The Research Of Urea Formaldehyde Foam And Modified Urea Formaldehyde Foam

Based on China's building materials industry,we have more stringent requirements on thermal insulation materials recently.To improve the flame retardant of polystyrene and polyurethane foam and reduce manufacturing costs of phenolic foam,we have synthesized a new thermal insulation materials with good flame retardant and low manufacturing costs.This thermal insulation materials is urea formaldehyde resin.And we modified this urea formaldehyde resin foam by using chemical methods,we synthesized melamine-urea-formaldehyde foam.We studied how these factors the foaming process,curing agent,foaming agent,surfactants impacted on the properties of those foam.The work in this paper included:Urea formaldehyde foam was prepared by using urea formaldehyde resin,phosphate which was used as curing agent,magnesium carbonate which was used as foaming agent and the surfactant.Then the mechanics performance,the microstructure,the apparent density,the coefficient of thermal conductivity and the flame retardant performance of urea formaldehyde foam was studied by adjusting the quantity of curing agent,the quantity of foaming agent,the viscosity of resin,the types of surfactants and the quantity of surfactants.The results showed that when we used chemical foaming method to synthesize the foam,the content of phosphoric acid which is used as curing agent should be 5.0wt%?7.0wt%;the content of magnesium carbonate which is used as foaming agent should be about 3.0wt%;the percentage of water should be controlled at about 15wt%;and the content of Span80 which is used as surfactant is 0.9wt%.Finally,we used orthogonal experiment to optimize the foaming process,the foam have good property when the content of magnesium carbonate,phosphoric acid and water is 2.8wt%,6.0wt%,15wt%.Melamine urea formaldehyde resin was synthesized by using melamine and urea formaldehyde resin.Then melamine urea formaldehyde foam was prepared by using melamine urea formaldehyde resin,phosphate which was used as curing agent,magnesium carbonate which was used as foaming agent and the surfactant.We compared the property of urea formaldehyde resin with the property of melamine-urea-formaldehyde resin.We found that melamine-urea-formaldehyde foam had better flame retardance and better water resistance than urea formaldehyde foam.Then we stuied the properties of melamine-urea-formaldehyde foam by changing the content of curing agent,foaming agent,surfactants.The results showed that those factors had great influence on the mechanical properties,the microstructure and fragility properties of melamine-urea-formaldehyde;and those factors had little influence on the limited oxygen index(LOI),thermal conductivity and formaldehyde emission of melamine-urea-formaldehyde foam.melamine-urea-formaldehyde foam had excellent properties when the content of curing agent,foaming agent,surfactants was15%,2.5%and 12%.Then we studied the thermal properties of melamine-urea-formaldehyde foam,the result showed that the char yield of melamine-urea-formaldehyde foam was 11.87%at 900?.And the contents of gas generated by burning melamine-urea-formaldehyde foam included CO,CO2,NH3 and H2O.The curing mechanism of foam was analyzed by 13C NMR and FT-IR.The principle curing reaction was the polycondensation among hydroxymethyl groups,hydroxymethyl groups and amino groups of melamine-urea-formaldehyde resin.The results provided base data for further researches and application of melamine-urea-formaldehyde foam.