JPS6261085A - Roll for electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To prevent the wrinkling of paper in a fixing part for a long period of time by providing a sponge layer made into two-layered structure having the hardness higher than the hardness of a lower layer on the peripheral face of an arbor. CONSTITUTION:The sponge layer 4 consisting of the upper layer 3 having the hardness higher than the hardness of the lower layer 2 is formed on the peripheral face of the arbor 1 and a surface layer 5 consisting of, for example, silicone rubber is formed on the peripheral face of the sponge layer 4. The material quality of the sponge layer 4 is set at, for example, the silicone rubber and the hardness of the lower layer 2 of the sponge layer 4 is made within a 3-35 range of the numerical value by the spring hardness test specified by Japan Rubber Association Standard SRIS0101-1968. The hardness of the upper layer 3 is set within a 10-45 range. In either case, the hardnesses are so set that the hardness of the upper layer 3 is higher than the hardness of the lower layer 2. The sponge layer 4 made into the two-layered structure in which the hardness of the upper layer 3 is higher than the hardness of the lower layer is used; therefore, a large nip width is obtd. and the wrinkling of the paper in the fixing part of a fixing device is prevented for a long period of time.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a roll for an electrophotographic copying machine.

[Technical background of the invention and its problems]

In recent years, as electrophotographic copying machines have become smaller, the diameter of rollers used in their fixing devices has also become smaller. Therefore, when fixing, the so-called nip width becomes small, causing a problem that sufficient fixing cannot be performed. In order to solve this problem, a roll for electrophotographic copying machines has been developed that uses low hardness rubber and has a wide roll width. Such rolls for electrophotographic copying machines are manufactured by, for example, applying an adhesive to the outer peripheral surface of a core metal, wrapping it with raw rubber, and vulcanizing and foaming this to form a sponge layer. There is. Alternatively, a sponge tube can be made by continuously extruding a rubber tube using an extruder, applying heat to vulcanize and foam the tube, and then inserting a core into the sponge tube. It is being done. In the roll for an electrophotographic copying machine constructed in this manner, the foaming ratio of the sponge layer is increased on the surface side.

When a fixing device assembled using such a roll for an electrophotographic copying machine is used, the surface portion of the sponge layer of the roll is destroyed by continuous heating and compression, resulting in a decrease in hardness.

As a result, paper wrinkles occur in the fixing section of the roll for an electrophotographic copying machine.

If the foaming ratio is lowered to increase the hardness of the sponge layer in order to prevent such wrinkles from forming in the paper, there is a problem in that the nip width cannot be increased and fixing cannot be performed sufficiently.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic copying machine roll that has a large nip width and can prevent paper wrinkles in the fixing section for a long period of time.

[Summary of the invention]

The present invention has a two-layered sponge layer with higher hardness than the lower layer on the circumferential surface of the core bar, which provides a large nip width and prevents paper wrinkles at the fixing section for a long period of time. It is an electrophotographic copier roll that can be used.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic configuration of an embodiment of the present invention. In the figure, 1 is a core metal, and a sponge layer 4 consisting of an upper layer 3 having a higher hardness than a lower layer 2 is formed on its circumferential surface. A surface layer 5 made of silicone rubber, for example, is formed on the circumferential surface of the sponge layer 4. The material of the sponge layer 4 is set to silicone rubber, for example. The hardness of the lower layer 2 of the sponge layer 4 is the Japan Rubber Association standard 5RI.
The value according to the spring hardness test of S 0101-1968 is within the range of 3 to 35, and the hardness of the upper layer 3 is 10 to 45.
The hardness of the upper layer 13 is set to be higher than the hardness of the lower layer 2 in any case. Here, if the hardness of the lower layer 2 is less than 3 or the hardness of the upper layer 3 is less than 10, the predetermined pressure cannot be sufficiently transmitted and the function as a roll is lost. Further, if the hardness of the lower layer 2 exceeds 35 or the hardness of the upper layer 3 exceeds 45, a sufficient nip width cannot be obtained. Further, the sponge layer 4 having such a two-layer structure may be manufactured by wrapping two layers of raw rubber around the circumferential surface of the core bar 1 via an adhesive, and vulcanizing and foaming this. Alternatively, the process may be carried out by making a two-layered sponge tube in advance using an extruder and inserting the core bar 1 into the tube.

According to the roll 10 for an electrophotographic copying machine configured in this way, since the sponge layer 4 has a two-layer structure in which the upper layer 3 has a higher hardness than the lower layer 2, a large nip width can be obtained, and Paper wrinkles can be prevented from occurring in the fixing section of the fixing device for a long period of time.

Next, an example of an experiment conducted to confirm the effects of the present invention will be described.

Experimental Example 1 A sponge raw material made of silicone rubber with a hardness of 20 according to the Japanese Rubber Association Standard 5RIS 0101-1968 (Hardness by hardness test (hereinafter only numerical values are simply written)) was coated with a predetermined adhesive on the circumferential surface. The surface of the core metal 1 with a diameter of 10 mφ is wrapped, and the core metal 1 with a diameter of 19 mmφ is coated with a sponge layer 4 on the surface.
A product was obtained in which the lower layer of the groove was formed. Next, an adhesive T- is applied to the circumferential surface of the lower layer 20, and a sponge material made of silicone rubber with a hardness of 35 is wrapped around the surface, and this is foamed with hot air to form the upper layer 3 and the lower layer 2 on the circumferential surface. A roll having a diameter of 23 m+φ and having a two-layer sponge layer 4 formed thereon was obtained. A lateral surface layer 5 made of silicone rubber was formed on the circumferential surface of the sponge layer 40 thus obtained to obtain a roll 1θ for an electrophotographic copying machine having a diameter of 24 rmφ and having a structure as shown in FIG. 1.

When this roll 10 for an electrophotographic copying machine was used as a fixing roll in an electrostatic copying machine (PC-25 manufactured by Canon Corporation), a sufficiently large nip width was obtained, and approximately 12 sheets could be printed before wrinkles appeared. I was able to make a clear copy of

Actual scent example 2: Using a twin-screw presser, the outer layer has a hardness of 43. Hardness 35 on the inner layer
A sponge tube made of silicone rubber having a
φ×19ioIφ, and the upper layer 3 was formed with a sponge layer 4t consisting of 19φ×251φ. This sponge layer has 4 layers.

The core metal 1 was inserted into the roll and polished to obtain a roll having a diameter of 23 mm. A surface layer 5 made of silicone rubber was formed on the surface of the roll thus obtained, and as shown in FIG.
I got it.

When this roll L for an electrophotographic copying machine was used as a fixing roll of an electrostatic copying machine, a sufficient nip width was obtained.
I was able to make about 155,000 clear copies before the paper wrinkled.

Next, a comparative example conducted to compare the effects of Experimental Example 1.2 above will be described.

Comparative Example A sponge layer made of silicone rubber with a hardness of 35 was extruded and subjected to multiple continuous vulcanization and foaming treatment using hot air to obtain 1mφX25++awφ(D). A core metal 12 was inserted into the roll and polished to obtain a roll having a diameter of 23 mm.

A surface layer 13 made of silicone rubber on the circumferential surface of this roll
A roll 20 for an electrophotographic copying machine as shown in FIG. 2 having a diameter of 24III11φ was obtained. Further, when the hardness of the sponolayer J1 of the obtained roll 20 for an electrophotographic copying machine was examined, as shown in FIG. 3, the hardness was 32.
It was 40 on the core metal side 11b.

When this electrophotographic copying machine roll L was used as a fixing roll in an electrostatic copying machine, paper wrinkles occurred after about 45,000 copies were made.

〔Effect of the invention〕

As described above, the roll for an electrophotographic copying machine according to the present invention has a large nip width and can prevent the occurrence of paper wrinkles in the fixing section for a long period of time.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a schematic configuration of an embodiment of the present invention,
FIG. 2 is an explanatory diagram showing a schematic configuration of a conventional roll for an electrophotographic copying machine, and FIG. 3 is an explanatory diagram showing problems with the conventional roll for an electronic photocopying machine. 1...Core metal, 2...Lower layer, 3...Upper layer, 4...
Sunzo layer, 5... Surface layer, IO... Roll for electrophotographic copying machine.

Claims (1)

[Claims] 1. A roll for an electrophotographic copying machine, comprising a sponge layer on the circumferential surface of a core bar, comprising a lower layer and an upper layer harder than the lower layer, and a surface layer on the surface of the sponge layer.