The Process of Microcrystalline Cellulose
Microcrystalline cellulose (MCC) is the crystalline fiber with a degree of polymerization of about 220 and a relative molecular weight of 36,000, obtained by strong acid hydrolysis of the fiber with a high degree of crystallinity to remove the amorphous part of it.
Its dispersibility in water, crystallinity and purity are different from the mechanical cellulose. Currently, the commercial microcrystalline cellulose at home and abroad is prepared as follows: put the α-cellulose boiled for 15min with 2.5mol • L-1 HCl at 105℃, remove the amorphous part, filter, wash the crystals with water and aqueous ammonia, then disperse by vigorous mixing and form the powdery microcrystalline cellulose by spray drying.
On the foreign market there is the microcrystalline cellulose of RC type, known as colloidal cellulose or dispersible cellulose B.P.. With the hydrolyzed α-cellulose as the raw material, destroy the naturally occurring aggregate with the mechanical grinding method to make it become fine crystalline. In order to prevent the re-agglomeration during drying, it is often grinded together with the hydrophilic dispersing agents (such as the sodium carboxymethyl cellulose containing 8.5 % -11% ), and then it is made by drying.