紫外老化对溶剂型膨胀防火涂料基本性能的影响

膨胀型钢结构防火涂料的耐候性是其应用中需考虑的一个重要因素。本文利用扫描电镜（ SEM）、热重分析仪（ TG）和小型耐火试验炉研究了紫外老化对膨胀型防火涂料的磷含量、表面形貌、热稳定性和防火性能的影响规律,并研究了面漆对其上述性能的影响。研究结果表明：随紫外老化试验的进行,防火涂料的磷含量、热稳定性、高温膨胀成炭性能和耐火隔热性能均出现明显降低;面漆具有较好的保护作用,表面涂刷面漆的防火涂料各项性能变化不大。     

Synergistic effects of aluminum hydroxide on improving the flame retardancy and smoke suppression properties of transparent intumescent fire-retardant coatings

A series of novel aluminum phosphate ester (APEA) flame retardants were synthesized by the salification of cyclic phosphate ester acid (PEA) with different mass ratios of aluminum hydroxide (ATH) and thoroughly characterized by Fourier transform infrared (FTIR) spectroscopy and ¹H nuclear magnetic resonance spectroscopy. The PEA and APEAs were thoroughly mixed with melamine formaldehyde resin to produce five kinds of transparent fire-retardant coatings. The synergistic effects of ATH on the thermal stability, flame retardancy, and smoke suppression properties of the coatings were investigated by different analytical instruments. The results show that the incorporation of ATH greatly decreases the weight loss, char index, flame spread rating, heat release rate, total heat release, smoke production rate, total smoke release and specific optical density in the coatings applied to plywood boards, which is ascribed to a more compact and intumescent char formed during burning, as determined from digital photographs and scanning electron microscopy images. The synergistic effects of ATH in the coatings depend on the content of ATH, and an excessive amount of ATH diminishes the synergistic effects on the flame retardancy and smoke suppression properties based on fire protection tests and cone calorimeter test. Thermo-gravimetric analysis reveals that the thermal stability and char-forming ability of the coatings gradually improve with increasing loading of ATH. FTIR analysis demonstrates that the incorporation of ATH forms a more phosphorus-rich crosslinked char and aromatic char during burning, thus effectively reducing the mass loss, heat release, and smoke production and exhibiting excellent synergistic flame retardant and smoke suppression effects in the coatings.     

耐火膨胀涂料防火性能的模拟分析与验证

简述了耐火膨胀涂料的基本组成和原理.通过有限元分析和涂料样板实验,介绍了耐火涂料在钢结构耐火隔离上所起到的作用,并展望了耐火膨胀涂料所具有的性能优势和在船舶耐火领域的发展应用前景.     

Influences of silicone emulsion on fire protection of waterborne intumescent fire-resistive coating

The combination of self-crosslinking polyacrylate emulsion and silicone emulsion was used as a binder for the preparation of waterborne intumescent fire-resistive coatings. The influences of silicone emulsion on fire protection and char formation of the coatings were investigated in detail by means of TGA, SEM, energy dispersive spectroscopy analysis, rheological measurement, and fire protection tests. The results showed that using silicone emulsion improved thermal stability and antioxidation ability of the coating and increased the residue weights of the char layer at high temperature. Furthermore, an appropriate amount of silicone emulsion could improve the rheological property of the mixed binders and be conducive to the increase of the intumescent factor of the coatings, thus improving the fire protection of the coating significantly. However, an excess amount of silicone emulsion can lead to uneven dispersion of silicone emulsion in the mixed binder and cause an uneven distribution of cell size of the char layer.     

海泡石和可膨胀性石墨对水性超薄膨胀型钢结构防火涂料阻燃性能的影响

采用可膨胀性石墨（EG）和海泡石对传统的APP/PER/MEL膨胀型防火涂料体系进行改性,制备了一种新型水性超薄膨胀型防火涂料,并采用防火性能测试装置、热重分析（TGA）、差热重量分析（DTG）及X射线衍射（XRD）等方法对该防火涂料的耐火性能、热降解过程、碳化层结构进行了研究。热分析结果表明,海泡石与EG复合使用,将充分发挥它们的协同作用：EG在较低温度区域能够延缓碳化层的形成,而海泡石则能够在高温区域阻止碳化层氧化分解,并提高成炭率从而达到阻燃的目的。XRD结果显示,复合使用EG和海泡石能够促进碳化层中TiP2O7的形成,在高温阶段保护碳化层不被氧化。当防火涂料中添加3wt%海泡石和2wt%EG,涂层厚度为1mm时,钢材的耐火时间达到72min。     

Effects of expandable graphite on char morphology and pyrolysis of epoxy based intumescent fire-retardant coating

The current study was designed to investigate the effects of expandable graphite (EG) on fire protection properties of intumescent fire-retardant coating for steel structures. Several formulations of intumescent coating were prepared and tested according to ISO 834 for char expansion. The chars were found without cracks and bonded with the steel substrate. The results showed that the coating slowly degraded during the test and char remained in contact with vertically tested coated substrate. The coated substrates were also tested for weather resistance using humid and ultraviolet environment. The char was characterized by using FESEM, XRD, FTIR, TGA, and XPS analysis. FESEM examined char morphology of the coatings after furnace fire test. XRD and FTIR showed the presence of graphite, borophosphate; boron oxide and sassolite in the char. TGA and DTGA results disclosed that EG improved the residual mass of coating. XPS analysis showed the percentages of carbon and oxygen are 48.50 and 43.45 in char of formulation with 12.8% EG. The results of weathering test coatings showed decreased in char expansion because of a humidity and UV light. The formulation with 9.8% EG showed the maximum char expansion and high residual mass among the formulations investigated in this study. The weathering tested coated samples showed their capability of fire protection.     

Exfoliated and functionalized boron nitride nanosheets towards improved fire resistance and water tolerance of intumescent fire retardant coating

In this work, the exfoliated and functionalized boron nitride (f-BN) nanosheets were prepared via facile treatment and used in the intumescent fire retardant (IFR) coatings, which offer passive fire protection to the steel. To acquire the best fire resistance, the formula of the coating was optimized using response surface methodology (RSM) based on central composite design. According to the result, the optimal sample, with 36.2 wt% ammonium polyphosphate (APP), 27.4 wt% pentaerythritol (PER), 16.8 wt% melamine (MEL), and 7.9 wt% f-BN, was prepared and its fire resistance was tested in our lab. At the end of fire resistance test, the backside temperature of optimal sample was only 185.2°C, which was very close to the RSM-predicted result, indicating satisfactory fire resistance. During the test, the coating decomposed to form an intumescent char layer with high graphitization degree and compactness, thus suppressing the transfer of heat and protecting the underlying steel. In addition, the optimal coating possessed great water tolerance and thermal stability, and its water contact angle and char yield reached up to 66.7° and 40.5%, respectively. Hence, this IFR coating with satisfied fire retardancy and water tolerance has broad practical future in the fire safety of steel structure.     

Influence of heat-stable filler on the thermal shielding performance of water-based intumescent fire-resistive coating for structural steel applications

Intumescent coatings are the newest passive fireproofing materials which maintain structural integrity of high-rise buildings in fire events. The present work focuses on the influence of zirconium silicate as a heat-stable filler in intumescent coatings. Different coatings were formulated by varying the zirconium silicate concentration from 1, 3, 5, 8, and 10 on parts per hundred basis (phr). Fire performance of the coatings was then determined by fire test using a Bunsen burner fire flame at 950°C for 1 h. The degradation of coatings was examined by thermogravimetric analysis (TGA). The morphology of the intumescent chars was analyzed by environmental scanning electron microscopy. The char was also examined by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy. XRD confirmed the inertness of zirconium silicate with intumescent ingredients at high temperatures. TGA showed an increase in the weight residue of char at high temperature. The incorporation of zirconium silicate into intumescent coating forms a thermally stable char with better substrate adhesion. EDS analysis confirmed an increase in the antioxidation property of the char, and the fire test also confirmed an increase in char strength of coatings by the incorporation of zirconium silicate.     

Influence of nano-boron nitride on fire protection of waterborne fire-resistive coatings

Nano-sized BN and micron-sized BN were used as fillers in fire-resistive coatings. The experimental results suggested that nano-BN with a multilayer structure could remarkably enhance the fire protection of fire-resistive coatings. Turbiscan data indicated that nano-sized BN had better dispersion stability in waterborne coatings than micron-sized BN. TGA results showed that nano-sized BN could enhance the thermal stability of the coatings, especially under high temperature. FTIR and EDS results exhibited that nano-sized BN was helpful in reducing the oxidation degree and enhancing the antioxidation property of the char layer under high temperature. The morphology observation demonstrated that nano-sized BN could improve the foam structure of the char layer so as to improve the mechanical strength of the char layer. Nano-sized BN was helpful for the even distribution of the cells; thus the efficiency of heat insulation of the char layer was enhanced. These results proved that nano-sized BN was beneficial to the forming and expanding of the intumescent char layer, and could provide better fire protection for the coatings.     

Influences of glass flakes on fire protection and water resistance of waterborne intumescent fire resistive coating for steel structure

Glass flake (GF) was used as a modifier to improve the fire protection and water resistance of waterborne intumescent fire resistive coating. The influences of GF on the properties of the coatings were investigated in detail by using TGA, XRD, X-ray fluorescence spectrometry (XRF), SEM and fire protection test. The TGA results proved that addition of GF could enhance the anti-oxidation of the char layers and increase the residue weights of the coatings. The XRF results indicated that anti-oxidation of the coatings modified by GF was improved. The SEM images demonstrated that addition of GF could improve the foam structure of the coatings. After immersed in water over 600 h, the results showed that the thermal stability and fire protection of the coating without GF were significant decreased, but the coatings modified by GF could still maintain the excellent intumescent effect and fire protection.     

氧化石墨烯提高钢结构水性膨胀防火涂料的防火性能研究

以水性丙烯酸树脂为基体,聚磷酸胺、季戊四醇和三聚氰胺为膨胀阻燃体系,加入少量氧化石墨烯制备水性膨胀防火涂料。采用小板燃烧法研究了氧化石墨烯用量对膨胀型防火涂料的阻燃性能的影响。结果表明:加入极少量氧化石墨烯(<0.01%),可提高涂料的阻燃性,当氧化石墨烯含量在0.005%时,涂层的耐燃时间可达432 s,炭层膨胀高度较未加氧化石墨烯涂层增加了13.04%。结合红外光谱(FT-IR)、X射线衍射(XRD)和扫描电子显微镜(SEM)等表征手段对炭层形貌进行分析可知,加入氧化石墨烯后炭层在300~500 ℃范围的热稳定性提高,燃烧炭层完整密实,隔热性能提高,耐燃时间提高。     

海泡石和EG对水性膨胀型钢结构防火涂料的影响

采用可膨胀性石墨(EG)和海泡石对传统的APP/PER/MEL膨胀型防火涂料体系进行改性,制备了一种新型水性超薄膨胀型防火涂料,并采用防火性能测试装置、热重分析(TGA)、差热重量分析(DTG)及X射线衍射(XRD)等方法对该防火涂料的耐火性能、热降解过程、炭化层结构进行了研究。热分析结果表明,海泡石与EG复合使用,将充分发挥它们的协同作用:EG在较低温度区域能够延缓炭化层的形成,而海泡石则能够在高温区域阻止炭化层氧化分解,并提高成炭率从而达到阻燃的目的。XRD结果显示,复合使用EG和海泡石能够促进炭化层中TiP2O7的形成,在高温阶段保护炭化层不被氧化。当防火涂料中添加质量分数3%海泡石和质量分数2%EG,涂层厚度为1.0 mm时,钢材的耐火时间达到72 min。     

Influence of nano-boron nitride on anti-aging property of waterborne fire-resistive coatings

The influence of nano-boron nitride (BN) with a multilayered structure on the anti-aging property of fire-resistive coatings was studied. After accelerated weathering for 20 days, the thermal stabilities and fire protection of the coating without nano-BN were significantly decreased, but the coating modified by nano-BN still maintained excellent intumescent effect and fire protection. The results indicated that nano-BN could improve the anti-aging property of the coatings remarkably. FTIR and XPS characterizations suggested that nano-BN with a multilayered structure could prevent the migration behavior of the hydrophilic fire-retardant additives and keep the fixed ratio of those additives in the coating. TGA results demonstrated that nano-BN could effectively enhance the thermal stabilities of the aged coatings and improve the anti-oxidation property of the char layers formed by the coatings. XRD and EDS results proved that the anti-oxidation of the aged coatings under high temperature could be enhanced effectively after adding nano-BN. SEM observations illustrated that nano-BN addition was beneficial to the improvement of the foam structure of the aged coating.     

Effects of inorganic fillers on the performance of the water-based intumescent fire-retardant coating

The purpose of this research was to evaluate the influences of filler type and its content on the performance of a water-based intumescent fire-retardant coating. Three fillers (vermiculite, celite, and aluminum hydroxide) were added to the intumescent paint formulation. The thermal and fire protective properties were studied with thermogravimetric analysis (TGA), torch test, electrical furnace, scanning electron microscopy (SEM), and Fourier transform infrared analysis (FTIR). The results showed that adding fillers into coatings up to 3% could improve the intumescent coating's behavior and increase its endurance against flames. Of the three fillers used, vermiculite showed a better performance in the torch test, attributed to its chemical and physical structure. Vermiculite has low thermal conductivity and is considered an appropriate filler for heat-insulation. The final back-plate temperatures in the torch test for the vermiculite-containing samples were around 100°C–150°C lower than that of other samples. Moreover, vermiculite's addition improved the coating's expansion by 10% compared with the control sample's. The vermiculite sample's char layer morphology showed a uniform cell size distribution, indicating structural robustness. The coating samples successfully transformed polypropylene flammability from highly flammable to V0 level in the UL 94 vertical burning test standard. The results showed that vermiculite could improve intumescent paint's fire resistance and be used as an enhancer in intumescent coating formulations.     

Formulation and study of corrosion prevention behavior of epoxy cerium nitrate–montmorillonite nanocomposite coated carbon steel

Nanocomposite coatings which were applied on carbon steel panels based on epoxy cerium nitrate–montmorillonite (MMT) were synthesized and formulated. Nanoparticles were incorporated into epoxy resin by mechanical and sonication processes. The state of dispersion, dissolution, and incorporation were characterized by optical microscopy, sedimentation tests, X-ray diffraction, and transmission electron microscopy. To investigate anticorrosive properties of nanocomposite coatings, electrochemical impedance spectroscopy and salt spray tests were employed. The experimental results showed that epoxy cerium nitrate–MMT nanocomposite coatings were superior to the neat epoxy in corrosion protection effects. In addition, it was observed that the corrosion protection of nanocomposite coatings was improved as the clay loading was increased up to 4–2 wt% cerium nitrate.     

Effect of melamine and its salts on combustion and thermal decomposition of polyamide 6

Melamine and its salts added to polyamide 6 (PA-6, nylon 6) improve its fire retardancy as measured by oxygen index and UL94 tests. The mechanism of the fire-retardant action of the additives was studied using thermogravimetry, kinetics of thermal decomposition and characterization of solid residues and evolved high-boiling products. It was found that melamine, melamine oxalate, melamine phthalate and melamine cyanurate facilitate thermal decomposition of PA-6 with increasing evolution of oligomeric chain fragments instead of caprolactam, which is the principal product evolved from the nonfire-retarded PA-6. These additives promote non-combustible flow dripping and help extinguishment of the flame. The observed increase in solid residue from the thermal decomposition of the formulations or the endothermic cooling due to melamine evaporation might give an additional but less important contribution to fire retardancy. In the case of dimelamine phosphate and melamine pyrophosphate, PA-6 reacts with liberated phosphoric acids producing phosphoric esters which give char upon further thermal decomposition. The fire-retardant effect of these two salts is mostly attributed to polymer mass retention and intumescent layer protection mechanisms. © 1997 John Wiley & Sons, Ltd.     

Effects of inorganic fillers on the shear viscosity and fire retardant performance of waterborne intumescent coatings

In the present work, the effects of inorganic fillers on the fire retardant performance of waterborne intumescent coatings are investigated by thermogravimetry (TG), capillary rheometer, X-ray diffraction spectroscopy (XRD) and fire retardant test, etc. The TG results indicate that the thermal stability of vinyl acetate-vinyl ester of versatic acid copolymer (hereafter VAc-VeoVa) in VAc-VeoVa/Si–Al powder composite or in VAc-VeoVa/Halloysite nanometer-tube (HNTs) composite is improved mainly due to the release of the crystal water in Si–Al powder or HNTs. Capillary rheometer analysis results demonstrate that the VAc-VeoVa/HNTs composite melt possesses the highest shear viscosity, because of the large specific surface area of HNTs and the strong interaction force between HNTs and VAc-VeoVa. Weight loss difference (ΔT) of filler/ammonium polyphosphate (APP) composites show antagonism effects at 300 °C < T < 650 °C and synergistic effects at T > 650 °C. The fire retardant test results show the coatings using TiO₂/Si–Al powder/HNTs (8/1/1) as multiple fillers obtains an intumescent char layer with intumescent ratio of 28.14 and presents excellent fire retardant performance (3327 s). It is found that the high melt viscosity, resulted from the effect of inorganic filler, immobilizes the relaxation and rotation of polymer chain, restricts the intumescent behavior of the coatings, which leads to the formation of an intumescent char layer with lower intumescent ratio and the shortening of the fire retardant time. Moreover, the antagonism effect between filler and APP reduces the catalytic dehydration efficiency of pentaerythritol (PER) and VAc-VeoVa, which, as a result, also affects the final fire retardant performance of coatings.     

Thermal shielding performances of nano-structured intumescent coatings containing organo-modified layered double hydroxides

Cone calorimetry tests performed at 50 kW/m² heat flux have been exploited for assessing the fire resistant properties of nano-structured intumescent coatings containing modified layered double hydroxides (hydrotalcites, LDHs) and deposited on steel plates. The effects of different types of modified hydrotalcites (i.e. magnesium–aluminum lactate hydrotalcite, magnesium–aluminum gluconate hydrotalcite, magnesium–aluminum hydrotalcite modified with a fatty acid, magnesium–aluminum hydrotalcite modified with rosin) on the thermal shielding performances of the intumescent coatings and their intumescent degree have been thoroughly discussed and compared with the pristine unfilled counterparts.More specifically, the coatings containing organo-modified LDHs showed better thermal shielding performances with respect to the reference intumescent coating; on the contrary, the use of unmodified hydrotalcite in the intumescent formulations was found detrimental. The thermal shielding performances of the coatings filled with modified LDHs were found to be strictly related to the intumescent degree developed during the cone calorimetry tests. In addition, it was possible to compare the thermal shielding performances of the nanofilled coatings by evaluating the temperatures achieved after 2000 s exposure to the 50 kW/m² heat flux of the cone: the thermal shielding performance sequence was LDH-GL > LDH-RS > LDH-LA > LDH-FA > LDH).Finally, the intumescent degree of the modified coatings was found to decrease with increasing the hydrotalcite content, hence lowering their thermal shielding performances.     

Effect of the incorporation of montmorillonite-layered double hydroxide nanoclays on the corrosion protection of epoxy coatings

A series of layered double hydroxide (LDH)/montmorillonite (MMT) nanocomposite coating, LDH nanocomposite coating, and MMT nanocomposite coating were successfully prepared. The nanocomposite materials were characterized by X-ray diffraction and scanning electron microscopy (SEM). To understand the effect of MMT and LDH on the corrosion inhibition performance of epoxy resin coatings immersed in 3.5 wt% saline solution at 90°C, electrochemical impedance spectroscopy and an autoclave test were performed on epoxy resin; epoxy resin blended with LDH, MMT, and LDH + MMT (LM) coatings painted on Q345 steel. The metal/coating interfaces were observed by SEM and energy-dispersive spectroscopy. Results showed that addition of LDH and MMT improved the protection properties of the epoxy resin coatings. The corrosion protection of the LM nanocomposite coating was superior to that of the other coatings. This finding can be attributed to the ionic selectivity and barrier effect of MMT and LDH nanoclay platelets dispersed within the composite coatings.     

Eggshells: A novel bio-filler for intumescent flame-retardant coatings

The aim of this study was to develop intumescent flame-retardant coatings that incorporate chicken eggshell (CES) waste as a novel eco-friendly bio-filler. Three flame-retardant additives, namely, ammonium polyphosphate phase II, pentaerythritol and melamine were mixed with flame-retardant fillers and acrylic binder to synthesize the intumescent coatings. The fire performance of the coatings was evaluated in accordance with ‘BS 476: Part 6-Fire Propagation’ and ‘BS 476: Part 7-Surface Spread of Flame’ test standards. It was found that 4 out of 5 of the coated specimens (B, C, D and E) neither showed surface spread of flame nor any afterglow combustion upon fire exposure. The addition of 5.0 wt% and 2.5 wt% eggshell bio-filler into formulations B and E, respectively, improved fire protection due to char formation, with better morphology, height and structure of the protecting shield. The filler compositions of samples D (3.4 wt% TiO₂/3.3 wt% Al(OH)₃/3.3 wt% Mg(OH)₂) and E (2.5 wt% TiO₂/2.5 wt% Al(OH)₃/2.5 wt% Mg(OH)₂/2.5 wt% CES) applied at a thickness of 1.5 ± 0.2 mm achieved the lowest fire propagation index with a value of 4.5 and 5.0, respectively (BS 476 Part 6, Class 0 materials) which indicates excellent fire-stopping properties. The results showed that the coatings were effective in fire protection, with good qualities of water resistance, thermal stability, and adhesion strength. Significantly, coating E (with CES) has proved to be efficient in the protection of plywood against fire.