Synthesis Of A Novel Yellowing Inhibitor And Study Of Its Use For High-Yield Bamboo Pulps

In the high-yield bamboo pulps there is a lot of lignin which lets it be yellowed easily, and limits the scope of its use and economic benefits. There are a lot of studies on inhibiting light-induced yellowing of high-yield pulps with additives. A new fiber-reactive yellowing inhibitor was synthesized from radical scavenger, 4-amino-2,2,6,6-tetramethy piperidine (TAD). The synthetic process of fiber-reactive yellowing inhibitor was optimized, and the structure of final product was established by UV and FTIR. By sizing and surface spraying experiment in APMP bamboo pulps, the yellowing inhibition effect of final product, TAD and purchased UV-absorber was compared, and the application condition of final product was studied. The mechanism of final product inhibiting yellowing of APMP bamboo pulps was studied by SEM and FTIR.The optimized synthetic process conditions are listed as follow:The first step: the molar ratio of cyanuric chloride to TAD is 1:1; the pH of the reacting system is 8～9; the reaction temperature is 7℃; the reaction time is 2h; choose ethyl alcohol as the dissolvent, and the mass ratio of ethyl alcohol to cyanuric chloride is 7:1.The second step: choose deionized water as the dissolvent, and the dosage of deionized water is 50ml when the dosage of product in the first step is 0.005mol; the molar ratio of cationic reagent to the product in the first step is 2:1; the pH of the reacting system is lower than 7; the reaction temperature is 30℃; the reaction time is 1h. From the UV-Visible spectrum and FTIR-IR spectrum of the final product, major absorption peaks of the reactions can be found, which means the reaction carried out in the expecting way, and the main structure of reactions was in the final product.The application in APMP bamboo pulps indicated that the effect of the final product to inhibit yellowing is much better than TAD and a bit better than purchased UV-absorber, and the final product has synergy with UVA. The effect tends to be stable when the dosage of product is up to 0.7%.The SEM figure of paper sample indicates that the product is fiber-reactive and can stay in the fiber web structure. The FTIR indicated that the amount of chromophores groups in paper sample before and after light-inducing was effected by product and UVA in different ways.The novel yellowing inhibitor is fiber-reactive, can be used in high-yield bamboo pulps and inhibit its light-induced yellowing much better than TAD.