Method for producing single nucleus detergent particles

A process for preparing uni-core detergent particles having a degree of particle growth of 1.5 or less and a bulk density of 500 g/L or more, comprising the steps of:

• (C-I):
• mixing base particles for supporting a surfactant which have an average particle size of from 150 to 500 μm and a bulk density of 400 g/L or more (Component (a)), a powdery builder (Component (b′)) of which primary average particle size is from 5 to 50 μm in an amount of from 5 to 50 parts by weight, based on 100 parts by weight of Component (a), and a surfactant composition (Component (c));
• (C-II):
• mixing a mixture obtained in Step (C-I) with a powdery builder (Component (b)) of which primary average particle size is from 3 to 30 μm in an amount of from 5 to 50 parts by weight, based on 100 parts by weight of Component (a);
• and
• (C-III):
• mixing a mixture obtained in Step (C-II) with a fine powder (Component (d)) of which primary average particle size is smaller than that of Component (b) in an amount of from 5 to 100 parts by weight, based on 100 parts by weight of said mixture,
• wherein a formulation ratio of Component (a) and Component (c) in Step (C-I) is such that an amount of Component (c) is from 20 to 100 parts by weight, based on 100 parts by weight of Component (a).