Synthesis And Properties Of Multifunctional Light Stabilizer Based On Coumarin

In recent years, expanding and improving the application range and efficiency of high yield pulp have become an ideal way for the paper industry to effectively utilize the wood fiber resources, and the pulp brightness could reach 85 ISO%. However, the high yield pulp contains much more lignin and the way of bleaching is usually the "retain lignin type", leading to the bad light stability of high yield pulp. Long term exposed to the sunlight, the structure of lignin will easily generate Chromophore and Auxochrome, resulting in the yellowing of high yield pulp. Researches show that the yellowing of high yield pulp could be reduced by using the light stabilizer. However, the traditional light stabilizers are small organic molecules, having some deficiencies, such as bad water-soluble, high toxicity, bad combination with fiber of paper, signal function et al, which result in the limitation of practical applications of them in the paper industry. If the water-soluble can be improved and various additives can be used cooperatively, the yellowing of high yield pulp would be inhibited in different ways, presenting the multifunction effect. Based on this design idea, a series of light stabilizers of high yield pulp were synthesized.In this paper, a water-soluble small weight light stabilizer was synthesized firstly. Based on the Pechmann method,7-amino-4-methylcoumarin fluorescent brightener agent was synthesized by the reaction of 3-amino phenol and ethyl acetoacetate, catalyzed by Lewis acid. Then, inducting the 2,3-epoxypropyltrimethylammonium chloride(a cationic etherifying agent) and 7-amino-4-methylcoumarin, the cationic 7-amino-4-methylcoumarin fluorescent brighteners was synthesized. Secondly, two kinds of water-soluble polymeric light stabilizers were synthesized by polymerization. The 7-amino-4-methylcoumarin fluorescent brightener agent and 2,4-dihydroxybenzophenone ultraviolet absorbent agent are raw materials and respectively react with acryloyl chloride, obtaining fluorescent brightener monomer and ultraviolet absorbent monomer. Then the two monomers respectively react with acrylamide and trimethyl-2-methacroyloxyethylammonium and two kinds of water-soluble polymeric light stabilizers were synthesized. Finally, a water-soluble multifunction polymeric light stabilizer was synthesized, through the reaction of fluorescent brightener monomer, ultraviolet absorbent monomer, acrylamide and trimethyl-2-methacroyloxyethylammonium.The structures of the target products were characterized by FT-TR,1HNMR, and GPC. The optical properties of them were discussed by the ultraviolet spectrum and fluorescence spectrum. The thermal stability of products and microtopography of surface sized papers with products were determined by TG and SEM. Through the Surface sizing experiment, the surface strength and smoothness of surface sized papers with products were measured. At last, the application effect of the yellowing inhibition on paper was evaluated by the UV accelerated aging test. Results show that the cationic coumarin fluorescent brightener agent has a better hydrophilicity and restrains the paper back to yellow for a long time. After the UV accelerated aging test for 48 h, the brightness and PC value of coated paper with product are 10.11 ISO% and 8.1, which is lower than that of blank paper by 9.4 ISO%; Both of the polymeric light stabilizers not only have better hydrophilicity, but also own excellent light stability, film-forming property and anti-UV aging property. After the UV accelerated aging test for 48 h, the brightness and PC value of coated paper with products are respectively 68.58 ISO%,53.82 ISO%,2.46 and 4.9, which are lower than those of their initial brightness by 9.87 ISO% and 14.70 ISO%; The multifunction polymeric light stabilizer can well reflect the synergistic interaction between different groups, which owns better hydrophilicity, light stability, film-forming property and anti-UV aging property. After the UV accelerated aging test for 48 h, the brightness and PC value of coated paper with 0.4% product is respectively 65.46 ISO%, which is lower than that of its initial brightness by 8.03 ISO%.