Solvent-free low-temperature ball-milling preparation method of solid polycarboxylic slump retaining agent

The invention relates to a solvent-free low-temperature ball-milling preparation method of a solid polycarboxylic slump retaining agent, which comprises the following steps: adding molten ethylene glycol vinyl polyoxyethylene ether, unsaturated carboxylic acid, acrylate, unsaturated amide and a chain transfer agent into a ball mill, closing a cover, opening an initiator feed valve, and adding halfof an initiator; opening a jacket chilled water valve of the ball mill while starting the ball mill for ball milling, and controlling the temperature to be 60+/-2 DEG C; adding the rest half of the initiator when ball milling is carried out for half of time, controlling the ball milling time to be 5-15 min, and after ball milling is finished, conveying a finished product to a cryogenic crusher through a discharging valve to crush and discharge the finished product. A solvent-free low-temperature ball milling method is adopted for bulk synthesis, the solid polycarboxylic acid slump retaining agent with the solid conte