US 1714039 A
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Patented Ma 21, 1929.
UNITED. STATES PATENT OFFICE.
'romosuxn MUTO AND sABuno HIDA, OF'KOBE,IJ IAIPAN, assrenons 'ro KANEGA- room nosnxr KABUSHIKI KWAISHA, or TOKYO-EU, JAPAN.
PROCESS OF LIQUIDATION OF NATURAL SILK THREADS.
1T0 Drawing. Application filed February 21, 1928, Serial No. 256,059, and in Japan December 15, 1927.
This invention relates to improvements in the process of dissolving natural silk threads and is characterized by the fact that the natural silk is colloidally dissolved in a solution by treating the silk with a solution of magnesium nitrate or other soluble magnesium salts, and then removing the magnesium salts from the solution.
The main object of this invention is to prepare a colloidal adhesive liquid of natural silk from natural raw silk threads, silk yarn, silk waste, old silk cloth or other. similar raw silk materials by a simple andeconomical process, to regenerate silk threads from the liquid or to be utilized in manufacture of plastic materials or painting materials etc.
Heretofore there has been little success in attempts to re-gain silk threads, artificially from liquefied silk, which have high strength and tenacity because threads heretofore formed from solutions of liquefied silk have been brittle.
According to the present invention, these defects are overcome and we are able toobtain threads from a silk solution which possess good strength and tenacity characteris- .By way of example of carrying out our invention in practice we proceed as follows. About ten parts of magnesium nitrate are dissolved in five parts of water and this solution is heated to a temperature of about 110 (3., then two or three parts of waste silk threads divided in several small quantities are successively added, dipped into the said magnesium nitrate solution and stirred gently a-nd dissolved to form a suspending colloidal solution. After that the magnesium salt added is separated and expelled from this suspending solution by dialysis or other ordinary separating method. Dialysis is the preferred method and is accomplished by simply placing the solution in an unglazed earthenware pot surrounded by pure water. Under such conditions, the magnesium nitrate passes through the pot into the water whereas the colloidal silk remains behind. The method of separation by dialysis is a well known colloidal chemical process and needs no further description. The suspension of natural silk thus formed is new concentrated at a comparatively low'temperathen drawn into coagulating solution bath such as acetic acid, methyl-alcohol or other known dehydrating agents. In other cases we may prepare thin paperlike sheets of natural silk by spreading the said concentrated liquid silk over a flatsurface such as glass plate and drying the film. A suitable quantity of gelatin, glucose etc. may be added either before or after the expelling of salts to modify the strength and elasticity of the finished thread.
As is shown in the aforesaid explanation one of the characteristics of this invention resides in the use of magnesium nitrate or other soluble magnesium salts as liquefying agents for the natural silk threads. Owing to this reason it is easy to remove the magnesium salts from the colloidal solution of the natural .silk and recover a good product having devention as claimed, and, accordingly we beg to intend not to be limited as to the details described.
We claim The method of preparing a'colloidal solution of natural silk which comprises dissolving the silk in a solution of magnesium nitrate and then subjecting the solution to dialysis to free it of the magnesium nitrate.
In.testimony whereof we have affixed our signatures.
'IOMENGSUKE MUTO. SABURO HIDA.