US1858474A - Silk improved in weight, durability, and appearance and process for obtaining the same - Google Patents

Description

Patented May 17, 1932 FRIEDRICH W. WEBER, OF HACKENSAOK, NEW JERSEY, ASSIGNOR T MAY'WOOD CHEMICAL WORKS, 015 HAYWOOD, NEW JERSEY, A GORPOBATION OF NEW JERSEY SILK HEPROVED IN WEIGHT, DURABILI'IY, AND APPEARANCE AND PROCESS FQR OBTAINING THE SAME No Drawing.

This invention relates to silk improved in Weight, durability and appearance, the obj ect of the invention being to provide a process by which said improved product can be obtained with great regularity, greater convenience and at a lower price.

In the many efforts to substitute, on account of its high price and its harmful action, the tin-tetrachloride for the treatment of silk to increase its weight, a great number of chemicals have been suggested with more or less success. Among these chemicals tried to substitute the tin tetrachloride are especially the salts of the rare earth metals which, owing to their high atomic Weight were expected to give especially good results. The finished product obtained by treating silk with solutions of such rare earth metals were highly promising as a considerable increase in weight could relatively easily be obtained though otherwise the quality of the fiber was not up to the requirements. Not-' withstanding some efforts in this line proper progress has not'been accomplished and the failure of the rare earth metals was usually attributed to the readiness with which for instance the cerous compounds, contained in the applied rare earth metals, change to the ceri-compounds and that thereby changes in the silk fiber are caused which detract very much from the obtained result.

Though there are processes in which the tin tetrachloride is at least partly substituted by the salts of certain other metal salts, all these processes applying either salts of the rare earth metals exclusively or applying the same in the presence of other metals salts, for instance those of tin, have not been able to get a foothold in the U. S. silk industry notwithstanding the fact that the highly developed industry of the rare earth metals would have been able to furnish all necessary salts of these metals in the greatest quantities and purity.

Long years of experience in the application of the rare earth metal compounds have convinced me that in fact the salts of the rare earth metal compounds, especially if they contain cerium, exert a deleterious efiect on the silk fiber and therefore should never Application filed. February 2, 1927. Serial No. 165,504.

be applied directly to the silk fiber because the original strength and elasticity is much affected by them, even if the lustre of the silk should not suffer, and that in this manner an industrial product will never be obtained. This efiect of the salts of the rare earth metals, especially in the presence of cerium, is so pronounced that even their use in the presence of varying quantities of other metal salts will not remedy the situation; the reason for this appears to be that this does not avoid the direct contact of the silk fiber by the cerium compound.

I have now found out that owing to the otherwise undesirable effect of the ocrium compounds on the silk the same must always first be given a protective coat before the treatment of silk with rare earth metal compounds can take place. This protective coat is generated by first treating the silk fiber with the solution of a tin salt, for instance such as tin tetrachloride. The recognition of the necessity of thus first preparing the silk for its further treatment with the salts of the rare earth metals is important for the facts stated further below. Of the solutions of the salts of the rare earth metals I found that of the acetates the most suitable, especially. that carrying a content of 810% of oxides of the rare earth metals with the exception, or at least only a small content of thorium.

phosphate is entirely avoided because the same is enveloped by the tin phosphate as will be more clearly seen from the description below of one way of operating my invention.

To carry the same into effect, I can for instance proceed as follows: A skein of silk, degummed in any of the usual Ways and Moreover, the well '10 at a temperature of approximately 70 25 the rare earth metals.

weighing about 45 grams, is immersed for about one hour into a 50% tin tetrachloride solution which was diluted by a like volume of water. The silk is then taken out of the 5 bath, the adhering tin chloride solution is pressed out and the silk is then well washed with water. Thereupon the silk thus treated is immersed into a slightly agitated bath of a 610% disodium phosphate solution ke t This treatment is also continued for about one hour, the silk is then taken out and the solution squeezed out of it and then the silk is well washed with water. The treatment with tin tetrachloride is once'more repeated in exactly the same way as described above and followed by another treatment with disodium phosphate solution. Now I treat the silk with the solution of a salt of the rare earth metals. The well washed and almost dry silk fiber is now immersed for approximately one hour into a solution of the acetates of the rare earth metals, free of thorium, containing approximately -810% of oxides of The silk is then taken out of the bath, squeezed to remove the adhering solution, and well washed, whereupon the silk is .then immersed in an 840% solution of disodium phosphate, for one hour, is then taken out and squeezedto remove the adhering solution and is then well Washed with water. This operation of treating the silk with a solution of the acetates of the rare earth metals and then with a solution of sodium di-phosphate is repeated three times more. This having been done the silk thus treated is returned once more to the tin tetrachloride bath for one hour, freed of the adhering tin tetrachloride solution and washed with water and finally treated again in a disodium phosphate bath, freed of the adhering solution and well washed with water.

The silk treated by my new process can be soaped, dyed and finished in any of the well known ways.

The skein of silk, after having been treated as above, increased in weight from grams to 108 grams; it contains approximately even quantities of tin phosphate and of the phos 0 phates of the applied rare earth metals and shows an excellent lustre and perfect whiteness, undiminished elasticity and strength. It is noteworthy that its fiber, when tested under the microscope, showed an absolute eveness in the thickness of the fiber.

I may furthermore say that if desired, the weighting of the silk with the rare earth metal compounds can be operated more than four times as described above without any detriment to the desired and required properties of the fiber. I may also say that for the purposes of the invention also other solutions of the salts of the rear earth metals may be used, such as chlorides of the same, but owing to the liberation of mineral acids, dur- .ing the process I prefer the acetates of the rare earth metals which should be free of showing a dull appearance were always due to the presenceof more or less greater quantities of thorium whereas this trouble .is avoided by the presence of minor quantities of the same as then the effect of the compounds of the rare earth metals keeps down this influence of thorium.

In regard to the chemical side of the process I may furthermore say that the above mentioned fixing bath of disodium hosphate may be substituted by sodium si icate or by that of any other chemical forming an insoluble salt with any of the metal salts coming in consideration for my new process. I may say that in the repeated application of such fixing baths I may also use for instance alternately another fixing bath, for instance one of a solution of disodium phosphate and of sodium silicate.

In mentioning degummed silk in the above example, I may say that the process can also be operated with or applied to raw silk, and silk fabric as well as to silk in the skein. It is thus evident that various changes can be made in the operation of my new process without deviating from the spirit of or sacrificing the advantages of the invention as such changes fall within the scope of the ap pended claims in which such intermediate steps, as for instance removing the solution adhering to the silk by squeezing and washing then the silk with water before bringing it into the next treating bath, represent steps which are a natural accessory to each preceding step before one can accede to the next following one.

What I claim is:

1. The process of improving silk, comprising treating silk first with a solution of a tin salt, subjecting the silk thus treated to a solution of disodium phosphate, immersmg the thus treated silk into a solution of a saltof the rare earth metals free of thorium, subjecting then the silk to a solution of disodium phosphate, returning the silk to the solution of the tin salt, and finally subjecting it again to the solution of the disodium phosphate.

' 2. The process of improving silk, comprising treating silk first with a solution of tin tetrachloride, subjecting the silk thus treated to a solution of disodium phosphate, immersing the thus treated silk into a solution of the acetate of the rare earth metals free of thorium, subjectingthen the silk to a solution of disodium phosphate, returning the silk to the solution of tin tetrachloride, and finally subjecting it again to the solution of disodium phosphate.

3. The process of improving silk with the salts of the rare earth metals, comprising treating first the silk with a solution of tin tetrachloride, then with a solution of disodium phosphate, and then with a solutionfof an acetate of a rare earth metal free of tliorium.

m 4. As a new article of manufacture, silk loaded with approximately equal amounts of an insoluble salt of tin and of a compound of a rare earth metal other than thorium, in

' layers deposited alternately upon each other the first layer consisting of the tin salt.

5. The process of Weighting silk which comprises treating the silk fiber with a solu tion of a tin compound and treating the same with a soluble phosphate, then treating the fiber with a solution of a salt of a rare earth metal, and again treating the fiber with a soluble phosphate.

6. The process of weighting silk which comprises treating the silk fiber with a solution of a tin compound and treating the same with a soluble phosphate, then'treating the fiber with a solution of a salt of a cerium, and again treating the fiber with a soluble phosphate.

7 The process of weighting silk which comprises treating the silk fiber with a solution of a tin compound and treating the same with a soluble phosphate, then treating the fiber with a solution of cerium acetate, and

0 again treating the fiber with a soluble phosphate.

I In witness whereof I have hereunto set my hand this 31st day of January, 1927.

m FRIEDRICH W. BER.