JPH07175358A - Multilayered roller - Google Patents

Abstract

PURPOSE:To extend the life of a multilayer roller of a copying machine. CONSTITUTION:A multilayer tube having two layers of the outer layer 4b containing fluorocarbon resin and an inner layer 4a comprising a resin having a lower melting point than the fluorocarbon resin is formed, into which a core metal 2 with an elastic layer 3 is inserted. Then the roller is heated to a temp. higher than the melting point of the inner layer resin 4a to shrink the tube to tightly adhere to the elastic layer 3. Thereby, good adhesion property with the elastic layer is obtd. even the surface layer consists of fluorocarbon resin, and the fluorocarbon resin layer does not cause peel nor blister even when exposed to high temp. Thereby, a good image can be obtd. for a long time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer roller used in laser printers, electronic copying machines and the like.

[0002]

2. Description of the Related Art Conventionally, an electronic copying machine or a laser printer exposes a photosensitive drum whose surface is uniformly charged through a raw paper and exposes the photosensitive drum by light transmitted through a portion of the raw paper where an image is not formed. By removing the charge, an electrostatic latent image is formed on the photosensitive drum, and the opposite toner is attached to the electrostatic latent image at the developing unit. Then, the copy sheet is passed between the photosensitive drum and the transfer roller charged more strongly than the photosensitive drum in the transfer section, the toner is moved onto the copy sheet, and further, the toner is fixed on the copy sheet in the fixing section. There is.

The toner fixing section of such an electronic copying machine is composed of a heating roller and a pressure roller having a heater inside, and the copy sheet on which the toner is transferred passes between the heating roller and the pressure roller. While the toner is being heated, the toner is heated and melted by the heating roller, and the melted toner is pressed against the copy paper by the pressure roller to fix the toner on the copy paper for printing. The roller of such a fixing unit is required to have heat resistance, moderate elasticity, and good releasability from the toner in order to stabilize the sheet passing and obtain a clear image. Therefore, in order to obtain a roller with low hardness that can secure the nip width, good paper passing property, and excellent durability that does not easily wear, in order to obtain a roller that has appropriate elasticity on the core metal, elasticity containing silicone rubber, fluororubber, etc. Set up the body,
A roller having a multi-layer structure is used in which an outermost layer made of a fluororesin having good releasability from toner is laminated on the upper layer.

In order to manufacture the pressure roller among such fixing rollers, the outermost layer of fluororesin is formed into a tube in advance, and an elastic body such as silicone rubber which gives a desired nip width is cored to the tube. Insert the one formed on the metal, or inject the liquid rubber into the gap between the tube attached to the inner wall of the cylindrical mold and the core metal arranged coaxially with the mold, and then heat the mold, A tube-covered roller is manufactured by curing the liquid rubber and integrating the tube and the elastic body.

Further, as a method of manufacturing a heating roller, an elastic layer is formed on a cored bar, and after grinding, a dispersion of fluororesin is applied and baked to form a surface layer.

[0006]

However, fluororesin, which is excellent in releasability from toner, has poor adhesion to the resin. Especially when the lower layer is an elastic layer containing silicone rubber, a tube-covering roller or coating, No matter what is formed by firing, adhesion with silicone rubber is not sufficient, and peeling or film floating occurs in a severe environment where it is heated to a high temperature, which shortens the life of the roller. There was a drawback.

The present invention has been made to solve the above-mentioned drawbacks, and improves the adhesion between the surface fluororesin layer and the lower elastic layer, so that a good image can be stably obtained for a long time. An object of the present invention is to provide a multi-layer roller that can extend the life.

[0008]

To achieve the above object, a multi-layer roller of the present invention is a multi-layer roller in which an elastic layer and a surface layer are sequentially provided on a core metal, and the surface layer is composed of resins having different melting points. The outermost layer contains a fluororesin.

[0009]

The surface layer provided on the elastic layer of the multi-layer roller is formed into a multi-layer tube with resins having different melting points. The outermost layer of the tube contains a fluororesin. The inside of the tube is formed of a resin having a lower melting point than the fluororesin forming the outermost layer. Therefore, if heated at a temperature equal to or higher than the melting point of the resin inside the tube, only the resin inside the tube is melted and the adhesiveness with each of the surface layer containing the elastic layer and the fluororesin layer is improved, and even in a high temperature environment. No peeling of the surface layer occurs, a good image is obtained for a long time, and the life of the roller is extended.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the multi-layer roller of the present invention is applied to a roller of a fixing portion of an electronic copying machine will be described with reference to the drawings.
As shown in FIG. 1, the fixing roller 1 of the present invention has a core metal 2 on which an elastic layer 3 and an inner layer 4a, and a surface layer 4 including an outermost layer 4b containing a fluororesin are sequentially laminated and integrated. Is.

The core metal 2 is made of a material that is well adhered 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. In particular, silicone rubber is preferably used because it is less likely to deteriorate due to heat and can secure the nip width. Elastic layer 3
In order to improve the adhesion with the tube of the upper layer, those without oil are suitable. In order to form the elastic body layer 3, it may be formed by winding a sheet-shaped product in advance around the cored bar 2 through a primer and heating and curing the cored bar. As another method, a multi-layer tube to be the outer layer is attached to the inner wall of the cylindrical mold,
Liquid silicone rubber or the like may be injected between the cored bar and the multilayer tube arranged coaxially with the mold, and the entire mold may be heated and cured.

The elastic layer 3 preferably has a hardness of 10 to 60,
In order to secure the nip width, it is preferably formed to have a thickness of 2 to 10 mm. Further, the surface layer 4 has good releasability from the toner, has a small friction coefficient, and has heat resistance, and is formed beforehand as a multi-layer tube having at least two layers of the inner layer 4a and the outermost layer 4b. . Therefore, the outermost layer 4b contains a fluororesin having excellent releasability. The inner layer 4a is formed of a resin having a melting point lower than that of the fluororesin, and it is preferable that the difference in melting point is large. The multilayer tube is heat-shrinkable and shrinks when heated to a temperature equal to or higher than the melting point of the inner layer 4a. The shrinkage rate is 10 to 100%, preferably 20 to 80%.

Polyfluoroalkoxy resin (PFA resin) is used as the fluororesin forming the outermost layer 4b.
(Melting point 300 to 310 ° C.) and polytetrafluoroethylene resin (PTFE resin) (melting point 327 ° C.) are suitable. Inner layer 4a formed inside such outermost layer 4b
Is determined by the melting point of the resin forming the outermost layer and the relationship of adhesiveness with the elastic layer, and tetrafluoroethylene-6-fluorinated propylene copolymer resin (FEP resin) (melting point 250 to 2
80 ° C.), ethylene-4-fluoroethylene copolymer resin (ETFE resin) (melting point 270 ° C.) and the like can be used. Such an inner layer has improved adhesiveness even when the elastic layer is made of silicone rubber. Additives can be appropriately added to these outermost layer and inner layer. It is also possible to add a conductive substance such as carbon black to impart conductivity to the roller to prevent the copy paper from being wrapped around.

In order to form a multilayer tube, it may be formed by extruding with a two-layer extruder and then stretching it so as to have a desired diameter and thickness. As the thickness of the surface layer, the thickness of the multilayer tube after shrinkage is 0.05 to 1 mm, and preferably 0.05.
Is about 0.2 mm. When the thickness is large, the thermal response is poor, and when it is thin, the mechanical strength is low. To produce a fixing roller having such a structure, a cored bar is prepared by applying a primer to a cored bar that has been washed, degreased and blasted, and press-molded silicone rubber, fluororubber, etc., to which additives have been appropriately added. Wound around, heated and vulcanized to form an elastic layer, or into a cylindrical mold with a cored bar installed coaxially,
Liquid rubber is injected, heated and vulcanized to form an elastic layer. Then, it is ground into a cylinder by a cylinder grinder or the like. In particular, since the release agent remaining on the surface and unevenness are likely to occur due to the compounding agent, after degreasing the surface with sandpaper, sandblasting, etc., insert it into a multilayer tube and heat it above the melting point of the resin forming the inner layer. The fluororesin tube shrinks and adheres to the elastic layer to be integrated with each other to form a roller.

As another method, the multi-layer tube is mounted in a cylindrical metal mold having an inner diameter smaller than the inner diameter of the multi-layer tube, and a liquid core silicone fixed between the core metal coaxially with the metal mold and the multi-layer tube. Inject rubber, heat each mold,
It may be vulcanized to form a roller. The above description is an explanation of one embodiment of the present invention, the present invention is not limited to this, the multilayer tube is not limited to two layers, and a multilayer tube can be appropriately used as necessary to secure adhesiveness. . Further, not only the fixing roller but also other rollers can be applied.

Examples will be described below. Example 1 A two-layer extruder was used to extrude a PFA resin on the outside to a thickness of 0.05 mm and an FEP resin on the inside to a thickness of 0.03 mm to a diameter of 30 mm by a two-layer extruder, and stretched to a diameter of 40 mm to obtain a multilayer tube. The shrinkage rate of this multilayer tube was 25%.

A sheet of millable silicone rubber is wrapped around a core bar coated with a primer,
After press vulcanization at 30 ° C. for 30 minutes, it was further heated at 200 ° C. for 4 hours. The surface of this was ground with a cylindrical grinder to a thickness of 2 mm and an outer diameter of 38 mm. Then, insert into a multi-layer tube, apply hot air to heat the multi-layer tube surface to 300 ° C,
The multilayer tube was contracted and integrated with the elastic layer to form a roller.

The obtained roller was set as a heating roller of an electronic copying machine, and a paper passing test was conducted at a sheet surface (A4) of 60 sheets / min at a roller surface temperature of 200 ° C. No abnormality occurred even after passing 500,000 sheets. As a comparative example, a PTFE resin is applied on an elastic layer formed in the same manner as in the example and baked,
A surface layer having a thickness of 20 μm was formed.

The obtained roller was set as a heating roller of an electronic copying machine, and a paper passing test was conducted in the same manner. The surface layer peeled off after 220,000 sheets were printed. [Example 2] A core bar coated with a primer was placed coaxially in a cylindrical mold, and liquid silicone rubber was injected,
After vulcanization and curing at 1 ° C for 1 hour, secondary vulcanization was performed at 200 ° C for 4 hours. Silicon rubber has a thickness of 6 mm and an outer diameter of 3
It was 8 mm. Then, it was inserted into a tube prepared in the same manner as in Example 1 and heated in the same manner to prepare a roller.

The obtained roller was set as a pressure roller of an electronic copying machine, and an idle rotation test was conducted at 230 ° C. 130
No abnormality occurred even after 0 hour. As a comparative example, a roller having an elastic layer formed thereon was used as a PFA as in the example.
Insert one tube of resin into the inner surface of which is etched with Na / naphthalene, and heat it in the same manner to obtain a surface layer thickness of 5
A 0 μm roller was created.

The roller thus obtained was set as a pressure roller of an electronic copying machine, and an idle rotation test was conducted in the same manner. The surface layer peeled off after 500 hours. As is clear from the results, in the roller formed by using the multilayer tube for the surface layer, the elastic layer and the surface layer are firmly adhered to each other, and the life of the roller is extended.

[0022]

As is apparent from the above description, according to the multi-layer roller of the present invention, the outermost layer containing the fluororesin as the surface layer and the heat-shrinkable multi-layer of the inner layer having a lower melting point than the fluororesin of the outermost layer Since it is formed in a tube, the surface layer containing the fluororesin and the elastic layer can be adhered to each other by heating the resin above the melting point of the resin in the inner layer. In such a roller, the fluororesin layer and the elastic layer are firmly adhered to each other even under heating, and the fluororesin layer is not peeled off or the film is not lifted.
Therefore, a good image can be stably obtained for a long time, and the life of the roller can be extended.

[Brief description of drawings]

FIG. 1 is a sectional view showing a fixing roller according to an embodiment of the present invention.

[Explanation of symbols]

 1 ... fixing roller (multi-layer roller) 2 ... core metal 3 ... elastic layer 4 ... surface layer (multi-layer tube) 4a inner layer 4b outermost layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area // B29K 27:12

Claims (1)

[Claims] 1. A multi-layer roller having an elastic layer and a surface layer sequentially provided on a core metal, wherein the surface layer is a multi-layer tube made of resins having different melting points, and the outermost layer contains a fluororesin. A multi-layer roller characterized in that