KR20050085305A - Mercerisation of cellulosic fibers - Google Patents

Abstract

A process for mercerising unconstrained cellulosic fibres comprises transporting the fibres along a transit path through a mercerising zone in which the fibres are contacted with a mercerising liquid, followed by a rinsing zone, in which the fibres are rinsed, wherein the unconstrained cellulosic fibres are held to prevent longitudinal shrinkage during transportation through both zones. The fibres, such as cotton fibres in sliver form, may be held by being pressed between a pair of belts through the zones. Apparatus for conducting the process contains a mercerising zone and a rinsing zone, and a conveyor comprising a pair of surfaces such as belt surfaces for holding the fibres to prevent shrinkage. The belts may be slightly elastic and under tension to slightly stretch the fibres. The belts wind around rollers separated a short distance apart to maintain tension on the belt and on the fibres therebetween.

Description

Mercerization of cellulose fibers {MERCERISATION OF CELLULOSIC FIBERS}

The present invention relates to a method and apparatus for mercerizing free cellulose fibers.

The beneficial effect of treating cotton with a concentrated solution of various reagents was described in John Mercer's British Patent 13,296 in 1850. In particular, he notes that treating cotton fabrics with sodium or potassium hydroxide followed by thorough cleaning results in shrinkage and thickening similar to those obtained when milling wool fabrics. He also noted that after this treatment the tensile strength is increased and the affinity for the dye is improved.

The original method developed by Mercer improves the strength of cotton fabrics, but the fabric becomes thicker and denser due to shrinkage. In addition, the treatment resulted in poor "handling" or gloss of the fabric.

In 1890, this method, now known as mercerization, was first described in Lowe's British Patent 4552. Mercerization is a variation on the original method developed by Mercer, in which cotton fabrics or spun yarns are treated in a stretched state with mercerizing agents (usually sodium hydroxide) and then washed to remove the formulation. Lowe found that shrinkage of cotton fabrics or yarns can be prevented by maintaining tension in the cotton fabrics or yarns during the treatment and cleaning steps. Another important effect discovered by Lowe was the development of a very high degree of gloss. Other effects previously found by Mercer, such as increased strength and improved affinity for dyes, have also been obtained by this method.

The most commonly practiced mercerization method at present is that an impregnated stretched cotton yarn or fabric is impregnated with a concentrated aqueous solution of sodium hydroxide (or less commonly another mercerized liquor), followed by washing with water and any alkali remaining on the washed side. Neutralizing with dilute acid. The strong swelling action of sodium hydroxide (or other mercerized liquor) has a pronounced effect on the structure and properties of cellulose. Vortex present in the raw cotton fibers is removed and their shape is changed from a flat ribbon structure to a smoother cylinder. The effect of mercerized liquor in cellulose swelling is that most of the central cavity (lumen) present on the surface disappears and the fiber material fills the entire cross section. Original cotton contains both crystalline and amorphous cellulose, and mercerization increases the proportion of amorphous material to the fiber. Mercerization is also

ㆍ Color yield at predetermined dye concentration

ㆍ Dye Coverage of Immature Fibers

ㆍ chemical reactivity

ㆍ tensile strength

ㆍ Maintain strength after application of finishing materials that do not require maintenance

ㆍ Gloss

Improves surface properties such as

There was no idea that the mercerization benefits could be obtained from cotton before the cotton was assembled into yarns or fabrics.

The length of the cotton fibers can vary from less than 0.5 inches to about 2 inches but is approximately 1 inch long. Until the fibers were aligned and spun into spun yarn form, it was not thought that the assembly of fibers such as card yarn, sliver and roving could be stretched by pulling on one end of the assembly. For example, if one side of the cotton sliver is pulled, the cotton fibers will slide together and will not be stretched individually. Thus, cotton is mercerized in the form of woven or spun yarns.

Applicants have also found that mercerizing cotton in the form of yarns or textiles is less complete than previously thought. Highly concentrated sodium hydroxide fluids are too viscous at low temperatures to completely wet all fibers. This is due to the constraints imposed on the fibers by yarn twist and weaving the fabric. If alkali is improperly penetrated, only the outer layer of fiber is mercerized and the fibers inside the yarn can be improperly treated. It is often the case that exposed surfaces, especially the free ends of the fibers, are better treated than fibers embedded deep inside the yarn. Although superficially mercerized, darkly dyed colors are unevenly dyed, causing a problem of "frosting" due to discoloration or subsequent wear of the surface during subsequent washing.

It is therefore an object of the present invention to provide an alternative method of mercerizing cellulose fibers. Preferably, it should be a method that can be carried out continuously and provides all the benefits of tension mercerisation, including development of gloss and maintenance of fiber length.

Summary of the Invention

The present invention relates to a mercer of free cellulose fibers comprising the step of transporting the free cellulose fibers along a passage through the mercerization zone for contacting the free cellulose fibers with the mercuring liquor, and then through the cleaning zone for cleaning the free cellulose fibers. And a free cellulose fiber in which longitudinal shrinkage is prevented while being transported through both zones.

As used herein, "free" cellulose fiber refers to oriented or unoriented cellulosic fibers that are not spun or twisted to the extent that they form a spun yarn. Thus, the term includes raw fibers, card fibers, slivers, and rovings, and does not include yarns and fabrics.

As used herein, "cellulose fiber" is used in the broadest sense and includes cotton yarn, flax, viscose and combinations thereof.

The fibers must remain in the passage between each of the mercerization and cleaning steps and between these two steps. If the fiber is maintained to prevent shrinkage through the passage after the mercerization step leading to the cleaning step, the fiber will shrink upon release of the holding force. To regain the original fiber length, you will need to redraw the fiber. For this reason, as long as the fibers are not redrawn before cleaning, the fibers are ideally maintained to maintain the fiber length during the entire sequence of mercerization and subsequent cleaning steps. Once most of the mercerized liquor is removed in the rinse step, the holding or tensile force will flow out, for example, without adverse conditions in the acid neutralization step after the rinsing step.

Free cellulose fibers are maintained by being compressed between two surfaces as they travel along the passage path. In practice, it is desirable to transport along a pass path between a pair of belts and to squeeze together at several locations through the pass path. The belt should be under a tension sufficient to maintain the compressive force on the fiber to hold the fiber firmly and prevent longitudinal shrinkage.

Applicants have found that good results are obtained when the fibers are stretched (when under stretch tension) during transport through the mercerization zone and the cleaning zone. Elongation is preferably about 4% or less. Elongation above 4% can reduce fiber strength and is therefore preferably avoided. Stretching of the fibers in both zones can be achieved using a weakly elastic belt placed under tension through the mercerization and cleaning zones. In this arrangement the fibers will be stretched in the direction of motion of the belt, so the free cellulose fibers are preferably oriented. The free cellulose fibers are preferably in the form of card yarns, slivers or rovings.

The belt may be made of any suitable material that withstands the action of mercerized liquor. Various polymer materials such as polyesters are particularly suitable for this purpose. The belt may be in any suitable form or structure. For example, the belt can be woven, nonwoven, mesh, perforated, nonperforated, or the like.

Preferably, the passage path has nip rollers at the beginning and end of the passage path. Oriented free cellulose fibers can be introduced into the process between two belts in the first portion of the nip roller. As a result, when the belt is under tension and somewhat elastic, the fibers are somewhat stretched due to the belt as it enters the process.

The belt preferably passes through the guide means at a number of points along the passage path. Applicants note that in order to obtain optimum efficiency in preventing the fiber from slipping between the belts, the straight path length between the points where the belt contacts the guide means must be within or below the average length of the cellulose fibers. Found. For example, for cotton fibers having an average length of about 1 inch (2.5 centimeters), the straight path length should be less than 2.8 cm, preferably 2.5 cm or less.

Since the guide means can be any suitable structure that serves to guide the belt, the term includes surfaces, rods, rollers and the like. Preferably, the guide means is a roller. The diameter of the roller is less important than the path length between the rollers, but small diameter rollers are preferred. It may be advantageous that the diameter of the roller is less than twice the average length of the fibers to be treated. More preferably, it is less than 1.5 times the average length of the fibers to be treated, most preferably less than or equal to the average fiber length.

The passing path may be of any design, but is preferably a bypass path wound around the roller. More preferably, there are approximately equal numbers of left and right curves around the rollers in the passage path.

In addition to being at the beginning and end of the passage path, additional nip rollers may be provided. For example, a nip roller may be provided in the area between the mercerization zone and the cleaning zone to squeeze excess mercuring fluid out of the fiber and belt.

The belt can be driven by any suitable means. For example, the nip roller at the distal end of the passageway can be formed as a pad mangle pulling the belt through the passageway.

The mercerized solution is preferably contained in a mercerized bath, and the cleaning liquid is contained in a cleaning bath.

Any suitable mercerized solution can be used in the method of the present invention. However, it is preferable that a mercerized liquid is alkali. More preferably, the alkali is a concentrated solution of sodium or potassium hydroxide. Appropriate alkali concentrations are known in the art. Preferably the alkali concentration is 15-30% M / V (grams per 100 ml) or 35-55 ° Tw (Twaddell degree-determination of specific gravity used in the art to which this invention belongs). More preferably, the concentration is about 20-22% or about 40 ° Tw. Alternative mercerates may include strong acids (eg sulfuric acid or phosphoric acid) zinc chloride, calcium chloride, and the like.

Preferably, the mercer solution also includes a humectant. Wetting agents are particularly useful in situations where the mercer liquor comes into contact with the fibers at low temperatures without the first higher temperature step. Suitable wetting agents (ie, those which are stable in concentrated alkaline solutions) are known in the art.

The cleaning liquid is preferably water, but may be any other liquid having a pH lower than the pH of the mercuring solution when the mercuring solution is alkali.

Cellulose fibers can be transported through additional zones after cleaning. For example, cellulose fibers may be transported through a neutralization zone where the cellulose fibers are neutralized with a neutralizer. The neutralization liquid can be, for example, dilute acid.

The present invention also provides

(i) mercerization zone;

(ii) the washing zone after the mercerization zone;

(iii) a conveyor comprising a pair of surfaces for holding the fibers such that longitudinal shrinkage is prevented during transport of the free cellulose fibers along the passage path through the mercerization zone and the cleaning zone;

(iv) drive means for driving the conveyor; And

(v) pressing means for holding the free cellulose fibers so as to compress the conveyor surfaces together in the mercerization zone and the cleaning zone, thereby preventing longitudinal shrinkage of the fibers passing through the zone;

It provides a mercerizing apparatus of free cellulose fibers, comprising.

Preferably, the apparatus further comprises a neutralization zone after the cleaning zone. As an example, any other treatment zones may be included in the device, including staining zones.

The conveyor is formed to maintain free cellulose fibers so that longitudinal shrinkage is prevented through the mercerization zone, the cleaning zone and the passage between these two zones. However, there is no need to keep the fibers during transportation through the neutralization zone.

Preferably, the conveyor includes a pair of belts. The belt is preferably under tension so that the compressive force is maintained on the fiber during use to hold the fiber firmly, thereby preventing longitudinal shrinkage. For the reasons described above, it is preferred that the belt is somewhat elastic such that in use the assembly of aligned free cellulose fibers supplied between the belts is subjected to stretching by the belt in the mercerization zone and the cleaning zone. Another aspect of the belt is disclosed earlier.

The pressurization means comprises at least two pairs of nip rollers, a pair of nip rollers positioned at the end of the mercerization zone and squeezing excess mercuring liquor and another pair of nip rollers positioned at or after the end of the cleaning zone. It is preferable. The nip roller pair should position the belt under tension in the mercerization zone and the cleaning zone.

The straight line distance ("path length") between the points where the belt contacts the pressing means along the passage path is preferably within or below the average length of the cellulose fibers to be treated in the device. The path length is preferably less than 2.8 cm, more preferably 2.5 cm or less.

The pressurizing means preferably comprises a plurality of rollers located along the passage path in the mercerization zone and the cleaning zone. The diameter of the rollers is preferably less than twice the average length of the fibers to be treated in the apparatus, more preferably less than 1.5 times and most preferably below the average fiber length.

The passing path is preferably a bypass path wound around the roller, which has approximately equal left curves and right curves around the roller.

The drive means is preferably in the form of a mangle located at the distal end or downstream of the passage path. The drive means may consist of the last pair of nip rollers located at the distal end of the passage path and having the dual effect of squeezing the fibers.

The apparatus may comprise additional parts, for example additional nip rollers for controlling the transport of the mercerized liquor and the belt through the cleaning and neutralizing liquor.

The mercerization zone preferably comprises a mercerization tank for containing the mercerizing solution, the cleaning zone includes a cleaning tank for receiving the cleaning liquid, and the neutralization zone (if any) comprises a neutralizing tank for receiving the neutralizing liquid. do. The neutralization liquid can be, for example, dilute acid.

As will be appreciated by those skilled in the art, the disclosed device can be used in any other method of treating fibers, including cellulose fibers and non-cellulose fibers (including wool), where it is desired to retain the fibers to prevent shrinkage during treatment. Thus, the present invention more broadly

Treatment zone;

A conveyor comprising a pair of surfaces for holding the fibers to be treated such that shrinkage of material through the treatment zone is prevented;

Drive means for driving the conveyor; And

Pressing means for holding the fibers together to compress the surface of the conveyor to prevent the shrinkage of the fibers

It relates to a fiber processing apparatus comprising a.

Examples of other treatment zones are fiber dyeing zones, fiber alkali treatment zones without mercerization and the like.

Other features of the device are as described above.

The present invention will be further described with reference to the accompanying drawings.

1 is a schematic diagram of a mercerizing device according to a preferred embodiment of the present invention.

FIG. 2 is a photograph taken through a scanning electron microscope of a cross section of cotton fibers before and after treatment in the apparatus of FIG. 1. FIG.

3 is a photograph of the side shape of the cotton fiber of FIG. 2 before and after treatment with a scanning transfer microscope.

1 schematically shows a device according to a preferred embodiment of the invention.

The mercerizing apparatus of free cellulose fibers according to a preferred embodiment as shown in FIG. 1 comprises a first bath 10 containing mercerizing solution, a second bath 12 containing cleaning liquid, and a passage above the baths. A pair of housing transport belts including an upper belt 14 having a revolving loop and a lower belt 16 having a revolving loop passing under the jaws, and nip rollers 18, 20, 22 are applied by pressing force It comprises a series of rollers including guide rollers 24a-k for pressing the belt together between the rollers 18 and 22. The nip roller 22 is configured as a pad mangle that drives the belt in the direction indicated by the arrow.

The belts 14 and 16 are made of a material (polyester) that withstands the mercerized liquor contained in the first bath 10 and is somewhat elastic. The thickness of the belt is approximately 1 mm, but different thickness belts may be used. The belt is made so that the mercerized liquor used in the process can penetrate the sliver and the cleaning liquid can completely clean the sliver. The belt is driven through a passage path leading from the nip roller 18 to the nip roller 22. The passage of the belt passes through the first jaw 10 and the first jaw, passes through the second jaw 12 and continues in the advancing direction of the belts 14 and 16.

The path of passage of the belt is followed by winding around a series of closely spaced rollers 20 and 24a-k of small diameter. The diameter of the roller of the preferred embodiment shown is 5 cm. This is appropriate for cellulose fibers having an average length of about 2.5 cm. The diameter of the roller can be adjusted. The straight path length of the belt between adjacent rollers is measured between the points where adjacent rollers contact. The straight path length is closer to or less than the average fiber length (2.5 cm in this case). In the preferred embodiment shown, the straight path length between adjacent rollers ranges from 2.8 cm to 0 (for nip rollers). The distance between the rollers can also be adjusted.

The rollers are arranged such that the belt follows a bypass path through the mercerization tank and the cleaning tank having approximately equal left curves and right curves. Of course, other roller arrangements are possible.

Preferably free cellulose fibers in the form of one or more slivers 26 are fed between the two belts from the nip roller 18 to the nip roller 22. The sliver fibers are aligned in the direction of movement of the belt and in the direction of feeding the sliver into the apparatus (arrow A).

The pad mangle 22 pulls the belt along the passage path and exerts a tension on the belt between the pad mangle and the nip roller 18. When the belt is somewhat elastic, the belt is stretched starting with the nip roller 18. The inlet sliver 26 supplied between the belts at the nip roller 18 is compressed to be sufficiently secured between the belts so that the shrinkage of the fiber is prevented as the fiber passes through the passageway. The sliver will squeeze slightly due to the compression of the sliver. If there are several strands of sliver fed to the device over the width of the belt, the slivers are suitably spaced adjacent to each other in a single layer. As the sliver spreads, there may be some overlap between the compression edges of adjacent slivers.

The belt is somewhat stretched at the beginning of the passage path at the nip roller 18, so is the fiber between the belts. The elongation of the fiber is about 1 to 2%. The fibers remain elongated as they move along the passageway through the mercerization tank and out of the mercerization tank and through the cleaning bath. The tensile force applied to the fibers also helps to keep the fibers parallel to the direction of travel through the device. In the illustrated embodiment, the cotton fiber loading supplied to the device causes the belt separation distance (in this case the belt itself not included in the interbelt distance) to be about 2 to 3 mm or less. This corresponds to a cotton sliver with a thickness of 5 kTex being fed to the device. This size of cotton sliver is slightly stretched to about 10 to 15 mm wide, so an array of three 5 kTex slivers will cover a belt about 3 to 40 mm thick. For thicker cotton slivers or other fibers, it can be supplied to the device up to 5 kTex per 30 mm belt width.

As discussed earlier, the small diameter of the rollers 20 and 24a-k and the short path length between the rollers (based on fiber length) are used to prevent the fibers from slipping between the opposing surfaces of the pair of belts 14, 16. It has been found to provide optimum efficiency.

The nip roller 20 is located on the mercerization bath and squeezes excess mercuring liquor out of the sliver and belt. Excess mercerized liquor is returned to the bath.

In a preferred embodiment of the invention, the mercerized solution is an aqueous sodium hydroxide solution. The concentration of sodium hydroxide is 40 ° Tw at 20-22% MV or 15 ° C, which corresponds to about 21 g of sodium hydroxide or 1.2 specific gravity per 100 ml of water. Mercerates also contain humectants in amounts of 5-25 g / L. One of the wetting agents stable in strong alkalis known in the art is used in preferred embodiments. Wetting agents are useful in situations in which the mercer liquor comes into contact with the fibers at low temperatures. Before reducing the temperature of the mercerized solution in contact with the fiber to the mercerized treatment temperature, the wetting agent may be dispersed if the method is modified to bring the mercerized liquid into contact with the fiber at a higher temperature.

The mercerization solution is maintained at a temperature range of -5 to 25 ° C. The temperature is more suitable toward the lower limit of this range.

The pH of the wash is lower than the pH of the mercerized solution. In a preferred embodiment, water is used.

The sliver 26 may also be transported through an additional zone (not shown) that exposes the sliver to additional solution. Additional zones may include a solution containing dilute acid to further neutralize any residual mercuring liquor in the sliver and / or belt.

While the preferred embodiment shown uses a bath for containing the mercerized liquor and the cleaning liquid, those skilled in the art will appreciate that the chamber (s) where liquid is sprayed onto the free cellulose fibers may be used instead of the bath. Thus, "zone" should be interpreted broadly to encompass it.

The speed (and length of the jaw) of transporting the sliver 26 through the mercerization bath 10 should be sufficient to allow the mercerized liquor to fully penetrate the sliver so that the mercerization of the fibers is assured. This also applies to other tanks in which the slivers are transported. For this reason, the number of rollers through which the fiber proceeds should be sufficient to remain in contact with the mercer liquor for a time sufficient for complete penetration and mercerization to take place.

Cellulose fibers remain compressed between the tensioned belts 14, 16, but Applicants have surprisingly found that the fibers swell and increase in diameter. Thus, the fiber is changed by the mercerization process from a flat ribbon that is common for untreated cellulose fibers to a more circular cross-sectional area characteristic of mercerized cellulose fibers.

Example 1

A 5 kTex sliver composed of cotton fibers was treated in the device shown in FIG. The sliver was fed into a pair of nip rollers between the two belts. This was done between the belts around a series of rollers impregnated in a tank containing a mercerized solution consisting of an aqueous solution of sodium hydroxide at a concentration of 21.4% (M / V) maintained at a temperature of 10 ° C. or lower. The treatment solution also contained 7 g / L humectant (Leophen MC [BASF]). The speed of the belt and the sliver was set so that the impregnation time in the sodium hydroxide solution was 40 seconds. After squeezing the excess sodium hydroxide solution, the sliver still maintained under tensile force was passed through a cleaning bath containing water for 30 seconds. After washing, excess liquid was removed with a pair of squeeze rollers (not shown in FIG. 1). The sliver was then passed through a bath containing dilute acetic acid (not shown in FIG. 1), maintained at pH 5 and neutralized residual alkali.

A control was prepared by treating a cotton sliver with the wetting agent and sodium hydroxide solution disclosed above, but in this case the material could be completely relaxed in the treatment solution during the cleaning and neutralization steps (this sample is called slack mercerization). .

Sliver experiments after drying showed that the mercerized sample under tension on the belt mercerizer was more shiny than the untreated material, and more shiny than the tensionless mercerized sample. The gloss of the sliver was twice that of the untreated material. Fiber length, strength and elongation at break of untreated and treated slivers were measured. The data shown in Table 1 indicate that the tensionless mercerized fibers shrink in length, while the tension mercerized fibers are somewhat longer than the untreated material. Both tensionless and belt mercerized fibers were stronger than untreated cotton and had higher elongation at break.

Physical Properties of Untreated, Tensionless Mercerized, and Belted (Terminated) Mercerized Cotton Average Fiber Length (Inches) Fiber strength (grams force per tex) (a) Elongation at Break (%) Untreated 1.17 32.5 6.0 Intense Mercerization 1.12 (-4.3%) 42.3 (+ 30.2%) 13.3 Belt Mercerization 1.18 (+ 0.9%) 41.5 (+ 27.7%) 8.9

The numbers in parentheses are the percentage change compared to the untreated face, gauge length 1/8 inch-see middle column above.

Scanning electron micrographs of untreated and belt mercerized cotton (FIGS. 2 and 3) show that the belt mercerizing technique is characterized by a more circular cross section of the fiber, characterized by the kidney bean-shaped, ribbon-shaped cross-section of the normal cotton fiber. Show that the shape has been successfully changed. 3 shows that the mercerized fiber surface is softer, less distorted, and more cylindrical, thus increasing gloss.

Example 2

Example 1 was repeated using 5 kTex slivers of the other two cotton fiber samples. The results were compared to the control example, one of which was not mercerized and the other, which was armless mercerized. The composition and concentration of the solution was as outlined in Example 1.

The properties of the fibers were tested and the results are shown schematically in Table 2. The results in Table 2 include those outlined in Table 1.

For certain cotton samples, the break adhesion to "belt"-(tension) and tensionless slivers was comparable, but significantly higher than the unmersed control. The elongation at break for the belt-mercered sliver is similar to the control, but the tensionless mercerized sliver showed a marked increase in elongation, which further confirms the high fiber shrinkage effect that occurs when the fiber is not constrained during treatment. will be.

The measured results also showed that the sliver of Sample 2 was 2.5 times more polished after the belt mercerization process than the non mercerized control.

Fiber length, strength and fineness for the three mercerized cotton samples, comparing the control with the "belt" -mercerized or without length constraint mercerized (tension mercerized) case Sample and Mercerization Processing Top 1/2 Average Length (inches) Fiber shrinkage (%) Short Fiber Index (% <0.5 inches) Length nonuniformity (%) Breaking adhesive force (gf / tex) Elongation at Break (%) Micronair (μg / inch) Sample 1 cotton sliver Non mercer belt 1.191.24 0-4.2 2.61.1 84.384.6 36.047.5 5.85.6 4.34.6 Sample 2-sided Sliber Beamer Mercerized Belt 1.171.181.12 0-0.95.1 3.64.55.6 82.582.080.6 32.541,542.3 6.08.913.3 4.24.85.3 Sample 3 Cotton Sliber Beamer Mercerized Belt 1.181.161.09 01.36.0 3.04.15.0 83.582.581.3 35.942.545.3 6.17.116.3 4.24.85.6

(Note: A positive number below contraction means contraction; a negative number means expansion-negative number is what you want)

Spinning and Staining Results

Samples of “belt” (tension) -mercerized and control slivers (sample 2 sides) were successfully drawn down from 5 kTex to 1 kTex and then spun into 40 kTex single yarn at 700 tpm. Two-folding was successfully completed at 400 tpm. Soon, it was necessary to add lubricant during the drawing and spinning process. This confirms that the mercerization method of the example does not play a sufficient role in removing the natural wax coating from the fibers.

Belt-mercerized yarn and control yarn were simultaneously cone-dyed in the same bath and knitted into small pieces of fabric. Examination of both yarn and knit samples confirmed that the belt-mercerized yarns had increased gloss and increased color.

The disclosed method has the following advantages:

Improved uniformity of treatment resulting from subsequent processes carried out after mercuring the fibers.

ㆍ Fiber strength is increased compared to normal cotton. This improves the spinning performance, in particular the possibility of higher spinning frame rates.

Mercerized cotton fibers can be blended with alkali-sensitizing materials, especially keratin fibers such as wool.

It is possible to manufacture knitted fabrics from mercerized cotton. Knitted fabrics can be mercerized but the bulk of the fabric is prone to mercerizing. This problem is avoided when mercerizing cotton as loose fibers or slivers.

The above preferred embodiments and examples are provided merely as illustrations of the inventive concept. Various modifications of the preferred embodiments and examples can be made without departing from the spirit and scope of the invention.

Claims (38)

Transporting the free cellulose fiber along a passage path through the mercerization zone that contacts the unconstrained cellulosic fiber with a mercuring liquor, and then through a cleaning zone that cleans the free cellulose fiber; A method of mercerizing free cellulose fibers, wherein the longitudinal shrinkage is maintained while the fibers are transported through both zones. The method of claim 1, wherein the free cellulose fibers are raw fibers, card fibers, slivers, or rovings. The method of claim 1 wherein the free cellulose fiber is in the form of a sliver. The method of claim 1, wherein the fiber is adapted to maintain the fiber length during the entire sequence of mercerization step, subsequent cleaning step, and passing step between the two steps. The method of claim 1, wherein the free cellulose fiber is maintained by being compressed between two surfaces as it travels along the passage path. The method of claim 5, wherein the cellulose fibers are transported along the passage path between a pair of belts that are pressed together at a plurality of locations through the passage path. The method of claim 5 or 6, wherein the fibers are stretched while being transported through the mercerization zone and the cleaning zone. The method of claim 7, wherein the elongation is less than or equal to about 4%. The method of claim 7 or 8, wherein the belt is slightly elastic and lies under tension through the mercerization zone and the cleaning zone. 10. The method of any of claims 7-9, wherein the free cellulose fibers are oriented. The method of any one of claims 6 to 10, wherein the passage path comprises a nip roller at the beginning and the end of the passage path such that the belt passes through the two zones under tension. The method according to claim 6, wherein the belt passes over the guide means at a number of points present along the passage path. The method of claim 12, wherein the straight path length between the points where the belt contacts the guide means is within or below the average length range of the cellulose fibers. The method of claim 13, wherein the straight path length is less than 2.8 cm. The method according to claim 12, wherein the guide means is a roller. The method of claim 15, wherein the diameter of the roller is less than twice the average length of the fibers to be treated. The method of claim 15, wherein the diameter of the roller is less than 1.5 times the average length of the fibers to be treated. 18. The method of any one of claims 15 to 17, wherein the passage path is a bypass path wound around the roller. 19. The method of any one of claims 12-18, wherein the nip roller is provided in the region between the mercerization zone and the cleaning zone to squeeze the excess mercuring liquor out of the fiber and belt. 20. The method of claim 6, wherein the belt is driven by a pad mangle positioned at the distal end of the passageway and pulling the belt through the passageway. The method of claim 1, wherein the cellulose fibers are transported through additional zones after cleaning. The method of claim 21, wherein the cellulose fibers are transported through a neutralization zone where the cellulose fibers are neutralized with a neutralizing liquid. (i) mercerization zone; (ii) the washing zone after the mercerization zone; (iii) a conveyor comprising a pair of surfaces for holding the fibers such that longitudinal shrinkage is prevented during transportation of free cellulose fibers along a passage path through the mercerization zone and the cleaning zone; (iv) drive means for driving the conveyor; And (v) pressing means for holding the free cellulose fibers so as to compress the conveyor surfaces together in the mercerization zone and the cleaning zone, thereby preventing longitudinal shrinkage of the fibers passing through the zone; Merchandising apparatus of a free cellulose fiber, comprising. The apparatus of claim 23 comprising a neutralization zone after the cleaning zone. The apparatus of claim 23 or 24, wherein the conveyor is formed to be capable of holding free cellulose fibers such that longitudinal shrinkage is prevented across the mercerization zone, the cleaning zone and the passage zone between these two zones. 26. The apparatus of any one of claims 23 to 25, wherein the conveyor comprises a pair of belts. 27. The device of claim 26, wherein the belt is under tension to such an extent that compressive force is maintained on the fiber in use to hold the fiber firmly, thereby preventing longitudinal shrinkage. The apparatus of claim 27, wherein the belt is slightly elastic so that, in use, the bundle of aligned free cellulose fibers supplied between the belts is subjected to stretching by the belt in the mercerization zone and the cleaning zone. 29. The method according to any one of claims 26 to 28, wherein the press means comprises at least two pairs of nip rollers, wherein the pair of nip rollers are positioned at the distal end of the mercerization zone to squeeze excess mercuring liquor, and Wherein the pair is located at the end of the cleaning zone or after the end of the cleaning zone. 30. The straight line distance ("path length") between any point of any of claims 26 to 29 wherein the belt contacts the pressing means along the passage path is within the average length range of the cellulose fibers of the fibers to be treated in the device. Or is less than this distance. 31. The apparatus of claim 30, wherein the path length is less than 2.8 cm. 32. The apparatus according to any one of claims 26 to 31, wherein the press means comprises a plurality of rollers located along the passage path in the mercerization zone and the cleaning zone. 33. The apparatus of claim 32, wherein the diameter of the roller is less than twice the average length of the fibers to be treated in the apparatus. 34. The apparatus according to claim 32 or 33, wherein the passage path is a bypass route wound around the roller, wherein there is an approximately equal number of left and right curves around the roller in the passage path. 35. The device according to any one of claims 26 to 34, wherein the drive means is in the form of mangles, which is located at the end or downstream of the passage path. 36. The apparatus of any one of claims 23 to 35, wherein the mercerization zone comprises a mercerization bath for containing the mercuring liquor, and the cleaning zone comprises a cleaning bath for containing the cleaning liquor. Treatment zone; A conveyor comprising a pair of surfaces for holding the fibers to be treated such that shrinkage of the material through the treatment zone is prevented; Drive means for driving the conveyor; And Pressing means for pressing the surface of the conveyor holding the fibers together to prevent the shrinkage of the fibers Fiber processing apparatus comprising a. A product made by the method of any one of claims 1-22 or by the device of any one of claims 23-37.