US2196986A - Treatment of silk, and product - Google Patents

Description

Patented Apr. 16,1940 I UNITED STATES 2,196,986 TREATMENT OF SILK, AND PRODUCT Alessandro Gandini, Monza, Italy No Drawing. Application October 26, 1937,

Serial No. 171,097

11 Claims.

The invention relates to a method for the processing of silk fibers, and to a product produced thereby. More particularly, it iscQncerned with a method for the treatment of silk waste, and to l the silk fibrous mass obtained therefrom, and includes correlated improvements and discoveries whereby the qualities of silk fibers are enhanced.

The processing of silk heretofore, for the purpose'of separating the fibers, entailed a removal of the sericin or gum which cements or holds the fibers together. This sericin was removed, by placing the silk in an alkaline or acid bath and heating substantially to the boiling point whereoy the gum or sericin was removed from the fiber by solution. Such procedure employed baths containing to soap or sodium carbonate, or a bath containing 1 to 2% sulfuric acid or 2 to 3% hydrochloric acid, and the like; in all of which procedures it will be noted a marked change in 20 the silk fiber was occasioned due to the removal of the sericin.

It is an object of this invention to provide a method for processingsilk which renders it well adapted for and capable of conversion into a yarn 35 with retention of substantially the natural content of sericin.

Another object of the invention is to provide a method wherebythe processingof silkmaybereadily, economically and efliciently carried out commercially, with obtainment of silk fibers that are hygroscopic, rugged, elastic, and non-conducting of electricity.

' A further object of the invention is to provide a method for the treatment of silk waste in a manner such that the fibers are so conditioned that they may be carded and combed to produce a staple fiber which may be spun into a yarn with facility.

0 An additional object of the invention is a method for the treatment of silk waste whereby a staple fiber for conversion into a yarn is obtained in conjunction with a mattable by-product which is well adapted for felting, either alone or in admixture with other materials, as hair and wool.

A still further object of the invention is to modify the sericin content of silk fibers in a manner such that the adherent qualities thereof are largely if not entirely obviated while the hygroscopicity of the fibers is retained and the fibers are readily separable.

A specific object of the invention is to effect a modification of silk fibers in silk waste by a sub-- and for a period suflicient to bring about the desired modification of the fibers. V

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the seva eral steps and the relation of one or more of such steps with respect to each of the others, and the product possessing the features, properties, and the characteristics which are exemplified in the following detailed disclosure, and the scope of the 10 invention will be indicated in the claims.

Silk, which may be in the form of waste, may be modified and adapted for the production of yarn by freeing it from the gum or sericin which is a natural component, or by altering the sericin 5 so that the adherent properties which attend it in its natural condition are substantially removed. Thereby the fibers are so changed that by carding and combing there is obtained a staple fiber which may be spun into a yarn, or othergo wise utilized. I

In the practice of the invention, silk fibers are treated in a manner such'that the sericin is not removed, but the adherent properties are almost wholly obviated and the fibers thereby become 25 readily separable with a retention of their hygroscopic properties. This may be effected by treating silk, more especially a silk waste, with a solution containing a substance capable of removing andin an amount suflicient to remove substantially all of the adherent properties of sericin, but without any material destruction of the hygroscopicity of the silk fibers. More particularly, the treatment comprises immersing silk in a bath containing a substance such as above defined, and specifically a metallic salt belonging to the group consisting of soluble salts, as chlorides, nitrates, sulfates, acetates of cadmium, bismuth, antimony, cobalt and aluminum. These salts preferably are in the form of sulfates, which may be either simple, double or complex.

Moreover the treating substance may be a member of the group .consisting of oxybenzoic acid, salicylic acid and coumarin. An amount of the compound is dissolved in water to give a concentration upwards to 10%, and such solutions are utilized for the processing of the silk. The temperature at which the procedure may be carried out is ordinary room atmospheric temperatures, and while the period of treatment may vary, it has been found desirable, and satisfactory results have been obtained, by an immersion offrom two to three hours. Following the period of treatment the silk is removed from the bath, freed from adhering solution or aqueous bath liquid by centrifuging, and purified by immersing in water, centrifuging and then again immersing in water and centrifuging with a final drying.

The silk obtained by the processing just described retains substantially its natural content of sericin with a substantial obviation of theadherent qualities and a rending insoluble in ammonia and organic acids, as acetic and formic acids. There is obtained a fiber which is hygroscopic, elastic, rugged, and a non-conductor of electricity, so that it does not readily become disordered and knotted, and upon carding, combing and spinning yields from a waste a relatively high percentage of yarn with an accompanying by- -product which, because of its hygroscopic and 100 parts of silk are immersed in from 700 to 800 parts of an aqueous solution of a metallic salt, thus a sulfate of aluminum in a concentration of, from 1 to 3%. The silk is permitted to remain in the bath or in contact with the solution for a period of from 2 to 3 hours and at atmospheric temperatures. During this period a portion of the silk may be removed at intervals for the purpose of determining the separability of the fibers and the condition or adherence of the sericin. When it is found that the fibers may be readily separated, and that the adherent properties of the sericin have been substantially removed, the silk is taken from the bath and separated from the solution or aqueous bath clinging to it by centrifuging. Following this the silk may be repeatedly rinsed in cold water with intervening centrifuging, and finally dried. After drying it may be passed through a beating process and then combed and carded, yielding a staple fiber which may be spun into yarn.

As a result of the foregoing process there may be obtained from 100 parts of silk parts of treated material which, when carded and combed, gives from 70 to 73 parts of staple fiber and as a by-product 8 to 10 parts of a silk mass which may be cut and made into a felt in combination with other felting materials, as hair and wool. The by-product consequently is not a waste material, but is useful and of value. This is in marked contradistinction to former methods in which parts of silk would yield, after boiling in a soda bath, for example, about '70 parts of silk which, when carded and combed would give about 50 to 52 parts of staple and from 18 to 20 parts of a byproduct which is of little value, is not capable of being felted, and has few industrial uses.

Example II Silk cocoons may be treated so that the fibers are readily separable and the adherent qualities of the sericin substantially obviated by first extracting the oil present in the cocoon by a suitable solvent material. Having completed the extraction of the oil, 100 parts of the extracted cocoon material may be immersed in 700 to 800 parts of an aqueous bath containing 2 to 3% cadmium sulfate, and the cocoon allowed to remain therein for a period of time. The remaining steps of the treatment are then the same as set forth in Example I.

This treatment yields a cocoon mass from each 200 lbs. of treated material.

which the fibers may be readily separated, and

gives about 65 to 70% of treated material. which contains about 40 to 42% of silk, and after carding and combing gives 28 to 29% of a staple fiber and a lay-product silk mass which, after cutting, may be manufactured into a felt and other articles.

Example III 100 parts of silk waste are immersed in 700 to 800 parts of a bath containing a water solution of salicylic acid in a concentration of 7 to 10%.

'Ihe silk is allowed to remain in the bath, as in Example I, and the other procedural steps are as given therein.

In the foregoing processing the final treatment is by rinsing in water followed by centrifuging with a final drying. This treatment entails the use of from 8 to 10 cubic meters of water for Moreover, the processing of the silk leads to the obtainment of a silk fiber having marked hygroscopic characteristics and a staple yarn which in amount is considerably more than that produced by previous procedures.

The retention of the sericin in a non-adherent condition and. without loss of hygroscopicity makes the fiber well suited for conversion into a staple which may be spun into' yarn, and the procedure whereby the improved fiber is oblainedis materially less costly than the former process of boiling to remove the sericin, inasmuch as a given quantity of finished product requires a lesser quantity of raw material, and in view of the fact that there is'a decided saving in both time and labor.. The fiber obtained is characterized by being'soft, hygroscopic, non-adherent, elastic, rugged, and a non-conductor of electricity.

Moreover, when the fibers are spun into yarn and the yarn woven intogoods, these fibers remain in the positions in which they were placed in the woven material and do not tend to slide from such positions so that the woven goods possess the quality of maintaining its woven features without displacement of fibers through stretching or otherwise.

In addition, the fibers can be bleached without loss of weight, and therefore can be dyed with light colors as well as 'with dark colors. The dyeing may be carried out either with the fibers in the yarn state or after weaving. When dyeing, the various acid colors may be utilized and the dyed material is resistant to light andother atmospheric conditions.

It may be added that the procedure for purification followed in the present process leads to economies and may be carried out with greater facility than the method heretofore employed. It has been usual to rinse. the material following treatment to remove the sericin, by placing it under a jet of water having a pressure of 75 to 90- lbs. and a flow of from 90 to 100 gallons per secend. By the process herein described the use of water under pressure is not necessary, and only about one-one hundredth ofthe quantity of water previously used is required. Further, no

out departing from its scope, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following properties of'ithe claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A method for processing'silk, which comprises treating silk fiber with an initial aqueous solution containing from about 1% to about 10% of a metallic salt belonging to the group consisting of soluble salts of cadmium, bismuth, antimony, cobalt and aluminum whereby substantially all of the adherent properties of sericin are removed while retaining the sericin on the fiber and without destroying the hygroscopic properties of the silk fiber, and at substantially ordinary temperatures.

2. A method for processing silk, which comprises treating fiber with an initial aqueous solution containing from about 1% to about 10% of a metallic salt belonging to the group consisting of soluble salts of cadmium, bismuth, antimony, cobalt and aluminum whereby substantially all of the adherent'properties of sericin are removed' while retaining the sericin on the fiber and without destroying the, hygroscopic silk fiber, and at substantially ordinary temperatures for a period of from 2 to 3 hours and with a quantity of solution substantially '1 to 8 times that of the silk.

3. A for processing silk, which comprises treating silk fiber with an initial aqueous solutionficontaining upwards to 10% of a metallic salt belonging to the group consisting of soluble saltsof cadminm, bismuth, antimony, cobalt and aluminum, whereby substantially all of the adherent properties of sericin are removed while retaining the sericin on the fibers and without datroying the hygroscopic properties of the silk 11 r.

4. A method for processing silk, which comprises treating silk fiber with an initial aqueous solution containing from about 1% to about 10% of a sulfate of aluminum whereby substantially all of the adherent properties of sericin are removed while retaining the serlcin on the fibers and without destroying the hygroscopic properties of the silk fiber.

5. A method for processing silk, which comprises treating silk fiber in an initial aqueous bath containing from 1 to 3% of a sulfate of aluminum for a period of 2 to 3 hours at atmospheric temperatures wherebyv substantially all of the adherent properties of sericin are removed while retaining the sericin on the fibers and without, destroying the hygroscopic properties of the silk fiber.

6. A method for processing silk, which comprises treating silk fiber in an aqueous bath containing from 1 to 3% of a sulfate of aluminum for a period of 2 to 3 hours at atmospheric temper atures, freeing the fiber from adhering aqueous bath by centrifuging, then immersing in water, again centrifuging, immersing another time in water, and finally centrifuging and drying.

7. A method for processing silk, which comprises extracting oil from treated silk cocoons, immersing the so treated cocoons in an initial aqueous bath containing from about 1% to about 10% of a metallic salt belonging to the group consisting of soluble salts of cadmium-bismuth, antimony, cobalt and aluminum whereby'substantially all of the adherent properties of sericin are removed while retaining the sericin on the fibers and without destroying the hygroscopic properties of the silk fiber at ordinary temperatures, freeing the thustreated cocoons from adherin'g aqueous bath by centrifuging, and then purifying by repeated immersion in water, centrifuging, and finally drying.

8. As an article of manufacture a silk fiber carrying substantially its natural content of sericin, said cericin being in modified conditionso that it is substantially without adherent properties, insoluble in ammonia and acetic and formic acids, said fibers possessing hygroscopicity, elasticity, ruggedness, non-conductability of electricity, capable of dry spinning and of being dyed with acid colors in the usual manner, and obtainable by the method defined in claim 4..

9. As an article of manufacture, silk waste in which the fibers are readily separable, said fibers carrying substantially their natural content of sericin which is in modified condition so that it is substantially without'adherent properties, insoluble in ammonia and acetic and formic acids and possessing hygroscopicity, elasticity, ruggedness, non-conductability of electricity, capable of dry spinning and of being dyed with acid colors in the usual manner, and obtainable by the process defined in claim 5.

10. A method for processing silk, which comprises treatlng silk fiber in an initial aqueous bath containing upwards to about 10% of sulfate of aluminum for a period of two to three hours at atmospheric temperatures, freeing the fiber from adhering aqueous bath, then immersing in water, again freeing the fiber from adhering aqueous bath, immersing another time in water, and finally freeing from adhering aqueous bath, and drying.

11. A method for processing silk, which comprises treating silk fiber in an initial aqueous bath containing from about 1% to about 10% of a metallic salt belonging-tothe group consisting of soluble salts of cadmium, bismuth, antimony, cobalt and. aluminum for a period of two to three hours at atmospheric temperatures, freeing the fiber from adhering aqueous bath by centrifuging, then immersing in water, again centrifuging, immersing another time in water, and finally centrifuging and drying.

. ALESSANDRO GANDINI.