Spider silk protein film, and method for producing same
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.
1. A method for producing a spider silk protein film containing a polypeptide derived from spider silk proteins, comprising:
dissolving a polypeptide derived from spider silk proteins in a dimethyl sulfoxide solvent to prepare a dope solution such that the dope solution consists essentially of the polypeptide derived from spider silk proteins and dimethyl sulfoxide (DMSO); and
cast-molding the dope solution on a surface of a base to form the spider silk protein film.
2. The method for producing a spider silk protein film according to claim 1 , wherein the dope solution has a viscosity of 15 to 80 centipoise (cP).
3. The method for producing a spider silk protein film according to claim 1 , wherein the base to be used at the time of the cast molding is a polyethylene terephthalate (PET) film or a release film composed of a PET film and a silicone compound that is fixed on a surface of the PET film.
4. The method for producing a spider silk protein film according to claim 1 , wherein the film is subjected to drying and/or desolvation by at least one selected from vacuum drying, hot-air drying, air drying, and immersion.
5. The method for producing a spider silk protein film according to claim 4 , wherein the film after the drying and/or desolvation is stretched uniaxially or biaxially in water, or the film is subjected to desolvation simultaneously with stretching.
6. The method for producing a spider silk protein film according to claim 5 , wherein the film after the stretching is subjected to thermal fixation by dry heat at 50 to 200° C.
7. The method for producing a spider silk protein film according to claim 1 , further comprising:
dissolving or dispersing a colorant in DMSO to prepare a DMSO coloring liquid; and
adding the DMSO coloring liquid to the dope solution or adding the dope solution to the DMSO coloring liquid and mixing them to prepare the dope solution for film casting.