JP2006047766A - Toner fixing belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner fixing belt equipped with nickel electroformed belt base substance capable of coping with both of a heater heating system and an induction heating system, and meeting the demand of high durability, which gets larger and larger. <P>SOLUTION: The toner fixing belt (10) is equipped with the nickel electroformed belt base substance (11) containing phosphorus so that its content may be ≥0.05 mass% and <0.4 mass% and sulfur so that its content may be ≥0.005 mass%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  In the image forming apparatus, an endless fixing belt (endless belt or endless film) is used instead of the fixing roller in order to meet the demands for downsizing, energy saving, printing and copying speed of the image forming apparatus. A belt fixing system is adopted.

  As such a fixing belt, a belt substrate made of resin such as polyimide or a belt substrate made of stainless steel is known. These resin or stainless steel belt bases can be heated by a heating method using a heater, but an induction heating method in which the fixing belt self-heats by an eddy current due to electromagnetic induction cannot be adopted.

  On the other hand, the nickel electroformed belt substrate can employ either a heating method using a heater or an induction heating method. For example, Patent Document 1 and Patent Document 2 disclose a fixing belt including a nickel electroformed belt base.

  However, a conventional fixing belt having nickel electroforming as a belt base does not have sufficient heat fatigue strength at high temperatures and has poor durability (fatigue resistance). Nickel electroforming is also an important factor in that the mold release from the mother mold is good. In order to improve the demolding property and improve the fatigue resistance, Patent Document 3 discloses a nickel electroformed belt containing phosphorus in a content of 0.4 to 1.6% by mass. .

Recently, image forming apparatuses such as copiers, facsimiles, and laser beam printers have advanced high-speed printing that combines on-demand (quick start) and power savings, and the required printing resistance (durability). Has also increased. The conventional fixing belt having the nickel electroformed belt substrate may crack due to repeated use over a long period of time at a high temperature, resulting in insufficient durability.
JP 2002-148975 A JP 2003-57981 A JP 2000-26990 A

  Accordingly, the present invention provides a toner fixing belt having a nickel electroformed belt base that can be used for both the heater heating method and the induction heating method, and satisfying the increasing demand for high durability. The purpose is to provide.

  In order to achieve the above-mentioned object, the present inventors have conducted intensive research on a nickel electroformed belt substrate. As a result, the nickel electroformed belt substrate contains phosphorus and sulfur at a predetermined content rate, thereby providing a nickel electroformed belt substrate. The inventors have found that the durability has been dramatically improved, and that the nickel electroformed belt can be easily removed from the mold, and the present invention has been completed.

  That is, according to the present invention, there is provided a belt substrate made of nickel electroforming containing phosphorus in a content of 0.05% by mass or more and less than 0.4% by mass and sulfur in a content of 0.005% by mass or more. A toner fixing belt is provided.

  The toner fixing belt of the present invention is extremely excellent in durability and has good demoldability of the nickel electroformed belt substrate.

Hereinafter, various embodiments 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 an embodiment of the present invention, and FIG. 2 is an enlarged view of a cross-sectional portion taken along II-II in FIG.

  The fixing belt 10 has the same configuration as that of a normal toner fixing belt except that a predetermined nickel electroformed belt base 11 is provided as a nickel electroformed belt base. As shown in FIGS. 1 and 2, the fixing belt 10 is usually formed by coating the outer peripheral surface of the belt base 11 with a release layer 13 such as a fluororesin as an outermost layer directly or through an elastic layer 12 such as silicone rubber. In addition, a sliding layer (for example, polyimide, fluororesin, etc.) 14 is formed on the inner peripheral surface of the belt base 1 as necessary. The thickness of the elastic layer 12 is usually 20 to 1000 μm, preferably 150 to 450 μm. The thickness of the release layer 13 is usually 1 to 150 μm, preferably 5 to 50 μm. Moreover, the thickness of the sliding layer 14 is 5-100 micrometers normally, Preferably it is 10-60 micrometers.

  The thickness of the belt substrate 11 is preferably 1 μm to 100 μm when an electromagnetic induction heating method is used for heating the fixing belt. If the thickness of the belt substrate 11 is less than 1 μm, the belt substrate cannot absorb most of the electromagnetic energy, and the heating efficiency tends to decrease. On the other hand, when the thickness of the belt base 11 exceeds 100 μm, the rigidity increases and the flexibility decreases, so that the flexibility is impaired and it tends to be difficult to use as a fixing belt.

  On the other hand, when a halogen heater is used as a heat source for heating the fixing belt, the thickness of the belt base 11 is usually 10 to 100 μm, preferably 15 to 80 μm in order to reduce the heat capacity and improve the quick start property. More preferably, it is about 20-60 micrometers. From the viewpoint of the balance of heat capacity, thermal conductivity, mechanical strength, flexibility, etc., a thickness of about 30 to 50 μm is most preferable.

  The nickel electroformed belt substrate 11 of the present invention contains phosphorus in a content of 0.05% by mass or more and less than 0.4% by mass and sulfur in a content of 0.005% by mass or more. Under the specific condition that the phosphorus content is set to a low range of 0.05% by mass or more and less than 0.4% by mass, and the sulfur content is set to 0.005% by mass or more, unexpectedly, It has been found that the heat fatigue resistance of the nickel electroformed belt substrate is remarkably improved and the demolding property is also improved.

  When the phosphorus content in the nickel electroformed belt substrate 11 is less than 0.05 mass%, the heat resistance fatigue characteristics of the nickel electroformed belt substrate are sufficiently improved even if the sulfur content is set to 0.005 mass% or more. On the other hand, if the phosphorus content is 0.4% by mass or more, the demoldability of the nickel electroformed belt substrate is deteriorated. The phosphorus content is preferably 0.1% by mass or more and less than 0.4% by mass.

  Further, when the sulfur content in the nickel electroformed belt substrate 11 is less than 0.005% by mass, the nickel electroforming is performed even if the phosphorus content is set to 0.05% by mass or more and less than 0.4% by mass. The heat fatigue resistance and demoldability of the belt substrate are not sufficiently improved. The sulfur content is preferably 0.016% by mass or less. When the sulfur content exceeds 0.016% by mass, the nickel electroformed belt substrate becomes hard and brittle, and the heat fatigue resistance tends to decrease. The sulfur content is particularly preferably 0.01 to 0.016% by mass.

  When the carbon content of the nickel electroformed belt substrate 11 of the present invention is 0.04% by mass or less, the demolding property becomes better without diminishing the effect of improving the thermal fatigue properties caused by phosphorus and sulfur. I understood it. From the viewpoint of improving demoldability, the nickel electroformed belt substrate may not contain carbon (carbon content: 0%), but carbon is contained in the electroforming bath used for producing the nickel electroformed belt substrate. Derived from the above components (for example, primary brightener, secondary brightener) and inevitably contained. Therefore, usually, the carbon content of the nickel electroformed belt substrate exceeds 0% by mass. In the present invention, the carbon content is more preferably 0.01% by mass or less. The carbon content is particularly preferably 0.005 to 0.01% by mass.

  The belt substrate 11 can be generally formed by electroforming using a nickel electroforming bath such as a watt bath mainly composed of nickel sulfate or nickel chloride or a sulfamic acid bath mainly composed of nickel sulfamate. . The electroforming method is a well-known method for obtaining a product by performing nickel plating on the surface of the mother die and peeling it from the mother die.

  Various electroforming baths known in the art can be used as the nickel electroforming bath, but a sulfamic acid bath is preferably used. The sulfamic acid bath contains nickel sulfamate tetrahydrate 300 to 600 g / L, nickel chloride 0 to 30 g / L, boric acid 20 to 40 g / L, an appropriate amount of primary brightener, secondary brightener and the like. Can be mentioned. The pH of the electroforming bath is preferably 3.5 to 4.5. The sulfamic acid bath is used for pH buffering agents such as boric acid, formic acid, nickel acetate, and for the purpose of smoothing, pit prevention, crystal refining, reduction of residual stress, etc. A stress reducing agent or the like can be contained.

  In the present invention, a water-soluble phosphorus-containing acid salt such as sodium hypophosphite is added to the nickel electroforming bath as a source of phosphorus contained in the nickel electroformed belt substrate. By adjusting the amount of the water-soluble phosphorus-containing acid salt, the phosphorus content defined in the present invention can be achieved. For example, when sodium hypophosphite is used, it can be added to the sulfamic acid bath at a concentration of 40 to 200 mg / L, for example. Sulfur is also introduced into the nickel electroformed belt substrate from nickel sulfamate, and the main source is trisodium naphthalene-1,3,6-trisulfonate used as a primary brightener. And introduced into the nickel electroformed belt substrate. Therefore, the ratio of the primary brightener can be adjusted to achieve the sulfur content defined in the present invention. Carbon is mainly introduced into the nickel electroformed belt substrate using the primary brightener and 2-butyne-1,4-diol used as a secondary brightener as its supply source. Therefore, the carbon content can be achieved by adjusting the amount of the primary brightener and the secondary brightener.

In electroforming, the temperature of the sulfamic acid bath is preferably set to 40 to 60 ° C., and the current density is preferably set to a range of 0.5 to 15 A / dm ² . In the case of high concentration bath, the current density is preferably in the range of 3~40A / dm ^2.

  By performing electroforming in this manner, a nickel electroformed belt substrate containing a predetermined amount of phosphorus and sulfur and, if necessary, a predetermined amount of carbon can be obtained.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited.
The toner fixing belt is heated from the inside, and the belt substrate may be heated to 200 ° C. or higher. The heating temperature of 250 ° C. considered in the fatigue characteristic evaluation of the following examples is a temperature that allows for a margin with respect to the temperature of 200 ° C.
Examples 1-8, Comparative Examples 1-5
An aqueous solution containing nickel sulfamate tetrahydrate at a rate of 500 g / L and boric acid at a rate of 30 g / L was made, and this aqueous solution was electrolytically purified at low current while circulating between the vessel filled with activated carbon and the electrolytic cell. did. In the aqueous solution thus purified, trisodium naphthalene-1,3,6-trisulfonate as the primary brightener, 2-butyne-1,4-diol as the secondary brightener, and sodium hypophosphite monohydrate as the phosphorus source The desired sulfamic acid bath (electroforming bath) was prepared by adding the products at the ratios shown in Table 1 below, and further adding a pit inhibitor so that the surface tension of the aqueous solution was 36 mN / m. Made of stainless steel with an outer diameter of 34 mm rotating in the electroforming bath while continuously stirring with a 0.5 μm filter while maintaining the bath temperature at 60 ° C. and maintaining the pH at 4.5. Electroplating was performed under the current density shown in Table 1 with a cylindrical mother die as the cathode and a titanium basket containing nickel pellets as the anode, and the electrodeposit was deposited on the outer periphery of the mother die to a thickness of 50 μm. Formed. The matrix having this electrodeposit was removed from the electroforming bath and washed with water. The burrs at both ends of the electrodeposit were cut off. The mother die having this electrodeposit is immersed in water to release the electrodeposit from the mother die, and after being pulled out of the mother die, it is thoroughly washed and dried to a nickel electroforming belt having an inner diameter of 34 mm and a thickness of 50 μm. A substrate was obtained.

<Demoldability>
The demoldability of the belt substrate was evaluated according to the following criteria.

◎… When the above-mentioned mother mold is immersed in water for 15 minutes or less, it is pulled out from the matrix. ○… When the above-mentioned immersion in water exceeds 15 minutes, it is pulled out of the mother mold within 25 minutes. ... The above immersion time exceeds 25 minutes, but has been withdrawn from the mother mold in 1 hour.

  The results are shown in Table 2.

<Phosphorus, sulfur and carbon content>
About each obtained nickel electroformed belt base | substrate, the content rate of phosphorus, sulfur, and carbon was measured. The phosphorus content is measured by an inductively coupled plasma (ICP) emission spectrometer, and the sulfur and carbon contents are measured by high-frequency heating combustion in the oxygen stream-infrared absorption method (heating the sample in the oxygen stream to cause oxidation reaction) The carbon in the sample is converted to carbon dioxide and carbon monoxide, and the sulfur in the sample is converted to sulfur dioxide and introduced into the infrared detector at a constant flow rate. The detected carbon dioxide and carbon monoxide The carbon content in the sample is calculated from the detected sulfur dioxide, and the sulfur content in the sample is calculated from the detected sulfur dioxide. The results are also shown in Table 1.

<Thermal fatigue test>
A No. 13B test piece defined in JIS Z2201 was cut out from the belt bases obtained in Examples 1 to 8 and Comparative Examples 1 to 6, and a thermal fatigue test was performed using the INSTRON 8871 system manufactured by INSTRON under the following conditions.

Maximum repeated tension: 700 MPa; Minimum repeated tension: 80 MPa;
Atmospheric temperature: 250 ° C .; repetitive cycle: 15 Hz.

  This thermal fatigue test was conducted until the test piece broke, and the number of repetitions until that time was recorded (however, the test was completed after 10 million times; therefore, when the test piece was not broken even after 10 million times of repetition) Is written as “10000000 or more”). The results are also shown in Table 2.

  From the results shown in Table 2, the carbon content of the nickel electroformed belts of Examples 1 to 8 and Comparative Examples 1 to 5 is not significantly different, but the phosphorus content specified in the present invention: 0.05% ≦ P <0.4% and sulfur content: 0.005% ≦ Similarly, the nickel electroformed belt bases of Examples 1 to 8 (see Table 1) have very high thermal fatigue resistance as defined in the present invention. It can be seen that the demoldability is satisfactory. In contrast, the nickel contents of Comparative Examples 1 and 2 and Comparative Example 5 that do not satisfy the phosphorus content: 0.05% ≦ P <0.4% and the sulfur content: 0.005% ≦ S specified in the present invention at the same time The electroformed belt substrate (see Table 1) has extremely poor heat fatigue resistance. The nickel electroformed belt substrate of Comparative Examples 3 and 4 could not be removed.

  Here, in terms of mold releasability, the nickel electroformed belt of Comparative Example 1 does not contain phosphorus and has a relatively high carbon content (see Table 1). It is good. Further, the nickel electroformed belt of Comparative Example 5 does not contain phosphorus, and the demoldability is good even though the carbon content is in the range of Examples 1-8. However, the nickel electroformed belts of Comparative Example 3 and Comparative Example 4 have a phosphorus content in the range specified in the present invention, and the carbon content is also in the range of Examples 1 to 8. Therefore, demolding was impossible. This is because the nickel electroformed belts of Comparative Examples 1 and 5 have a sulfur content within the range defined in the present invention, whereas the nickel electroformed belts of Comparative Examples 3 and 4 have a sulfur content. It is clear from the data in Table 1 that this is due to the deviation from the range defined in the present invention. That is, it is understood that the sulfur content has a greater influence on the demoldability than the carbon content.

  Next, the nickel electroformed belts of Comparative Examples 1 and 2 have a sulfur content within the range defined by the present invention, but the phosphorus content deviates from the range defined by the present invention. As a result, as shown in Table 2, the heat fatigue characteristics are remarkably inferior.

  Furthermore, when the nickel electroformed belt bases of Examples 1 to 8 are compared and examined, preferable content rate conditions of phosphorus and sulfur (0.01% ≦ P <0.4; 0.005% ≦ S ≦ 0.016%) The nickel electroforming belts of Examples 1 to 6 satisfying the above conditions have the phosphorus and sulfur content in the range defined by the present invention, but the nickel electroforming belts of Examples 7 to 8 outside this preferable content condition It has much better heat fatigue resistance than belts. Moreover, when the carbon content is viewed from the viewpoint of demoldability, it can be seen that if the carbon content is 0.04% by mass or less, the demoldability is satisfactory. Furthermore, it can be seen from the results of Examples 1 and 2 and Comparative Example 5 that the demoldability is particularly excellent when the carbon content is 0.005 to 0.01% by mass. Further, from the results of Examples 1 and 2, if the phosphorus content is 0.1% by mass or more and less than 0.4% by mass and the sulfur content is 0.01 to 0.016% by mass, extremely excellent heat resistance is obtained. It can be seen that a nickel electroformed belt substrate exhibiting fatigue properties is obtained.

  Next, for reference, the belt substrate according to the heat history (unheated or after heating at 300 ° C. and 350 ° C. for 2 hours) of the nickel electroformed belt substrate obtained in Examples 1 to 8 and Comparative Examples 1 to 5, respectively. The hardness (micro Vickers hardness (Hv)) of the front surface (outer peripheral surface) and the back surface (inner peripheral surface) was measured using MVK-G1 manufactured by Akashi Co., Ltd. In measuring the Vickers hardness, the load was 100 gf and the load holding time was 15 seconds. The results are shown in Table 3 below.

  From the results shown in Table 3, the nickel electroformed belt bases of Examples 1 to 6 that were particularly excellent in heat-resistant fatigue properties were unheated and had a Vickers hardness of 330 to 590 on both front and back surfaces after heating at 300 ° C. for 2 hours and 350 It can be seen that both the front and back surfaces exhibit a Vickers hardness of 360 to 700 after heating at ° C for 2 hours.

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 ... Toner fixing belt 11 ... Belt base 12 ... Elastic layer 13 ... Release layer 14 ... Sliding layer

Claims (8)

  A toner fixing belt comprising a nickel electroformed belt substrate containing phosphorus in a content of 0.05% by mass or more and less than 0.4% by mass and sulfur in a content of 0.005% by mass or more.   The toner fixing belt according to claim 1, wherein the phosphorus content is 0.10% by mass or more.   The toner fixing belt according to claim 1, wherein the sulfur content is 0.016% by mass or less.   The toner fixing belt according to claim 3, wherein the sulfur content is 0.01 to 0.016 mass%.   The toner fixing belt according to claim 1, wherein the belt base contains carbon at a content of 0.04% by mass or less.   The toner fixing belt according to claim 5, wherein the carbon content is 0.005 to 0.01 mass%.   The belt substrate has a phosphorus content of 0.1 mass% or more and less than 0.4 mass%, sulfur content of 0.01 to 0.016 mass%, and carbon content of 0.005 to 0.01. 2. The toner fixing belt according to claim 1, wherein the toner fixing belt is contained at a content of mass%.   The toner fixing belt according to claim 1, further comprising a release layer as an outermost layer.

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