JP2003098881A - Member for fixing, method for manufacturing the same and device for forming image having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a member for fixing, a method for manufacturing it and a device for forming images having it that excels in heat resistance, flexibility and toner mold release properties, and improves the gloss of the image, the uneven gloss of image, and a fixed temperature range by making a surface smooth without cracks. SOLUTION: In a member for fixing (1), having a mold release layer 4, or an elastic layer (3) and a mold release layer (4) made of heat-resistant rubber on a substrate (2) one after another, the mole release layer 4 is made of fluorine resin, average roughness in the central line of a surface of which has Ra less than 1 μm, the ten-point average roughness, which has Rz less than 2 μm and the average inclination of which has θa less than 3 deg.. The mold release layer 4 is burnt, without touching anything on a surface of a fluorine resin applying layer in the first burning, and after the second burning, the fluorine resin applying layer is formed by heating and burning in a situation, where a smooth surface made of material having more heat resistance than the melting point of the fluorine resin is made to touch on the surface of fluorine resin applying layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine,
In an image forming apparatus such as a laser printer or a facsimile, a fixing member such as a roll, a sheet, an endless belt used to heat and pressurize an unfixed image on a transfer paper, a manufacturing method thereof, and an image formation including the fixing member. Regarding the device.

[0002]

2. Description of the Related Art FIG. 4 is an explanatory view of a conventional electrophotographic image forming apparatus. A conventional electrophotographic image forming apparatus 100, such as a copying machine and a laser printer, includes a photosensitive drum 101 and a photosensitive drum 1 on which an electrostatic latent image is formed.
01, a charging roll 102 for performing a charging process, an exposure unit 103 such as a laser beam, a developing roll 104 for adhering toner to an electrostatic latent image on the photoconductor drum 101, and a DC voltage for applying a DC voltage to the charging roll 102. Power pack 1
05, the toner image on the photosensitive drum 101 is recorded on the recording paper 107
Transfer roller 106 for performing transfer processing on the surface, a cleaning device 108 for cleaning the photoconductor drum 101 after the transfer processing, a surface potential meter 109 for measuring the surface potential of the photoconductor drum 101, and a heat fixing roll 111 and a pressure roll. The thermal fixing device 110 is composed of 112.

Image forming apparatus 1 using this electrophotographic system
In 00, the photosensitive layer of the rotating photosensitive drum 101 is uniformly charged by using a charging roll 102, and then exposed by an exposing means 103 such as a laser beam to form an electrostatic latent image. The image is developed with toner to form a toner image, the toner image is transferred onto a recording paper 107, and the recording paper 107 is passed through a heat fixing device 110 including a heat fixing roll 111 and a pressure roll 112. The toner adhering to the recording paper 107 is heated by the heat fixing roll 1
The toner image is softened by the heat of 11 and pressed to thermally fix the toner image on the recording paper 107.

The heat fixing roll 111 is composed of a roll having a fluororesin layer provided on a core metal. Such a heat fixing roll 111 is excellent in mold releasability but inferior in flexibility and elasticity, so that it can be applied to an image forming apparatus such as a full color copying machine or a full color laser printer which requires gloss. Can not do it. Conventionally, in image forming apparatuses such as full-color copying machines and laser printers that require glossy images, red (magenta), blue (cyan), yellow (yellow), black (black)
4 color toners are used. When fixing a color image composed of these color toners,
It is necessary to mix these color toners in a molten state. Therefore, the melting point of the color toners is lowered to facilitate melting, and a plurality of types of color toners are wrapped by the surface of the heat fixing roll 111 and melted. It is necessary to mix uniformly in the state. Therefore, one of the properties required for the surface of the fixing member (roll, belt) is flexibility. As a fixing member for full color that gives flexibility to the surface of the fixing member, a rubber layer such as silicone rubber or fluororubber (a rubber material considering release and durability is used rather than the base rubber). There is a heat-fixing roll having a structure provided with.

The heat roll fixing method is suitable for increasing the printing speed because it has the advantages that it can hold the entire heat roll at a predetermined temperature and has a large heat capacity. However, the heat roll fixing method has a problem in that it takes a considerable amount of time to heat the heat roll to a predetermined temperature, so that the entire heat roll consumes a large amount of power. In recent years, in the field of image forming apparatuses, activities for energy saving have become active, and reduction of the rise time thereof has been studied. As one of the technologies for shortening the start-up time of the image forming apparatus,
A belt fixing method has been proposed in which toner on recording paper is heated via a film-shaped endless belt heated by a heater. In this fixing method, the fixing belt in the form of a thin film is directly heated, and after the power is turned on, the heating portion reaches a predetermined temperature in a short time, so that the waiting time after the power is turned on can be considerably reduced. Further, since only the necessary portion is heated, there is an advantage that power consumption is small.

FIG. 5 is an explanatory view showing a usage state of a conventional fixing endless belt. As shown in FIG. 5, in the conventional image forming apparatus, a heating roll 115 and a pair of parallel pressure rolls 116, 1 provided opposite to the heating roll 115 are provided.
16 and a belt type fixing device 113 having a fixing endless belt 114 which is in contact with the heating roll 115 and is rotatably provided by a pair of parallel pressure rolls 116, 116. Conventionally, it has been proposed to directly form an elastic layer on the base of the fixing endless belt 114 using a rubber material such as silicone rubber or fluororubber in consideration of releasability and durability.

As described above, since the surfaces of the conventional fixing roll and fixing belt are composed of the elastic layer formed of resin such as silicone rubber and fluororubber, the flexibility is excellent, but the toner is released from the toner. Because of lack of sex,
The toner offset phenomenon is likely to occur. Further, since these elastic layers have low wear resistance, the surface is severely worn and deteriorated. To solve these problems, there is a method of applying a silicone-based lubricating oil to the surfaces of the fixing roll and the fixing belt. However, although this oil application method is initially effective, it is not sufficient, and this oil causes a new problem of swelling of the rubber material. Further, the mechanism for applying the oil (including the coating amount control mechanism) and the replenishment of the oil cause the troubles of user maintenance and high cost. Therefore, a fixing member that does not use oil is desired.

Recently, it has been proposed that a rubber elastic layer is provided on the base of the fixing roll and the fixing belt, and a release material such as fluororesin is coated on the elastic layer. However, when the elastic layer is coated with a release material such as a fluororesin, the flexibility, which is an important characteristic of the surface of the fixing member, tends to decrease. Problems in this case include non-uniformity of the image and poor transparency of the image on the OHP sheet. Therefore, it is desired to develop a technical means for avoiding these problems, for example, a technique relating to a coating method that does not impair the flexibility of the elastic layer and a technique relating to a coating material.

Conventionally, polytetrafluoroethylene copolymerization (PTF) has been used as a material for the release layer for the fixing roll.
E) is used, but recently, since tetrafluoroethylene-polyethylene fluorovinyl ereyl copolymerization (PFA) has better workability, PFA is mainly used as a material for the release layer for the fixing roll. It is used. In particular,
Recently, the use of PFA tubes has increased. PFA
The advantage of the tube is that the surface property is excellent. Further, silicone rubber or the like is often interposed as an elastic layer between the cored bar and the release layer for the purpose of improving image quality, but it is also possible to prevent heat deterioration of the rubber of the elastic layer by using a tube. If a tube is used for the release layer, even if the curing temperature of the silicone resin is high, it can be processed by raising the temperature to around 200 ° C. Therefore, such a problem does not occur.
Therefore, until now, when using PFA, the above-mentioned tube method or powder coating has been considered.

Further, the tube system has no problem of cracking, but when used in an actual machine, there is a problem that wrinkles, floating, etc. occur due to insufficient adhesion between the tube and the elastic layer. In the coating method, generally, the elastic layer and the release layer are adhered to each other via a primer, but the elastic layer and the release layer are adhered in a state where the release layer is baked and melted. In order to be well glued.

On the other hand, when a tube is used, there are two methods: a method of covering the tube later or a method of casting an elastic layer between the tube and the base body. Since the tube is adhered to the primer without being melted, the adhesion is insufficient as compared with the melt adhesion of the coating method. Further, in particular, in the method of casting the elastic layer, the gas or the like generated during firing of the elastic layer cannot pass through the tube, and air bubbles are generated between the tubes, resulting in poor adhesion. There is also a method of finally heating and melting and bonding the tube, which improves the adhesiveness and gas permeability, but causes the problem of wrinkling due to shrinkage of the tube.

The tube tends to have uneven strength in the circumferential direction (direction perpendicular to the extrusion direction) due to its processing characteristics. It is considered that the extrusion speed (amount) fluctuates due to pressure fluctuations and the like during molding. Therefore, partial elongation, that is, wrinkles are likely to occur, especially the outer diameter is 30 m.
When the thickness is m or more and the film thickness is 50 μm or less, wrinkles are likely to occur.
Also, due to handling problems, the tube size is 20μ
It is difficult to form with a thickness of m or less. Such a problem of wrinkles does not occur in a fixing device using a general roll, but in an image forming apparatus using a belt-shaped fixing member,
This is especially likely to occur because the belt is largely bent.

On the other hand, in the coating method, since PFA is formed on the elastic layer by coating or the like and is heated to a temperature of about 350 ° C. and baked, the elastic layer is easily deteriorated by the heat. Therefore, there is a problem that even a silicone rubber that is said to have excellent heat resistance (heat resistance temperature of about 250 ° C.) is deteriorated.

[0014]

Therefore, the inventor of the present invention
It has been found that iron oxide is added to silicone rubber to improve heat resistance, and an elastic layer that can withstand temperatures up to around 350 ° C. was formed, but it was found that the following problems occur. That is, the elastic layer expands when the temperature of the silicone rubber forming the elastic layer rises, whereas the PFA forming the release layer follows the expansion of the elastic layer because of poor fluidity. The phenomenon that cannot be done occurs. As a result, there is a problem that surface defects such as cracks occur in the release layer. Also,
Since the elastic layer is thicker than the release layer, it has a larger heat capacity than the release layer and is gradually cooled. Therefore, in the cooling step, the release layer has a higher temperature, and when the release layer in such a state is cooled, the release layer is rapidly cooled. Therefore, there is a problem that the elastic layer shrinks even after the release layer is solidified, so that the release layer is also cracked.

There are two means for coating, wet coating such as spraying, dipping, roll coating, blade coating and the like, and powder coating has a larger particle diameter of the fluororesin (10 .About.50 .mu.m), there is a large margin for cracks. However, in powder coating, if the particle size of the fluororesin used is large, the surface properties after film formation deteriorate, and secondary processing or the like is often required. Further, it is possible to increase the particle size of the fluororesin by wet coating, but since the particle size is as small as 0.1 to 2 μm as compared with the particle size of the fluororesin in powder coating, it is difficult to make a great improvement. As a result, in order to use the fluororesin dispersion, for example, Japanese Patent Publication No. 7-4355.
As disclosed in Japanese Patent Laid-Open No. 6-59 and Japanese Patent Laid-Open No. 11-5059, there is known a secondary processing method for suppressing the rubber deterioration of the elastic layer as much as possible and improving the film forming property of the release layer. With such a conventional technique, although it is possible to reduce the rubber deterioration, it is difficult to satisfy the surface characteristics of the release layer which satisfies the required specifications in the oilless fixing system. Also, if the film-forming property is insufficient such as cracks appearing on the surface of the release layer before secondary processing, no matter how much heating is performed above the melting point during secondary processing, cracks will be eliminated. I can't.
In the case of a fluorine material having a particle size of about 0.3 μm used in a fluororesin dispersion, once a crack is formed, that is, a gap is formed between the particles, the fluorine material originally has poor fluidity and also has a film-forming agent. Since it is almost removed, no crack can be filled, that is, a gap, no matter how much it is heated.

The present invention aims to solve such problems. That is, the present invention provides a fixing member which is excellent in heat resistance, flexibility, and toner releasability, and has a smooth surface without cracks to improve image gloss, image gloss unevenness, and fixing temperature range. An object of the present invention is to provide a manufacturing method thereof and an image forming apparatus having the manufacturing method.

[0017]

In order to achieve the above-mentioned object, the invention described in claim 1 has a release layer on a substrate,
Alternatively, in a fixing member sequentially having an elastic layer and a release layer, the release layer is made of a fluororesin, and the center line average roughness Ra of the surface of the release layer is set to 1 μm or less, and a ten-point average is used. The fixing member is characterized by having a roughness: Rz of 2 μm or less and an average inclination: θa of 3 ° or less.

The invention described in claim 2 is the invention described in claim 1, wherein the base is (a) a sheet or an endless belt made of a metal material such as stainless steel or nickel, (b) A sheet or an endless belt made of a heat-resistant resin material such as polyimide or polyamide-imide, or (c) a laminated sheet or an endless belt of (a) and (b) above.

According to a third aspect of the invention, in the invention according to the first aspect, the substrate is aluminum.
The roll is made of a metal material such as stainless steel or brass.

According to a fourth aspect of the present invention, in a method of manufacturing a fixing member having an elastic layer and a release layer on a substrate in this order, a fluororesin is coated on the surface of the elastic layer to form a fluororesin coating layer. After that, the fluororesin coating layer is heated to a temperature equal to or higher than the melting point and baked at least twice or more,
At that time, in the first baking, the surface of the fluororesin coating layer was baked without contacting anything, and in the second and subsequent baking, the fluororesin coating layer was formed on the surface of the melting point of the fluororesin. In a state where a smooth surface body formed of a heat-resistant material is in contact, it is heated and fired, and then the heat-fired fluororesin coating layer is removed to remove the smooth surface body and crystallize the fluororesin. A method for producing a fixing member, characterized by forming a release layer by rapidly cooling to a crystallization temperature or lower, or by cooling while keeping in contact with a smooth surface body until the temperature falls to a crystallization temperature. Is.

The invention described in claim 5 is characterized in that, in the invention described in claim 4, a fluororesin dispersion liquid is applied to the surface of the elastic layer.

According to a sixth aspect of the present invention, in the invention according to the fourth or fifth aspect, the fluororesin coating layer which has been heated and fired for the second time and thereafter is crystallized at a cooling rate of 30 ° C./min or more. It is characterized by being rapidly cooled to below the temperature.

The invention described in claim 7 is the invention defined in claims 1 to 3.
An image forming apparatus having the fixing member according to any one of 3 above.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. 1 is a sectional view of a fixing endless belt showing an embodiment of the present invention, FIG. 2 is a sectional view of a fixing roll showing another embodiment of the present invention, and FIG. FIG. 3 is an explanatory diagram showing the relationship between the toner and the surface of the fixing endless belt and the surface of the recording paper showing the embodiment of the present invention.

In FIG. 1, reference numeral 1 is a fixing endless belt (fixing member). The fixing endless belt 1 has a release layer 4, or an elastic layer 3 and a release layer 4 in this order on a substrate 2.

The base 2 is (a) stainless steel,
A sheet or an endless belt made of a metal material such as nickel, (b) a sheet or an endless belt made of a heat-resistant resin material such as polyimide, polyamide-imide or fluororesin,
Alternatively, (c) the laminated sheet or endless belt of the above (a) and (b). When the base 2 is made of a metal material, the thickness of the base 2 is 100 in consideration of the bending of the belt.
It is desirable that the thickness is μm or less. Further, the base 2 is
When it is made of heat-resistant resin material, heat capacity (thin is advantageous from the viewpoint of shortening the rise time), and
From the viewpoint of strength (thicker is more advantageous), the film thickness is
A film thickness of 30 to 200 μm is preferable.

The elastic layer 3 has a fixing temperature of 200 ° C.
Therefore, it is made of a heat-resistant synthetic rubber material such as silicone rubber or fluorosilicone rubber, which can withstand heat of about 200 ° C. The elastic layer 3
May be made of a heat-resistant synthetic rubber other than the above, as long as it does not deviate from the object of the present invention. Fixing member,
For example, the surface of the fixing endless belt 1 comes into contact with an unfixed toner image, and the toner is heated and pressed to fix the toner on the recording paper.
If there is unevenness on the surface of the, the contact state between the peak and the valley will be different. Such a difference in the contact state naturally appears in the difference in heat transfer and the pressure on the toner, and as a result, it appears as image unevenness (uneven gloss). The elastic layer 3 of the present invention has an effect of elastically reducing the difference in contact state between the peak and the valley.

The release layer 4 is made of polytetrafluoroethylene copolymer (PTFE), tetrafluoroethylene-polyethylenefluorovinyl ether copolymer (PFA),
It is composed of a fluororesin such as tetrafluoroethylene / hexafluoropropylene copolymer resin (FEP). According to the present invention, since the release layer 4 is made of the fluororesin as described above, the heat resistance, flexibility and toner releasability of the fixing member are excellent. Further, when the elastic layer 3 is covered with the release layer 4, the toner releasability and the prevention of paper dust adhesion can be achieved without using silicone oil (oilless). However, these fluororesins having releasability are
Generally, since it does not have elasticity like a rubber material, when the release layer 4 is formed thick on the elastic layer 3, the uneven gloss occurs as described in the problems of the prior art. Therefore, in order to prevent the uneven glossiness and ensure the releasing property for the toner and the paper powder, it is necessary to form the releasing layer 4 so as not to impair the flexibility of the elastic layer 3. For this purpose, it is necessary that the material of the release layer 4 is as flexible as possible and that the thickness of the release layer 4 is thin. That is, the belt surface is required to be flexible.

In the present invention, the release layer 4 is made of a fluororesin, the center line average roughness Ra of the surface of the release layer 4 is 1 μm or less, and the ten-point average roughness Rz is 2 μm. And the average inclination: θa is 3 ° or less. The "center line average roughness: Ra" is obtained by cutting out a portion having a measurement length L from the roughness curve in the direction of the center line and calculating the arithmetic mean of the absolute values of the deviation between the center line and the roughness curve of the extracted portion. It is the value. The “ten-point average roughness: Rz” is
It is the difference between the average value of the elevations of the 5th to the highest peaks and the average value of the elevations of the 5th deepest valley bottoms with respect to the average line of the portion extracted by the reference length L from the sectional curve. The “average inclination: θa” is the average value of the angle formed by the average line of the portion extracted by the measurement length L from the sectional curve and the sectional curve. As described above, the release layer 4 is made of a fluororesin, and the center line average roughness Ra of the surface of the release layer 4 is
When the average roughness is 10 μm or less, the ten-point average roughness: Rz is 2 μm or less, and the average inclination: θa is 3 ° or less, a smooth surface without cracks is obtained, and the image glossiness, the image gloss unevenness, and the fixing temperature range are reduced. Can be improved.

The fixing member 1 having the elastic layer 3 and the release layer 4 in this order on the substrate 2 having such surface characteristics is manufactured as follows. That is, the surface of the elastic layer 3 formed on the substrate 2 is coated with a fluororesin to form a fluororesin coating layer (4), and then the fluororesin coating layer (4) is melted at least the melting point at least twice. And heat it to
At that time, in the first baking, the surface of the fluororesin coating layer (4) is heated and baked without contacting anything, and
In the second and subsequent heating and baking, the surface of the fluororesin coating layer (4) is heated and baked in a state in which a smooth surface body formed of a material having a heat resistance higher than the melting point of the fluororesin is contacted, Such a heated and baked fluororesin coating layer (4) is removed by removing the smooth surface body and rapidly cooled to a temperature not higher than the crystallization temperature of the fluororesin, or is brought into contact with the smooth surface body until the temperature falls to the crystallization temperature. The mold release layer 4 is formed by cooling while leaving it. The fixing member 1 having the release layer 4 on the substrate 2 of the present invention is manufactured in the same manner as the above manufacturing method.

The fluororesin is preferably applied to the surface of the elastic layer 3 as a fluororesin dispersion liquid. Fluorine resin coating layer (4) that has been heated and baked for the second time and thereafter
Is rapidly cooled to the crystallization temperature or lower at a cooling rate of 30 ° C./min or higher.

In the above description of the present embodiment, the case where the fixing member is an endless belt has been mainly described, but the fixing member is a sheet (not shown) and a fixing roll (see FIG. 2 below). The case can be similarly described.

As shown in FIG. 2, the fixing roll 11 has an elastic layer 13 and a release layer 14 in this order on a columnar base 12. The base 12 is made of a metal material such as aluminum, stainless steel, or brass and / or a heat resistant resin.

The fixing member according to any one of claims 1 to 3 can be provided in an image forming apparatus as shown in FIGS. The fixing member according to any one of claims 1 to 3 is excellent in heat resistance, flexibility, toner releasability, and durability. It is possible to form a uniform and fixed image stably for a long period of time without causing uneven gloss on the toner surface or unevenness of the image on the OHP unlike the forming device.

[0035]

(Example) (Example 1) Diameter 6 composed of polyimide
A base made of an endless belt having a length of 0 mm, a surface length of 315 mm and a thickness of 90 μm was formed, and a primer was applied to the surface of the base. Silicone rubber mixed with iron oxide to improve heat resistance on a base coated with this primer (JIS
A hardness: 20 degrees) was blade-coated to form an elastic layer having a thickness of 200 μm. After coating the surface of this elastic layer with a primer, a fluororesin (PFA) dispersion liquid was applied to the elastic layer coated with this primer in a thickness of 20 μm to form a fluororesin coating layer. This fluororesin coating layer was heated to 350 ° C. and baked without contacting anything on its surface (1
This time, it was cooled at a cooling rate of 10 ° C./min (hereinafter referred to as “primary processing”). A sheet of polyimide resin (PI) having a smooth surface is arranged on the surface of the fluororesin coating layer that has been subjected to this primary processing, and this is heated to 350 ° C. from the outside in a state of being pressurized with 2 Mpa to give a fluororesin. The coating layer was baked (second time). Then, the second-baked fluororesin-coated layer was cooled at a cooling rate of 20 ° C./min to form a release layer while the sheet was placed, to obtain a fixing member (hereinafter, referred to as a fixing member). , "Secondary processing".).

Example 2 The fluororesin coating layer formed in the same manner as in Example 1 was heated to 350 ° C. without contacting the surface thereof.
It was heated to calcination (first time) and cooled at a cooling rate of 20 ° C./min. A sheet of polyimide resin (PI) having a smooth surface is arranged on the surface of the fluororesin coating layer that has been subjected to this primary processing, and this is heated to 350 ° C. from the outside in a state of being pressurized with 2 Mpa to give a fluororesin. The coating layer was baked (second time). Then, the second-baked fluororesin coating layer was cooled at a cooling rate of 20 ° C./min while forming the sheet to form a release layer, thereby obtaining a fixing member.

Example 3 The fluororesin coating layer formed in the same manner as in Example 1 was heated at 350 ° C. without contacting the surface thereof.
It was heated to calcination (first time) and cooled at a cooling rate of 20 ° C./min. A sheet of polyimide resin (PI) having a smooth surface is arranged on the surface of the fluororesin coating layer that has been subjected to this primary processing, and this is heated to 350 ° C. from the outside in a state of being pressurized with 2 Mpa to give a fluororesin. The coating layer was baked (second time). Then, the second-baked fluororesin coating layer was cooled at a cooling rate of 30 ° C./min to form a release layer while the sheet was placed, to obtain a fixing member.

(Comparative Example 1) A fluororesin coating layer formed in the same manner as in Example 1 was used in a state where nothing was brought into contact with the surface thereof.
A fixing member was obtained by heating at 50 ° C. and firing, and cooling this at a cooling rate of 10 ° C./min to form a release layer.

(Comparative Example 2) A fluororesin coating layer formed in the same manner as in Example 1 was used in a state in which nothing was brought into contact with the surface thereof.
A fixing member was obtained by heating to 50 ° C. and firing, and cooling this at a cooling rate of 20 ° C./min to form a release layer.

(Comparative Example 3) The fluororesin coating layer formed in the same manner as in Example 1 was heated to 350 ° C. without contacting the surface thereof.
The mixture was heated to calcination (first time) and cooled at a cooling rate of 10 ° C./min. Then, the fluororesin coating layer subjected to the primary processing is heated to 350 ° C. and baked without bringing anything into contact with the surface thereof (second time), and this is cooled at a cooling rate of 20 ° C./min. By forming a release layer, a fixing member was obtained.

(Comparative Example 4) The fluororesin coating layer formed in the same manner as in Example 1 was heated to 350 ° C. without any contact with the surface thereof.
The mixture was heated to calcination (first time) and cooled at a cooling rate of 10 ° C./min. A sheet of polyimide resin (PI) having a smooth surface is arranged on the surface of the fluororesin coating layer that has been subjected to this primary processing, and the sheet is heated to 350 ° C. from the outside in a state of being pressurized with 2 Mpa to give a fluororesin. The coating layer was baked (second time). Then, the fluorocarbon resin coating layer that had been baked for the second time was cooled at a cooling rate of 10 ° C./min while forming the sheet to form a release layer, thereby obtaining a fixing member.

(Comparative Example 5) The fluororesin coating layer formed in the same manner as in Example 1 was heated to 350 ° C. without contacting the surface thereof.
It was heated to calcination (first time) and cooled at a cooling rate of 20 ° C./min. Then, the fluororesin coating layer subjected to the primary processing is heated to 350 ° C. and baked without bringing anything into contact with the surface thereof (second time), and this is cooled at a cooling rate of 20 ° C./min. By forming a release layer, a fixing member was obtained.

(Comparative Example 6) The fluororesin coating layer formed in the same manner as in Example 1 was heated to 350 ° C. without contacting the surface thereof.
It was heated to calcination (first time) and cooled at a cooling rate of 20 ° C./min. A sheet of polyimide resin (PI) having a smooth surface is arranged on the surface of the fluororesin coating layer that has been subjected to this primary processing, and this is heated to 350 ° C. from the outside in a state of being pressurized with 2 Mpa to give a fluororesin. The coating layer was baked (second time). Then, the fluorocarbon resin coating layer that had been baked for the second time was cooled at a cooling rate of 10 ° C./min while forming the sheet to form a release layer, thereby obtaining a fixing member.

(Comparative Example 7) The fluororesin coating layer formed in the same manner as in Example 1 was heated to 300 ° C. without contacting the surface thereof.
It was heated to calcination (first time) and cooled at a cooling rate of 20 ° C./min. A sheet of polyimide resin (PI) having a smooth surface is arranged on the surface of the fluororesin coating layer that has been subjected to this primary processing, and this is heated to 350 ° C. from the outside in a state of being pressurized with 2 Mpa to give a fluororesin. The coating layer was baked (second time). Then, the second-baked fluororesin coating layer was cooled at a cooling rate of 30 ° C./min to form a release layer while the sheet was placed, to obtain a fixing member.

(Comparative Example 8) A sheet of polyimide resin (PI) having a smooth surface was placed on the surface of the fluororesin coating layer formed in the same manner as in Example 1, and the outside thereof was pressed under a pressure of 2 MPa. Further, it was heated to 350 ° C. to bake the fluororesin coating layer (first time). A sheet of polyimide resin (PI) having a smooth surface is arranged on the surface of the fluororesin coating layer that has been subjected to this primary processing, and this is heated to 350 ° C. from the outside in a state of being pressurized with 2 Mpa to give a fluororesin. The coating layer was baked (second time). Then, the second-baked fluororesin coating layer was cooled at a cooling rate of 30 ° C./min to form a release layer while the sheet was placed, to obtain a fixing member.

As described above, (1) The belt-shaped fixing members formed in Examples 1 to 3 and Comparative Examples 1 to 8 were baked for the first time (that is, those which were subjected to primary processing) and 2
Regarding the characteristics of the fixing member shown below for the one after the second baking (that is, the one subjected to the secondary processing), the center line average roughness of the surface of the release layer of the fixing member: Ra (μm), ten-point average Roughness: Rz (μm) and average inclination: θa (°) were measured. The roughness of the surface is a roughness meter: a stylus type surface roughness measuring instrument and a surf coder S manufactured by Kosaka Laboratory.
It measured using E-30H. At that time, the measurement length L:
2.5 mm, scanning speed: 0.1 mm / sec, cutoff λc: 0.8 mm, and probe tip curvature radius: 2 μm.

(2) Regarding the belt-shaped fixing members formed in Examples 1 to 3 and Comparative Examples 1 to 8, as the fixing property, image gloss, image gloss unevenness, and fixing temperature range (° C.) ) Were evaluated respectively. The evaluation items were performed by mounting the fixing member on an image forming apparatus manufactured by Ricoh Company and fixing unfixed toner on the recording paper. The evaluation conditions at that time were as follows.

-Toner: Ricoh's oil-less fixing wax-containing toner prototype-Heating roll φ23.4 Al t = 1-Fixing belt φ60 Polyimide 90 μm, Silicone 20
0μm, PFA 20μm Belt tension on one side 3kgf ・ Pressure roll φ40 Tsumi 120μ Silicone t = 1 ・ Fixing roll φ29.5 Sponge t = 8 Straight Asuka C 51Hs Core bar φ14 ・ Linear speed 125mm / s ・ Heater heating roll 770W 350W for pressure roll ・ Drive is pressure roll and fixing roll ・ Load is fixed between 17kgf axis on one side

The "fixing temperature range" is releasability (fixing temperature range = hot offset temperature-cold offset temperature).
Means That is, how the fixing temperature range changes depending on the surface condition of the fixing endless belt. Cold offset is generally a state where toner is not sufficiently fixed on recording paper, and is caused by insufficient melting of toner (low fixing temperature) and insufficient pressure between the endless fixing belt and recording paper. As described above in the image characteristics, when Rz and Ra are large, the heat transfer to the toner and the pressure applied to the toner at the valley portion are low, and the possibility of causing cold offset is high. Hot offset is a phenomenon in which melted toner adheres to and remains on the belt surface, and occurs when the adhesive force between the belt and the toner becomes larger than the cohesive force of the toner (see FIG. 3). When the belt surface material is the same, the larger the contact area with the toner, the greater the adhesive force between the belt and the toner.

The gloss of the image was evaluated based on the following evaluation criteria. ◯: Gloss with no practical problems Δ: Practical use, some lack of gloss ×: Practical use No gloss The uneven glossiness of the image was evaluated based on the following evaluation criteria. ◯: No significant gloss unevenness Δ: Partially satin-like unevenness was generated ×: Occurrence of satin-like unevenness over the entire image The overall evaluation was evaluated based on the following evaluation criteria. Good: Gloss good, gloss unevenness good, and fixing temperature range of 60 ° C. or more are all satisfied. Δ: Satisfies the two conditions of ◯ gloss and uneven gloss ◯, and
The fixing temperature range of 30 ° C. or more is satisfied. Poor: The gloss and the uneven gloss were not satisfied.

The measurement results and evaluations are shown in Table 1 below. In Table 1, the "image gloss" is abbreviated as "gloss", and the "image gloss unevenness" is abbreviated as "gloss unevenness".

[0052]

[Table 1]

From the examples 1 to 3 and the comparative examples 1 to 8, the following was found. That is, Examples 1 to 3 are those which were brought into contact with a smooth surface body, fired and rapidly cooled in the secondary processing. As a result, it became possible to achieve the required characteristics for both the image glossiness and the fixing temperature range, regardless of the characteristics before the secondary processing. Also, the quenching condition is 20 to 30 ° C /
By further quenching to min, it was confirmed that the fixing property was further improved.

On the other hand, Comparative Examples 1 and 2 are those in which only the cooling is gradually cooled or rapidly cooled in the general primary processing, but the required fixing characteristics are insufficient. Comparative Example 3 regardless of the cooling conditions in the primary processing,
In Example 5, rapid cooling without contact was performed, and in Comparative Examples 4 and 6, gradual cooling with contact was performed, but Comparative Examples 3 to 6 cannot satisfy both properties of gloss and fixing temperature range. As shown in Nos. 7 and 8, no matter how much the secondary processing was performed under the same conditions as in Example 3, if the surface property of the primary processing was insufficient,
There is no effect of secondary processing, and in Comparative Example 7, the film forming agent of the dispersion liquid is removed, but since it is not heated above the melting point, minute cracks (gap between PFA powders) remain. However, they cannot be eliminated even by performing secondary processing. In Comparative Example 8, since the volatile component cannot escape because it is in contact with a smooth sheet,
It can be seen that a void is generated and this cannot be eliminated by the secondary processing as in Comparative Example 7.

As described above, it is necessary to make the surface state at least free of cracks before the secondary processing. For that purpose, it is of course necessary to use a material whose thermal expansion is suppressed for the elastic layer, but also pay close attention to the temperature rise profile. Further, in order to reliably remove (volatilize) the film-forming agent at a temperature equal to or lower than the melting point and then raise the temperature above the melting point to melt the fluorine surface, it is necessary to maintain a certain temperature or the like. Also, in the primary processing, the surface should not be covered (contacted) with a sheet so that volatile components can easily escape. The fixing temperature range is 3
Below 0 ° C, the margin is low and there is a practical problem, but
At 60 ° C, the margin is narrow, but it is practical. 60 ° C
The above is desirable.

[0056]

EFFECTS OF THE INVENTION According to the present invention, excellent heat resistance, flexibility, and toner releasability are obtained, and the gloss of the image, uneven gloss of the image and fixing temperature range are improved as a smooth surface without cracks. The fixing member, the manufacturing method thereof, and the image forming apparatus having the fixing member can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view of a fixing endless belt showing an embodiment of the present invention.

FIG. 2 is a sectional view of a fixing roll according to another embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a relationship between the toner and the surface of the fixing endless belt and the surface of the recording paper according to the embodiment of the invention.

FIG. 4 is an explanatory diagram of a conventional electrophotographic image forming apparatus.

FIG. 5 is an explanatory view showing a usage state of a conventional fixing endless belt.

[Explanation of symbols]

1 Fixing endless belt (fixing member) 2 base 3 elastic layer 4 Release layer 11 Fixing roll (fixing member) 12 Base 13 Elastic layer 14 Release layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Minoru Matsuo             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Koji Kamiya             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F term (reference) 2H033 AA09 AA26 AA32 BA11 BA12                       BB03 BB05 BB13 BB14 BB15                       BB26                 3J103 AA02 AA15 AA21 AA51 BA03                       BA41 EA11 EA12 EA20 FA07                       FA20 GA02 GA57 GA58 GA66                       HA03 HA04 HA05 HA12 HA15                       HA20 HA33 HA36 HA37 HA43                       HA53 HA54                 4F100 AB04A AB10A AB16A AB31A                       AK17C AK49A AK50A AN02B                       AR00B AT00A BA02 BA03                       BA10A BA10C DA11 DA16                       DD07C EH46C JK06C JK07B                       JK15C YY00C

Claims (7)

[Claims] 1. In a fixing member having a release layer, or an elastic layer and a release layer on a substrate, the release layer is made of fluororesin, and the center line of the surface of the release layer is used. Average roughness: Ra less than 1 μm, 10-point average roughness: R
A fixing member having z of 2 μm or less and an average inclination: θa of 3 ° or less. 2. The base is (a) stainless steel,
A sheet or an endless belt composed of a metal material such as nickel, (b) a sheet or an endless belt composed of a heat-resistant resin material such as polyimide or polyamide-imide, or (c) the above (a) and (b) The fixing member according to claim 1, which is a laminated sheet or an endless belt. 3. The fixing member according to claim 1, wherein the base is a roll made of a metal material such as aluminum, stainless steel, or brass. 4. A method for manufacturing a fixing member having an elastic layer and a release layer on a substrate in order, wherein a fluororesin is applied to the surface of the elastic layer to form a fluororesin coating layer, and then at least twice. As described above, the fluororesin coating layer is heated to a temperature equal to or higher than the melting point and fired, in which case the first firing is performed without touching the surface of the fluororesin coating layer, and the second and subsequent firings. In the above, the fluororesin coating layer is heated and baked in a state in which a smooth surface body formed of a material having a heat resistance higher than the melting point of the fluororesin is in contact with the surface of the fluororesin coating layer, and then the heat-baked fluororesin is applied. The coating layer is rapidly cooled to the crystallization temperature of the fluororesin or lower by removing the smooth surface body, or by cooling while being in contact with the smooth surface body until the temperature falls to the crystallization temperature, Release layer A method for manufacturing a fixing member, comprising: 5. The method for manufacturing a fixing member according to claim 4, wherein a fluororesin dispersion liquid is applied to the surface of the elastic layer. 6. The fixing member according to claim 4, wherein the fluororesin coating layer which has been heated and fired for the second time and thereafter is rapidly cooled to a crystallization temperature or lower at a cooling rate of 30 ° C./min or higher. Manufacturing method. 7. An image forming apparatus comprising the fixing member according to claim 1. Description: