US2700202A - Method of treating tubular knitted fabric - Google Patents

Description

Jan. 25, 1955 F. R. REDMAN ETAI- METHQD oF TREATING TUBULAR KNITTED FABRIC 3 Sheets-Sheet l INVENTONS; FRANK .REDMAN JOHN HAMILTON JACK P, wlLsoN Bfr OZ 20p-0200 Iwzfm Original Filed 001;. 8, 1952 Jam 25, 1955 F. R. REDMAN ETAL 2,700,202

l METHOD OF TREATING r] .llBU..R KNITTED FABRIC Originai Filed Oct. '8, 1952 3 Sheets-Sheet 2 f NORMAUZER- Ewan/:15

3a (FOLDER) (FOLDER) r 5 o l I (FOLDER) 47 f v 5|. 49 F o v 5 a o @j A j o o mvENT FRANK KREDMAN JOHN HAMILTON JACK i? WILSON i Jan. 25, 1955 F. R. REDMAN ETAL METHOD oF TREATING TUB\1LAR KNITTED FABRIC 5 Sheets-Sheet 3 original Filed oct. 8, 1952 INVENTORS: FRANK .REDMAN JOHN HAMILTON BY JACK e WILSON hbwdoryh/wdw METHOD F TREATING .FABRIC nited States Patent Frank R. Redman, Yardley John Hamilton, Oakfordnnd .lackPf'Wilsom-Penn 'Wynne Pa., assignors -to Proctor & Schwartz, inc., Philadelphia, Pa., a conrmration'of Pennsylvania Original napplication (lctober'8,"1952,Seriall No. 313,622,

now Patenti-ilo. 2,684,519,1dated duly-27,1954 Divided and this application July'17, 1953, Serial No. 374,612

Y-z Claims. *,(Cl. zei-18.5)

This invention relates to treatment of tubular knitted fabricswhich -requirernaptfn'ng7 the general obiect offtheinvention being to minimize g or `substantiallyv elnrnnate shrinkage in such-fabrics land also rtoimprove the texture `or `-hand of they fabrics.

This application is a ldivision of1ourjU. ;S. Patent-No.

2,684,519, issued July 27,1954.

It is now recognized inthe ,artethatfshrinkageoffgarments made from tubular knitted fabrics is causedzbyzan unnatural condition of thecfabricrat the-time garments are made therefrom. To explain thisrtubularknitted fahr-ici. is

`stretched lengthwise :or elongated byrthe treatmentsfgto which it issubjected 'subsequentto knitting ofthe fabric and prior tothe cutting thereof inthe;Subsequentmauufacture of garments. lnits stretched .or elongated condition, the .fabric stitches are elongated.lengthwiseandnarrowed widthwise, and they tend fto acquire .sa distorted set. Ordinary treatment of the fabric prior ato .the making of garments therefrom does l.notundoathis distorted set, but the lannderingof garments .does .so due .tothe agitation. to which .the fabric :is subjectedin laundering. The undoing of this distorted ,"fset relieves the stitches yand permitsv them to `return substantially totheir normal-condition, i..-e. .the normal :shape and size that the` stitches; had

immediately after knitting ofnthefabric and prior to treatment thereof. Consequently, the laundering of the garments made from distorted fabricl causes-shrinkage Aof the garments, resulting in shortening and Lwidening :of the garments. lttis nowknown that in orderto minimize or substantially .eliminatel shrinkage of` garments made .from

vtubular-knitted fabrics, it is necessary to restore .the fabric substantially to its normal or naturalcondition ,prior to the making of garments therefrom.

All tubular knittedfabrics, following thefknittingfthereof,- are subjected to so=cal1ed wet processing. which includes scouring, bleaching and dyeing. The fabric is vknitted in lengths of, for example, one hundred yardsand these arefastened together lin succession. As the fabric goes through the wet`processing in continuous rope form, it is subjected to severe tensional foreeslengthwise v:which impart considerable lengthwise stretch-to it, the `degree of vstretch depending upon the type-and weight of the fabric and'also the type and condition of the machinery4 used -in the wet processing. Generally speaking, the fabric will be stretched in .an amount'which is a substantial percentage of its length, within the range of about 8% to 35%. Lightweight'fabrics-will stretch within a range of about 15% to V35 while heavyweight fabrics will stretch Within a range of about 8% to 15%.

After wet processing, tubular knitted fabrics are variouslly treated to condition them for the making of garments,

the treatment depending upon the type and weight ofthe fabric. It was long customary to spread the fabric to a desired widthwhile maintaining it`under tension lengthwise, and then dry and ,sometimes calender the fabric preparatory to the cutting of garments. This practice did nothing to alleviate the stretch or shrinkage and, `in fact, it tended to promote greater shrinkage.

An important development in the treatment of tubular knitted fabric is a treatment known as normalizing which is the subject of U. S.vPatent-No. 2,597,530, issued May 20, 1952,.to Frank R. Redman. The normalizing treatment comprises internally expanding the tubular Yknitted'fabric widthwise, while itpis :free lengthwisefrto 2,700,202 Patented Jan. 25, 1955 2 effect .shortening or ycondensing 'of the ffabric, and permitting the fabric to relax. The widthwise expanslony of .the fabric, while lit vis vfree lengthwise, vundoes the -aboye- .mentioned distorted: -set, and upon relaxing of the fabric the ,knittedstitches thereof return substantially totheir normal size vand-shape, =so that the fabric 1s then restored to its naturalv or normal condition. The normalizing treatment may `-be `carried out either with thefabric dry or with-some degree of moisture present in the fabric. The -word dry,7 as here used and asusedin the appended claims, means that the fabric has only such moisture y.as

kit mayhave absorbed from-the air. Therefcre, by a Vfabric having some .degree of-mo1sture .present therein, we mean a fabric whichhas at least; some-moisture -111I addition to that whichit may absorb Afrom theair. ,'Tihus,.a fabric -which has` just come frornwet pr ce ssing, with the excess `water removed,has` a moisture contentwithin .the range -of about-40% to 85% of the .weightof n,the fabric, in excess 'of ,they dry condition, and .thisis -referredttoas ,a wet fabric. A moist .fabric-is onethathas been-dried and has hadmoisture-,addedina content of `about.,2 to 10% of the weightof=the fabric.

With respectto fabrics which must be napped, ,the napping must be donewhile `the fabric -is in .dry condition, Aand therefore,l it isnecessary to dry. the fabric :preparatory to napping.. The `normalizing Vtreatment ,is useful `in conjuction with all typesandkindsfof tubular knitted fabrics illuding those whichjare to be napped. .lt has Abeen fol-1nd, however, that napping itself -,distorts 'the lfabric and the knitted stitches-thereof .to an -appreciable extentand, therefore, tendsto cause s hrinkageoffgarmentsmade yfrom the fabric.

The ,principal object of the fpresent ,invention-is to provide animprovedprocess'forthe `treatment of tubular `knitted fabrics-.that are-to bevnapped,.to,fthe ends that the finished fabric will have substantially a zero-.zero

.reasons -for providingsuch ytreatmentsequences for -different fabriC,S-.it,is desirable, ,rSt toetzforth the-distinetionfbetweenthe different-fabrics so far -as the presfent inventionis concerned. From the standpoint of treatmentaccording ,to -the present invention, tubular knitted fabrics may be divided into two types or classes, as folows: v

l(.1) Those fabrics which are stretched inthe we tprocessingto a relatively-greatdegree or extent; and

(2) .Those fabrics which are stretched in the-wet processing toa substantially lesser degree ory extent.

The degree or extent. to which ,any tubular knitted fabric willbe `stretched in thewet processing is dependent upon `a number of factors which include the weight or density of the fabric, they stitch construction, the yarn cut and count and the type of `wet processing to which the fabric is subjected. Generally speakinglightweight and medium Weight fabrics will be stretched from about 15% to about 35% of their original length, while heavyweight fabrics `willbe stretched from about 8% to labout 15% of 'their original length. However, as indicated, the amount of ystretch depends upon certainfactors in addition to the weight of the fabric.

As previously mentioned, it is highly desirable to normalize all tubular knitted fabric by the normalizing treatment, includingrtubular,knitted fabrics which require napping and with which the present invention is concerned. Furthermore, it should be noted here that the normalizing treatment Vis more easily carried out with the tubular knitted fabric `in wet condition. However, in the case `of the fabrics of type l) above,i. e. fabrics which'stretch greatlyfinhasbeenfoundthat inthe course of napping -wet processing to a relatively great degree or extent.

such fabrics, the napping tends to stretch the fabric to a very substantial degree. Therefore, if such fabrics are first wet normalized and dried, and are then napped, the napping tends to defeat the purpose of the normalizing in that it puts back into the fabric at least a substantial part of the stretch which was removed by the wet normalizing. Therefore, it is necessary again to normalize the fabric, and this involves undesirable duplication. According to the present invention, this objection is overcome by the treatment sequence indicated in Fig. 1 in which the fabric is normalized only after napping, at which time the fabric is dry, and the dry normalizing is followed by a moisture changing step, as hereinafter specifically described. The treatment sequence of Fig. 1 is claimed in the aforementioned patent.

In the case of the fabrics of type (2) above, if such fabrics are wet normalized and dried and then napped, the napping does not greatly stretch the fabric and does not defeat the purpose of the wet normalizing, although it does impart some stretch to the fabric. According to the present invention, such fabrics are treated according to the sequence indicated in Fig. 2, in which the napping operation is followed by an agitation step, as hereinafter specifically described, which is effective to remove the stretch imparted to the fabric by the napping. The treat* ment sequence of Fig. 2 is claimed herein.

In the treatment of tubular knitted fabrics of type (l) above, as indicated in Fig. l, the fabric is subjected successively to drying in stage 10, napping in stage 11, dry normalizing in stage 12, moisture changing in stage 13 and nish conditioning in stage 14.

In the treatment of tubular knitted fabrics of type (2) above, as indicated in Fig. 2, the fabric is subjected successively to wet normalizing in stage 20, relaxed drying in stage 21, napping in stage 22, agitation in stage 23 and finish conditioning in stage 24.

Figs. 3 to 8 show, diagrammatically, various devices which may be employed in treatment steps or stages of the treatment sequences represented or indicated in Figs. l and 2. For simplicity of illustration, in Figs. 3 to 8 the treatment step or stage illustrated in each instance is depicted as a complete process in itself in which the fabric F is drawn from a truck and is passed through the treatment stage and is then fed to some receiving means, such as a second truck. However, in actual practice of the treatment sequences indicated in Figs. 1 and 2, the overall process could be continuous, and handling of the fabric would be minimized. As far as is possible, therefore, the fabric could be fed from one treatment stage directly into the next treatment stage.

The treatment sequences indicated in Figs. 1 and 2 will now be specifically described, with reference to the specific devices shown in Figs. 3 to 8.

Referring first to the treatment sequence indicated in Fig. 1, as hereinbefore stated, this treatment sequence is utilized for the treatment of tubular knitted fabrics of type (1) above, i. e. fabrics which are stretched in the s the fabric comes from the wet processing, it is first dried in stage preparatory to napping. The drying of the fabric may be carried out in any conventional dryer, although it could be carried out in a relaxation dryer of the character represented in Fig. 7 hereinafter described and shown in U. S. Patent No. 2,597,490, issued May 20, 1952, to A. O. Hurxthal. that relaxation drying is unnecessary because it is irnmaterial whether the fabric is further stretched in the drying operation, since the subsequent normalizing will remove whatever stretch has been imparted to the fabric.

Following the drying of the fabric, it is napped by means of a conventional napping device, as diagrammatically represented in Fig. 3. In the illustration of F1g. 3

`the fabric is shown as being drawn from a truck 25 by nip rolls 26 over an idler roll 27 and over a spreader 2i?. The nip rolls 26 feed the fabric to the napping device represented at 29, from which it is drawn by a roll or drum 3() to a conventional folding device 31 which folds it into the truck 32.

Following the napping operation, the fabric is dry normalized by means of apparatus of the character disclosed in the above-mentioned Redman patent. Fig. 4 shows, diagrammatically, the normalizing operation. In this showing the fabric is drawn from the truck 32 over idler rolls 33 and 34 and'over the normalizing device 35' by vmeans of nip rolls 36 which feed the fabric ontoa The significant point here is iii) lthis is more or less a matter of choice.

'agitation helps to relieve the stress in the stitches.

shown in the above-mentioned Hurxthal patent.

conveyer 37, the latter serving to carry the fabric in relaxed condition to a folding device 38 which folds it into a truck 39. As described in the above-mentioned Redman patent, the normalizing device expands the fabric widthwise, while it is free lengthwise, to effect lengthwise shortening or condensing of the fabric, after which the fabric is relaxed and its stitches return substantially to their normal size and shape. In the arrangement of Fig. 4, the fabric is overfed onto the conveyer 37 by the nip rolls 36, in order to relax the fabric on the conveyer.

The dry normalizing is effective substantially to remove the stretch imparted to the fabric by the wet processing and by the napping, but it has been found that dry normalizing leaves the fabric somewhat stretched in width and that the stitches do not readily assume their normal or natural condition, apparently due to the fact that the fabric is dry. We have discovered that the fabric may be greatly improved, both from the standpoint of widthwise normalization and from the standpoint of texture, by temporarily changing the moisture content of the fabric after the dry normalizing treatment represented in Fig. 4. Moreover, we have discovered that the' same result may be achieved either by adding moisture to the dry fabric or by expelling all of the moisture which is present in the dry fabric to bring about a bone dry condition. Apparently, the act of temporarily changing the moisture content of the fabric relieves the stitches and permits them to assume fully their normal condition, whether the change of moisture content be an increase or a decrease of moisture.

While we do not wish to be bound by any particular theory as to why a temporary change of moisture content of the fabric produces the results above stated, the following is offered as a plausible explanation. It is well known that a change of moisture content of a single fiber or thread, whether the change be an increase or a decrease of moisture, will produce swelling or contraction of the thread. In the case of fabric comprising a multiplicity of fibers or threads forming the yarns which are knitted to form the stitches, a change of moisture content of the fabric, apparently causes the threads to twist tighter or looser, and relieves any stress in the stitches due to effective movement of the yarns caused by swelling or contraction of the constituent fibers or threads which are twisted together and compose the yarn. Therefore, the step of temporarily changing the moisture content of the fabric serves as an adjunct to the dry normalizing by relieving any stress which may remain in the stitches of the fabric after the dry normalizing.

As to the character of the moisture change, that is, whether it is a moisture increase or a moisture decrease, If moisture increase is selected, it may be carried out in any suitable apparatus such as the alternative forms shown in Figs. 5 and 6. In the showing of Fig. 5, the fabric is drawn from the truck 39 by a driven roll or drum 40 which overfeeds the fabric onto a conveyer 41 through a moistening chamber 42. Within the moistening chamber there are water or steam spray jets 43 and 44 directed against the opposite sides of the fabric. The moistened fabric is carried by the conveyer 41 in relaxed condition to a folding device 45 which folds the fabric into a truck 46.

In the alternative showing of Fig. 6, the fabric is drawn from the truck 39 by a driven roll or drum 47 which overfeeds it onto a power-driven conveyer 48. The conveyer carries the fabric between water or steam jets 49 and 50, the conveyer being of foraminous form to permit moistening of both sides of the fabric. The conveyer carries the fabric in relaxed condition to a folding device 51 which folds the fabric into the truck 46.

We have discovered further that better results may be achieved by combining some agitation of the fabric with the change of moisture content thereof. Apparently, tbE agitation is employed in the arrangement of either Fig. 5 or Fig. 6, it may be effected as the fabric is carried along on the conveyer by impinging pressurized air on the fabric from spaced nozzles (not shown).

If it is desired to employ moisture decrease or expulsion, instead of moisture addition, the moisture expulsion may be carried out in a basket dryer of the character In such apparatus the fabric is loosely deposited in basket loops of a basket conveyer, and it is subjected to pressurlzed heated air. In the diagrammaticv showingof Fig. 7, the

basket conveyer is represented at 52. In this showing the fabric is drawn from truck 39 by a power-driven roll or drum 53a and is loosely deposited in the successive basket loops of the moving basket conveyer. As it is carried along by the conveyer, the fabric is subjected to pressurized heated air from ducts 53 and 54 having spaced outlet nozzles 55 and 56. The pressurized air enters the ducts through a common conduit 57 and an air heater 58. In the arrangement shown, the fabric is overfed by the basket conveyer onto a plane conveyer S9 which carries the fabric in relaxed condition to a folding device 60, the latter folding the fabric into the truck 46.

It should be remembered that the fabric is in the dry condition as it leaves the normalizing stage 12 of Fig. 1, i. e. the fabric contains only such moisture as it may have absorbed from the air. The temporary moisture expulsion treatment carried out in the apparatus represented in Fig. 7 serves to drive substantially all of the moisture from the fabric to bring about a bone dry condition thereof. This may be readily achieved in the apparatus of Fig. 7, by using enough pressurized heated air alud by operating the basket conveyor at a proper spec Following the moisture changing step, the fabric is subjected to finish conditioning which is the final operation prior to cutting of the fabric for the making of garments. By finish conditioning, as used here and in the appended claims, we mean folding or rolling of the fabric with or without calendering thereof. In the specific illustration of Fig. 8 the finish conditioning operation is shown as involving calendering and folding of the fabric. In the illustration, the fabric is drawn from the truck 46 by calender rolls 61 over an idler roll 62 and over a spreader 63. From the calender rolls the fabric is drawn by nip rolls 64 over idler rolls 65 and 66 and over a spreader 67. The nip rolls 64 supply the fabric to a driven folding table 68 which may be of conventional form. After being folded on the folding table 68, the fabric is ready for the cutting thereof preparatory to the making of garments.

Referring now to the treatment sequence indicated in Fig. 2, as previously mentioned, this treatment sequence is utilized, according to the present invention, for the treatment of fabrics of type (2) hereinbefore mentioned, i.. e. those fabrics which are stretched in the wet processing to a substantially lesser degree or extent than the fabric of type (l). Generally speaking, tubular knitted fabrics of relatively heavy weight will be among those identified as type (2). However, as previously mentioned, the degree or extent to which a fabric stretches in the wet processing is determined by factors in addition to the weight of the fabric.

The treatment sequence indicated in Fig. 2 is applicable to tubular knitted fabrics of type (2) principally because the napping of such fabrics does not greatly stretch the fabric, although it does impart some stretch thereto. Accordingly, in the treatment of such fabrics it is desirable, first, to normalize the fabric in the wet condition as it comes from the wet processing. The wet normalizing is performed by means of apparatus of the character disclosed in the above-mentioned Redman patent, or as diagrammatically represented in Fig. 4. This normalizing treatmentis identical with that previously described, the only difference being that the fabric is in wet condition instead of being in dry condition. As previously indicated, wet normalizing of a fabric is desirable because the fabric yarns and stitches, when in wet condition, are more responsive to the normalizing treatment, and the stitches are better able to assume their normal or natural condition upon relaxation of the fabric after the widthwise expansion thereof.

Following the wet normalizing step in the treatment sequence of Fig. 2, the fabric is dried in a relaxed condition. This relaxed drying step may be carried out in apparatus of the character disclosed in the above-mentioned Hurxthal patent, or as shown diagrammatically in Fig. 7. In such apparatus the fabric is fed to the basket conveyer and is subjected to the drying action of pressurized heated air impinged against the fabric, as previously described. This drying step, however, is to be distinguished from the moisture expulsion treatment previously described in connection with the moisture changing step in the sequence of Fig. 1. In the relaxed drying step of the sequence of Fig. 2 now being considered, it is desired only to bring about a dry condition of the fabric, i. e. a condition in which the fabric contains only such moisture as it may absorb from the surrounding air.

After relaxed drying, the fabric is napped by means of a conventional napping device such as diagrammatically represented in Fig. 3. As previously mentioned, the napping of fabric of type (2), with which we are here concerned, does not defeat the purpose of the previous wet normalizing of the fabric, but it does impart some stretch to the fabric. With such fabrics, the napping elongates the knitted stitches to some extent but not nearly to the extent that they were elongated in the wetprocessing. Moreover, the napping does not cause the stitches to acquire a distorted se We have discovered that the stretch and distortion produced by napping fabrics' of this type can be substantially eliminated by agitating the fabric after the napping operation. Apparently, the agitation relieves the stitches and permits them to return to their normal condition. Accordingly, as indicated in Fig. 2, the napping step is followed by an agitation step which is effective to eliminate the stretch imparted to the fabric by napping. This agitation step can be carried out in any suitable apparatus, and the agitation may be effected in various ways such as air agitation, mechanical agitation. etc. By way of example, the agitation step may be carried out in an apparatus of the character represented in Fig. 7, using air impingement to eifect the agitation. As drying is not involved, it is unnecessary that the air be heated. As shown in Fig. 7, provision may be made for supplying pressurized unheated air to the ducts 53 and 54 from a conduit 69. An air-flow controlling member or vane 70, pivoted at 71, may be moved to the broken line position to shut olf conduit57 and to open conduit 69. By supplying unheated air at suitable velocity, the fabric may be agitated sufficiently for the intended purpose mentioned above.

Following the agitation step, the fabric s subjected to finish conditioning which is similar to the final step in the treatment sequence of Fig. l as described above.

From the foregoing description it will be seen that the invention provides novel treatment sequence for various tubular knitted fabrics that are to be napped, and the treatment sequence which is applicable in any instance serves to so condition the fabric that the stitches thereof are substantially in their natural or normal condition, thus substantially preventing shrinkage of garments made from the fabric.

It will be understood, of course, that the invention is not limited to the specific disclosure, but is susceptible to such modifications as will occur to those skilled in the art.

We claim:

1. A method of treating tubular knitted fabric as it comes from wet processing, which comprises: internally expanding the wet fabric widthwise while it is sufficiently free lengthwise to permit lengthwise shortening or condensing thereof, then permitting the fabric to relax; drying the fabric in relaxed condition; napping the fabric; agitating the napped fabric; and finish conditioning of the fabric for the cutting thereof in subsequent manufacture of garments.

2. A method of treating tubular knitted fabric as it comes from wet processing, which comprises: internally expanding the wet fabric widthwise while it is sufficiently free lengthwise to permit lengthwise shortening or condensing thereof, then permitting the fabric to relax; dr'ying the fabric in relaxed condition; napping the fabric; agitating the napped fabric: calendering the fabric; and packaging the fabric for the cutting thereof in subsequent manufacture of garments.

References Cited in the le of this patent UNITED STATES PATENTS 2,469,245 Russell May 3, 1949 2,588,624 Evans Mar. 11, 1952 2,589,345 Cohn et al Mar. 18, 1952 2,597,530 Redman May 20, 1952

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