Method for preparing powder cosmetic with gradient color effect and powder cosmetic

A method for preparing a powder cosmetic with a gradient color effect, comprising the following steps:

• mixing:
• providing raw materials for preparing the powder cosmetic, and mixing them to obtain a mixed material system;
• color laydown:
• providing a mold, the mold having at least one cavity with an upward opening;
• taking at least one water-soluble pigment, diluting them separately to obtain at least one pigment solution, and dot-coating the at least one pigment solution onto at least one preset position on a bottom of the cavity;
• filling:
• after color laydown, filling a predetermined amount of the mixed material system into the mold, wherein the water-soluble pigment directionally diffuses within the mixed material system under the action of a concentration gradient;
• auxiliary diffusion:
• baking or microwave heating the mixed material system within the mold, wherein a baking temperature is from 30 to 70° C., and a baking time is from 5 minutes to 1 hour;
• during the baking, the baking temperature increases in a gradient from the edge region to the central region of the mixed material system;
• wherein the microwave heating has a power of from 0.2 to 1 GHz;
• a microwave heating time is from 20 seconds to 5 minutes;
• freezing:
• freezing the material system within the mold at a low temperature to obtain a powder masterbatch;
• demolding:
• separating the powder masterbatch from the mold;
• drying:
• drying the demolded powder masterbatch to obtain a powder cosmetic with a gradient color effect;
• wherein a concentration of the pigment solution is from 0.1% to 10% by mass;
• and a viscosity of the mixed material system at 25° C. is from 1000 to 15000 cP.