Abstract: A film of the present invention contains a polypeptide derived from spider silk proteins. The decomposition temperature of the film is 240 to 260° C. The film absorbs ultraviolet light having a wavelength of 200 to 300 nm and has a light transmittance of 85% or more at a wavelength of 400 to 780 nm. The film is transparent and colorless in a visible light region. A method for producing a film of the present invention includes: dissolving a polypeptide derived from spider silk proteins in a dimethyl sulfoxide solvent to prepare a dope; and cast-molding the dope on a surface of a base. Thus, the present invention provides a spider silk protein film that can be formed easily and has favorable stretchability, and a method for producing the same.

Abstract: A film of the present invention contains a polypeptide derived from spider silk proteins. The decomposition temperature of the film is 240 to 260° C. The film absorbs ultraviolet light having a wavelength of 200 to 300 nm and has a light transmittance of 85% or more at a wavelength of 400 to 780 nm. The film is transparent and colorless in a visible light region. A method for producing a film of the present invention includes: dissolving a polypeptide derived from spider silk proteins in a dimethyl sulfoxide solvent to prepare a dope; and cast-molding the dope on a surface of a base. Thus, the present invention provides a spider silk protein film that can be formed easily and has favorable stretchability, and a method for producing the same.

Abstract: A film of the present invention contains a polypeptide derived from spider silk proteins. The decomposition temperature of the film is 240 to 260° C. The film absorbs ultraviolet light having a wavelength of 200 to 300 nm and has a light transmittance of 85% or more at a wavelength of 400 to 780 nm. The film is transparent and colorless in a visible light region. A method for producing a film of the present invention includes: dissolving a polypeptide derived from spider silk proteins in a dimethyl sulfoxide solvent to prepare a dope; and cast-molding the dope on a surface of a base. Thus, the present invention provides a spider silk protein film that can be formed easily and has favorable stretchability, and a method for producing the same.

Abstract: A solution-dyed protein fiber of the present invention includes 0-100 mass % of silk fibroin and 100-0 mass % of a polypeptide derived from spider silk proteins when the protein fiber is assumed to be 100 mass %, wherein the solution-dyed protein fiber contains a solution-dyeing colorant. The fiber is obtained by: dissolving or dispersing a solution-dyeing colorant in a solvent used for a spinning solution or in dimethyl sulfoxide, thereby preparing a coloring liquid; adding a solvent to the coloring liquid in an amount necessary for a spinning solution; adding and dissolving protein powder into the solvent, thereby preparing a spinning solution; and subjecting the spinning solution to wet spinning or dry-wet spinning. Thereby, the present invention provides a low-cost solution-dyed protein fiber in which a solution-dyeing colorant is dispersed uniformly and that can exhibit bright color tone, and a method for producing the same.

Abstract: An artificial polypeptide fiber of the present invention is an artificial fiber containing a polypeptide as a main component, and has a stress of 350 MPa or more and a toughness of 138 MJ/m3 or more. A method for producing an artificial polypeptide fiber of the present invention is a method for producing the artificial polypeptide fiber obtained by spinning a spinning solution (6) containing a polypeptide derived from natural spider silk proteins and performing drawing of at least two stages. The drawing of at least two stages includes a first-stage drawing (3) in wet heat and a second-stage drawing (4) in dry heat. Thereby, the present invention provides high-toughness artificial polypeptide fibers having favorable stress and rupture elongation, and a method for producing the same.

Abstract: A film of the present invention contains a polypeptide derived from spider silk proteins. The decomposition temperature of the film is 240 to 260° C. The film absorbs ultraviolet light having a wavelength of 200 to 300 nm and has a light transmittance of 85% or more at a wavelength of 400 to 780 nm. The film is transparent and colorless in a visible light region. A method for producing a film of the present invention includes: dissolving a polypeptide derived from spider silk proteins in a dimethyl sulfoxide solvent to prepare a dope; and cast-molding the dope on a surface of a base. Thus, the present invention provides a spider silk protein film that can be formed easily and has favorable stretchability, and a method for producing the same.

Abstract: A polypeptide solution of the present invention is a polypeptide solution in which a polypeptide derived from natural spider silk proteins is dissolved in a solvent. The solvent contains at least one selected from the following (i)-(iii): (i) DMSO; (ii) DMSO with an inorganic salt; and (iii) DMF with an inorganic salt. Further, in the present invention, an artificial polypeptide fiber is obtained by: using the polypeptide solution as a dope solution; and extruding the dope solution from a spinneret into a desolvation bath so as to eliminate the solvent from the dope solution and form a fiber to produce an undrawn yarn. Moreover, in the present invention, a polypeptide is purified by subjecting the polypeptide solution to heat treatment and thereafter removing an undissolved substance therefrom.

Abstract: A solution-dyed protein fiber of the present invention includes 0-100 mass % of silk fibroin and 100-0 mass % of a polypeptide derived from spider silk proteins when the protein fiber is assumed to be 100 mass %, wherein the solution-dyed protein fiber contains a solution-dyeing colorant. The fiber is obtained by: dissolving or dispersing a solution-dyeing colorant in a solvent used for a spinning solution or in dimethyl sulfoxide, thereby preparing a coloring liquid; adding a solvent to the coloring liquid in an amount necessary for a spinning solution; adding and dissolving protein powder into the solvent, thereby preparing a spinning solution; and subjecting the spinning solution to wet spinning or dry-wet spinning. Thereby, the present invention provides a low-cost solution-dyed protein fiber in which a solution-dyeing colorant is dispersed uniformly and that can exhibit bright color tone, and a method for producing the same.

Abstract: A polypeptide solution of the present invention is a polypeptide solution in which a polypeptide derived from natural spider silk proteins is dissolved in a solvent. The solvent contains at least one selected from the following (i)-(iii): (i) DMSO; (ii) DMSO with an inorganic salt; and (iii) DMF with an inorganic salt. Further, in the present invention, an artificial polypeptide fiber is obtained by: using the polypeptide solution as a dope solution; and extruding the dope solution from a spinneret into a desolvation bath so as to eliminate the solvent from the dope solution and form a fiber to produce an undrawn yarn. Moreover, in the present invention, a polypeptide is purified by subjecting the polypeptide solution to heat treatment and thereafter removing an undissolved substance therefrom.

Abstract: A polypeptide solution of the present invention is a polypeptide solution in which a polypeptide derived from natural spider silk proteins is dissolved in a solvent. The solvent contains at least one selected from the following (i)-(iii): (i) DMSO; (ii) DMSO with an inorganic salt; and (iii) DMF with an inorganic salt. Further, in the present invention, an artificial polypeptide fiber is obtained by: using the polypeptide solution as a dope solution; and extruding the dope solution from a spinneret into a desolvation bath so as to eliminate the solvent from the dope solution and form a fiber to produce an undrawn yarn. Moreover, in the present invention, a polypeptide is purified by subjecting the polypeptide solution to heat treatment and thereafter removing an undissolved substance therefrom.

Abstract: A polypeptide solution of the present invention is a polypeptide solution in which a polypeptide derived from natural spider silk proteins is dissolved in a solvent. The solvent contains at least one selected from the following (i)-(iii): (i) DMSO; (ii) DMSO with an inorganic salt; and (iii) DMF with an inorganic salt. Further, in the present invention, an artificial polypeptide fiber is obtained by: using the polypeptide solution as a dope solution; and extruding the dope solution from a spinneret into a desolvation bath so as to eliminate the solvent from the dope solution and form a fiber to produce an undrawn yarn. Moreover, in the present invention, a polypeptide is purified by subjecting the polypeptide solution to heat treatment and thereafter removing an undissolved substance therefrom.

Abstract: An artificial polypeptide fiber of the present invention is an artificial fiber containing a polypeptide as a main component, and has a stress of 350 MPa or more and a toughness of 138 MJ/m3 or more. A method for producing an artificial polypeptide fiber of the present invention is a method for producing the artificial polypeptide fiber obtained by spinning a spinning solution (6) containing a polypeptide derived from natural spider silk proteins and performing drawing of at least two stages. The drawing of at least two stages includes a first-stage drawing (3) in wet heat and a second-stage drawing (4) in dry heat. Thereby, the present invention provides high-toughness artificial polypeptide fibers having favorable stress and rupture elongation, and a method for producing the same.