JPS6334574A - Production of heat fixing roller - Google Patents

Abstract

PURPOSE:To prevent the sagging and local building-up of a fluoroplastic dispersion at roller ends by blowing gas to both ends of a rubber layer at the time of spraying the fluoroplastic dispersion CONSTITUTION:A rubber-like compsn. such as silicone rubber is coated on a metallic core shaft 1 and is cured to form a rubber layer 2. The surface thereof is ground. The fluoroplastic dispersion 4 is then uniformly spray-coated thereto while the core shaft 1 is kept rotated and a spray gun 3 is moved in parallel with the central axial direction. Two pieces of nozzles 5, 6 to blow air are disposed near both ends of the roller at this time and the air is blown to both ends of the roller. After the dispersion is spray-coated by the prescribed amt., this state is continued and the coating is dried to about the extent at which the film does not flow. The coating is thereafter subjected to predrying and baking by which the fluoroplastic-coated silicone roller is obtd. The sagging and local building-up of the fluoroplastic dispersion are not observed on the surface of the resulted rubber roller.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method of manufacturing a heat fixing roller used in a heat fixing section of an electronic copying machine or the like.

(Prior Art) Conventionally, heat rollers and press rollers used in heat fixing units of electronic copying machines and the like have generally used metal cylinders coated with silicone rubber, fluororubber, or the like. In order to improve the releasability of such rollers from the toner, it is common practice to pre-impregnate a silicone rubber material with silicone oil or to provide a fluororesin layer on the rubber layer.

Among these rollers, rollers with a fluororesin layer provided on a silicone rubber layer are cheaper than fluororubber rollers, and also have better toner resistance than rollers with silicone rubber impregnated with silicone oil. It has the advantages of excellent mold releasability and easy maintenance, and is widely used.

(Problems to be Solved by the Invention) Methods for manufacturing rollers with a fluororesin layer provided on a silicone rubber layer include a method of applying fluororesin powder by electrostatic coating and baking it; Methods such as coating a heat-shrinkable tube or coating and baking a fluororesin dispersion are known, but among these methods, the method of coating and baking a fluororesin dispersion cannot form a uniform thin film. It has attracted attention in recent years because it requires relatively simple equipment.

In this method, a rubber layer is placed on the core, a fluororesin dispersion is applied while rotating the core, the dispersion medium is then dried and removed, and the fluororesin thin film is formed by baking at high temperatures. .

However, in this method, when coating the fluororesin dispersion, it is cast onto both ends of the rubber layer, which requires a lot of work to remove the excess fluororesin coating after firing, and it is often difficult to remove the fluororesin dispersion during firing. There was a problem in that the coating in this area would crack.

The present invention has been made to solve these conventional problems, and provides a method for manufacturing a heat fixing roller that does not form an excess film by casting a fluororesin dispersion on both ends of a rubber layer. The purpose is to

"Structure of the Invention" (Means and Effects for Solving the Problems) The method for manufacturing a heat fixing roller of the present invention is to coat a roller core shaft with a rubbery composition and cure it to form a rubber layer, and then rotate the core shaft. In the heat fixing roller manufacturing method, in which a fluororesin dispersion is sprayed onto the rubber layer and baked to form a fluororesin film, the fluororesin dispersion is sometimes sprayed onto both ends of the rubber layer. It is characterized by being sprayed with

Examples of the fluororesin dispersion used in the present invention include TFE (tetrafluoroethylene), PFA (perfluoroalkoxy), and FEP (tetrafluoroethylene-hexafluoropropylene).

Further, the gas used in the present invention may be air or an inert gas.

(Function) In the present invention, when the fluororesin dispersion is sprayed, air is blown onto both ends of the rubber layer, so the fluororesin dispersion is prevented from flowing toward the ends. This prevents the roller from dripping or locally rising at the end of the roller.

(Example) Examples of the present invention will be described below.

First, a rubbery composition such as silicone rubber is coated and cured on the metal core shaft 1 via a primer to form a rubber layer 2.
Grind its surface. Thereafter, the fluororesin dispersion 4 was uniformly sprayed while rotating the core shaft 1 and moving the spray gun 3 in parallel in the direction of the core shaft as shown.

At this time, two nozzles 5.6 for blowing air were placed near both ends of the roller to blow air to both ends of the roller.

゛ After spraying the PTFE dispersion for a predetermined amount of time, this state was continued until the coating was dried to the extent that it would not spread.

Thereafter, preliminary drying was performed and further baking was performed to obtain 1 q of fluororesin-coated silicone rubber roller. On the surface of the rubber roller obtained in this example, no dripping of the fluororesin dispersion or localized canning was observed, and the end of the roller after firing was smooth with no cracks.

[Effects of the Invention] As explained above, according to the present invention, there is no sagging or swelling of the fluororesin dispersion at the end of the roller during coating with the fluororesin dispersion, and therefore it is possible to remove these in the return process. This is not necessary, and it is possible to obtain a fluororesin-coated heat fixing roller with a good surface condition without cracking at the edges even during firing.

[Brief explanation of the drawing]

The drawings are diagrams schematically showing a method of manufacturing a heat fixing roller according to the present invention. 1...Metal core shaft 2...Rubber layer 3...Spray gun 4...・
...Fluororesin dispersion 5.6...
・Air nozzle

Claims (1)

[Claims] (1) A rubbery composition is coated and cured on the roller core shaft to form a rubber layer, and while the core shaft is rotated, a fluororesin dispersion is spray-painted on this rubber layer and baked to form a fluororesin coating. 1. A method for manufacturing a heat fixing roller, characterized in that when the fluororesin dispersion is sprayed, gas is sprayed onto both ends of the rubber layer.