Abstract:

Objective Tarpaulin textiles have a wide range of applications in military field, and multifunctional tarpaulin textiles have attracted extensive attentions of researchers. The main purpose of this study is to develop a type of tarpaulin with both flame-retardancy and waterproofness, which are contradictive to each other and are difficult to achieve. The tarpaulin prepared in this study is expected to be used for covering automobile, aircraft, tank and for field tent cloth.
Method The effect of the concentration of flame-retardant TF-11 and the method of dipping the flame retardant on the flame-retardant performance was investigated. In order to improve the flame-retardant and waterproof performance of canvas, DBDPO and Sb₂O₃ were added to PA-822 resin solution and coated on the polyester canvas based on the bromine antimony flame-retardant synergy theory. The flame-retardant and anti-melt-drip mechanism of the multifunctional tarpaulins was analyzed by testing the after-glow time, the after-flame time, the damage length, hydrostatic pressure resistance and breaking strength of the finished tarpaulins, and by testing the carbon residue of the original polyester canvas and the finished tarpaulins with the aid of TG and SEM.
Results The polyester canvas was dipped and rolled twice in 150 g/L of the nitrogen-phosphorus flame retardant TF-11, and after dipping and rolling the fabric had the after-glow time and the after-flame time of 0 s and a damage length of 7.5 cm(Tab. 1). TG analysis showed that the phosphoric acid produced by the flame retardant during combustion was a strong dehydrating agent, which promoted the charring of the polyester canvas and prevented the decomposition of the fabric. The fabric was coated after dipping and rolling with the nitrogen and phosphorus flame retardant TF-11. When the mass ratio of decabromodiphenyl ether (DBDPO) to antimony trioxide was 2∶1 and 30% of the total amount of polyacrylic resin PA-822, the after-glow time and the after-flame time of the coated fabric was 0 s. Compared with the unfinished polyester canvas, the damage length was shortened to 5.5 cm (Fig. 3), and there was no melt drip, and the tarp had a high flame-retardant performance. The SEM images of the residual carbon profile of the finished tarpaulin showed a significant increase in the charring of the coated fabric (Fig. 4) and a significant reduction in the length of damage. This may be due to the synergistic effect of the bromine and antimony added to the coating agent, which promote the charring of the fabric. The char layer inhibits the diffusion of combustible gases and the transfer of heat to achieve the flame-retardant effect, and the bromine and antimony produced the incombustible gas SbBr₃, which reduced the oxygen concentration. Compared with uncoated polyester canvas, the hydrostatic pressure resistance value of the coated polyester canvas increased from 0 to 5.1 kPa (Tab. 2), with excellent waterproof performance. Compared with commercially available tarpaulins, the warp and weft breaking strength of prepared tarpaulins was above 2 000 N (Tab. 4). The flame-retardant effect can reach the degree of self-extinguishing from fire, and the length of damage after burning was obviously reduced, with good waterproof ability.
Conclusion Using polyester canvas as the tarp base fabric, the flame-retardant properties of the polyester canvas were significantly improved by dipping and rolling with the nitrogen and phosphorus flame-retardant TF-11. In order to further improve the flame-retardant and waterproof performance of the polyester canvas, a moisture permeable polyacrylic resin containing bromine antimony flame-retardant was used to coat the fabric after dipping and rolling the nitrogen phosphorus flame-retardant, so that the tarp had good flame-retardant and waterproof performance at the same time, which better solves the contradiction problem between the flame-retardant and waterproof performance of polyester canvas. The multifunctional tarpaulin can reach the degree of self-extinguishing from fire, with hydrostatic performance, can resist the rainstorm soaking, meeting the tarpaulin standard for flame retardant and waterproof performance requirements. In addition to high flame-retardant and waterproof performances, tarpaulin in practical application should also have high strength and corrosion resistance, low weight and fastness to the sun, to cope with different environmental conditions. In protective textiles, the tarpaulin with flame-retardant and waterproof performance has a good prospect for development and application.

Key words: coating finishing, flame-retardant finishing, anti-dripping, waterproof finishing, multifunctional tarpaulin