JP2000079365A - Oil coating roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil coating roller for the fixing device of an electronic copier capable of applying even silicone oil of low viscosity in proper quantity from a start of use. SOLUTION: A porous round rod-shaped molded object with the total voids of 30-90% obtained by molding heat-resistant fibers is used as an oil holding member to be impregnated with silicone oil and a heat-resistant fiber felt layer is provided to the outer periphery of this impregnated molded object and, pref., a thin layer of an elastomer having open cells is provided on the outer periphery thereof. Further, the outer periphery of the thin layer is covered with a porous film (especially comprising polytetrafluoroethylene) with a thickness of 0.1-1.0 μm, voids of 60-90% and air permeability of 3-100 sec/100 cc to form an oil coating roller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil application roller which is a component of a fixing device in an electrostatic copying machine, an electrophotographic printer, etc. (especially for color copying and multicolor printing).

[0002]

2. Description of the Related Art In a fixing device of an electrostatic copying machine or an electrophotographic printer, in order to prevent toner remaining on the fixing roll from soiling the recording paper, the fixing roller is rotated directly or indirectly in contact with the fixing roll. Usually, a small amount of silicone oil is always applied to the fixing roll by providing an oil application roller.

[0003] Various oil application rollers have already been provided, but as an oil holding member for storing oil to be applied, a metal pipe having a large number of pores in a tube wall or a cylindrical member made of heat-resistant fiber. An oil application roller using a molded body and having an oil application member layer made of heat-resistant felt on the surface thereof, in which heat-resistant fibers are mutually bonded by a binder as an oil holding member, and a binder is present between the fibers. Not having fine communicating pores and uniformly distributed pore groups having a pore diameter of 0.05 to 2 mm, and a total porosity of 30 to
An oil application roller using a 90% porous cylindrical molded body (Japanese Patent Application Laid-Open No. 9-108601) is capable of holding a large amount of silicone oil by an oil holding member and applying a high load to the silicone oil. Since the liquid can be stably discharged over a long period of time even under conditions, there is a feature that stable oil application is performed for a long period of time.

However, when this is used for a fixing device of a color copying machine or a color printer, the above-mentioned features are still exhibited, but a larger amount of oil is applied to the fixing roll than in the case of a monochrome type. Due to the necessity of application, a relatively low viscosity silicone oil of 50 to 1000 cst is used, so the oil application amount becomes excessive for a while from the start of use (between several hundred to one thousand sheets in number of sheets passed). Tend. In addition, for the same reason, the amount of oil that leaks out even when the machine is stopped is increased, and there is a problem that the silicone oil, which also exceeds the proper amount, is applied to the fixing roll for a short time immediately after resuming paper feeding.

Further, when copying or printing is performed on OHP paper made of a plastic sheet, even a slight amount of uneven oil application may affect the fixation of the toner and easily cause shading of the fixed image. The surface of the felt layer formed by helically winding has a slight step at the abutting part of the end face of the tape-shaped felt even though it is apparently flat, and it extends spirally, so it has a slight streak-like This causes oil application unevenness, and eventually causes unevenness in the density of a fixed image.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and is intended to apply a proper amount of oil from the start of use even for a low-viscosity silicone oil. It is an object of the present invention to provide an oil application roller which enables the above.

Another object of the present invention is to provide an oil applying roller which has a small amount of unnecessary oil bleeding during stoppage and is free from excessive oil application immediately after resuming paper feeding.

It is still another object of the present invention to provide an oil application roller which enables extremely uniform oil application without causing shading in a fixed image even when copying or printing on OHP paper. .

[0009]

The oil application roller according to the present invention comprises a porous round bar-shaped molded article (including a hollow cylindrical molded article), preferably a heat-resistant fiber bonded to each other by a binder. A porous round bar-shaped molded product having fine communicating pores having no binder therebetween and uniformly distributed pore groups having a pore diameter of 0.05 to 2 mm and a total porosity of 30 to 90% is used as an oil holding member. This is impregnated with silicone oil, and a heat-resistant fiber felt layer having a thickness of 0.5 to 5 mm is provided on the outer periphery thereof.
3-3mm, compression hardness 0.03-1.5N / cm
² , an elastic layer having continuous air holes is provided, and furthermore, the outer periphery thereof has a thickness of 15 to 130 μm and an average pore diameter of 0.1 to 1.
0 μm, porosity 60 to 90%, air permeability 3 to 1500 seconds /
It is characterized in that the outermost surface layer is covered with a 100 cc porous film.

[0010] Here, "compression hardness" refers to JIS K6767.
And the “air permeability” is the Gurley number (unit: sec / 100 cc) measured by a B-type Gurley densometer,
“Total porosity” and “porosity” are values calculated from the measured values of specific gravity by the following formula. Total porosity, porosity (%) = [1-bulk specific gravity / true specific gravity] × 1
00

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The oil holding member at the core of the oil application roller according to the present invention is preferably the one described in
It is similar to that disclosed in JP 08601, and retains a large amount of silicone oil in a large pore group. The retained silicone oil migrates to the heat-resistant fiber felt layer by capillary action via fine inter-fiber voids, and then, when an elastic layer is provided, also passes through the elastic layer to form a porous membrane. And finally seeps onto the roller surface.

The porous film present in the outermost layer stabilizes the applied amount of silicone oil at a very desirable level. Attaching a porous membrane to the surface limits oil ooze, which not only suppresses oil ooze for a while from the start of use and immediately after resumption of operation, but also reduces oil ooze during steady operation. It was expected that a large amount of oil could not be applied, but a low viscosity silicone oil of 50 to 1000 cst, a thickness of 15 to 130 μm, an average pore diameter of 0.1 to 1.0 μm, a porosity of 60 to 90%, and air permeability In combination with a polytetrafluoroethylene porous membrane of 3 to 1500 seconds / 100 cc, the problem of excessive oil application at the start of use and at the start of operation is remarkably improved. A larger amount of oil was applied rather than without the porous membrane, resulting in a very stable oil application. It is.

A porous film having a larger pore diameter than that of the above-mentioned porous film and thus having a low air permeability is not considered to be inferior to the original oil application amount stabilizing effect. It is not preferable because the pores are clogged or the amount of oil applied is significantly reduced when used for a long period of time.

In the case where an elastic layer is provided between the porous film and the felt layer, the elastic layer has a cushioning effect based on its elastic deformation ability, and the contact pressure between the oil application roller and the fixing roller is felt. It is possible to prevent the above-described unevenness in oil application and, consequently, unevenness in image fixation caused by the unevenness of the layer.

Next, a typical production method of the oil application roller of the present invention will be described, but the production method is not limited to this.

The most preferable oil holding member for the oil application roller of the present invention can be manufactured by the method described in JP-A-9-108601. That is, heat-resistant fibers such as aluminosilicate fibers, alumina fibers, glass fibers, and aramid fibers (preferably having a fiber diameter of about 2 to 1
5 μm), water-resistant granular organic substances for forming pores, for example, finely divided synthetic resin, wood powder, carbon powder, etc., and a suitable binder, and if necessary, for adjusting the inter-fiber void amount of the product. Inorganic fillers are usually blended in the following ratio, and an appropriate amount of water is added and mixed to form a desired shape.

Heat-resistant fiber (total amount of filler when filler is used) 100 parts by weight Water-resistant granular organic substance 10 to 300 parts by weight Binder 2 to 100 parts by weight (mixture of organic binder and inorganic binder) 50 to 300 parts by weight when using

The obtained molded body is dried and cured under heating, and further heated to about 150 to 400 ° C. (when used together with an inorganic binder, fired at about 400 to 1000 ° C.) to obtain a granular product. When the organic matter is eliminated by burning or decomposition / gasification, pores remain thereafter.

In the above steps, selection of raw materials, mixing ratio,
By selecting the molding conditions and the like, a group of pores having a pore size of 0.05 to 2 mm and preferably a pore size of 5 to 30
A μm inter-fiber porosity is formed such that the total porosity is 30-90% (preferably about 70-85%). This is necessary in order to be able to hold as much oil as possible while ensuring mechanical strength, and to be able to smoothly discharge the held oil.

The obtained oil holding member has a viscosity of 50 to 1
It is immersed in a 000 cst silicone oil to absorb the oil so that most of the pores in the holding member are filled with the silicone oil.

As the oil holding member, any other fibrous or metal porous cylindrical molded body can be used.

Thereafter, a felt having a thickness of 0.5 to 5 mm, preferably 1 to 3 mm, cut into a tape having a width of about 30 mm is spirally wound around the outer periphery of the oil holding member and fixed. As the felt, a bulk density of a heat-resistant synthetic fiber such as aramid fiber is 150 to 300 kg / m.
^{About 3} is appropriate. The felt layer not only sucks up the oil from the oil holding member, but also elastically deforms to increase the contact area between the heat roller and the oil application roller of the fixing device, and has the effect of eliminating uneven oil application.

When an elastic layer is provided on the felt layer, a sheet-like porous elastic body is wound thereafter. Suitable elastic materials include nonwoven fabric, foamed polyurethane, foamed melamine resin, and the like. The elastic sheet to be used must have an appropriate thickness. If the thickness is less than 0.3 mm, the unevenness of the felt layer cannot be absorbed in many cases, and the effect of preventing uneven oil application is insufficient. On the other hand, when the thickness exceeds 3 mm, it becomes difficult to supply a required amount of oil to the outermost surface layer. The compression hardness of the elastic layer is important for the layer to exhibit an appropriate compression elasticity. Even hardness exceeds the 1.5 N / cm ² at less than 0.03 N / cm ^2, suitable elasticity needed to equalize the oil application roller contact pressure elastic layer absorbs the unevenness of the felt layer No deformation is shown.

Finally, the above-mentioned porous membrane is wound and fixed. As the porous film, a film made of polytetrafluoroethylene is most suitable because of its excellent effect. Polytetrafluoroethylene porous membranes having various characteristics having different pore sizes, amounts, film thicknesses, and the like are commercially available, and those used in the present invention can be easily obtained.
Examples of commercially available products include Microtex of Nitto Denko Corporation and Poeflon of Sumitomo Electric Industries, Ltd.

As described above, the oil application roller of the present invention is obtained. The support shaft to be mounted on a fixing device of a copying machine or a printer can be attached at any stage before or after the impregnation with silicone oil.

[0026]

EXAMPLES Comparative Example 1 An outer diameter of 22 mm, an inner diameter of 6 mm and a length of 30 made mainly of aluminosilicate fiber having an average fiber diameter of 3.8 μm.
0 mm cylindrical porous molded article (having fine inter-fiber voids and pores having a pore diameter of about 0.1 to 0.3 mm, and having a total porosity of 78%
About 100 cst silicone oil about 73
g was impregnated, and then a spindle was inserted into the hollow portion and fixed at both ends. Thereafter, an aramid-based heat-resistant fiber felt (bulk density: 260 kg / m ³ , thickness: 2 mm) was wound around the outer peripheral surface and fixed to obtain an oil application roller for a fixing device of a color copying machine.

Comparative Example 2 Heat-resistant paper (mixed with aramid fiber and polyester fiber; thickness of 55) was applied to the outer peripheral surface of the oil application roller of Comparative Example 1.
μm, average pore diameter 30μm, air permeability 2sec / 100cc)
Was wound and fixed.

Examples 1 and 2 A porous film made of polytetrafluoroethylene as shown in Table 1 was fixed around the outer peripheral surface of the oil application roller of Comparative Example 1.

Test Example 1 The suitability of the oil application roller of each of the above examples as a silicone oil application roller of a fixing device of a color copying machine was tested by the following test method.

Test method: The application roller was mounted on an oil discharge characteristic tester, and the change in the amount of oil applied (mg / sheet) when paper was continuously passed at a sheet passing speed of 16 sheets / min was examined.

The test results are shown in Table 1. It can be seen that covering the surface with a specific porous film solves the problem of initial overcoating and does not reduce the coating amount.

[0032]

[Table 1]

Test Example 2 With respect to the oil application rollers of Example 1 and Comparative Example 2,
It was mounted on a medium-speed copier to test the stability of oil application amount. The test was performed by interrupting the paper feeding after 2,000 sheets were passed at 65 ppm, restarting the paper feeding three hours later, and comparing the oil application amounts before and after the paper feeding was interrupted.

The results are as shown in Table 2, and it can be seen that the example product does not apply excess oil immediately after resuming paper feeding.

[0035]

[Table 2]

Examples 3 to 6 and Comparative Examples 1 to 3 About 120 g of a silicone oil having a viscosity of 100 cst was added to a cylindrical porous molded body (outer diameter 29 mm, inner diameter 8 mm, length 338 mm) produced in the same manner as in Comparative Example 1. , And then a spindle is inserted into the hollow portion and fixed at both ends. Next, an aramid fiber felt cut into a tape having a width of 30 mm (bulk density: 260 kg / m ³ , thickness: 2 mm) is formed on the outer peripheral surface.
Is helically wound and fixed thereon, and a nonwoven fabric made of polyester fiber is wound thereon to form an elastic layer, on which a polytetrafluoroethylene porous membrane (average pore diameter 0.1 μm, porosity 60%) , 30 μm in thickness).

An oil application roller was manufactured by the above-described method by changing the nonwoven fabric as the material of the elastic layer in various ways, and the performance of the product was compared by the following test method. For comparison, an oil application roller manufactured in the same manner without the elastic layer was also tested.

Test method: An oil application roller is mounted on a fixing device of a color copying machine, and magenta monochromatic toner is fixed on the entire surface of an A4-size OHP sheet at a sheet passing speed of four sheets per minute. The magenta unevenness of the entire surface due to the fixed toner is visually observed, and the image quality is evaluated based on the following criteria.

◎: very good ：: good △: shading corresponding to the winding of the felt is partially observed. ×: The shading unevenness is severe. Table 3 shows the test results.

[0040]

[Table 3]

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiyuki Motoyoshi 1-8-4 Dobashi, Miyamae-ku, Kawasaki City, Kanagawa Prefecture (72) Inventor Osamu Horiuchi 3-43-32, Takatatsuhigashi, Hamamatsu City, Shizuoka Prefecture (72) Inventor Munehiko Fukase 5-5-7 Kamijima, Hamamatsu City, Shizuoka Prefecture (72) Inventor Toshiyuki Kishida 5-5-7 Kamijima, Hamamatsu City, Shizuoka Prefecture (72) Inventor Shigeru 5-5-7 Kamijima, Hamamatsu City, Shizuoka Prefecture (72) Inventor Abe Yumi 5-5-7 Kamijima, Hamamatsu City, Shizuoka Prefecture (72) Inventor Hironori Furuya 226-20 Shimoatsuzaki, Kuroiso City, Tochigi Prefecture Zenith Corporation

Claims (5)

[Claims] 1. A porosity having heat-resistant fibers interconnected by a binder and having fine communicating pores in which no binder is present between the fibers and pores having a pore diameter of 0.05 to 2 mm uniformly distributed. Is 30 to 90%, and a silicone oil is impregnated in a porous round bar-shaped molded product, and the outer periphery thereof has a thickness of 0.5 to 90%.
A heat-resistant fiber felt layer of 5 mm is provided, and furthermore, the outer periphery thereof has a thickness of 15 to 130 μm and an average pore diameter of 0.1 to 1.0 μm.
m, porosity 60 to 90%, air permeability 3 to 1500 sec / 10
An oil application roller covered with a 0 cc porous film. 2. A porous round bar-shaped molded product is impregnated with silicone oil, and a tape-like tape of heat-resistant fiber felt having a thickness of 0.5 to 5 mm is spirally wound around its outer periphery, and a continuous vent hole is formed on its outer periphery. A thin layer made of an elastic body having a thickness of 15 to 130 μm and an average pore diameter of 0.1 to 130 μm.
1 to 1.0 μm, porosity 60 to 90%, air permeability 3 to 15
An oil application roller covered with a 00 second / 100 cc porous film. 3. A total porosity having heat-resistant fibers mutually bonded by a binder and having fine communicating pores in which no binder is present between the fibers and pores having a pore diameter of 0.05 to 2 mm uniformly distributed. Is 30 to 90%, and a silicone oil is impregnated in a porous round bar-shaped molded product, and the outer periphery thereof has a thickness of 0.5 to 90%.
A 5 mm heat-resistant fiber felt tape is wound spirally, and then has a thickness of 0.3 to 3 m having continuous air holes.
m, compression hardness (JIS K6767) 0.03 to 1.5
A layer made of an elastic body of N / cm ² is provided, and furthermore, the outer periphery thereof has a thickness of 15 to 130 μm and an average pore diameter of 0.1 to 1.0 μm.
m, porosity 60 to 90%, air permeability 3 to 1500 sec / 10
An oil application roller covered with a 0 cc porous film. 4. The oil application roller according to claim 1, wherein the porous film is made of polytetrafluoroethylene. 5. The oil application roller according to claim 2, wherein the elastic body having the continuous ventilation holes is a nonwoven fabric.