The standard was formulated by the Shenzhen Polymer Industry Association and jointly developed by 19 upstream and downstream companies that produce melt-blown materials, melt-blown cloths and medical masks. It passed the expert review on May 13, 2020.

　　Compared with existing standards:

　　First, the existing standard only involves six technical indicators: appearance, melt mass flow rate, volatile matter, ash, molecular weight distribution and residual amount of di-tert-butyl peroxide. The group standard has been increased to 11 technical indicators, respectively increasing the density, melting point, odor, n-hexane extract and xylene extract 5 indicators, and appropriately improved the original 4 indicators.

　　Second , the group standard has special medical indicators. On the basis of the national standard, three indicators were added: odor, n-hexane extract and xylene extract.

（R-03）