Advantages of chelating properties of biological buffer Bicine in papermaking coating

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It is generally understood that Bicine is commonly used as a pH buffer in biological systems or medical research. Few reports about its good chelating properties are known. Chelating agents are widely used in analysis, printing and dyeing, chemical industry, papermaking, food, leather, wastewater treatment, etc.



N,N-Dihydroxyethylglycine (Bicine) is a white crystalline amino acid analog that is easily soluble in water. It contains two -OH and one -COOH, which has good chelating properties. At pH 9, it can chelate iron ions, and its stability constant is slightly lower than EDTA. It cannot chelate calcium and magnesium ions, but can chelate other metal ions. Let's take a look at the advantages of its chelating properties in papermaking coating.


Zirconium is an element of the fourth subgroup of the fifth period of the chemical periodic table, and its usual coordination number can be as high as 8. Aluminum is an element of the third main group of the third period with a maximum coordination number of 6, and its complexing ability is very strong. Propylene glycol and -COOH as ligands both contain electron-donating groups, both of which are bidentate ligands. The aluminum atom and the zirconium atom are connected to form a stable six-membered ring structure through the monoOH of propylene glycol and the -COOH of N,N-dihydroxyethylglycine. One of the COOH and aluminum and zirconium atoms form an oxygen complex bridge structure.


This coupling agent has more inorganic reaction points (aluminum and zirconium) than silane coupling agents, which can enhance the surface interaction with inorganic fillers or pigments. The tertiary amine group of the organic ligand N,N-dihydroxyethylglycine is cationic, which better combines with the surface of the negatively charged fiber, so that the inorganic filler or pigment and the organic matrix produce special functions. Molecular bridge". It can inhibit the agglomeration of inorganic fillers, disperse particles and reduce viscosity. It breaks through the limitation that the traditional aluminum-zirconium coupling agent is oil-soluble and uncharged, so that the aluminum-zirconium coupling agent can not only deal with the treatment of plastics, rubber and other fillers, but also extend to the treatment of powders in water-based systems such as paint, paper, leather, etc. , Has expanded its application areas.


N,N-Dihydroxyethylglycine has good chelating properties, and the coupling agent involved in the synthesis has a satisfactory effect on papermaking coating. After the coupling agent is added, the whiteness of the paper is not affected, and the napping speed and ink absorption are improved; at the same time, the viscosity is greatly reduced, and the rheology of the coating is enhanced, which is beneficial to the coating operation and reduces energy consumption.