Synthesis And Application Of Polyacrylate Water-repellent Agent Based On Modified Nano-SiO₂

Polyacrylate water repellent agents are main non-fluorine productions in market for textiles hydrophobic finishment.Nano-scale silica particles can enhance hydrophobicity of textile through increasing the surface roughness of fabric.It also can improve hand feeling and whiteness of fabric.In this thesis,polyacrylate water-repellent emulsions with long-chain alkyl groups was prepared by the polymerization of(methyl)acrylate monomers.The compound surfactant contained sodium dodecyl sulfate and polyoxyethylene stearate was used as emulsifier.The ratio of sodium dodecyl sulfate and polyoxyethylene stearate in the compound was decided by HLB=8.The amount of compound surfactant for polymerization was 10%of the total weight of monomers.Potassium persulfate(0.5%of the total weight of monomers)was used as the initiator.The mole ratio of octadecyl acrylate(SA)to methyl methacrylate(MMA)was 1:2.5,and glycidyl methacrylate(GMA)was 10%of the total weight of MMA and SA.Monomers were emulsified separately and were added into reaction system with controlled feeding rate,which was finished with 2-3 hours.The polymerization was operated at 75? for 4 hours with a solids content of 15.97%and a monomer conversion rate of 79.84%.Polyacrylate water repellant agent based on modified nano-SiO2 was synthesized through pre-emulsification method.Nano-SiO2 particles with C=C bonds was prepared through the hydrolytic polycondensation of vinyltrimethoxysilane(VTMS)and tetraethoxysilane(TEOS).VTMS and TEOS were dispersed in the water solution of sodium dodecyl sulfate and polyoxyethylene stearate with ammonia as catalyst.Nano-SiO2 particles with C=C bonds,MMA,SA and GMA were polymerized to obtain nano-SiO2 modified polyacrylate water repellant emulsion.The mass ratio of TEOS to VTMS was 1:2,the total amounts of VTMS and TEOS were 4.5%of the emulsion mass,ammonia was 1.5%of the emulsion mass.The reaction for the synthesis of nano-SiO2 particles were operated at 30? for 6 hours.The mole ratio of SA to MMA was 1:2.5,and GMA was 10%of the total weight of MMA and SA for the polymerization of polyacrylate water repellent agent based on modified nano-SiO2 with a solids content of 13.84%and a monomer conversion rate of 75.58%.The characterization of synthesized polyacrylate and polyacrylate based on modified nano-SiO2 water repellent emulsions showed that the emulsions had good stability.The FTIR and XPS tests results suggested that the polymerization occurred between monomers.TG curves indicated that both the two polymers had great thermal stability,and the thermal performance of polyacrylate could be significantly improved with the modification of nano-SiO2.The optimal reaction conditions for the treatment of cotton fabrics with synthesized polyacrylates were that fabric was first immersed in synthesized emulsions with a concentration of 60 g/L,and then it was prebaked at 80? for 60 s followed by the baking of 150? for 180 s.The static contact angles of finished fabrics were 142°±2° for synthesized polyacrylate emulsion and 147°±2° for polyacrylate emulsion based on modified nano-SiO2,respectively.The FTIR,XPS,SEM,AFM of treated fabric showed that synthesized emulsions could membranes on the surface of the fibers and the surface roughness of fibers was improved obviously due to the existence of nano-particles.It was found that the treated fabrics had an excellent washing fastness.Fabric has a little decrease with breaking strength.The polyacrylate emulsion modified with nano-silica particles could increase the whiteness of fabrics compared with the one without modification.