Explanation

With urea-formaldehyde resin as the base material, the interior is filled with countless micropores of plastics. This materials has low mechanical strength, when the density is 231 kg/m 3 Its compressive strength is 0.057 MPa perpendicular to the rising direction of foam and 0.081 MPa parallel to the rising direction of foam. The strength can be improved by adding a certain amount of reinforcing agent, such as polyethylene glycol ether, and fillers, such as wood powder, asbestos, glass powder, graphite and glass fiber. This materials was treated at 130 ° C for 12 hours, and then at -30 ° C for 12 hours. After one year of alternate treatment, its strength and cell structure did not change. This materials has good flame retardancy, heat insulation and sound insulation. It has high water absorption, and after soaking the sample in water and drying it at room temperature, the bubble structure remains unchanged. At 38 ° C and a relative humidity of 90%, the water vapor transmittance ranges from 24 to 27.5 g/m 2· H. However, this materials is not resistant to inorganic acids, strong bases and some organic acids, such as formic acid. In addition, it also has a certain bactericidal effect. The method for preparing this materials is to add the foaming liquid (composed of water, emulsifier, powder, foam stabilizer, m-diethylphenol and intermediating agent such as oxalic acid or phosphoric acid) into the bubbler, stir and fill it with air. After 1-2 minutes, add 30% aqueous solution of urea-formaldehyde resin. After stirring for tens of seconds, pour the mixture into the mold, conduct preliminary curing at room temperature for 4 hours, and then dry it at 50 ° C for 21 to 28 hours. This materials is usually used as a thermal insulation thermal insulation materials material, used to maintain soil moisture and nutrients in agriculture, and also used to make bandages with strong water absorption capacity, cotton and bandages for surgery, and to make artificial landscapes.

Classification