GB/T 40409-2021 in English

GB/T40409-2021 stipulates the technical specifications of tetrabromophthalic acid diol as a flame retardant, which is suitable for flame retardant applications in the fields of polyurethane, epoxy resin, etc. For the first time, the standard divides the products into three categories according to viscosity: LV type (10-50Pa·s), MV type (50-100Pa·s) and HV type (100-200Pa·s).

Determination of bromine content - Alkali fusion potentiometric titration

This method decomposes the sample by melting sodium/potassium hydroxide, and uses silver nitrate titration combined with potential mutation to determine the endpoint. Key control points include:

• Melting temperature is controlled at 400-450℃
• pH adjustment requires three acid-base callbacks
• End point determination accuracy reaches 0.1mV

Compared with the traditional oxygen bottle combustion method, this method improves the detection accuracy from ±0.5% to ±0.2%.

Application Guide for Manufacturers

1. Establish a viscosity grading production line. HV type needs to adopt a low-temperature polymerization process
2. It is recommended to configure an automatic potentiometric titrator
for bromine content detection
3. Bulk barrels with UV barrier materials should be used for packaging

Key points for acceptance by the purchaser

• Check the hydroxyl value-viscosity matching (high hydroxyl value corresponds to low viscosity)
• Pay attention to the sample homogenization when retesting the bromine content of the retained sample
• Avoid crystallization caused by low temperatures below -10°C during transportation

The main breakthroughs of this standard compared with the old industry regulations: