Research On The Technology Of Modified Melamine Formaldehyde/Phosphate Composite Foamed Thermal Insulation Material

Thermal insulation materials are materials which have a thermal conductivitylower than0.2W/m·K. They are widely used in buildings due to their excellent thermalinsulation properties. At present, the most widely used thermal insulation material isorganic insulation material, which is not up to the flame retardancy standard required bythe document lately enacted by Ministry of Public Security. So developing new kinds ofnon-combustible thermal insulation materials is of great urgency.To get non-combustible material, a kind of inorganic thermal insulation materialwas prepared firstly. It was found that it is possible to get a kind of inorganic foamedpanel by mixing phosphoric acid, aluminium hydroxide, magnesium oxide, zinc oxideand carbonate. Phosphoric acid and aluminium hydroxide was mixed together to get aphosphate solution. The ratio of the number of atom aluminium to that of phosphateatom is in the range from1/5~1/2. Magnesium oxide and zinc oxide was subsequentlyadded. The ratio of the total number of metal atoms to that of phosphate is in the rangefrom2/3~3/2. Basic magnesium carbonate was used as foaming agent, which accoutsfor20%~30%of the total mass. The viscosity of the solution was in the range of10~20mPa·s. The best option got throw orthogonal experiment was as follow: Al/P equals to1/4.5，M/P equals to3/4, the viscosity of the solution was14mPa·s, carbonate accoutsfor26.8%of the total mass. Mechanical property test showed that the compressivestrength of the foamed panel was21kPa, weight loss was21.7%, both of which isrelatively low, so toughening is necessary.Melamine Formaldehyde (MF) resin was chosen as the toughened resin due to itsexcellent fire retardancy. MF resin was prepared firstly. The impact of pH, reactingtemperature and the ratio of Formaldehyde to Melamine on the propertiy of resin wasstudied. SEM showed that the composite panel has uniform discrete cells. Thenon-combusitibility property test showed that the composite foamed panel wasnon-combusitibility material when the resin content was lower than40wt%. Mechanicalproperty test showed that the compressive strength of the composite foamed panel was60kPa, weight loss was8.7%, both of which were improved compared with theinorganic foamed panel, but still low compared with other common insulation material.Further work is necessary to improve the mechanical properties.PVA was chosen to modified MF resin. And composite foamed panel with themodified resin was prepared. Mechanical test showed that compressive strength was170kPa, weight loss was lower than4%, both of which were largely improvedcompared with the former panel, and the compressive strength was about the same with rock wool panel, lager than that of EPS and PVC composite foamed panel. Thenon-combusitibility property test showed that the composite foamed panel wasnon-combusitibility material when the resin content was lower than40wt%. The thermalconductivity value was0.035~0.040W/m·K. All the other properties were up to thestandard of thermal insulation materials. With all these advantages, especially thenon-combusitibility, the composite foamed material claimed in this paper is a kind ofvery promising building thermal insulation material.