JPH01308457A - Silicone rubber composition, molding formed there-from and elastic rotating body and fixation apparatus having said composition - Google Patents

Abstract

PURPOSE:To make it possible to prevent or control the buildup of static electricity of a molding, by using a porous inorganic powder supporting thereon a specified silicone polyether copolymer. CONSTITUTION:100pts.wt. microporous inorganic powder (a) having a particle diameter of 1-70mum, a mean particle diameter of 1-40mum and an oil absorption of 200-800ml/100g is allowed to support thereon 100-600pts.wt. silicone polyether copolymer (b) having a polyoxyalkylene group as a side chain, having a structure of a nonionic surfactant in which a dimethyl-polysiloxane moiety is the hydrophobic group and a polyether moiety is the hydrophilic group to obtain a component (B) comprising the component (a) supporting thereon the component (b). A polymer (A) having groups of the formula (wherein R1-2 are each an alkyl, an aryl, a polyfluoroalkyl group or the like) as the main chain is mixed with 0.1-20wt.%, based on component A, component B in an amount to give 0.1-20wt.% component (b), based on component A, and optionally, a filler, a heat resistance improver, a compression set improver, a dispersant, etc. (C).

Description

Detailed Description of the Invention [Industrial Application Field] The present invention comprises a silicone rubber composition, a molded article formed from the composition, and an elastic body having a surface layer formed from the composition. The present invention relates to an elastic rotating body and a fixing device having the elastic rotating body.

[Prior Art] In an image forming apparatus such as an electronic copying machine, a conveyance roller that conveys a sheet-like transfer material or recording material such as plain paper along a predetermined path generally has a certain level of conveyance performance, JIS conformity, and durability. is required.

In particular, fixing rollers and heat rollers that must apply heat under pressure to the unfixed toner image on the transfer paper and convey the transfer paper to a predetermined path while preventing the offset phenomenon of semi-melted or molten toner. A fixing device equipped with a pressure roller is required to have conveyance properties, A-type properties, #abrasion properties, fixing properties, and durability under more severe conditions.

Conventionally, this type of fixing device has at least a fixing roller and a pressure roller that is in pressure contact with the fixing roller and rotates as a result of the fixing roller. The fixing roller is made of a material with good mold releasability such as polytetrafluoroethylene, tetrafluoroethylene-fluoroalkoxyethylene copolymer, fluororesin, or silicone rubber on a hollow core metal such as aluminum or iron. A layer is formed over the surface. Further, the fixing roller is provided with a heater such as a halogen lamp, if necessary, to raise the temperature of the surface of the fixing roller to a specific temperature suitable for fixing. Further, in many cases, the surface temperature of the fixing roller is controlled using a sensor so that it always remains at a set temperature. Furthermore, the outer circumferential surface of the fixing roller may be provided with a cleaner for removing offset toner and paper dust, and a separation claw for preventing the image bearing material from wrapping around the fixing roller.

On the other hand, in the pressure roller, a core metal such as iron or stainless steel is coated with an elastic layer having release properties such as silicone rubber. The pressure roller is pressed against the fixing roller by a spring or the like.

In this manner, the image bearing material having the unfixed toner image is conveyed while being held under heat and pressure by the fixing roller and the pressure roller, whereby the unfixed toner image is fixed under pressure.

[Problems to be Solved by the Invention] In the conventional apparatus described above, there is a problem in that the pressure roller becomes charged to, for example, 2 KV or more due to friction and electrification when paper is passed through the paper, and as a result, the paper wraps around the pressure roller. Ta. Further, due to the electric field of the pressure roller, unfixed toner scatters and blurs the line image, and toner adheres to the surface of the fixing roller, resulting in increased offset.

As a countermeasure to the above-mentioned problem, conventionally, a static elimination brush was brought into contact with the pressure roller to eliminate static electricity by grounding. However, even with this measure, the potential drops only to about 1 to 2 KV, and the static elimination effect is limited and cannot be said to be sufficient, and an improvement has been desired.

Also, in the case of a fixing device that does not have a cleaning means for cleaning the surface of the fixing roller.

If the pressure roller surface is highly charged, the amount of toner adhering to the fixing roller surface increases, and the toner transfers to a transfer material such as paper or to the pressure roller surface.

Problems such as image defects such as offset and toner adhesion stains on the roller surface are likely to occur.

[Means and effects for solving the problems] The present invention provides a silicone rubber composition containing a porous inorganic fine powder having micropores supporting a silicone polyether copolymer having a polyoxyalkylene group in a side chain. This makes it possible to prevent or suppress charging of the rubber molded product.

The silicone rubber composition of the present invention may be of the condensation reaction type, addition reaction type, or radical reaction type, and the polymer component constituting the silicone rubber composition of the present invention may be any of the condensation reaction type, addition reaction type, and radical reaction type.

7, such as alkyl groups such as ru groups, ethyl groups, phenyl groups, etc.
These include polyfluoroalkyl groups such as lyl group and trifluoropropyl group.

The silicone polyether copolymer having a polyoxyalkylene group in the side chain in the present invention is a nonionic surfactant in which the dimethylpolysiloxane part of the molecule is a hydrophobic group and the polyether part is a parent wood group. The porous fine powder having micropores in the present invention is preferably an inorganic fine powder from the viewpoint of thermal stability. Those with a large oil absorption capacity that can support a large amount of the silicone polyether copolymer are preferable. M,S,GEL
, silica microbeads manufactured by Catalysts & Chemicals Co., Ltd., siloids manufactured by Fuji Davison Chemical Co., Ltd.), Shirasuba,
Runes are exemplified. The fine powder has a particle size of 1 to ? Opm
The average particle size is in the range of 1 to 40 layers, and the oil absorption is 200 to 800 layers 1'/100 g, preferably 300 to 800 mA'/100 g.

The impregnation ratio of the silicone polyether copolymer having a polyoxyalkylene group to the fine powder is #fine powder 1
00 parts by weight is preferably 100 to 600 parts by weight,
The amount of the silicone polyether copolymer supported porous fine powder having micropores to be added to the silicone rubber composition, which is particularly preferably in the range of 200 to 500 parts by weight, is based on the silicone rubber. The actual addition amount of the combined substance is 0.1 to 20% by weight, preferably 1
．． Amounts corresponding to 5 to 10% by weight are suitable. Addition amount is 0.
If the amount is less than 5% by weight, the antistatic effect will not be exhibited, and if the amount is more than 20 parts by weight, the physical properties will deteriorate.

The silicone rubber composition of the present invention includes fine powder synthetic silica, quartz powder, fused quartz powder, diatomaceous earth,
Other additives that may include calcium carbonate include heat resistance improvers such as iron oxide such as red iron oxide, compression set improvers such as titanium oxide and zinc oxide, dispersants such as low molecular weight siloxane, etc. You may also use

The elastic rotating body of the present invention is an elastic body formed from a silicone rubber composition containing porous inorganic fine powder having micropores and supporting a silicone polyether copolymer having a polyoxyalkylene group in the side chain. The fixing device of the present invention fixes an unfixed toner image formed on an image carrier by heating and pressurizing the image carrier by sandwiching and conveying the image carrier between at least a pair of rollers.

Embodiments of the elastic rotating body and fixing device of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a diagram mainly showing a vertical cross-sectional view showing a schematic configuration of a fixing device including an elastic rotating body of the present invention as a pressure roller. In the figure, reference numeral 1 denotes a fixing roller, and the fixing roller 1 is made of a core metal 2 made of aluminum, iron, stainless steel, etc., and resin waste 3 having heat resistance and mold releasability, such as PFA or PTFE, is formed on the outer surface of the core metal 2. There is. A heating means 9 such as a heater is included inside the core metal 2.

A pressure roller 4 is pressed against the fixing roller 1 by a spring or the like (not shown) and is driven to rotate. The pressure roller 4 has an elastic layer 6 made of a silicone rubber composition according to the present invention formed on a core metal 5 made of iron, stainless steel, or the like.

Around the fixing roller 1, there is a thermistor 8 for detecting the temperature of the fixing roller l. A cleaner may be provided for contacting the fixing roller 1 to clean its surface, and an entrance for guiding a transfer material 11 such as plain paper having a toner image 1O between the fixing roller 1 and the pressure roller 4. A guide 12 and the like are provided. On the other hand, a conductive leaf spring 13 for grounding is in contact with the core metal 5 of the pressure roller 4 .

[Example] Hereinafter, parts mean parts by weight.

Example 1 To 100 parts of an addition reaction type liquid silicone rubber composition having a viscosity of 800 poise, consisting of 100 parts of vinyl group-containing diorganopolysiloxane, 5 parts of dry finely powdered silica, 20 parts of quartz powder, 1 part of red iron and a platinum catalyst, Addition obtained by adding 5 parts of porous inorganic fine powder having micropores supporting a silicone polyether copolymer (Shin-Etsu Chemical KF352) having a polyoxyalkylene group in the side chain, and uniformly stirring and dispersing it. The reactive liquid silicone rubber composition was designated as A liquid.

100 parts of a mixture of vinyl group-containing diorganopolysiloxane and active hydrogen group-containing diorganopolysiloxane, 5 parts of dry fine powder silica, 1 part of quartz powder, 20 parts.

Similar to liquid A, 5 parts of a porous inorganic fine powder having micropores supporting the above-mentioned silicone polyether copolymer were added to 100 parts of an addition-reactive liquid silicone rubber composition having a viscosity of 800 poise and consisting of 1 part of red iron. The addition reaction type liquid silicone rubber composition obtained by adding and stirring and dispersing uniformly was designated as Liquid B.

The weight ratio of liquid A and liquid B is 100 parts! After mixing with OO and defoaming,
By heating at 150° C. for 10 minutes, the vinyl groups in the mixed composition and silicon-bonded hydrogen start an addition reaction in the presence of a platinum catalyst, and the mixed composition is cured to form a rubber-like elastomer. became.

A porous inorganic fine powder supporting a silicone polyether copolymer was prepared as follows. Average particle size: 251° Pore size: 0.
01" 10gm, oil absorption 50hi'/loog,
The apparent specific gravity is 0.1. 100 parts of gyrolite-type calcium silicate (Fluorite R manufactured by Tokuyama Soda) with a BET specific surface area of 115 and 27 g was introduced into a stirring device, and 400 parts of a polyoxyalkylene group-containing silicone polyether copolymer (F352 manufactured by Shin-Etsu Chemical) was introduced into the stirrer. 1 part was gradually dropped into the stirred calcium silicate fine powder, and after dropping the entire amount (400 parts), stirring was continued for a while, and the silicone polyether copolymer having a polyoxyalkylene group was taken out from the stirring device. A fine powder of supported calcium silicate was obtained.

Comparative Example 1 An addition reaction liquid silicone rubber composition with a viscosity of 900 voids was prepared in the same manner as in Liquid A of Example 1, except that no inorganic fine powder supporting a silicone polyether copolymer was added. , and liquid C.

In addition, an addition reaction liquid silicone rubber composition with a viscosity of 600 voids was prepared in the same manner as in Solution B of Example 1, except that no inorganic fine powder supporting a silicone polyether copolymer was added. It was made into liquid D.

Mix liquid C and liquid D uniformly at a weight ratio of 100:100,
After defoaming, by heating at 150°C for 10 minutes,
The vinyl groups and silicon-bonded hydrogen in the mixed composition started an addition reaction in the presence of a platinum catalyst, and the mixed composition was cured into a rubber-like elastic body.

Example 1. Regarding the rubber-like elastic body obtained in Comparative Example 1,
The antistatic and static neutralizing effects were investigated using the following methods. 2
After applying -5000 V for a predetermined time (1 second) to a rubber test piece of 0 mm x 80 m layer x 2 mm by corona discharge, the change in potential on the surface of the rubber test piece was immediately measured with a surface electrometer using a sensitive plate probe. The results are shown in FIG.

Example 2 A pressure roller for a thermopressure fixing device having the silicone rubber composition of the present invention as an elastic layer was manufactured as follows.

Liquid A of the silicone rubber composition of Example 1 was placed in a cylindrical mold in which a siloxane-based primer coated pressure roller core bar made of stainless steel with an outer diameter of 10 mm was preheated to 130°C. Liquid B was mixed uniformly at a weight ratio of 100:100, and the resulting mixed liquid was injected and held at the same temperature for 10 minutes to harden. The silicone rubber coated pressure roller taken out from the mold after curing has an outer diameter of 1
The thickness of the silicone rubber coating layer was 3II11.

A heat fixing type fixing device shown in FIG. 1 was installed using the pressure roller obtained above, and a continuous sheet feeding fixing process test was conducted under the following conditions. The fixing roller 1 used was one in which an aluminum core metal having an outer diameter of 20 ts was coated with a tetrafluoroethylene resin in a layer thickness of 15 g+s.

[Fixing conditions] Fixing roller surface control temperature: 150'0 Tightening pressure between fixing roller and pressure roller: 6 kgf Paper passing: A4 size transfer paper (plain paper) on which the unfixed toner image of the test pattern was formed Paper passing Speed: 4 sheets/min As a result, even after passing 10,000 sheets, no toner adhesion stains occurred on the pressure roller surface, and no toner adhesion to the fixing roller surface. In addition, there were no image quality defects, no image stains, and no image omissions, and good image quality and fixing properties were maintained. In particular, there was no occurrence of paper wrapping around the rollers, no paper jams, no paper curls, no paper wrinkles, and good conveyance was maintained without any jam troubles. Changes in the shape of the roller were also extremely small, and the dimensional stability was also good.

Comparative Example 2 A pressure roller was manufactured in the same manner as in Example 2, except that Liquid C and Liquid D prepared in Comparative Example 1 were used.

As a result, after 10,000 sheets were passed, toner adhesion to the pressure roller surface increased, poor image quality, 2 image stains, 9 missing images, 9 paper wrinkles,
Paper jams, 9 paper curls, etc. occurred.

[Effects of the Invention] The present invention provides a silicone rubber composition that contains a porous inorganic fine powder having micropores supporting a silicone polyether copolymer having a polyoxyalkylene group in its side chain. It is possible to prevent or suppress charging of objects.

When the composition of the present invention is used, for example, as an elastic surface layer of a fixing roller of an image fixing device in an image forming apparatus such as an electronic copying machine and a fixing roller such as a pressure roller, charging on the surface of the roller can be prevented or suppressed. As a result, the amount of toner adhering to the roller surface is significantly reduced, preventing image defects such as offset and contamination due to toner adhesion to the roller surface, as well as reducing conveyance problems such as paper wrapping and curling. is also resolved. In addition, since the silicone polyether copolymer supported on the porous inorganic fine powder having micropores is gradually supplied into the silicone rubber, good antistatic effect and antistatic effect are maintained over a long period of time. As a result, transportation problems such as contamination due to toner adhesion to the roller surface, paper wrapping around the roller, and paper curling are prevented for a long period of time, making it possible to dramatically improve the durability of the roller.

Note that the silicone rubber composition of the present invention may be used as a covering material for both the fixing roller and the pressure roller among the fixing rollers, or either the fixing roller or the pressure roller may be used.

[Brief explanation of the drawing]

FIG. 1 shows a longitudinal sectional view showing an embodiment of the device of the present invention,
FIG. 2 shows an example of the change over time in the surface potential of the silicone rubber surface.

Claims (4)

[Claims] (1) A silicone rubber composition characterized by containing a porous inorganic fine powder having micropores supporting a silicone polyether copolymer having a polyoxyalkylene group in a side chain. (2) A molded article formed from the silicone rubber composition according to claim 1. (3) An elastic rotating body comprising an elastic body having a surface layer formed from the silicone rubber composition according to claim 1. (4) In a fixing device that heats and presses an unfixed toner image formed on an image carrier by transporting the image carrier between at least a pair of rollers, the surface layer of at least one of the rollers is made of an elastic material. A fixing device characterized in that the elastic body is formed of the composition according to claim 1.