JPS5822184Y2 - Pressure roll for electrophotography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a pressure roll used in the fixing process of an electrophotographic copying device, and more specifically, to an improvement in a pressure roll used in a heat-pressure fixing device using an anti-offset liquid.

A conventionally known heating and pressure fixing device is shown in FIG.

The main parts of this device are a heating roll 1 and a pressure roll 2. The pressure between these rolls and the heat of the heating roll are used to transfer thermoplastic resin powder (hereinafter referred to as toner) of an unfixed image onto the paper. to complete the fixing.

In this fixing process, silicone oil or the like is used as an anti-offset liquid to prevent toner from adhering to the rolls, and the surfaces of the heating roll 1 and the pressure roll 2 are wetted.

The heating roll 1 includes a heating element 3 inside a metal support tube 5, and the surface of the metal support tube is coated with a non-adhesive resin.

As shown in FIGS. 1 and 2, the pressure roll 2 is made by vulcanizing and molding a heat-resistant and elastic deformable material 7 (hereinafter referred to as mold rubber) on a metal support shaft 6 (hereinafter referred to as roll core). Then, a thin-walled tube 8 made of non-adhesive resin (hereinafter referred to as sleeve) is placed over the surface of the molded rubber, and the molded rubber 7 is
It has a structure in which a sleeve (for example, a silicone rubber material) is bonded with an adhesive.

Both ends of this molded rubber 7 are made of oil-resistant deformable material.
A ring seal 14 made of, for example, silicone fluoride is provided, and the molded rubber surface of the ring seal 14 is bonded to the inner surface of the sleeve with an adhesive.

Furthermore, both ends of the ring seal are pressed together with metal fixing rings 15 and fixed with circlips 16.

The anti-offset liquid is co-supplied through the supply felt 9;
It flows from the surface of the heating roll 1 to the surface of the sleeve 8 of the pressure roll 2 that is in contact with the heating roll, and further flows from both ends of the sleeve to the cylinder roll 14, penetrates into the ring seal and swells it, and causes the mold to swell. The adhesive part between the rubber 7 and the ring seal swells and the adhesive part peels off, and the anti-offset liquid eventually penetrates into the mold rubber, causing the mold rubber to swell and reduce its hardness, and also causing the mold rubber and sleeve 8 to become damaged. and peels off.

For this reason, the pressure distribution and nip width between the pressure roll 2 and the heating roll 1 become uneven, resulting in problems such as poor fixing and paper wrinkles.

Further, during normal fixing, the pressure roll is subjected to pressure and heat, so that the mold rubber and the rubber of the ring seal undergo elastic deformation.

Further, the rubber expands due to heating and its hardness decreases, and in particular, the ring seal exhibits elastic deformation in the form of a convex bulge on the outside of the roll, as shown in FIG.

Furthermore, if the fixing ring 15 is rotated in this deformed state, the sides or corners of the fixing ring 15 will come into contact with the elastically deformed parts of the ring seal, causing wear and cracks, which can cause serious problems such as the offset prevention liquid penetrating through the cracks. This will result in defects.

Therefore, the conventionally used ring seals disclosed in Japanese Patent Publication No. 47-20747 and Japanese Patent Application Laid-Open No. 52-7736 have the disadvantage that they cannot withstand long-term use.

In order to eliminate these drawbacks of conventional pressure rolls, the present invention has developed a deformable material (hereinafter referred to as oil seal) that prevents offset prevention liquid from penetrating into both ends of the pressure roll.
is provided on the outside of the ring seal 14 shown in FIG. 2 without being joined to the ring seal to eliminate cracks in the ring seal, and this oil seal prevents the anti-offset liquid from penetrating from both ends of the pressure roll. This is how it was done.

Improved portions of a typical example of the pressure roll of the present invention are shown in FIGS. 4 and 5.

This pressure roll has oil seals 17 a at both ends thereof.
, 17b are provided, and the oil seal and the ring seal 14 are not bonded with adhesive or the like, but if possible, it is better to maintain the interval between them for better results.

This interval is determined based on the material of the oil seal and ring seal, the difference in physical properties such as hardness, the thickness and flexibility of the oil seal, and the amount of deformation caused by the pressure of the pressure roll, especially when the ring seal deforms into a convex shape. It is necessary to consider and decide.

When the ring seal and the oil seal are fully or partially adhered, stress (force in the direction parallel to the roll axis caused by the seal ring deforming into a convex shape) will be applied to the adhesive area between the oil seal and the sleeve 8 or the adhesive area between the oil seal and the roll core 6. ), there is a risk that the oil seal will peel off, and its life will be shortened, so joining is avoided in the present invention.

The material of the oil seals 17a and 17b is preferably oil-resistant and non-swellable to the anti-offset liquid, such as rubber-based materials such as fluororubber, acrylic rubber, EPDM rubber, polyurethane, polyethylene, polypropylene, and fluorine-based resins. A resin film such as the following can be used.

In addition, when using oil-resistant rubber or resin film, or general rubber or resin film, the surface of the oil seal may be coated to improve non-swelling properties and oil resistance [for example, the product Meiko Muralon (Nippon Acheson Co., Ltd.)] It is preferable to use a material in which a non-swellable thin sheet (for example, the above-mentioned resin film or metal foil) is applied to both or one side of the oil seal to form a laminate layer.

The oil seal 17a maintains the shape shown in FIG. 4 under no load, and can deform into any shape (for example, the state shown by the dotted line in FIG. 4) when pressurized or rotated under pressure and heating conditions.

In addition, even if the oil seal material is molded into the shape shown in Figure 5 under no load, the oil seal can deform into any shape during pressurized rotation, further extending the life of the oil seal. became.

Even if the improved pressure roll manufactured using the oil seals 7a and 7b of the present invention is used for a long period of time, the ring seal 14 and molded rubber 7 do not contain anti-offset liquid (for example, K).
No penetration of F96 silicone oil (viscosity: 100 centistocous) was observed, eliminating the drawbacks of conventional pressure rolls.

As a result, instead of using oil-resistant, non-swellable fluorinated silicone rubber as the ring seal material, it is possible to use general heat-resistant rubber, which means that the same type of material as the mold rubber (for example, silicone rubber) can be used. became.

Therefore, the material and hardness of the ring seal 14 used to maintain uniformity of the nip width and pressure formed between the pressure roll and the heating roll can now be freely selected.

Furthermore, by providing the oil seal of the present invention, the ring seal 14 could be omitted if a long pressure roll was used.

Example 1 A roll core 6 made of carbon steel (530C) is made, and heat vulcanization type silicone rubber (hardness 35 degrees after vulcanization) is used as the mold rubber material, and the roll core 6 is vulcanized and molded to form a rubber roll. was produced.

Non-glue seals 14 made of silicone rubber having a hardness of 50° were bonded to both end sides of the rubber roll with an adhesive, and the surface of the rubber roll was ground.

On the other hand, non-adhesive resin tube (PFA heat shrink tube, DuPont Teflon heat shrink tube, thickness Q, 5 mm)
A pressure roll having a structure similar to the conventional pressure roll 2 was manufactured by covering the rubber roll with an etched inner surface, and bonding the tube and the surface of the rubber roll with adhesive while heat-shrinking the PFA tube. did.

Both ends of the pressure roll 2 are made of EPDM (ethylene propylene copolymer rubber) material with a thickness of Q, 7 mm and a hardness of 65 degrees.
An improved pressure roll was manufactured in which the oil seal 17a was joined to the inner surface of the PFA tube and the roll core instead of being joined to the molded rubber as shown in FIG.

When pressure was applied to this improved pressure roll, the oil seal deformed freely.

Furthermore, when this pressure roll is attached to the conventional heating and pressure fixing device shown in FIG. No penetration of silicone oil into the ring seal or mold rubber was observed.

Therefore, even if used for a long time, the ring seal and molded rubber will not deteriorate in hardness or peel off the adhesive from the sleeve, there will be no friction between the ring seal and the fixing ring 15, there will be no cracks in the ring seal, and the pressure roll will not deteriorate. The required uniform pressure and nip width could always be maintained.

When tested over a long period of time, the lifespan was more than three times that of conventional pressure rolls, and the drawbacks of conventional pressure rolls were eliminated.

Example 2゜An oil seal 17b having the shape shown in Fig. 5 is made from nitrile rubber in the same manner as in Example 1, and one side (outer side) of the oil seal is treated with Emlaron to form an improved pressure roll similar to that in Example 1. When we made a similar test, good results were obtained.

Fluorinated silicone, which is a conventional ring seal material, has the problem of poor adhesion and quick fatigue under repeated compression.

By using the oil seal of the present invention, it is possible to arbitrarily select a material (for example, silicone rubber) that has strong mechanical and physical strength and good adhesive properties as the material for the ring seal 14.

Furthermore, by increasing the hardness of the ring seal 14 compared to the conventional one, the fixing ring 15 is no longer necessary, and as a result,
There is no longer any friction between the ring seal and the fixing ring.

[Brief explanation of the drawing]

FIG. 1 is a lateral cross-sectional view of a roll schematically showing a conventional heat-pressure fixing device, and FIG. 2 is a partial axial cross-sectional view of the conventional pressure roll in an unloaded state. FIG. 3 is an axial cross-sectional view of a conventional pressure roll under pressure. 4 and 5 are partial axial sectional views showing an embodiment of the pressure roll according to the present invention. Codes in the figure 1... Heating roll, 2...
Pressure roll, 3...Heater, 4...
Non-adhesive resin layer, 5...Metal support tube, 6...
...Metal support shaft, 7...Mold rubber, 8.
...Non-adhesive resin pipe, 9 ...Offset prevention liquid supply felt, 10 ...Offset prevention liquid container, 11 ...Cleaning felt, 12
...Paper release finger, 13...Unfixed paper, 14...Ring seal, 15...
...Fixing metal ring, 16... Circlip, 17 a, 17 b... Oil seal, 1
8... Improved pressure roll, 19... Paper feed belt, 20... Arrow indicating the pressure direction.

Claims (1)

[Scope of utility model registration request] 1. In a pressure roll for an electrophotographic fixing device having a metal support tube, a cylindrical molded rubber surrounding the tube, and a non-adhesive resin tube surrounding the molded rubber, if necessary, both ends of the molded rubber, the metal support tube and the non-adhesive resin tube are attached. A ring seal is attached to the inner surface of the adhesive resin, and a deformable material is attached to both ends of the mold rubber, or to the outside of the ring seal, but not to the ends of the mold rubber or the ring seal, but to the metal support tube and the non-adhesive resin surface. A pressure roll characterized by being provided with an oil seal consisting of. 2. The pressure roll according to claim 1, wherein the oil seal is made of an oil-resistant, non-swelling elastic material. 3. The pressure roll according to claim 1, wherein the oil seal is made of a material treated with an oil-resistant coating agent on both or one side thereof. 4. The pressure roll according to claim 1, wherein the oil seal is made of a material laminated with an oil-resistant film or metal foil on both or one side thereof.