Research On Preparation And Process Of Flame Retardant TPU Microcellular Foam Based On Supercritical CO₂

Thermoplastic polyurethane(TPU)has excellent physical and mechanical properties and good processability.The microcellular foaming material has the advantages of low density,good elasticity,low temperature performance and good cushioning property,and has become the research focus of production and application.However,due to its own flammable materials,TPU micro foam material is even worse.At present,the focus of the research is mainly on the research and development of flame retardant TPU,and the research and development of TPU microcellular foams.The research of modified flame retardant TPU micro foam material is very little.In this paper,the flame retardant composed of ammonium polyphosphate,melamine and cyanuric acid was prepared,and the flame retardant TPU material was prepared by using nano calcium carbonate as the synergistic agent.The TPU flame retardant was prepared by supercritical CO2 batch method.The foaming process was studied by orthogonal test,and the optimum foaming process was determined,and the influence of the process conditions on the foaming ratio of the material was discussed.With the increase of the amount of flame retardant,the flame retardancy of the micro foam material in TPU has been improved significantly.However,the micro foam material appears dry,cracking,etc,The SEM observation of flame retardant TPU micro foam material showed that the compatibility between flame retardant and TPU was poor.After the addition of flame retardant,the integrity and stability of the pore structure were significantly worse.But the nano calcium carbonate and flame retardants were added into TPU materials,the structure of the micro foaming material appearance and bubble hole have been greatly improved,and the flame retardant performance is also improved,which increased,then decreased slightly with the increase of nano calcium carbonate.The orthogonal experiment was used to find out the influence of foaming temperature on the foaming effect,and then the foaming time,saturation pressure and saturation time.With the increase of foaming temperature,saturation time and s foaming time,the foaming ratio increases firstly and then decreases.According to variance analysis of orthogonal test method,foaming temperature changes have significant influence on foaming ratio of flame retardant TPU foam material.