JPS608397B2 - How to make plastic pipes - Google Patents

Description

[Detailed description of the invention] TECHNICAL FIELD The present invention relates to a plastic tube passed through an electrical conduit or the like.

Plastic pipes are widely used for structural materials, piping, electrical conduits, etc. because they are superior in insect resistance and chemical resistance, as well as being lightweight and flexible, compared to metal pipes. but,
Due to its flexibility, plastic pipes are susceptible to fan-flat deformation when subjected to lateral pressure, and have the disadvantage of causing anxiety when used in situations where lateral pressure is applied, such as when buried in the ground.

Possible ways to resolve these concerns include, for example, using plastic with a high elastic modulus or increasing the wall thickness of the tube, but both increase the bending rigidity, which is a characteristic of plastic tubes. Maneuverability is lost.

We conducted various studies to obtain a plastic tube with a good balance between local flat deformation resistance and sacrificial capacity.We made a pipe using PVC, whose elastic modulus increases markedly by irradiating it with electron beams, and created a pipe with Rather than curing by irradiation,
By intermittently irradiating and curing the pipe in the length direction, it was realized that a pipe with good resistance to lateral pressure and excellent maneuverability could be obtained, and the present invention was completed. The present invention will be explained in detail below with reference to the drawings and examples.

A compound was made with the formulation shown in Table 1, and a pipe with an inner diameter of 6 mm and a thickness of 3 mm was made by extrusion.

This pipe is shown in Figure 2 as a halved lead pipe with one window.
By passing under an electron beam, the material was intermittently irradiated and cured in a strip shape substantially perpendicular to the length direction.

(Electron beam irradiation dose: approximately 10 megarads) Figure 1 shows a pipe that has been partially cured by radiation, with the portion 3 being the uncured portion and the portion 4 being the hardened portion. The ratio between portions 3 and 4 can be freely changed by changing the shape and spacing of the window 1 of the lead pipe shown in FIG. The thus obtained partially cured pipe had a deformation rate of 10% or less even when external pressure of lton/skin was applied, and had low bending rigidity and could be bent freely by hand.

Therefore, if used for cable ducts, for example, it would have great practical value, such as simplifying power distribution work. The formulations in Table 1 are just examples, and the composition is not limited to these formulations.

The necessary condition is that it can be cured by irradiation, and polyfunctional monomers such as divinylbenzene, ethylene glycol diacrylates, ethylene glycol dimethacrylates, diallyl phthalate, and trimethylolprohane trimethacrylate can also be used. is possible,
As the base polymer, not only PVC but also chlorinated polyethylene, vinyl ethylene chloride vinyl acetate terpolymer, ethylene vinyl acetate, and blends thereof can be used.

Table 1

[Brief explanation of drawings]

FIG. 1 shows an example of the pipe of the present invention, and FIG. 2 shows a half-split lead pipe for shielding the pipe for irradiating the pipe in a cotton-like manner. 1...Window, 2...Half-split lead pipe, 3...
...uncured part, 4...cured part. 2 diagrams outside the zoo diagram

Claims (1)

[Claims] 1. After covering a plastic pipe made of a plastic compound containing a polyfunctional monomer with a tube made of a radiation shielding material with intermittent windows in the axial direction,
A method for manufacturing a plastic tube, characterized in that the plastic pipe is intermittently hardened in the axial direction by irradiating the plastic pipe together with the tube made of the radiation shielding material.