Study On Preparation And Properties Of Waterborne Polyurethane Fluorescent Material

Small organic brightener molecules have poor water-solubility and toxic and side-effect,detached easily from the matrix and causes contamination of the system to be measured,which caused that the use of specialty paper,cotton spinning,and environmental science have been greatly limited.In order to improve these shortcomings,a new synthesis method of fluorescent waterborne polyurethane emulsion was designed in this paper.The method used chemical reaction to type small organic fluorescent compounds with hydroxyl groups(amino groups)into the chain of waterborne polyurethane(WPU).The obtained product had the advantages of both PU and fluorescent,and its dispersion was uniform and its performance was stable.In this paper,fluorescent waterborne polyurethane preoplymer was succes-sfully synthesized by anionic self-emulsification method with isophoronediisoc-yanate(IPDI),polycaprolactone diol(PCL-1000),2,2-dimethylolpropionic acid(DMPA),trimethylolpropane(TMP)and as main raw materials and dibutyltin dilaurate(DBTDL)as catalyst,the self-made fluorescent compounds of small molecules were chain extenders.Through prepolymerization,triethylamine(TEA)was neutralized,and finally water was dispersed.And the synthesis process was optimized by changing the isocyanate index R and carboxyl content.The effects of small molecular fluorescent agents with different mass fraction on the properties of waterborne polyurethane were also studied by single factor inquiry method.(1)The 5,7-dihydroxy-4-methylcoumarin was synthesized by perkin meth-od with phloroglucinol and ethyl acetoacetate as main raw materials and1,4-dioxane as solvent.The structure were characterized by ~1H NMR,FTIR and the results showed that the expected product was successfully synthesized.A series of fluorescent waterborne polyurethane(FWPU)emulsions were prepared by the reaction of hydroxyl groups of DHMC with isocyanate groups.The structure and properties were characterized by FTIR,dynamic light scattering(DLS),ultraviolet spectrum(UV-Vis),fluorescence spectrometer and atomic force microscopy(AFM),mechanical properties and thermogravimetric analysis(TGA).The results showed that the particle size distribution was uniform and narrow(PDI=0.101),the emulsion had a strong UV absorption peak at 310nm,the strongest fluorescence of the film was 432181.97 a.u.,the tensile strength of the film was 18.5 MPa and the thermal decomposition temperature was 329.11℃when wt(DHMC)=0.60%.With the increasing of mass fraction of DHMC,the fluorescence intensity and mechanical properties of the film increased first and then decreased,and the thermal stability of the films were improved obviously.In the application experiment,the synthesized fluorescent polyurethane emulsion from ordinary paper were evaluated—as the surface sizing agent on handsheet by scanning electron microscope(SEM),whiteness and sizing degree and the paper’s application performance was investigated.The results showed that the sizing degree increased firstly with the weight fraction of the sizing agent and then tended to smooth.Specially,if wt(DHMC)was 0.60%,fluorescent polyurethane as sizing agent had better whitening effect on paper.(2)The 4,4’-diaminodiphenylethylene-2,2’-disulfonic acid was synthesized by catalytic hydrogenation method with DNS acid as main raw materials.The structure was characterized by means of FTIR,and the result showed that the expected product was successfully synthesized.A series of uniform and stable SWPU emulsions were also prepared by adjusting the ratio of-NH to-NCO.The results showed that when the optimum dosage of DSD acid was 2%,the average particle size of SWPU emulsion is 44.61 nm and the distribution was narrower than that of FWPU.The fluorescence intensity of the film was432181.97 a.u.and the fluorescence quantum yield was 36.40%.The mechanical properties and thermal stability of the film were improved.With the increase of DSD acid content,the crystallinity and contact angle increased,the phase separation degree of the film decreased,and the fluorescence intensity and mechanical properties of the film first increased and then decreased.In the application experiment,the synthesized fluorescent polyurethane emulsion from ordinary paper were evaluated—as the surface sizing agent on handsheet by whiteness,sizing and paper surface strength(dry&wet)and the paper’s application performance was investigated.The results showed that compared with FWPU sizing,the sizing agent was better for paper whitening,and the sizing degree increased with the increase of the weight fraction of sizing agent.(3)The 4-hydroxyethyl-N-(2-hydroxy-1-hydroxymethylethyl)-1,8-naphth-alimide was synthesized by 4-bromo-1,8-naphthalic anhydride,2-amino-1,3-propanediol and aminoethyl alcohol as main raw materials,through imidization and substitution reactions.The structure was characterized by means of FT-IR,and the result showed that the expected product was successfully synthesized.A series of uniform&stable and green fluorescence BWPU emulsions were also prepared by adjusting the ratio of-NH to-NCO.The HHHNA films were characterized by the same method.The fluorescence intensity of the film was708078.65 a.u..The results showed that the fluorescence property of BWPU film was the strongest,the BWPU5 was 708078.65 a.u.,the mechanical property was 50.40 MPa,and the thermal stability was obviously improved.