JPH0261750B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a silicone rubber roller used in a heat fixing section. [Technical background of the invention and its problems] Conventionally, heat rollers or press rollers used in the heat fixing section of electronic copying machines, etc. include (1) those coated with fluororesin, and (2) shrinkable rollers made of fluororesin. Known examples include (3) a tube coated on a rubber roller, (3) a metal cylinder coated with a heat-curing silicone rubber, and (4) a metal cylinder coated with a condensation reaction room-temperature cure silicone rubber. . However, these had the following drawbacks. (1) Fluorine resin coated rollers result in poor image quality. (2) If a rubber roller is coated with a fluororesin shrink tube, the roller will be expensive. (3) Heat-curable silicone rubber rollers have poor release properties from toner, making it necessary to use an oil coat fixing method. (4) Condensation reaction room temperature curing silicone rubber rollers have a large narrowing of the outer diameter and a large amount of creep, so it is necessary to release the pressure. In general, fusers that are oil-less and do not require pressure release have the advantage of being able to significantly reduce costs and being technically easier to design. For this purpose, the two requirements are that the rubber material of the roller has excellent releasability from the toner and that the amount of creep is small. As a rubber material that meets these requirements, condensation reaction room temperature curing silicone rubber is suitable in terms of releasability from toner, and addition reaction room temperature curing silicone rubber and heat curing silicone rubber are suitable as rubbers with a small amount of creep. Rubber is known, but no rubber material that satisfies both properties has been known. [Object of the Invention] The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a silicone rubber roller for a heat fixing section that has excellent releasability from toner and does not require pressure release. . [Summary of the Invention] The silicone rubber roller of the present invention mainly includes a base oil made of dimethylpolysiloxane end-blocked with vinyl groups, an inorganic filler, and a silicone oil with a viscosity (at 25°C, the same hereinafter) of 1 million centistokes or more. It is characterized in that a roll core shaft is coated with an addition reaction room temperature curing silicone rubber composition obtained by crosslinking and curing a mixture. As the base oil used in the present invention, addition reaction linear dimethylpolysiloxane with both ends capped with vinyl groups is suitable, and its viscosity is 1000~1000~
10000 centistokes is preferred. If it is less than 1,000 centistokes, the mechanical properties of the cured rubber will be poor, and if it exceeds 10,000 centistokes, the viscosity of the compounded rubber will become too high, causing problems in molding. In the present invention, the inorganic filler has a particle size of
It is preferable to mix and blend silica with a particle size of 50 mμ or less and a specific surface area of 100 m ² /g or more, and silica with a particle size of 1 μ to 50 μ and a specific surface area of 10 m ² /g or less. A good mixing ratio is former:latter = 25/75 to 75/25. Further, the appropriate blending amount of these components is 10 to 35 parts by weight per 100 parts by weight of the base rubber. If it is less than this value, the physical properties will be poor, and if it exceeds this value, the viscosity will be high and at the same time the releasability from the toner will be poor. In the present invention, the silicone oil used has a viscosity of 1 million centistokes or more. The object of the present invention cannot be obtained with oils having a viscosity less than this value, that is, commonly used silicone oils having a viscosity of about 100 to 1000 centistokes. The amount of this compound in the composition is 1 to 1.
An amount accounting for 10% by weight is suitable. If it is less than 1% by weight, the mold releasability will be poor, and if it exceeds 10% by weight, the physical properties will deteriorate. Examples of the crosslinking agent used in the present invention include methylhydrodiene polysiloxane, and the hydrogen/vinyl group of the crosslinking agent is equal to the vinyl group weight of the base rubber.
1 to 5 are preferred. Catalysts that can be used in the present invention include platinum catalysts, which are added in conventional amounts. In addition to the above-mentioned components, it is also possible to add petals etc. for coloring. In the present invention, after mixing the above-mentioned components,
The silicone rubber roller of the present invention is produced by pouring into a cylindrical roll mold in which a metal core bar that has been degreased, blasted, and coated with a primer is placed at the center, and left to stand at room temperature or cured by heating. [Embodiments of the Invention] Examples Next, examples of the present invention will be described. To 100 parts by weight of addition reaction dimethylpolysiloxane with a viscosity (25°C) of 1000 to 10000 centistokes,
20 parts by weight of silica, 5 parts by weight of silicone oil having a viscosity of 1.5 million centistokes, a platinum catalyst and a crosslinking agent were blended to obtain a mixture having a viscosity of 480 poise. This was poured into a roll mold and left to stand at room temperature to harden, producing a heat roller with an outer diameter of 40 mmφ and a wall thickness of 0.5 mm, and a press roller with an outer diameter of 40 mmφ and a wall thickness of 5 mm.
The mechanical properties of the rubber part of the obtained rubber roller were tensile strength of 33 kg/cm ² , elongation of 250%, and hardness of 34 ((JIS-
A), tear strength 4Kg/cm, compression set rate 6%
(room temperature) (25% at 180°C for 22 hours). These rollers were brought into contact with each other, the temperature of the heat roller was adjusted to 180° C.±3° C., and a copying test was conducted by applying a load of 80 kg between the rollers. The results were as shown in the table below. Comparative Example 1 in the table is a mixture of 100 parts by weight of condensation reaction room-temperature-curing polysiloxane, 20 parts by weight of silica, 15 parts by weight of silicone oil with a viscosity (25°C) of 100 centistokes, a crosslinking agent, and a catalyst. In Comparative Example 2, a heat-curable silicone rubber roller was heated at 180°C.
This is an example in which the sample was used after being immersed in dimethyl silicone oil. Comparative Example 3 is an example in which the silicone oil in Example 1 was changed to a viscosity of 100 centistokes, and the other formulations were the same as in Example 1. Furthermore, as Comparative Example 4, an attempt was made in which the addition reaction dimethylpolysiloxane of Example 1 was changed to a condensation reaction cold-curing polysiloxane, and the other ingredients were the same as those of Example 1. A large amount of silicone oil had bled out and was unusable.

【table】

[Table] - Check for dirt on the surface.
(Note)…A jam occurred after passing approximately 2000 sheets.
[Effects of the Invention] As is clear from the above examples, the silicone rubber roller of the present invention has excellent mold releasability, so an oil-less method can be applied, and it can also be used without pressure release.

Claims (1)

[Claims] 1. A mixture mainly composed of a base oil consisting of dimethylpolysiloxane end-blocked with vinyl groups, an inorganic filler, and a silicone oil having a viscosity (at 25°C) of 1 million centistokes or more is cross-linked and cured. A silicone rubber roller for a heat fixing section, comprising a roll core shaft coated with an addition reaction room temperature curing silicone rubber composition. 2 The inorganic filler has a particle size of 50 mμ or less and a specific surface area of
The silicone rubber roller for a heat fixing section according to claim 1, which is a mixture of silica having a particle size of 100 ^{m 2} /g or more and silica having a particle size of 1 to 50 μm and a specific surface area of 10 m 2 /g or less. 3 The amount of silicone oil blended is 1 to 10 in the composition.
The silicone rubber roller for a heat fixing unit according to claim 1 or 2, wherein the amount is % by weight.