Low-substituted hydroxypropyl cellulose, production method thereof, and solid preparation

Low-substituted hydroxypropyl cellulose having a hydroxypropoxy content of from 5 to 16% by weight, and having, on a basis of a dynamic image analysis to divide all particles into fine particles, spherical particles, and fibrous particles consisting of long and short fibrous particles, a volume fraction of the long fibrous particles relative to all of the particles of from 15 to 50% and a volume fraction of the short fibrous particles relative to all of the particles of from 23 to 60%,

• wherein
• the fine particles have a length of fiber of less than 40 μm,
• the spherical particles have a length of fiber of 40 μm or more and consist of first and second spherical particles, wherein the first spherical particles have an elongation, which is a ratio of a diameter of fiber to a length of fiber, of 0.5 or more, and the second spherical particles have an elongation of less than 0.5, an aspect ratio, which is a ratio of a maximal Feret diameter to a minimal Feret diameter, of 0.5 or more, and a circularity, which is a ratio of a perimeter (PEQPC) of a circle that has the same area as a projection area to a perimeter (Preal) of a real particle, of 0.7 or more,
• the long fibrous particles have a length of fiber of 200 μm or more and an elongation of less than 0.5, and consist of first and second long fibrous particles, wherein the first long fibrous particles have an aspect ratio of less than 0.5, and the second long fibrous particles have an aspect ratio of 0.5 or more and a circularity of less than 0.7, and
• the short fibrous particles have a length of fiber of 40 μm or more and less than 200 μm and an elongation of less than 0.5, and consist of first and second short fibrous particles, wherein the first short fibrous particles have an aspect ratio of less than 0.5, and the second short fibrous particles have an aspect ratio of 0.5 or more and a circularity of less than 0.7.