Tong Hongping, Wang Weimin, Wang Gui, Wang Xiaojun, Yu Dongmei, Chen Bajin, Pei Kemei
School of Chemistry and Chemical Engineering, Zhejiang Sci-Tech University Hangzhou 310018 China
School of Materials Science and Chemical Engineering, Ningbo University Ningbo 315211 China.
RSC Adv. 2024 Oct 10;14(44):32031-32040. doi: 10.1039/d4ra05873a. eCollection 2024 Oct 9.
Waterborne polyurethane (WPU) offers many advantages and is widely used in coatings, leathers, adhesives, biomaterials, and other consumer products. However, WPU is highly flammable. Many reactive flame retardants have been developed, but their char formation efficiency is still unsatisfactory, and the melt dripping during combustion has not been effectively suppressed. In this paper, a novel phosphorus-containing flame retardant with dihydroxy groups, (6-((4-hydroxyphenyl)((4-hydroxyphenyl)amino)methyl) dibenzo[,][1,2]oxaphosphinine 6-oxide) (PHAD), was successfully synthesized and incorporated into WPU molecular chain as a chain extender, thereby synthesizing a series of non-ionic flame-retardant waterborne polyurethane (NFRWPU) emulsions. The chemical structure of NFRWPU was successfully characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance. With the help of a thermogravimetric analyzer, scanning electron microscope and other instruments, some key performance parameters of NFRWPU in applications were investigated, including: physical, mechanical, and thermal stability and flammability. Some important experimental results include: both the particle size and viscosity of the emulsion increase gradually with increasing PHAD content, and when the PHAD content reaches 12%, the average particle size of emulsion increases to 106.6 nm with a viscosity of 89 mPa s; with the addition of PHAD, the tensile strength of NFRWPU initially increased and then decreased, while the elongation at break showed a continuous downward trend. The maximum tensile strength reached 22.63 MPa, and the minimum elongation at break dropped to 1060%; the addition of PHAD improved the thermal stability and flame retardancy of the film, with the highest limiting oxygen index value reaching 25.6% and the maximum carbon residue increasing to 6.5%. All these results indicate that NFRWPU is a promising flame retardant WPU considering the comprehensive performance.
水性聚氨酯（WPU）具有诸多优点，广泛应用于涂料、皮革、胶粘剂、生物材料及其他消费品中。然而，WPU具有高度易燃性。人们已开发出许多反应型阻燃剂，但其成炭效率仍不尽人意，且燃烧过程中的熔体滴落现象尚未得到有效抑制。本文成功合成了一种含二羟基的新型磷系阻燃剂（6-((4-羟基苯基)((4-羟基苯基)氨基)甲基)二苯并[,][1,2]氧杂磷杂环庚三烯6-氧化物）（PHAD），并将其作为扩链剂引入WPU分子链中，从而合成了一系列非离子型阻燃水性聚氨酯（NFRWPU）乳液。通过傅里叶变换红外光谱和核磁共振成功表征了NFRWPU的化学结构。借助热重分析仪、扫描电子显微镜等仪器，研究了NFRWPU在应用中的一些关键性能参数，包括物理、机械、热稳定性和阻燃性。一些重要的实验结果包括：乳液的粒径和粘度均随PHAD含量的增加而逐渐增大，当PHAD含量达到12%时，乳液的平均粒径增大至106.6 nm，粘度为89 mPa·s；随着PHAD的加入，NFRWPU的拉伸强度先增大后减小，而断裂伸长率呈持续下降趋势。最大拉伸强度达到22.63 MPa，最小断裂伸长率降至1060%；PHAD的加入提高了薄膜的热稳定性和阻燃性，最高极限氧指数值达到25.6%，最大残炭量增加至6.5%。所有这些结果表明，综合性能方面NFRWPU是一种很有前景的阻燃WPU。
