Study On The Preparation And Properties Of Flame-Retardant Polyurethane Sealing Material For Mine Use

One of the main facilities to ensure mine ventilation and safety is to construction of the seal wall in coal mine,but there are same problems in the construction standards,technology,equipment,material properties and sealing effect of seal walls in China,so many coal mine accidents were related to poor airtight of the seal wall.In order to solve this problem,polyurethane foam was widely applied to seal materials in the coal mine,due to its some advantages such as fast foaming speed,high foaming rate and good adhesion.The application of polyurethane foam provides a guarantee for safe and efficient production of the mine.In this paper use the different ratio of the soft polyurethane foam and rigid polyurethane foam to obtained suitable for mechanical properties and water resistance polyurethane sealing material（PUM）,and study combustion performance of the expandable graphite（EG）as the main flame retardant was added into PUM.EG with many flame retardants shows good synergistic effect,so EG was compound added into PUM with inorganic flame retardant and organic flame retardant agent,respectively.The results showed that the EG with borax shows the better synergistic effect of flame retardancy than other EG with inorganic flame retardant was added into PUM samples,and which best ratio is 8:4.In the EG with organic flame retardant was added into PUM samples,the EG with dimethyl methylphosphonate（DMMP）shows the better synergistic effect of flame retardancy,and which best ratio is 8:4.In the same amount of addition,the EG/DMMP shows better flame retardant effect than EG/borax was added into PUM.The PUM samples after flame-retardant treatment shows the better flame retardant effect,but its shows the poor mechanical properties and water resistance,which is because the large amount of flame retardant and the poor compatibility with PUM.In order to solve this problem,because EG with phosphorus containing flame retardant shows good synergistic effect of flame retardancy,so EG was modified by the phosphorus element to obtained modified EG（EGP）,and EGP was added into PUM.The PUM/EGP shows the better flame retardancy and reduces the effect of mechanical properties and water resistance for flame retardant was added.Tannic acid is complex polyhydric phenols,in which there is multiple phenolic hydroxyl,which can simultaneously form a stable chelate with Fe³⁺.This chelate can form a nanoscale film cling to any substrate interface.Via chelation reaction of tannic acid with the Fe³⁺in the surface of EG to obtained microencapsulated EG（EGM）,its compatibility in PUM was great improved,and improve the mechanical properties and water resistance.Meanwhile,the Fe³⁺in ferric tannin can be improve the flame retardancy and smoke suppression of PUM sample.