a high-quality image with high gloss and no unevenness in fixing can be obtained.

  The thickness of the belt elastic layer 3b is preferably 30 to 500 μm, preferably 100 in order to obtain a good quality image with sufficient elasticity, and to prevent the heat capacity from being delayed until reaching a predetermined temperature by heating. It is desirable that the thickness be ˜300 μm.

  Although the belt elastic layer 3b is not particularly limited, it is easy to process, it can be processed with high dimensional accuracy, and a reaction by-product is not generated at the time of heat curing. preferable. The addition reaction crosslinking liquid silicone rubber contains, for example, organopolysiloxane and organohydrogenpolysiloxane, and may further contain a catalyst and other additives. Organopolysiloxane is a base polymer that uses silicone rubber as a raw material, and a polymer having a number average molecular weight of 5,000 to 100,000 and a weight average molecular weight of 10,000 to 500,000 may be used.

  The liquid silicone rubber is a polymer having fluidity at room temperature, but is cured by heating, has a moderately low hardness after curing, and has sufficient heat resistance and deformation recovery ability. Therefore, the liquid silicone rubber is suitable not only for the belt elastic layer 3b but also for the elastic layer 4b of the pressure roller 4 described later.

  By the way, if the belt elastic layer 3b is formed of a single silicone rubber, the thermal conductivity of the belt elastic layer 3b is lowered. If the thermal conductivity of the belt elastic layer 3b is low, the heat generated by the heater 1 is difficult to be transmitted to the paper P via the fixing belt 3, so that when the toner is fixed on the paper P, the heating becomes insufficient and fixing unevenness is caused. Image defects can occur.

Therefore, in order to increase the thermal conductivity of the belt elastic layer 3b, for example, a granular high thermal conductive filler having high thermal conductivity is mixed and dispersed in the belt elastic layer 3b. As the granular high thermal conductive filler, silicon carbide (SiC), zinc oxide (ZnO), alumina (Al ₂ O ₃ ), aluminum nitride (AlN), magnesium oxide (MgO), carbon, or the like is used.

  Moreover, you may use a needle-like high heat conductive filler instead of a granular high heat conductive filler according to the objective. That is, the shape of the high thermal conductive filler includes a pulverized shape, a plate shape, a whisker shape, etc. in addition to the granular shape and the needle shape, and any of these shapes may be used for the belt elastic layer 3b. Moreover, these things may be used independently and 2 or more types may be mixed and used. The belt elastic layer 3b can be provided with conductivity by mixing the high thermal conductive filler into the belt elastic layer 3b.

  The surface layer 3c is a fluororesin layer that covers the outer periphery of the belt elastic layer 3b. The surface layer 3 c is provided to make it difficult for toner to adhere to the fixing belt 3. The surface layer 3c includes fluorine such as tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin (PFA), tetrafluoroethylene resin (PTFE), and tetrafluoroethylene / hexafluoropropylene copolymer resin (FEP). A resin may be used.

  The thickness of the surface layer 3c is 1 to 50 μm, preferably 8 to 25 μm. The surface layer 3c may be formed on the outer periphery of the belt elastic layer 3b by coating with a fluororesin tube or applying a paint made of fluororesin.

[Pressure roller]
The pressure roller 4 will be described. FIG. 3A is a perspective view of the elastic pressure roller 4 which is a nip portion forming member. The pressure roller 4 has a multilayer structure having an elastic layer 4b formed concentrically with the base 4a on the outer periphery of the base 4a and a release layer 4c coated on the outer periphery of the elastic layer 4b. Is formed. As shown in FIG. 3A, in the following, the circumferential direction (paper transport direction) of the pressure roller 4 is the “x” direction, and the longitudinal direction (axial direction) of the pressure roller 4 is the “y” direction. The thickness direction (layer thickness direction) of the constituent layers of the pressure roller 4 is represented as the “z” direction.

<Substrate>
The base 4a is a shaft core or a metal core formed using stainless steel, phosphor bronze, aluminum, or the like including a steel material such as a SUM material (sulfur and sulfur composite free-cutting steel) plated with nickel or chromium. . The outer diameter of the base 4a may be 4 mm to 80 mm.

  Reference numerals 4a-1 and 4a-2 denote small-diameter shafts disposed concentrically with the base body 4a on one end side and the other end side in the longitudinal direction of the base body 4a. The small-diameter shaft portions 4a-1 and 4a-2 on the one end side and the other end side are portions that are rotatably supported by a fixed portion (not shown) such as a frame of the fixing device 10 via a bearing member such as a bearing. . Reference numeral 4a-3 denotes an outer surface of the base body 4a.

<Elastic layer>
The elastic layer 4b is a silicone rubber layer that covers the outer periphery of the base 4a. As the elastic layer 4b, liquid silicone rubber is preferably used in the same manner as the belt elastic layer 3b of the fixing belt 3. FIG. 3B is an enlarged perspective schematic view of the sample S cut out from the elastic layer 4 b of the pressure roller 4. As shown in this schematic diagram, the elastic layer 4b has acicular (elongated fiber-shaped) high thermal conductive fillers 4b2 (hereinafter simply referred to as acicular fillers 4b2) in an axial direction (y direction) and a circumferential direction (x Mixed and dispersed in a state oriented in the direction).

  The acicular filler 4b2 will be described. As the needle-like filler 4b2, pitch-based carbon fibers having a thermal conductivity in the filler longitudinal direction of 500 W / (m · K) or more are used. Pitch-based carbon fiber is a carbon fiber manufactured from “pitch”, which is a by-product of petroleum refining or a coal-distillation by-product, and has a feature that it has high thermal conductivity and conductivity, but has almost no thermal expansion. The needle-like filler 4b2 is a member having an elongated rod shape such as a cylinder or a polygonal column, and has a large ratio of length to diameter, that is, a high aspect ratio.

  As described above, the needle filler 4b2 preferably has an aspect ratio of 4.5 to 200 times. The needle-like filler preferably has a thermal conductivity in the longitudinal direction of 500 W / (m · K) or more.

  The needle-like filler 4b2 has thermal conductivity anisotropy (characteristic that the heat conduction in the major axis direction (length direction) of the needle-like filler is higher) that facilitates heat transfer in the oriented direction. FIG. 4 schematically shows the shape of the needle-like thermally conductive filler 4b2. The needle shape refers to a shape having a length in only one direction compared to the other direction, and the shape can be represented mainly by a short axis diameter D and a long axis length L. The minor axis diameter D (average) is not particularly limited, but those of 5 to 15 μm can be used relatively easily. The major axis length L (average) is preferably 0.05 to 5 mm. More preferably, it is 0.1 to 0.5 mm.

  In the present embodiment, the elastic layer 4b is formed so that the thermal conductivity in the plane direction (xy plane) is higher than the thermal conductivity in the thickness direction z. In particular, the thermal conductivity in the longitudinal direction y and the thermal conductivity in the circumferential direction x are increased. More specifically, the thermal conductivity in the longitudinal direction y and the thermal conductivity in the circumferential direction x are 6 to 20 times higher than the thermal conductivity in the thickness direction z.

  The elastic layer 4b is a rubber elastic body having holes, and a large number of holes 4b1 are formed as shown in FIG. That is, the elastic layer 4b has a porous structure in which a large number of pores 4b1 are formed, and a continuous porous structure in which the pores 4b1 are connected to each other is preferable. And it is preferable that the ratio of the void | hole part of the continuous porous structure which occupies for the elastic layer 4b is 40 volume% or more and 60 volume% or less. By forming the hole 4b1, the heat capacity of the elastic layer 4b is reduced. Further, when the hole portion 4b1 is formed, the thermal conductivity in the thickness direction z of the elastic layer 4b is lower than the heat conductivity when the hole portion 4b1 is not formed.

  As a method for forming the hole 4b1, it is desirable to use water that flows together with the base polymer and the needle-like filler and does not interfere with the orientation of the needle-like filler in the pressure roller manufacturing process described later. Water is dehydrated during the manufacturing process, and pores are formed in the elastic layer after dehydration. Water alone does not disperse with the base polymer and is used in a swollen state of a water-absorbing polymer or clay mineral that does not affect the properties of the elastic layer after dehydration, that is, in the form of a “hydrated gel”.

  Emulsified elastic layer-forming liquid rubber composition (water-containing liquid rubber composition) by adding an emulsifier and viscosity modifier to the hydrogel, base polymer, needle filler, etc. To prepare. Here, the proportion of water in the liquid rubber composition is preferably 40% by volume or more and 60% by volume or less.

  By injecting this into a casting mold and curing it at a temperature at which water does not evaporate, an elastic body in which water in the liquid rubber composition is uniformly and finely dispersed can be formed. Thereafter, by evaporating (dehydrating) water from the elastic body, it is possible to form an elastic layer in which fine pores (a continuous porous structure in which pore portions are connected to each other) are uniformly formed.

  Examples of the water-absorbing polymer include acrylic acid and methacrylic acid, polymers of these metal salts, copolymers and cross-linked products thereof. Among them, an alkali metal salt of polyacrylic acid and a cross-linked product thereof can be suitably used, and can be easily obtained industrially (for example, “Rheology 250H” (trade name, manufactured by Toagosei Co., Ltd.)).

  Further, if “water in which clay mineral is swollen” having a thickening effect is used, it is suitable for preparing an emulsion-like liquid composition for forming an elastic layer. Examples of such a clay mineral include “Bengel W-200U” (trade name, manufactured by Hojun Co., Ltd.). Moreover, you may add surfactants, such as nonionic surfactant (Sorbitan fatty-acid ester brand name "Ionette HLB4.3", the Sanyo Chemical Industries Co., Ltd. product), as an additive for emulsification.

  The size of the hole 4b1 in the elastic layer 4b is preferably in the range of 5 to 30 μm from the viewpoint of strength and image quality. Further, the volume occupancy (hereinafter referred to as porosity) of the pores 4b1 in the elastic layer 4b is preferably 40% by volume or more in order to obtain the expected rise time shortening effect. Further, in order to form an elastic layer uniformly containing fine pores 4b1 while maintaining the state in which the water in the liquid rubber composition is uniformly and finely dispersed in the process of forming the elastic layer, 50 volume% or less Is preferred.

  The thickness of the elastic layer 4b is not particularly limited as long as it can form a nip portion N having a desired width in the sheet conveyance direction when the entire elastic layer is elastically deformed by contacting the fixing belt 3. It is preferably 5 to 10.0 mm. The hardness of the elastic layer 4b is preferably in the range of 20 ° or more and 70 ° or less from the viewpoint of securing the nip portion N having a desired width.

<Release layer>
The release layer 4c is a fluororesin layer. The release layer 4c is formed by coating the outer periphery of the elastic layer 4b with, for example, a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA) tube (fluorine resin tube: PFA resin tube).

  Or you may form by apply | coating the coating material which consists of fluororesins, such as PFA, a polytetrafluoroethylene (PTFE), a tetrafluoroethylene-hexafluoropropylene copolymer (FEP), to the outer periphery of the elastic layer 4b.

  The thickness of the release layer 4c is not particularly limited, but is preferably about 15 to 80 μm. The release layer 4 c is provided to make it difficult for toner to adhere to the pressure roller 4.

  A primer layer, an adhesive layer, or the like may be provided between the elastic layer 4b and the release layer 4c for the purpose of adhesion, energization, and the like.

[Method of forming elastic layer]
Next, a method for forming the elastic layer 4b and a method for forming the release layer 4c will be described.

(1) Formation of liquid rubber mixture The needle-like filler 4b2 and a hydrous gel containing water in a water-absorbing polymer are mixed with liquid silicone rubber (uncrosslinked) to contain a liquid rubber mixture (containing liquid silicone rubber and water). Emulsion composition). In order to produce this liquid rubber mixture, a predetermined amount of each of the liquid silicone rubber, the needle-like filler 4b2, and the water-containing material is weighed and stirred using a known filler mixing and stirring means such as a planetary universal mixing stirrer. do it.

(2) Formation of Elastic Layer 4b Using Liquid Rubber Mixture (2-1) Mold A method for forming the elastic layer 4b will be described taking casting as an example. FIG. 5 is a longitudinal sectional view of a hollow mold 5, an inner piece mold 6 and an outer piece mold 12 on one end side thereof, and an inner piece mold 7 and an outer piece mold 13 on the other end side, which constitute the mold 11. It is. This mold 11 is a mold capable of holding the base 4a of the pressure roller 4 as a fixing member inside (molding space).

  The mold 11 includes a hollow mold (hollow cylindrical mold, pipe-shaped cylinder) 5 having a columnar molding space (hereinafter referred to as a cavity) 53, and one end side opening 51 of the hollow mold 5. One end-side inner piece type 6 and the other end-side inner piece type 7 are mounted on the other end side opening 52, respectively.

  The one-end-side inner piece mold 6 is a piece mold for injecting liquid rubber into the cavity 53 of the hollow mold 5. The other end side inner piece type 7 is a piece type for discharging the air pushed out from the cavity 53 as the liquid rubber is injected into the cavity 53.

  6A is an inner surface view (end view on the cavity side) of the inner piece mold 6 on one end side, and FIG. 6B is an outer view (end view on the side opposite to the cavity side). With reference to FIG. 5 and FIG. 6, a central hole 6 c serving as a base body holding portion into which the small-diameter shaft portion 4 a-1 on one end side of the base body 4 a is inserted is provided in the central portion on the inner surface side of the inner piece mold 6 on one end side. Yes. Further, a circumferential hole (sinus, recess) 6a is provided on the outer surface side. A plurality of liquid rubber mixture injection holes 6b extending from the outer surface side to the inner surface side are formed in the circumferential hole 6a along the circumference.

  Referring to FIG. 5, as a base body holding portion into which the small-diameter shaft portion 4 a-2 on the other end side of the base body 4 a is inserted into the inner surface central portion (end surface center portion on the cavity side) of the other end inner piece mold 7. The central hole 7c is provided. A plurality of exhaust holes 7b extending from the inner surface side to the outer surface side are formed.

  The one end-side inner piece mold 6 is fitted into the one end-side opening 51 of the hollow mold 5 with the inner surface first, and the inner circumferential edge 6d abuts against the annular step 51a on the inner peripheral surface of the opening. It is mounted on one end side of the hollow mold 5 by sufficiently inserting it until it is received.

  Further, the other end-side inner piece mold 7 is fitted into the other end-side opening 52 of the hollow mold 5 with the inner surface first, and the inner peripheral edge 7d is an annular stepped portion 52a on the inner peripheral surface of the opening. The hollow mold 5 is mounted on the other end side by being sufficiently inserted until it hits and is received.

(2-2) Placement of Base on Mold A base 4a was preliminarily coated with a primer for silicone rubber on a portion where the rubber elastic layer 4b was formed and baked in a hot air circulation oven. As shown in FIG. 7A, the one-end-side inner piece mold 6 is attached to the one-end-side opening 51 of the hollow mold 5. Next, as shown in (b), the base body 4a is inserted from the other end side opening 52 of the hollow mold 5 with the small diameter shaft portion 4a-1 on the one end side first, and the one end piece type is formed. The small-diameter shaft portion 4a-1 is inserted into and supported by the central hole 6c on the inner surface side.

  Next, as shown in (c), the other-end-side inner piece mold 7 is inserted into the other-end-side opening 52 of the hollow mold 5, and the small-diameter shaft portion on the other end side of the base 4a is inserted into the central hole 7c on the inner surface side. 4a-2 is inserted and supported in a mounted state.

  As a result, the base 4a is supported at the central holes 6c and 7c of the one end side inner piece type 6 and the other end side inner piece type 7 by the small diameter shaft portions 4a-1 and 4a-2 on one end side and the other end side, respectively. The position is determined concentrically and held in the center of the column of the columnar cavity 53 of the mold 5. A rubber elastic layer 4b having a predetermined thickness is provided between the cylindrical molding surface (inner peripheral surface) 53a of the cylindrical cavity 53 and the outer surface (outer peripheral surface) 4a-3 of the base body 4a on the outer periphery of the base body 4a. A gap 8 for casting is formed.

  In addition, installation of the base 4a with respect to the cavity 53 of the mold 11 is not limited to the above procedure. The hollow mold 5, the base 4a, the one end side piece 6 and the other end piece 7 may be finally assembled as shown in FIG.

(2-3) Casting of liquid rubber mixture As shown in FIG. 8, the mold 11 having the base body 4a installed in the cavity 53 as shown in FIG. The piece mold 7 is set to the upper side, and it is pressed and held in a vertical posture between the opposed lower outer piece mold 12 and upper outer piece mold 13 and held. One end side inner piece type (hereinafter referred to as a lower inner piece type) 6 side of the mold 11 is fitted into the receiving hole 12a of the lower outer piece 12 and is received. The other end piece type (hereinafter referred to as the upper inner piece type) 7 side of the mold 11 is fitted into the receiving hole 13a of the upper outer piece 13 and is received.

  Here, in this embodiment, the one end side inner piece mold 6 and the lower outer piece mold 12 are mold terminal members on one end side of the mold 11, and the other end piece piece 7 and the upper outer piece mold 13 are This is a mold terminal member on the other end side of the mold 11.

  That is, the mold 11 has a lower outer piece 12 and an upper outer piece in a posture in which the columnar axis of the columnar cavity 53 is oriented vertically and the side on which the injection hole 6b is disposed is on the lower side. 13, the casting process is performed.

  A liquid rubber injection port 12b is formed at the center of the receiving hole 12a of the lower outer piece 12. A liquid rubber mixture supply pipe 14a of an external liquid rubber mixture supply device 14 is connected to the liquid rubber inlet 12b. An exhaust port 13b is formed at the center of the receiving hole 13a of the upper outer piece 13.

  When the liquid rubber mixture supply device 14 is driven, the liquid rubber mixture of the above item (1) enters the receiving hole 12a from the inlet 12b of the lower outer piece 12 through the supply pipe 14a, and receives the receiving hole 12a and the lower side. The space portion formed by the outer surface side circumferential hole 6a of the inner piece mold 6 is filled.

  Along with the supply of the liquid rubber mixture, the filled liquid rubber mixture passes through the injection holes 6b formed along the circumference of the circumferential hole 6a and passes through the injection holes 6b from the outer surface side to the inner surface side. Flowing into. And it inject | pours with respect to the clearance gap 8 formed between the cylindrical molding surface 53a of the cavity 53, and the outer surface 4a-3 of the base | substrate 4a.

  As the liquid rubber mixture is further supplied, the liquid rubber mixture is injected into the gap 8 from the bottom to the top. The air present in the gap 8 is pushed up from the bottom to the top as the liquid rubber composition is injected into the gap 8 from the bottom to the top. And it goes out of the mold 11 through the exhaust port 13b of the upper outer piece 13.

  The liquid rubber mixture is injected into each of the gaps 8 from each of the injection holes 6 b of the lower inner piece mold 6 on the average in the circumferential direction of the gap 8. In addition, the base body 4a is concentrically fixed to the central part of the cylinder of the cavity 53 by the upper and lower inner frame molds 6 and 7, and the base body 4a does not move when the liquid rubber mixture is injected, and the uneven thickness is reduced. The gap 8 can be filled with the liquid rubber composition without excess or deficiency.

  As described above, the liquid rubber mixture is poured (cast) into the mold so as to be along the axial direction of the substrate 4a disposed in the mold 11. When the liquid rubber mixture is poured into the mold along the axial direction of the substrate 4a, most of the needle fillers 4b2 follow the flow of the liquid rubber mixture in the axial direction of the substrate 4a, that is, the longitudinal direction of the pressure roller 4 (y Orientation).

  Therefore, the thermal conductivity in the longitudinal direction of the elastic layer 4b is higher than the thermal conductivity in other directions. As a result, when the temperature of the non-sheet passing portion (recording material non-passing portion) starts to increase during operation of the fixing device 10, the paper passing portion (recording material passing portion) having a relatively low temperature from the non-sheet passing portion. In addition, the heat of the non-sheet passing portion is easily transmitted to both end portions of the pressure roller. That is, the heat of the non-sheet passing portion can be efficiently diffused.

  Even if the liquid rubber mixture is poured into the mold along the axial direction of the substrate 4a, the flow of the liquid rubber mixture may be disturbed in the mold. In that case, the liquid rubber mixture also flows in the paper conveyance direction, that is, in the circumferential direction (x direction) and in the direction intersecting the circumferential direction (which may include the y direction).

  For this reason, in the elastic layer 4b, the needle-like filler 4b2 is mainly oriented in the longitudinal direction, but is not limited thereto, and there are also those that are oriented in a plane direction (xy plane) including the longitudinal direction and the circumferential direction. In this case, not only the thermal conductivity in the longitudinal direction y but also the thermal conductivity in the circumferential direction x is increased, but even if the thermal conductivity in the circumferential direction x is increased, the non-sheet passing portion temperature rise (the recording material non-passing portion rises). There is no problem because it is effective in suppressing (temperature). That is, in the elastic layer 4b, the direction of the needle-like filler 4b2 is effective in suppressing the temperature rise of the non-sheet passing portion as long as the direction is the plane direction (xy plane).

  The liquid rubber mixture is injected into the mold 11 at least until the gap 8 is sufficiently filled with the liquid rubber mixture. The exhaust hole 7b of the upper inner piece mold 7 does not need to be sufficiently filled with the liquid rubber mixture.

(2-4) Crosslinking and curing of silicone rubber component After casting of the liquid rubber mixture (after completion of the casting process), the casting liquid rubber in the mold 11 is the outer opening of the lower piece mold 6 and the upper piece mold 7. The outer openings (12a, 13a) of the lower inner piece mold 6 and the upper inner piece mold 7 are sealed by attaching a blind plate, a set screw, or the like so as not to flow out of the inside. Then, the mold 11 is heated in a sealed state.

  The heating of the mold 11 at this time is performed as follows as a heating procedure peculiar to the present invention. First, the mold terminal members 6 and 12 on one end side of the mold 11 and the mold terminal members 7 and 13 on the other end side are heated at a predetermined temperature below the boiling point of water for a predetermined time. And while the heating continues, the mold part 5 between the mold terminal members on one end side and the other end side is heated at a predetermined temperature below the boiling point of water for a predetermined time.

  That is, the outer surfaces of the upper and lower outer piece molds 12 and 13 in the mold terminal members on the one end side and the other end side are heated prior to the outer surface of the hollow mold 5, and the inside of the vicinity of the piece mold, that is, the shaft (longitudinal) of the roller. Curing of the liquid rubber at the direction end is promoted more than at the center.

  More specifically, as shown in FIG. 1, it is arranged so as to sandwich the outer surface of the mold 11, and is set in advance at a predetermined heating temperature, divided into two in the circumferential direction and three in the longitudinal direction. A heated metal plate 15 is prepared. And among the three divisions in the longitudinal direction of the heated metal plate 15, the upper and lower portions 15a surrounding the outer frame molds 12 and 13 at both upper and lower ends are closed first and brought into contact with the outer surfaces of the upper and lower outer frame molds 12 and 13. Prior to the central portion 5 of the mold 11, the upper and lower end piece portions 12 and 13 are heated.

  In addition, the upper outer piece 13 is moved from the top to a hydraulic cylinder or the like so that the rubber does not leak from the fitting portions of the upper and lower pieces 12 and 13 and the central die 5 due to the expansion pressure of the liquid rubber inside the die due to heating. The pressing device 16 is pressed in advance with a sufficient pressing force.

  The set temperature of the heated metal plate 15 is set to a temperature not higher than the boiling point of water, for example, 70 to 90 ° C. The upper and lower end piece parts 12 and 13 are heated for a certain period of time, and the liquid rubber is semi-cured, and then the central part 15b of the heated metal plate 15 is closed to heat the outer surface of the hollow mold 5.

  The preceding heating time of the upper and lower end piece parts 12 and 13 varies depending on the set temperature, and is preferably 30 to 60 minutes at 70 ° C and 2 to 5 minutes at 90 ° C. The total heating time including the outer surface of the central mold 5 (central part of the heating panel) is preferably 100 minutes for 70 ° C. and 10 minutes for 90 ° C. As described above, when the liquid rubber mixture is heat-treated under hermetic conditions, the silicone rubber component is crosslinked and cured while retaining moisture in the water-containing material.

(2-5) Formation of Hole Part After the cross-linking and curing treatment, the lower piece molds 6 and 12 and the upper piece molds 7 and 13 are removed from both ends of the mold 5 so that both ends of the mold 5 are opened. . In this state, the mold 5 is further heated to a predetermined high temperature to heat the internal elastic molding roller.

  The lower inner piece mold 6 and the upper inner piece mold 7 are removed from the hollow mold 5 by pulling out from the one end side opening 51 and the other end side opening 52 of the hollow mold 5, respectively. This removal is performed at the end portion of the cured rubber layer of the elastic roller in the hollow mold 5 and the meeting portion (joining portion) of the cured rubber layer in the holes 6b and 7b on the lower inner piece mold 6 and the upper inner piece mold 7 side. Made against the bond strength.

  Since the moisture contained in the water-containing material evaporates as the temperature in the elastic layer 4b rises due to the heating described above, the hole 4b1 is formed at that location. As a condition for heating the elastic roller 4 at this time, the heating temperature is set to 150 to 180 ° C. For heating, the central portion 15b of the heating metal plate 15 may be used, or a hot air circulation oven may be used. Although the heating time depends on the heating method and the heating temperature, it is preferably 50 to 100 minutes in the case of a heated metal disk and 100 to 200 minutes in the case of a hot air circulating oven. As described above, the elastic layer 4b having the hole 4b1 and the needle-like filler 4b2 is formed on the outer periphery of the base 4a.

(2-6) Demolding of the porous elastic roller After the heated mold 5 is cooled by a water cooling method or an air cooling method, the porous elastic roller 4 formed from the mold 5 is demolded. And the shaping process which removes the burr | flash and irregular part which remain | survived in the one end side end surface and the other end side end surface of the elastic layer 4b about the porous elastic roller 4 removed from the hollow metal mold | die 5 as needed. The porous elastic roller 4 was left in a hot air circulation oven at 200 ° C. for 4 hours to secondarily cure the elastic layer 4b.

(2-7) Formation of Release Layer The release layer 4c is formed by covering the elastic layer 4b with a fluororesin tube. In order to coat the fluororesin tube, an adhesive is generally used. However, in some cases, the elastic layer 4b and the fluororesin tube can be bonded to each other without using an adhesive. In such a case, the adhesive need not be used. The release layer 4c may be formed by applying a coating made of a fluororesin on the outer periphery of the elastic layer 4b.

  Alternatively, the release layer 4c may be formed together with the elastic layer 4b. That is, as shown in FIG. 5, the fluororesin tube 4 c is arranged (mounted) in advance on the inner surface (formation surface) of the mold 5. Then, the base body 4a is arranged in the mold 5 as shown in FIG. Then, a liquid rubber mixture is poured between the base 4a and the fluororesin tube 4c as shown in FIG. 8, thereby forming the elastic layer 4b in a state where the release layer 4c is formed. In addition, the fluororesin tube 4c arrange | positioned in a metal mold | die uses the thing by which the inner surface was etched and the primer was apply | coated and dried beforehand.

  In the above, before injecting the liquid rubber composition between the inner surface of the fluororesin tube 4c and the outer surface of the substrate 4a, by vacuum suction between the inner surface 53a of the mold and the outer surface of the fluororesin tube 4c, It is preferable that the fluororesin tube 4c is in close contact with the inner surface of the mold. In the mold 5, reference numeral 55 denotes a suction hole provided for the above-described vacuum suction.

  Here, the lower piece molds 6 and 12 and the upper piece molds 7 and 13 are preliminarily coated with a release agent on their wetted surfaces and removed from the cured rubber remaining on the piece mold side after demolding. And reuse. If a release agent is applied, it is easy to remove the cured rubber remaining on the piece-shaped side. By applying a release agent to the molding surface 53a of the hollow mold 5 in advance, it is easy to remove the mold after the rubber is cured.

  Further, in the casting step, the mold 11 may be in a lateral orientation or an upside down orientation. However, since there is a possibility that air may be taken in at the time of injecting the liquid composition in the horizontal orientation or the upside-down orientation, the configuration in which the injection side is arranged on the lower side is preferable.

[Evaluation of pressure roller]
Hereinafter, evaluation of the pressure roller 4 formed by the above-described method for manufacturing the tube-covered elastic roller will be described with reference to Examples 1 to 2 and Comparative Examples 1 to 3 described later.

  The comparative evaluation was performed using the film heating type fixing device 10 shown in FIG. 2 in which the pressure rollers according to the present example and the comparative example were respectively incorporated.

  Rotation drive so that the moving speed (circumferential speed) of the pressure roller surface is 246 mm / sec with the applied pressure at about 156.8 N at one end and the total applied pressure at about 313.6 N (32 kgf). I let you. When the surface temperature of the fixing film was adjusted to 170 ° C., the offset force that the fixing film received from the pressure roller was measured while rotating while following the roller. More specifically, a load cell was installed on a flange, which is a member for regulating both ends of the film, and the force received from the fixing film at the end of the fixing film in the lateral direction was measured as the lateral force.

  The durability (lifetime) of the fixing film is determined when the film end face breaks in less than 300 hours due to the friction with the flange caused by the offset force in the state of being driven and rotated by the pressure roller as described above. X. And the case where it continued to drive for 300 hours, without destroying from a film end surface was set as (circle).

  Hereinafter, an example of manufacturing a pressure roller according to the present invention will be described.

  The pressure roller of Examples 1 and 2 and the pressure roller of Comparative Examples 1 to 3 are all in common, and the iron core for A3 size (elastic layer 4b forming area length 327 mm) as the base 4a is 24.5 mm in outer diameter. Gold was used. “DY39-051” (trade name, manufactured by Toray Dow Corning Co., Ltd.) was used as a primer to be applied to the peripheral surface of the cored bar. The primer was applied to the core metal peripheral surface, and then baked at 180 ° C. for 30 minutes in a hot air circulating oven.

The liquid silicone rubber mixture for the elastic layer 4b formed on the peripheral surface of the core metal is
1) Addition reaction-crosslinking liquid silicone rubber “DY35-2083” (trade name, Toray Dow Corning) preliminarily blended with polyether-modified silicone (trade name: FZ-2233, manufactured by Toray Dow Corning Co., Ltd.) as an emulsifier. 100 parts by mass) 2) A mixture of hydrogels at a rate of 100 parts by mass was used.

  The hydrogel contains sodium polyacrylate as a main component, and a thickener (trade name “Bengel W-200U”, manufactured by Hojun Co., Ltd.) containing a smectite clay mineral is 1% by weight. Add 99% by weight of ion exchange water. This was prepared by sufficiently stirring and swelling.

  Furthermore, pitch-type carbon fiber “XN-100-25M” having an average fiber diameter of 9 μm, an average fiber length of 250 μm, and a thermal conductivity of 900 W / (m · K) as the needle-like filler 4b2 (trade name, GRANOC milled fiber, Nippon Graphite Fiber) Manufactured by KK). This was blended with a liquid silicone rubber and hydrogel mixture at a volume ratio of 10%.

  Using the planetary universal mixing stirrer (Hibismix 2P-1 type, manufactured by Primix Co., Ltd.), the above liquid silicone rubber, water-containing gel, and needle filler are mixed and stirred at 80 rpm for 60 minutes, and water Is emulsified and dispersed in liquid silicone rubber. This obtained the liquid silicone rubber mixture for elastic layer 4b formation.

  The release layer 4 c is a fluororesin (PFA) tube with an inner diameter of φ29.5, and both ends of the fluororesin tube inserted in advance into the hollow mold 5 with an inner diameter of φ30.2 are attached to the outer wall surface of the hollow mold 5. By folding, it was installed on the inner wall surface of the cylindrical mold.

  Primer “DY39-067” (trade name, manufactured by Toray Dow Corning Co., Ltd.) was applied to the inner surface of the fluororesin tube attached to the inner wall of the cylindrical mold and dried in a hot air circulation oven at 70 ° C. for 20 minutes. . The core after the primer treatment is placed concentrically in the hollow mold 5, and the pieces 6, 12, 7, and 13 are fitted into the upper and lower ends, respectively, and the outer piece 13 is pressed by the toggle clamp. Thus, the cored bar was concentrically fixed and arranged in the hollow cylindrical mold.

  After the liquid rubber was injected between the fluororesin tube disposed on the inner wall of the mold and the core metal, the piece molds at both ends of the mold were sealed. Then, the upper outer piece mold 13 is pressed from above by the pressing device 16 so that the rubber does not leak from the fitting portions of the upper and lower piece molds 12 and 13 and the central mold 5 due to the expansion pressure of the liquid rubber inside the mold in the subsequent curing step. I pressed it down in advance.

  In the subsequent curing process of the liquid silicone rubber mixture by heating the outer wall of the mold, a total of five types of pressure rollers of Examples 1 to 2 and Comparative Examples 1 to 3 were prepared based on the difference in heating method.

(Pressure roller of Example 1)
First, the heating metal board 15a temperature-controlled at 90 degreeC was made to contact the outer wall of the upper-and-lower-end piece parts 12 and 13, and it heated for 3 minutes. Subsequently, the heating of the outer wall of the hollow mold 5 was similarly started by bringing the heating metal disk 15b at 90 ° C. into contact therewith. At this time, the upper and lower end piece portions 12 and 13 are still heated.

  When the total heating time is 10 minutes (ie, the heating time of the hollow mold 5 is 7 minutes) from the start of heating the upper and lower end piece parts 12 and 13, the heated metal plates 15a and 15b are separated from the outer wall of the mold. The heating was finished.

  Through the above heating process, the liquid rubber mixture was cured, and the cored bar, rubber and tube were bonded and integrated (primary curing). After the mold is air-cooled, the pieces 6, 12, 7, 13 at both ends are removed from the mold, and the mold is left open in a hot air circulation oven at 180 ° C. for 100 minutes with both mold ends open. Then, the pores 4b1 were formed by evaporating the water in the elastic layer 4b. After the mold was cooled, the tube covering roller was removed from the mold, and the roller was left in a hot air circulation oven at 200 ° C. for 4 hours to secondary cure the elastic layer 4b. The pressure roller of Example 1 was obtained through the above steps.

(Pressure roller of Example 2)
The set temperature of the heated metal disk 15 was set to 70 ° C., and the liquid rubber mixture inside the mold was cured in the same process as in Example 1. First, the heating metal disc 15a was brought into contact with the outer walls of the upper and lower end pieces 12 and 13 and heated for 40 minutes. Subsequently, the heating of the outer wall of the hollow mold 5 was similarly started by bringing the heating metal plate 15b at 70 ° C. into contact therewith.

  When the total heating time reaches 100 minutes (ie, the heating time of the hollow mold 5 is 60 minutes) from the start of heating of the upper and lower end piece parts 12 and 13, the heated metal plates 15a and 15b are separated from the outer wall of the mold. The heating was finished. After the above heating process, the same process as in Example 1 was performed to obtain a pressure roller of Example 2.

(Pressure roller of Comparative Example 1)
Heating was started by setting the set temperature of the heated metal plate 15 to 90 ° C. and simultaneously bringing the heated metal plates 15 a and 15 b into contact with the upper and lower end piece parts 12 and 13 and the outer wall of the hollow mold 5 at the same time. After 10 minutes from the start of heating, the heated metal plates 15a and 15b were separated from the outer wall of the mold and the heating was completed. After the above heating process, the pressure roller of Comparative Example 1 was obtained through the same process as in Example 1.

(Pressure roller of Comparative Example 2)
Heating was started by setting the set temperature of the heated metal plate 15 to 70 ° C. and simultaneously bringing the heated metal plates 15 a and 15 b into contact with the upper and lower end piece parts 12 and 13 and the outer wall of the hollow mold 5 simultaneously. After 100 minutes had elapsed since the start of heating, the heated metal plates 15a and 15b were separated from the outer wall of the mold and heating was completed. After the above heating process, the same process as in Example 1 was performed to obtain a pressure roller of Comparative Example 2.

(Pressure roller of Comparative Example 3)
After the liquid silicone rubber mixture was poured, the mold that was sealed and pressed was put into a hot-air circulating oven set at 90 ° C., and heating was started. After 60 minutes from the start of heating, the mold was taken out of the hot air circulation oven and heating was terminated. After the above heating process, the same process as in Example 1 was performed to obtain a pressure roller of Comparative Example 3.

  Table 1 shows the results obtained by confirming the above-mentioned offset force and durability in the pressure rollers of the respective examples and comparative examples.

  Compared with Comparative Examples 1 to 3, it can be seen that the pressure rollers of Examples 1 and 2 have a smaller shifting force. In addition, when the pressure rollers of Comparative Examples 1 to 3 were used, the driven rotation fixing film did not have 300 hours and was broken from the end face. On the other hand, when the pressure rollers of Examples 1 and 2 were used, the fixing film could continue to rotate for 300 hours without breaking from the end face.

  The above results can be explained by thinking as follows. As in the comparative example, when the sandwiching piece mold at both ends and the hollow cylindrical mold are simultaneously heated from the outer surface, the liquid rubber inside is longer than the length of the hollow mold due to the influence of the both end piece mold having a large heat capacity with respect to the outer surface area. Curing begins when the temperature rises from near the center. The fitting part between the hollow mold both ends and the piece mold sandwiching the hollow mold is slow to cure, so it easily flows in a state where the liquid viscosity of the liquid rubber is low, and receives expansion pressure from the longitudinal center part where thermal expansion is large. Thus, the liquid rubber slightly flows out from the gap between the fitting portions at either end.

  This outflow of the liquid rubber leaves a flow history in the liquid rubber inside the mold, and thus the emulsified and dispersed state of the water after the rubber is cured, and consequently the shape of the pores formed after the water is evaporated is different. Give direction. When anisotropy occurs in the shape of the hole portion of the pressure roller elastic layer, when the fixing film is pressed against the pressure roller and rotated in the fixing device, the pressure direction (rubber layer thickness direction) The force is also distributed in the rotation axis direction (longitudinal direction). As a result, the fixing film that is driven as a shifting force is moved toward one side in the rotational axis direction.

  On the other hand, when the outer surface of the clamping piece type at both ends is heated before the outer surface of the hollow mold as in the embodiment, the internal liquid rubber is heated from the vicinity of the both ends piece shape and is cured. Therefore, even if it receives the expansion pressure from the longitudinal central part accompanying the subsequent hardening of the hollow mold, the fitting part between the hollow mold both ends and the piece mold sandwiching it is in a state where the liquid viscosity is high or the rubber is It is in a semi-cured state. Therefore, the outflow from the liquid rubber insertion portion is suppressed, and the flow history of the liquid rubber inside the mold is reduced.

  As a result, the emulsified and dispersed state of the water after the rubber is cured, and consequently the pores after the water is evaporated, isotropically formed, so that the fixing film is pressed against the pressure roller in the fixing device. Force (shifting force) in the direction of the rotation axis (longitudinal direction) is less likely to occur.

《Other matters》
(1) Although the pressure roller has been described as an example in the above-described embodiments, the present invention is not limited to this. For example, the present invention can be applied to a fixing roller having a fluororesin tube as a release layer. Alternatively, the present invention can also be applied to a pressure belt or a fixing belt provided with a substrate made of polyimide, polyamideimide, polyetheretherketone, or the like, or a substrate made of a thin metal such as stainless steel or nickel, and a fluororesin tube as a release layer.

  (2) The image fixing device 10 may be a device (also referred to as a fixing device in this case) that heats and presses a toner image once fixed or assumed on the recording material in order to improve the gloss of the image.

  (3) The image forming unit of the image forming apparatus is not limited to the electrophotographic system. The image forming unit may be an electrostatic recording system or a magnetic recording system. Further, the transfer method is not limited, and an unfixed image may be formed on the recording material P by a direct method.

  10..Image fixing device, 4..Fusing member (pressure roller), 4a..Base, 4b..Elastic layer, 4b1..Hole, 11..Mould, 53..Inside of mold (Molding space), 6, 12... Mold end member on one end side, 7, 13... Mold end member on one end side, 51, 52.

Claims (15)

Using a mold capable of holding a base of a fixing member used in an image fixing apparatus inside, a liquid rubber composition containing water is injected into the mold holding the base, and the mold is After the rubber composition is heated and cured by heating, the mold terminal members attached to one end side and the other end side of the mold are removed, and the mold is opened with both ends of the mold open. Elasticity comprising a rubber elastic body having pores produced by evaporating water from the rubber composition by heating the rubber composition to form pores in the heat-cured rubber composition In a method for producing a fixing member having a layer and a substrate,
When the rubber composition is heated and cured by heating the mold, the mold on one end side and the other end side is ahead of the mold portion between the mold terminal members on one end side and the other end side of the mold. A method for manufacturing a fixing member, comprising heating a mold terminal member.   After heating the mold terminal members on the one end side and the other end side at a predetermined temperature equal to or lower than the boiling point of water for a predetermined time, the heating is continued while the mold terminal member between the one end side and the mold end member on the other end side is kept. The method for manufacturing a fixing member according to claim 1, wherein the mold part is heated for a predetermined time at a predetermined temperature equal to or lower than the boiling point of water.   3. The method for manufacturing a fixing member according to claim 1, wherein the water-containing liquid rubber composition is an emulsion composition containing a liquid silicone rubber and water.   The method for manufacturing a fixing member according to any one of claims 1 to 3, wherein a ratio of water in the liquid rubber composition is 40% by volume or more and 60% by volume or less.   The method for producing a fixing member according to claim 1, wherein the liquid rubber composition contains a needle-like filler.   The method for manufacturing a fixing member according to claim 5, wherein an aspect ratio of the needle-like filler is 4.5 to 200 times.   The method for manufacturing a fixing member according to claim 5, wherein the needle-like filler has a thermal conductivity in the longitudinal direction of 500 W / (m · K) or more.   The method for manufacturing a fixing member according to claim 5, wherein the needle-like filler is pitch-based carbon fiber.   The method for manufacturing a fixing member according to claim 1, wherein the pores have a continuous porous structure in which the pores are connected to each other.   The method for manufacturing a fixing member according to claim 9, wherein a ratio of pores of the continuous porous structure in the elastic layer is 40% by volume or more and 60% by volume or less.   A fluororesin tube is attached to the inner surface of the mold, and the liquid rubber composition is injected between the inner surface of the fluororesin tube and the outer surface of the base, whereby the outer peripheral surface of the elastic layer is The method for manufacturing a fixing member according to any one of claims 1 to 10, further comprising a release layer made of a fluorine-based resin tube.   The method for manufacturing a fixing member according to claim 11, wherein the fluororesin tube is a PFA resin tube.   Before injecting the liquid rubber composition between the inner surface of the fluororesin tube and the outer surface of the base, by vacuum suction between the inner surface of the mold and the outer surface of the fluororesin tube, The method for manufacturing a fixing member according to claim 11, wherein the fluororesin tube is closely attached to an inner surface of the mold.   The method for manufacturing a fixing member according to claim 1, wherein the base is a cylindrical or columnar cored bar.   The method for manufacturing a fixing member according to claim 1, wherein the fixing member is a pressure roller.