US2220805A - Treatment for animal fiber - Google Patents

Description

- Patented Nev. s, 1940 UNITED STATES PATENT" oFFrcs 2,220,805 I V mmmnr ron ANIMAL FIBER Williain' Beach Pratt, .Boston, Mass; Annette Harris Pratt, ,administratrix of said William Beach Pratt, deceased; assignor to Aldox Corporation, Dover, Del, a corporation of Delaware No Drawing. Application July 18,1938, Serial No. 219,823

I 3 Claims. (Ol.-8128) The attachment of the aldehyde radical to the nitrogenous fiber must be carried out in the abence of substances having a "greater aiiinity for the aldehyde present than the aflinity for the nitrogenous fiber thereof, and is preferably effected in' an aqueous both free from. substances reacting with aldehyde to form condensation products. The subsequent oxidation of the alde-.

hyde radical should also be carried out -in the absence of any substantial alkalizing influence.

The fibers are preferably treated in accordance 20. with myinventionbefore being subjected to ordinary cleansing treatments which so deteriorate or break down the fibers that their natural char acteristics cannot be restored My treatment is applicable to the fibers before or after removal from the skins or-in the form of fibers, per se,

-' filaments, yarns or-fabrics.

By my method of treatment, not only is a chemical compound formed between the aldehyde and fiber molecules, but the greasy, gummy, waxy;

Q gents.

The lowering of th melti g points of the .grea'ses, waxes, etc., is accompanied by an increase in the resistivity of the. fiber itself .to thei action of heat, hence the treatment may be car- 40 ried out at; a temperature such that the oils, greases and waxes are rapidly emulsifiedwithout inluryj to the fiber itself.

The removal of such substances and the subsequent removal of the aldehyde radical gives thefibers a lofty hand and permanent set, makes possible the bleaching of such fibers without dev v solutions are-used, the solubility or dilution is teriorating effects, renders the fibers more" resistant to the physical effects resultlngrfrom- .washing untreated fibers in "alkaline solutions, makesthe fibers more hygroscopic,-and improves dye absorption and the tinctorial eii'ect ofdyes vmay .be used to'reduce the pH of the bath to cation with water of the softened, greasy, gummy and like constituents, it should not be suifioiently high to impair the natural elasticity of the fiber or to cause wasteful loss of aldehyde from aqueous solution. The loss of aldehyde from aqueous solution may be retarded by forming in the bath a loose bedof fibers of substantial thickness.

The attachment of the aldehyde to the molecules of the fiber appears to take place most read= 11y when the bath is substantial y neutral, or has I101 a. pH of say '7 to 9 and fre e'fromany substance reactive with aldehyde to form a condensation product. Thefiber may have the aldehyde 'combined therewith by immersion in a bath, of such pH, containing initially only trioxymethylene. ll After suflicient aldehyde has been released from the trioxymethylene and attached to the fiber, suitable detergents, such as neutral soap and borax, may be addedhto the bath to facilitate ;emulsification and removal of the grease and 0 waxes. A good attachment of the aldehyde to they fiber, and a somewhat more rapid processing is, however, secured when the detergents are added to the bath at the beginning of the aldehyde treatment, since the aldehyde and borax both 2 tend to reduce. the'pH which would result, from the soap alone. If a soap producing a pH of, say, 10.2 is used, sufiicient borax and'aldehyde around 8. e I 7 My tendency toward decomposition of the soap is avoided by the maintenance of a temperature below its decomposition point and counteracted by'the inclusionIof the borax in the bath. The action of borax in keepingthe solution at a pH value as low as possible" without injuring'the properties of the detergent, is of distinct advantage in the treatment of animal fiber.

. I'may provide the bath for giving the aldehyde treatment by diluting with water-standard com- (0* mercial aqueous solution of formaldehyde of say 3.7-to 40 concentration, or I may employ reversible polymerization products of formaldehyde free from extraneous substances. Such products as trioxymethylene or para-formaldehyde may 45 be employed. Where commercial formaldehyde uniformly distributedthrough such solution] re- I gardless of the water temperature, but when 'para-formaldelwde orutrioxymethylene is em- 50 ployed thetemperature must be raised to at least. F. to insure complete solubility throughout the aqueous solution of formaldehyde produced by the splitting up of these polymerization products. But even whenia dilute commercial som 55 tion of formaldehyde is employed, the bath should be maintained at a temperature of at least 120 F. in order that the free formaldehyde gas present in the solution may adequately act on the greases and gums and combine with the keratin or fibroin on the fiber.

The neutral soap, borax and aldehyde, in the form of trioxymethylene, may be well mixed together in dry form and then dissolved in the water to form a bath substantially free from substances with which aldehyde tends to form condensation products or for which it has a greater afiinity than it has for the animal fiber. The bath should have a temperature which eifects the liberation of the aldehyde and the chemical combination thereof with the molecular structure of the animal fiber and increase the solubility and factors of emulsification of the greasy and gummy constituents of the fiber. As the aldehyde lowers the melting points of the greasy and gummy constituents and increases the resistance of the fiber to the action of heat, the treatment can be readily carried on at a temperature of say 140 F. which is above the point to which the aldehyde lowers the melting point of the gummy and greasy constituents and well below a point injurious to the aidehyde treated fibers.

The aldehyde so combines with the molecules of the fiber as to resist removal by repeated washings, which washings effect the substantially complete removal of the foreign matter such as grease, lanolin, seresin, and other oily and gummy substances. v

After the washing of the fibers, the aldehyde radical or constituent of the keratinous or fibroin molecules is removed by the oxidation thereof into an acid in the presence of water, which takes the place of the aldehyde radical and hydrates '40: the fibers.

The removal of the aldehyde radical should preferably be eifected by means of an oxidizing agent capable of the use in neutral or slightly acid solutions as it is desirable that the oxida- 5' tion be carried on under conditions free from alkalizing influences.

I have successfully employed a solution containing. say, 0.25% of potassium permanganate (based on the weight of the fiber) and a small m amount of sulphuric acid or magnesium sulphate to act as a buffer in neutralizing any caus tic soda that might be freed through reaction. Other suitable oxidizers for removing the aldehyde after it has been firmly attached to the Q fiber molecules and effecting substitution of wa- The following is a specific example, but by way of illustration only, of the carrying out of my invention for the treatment of wool.

A mixtureof say 40.pounds of trioxymethylene,

20 pounds of borax, and 100 pounds of neutral.

soap of low'titer, is dissolved in water sufiicient in amount for the wetting and immersion of say ten thousand pounds of wool. The treatment may be carried on in thestandard equipment commonly used for wqol scouring, but the treating tanks should preferably be made of 75 wood and be substantially free from any exposed iron. The treatment may be carried on either in batch or continuously, depending upon the character of the equipment employed.

The wool is subjected to the action of the solution at a temperature between 120 F. and 140.

F. and preferably in the neighborhood of 130 F. for approximately fifteen minutes. At the end of this time the wool is passed through a washing tank where the impurities, soap and any uncombined aldehyde are thoroughly removed from the fiber. The presence of the combined aldehyde in the fiber may be tested by treatment of a washed sample with Fehlings solution. When the aldehyde bath is initially free of detergents, a somewhat longer combining time is generally desirable than where detergents are initially present.

The thoroughl cleaned wool is then passed through an aqu ous solution containing say 0.25% of potassi permanganate or sodium permanganate, base on the weight of the wool, and at a tem ature preferably between 104 .F. and 120 F. The aldehyde treated fiber acts promptly to reduce the permanganate solution to a clear aqueous solution with the permanganate salts of decomposition precipitatedin or upon the animal fiber. This precipitation will ordinarily take place in about .ten minutes. When the precipitation is complete, the fibers are passed directly into a solution of sodium bisulphite and/or sulphurous acid to remove the decomposition products'from the reduction of permanganate. The wool is then rinsed'inrunning water to wash out the soluble products .so formed; In regular commercial practice, and where it is not necessary to secure'the highest degree of whiteness, a regular hydrogen peroxide bleach may be employed, or any standard method for bleaching the wool as is practiced after the usual scouring operation.

The oxidizing treatment may be so limited as to merely free the animal fiber from the aldehyde radical to hydrate'the fiber and permit subsequent bleaching, or the oxidation may be carried on until the fiber is partially bleached or bleached to a pure white.

I have heretofore pointed out in my co-pending application for Patent 2,126,809, whereof the present application is a continuation in part, that nitrogenous fibers having a sulphur containing radical may be advantageously treated with aldehyde to improve the texture and loftiness of the fibers and with oxidizing agents to prevent the formation of condensation products from. the aldehydic constituent and efiect bleaching of the fiber. of certain fibers are best effected after subjecting the fibers to an ammoniacal treatment which attacks the sulphur constituent of the sulphur radical of the fiber, to the ultimate removal or rearrangement of the sulphur radical. Such am- Such aldehydic and oxidizing treatments moniacal treatment renders the fiber much more readily susceptible to the action of the aldehydic and oxidizing agents. By such ammoniacal, al-

dehyde, and oxidizing treatments, naturally black yarns composed of or containing them, they may -be immersed in and drawn through an aqueous solution containing approximately 6% of 'ammonia, approximately 1% .of aldehyde; 1% of neutral soap, and 1% of sodium perborate or other suitable oxidizing agents based on the treatment without danger of forming condensation products.

After immersion for approximately two hours at a temperature of from 130 to 140, the fibers are rendered lofty, white and free from grease and dirt. Should the fabrics be darkly pigmented,

naturally, a larger percentage of oxidizing agent may be used or the fibers may be given repeated treatments until a pure white is obtained.

For degumming and bleaching silk the same treatment may be usedrbut the ammonia should be dispensed with.

Howsoever the practice of my invention is carried on, the baths employed shouldcontain no reagents free to combine with aldehyde to form condensation products or deleteriously effect the nitrogenous fibers, as, for instance, soda ash, caustic soda, trisodium phosphate or sodium bisulphate. 'The use of soaps that tend to break down readily and release alkali at the treatment temperatures should be avoided. The presence in a bath containing aldehyde of reagents free to combine therewith to form insoluble condensation products not only retards or prevents the liberation of free aldehyde gas and the combining thereof with the molecules of the animal fiber, but may also stain the goods and even effect removal of some aldehyde radicals which have been attached to the fiber molecule. The formation of objectionable condensation products from the reaction of the aldehyde with such reagents will frequently take place at lower temperatures than the temperature at which aldehyde satisfactorily combines with molecules of animal fiber. Hence while such condensation products of aldehyde and The reaction of the aldehyde on the greases and gums inherent in natural animal fibers appears to be both chemical and physical. Their melting points are lowered and they appear to change in surface tension to increase water ab- 5 sorption. They are rendered by my treatment readily removable from the animal fiber by washing, particularly when proper detergents or emulsifying agents are employed in a subsequent washingoperation.

Having described my invention, I claim:

1. In the treatment of animal fibers having a greasy or gummy constituent, the steps which include lowering the melting point of such constituent by treatment with an aldehyde in the presenceof a detergent of the group consisting of a neutral soap and borax at a temperature below the decomposition point of the detergent and above the point to whichthe aldehyde lowers the melting point of the constituent.

2. In the treatment of animal fibers having a greasy or gummy constituent, the steps which include treating the fibers with an aqueous solution containinga detergent of the group consisting of a neutral soap and borax and a reversible poly- 25 merization product of formaldehyde free from extraneous substances at a temperature at which the melting point of such constituent is lowered and aldehyde combines with the molecules of the fiber.

3. In the treatment of'keratinous fiber having a natural gummy or greasy constituent, the steps which include impregnating the fibers in an aqueous formaldehyde neutral soap bo'rax solution de-. void of reagents combining with formaldehyde in the presence of borax and at a temperature substantially in the range of to F. until the melting point of such constituent islowered and an aldehyde radical has formed on the fiber, and substituting water for the aldehyde radical by oxidizing the aldehyde to acid in the presence of water prior to any reaction of the radical to form a condensation product.

wnmau BEACH PRATI'.