JPH0797255B2 - Fixing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for an electrophotographic copying machine, and more particularly to a fixing device in which the amount of silicone oil, which is a release agent, is small.

2. Description of the Related Art One example of a conventional electrophotographic copying machine will be described with reference to the schematic configuration diagram of FIG.

The charge receptor 22 having a photoconductive layer formed on an aluminum substrate has a drum shape, and the surface of the charge receptor 22 is uniformly charged by a charging device 21 before image information is irradiated. A document table 11 on which a document 10 to be copied is placed is provided above the document table 11, and a light source 12 for irradiating the document 10 and a charge receptor for reflecting light from the document 10 are provided below the document table 11. An optical system 23 leading to 22 is installed.

Further, the electrostatic latent image formed on the surface of the charge receptor 22 by the exposure step is transferred to the transfer device 14 after being a toner image developed by the developing device 13 installed around the charge receptor 22.
The toner image is transferred onto the paper 16 fed from the paper feeding device 15.

The paper 16 to which the toner image is transferred is discharged by the peeling charging device 17, peeled from the charge acceptor 22 and sent to the fixing device 18, and the fixing device 18 fixes the toner image on the paper 16 to the paper 16. .

On the other hand, the untransferred toner remaining on the surface of the charge receptor 22 after the transfer step is neutralized by the pre-cleaning corotron 19 and then removed from the surface of the charge receptor 22 by the cleaning device 20 to prepare for the next copy cycle.

As a fixing method of a toner image, a heat fixing method, a pressure fixing method, a solvent fixing method and the like are known.

The heat fixing method is a method in which toner is melted by heating and adhered onto a sheet, and is widely used. There are various fixing methods such as a hot air fixing method, an oven fixing method and a heat roll fixing method, but the heat roll fixing method is the most common.

The heat roll fixing method is a method of fixing by applying a constant pressure between a pair of rolls heated at least one of them, and passing a sheet having an unfixed toner image through it, as compared with other heat fixing methods. There are advantages such as low power consumption, high-speed fixing, and low risk of fire due to paper jam at the fixing unit.

As the heating roll of this heat roll fixing device, one whose surface is coated with a heat-resistant release material such as tetrafluoroethylene (trade name: Teflon) or silicone rubber is usually used. On the other hand, as a pressure roll paired with a heating roll to sandwich and pass the paper, one made of a heat resistant elastic body such as silicone rubber or fluororubber in order to have a width at the contact portion when pressure contact is made with the heating roll. It is used.

However, in the heating roll having Teflon as the surface layer, when fixing the toner image on the paper, a part of the toner is transferred to the heating roll, and the trailing edge of the same paper or the next paper There is a drawback in that an offset phenomenon occurs in which the toner is re-transferred and fixed.

Therefore, in order to prevent the occurrence of this offset phenomenon,
Generally, a means for impregnating a release agent such as silicone oil on the surface of at least one roll or supplying it to the surface is used. However, since the heat roll of these silicone oils is heated to around 200 ° C, volatilization (evaporation) of low molecular weight components such as oligomers in the silicone oil occurs, which accelerates the deterioration of the corotron,
It adhered to the platen gas, mirrors, lenses, etc. and caused non-uniformity of the copy image and a decrease in density.

An object of the present invention is to provide a fixing device in which the silicone oil is less likely to volatilize even when the heat roll is heated, and the deterioration of the corotron and the stains on the platen glass, the mirror, etc. are less likely to occur.

Means for Solving the Problems In order to solve the drawbacks of the prior art, the present invention uses a silicone oil from which low-molecular-weight components such as oligomers, which are volatile, are removed.

That is, the present invention uses a silicone oil having a degree of polymerization of 10 or more as a main component, in which a volatile monomer and oligomer components are removed, in a fixing device including a heating roll and a pressure roll and using silicone oil as a release agent. Fixing Device According to Embodiment 1 As one of the embodiments of the fixing device of the present invention, as shown in FIG. 1, a system for supplying silicone oil to the surface of a heating roll and / or a pressure roll is used. There is something.

The fixing device 1 shown in FIG. 1 is provided with a heater inside a cylindrical core metal 2a, and a heat-resistant resin such as polytetrafluoroethylene or HTV silicone rubber (HTV) on the surface of the core metal 2a.
igh Temperature Vulcanization Silicone Rubber), R
TV Silicone Rubber (Room Temperature Vulcanization S
A heating roll 2 having a coating layer 2b made of a heat resistant elastic material such as ilicone Rubber) and a cylinder provided on the surface of the heating roll 2 below the heating roll 2 and having a cylinder on the surface of a core metal 3a, such as HTV silicone rubber and LTV silicone rubber (Low Temperature Vulcanization). Silicon
e Rubber), RTV silicone rubber, fluorine rubber, or other heat-resistant elastic layer 3b is formed on the pressure roll 3, and the wick 5, the oil pan 6, the blade 7 for controlling the amount of oil applied, the oil tank 8, etc. Oil supply device 9
Is placed in the vicinity of the pressure roll 2 and the surface of the pressure roll 1 is continuously coated with silicone oil as a release agent, so that the release agent is applied to the surface of the heating roll contacting the pressure roll. Is supplied to prevent the toner offset phenomenon,
This is a heat roll type device that performs fixing by inserting a sheet 4 on which an unfixed toner image is formed between rolls 2 and 3.

The release agent may be directly supplied to the heating roll 3.

In the present invention, as a release agent, the degree of polymerization of the main component is 10 or more,
Although preferably 20 or more silicone oils are used, such silicone oils include, for example, a method of stripping volatile oligomer and monomer components in a commercially available silicone oil after ethanol extraction, and a method of directly removing by vacuum distillation. It can be easily obtained by

Example 1 In the configuration of FIG. 1, a pressure roll 3 made of fluororesin
In addition, the viscosity of commercially available dimethyl siloxane (viscosity 100CS) was removed by stripping the oligomers and monomers with a polymerization degree of 20 or less to 0.005 wt% or less after ethanol extraction
The heating roll 2 was heated with respect to a device for supplying 100 CS of silicone oil, and the amount of silicone oil lost was examined.

The heating loss of this oil was 0.015 wt% at 180 ° C. for 2 hours. With conventional oil, the loss on heating was 0.093 wt%. When the above-mentioned fixing device according to the present invention and the conventional fixing device using oil are introduced into an electrophotographic copying machine to perform copying, when the conventional fixing device is used, the copy density unevenness is about 30,000 copies. Occurred. At this time, when the corotron wire was observed, a large amount of discharge products had grown,
Oil was attached to the platen glass and the mirror.
On the other hand, when the fixing device according to the present invention was used, good copies were obtained even after copying 50,000 sheets.

The viscosity of the silicone oil used is not limited to 100CS, and 50CS to 500,000CS oil can be used.
Further, the low molecular weight component to be removed is not limited to a polymerization degree of 20 or less, and silicone oil produced by a usual method having an average molecular weight or less can be targeted for removal.

Embodiment 2 As another embodiment of the fixing device of the present invention, a silicone rubber roll constituting a heating roll or a pressure roll is immersed or kneaded to contain a silicone oil having a polymerization degree of 20 or more as a main component. There is a device.

The structure of this device is the same as that of the embodiment shown in FIG.

Example 2 After forming silicone rubber (HTV) on the surface of a metal shaft by heating and curing it under pressure, oligomers and monomers having a degree of polymerization of 20 or less were removed by vacuum distillation to 0.01 wt% to have a viscosity of 100CS. 24 in silicone oil (see Example 1) heated to 150 ° C
After dipping for a time and swelling the silicone rubber layer with silicone oil, the surface was polished to form a pressure roll 3, and a fixing device having the same configuration as in Example 1 was loaded in an electrophotographic copying machine to make a copy. I did. In the case of using the conventional fixing device, uneven copy density occurs in about 20,000 copies. At this time, when observing the corotron wire, a large amount of discharge products grow, and oil adheres to the platen glass and mirror. In contrast, when the fixing device of the present invention is used,
Good copies were obtained even after making 10,000 copies.

Example 3 A fixing roll was prepared using a silicone rubber composition in which low molecular weight components having a degree of polymerization of 20 or less were solvent-extracted and stripped to 0.001 wt% to knead silicone oil having a viscosity of 5,000 CS. When the same test as in Example 2 was conducted, a good copy was obtained even after copying 50,000 sheets as in Example 2.

EFFECT OF THE INVENTION The fixing device of the present invention is one in which a silicone oil from which low-molecular weight volatile components have been removed is supplied to the roll surface or contained in the roll as a release agent. According to the fixing device of the present invention, the fixing device is heated. Since the volatilization of the silicone oil from the fixing roll is reduced, the deterioration of the corotron and the stains on the platen glass, the mirror, the lens, etc. are reduced, and it becomes possible to maintain a good copy for a long time.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of an example of a fixing device of the present invention, and FIG. 2 is a schematic configuration diagram of an example of an electrophotographic copying machine. Reference numeral 1 in the figure: fixing device; 2 ... heating roll; 2a ... core bar; 2b ... coating layer; 3 ... pressure roll; 3a ... core bar; 3b ... heat resistant elastic layer; 4 ... … Paper; 5… Wick; 6… Oil pan; 7… Control grade; 8… Oil tank; 9… Oil supply device; 10… Originals; 11… Platen; 12… Light source; 13 …… Developer; 14 …… Transfer; 15 …… Paper feeder; 16 …… Paper; 17 …… Peeling charger; 18 …… Fixer; 19 …… Pre-cleaning corotron; 20 …… Cleaning Device; 21 ... Charging device; 22
…… Charge acceptor; 23 …… Optical system.

Continuation of the front page (56) Reference JP 62-47673 (JP, A) JP 63-169678 (JP, A) JP 59-69773 (JP, A) JP 60-135975 (JP , A) JP 60-111272 (JP, A) JP 59-185374 (JP, A) JP 59-180572 (JP, A) JP 56-6279 (JP, A) JP 55-90983 (JP, A) JP 58-14173 (JP, A) JP 56-64368 (JP, A) Actually opened 58-10459 (JP, U) Actually opened 59-73762 (JP, U) JP-B 57-4906 (JP, B2) JP-B 58-52589 (JP, B2) JP-B 59-29874 (JP, B2) JP-B 61-1750 (JP, B2) JP-B 54 -26899 (JP, B2) JP-B 59-21556 (JP, B2) JP-B 59-4699 (JP, B2) JP-B 54-41332 (JP, B2) JP-B 53-30495 (JP, B2) ) Japanese Patent Publication Sho 54-41332 (JP, B2)

Claims (3)

[Claims] 1. In a fixing device comprising a heating roll and a pressure roll and using silicone oil as a releasing agent, a silicone oil having a polymerization degree of 10 or more as a main component, from which volatile monomer and oligomer components have been removed, is used. A fixing device characterized by: 2. The fixing device according to claim 1, wherein silicone oil is supplied to the surface of the heating roll and / or the pressure roll. 3. The fixing device according to claim 1, wherein a silicone rubber roll forming a heating roll or a pressure roll contains silicone oil.