There are provided low-substituted hydroxypropyl cellulose (L-HPC) having good compressibility and capping-prevention performance, and others. Specifically, provided are L-HPC having a hydroxypropoxy content of 5 to 16% by weight, a volume fraction of long fibrous particles of 20 to 40% and a volume fraction of short fibrous particles of 26 to 60% with the proviso that the latter is greater than the former; and a solid preparation containing the L-HPC. Also provided is a method for producing the L-HPC including the steps of: bringing powdery pulp having a length-weighted mean width of 10 to 25 m into contact with an alkali metal hydroxide solution, reacting the alkali cellulose with propylene oxide, and neutralizing the alkali metal hydroxide present in the reaction product with an acid to precipitate crude low-substituted hydroxypropyl cellulose in the absence of a step of dissolving a portion or all of the reaction product.

There is provided is a hydroxyalkyl alkyl cellulose exhibiting good flowability and high compressibility. More specifically, provided are a hydroxyalkyl alkyl cellulose having a volume-based average particle diameter, determined by dry laser diffractometry, of 50 to 100 m, and having, on a basis of a dynamic image analysis to divide all particles into fine particles, spherical particles and fibrous particles, a volume fraction of the fibrous particles consisting of long and short fibrous particles relative to all of the particles of 45 to 70%, and a volume fraction of the fine particles relative to all of the particles of less than 2.0%; a solid preparation including the hydroxyalkyl alkyl cellulose; and others.

Provided are low-substituted hydroxypropyl cellulose (L-HPC) 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, spherical, and fibrous particles consisting of long and short fibrous particles, a volume fraction of the long fibrous particles of from 15 to 50% and a volume fraction of the short fibrous particles of from 23 to 60%; and a solid preparation containing the L-HPC. Also provided is a method for producing the L-HPC including the steps: bringing sheet-like or chip-like pulp having a length-weighted average fiber length of from 2.40 to 3.50 mm into contact with an alkali metal hydroxide solution, reacting the resulting alkali cellulose with propylene oxide, and dispersing the resulting reaction product in water containing an acid to partially dissolve it therein, followed by neutralization with an acid to precipitate crude L-HPC.

Provided is a hydroxyalkyl alkyl cellulose exhibiting good flowability and high compressibility. More specifically, there are provided a hydroxyalkyl alkyl cellulose having a volume-based average particle size, determined by dry laser diffractometry, of more than 100 m and not more than 150 m; and after dividing all particles into fine particles, spherical particles and fibrous particles by a dynamic image analysis, a volume fraction of the fibrous particles relative to all of the particles of more than 40% and not more than 50%, and a volume fraction of the fine particles relative to all of the particles of less than 2.0%; a solid preparation including the hydroxyalkyl alkyl cellulose; and others.

Provided are low-substituted hydroxypropyl cellulose (L-HPC) 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, spherical, and fibrous particles consisting of long and short fibrous particles, a volume fraction of the long fibrous particles of from 15 to 50% and a volume fraction of the short fibrous particles of from 23 to 60%; and a solid preparation containing the L-HPC. Also provided is a method for producing the L-HPC including the steps: bringing sheet-like or chip-like pulp having a length-weighted average fiber length of from 2.40 to 3.50 mm into contact with an alkali metal hydroxide solution, reacting the resulting alkali cellulose with propylene oxide, and dispersing the resulting reaction product in water containing an acid to partially dissolve it therein, followed by neutralization with an acid to precipitate crude L-HPC.

There are provided low-substituted hydroxypropyl cellulose (L-HPC) having good compressibility and capping-prevention performance, and others. Specifically, provided are L-HPC having a hydroxypropoxy content of 5 to 16% by weight, a volume fraction of long fibrous particles of 20 to 40% and a volume fraction of short fibrous particles of 26 to 60% with the proviso that the latter is greater than the former; and a solid preparation containing the L-HPC. Also provided is a method for producing the L-HPC including the steps of: bringing powdery pulp having a length-weighted mean width of 10 to 25 ?m into contact with an alkali metal hydroxide solution, reacting the alkali cellulose with propylene oxide, and neutralizing the alkali metal hydroxide present in the reaction product with an acid to precipitate crude low-substituted hydroxypropyl cellulose in the absence of a step of dissolving a portion or all of the reaction product.

There is provided is a hydroxyalkyl alkyl cellulose exhibiting good flowability and high compressibility. More specifically, provided are a hydroxyalkyl alkyl cellulose having a volume-based average particle diameter, determined by dry laser diffractometry, of 50 to 100 m, and having, on a basis of a dynamic image analysis to divide all particles into fine particles, spherical particles and fibrous particles, a volume fraction of the fibrous particles consisting of long and short fibrous particles relative to all of the particles of 45 to 70%, and a volume fraction of the fine particles relative to all of the particles of less than 2.0%; a solid preparation including the hydroxyalkyl alkyl cellulose; and others.

Provided is a hydroxyalkyl alkyl cellulose exhibiting good flowability and high compressibility. More specifically, there are provided a hydroxyalkyl alkyl cellulose having a volume-based average particle size, determined by dry laser diffractometry, of more than 100 m and not more than 150 m; and after dividing all particles into fine particles, spherical particles and fibrous particles by a dynamic image analysis, a volume fraction of the fibrous particles relative to all of the particles of more than 40% and not more than 50%, and a volume fraction of the fine particles relative to all of the particles of less than 2.0%; a solid preparation including the hydroxyalkyl alkyl cellulose; and others.