| Traditional wallpaper is categorized as a single functional product,demanding no rigid techniques and inferior in added-value.Research and development of multifunctional environment-friendly wallpaper products is of important significance to increase its technical content and enhance its market competitiveness.It will drive the development trend of indoor wall decoration materials towards the improvement of environmental protection and multifunction.In this paper,the traditional polyvinyl chloride(PVC)coated wallpaper has been ameliorated into multifunction:amelioration of visible-light photocatalysis on the surface of PVC,amelioration of flame-retardancy in PVC layer,and improvement of the mildew resistance on the surface of paper-based layer.Experiment results showed that the prepared PVC coated wallpaper is proved with visible-light degradation of formaldehyde,flarne-retardancy and anti-mould activity.Experiments and key findings of this paper are listed as follows:Nitrogen doping titanium dioxide(N-Ti02)was prepared by sol-gel method using urea as the source of nitrogen and tetrabutyl titanateas the source of titanium.The effect of molar ratio of N/Ti,drying process of sol,temperature and time of gel calcination on photocatalytic activity of N-Ti02 was systematically investigated in the paper.Results showed that visible-light catalytic activity of rhodamine B(RhB)solution degradation of N-Ti02 was significantly improved after replacing with urea as nitrogen source,and the optimal molar ratio of N/Ti was 1:1.Vacuum freeze-drying process of sol was firstly used to prepare N-Ti02.Compared with the traditional heated-air drying process,N-Ti02 with higher catalytic activity,higher crystallinity,smaller particle size and larger specific surface area was prepared under-50℃ and 15 Pa for 12 h.Calcination temperature and time significantly affected the photocatalytic activity of N-TiO2.The optimal calcination temperature and time was 400℃and 4 h,respectively.Surface chemical environment and optical absorption performance of N-TiO2 was characterized in this paper.X-ray photoelectron spectroscopy analysis showed that 400 eV and 396 eV absorption peak were appeared in N1s of N-Ti02,in accordance with the nitrogen lattice with valence state of N5+in N-O-Ti bond and N3-in Ti-N bond respectively.This phenomenon can be attributed to the doping of N ions into the Ti02 lattice.UV/VIS diffuse reflection spectrum analysis showed that N-Ti02 was able to absorb light in the visible properties.UV/VIS absorption spectrum analysis showed that the highest absorption peak of RhB had a significant blue shift simultaneous with peak falling.This phenomenon proves the photocatalytic oxidation degradation of N-Ti02 on RhB.The photocatalytic PVC coated wallpapers were prepared by coating N-Ti02 on PVC surface.The influence of molar ratio N/Ti,sol drying process,calcination temperature and time of gel on photocatalytic degradation activity of formaldehyde gas of the photocatalytic PVC coated wallpaper were systematically investigated in this paper.The results showed the best degradation of formaldehyde gas activity in visible-light was achieved when preparing coated N-Ti02 with molar ratio N/Ti was 1:1,using freeze-drying to dry sol,and it was 400℃ and 4 h for calcination during preparation,which indicates the best photocatalytic activity of coated N-Ti02.The degradation rate of formaldehyde gas had reached 65.22%after 12 hours’ visible-light irradiation.In this paper,an experimental equipment saving time on measuring concentration change of formaldehyde gas and visible-light catalytic activity was self-designed,and an evaluation and test method of visible-light catalytic degradation of formaldehyde gas using PVC coated wallpaper has been set up firstly.The flame retardant PVC coated wallpaper was prepared by adding inorganic flame retardant into the PVC paste while using tritolyl phosphate(TCP)as PVC plasticizer to replace the traditional PVC paste(dioctyl phthalate).The flame retardancy of flame retardant PVC coated wallpaper was systematically investigated in the papers.The results showed that either adding inorganic flame retardant 2Zn0-3B2O3·3.5H2O(ZB-2335)or adding plasticizer TCP separately,the flame retardancy of PVC coated wallpaper will be increased to a certain extent.The flame retardancy,thermal stability,smoke abatement and wet tensile strength of horizontal of wallpaper can obviously be improved by preparing with TCP as plasticizer and adding 5%of ZB-2335.It showed that a synergistic effect of flame retardant was generated by ZB-2335 and TCP.The limited oxygen index of flame retardant PVC coated wallpaper had reached 32.5,which was 51.2%higher than traditional wallpaper,and reached the requirements of the flame retardant standard level B1 listed the national standard(GB 8624-2012).Thermogravimetric properties of inorganic flame retardant,PVC plasticizer and PVC coated wallpaper was tested in this paper.Thermogravimetric analysis showed that a good thermal stability can be kept before 307℃ for PVC coated wallpaper when using TCP as PVC plasticizer.Initial degradation temperature of ZB-2335 was at about 300℃while thermal decomposition rate of flame retardant PVC coated wallpaper was always less than traditional wallpaper after 300℃.This phenomenon illustrates the fact that thermal decomposition of ZB-2335 had improved the flame retardancy and thermal stability of the material.ZB-2335 had accelerated pyrolysis after 300℃ and released vast amount of water vapor simultaneously.The thermolysis product ZnCl2 and B20 would cover on the surface of PVC to inhibit combustible gases and slow down the rate of combustion.In view of the above factors,the flame retardant and thermal stability of PVC coated wallpaper had improved immensely.The chitosan/antimould microspheres emulsion was prepared by using chitosan/glacial acetic acid mixture solution as carrier,using sodium tripolyphosphate solution as cross-linking agent and using ionic cross-linking method.The mould inhibition effect of chitosan/antimould microspheres in PVC coated wallpaper was systematically investigated in the papers.The results showed that by using ionic cross-linking method,there was a synergistic effect of mildew resistance in prepared chitosan microspheres emulsion,attributed to sodium fluoride and chitosan microspheres,and the optimum mass ratios of sodium fluoride,sodium tripolyphosphate and chitosan was 2:7:28.The mould-proof PVC coated wallpaper could be prepared by spraying chitosan/sodium fluoride microspheres emulsion on the surface of based paper.The mildew resistance area of aspergillus Niger had reached the requirements 100%as the antimould activity standard level 0 with the national standard(GB/T 24346-2009).Surface morphology,particle size distribution and chemical change of chitosan/sodium fluoride microspheres were tested in this paper.TEM observation results showed that chitosan/sodium fluoride compounds existed in microspheres.Laser granulometer analysis results showed that particle size of chitosan/sodium fluoride microspheres was uniformly distributed and average particle size was 615nm.Fourier infrared spectrometer analysis results showed that sodium fluoride and chitosan were formed chitosan/sodium fluoride microspheres by physical cross-linking method under the action of sodium tripolyphosphate.These test results are the proof that chitosan/sodium fluoride microspheres are more likely to adhere on the base paper than sodium fluoride powder.Through this way,the retention rate of sodium fluoride in PVC coated wallpaper could be improved immensely. |
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