JPH0314350B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is applicable to an electrophotographic copying machine, a facsimile machine,
This relates to fixing devices used in devices that use electrophotographic processes, such as printers. [Prior Art] Conventionally, in copying machines and the like that utilize an electrophotographic process, it is necessary to fix an unfixed toner image formed on paper to make a permanent image. Fixing methods, heat fixing methods, and the like are known. However, the above solvent fixing method causes solvent vapor to scatter,
It has many disadvantages such as odor and hygiene problems,
On the other hand, the pressure fixing method also has disadvantages in that its fixing properties are poor compared to other fixing methods, and the pressure-adaptive toner is expensive, both of which are not widely put into practical use. Therefore, for fixing unfixed toner images, a heat fixing method is generally used in which the toner is melted by heating and adhered to the paper. As shown in FIG. 2, this fixing device has a heater b disposed inside a cylindrical core metal a, and a heat-resistant resin such as polytetrafluoroethylene or HTV silicone on the surface of the core metal a. Rubber (High Temperature Vulcanization)
Silicone Rubber), RTV Silicone Rubber (Room Temperature Vulcanization Silicone
A heat-fixing roll d on which a coating layer c made of a heat-resistant elastic material such as
HTV silicone rubber, LTV silicone rubber (Low Temperature Vulcani−zation Silicone
Rubber), RTV silicone rubber, fluoro rubber,
EPDM rubber (Ethylene Propylene Diene
A heat roll method in which a sheet h on which an unfixed toner image has been formed is inserted between these rolls d and g for fixing. This device is the most widely used because it is superior in fixing performance, fixing speed, safety, and economy compared to other heat fixing methods such as flash fixing or oven fixing. has been done. [Problems to be Solved by the Invention] However, in the conventional fixing device that uses a heat-resistant resin as the coating layer c of the heat fixing roll d, the toner image fixed by this device does not have gloss. However, there was a problem in that the reflected light made the fixed image difficult to read. That is, the heat fixing roll d coated with a heat-resistant resin such as polytetrafluoroethylene is usually coated on the core metal a in a state in which the resin is heated and melted, and the coated surface is subjected to a buffing process or the like. Since the surface of the coating layer c is smooth and has no elasticity, the paper h
This is because the upper unfixed toner image is crushed by the heat fixing roll d, and its surface becomes smooth, resulting in a glossy appearance. In contrast, in conventional fixing devices that use a heat-resistant elastic material such as HTV silicone rubber as the coating layer c of the heat-fixing roll d, the coating layer c has many fine irregularities on its surface and has elasticity. Since the unfixed toner image on the paper h is not crushed during heat fixing, there is no problem mentioned above that the fixed image becomes difficult to read. It has less abrasion resistance than synthetic resins, and the paper peeling claw i or temperature sensor j disposed around the paper h and heat fixing roll d.
Since it is easily abraded by contact with objects such as the like, there is a problem in that it causes poor fixing even when used for a short period of time. Furthermore, the heat-resistant elastic material has a property of being easily swollen by the release agent for toner offset prevention applied to the surface of the heat fixing roll d, so when this release agent is used, the coating layer c is There is a problem that even if used for a short period of time, the paper h will be deformed and wrinkles will occur.On the other hand, if a release agent is not used, some of the toner on the paper h will be absorbed into the unevenness of the coating layer c. There are disadvantages such as adhesion to the paper h and deterioration of the peelability of the paper h from the heat fixing roll d, or causing the above-mentioned toner offset. However, there were some problems that made it more troublesome than other fixing devices. The present invention has been made in view of the above-mentioned problems.The present invention is based on a fixing device equipped with a heat fixing roll coated with a heat-resistant resin, and the toner image after fixing does not have gloss. It is an object of the present invention to provide a fixing device that does not emit light and can maintain this fixed state for a long period of time. [Means for Solving the Problems] That is, the present invention includes a heat fixing roll and a pressure roll that rotate while being pressed against each other, and a sheet on which an unfixed toner image is formed is inserted between these rolls to fix the unfixed toner image. Assuming a fixing device for fixing a toner image, the heat fixing roll is composed of a cylindrical core metal and a fluorine-based heat shrinkable tube that covers the outer peripheral surface of the cylindrical core metal via an adhesive, Moreover, the surface of this fluorine-based heat-shrinkable tube is roughened to a ten-point average roughness of 2 μmRz to 30 μmRz. [Operation] According to the technical means described above, even if an unfixed toner image on a sheet is crushed by a heat fixing roll during heat fixing, the fixed image is fixed with its surface roughened. does not produce gloss, and due to the hardness of the fluorine-based heat-shrinkable tube, the roughness of the heat-fixing roll surface is difficult to change even if it comes into contact with sheets or peeling nails many times, so this product can be used for a long period of time. It becomes possible to maintain the fixed state. [Example] Examples of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the fixing device of the present invention is composed of a heat fixing roll 1 and a pressure roll 2. be. First, as shown in FIG. 1, the heat fixing roll 1 includes a cylindrical core 3 that is rotatably supported in the direction of arrow A, and a PFA resin that coats the surface of the core 3 with an adhesive 4. (Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) fluorine-based heat shrinkable tube 5, and a heater 6 is disposed within the core bar 3. On the other hand, the pressure roll 2 is provided below the heat-fixing roll 1, and like the heat-fixing roll 1, it covers a cylindrical core bar 7 and the surface of the core bar 7.
The heat-resistant elastic layer 8 is made of HTV silicone rubber, etc., and is supported on a bearing so that it can rotate in the direction of arrow B as the heat-fixing roll 1 rotates. , appropriate pressure is applied by a mechanism not shown. The surface of the fluorine-based heat-shrinkable tube 5 of the heat-fixing roll 1 is roughened to a ten-point average roughness of 2 μmRz by blasting with Alundum. In FIG. 1, 9 and 10 are the heat fixing rolls 1.
11 shows a paper sheet on which an unfixed toner image has been formed, and 12 shows a paper peeling claw provided on the roll 1 and a temperature sensor for detecting the temperature on the surface of the roll 1. 1,2
A paper guide is shown to be inserted between the two. Next, in order to fix the toner using the fixing device of the present invention, as shown in FIG. As a result, the toner is melted and poured into the fibers of the paper 11, cooled, and fixed. At this time, even if the unfixed toner image on the paper 11 is crushed by the heat fixing roll 1, the fixed image will not be glossy because it will be fixed with its surface roughened. Moreover, the fluorine-based heat-shrinkable tube 5 is hard and the surface roughness does not change even if it is brought into contact with the paper 11 many times, so that the above-mentioned good fixing state can be maintained for a long period of time. Here, the fixing device of the present invention, a conventional fixing device using a heat fixing roll coated with a heat-resistant resin, and a fixing device using a heat fixing roll coated with a heat-resistant elastic material were used, respectively. The surface roughness of the heat-fixing roll, the glossiness of the fixed image fixed by each fixing device, and the number of sheets of paper that can be inserted to maintain the initial fixing state (gloss) of each fixing device, that is, the lifespan of the heat-fixing roll. We conducted a comparative experiment for comparison. The heat fixing roll in the fixing device () of the present invention has an alundum mesh, a spray pressure,
These results were obtained by changing the blasting conditions such as spraying time. In addition, the heat fixing roll in a conventional fixing device using heat-resistant resin is obtained by coating the core metal surface with heated and melted PFA resin, and then blasting the surface to a ten-point average roughness of 1.5 μmRz. On the other hand, the heating fixing roll in a conventional fixing device using a heat-resistant elastic material is obtained by coating the surface of a core bar with RTV silicone rubber. Furthermore, the glossiness of the fixed image was evaluated by the reflectance of light, and the life of the heat fixing roll was evaluated by the total number of sheets of paper inserted when the initial fixing state could no longer be maintained. As a result, the measured values shown in Table 1 below were obtained.

〔Effect of the invention〕

According to the present invention, even if an unfixed toner image on a sheet is crushed by a heat fixing roll during heat fixing, the fixed image is fixed with its surface roughened, so that the fixed image does not become glossy. Furthermore, due to the hardness of the fluorine-based heat-shrinkable tube, the roughness of the surface of the heat-fixing roll does not change easily even if it is brought into contact with sheets or peeling claws many times, making it possible to maintain this fixed state for a long period of time. becomes. Therefore, a good toner fixation state without glossiness can be maintained for a long period of time, which has the effect of facilitating maintenance and management.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an explanatory sectional view of a fixing device of the present invention, and FIG. 2 is an explanatory sectional view of a conventional fixing device. Description of symbols, 1... Heat fixing roll, 2... Pressure roll, 3, 7... Core bar, 4... Adhesive, 5...
Fluorine-based heat shrink tube, 6... Heater, 8...
Heat-resistant elastic body, 9...Paper peeling claw, 10...Temperature sensor, 11...Paper, 12...Paper guide.

Claims (1)

[Scope of Claims] 1. A heat fixing roll and a pressure roll that rotate while being pressed against each other are provided, and a sheet on which an unfixed toner image is formed is inserted between these rolls to fix the unfixed toner image. In the fixing device, the heating fixing roll is composed of a cylindrical core metal and a fluorine-based heat-shrinkable tube that covers the outer peripheral surface of the cylindrical core metal via an adhesive, and the fluorine-based heat-shrinkable tube A fixing device characterized in that the surface of the fixing device is roughened to a ten-point average roughness of 2 μmRz to 30 μmRz.