Preparation And Leather Fatliquoring Properties Of Gemini Fatty Alcohol Phosphate Bonded With Dihydric Alcohol

Gemini surfactant is a new chemical additive with unique properties.As a characteristic component of functional leather chemicals,Gemini surfactant has been widely used in various processes of leather making.Long-chain phosphate surfactant is already a hot topic in fatliquoring researching for its combined performence.In this paper,Gemini phosphate surfactants was synthesized by POCl₃ method,and the reaction conditions were optimised,meanwhile properties of the products were anlyzed.Effect of linked-chain length and the number of carbon in dihydric alcohol on the properties of Gemini phosphate surfactants were investigated.we explored the rules about performance and appearance of fibers with the series of products fatliquored into the wet-blue leather.The rules are intended to provide a theoretical basis for in-depth research on Gemini phosphate fatliquorings and their application.Using different dihydric fatty alcohols（ethylene glycol,1,4-butanediol,1,6-hexanediol,1,10-decanediol）and aliphatic alcohols（n-octyl alcohol,n-decyl alcohol,dodecyl alcohol,cetyl alcohol）as raw material,using POCl₃ as phosphorylation reagent,four series of Gemini fatty alcohol phosphate surfactants were prepared（product’s series abbreviated as 8-m-8,10-m-10,12-m-12,16-m-16,where m=2,4,6,10）.The optimized synthesis conditions are as follows:under the nitrogen gas flow,the dihydric fatty alcohols binding reaction temperature is 2°C,reaction time is 8h;the aliphatic alcohols esterifying reaction temperature is 30°C.When the hydrolysis and neutralization are finished,the products were evaporated and recrystallized by absolute ethanol.The purified products was confirmed by FT-IR and ¹H-NMR.Subsequently,The relationship between the properties（such as particle size,surface tension,emulsion stability,emulsifying power,foaming）and stucture of the series of products was analyzed.The results showed that:due to the role of electrostatic repulsion of diphosphate head group,Gemini surfactants with—（CH₂）₂—binding group have the smallest particle size and the lowest surface tensionas as well as the best emulsifying power and the stable foam,Surface activity of 8-2-8is the best among four series,and its particle size is 1.27nm,the surface tension is 22.7mN/m.In each series,with the growth of the binding chain,the particle size,emulsification and foam volume of gemini surfactants increase gradually,however foam stability decreases.The surface tension result showed that the surface tension of 8-m-8,10-m-10,12-m-12 increases and then decreases,and16-m-16 gradually decreases with the growth of the binding chain,but them all lower than the monohexadecanol phosphate surfactant P-16.As the hydrophobic fatty alcohol tail grows,the particle size and the surface tension of Gemini surfactants increases gradually while the foam is more unstable（16-m-16 is almost no foam）.Series of Gemini fatty alcohol phosphate surfactants were used for sheep wet-blue leather with conventional fatliquoring treatment,and the correlation between the structure and the performance of leather was explored.As the hydrophobic tail or binding chain grows,tensile strength,softness of all leather increases while the conductivity decreases.With the binding chain grows（same hydrophobic tail）,the tear strength of series leather increases overall,moisture permebility（hygienic properties）do not change much.With hydrophobic tail grows（same binding chain）,the tensile strength,the tearing strength and the softness of series leather increased,and waterproofness is enhanced.It is found that Leather fatliquored by 12-m-12 and 16-m-16 have good comprehencive performance,When the dosage increased from 5%to 12%,the softness,tensile strength and waterproofness increased.When the dosage exceeds 12%,the softness,tensile strength and water-resistance hardly increase,so 12%dosage is better for fatliquoring effect.Meanwhile the reason of better waterproofness is confirmed by XPS detection.