US2378186A - Process for stabilizing textiles - Google Patents

Description

June l2, 1945. J. A. CLARK PROCESS FOR STAYBILIZING TEXTILES Filed Feb, 15,l 1941- UWQQQ @QON Sak WQQQQQ mvENToR J was BY WMMMMNMMMMMMMWAW vvvvvvvvvvvvvvvm ATTORNEY Patented June 12, 1945 t raocsss Foa srAamzING TEXTILES .itunesv A. clark, Port chester, N. Y., signor a Sylvania Industrial Corporation, Fredericksburg, Va., a corporation .of Virginia Application February 15, 1941, Serial No. 379,100 't 3 claims. n (ci. 117-166) The invention relates in general to the treatment of fabrics formed in whole or in part of artificial fibres or filaments and in particular to a method for stabilizing the structure and form of rayon fabrics and to the stabilized fabrics produced.

In the conventional method of making fabrics.

by knitting and. weaving, the yarns are subjected to tension to secure proper operation of the knitting and weaving machines and to draw the fabrics through themachines. Fabrics made in such machines are not uniform in yarn tension and tend to shrink when wet. However, part or all of the shrinkage so acquired may be offset or lost through mechanical'strain and stretch that the fabric encounters in conventional finishing Consequently, when the goods are operations. again wet out, asin laundering, they will again tend to shrink either warpwise or filling-wise, or both. Prior methods of mechanical shrinking, such as the Sanforizing process, must eect by such treatments, a complete shrinkage equal to the ultimate shrinkage obtained by repeated predetermined structure which is substantially permanent. y

It is a further specific object to preshrink fabrics comprising artificial fibres, inparticular, cut staple rayon, and to render the shrunk condition substantially permanent.

It is a further object of the invention to stabilizethe dimensions of fabrics comprising artificial fibres or filaments to preventpermanent distortions. either by stretchingor shrinking. Other objects of the invention will in part be obvious and will in part appear hereinafter.

According .y to the present invention, textiles formed in whole or in part of artificial fibres or filaments arestabilized in predetermined dimensions by treating such textiles with a composition comprising an alkaline` dispersion of a coagulable hydrophilic cellulosic material, the textile beingV treated at-ian elevated temp'wature at which the alkali of the composition will vrot adversely affect the artificial fibres or filaments,

and the cellulcsic material being coagulated on laundering or else the fabric willshow an excessiveresidualshrinkage. Buch prior methods are thus incapable of permanently fixing the dimensions of the fabric in a partially shrunk condition although this is frequently necessary to atl tain a desired width in the fabric.

Moreover, such prior methods -of shrinking have not been entirely successful with rayon fabple viscose rayon. Owing to the swelling and shrinking which viscose rayon undergoes on being wetted and dried, fabrics made of such iliaments do not retain the condition resulting from the mechanical pre-shrinking operation.

lThereiore, it is desirable to provide fabrics,

comprising artificial fibres or filaments, whichare characterized by having a substantially permanent resistance todistortions of all types in 'order to preserve a desired structure, form and character in such fabrics.

On'the other hand, it is frequently desired to impart to fabrics, comprising artificial fibres or filaments, a predetermined structure or shape designed to enhance its general utility or to render the fabric adaptedlfor some special' uses. For example, it is desirable tc 'leave such fabrics with a predetermined and denite residual shrinkage so that the fabric will maintain its shape and structure during wear and laundering. Accordingly, it is a general object of the present inventionto provide a stabilized textile formed in whole or in part of artificial fibres and having a a rics, in particular of fabrics containing cut stal the fabric while it is maintained in the desired dimensions. Preferably the textile fabric is treated while free of suchlongitudinal ltension as will stretch the fabric and also, preferably, while the .fabric is being stretched transversely. The treated textiles may be washed and otherwise finished and finally dried. The cellulosic deposit on the fabric appears to resist permanent distortions ofthe treated fabric as a result o! laundering or wear,l and thus stabilizes the dimensions of the fabric against both stretching andshrinking. l

The present invention is -particularly adapted for stabilizing textiles formed in whole or in part of regenerated cellulose fibres or laments which may be derived from viscose, cuprammonium cellulose or the de-esterication of cellulose esters, such as nitrocellulose, or from solutions ofvcellulose in inorganic salt solutions and in organic bases such as the quaternary ammonium hydroxides. However, the process is also useful for stabilizing textiles comprising fibres or filaments of other hydrophilic colloidsI such for example as gelatine, casein and alkali-soluble water-insoluble cellulose ethers, the solubility of which is less than that of the cellulose ethers used in the alkaline dispersion at the time of applications. and such cellulose esters and synthetic resins as ,tend to swell in water orsoap solutions. The invention isalso applicable to vtextiles formed o fmixtures of two or more of the above-mentioned hydrophilic fibres or mixuble cellulose ethers such as the alkyl ethers, hy-

droxy-alkyl ethers and -carboxy-alkylA ethers,

mixed cellulose ethers, the xanthates of such cellulose ethers, and alkali-soluble cellulose thiourethanes. There may be used also cellulose per se dissolved in inorganic bases, such for example as aqueous solutions of sodium hydroxide, potasslum hydroxide and the like, and cellulose dissolved in strong organic bases, such for example as the quaternary ammonium hydroxldes. The composition may comprise a mixture of two or more diierent cellulosic materials oi types mentioned herein. I prefer to use the alkali-soluble, water-insoluble cellulose ethers because of their cost, clarityl lack ot odor` and ease oi application. The cellulose compound may be dissolved or colloidally dispersed in the bases. preferably by cooling the dispersion to C. with stirring. The expression "stabilizing composition as used in the following description and in the claims is intended to designate the dispersion (whether true solution or colloidal dispersion) of the hydrophilic cellulosic colloid in a dilute aqueous solution of a strong base whether inorganic `or organic.

In carrying out the process the 'concentration of the cellulosic colloid in the alkaline dispersion should be so regulated that the quantity of the cellulosic colloid deposited upon coagulation is sumcient for stabilizing the textile in the desired dimensions. In the now preferred ement, the cellulosic content of the alkaline dispersion is preferably from 2 to i0 per cent by weight of the dispersion, a preferred concentration with an alkali soluble cellulose ether being from 2 t0 6 per cent by weight.

The concentration of alkali in the stabilizing composition will depend upon the nature and concentration of the cellulosic material. However, since the ilbres and filaments which swell in water also swell in aqueous alkali solutions,

' it is advisable not to have the concentration of alkali in the dispersion any higher than necessary to maintain the coagulable cellulosic colloid in the dispersion condition. For example, when using a composition containing from 2% to 6% of alkali-soluble water-insoluble cellulose ether, the total alkali calculated as sodium hydroxide will normally be about 2% to 9%. When treating textiles comprisingiviscose rayon, it is advisable to have the alakli concentration less than and preferably less than 3%.

It is characteristic of the process of the present invention that the treatment o! the textile with the alkaline dispersion of the hydrophilic cellulosic colloid is carried out at a temperature above that at which the alkali present in the dispersion will adversely ail'ect the artificial libres or filaments in the textile. It the temperature is too low, the alkali will tend to swell excessively and even to disintegrate such artiilcial ric filling-wise.

ilbres as viscose rayon and iibres of alkali soluble-water insoluble cellulose ethers. On the other hand, if the temperature is too high and the alkali is high in concentration, kthe alkali will tend to saponify artiiicial libres made of cellulose esters, such as cellulose acetate. Accordingly, in carrying out the present process, it is preferable to maintain the temperature of the cellulose dispersion above 70 F., but the upper limit of temperature will vary with the concentration 'of the alkali and the nature of the libres, although temperatures as high as F. may bevused with no adverse eliect on most of the rayon libres.

The period of time during which the stabilizing composition is allowed to remain in contact with the fabric is dependent in part upon the pro- .portions of celulosic colloid and alkali in the composition and the temperature of treatment but more particularly, upon the method oi' application. If pressure is not applied to the fabric simultaneously with the application of the composition, a longer time should be allowed for the 'l thorough penetration of the composition through the textile and into the yarns. On the other hand, ifv the dispersion is applied under pressure as in a pad, a shorter time or treatment may be allowed, but even in this case, it is desirable to allow the composition to remain on the fabric for a short period of time such as one or two minutes before coagulation, for example, by giving the fabric an air-lay.

It is also characteristic of the present invention that the treatment of the textile with the stabilizing composition' should be carried out while the fabric is under substantially no tension or under a predetermined and uniform tension. VIn most cases the normal fabrication oi iabrics will tend to elongate or stretch the textile warpwise and'diminish its width. Therefore, it is desirable to treat the fabric with the stabilizing composition while the fabric is substantially free of warpwise tension and preferably under such conditions as to stretch the fab- By decreasing or preventing warpwise tension and simultaneously exerting a transverse tension, the fabric may be brought to the desired dimensions while it is being impregnated or treated with the stabilizing composition.

`after the fabric has been sulciently impregnated or treated with the stabilizing composition, the cellulcsic material may be coagulated on the textile by means of a suitable coagulant such for example as an aqueous solution of an acid or an acid salt, or by means of an acid gas. lit-is characteristic of the present invention that, during the step oi coagulation, the tension on the treated textile be so regulated that the textile is maintained or brought back to the desired dimensions so that the coagulation of the cellulosic material on the textile should occur when the textile has the dimensions and shape desired. Accordingly,

if the fabric has been freed from warpwlse'tension .and subjected to transverse tension, lt is advisable that the coagulation occur while the fabric is in the dimensions resulting from such tensions, although in most cases it will not be necessary to subject the fabric to iilling-wise tension during coagulation.

' It will be apparent from the above discussion of the chief features of the present invention that various mechanical means may be employed for carrying out the process. For a more coml Y asvaiao' `plete understanding of the nature and J.objects of the invention and the methods of application, reference should be had to the accompanying drawing in which: f

Fig. 1 is a diagrammatical representation of suitable apparatus for carrying out one embodiment of the process of the invention;

Fig. 2 is a top plan view of one of the rolls used in the treating tank illustrated inFig. I;

and

Fig. 3 is a diagrammatical representation of other apparatus suitable for carrying out another embodiment of the process..

While the process will now be described detail with reference to the apparatus shown in the drawing, it is to be understood that the process is not limited to operation with the apparatus shown andthat other devices may beemployed for carrying out the several steps of the process. Likewise, in the following detailed description reference will be made to the treatment of viscose rayon fabrics, but this is for the purpose of illustration and not by way of limiting the invention.

Referring to Fig. 1, arayon fabric I is led from the reel II between tension rolls I2 into a treating tank I3 where it passes first over a treating tank may be free of warpwise tension or can be placed under apredetermined tension while it is simultaneously stretched transversely to a predetermined width and the coagulation of the cellulosic colloid on the textile occurs while the textile .is maintainedsubstantially in such predetermined dimension. Thus, it is possible by usefof the apparatus of Fig. 1 to impart to a rayon fabric a reasonably predetermined dimen- 'f fabric.

The apparatus illustrated in Fig. 3 differs from that illustrated in Fig. 1 chiefly in not providing any means for `stretching the fabric filling-wise driven roll Il and then over and under a series of idler rolls I5. 'Ihe idler rolls-are of the divided corrugated type shown in Fig. 2, the corrugations tending to smooth out and stretch the fabric flllingwise as it passes over the rolls. The

stabilizing composition in the treating tank may be heated by means of the steam coils I6 disposed therein. The treated fabric passes from the tank I3 through the squeeze rolls I1 Vand I1' which remove the excess solution and then into a coagulating tank I8 of conventional type by means of which the fabric III is subjected to treatment with a coagulant of the cellulosic co1- loid. The surface speed of the rolls I1 and I1' are so correlated with the surface speed of the driven roll I 4, that th abric may be freed vfrom substantial longitudina tension while passing through the treating t i3 or may be subjected to a predetermi d warpwise tension. Since the rolls I1' may surface speed as the roll I1, the fabric may be passedinto the coagula 1 tank I8 under the same warpwise tension imparted to it in passing through the tank Il. From the coagulating tank Il, the 'fabric passes through the squeeze rolls I8`a into one or morewashers, such as the reel washer V'I9 which` is designed to carry the fabric in a rope form in a' number of passes through the washing liquid. Thewashed fabric may be opened either by hand or by means of a conventional opening device designated generally as 2 2. Before or after being opened, the fabric may be subjected to bleaching, dyeing or other finishing operations of a conventional type, which treatments per se form.no part of the present invention. The fabric isilnally dried in a m'anner such that the dimensions imparted to it in the treating tank will be preserved. That is, it is preferably dried free of warpwise tension,

driven at the same,

since such stretching is not essential with some fabrics comprising artificial fibres or filaments.

In carrying out the process with the apparatus of Fig. 3, a rayon fabric I0 passingfromthe reel Il is first saturated with the stabilizing composition by multiple passage over and under the rolls 22 which are positioned ahead of the padding rolls 23 in the treating tank 24. The composition in this tank may also be heated by means of steam coils I6. From the padder 23 the fabric is passed to an Yair-lay conveyor comprising an elongated tank 25 not supplied with liquid and having an endless belt 26 running therein. 'I'he speed of the belt is so correlated with the sur, face speed of the padder 23 that thefabric is delivered to the belt faster than the surface speed ofthe belt so that the fabric forms folds on the through the squeeze rolls I1 and I1' and into the coagulating liquid contained in the tank 21. From the coagulating tank, the fabric I0 passes through one or more washers, such as the vat washer 28 through whichthe fabric passes in a sinuous path, the rolls 29 thereof being so driven that the fabric is not subjected to substantial longltdinal tension. The fabric may be dried4 either on the loop drier' shown in Fig. 1 or on a tenter drier designated 30 in which the fabric is subjected to transverse tension. Before passing to the drier, the fabric may be subjected to conventional treatments for bleaching, dyeing and other treatments, such treatments per se forming no part of the present invention. If desired. the-dried or semi-dried fabric may be passed from the tenter patents previously mentioned.

for example, by means of a conventional loop drier shown diagrammatically in Fig. 1 and designated 2|. The dried fabric may be subjected to a conventional preshrinkage treatment as, for example, by subjecting it to one of' the processes described in U. S. Patents Nos. 1,982,720, 1,988,376, 2,021,975, andf2,052 ,948,` as in a Sanforizing range. A In carrying out the process with the apparatus of Fig. 1 the fabric while passing through. the

The process of this invention is capable of many variations. For example the process may be applied to the grey cloth or to the cloth in any condition of manufacture which is compatible with the stabilizing treatment. The clo'th may be dried after a boil-01T, then treated by this process and then dyed, or, alternatively, the cloth l may be boiled off, dyed and then treated with the process of this invention if the dye is re.- 'sistant to the alkali and acid used in the present process. In the event that it is elected to apply lthe process of this inventionl to the cloth in the grey state, the real washer shown in Fig. 1 may be replaced by a boil-olf machine of conventional design. lByway of more detailed illustration, but not by way of limiting the invention, there will be given the following specific example.

ture.

Example y A rayon fabric 40 inches wide, and containing 80% viscose and 20% cellulose acetate fibres spun together, is treated in the grey condition as in the 5 tank I3 of Fig. l with a stabilizing composition comprising 2% alkali soluble cellulose ether dissolved in 98 parts oi a3.% aqueous sodium hydroxide solution maintained ,at 85 E. The fabric is treated for one minute Tree of longitudinal .1

tension while beingmaintained to approximately 39 inches in width by means of the rolls I6. The treated fabric is passed into the tank l containing 5% acetic acid maintained at 140 F.

where the cloth is allowed to remain for about 1 seconds during which time the cellulose ether is coagulated on the yarns. The excess acid is squeezed out of the cloth by rolls l8a and the cloth is passed next into a standard boil-ofi ma;

eter of and to shorten the yarns of the fabric.

.The net result of this is to straighten the filling being treated and subjected to coagulation, washing and drying, the treated textiles may be further subiected to a pre-shrinking operation as on a Sanforizing range with very desirable results.

l In the conventional Sanforizing treatment, the

chine about 60 feet long. The boil-oi! solution o canl be of any conventional formula, for example,

0.5% soap and 0.25% sodium pyrophosphate maintained at 190 to 200 F. The cloth is then washed, bleached and finally dried on the loop drier 2l while free of warpwlse tension. When 25 ilnished to 36 inches in dry width, the dried cloth will have residual shrinkage of between 2 to 3% when subjected to a conventional laundry washing. In comparison with this a similar cloth passed through this entire process, but without 30 treatment with the alkaline solution oi cellulose ether and acid coagulation will show a residual shrinkage upon washing of from '1% to 13%.

Without limiting the invention by any theoretical e lanation, it a ars that when the celluxp ppe 30 ether `on said textile while maintaining said textile losic material has coagulated on the textile, it forms a gel which has a denite shape and dimension and a substantially nxed colloidal struc- After their initial drying, such cellulosic gels appear to be elastic, but exhibitsubstantially no plastic flow so that even after drying and wetting of the treated textiles, the gel tends to revert to its initial shape and dimensions. thus restraining the fabric from stretching or shrinking. It

i'abrics are usually first moistened and then subjected to a mechanical shrinking operation. When the fabric is so moistened, the cellulose co1- loids deposited on the fabric swell and when the pre-shrunk fabric passes over the Sanorizing range and is again dried, the gel tends to assume the structure, shape and dimensions imparted to it by the Sanforizlng operation so that the tex-y tile is stabilized in such pre-shrunk condition.

I claim:

1. Ina process for stabilizing textiles comprising articial hydrophilic lfibres, the steps comprising treating said textiles Iwith an alkaline dispersion of an alkali soluble water insoluble cellulose ether at an elevated temperature at which the alkali present will not adversely affect said artificial bres, and coagulating said cellulose in the desired dimensions.

2. In a process for stabilizing textiles comprising artiiicial hydrophilic libres, the steps comappears also that the alkali plays an important 'role in eilecting the novel results of the present invention in that, when the textile comprises artiilcial bres or filaments which swell in alkali,

the swell ofsuch ilbres causes a shortening of the yarns. Thus, ii' the textile before treating 5 has been subjected during fabrication to warpwise tension, 'the warp yarns will normally be straight, while the filling yarns will show a substantial crinkle and undulation. When swollen by the alkaline stabilizing composition, the swell- 5 ing o! the yarns tends to both enlarae thel diamprising treating said textiles with a dispersion of an alkali-soluble water-insoluble cellulose ether in an alkali having a concentration oi' notv substantially more than 9% and at a temperature of trom '70 F. to 160 F., and'coagulating said cellulose ether on said textile while maintaining said textile in the desired dimensions.

3; In a process :for stabilizing textiles comprising artiilcial hydrophilic libres, the steps comprising treating said textile while free ot tension with an alkaline dispersion ci' an alkali-soluble waterinsoluble cellulose ether at an elevated temperature at which the alkali present will not adversely affect said artificial libres, and coagulating said cellulose ether on said textile while maintaining sald textile in the desired dimensions.

, JAMES A. CLARK.

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