Study On Release Of Formaldehyde And Color Improvement Of Polyoxymethylene Products

Polyformaldehyde resin is a kind of engineering plastics with excellent comprehensive properties,which is widely used in household appliances,electronic and electrical,automotive,building materials and precision machinery industries.Polyformaldehyde products are classified into high viscosity,medium viscosity and low viscosity.High viscosity polyformaldehyde products,whose trade name is M25 in Yunnan Yuntianhua Limited by Share Ltd,is a general polyformaldehyde with high strength and toughness,and it is mainly used in bars,plates and conveyor belt parts.In this paper,aiming at the characteristics of yellowing and large release of formaldehyde content of M25 products,a series of experiments such as HAAKE thermal performance test,low temperature surface formaldehyde content determination,residual formaldehyde measurement and so on were carried out.Finally,the goal of reducing the yellow index and formaldehyde release of M25 products was achieved.The experimental results show that pointing at the yellowing of M25 products,the removing maleic hydrazide and calcium carbonate and improving the content of M(Melamine)to 0.25% can obviously reduce the accelerated yellowing of HAAKE melts from the formula.HAAKE melts without passivator M25 had the lowest accelerated yellowing.Triethanolamine passivator has a great effect on the accelerated yellowing of M25 powder HAAKE melt.The effect of quaternary ammonium salt passivator on the accelerated yellowing of M25 powder HAAKE melt was small.The reduction of engine speed and load had a positive impact on the color of M25 particles.Aiming to the release of formaldehyde from M25 products,reducing the particle size is beneficial to the decrease of formaldehyde emission.Reducing the load is beneficial to reduce the release of formaldehyde.Prolonging the post-treatment time of 140 ? particles to 12 h is beneficial to diminish the release of formaldehyde.Through further theoretical research,the experience of production practice will be thoroughlysublimated,which will play a certain role in promoting and guiding future product production.