Properties And Self-organized Gradient Distribution Behavior Of Silicon Modified Fluorinated Acrylate-waterborne Polyurethane Composite Emulsion

At present,research on fluorine-containing self-organized gradient polymer materials has attracted attention.The phase structure or composition phase concentration in the gradient polymer materials spontaneously migrates to a certain interface of the material,and exhibits a gradient change,thereby obtaining a special surface function.The silicon-containing component is introduced into the fluorine-containing acrylate-waterborne polyurethane?PUFPA?,which has the characteristics of microphase separation during the film formation process by PUFPA.At the same time,the silicon-containing component and the fluorine-containing component show good compatibility and tendency By controlling the type and content of the silicon-containing component,the silicon-modified PUFPA emulsioncan form a film having a fluorine-containing component concentration self-organized gradient structure.In this paper,the inorganic silicon nano-SiO₂ modified fluorine-containing acrylate-waterborne polyurethane?SiO₂?was synthesized by miniemulsion polymerization using IPDI,PTMG,MDEA,TMP,nano-SiO₂,KH570,hydroxy silicone oil and perfluoroalkyl acrylate as raw materials?SiO₂/PUFPA?.Forthermore,KH570modifiedfluorine-containingacrylate-waterborne polyurethane?SiPUFPA?and different KH570 and hydroxy silicone oil ratio modified fluorine-containing acrylate-waterborne polyurethane emulsion?SiPUFPAx-y?,were prepared The effects of formulation components and process conditions,different silicon component content on emulsion and latex film properties and self-organized gradient behavior were studied.At last the silicon modified emulsions were applied as sizing agent for paper.The results show that:?1?The latex particles of the SiO₂/PUFPA emulsion exhibit a core-shell structure,and the shell phase region is larger than the core phase.The size of the colloidal particles is basically uniform.With the increase of the amount of nano-SiO₂,the surface tension of the emulsion first decreased and then increased.The appearance of the emulsions gradually became white and precipitated while the amount of nano-SiO₂ increased.The particle size of the emulsion was 89.44 nm when the emulsion was stable.The crystallinity of SiO₂/PUFPA is lower than that of the PUFPA latex film,and the thermal stability is higher than that of the PUFPA latex film.When the amount of nano-SiO₂ is3%,the tensile strength of the latex film is the largest,being 16.18 MPa.The water contact angles on the air-film surface and film-plate surface are 109.7°and128.9°,respectively.The oil phase contact angles on the air-filmsurface and film-plate surface are 71.6°and 82.5°,.respectively.The difference of free energy between the the air-film and film-platesurface is the largest,reaching14.75mN/m.The particles of the air-filmsurface are more uniformly fused.The cross section of the latex film is obviously layered from the air-flim surface to the film-plate surface.The fluorine-containing component migrates and enriches to the film-plate surface?F-P?,forming a distinct gradient structure in the thickness direction.?2?The optimal initiation polymerization temperature of the SiPUFPA composite emulsion was 75?,the polymerization time was 4h,and the dispersion stirring speed was 4000 rpm.With the increase of the content of silicone KH570,the particle size and viscosity of the emulsion gradually increase,and the color appearance of the emulsion becomes white and deepens to produce precipitation.The emulsion latex particles are spherical,the distribution is relatively uniform,and the core-shell structure is fuzzy.The roughness of the air interface of the latex film first decreases and then increases,which is weaker than the roughness of the PUFPA latex film,and the thermal stability of the modified latex film is improved.When the content of KH570 is9%,the difference between the contact angles and the surface free energy of the air-film surface and film-plate surface is the largest,and the tensile strength and elongation at break reach 14.60MPa and 206.06%.The latex film has a self-organized gradient structure,EDS indicats that the silicone has a promoting effect on the migration of the fluorine-containing component,and the fluorine-containing component migrates and enriches in the air-flim surface.?3?The SiPUFPAx-y composite emulsion latex particles are spherical,and have a distinct core-shell structure compared with the SiPUFPA latex particles,and the nuclear phase region is larger than the shell phase region.The ratio of hydroxy silicone oil to KH570 increased,the particle size of the emulsion decreases first and then increases.The stability of SiPUFPAx-y composite emulsion deteriorates with the ratio of hydroxy silicone oil to KH570 increase.The thermal stability and crystallinity of latex film are both higher than that of SiPUFPA and PUFPA latex film.When the ratio of KH570 to hydroxy silicone oil is 1:1.2,the fluorine element tends to be in the air-film surface,the latex film is obvious layered,and the fluorine-containing component migrates to the air-film?A-F?surface.The concentration of the fluorinated components gradually decreases from the air-film surface to the film-plate surface,and the self-organized gradient structure is more obvious than SiPUFPA.?4?The preferred sizing process of SiPUFPAx-y,SiPUFPA,SiO₂/PUFPA and PUFPA four composite emulsions on paper is as follows:sizing concentration is 1‰,drying temperature is 110?.SiPUFPAx-y is the bettert sizing agent.The contact angle can reach 133°.The fibers is bonded more closer after sizing.The surface fluorine content of the paper containing SiPUFPAx-y can reach 27.34%,which is 18.53%difference with the fluorine content of PUFPA surface,and the fluorine component migration degree is the largest.