Study Of High-Powered Urea Formaldehyde Molding Compound

For the preparation of high-performance urea formaldehyde molding compound, this paper has studied in detail the influence on the quality of urea-formaldehyde resin, processing properties, mechanical properties and thermal stability of urea formaldehyde molding compound from synthesis process, liquidity modifier and fillers. The critical conclusions are as below:When the mass ratio of formaldehyde and hexamine is 100:1, the comprehensive performance of urea formaldehyde molding compound is the best and compared with urea formaldehyde molding compound when the mass ratio of formaldehyde and hexamine is 23:1, bending strength increases by 17.1% and heat distortion temperature increases by 10℃; When urea is added in batches, and holding time is 30min, the temperature is 60℃, the comprehensive performance of urea formaldehyde molding compound is the best, and compared to condition 1, the rate of increase of the bending strength and modulus are respectively 18% and 4 %;With the onset temperature of the solution of formaldehyde and hexamine increase, the bending strength and modulus are the largest at 60℃, the rate of increase of the bending strength and modulus are respectively 8.1% and 2%.The fluidity of urea formaldehyde molding compound which are blended with hydrophilic fluidity modifiers in the dry process technique of production is better than the one blended with lipophilic fluidity modifiers;The fluidity of urea formaldehyde molding compound increases by only 16.7% when stearin is added by 1.2 copies and the fluidity increases by 24% when PEG1000 is added by 0.5 copies. When PEG1000 and PEG400 were used at the same time, the outward appearance of urea formaldehyde molding compound was not influenced, and when the allocated proportion was 7:3, the fluidity increases by 20%.When used as the stuffing of urea formaldehyde molding compound, wood powder can enhance the bending strength, reduce bending modulus, and obviously improve the shock strength of urea formaldehyde molding compound, and the shock strength is increased by 45% when wood powder is added by 24%; wood pulp and wood powder have synergy and can enhance the bending strength of urea formaldehyde molding compound; However, the mixed proportion is not arbitrary, and when the content of wood powder increases to 60%, the bending strength will be reduced. When the amount of curing agent is 0.9%, urea formaldehyde molding compound achieves the best overall performance.With the content of rice husk powder in the filler system increase, the bending strength and the impact strength of urea formaldehyde molding compound is gradually reduced; Changes of the ratio of paper pulp and rice husk powder have no great influence on the bending modulus of urea formaldehyde molding compound; With the content of rice husk powder increase, the heat distortion temperature is firstly reduced and then increased; The heat distortion temperature of urea formaldehyde molding compound when rice husk powder is added by 60% reached the maximum and compared to the one added pure wood pulp paper, only increases by 6℃.