Biaxial orientation polyvinyl chloride pipe and preparation method thereof

Abstract

The invention discloses a biaxial orientation polyvinyl chloride pipe and a preparation formula thereof. The preparation formula comprises 100 parts of PVC (Polyvinyl Chloride), 1.5-3.0 parts of thermal stabilizing agent, 4-6 parts of processing agent, 5-10 parts of toughening agent, 0.2-0.5 part of outer lubricant, 0.3-0.8 part of inner lubricant, 1.0-2.5 parts of titanium dioxide and 0.02-0.04 part of carbon black. The invention further discloses a preparation method of the biaxial orientation polyvinyl chloride pipe. The preparation method comprises the following steps: weighing a raw material, performing a kneading process, performing an extrusion forming process, and performing a stretching and swelling orientation process. Due to adoption of the raw material formulation, by adding a proper amount of the toughening agent, the toughness of a pipe blank to be oriented is greatly improved, no cracks are caused in expansion, and thus the expansion stretching velocity can be increased by multiple times; through inner and outer water bath heating on the pipe blank, the pipe blank is prevented from influence of temperature of an ambient environment in the orientation process, the whole pipe blank to be oriented can meet the orientable temperature, and the time that the pipe is heated to be the expansion temperature is shortened by more than 10%, so that the production efficiency is greatly improved; due to arrangement of an outer diameter fixing sleeve in the expansion procedure, the size precision of the outer diameter and the wall thickness of the pipe is ensured, the pass percent of a product is improved, and the cost is lowered.

Description

technical field [0001] The invention relates to a PVC pipe material, in particular to a biaxially oriented polyvinyl chloride pipe and a preparation method thereof. Background technique [0002] PVC is a non-crystalline, amorphous plastic. Since the chlorine in the molecule is highly polar, it is rigid, has a high glass transition temperature, and has no clear melting point. Therefore, PVC pipes, compared with other crystalline polyolefin pipes, are more suitable for biaxial stretch orientation. By biaxial stretching and orientation, not only the axial strength of the pipe is increased, but also the radial (that is, hoop) strength of the pipe is increased. The improvement of the radial strength directly improves the ability of the pipe to withstand water pressure. Radial expansion of the tubing during processing allows the molecules to be oriented in the circumferential direction, resulting in not only increased strength, but also a substantial improvement in toughness. Be...

AI Technical Summary

Problems solved by technology

In this invention, the radial expansion only relies on the pressure of the fluid medium in the pipe without limiting the outer diameter shaping device, so it is difficult to ensure the dimensional accuracy of the outer diameter and wall thickness of the pipe.

In the process of expansion molding and orientation, this invention only relies on the fluid medium in the tube to be oriented to transfer heat to the tube through the inner wall of the tube, and it takes a relatively long time to raise the temperature of the entire tube to above the glass transition temperature (orientable temperature). time, and the outer layer of the pipe is easily affected by the external environment and cannot reach the orientable temperature. If the pipe is forcibly expanded in this way, it is easy to cause the pipe to crack or be damaged by forced expansion due to the local failure to reach the expansion temperature. Undetectable defects bury hidden dangers for engineering quality accidents

In addition, there is no toughening agent in the raw material formula components of this invention, and the rate of pipe orientation must be controlled at a low level to ensure that the pipe does not crack or leave defects