US2972220A - Treatment of fibers - Google Patents

Description

Feb. 21, 1961 J. M. FLAcK ETAL TREATMENT oT FIBERS 2 Sheets-Sheet l Filed Aug. 4, 1955 Feb. 2l, 1961 J. M. FLACK ErAL TREATMENTv OF FIBERS 2 Sheets-Sheet 2 Filed Aug. 4, 1955 United States Patent O TREATMENT OF FIBERS 'James M. Flack, Westford, Mass., Benjamin F. Pulsifer, Nashua, N.H., and James D. Whatley, Cordova, Ala., assgnors to Indian Head Mills, Inc., New York, NX., a corporation of Massachusetts Filed Aug. 4, 1955, Ser. No. 526,508

7 Claims. (Cl. 57-156) This invention relates to a novel method of treating cotton in loose ber form to improve its weaving and spinning properties and to the product which is thereby obtained. The invention relates, in particular, to a method for improving the quality or grade of cotton and for reducing loss in the form of lint waste that normally occurs in the processing of cotton bers.

In the preparation of cotton thread from the staple, cotton bers from the bale are subjected to an opening operation followed by cleaning, lint removal, picking, carding, drawing and spinning. One or more of such processing steps has usually involved the separation of short and immature fibers which have heretofore been considered to be undesirable in a high quality cotton thread because it had been found that, unless the short and immature bers were removed, the spinning of the bers would be impeded and the resulting product would be weak and of inferior quality. On the other hand, raw staple which had a low content of such short or immature bers and which would therefore be subject to less loss during processing would be less plentiful and of high cost.

The invention described herein provides a method for treating cotton in loose ber form so that the short and immature bers need not be removed but remain in the material thereby eecting an economy in the price and quantity of the staple that may be used without impeding the spinning of the bers and without loss of quality in the nished product. Another advantage of the invention is that the resulting product has a quality as evidenced by tensile strength and Micronaire count substantially better than it would otherwise have. The short and irnmature bers are so modified according to the process of the invention that cotton containing such bers may be successfully spun into thread of desirable properties.

Particular advantages of the invention are that the amount of lint waste normally lost in processing untreated cotton is greatly reduced; spinning characteristics of the ber are improved; Micronaire count is substantially increased; and tensile strength is increased.

According to the method of the invention, loose cotton bers are treated with a cold, strong causticizing agent to swell the bers Without producing substantial gelatinization thereof, while holding the bers under tension and surface frictional restraint to retard the normal contraction and curling thereof that would occur but for the tension. The tension is applied until the causticizing agent is removed from the bers. The bers treated by the method described herein have improved properties from the standpoint of maturity (measured by standard Micronaire tests) and spinability into yarns or threads. Fiber loss in the form of lint waste is lower. The improved properties are rthought to be due to the fact that the immature bers are swollen thereby improving maturity as measured by the Micronaire count.

The cotton subjected to causticizing treatment according to the invention may be wetted raw unscoured cotton; or scoured and wetted; or scoured, bleached and wetted.

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If desired, the causticizing treatment may be carried out on dry bers. However, it is preferred to moisten the bers prior to causticizing treatment. More marked and rapid effects are produced by treating scoured, bleached and wetted fibers.

The length of the bers is in the textile ber range, that is, a major portion of the bers are of length of at least one-half inch, preferably at least of an inch and ranging up to 11/2 inches or greater length.

Prior to the causticizing or wetting and causticizing treatment, the bers may be processed according to usual procedures. The raw cotton bers are taken from the bale and processed through an opening and cleaning line that will open and flulf up the bers, clean out non-lint Waste without removing immature bers, and form a mat suitable for chemical treatment. Any suitable means may be employed for initially assembling the bers. For instance, bers from the bale after opening, cleaning and lap forming are preferably subjected to a parallelizing treatment, as described in more detail hereinafter, and then the causticizing or wetting plus causticizing process. The weight of the Web or lap of dry assembled bers subjected to causticization is preferably 4 to about l0 ounces for a one yard long section of 40 inch wide web. r[The web in the weight range indicated is sufficiently light so as not to interfere with the operation of the means described more fully hereinafter which tends to maintain the bers under tension by fricticnal restraint during the treatment with causticizing agent. On the other hand, the web is not so heavy that the innermost bers do not become suliiciently wetted nor suiciently subjected to the causticizing agent. The preferred maximum web weight is about 14 ounces.

The temperature and time of treatment and concentration of caustic are interrelated and controlled at levels which will produce the desired swelling and controlled curling of the bers without producing substantial gelatinization thereof. Excessive gelatinization would result in an undesirable welding or fusion of bers to each other. Generally, the concentration of caustic should be at least 8% and less than 32% NaOH and the temperatures should be from just above the freezing point 4of the solution to F. Preferably, such solutions are used in concentration in the range 20-25% at temperatures of llt-20 F. The time of contact between the bers and the causticizing agent is such as to wet the bers thoroughly and permit the desired swelling thereof. The time of treatment may be within the range of about 30 seconds to 2 minutes, and, preferably, within the range or" 30 seconds to l minute.

The means and the methods for retaining the bers under frictional restraint to produce the controlled tension which is an essential element of the invention will be described in greater detail in connection with the graphical description of the invention appearing in the attached Figures 1 and 2.

Figure 1 is a oW sheet outlining the operating steps, including those which precede and those which follow the causticizing treatment;

Figure 2 is an illustration, largely schematic, of apparatus for carrying out the method of the invention.

In Figure 1, reference number 10 designates an opening apparatus which loosens the bers as they come from the bale. After opening, the bers pass to a cleaner 11 which serves to separate from the cotton foreign material other than lint. Suitable cleaners are the gin cleaner or superjet cleaner with a condenser.

After opening and cleaning, the bers pass to the blending reserve, evener and picker, designated generally at 12. The apparatus is operated according to conventional procedure except that the grids of the picker are closed so as to retain substantially all of the shorter bers. The

picker lap may -be introduced directly to the chemical treatment operation illustrated more fully in Figure 2, or may receive an optional but preferably supplemental treatment,'for parallelization of the bers, as shown at 15, prior to the causticizing step.V Parallelizing of the bers may be effected by carding or garneting plus drawing or similar methods which will place the bers in the form of a sheet or web at least partly but not necessarily completely oriented in one direction, most suitably in the direction of the length of the web.

After the chemical treatment described more fully below, the bers are dried, suitably in a circulated hot air oven or by infrared radiation, as shown at 17, and opened again at 18 to disperse the bers suitably in a gin type opener. The opened bers pass through a blending reserve, evener and picker with the grids closed, as shown at 20, and then through conventional equipment such as carding, drawing, spinning and weaving machines at 21.

Referring to Figure 2 for the details of the wetting and causticizing treatments, reference number 25 designates a roll of specially prepared cotton lap. The lap 26 is unwound from roll 25 by being drawn continuously between the feed rolls 27. Screen belts 30 and 31 above and below the lap, respectively, pick up the lap 26. Screen belt Si) is fed over a series of rollers shown in the drawing above the lap, and screen belt 31 is fed from a series of rollers, some of which are in wetting tank 32 disposed below the lap. Screen belts 30 and 31 converge and come into direct contact with the top and bottom surfaces of the lap so as to carry it down into wetting out solution 35 maintained in tank 32. Belts 30, 31 carry the bers down into solution 35 and around guide rolls 36 which allow the bers to remain in the liquid until the bers are thoroughly wetted.

The ber lap leaves the screen belts 30, 31 at guide rolls 49 and is fed between squeeze rolls 41. Rolls 41 are driven by suitable means, not shown, as are feed rolls 27 and guide rolls 36 so that the surface speed of screens 3@ and 31 will lbe the same as the surface speed of squeeze rolls 41. If desired, however, the surface speed of screens 30 and 31, as controlled by the cooperating guide rolls, may be varied in relation to the surface speed of squeeze rolls 41.

After leaving squeeze rolls 41, the bers are again picked up by a pair of screen belts 42 and 45 carried and driven by a series of guide rolls 46 and 47, respectively. Screen belts 42, 45 carry the bers down into causticizing solution 50 in the tank 51. The lower screen belt 45 passes around weighted guide roll 72 which keeps the screen tight. The top screen belt 42 passes around weighted guide roll 71 which keeps this screen tight and the ber lap 26 under desired controlled compression between the two screens. The composite screen-ber web-screen laminate passes around synchronized rollers 55 within the tank.

An important feature of the invention referred to hereinabove is that screens 42 and 45 compress the lap 26 so that the individual bers are retained in frictional restraint largely through ber to ber contact between the wires of the screen mesh and thereby retained under controlled tension to prevent unrestrained shrinkage and curling. The desired conditions of frictional restraint and tension are maintained while the laminate passes through solution 50 in tank 51. Solution 50 is maintained at the desired temperature by a refrigeration apparatus shown in the drawing below tank 51. Solution 56 overows dam 56 and is withdrawn through piping 57 to pump 6i). In the cooler 61, the temperature of the solution is reduced by indirect heat interchange with refrigerant entering the cooler at 62 and leaving at 65, and is then returned to tank 51 through piping 66.

The length of tank 51 and number of cylinders 55 within the tank and the rate of travel of the screens and web through the tank `are suicient to provide the desired 4 time of contact between causticizing agent 50 and web 26 at the temperature of solution 50.

The endless screen belts 42 and 45 are separated at guide rolls 67 and the separated web is fed between squeeze rolls 70 which squeeze out the excess caustic liquid and return it to tank 51.

After the ber lap leaves squeeze rolls 70, it is again picked up by a pair of endless screen belts and 76 which carry the cotton lap 26, still under compression, through the rst wash box 77. In this box there is a continuous flow of water at about 100 F through manifolds and jets Si) which impinge directly on the screens and bers to wash out caustic therefrom. Wash tank 77, and all of the succeeding tanks, have a continuous inflow and outflow of liquid and a liquid level maintained therein by means not shown. After the first wash, the lap leaves the screen belts at rolls 81 and is immediately picked up by squeeze rolls 82 and fed again between a pair of continuous screen belts 85 and 86 and passed through the second washing tank 87. The web leaves belts 85 and 86 at 9i) and is passed between the squeeze rolls 91. It is again picked up by screen belts 92 and 95 and passed through tank 96 where it is treated with a diluted solution of acetic acid, sulphuric acid or sodium bicarbonate to neutralize any caustic which still remains in the bers.

The ber lap 26 is then carried through squeeze rolls 100 and thence through Wash tanks 101 and 102 between endless cooperating screen belts in each case and through a squeeze roll after each wash. In each tank there is a substantial ow of hot water through piping, not shown in the drawing, for the purpose of washing out residual amounts of chemicals which may 'remain in the bers. Finally, the cotton lap 26 reaches tank 105 where it is again treated with a liquid between parallel cooperating endless belt screens. The liquid in tank is a solution or an emulsion 196 of a ber lubricant. It is nally squeezed between rolls 107 and passes along to a raw stock dryer, not shown in the drawing.

The mesh of the screen is of some importance in obtaining successful results according to the invention. The screen mesh generally must be sufciently open to permit passage of the causticizing liquid and thorough wetting and treatment of all the bers. On the other hand, it must be sufciently ne to retain the bers under frictional restraint and controlled tension so as to retard and control the extent of shrinkage of the bers during causticizing. The mesh also must be suiciently ne to prevent excessive loss of small bers through the screen. Screens having four meshes to the inch have been used successfully laccording to the method of the invention. Generally, the screen opening may be about Jy inch to as much as about 1A inch without resulting in appreciable loss of the shorter bers and without sacricing desired frictional restraint of ythe bers during causticization.

Following is an example of one mode of carrying out the process of the invention and of manufacturing the product of the invention.

Example A 14 ounce picker lap of loose cotton bers, which had been opened from the bale, cleaned and processed through the picker, was placed between two 1A inch mesh screens, pressed together and treated in the following manner:

l) immersed in a cold aqueous solution of two pounds of Kwik Wet wetting agent (produced by Edwal Scientic Products Company) per 50 gallons of water for 10 seconds. The excess water was then squeezed out by running the screens yand the web through rubber covered squeeze rolls under pressure. Other wetting agents may be substituted for the Kwik Wet.

(2) immersed in an aqueous sodium hydroxide solution (50 gallons) 48 Twaddell at 20 F. The caustic solution contained 4 pounds, 6 ounces of Dypenol No. 88 wetting agent (produced by Dexter Chemical Corp).

The initial immersion period was 5 seconds after which the 'screens and web were passed between rubber covered squeeze rolls under pressure to squeeze out excess caustic. About ten seconds after removing the web from the caustic bath in the rst immersion period, the web was submerged for a second immersion period in the same caustic and held there for 35 seconds. After the second immersion period, excess caustic was squeezed out between rolls as before. The total time of contact of the bers with caustic was 50 seconds. Other types of wetting agents suitable for use as `aqueous solutions may be substituted for the Dypenol No. 88.

(3) Washed in running water at 160 F. for ten seconds and thereafter again squeezed between rolls under pressure.

(4) Washed in running water at 160 F. for ten seconds and compressed as before.

(5) lmmersed in an aqueous solution of 5 pounds sodium bicarbonate per 50 gallons of water at a temperature near boiling for l0 seconds and thereafter compressed between rolls under pressure to remove excess solution. Sodium bicarbonate may be replaced by acetic acid or sulphuric acid (dilute in each case) for the same purpose, i.e., the removal of residual amounts of sodium hydroxide which may be retained by the bers.

(6) Washed in running water at 160 F. until all alkali was removed from the ber. At the end of this Washing period, the pH of the bers was 7.0 to 7.2.

(7) lmmersed in an aqueous solution or emulsion of a ber lubricant of a type known in the textile ber cld. The amount of lubricant deposit on the ber is not over 0.2 part of 1% based on the weight of the dry ber. After immersion, the excess lubricant is removed by squeezing as before.

(8) The screens are removed from the ber web and the bers passed through a hot air type drier to dry the bers.

(9) The caustic treated and dried bers are processed in conventional gin type opener and picker followed by usual mill processes, i.e., carding, Ydrawing and spinning. The neness of the treated ber, as determined by Micronaire measurement, was 3.8 as compared with a value of 2.5 determined by measurement of the neness of untreated ber. This reflects an increase in coarseness of the ber of about 50% since the higher reading on the Micronaire reects a lower degree of neness.

Although specic embodiments of the invention have been described herein, it will be apparent to those skilled in the art that the invention contemplates many modications and equivalents. Accordingly, it is intended to include within the scope of the appended claims all modications and equivalents of the invention.

We claim:

1. The method of treating loose unwoven cotton bers containing immature bers which comprises compressing a web of said bers between parallel screens to provide surface frictional restraint to prevent normal shrinkage and curling of said bers during treatment with caustic cellulose swelling agent, treating said web while it is compressed between said screens with a strong caustic cellulose swelling agent of sufficient strength to produce chemical swelling thereof at such temperature and for such duration as to swell said bers without substantial gelatinization thereof, the strength of said agent being suicient under said conditions of temperature and duration of treatment to produce shrinkage and curling of said bers in the absence of said frictional restraint, thereby to increase the measured maturity of the nished ber web, removing the caustic cellulose swelling agent from said bers while said bers are still held by surface frictional restraint, removing said bers from said screens thereby to obtain a Web which can be processed into a thread, orienting the treated bers in said web for spinning and spinning said oriented bers into a thread.

2. The method of claim 1 in which the dry weight of the ber web is in the range of approximately 4 to 14 ounces for a one yard length of 40 inch Wide web.

3. The method according to claim 1 in which the cellulose swelling agent is an aqueous NaOH solution of concentration in the range of approximately 8-32% and temperature in the range from but not including the freezing point of the solution to approximately F.

4. The method of claim 1 in which the bers are prewetted with water before they are treated with cellulose swelling agent.

5. A thread prepared by spinning bers produced by the method of claim 1.

6. In the method of preparing a cotton web suitable for drawing and spinning into a thread comprising the steps of opening, cleaning, picking and carding the bers, the improvement which comprises retaining in the ber mass the short and the immature fibers normally removed before spinning, compressing said bers at a stage in the operation subsequent to the cleaning stage in the form of a web between parallel screens to provide surface frictional restraint to prevent normal shrinkage and curling of said bers during treatment with caustic cellulose swelling agent, treating said compressed web with a strong caustic cellulose swelling agent of sufficient strength to produce chemical swelling thereof at such temperature and for such duration as to swell said bers without substantial gelatinization thereof, the strength of said agent being suicient under said conditions of temperature and duration of treatment to produce shrinkage and curling of said bers in the absence of said frictional restraint, thereby to increase the measured maturity of the nished ber web, removing said caustic cellulose swelling agent from said bers while said bers are still compressed between said screens, removing said bers from said screens thereby to obtain a web which may be processed into a thread of satisfactory quality containing said short and said immature bers, orienting the treated bers in said web for spinning, and spinning said oriented bers into a thread.

7. The method described in claim 1 wherein the neness of said loose unwoven cotton bers containing immature bers as measured by Micronaire count is about 2.5.

References Cited in the le of this patent UNITED STATES PATENTS 1,626,766 Tompkins May 3, 1927 1,757,755 Hahn May 6, 1930 1,757,756 Schwartz May 6, 1930 1,757,757 Schwartz May 6, 1930 1,791,248 Schwartz Feb. 3, 1931 2,528,793 Secrist Nov. 7, 1950 2,552,078 Williams May 8, 1951 FOREIGN PATENTS 17,397 Great Britain A D. 1897 443,888 Great Britain Dec. 8, 1934 OTHER REFERENCES Textile Research Journal, February 1954, pp. 156- UNITED STATES PATENT OEEICE CERTIFICATIN 0F CORRECTION Patent No. 2,972,220 February 21, 1961 James M. Fleck et a1.

It is hereby certified that err-or appers n the above numbered patent requiring correction and that the said Letters Patent should read as corrected below'.

Column 6, list of references cited, under "UNITED STATES PATENTS", add the following:

2,774,126 Secrist Dec. 18, 1956 signed and sealed this 11th day of July. 1961.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents

Claims (1)

1. 6. IN THE METHOD OF PREPARING A COTTON WEB SUITABLE FOR DRAWING AND SPINNING INTO A THREAD COMPRISING THE STEPS OF OPENING, CLEANING, PICKING AND CARDING THE FIBERS, THE IMPROVEMENT WHICH COMPRISES RETAINING IN THE FIBER MASS THE SHORT AND THE IMMATURE FIBERS NORMALLY REMOVED BEFORE SPINNING, COMPRESSING SAID FIBERS AT A STAGE IN THE OPERATION SUBSEQUENT TO THE CLEANING STAGE IN THE FORM OF A WEB BETWEEN PARALLEL SCREENS TO PROVIDE SURFACE FRICTIONAL RESTRAINT TO PREVENT NORMAL SHRINKAGE AND CURLING OF SAID FIBERS DURING TREATMENT WITH CAUSTIC CELLULOSE SWELLING AGENT, TREATING SAID COMPRESSED WEB WITH A STRONG CAUSTIC CELLULOSE SWELLING AGENT OF SUFFICIENT STRENGTH TO PRODUCE CHEMICAL SWELLING THEREOF AT SUCH TEMPERATURE AND FOR SUCH DURATION AS TO SWELL SAID FIBERS WITHOUT SUBSTANTIAL GELATINIZATION THEREOF, THE STRENGTH OF SAID AGENT BEING SUFFICIENT UNDER SAID CONDITIONS OF TEMPERATURE AND DURATION OF TREATMENT TO PRODUCE SHRINKAGE AND CURLING OF SAID FIBERS IN THE ABSENCE OF SAID FRICTIONAL RESTRAINT, THEREBY TO INCREASE THE MEASURED MATURITY OF THE FINISHED FIBER WEB, REMOVING SAID CAUSTIC CELLULOSE SWELLING AGENT FROM SAID FIBERS WHILE SAID FIBERS ARE STILL COMPRESSED BETWEEN SAID SCREENS, REMOVING SAID FIBERS FROM SAID SCREENS THEREBY TO OBTAIN A WEB WHICH MAY BE PROCESSED INTO A THREAD OF SATISFACTORY QUALITY CONTAINING SAID SHORT AND SAID IMMATURE FIBERS, ORIENTING THE TREATED FIBERS IN SAID WEB FOR SPINNING, AND SPINNING SAID ORIENTED FIBERS INTO A THREAD.

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