Method for Producing Molded Bodies from Proteins

Abstract

The invention relates to a method for producing molded bodies from proteins by ionic liquids, in particular in 1,3-dialkyl-imidazolium-acetates or 1,3-dialkyl-imidazolium-chloride as solvents in which the protein is dissolved, the solution is formed into fibers and foils, or membranes, respectively, the protein is regenerated by precipitation in protide solutions, the solvent is separated by washing and the molded bodies are tried. Furthermore the invention relates to molded bodies produced by said method.

Description

[0001]Method for producing molded bodies as well as molded bodies produced by said method from proteins in ionic liquids, in particular in 1,3-dialkyl-imidazolium-salts as well as the product oriented processing of such solutions by forming processes such as spinning, molding and blow processes for producing molded bodies such as fibers, filaments, fleeces, flat and tubular foils, respectively, membranes and films.[0002]The inventional method for producing molded bodies from proteins is characterized in that the protein is dissolved in the ionic liquid, the solution is formed to molded bodies, the protein being regenerated by precipitation in protide solutions, the solvent being separated by washing and the molded bodies are tried.[0003]Proteins within the scope of the present invention are native, highly molecular fibrous or globular proteins which, due to the formation of strong intra-molecular and inter-molecular hydrogen bridge linkages in their structure, have a poor solubility...

AI Technical Summary

Benefits of technology

[0015]It is an object of the present invention is to provide under substantially maintaining the molecular parameters a method for forming in a simple manner proteins into moulded bodies such as filaments, spinning fibers and foils / membranes at a high reliability of the proceeding and environment friendliness.

[0020]d) applies the solution to a smooth plate by a doctor blade and evenly distributing it thereupon and by treatment with a tempered solution which is mixable with the ionic liquid, however, is a precipitant to the protein, regenerates the protein and doffs the molded body as a foil / membrane, subjects it to a one, respectively, multi-step washing for removing the precipitant and dries it.

[0022]According to the inventional method fibrous protein such as silk fibroin will be disintegrated up to single fibers under strong shearing in water. After squeezing out, swollen fibroin is obtained with about 80-90 mass % water. Globular protein, such as maize zein and wheat gluten, ground up to powder will be dispersed in water and filtered off as swollen material. Surprisingly, the moist protein material in aqueous 1,3-dialkyl-imidazolium salts can easily be transferred into a homogeneous suspension which under shearing, heat supply and vacuum turns into a homogeneous spinning solution after having distilled off the water. Thereby the temperature range lies preferably at 80-95° C. The inventional method does not require to work under an inert nitrogen atmosphere and it generally permits to select a considerably lower temperature for dissolving the protein than will be otherwise necessary to dissolve the dry silk fibroin in an ionic anhydrous liquid (refer to D. M. Phillips et al. J. Am. Chem. Soc. 2004, 126, 14350-14351).

[0026]To obtain a high stability of the mol mass of the protein over a long time at an increased temperature, an addition of anti-oxidants such as hydroquinone, p-phenylene-diamine, gallic-acid-ester, tannins and the like prove a success. As thermo-gravimetric analyses (TGA) and measurements by differential-scanning-calorimetry (DSC) show a good thermal stability of the inventional spinning solution is given up to 220° C. Hence, the solutions according to present invention exhibit a considerably better stability compared to protein solutions in N-methylmorpholin-N-oxide-hydrate (NMO-hydrate) which above 130° C. tend to an explosive decomposition (K. Heinemann, E. Taeger DE19841649). While in the manufacture of the protein solutions in NMO-hydrate a precise distillation has to be kept to until the mono-hydrate has been obtained, the simpler procedure when dissolving in ionic liquids yields considerably shorter processing times for producing the spinning solution. Moreover, compared to the NMO-hydrate solutions, there can be obtained at comparable viscosities which permit a processing by spinning procedures a higher mass percentage of protein dissolved in ionic liquids, in particular in 1,3-dialkyl-imidazolium-acetal, which leads to a more effective process and more stable molded bodies.

Problems solved by technology

However, answers concerning the characterization and processing of the fibroin solution by forming methods such as spinning, casting and blowing processes are not given.

A preparation of the proteins from such solutions leads to properties of the products having a low quality level.

The processing of salinous solutions generally leads to a poor quality of the threads and molded bodies produced therefrom due to the residual of the respective salt in the product.

In both methods the technological expenditure is considerably increased due to the required dialysis of the salt solution and the subsequent drying for removing the water.