Research on flame-retardant paper prepared by the method of in-pulp addition of ammonium polyphosphate

At present, the production of flame-retardant paper usually uses impregnation method phos-phorus-nitrogen flame retardants in paper. There are few reports on application an in-pulp addition method. In this paper, solubility ammonium polyphosphate (APP) and its effect were investigated for use It was found that APP particles square, with average particle size 21.88 μm. The decreased significantly after immersion water at 25°C 24 h. Furthermore, most APPs dissolved 90°C 0.5 h, residuals agglomerated their shape turned into amorphous form. possessed strong electronegativity could partially ionize water. 0.18 g/100 mL increased quickly when temperature higher than 30°C. Therefore, should be added to pulp temperatures below tensile strength initially APP, it reached maximum value content 10% then gradually decreased. limiting oxygen index (LOI) 28.7% amount 30% cationic polyacrylamide (CPAM) 0.08%, reaching level.