US1661879A - Treatment of cellulosic materials - Google Patents

Description

Patented Mar. 6, 1928.

UNITED STATES PATENT orFicE.

DENIS DI GONCZ, 01! NORTH ADAMS, MASSACHUSETTS, ASSIGNOB TO ARNOLD rm WORKS, 01 NORTH ADAMS, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

TREATMENT OF CELLULOSIC MATERIALS.

No Drawing.

This invention relates to the treatment of textiles and other constructions of cellu ments for the purpose of reconstitutingv their texture by the developmentof cellu losic derivatives in a rearranged and improved physical condition as compared'with the natural material, fibre, or texture.

The present process has for one of its objects to improve the steps of treatments of this category for. economy of time and material, certainty of result, and an improved effect or final state of the product.

, The practices of the prior art do not at? tain the effect gained by the present process, and are moreover in general characterized by difliculties in realization due to lack of stability or variable quality of the reagents necessarily employed. For example, a. preferred solvent reagent of old use is an ammoniacal solution of copper, or cuprammonium so-called. Heretofore it has been customary, if not necessary, to use a solution containing caustic alkali, without which alkaline qualification the reagent is not certainly or suiiiciently active upon the fibrous cellulose. 'But this fact has militated against the use of this reagent, because an alkaline ammoniacal solution" of copper 1S prone to break down spontaneously, with.

separation of copper oxide. This has led to uncertainty of results and to necessity for frequent renewals of the solution, as well as to ineffective or damaging treatment of the cloth when the solution decomposes during a run of treatment.

Such treatments of vegetable-fibre fabrics have heretofore been characterized in groups roughly identifiable by their eifects as those producing mercerized fabrics and those producing parchinentized fabrics, with some variations relating to the physical state of the surfaces of the fabric, such as the production of high silky glosses by mercerizin and stretching, of wrinkled or creped e fects, or effects upon vegetable fibres resembling the texture of wool. The effect gained by the present invention is a trans Application and September 22, 1924. Serial No. 739,201.

1 formation or conversion yarns to the natural effect of long-line linen, the product being cool to thetouch, smooth, glossy, having a superficial transparent skin effect, slightly lessened flexibility, high absorption and (permeability, improved tensile strength, an freedom from stray thin fibres or fuzz. material for treatment in the case of textiles is cotton.

In the preferred practice, the material to be treated is made to carry a reagent substance in measured. quantity entrained with the texture of the material into the presence ofa cellulose solvent adapted to be activated by the presence of the said material-carried reagent in its solvent or other reactive capacity toward the cellulosic material. For example, there will herein be described in detail, as one instance of thisinvention, the application of a measured dosage of an appropriate reagent to a sheetmaterial to be treated. If the solvent is to be an ammoniacal solution of copper, a preferred reagent to be carried by or entrained with the material is. an alkaline solution such as caustic soda, which may be supplied to the material in any convenient way for securing a uniform distribution, as by padding by dipping and squeezing (or partially drying, or both) or by treatment otherwise securing an even distributionon the surfaces and in the capillary spaces of the cloth or other material of the reagent or activating solution. But I am not. to be understood as limiting this process to the treatment of everypart of a web of material, since the treatment obviously may be applied locally chemical efi'ect such as mercerizing at the.

normal temperatures and times of treatof the component The most advantageous ment other than adsorption upon the cellulosic contents of the alkaline contents.

When the material is prepared by-associating with it an alkaline reagent in this manner, the capillary and adsorptive association of the material to be treated with the alkaline reagent prevents or inhibits the acti- -vating reagent from leaving the surfaces and capillary spacesof the fabric or material in a subsequent dip ing bath. This is important, because while t e reagent is necessary to activate the solvent, it is thus ensured that the solvent be not degraded by any substantial diffusion of the activating agent away from the material to be treated and into the solvent solution. This localizes the reaction at the surfaces and in the capillary spaces between the fibrous elements of ment in a wet state with the solvent proper;.

but in any case, I have discovered that when the material so carries a measured dosage of the activating reagent which primarily operates according to its chemical, physical or catalytic nature, into the presence of the solvent (for example, respectively, cotton cloth carrying caustic soda solution into the presence of ammoniacal copper solution), there ensues a three-part reaction participated in by the activating reagent, by the solvent solution, and by the nascent cellulosic surface, solution or colloid extension formed at the seat of the reaction. This reaction, whatever its true nature in a physical or chemical sense, is not only highly effective to produce the effect of linen on cloths of other vegetable fibres but the reaction proceeds with controllable regularity at practicable high speeds, and especially in the case of alkali-activated copper-ammonia solvent, results in high economy of solvent chemicals, the losses of the caustic and solvent baths being only those directly attributable to causing the improvement in the cellulosic material. I attribute the gains of solvent etiiciency and regularity of action to the spperior effect of a solvent in a state of being uniformly and locally activated by the entrained activating substance, as well as to the superior type of application to the cellular surfaces secured by confinement to and against them of the seat of chemical activity;

and to the relatively large proportion of reactable cellulose in the presence of the en-' tire active quantity of the reagent solution, thus effectively provided for.

Details of the treatment may be varied according to the material to be treated and the degree of conversion desired to be realized. The weight or cellulosic mass-contents of the cloth to be treated, for example, to a degree indicates the concentration, of the reagents, especially of the alkaline activating reagent, and the state of the material attained by previous 'usual treatments, such as bleaching or mercerizing treatments, may also be taken into consideration. One of the advantages ofuthis treatment resides in the ease with which the previous state, weight. density (and in general, the reaction power) of the material treated may be compensated for, and in the consequent applicability of this process, with predetermined desirable results of a linenizing finish, to cotton cloths and other materials of widely varying mass, texture and previous conditions of treatment.

The invention is well illustrated by reference to typical examples of practice as follows:

A relatively heavy continuous web of cotton (for example, of double-cloth suitable for vestings, collars or shirts) without previous treatment except scouring to make it absorbent, or bleaching when desirable. is continuously passed at a predetermined rate through a bath of a solution of caustic al ali in a suitable dipping and squeezing or 0 her padding device; or the alkaline solution is otherwise suitably applied, in such a way as to effect a brief wetting contact with and entrainment of the solution on the surfaces and in the capillary spaces of the cloth. The web continues for a predetermined time of travel (insufficient in relation to the alkaline concentration for reaction of the solution with the cellulose in any chemical sense) and with or without evaporative conditioning of the entrained reagent, into prompt contact with a dipping or other applying bath of the solvent reagent, preferably cuprammonium as mentioned below. Here also the time of treatment, controlled by the length of the bath and the rate of passage of the web, is very brief. Thereafter the web is treated to neutralize, washed, stretched and dried.

In the instance given, a solution of commercial caustic soda of 19 Twaddell (1.095 sp. gr.) at normal room temperatures of 20 to 30 C. in contact with the fabric for six to eight seconds between first contact and the solvent bath. without substantial intermediate evaporation, is satisfactory. The alkaline entrainment in the fabric is well secured by passing under a dip roll in a trough vat of the solution, to emerge between squeeze rolls and immediately pass to a similar padding machine for the solvent treatment, the padding machines being conveniently close together, and the cloth traveling at the rule of thirty to forty yards per minute.

The solvent bath preferred in the given case contains forty pounds of copper sul- IOU ' evaporates from the solvent, and the fabric isobserved to be blue from the precipitated copper oxide of the reaction in the padding bath. During or after tentering, prefes ably after, the cloth is soured in dilute sulphuric acid, recommended to have a concentration of 6? Twaddell (1.03 sp. gr.), washed in copious water, and laundered, dried, ironed or calendered as may. be desired.

The concentration of the caustic bath may be utilized for control of the effect, and should be lessened when the mass of the web is less, or when previous treatment, such as yarn or piece mercerization, has increased susceptibility of its'cellulose to solvent reac-. tions. A plain muslin for example, under the conditions of treatment above indicated, is recommended to be padded with a caustic solution of about 14 Twaddell (1.07 sp. gr.) concentration, andconcentrations'as low as 12 Twaddell may be advantageouslyemployed when the previous condition of the web renders it highly sensitive.

For light fabrics, the ammoniacal copper solution may also be reduced in concentration; for example, to half the concentration above mentioned.

When I refer to padding the reagent substances into or upon the material to be treated, it will be understood that I do notnecessarily refer to complete bibulous saturation. In many cases it is advantageous and desirable to limit the application of the entrained reagent to one surface, or to a pattern. For these purposes, the padding treatment may be carried'outby spraying, by printing, by stenciling .or with the aid of resists applied to the webs superficially or interstitially. However the application. of the activating reagent is performed, it is preferable to remove any wet excess .before. contact with the solvent solution, in order to avoid degrading the solvent solution by transfer to it of any free excess alkali. This process is thus in part characterized by the preliminary association of thecellulosic structure with the activating substance, and the subsequent contact of this association with the solvent substance to be activated.

lVhatever may be the mutual interaction between the cellulose, the alkali, and the cuprammonium, the ultimate effect indicates the reaction to be. catalytic in character. The cuprammonium solutions employed when acting independently on cellulose are of such a degree of dilution as to be substantially inert; the alkaline solution is correspondingly ineffective alone, whereas the solvent effect of the tripartite group of cellulose, alkali and cuprammonium on its cellulose member'is most pronounced and exceedingly rapid. It may be postulated that copper oxide is formed by reaction between the cuprammonium compound and the alkali, and that thecopper oxide, in a finely divided and nascent state, is a catalyst for the action of the contact-film of the remaining substances in solution upon the cellulose. It will be observed thatthe recommended treatment places the tripartite group in necessary contact with the material to be treated throughout the possible seat of anyreaction,

and that the reagents are nowhere else in an active state. A constant effect on the material treated, uniformly distributed and invariable in degree of chemical activity, in

accordance with the'predetermined concentrations, temperatures and times, is thus secured. It is to be understood that the specific instances of practice of this process herein described are illustrative only of the principle of the invention, which is not limited to the species used for illustration. For example, it is obvious that other activating reagents or other solvent solutions may appropriately be substituted, and that the principle of the invention is independent of mere choice of materials to be treated or fibrous stock or after making into yarns or into fabrics such as cotton cloth; and'particularly the heavier grades of textiles, such as sheeting, osnaburgs or collar cloth, treated in accordance withthe invention, acquire a more lustrous surface and have more sheen. According to the degree of treatment, more or less ofthefuzz is removed, and individual fibres tend slightly to agglomeration in bundles, to become rounder, without substantial loss ofdiameter, and the integuments of the fibres become less striated, smoother, stifl'er and harder. cally, the treated fibres are more polished and superficially more transparent. It will also be observed that the individual yarns, when the fabric is a woven or knit fabric,

j are slightly stiffened, have a greater tensile strength, that there is little or no cementing tendency at points of contact between yarns, and that the permanently slightly hardened surfaces which result give the smooth, coolingsensation to the touch which is charac- Opti-- teristic of linen; and finally, that all of these properties thus imparted to the fibres are permanent, resisting both the action of normal wear and subse uent washings. The fabrics resulting are t ms permanentl and insolubly dressed in effect, as if very lightly starched, but, as may be shown by raveling, no paper-like adhesions between yarns result from the described degree of treatment of an organized textile, and the flexible and durably flexible character of the textile structure is decreased merely in degree, without any loss of the useful qualities expected of a cloth. The cloth may thus be repeatedly folded and machine-sewed without breakage or increased difficulty of sewing. The qualities gained by the treatment are positive and valuable accordingly.

If lighter grades of textile fabrics are subjected to the treatment, they obtain in addition to the above properties also a very marked degree of transparency. The degree and uniformity of treatment efi'ected is enconverting treatments, and produces a prodnet in which the glossing effect does not involve the tensile elongation with substantial loss of diameter, of the fibres composing the fabric, as is the case with fabrics glossed by alkaline reaction with concomitant heavy stretching.

The term natural cellulosie material as used in the claims is intended to include the well known vegetable fibres such as cotton, jute, linen, ramie and wood, but to exclude esters of cellulose such as the well known artificial silks and the like.

I claim:

1. Process of treating natural cellulosic material of the character described which comprises applying to such material a solvent activating agent, and thereafter subjecting the material containing the activating agent to the superficial action of a cellulose solvent.

2. Process of treating natural cellulosic material of the character described which comprises wetting such material with a solvent activating solution, and thereafter subjecting the material containing the activating agent to the superficial action of a cellulose solvent.

4. Process of treating natural cellulosic material of the character described'which comprises applying to such material a caustic alkali, and thereafter subjecting the material containing the caustic alkali to the superficial action of a cuprannnonium solution.

5. Process of treating natural cellulosic material of the character described which comprises wetting such material with a caustic alkali solution, and thereafter subjecting the material containing the caustic alkali to the superficial action of a cuprannnonium solution.

6. Process of treating natural cellulosic material of the character described which comprises filling the interstitial spaces of the material with a caustic alkali solution, removing excess caustic alkali solution, and introducing the material containing the remainder of caustic alkali into a cuprammonium solution for superficial action thereon.

7. Process of treating natural ccllulosic material of the character described which comprises treating such material with a caustic alkali solution of a strength incapable of chemically afi'ecting the cellulosic material during the time of such treatment, and thereafter introducing the material containing the caustic alkali into a cuprammonium solution for superficial action thereon.

8. Process of treating natural cellulosic material of the character described which comprises filling the interstitial spaces of the material with a caustic alkali solution of not substantially greater than 19 Twaddell concentration, and thereafter subjecting the prepared material containing the caustic alkali for a limited {period of time to the superficial solvent action of a cuprainmonium solution.

9. Natural cellulosic material of the character described superficially modified by the physical action of caustic alkali activated cuprammonium.

Signed by me at North Adams, Massachusetts, this fourth day of September, 1924.

DEN IS on GQN CZ.