Study On Preparation And Properties Of The Sizing Agent Based On Leather Collagen Modified By Epoxy Compound

Leather,as a kind of biomass modified material,is favored by many consumers because of its excellent performance,which makes the leather industry contribute to the promotion of global economic development.However,with the rapid development of tannery industry,a large number of waste from tannery edge materials have been produced.Landfilling or burning them directly cause serious environmental pollution problems and lead to great waste of resources.To solve the pollution of tannery wastes by effective means has become a focus point of all sectors of society.In this study,three kinds of sizing agents?SA?were synthesized by cross-linking and grafting modification of collagen hydrolysate obtained form collagen with three epoxy compounds?glycol diglycidyl ether?GDE?,tetrahydrophthalate diglycidyl ester?TDE?and triglycidyl p-aminophenol?TP??.And the hydrophobic monomers were styrene?St?and butyl acrylate?BA?.The morphology and basic properties of sizing agents were studied.Using corrugated paper as paper model,the sizing performance of sizing agent and its synergistic sizing effect with starch sizing agent were studied.Specifically as follows.Firstly,the glycol diglycidyl ether as crosslinking agents,styrene and butyl acrylate as hydrophobic monomers,and the collagen hydrolysate was modified by cross-linking-grafting.A sizing agent,GDESA,was synthesized by modifying collagen hydrolysate with ether epoxy compound.The collagen hydrolysate and sizing agent were characterized by Fourier transform infrared spectroscopy?FT-IR?.The results showed that the collagen hydrolysate was successfully crosslinked and grafted.Video optical contact angle meter,tension index tester,computer controlled compression tester,paper tear tester and stiffness tester were used to test the water resistance and physical and mechanical properties of corrugated paper sized under different process parameters.The optimal synthesis conditions for the preparation of GDESA by single factor experiment were as follows.The Mn of collagen hydrolysate was¹0000,the amount of the cross-linking agent was 10 wt.%of collagen hydrolyzate,the cross-linking reaction pH was 9,m?hydrophobic monomer?:m?collagen hydrolysate?was 2:1,the amount of initiator was 0.8 wt.%of hydrophobic monomer,and the reaction temperature was 90°C.Under these condition,the grafting rate of synthetic GDESA sizing agent emulsion was 80%,the precipitation rate was 0.7%,the emulsion stability was good,and the contact angle of corrugated paper was 122.1°.The tensile index,tear strength,ring pressure index and stiffness were 57.35 N m/g,299.341 mN,11.14 N m/g and9.87 mN m,respectively.Secondly,the collagen hydrolysate was crosslinked and grafted with epoxy compound?tetrahydrophthalate diglycidyl ester and triglycidyl p-aminophenol?,styrene and butyl acrylate were used as hydrophobic monomers.Two sizing agents?glycidyl ester epoxy modified collagen hydrolysate sizing agent and glycidylamine sizing agent?TDESA and TPSA??were synthesized.The basic properties of sizing emulsion were tested by precise pH meter,electronic moisture meter and digital viscometer.The results showed that the three kinds of sizing emulsion were acidic.Among the three sizing agents,the solid content?27.21%?and viscosity?10.04 mPa s?of GDESA sizing emulsion were the largest.The microstructures of collagen hydrolysate and three sizing agents were characterized by FT-IR.The results showed that the collagen hydrolysate was successfully cross-linked and grafted.The molecular weight and particle size of the collagen hydrolysate and three sizing agents were determined by GPC and nanoparticle surface potential analyzer.The results showed that the GDESA sizing emulsion was relatively stable and with the best dispersion.The thermal stability of collagen hydrolysate and three sizing agents was characterized by thermogravimetric analyzer.The results showed that the collagen hydrolysate was successfully modified.The static water contact angle of corrugated paper was measured by video optical contact angle meter.The results showed that the water droplets of unsized corrugated paper were completely absorbed within 20 s,while the contact angle of GDESA sizing corrugated paper was 117.2°.The corrugated fiber was observed by scanning electron microscope?SEM?.The results showed that the corrugated paper fibers after GDESA sizing were the most compact and the surface of the fibers was the smoothest.The physical and mechanical properties of corrugated paper were tested by paper thickness tester,tensile index tester,computer controlled compression tester,paper tear tester and stiffness tester.The results showed that the physical and mechanical properties of corrugated paper with GDESA as sizing agent were the strongest.The thickness,stiffness,tear strength,tension index and ring pressure index of corrugated paper were 1.2,2.1,1.6,1.5 and 2 times of those of unsized corrugated paper,respectively.The bending resistance of corrugated paper before and after folding was studied by taking photos of water droplets on corrugated paper.The water droplets on the corrugated paper sized by GDESA can still be completely retained,completely.Finally,a series of composite sizing agents?SGDESA-1,SGDESA-2,SGDESA-3 and SGDESA-4?were obtained by mixing the GDESA sizing agent synthesized under the optimal experimental conditions with starch sizing agent according to different mass ratios.The compound sizing agent was applied to the surface sizing of corrugated paper,and the physical,mechanical properties and water resistance of corrugated paper were tested.Then the application performance of the common styrene-acrylic polymer sizing agent?SAE?and compound sizing agents was compared.The results showed that compared with SAE sizing agent,the tear strength,stiffness,tension index and circumferential pressure index of corrugated paper with SGDESA-2 sizing agent are 1.5,1.4,1.2and 1.9 times higher than SAE sizing agent respectively,and the water absorption value of 60 s(Cobb₆₀)is 1.1 times lower.It changed the shortcoming of poor water resistance of corrugated paper coated by starch sizing agent alone.By testing the flexural properties of corrugated paper,it was found that when SGDESA-2 sizing corrugated paper was folded 20 times,the corrugated paper still showed the maximum contact angle?125.5°?,which indicated that SGDESA-2 sizing corrugated paper had the best flexural properties.