Used as a leveling agent and film forming substance for producing high transparency and good weather resistance plastic film substrates, films, and various coatings. In addition to hydroxyl and acetyl groups, CAB molecules also contain butyryl groups, and their properties are related to the content of the three functional groups. The melting point and tensile strength increase with the increase of acetyl content, while the compatibility with plasticizers and the flexibility of the film increase within a certain range with the decrease of acetyl content. The increase in hydroxyl content promotes its solubility in polar solvents. An increase in the content of butyryl groups results in a decrease in density and an expansion of the dissolution range. Contains 12% to 15% acetyl groups and 26% to 29% butyryl groups. Transparent or opaque granular material, with tough texture, good weather and cold resistance. The melting temperature is 140 ℃. Density 1.15-1.22g/cm3. The tensile strength is 14-52MPa, the bending modulus is 621-2070MPa, the impact strength of the cantilever beam notch is 53-580J/m, and the Rockwell hardness is R31-116. The thermal deformation temperature is 45-94 ℃.