JPH06344470A - Production of multilayered roller - Google Patents

Abstract

PURPOSE:To produce a multilayered roller excellent in durability and thermal responsiveness and adaptable to a high speed copier. CONSTITUTION:A coating soln. prepared by adding an equal amt. mixture of a carbon type surfactant and a fluorine type surfactant to a fluoroplastic dispersion is applied to the elastomer layer 3 formed on a core metal 2. This coating soln. is enhanced in film forming properties and can be thinly applied and the mechanical strength of the formed fluoroplastic layer 4 is markedly enhanced in mechanical strength. By this constitution, the fluoroplastic layer 4 is thin and the obtained multilayered roller is enhanced in thermal responsiveness and can be adapted to a high speed copier.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multi-layer roller used in a laser printer, an electronic copying machine or the like, and more particularly to a method for manufacturing a multi-layer roller used in a toner fixing portion.

[0002]

2. Description of the Related Art Conventionally, a toner fixing section of an electronic copying machine or a laser printer is composed of a heating roller having a heater inside and a pressure roller, and presses copy paper on which toner is transferred with the heating roller. While passing between the rollers, the heating roller heats and melts the toner, and the pressure roller presses the toner onto the copy paper to fix the toner on the copy paper for printing. The roller of the fixing unit is required to have appropriate elasticity and good releasability from the toner in order to stabilize the sheet passing and obtain a clear image.
In addition, downsizing and speeding up have become a problem with the demands for speeding up and downsizing of electronic copying machines and laser printers equipped with fixing section rollers. Therefore, in order to obtain a roller with low hardness that can secure the nip width, smooth surface, good paper-passing property, and excellent durability that does not easily wear, an elastic body with appropriate elasticity is provided on the core metal, and the upper layer A roller having a multi-layer structure in which the outermost layer having good releasability from the toner is laminated is used.

Since the roller having such a multi-layer structure is heated to a considerably high temperature, it must have heat resistance and good thermal conductivity. Silicone rubber or fluororubber is used as an elastic body, and the outermost layer is used. As such, a fluororesin such as a perfluoroalkoxy resin (PFA resin) or a polytetrafluoroethylene resin (PTFE resin) is adopted. In order to manufacture a multi-layered roller, the outermost fluororesin is molded into a tube in advance, and an elastic body of silicone rubber or the like with which a desired nip width is obtained is formed on the tube and inserted into the tube. Alternatively, the liquid rubber is injected into the gap between the tube attached to the inner wall of the mold and the core metal arranged coaxially with the mold, and then the mold is heated to cure the liquid rubber and the tube and the elastic body. The tube-coated roller was manufactured integrally.

As another method, there is a method in which an elastic layer is formed on a cored bar, ground, and then coated with a dispersion of fluororesin and baked to form the elastic layer.

[0005]

However, when a roller is manufactured using a fluororesin tube formed in advance, it is difficult to form the tube thinly, for example, to 30 μm or less, and to form it uniformly and stably. there were. For this reason, the roller using a thick tube has a poor thermal response and cannot be used for a high image quality and high-speed machine that requires thermal response.

Further, when the fluororesin layer is formed by coating and baking, the film thickness can be made thin, but there is a drawback that mechanical strength is poor, durability is poor, and the life of the roller is shortened. It was The present invention has been made in order to solve the above-mentioned drawbacks, and a multi-layer roller having a fluororesin layer that can be uniformly formed with good film-forming property and has mechanical strength and has a long life is provided. It is intended to provide a manufacturing method.

[0007]

In order to achieve the above object, a method for manufacturing a multi-layer roller of the present invention is such that a dispersion containing a fluororesin is applied to an elastic layer formed on a cored bar and baked. When the surface layer is provided by applying the surfactant, a surfactant having a critical micelle concentration or more is added to the dispersion of the fluororesin to apply it to the elastic layer.

[0008]

[Function] When forming a surface layer containing a fluororesin, if a dispersion of the fluororesin contains a surfactant in a concentration higher than the critical micelle concentration, it can be applied to a thin fluororesin film and has a uniform thickness. Can be formed with
The coating property can be improved. When the thinly applied fluororesin is baked to form the fluororesin layer, the mechanical strength of the fluororesin layer is significantly improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the method for manufacturing a multi-layer roller according to the present invention is applied to a method for manufacturing a pressure roller for a fixing roller of an electronic copying machine will be described with reference to the drawings. As shown in FIG. 1, a pressure roller 1 which is a multi-layer roller formed by the method for manufacturing a multi-layer roller of the present invention has a core metal 2 on which an elastic layer 3 and a surface fluororesin layer 4 are adhered. It is an integrated one.

The cored bar 2 is made of a material having good adhesion to the elastic layer 3,
For example, it is formed of iron, aluminum, or the like. The elastic layer 3 formed on the cored bar 2 is preferably one that is less likely to be deteriorated by heat and has appropriate elasticity so as to satisfy the paper passing property, and silicone rubber, fluororubber or the like is used.
Silicone rubber is used because it is less likely to be deteriorated by heat. It is preferable that the elastic layer 3 does not contain oil in order to improve the adhesion with the upper fluororesin layer 4. The elastic layer 3 may have semiconductivity in order to improve the releasability of the toner. Carbon black or the like is appropriately added in order to make it semiconductive. In addition, the elastic layer 3
Other fillers may be added to the. In order to form the elastic body layer 3, it can be formed by a known method such as winding a sheet-shaped one in advance around the cored bar 2 via a primer and heating and curing. The elastic layer 3 has a hardness of 50 to 70 (JIS-
A), preferably formed to have a thickness of 0.1 to 2 mm.

Further, the fluororesin layer 4 as the surface layer is preferably one which is less deteriorated by heat, has an excellent releasability from the toner, and has a small friction coefficient, such as a polyfluoroalkoxy resin (PFA resin) or a polytetrafluoroethylene resin. (PT
FE resin) and the like are preferable. To form the fluororesin layer 4, a dispersion containing 60% by weight of fluororesin is used. A surfactant is added to such a fluororesin dispersion in a concentration of at least the critical micelle concentration. When the surfactant is added to the fluororesin dispersion at a critical micelle concentration or more, the surface tension of the dispersion is lowered and the film forming property of the coating film is improved. Therefore, the fluororesin layer can be applied thinly and uniformly. The relationship between the amount of surfactant added and the surface tension is shown in FIG. When the surfactant is added at a concentration above the critical micelle concentration, the surface tension becomes equilibrium and stabilizes.

When the amount of the surfactant added is less than the critical micelle concentration, the coating property is improved to some extent, but it may crack, and the surfactant is a critical micelle for the dispersion of the fluororesin. It is preferable to add more than the concentration.
The mechanical strength can be remarkably improved by baking the fluororesin film applied by adding a surfactant having a critical micelle concentration or higher. The amount of surfactant added and the film (thickness 20
Table 1 shows the tensile strength and the elongation of (μm).

[0013]

[Table 1]

As can be seen from the tensile strength and elongation shown in Table 1, when the surfactant is added at a concentration higher than the critical micelle concentration,
The physical properties of the film are improved. As the surfactant to be used, it is preferable to use a hydrocarbon-based surfactant and a fluorine-based surfactant in combination. Ammonium perfluorocarboxylic acid salts and the like are used as hydrocarbon-based surfactants, and perfluoroalkyl betaine-type surfactants and the like are used as fluorine-based surfactants. When a hydrocarbon type surfactant and a fluorine type surfactant are mixed and used in a ratio of 1: 1 and used, a critical micelle concentration is reached with a small amount of addition.

After coating, the fluororesin layer 4 is formed by firing. The fluororesin layer 4 preferably has a thickness of 10 to 30 μm. When it is 30 μm or more, the thermal response is poor, and 10 μm
If it is below, the mechanical strength will decrease. In order to manufacture a multilayer roller having such a structure, a primer is applied to a core metal that has been cleaned, degreased and blasted, and carbon black, a silicone rubber containing a softening agent and the like, a fluororubber, etc. are molded into a sheet shape. Wrap things around the core, heat,
Vulcanize to form an elastic layer. Then, it is ground into a cylinder by a cylinder grinder or the like. A mixture of a hydrocarbon type surfactant and a fluorine type surfactant is applied to the fluororesin dispersion. The application method may be any method such as spray coating, dipping, and roller coating.
After coating, it is baked. Firing may be performed at a fluororesin curing temperature after preheating, or without preheating,
You may bake.

Examples will be described below. [Example] A sheet of silicone rubber was prepared, wrapped around a cored bar, heated at 160 ° C for 30 minutes to form an elastic layer, and ground by a cylindrical grinder. Onto this, 1.7 parts and 2.3 parts of 100 parts of PTFE resin dispersion was added a mixture of perfluorocarboxylic acid ammonium salt and perfluoroalkyl betaine type surfactant in a ratio of 1: 1, and a coating solution was prepared. It was made and applied by dipping. Then, it heated at 500 degreeC for 5 minutes, and formed the 20-micrometer-thick fluororesin layer.

The resulting multi-layer roller was mounted on a copying machine, and a paper passing test of A-4 copy paper was performed at a copy speed of 80 sheets / minute. The results are shown in Table 2. As a comparative example, 100 parts of PTFE resin dispersion, ammonium salt of perfluorocarboxylic acid, and perfluoroalkyl betaine-type surfactant were added to the elastic layer prepared in the same manner as in the example of 1 :.
A coating solution prepared by adding 1.0 part of the mixture of 1 and a surfactant was not prepared, was coated by the same method, and was baked to form a fluororesin layer.

The resulting multi-layer roller was mounted on a copying machine, and a paper passing test of A-4 copy paper was conducted at a copy speed of 80 sheets / minute. The results are shown in Table 2.

[0019]

[Table 2]

As is clear from the results, it has been found that the roller prepared by adding the surfactant to the fluororesin in the critical micelle concentration or more has improved mechanical strength and remarkably extended life.

[0021]

As is apparent from the above description, according to the method for producing a multilayer roller of the present invention, the fluororesin layer is prepared by adding the surfactant to the fluororesin dispersion in a concentration equal to or more than the critical micelle concentration. As a result of the improved coating property, the obtained surface layer can be formed thin and the mechanical strength can be remarkably improved. Therefore, a multi-layer roller having good thermal response and excellent durability can be obtained and can be applied to a high-speed electronic copying machine.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a multilayer roller according to a method for manufacturing a multilayer roller of the present invention.

FIG. 2 is a diagram showing the relationship between the amount of surfactant added and the surface tension.

[Explanation of symbols]

 1 ... Multi-layer roller 2 ... Mandrel 3 ... Elastic layer 4 ... Fluorine resin layer (surface layer)

Claims (1)

[Claims] 1. When a dispersion containing a fluororesin is applied onto an elastic layer formed on a cored bar and baked to form a surface layer, a surfactant having a critical micelle concentration or more in the dispersion of the fluororesin. A method for producing a multilayer roller, comprising adding the compound to the elastic layer and coating the elastic layer.