JPH08123237A - Production of oil holding member of oil coating roller - Google Patents

Abstract

PURPOSE: To provide a production method of an oil holding member of an oil coating roller for a fixing device in an electrostatic copying machine so that oil can be stably supplied for a long term. CONSTITUTION: Heat-resistant fibers having >=3μm average fiber diameter, 30-50wt.% of a binder to the heat-resistant fibers, and a proper amt. of water are mixed to obtain a plastic mixture, which is then formed by extrusion molding and dried to obtain a formed body having 15-50μm average pore diameter and 50-80% porosity. Since large continuous pores are distributed in a high proportion inside of the product so that a large amt. of silicone oil can be held in the pores.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an oil holding member used for an oil application roller of a fixing device in an electrostatic copying machine or an electrophotographic printer.

[0002]

2. Description of the Related Art Most of fixing devices for electrostatic copying machines and electrophotographic printers have a part called an oil applying roller. The oil applying roller is brought into contact with the fixing roller to rotate, and the fixing roller is rotated in the meantime. A small amount of silicone oil is applied to improve the releasability of the recording paper. The oil application roller also has a role of preventing the offset by wiping off the toner attached to the fixing roller.

The silicone oil applied to the fixing roller by the oil applying roller may be sequentially supplied to the oil applying roller from a separately prepared oil storage member, but the oil applying roller itself holds a certain amount, When the retained oil is exhausted, it is normal to replace the entire oil application roller.

As a mechanism for holding the silicone oil on the oil application roller, conventionally, a mechanism for holding the silicone oil directly on the drive shaft or through a silicone rubber layer is used.
Paper or felt wrapped around and impregnated with silicone oil; A shaft around which a felt or the like as an oil retaining layer is wrapped around to impregnate silicone oil, and the surface of which is provided with a felt layer in contact with the fixing roller A drive shaft of an oil coating roller is oil-permeable and hollow, and silicone oil is sealed in the hollow portion.

The performance required of the oil application roller is that the amount of oil applied during use is small and the recording paper is soiled with oil by applying an excessive amount of oil even when the operation is restarted after not using for a long time. It has a large oil holding capacity, can be used for a long period of time, and is as small as possible.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an improved oil holding member that enables the oil applying roller with an oil holding mechanism to perform stable oil application for a long period of time.

[0007]

The method for producing an oil holding member according to the present invention comprises a heat resistant fiber having an average fiber diameter of 3 μm or more, a binder of 30 to 50% by weight based on the heat resistant fiber,
And an appropriate amount of water are mixed, and the obtained plastic mixture is extrusion-molded into a required shape as an oil holding member and then dried to have an average pore diameter of 15 to 50 μm and a porosity of 50 to 80%.
It is characterized by obtaining a molded product of (however, porosity = [1
-Bulk specific gravity / true specific gravity] x 100)).

The above manufacturing method will be described in detail below. The heat-resistant fiber as a raw material has an average fiber diameter of about 2 from among those having an arbitrary chemical composition such as rock wool, aluminosilicate fiber, alumina fiber, glass fiber and aramid fiber.
.About.15 .mu.m, particularly preferably 3 to 5 .mu.m, a rather thick one is used. This is because the thick fiber with high rigidity is used.
This is because it is advantageous to obtain a product having a large pore diameter of 5 μm or more. If thin fibers having an average fiber diameter of less than 2 μm are used, it is difficult to obtain a product having a large pore diameter even if the raw material composition and molding conditions are selected.

Examples of the binder include organic binders such as methyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, phenol resin, polyacrylic acid ester and sodium polyacrylate, and inorganic binders such as colloidal silica and alumina sol. Agents can be used.

The heat resistant fiber and the binder are mixed well by adding an appropriate amount of water to form a uniform plastic mixture. Since the blending amounts of the binder and water influence the porosity of the product, the preferable blending ratio of the raw materials varies depending on the required product characteristics, but is generally in the following range. Heat resistant fiber 50 to 90% by weight Binder 50 to 10% by weight Water 100 to 200 parts by weight per 100 parts by weight of the total amount of the above raw materials.

[0011] The strength of the product increases as the organic binder and the inorganic binder are sufficiently used, but when used in excess,
It becomes difficult to obtain a product having a high porosity of 50 to 80%.

The obtained plastic mixture is extruded into a predetermined shape by selecting extrusion conditions such as extrusion pressure.
The average pore size of the product is 15-50 μm, and the porosity is 50-8.
Make it 0%. The molding shape can be arbitrarily selected according to the usage method of the product oil coating roller,
Usually, it is formed into a cylindrical or columnar shape that can be mounted on the drive shaft of the oil application roller (for example, formed into a cylindrical shape having a hollow portion into which the drive shaft can be tightly fitted).

Then, the extruded product is cured by drying at room temperature or under heating. In this dry curing process where water evaporates,
An open air hole is formed in the molded product. Before or after drying, cut into an appropriate length according to the size and usage of the oil application roller to be mounted.

Large vent holes are distributed at a high rate inside the oil holding member obtained by the above manufacturing method, and a large amount of silicone oil can be held therein. The amount of silicone oil that can be retained is
Although it depends on the porosity of the holding member, it is usually about 45 to 180% by weight of the weight of the holding member.

Next, a description will be given of an example in which the oil applying roller is manufactured by using the oil holding member which is formed so as to have an inner diameter slightly larger than the diameter of the drive shaft of the oil applying roller. After soaking in silicone oil and impregnating the oil, insert the drive shaft into the hollow part,
It is fixed to the drive shaft at both ends, and a felt made of aramid series or any other heat resistant fiber is wound around the surface.

The silicone oil held in the pores of the oil holding member oozes out little by little to wet the surface of the fibers constituting the surface felt layer, and the oil applying roller is operated during the operation of the equipment equipped with the oil applying roller. It is applied to a fixing roller that contacts while rotating. When the silicone oil in the surface felt layer is deprived by the fixing roller, the reduced amount is successively replenished from the oil holding member, so that the surface felt layer is always kept wet with the silicone oil.

The average pore diameter of the oil holding member is 15 to 50.
Molding to have a thickness of μm is necessary so that the above-mentioned silicone oil can be smoothly supplied to the surface felt layer. If the pore diameter is smaller than the above range, the oil retaining force due to the capillary phenomenon is too strong, and the silicone oil cannot be smoothly replenished to the surface felt layer. There will be a shortage. On the other hand, if the pore diameter is too large, the oil retaining force becomes weak and the silicone oil excessively migrates to the surface felt layer, resulting in an excessive amount of oil applied to the fixing roller. In particular, when the device is stopped, a large amount of oil is transferred to a portion that was in contact with the oil application roller, and the recording paper is soiled when the device is restarted.

The porosity of the oil retaining member is related to the amount of silicone oil that can be retained rather than the above-mentioned oil exudation characteristics. The higher the porosity, the greater the amount of silicone oil that can be retained. If the porosity is less than 50%, the silicone oil cannot be retained so much that the life of the oil application roller becomes too short. On the other hand, if the porosity is highly porous and exceeds 80%, it becomes difficult to secure the strength required for the oil application roller.

[0019]

EXAMPLES 67 parts by weight of aluminosilicate fiber having an average fiber diameter of 3.8 μm, 15 parts by weight of organic binder, and 95 parts of water
After kneading parts by weight, the obtained plastic mixture was extruded into a cylindrical shape. Then, the molded product is dried at 105 ° C. to have a porosity of 7
An oil holding member having 2.9%, an average pore diameter of 18.8 μm, a bulk specific gravity of 0.64, an inner diameter of 6 mm, an outer diameter of 16 mm, and a length of 300 mm was obtained.

This oil holding member was immersed in silicone oil having a viscosity of 60,000 cs to impregnate 35 g of silicone oil, and then a drive shaft having a diameter of 6 mm was inserted into the hollow portion of the holding member to fix both ends of the holding member in an annular shape. It was fixed to the drive shaft with metal fittings. Further, a felt made of aramid heat resistant fiber was wound around the outer peripheral surface of the oil holding member to obtain an oil application roller.

The above-mentioned oil application roller was mounted on an oil discharge characteristic tester, and the change in the oil discharge amount was examined under the same continuous paper-feeding conditions as those used by mounting it on a copying machine. as a result,
The amount of oil discharged per 1000 sheets of recording paper is at a preferable level of 0.0 until the cumulative number of passed sheets reaches 100,000.
7 to 0.1 g was maintained.

For comparison, an oil holding member having an average pore diameter of 14.2 μm (porosity 75.9%, bulk specific gravity 0) produced in the same manner except that aluminosilicate fiber having an average fiber diameter of 2 μm was used as a raw material. .55) was used to manufacture an oil application roller, and the same oil discharge characteristic test was conducted.
In this case, although the oil impregnation amount was 36 g and there was no great difference, it was possible to maintain the above-mentioned preferable oil discharge amount up to 20,000 accumulated sheets.

[0023]

As described above, according to the present invention, it is possible to easily mass-produce an oil holding member capable of holding silicone oil in a high volume ratio and stably releasing it for a long period of time. It enables cost reduction and longer life.

Claims (1)

[Claims] 1. A heat-resistant fiber having an average fiber diameter of 3 μm or more,
The heat-resistant fiber is mixed with 30 to 50% by weight of a binder and an appropriate amount of water, and the obtained plastic mixture is extrusion-molded and dried to have an average pore diameter of 15 to 50 μm and a porosity of 50 to 50 μm. A method for producing an oil holding member for an oil application roller, which comprises obtaining a molded product of 80%.