Preparation method of foamed polypropylene beads

Abstract

The invention belongs to the technical field of foamed polypropylene, and relates to a preparation method of foamed polypropylene beads, which comprises the following steps: (1) adding polypropylene particles, a dispersion medium, a dispersing agent and a dispersing aid into a closed high-pressure-resistant kettle, and conducting stirring to form a dispersion system; (2) conducting heating to a certain temperature, and conducting filling with a certain amount of CO2; and (3) releasing the dispersion to normal pressure to obtain foamed polypropylene beads, conducting washing with cleaning water, conducting dehydrating, and conducting drying to obtain a foamed polypropylene bead finished product. The polypropylene particles comprise the following components in percentage by weight: 94 to 99.94 percent of polypropylene, 0.01 to 2 percent of a crystallization nucleating agent, 0.02 to 4 percent of an organophosphate compound and 0.03 to 0.3 percent of a cell nucleating agent. The polypropylene particles used in the invention contain organophosphate compounds, and have the effect of inhibiting the particles from caking in a kettle or the beads from caking outside the kettle in the high-temperature and high-pressure kettle type foaming process, so that the use amount of a dispersing agent can be reduced, the content of attachments on the surface of the foamed polypropylene bead finished product is lower than 200ppm, and a water vapor molded part is lower in sintering pressure and excellent in apparent quality.

Description

technical field [0001] The invention belongs to the technical field of expanded polypropylene, and in particular relates to a preparation method of expanded polypropylene beads. Background technique [0002] Expanded polypropylene beads (EPP) can be easily molded into application parts of various shapes through the steam molding process, and the EPP beads produced by the mainstream batch foaming method in the industry have a closed-cell structure and a high expansion rate. High, endowing EPP parts with excellent dimensional accuracy and lightweight characteristics, many performance advantages make EPP widely used in automotive cushioning and protection parts, packaging and transportation cushioning materials and lightweight structural parts and other application scenarios. [0003] The manufacturing process of EPP produced by the kettle method is as follows: the foamable polypropylene-based polymer material is extruded and granulated by the extruder unit to obtain particles ...

AI Technical Summary

Problems solved by technology

Although the above patented technologies have obtained foamed bead products with less surface attachments, there is still room for further improvement