JP5948979B2 - Endless metal thin film roll, method for manufacturing endless metal thin film roll, heat fixing belt, fixing unit, and image forming apparatus - Google Patents

Description

  The present invention is an endless metal thin film roll suitable for a fixing device used for electrophotographic copying machines, printers, facsimiles, and the like, for fixing an unfixed toner image, its manufacturing method, fixing belt, fixing device, and The present invention relates to an image forming apparatus, and more particularly to an endless metal thin film roll manufactured by an electroforming method, a manufacturing method thereof, a heat fixing belt, a fixing unit, and an image forming apparatus.

  In image forming apparatuses using electrophotographic technology such as copying machines and printers, cylindrical rollers and belts are used as heat fixing parts, and these are heated by various heating means to fix toner on recording paper. . As a base material for a cylindrical roller or belt, a seamless and cylindrical endless metal thin film roll manufactured by a nickel electroforming method is generally used.

Here, a fixing belt will be described with reference to FIGS. 2 and 3 by taking a QSU (short time start unit) fixing method as an example of a toner fixing method. FIG. 2 is a schematic cross-sectional view of a fixing unit using the QSU toner fixing method. FIG. 3 is an enlarged cross-sectional view of the fixing belt.
As shown in FIG. 2, the fixing unit 26 of the QSU toner fixing system sandwiches a seamless nickel electroformed fixing belt 5, a heating pipe 2 fitted inside the fixing belt 5, and the fixing belt 5. And a pressure roller 6 disposed to face the heating pipe 2. As shown in FIG. 3, a sliding layer 5b is formed on the inner surface of the fixing belt 5, and an elastic layer 5c and a release layer 5d are formed on the outer surface. In the hollow portion of the heating pipe 2, there is a heat generating member 1 such as a halogen heater and a pressure pad 4 fixed by a stay 3 attached in the heating pipe 2. The fixing belt 5 and the pressure roller 6 are in contact with each other at a predetermined pressure by the pressure pad 4, and a transfer paper P to which unfixed toner is adhered is formed between the fixing belt 5 and the pressure roller 6. In the process of passing through the nip portion N, the toner is fixed to the transfer paper by pressurization and heating.
As a method of manufacturing a fixing belt base material by nickel electroforming, a SUS-made cylindrical mother mold with a polished and cleaned surface is immersed in a nickel electroforming bath and energized to deposit nickel on the mother mold surface. Then, it is lifted out of the bath, and the deposited nickel electroformed film is removed from the cylindrical mother mold, and the upper and lower sides are cut to complete the required length.

  For example, Patent Document 1 describes a fixing belt having a metal layer (base material) manufactured by a nickel electroforming method and a release layer formed on the metal layer. In the present invention, the durability of the fixing belt is enhanced by increasing the thickness of both end portions in the longitudinal direction of the metal layer with respect to the central portion.

In order to demold a base material manufactured by the nickel electroforming method from a cylindrical matrix, generally, a thermal expansion difference due to a temperature difference is used.
For example, when the diameter of the fixing belt is relatively large such as exceeding 60 mmφ, it is immersed in cold water after electroforming, and demolding using the difference in thermal expansion between the cylindrical matrix and the nickel electroformed film. Such means can be used. It is clear from the experience of the present inventor that the mold can be removed by the above-described method if the clearance between the cylindrical matrix and the electroformed thin film is approximately 6 μm or more (diameter difference of 12 μm or more) on one side. doing.

  Here, FIG. 14 is a graph showing the relationship between the diameter of the SUS cylindrical matrix and the thermal expansion difference generated between the SUS cylindrical matrix and the nickel electroformed film. This figure shows the thermal expansion difference generated between 50 ° C., which is slightly lower than the bath temperature during nickel electroforming, and 5 ° C., which is cold water. From this figure, if the diameter of the cylindrical matrix is 60 mmφ or more, it is possible to obtain a difference in thermal expansion of 12 μm or more in terms of diameter difference, and it is possible to remove the mold by dipping in cold water after electroforming. Can be seen. It is known from the result that the present inventors actually performed cylindrical electroforming of various diameters that this is correct. In addition, since the bath temperature at the time of nickel electroforming is set to around 55 ° C., a slightly larger thermal expansion difference is actually obtained than this graph.

However, in recent years, copying machines and printers have been rapidly downsized, and parts such as belts and rollers used as parts are required to have a smaller diameter. Specifically, in the above-mentioned QSU toner fixing unit, the diameter of the fixing belt is required to be 30 mmφ or less.
With a small-diameter fixing belt, it is difficult to remove the mold by using only the difference in thermal expansion as described above. Therefore, the internal stress of the electroformed film is reduced to a compressive stress by adjusting the electroforming bath composition and electroforming conditions. A technique is employed in which the electroformed film is demolded by utilizing the effect of expansion due to stress. FIG. 15 is a graph showing the relationship between the electroformed film stress and the clearance between the matrix and the electroformed film. FIG. 15 shows the difference in thermal expansion that occurs between 50 ° C. and 5 ° C. of cold water, as in FIG. When the diameter is 30 mmφ, a compressive stress of about −40 to −50 N / mm ² is required to secure a clearance of 6 μm.

However, if electroforming is performed in a state of large compressive stress, a part of the electroformed film floats up and expands during electroforming, and the diameter becomes uneven in the axial direction, or around the end of the axial direction. There is a problem in that the electroforming film of the film rises and the electroforming liquid penetrates and the appearance is deteriorated.
The present invention has been made in view of the above circumstances, and when producing an endless metal thin film roll by a nickel electroforming method, even if the roll diameter is reduced (φ30 mm or less), swelling or It is an object of the present invention to provide an electroforming and demolding method that does not have a poor penetration of the plating solution and can smoothly demold the electroformed film from the electroforming mother mold.

In order to solve the above-mentioned problems, the present invention provides nickel sulfamate, p-toluenesulfonamide as a primary brightener, 2-butyne-1,4-diol as a secondary brightener, and heat resistance of an electroformed film. A hollow cylindrical endless metal thin film roll manufactured by a nickel electroforming method using a plating bath containing sodium phosphinate or phosphorous acid as an additive for improving the properties. It is characterized by being 0.006 to 0.04% smaller than the inner diameter of the central portion in the direction.

  In the endless metal thin film roll of the present invention, the inner diameter of both end portions in the thrust direction is 0.006 to 0.04% smaller than the inner diameter of the central portion in the thrust direction. Both end portions are brought into close contact with the cylindrical mother die, so that it is possible to prevent the electrocasting liquid from penetrating and poor appearance due to swelling and floating, and it is possible to smoothly remove the mold from the cylindrical mother die.

1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. 2 is a schematic cross-sectional view of a QSU toner fixing unit. FIG. FIG. 3 is an enlarged cross-sectional view of a fixing belt. It is a schematic diagram of a cylindrical mother mold. It is the schematic diagram which showed the nickel electroforming apparatus and the electroforming method. (A)-(c) is the schematic diagram which showed the relationship between a cylindrical mother block and an anode. It is a table | surface which shows an electroforming bath component. It is the graph which showed the relationship between the cathode current density at the time of using the nickel electroforming liquid of the structure shown in FIG. 7, and an electroforming film | membrane stress. It is a table | surface which shows the relationship between each internal stress of the center part and both ends of an electroformed thin film roll, and the possibility of demolding. It is a table | surface which shows the relationship between the internal stress of each center part and both ends of an electroformed thin film roll, and the presence or absence of the penetration | infiltration of an electroforming liquid, swelling, and the appearance defect of a float. It is a table | surface which shows the internal stress range from which the result of FIG. 9 and FIG. 10 was favorable. (A), (b) is the schematic diagram which showed the relationship between a cylindrical mother block and an anode. It is the schematic diagram which showed a mode that the electroformed film was peeled. It is the graph which showed the relationship between the diameter of a SUS cylindrical mother block, and the thermal expansion difference produced between a SUS cylindrical mother block and a nickel electroformed film. It is a graph which shows the relationship between the electroforming film | membrane stress and the clearance between a mother mold | die and an electroforming film | membrane.

The outline of this embodiment is as follows. In the present invention, when producing an endless metal thin film roll to be used as a base material for a belt used for development and fixing by a nickel electroforming method, the electroforming liquid is prevented from penetrating during electroforming, and the roll diameter is reduced. This is a technique for providing an electroforming and demolding method capable of smoothly demolding from an electroformed mother mold even when the diameter is small (φ30 or less). That is,
1. At least one main anode is installed at a position facing the central part of the cylindrical master mold in the thrust direction, and a secondary anode is also installed at a position facing both ends of the cylindrical master mold. A main rectifier for partial electroforming is provided, and a sub rectifier independent of the main rectifier is provided at the sub anode.
2. For both ends of the cylindrical mother die, electroforming is performed at a current density higher than that of the central portion of the cylindrical mother die.

FIG. 8 is a graph showing the relationship between the cathode current density and the electroformed film stress during electroforming using the nickel electroforming liquid having the configuration shown in FIG. The electroformed film stress is a negative compressive stress on the low current density side, but the compressive stress weakens as the current density increases, and on the tensile stress side when it exceeds 10 A / dm ² .
Therefore, electroforming is performed at a constant current density that gives a high compressive stress at the central part of the cylindrical mother die, and at both ends, swelling and floating do not occur during electroforming, and it becomes a stress that can be removed after electroforming. Electroforming is performed independently at a higher current density than the center of the mold. Specifically, electroforming is performed in the range of about 3 to 5 A / dm ² at the center and about 7 to 10 A / dm ² at both ends. As a result, the central portion of the electroformed thin film roll (endless metal thin film roll) expands due to high compressive stress and the inner diameter expands, and both ends expand less than the central portion. Becomes smaller. That is, the electroformed thin film roll has a cylindrical roll shape in which the inner diameter of the central portion of the cylinder is large, both end portions are slightly small, and both ends are slightly contracted.

By doing as described above, under the temperature environment at the time of electroforming, both end portions of the electroformed film are in close contact with the cylindrical matrix, and it is possible to prevent the electrocasting liquid from penetrating and poor appearance due to swelling and floating, After electroforming, the roll can be smoothly removed from the mother die.
It should be noted that the length range in the thrust direction of the portion having a small inner diameter at both ends of the electroformed thin film roll is not applied to the sheet passing portion at the time of fixing.
3. When the thickness of the electroformed film on both ends of the electroformed thin film roll reaches a predetermined thickness, the energization of the sub-rectifier is stopped, and at the same time, shielding plates are installed between the sub-anode and both ends of the cylindrical matrix.
4). When the electroformed thickness at the center of the electroformed thin film roll reaches a predetermined thickness, the energization of the main rectifier is stopped, and the cylindrical matrix on which the electroformed film is formed is taken out from the electroformed tank. By performing the above-described electroforming procedure, the electroformed thin film roll expands outward due to a large compressive stress and becomes larger in inner diameter, and both end portions have a smaller compressive stress than the central portion. Also, the inner diameter of both ends is slightly small, and the both ends are slightly cylindrically compressed. Thereafter, the electroformed thin film roll can be easily released from the cylindrical mother die and removed from the mold by performing the steps of washing, cutting unnecessary portions at both ends of the roll, and immersing in water.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 40 is wound around an image forming unit 20 having a photoconductor 21 as an image carrier for forming an electrostatic latent image, and three rollers (22a, 22b, 22c) located in the center of the image forming apparatus. A belt-like intermediate transfer belt 22 is provided. A secondary transfer roller 23 is provided at a position facing the roller 22a with the intermediate transfer belt 22 interposed therebetween to form a secondary transfer position. Further, below the image forming apparatus, a recording material cassette 24 that stores recording materials such as paper and OHP film is provided. A recording material conveyance path 25 for conveying the recording material is provided between the recording material cassette 24 and the secondary transfer position. The recording material conveyed through the recording material conveyance path 25 is transferred with the toner image from the photosensitive member 21 via the intermediate transfer belt 22 at the secondary transfer position, and is fixed by a fixing unit 26 disposed downstream of the secondary transfer position. The toner is fixed by heat and pressure. Thereafter, the recording material is discharged to an externally attached stack tray 27.

A toner fixing method in the fixing unit 26 will be described with reference to FIGS. FIG. 2 is a schematic cross-sectional view of the QSU toner fixing unit. FIG. 3 is an enlarged cross-sectional view of the fixing belt.
As shown in FIG. 2, the fixing unit 26 of the QSU toner fixing system includes a seamless nickel electroformed fixing belt 5, a heating pipe 2 fitted inside the fixing belt 5, and the fixing belt 5. And a pressure roller 6 disposed to face the heating pipe 2. As shown in FIG. 3, a sliding layer 5b is formed on the inner surface of the fixing belt 5, and an elastic layer 5c and a release layer 5d are formed on the outer surface. In the hollow portion of the heating pipe 2, a heating member 1 such as a halogen heater and a pressure pad 4 fixed by a stay 3 attached in the heating pipe 2 are provided. The fixing belt 5 and the pressure roller 6 are in contact with each other at a predetermined pressure by the pressure pad 4, and a transfer paper P to which unfixed toner is adhered is formed between the fixing belt 5 and the pressure roller 6. In the process of passing through the nip portion N, the toner is fixed to the transfer paper by pressurization and heating.

When the film thickness of the endless metal thin film roll (electroformed film 5a) which is the base material of the fixing belt 5 is less than 10 μm, the strength as the base material is insufficient, and when it exceeds 60 μm, the flexibility as the belt decreases. Therefore, a film thickness of 10-60 μm is appropriate. However, if desired, the thickness is set to 20 to 50 μm.
As shown in FIG. 3, a polyimide or PFA layer having a thickness of 15 μm is formed as the sliding layer 5b on the inner peripheral side of the electroformed film 5a. A foamed silicone rubber layer having a thickness of 100 to 200 μm is formed as an elastic layer 5c on the outer peripheral side of the electroformed film 5a, and a PFA layer having a thickness of 20 to 40 μm is sequentially formed as a release layer 5d on the outer peripheral side thereof. It becomes as.

Next, a method for producing an endless metal thin film roll as a fixing belt substrate will be described.
First, a cylindrical matrix used for electroforming deposition of an endless metal thin film roll will be described. FIG. 4 is a schematic view of a cylindrical matrix.
As the material of the hollow cylindrical mother die 7, the SUS material No. 300 series material is most suitable (see Example 1). In addition, an aluminum cylindrical matrix can be used (see Example 2).
The cylindrical mother die 7 is immersed in the electroforming bath in a state where it is suspended with the thrust direction (axial direction) as the vertical direction. A suspension supporting electrode 8 is formed so as to protrude upward from the upper end of the cylindrical mother die 7. This part is not immersed in the electroforming bath. A predetermined range is insulation-coated in the thrust direction from the upper end of the cylindrical mother die 7 to form an upper insulating portion 9. The electroformed film is not deposited on this portion, and the upper end side of the upper insulating portion 9 is exposed above the liquid surface portion of the electroforming bath during electroforming. It is desirable that the lower end of the upper insulating part 9, that is, the portion corresponding to the upper end of the electroformed film to be electrodeposited, is located at a depth of 20 to 50 mm from the surface of the electroforming bath when immersed in the electroforming bath. .
The part located below the lower end of the upper insulating part 9 of the cylindrical mother die 7 is an electrodeposition part 7a where the electroformed film is deposited.

An upper insulating coat portion 10 and a lower insulating coat portion 11 having a V-shaped recess having a length in the thrust direction of about 10 mm and facing in the circumferential direction are formed at the upper and lower ends of the electrodeposition site 7a. When the electroformed film is formed, strip-shaped peeling start portions 10a and 11a are formed in the circumferential direction adjacent to the reverse wedge-shaped insulating coating portions 10 and 11 (see FIG. 9). After forming the electroformed film, when the mold is removed from the cylindrical mother die 7, the upper and lower portions of the electroformed film are formed in a tape shape along the circumferential direction by the length in the thrust direction of the insulating coat parts 10 and 11 from the peeling start portions 10a and 11a. Is peeled off (see FIG. 9). Then, by immersing in cold water, water infiltrates from the gap between the upper and lower end portions of the electroformed film and the cylindrical mother die 7 and can be removed smoothly. Although not shown, the lower end surface of the cylindrical mother die 7 is coated with an insulating coating so that the electroformed film is not electrodeposited.
The length of the electrodeposition site 7a of the cylindrical mother die 7 is the thrust of the nickel electroformed thin film roll (endless metal thin film roll) when the maximum size of paper to be passed during fixing is set to A4 width (297 mm). Assuming that both ends in the direction are cut, the thickness is set to about 400 mm. The surface of the cylindrical mother die 7 is processed so that the surface roughness Ra becomes 0.1 μm or less so that the nickel electroformed thin film roll can be easily peeled and removed. The cylindrical mother die 7 is degreased and acid washed after the side surface of the mother die is wiped and washed with a nonwoven fabric before electroforming.

Nickel electroforming is performed on the cylindrical mother die 7 having the above-described configuration by using a nickel electroforming apparatus described below. First, the nickel electroforming apparatus will be described. FIG. 5 is a schematic view showing a nickel electroforming apparatus and an electroforming method. 6A to 6C are schematic views showing the relationship between the cylindrical matrix and the anode.
In the nickel electroforming apparatus 12, at least one, preferably 2 to 4 main anodes 13 are installed at positions facing the central part (intermediate part) in the thrust direction of the cylindrical mother die 7. The main anode 13 is installed every 90 ° to 180 ° when the cylindrical mother die 7 is erected vertically (a state in which the thrust direction is vertical) when viewed from directly above (see FIG. 6). Separately from the main anode 13, at least one, preferably 2 to 4 upper sub-anodes 14 and lower sub-anodes 15 are installed at positions facing the upper and lower portions of the cylindrical mother die 7. As can be seen from FIG. 6B, the main anode 13, the upper sub-anode 14, and the lower sub-anode 15 do not necessarily have to be arranged at equal intervals in the circumferential direction.

Connected to the main anode 13 is a main rectifier 16 for electroforming the central portion of the cylindrical mother die 7 in the thrust direction. The upper sub-anode 14 and the lower sub-anode 15 are connected to an upper sub-rectifier 17 and a lower sub-rectifier 18 for electroforming both ends in the thrust direction of the cylindrical mother die 7 independent of the main rectifier 16, respectively. Note that the negative of the main rectifier 16, the upper sub rectifier 17, and the lower sub rectifier 18 are connected to the suspension support electrode 8, respectively. In this way, the amount of current applied to the upper part and the lower part can be independently adjusted with respect to the intermediate part of the cylindrical mother die 7. The upper sub rectifier 17 and the lower sub rectifier 18 may be integrated.
When the length of the cylindrical mother die 7 is about 400 mm, the length corresponding to the thrust direction of the cylindrical mother die 7 of the upper sub-anode 14 and the lower sub-anode 15 is about 20 mm, and the gap between the mother die and the sub-anode The distance is about 30 to 50 mm. By carrying out like this, the range with a small internal diameter of the both ends of an electroformed thin film roll will be about 30 mm in a thrust direction. Therefore, it is possible to prevent the small range of the inner diameter at both ends of the electroformed thin film roll from interfering with the paper passing portion located in the central portion in the thrust direction and to prevent the print quality from being affected, and to float and swell during electroforming. And no electroforming liquid penetration. After electroforming, about 10 mm width portion of the both end portions of about 30 mm is cut off from the peeling start portions 10a and 11a, and then demolding can be performed smoothly by immersing in cold water.

In addition, the length corresponding to the cylindrical mother die 7 thrust direction of the main anode 13 is set to about 340 mm to 360 mm in the case described above. This is because the length (20 mm × 2) of each of the upper sub-anode 14 and the lower sub-anode 15 is subtracted from the length 400 mm of the cylindrical mother die 7, and the main anode 13, the upper sub-anode 14, the lower sub-anode 15, However, it is set including a margin for preventing contact with each other. The distance between the matrix and the main anode is about 50 mm to 70 mm.
The main anode 13, the upper sub-anode 14, and the lower sub-anode 15 are placed in a basket (mesh basket) made of a corrosion-resistant metal material such as titanium, and S round nickel or S pellet nickel with good nickel elution is put into the basket. Cover with an anode bag to prevent sludge (anode slime) generated by elution of the anode from entering the electroforming bath. The electroforming bath is ejected upward by a liquid circulation pump 50 from a liquid ejecting nozzle 51 installed at the lower part of the electroforming apparatus, and a new electroforming bath filtered through the filter 52 is used as a cylindrical matrix. Can be sprayed on. Although not shown, an auxiliary tank 53 is installed in the electroforming apparatus, a dummy electrode (cathode) is placed in the auxiliary tank 53, and a weak current of about 0.1 to 1 A / dm ² is always applied. Removes impurities such as heavy metals in the electroforming bath.

  The nickel electroforming bath used in the nickel electroforming apparatus 12 is basically composed of a nickel salt (nickel sulfate, nickel sulfamate), a pH buffer (boric acid, citric acid), and a nickel halide (anodic dissolution agent). (Nickel chloride, nickel bromide) and other additives. In this example, nickel sulfamate, which is difficult to be subjected to high-speed electroforming as a nickel salt and capable of high speed electroforming, is 500 to 550 g / L, pH, boric acid is 30 to 35 g / L as a buffer, and nickel halide is low stress. The basic bath composition is 1 to 5 g / L of nickel bromide (see FIG. 7). As other additives, an appropriate amount of a pit inhibitor (sodium dodecyl sulfate or a commercially available product) may be used, 0.08 g / L of p-toluenesulfonamide as the primary brightener, and 2-butyne-1 as the secondary brightener. , 4-diol 0.1 g / L, and sodium phosphinate (sodium hypophosphite) or phosphorous acid 0.15 to 0.4 g / L for improving the heat resistance of the electroformed film (See FIG. 7). In this embodiment, phosphorus is not necessarily a necessary additive. The pH of the electroforming bath is adjusted to 3.5 to 4.5, and the bath temperature during electroforming is adjusted to 55 ± 3 ° C.

Here, the relationship between the cathode current density and the electroformed film stress will be described. FIG. 8 is a graph showing the relationship between the cathode current density and the electroformed film stress during electroforming using the nickel electroforming liquid (see FIG. 7) used in this example. The electroformed film stress is a negative compressive stress on the low current density side, but the compressive stress weakens as the current density increases, and on the tensile stress side when it exceeds 10 A / dm ² .
Based on this data, electroforming is performed by changing the electroforming film stress at the center and both ends of the electroformed thin film roll, whether or not the mold can be removed after electroforming, and the penetration of the electroforming liquid during electroforming. The presence or absence of poor appearance of swelling and floating was judged. FIG. 9 is a table showing the relationship between the internal stresses at the center and both ends of the electroformed thin film roll and the possibility of demolding. FIG. 10 is a table showing the relationship between the internal stresses at the center and both ends of the electroformed thin film roll and the presence or absence of poor appearance of the electroforming liquid soaking and swelling. FIG. 11 is a table showing the internal stress range in which the results of FIGS. 9 and 10 were both good.
From this table, the range of demolding possible and no appearance defects stress in the thrust direction central portion of the electroforming film roll, -40~-60N / mm ^2, in the thrust direction both end portions 0~-30N / mm ² ,It can be seen that it is. The current density corresponding to this stress, from FIG. 8, the degree of the thrust direction central in part 3~5A / dm ^2, the 7~10A / dm ² in the range of about a thrust direction both end portions. FIG. 8 shows this range.

The central portion in the thrust direction of the electroformed thin film roll electroformed under such conditions expands due to high compressive stress and the inner diameter expands, and the expansion at the both ends in the thrust direction is smaller than the central portion in the thrust direction. Becomes smaller than the central portion. That is, the electroformed thin film roll has a cylindrical roll shape in which the inner diameter of the central portion of the cylinder is large, both end portions are slightly small, and both ends are slightly contracted. The difference in inner diameter varies depending on the stress difference between the center and both ends. When the stress difference is the largest (when the center stress is −60 N / mm ² and the stress at both ends is 0 N / mm ² ), When the inner diameter is 0.04% smaller than the inner diameter of the central portion and the stress difference is the smallest (when the central portion stress is −40 N / mm ² and the both end stress is −30 N / mm ² ), The inner diameter is 0.006% smaller than the inner diameter of the central portion. Therefore, the electroformed thin film roll manufactured according to the present embodiment has a roll shape in which the inner diameter of the both end portions is smaller by 0.006 to 0.04% than the inner diameter of the central portion.

Next, an electroforming procedure will be described. 12A and 12B are schematic views showing the relationship between the cylindrical matrix and the anode. FIG. 13 is a schematic view showing a state where the electroformed film is peeled off.
The cylindrical mother die is immersed in a position where the lower end of the upper insulating portion 9 of the cylindrical mother die 7 sinks about 30 mm from the surface of the electroforming bath, and energization is started. The cylindrical mother die 7 is 30 to 100 r / min. Rotate in the circumferential direction at
After immersion of the cylindrical mother die 7, the mother die surface is adapted to the electroforming bath in a non-energized state for about 10 seconds, and then the main rectifier 16 is energized with ³ to 5 A / dm ² to obtain a predetermined plating thickness (this embodiment) In the example, energization is continued for a period of time (about 32 to 53 minutes) until it reaches about 32 μm). The upper sub-rectifier 17 and the lower sub-rectifier 18 connected to the upper sub-anode 14 and the lower sub-anode 15 are kept in a non-energized state for about 10 seconds after the cylindrical mother die 7 is immersed, and then 7-10 A / dm ² . Current is applied at a current density for 16 to 23 minutes to deposit a predetermined plating thickness (about 32 μm in this embodiment).

Since the electroforming at the upper end and the lower end of the cylindrical mother die 7 is completed earlier than the central portion, after completion of the electroforming at both ends, the cylinder whose inner diameter is about 10 mm larger than the die radius and whose length in the thrust direction is about 30 mm. The shape shielding plates 54 are installed on the upper and lower ends of the cylindrical mother die 7 (see FIG. 12B). By installing shielding plates 54 between the upper sub-anode 14 and the cylindrical mother die 7 and between the lower sub-anode 15 and the cylindrical mother die 7, the upper and lower end plating thicknesses are not further increased, and electroforming is performed. After completion, the film thickness is almost the same as that at the center.
After energization, the cylindrical mother die 7 on which the electroformed film is formed is pulled up from the electroforming bath and washed with water.
Thereafter, the upper and lower ends of the electroformed film are peeled in a tape shape along the circumferential direction of the cylinder from the peeling start portions 10a and 11a at the upper and lower ends of the cylindrical mother die 7 (see FIG. 13), and then immersed in cold water. Thus, a gap is formed between the mother die and the nickel electroformed thin film roll due to a difference in thermal expansion, and water can penetrate there, whereby the electroformed film roll can be smoothly removed from the cylindrical mother die.
The removed electroformed film roll can be used as a fixing belt substrate by cutting unnecessary portions at both ends so as to have a required length.
The nickel electroformed thin film roll thus formed contains 0.5 to 0.7 mass% of phosphorus in addition to nickel as a main component. Therefore, even when the PFA release layer was subjected to heat treatment at 350 ° C. for 30 minutes, no defects such as scratches or breaks were found in the electroformed film even after the 200K paper passing test.

[Example 1]
The cylindrical matrix used in this example is made of SUS material No. 300 series material (SUS310 in this example), and the upper end of the cylindrical matrix is coated with an insulating coating. did. A reverse wedge-shaped insulating coat portion having a vertical width of 5 to 10 mm was formed immediately below the upper insulating portion. The surface of the cylindrical mother die was surface-treated so that the surface roughness Ra was 0.1 μm or less so that the electroformed film could be easily peeled and removed.
In the electroforming apparatus for electroforming the cylindrical mother die, at least one main anode is installed at a position facing the central portion in the thrust direction of the cylindrical mother die, and a position facing the upper and lower end portions in the thrust direction of the cylindrical mother die. In addition, at least one secondary anode was installed for each. In addition, the upper sub-anode and the lower sub-anode are provided with rectifiers independent from those for the main anode, so that the amount of current applied to the upper and lower ends of the cylindrical mother die can be independently adjusted. Electroforming was performed using an electroforming bath having a bath composition shown in FIG. 7 and having a pH adjusted to 3.5 to 4.5 and a bath temperature adjusted to 55 ± 3 ° C.
After immersion of the cylindrical mother mold, the mother mold surface is adapted to the electroforming bath in a non-energized state for about 10 seconds, and then the main rectifier is energized with ³ to 5 A / dm ² to obtain a predetermined plating thickness (in this embodiment, The energization is continued for a time (about 32 to 53 minutes) until reaching about 32 μm). The upper sub-rectifier and the lower sub-rectifier connected to the upper sub-anode and the lower sub-anode have a current density of 7 to 10 A / dm ² after being kept in a non-energized state for about 10 seconds after immersion of the cylindrical mother die. Energization is performed for 16 to 23 minutes to deposit a predetermined plating thickness (about 32 μm in this embodiment).

Since the electroforming of the upper and lower ends in the thrust direction of the cylindrical mother die is finished earlier than the center portion, the inner diameter is about 10 mm larger than the die radius after the electroforming of both ends, and the length in the thrust direction is about 30 mm. Cylindrical shielding plates are installed at both ends of the matrix. As a result, the plating thicknesses at the upper and lower end portions are not further increased, and the film thickness is substantially the same as that at the central portion.
After energization is completed, the cylindrical mother die on which the electroformed film is formed is pulled out of the electroforming bath and washed with water.
Thereafter, the upper part of the electroformed film is peeled off in a tape shape in the circumferential direction from the peeling start part of the upper and lower ends of the cylindrical mother die, and then immersed in cold water, so that the cylindrical mother die and the nickel electroforming are caused by the difference in thermal expansion. A gap is formed between the thin film rolls, and when water enters, the electroformed film roll can be smoothly removed from the cylindrical matrix.
The nickel electroformed thin film roll thus formed contained 0.5 to 0.7 mass% of phosphorus. Therefore, even when the paper passing test was performed 200K times after heat treatment at 350 ° C. for 30 minutes, no defects such as scratches or breakage were found in the electroformed film.

[Example 2]
As the material of the cylindrical matrix, an aluminum-based material can be used in addition to the above-mentioned SUS 300 series material. As the aluminum-based material, the 5000 series material is suitable because it is easily available and has good hardness. Since the base material of the aluminum-based material is eroded during nickel electroforming, a coating that is corrosion resistant and can form a passive film on the surface is formed on the surface of the base. As the coating, there are chromium, titanium, and nickel-phosphorus alloy. In this embodiment, a chromium coating with a strong passive film that can form a coating of about 10 to 20 μm satisfactorily by electroforming is selected. . Examples will be described below.

The A5056 aluminum material is processed to form the same shape as the cylindrical matrix described in the first embodiment. The side surface and the lower end surface of the aluminum cylinder were processed so that the surface roughness Ra was 0.1 μm or less.
A chromium film was formed on the surface of the cylindrical matrix by chromium electroforming.
First, the cylindrical matrix was immersed in an aqueous solution of sodium hydroxide having a temperature of about 30 to 50 g / liter and a liquid temperature of about 50 ° C. for 30 seconds to 1 minute and etched. Thereafter, it was washed with water.
Next, it was immersed in an aqueous nitric acid solution at 20 to 30% by weight at room temperature for about 1 minute to remove surface smut. A commercially available desmutting agent (Okuno Pharmaceutical: top desmutting etc.) may be used for smut removal. Thereafter, it was washed with water.

Next, a zinc replacement treatment with a zincate treatment agent was performed. In this example, Okuno Seiyaku: Substar ZN-111 was treated by immersing it in an aqueous solution of 500 ml / L at room temperature for 40 to 60 seconds. After washing with water, it was immersed in an aqueous nitric acid solution at 20 to 30% by weight at room temperature for about 1 minute to remove the surface zinc film once. Thereafter, by performing zincate treatment again under the same conditions, a fine and dense zinc film was formed on the surface of the cylindrical matrix.
Next, it is immersed in a chromium electroforming bath of pure chromic acid 250-300 g / L, sodium fluoride 15-20 g / L, sulfuric acid 0.5-1 g / L, bath temperature 40-50 ° C., 20-60 r / L min. While rotating at 10 to 20 A / dm ² for 10 to 20 minutes, a chromium film was deposited to 10 to 20 μm. In addition, the lead alloy of 2-5 mass% of antimony was used for the anode.
By using the cylindrical mother mold having such a configuration, the subsequent processes from electroforming to demolding are the same processes as in Example 1, so that an electroformed film roll can be manufactured satisfactorily by the nickel electroforming method. It was.

[Example 3]
The cylindrical matrix for depositing the electroformed film had the same configuration as in Example 1 or Example 2, and the same electroforming apparatus as that in Example 1 was used for electroforming. The nickel electroforming bath used in this example is nickel sulfamate 500 to 550 g / L which is difficult to be on the tensile stress side as nickel salt and can be high speed electroformed, boric acid 30 to 35 g / L as pH buffer, nickel The basic bath composition is 1 to 5 g / L of low-stress nickel bromide as a halide (see FIG. 7). As other additives, an appropriate amount of a pit inhibitor (sodium dodecyl sulfate or a commercially available product) may be used, 0.08 g / L of p-toluenesulfonamide as the primary brightener, and 2-butyne-1 as the secondary brightener. , 4-diol is added at 0.1 g / L. The steps so far are the same as the bath composition of FIG.
In this embodiment, 0.1 to 0.3 g / L of phosphorous acid or dipotassium phosphite is added instead of sodium phosphinate in order to improve the heat resistance of the electroformed film. The pH of the electroforming bath is adjusted to 3.5 to 4.5, and the bath temperature during electroforming is adjusted to 55 ± 3 ° C.

The electroforming procedure was the same as in Example 1. The demolding process after electroforming was also performed in the same process as in Example 1.
The nickel electroformed thin film roll thus formed contains 0.5 to 0.7 mass% of phosphorus in the same manner as in Example 1 in addition to nickel as the main component. Therefore, even when the PFA release layer was subjected to heat treatment at 350 ° C. for 30 minutes, no defects such as scratches or breaks were found in the electroformed film even after the 200K paper passing test.

  As described above, according to the present embodiment, since electroforming is performed at both ends in the thrust direction of the cylindrical matrix at a higher current density than the central portion, the central portion of the electroformed thin film roll has a high compressive stress. Therefore, the inner diameter of each end is smaller than that of the central portion. Slightly small cylindrical roll shape with both ends slightly shrunk, and during electroforming, both ends of the electroformed film are in close contact with the cylindrical matrix to prevent penetration of the electroforming liquid due to swelling and floating and poor appearance It is possible to smoothly remove the roll from the mother mold after electroforming.

In addition, when the thickness of the electroformed film on both ends of the electroformed thin film roll reaches a predetermined thickness, the energization of the rectifier for both ends of the cylindrical mother die is stopped, and at the same time, between the anode and both ends of the cylindrical mother die. Therefore, the electroformed film thickness can be made uniform at the center and both ends in the thrust direction without installing auxiliary electrode rings or the like at both ends of the cylindrical matrix.
The electroformed thin film roll thus manufactured has a shape in which the inner diameter at both ends in the thrust direction is smaller than the inner diameter at the center, and the inner diameter at both ends is 0.006 to 0.04 with respect to the inner diameter at the center. Therefore, during electroforming, both ends of the electroformed film are in close contact with the cylindrical mother die, preventing the electrocasting liquid from penetrating and poor appearance due to swelling and floating. Smooth demolding of the roll is possible.

Further, the internal stress in the thrust direction central portion of the electroforming internal stress of the film is in the range of ^{-60N / mm 2 ~-40N /} mm 2, and electroforming thrust direction end portions coating, -30N ^/ mm 2 ~0N Since it is in the range of / mm ² , a cylindrical roll shape in which the inner diameter of the central portion of the cylinder is large, both end portions are slightly small, and both ends are slightly contracted is obtained. At the time of electroforming, both ends of the electroformed coating are in close contact with the cylindrical mother die, preventing the electrocasting liquid from penetrating and poor appearance due to blistering and floating, and smooth removal of the roll from the mother die after electroforming. A mold becomes possible.

  DESCRIPTION OF SYMBOLS 1 ... Heat generating member, 2 ... Heat pipe, 3 ... Stay, 4 ... Pressure pad, 5 ... Fixing belt, 5a ... Electroformed film, 5b ... Sliding layer, 5c ... Elastic layer, 5d ... Release layer, 6 ... Pressure roller, 7 ... Cylinder matrix, 7a ... Electrodeposition site, 8 ... Hanging support electrode, 9 ... Upper insulating part, 10 ... Upper insulating coating part, 11 ... Lower insulating coating part, 10a, 11a ... Start of peeling , 12 ... nickel electroforming apparatus, 13 ... main anode, 14 ... upper sub-anode, 15 ... lower sub-anode, 16 ... main rectifier, 17 ... upper sub-rectifier, 18 ... lower sub-rectifier, 20 ... imaging unit, 21 ... Photoconductor, 22 ... Intermediate transfer belt, 22a, 22b, 22c ... Roller, 23 ... Secondary transfer roller, 24 ... Recording material cassette, 25 ... Recording material conveyance path, 26 ... Fixing unit, 27 ... Stack tray, 40 ... Image forming apparatus, 50 ... liquid circulation pump , 51 ... liquid ejection nozzle, 52 ... Filter, 53 ... auxiliary tank, 54 ... shield plate, N ... nip, P ... transfer paper

Japanese Patent No. 3866215

Claims (7)

P-Toluenesulfonamide as the primary brightener, 2-butyne-1,4-diol as the secondary brightener, and sodium phosphinate or phosphorous as an additive for improving the heat resistance of the electroformed film to nickel sulfamate A hollow cylindrical endless metal thin film roll manufactured by a nickel electroforming method using an acid-containing plating bath ,
An endless metal thin film roll characterized in that the inner diameter at both ends in the thrust direction is 0.006 to 0.04% smaller than the inner diameter at the center in the thrust direction. The internal stress of the electroformed film at the central portion in the thrust direction is −60 N / mm ² or more and −40 N / mm ² or less, and the internal stress of the electroformed film at both ends in the thrust direction is −30 N / mm ² or more. 0 N / mm < ² > or less, The endless metal thin film roll of Claim 1 characterized by the above-mentioned. A cylindrical matrix, at least one main anode installed at a position facing the central portion in the thrust direction of the cylindrical matrix, and at least one installed at positions opposed to both ends in the thrust direction of the cylindrical matrix. An endless metal thin film roll is manufactured by nickel electroforming using a sub-anode, a main rectifier connected to the main anode, and a sub-rectifier connected to the sub-anode and independent of the main rectifier. A method,
The plating bath consists of nickel sulfamate, at least p-toluenesulfonamide as the primary brightener, 2-butyne-1,4-diol as the secondary brightener, and phosphinic acid as an additive for improving the heat resistance of the electroformed film. Contains sodium or phosphorous acid,
Endless thin metal film roll and performs the current density of the cylindrical mold end portions and 7~10A / dm ^ 2, electroforming a current density of the cylindrical mold central portion as 3~5A / dm ^ 2 Manufacturing method.   After the electroforming starts, when the electroformed film on both ends of the cylindrical mother die reaches a predetermined thickness, the energization of the auxiliary rectifier is stopped and a shielding plate is provided between the auxiliary anode and the cylindrical mother die. The method for producing an endless metal thin film roll according to claim 3, wherein:   A sliding layer is formed on the inner peripheral surface of the endless metal thin film roll according to claim 1 or 2, or the endless metal thin film roll manufactured by the manufacturing method according to claim 3 or 4, and the outer peripheral surface is elastic. A heat-fixing belt, wherein a layer and a release layer are sequentially formed.   A fixing unit comprising the heat-fixing belt according to claim 5.   An image forming apparatus comprising the heat-fixing belt according to claim 5 or the fixing unit according to claim 6.

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