What stabilizers do polyester bottle sheet manufacturers use?

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There is evidence indicating that the stabilizer polyphosphoric acid used in traditional bottle-grade polyester production reacts with antimony in catalysts and cobalt in PTA to form gels and precipitates that clog the melt filters. The relevant sources are as follows: Practices for improving the formulation of polyester chips for bottles: http://www.cqvip.com/asp/userlink.asp?re=77616; Current status of the use of stabilizers in polyester PET: http://www.cqvip.com/asp/userlink.asp?re=77617; Impact of quality characteristics of bottle-grade polyester chips on the transparency of products: http://www.cqvip.com/asp/userlink.asp?re=77618. However, the new stabilizers recommended in these sources – triethyl phosphate with a boiling point of 215°C, trimethyl phosphate with a boiling point of 194°C, and triphenyl phosphate with a boiling point of 244°C – all have boiling points lower than those of the polyester reaction temperature. Now, let’s discuss the following three questions: 1. What stabilizers do different manufacturers use? 2. Has there been a frequent problem of clogging in the melt filter? 3. What processing methods were used if a new type of stabilizer was employed?