JPS6325928B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for centrifugally molding a resin tube, which involves centrifugally molding a cylindrical tube by supplying a resin liquid onto its inner peripheral surface while rotating the tube around its horizontal axis.

When a centrifugally molded resin layer is cured, its inner surface comes into contact with air; therefore, in the case of polyester, for example, the inner surface becomes uncured due to the influence of oxygen (in the air). Conventionally, wax is added to the solvent (styrene monomer) mixed into the resin liquid, and when the styrene monomer is evaporated into the air during centrifugal molding, the wax (oil) remains on the inner surface and forms an oil film. A molding method is provided that prevents air exposure. However, in this case, the oil film is so thin that it cannot be cleaned.
This results in incomplete hardening, resulting in a decrease in corrosion resistance. Furthermore, since wax has no effect on air or insulation unless individual surfaces are formed on the resin surface,
There was a problem that a wax-type oil film at a temperature of ~50°C or higher could not be obtained. However, a high temperature is required to quickly cure the resin, and if the temperature is low, the resin liquid cures slowly, reducing productivity.

An object of the present invention is to provide a method for centrifugal molding of a resin tube, which can increase productivity at high temperatures and also promote the curing reaction of the inner surface of the resin layer.

In order to achieve the above object, the method of centrifugal molding of a resin tube according to the present invention involves centrifugally molding a cylindrical tube by supplying a resin liquid onto its inner peripheral surface while rotating the cylindrical mold around a horizontal axis. While curing the resin layer, a water-soluble air shield is supplied into it to form a water film on the inner surface of the resin layer, and then infrared rays are applied to the inner surface of the resin layer through the water film.

According to the method of the present invention, the following effects can be expected. That is, since the water film can be easily and cleanly formed, this water film can prevent the inner surface of the resin layer from coming into contact with air, and infrared rays can promote the curing reaction of the inner surface through the water. Therefore, although productivity can be increased at high temperatures, curing can be performed quickly and reliably. Further, the water-soluble water film material is blended with resins such as popal alcohol resin, gelatin, and glue, a solvent of alcohol, an acidifying agent, and an oxygen-staining material pigment. This water film material is harmless compared to wax.

An embodiment of the present invention will be described below based on the drawings. First, as shown in FIG.
A cylindrical shape 3 supported by the
While rotating around the horizontal axis 4, a resin liquid 6 is supplied onto the inner peripheral surface of the cylindrical mold 3 from a resin liquid supply pipe 5, and centrifugal molding is performed. As shown in FIG. 2, a cylindrical resin layer 7 is centrifugally formed on the inner peripheral surface of the cylindrical mold 3
While curing, a water film material 10 is supplied to the inner surface of the resin layer via a spray 9 provided at the tip of the arm rod 8, and a water film 11 is formed on the inner surface of the resin layer by centrifugal molding. The water film material becomes air-tight and breaks when it is heated quickly. Next, as shown in FIG. 3, the infrared heater 12 provided on the arm rod 8 is placed to face the inner surface of the resin layer. Then, the infrared rays pass through the water film 11 and promote the curing reaction on the inner surface of the resin layer.

This effect is achieved by shriveling the resin surface using air-filled membranes, and further hardening the surface with infrared rays passing through the resin to reduce the influence of the resinous membrane (water film). This overlapping effect speeds up the film formation time and accelerates the curing of the resin surface affected during that time using infrared rays, allowing surface curing to be performed at high temperatures and high speeds with the NON-WAX type. In other words, high-speed sexual production is possible.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIGS.
The figure is a longitudinal sectional side view showing the molded state. 1... Ring body, 2... End face jig, 3... Cylindrical shape, 4
... Horizontal axis, 5 ... Resin liquid supply pipe, 6 ... Resin liquid, 7 ... Resin layer, 8 ... Arm rod, 9 ... Spray, 10 ... Water, 11 ... Water film, 12 ... ...Infrared heater.

Claims (1)

[Claims] 1 While rotating the cylindrical mold around its horizontal axis, a resin liquid is supplied onto the inner circumferential surface of the cylindrical mold for centrifugal molding, and while the cylindrical resin layer is hardened, a water-soluble air bubble and a break are inserted into it. A method for centrifugal molding of a resin tube, which comprises supplying a material to form a water film on the inner surface of the resin layer, and then applying infrared rays to the inner surface of the resin layer through the water film.