Design Of Double-Bond Monomers Containing Phosphorus, Nitrogen, Silicon And Its UV-cured Coatings And Study On Flame Retardant Properties And Mechanism

This paper stood on the UV-curing technology, reviewed the progress of flame-retardant coating on the basis of the latest research, aimed at the limitations and shortcomings for the present transparent flame-retardant coating, through the molecular design, synthesized flame retardant monomers containing phosphorus, nitrogen and silicon. This paper combined UV-cured technology, halogen-free flame retardant and nano-composite, prepared a new type of transparent flame retardant coating and nanocomposites coatings. We studied influence of the coating composition and structure on its thermal stability, combustion performance and fire resistance. We also studied the flame retardant mechanism for transparent coating, clarified the influence of char layer on the fireproof performance of coatings, and revealed the relationship among the coating composition, structure, thermal stability, combustion performance and fire resistance. We optimized flame retardant system, and used it on the protection of fabric and wood, and explored its feasibility. The research work of this dissertation is composed of the following parts:1. Through the molecular design, a novel phosphorus monomer (BDEEP) containing four reactive group has been synthesized by allowing phosphorus oxychloride to react with 2-hydroxyethyl acrylate (HEA) and 1, 4-Butane diol. Its structure was characterized by Fourier transformed infrared spectroscopy (FTIR) and ¹H nuclear magnetic resonance spectroscopy (¹H NMR). The flame retardant coatings were prepared through UV-cured technology. The thermal degradation mechanism was characterized using thermogravimetric analysis/ infrared spectrometry (TGA-IR). The curve of TGA indicates that there are three characteristic degradation temperature stages for the cured film, which was further characterized by real time Fourier transform infrared (RT-FTIR) measurement. The volatilized products formed on thermal degradation of BDEEP indicated that the volatilized products are CO, CO₂, water, alkane, carbonyl, phosphorus compounds and aromatic compounds according to the temperature of onset formation. The combustion performance was examined by microscale combustion calorimeter (MCC). The heat release rate (HRR) and heat release capacity (HRC) were very low.2. Through the molecular design, a silicon-based acrylate (SHEA) was synthesized via the reaction between 2-hydroxylethyl acrylate and dimethyldichlorosilane. Its structure was characterized by Fourier transform infrared (FTIR), ¹H NMR spectroscopy and ²⁹Si NMR spectroscopy. We adjusted the ratios of SHEA and tri(acryloyloxyethyl) phosphate (TAEP) to prepare a series of flame retarded coatings containing silicon and phosphorus through UV-cured technology. Their combustion behaviors were examined by microscale combustion calorimetry (MCC). The thermal degradations of TAEP/SHEA composites were characterized using thermogravimetric analysis/infrared spectrometry (TGA–IR). The MCC results present that the addition of TAEP into SHEA was able to decrease the HRR, HRC, T_max and THC, and form the stable char layer. Results showed that synergistic effect between TAEP and SHEA.3. Through the molecular design, a nitrogen-based acrylate (TGICA) containing three reactive group was synthesized via the reaction between acrylic acid and triglycidyl isocyanurate. A novel phosphorus monomer containing a single reactive group, 2, 2-dimethyl-1,3-propanediol acryloyloxyethyl phosphate (DPHA), has been synthesized through phosphorus oxychloride reacting with neopentyl glycol and 2-hydroxyethyl acrylate (HEA). A novel phosphorus monomer (PDHA) containing double reactive group has been synthesized through phenyl dichlorophosphate (PDPC) reacting with 2-hydroxyethyl acrylate (HEA). Based on the intumescent flame retardant mechanism, We adjusted the ratios of TGICA and DPHA,PDHA and TAEP to prepare a series of intumescent flame retarded coatings through UV-cured technology. The UV–Vis spectra showed that each UV-cured coating had good optical transparency, compatibility and the higher LOI values. The test results from MCC and TGA indicated that there was a distinct synergistic effect exists between TGICA and DPHA,PDHA and TAEP. When the weight ratio was appropriate, the flame retardant coatings had the lower PHRR and higher amount of char. TGA-IR results indicated that the evolved products were CO, CO₂, water, NH₃, carbonyl, phosphorus oxides and aromatic compounds according to the temperature of onset formation. The above study results suggested that when the weight ratio between nitrogen and phosphorus was appropriate, intumescent flame retardant coatings could form the compact char layer at higher temperature.4. This paper designed a series of flame retarded nanocomposites coatings, and prepared epoxy acrylate resin (EA)/layer compound (Mg/Al-LDH and OZrP) UV-cured nanocomposites coatings, EA/TGICA/TAEP and PDHA/TGICA flame retarded nanocomposites coatings through in situ polymerization. Results showed that LDH and OZrP did not affect the conversion percentage. The results obtained from MCC, LOI and TGA indicated that the addition of layer compounds into coatings could decrease the peak of heat release rate (HRR) for the films, increase the LOI value of the films and char yield at higher temperature and enhance flame retardant of coatings.5. Based on the above study, we optimized flame retardant system, prepared PDHA/TGICA flame retardant coating and TAEP/TGICA flame retardant coating, and used them on the protection of fabric and wood, and explored its feasibility. The flame retardancy of the treated fabrics was studied by MCC and LOI. The cottons coated flame retardant coatings had the lower peak heat release rate (PHRR), heat release capacity (HRC), total heat of combustion (THC) and higher LOI value compared with untreated cotton. The flame retardant coatings (PDHA/TGICA and TAEP/TGICA system) could protect wood from fire effectively. It could be seen that wood with flame retardant coatings could show the lower mass loss and carbonization volume and prolong fire resistant time of wood compared with untreated wood. In addition, the cone calorimeter results showed that treated wood had the lower PHRR and THR. Flame retardant coatings can form intumescent and compact char layer to protect wood from fire.