Preparation Of Hemp Powder Coating And Its UV Resistance

As tempereture rises, the environment pollution is more and more serious, the ozone layer is destroyed, and the intensity of ultraviolet radiation to the surface of the earth increases, the harm to human health isincreasing, and the amount of skin cancer patients are increasing yearly. Therefore, anti ultraviolet(anti-UV) textiles have been highly valued by people, and now in the research of anti-UV fabric, TiO2, ZnO and other inorganic nano particles or organic compounds are mostly, and some finishing agent on the environment also has a certain degree of pollution, with strong anti-UV, non-polluting natural materials are becoming the focus of the research. The application of hemp powder in the anti-UV fabric can broad the use of hemp fiber, but also solve some problem of the anti-UV fabric environmental pollution, save the costing to provide new methods for the study of anti-UV fabric.This paper prepared 10 kinds of hemp powder, according to grinding hemp fiber with the use of high energy nano impact grinding, and changed the grinding time, the interval time of each two kinds of powder was 2 hours. Through the SEM, FTIR, powder particle size, DSC and other analytical methods, the morphology,structure and properties of the hemp powder were characterized. Then two particle size difference between the largest hemp powder body were added to aqueous polyurethane, polyester fabric as Substrate was prepared by coated fabric, analysis and discuss the influence of hemp powder on the basic performance, focusing on the discussion of the hemp powder content,hemp powder particle diameter, waterpoly ammonia ester content, fabric thickness of coated fabric anti ultraviolet performance impact.The experimental results show that:(1) when the total grinding time was 12h, the hemp powder reaches the "grinding limit", and the particle size reaches the minimum. At the same time, the mechanical polishing of hemp fibers, not only changes the morphology of the hemp, but also changes its structure and properties. However, there is no new functional groups. The category of molecular groups is consistent with the fibers, and the change of grinding time does not affect the performance of hemp. (2) With the add of waterborne polyurethane, anti-UV property of the fabric enhanced, but once excessive, the anti-UV performance weakened, due to high viscosity coating agent; the content was differentthe with the different particle size, when the content of large particle size powder was 6%, the anti-UV performance was the best, when the content was 4%,the anti-UV property of small particle size powder coating reached the optimal; the anti-UV property of the two coatings both became better and then worse; anti-UV property of small particle size powder coating was better; with the particle size of the hemp powder was different, the properties of the coating were also different. Hemp powder with small particle size dispersed more evenly in the waterborne polyurethane, the surface of the coating had less pores, powder distribution was more clearly, but because of the smaller particle, and the connection of waterborne polyurethane was more compact, the thickness of the coating was slightly larger; hemp powder added in the coating improved the moisture permeability and air permeability, but air permeability was overall poor.