Microwave-assisted Synthesis Of Nano Zinc Phosphate And Its Application

Zinc phosphate has many advantages, such as non-toxic, environmental friendlyand good dispersibility. Now it has been widely applied in the anti-corrosive pigments,open-framework materials and so on. With the development of science and technology,it will exhibit more potential applications in catalysis, biology, electrical conductivityand magnetism. In this paper, cotton fabric with UV-blocking and flame retardantcapabilities were prepared using zinc phosphate as UV-blocking and flame retardantfinishing agents by microwave-assisted in situ synthesis and traditional pad-dry-curemethod.The research included three parts. The first part studies the synthesis of Nanozinc phosphate under microwave irradiation, using zinc nitrate, zinc acetate, zincsulfate, sodium dihydrogen phosphate and phosphate, diammonium phosphate, urea,hexamethylenetetramine and guanidine carbonate as raw material. The products werecharacterized by XRD, IR and TG-DTG. At the same time, the number of crystalwater of zinc phosphate was studied under different drying temperature. The resultsshowed that the product is four hydrated zinc phosphate at80°C; when it is heated at140°C, it becomes a mixture of two hydrated zinc phosphate and four hydrated zincphosphate.The second part studied the preparation of cotton fabric having UV-blockingcapabilities. In the experiment, the fabric was finished in the flask containing thesolution of zinc ions, phosphate ions and alkali agents. After microwave radiation of20minutes at80℃, the sample was padded twice, and cured at140℃after treatingseveral minutes at80℃. It showed that the UV-resistance capabilities of samplesincreased with the increase of concentration of zinc sulfate, curing temperature andcuring time; the microwave temperature and time had no obvious influence on theUV-resistance capabilities. However, the UV-resistance capabilities decreased with theincrease of concentration of urea. When urea was not used, the treated cotton fabric had very good resistance to ultraviolet and low tear strength. After the addition of urea,the tear strength of treated fabric became much better. The best processing conditionis: the concentration of zinc sulfate is0.4mol L-1, the concentration of urea is0.7mol L-1, microwave reaction for20minutes at80℃, dried for4min at80℃andcured for3min at140℃. The UPF value of treated fabric was55.28, compared to23.58of original fabric; the warp tear strength of treated fabric was1091.01cN, wefttear strength was633.16cN, compared with the original fabric, the tear strength lossof treated fabric is very small.The third part studied the preparation of flame retardant cotton fabric. In theexperiment, the fabric was finished in the flask containing the solution of zinc ions,phosphate ions and alkali agents. After microwave radiation of20minutes at80℃,the sample was padded twice, and cured at140℃after treating several minutes at80℃. It showed that the flame retardant capabilities of treated fabric increased withthe increase of concentration of zinc sulfate without urea. After the addition of urea,the flame retardancy and tear strength both have a great improvement. The resultshowed that the fabric treated with urea alone almost had no flame retardancy; thefabric treated with the mixture of urea and zinc phosphate has better flame retardancy.TG-DTG analysis showed that the onset decomposition temperature and thetermination decomposition temperature increased with the increase of concentrationof urea; on the contrary, the onset and termination decomposition temperaturedecreased with the increase of concentration of zinc phosphate. As compared with theoriginal fabric, the onset decomposition temperature, termination decompositiontemperature and maximum decomposing rate of treated fabric both decreased a lot.The best processing condition is: the concentration of zinc sulfate is0.4mol L-1, theconcentration of urea is1.7mol L-1, microwave reaction for20minutes at80℃, driedfor4min at80℃and cured for3min at140℃.SEM analysis was investigated to study the surface morphology of the cottonfabric before and after burning. The results showed that the fiber surface of originalcotton fabric was smooth and had a certain degree of natural curvature. After burning,the cotton fiber became hollow and the structure of the fabric was severely damaged; the fiber surface of treated cotton fabric had many tiny particles. The fibers appearedto be almost intact. In order to test the washing fastness of treated fabric, elementalanalysis was investigated after washing. The results showed that the content of zincphosphate on fabric didn’t show significant change, which illustrated that zincphosphate can firmly adhere to fabrics. Finally, the treated fabric was analyzed inorder to analysis the nature of particles on the burned fabric with XRD analysis. Theresults showed that those particles are anhydrate zinc phosphate.