JPS61160780A - Coating device of thermofixing roll offset preventive solution - Google Patents

Abstract

PURPOSE:To coat offset preventive solution to proper thickness by forming an offset preventive solution coating member of a heat-resistant porous material in a vessellike shape, putting a liquid absorbing material in it, and coating it on the outer peripheral face of a heat roller controlling the quantity of oozing of the offset preventive solution by the coating member. CONSTITUTION:The coating member 10 is made of heat-resistant porous material less than 1mum in pore diameter, for instance, an ethylene tetrafluoride resin sheet. Heat-resistant liquid absorbing material 11 contained in the coating member 10 is, for instance, felt. The felt 11 is made to hold silicon oil 8 as offset solution in less than the saturation retention quantity of the felt 11. The viscosity of the silicon oil 8 is lowered by heating of a heat roll 2. In this state, partial distortion occurs in the felt 11 by vibration, etc. caused by rotation of the heat roll 2 and the oil retentivity of the felt 11 lowers. Thus, the silicon oil 8 oozes out from the felt 11, and coated on the outer peripheral face of the heat roll 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a coating device for a thermal fixing roll part offset prevention liquid applied to a copying machine having a thermal roll fixing part.

Summary of the Invention The present invention provides an anti-offset liquid application member formed of a heat-resistant porous material in the shape of a container, and a liquid absorbent that retains the anti-offset liquid at a saturation retention amount or less within the anti-offset liquid application member. The anti-offset liquid is applied to the outer circumferential surface of the heat roller while the amount of the anti-offset liquid seeped out is controlled by the application member.

<Prior art and its drawbacks> In general, the heat roll fixing section of a copying machine consists of a heat roll 2 with a built-in heater L, a backup roll 3 receiving a pressing force F, etc., as shown in FIG. The outer peripheral surface of the heat roll 2 is maintained at about 180°C by a temperature sensor 4 such as a thermistor and a heater control circuit (not shown).Unfixed toner is offset on the outer peripheral side of the heat roll 2. A surface-treated RFI 5 made of Teflon resin or the like is formed to make it difficult to use, and the backup roll 3 is made of silicone rubber to maintain pressure and provide additional fixing width. However, even with this configuration, it is difficult to completely prevent offset of unfixed toner. Therefore, as an auxiliary means, it is commonly used to apply silicone oil as an anti-offset liquid to the outer circumferential surface of the heat roll 2 to strengthen the mold release property. in this case,
The applied silicone oil needs to be as thin and uniform in thickness as possible. In other words, if the applied amount is excessive, silicone oil will adhere to the copy paper, and this oil will tend to accumulate especially at the position of the claw used to peel the copy paper from the heat roll 2, and this will evaporate and cause the corona discharge wire and If it adheres to the photoreceptor drum, it will cause deterioration of image quality.

In view of these points, conventionally, as shown in FIG. 3, an applicator member 6 made of a heat-resistant nonwoven fabric such as felt is provided which is in sliding contact with the outer peripheral surface of the heat roll 2. Silicone oil 8 is applied to the application member 6 by capillary action.
Apply silicone oil 8 with this application member 6 while impregnating it with silicone oil 8.
was applied to the outer peripheral surface of the heat roll 2, and the coating thickness of the silicone oil 8 was kept constant by scraping with a blade 9 made of Teflon rubber or the like.

However, in the above-mentioned conventional method, the blade 9 must be replaced as appropriate due to wear, etc., and the application member 6 must be replaced.
Since the silicone oil 8 always contains the silicone oil 8 up to the saturation retention amount, the amount of coating is originally large, and if the blade 9 wears out even a little, it will become overcoated. In particular, since the applicator 6 is made of nonwoven fabric, if a small amount of unfixed toner begins to adhere to the sliding contact portion 6a of the applicator 6 with the heat roll 2, that area will become clogged and the applicator function will deteriorate. The application member 6 must also be replaced soon.

<Object of the Invention> The object of the present invention is to solve the above-mentioned problems, to make it possible to apply an offset liquid to an appropriate thickness without using a blade for regulating the application thickness, and to effectively maintain the application performance of the application member over a long period of time. An object of the present invention is to provide an apparatus for applying an offset prevention liquid to a heat fixing roll part that can be maintained.

<Structure and effects of the invention> This invention is constructed as follows.

The anti-offset liquid application member that is in sliding contact with the outer peripheral surface of the heat roll is formed into a container shape using a heat-resistant porous material such as tetrafluoroethylene resin.

A heat-resistant liquid-absorbing material such as felt is housed in the application member.

The liquid-absorbing material retains an anti-offset liquid such as silicone oil at a saturation retention amount or less.

As a result, the offset liquid whose viscosity has decreased due to the heating of the heat roll begins to separate from the liquid absorbent material, seeps out through the porous coating member, and is applied little by little to the outer peripheral surface of the heat roll.

According to the present invention, configured as described above,
Since the amount of offset liquid held in the liquid absorbing material that seeps out depends on its viscosity, the amount applied to the heat roll is small and constant, and there is no need to provide a blade (particularly for the above-mentioned application). Since the member is made of porous material and a small amount of offset liquid always seeps out, unfixed toner will not adhere to the contact area with the heat roll, eliminating the risk of clogging the applicator and ensuring proper cleaning. The application effect can be maintained for a long period of time.

<Example> Fig. 1 is a schematic diagram of a coating device for anti-offset liquid on a heat fixing roll according to an example of the present invention, and the same parts as in the conventional one are given the same reference numerals and explanations are omitted. do.

In the figure, IO is a container-shaped anti-offset liquid applying member arranged so as to be in sliding contact with the outer peripheral surface of the heat roll 2. This coating member 10 has heat resistance and a pore diameter of 1 μm.
It is made of a porous material with a diameter of 50 m or less, for example, a tetrafluoroethylene resin sheet. Reference numeral 11 denotes a heat-resistant liquid-absorbing material, such as felt, housed in the coating member IO. This felt 11 is made to hold silicone oil 8 as an offset liquid at a level below the saturation retention amount of the felt 11 .

In the above configuration, the heat roll 2 rotates clockwise, and the outer peripheral surface thereof is heated to about 180° C. by the heater 1. Silicone oil 8 is heated by heat roll 2.
In a state where the viscosity of the felt 1-11 is reduced, partial distortion occurs in the felt 1-11 due to vibrations caused by the rotation of the heat roll 2, and the oil retention property of the felt 11 is also reduced. the result,
Silicone oil 8 seeps out from the felt 11 and is applied to the outer circumferential surface of the heat roll 2 through the holes of the application member 10 as shown in FIG. In this case, the silicone oil 8
Since the amount of coating is restricted by the viscosity of the coating, the coating thickness is kept constant. Furthermore, the pore diameter of the coating member 10 is 1 μm.
In addition to being small in size, the silicone oil 8 always seeps into this area, so the applicator 10 will not be clogged with unfixed toner.

The silicone oil 8 is set so that when the heat roll 2 is not rotating, the liquid absorption and retention force due to the capillary phenomenon of the felt 11 overcomes the retention force during heating.

Further, it is desirable to select and set the applicator 6 at a roll contact position where it can be easily deformed as much as possible so that the felt 11 is partially distorted when the heat roll 2 rotates.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a coating device for anti-offset liquid on a heat fixing roll according to an embodiment of the present invention, Fig. 2 is an enlarged view of the part marked ■ in Fig. 1, and Fig. 3 is a conventional heat fixing roll. FIG. 2 is a schematic configuration diagram of a coating device for anti-offset liquid. 2-heat roll, 8-offset prevention liquid, 10-coating member, 11-liquid absorbing material.

Claims (3)

[Claims] (1) An anti-offset liquid application member formed into a container shape from a heat-resistant porous material and slidably contacted with the outer peripheral surface of the heat roll of the heat fixing roll section, and a member for applying an anti-offset liquid to keep the anti-offset liquid below the saturated retention amount. and a heat-resistant liquid-absorbing material accommodated in the coating member. (2) The apparatus for applying an offset prevention liquid to a heat fixing roll part according to claim 1, wherein the application member is made of tetrafluoroethylene resin. (3) The apparatus for applying an offset prevention liquid to a heat fixing roll part according to claim 1, wherein the liquid absorbent material is made of a nonwoven fabric.