Preparation Of Polyacrylate/nano-SiO₂ Composite Emulsion By Miniemulsion Polymerization And Its Leather Finishing Performance

Miniemulsion polymerization is an emulsion polymerization method with "droplet nucleation" as the main nucleation mode.The morphology of organic/inorganic composite particles can be easily controlled,and more inorganic nanoparticles can be introduced in the polymer matrix by the miniemulsion polymerization.Based on the previous research of our group,the polyacrylate/nano-SiO₂ composite emulsion was prepared by miniemulsion polymerization to achieve the stable existence of a large amount of nano-SiO₂ particles in the polymer matrix,and the morphology of composite latex was encapsulated or coated.The effects of the existing form of nano-SiO₂ in the emulsion on the finished leather properties were investigated.The specific research contents are as follows:Nano-SiO₂ was hydrophobization by vinyltriethoxysilane.The encapsulated polyacrylate/nano-SiO₂ composite emulsion was prepared by miniemulsion polymerization.The effects of reaction temperature,dosage of sixteen alkyl（HD）,twelve sodium dodecyl sulfate（SDS）and SiO₂ on the composite emulsion and film-forming properties have been investigated.The composite emulsion was characterized by transmission electron microscopy（TEM）and dynamic light scattering particle size analyzer（DLS）,and the leather finishing performance had also been studied.The results demonstrated that when the dosage of HD,SDS and nano-SiO₂ was 2% respectively and the reaction temperature up to 75℃,the optimum composite emulsion and its film-forming properties was obtained.Most of the nano-SiO₂ were encapsulated in the polyacrylate latex particles,and the particle size of the emulsion was about 200⁶00nm.Compared with polyacrylate emulsion finishing leather,the tear strength and air permeability of the composite emulsion were improved to some extent.Meanwhile,the wet scrub-resistant improved semi-level and water vapor permeability had slightly lower.The surface-coated polyacrylates/nano-SiO₂ composite emulsion was prepared by miniemulsion polymerization using nano-SiO₂ particles and sodium dodecyl sulfate（SDS）both as stabilizers.The effects of mass ratio of butyl acrylate to methyl methacrylate（BA: MMA）,dosage of SDS and nano-SiO₂ on the composite emulsion and film-forming properties have been investigated.The effects of nano-SiO₂ and SDS dosages on the composite emulsion morphology was studied.Also,the leather finishing performance had been studied.The results demonstrated that when the BA:MMA was 6:4,the dosage of SDS was 0.3% and the nano-SiO₂ was 3% the optimum composite emulsion and film-forming properties was obtained.When the dosage of SDS was 0.3% and the dosage of nano-SiO₂ was 3%,the synergistic stability of the emulsion system was the best and the regular surface-coated polyacrylate/nano-SiO₂ composite emulsion was obtained.And it was conducive to improve the tear strength,permeability and wet scrub-resistant.The surface-coated polyacrylate/nano-SiO₂ composite emulsion was obtained by miniemulsion polymerization using nano-SiO₂ particles as sole stabilizer.The effects of nano-SiO₂ dosag,n-butanol and ammonium persulfate（APS）on the composite emulsion and film-forming properties have been investigated.The monomer conversion and morphology of the composite emulsion were studied at different polymerization times,and the nucleation mechanism of the composite latex particles was deduced.The surface of the composite emulsion film-forming was characterized by scanning electron microscopy（SEM）.The results demonstrated that when the dosage of nano-SiO₂ was 8%,the n-butanol was 2.5% and the APS was 3% the optimum composite emulsion and its film-forming properties was obtained.There were two main nucleation ways which were droplet nucleation and likeness micellar nucleation.The surface of the composite emulsion has irregular rough structure and void structure.Finally,the film-forming and leather finishing performance of encapsulated PA/SiO₂-S composite emulsion,coated PA/SiO₂-Q composite emulsion using nano-SiO₂ particles and SDS both as stabilizers,PA/SiO₂-W composite emulsion using nano-SiO₂ particles as sole stabilizer were compared with each other.The results of films performance showed that both coated composite emulsion film-forming performance were better than that encapsulation composite emulsion.The water resistance of PA/SiO₂-Q composite emulsion film was best.The tensile strength and thermal stability of PA/SiO₂-W composite emulsion was the best.The leather finishing results showed that the wet rubbing fastness of the leather with finishing by three kinds of composite emulsions was improving one level compared with commercially polyacrylate emulsion.The air permeability and water vapor permeability of leather which finished by coated PA/SiO₂-Q composite emulsion were rised respectively 39.1% and 4.9%%.Its increase rate was largest finished by PA/SiO₂-W composite emulsion,rised respectively 210.8% and 69.8%.4.