An intermediate, tetramethylene bis (orthophosphate), was prepared by the esterification of pyrophosphoric acid and l,4-butanediol. Then pyrophosphoric-containing modified polyesters (ATTBs) were synthesized by polycondensation of tetramethylene bis(orthophosphate), trimethylolpropane, adipic acid, and l,4-butanediol. The content of l,4-butanediol was varied from 10 to 20wt% for the reaction. The increase of the amount of l,4-butanediol in the synthesis of ATTBs resulted in increase in average molecular weight and decrease in kinematic viscosity owing to the excellent flowability and reactivity of l,4-butanediol.

Two PU flame-retardant coatings, 2,3-DBPO/N-l00 (DBPON) and 2,3-DBPO/IL (DBPOI), were prepared by curing 2,3-dibromo modified polyester (2,3-DBPO) with isocyanate curing agent Desmodur N-l00 (or Desmodur IL) at room temperature. The physical properties and flame-retardancy of the two coatings were tested and compared. As a result, the pot-life, yellowness index, lightness index difference, 60˚ specular gloss, cross-hatch adhesion, viscosity, and accelerated weathering resistance of DBPON were better than those of DBPOI; the fineness of grind of the two coatings were the same; and the drying time, hardness, and abrasion resistance of DBPOI were better than those of DBPON. The flame retardancy of the flame-retardant coatings increased with the content of the flame retarding component, 2,3-dibromopropanoic acid (2,3-DBP); and the LOI values of the two coatings were in a range of 27~29% when the content of 2,3-DBP was 30wt%.

Two-component polyurethane flame-retardant coatings were prepared by blending trichloro aromatic modified polyesters(TCMPs) and polyisocyanate. TCMPs were synthesized by polycondensation of trichlorobenzoic acid(TCBA), a flame-retardant component, with adipic acid, 1,4-butanediol, and trimethylolpropane. The content of TCBA was varied in 10, 20, and 30 wt% for the reaction. These new flame-retardant coatings showed various properties comparable to other non-flame-retardant coatings. Moreover, we carried out the combustion test and the flammability test for our flame-retardant coatings. The results of vertical burning test for the coatings containing more than 20 wt% of TCBA were determined as 'no burn'. The results of flammability test for the coatings with 20 wt% and 30 wt% of TCBA contents indicated the limiting oxygen index(LOI) values of 25% and 28% respectively, which implied relatively good flame retardancy.

Pyrophosphoric lactone modified polyester(PATT) that contains two phosphorous functional groups in one unit base resin structure was synthesized to prepare a non-toxic reactive flame retardant coatings. Then the PATT was cured at room temperature with isocyanate, Desmodur IL, to get a two-component polyurethane flame retardant coatings(PIPUC). Comparing the physical properties of the films of PIPUC with the film of non-flame retardant coatings, there was no degradation observed in physical properties by the introduction of a flame-retarding component into the resin. We found that the char lengths measured by 45˚Meckel burner method were 3.1~4.4cm and LOI values recorded 27~30%. These results indicate that the coatings prepared in this study is good flame retardant one. The surface structure of coatings investigated with SEM does not show any defects and phase separation.

Two-component polyurethane flame retardant coatings were prepared by blending phosphate-containing modified polyesters(PMPEs) and TDI-adduct. PMPEs were synthesized by polycondensation of dimethyl phenylphosphonate, a flame retardant component, with 1,4-butanediol, adipic acid, and trimethylolpropane. The content of dimethyl phenylphosphonate was varied 10, 15, and 20wt% for the reaction. Various physical properties of these new flame retardant coatings were comparable to non-flame retardant coatings. Coatings with 20wt% dimethyl phenylphosphonate did not burn during the vertical burning test.