Polyethylene terephthalate (PET) is a member of the polyester family which is tough, lightweight, and recyclable, and which has good acid/base resistance. Combined with its excellent water and moisture barrier properties, PET is widely used to make plastic containers. In order to improve the texture and increase the sales of plastic containers, a pearlescent composition is often used during the manufacturing process, providing the resulting containers with a dazzling pearlescent effect in the eyes of the viewers.
In general, conventional pearlescent compositions usually contain PET as a main component, and a pearlescent component composed of a single material other than PET. For example, US2016/0009016A1 discloses a process for making a plastic container with a pearly gloss, in which first pellets made from a single polyolefin-based material is ground into fine powders having an average particle size not greater than 500 μm (1 wt % to 10 wt %) and is blended with 90 wt % to 99 wt % of second pellets made from polyethylene terephthalate. The obtained blend is heated, followed by being subjected to injection molding to obtain a preform. The preform is then subjected to blow molding, thereby obtaining the plastic container with a pearly gloss.
Although a higher amount of pearlescent component results in a better pearlescent effect, the amount of the pearlescent component in the pearlescent composition cannot be arbitrarily increased, being required to range from 1 wt % to 10 wt % based on the total weight of the pearlescent composition. When the amount of the pearlescent component is higher than 10 wt %, phase separation between the pearlescent component and the PET component occurs due to aggregation of the pearlescent component, causing the plastic container to be flawed. In addition, the production of conventional plastic containers also involves a high-temperature heating process which consumes much energy and time. Therefore, improvements in the production of plastic containers exhibiting a better pearly gloss and reduction of the production cost are needed.