JPH07108746B2 - Roller surface modification method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a pinch roller used for audio and video equipment (cassette tape recorder, DAT, VTR, etc.), or OA equipment (copier, facsimile, printer, etc.). The present invention relates to a method for modifying the surface of a roller such as a platen roller, a paper feeding roller, and a conveying roller used in (1), which can reduce the viscoelasticity of the surface rubber and prevent adhesion with a tape or paper.

(Prior Art) Conventionally, a large number of rollers such as a pinch roller and a paper feed roller whose surface is formed of rubber are used for transporting tapes and papers in audio / visual equipments or OA equipments. These rollers must transfer the tape or paper smoothly, but since the rubber surface has viscoelasticity, the tape or paper sticks and hinders smooth transfer. For that reason, these rollers are taken a method for preventing adhesion with a tape or paper.

Conventionally, the following methods have been used to reduce the adhesive strength.

That is, the first is a method of blending a wax or the like into the rubber composition to reduce the adhesive force, and the second is a method of treating the rubber surface of the roller with a chemical agent, that is, a dipping treatment in a chromic acid aqueous solution, Thirdly, the rubber surface is heated by a dry heat device or the like to oxidize and deteriorate the surface, and a cured coating is formed to reduce the adhesive strength.

(Problems to be Solved by the Invention) However, the conventional methods for reducing the adhesive force on the rubber surface have the following problems.

That is, the method of blending wax or the like into the first rubber composition can reduce the adhesive force, but at the same time also lowers the friction coefficient. Further, there is a problem that wax or the like deposits on the rubber surface and contaminates tape or paper.

Further, in the second chemical treatment method, if the washing with water is not sufficient after the immersion treatment in the chemical, the metal part of the equipment or machine incorporating these rollers is oxidized by the remaining chemical. There is a problem of being rusted. In addition, the waste liquid treatment of chemicals must be done carefully to prevent pollution.

Further, in the third heat treatment method for the rubber surface, the cylindricity of the roller decreases because the rubber surface shrinks. For this reason, the distribution of the contact pressure with the mating roller deteriorates, and not only the tape or paper cannot be transferred smoothly, but the wrinkles on the tape or paper further deteriorate the quality.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a surface modification method for a roller that reduces the adhesive force while maintaining the friction coefficient by a simple method.

(Means for Solving the Problem) Therefore, the present invention is characterized in that the rubber surface of the roller that has been subjected to polishing finish is irradiated with ultraviolet rays while rotating the roller to form a thin cured layer on the surface. .

The rubber material of the roller may be either natural rubber or synthetic rubber, but diene rubbers such as acrylonitrile-butadiene copolymer rubber, styrene-butadiene copolymer rubber, polyisobutylene rubber and natural rubber are preferable.

The desired wavelength, illuminance, and irradiation time of the ultraviolet rays to be irradiated are determined depending on the type of rubber material and the application. Usually, irradiation with ultraviolet rays for about 3 to 7 minutes can enhance the processing effect.

Further, the ultraviolet irradiation method requires that the rubber surface of the roller be uniformly irradiated, and the roller is rotated with respect to the ultraviolet lamp, or the ultraviolet ray is irradiated from the vertical direction while the roller is fed by a conveyor. Method may be used.

(Operation of the Invention) A cross-linking reaction is caused by irradiation of ultraviolet rays, and the skin layer on the rubber surface is cured to reduce the adhesive strength.

(Example) Below, the Example of this invention is shown.

As shown in Fig. 1, the rubber material is NBR and the rubber hardness is 5
A VTR pinch roller 1 with a 0 degree and an outer diameter of 8 mm is molded, and an ultraviolet lamp 2 with a lamp output of 80 W / cm, a rated power of 2000 W, and a wavelength of 200 to 450 nm (main wavelength 365 nm) is formed on the pinch roller 1. For 5 minutes. The conventional heat treatment was performed by secondary vulcanization.

The results are shown below in comparison with the conventional heat treatment method.

(1) Change in adhesive strength The change in adhesive strength of the pinch roller was measured as follows. That is, as shown in FIG. 2, the roller 1 is placed on the carriage 5 to which the adhesive tape 4 is attached, the prescribed weight 8 is placed on the tray 7 attached to the roller 1, and the prescribed weight 8 is passed after the prescribed time. Remove and measure the force when moving the carriage 5 at the specified speed in the direction of the arrow with the fixed strain gauge 9,
This was taken as the adhesive strength.

The results are as follows, and it is clear that the adhesive strength was reduced by the ultraviolet treatment method.

Heat treatment method Ultraviolet treatment method Before treatment 247 (gf) 232 (gf) After treatment 102 (gf) 90 (gf) (2) Change in friction coefficient The change in friction coefficient was measured as follows. That is, the third
As shown in the drawing, the tray 7 is attached to the roller 1 placed on the trolley 5, a prescribed weight 8 is placed thereon, and after a prescribed time, the force when the trolley 5 is moved at the prescribed speed in the arrow direction is measured by the strain gauge 9 The coefficient of friction was measured on the day with the specified weight.

The results are as follows, and there was no difference between the two.

Heat treatment method Ultraviolet treatment method Before treatment 1.47 1.50 After treatment 1.42 1.47 (3) Change in cylindricity When heat treatment is used, the rubber shrinks greatly and the cylindricity changes, but the thickness of the vulcanized rubber surface due to UV irradiation. Since it is at most about several microns, there is no effect on the dimensional change due to shrinkage.

 Heat treatment method UV treatment method Before treatment 11.2 (μm) 10.8 (μm) After treatment 19.9 (μm) 11.1 (μm) (4) Ozone resistance There was no difference in ozone resistance between the two.

Heat treatment method Ultraviolet treatment method No crack before treatment No crack after treatment No crack after treatment (Ozone test conditions were 50PPHM x 40 ° C x 96H, 10% elongation.) (Effect of invention) As described in detail above, According to the present invention, although the adhesive force of the roller decreases, the friction coefficient and ozone resistance do not change, the ability before irradiation with ultraviolet rays can be maintained, and the roller surface can be modified by a simple method.

[Brief description of drawings]

FIG. 1 is an explanatory perspective view showing an ultraviolet irradiation state, FIG. 2 is an explanatory front view of an adhesive force measuring device, and FIG. 3 is an explanatory front view of a friction coefficient measuring device. 1 is a roller, 2 is a UV lamp

Claims (1)

[Claims] 1. A surface modification method of a roller, which comprises irradiating a rubber surface of a roller which has been polished and finished with ultraviolet rays while rotating the roller to form a thin cured layer on the surface.