U.S. patent application 20180362243 (applicant Solee Science & Technology Co. Ltd., Wuhan, China):
"An insulating container comprises a container body and a container cover connected to the container body. The container both and the container cover each comprises a frame and a plate arranged on the frame. The plate comprises, from inside out, an external high strength sheet, an extruded polystyrene sheet, phase-change insulating sheets made of phase-change material, and an internal sheet. A phase-change process of the phase-change insulating sheets cooperates with a refrigeration system of the transportation device to precisely control the temperature of the insulating container and a refrigerator truck to be near a phase-change temperature. In the present disclosure, the phase-change insulating sheets made of the phase-change material remain to be in a solid state before or after occurrence of a phase change, so that the structure of the insulating container does not change with the phase change and a leakage problem of the phase-change material does not exist."