JP2006106350A - Fixing belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing belt made of electroformed nickel having excellent durability even at high temperature. <P>SOLUTION: The fixing belt (10) for fixing a toner image on a transfer material has an endless belt substrate (101) made of electroformed nickel. The belt substrate (101) contains 0.0045 to <0.017 mass% of sulfur, and with respect to crystallites of the belt substrate aligned on a crystal alignment surface on which such crystallites undergo large variation in grain size by heating, a rate of change in average grain size after heating at 250°C for 2 hours is ≤60%, based on average grain size before heating. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing belt having an endless belt base made of nickel electroforming, which is used to fix a toner image on a transfer material in a fixing unit of an image forming apparatus such as a facsimile or a laser beam printer.

  In image forming apparatuses such as facsimiles and laser beam printers, there is a belt fixing system that uses an endless fixing belt instead of a fixing roller in order to meet demands such as miniaturization, energy saving, and high-speed printing and copying. It has been adopted. Since the fixing belt is thin, the entire fixing belt is heated quickly, and there is an advantage that the waiting time after power-on can be greatly shortened.

  For example, Patent Document 1 discloses that an endless nickel belt substrate made of electroforming formed by electroforming is used as a belt substrate of such a toner fixing belt. In the electroforming method, a mother die (electric die, mold), for example, a stainless steel cylindrical mother die is used as a cathode, and a nickel plating film is formed by performing electroplating on the surface using a nickel plating bath. The film is peeled off (demolded) from the matrix to make a product.

Patent Document 1 describes that an endless nickel belt having a carbon content of 0.01 to 0.1% by mass is formed by electroforming. Patent Document 2 describes a belt fixing method using a halogen lamp as a heat source.
JP 2002-148975 A JP 2003-57981 A

  However, a conventional fixing belt having nickel electroforming as a belt substrate does not have sufficient heat-resistant fatigue strength at high temperatures and has poor durability. That is, the conventional nickel electroformed fixing belt substrate has a problem that cracks occur due to repeated use at high temperatures and the belt substrate breaks.

  Accordingly, an object of the present invention is to provide a highly durable fixing belt having improved heat fatigue characteristics at high temperatures.

  As a result of repeated crystallographic studies on the nickel electroformed belt substrate of the fixing belt used at high temperatures, the inventors of the present invention found that the broken belt substrate had a specific crystallite among the crystallites constituting nickel electroforming. The crystallites oriented in the crystal plane, for example, the crystallites oriented in the (111) plane on the back surface grow relatively large by heating at a high temperature, which causes breakage of the belt substrate at a high temperature. I found out. The inventors have found that this crystallite growth is suppressed through controlling the sulfur content in nickel electroforming. The present invention is based on such knowledge.

  That is, according to the first aspect of the present invention, there is provided a fixing belt for fixing a toner image on a transfer material, comprising an endless belt base made of nickel electroforming. The crystallites that are contained in a ratio of 0045% by mass or more and less than 0.017% by mass and that have a large change in crystallite grain size due to heating are aligned on the crystal orientation plane. The fixing belt is characterized in that the change rate of the average particle size after heating for 2 hours is 60% or less.

  According to a second aspect of the present invention, there is provided a fixing belt for fixing a toner image on a transfer material, comprising an endless belt base made of nickel electroforming, wherein the belt base contains 0.1% sulfur. The crystallites that are contained in a proportion of 0045% by mass or more and less than 0.017% by mass and that have a large change in crystallite grain size due to heating are aligned on the crystal orientation plane. The fixing belt is characterized in that the change rate of the average particle diameter after heating for 2 hours is 70% or less.

In the fixing belt of the present invention, the belt substrate preferably contains a crystal growth inhibitor composed of phosphorus, manganese, and / or boron.
In the present invention, regarding the belt substrate, the back surface means the inner peripheral surface of the belt substrate, and the front surface means the outer peripheral surface of the belt substrate.

  According to the present invention, it is possible to obtain a highly durable fixing belt that suppresses thermal degradation in a use environment and improves fatigue resistance characteristics at high temperatures.

Hereinafter, various aspects of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic front view of a toner fixing belt 10 according to one embodiment of the present invention, and FIG. 2 is a diagram showing a cross-sectional portion along II-II in FIG.

  The toner fixing belt 10 includes a belt base 101 formed endlessly by nickel electroforming. Usually, a release layer 103 made of a fluororesin or the like is coated on the surface (outer peripheral surface) 101a of the belt base 101 directly or via an elastic layer 102 such as silicone rubber. Further, a sliding layer 104 for improving slidability is formed on the back surface (inner peripheral surface) 101b of the belt base 101 as necessary. A primer layer (not shown) is provided between the belt base 101 and the elastic layer 102, between the elastic layer 102 and the release layer 103, or between the belt base 101 and the sliding layer 104 for adhesion. May be.

When the electromagnetic induction heating method is used, the thickness of the belt base 101 is represented by the following formula:
σ = 503 × (ρ / fμ) ^1/2
(Where σ is the skin depth (m), f is the frequency of the excitation circuit (Hz), μ is the magnetic permeability, and ρ is the specific resistance (Ωm)). It is preferable to be 1 μm or more and 100 μm or less. This skin depth indicates the depth of absorption of electromagnetic waves used for electromagnetic induction heating, and the intensity of electromagnetic waves becomes 1 / e or less deeper than this, and most energy is absorbed up to this depth. The If the thickness of the belt base is less than 1 μm, the belt base 101 cannot absorb most of the electromagnetic energy, and the efficiency may be lowered. On the other hand, if the thickness of the belt substrate 101 exceeds 100 μm, the rigidity increases, the flexibility decreases, and the flexibility tends to be impaired, making it difficult to use as a fixing belt.

  On the other hand, when used in a belt fixing method using a halogen heater as a heat source, the thickness of the belt base 101 is usually 10 to 100 μm, preferably 15 to 80 μm, in order to reduce heat capacity and improve quick start performance. More preferably, it is about 20 to 60 μm. From the viewpoint of balance between heat capacity, thermal conductivity, mechanical strength, flexibility, etc., the thickness is most preferably about 30 to 50 μm. When applied to a fixing belt of an electrophotographic copying machine, the width can be appropriately determined according to the width of a transfer material such as transfer paper.

  In the present invention, the nickel electroformed belt substrate 101 has a sulfur content of 0.0045% by mass or more and less than 0.017% by mass, and the crystallite has a large change in grain size due to heating. For the crystallites oriented in the orientation plane, the change rate of the average particle diameter after heating at 250 ° C. for 2 hours with respect to the average particle diameter before heating (ie, [(average particle diameter after heating−average particle diameter before heating) / Average particle size before heating] × 100) is 60% or less, and the crystallites oriented in the crystal orientation plane having a large change amount are heated at 300 ° C. for 2 hours with respect to the average particle size before heating. The average particle size change rate is 70% or less.

  Further, in the present invention, the nickel electroformed belt base 101 has a crystal orientation in which the change in the crystallite grain size due to heating is large from the viewpoint of the change in the average grain diameter of the crystallites constituting the belt base 101. For crystallites oriented in the plane, the difference between the average particle size after heating at 250 ° C. for 2 hours and the average particle size before heating, that is, the change due to heating is suppressed to 120 ° C. or less, and heated at 300 ° C. for 2 hours. The difference between the average particle diameter after heating and the average particle diameter before heating, that is, the amount of change due to the heating is suppressed to 90 mm or less.

  In the present invention, unheated (state) or before heating refers to a state in which the belt substrate is placed at an ambient temperature. The ambient temperature includes the temperature at which the belt substrate is placed after the belt substrate is manufactured by electroforming and before the fixing belt is manufactured using the belt substrate. Usually, this ambient temperature is at most 100 ° C.

  In general, in the present invention, the nickel electroformed belt base 101 can be composed of crystallites having an average particle size of 90 to 200 mm in an unheated state.

  The belt base 101 formed by the nickel electroforming method has crystallites oriented in a plurality of specific crystal orientation planes on the front and back surfaces. For example, a crystallite oriented in the (111) plane on the front surface (hereinafter referred to as “surface (111) crystallite”), and a crystallite oriented in the (111) plane on the back surface (hereinafter referred to as “back (111) crystallite”). ), Crystallites oriented in the (200) plane on the front surface (hereinafter referred to as “surface (200) crystallites”) and crystallites oriented in the (200) plane on the back side (hereinafter referred to as “back (200) crystals”. It can be mainly composed of “child”. In the present invention, among the crystallites constituting the nickel electroformed belt substrate, the crystal orientation plane having the largest change amount or change rate of the average grain size of the crystallites by heating (for example, heating at 250 ° C. for 2 hours) If the grain growth due to the heating of the oriented crystallites is suppressed, the thermal fatigue characteristics of the belt substrate 101 are significantly improved, that is, in the following thermal fatigue test, 300,000 times or more even under the maximum tension of 700 MPa. It was found that the number of repetitions was preferably 500,000 times or more, and more preferably 1,000,000 times or more, and excellent thermal fatigue characteristics were exhibited. The change rate of the average particle diameter of the crystallites by heating at 250 ° C. for 2 hours is preferably 40% or less. Further, the amount of change in the average particle size of the crystallites by heating at 250 ° C. for 2 hours is more preferably 50 μm or less.

  Needless to say, the average particle diameter of the crystallites oriented in each crystal orientation plane can be measured using an X-ray diffractometer. The average particle size of the crystallites can be determined by commercially available analysis software.

  The crystallites oriented in the crystal orientation plane having the largest change amount or rate of change of the crystallite grain size due to the heating are the front surface (111) crystallite, the back surface (111) crystallite, the front surface (200) crystallite, and the back surface ( 200) In a belt substrate composed of crystallites, it is the back (111) crystallite. It goes without saying that the selection of crystallites oriented in the crystal orientation plane where the change or rate of change of crystallites due to heating is the largest can also be applied to nickel electroformed belt substrates having other crystal orientation faces. Absent.

  Although details of improving the heat fatigue resistance of the belt substrate of the present invention are not detailed, the growth of crystallites is suppressed by containing sulfur in a content of 0.0045 mass% or more and less than 0.017 mass%. At the same time, it is thought that sulfur embrittlement is also suppressed. When the sulfur content is less than 0.0045% by mass, crystal growth during electrolysis is not significantly suppressed, and when the sulfur content is 0.017% by mass or more, under high tension due to sulfur embrittlement. The heat resistance durability of the is reduced. The belt substrate of the present invention can contain carbon at a content of 0.005 to 0.08 mass%.

  Such a belt substrate 101 is generally formed by electroforming using a nickel plating bath such as a watt bath mainly composed of nickel sulfate or nickel chloride or a sulfamic acid bath mainly composed of nickel sulfamate. Can do. The electroforming method is a method of obtaining a product by performing thick plating on the surface of a mother die and peeling it from the mother die. That is, the back surface (inner peripheral surface) 101b of the belt base 101 is a surface on the side in contact with the mother die.

  In order to obtain the belt base 101, a cylinder made of stainless steel, brass, aluminum or the like is used as a matrix, and a nickel plating film can be formed on the surface thereof using a nickel plating bath. When the matrix is a non-conductor such as silicone resin or gypsum, the conductive treatment is performed by graphite, copper powder, silver mirror, sputtering, or the like. In electroforming to a metal mother mold, in order to facilitate the peeling of the nickel plating film, a peeling process such as forming a peeling film such as an oxide film, a compound film, or a graphite powder coating film on the surface of the mother mold is performed. Is preferred.

  The nickel plating bath includes a nickel ion source, an anodic solubilizer, a pH buffer, and other additives. Examples of the nickel ion source include nickel sulfamate, nickel sulfate, and nickel chloride. As the anodic solubilizer, nickel chloride plays this role in the Watt bath, and in other nickel baths, ammonium chloride, nickel bromide and the like are used. Nickel plating is generally performed in the range of pH 3.0 to 6.2, but a pH buffering agent such as boric acid, formic acid, nickel acetate or the like is used in order to adjust the pH to a desired range. As other additives, for example, a brightener, a pit inhibitor, an internal stress reducer, and the like are used for the purpose of smoothing, prevention of pits, refinement of crystals, reduction of residual stress, and the like.

As the nickel plating bath, a sulfamic acid bath is preferable. The composition of the sulfamic acid bath is as follows: nickel sulfamate tetrahydrate 300 to 600 g / L, nickel chloride 0 to 30 g / L, boric acid 20 to 40 g / L, appropriate amount of surfactant, appropriate amount of brightener (primary brightener , Secondary brighteners) and the like. Examples of the primary brightener include naphthalene-1,3,6-trisulfonic acid trisodium, which is a sulfur supply source during nickel electroforming, and examples of the secondary brightener are during nickel electroforming. 2-butyne-1,4-diol, which is also a carbon supply source. The pH of the sulfamic acid bath is preferably 3.5 to 4.5. The bath temperature is preferably 40 to 60 ° C. The current density during electroforming is preferably in the range of 0.5 to 15 A / dm ² , and in the case of a high concentration bath, it is preferably in the range of 3 to 40 A / dm ² .

In one embodiment of the present invention, by adding a source of phosphorus, boron, and / or manganese to the nickel plating bath, particularly a nickel sulfamate bath, and performing electroforming under the above conditions, particles by heating the crystallites It has been found that growth can be more effectively suppressed. That is, phosphorus, boron, and / or manganese acts as a crystal growth inhibitor for crystallites. When electroforming is carried out using a nickel plating bath containing phosphorus, boron and / or manganese, particularly a sulfamic acid bath, the detailed mechanism is not clear. A large amount of phosphorus, boron, and manganese is taken into the nickel film first deposited on the surface, and the amount of phosphorus, boron, and manganese is relatively reduced in the nickel film deposited after that. As a result, the obtained belt substrate is suppressed on the back surface thereof, in particular, crystal growth of crystallites oriented in the (111) plane, and the heat fatigue resistance is improved.
Phosphorus can be co-deposited with nickel by adding it to a nickel plating bath in the form of a water-soluble phosphorus-containing acid salt such as sodium hypophosphite monohydrate. Boron can be co-deposited with nickel by adding it to a nickel plating bath in the form of a water-soluble organoboron compound such as trimethylamine borane. Manganese can be co-deposited with nickel by adding it to the nickel plating bath in the form of a water-soluble manganese compound such as manganese sulfamate tetrahydrate. Boric acid is not a source of boron into nickel electroforming. The nickel electroformed belt substrate of the present invention preferably contains phosphorus at a content of less than 0.4% by mass with respect to phosphorus. Usually, the phosphorus content is 0.04% by mass or more. Moreover, it is preferable that the nickel electroformed belt base | substrate of this invention contains boron with the content rate of 0.001 mass%-0.02 mass% about boron. Furthermore, it is preferable that the nickel electroformed belt base body of the present invention contains manganese at a content of 0.04% by mass to 0.5% by mass with respect to manganese.

  The toner fixing belt may be heated to 200 ° C. or higher. The heating temperature of 250 ° C. considered in the present invention is a temperature allowing for a margin with respect to the temperature of 200 ° C. The heating temperature of 300 ° C. considered in the present invention is a more severe condition, and is considered here as the maximum temperature that the toner fixing belt can encounter even temporarily by induction heating or the like.

  According to the present invention, the change rate of the average particle size after heating at 250 ° C. for 2 hours with respect to the average particle size before heating for the crystallites oriented in the crystal orientation plane where the change in the crystallite particle size by heating is large. It was found that the heat resistance fatigue characteristics of the nickel electroformed belt base material were significantly improved when the ratio was 60% or less. Therefore, after the nickel electroformed belt base material was manufactured, the rate of change in the average particle diameter before and after heating was found. It can be said that a fixing belt excellent in heat-resistant fatigue characteristics can be stably manufactured by measuring the above and measuring a change rate of 60% or less. Similarly, after producing a nickel electroformed belt substrate, the amount of change in the average particle size before and after heating is calculated for the crystallites oriented in the crystal orientation plane where the amount of change in the crystallite size due to heating is large, and the change By producing a product having an amount of 120% or less, a fixing belt excellent in heat fatigue resistance can be stably produced. Similarly, the change rate of the average particle diameter before and after heating at 300 ° C. for 2 hours can be measured, and the change rate of 70% or less can be commercialized, and the average particle diameter before and after heating at 300 ° C. for 2 hours. It is also possible to calculate the amount of change and to produce a product whose change amount is 90 mm or less.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited.
Comparative Examples 1-6 and Examples 1-7
Make an aqueous solution containing nickel sulfamate tetrahydrate at a rate of 500 g / L and boric acid at a rate of 35 g / L, and perform electrolytic purification at a low current while filtering with a 0.5 μm filter in a container filled with activated carbon. went. Next, after taking out activated carbon and adding a required amount of pit inhibitors, trisodium naphthalene-1,3,6-trisulfonate as a primary brightener and 2-butyne-1,4-as a secondary brightener. In Table 1 below, the diol was further used, optionally using sodium hypophosphite monohydrate as the phosphorus source, trimethylamine borane as the boron source, and manganese sulfamate tetrahydrate as the manganese source. The desired sulfamic acid bath (electrolytic bath) was prepared at the indicated ratio.

Using this electrolytic bath, electrocasting was performed at a predetermined bath temperature using a stainless steel cylindrical mother die having an outer diameter of 34 mm as a cathode, and an electrodeposit was formed on the outer peripheral surface of the mother die to a thickness of 50 μm. The current density is, for Examples 3 and 4, is set to 16.1A / dm ^2, in another example was set to 10.7A / dm ^2. The obtained electrodeposit was washed with pure water and then removed from the mother die to obtain a nickel electroformed belt substrate having an inner diameter of 34 mm and a thickness of 50 μm.

The nickel electroformed belt bases obtained in Comparative Examples 1 to 6 and Examples 1 to 7 were analyzed for sulfur and carbon content (mass%) using a combustion-infrared absorption method, and phosphorus and boron content rates. (% By mass) was analyzed using an ICP emission spectrometer, and the manganese content (% by mass) was analyzed using an atomic absorption spectrophotometer. The results are shown in Table 2.

Next, with respect to the belt substrates obtained in Comparative Examples 1 to 6 and Examples 1 to 7, the back surface (111) crystallite, the front surface (111) crystallite, the back surface (200) crystallite, and the front surface (200) crystal, respectively. The average particle size before heating the child, the average particle size after heating at 250 ° C. for 2 hours, and the average particle size after heating at 300 ° C. for 2 hours are measured with an X-ray diffractometer (RINT-2100 manufactured by Rigaku Corporation). The diffraction data was obtained by analysis software (JADE (registered mark)), and the change amount and change rate of the average particle diameter were calculated. The results are shown in Tables 3 to 6 below.

  As can be seen from the results shown in Tables 3 to 6, the crystallites constituting the nickel electroformed belt substrate obtained in Examples 1 to 7 have an average particle diameter of 90 to 200 mm before heating. And the crystallites constituting the nickel electroformed belt substrate obtained in Comparative Examples 1 to 6 and Examples 1 to 7, that is, the back surface (111) crystallite, the front surface (111) crystallite, the back surface (200) crystallite, Of the surface (200) crystallites, the crystallite having the largest amount of change and average rate of change in the average particle diameter before and after heating is found to be the back surface (111) crystallite.

<Thermal fatigue test>
The shape of No. 13B test piece defined in JISZ2201 was cut out from the belt bases obtained in Comparative Examples 1 to 6 and Examples 1 to 4 and 7, and a thermal fatigue test was performed using the INSTRON 8871 system manufactured by INSTRON under the following conditions. .

Maximum repeated tension: 650 MPa; Minimum repeated tension: about 80 MPa;
Atmospheric temperature: 250 ° C .; repetitive cycle: 15 Hz.

  This thermal fatigue test was performed until the test piece broke, and the number of repetitions at that time was recorded. The upper limit of the number of repetitions was set to 1 million. In this thermal fatigue test, the case where the number of repetitions was less than 300,000 was evaluated as “X”, and the case where the number of repetitions reached 1 million was not evaluated as “◯”. The results are shown in Table 7 below.

Among the belt bases that received the evaluation of “◯”, the thermal base test was similarly performed on the belt bases of Comparative Example 6 and Examples 1 to 4 (both containing phosphorus) by repeatedly changing the maximum tension to 700 MPa. It was. The results and evaluation are shown in Table 7.

  As can be seen from the results at the maximum tension of 650 MPa shown in Table 7, Comparative Examples 1 to 5 in which the sulfur content deviates from 0.0045 mass% ≦ S <0.017 mass% and does not contain a crystal growth inhibitor. This belt substrate breaks even when the number of repetitions is 110,000 times or less. The belt substrate of Comparative Example 6 containing a crystal growth inhibitor but having a sulfur content of 0.017% by mass does not break at the maximum tension of 650 MPa, even if it is repeated 1 million times, but the maximum tension is 700 MPa. If it increases, it will break after repeating 250,000 times. On the other hand, the belt bases of Examples 1 to 4 and 7 do not break even when the maximum tension is 650 MPa, even if the belt bases of Examples 1 to 4 have a maximum tension of 700 MPa. It does not break even after repeated times. And as for the belt base | substrate of Examples 1-4, the average particle diameter change rate of a back surface (111) crystallite in 300 degreeC 2 hours is 70% or less, and an average particle diameter variation | change_quantity is 90 mm or less.

  Although the present invention has been described in detail with respect to various aspects, the present invention is not limited to the above aspects as they are, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, you may delete some components from all the components shown by the said aspect. Furthermore, you may combine suitably the component over a different aspect.

1 is a front view of a fixing belt according to the present invention. The figure which expands and shows a part of cross section which follows the II-II line | wire of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fixing belt 101 ... Belt base 101a ... Belt base surface 101b ... Belt base back surface 102 ... Elastic layer 103 ... Release layer 104 ... Sliding layer

Claims (6)

  A fixing belt for fixing a toner image on a transfer material, comprising a nickel electroformed endless belt base, wherein the belt base is a ratio of 0.0045% by mass or more and less than 0.017% by mass of sulfur. The change rate of the average particle diameter after heating for 2 hours at 250 ° C. with respect to the average particle diameter before heating for the crystallites oriented in the crystal orientation plane with a large change in the crystallite particle diameter due to heating A fixing belt, wherein the fixing belt is 60% or less.   2. The crystallites oriented in a crystal orientation plane having a large change amount have a difference between an average grain size after heating at 250 ° C. for 2 hours and an average grain size before heating of 120 mm or less. The fixing belt described in 1.   The fixing belt according to claim 1, wherein the nickel electroforming includes at least one crystal growth inhibitor selected from the group consisting of phosphorus, boron, and manganese.   A fixing belt for fixing a toner image on a transfer material, comprising a nickel electroformed endless belt base, wherein the belt base is a ratio of 0.0045% by mass or more and less than 0.017% by mass of sulfur. The change rate of the average particle diameter after heating at 300 ° C. for 2 hours with respect to the average particle diameter before heating, with respect to the crystallite oriented in the crystal orientation plane with a large change amount of the crystallite particle diameter by heating. A fixing belt, wherein the fixing belt is 70% or less.   5. The crystallites oriented in the crystal orientation plane having a large change amount have a difference between an average grain size after heating at 300 ° C. for 2 hours and an average grain size before heating of 90 μm or less. The fixing belt described in 1.   6. The fixing belt according to claim 4, wherein the nickel electroforming includes at least one crystal growth inhibitor selected from the group consisting of phosphorus, boron, and manganese.

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