Method for manufacturing dual cosmetic container

A method for manufacturing a dual cosmetic container, comprising:

• molding an inner preform (40 or 40a) formed with a patterned portion having one or more shapes selected from characters, pictures, figures, and helical grooves on an outer surface thereof using an upper mold (10) for the inner preform having a molding space (11) and formed with a pattern molding portion (12a) on an inner circumferential surface thereof and an lower mold (14) for the inner preform having a molding space (15) for a discharge portion;
• inserting the inner preform (40 or 40a) into a molding space (21) of an upper mold (20) for an outer preform, fixing a discharge portion (41) of the inner preform (40 or 40a) to a lower mold (23) for the outer preform, feeding a liquid raw material into the molding space (21) of the upper mold (20) for the outer preform, and molding the outer preform (50) in close contact with the outer surface of the inner preform (40 or 40a) formed with the patterned portion (42);
• and
• simultaneously heating the inner preform (40 or 40a) and the outer preform (50) molded in close contact with each other, inserting the two heated preforms into a molding space (31) of a blow mold (30), inserting a blow tube (32) into the discharge portion (41) of the inner preform (40 or 40a), and simultaneously expanding the inner preform (40 or 40a) and the outer preform (50) by blow molding to manufacture the desired dual cosmetic container in which an inner container (100 or 100a) and an outer container (200) are in close contact with each other,
• wherein a reinforcing portion (42a) with a greater depth is formed along an outer line of the patterned portion such that an overall shape of the patterned portion (42) is clearly visible upon blow molding.