JPS6226027B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved fixing roller, and in particular to a heated fixing rubber that has excellent durability and does not undergo dimensional changes or distortion when it comes into contact with offset prevention silicone oil. The purpose is to provide rollers.

Conventionally, fixing rubber rollers used in copying machines such as electrophotographic copying machines have been made by forming a silicone rubber layer with relatively high heat resistance to a certain thickness on the outer circumferential surface of a metal shaft (metal roll). It has been known. When such a fixing rubber roller is actually used, silicone oil is supplied to the surface of the roller for the purpose of preventing offset.

However, this supply of silicone oil causes the silicone rubber layer to swell. For example, if the silicone rubber layer swells by 0.5 mm or more on a roller with a diameter of 40 mm, uneven pressure will occur during fixing, resulting in uneven shading on the image or even poor adhesion. is brought about. As a method to solve this disadvantage, silicone oil heated to a temperature of 100 to 200°C is brought into contact with the silicone rubber layer formed on the outer peripheral surface of the metal shaft for 8 to 72 hours. A silicone oil-impregnated fixing rubber roller has been proposed that maintains the required dimensional accuracy by swelling the silicone rubber layer and then polishing the surface of the swollen silicone rubber layer.

The above-mentioned silicone oil-impregnated fixing rubber roller achieves the purpose of preventing offset even without supplying silicone oil initially, and also has the advantage that even when silicone oil is supplied, dimensional changes and distortions are less likely to occur as described above. However, satisfactory results in terms of durability were not obtained.
Furthermore, since the polishing process after impregnation with the silicone oil described above is a laborious process, there is a drawback that the manufacturing cost of the roller increases.

On the other hand, attempts have been made to manufacture fixing rubber rollers using so-called high-temperature curing fluorosilicone rubber, which is cured by heating to a temperature of around 200°C under pressure, but in this case, the swelling change with respect to silicone oil is Although it has the excellent advantage of being small, the outer diameter changes as it needs to be hardened under pressure and heat during molding, and therefore an extremely difficult polishing process is required to achieve the desired size. .

The present invention aims to provide a fixing roller with a new structure that solves the disadvantages and shortcomings of the conventional technology. The present invention relates to a fixing roller provided with.

In manufacturing the fixing roller of the present invention,
Since there is no need to pressurize and heat when forming a room-temperature-curing fluorosilicone rubber layer on a silicone rubber layer, dimensional irregularities do not occur even if the thickness and surface properties of the silicone rubber layer are not uniform. , Therefore, it is possible to omit the step of polishing and finishing. This greatly reduces the manufacturing cost of the fixing roller, and there is no dimensional change or distortion when it comes into contact with the offset prevention silicone oil, so fixing is achieved stably and it has excellent durability. It has the advantage of being

The present invention will be explained in detail based on the drawings.

The drawing shows a schematic cross-sectional structure of a fixing roller 1 and a pressure roller 2 that is in pressure contact with it.
4 is a heating element, 4 is a metal shaft, 5 is a silicone rubber layer formed at a constant thickness on the outer surface of the metal shaft, 6 is a room temperature curable fluorosilicone rubber layer, and 7 is a synthetic resin layer or rubber elastic layer. are shown respectively. The silicone oil for preventing offset is supplied from the container 8 through the felt 9 to the surface of the fixing roller.

In the present invention, the silicone rubber layer 5 is made of a silicone rubber material such as high molecular weight (particularly raw rubber-like) dimethylpolysiloxane, diorganopolysiloxane into which phenyl or vinyl groups are introduced and other groups are methyl groups. Of course, this does not include fluorosilicone rubber. This silicone rubber layer is generally formed by pressurizing and heating curing, but if necessary, it is best to apply a primer (adhesion improver) to the surface of the metal shaft in advance, which will bond the metal shaft surface and the silicone rubber. It is possible to strengthen the adhesion between the layers. The thickness of the silicone rubber layer 5 varies somewhat depending on the size of the fixing roller, but in normal cases it is approximately 0.5~
The thickness may be 6 mm, and it is desirable to select a rubber material composition so that the hardness of the rubber after curing is 30 to 60 degrees in JIS hardness. Note that the dimensions of this silicone rubber layer do not necessarily need to be highly accurate.

Formation of the room-temperature-curing fluorosilicone rubber layer 6 on the silicone rubber layer 5 can be easily carried out without requiring a pressure-heat molding operation, since this fluorosilicone rubber material is a room-temperature curable material. I can do it. This formation method includes, for example, supplying a room temperature curable fluorosilicone composition onto the silicone rubber layer 5 formed to a constant thickness on the outer surface of a metal shaft while rotating the metal shaft using a doctor knife. For example, the gap between the silicone rubber layer and the doctor knife is initially kept small, and as the fluorosilicone rubber is supplied, the gap between the doctor knives is gradually increased, and the doctor knife is fixed at a constant distance from the center line of the metal shaft, and the fluorosilicone rubber layer is A method may be used in which the outer circumferential diameter of the layer is made constant.

It is disadvantageous to make the fluorosilicone rubber layer 6 thicker than necessary; it is advantageous to make it as thin as possible in order to maintain surface smoothness and thickness uniformity. However, on the other hand, it is required to have a certain thickness for contact with the silicone oil for preventing offset, so it is desirable that the thickness be approximately 20 to 500 .mu.m, particularly 50 to 500 .mu.m.

In the room-temperature-curing fluorosicone rubber of the present invention, both ends of the molecular chain are blocked with hydroxyl groups, and the main chain has the following siloxane unit structural formula: T: trifluoropropyl group, R: alkyl group such as methyl group or ethyl group, or aryl group such as phenyl group, m, n: indicates the molar ratio of each siloxane unit, m
When +n is 100 mol%, m is 30 to 100
mol%, especially 50 to 100 mol%, and a crosslinking selected from the main component and triacetoxysilane or trialkoxysilane, other trifunctional silanes, or partially hydrolyzed condensates thereof. It is obtained by using a room-temperature curable fluorosilicone rubber composition comprising a condensation catalyst such as a metal salt of an organic acid, and a condensation catalyst such as a metal salt of an organic acid. If triacetoxysilane or a partially hydrolyzed condensate thereof is used as the crosslinking agent, this composition will be condensed and cured by acetic acid removal reaction, or a triacetoxysilane (generally triethoxysilane) or a partially hydrolyzed condensate thereof will be cured. If used, condensation hardening occurs through dealcoholization reaction. Furthermore, depending on the type of crosslinking agent, condensation curing is performed by a deoxime reaction or a deketone reaction. In the present invention, a composition of the type that undergoes an acetic acid removal reaction is preferable because it forms a fluorosilicone rubber layer that firmly adheres and hardens to the surface of the silicone rubber layer 5 and is stable against swelling by silicone oil. In this case, the adhesive effect of the base component having the above-mentioned siloxane unit structural formula is sufficient if the value of m is 30 mol% or more, but it is particularly preferable that the m value is 50 mol% or more, and the thickness of the layer to be formed is It is desirable that the thickness is 50 μm or more.

On the other hand, the synthetic resin layer or rubber elastic layer 7 of the pressure roller 2 may be made of general synthetic resin or rubber and is not particularly limited, but it is preferably made of polytetrafluoroethylene or silicone rubber from the viewpoint of heat resistance, durability, etc. This is desirable. Of course, this may have the same configuration as the fixing roller.

The fixing roller of the present invention has the advantage of being inexpensive because it is easily manufactured without the need for immersion in silicone oil for a long period of time and polishing in the manufacturing process as in the conventional manufacturing process. The fluorosilicone rubber layer 6 of this fixing roller has excellent swelling resistance against offset prevention silicone oil, so there is no dimensional change or distortion during use, and the roller has excellent properties. It is something.

[Brief explanation of the drawing]

The drawings schematically show a cross-sectional structure of a fixing roller of the present invention and a pressure roller that comes into pressure contact with the fixing roller. 1... Fixing roller, 2... Pressure roller, 3
...Heating element, 4...Metal shaft, 5...Silicone rubber layer, 6...Fluorosilicone rubber layer,
7...Synthetic resin layer or rubber elastic layer.

Claims (1)

[Claims] 1. A fixing roller comprising a cured coating layer of room temperature curing fluorosilicone rubber on the outer peripheral surface of a metal roll with a silicone rubber layer interposed therebetween.