Provided is an optical film containing a cellulose derivative, the optical film having an in-plane retardation Ro.sub.550 within the range of 120 to 160 nm measured at a wavelength of 550 nm under an atmosphere of a temperature of 23° C. and a relative humidity of 55%, and a ratio Ro.sub.450/Ro.sub.550 within the range of 0.65 to 0.99, Ro.sub.450/Ro.sub.550 being a ratio of an in-plane retardation Ro.sub.450 measured at a wavelength of 450 nm to the in-plane retardation Ro.sub.550 measured at a wavelength of 550 nm, wherein, a substituent of a glucose skeleton in the cellulose derivative satisfies the requirements (a) and (b) which are described in the specification, and the optical film contains a compound A satisfying the following condition defined by Expression (a1) which is described in the specification.

Provided is an optical film containing a cellulose derivative, the optical film having an in-plane retardation Ro.sub.550 within the range of 120 to 160 nm measured at a wavelength of 550 nm under an atmosphere of a temperature of 23° C. and a relative humidity of 55%, and a ratio Ro.sub.450/Ro.sub.550 within the range of 0.65 to 0.99, Ro.sub.450/Ro.sub.550 being a ratio of an in-plane retardation Ro.sub.450 measured at a wavelength of 450 nm to the in-plane retardation Ro.sub.550 measured at a wavelength of 550 nm, wherein, a substituent of a glucose skeleton in the cellulose derivative satisfies the requirements (a) and (b) which are described in the specification, and the optical film contains a compound A satisfying the following condition defined by Expression (a1) which is described in the specification.

Provided are a composite for cellulose fiber dispersion that can inexpensively and sufficiently disperse cellulose fibers, particularly nanocellulose, in a hydrophobic resin and a cellulose fiber composition containing the composite. A composite for cellulose fiber dispersion according to the present invention has a structure in which a vinyl polymer is grafted to a cellulose derivative. A cellulose fiber composition according to the present invention contains the composite and cellulose fibers and more specifically also contains an organic solvent, a resin precursor, or a resin.

Provided are a composite for cellulose fiber dispersion that can inexpensively and sufficiently disperse cellulose fibers, particularly nanocellulose, in a hydrophobic resin and a cellulose fiber composition containing the composite. A composite for cellulose fiber dispersion according to the present invention has a structure in which a vinyl polymer is grafted to a cellulose derivative. A cellulose fiber composition according to the present invention contains the composite and cellulose fibers and more specifically also contains an organic solvent, a resin precursor, or a resin.

Nanoparticles including a cellulosic polymer and a hydrophobic material and methods for forming them.

The present invention describes a method for producing nanoparticles, wherein the nanoparticles contain or consist of hydroxypropyl methylcellulose acetate succinate (HPMCAS), and wherein i) HPMCAS is dissolved in an organic solvent in order to obtain an organic solution and ii) the organic solution is mixed with water to precipitate the nanoparticles in order to obtain precipitated nanoparticles and a mixed liquid phase as well as nanoparticles obtained by that method.

The present invention describes a method for producing nanoparticles, wherein the nanoparticles contain or consist of hydroxypropyl methylcellulose acetate succinate (HPMCAS), and wherein i) HPMCAS is dissolved in an organic solvent in order to obtain an organic solution and ii) the organic solution is mixed with water to precipitate the nanoparticles in order to obtain precipitated nanoparticles and a mixed liquid phase as well as nanoparticles obtained by that method.

A biodegradable material and a method for preparing a biodegradable material are provided. The biodegradable material includes a continuous phase and a dispersed phase. The continuous phase includes a polyester, and the dispersed phase includes a modified saccharide oligomer. In particular, the weight ratio of the modified saccharide oligomer to the polyester is from 3:97 to 30:70. The dispersed phase has a maximum diameter of 100 nm to 900 nm.

A biodegradable material and a method for preparing a biodegradable material are provided. The biodegradable material includes a continuous phase and a dispersed phase. The continuous phase includes a polyester, and the dispersed phase includes a modified saccharide oligomer. In particular, the weight ratio of the modified saccharide oligomer to the polyester is from 3:97 to 30:70. The dispersed phase has a maximum diameter of 100 nm to 900 nm.

There is provided a method for producing hypromellose acetate succinate (HPMCAS), the method not requiring any special device and facilitating removal of impurities. More specifically, there is provided a method for producing HPMCAS, including an esterification step of esterifying hypromellose with an acetylating agent and a succinoylating agent in the presence of an aliphatic carboxylic acid to obtain a reaction product solution containing HPMCAS; a precipitation step of precipitating the HPMCAS by mixing the reaction product solution with water to obtain a suspension of the precipitated HPMCAS; a neutralization step of neutralizing the suspension with a basic substance to obtain a neutralized suspension; and a washing step of washing the HPMCAS contained in the neutralized suspension to obtain the washed HPMCAS.