Synthesis And Application Of Siloxane Polyurethane Sol As Wool Antifelting Agent

Textile finishing by sol-gel methods is a currently developing technology.In our lab's early works,γ-glycidyloxypropyltrimethoxysilane(GPTMS) sol was applied to wool anti-felting industrialized finish by using sol-gel technology and curing temperature at 180℃,which reached the technical standards of machine wash for pure wool fabric(Woolmark TM No.31) and the requirements of current international market(area felting rate of pure wool fabric≤3%).Although this technique has resolved the environmental pollution,e.g.AOX value produced by the traditional anti-felting process of Chlorine-Hercosett,due to the high curing temperature,the wool fabrics treated with GPTMS sol yellowed and caused a color change,which restricts a further promotion of this technology.In this paper,polyurethane with different structure and molecular weight were introduced into 3-aminopropyltriethoxysilane(APTES) for the target of reducing the curing temperature.Firstly,based on molecular design,isophorone diisocyanate(IPDI) was reacted with propylene oxide triol(PPT) and polyethylene glycol(PEG) separately and two types of isocyanate-terminated prepolymers were obtained.In this step,the influence of temperature,time, amount of catalyst,molar ratios of NCO/OH,as well as the types of polyether on the pre-polymer reaction was researched,and a prescription of the prepolymer reaction was proposed. Then,PPT and PEG silanol-terminated polyurethane precursors were obtained after the isocyanate-terminated prepolymers were blocked by 3-aminopropyltriethoxysilane(APTES).The influence of the amount of APTES(depending on the molar ratio of NCO/NH₂),reaction temperature,reaction time,as well as solvents used on the block reaction were discussed,and a prescription of the block reaction was proposed.Meanwhile,the prepolymer and block reactions were verified by Fourier-transform Infrared Spectroscopy(FTIR) analysis.Finally,multiplied silica-hydroxyl-terminated PPT and PEG siloxane polyurethane sols were obtained after the precursors hydrolyzed in an acid condition.At the same time,the proportion in quantity between alcohol and water,pH value,and time during the hydrolysis reaction of the precursors were also selected.Referring to the test results of ²⁹Si-NMR and mechanical properties of gel films,the preparation prescription of the sols were proposed at last.Besides that,the physical and chemical properties of the gel films made from the sols were characterized by thermal analysis(TGA,DTG), wide-angle X ray diffraction(WAXD) and scanning electron microscopy(SEM) analysis.On this basis,the sols were applied to wool anti-felting finish,and GPTMS sol was studied as a referent.The influence of curing temperature and time on the anti-felting effect was focused on. And the results show that the treatment by PPT siloxane polyurethane sol with a curing temperature of 120℃endows the wool fabric an area felting rate of 2.4%,which attained the technical standards of area felting rate of pure wool fabric≤3%.The test results of mechanical properties,CIE Lab values,K / S value as well as the yellowing index indicated that compared to GPTMS sol,a mild change in the chromatic aberration occurred in the wool fabric treated by PPT siloxane polyurethane sol,which indicated that the tendency of yellowing of the treated fabrics eased,and the changes in the mechanical properties of them were in a acceptable range. Meanwhile,the results of thermal analysis(TGA,DTG),wide-angle X ray diffraction(WAXD) and scanning electron microscopy(SEM) analysis indicated that the thermal properties and crystallinity of the treated wool fabrics by PPT siloxane polyurethane sol were both slightly changed,and the edges of the scales of the treated wool fibers were blunted and the scales coated with thin films,which reduce the sliding tendency between the scales,that is,the coefficient of directional fiction effect(DFE) was decreased.As a result,the shrink-proofing ability of the treated wool fabrics was improved.