JPS6359146B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a heat-curable silicone rubber roller that prevents charging.

Recently, the demand for copiers, line printers, etc. has been increasing, but their fixing parts use fluororesin coated rollers or silicone rubber rollers as heat rollers, while silicone rollers are used as back-up rollers. It is common that When a copy paper on which a toner image has been transferred passes through these fixing sections, the copy paper becomes charged due to friction between the roller and the copy paper, resulting in a problem in that the paper gets wrapped around.

One solution to this problem is to remove the static electricity generated by friction by bringing a metal brush or metal wire into contact with the roller, but this method requires accessories such as metal brushes, which increases costs. There was a space problem.

There are also methods of adding antistatic properties to the roller itself, such as adding conductive substances such as carbon black to silicone rubber, or adding organic antistatic agents, but the former has the disadvantage that it is limited to black. The latter had the problem of compatibility between the silicone rubber and the antistatic agent, and although the initial properties were sufficiently satisfactory, it lacked long-term reliability.

Furthermore, although there is no problem when used at low temperatures, there is a drawback that when used at high temperatures, the added organic antistatic agent scatters from the rubber and becomes ineffective. These drawbacks are particularly severe with regard to heat-curing silicone rubber, and although heat-curing silicone rubber has better tensile strength and creep properties than room-temperature-curing silicone rubber, it is not used for these reasons. There was a desire to develop antistatic technology for heat-curable silicone rubber.

Therefore, the present inventors first added a certain fluorine compound to heat-curable silicone rubber, molded and crosslinked it, and then immersed it in silicone oil to create a non-static heat-curable silicone rubber roller. I discovered that I could obtain this and filed an application.

However, since this additive is very expensive, the cost of the roller increases.

The inventors of the present invention conducted various studies to resolve these difficulties, and found that the roller's antistatic treatment only needs to be applied to the surface layer, and the entire rubber does not need to be antistatically treated. When only the surface layer was formed using the above composition, it was found that costs could be reduced without deteriorating performance.

The present invention has been made based on such knowledge, and the silicone rubber is coated with (a) C _{8 F} on the surface of a heat-curable silicone rubber roller having a volume resistivity of 5×10 ¹⁴ Ω-cm or more. ₁₇ SO ₃ Na and An antistatic rubber layer is provided on the surface of the silicone rubber roller by coating and crosslinking a composition prepared by adding and mixing a mixture of (b) organic peroxide in a ratio of about 1:1 (weight ratio). This invention provides a rubber roller that is electrically chargeable.

The volume resistivity used in the present invention is 5×10 ¹⁴ Ω−
Heat-curing silicone rubber of cm or more is mainly composed of dimethylpolysiloxane or methylphenylpolysiloxane, with reinforcing agents such as fumed silica, titanium white, Bengara, silica, etc. Examples include Toshiba Silicone's TSE220-6u and TSE220-5u, and Shin-Etsu Chemical's KE765.

C ₈ F ₁₇ SO ₃ Na used in the present invention and A mixture of approximately 1:1 (weight ratio) is available from Tohoku Fertilizer Co., Ltd.
It is commercially available as EFTOP501. This mixture is a homogeneous yellow paste-like mixture obtained by stirring both compounds at room temperature in a weight ratio of about 1:1, and phenomena such as layer separation do not occur even when left at room temperature. C ₈ F ₁₇ SO ₃ Na is an anionic white powdery compound that exhibits an antistatic effect when used alone, but because of its low compatibility with silicone rubber etc., it has very poor dispersibility during addition and kneading. When the silicone rubber material thus obtained is used as a roller, it has the disadvantage that the compound oozes out onto the surface of the roller. on the other hand, is a nonionic compound that has good compatibility with C ₈ F ₁₇ SO ₃ Na, and when these two compounds are stirred at room temperature, they form a homogeneous mixture. It has very good properties and does not ooze out during use. The amount of this substance added is 0.5 per 100 parts by weight of silicone rubber.
~7.0 parts by weight is good; if it is less than this, there is no antistatic effect, and if it is more than this, the cost will increase, so it is not preferable.

The heat-curable silicone rubber in the present invention includes
2.4-An organic peroxide such as dichlorobenzoyl peroxide or dicumyl peroxide is added to cause crosslinking. The amount of organic peroxide added is usually 0.1 to 3 parts by weight per 100 parts by weight of silicone rubber.

The non-static roller of the present invention is manufactured by first coating a core metal such as aluminum, stainless steel, or iron with silicone rubber that is not antistatically treated and containing only organic peroxide, and then crosslinking it. A regular roller is manufactured by grinding it to the dimensions of .

Subsequently, a composition obtained by blending silicone rubber with a fluorine compound and an organic peroxide and subjected to antistatic treatment is coated thereon to a thickness of 0.5 mm or more and crosslinked. If it is then immersed in silicone oil, a higher antistatic effect can be obtained. Thereafter, it is ground to a predetermined size to obtain a non-chargeable roller. Note that it is preferable that the same silicone rubber be used for the non-static roller and the antistatic layer provided thereon in terms of adhesion.

Next, an example will be described.

Example: 100 parts by weight of TSE220-5u (silicone rubber), 1 part by weight of Bengara Masterbat, and 0.4 parts by weight of dicumyl peroxide were mixed to make a 5 mm sheet, which was wrapped around a stainless steel mandrel with a diameter of 45 mm. Primary vulcanization was performed at 150°C for 30 minutes. This was followed by polishing to obtain a roller with a diameter of 50 mm. On top of this, 100 parts by weight of TSE220-5u (silicone rubber), 1 part by weight of Bengara master batch, EFTOP501
0.8 made by adding and mixing 1 part by weight (fluorine compound)
A sheet of mm thick was wound around it, and secondary vulcanization was performed at 200°C for 4 hours. Thereafter, it was polished to obtain a non-static roller of the present invention having a diameter of 51 mm. This roller is used as a backup roller in a copying machine to adjust the fusing temperature.
185℃, peripheral speed 115m/sec, load between rollers 60Kg/
When copies were made under conditions of 330 mm and nip width of 6 mm, the amount of charge on the copy paper was 200 V, which was the same as if the entire rubber had been treated with antistatic treatment.

On the other hand, those without antistatic treatment
It was 520V. Furthermore, if the entire rubber was treated to prevent static electricity, the cost would increase by 15%, but if only the surface layer was treated to prevent static electricity, the cost increase could be reduced to 2%.

Claims (1)

[Claims] 1. A method for imparting antistatic properties to a heat-curable silicone rubber roller having a volume resistivity of 5×10 ¹⁴ Ω-cm or more, in which the silicone rubber contains (a)
C ₈ F ₁₇ SO ₃ Na and 1. An antistatic roller comprising an antistatic rubber layer formed by adding and mixing (b) an organic peroxide and crosslinking the mixture in a ratio of approximately 1:1 (weight ratio). 2. The antistatic roller according to claim 1, wherein the antistatic rubber layer has a thickness of 0.5 mm or more.