The invention discloses branching, cross-linking, expanded, melt-dropping-resistant and
flame-retardant
copolyester based on a
triazine ring structure. The
copolyester is prepared by conducting random copolymerization on structure units expressed as formulae I, II and III or structure units expressed as formulae I, II, III and IV according to a conventional method. The
intrinsic viscosity [eta] of the prepared branching, cross-linking, expanded, melt-dropping-resistant and
flame-retardant
copolyester is 0.41-1.10 dL / g; the extreme
oxygen index is 24.5-38.0%; the vertical
combustion grade is between V-2 and V-0; the peak heat release rate p-HRR in a cone heat test is 247-643 kW / m<2>. According to the copolyester, a modified
monomer of the
triazine ring structure is introduced, and then copolymerized with
polyester to form a unique ternary branched cross-linking
network structure; the modified
monomer of the
triazine ring structure contains the
flame-retardant element
nitrogen, so that the
melt viscosity of the copolyester in
combustion can be improved; the copolyester is capable of releasing
nitrogen and quickly forming an expanded
char layer with excellent heat and
oxygen insulation effects; especially, a
phosphorus-
nitrogen synergism effect can be generated when the copolyester is used together with the conventional
phosphorus-containing flame-retardant agent; the flame-retardant performance and the melt-dropping-resistant effects can be more excellent; the selected
monomer is low in price; the preparation process is mature; the operation is simple and convenient; the industrialized large-scale production is liable to implement.