Study On The Preparation And Properties Of HFC-365mfc And HFC-245fa And Cyclopentane Three Type Blowing Agent Mix-foaming Rigid Polyurethane Foam Used In The Refrigerator

HFC-365mfc/HFC-245fa/CP ternary mixed foaming polyurethane rigid foam was prepared by one-step method in this paper. The performance indexes of polyurethane were studied by modifying the influencing factors:the ratio of ternary mixed foaming agent, the ratio of ternary mixed foaming agent to water, the type and index of isocyanate, the dosage of different foam stabilizer, different catalysts, various structures polyether glycols and different molecular weight polyether glycols with identical structure. These performance indexes was discussed with the help of SEM, compressive strength test, thermo-cycling size stability test, heat-conducting property test and flowing property test. The optimal foaming formula was obtained in consideration of economy. This best foaming formula was as follows:water content 2.1%(by the weight of polyhydric alcohol conjugate polyether), ternary mixed foaming agent content 16pbw, foam stabilizer AK8832 content 2 pbw, isocyanate (44V-20L) index R 1.15. The prepared polyurethane had a good combination property in fluidity, heat-conducting, compressive strength and thermo-cycling size stability with the increase of the dosage of foaming catalyst PC-5 and Gel-type catalyst A33 and polyether functionality, the decrease of the dosage of trimerization-type catalyst C41, the use of polyether glycol initiated by aromatic and aliphatic polyamine.The research results revealed that the prepared polyurethane had little change in heat-conducting coefficient, and the compressive strength of foam decreased greatly, and the thermo-cycling size stability decreased slightly when apparent core power density of molded polyurethane foam decreased gradually in the same polyhydric alcohol conjugate polyether formula. It was found that, compared with polyurethane, with apparent core power density of 32.0 Kg/m, produced by pure cyclopentane and HFC-245fa blowing agent, polyurethane, with core power density of 34.0 Kg/m3, prepared by the ternary mixed foaming agent had a better performance in heat-conducting coefficient, compressive strength and thermo-cycling size stability and so on. It was also indicated that this polyurethane produced by the ternary mixed foaming agent had a less heat-conducting coefficient, similar or better compressive strength and thermo-cycling size stability compared with polyurethane, whose core power density was 31.0 Kg/m3, prepared by pure HFC-245fa.