Synthesis Of A Kind Of Leather Flame Retardant & Technology Of Flame Retardanted Leather Manufacture

In order to safeguard the security and property of consumers, it is necessary to endow leather fire-resistance. Since the flammability of leather is greatly impacted by leather making technology, especially by the wet processing and fire retardant used, the research on both fields are very importamt. This paper consist of twosections: the first section is about the synthesis and characterization of a new type of flame retardant——pentaerythritol-dihydrogenphosphate biseste-malamine, and another is committed to revaluate the influences of retanning, fatliquoring and flame retandant treating processes on the flame resistant of leather. In the first section, the flame retardant——pentaerythritol-dihydrogenphosphate biseste-malamine was synthesized with phosphorus oxychloride, pentaerythritol and tripolycyanamide as raw materials and through two steps. The first is the reaction between phosphorus oxychloride and pentaerythritol to synthesis pentaerythritol phosphonyl dichloride (PDC) and the other is the reaction beween PDC and tripolycyanamide to prepare pentaerythritol-dihydrogenphosphate biseste-malamine. And then, the pentaerythritol-dihydrogenphosphate biseste-malamine was modified by formaldehyde and sodium bisulfite to endow it some properties suitable to the wet processing of leather manufacture. By some preliminary experiments, aluminium chloride was chosen as the catalyst in the first reaction and triethylamine was determined to be the acid-capture in the second reaction to increase the productive rate. The influencing factors of productive rates in both processes were studied by orthogonal experiment. In the first reaction, the results indicated that: according to the influence degrees to productive rate of the intermediate product PDC, the influence factors can be ranged as: mol ratio of phosphorus oxychloride and pentaerythritol(D) >reaction temperature(A) > reaction time(B)> dosage of catalyst (C), and the best condition to obtain the greatest productivity was A3B4C3D4, that is, when phosphorus oxychloride, pentaerythritol and AlCl3 are mixed with the mol ratio of 7.5:1:0.06 and react at 75℃for 10h, the highest productive rate should be realized. In the second reaction, influencing factors can be range as : addition reaction time (H)> hydrolyze reaction time (F)> hydrolyze reaction temperature (E)> addition reaction temperature (G), and the best reaction condition was E2F3G1H2, i.e. the proper hydrolyze reaction temperature , hydrolyze reaction time, addition reaction temperature addition reaction time are 80℃, 4h, 60℃and 3h respectively. In the second section, the influences of retanning agents and fat liquors on leather's flame resistance were studied and the flame retardant prepared in the first section experiments was also applied in leather and compared with other common flame retardants. The flammabilities of leather samples were tested by two methods —vertical flame test (ALCA Method E 50) and oxygen index test method (ASTM D 2863-74). In the retanning experiment, the results showed that retanning procedures by vegetable tannin, glutaraldehyde, synthetic tanning agent and resin tanning agent performed after chrome retanning deteriorated the fire retardance of leather, while the chrome retanning process have no clear impact. Moreover, the oxygen index test indicated that the quantity of retanning agent was also the influence factors of flammability. In the fat liquoring process, all fat evidently decreased the flammability of leather, sulfating fats especially. The influence of sulphited fats was smaller than sulfating fats. And sulphited fish oil, sulfated neat's foot oil and lecithin had the performance to improve the glow resistance of leather in this experiments. In the application experiments of flame retardants, according to oxygen indexvalues of the leather samples, flame retardant effects on leather could be ranged as: ammonium polyphosphate > borax > phosphated amino resin > pentaerythritol-dihydrogenphosphate bisester-melamine> amino sulfonic ammonium. When the results of vertical flammability test were concerned, it is indicated that all flame-retardant chemicals can improve the fire resistance of leather, nevertheless borax, pentaerythritol-dihydrogenphosphate biseste-malamine and ammonium polyphosphate had better flame retardant effect to leather. Flame retardants have some influences on other physical and mechanical properties of leather samples, such as tensile strength, tearing strength, breaking stretch,thickness and Ts, but the influence of pentaerythritol-dihydrogenphosphate biseste-malamine is much smaller. All results indicate that pentaerythritol-dihydrogenphosphate biseste-malamine has retanning and filling effect on leather as well as good flame retardant effect, and have no bad impact on leather's colour, softness, grain condition. It is a good flame retardant in flame-resistant leather manufacture.