JPH0653400B2 - Method for producing white antistatic rubber roll - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention makes it easy to read characters and symbols from a manuscript by using a method for producing a white antistatic rubber roll, particularly by using a white silicone rubber layer on the surface thereof. The present invention relates to a method of manufacturing a white antistatic rubber roll that is useful as a reading roll of a facsimile.

(Prior Art) Conventionally, acrylic rubber, butyl rubber, and butyl rubber have been excellent in compression set, temperature dependence, weather resistance, and heat resistance of paper feed rolls in various copying machines and communication equipment.
Heat-resistant and rigid rubber such as nitrile rubber, especially silicone rubber rolls are widely used.

However, mainly describing the silicone rubber roll below, this silicone rubber roll uses an electrically conductive carbon black as a filler in order to prevent paper wrapping and adhesion of paper powder due to static electricity, and imparts an antistatic property to the black color. However, when this is used as a reading roll of a facsimile, for example, there is a disadvantage that the characters and symbols from the original are difficult to read.

Therefore, for this type of rubber roll, the filler is not oxidized, white metal oxide such as zinc oxide is used, and the use of a white conductive rubber roll in which titanium oxide or the like is added as a white pigment is also considered, Compared to carbon black, these white metal oxides and white pigments are 2-3
Since it is twice as expensive, if the entire rubber roll is made of a conductive white material, the roll becomes extremely expensive, which is not economical. Therefore, the present inventors defined it as a two-layer structure having a conventionally known black conductive silicone rubber layer using carbon black and a white conductive silicone rubber layer using the above metal oxide and white pigment. Focusing on the fact that an inexpensive rubber roll can be obtained by doing so, we considered making this white conductive silicone rubber layer by press molding. However, this method was used in the half mold with a cavity matching the roll shape. 2 around metal shaft such as aluminum, stainless steel, brass, phosphor bronze, chrome plated iron
Place or wrap a predetermined amount of uncured carbon black-containing black conductive rubber that has been divided into pieces to cure by heating and pressing,
Then, after removing from the cooling latter half mold and scraping the parting line generated at the boundary of the half mold (deburring), grinding by perfect circle processing (eg 30 mm ± 20 μm), and then another half mold Among them, there is a drawback that the process is complicated and there is a lot of loss and the raw material yield is bad because the white conductive silicone rubber is provided and the deburring and polishing is performed again.

(Structure of the Invention) The present invention relates to a method for producing a white antistatic rubber roll that solves such disadvantages, in which a carbon-containing black conductive rubber layer is provided on a shaft, and a white metal oxide-containing white layer is provided on the surface. It is characterized in that a conductive silicone shrinkable rubber tube is covered, and then heated to shrink the shrinkable rubber tube and bring it into close contact with the black conductive rubber layer.

That is, the present inventors have variously studied the surface whitening method of the black conductive rubber roll, on the surface of the black rubber roll formed using the black conductive rubber using the carbon black made by the conventionally known method, Tin oxide and / or zinc oxide is used as a conductivity-imparting agent, and a thermoplastic material is added to a white conductive silicone rubber composition obtained by using titanium oxide as a white pigment to form a heat-shrinkable composition. The surface of the black conductive rubber roll can be easily covered by coating the tube molded by extrusion molding and then heat-treating the tube so that the shrinkage of the heat-shrinkable tube causes the tube to adhere to the surface of the black conductive rubber roll. It is found that whitening is achieved, and this makes it easy to extrude this white conductive silicone shrink rubber tube. And we have completed the present invention to confirm that it is possible to obtain white chargeability preventing rubber roll to be relatively thin so obtained as economically advantageously purposes also.

The white antistatic rubber roll produced by the method of the present invention is produced by coating the white conductive silicone shrinkable rubber tube on the black conductive rubber layer of the rubber roll using the black conductive rubber using carbon black as described above. However, this black conductive rubber roll may be manufactured by a conventionally known method.

Therefore, this black conductive rubber roll is obtained by applying a primer to the surface of a shaft made of aluminum, stainless steel, chrome-plated iron, or the like, and then using a commercially available silicone raw rubber 100 containing dimethylmethylvinylpolysiloxane as a main material. 5.0 to 100 parts by weight of carbon black, especially acetylene black or Ketjenblack, and dicumyl peroxide, 2,
Obtained by adding 0.3 to 5.0 parts by weight of an organic peroxide-based vulcanizing agent such as 5-bis (t-butylperoxy) 2,5-dimethylhexane, dicumyl peroxide, etc. and mixing them uniformly. Silicone rubber compound 170-190 ℃
It may be produced by press-molding under the condition of 15 to 50 kg / cm ² and then polishing and finishing with a polishing machine or the like.

According to the method of the present invention, the roll surface of the black rubber roll thus produced is coated with the white conductive silicone shrinkable rubber tube. This white conductive silicone shrinkable rubber tube is used to manufacture the above black conductive rubber roll. A powder of tin oxide and / or zinc oxide as a white conductivity imparting agent and titanium oxide as a white pigment is added to 100 parts by weight of a silicone raw rubber containing dimethylmethylvinylpolysiloxane as a main material similar to that used in
To 250 parts by weight and uniformly mixed to obtain a silicone rubber compound, which is further kneaded with 5 to 30 parts by weight of a thermoplastic resin such as polyethylene, polypropylene, polyacryl, polycarbonate, ABS or silphenylene. The composition thus obtained is allowed to cool to room temperature, and an organic peroxide vulcanizing agent, for example, 2,4-dichloroperoxide is added in an amount of 0.5 to 3.0 parts by weight and molded into a tube by an extrusion molding method. After that, it may be obtained by drawing under hot air or heating with steam etc. and quenching, and the diameter of this tube must be larger than the outer diameter of the black rubber roll covered with this tube. However, it is necessary to bring this product into close contact with this black rubber roll at the time of heat shrinking after the fact, so it is necessary to make direct contact before stretching during extrusion molding. 5 but also than the outer diameter of the black rubber roll
It should be 30% smaller.

In the method of the present invention, the white conductive silicone shrinkable rubber tube thus produced is coated on the black conductive rubber roll obtained by the above-mentioned method. Since it also has a large diameter, it can be easily coated. When the silicone rubber roll coated with the tube is heated to 150 ° C. or higher with hot air or flame, the tube abruptly contracts to the diameter of the extruded product before stretching, This tube has a diameter at the time of extrusion molding before stretching that is smaller than the outer shape of the black conductive rubber roll, and due to this contraction, it comes into close contact with the surface of the black conductive rubber roll. It is possible to easily and surely obtain the white antistatic rubber roll.

According to the method of the present invention, the shrinkage of the white conductive silicone shrinkable rubber tube causes the shrinkable tube to be completely adhered to the black conductive rubber roll, thus achieving the purpose of whitening the surface of the black conductive rubber roll. However, it is not particularly necessary to use an adhesive between the layers, since no slippage due to the displacement stress between the layers occurs at all. However, the white antistatic rubber roll thus obtained may be exposed to harsh high temperatures, so apply an adhesive to the surface of the black conductive rubber roll before coating this white conductive silicone shrink rubber tube. The white conductive silicone rubber layer and the black conductive rubber layer may be adhered to each other with an adhesive, and the adhesive may be a vinyl group-containing organopolysiloxane and a hydrogen atom (≡SiH) bonded to a silicon atom. (Bond)) in 100 parts by weight of an addition reaction type siloxane composition consisting of an organohandrodiene polysiloxane and a platinum-based catalyst, (CH ₃ ) ₃ SiO _0.5 unit, (CH ₃ ) ₂ (CH ₂ ═CH ) consisting of _{SiO 0.5} units and SiO ₂ units, and the so-called MQ siloxane was added 5.0 to 30 parts by Olga Carbon black as conductive agent to the siloxane-based adhesive, may be obtained by adding an appropriate amount of white conductive metal oxide. If too much adhesive is added, the roll surface will be contaminated during roll manufacturing and use, and the resulting roll will cause read errors and stains on the paper surface. Care should be taken to reduce the number as much as possible.

Next, examples of the present invention will be given.
The viscosity is a value measured at 25 ° C.

Example Stainless steel steam SU having a diameter of 10 mm and a length of 400 mm
The surface of 304 shaft was diluted with 10% of Primer No. 4 [trade name of Shin-Etsu Chemical Co., Ltd.] with toluene, brushed, air-dried for 30 minutes, and then baked at 150 ° C. for 5 minutes. .

Then, on this shaft surface, 100 parts of methyl vinyl polysiloxane containing 0.3 mol% of vinyl siloxane unit and having a viscosity of 1,000,000 cS and 25 parts of acetyl black and 2,
A silicone rubber compound obtained by adding 1.2 parts of 5-bis (t-butylperoxy) 2,5-dimethylhexane and mixing it uniformly was press-molded and polished with a grinder to give an outer diameter of 30.
A black conductive silicone rubber roll having a diameter of mmφ and a length of 360 mm was prepared.

Next, to 100 parts of the above-mentioned methyl vinyl polysiloxane, 50 parts of tin oxide as a white conductive additive, 150 parts of titanium oxide powder [manufactured by Ishihara Sangyo Co., Ltd.] as a white pigment and 15 parts of a polycarbonate resin were added. , 0.8 parts of 2,4-dichlorobenzoyl peroxide was added to 100 parts of the silicone rubber compound obtained by evenly mixing with a two-roll roller at 220 ° C. and allowing to cool to room temperature. Use an extruder to make a silicone rubber tube with an inner diameter of 27 mm and an outer diameter of 28 mm.
One side of the aluminum pipe was fixed in a sealed state and hot air of 200 ° C was blown from the other end at 10 kg / cm ² for 10 minutes. The silicone tube was stretched to fill the inner wall of the aluminum, so the blowing was stopped. Was immersed in water for 30 minutes for rapid cooling, and after water cooling, the silicone rubber tube was removed from the aluminum pipe. A white conductive silicone shrinkable rubber tube with an inner diameter of 32.2 mm and an outer diameter of 33 mm was obtained.
After being cut into pieces and coated on the black conductive silicone rubber roll obtained above, and then heated at 200 ° C. for 30 minutes, the shrinkable rubber tube shrinks and adheres to the black conductive silicone rubber roll, thereby obtaining the desired white charge. The anti-static rubber roll could be obtained.

The white antistatic rubber roll thus obtained has the physical property that the electric resistance between the central portion and the shaft is 5 × 10 ⁶ Ω. It was shown that the letters and symbols from were also legible.

This roll is a commercially available copying machine (Fuji Xerox 48
When set to 70) and tested, there were no problems even with 100,000 sheets.

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Claims (2)

[Claims] 1. A carbon-containing black conductive rubber layer is provided on a shaft, and a white conductive oxide-containing white conductive silicone shrink rubber tube is coated on the surface of the shaft and then heated to shrink the shrink tube to blacken it. A method for producing a white antistatic rubber roll, which comprises closely contacting with a conductive rubber layer. 2. The method for producing a white antistatic rubber roll according to claim 1, wherein the white conductive silicone shrinkable rubber tube has a thickness of 0.3 to 2.0 mm.