Study On The Curing Modification At Low Temperature And Application Of Phosphate Adhesive

Phosphate adhesive has the advantages of high bond strength,low curing shrinkage,low price,environmental protection and non-toxic,but its high curing temperature limits its popularization and application.In this paper,phosphate adhesive was modified by different curing agents to reduce its curing temperature,and the expanded perlite thermal insulation board was prepared by combining phosphate adhesive with the abundant local resources of Xinyang perlite in Henan province,and phosphate adhesive was discussed indirectly.Phosphoric acid,aluminum hydroxide and expanded perlite were used as main raw materials to prepare expanded perlite thermal insulation board in this paper.Factors affecting the properties of phosphate adhesive and thermal insulation boards were discussed and analyzed.The main research contents include the following aspects:(1)Mixed oxides were used as curing agents,the effects of preparation temperature and preparation time of phosphate adhesive base,drying temperature and drying time of insulation boards and curing agents on the properties of insulation boards were explored.(2)Preparation of dolomite-phosphate/expanded perlite insulation board.In order to determine the best preparation process,single factor experiment method was used to explore the P/Al ratio,calcination temperature of dolomite,dolomite dosage,drying temperature and drying time of insulation boards.Basing on the single factor experiment results,the orthogonal experiment was carried out among the drying temperature and drying time of the insulation boards,dolomite dosage.Based on the orthogonal experiment results,dolomite-phosphate adhesive was modified by using sodium fluoride and silane coupling agent to optimize the performance of expanded perlite thermal insulation boards.(3)The phosphate adhesive was prepared through adding metakaolin as curing agent.The effects of the calcination temperature and calcination time of kaolin,metakaolin dosage,drying temperature and drying time of samples on the performance of insulation boards were studied by using single factor experiment method.Experimental results indicating that,when the adhesive base material was prepared at85 ~oC for 30 min,the insulation boards were dried at 140 ~oC for 2 h,the obtained oxide-phosphate/expanded perlite insulation boards had the best properties.The apparent density,thermal conductivity and compressive strength of the thermal insulation board were 255.06Kg/m~3?0.050 W/(m·K)and 0.626 MPa,respectively.When the P/Al ration was 4 and the dolomite was calcinated 900 ~oC,the dosage of dolomite was 7%,the insulation boards were dried at 170 ~oC for 2.5 h,the dosage of Na F was 8%,and the dosage of silane coupling agent was 6.8%,the obtained dolomite-phosphate/expanded perlite insulation boards had the best properties.The apparent density,thermal conductivity and compressive strength of the obtained insulation board were 279.59 Kg/m~3,0.050 W/(m·K)and 1.114 MPa,respectively.When the kaolin was calcinated at 800 ~oC for 5 h,the dosage of metakaolin was 11%,the insulation boards were dired at 130 ~oC for 2 h,the obtained metakaolin-phosphate/expanded perlite insulation boards had the best properties.The apparent density,thermal conductivity and compressive strength of the obtained insulation board were272.81 Kg/m~3,0.048 W/(m·K)and 0.804 MPa,respectively.The obtained expanded perlite thermal insulation boards in the paper possess several advantages,such as light weight,simple technology,good insulation effect,environmental protection without pollution,low cost.Therefore,the obtained thermal insulation boards have a broad application potential in the future.