JPH04158011A - Manufacture of rubber roller covered with fluororesin tube - Google Patents

Abstract

PURPOSE:To enable a rubber layer and a fluororesin tube to be adhered securely by heating and then expanding in a close state liquid rubber injected between a cylindrical mold and a rubber roller, and uniformly pressing a fluororesin tube by the expansion pressure from the outside thereof. CONSTITUTION:Aluminum hollow core shaft 1 is covered with HTV silicone rubber 2, and the inner part of a rubber roller 3 obtained by grinding is subjected to etching, and then an adhesive applied PFA tube 4 is put around it. The rubber roller 3 is cocentrically placed in an iron cylindrical mold 5 and then stationarily secured therein by means of a plug 6, and further liquid silicone rubber 7 is injected between the cylindrical mold 5 and the rubber roller 3. Then, it is fixed mechanically in its upper and lower part and the inner part of the mold and then heated by making the mold inner part a close state. This is then left at room temperature for contracting the rubber material, and thereafter demolding it. The tubular silicone rubber wound round the outer periphery of the PFA tube 4 is broken and separated away therefrom, and thereby a silicone rubber roller can be obtained which is excellently covered with a PFA tube.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a silicone rubber roller coated with a fluororesin tube, which is suitable for a heat roller or the like used in an octopus fixing device of an electronic copying machine.

(Prior art) Various methods have been developed to provide a fluororesin layer with excellent releasability from toner on the surface of a silicone rubber roller with excellent heat resistance. There are four possible methods:

The first method is to apply a charged powder coating of fluororesin such as PFA (perfluoroalcoquine resin) to the surface of a silicone rubber roller that has been ground to a predetermined size by providing a rubber layer on a metal core shaft using a conventional method. After that, it is finished by firing.

In the second method, a silicone rubber roller obtained in the same manner as in the first method is sprayed with PTFE (polytetrafluoroethylene resin) dispersion and then finished by firing.

In the third method, a silicone rubber roller obtained in the same manner as the first and second methods is coated with a fluororesin tube such as PFA, and then heated and bonded.

The fourth method is the same method that has been applied to the manufacturing of pressure rollers, and uses a cylindrical mold into which a fluororesin tube such as PF^ is inserted in advance. By injection molding liquid silicone rubber, the rubber layer is formed and the fluororesin tube is covered at the same time.
It is manufactured without the need for grinding.

(Problem to be solved by the invention) However, each of these methods has its drawbacks.
In particular, it was difficult to manufacture heat rollers with thin rubber layers.

For example, in the roller obtained by the first method, the rubber layer suffers severe thermal deterioration due to the high temperature during firing, making it difficult to obtain a product that can withstand practical use.

The second method has the disadvantage that it requires rapid heating, and as a result requires a large amount of equipment.

In the case of the third method, gas and air are generated from the inside and surface of the rubber layer during heating after coating the tube, and these gases and air tend to accumulate at the boundary between the rubber layer and the tube and form bubbles. It was difficult to obtain a product with a smooth surface.

In addition, in this method, a tube with a thickness of 200 to 700 μm is generally used, and as a result of coating a relatively thick tube in this way, the original elasticity of silicone rubber is lost and the hardness of the roller becomes high. There was a problem that it became difficult to remove the nip width. However, if the thickness of the shrinkable tube is made thinner than this, the shrinkage rate will decrease, the adhesion with the rubber layer will deteriorate, and the durability will decrease.
There was also the problem that wrinkles occurred during shrinkage, resulting in uneven film thickness.

In the case of the fourth method, when liquid silicone rubber is injected into the mold, air is likely to be drawn in, and air may accumulate inside the rubber layer or at the boundary between the rubber layer and the tube as in the third method, creating air bubbles. It was easy to form. Therefore, the thickness of the rubber layer is thin like a heat roller, and generally 11
A roller having a diameter of n11 or less and approximately 0.2 to 0.7 mm is not suitable for manufacturing a roller.

It can also be used when manufacturing a so-called inverted crown-shaped roller, which is often used as a heat roller and has an outer diameter at the center that is smaller than the outer diameter at both ends to prevent paper wrinkles during paper passing. , it was difficult to apply it due to the difficulty of demolding.

The present invention has been made to solve the problems of such conventional methods. There is no risk of thermal deterioration of the roller rubber layer, and it can be manufactured without the need for extensive equipment, and it is possible to coat the fluororesin tube with a smooth surface even on the thin roller rubber layer. The purpose is to provide a method for manufacturing a fluororesin tube-covered roller that has sufficient adhesion between the rubber layer and the fluororesin tube and is applicable even if the roller has an inverted crown shape. .

[Structure of the Invention] (Means for Solving the Problems) That is, the method for manufacturing a fluororesin tube-covered roller of the present invention includes fitting a fluororesin tube onto a rubber roller having a rubber layer on a metal core shaft, and is inserted into a cylindrical mold having an inner diameter larger than its outer diameter and held concentrically, then liquid rubber is injected between the cylindrical mold and the rubber roller, and then the inside of the mold is It is characterized in that the liquid rubber is engraved by heating while being kept in a sealed state, and the fluororesin tube and the rubber layer of the rubber roller are bonded under pressure by the engraving pressure, and then the mold is removed.

In the present invention, it is possible to apply uniform pressure to the roller surface, so even tubes that are thinner than conventionally used fluororesin tubes, for example, with a film thickness of 100 μm or less, can be suitably coated. I can do it.

Furthermore, in the present invention, it is possible to apply uniform pressure to the roller surface regardless of the shape of the roller.
It can also be used to manufacture so-called inverted crown-shaped rollers, which are currently widely used as heat fixing rollers, in which the outer diameter at the center of the roller is smaller than the outer diameter at both ends, which is shaped like a drum to prevent paper wrinkles during paper passing. , the present invention can be suitably applied.

(Function) The present invention utilizes the fact that the expansion coefficient of rubber material is much larger than that of metal. The liquid rubber injected between the cylindrical mold and the rubber roller is heated and expanded in a sealed state, and the large engraving pressure generated at that time applies uniform pressure to the fluororesin tube from the outside. ,
To firmly adhere a rubber layer and a fluororesin tube.

In the present invention, even if the injected liquid rubber hardens and adheres to the outer periphery of the roller during demolding, the surface of the roller rubber layer is covered with a fluororesin tube that has good releasability. The tubular rubber can be cut out and easily peeled off from the roller surface.

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

Example 1 An aluminum hollow core shaft 1 with an outer diameter of 29 mu and a wall thickness of 2 mm was
)IT~] system silicone rubber 2 was coated and ground to obtain a rubber roller 3 finished to an outer diameter of 29.94 mm. Then, the inner surface is etched and adhesive is applied to a thickness of 30 mm.
A PFA chinibu 4 having a diameter of 28.7 mm and a diameter of 28.7 mm was placed on the rubber roller 3 described above. At this time, PF^tube 4 is
The tube was made to be 3n long from both ends of the roller 3, and the excess tube was cut off.

As shown in the figure, the rubber roller 3 thus obtained was placed concentrically in a cylindrical mold 5 made of an iron vibrator with an inner diameter of φ32, and fixed with a stopper 6. Then, liquid silicone rubber 7 was injected between the cylindrical mold 5 and the rubber roller 3. Then, the top and bottom of the plugs 6, 6 are mechanically fixed, the inside of the mold is sealed, and the temperature is set in a constant temperature bath at 150°C.
heated for an hour.

Thereafter, this was taken out from the thermostatic oven, left to stand at room temperature to shrink the rubber material, and the roller 3 was demolded.

The outer circumference of the PFA tube 4 of the roller 3 has a thickness of 1 mm.
It was wrapped in a tube of silicone rubber.

Cut out this tube-shaped rubber and peel it off to find an outer diameter of φ3.
A photo of a 0 mm PF'A tube or a silicone rubber roller coated in good condition was taken.

Example 2 As a roller to cover the PP^ tube, a so-called inverted crown-shaped roller, which is thinner than the outer diameter of the center or both ends of the roller, was used. A PFA tube coated roller was manufactured under the same conditions as in Example 1. As in Example 1, a silicone rubber roller coated with a PFA tube in good condition was obtained.

[Effects of the Invention] As explained above, according to the present invention, it is possible to provide a method for manufacturing a fluororesin tube-covered roller with sufficient adhesion between the rubber layer and the fluororesin tube. In particular, we can produce rollers that are difficult to obtain using conventional methods, such as rubber rollers with a fluororesin tube firmly adhered to the surface of a thin rubber layer, and inverted crown-shaped rubber rollers with a fluororesin tube firmly adhered to the surface. It also becomes possible to easily manufacture two. Therefore, it is possible to easily obtain a heat fixing roller of poor quality.

[Brief explanation of the drawing]

The drawing is a cross-sectional view of a mold used in an embodiment of the present invention. 1......Aluminum hollow core shaft 2...Silicone rubber 3...Rubber roller 4...PFA tube 5...・・・・・・Cylindrical mold 6・・・・・・Plug body

Claims (1)

[Claims] (1) A fluororesin tube is fitted onto a rubber roller having a rubber layer on a metal core shaft, and the rubber roller is inserted into a cylindrical mold having an inner diameter larger than its outer diameter and held concentrically, and then Liquid rubber is injected between the cylindrical mold and the rubber roller, and then the inside of the mold is heated while being kept in a sealed state to expand the liquid rubber, and the expansion pressure causes the fluororesin tube and the rubber roller to expand. A method for producing a rubber roller coated with a fluororesin tube, characterized in that the rubber roller is bonded to the rubber layer of the rubber roller under pressure and then removed from the mold.