The present application relates to modified
copolyester material, disclose a kind of modified
polyester and its preparation method and application.Modified
polyester is less than or equal to 130 ℃, modified
polyester and
polyvinyl chloride are melt-mixed to form composite particles with weight ratio 1:0.5-2, then with
toughening agent is co-
extrusion mixed to be made into the composite board material with thickness 1-2cm with weight ratio 1:0.1-0.15, the
impact resistance of composite board material is 390kg / mm above.Modified polyester preparation method includes: under
esterification reaction condition, after modified
monomer,
dibasic acid monomer, dibasic
alcohol monomer and catalyst are mixed, first stage reaction is carried out;Under
polycondensation reaction condition, second stage reaction is carried out, modified monomer contains polyhydric
alcohol with formula (I) shown structure and monomer with formula (II) shown structure, and the
molar ratio of monomer with formula (II) shown structure and
dibasic acid monomer is 0.4-1.5:1.Modified polyester
melting point is low, and the compatibility with
polyvinyl chloride is good, and the
composite material formed by melt-mixing of the two has excellent strength,
toughness and
cold resistance.