Study On Synthesis Of Nitrogen-Phosphorus Flame Retardant And Its Application In Leather Making Industry

As an ancient and traditional industry, the applications of leather which have been developed to people's life and property of the field, such as sofa, furniture, interior decoration, aircraft and car inner decorations and so on. According to the latest research reports, the social damage caused by combustion of leather products is as much as the damage caused by textile, rubber, plastic, and the current research methods of resistance to flammability leather are divided into two kinds: first, optimize leather grafts by sifting tanning agents, retanning agents, faltiquoring agents, finishing agents type and dosage, and this work has previous studies by our team; second, screening textile, plastic, rubber and other areas of flame retardants to join in leather, but the compatibility between these flame retardants and leather is poor, also the handle feelings is hard to meet the market requirements of leather products about flammability resistance.Flame retardants can be divided into inorganic and organic flame retardant, organic flame retardants are divided into organic halogen flame retardant, phosphorus flame retardant, nitrogen flame retardant and nitrogen-phosphorus flame retardant. Inorganic flame retardants have low smoke, low toxicity, halogen-free, good stability and lower price as advantages, but the volume of addition is large, compatibility is poor, and influences material performance. Although the organic halogen flame retardants have good material compatibility, small additive amount, small performance effect, the existence of large amount of smoke, generates halogenating hydrogen plenty of toxic gases, to cause hazards to human beings and the environment, so people actively research new halogen-free flame retardants to replace the traditional flame retardants. And nitrogen-phosphorus flame retardant as an environmentally friendly flame retardant; which is the development of an inevitable future trend.In this thesis, by means of Michael addition reaction, the midbody of 3-dimethoxy-phosphoryl propionamide was prepared by dimethyl phosphite and acrylamide through solvent-free method while using sodium methoxide as catalyst. Then reacted with glutaraldehyde, N-(5-hydroxyvaleraldehyde)-3-dimethoxy-phosphoryl propionamide was synthesed, which is a kind of phosphorus and nitrogen-containing flame retardant. Through orthogonal design, the effects of molar ratio, temperature, reaction time, and pH are studied. The results show: the optimum conditions: n(acrylamide): n(glutaraldehyde)=1.0:0.65, reaction temperature is 80℃, reaction time is 3.0 hour, the maximum yield is 86﹪. The flame retardant was applied to wet blue leather in retanning crafts by changing dosages of flame retardant and the conditions of retanning crafts. The molecular structure, thermal stability of the product is characterized by infrared spectrum, polarizing melting point apparatus and DSC-TG analysis. Also, sensory performances and mechanical properties tests, flame resistance tests were used. The experimental results indicate that the thermal stability of the product is enhanced, the sensory performances are improved, the mechanical properties of the products are heightened, and the limited oxygen index is highly up to 29.3, also the results of the vertical combustion,smoke density show dramatically change, which can meet the flammability performance requirements. Furthermore, the results also indicate that the thermal stability and flame retardant properties of the leather are optimum when the dosage of flame retardants is 4﹪.The flame resistance retanning process to solve the current leather industry about retardant materials and the contradiction between the leather handle feelings, make the high efficiency, low smoke and favorable handle feelings to come true.Aim at the synthetic flame-retardant retanning agent coloring flaxen problem, limits its application scope in white and light leathers. In this paper, using activate carbon and hydrogen peroxide as decolorants to deal with the novel synthetic phosphorus-nitrogen flame retardanted retanning agent, the decolorant dosage,the pH,the decoloration temperature and the decoloration time were chosen as the four factors,and the optimal technological conditions were found as follows: activate carbon dosage 1.2g, pH 3.6, decoloration temperature 60℃, and decoloration time 1.5 h, the color removel rate can come up to 79.8﹪; v(hydrogen peroxide)/v(sample)= 1:2, decoloration temperature 50℃, decoloration time 1.0h, the color removel rate can reach to 84.6﹪. The experimental results indicate that this phosphorus-nitrogen flame retardanted retanning agent has good flame resistance and retanning performance. Utilizing activate carbon to dispose the retanning agent, the handle, fullness and softness of the leather have improved in some extent, compared with the blank group, the oxygen index of the leather has increased,and the time to reach the max smoke density is delayed, and the max smoke density is lower, also it is demonstrated that the results of retanning and flame resistance performance with activate carbon are superior to that with hydrogen peroxide. After comprehensive consideration, active carbon was selected as the optimal decolorant.The synthesis experiment of flame retardant was expanded double to 5 times, glutaraldehyde conversion was analysed and determined in this system, the yield profile correlated to the N-times enlarged experiment was fitted. In addition, announcements and factors affected the enlarged experiment process were discussed, to make preparations for the subsequent batch production.