CN111757950A

CN111757950A - Sliver for spun yarn containing cellulose acetate

Info

Publication number: CN111757950A
Application number: CN201980015404.9A
Authority: CN
Inventors: 卡尔玛·卡德恩·凯莉; 埃文·V·罗迪克; C·史密斯查德; 罗纳德·A·斯内尔
Original assignee: Eastman Chemical Co
Current assignee: Eastman Chemical Co
Priority date: 2018-02-27
Filing date: 2019-02-26
Publication date: 2020-10-09
Also published as: JP2021515118A; EP3759267A1; WO2019168845A1; KR20200126398A; US20210123166A1

Abstract

A sliver containing cellulose acetate staple fibers is obtained which exhibits good fiber-to-fiber cohesion energy and can be drawn successfully and made into a spun yarn. Such sliver can be made from cellulose acetate staple fibers having a round shape, a denier of less than 3.0, a crimp frequency per inch (CPI) of 5 to 30, a good fiber-to-fiber coefficient of friction, and having low static charge. By containing cellulose acetate staple fibers, the textile fabric made from spun yarns has a plant-based renewable resource and can exhibit thermoplastic behavior to impart better dimensional stability to the textile fabric. The low denier cellulose acetate fibers can impart a cotton-like hand, but can be successfully processed through a carding machine to form cohesive sliver and retain their integrity throughout the draw process, allowing them to be formed into spun yarns.

Description

Sliver for spun yarn containing cellulose acetate

Technical Field

The present invention relates to slivers (slivers) containing cellulose acetate staple fibers to make rovings (rovings) and spun yarns (spun yarns) for textile fabrics, and more particularly to slivers having good fiber-to-fiber cohesion energy.

Background

Woven fabrics composed of spun yarns are widely used in a variety of applications. These fabrics are formed by weaving, knitting, crocheting, knotting or felting yarns made of natural and/or synthetic materials such as, for example, polyester, polyamide, acrylic, polyurethane, glass, wool, polypropylene, silk, cashmere, sisal, flax, hemp (hemp), cotton, various regenerated cellulose materials such as viscose, modal and lyocell, and are typically formed as blends of two or more of these materials.

Although the use of regenerated cellulose materials has the advantage of being derived from plant-based renewable resources (cellulose), they do not exhibit thermoplastic behavior. Typically, a textile fabric containing regenerated cellulose material, cotton, hemp or linen is blended with a heat set material, such as polyester or nylon, which is thermoplastic to provide the dimensional stability required for the textile fabric, such as low shrinkage, low twist (twist) and low skew (skew). Alternatively, woven fabrics without such thermoplastic materials need to be resinated and/or preshrinked to impart dimensional stability. It would be desirable to provide a textile fabric blend having materials derived from plant-based renewable resources and exhibiting the heat-set behavior of thermoplastic materials without the need for resin treatment and/or preshrinking.

Even if the material chosen meets end-use performance requirements, it cannot be adopted into the woven fabric market if it cannot be processed on existing equipment for making spun yarns. An important part of the spun yarn market uses a ring spinning process, which is carried out from a roving made from drawn sliver of staple fibers obtained by a carding process. The staple fibers should be suitable for carding into coherent sliver, which can be ring spun into yarn, all using conventional and existing equipment. The key to the success of this material is that it can be successfully carded and drawn into sliver of sufficient uniformity and strength. The staple fibers used to make the sliver should be capable of imparting cohesiveness to the sliver to maintain its integrity and shape, yet have a low enough coefficient of dynamic friction to allow easy drafting of the sliver.

The alternative material should also have a soft hand closer to that of cotton, rather than the composite hand of polyester, polypropylene or polyethylene fibers. Fibers with low denier are more suitable for achieving softer hand, however, fibers with low denier are more difficult to process. The fibers are crimped in order to separate and effectively orient the fibers during the carding operation and help maintain sliver integrity, which generally has no significant effect on the strength of the higher denier fibers. However, when the denier drops below 3, the application of crimp can weaken the tenacity of the fibers to the point that the fibers are prone to breakage, forming dust-like lint, which results in fiber loss and frequent machine shutdowns to remove the rapidly accumulating lint.

It is desirable to utilize an alternative material to regenerated cellulose as a material that is derived from a plant-based renewable resource, has thermoplastic behavior to impart better dimensional stability to a woven fabric than the same woven fabric containing regenerated cellulose, has a low denier to impart a cotton-like hand, and has the correct combination of properties to be processed through a carding machine to form cohesive sliver and successfully formed into spun yarn. In particular, the slivers made from such CA staple fibers should have good cohesive energy so that they can form carded slivers and retain their integrity throughout the draw process.

Disclosure of Invention

There is now provided a carded sliver comprising CA staple fibers having a circular shape, a denier of less than 3.0, a crimp frequency per inch (CPI) of 5 to 30, and wherein the sliver has a fiber-to-fiber cohesive energy of at least 10,000 joules.

Also provided is a spun yarn obtained from one or more carded sliver(s), at least one of which contains CA staple fibers having a circular shape, a denier of less than 3.0, a crimp frequency per inch (CPI) of 5 to 30, and wherein the sliver has a fiber-to-fiber cohesion energy of at least 10,000 joules.

The present invention also includes a woven fabric, the fabric being obtained from spun yarn, the yarn being obtained from carded sliver comprising CA staple fibers (CA staple fibers), the CA staple fibers containing an amount of a spin finish, and wherein the woven fabric contains no spin finish, or contains an amount of spin finish less than the amount on the CA staple fibers, the staple CA staple fibers having a round shape, a Denier (DPF) of less than 3.0, a crimp frequency per inch (CPI) of 5 to 30, wherein the one or more carded slivers have a fiber-to-fiber cohesive energy of at least 10,000 joules.

Desirably, the CA staple fibers used to make the carded sliver have a dynamic coefficient of friction between untwisted fibers and fibers (F/F CODF) of between 0.11 and less than 0.2, measured according to ASTM D3412/3412M-13 on uncrimped filament yarns having the same composition, shape and denier as the CA staple fibers. The CA staple fibers used to make the carded sliver also had a static charge of less than 1.0 at 65% relative humidity as measured on the filament yarn line.

Drawings

Fig. 1 relates to different parameters for determining the crimp amplitude of crimped fibers.

Detailed Description

It has been found that sliver can be successfully formed from CA staple fibers and further successfully processed into spun yarns to make woven fabrics. At the same time, the CA staple fibers may be environmentally friendly, exhibit thermoplastic behavior, have a soft hand feel similar to cotton, and may be processed using new and existing processing equipment.

As used herein, a woven fabric is a material made from spun yarn, and which is woven, knitted, crocheted, knotted, embroidered, braided/knitted, mesh woven (lace), or carpet pile-type. Textile fabrics include geotextiles, carpet pile and fabrics (including cloths). Geotextiles as used in the context of the woven fabrics herein are those which are woven or knitted. Examples of suitable types of woven fabrics that may be formed from the staple fibers of the present invention may include, but are not limited to: garments (undergarments, socks, hats, shirts, pants, dresses, scarves, gloves, etc.), bags, baskets, upholstered furniture, curtains, towels, tablecloths, bed covers, flat coverings, art, filters, flags, backpacks, tents, handkerchiefs, rags, balloons, kites, sails, parachutes, automobile upholstery, protective clothing (such as those of firefighters and welders that are heat, bullet or stab resistant), medical textile fabrics (such as implants) and crop protection agrotextiles. CA staple fibers refer to cellulose acetate staple fibers, and "staple fibers" refer to fibers cut from continuous filaments or tow bands of continuous filaments. The carded sliver, spun yarn or woven fabric "obtained" from said elements comprises any number and type of intermediate steps or process operations.

There is now provided a carded sliver comprising CA staple fibers having a circular shape, a denier of less than 3.0, a crimp frequency per inch (CPI) of from 5 to 30, and an electrostatic charge of less than 1.0 at 65% relative humidity, and wherein the sliver has a fiber-to-fiber cohesive energy of at least 10,000 joules.

Carded sliver is a continuous bundle or strand of loose untwisted fibers aligned generally parallel to each other. This alignment is performed by subjecting the fibers to a carding process.

The sliver and spun yarn of the present invention can be formed according to any suitable method. The process of forming sliver from staple fibers begins with feeding the staple fibers to a carding machine and optionally blending CA staple fibers with fibers of other non-cellulose acetate materials. If CA staple fibers are blended with other natural fibers, those natural fibers may optionally be separated from foreign objects (such as dust, seeds, and other foreign objects) by a sorting process and formed into a lap (lap). The CA staple fibers contained in the bale can be blended with other bale fibers by opening each bale and feeding the fibers into a blender. Blending may occur during lap formation, in a carding operation, or during a drawing operation, but desirably occurs during or before the carding process. The staple fibers may be opened and tufted to pull the fibers apart before being fed into a carding machine.

The carding process can be carried out manually or by any conventional carding equipment, including drum cards, bulk cards (cottage cards) and industrial cards. Typically, during carding, CA staple fibers are placed on a conveyor or carding machine along with staple fibers of other materials (non-CA staple fibers) other than cellulose acetate and passed through a plurality of cylinders (or other moving surfaces) covered with wire brushes, metal teeth, or other gripping surfaces. The carding machine may be a roller doffer carding machine, a fine air doffer carding machine or a coarse air doffer carding machine. A typical card consists of a large cylinder with a number of teeth or fine wire brushes that surround at least a portion of the surface of the larger cylinder and move in opposition to the larger cylinder, and a number of smaller rollers enclosed in a cover plate (flat) with wire brushes. As the surfaces move relative to each other, the fibers are mechanically separated and aligned in a direction substantially parallel to each other. The cover and cylinder have small teeth or wire brushes that can become progressively thinner or closer together as the fibers are drawn through the machine. The fibers remain on the cylinder surface and are drawn in the same parallel direction to form a thin web which is fed into a funnel-shaped tube, forcing the web into round loose strands or loose ropes called comb or carded sliver.

Alternatively, the carded sliver can be combed, which is a desirable operation for natural fibers used in very fine yarns, intended to make finer fabrics. Upon merging, a fine comb is applied to the sliver to further separate and remove too short fibers, further aligning the fibers parallel to each other.

Carded sliver is produced by a carding machine that has not been subjected to combing (if used) and drawing operations. The carded sliver desirably has a total denier of at least 10,000 or at least 15,000, or at least 20,000, or at least 25,000, or at least 30,000, or at least 35,000, or at least 40,000, or at least 45,000, or at least 50,000. Typically, the sliver has a total denier of no greater than 200,000, or no greater than 150,000, or no greater than 100,000, or no greater than 80,000, or no greater than 60,000, or no greater than 50,000. For most applications, the total denier of the sliver is from 20,000 to 80,000, or from 25,000 to 60,000 or from 30,000 to 60,000. If one wishes to convert sliver denier to grain, this conversion factor is used: a 60 grain sliver is 35,000 denier.

Once the carded sliver is formed, they are fed, after an optional combing step, to a draw frame where multiple slivers are combined and drafted (reducing weight per unit length) to make them longer, finer, and further straightened and aligned to produce slivers of more uniform size with enhanced fiber-to-fiber blending within the sliver. The multiple slivers are usually further combined to make a larger sliver or strand, which can then be further drawn. The draw process improves sliver quality by straightening and aligning the staple fibers therein and producing a more uniform composite sliver. The draw process requires passing the sliver through several pairs of rollers (optionally first through a guide such as a spoon) and each successive pair of rollers operates at a higher rate than the previous pair, so that the sliver merges, reduces in size and is substantially drafted as it moves down the draw frame. The combined thin and drafted sliver product is given a slight twist during drawing and is wound onto a bobbin as a roving.

The total denier of the strand or roving may be at least 30,000, or at least 40,000, or at least 50,000, or at least 55,000, or at least 60,000. Typically, the total denier of the sliver is no greater than 300,000, or no greater than 200,000, or no greater than 150,000. This conversion factor is used if one wishes to measure denier in hank: 1 skein 5300 denier. Typical industries for rovings range from 0.3 to 5.0 ends or about 18,000 to 1000 denier, respectively.

The roving wound on the bobbin may then be subjected to a yarn ring spinning operation. There are a wide variety of other spinning methods that can use drawn carded sliver directly without roving, such as open end (rotor) spinning, air jet spinning, air vortex spinning, and electrostatic spinning. The CA staple fibers of the present invention are well suited for any type of spinning process used.

A common spinning process is ring spinning. The roving wound on the spool may pass through another set of drafting rollers to elongate the roving and obtain the desired final thickness, and then fed through a moving section (roller) which moves at high speed around a fixed ring which surrounds another spool mounted on a rotating shaft. The velocity of the yarn moving through the moving section is slower than the velocity of the shaft, thereby imparting the desired twist to the yarn as it is wound onto the spool. The moving part oscillates axially relative to the spool to distribute the yarn along the length of the spool, which completes the twisting and winding in one step.

Open-end spinning is also a suitable method and differs from ring spinning in many ways. In open-end spinning, the roving step is omitted and the sliver is fed to the spinning machine by an air stream. To achieve this, the fibres in the sliver have to be separated (usually a rotary beater) and the separated fibres are carried by the air flow through a tube or duct to the rotor and deposited into grooves on the rotor side. As the rotor rotates, it twists the fibers in the grooves and removes the resulting twisted yarn from the grooves, as new separated fibers are continually fed into the rotor grooves.

The CA staple fibers in the carded sliver are formed from one or more cellulose acetates. The cellulose acetate may be formed of cellulose diacetate, cellulose triacetate, or a mixture thereof. The degree of substitution of cellulose acetate is in the range of 1.9 to 2.9. As used herein, the term "degree of substitution" or "DS" refers to the average number of acetyl substituents per anhydroglucose ring of the cellulosic polymer, with a maximum degree of substitution of 3.0. In some cases, the cellulose acetate used to form fibers as described herein may have an average degree of substitution as follows: at least about 1.95, 2.0, 2.05, 2.1, 2.15, 2.2, 2.25, or 2.3, and/or not more than about 2.9, 2.85, 2.8, 2.75, 2.7, 2.65, 2.6, 2.55, 2.5, 2.45, 2.4, or 2.35, wherein greater than 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% of the cellulose acetate has a degree of substitution greater than 2.15, 2.2, or 2.25. Desirably, greater than 90 wt%, or greater than 95 wt%, or greater than 98 wt%, or greater than 99 wt% and up to 100 wt% of all acyl substituents are acetyl substituents (C2). Desirably, the cellulose acetate has no acyl substituents with a carbon number greater than 2.

Weight average molecular weight (M) of cellulose acetate measured using gel permeation chromatography with N-methyl-2-pyrrolidone (NMP) as solvent_w) And may be no greater than 90,000. In some cases, the cellulose acetate may have a molecular weight as follows: at least about 10,000, at least about 20,000, 25,000, 30,000, 35,000, 40,000, or 45,000, and/or no greater than about 100,000, 95,000, 90,000, 85,000, 80,000, 75,000, 70,000, 65,000, 60,000, or 50,000.

Cellulose acetate or other CA staple (stabel) may be formed by any suitable method. In some cases, cellulose acetate may be formed as follows: cellulose acetate flakes are formed by reacting a cellulosic material, such as wood pulp, with acetic anhydride and a catalyst in an acidic reaction medium. The flakes can then be dissolved in a solvent (such as acetone or methyl ethyl ketone) to form a "solvent spinning dope," which can be filtered and fed through a spinneret to form CA staple fibers. In some cases, up to about 1 wt% or more of titanium dioxide or other matting agent can be added to the spinning dope prior to filtration, depending on the desired properties and end use of the fiber.

In some cases, the solvent spinning dope or flake used to form the CA staple fibers may include little (or no) additives other than cellulose acetate. These additives may include, but are not limited to, plasticizers, antioxidants, heat stabilizers, pro-oxidants, acid scavengers, minerals, pigments, and colorants. In some cases, CA staple fibers as described herein can include cellulose acetate (based on the total weight of the fiber) as follows: at least about 90%, 90.5%, 91%, 91.5%, 92%, 92.5%, 93%, 93.5%, 94%, 94.5%, 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99%, 99.5%, 99.9%, 99.99%, 99.995%, or 99.999%. Fibers formed according to the present invention can include no greater than about 10, 9.5, 9, 8.5, 8, 7.5, 7, 6.5, 6, 5.5, 5, 4.5, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.5, 0.1, 0.01, 0.005, or 0.001 weight percent of additives other than cellulose acetate, including the specific additives listed herein.

At the spinneret, the solvent spinning dope may be extruded through a plurality of orifices to form continuous cellulose acetate filaments. At the spinneret, the filaments may be drawn to form bundles of hundreds or even thousands of individual filaments. Each of these bundles or ribbons may comprise the following fibers: at least 100, or at least 150, or at least 200, or at least 250, or at least 300, or at least 350, or at least 400, and/or not more than 1000, or not more than 900, or not more than 850, or not more than 800, or not more than 750, or not more than 700. The spinneret can be operated at any rate suitable to produce filaments and bundles having the desired size and shape.

Multiple bundles may be combined into a tow band, such as, for example, a crimped or uncrimped tow band. The tow band may have any suitable dimensions, and in some embodiments, may have a total denier as follows: at least about 10,000, or at least 15,000, or at least 20,000, or at least 25,000, or at least 30,000, or at least 35,000, or at least 40,000, or at least 45,000, or at least 50,000, or at least 75,000, or at least 100,000, or at least 150,000, or at least 200,000, or at least 250,000, or at least 300,000. Additionally or alternatively, the total denier of the tow band may be no greater than about 5,000,000, or no greater than 4,500,000, or no greater than 4,000,000, or no greater than 3,500,00, or no greater than 3,000,000, or no greater than 2,500,000, or no greater than 2,000,000, or no greater than 1,500,000, or no greater than 1,000,000, or no greater than 900,000, or no greater than 800,000, or no greater than 700,000, or no greater than 600, 00, or no greater than 500,000, or no greater than 400,000, or no greater than 350,000, or no greater than 300,000, or no greater than 250,000, or no greater than 200,000, or no greater than 150,000, or no greater than 100,000, or no greater than 95,000, or no greater than 90,000, or no greater than 85,000, or no greater than 80,000, or no greater than 75,000, or no greater than.

The individual filaments extruded in a generally longitudinally aligned manner and ultimately forming the tow band are of a particular size. The monofilament linear denier (grammage of 9000m fiber length) or DPF of the CA filaments (and of the corresponding staple fibers in the sliver and yarn) in the tow band is in the range of 0.5 to less than 3, or 1.0 to less than 3, measured according to ASTM D1577-01 using the FAVIMAT vibrometer (vibroscope) procedure. Desirably, the DPF for the filaments and corresponding short fibers is in the range of 1.0 to 2.5, or 1.0 to 2.2, or 1.0 to 2.1, or more desirably, in the range of 1.0 to 2.0, or 1.0 to less than 2.0, or 1.0 to 1.9, or 1.1 to 1.9.

The individual filaments and corresponding staple fibers exiting the spinneret had a substantially circular cross-sectional shape, but in the acetone solvent spinning process, the cross-section would be slightly irregular or crenulated due to collapse of the hardened surface. As used herein, the term "cross-section" generally refers to the cross-section of a filament measured in a direction perpendicular to the direction of elongation of the filament. The cross-section of the filaments can be determined and measured using Quantitative Image Analysis (QIA). Staple fibers may have a similar cross-section to the filaments from which they are formed.

In some cases, this deviation can be characterized by the filament's shape factor, which is determined by the following equation, i.e., circumference/(4 π × cross-sectional area)^1/2. In some embodiments, the form factor of the individual cellulose acetate (or other CA staple) filaments may be 1 to 2, or 1 to 1.8, or 1 to 1.7, or 1 to 1.5, or 1 to 1.4, or 1 to 1.25, or 1 to 1.15, or 1 to 1.1. Has perfect circular shapeThe form factor of the filaments of the cross-sectional shape was 1. The shape factor can be calculated from the cross-sectional area of the filament, which can be measured using QIA.

After the bundles are assembled into a tow band, they may be passed through a crimp zone where a patterned undulating shape may be imparted to at least a portion or substantially all of the individual filaments. Imparting crimp is necessary to allow the staple fibers to be separated and oriented during the carding operation and to provide a degree of the required cohesion required to prevent unraveling of the sliver.

A suitable type of mechanical crimper is the "stuffing box" crimper which utilizes a pair of nip rollers to force a tow band into the confines of the stuffing box just downstream of the rollers. The compressive forces generated on the fibers can cause the fibers to bend, curl and interlock into a cohesive tow band. Examples of apparatus suitable for imparting crimp to a filament are described below: such as U.S. patent nos. 9,179,709; 2,346,258, respectively; 3,353,239, respectively; 3,571,870, respectively; 3,813,740, respectively; 4,004,330, respectively; 4,095,318, respectively; 5,025,538, respectively; 7,152,288, respectively; and 7,585,442, each of which is incorporated by reference herein to the extent not inconsistent with this disclosure. In some cases, the crimping step may be performed at a rate of at least: about 50m/min (75, 100, 125, 150, 175, 200, 225, 250m/min), and/or not more than about 750m/min (475, 450, 425, 400, 375, 350, 325, or 300 m/min).

The low denier CA staple fibers of the present invention are susceptible to breakage due to the normal crimp frequency imparted to the higher denier fibers typically used in cigarette filter tow. However, as mentioned above, crimp is an essential component of the fiber forming the coherent sliver and spun yarn. A low crimp frequency is necessary to form fibers with minimal breakage and a high degree of retained tenacity. As used herein, the term "retained tenacity" refers to the ratio of the tenacity of a crimped filament (or staple fiber) to the tenacity of the same, but uncrimped, filament (or staple fiber), expressed as a percentage. For example, if the same, but uncrimped, fiber has a tenacity of 1.5 g/denier, a crimped fiber having a tenacity of 1.3 grams-force/denier (g/denier) will have a retained tenacity of 87%.

Cellulose acetate filaments crimped according to the present invention can have a retained tenacity as follows: at least about 60%, or at least 65%, or at least 70%, or at least 75%, or at least 80%, or at least 85%, or at least 90%, or at least 95%. In some cases, the retained toughness may be 100%. In some cases, the final CA staple fibers may exhibit similar retained tenacity as compared to the same, but uncrimped staple fibers.

Crimping may be performed such that the final staple fibers have the following crimp frequency (measured according to ASTM D3937): at least 5, or at least 7, or at least 8, or at least 9, or at least 10, or at least 12, and at most 30, or at most 25, or at most 20, or at most 19 Crimps Per Inch (CPI). A CPI above 30 will result in excessive breakage and lower retained tenacity, resulting in lint formation and fiber loss. Less than 5CPI is not sufficient to properly card the fibers or retain the cohesion of the sliver. Desirably, the CPI is 10 to 20.

The ratio of CPI to DPF is a useful measure to ensure that the appropriate CPI is given for a given DPF and that the necessary balance of curl frequency and toughness is maintained for a given DPF. Suitable ratios of CPI to DPF include 6:1 to 30:1, or 6:1 to 20:1, particularly 6:1 to 14:1, or 7:1 to 12: 1.

When crimped, the crimp amplitude of the fibers may vary, and may be, for example, at least about 0.85, or at least 0.90mm, or at least 0.93mm, or at least 0.96mm, or at least 0.98mm, or at least 1.00mm, or at least 1.04 mm. Additionally or alternatively, the crimp amplitude of the fibres may be at most 1.75mm, or at most 1.70mm, or at most 1.65mm, or at most 1.55mm, or at most 1.35mm, or at most 1.28mm, or at most 1.24mm, or at most 1.15mm, or at most 1.10mm, or at most 1.03mm, or at most 0.98 mm.

In addition, the final staple fibers can have a crimp rating of at least about 1: 1. As used herein, "crimp ratio" refers to the ratio of uncrimped tow length to crimped tow length. In some embodiments, the staple fibers may have a crimp ratio of at least about 1:1, at least about 1.1:1, at least about 1.125:1, at least about 1.15:1, or at least about 1.2: 1.

Curl amplitude and curl ratio were measured according to the following calculationsThe dimensions of the photographs are shown in FIG. 1: crimp length (L)_c) Equal to the inverse of the curl frequency (1/curl frequency), and the curl ratio is equal to the straight length (L)₀) Divided by the curl length (L)₀:L_c). As shown in FIG. 1, half the length of the straight line (L) is used₀/2) and half the crimp length (L)_cAnd/2) calculating the amplitude (A) from a geometrical angle. The uncrimped length can be simply measured using conventional methods.

After crimping, the fibers may be dried in a drying zone to reduce the moisture (total of water and solvent) content of the tow band. In some cases, the drying zone may be sufficient to reduce the final moisture content of the tow band to (based on the total weight of the yarn): not greater than about 9 wt%, or less than 8.5 wt%, or less than 8 wt%, or less than 7.5 wt%, or less than 7 wt%, or less than 6.5 wt%, or less than 6 wt%. Typically, the moisture content does not fall below about 3.5 wt% or below about 4 wt%. Any suitable type of dryer may be used, such as, for example, a forced air oven, a drum dryer, or a heat-setting tunnel. The dryer can be operated at any temperature and pressure condition to provide the desired level of drying without damaging the yarn.

Once dried, the tow band may be fed to a cutting zone, or alternatively, baled first, and the resulting bale may be directed to a cutting zone where the elongated tow band may be cut into staple fibers. The staple fibers of the present invention may be cut to length as desired for the application. Unexpectedly, the cut length also affects the sliver cohesion and the ability to successfully spin a yarn at a given denier. All other factors remaining unchanged, to successfully spin a spun yarn at a given denier and staple length, it may be necessary to adjust the staple cut length at lower DPFs. The staple length is typically in the range of at least 5mm and at most 150 mm. Other examples of desired cut lengths include the following: at least 10mm, or at least 11mm and not more than about 100mm, or not more than 90mm, or not more than 80mm, or not more than 60mm, or not more than 55mm, or not more than 50mm, or not more than 45mm, or not more than 40mm, or not more than 38mm, or not more than 35mm, or not more than 32mm, or not more than 30mm, or not more than 28mm, or not more than 26 mm. Examples of cut length ranges include 10 to 55mm, or 10 to 50mm, or 10 to 45mm, or 11 to 38mm, or 11 to 26 mm.

Any suitable type of cutting device may be used that can cut the filaments to a desired length without unduly damaging the fibers. Examples of cutting devices may include, but are not limited to, rotary cutters, guillotines, stretch-breaking devices, reciprocating blades, and combinations thereof. Once cut, the staple fibers may be baled or otherwise bagged or packaged for subsequent transport, storage, and/or use.

The sliver obtained from CA staple fibers has a fiber-to-fiber cohesive energy of at least 10,000 joules (J), or at least 12,000J, or at least 15,000J, or at least 17,000J, or at least 20,000J. The fiber-to-fiber cohesion energy preferably does not have a cohesion energy greater than 30,000J to ensure that the sliver can be drawn sufficiently consistently without fiber breakage. Sliver fiber-to-fiber cohesion energy is affected by many factors, including cut length, CPI, denier, finish coating level and type (to adjust fiber-to-fiber and fiber-to-metal dynamic coefficient of friction, static charge), and fiber material. Since the process of making the sliver requires good fiber-to-fiber cohesion and since the sliver also needs to maintain their cohesion and integrity in downstream processing of the sliver, such as in drawing operations that subject the sliver to elongation, the fibers used in making the sliver and formed into the sliver require a greater F/FCODF relative to the fibers used in or making many nonwoven applications. For spun yarn applications, the F/F CODF is higher than for non-woven applications in order to retain the cohesion energy and strength of the sliver, but not so high that it breaks when drawn and elongated with conventional equipment.

The fiber-fiber cohesion energy of the carded sliver was determined by a rotor ring test. The test apparatus and procedure were developed at the textile technology institute of Denkendorf (Denkendorf) in germany. A small amount of pre-opened fiber (2-3 grams) was fed from the feed tank to a feed roll rotating at 5 revolutions per minute. The feed roller delivers the fibers to the opening roller, which spins at 4000 revolutions per minute by carding between cylinders. The fibers were transferred from the opening roll to a feed zone under partial vacuum and centrifugal force and then deposited by air transfer into a rotor that rotated at 10,000 revolutions per minute. In the rotor, a fiber ring is formed, which consists mainly of parallel fibers. The energy (joules) required to drive the opening cylinder at a constant rate was measured. The test was performed at 65% RH and 70 ° F.

Examples of suitable fiber-to-fiber cohesion energies for the sliver are 10,000J to 30,000J, or 10,000J to 28,000J, or 10,000J to 25,000J, or 10,000J to 23,000J, or 10,000J to 20,000J, or 12,000J to 30,000J, or 12,000J to 28,000J, or 12,000J to 25,000J, or 12,000J to 23,000J, or 12,000J to 20,000J, or 15,000J to 30,000J, or 15,000J to 28,000J, or 15,000J to 25,000J, or 15,000J to 23,000J, or 15,000J to 20,000J, or 17,000J to 30,000J, or 17,000J to 28,000J, or 17,000J to 25,000J, or 17,000J to 23,000J, or 17,000J to 20,000J.

Another method for describing the sliver cohesion energy is to perform a short fiber mat friction test on the short fibers used to make the sliver and calculate the scoroop value. The coated fibers described herein may have a Scoop value (measured as the difference between static and dynamic tension) of less than 160 grams force (g). In some embodiments, the coated staple fibers may exhibit a scroop value as follows: at least about 10 grams, or at least 15 grams, and desirably at least 20 grams, or at least 23 grams, or at least 25 grams, or at least 28 grams, or at least 30 grams, or at least 35 grams, or at least 40 grams, or at least 45 grams, or at least 50 grams, or at least 55 grams, or at least 60 grams, or at least 65 grams, or at least 70 grams, or at least 75 grams, or at least 80 grams, or at least 85 grams, or at least 90 grams (in each case in grams), and desirably no greater than 200 grams, or no greater than 180 grams, or no greater than 160 grams, or no greater than 180 grams, or no greater than 140 grams, or no greater than 120 grams (in each case in grams). Staple fibers with lower cohesion (as indicated by the lower scroop value) do not have sufficient cohesive energy to form a sliver that retains its integrity and strength and can be fully processed or drawn. The short fibers have a scroop value of more than 1 or even 0.8. The static and dynamic coefficients of friction and the resulting scroop values can be calculated from the pad friction methods described in us patent 5,683,811 and us patent 5,480,710, but using an Instron 5966 series machine or equivalent, rather than an Instron 1122 machine. As described in the 5,480,710 patent, the fiber-to-fiber static friction is determined as the maximum threshold pull force at low pull rates when equilibrium pull behavior is reached, and the fiber-to-fiber dynamic friction is similarly calculated, but as the pad traverses the slip-stick behavior, the fiber-to-fiber dynamic friction is the minimum threshold level of force. The scroop is calculated as the difference between the static friction tension and the dynamic friction tension in grams force.

A more detailed description of the fiber-to-fiber friction coefficient used in the pad friction method is given below. The friction coefficient test fixture comprises a fixed horizontal workbench and a movable sliding plate. Both the table and the sled can be covered with test material. A tow rope attaches the sled to the low force load cell, with the sheave guiding the tow rope during testing. The fixture was mounted to the base of the test instrument and the sled was pulled across the horizontal table as the crosshead/load cell was moved.

Data from the load cell was recorded during the test and analyzed to determine static and dynamic friction. Static friction is generally the maximum peak force on the load curve required to initiate movement of the skateboard, while dynamic friction is the average force on the load curve recorded throughout the total travel length of the skateboard. The pad friction coefficient is defined as the average of the static and dynamic friction divided by the mass of the skateboard, while the Scroop value is the difference between the static and dynamic friction.

The apparatus includes a Mettler Balance (Mettler Balance), an air jet to assist in opening and untwisting the short fiber sample, a mini-card or equivalent machine capable of orienting the short fiber sample to produce a test fiber mat, a universal draw/compression tester: instron 5966, or equivalent, fixed steel horizontal table with fixed pulleys: 200W 360L 13Hmm, steel movable slide: a 63W x 65L x 6Hmm steel block weighing 200g with hook attachment, steel weight: 1 kg.

The fiber sample manufacturing and testing apparatus was set up as follows:

1. about 50 grams of the cut staple crimped fibers were processed by air jets to introduce an opening effect on the individual fibers.

2. Two samples were taken, each opened fiber weighing about 5 grams and processed through a mini-card to form two fiber mats, each measuring 75W x 225L x 50 Hmm.

3. A universal tensile/compressive tester with a 5kN to 10kN load cell was used with a coefficient of friction test fixture attached.

4. A 50 grit sandpaper sheet was attached to a fixed steel horizontal table with tape (tape).

5. A second piece of 50 grit sandpaper was attached with adhesive tape to the bottom of the steel movable sled and a front wire harness (toeline) was attached to the load cell of the universal tensile/compressive tester so that when the load cell mechanism was run up, the front wire harness would pull the steel movable sled over the top of the fixed steel horizontal table.

6. A sample fiber pad was placed on sandpaper taped to a stationary steel horizontal table.

7. The second fiber mat was placed on top of the first fiber mat, which ran longitudinally along the length, the length of the fixed steel horizontal table.

8. A steel movable sled was placed on top of the top fiber mat and a steel weight was placed on top of the steel movable sled.

9. The universal tensile/compressive tester was set up so that the crosshead and load cell traveled at a rate of 150mm/min and the length of travel was 150 mm.

10. The top fiber mat was tested in the forward direction oriented and then rotated 180 degrees and the test repeated so that the mat was tested twice in the opposite direction.

11. The top fiber mat is turned over and then step 10 is repeated.

12. Static and dynamic friction forces were recorded and reported as described above, and the coefficient of friction was calculated.

The coated staple fibers of the present invention can exhibit the following fiber-to-fiber staple pad coefficient of friction: at least 0.20, or at least 0.25, or at least 0.30, and desirably at least 0.35, or at least 0.4, or at least 0.45, or at least 0.55, or at least 0.6, and/or not more than about 0.9, or not more than 0.85, and desirably not more than 0.80, or not more than 0.75, or not more than 0.70, or not more than 0.65, or not more than 0.6, or not more than 0.55. A problem with staple fibers having a fiber-to-fiber staple pad friction of greater than 0.9 is that the fibers are prone to breakage, increasing the staple fiber content, and below 0.2, the sliver is not formable, or the sliver has poor integrity and cannot be twisted or drawn.

Additionally or alternatively, the coated staple fibers can exhibit a coefficient of friction of fiber-to-metal staple pad friction of at least about 0.10, 0.15, 0.20, or 0.25, and/or not greater than about 0.55, 0.50, 0.45, 0.40, 0.35, or 0.30, as measured as described in U.S. patent No. 5,683,811, the entire disclosure of which is incorporated herein by reference to the extent not inconsistent with the description herein.

In one embodiment, the CA staple fibers contained in the carded sliver, spun yarn and woven fabric have an untwisted F/F CODF (also known as fiber-to-fiber sliding friction) of between 0.11 and 0.20, as measured by ASTM D3412/3412M-13 on filament yarns. To determine the F/F CODF of the fibers of the sliver, uncrimped continuous filaments were formed having the same composition, denier, shape and CPI as the filaments used to make the CA staple fibers, or if available, using continuous filaments used to make the CA staple fibers, and formed into filament yarns and conditioned at 70 ° F and 65% relative humidity for 24 hours prior to testing. Filament yarns were measured according to ASTM D3412/3412M-13, except that only 1 twist was used, the speed was 20M/min, and in the ASTM procedure the yarns were tested on an electronically driven Constant Tension conveyor (CTT-E) set according to FIG. 1, with an input Tension of 10 grams. The value obtained by this method is considered to be the F/F CODF of the CA staple fibers in the sliver.

If the F/F CODF of the sliver is below 0.11, the sliver is likely to fail to retain its integrity during drawing and will be stretch broken, particularly if more than 10 wt% CA staple fibers are used in the blend of staple fibers. If the F/F CODF of the sliver is greater than 0.20, the draw-down process will tend to exceed the tenacity of the sliver, especially as the CA staple content increases. Desirably, the F/F CODF is from 0.11 to 0.20, or from 0.11 to less than 0.20, or from 0.11 to 0.19, or from 0.11 to 0.18, or from 0.11 to 0.17, or from 0.11 to 0.16, or from 0.11 to 0.15, or from 0.12 to 0.20, or from 0.12 to less than 0.20, or from 0.12 to 0.19, or from 0.12 to 0.18, or from 0.12 to 0.17, or from 0.12 to 0.16, or from 0.12 to 0.15.

In addition to having the desired F/F CODF, the CA staple fibers contained in carded sliver, spun yarn and woven fabrics are also desired to have a fiber-to-metal dynamic coefficient of friction (F/M CODF) measured on the filament yarn of less than 0.80. To determine the F/M CODF of sliver fibers, continuous filaments used to make CA staple fibers were formed into filament yarns, conditioned at 70F and 65% relative humidity for 24 hours, measured according to ASTM D3108/D3108M-13 at 100M/min, 10 grams input tension, on a CTT-E instrument set up according to FIG. 2 under the procedure ASTM D3412/3412M-13.

In many of the sliver to yarn stages (including the carding, draw, roving and spun yarn stages), friction is applied by fiber-metal contact. These frictional forces can cause fibrillation of the fibers and weakening of the fibers to the point of breakage, resulting in increased staple fiber content and in some cases sliver breakage, especially at higher CA staple fiber content. Desirably, the F/M CODF is no greater than 0.70, or no greater than 0.65, or no greater than 0.60, or no greater than 0.59, or no greater than 55, or no greater than 0.52, or no greater than 0.50, or no greater than 0.48, or no greater than 0.47. Desirable ranges include 0.30 to 0.80, or 0.30 to 0.70, or 0.30 to 0.65, or 0.30 to 0.60, or 0.40 to 0.80, or 0.40 to 0.70, or 0.40 to 0.65, or 0.40 to 0.60, or 0.45 to 0.80, or 0.45 to 0.70, or 0.45 to 0.65, or 0.45 to 0.60, or 0.48 to 0.80, or 0.48 to 0.70, or 0.48 to 0.65, or 0.48 to 0.60, or 0.50 to 0.80, or 0.50 to 0.70, or 0.50 to 0.65, or 0.50 to 0.60.

Static electricity can be a nuisance to users of woven fabrics and can cause processing problems in the production of spun yarns and woven fabrics. Since moisture is an excellent antistatic agent, the problem of static electricity accumulation is particularly pronounced if the fibers are hydrophobic. In most dry-woven fabric processes, the fibers and fabric move at high speeds over various surfaces and against each other, which creates triboelectric charges resulting from frictional forces. The build-up of static electricity on the fibers tends to repel the fibers from each other, resulting in reduced sliver cohesion and other downstream processing problems in yarn spinning. In addition, static charges will affect fabric material handling, can be troublesome for consumers handling tight fitting garments, and can cause small electric shocks when walking on carpets, even under conditions of moderate to high humidity.

Thus, in one embodiment, which may include the above-described F/F CODF and/or F/M CODF, CA staple fibers used to make sliver from carded staple fibers have an electrostatic charge of less than 1.0 at 65% relative humidity. The electrostatic charge on the CA staple fibers will affect the sliver cohesiveness by reducing the fiber-to-fiber repulsion force, thereby preserving the sliver cohesiveness. When the filaments used to make staple fibers for sliver have an electrostatic charge of less than 1.0, sliver and carded staple fibers are considered to be made from CA staple fibers having an electrostatic charge of no greater than 1.0. The test method for determining the static charge of the CA staple fibers used to make the sliver is as follows. The samples were filament yarns used to make staple fibers in the sliver. The filament yarns were exposed to a controlled environment of 65% relative humidity and 70 ° F for 24 hours to condition the filament yarns. Two (2) foot sections of filament yarn were held at one end and the other end held by hand while rubbing the fixed sections of filament back and forth with the sides of a wooden No. 2 pencil for 3 cycles along the entire 2 foot section. The electrostatic charge imparted to the filaments was measured using a Simco electrostatic analyser model FMX-003, or equivalent device.

Desirably, the electrostatic charge is no greater than 1.0, or no greater than 0.98, or no greater than 0.96, or no greater than 0.90, or no greater than 0.85, or no greater than 0.80, or no greater than 0.78, or no greater than 0.75, or no greater than 0.70, or no greater than 0.68, or no greater than 0.58, or no greater than 0.60, or no greater than 0.58, or no greater than 0.55, or no greater than 0.50.

In addition to cut length, filament shape and denier, the F/F CODF, F/M CODF and electrostatic charge on the CA staple fibers can also be affected by the finish applied on the filaments used to make the CA staple fibers. The finish applied to the CA filaments, also referred to as "fiber finish" or "spin finish", refers to any suitable type of coating when applied to the fiber filaments:

1. varying the friction exerted by and on the fibres and the ability of the fibres to move relative to each other and/or relative to the metal surface, or

2. Reducing the build-up of static electricity on the fibres, or

3. Both of which are present.

Desirably, at least one finish should be applied to the fibers to alter the fiber-to-fiber and, optionally, the fiber-to-metal coefficient of friction. The same finish may also have antistatic properties, or a second antistatic finish may be applied.

Finishes, unlike binders, or other similar chemical additives, when added to fibers, prevent movement between fibers by adhering the fibers to one another. When the finish is applied, the finish continues to allow the fibers to move relative to each other and/or relative to other surfaces, but the ease of such movement can be altered by increasing or decreasing the friction.

Thus, it is desirable that the CA staple fibers have a coating that alters the F/F CODF within specified limits as compared to the same, but uncoated, fibers. While a relatively high CPI does give a measure of fiber-to-fiber dynamic friction, more friction is required when the staple fibers are formed into sliver and spun yarn because higher cohesive energy is required to give the sliver the necessary integrity and to give the spun yarn elongation and tenacity. Additionally, as noted above, fibers for use in and formed into sliver require a larger F/F CODF relative to fibers used in or for making many nonwoven applications.

A finish that imparts a reinforced fiber-to-fiber static and dynamic coefficient of friction and enhanced resistance to static buildup applied in one step is desirable so that only one application of finish to the fibers is required. However, the staple fibers may include at least two finishes that are applied to all or a portion of the surface of the staple fibers at one or more points in the fiber production process in one or more steps. When two or more finishes are applied to the fibers, the finishes (as a blend of two or more different finishes) may be applied in one step, or the finishes may be applied separately at different steps/locations in the process. For example, in some cases, the staple fibers may be at least partially coated with a spinning finish (spinning or spinfinish) applied to the filaments as or between filament spins and prior to crimping to facilitate the foregoing filament spinning and/or crimping steps. Finishes, including antistatic finishes, may be added to the fibers during the filament spinning step, or between fiber spinning and filament gathering into bundles. Additionally or alternatively, the finish (which may include an antistatic finish) may be applied at the time of filament spinning or at any point after filament spinning and before the cutting step, and may be applied to individual filaments, bundles, or tow bands.

Any suitable method of applying the finish may be used and may include, for example, spraying, wicking (wick) application, dip coating or the use of a squeeze roll, a kiss roll or a fountain roll.

The cumulative amount of all finish applied will depend on the type of finish, fiber denier, cut length, and type of CA used, which will impart F/F CODF to CA staple fibers and an electrostatic charge within the above limits. When used, the finish can be of any suitable type and can be present on the filaments, tow bands, CA staple fibers, which are present in the sliver and spun yarn in an amount of finish-on-yarn (FOY) relative to the weight of dry CA fibers as follows: at least about 0.05%, or at least 0.10%, or at least 0.15%, or at least 0.20%, or at least 0.25%, or at least 0.30%, or at least 0.35%, or at least 0.40%, or at least 0.45%, or at least 0.50%, or at least 0.55%, or at least 0.60%. Additionally or alternatively, the cumulative amount of finish can be present as the amount of Finish (FOY) on the following yarns, based on the total weight of dry fiber: less than 2.0%, or not more than 1.8%, or not more than 1.5%, or not more than 1.2%, or not more than 1.0%, or not more than 0.9%, or not more than 0.8%, or not more than 0.7%. The amount of finish (in wt%) on the fiber can be determined by solvent extraction. As used herein, "FOY" or "on-yarn finish" refers to the amount of finish on the yarn minus any added water, and in this context, the yarn does not refer to spun yarn, but rather to CA tow bands, which would represent the amount on the CA staple fibers and be the same as the amount on the CA staple fibers, and in the context of the sliver concerned, the percentage would be based on the CA staple fibers in the sliver. One or two or more types of finish may be used. Desirably, the cumulative amount of finish on the fiber is from 0.10 to 1.0, or from 0.10 to 0.90, or from 0.10 to 0.80, or from 0.10 to 0.70, or from 0.15 to 1.0, or from 0.15 to 0.90, or from 0.15 to 0.80, or from 0.15 to 0.70, or from 0.20 to 1.0, or from 0.20 to 0.90, or from 0.20 to 0.80, or from 0.20 to 0.70, or from 0.25 to 1.0, or from 0.25 to 0.90, or from 0.25 to 0.80, or from 0.25 to 0.70, or from 0.30 to 1.0, or from 0.30 to 0.90, or from 0.30 to 0.80, or from 0.30 to 0.70, each expressed as% FOY.

The antistatic finish may be a cationic, nonionic or anionic finish and may be in the form of a solution, emulsion or dispersion. The antistatic finish may be an aqueous emulsion, which may or may not include any type of hydrocarbon, oil (including silicone oil), wax, alcohol, glycol, or siloxane. The particular type of antistatic finish applied to the filaments or fibers may depend, at least in part, on the end application in which the staple fibers will be used. Examples of suitable antistatic finishes can include, but are not limited to, phosphates, sulfates, ammonium salts, and combinations thereof. Other components, such as surfactants, may also be present in minor amounts in order to enhance the stability and/or processability of the finish and/or to make it more suitable for the intended end use of the fiber (e.g., non-irritating when the fiber is in contact with the user's skin). Additionally, depending on the end use of the CA staple fibers, the finish may comply with federal and state regulations and may be approved, for example, by non-animal subject 65 (position 65) and/or FDA food contact.

The antistatic finish will affect the interaction of the coated fibers with water by changing the hydrophilicity of the uncoated fibers to make them more hydrophilic. The use of an antistatic finish can impart additional moisture to the fibers themselves. In some embodiments, the addition of the antistatic finish results in the addition of the following amounts of moisture to the fiber: at least 0.05%, or at least 0.1%, or at least 0.15%, or at least 0.20%, or at least 0.30%, or at least 0.50%, or at least 0.80%, and at most 1.5%, or at most 1.0%.

Carded sliver made with the CA staple fibers of the present invention desirably has a low coefficient of variation. Carded sliver made with other synthetic fibers typically have thick and thin spots along the length of the sliver, which manifests itself as a weight change along the unit length of the resulting spun yarn. Carded sliver with low coefficient of variation will be uniform, made from fibers with fairly uniform crimp frequency and finish, and have good coefficient of friction. The coefficient of variation (CVm) of a sliver containing CA staple fibers described herein can be: not greater than 4.5%, or not greater than 4.2%, or not greater than 4.1%, or not greater than 4.0%, or not greater than 3.8%, or not greater than 3.7%, or not greater than 3.6%, as measured on a 12mm section of sliver (over 250 linear codes) according to ASTM D1425 "textile strand unevenness measured using capacitive test equipment" test method.

Examples of typical ranges of CVm values are (in each case expressed in percentages): 1 to 4.5, or from 1.5 to 4.5, or from 2 to 4.5, or from 2.5 to 4.5, or from 2.8 to 4.5, or from 2.9 to 4.5, or from 3.0 to 4.5, or from 3.1 to 4.5, or from 3.2 to 4.5, or from 3.3 to 4.5, or from 3.4 to 4.5, or from 3.5 to 4.5, or from 3.6 to 4.5, or from 3.7 to 4.5, or from 3.8 to 4.5, or from 3.9 to 4.5, or from 1 to 4.2, or from 1.5 to 4.2, or from 2 to 4.2, or from 2.5 to 4.2, or from 2.8 to 4.2, or from 2.9 to 4.2, or from 3.0 to 4.5, or from 1.4.3 to 4.2, or from 1.5 to 4.2, or from 1.4.5 to 4.2, or from 1.8 to 4.2, or from 3.2, or from 1 to 4.2, or from 3.9 to 4.2, or from 3, or from 1.4, or from 3.5 to 4.5 to 4, or from 1, or from 3.4, or from 1 to 4, or from 3, or from 1, 4, or from 3, or from 2 to 4, or from 3, 4, or from 1, or from 2 to 4, or from 3, 4, or from 2 to 4, or from 3,2, or from 1, 4, 2 to 4, or from 3, 4, or from 3,2 to 4, or from 3, or from 2 to 4, or from 1, or from 4, 2 to 4, or from 3, 4, or from 1, 4, 2 to 4, or from 2, or from 4, 2, or from 3, or, or from 3.6 to 4.1, or from 3.7 to 4.1, or from 3.8 to 4.1, or from 3.9 to 4.1, or from 1 to 4.0, or from 1.5 to 4.0, or from 2 to 4.0, or from 2.5 to 4.0, or from 2.8 to 4.0, or from 2.9 to 4.0, or from 3.0 to 4.0, or from 3.1 to 4.0, or from 3.2 to 4.0, or from 3.3 to 4.0, or from 3.4 to 4.0, or from 3.5 to 4.0, or from 3.6 to 4.0, or from 3.7 to 4.0, or from 3.8 to 4.0, or from 3.9 to 4.0, or from 1 to 3.8, or from 1.5 to 3.8, or from 3.7 to 3.0, or from 3.3 to 3.8, or from 3.7 to 3, or from 3.8, or from 3 to 3.7 to 3, or from 3, or from 3 to 4, or from 3, or from 3, to 4, or from 3, or from 3,8 to 4, or from 3, or from 3, or from 3, to 4, or from 3, or from 3, to 4, or from 3, or from 3.3 to 3.7, or from 3.4 to 3.7, or from 3.5 to 3.7, or from 3.6 to 3.7, or from 1 to 3.6, or from 1.5 to 3.6, or from 2 to 3.6, or from 2.5 to 3.6, or from 2.8 to 3.6, or from 2.9 to 3.6, or from 3.0 to 3.6, or from 3.1 to 3.6, or from 3.2 to 3.6, or from 3.3 to 3.6, or from 3.4 to 3.6, or from 3.5 to 3.6.

Due to the good fiber-to-fiber cohesion energy of the sliver, the short fiber content of the sliver can be minimized. Staple fibers are fibers less than 1/2 inches long. The carded sliver may be made with staple fibers in an amount (in wt% in each case) of no greater than 30%, or no greater than 28%, or no greater than 26%, or no greater than 25%, or no greater than 23%, or no greater than 20%, or no greater than 18%, or no greater than 15%, or no greater than 13%, or no greater than 10%, or no greater than 8%, or no greater than 6%, or no greater than 5%, or no greater than 4%, as determined by using a Keisokki fiber length distribution tester. The tester measures the fiber clusters or whiskers clamped to the sample comb by optical methods and automatically plots the fiber length distribution of the sample from the fiber plot.

Alternatively, the carded sliver may be made with staple fibers in an amount (in wt% in each case) of no greater than 30%, or no greater than 28%, or no greater than 26%, or no greater than 25%, or no greater than 23%, or no greater than 20%, or no greater than 18%, or no greater than 15%, or no greater than 13%, or no greater than 10%, as determined by using the Uster AFIS test method. This test method is more disruptive to the fiber than the Keisokki fiber length distribution tester and will artificially generate additional short fibers, but even under this test method the short fiber content may be below 30 wt%, or below 25 wt%, or below 20 wt%, or below 15 wt%.

The CA staple fibers used in the sliver desirably exhibit high tenacity to avoid breaking and forming staple fibers during carding and drawing. For example, in some embodiments, the CA staple fibers used to make sliver, spun yarn, and woven fabrics can exhibit a tenacity of at least about 0.80, or at least about 0.85, or at least about 0.90, or at least about 0.95, or at least about 1.0, or at least about 1.05, or at least about 1.1, or at least about 1.15, or at least about 1.20, or at least about 1.25, or at least about 1.30 grams-force per denier (g/denier), and/or not greater than 2.50, or not greater than 2.45, or not greater than 2.40, or not greater than 2.35, or not greater than 2.30, or not greater than 2.25, or not greater than 2.20, or not greater than 2.15, or not greater than 2.10, or not greater than 2.05, or not greater than 2.00, or not greater than 1.95, or not greater than 1.90, or not greater than 1.85, or not greater than 1.80, or not greater than 1.75, or not greater than 1.70, or not greater than 1.65, or not greater than 1.60, or not greater than 1.55, or not greater than 1.45, or not greater than 1.40 g/denier, as measured according to ASTM D3822 for filaments (same staple fiber composition) used to make CA staple fibers, but not mixed with other fibers. Examples of suitable ranges of toughness for CA staple fibers include: 0.8 to 2.5, or 0.8 to 2.45, or 0.8 to 2.40, or 0.8 to 2.35, or 0.8 to 2.30, or 0.8 to 2.25, or 0.8 to 2.20, or 0.8 to 2.15, or 0.8 to 2.10, or 0.8 to 2.05, or 0.8 to 2.00, or 0.8 to 1.95, or 0.8 to 1.90, or 0.8 to 1.85, or 0.8 to 1.80, or 0.8 to 1.75, or 0.8 to 1.70, or 0.8 to 1.65, or 0.8 to 1.60, or 0.8 to 1.55, or 0.8 to 1.50, or 0.8 to 1.45, or 0.8 to 1.40, 0.9 to 2.5, or 0.8 to 2.45, or 0.9 to 1.0.5, or 0.0.0.0 to 1.5, or 0.0.0.0.9 to 1.0.0.0.0.0 to 1.5, or 0.9 to 1.0.0.9, 9 to 1.5, or 0.0.0.9 to 1.0.5, or 0.9 to 1.0.0.9 to 1.5, or 0.0.0.9 to 1.5 or 1.0.0.5, or 0.9 to 1.0.0.9 to 1.5, or 0.9 to 1.0.9 to 1.0, or 0 to 1.5, or 0.9 to 1.5, or 0.0.9 to 1.0.0.0.9 to 1.5, or 0.0.0.9 to 1.0.9 to 1.5, or 0.0, or 0.0.0.9 to 1.9 to 1.5, or 0.0.0, or 0.9 to 1.9 to 1.5, or 0.5, or 0.9 to 1.0.0, or 1.2 to 2.30, or 1.2 to 2.05, or 1.2 to 1.90, or 1.2o 1.70, or 1.3 to 2.5, or 1.3 to 2.30, or 1.3 to 2.15, or 1.3 to 2.00, or 1.3 to 1.85, or 1.3 to 1.70 grams per denier.

The elongation at break of the CA staple fibers used to make the sliver, spun yarn or woven fabric can be at least 10%, or at least 13%, or at least 15%, or at least 20%, or at least 25%, and/or not greater than about 50%, or not greater than 45%, or not greater than 40%, or not greater than 35%, or not greater than 30%, measured according to ASTM D3822. If the elongation at break is less than 10%, the sliver containing CA staple fibers will break more easily at normal draw ratios. CA staple fibers with an elongation at break of 10% to 13% are useful if they also have good tenacity. Examples of more desirable ranges include: 13 to 50, or 13 to 45, or 13 to 40, or 13 to 35, or 13 to 30, or 15 to 50, or 15 to 45, or 15 to 40, or 15 to 35, or 15 to 30, or 20 to 50, or 20 to 45, or 20 to 40, or 20 to 35, or 20 to 30, or 25 to 50, or 25 to 45, or 25 to 40, or 25 to 35, or 25 to 30.

CA staple fibers with high tenacity and elongation allow sufficient retention of sliver tenacity and elongation to allow them to be formed into sliver and drawn on a draw frame without breaking. CA staple fibers have higher or lower tenacity and elongation at break than the fibers with which they are blended. Therefore, the tenacity and elongation at break of the sliver and spun yarn will be affected by the blend ratio of the staple fibers. Sliver and spun yarn made with the CA staple fibers described herein have a tenacity retention of at least 50%, or at least 55%, or at least 60%, or at least 65%, or at least 70%, or at least 75%, as calculated by: tenacity of the blended sliver or yarn/tenacity of the sliver or yarn (made with 100% non-CA fibers used in the blend) x 100.

The CA staple fibers may include little or no plasticizer, even as compared to CA staple fibers having higher plasticizer levels, and will exhibit enhanced biodegradability under industrial, domestic, and soil conditions.

In some embodiments, the fibers of the present disclosure may include no more than 5 wt%, or no more than 4.5 wt%, or no more than 4 wt%, or no more than 3.5 wt%, or no more than 3 wt%, or no more than 2.5 wt%, or no more than 2 wt%, or no more than 1.5 wt%, or no more than 1 wt%, or no more than 0.5 wt%, or no more than 0.25 wt%, or no more than 0.10 wt%, or no more than 0.05 wt%, or no more than 0.01 wt% of a plasticizer (based on the total weight of the fiber), or the fibers may not include an added plasticizer. When present, the plasticizer may be incorporated into the fibers themselves by blending with a solvent spinning dope or cellulose acetate flakes, or the plasticizer may be applied to the surface of the fibers or filaments by spraying, by centrifugal force from a rotating drum device, or by dipping.

Examples of plasticizers that may be present (and desirably are not present) in or on the fibers can include, but are not limited to, aromatic polycarboxylates, aliphatic polycarboxylates, lower fatty acid esters of polyhydric alcohols, and phosphate esters. Other examples may include, but are not limited to: dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, dimethoxyethyl phthalate, ethyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, levulinate, dibutyrate of triethylene glycol, tetraethylene glycol, pentaethylene glycol, tetraoctyl pyromellitate, trioctyl trimellitate, dibutyl adipate, dioctyl adipate, dibutyl sebacate, dioctyl sebacate, diethyl azelate, dibutyl azelate, dioctyl azelate, glycerin, trimethylolpropane, pentaerythritol, sorbitol, triacetin (triacetin), glycerin tetraacetate, triethyl phosphate, tributyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, and tricresyl phosphate, and combinations thereof.

In addition, the CA staple fibers of the present invention may not be subjected to additional treatment steps aimed at enhancing the biodegradability of the fibers. For example, fibers as described herein are desirably not hydrolyzed or treated by enzymes or microorganisms. The fibers may include no greater than 1 wt%, or no greater than 0.75 wt%, or no greater than 0.5 wt%, or no greater than 0.25 wt%, or no greater than 0.1 wt%, or no greater than 0.05 wt%, or no greater than 0.01 wt% of a binder, or other modifier. In some embodiments, the fibers may not include any cohesiveness agents, binders, or modifiers, and may not be formed from any substituted or modified cellulose acetate. The modified cellulose acetate may comprise a cellulose acetate that has been modified with a polar substituent, such as a substituent selected from the group consisting of sulfate, phosphate, borate, carbonate, and combinations thereof.

Also provided are sliver or spun yarns that retain a substantial portion of their elongation at break through the use of CA staple fibers as described herein. The elongation at break retention can be at least 60%, or at least 65%, or at least 70%, or at least 75%, or at least 80%, or at least 90%, or at least 95%, and can even exceed the elongation at break of other blended fiber materials. The method used to calculate the elongation retention at break was: elongation at break of the blended sliver or yarn/elongation at break of sliver or yarn (made with 100% non-CA fibers used in the blend) x 100.

The spun yarn made from CA staple fiber may also have a break time of at least 0.5 seconds, or at least 0.6 seconds, or at least 0.65 seconds, or at least 0.70 seconds, or at least 0.75 seconds, measured using a spun yarn made from 100% CA staple fiber, according to ASTM2256 for testing purposes.

The spun yarn made from staple fibers may also have a breaking force, as measured according to ASTM2256 using a spun yarn made from 100% CA staple fibers, of at least 130g-N, or at least 140g-N, or at least 150g-N, and optionally at most 200g-N, or at most 190g-N, for testing purposes. Examples of suitable ranges of breaking force include, 130g-N to 200g-N, or 140g-N to 200g-N, or 150g-N to 200g-N, or 130g-N to 190g-N, or 140g-N to 190g-N, or 150g-N to 190 g-N.

Spun yarns made with CA staple fibers may also have a breaking force of at least 600, or at least 650, or at least 700. Additionally or alternatively, the yarn may have a force to break of at most 1200gFcm, or at most 1100gFcm, or at most 1000gFcm, or at most 900 gFcm. Force to break was measured using spun yarns made from 100% CA staple fibers for testing purposes according to ASTM 2256. Examples of suitable ranges include 600 to 1200gFcm, or 650 to 1200gFcm, or 700 to 1200gFcm, or 600 to 1100gFcm, or 650 to 1100gFcm, or 700 to 1100gFcm, or 600 to 1000gFcm, or 650 to 1000gFcm, or 700 to 1000 gFcm.

The spun yarn also exhibits high toughness. For example, in some embodiments, spun yarns made with CA staple fibers can exhibit a tenacity of at least about 0.80 gF/denier, or at least about 0.85 gF/denier, or at least about 0.90 gF/denier. Additionally or alternatively, the spun yarn may have a tenacity of at most 1.1 or 1.0 gF/denier. According to ASTM2256, for testing purposes, the tenacity of the spun yarn was measured using a spun yarn made from 100% CA staple fiber.

The elongation at break of the spun yarn containing CA staple fibers may be at least 10%, or at least 11%, or at least 12%, or at least 13%, or at least 15%. Additionally or alternatively, the elongation at break of the spun yarn may be at most 20%, or at most 15%, or at most 14%. According to ASTM2256, the elongation at break of the spun yarn was measured using a spun yarn made from 100% CA staple fiber for testing purposes.

The above values of tenacity and elongation to break can also be obtained on spun yarns having a twist multiplier (meaning the square root of twist per inch divided by english yarn count) of less than 4.0 and a total denier of less than 400 or even no more than 300. These values of tenacity and elongation at break described above are achievable on spun yarns having a twist multiplier of less than 4.0 or 3.6 or less and a total denier of no greater than 300 or no greater than 250.

The total denier of the spun yarn may be at least 100, or at least 125, or at least 150, and at most 1000, or at most 500, or at most 400, or at most 300, or at most 250. Suitable ranges include 100 to 1000, or 125 to 500, or 125 to 400, or 125 to 300, or 100 to 250.

Carded sliver, spun yarn and woven fabrics can be made with 100% CA staple fibers or can be blends of CA staple fibers with other fibers (non-CA staple fibers). The CA staple fibers may be present in sliver or spun yarn, or in an amount of at least 5 wt%, or at least 10 wt%, or at least 15 wt%, or at least 20 wt%, or at least 25 wt%, or at least 30 wt%, or at least 35 wt%, or at least 40 wt%, or at least 45 wt%, and up to 100 wt%, or up to 90 wt%, or up to 80 wt%, or up to 70 wt%, or up to 60 wt%, or up to 55 wt%, or up to 52 wt%, or up to 50 wt%, or up to 45 wt%, or up to 40 wt%, or up to 35 wt%, or up to 30 wt%, or up to 25 wt%, or up to 22 wt%, or up to 20 wt% (based on the total weight of the blend). The one or more other fibers may be present in an amount of at least about 5 wt%, or at least 10 wt%, or at least 15 wt%, or at least 20 wt%, or at least 25 wt%, or at least 30 wt%, or at least 35 wt%, or at least 40 wt%, or at least 45 wt%, or at least 50 wt%, or at least 55 wt%, or at least 60 wt%, or at least 65 wt%, or at least 70 wt%, or at least 75 wt%, or at least 80 wt%. The composition of a particular blend may be determined according to AATCC TM20A-2014 (No. 1). In sliver, spun yarn or woven fabric, examples of suitable ranges of CA staple fibers, based on the weight of all fibers in the sliver, spun yarn or woven fabric, include: 5 to 70 wt%, or 5 to 65 wt%, or 5 to 60 wt%, or 5 to 55 wt%, or 5 to 50 wt%, or 5 to 45 wt%, or 5 to 40 wt%, or 5 to 35 wt%, or 5 to 30 wt%, or 5 to 25 wt%, or 5 to 20 wt%, or 10 to 70 wt%, or 10 to 65 wt%, or 10 to 60 wt%, or 10 to 55 wt%, or 10 to 50 wt%, or 10 to 45 wt%, or 10 to 40 wt%, or 10 to 35 wt%, or 10 to 30 wt%, or 10 to 25 wt%, or 10 to 20 wt%, or 15 to 70 wt%, or 15 to 65 wt%, or 15 to 60 wt%, or 15 to 55 wt%, or 15 to 50 wt%, or 15 to 45 wt%, or 15 to 40 wt%, or 15 to 35 wt%, or 15 to 30 wt%, or 15 to 25 wt%, or 15 to 20 wt%, or 20 to 70 wt%, or 20 to 65 wt%, or 20 to 60 wt%, or 20 to 55 wt%, or 20 to 50 wt%, or 20 to 45 wt%, or 20 to 40 wt%, or 20 to 35 wt%, or 20 to 30 wt%, or 20 to 25 wt%.

Other types of fibers suitable for blending with CA staple fibers may include: natural and/or synthetic fibers (including, but not limited to, cotton, rayon, viscose) or other types of regenerated cellulose such as cuprammonium fibers, lyocell fibers, modal and lyocell, acetates such as polyvinyl acetate, wool, glass, polyamides including nylon, polyesters such as polyethylene terephthalate (PET), polycyclohexylenedimethylene terephthalate (PCT) and other copolymers, olefin polymers such as polypropylene and polyethylene, polycarbonates, polysulfates, polysulfones, polyethers, acrylics, acrylonitrile copolymers, polyvinyl chloride (PVC), polylactic acid, polyglycolic acid, and combinations thereof.

In some cases, the fibers may be monocomponent fibers, while in other cases, the fibers may be multicomponent fibers, including cellulose acetate with one or more other types of materials. Desirably, the fibers are monocomponent fibers.

Spun yarns formed from staple fibers may also exhibit desirable wicking properties. For example, in some embodiments, spun yarns and woven fabrics formed from CA staple fibers can have a wicking height of no greater than 200mm at 5 minutes. In some cases, the wicking height of the spun yarn as described herein can be no greater than about 175mm, 150mm, 125mm, 100mm, 90mm, 80mm, 70mm, 60mm, 50mm, 40mm, or 30mm, as measured as described in NWSP 010.1-7.3.

A woven fabric made from spun yarns containing the CA staple fibers of the present invention also maintained good pilling resistance in the woven fabric as determined by ASTM4970 using a Martindale tester. The woven fabric made with the CA staple fibers described herein can be either grade 4 or grade 5.

Staple fibers and nonwovens formed therefrom can be biodegradable, meaning that such fibers are expected to decompose under certain environmental conditions. Characterized by a degree of degradation that can be lost by weight of a sample exposed to certain environmental conditions over a given period of time. In some cases, the material (used to form the staple fibers, or woven fabrics produced from the fibers) may exhibit a weight loss of at least about 5%, 10%, 15%, or 20% after being buried in soil for 60 days, and/or may exhibit a weight loss of at least about 15%, 20%, 25%, 30%, or 35% after being exposed to typical municipal composters for 15 days. However, the degradation rate may vary depending on the particular end use of the fiber and the composition of the remaining article, as well as the specific testing. Exemplary test conditions are provided in U.S. patent 5,970,988 and U.S. patent 6,571,802.

CA staple fibers as described herein may exhibit enhanced levels of environmental non-durability characterized by better than expected degradation under various environmental conditions. The fibers and fibrous articles of the present invention meet or exceed the standards set by international test methods and authorities for industrial compostability, home compostability and/or soil biodegradability.

In order to be considered "compostable", the material must meet the following four criteria: (1) the material must be biodegradable; (2) the material must be disintegratable; (3) the material must not contain more than the maximum amount of heavy metals; and (4) the material must be ecologically nontoxic. As used herein, the term "biodegradable" generally refers to the tendency of a material to chemically decompose under certain environmental conditions. Biodegradability is an inherent property of a material itself, and a material may exhibit different degrees of biodegradability depending on the particular conditions to which it is exposed. The term "disintegratable" refers to the tendency of a material to physically break down into smaller pieces when exposed to certain conditions. Disintegration depends both on the material itself and on the physical size and configuration of the article tested. The effect of this material on plant longevity was measured using ecotoxicity, and the content of heavy metals in the material was determined according to the procedures specified in standard test methods.

According to ISO14855-1(2012), the CA staple fibers may exhibit a biodegradation of at least 70% over a period of no more than 50 days when tested under aerobic composting conditions at ambient temperature (28 ℃ ± 2 ℃). In some cases, when tested under these conditions, the CA staple fibers may exhibit at least 70% biodegradation over a period of no greater than 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, or 37 days, a condition also referred to as "home composting condition". These conditions may not be aqueous or anaerobic. In some cases, the CA staple fibers may exhibit a total biodegradation, according to ISO14855-1(2012), of at least about 71%, or at least 72%, or at least 73%, or at least 74%, or at least 75%, or at least 76%, or at least 77%, or at least 78%, or at least 79%, or at least 80%, or at least 81%, or at least 82%, or at least 83%, or at least 84%, or at least 85%, or at least 86%, or at least 87%, or at least 88%, when tested under home composting conditions for a period of 50 days. This may represent a relative biodegradation of at least about 95%, or at least 97%, or at least 99%, or at least 100%, or at least 101%, or at least 102%, or at least 103%, when compared to cellulose subjected to the same test conditions.

According to french standard NF T51-800 and australian standard AS 5810, in order to be considered "biodegradable" under home composting conditions, the material must exhibit a total biodegradation of at least 90% (e.g. compared to the initial sample) or at least 90% of the maximum degradation of a suitable reference material after both the reference and test items have reached a plateau. The maximum test duration for biodegradation under home compounding conditions was 1 year. The CA staple fibers described herein can exhibit at least 90% biodegradation, as measured according to 14855-1(2012) under home composting conditions, in no more than 1 year. In some cases, the CA staple fibers may exhibit a biodegradation of at least about 91, or at least 92, or at least 93, or at least 94, or at least 95, or at least 96, or at least 97, 9, or at least 8, or at least 99, or at least 99.5% within no more than 1 year, or the fibers may exhibit a biodegradation of 100% within no more than 1 year, as measured according to 14855-1(2012) under home composting conditions.

Additionally or alternatively, the fibers described herein may exhibit at least 90% biodegradation, as measured according to 14855-1(2012) under home composting conditions, for a period of time as follows: not greater than about 350 days, or not greater than 325 days, or not greater than 300 days, or not greater than 275 days, or not greater than 250 days, or not greater than 225 days, or not greater than 220 days, or not greater than 210 days, or not greater than 200 days, or not greater than 190 days, or not greater than 180 days, or not greater than 170 days, or not greater than 160 days, or not greater than 150 days, or not greater than 140 days, or not greater than 130 days, or not greater than 120 days, or not greater than 110 days, or not greater than 100 days, or not greater than 90 days, or not greater than 80 days, or not greater than 70 days, or not greater than 60 days, or not greater than 50 days. In some cases, the fiber may be at least about 97%, or at least 98%, or at least 99%, or at least 99.5% biodegradable in no more than about 70 days, or no more than 65 days, or no more than 60 days, or no more than 50 days, as tested according to ISO14855-1(2012) under home composting conditions. Thus, according to e.g. french standard NF T51-800 and australian standard AS 5810, CA staple fibers can be considered biodegradable when tested under home composting conditions.

The CA staple fibers can exhibit biodegradation of at least 60% over a period of no greater than 45 days when tested under aerobic composting conditions at a temperature of 58 ℃ (± 2 ℃) in accordance with ISO14855-1 (2012). In some cases, when tested under these conditions, also referred to as "industrial composting conditions," the fibers may exhibit at least 60% biodegradation over the following time period: no greater than 44 days, or no greater than 43 days, or no greater than 42 days, or no greater than 41 days, or no greater than 40 days, or no greater than 39 days, or no greater than 38 days, or no greater than 37 days, or no greater than 36 days, or no greater than 35 days, or no greater than 34 days, or no greater than 33 days, or no greater than 32 days, or no greater than 31 days, or no greater than 30 days, or no greater than 29 days, or no greater than 28 days, or no greater than 27 days. These conditions may not be aqueous or anaerobic. In some cases, the fibers may exhibit a total biodegradation of at least about 65%, or at least 70%, or at least 75%, or at least 80%, or at least 85%, or at least 87%, or at least 88%, or at least 89%, or at least 90%, or at least 91%, or at least 92%, or at least 93%, or at least 94%, or at least 95% when tested under industrial composting conditions for a period of 45 days according to ISO14855-1 (2012). This may represent a relative biodegradation of at least about 95%, or at least 97%, or at least 99%, or at least 100%, or at least 102%, or at least 105%, or at least 107%, or at least 110%, or at least 112%, or at least 115%, or at least 117%, or at least 119%, when compared to cellulosic fibers subjected to the same test conditions.

In order to be considered "biodegradable", under industrial composting conditions according to ASTM D6400 and ISO17088, at least 90% of the organic carbon (or for each ingredient present in an amount greater than 1% dry mass) in the entire article must be converted to carbon dioxide, or absolutely to carbon dioxide, at the end of the test period, compared to the control. According to european standard ED 13432(2000), the material must exhibit a total biodegradation of at least 90%, or after reaching a plateau for both reference and test items, to at least 90% of the maximum degradation of a suitable reference material. Under industrial complex conditions, the maximum test duration for biodegradability is 180 days. The CA staple fibers described herein can exhibit at least 90% biodegradation, as measured according to 14855-1(2012) under industrial composting conditions, in no more than 180 days. In some cases, the CA staple fibers may exhibit at least about 91%, or at least 92%, or at least 93%, or at least 94%, or at least 95%, or at least 96%, or at least 97%, or at least 98%, or at least 99%, or at least 99.5% biodegradation in no more than 180 days, or the fibers may exhibit 100% biodegradation in no more than 180 days, as measured according to 14855-1(2012) under industrial composting conditions.

Additionally or alternatively, the CA staple fibers described herein may exhibit at least 90% biodegradation, as measured according to 14855-1(2012) under industrial composting conditions, for the following time periods: not greater than about 175 days, or not greater than 170 days, or not greater than 165 days, or not greater than 160 days, or not greater than 155 days, or not greater than 150 days, or not greater than 145 days, or not greater than 140 days, or not greater than 135 days, or not greater than 130 days, or not greater than 125 days, or not greater than 120 days, or not greater than 115 days, or not greater than 110 days, or not greater than 105 days, or not greater than 100 days, or not greater than 95 days, or not greater than 90 days, or not greater than 85 days, or not greater than 80 days, or not greater than 75 days, or not greater than 70 days, or not greater than 65 days, or not greater than 60 days, or not greater than 55 days, or not greater than 50 days, or not greater than. In some cases, the CA staple fibers may be at least about 97%, 98%, 99%, or 99.5% biodegradable in not greater than about 65 days, or not greater than 60 days, or not greater than 55 days, or not greater than 50 days, or not greater than 45 days, tested according to ISO14855-1(2012) under industrial composting conditions. Thus, according to ASTM D6400 and ISO17088, the CA staple fibers described herein can be considered biodegradable when tested under industrial composting conditions.

The fibres or fibre products of the invention may exhibit a biodegradation in soil of at least 60% in no more than 130 days, measured under aerobic conditions at ambient temperature according to ISO 17556 (2012). In some cases, when tested under these conditions, also referred to as "soil composting conditions," the fibers may exhibit at least 60% biodegradation over the following time period: not greater than 130 days, or not greater than 120 days, or not greater than 110 days, or not greater than 100 days, or not greater than 90 days, or not greater than 80 days, or not greater than 75 days. These may not be aqueous or anaerobic conditions. In some cases, the fibers may exhibit a total biodegradation of at least about 65%, or at least 70%, or at least 72%, or at least 75%, or at least 77%, or at least 80%, or at least 82%, or at least 85% when tested under soil composting conditions for a period of 195 days according to ISO 17556 (2012). This may represent a relative biodegradation of at least about 70%, or at least 75%, or at least 80%, or at least 85%, or at least 90%, or at least 95% when compared to cellulosic fibers subjected to the same test conditions.

In order to be considered "biodegradable", according to

And DIN Gepr ü ft Biodegradable SOIL certification protocol (DIN Gepr ü ft Biodegradable in SOIL certification scheme) to DIN CERTCO, the material must exhibit a total of at least 90% biodegradation under SOIL composting conditions(e.g., as compared to the initial sample), or both the reference and test items reach a plateau, biodegradation is at least 90% of the maximum degradation of a suitable reference material. The maximum test duration of biodegradability under soil composite conditions is 2 years. The CA staple fibers described herein may exhibit at least 90% biodegradation, as measured under soil composting conditions according to ISO 17556(2012), in no more than 2 years, 1.75 years, 1 year, 9 months, or 6 months. In some cases, the CA staple fibers may exhibit a biodegradation of at least about 91, or at least 92, or at least 93, or at least 94, or at least 95, or at least 96, or at least 97, or at least 98, or at least 99, or at least 99.5% or the fibers may exhibit a biodegradation of 100% in no more than 2 years, measured under soil composting conditions according to ISO 17556 (2012).

Additionally or alternatively, the CA staple fibers described herein may exhibit at least 90% biodegradation, as measured according to 17556(2012) under soil composting conditions, in the following time periods: no greater than about 700 days, 650 days, 600 days, 550 days, 500 days, 450 days, 400 days, 350 days, 300 days, 275 days, 250 days, 240 days, 230 days, 220 days, 210 days, 200 days, or 195 days. In some cases, the CA short fibers may be at least about 97%, or at least 98%, or at least 99%, or at least 99.5% biodegradable in no more than about 225 days, or no more than 220 days, or no more than 215 days, or no more than 210 days, or no more than 205 days, or no more than 200 days, or no more than 195 days, tested under soil composting conditions according to ISO 17556 (2012). Thus, the CA staple fibers described herein are satisfactory for obtaining

Meets the requirements of the biodegradable soil qualification mark of DINCERTCO and meets the standards of DIN Gepr ü ft biodegradable soil certification scheme of DINCERTCO.

In some cases, the CA staple fibers (or fibrous articles) of the present invention can include less than 1 wt%, or not greater than 0.75 wt%, or not greater than 0.50 wt%, or not greater than 0.25 wt%, based on the weight of the CA staple fibers, of a component of unknown biodegradability. In some cases, the fibers or fibrous articles described herein may not include components with unknown biodegradability.

In addition to being biodegradable under industrial and/or home composting conditions, the CA staple fibers or fibrous articles described herein can also be compostable under home and/or industrial conditions. As previously mentioned, a material is considered compostable if it meets or exceeds the requirements set forth in EN 13432 for biodegradability, degradability, heavy metal content and ecotoxicity. The CA staple fibers or fibrous articles described herein may exhibit sufficient compostability to meet the needs of the consumer under domestic and/or industrial composting conditions

The requirement to obtain compostability (OK composition) and compostable Home compliance Mark (OK composition HOME compliance Mark).

In some cases, the volatile solids concentration, heavy metals and fluorine content of the CA staple fibers, fibers and fiber articles described herein may meet all requirements specified in EN 13432 (2000). In addition, the CA staple fibers did not negatively impact the compost quality (including chemical parameters and ecotoxicity testing).

In some cases, the CA staple fibers or fibrous articles may exhibit at least 90% disintegration in no more than 26 weeks, measured under industrial composting conditions according to ISO 169929 (2013). In some cases, the fiber or fibrous article may exhibit at least about 91, or at least 92, or at least 93, or at least 94, or at least 95, or at least 96, or at least 97, or at least 98, or at least 99, or at least 99.5% disintegration under industrial composting conditions for no more than 26 weeks, or the fiber or article may 100% disintegrate under industrial composting conditions for no more than 26 weeks. Additionally or alternatively, the fiber or article may exhibit at least 90% disintegration under industrial compounding conditions for no more than about 26 weeks, or no more than 25 weeks, or no more than 24 weeks, or no more than 23 weeks, or no more than 22 weeks, or no more than 21 weeks, or no more than 20 weeks, or no more than 19 weeks, or no more than 18 weeks, or no more than 17 weeks, or no more than 16 weeks, or no more than 15 weeks, or no more than 14 weeks, or no more than 13 weeks, or no more than 12 weeks, or no more than 11 weeks, or no more than 10 weeks, measured according to ISO 169929 (2013). In some cases, the CA staple fibers or fibrous articles described herein may disintegrate for at least 97%, or at least 98%, or at least 99%, or at least 99.5% in no more than 12 weeks, or no more than 11 weeks, or no more than 10 weeks, or no more than 9 weeks, or no more than 8 weeks, under industrial composting conditions, as measured according to ISO 169929 (2013).

In some cases, the CA staple fibers or fibrous articles may exhibit at least 90% disintegration, measured according to ISO 169929 (2013) under home composting conditions, in no more than 26 weeks. In some cases, the fiber or fiber article may exhibit at least about 91%, or at least 92%, or at least 93%, or at least 94%, or at least 95%, or at least 96%, or at least 97%, or at least 98%, or at least 99%, or at least 99.5% disintegration under home composting conditions in no more than 26 weeks, or the fiber or article may 100% disintegrate under home composting conditions in no more than 26 weeks. Additionally or alternatively, the fiber or article may exhibit at least 90% disintegration under home composting conditions, as measured according to ISO 16992 (2013), within the following time period: not greater than about 26, or not greater than 25, or not greater than 24, or not greater than 23, or not greater than 22, or not greater than 21, or not greater than 20, or not greater than 19, or not greater than 18, or not greater than 17, or not greater than 16, or not greater than 15 weeks. In some cases, the CA staple fibers or fibrous articles described herein can disintegrate at least 97%, or at least 98%, or at least 99%, or at least 99.5% in no more than 20 weeks, or no more than 19 weeks, or no more than 18 weeks, or no more than 17 weeks, or no more than 16 weeks, or no more than 15 weeks, or no more than 14 weeks, or no more than 13 weeks, or no more than 12 weeks, as measured according to ISO 169929 (2013) under home composting conditions.

The CA staple fibers of the present invention can achieve higher levels of biodegradability and/or compostability without the use of additives traditionally used to promote environmental non-durability of similar fibers. These additives may include, for example, photodegradants, biodegradants, decomposition promoters, and various types of other additives. Despite being substantially free of these types of additives, it has been unexpectedly found that CA staple fibers and articles exhibit enhanced biodegradability and compostability when tested under industrial, domestic and/or soil conditions, as previously described.

In some embodiments, the CA staple fibers described herein can be substantially free of photodegradants. For example, the fiber can include no greater than about 1 wt%, or no greater than 0.75 wt%, or no greater than 0.50 wt%, or no greater than 0.25 wt%, or no greater than 0.10 wt%, or no greater than 0.05 wt%, or no greater than 0.025 wt%, or no greater than 0.01 wt%, or no greater than 0.005 wt%, or no greater than 0.0025 wt%, or no greater than 0.001 wt% of the photodegradant, or the fiber can include no photodegradant, based on the total weight of the fiber. Examples of such photodegradants include, but are not limited to, pigments that act as photo-oxidation catalysts and are optionally augmented by the presence of one or more metal salts, oxidizable promoters, and combinations thereof. The pigment may comprise coated or uncoated anatase or rutile titanium dioxide, which may be present alone or in combination with one or more additional components such as, for example, various types of metals. Other examples of photodegradants include benzoin, benzoin alkyl ethers, benzophenones and derivatives thereof, acetophenones and derivatives thereof, quinones, thioxanthones, phthalocyanines and other photosensitizers, ethylene-carbon monoxide copolymers, aromatic ketone-metal salt sensitizers, and combinations thereof.

In some embodiments, the CA staple fibers described herein can be substantially free of a biodegrading agent and/or a disintegrating agent. For example, the fiber can include no greater than about 1 wt%, or no greater than 0.75 wt%, or no greater than 0.50 wt%, or no greater than 0.25 wt%, or no greater than 0.10 wt%, or no greater than 0.05 wt%, or no greater than 0.025 wt%, or no greater than 0.01 wt%, or no greater than 0.005 wt%, or no greater than 0.0025 wt%, or no greater than 0.0020 wt%, or no greater than 0.0015 wt%, or no greater than 0.001 wt%, or no greater than 0.0005 wt%, based on the total weight of the fiber, of the biodegrading agent and/or the disintegrating agent, or the fiber can include no biodegrading agent and/or the disintegrating agent. Examples of such biodegradation and decomposition agents include, but are not limited to: salts of oxyacids of phosphorus, esters of oxyacids of phosphorus or salts thereof, carbonic acid or salts thereof, oxyacids of phosphorus, oxyacids of sulfur, oxyacids of nitrogen, partial esters or hydrogenates of these oxyacids, carbonic acid and hydrogenates thereof, sulfonic acids and carboxylic acids.

Other examples of such biodegradation agents and decomposition agents include organic acids selected from the group consisting of oxo acids having 2 to 6 carbon atoms per molecule, saturated dicarboxylic acids having 2 to 6 carbon atoms per molecule, and lower alkyl esters of said oxo acids or said saturated dicarboxylic acids with alcohols having 1 to 4 carbon atoms. The biodegradation agent may also include enzymes such as, for example, lipases, cellulases, esterases and combinations thereof. Other types of biodegradants and disintegrants may include cellulose phosphate, starch phosphate, dibasic calcium phosphate, tribasic calcium phosphate, calcium hydroxide phosphate, glycolic acid, lactic acid, citric acid, tartaric acid, malic acid, oxalic acid, malonic acid, succinic anhydride, glutaric acid, acetic acid, and combinations thereof.

The CA staple fibers of the present invention may also be substantially free of several other types of additives that have been added to other fibers to promote environmental non-durability. Examples of such additives can include, but are not limited to, polyesters (including aliphatic and low molecular weight (e.g., less than 5000) polyesters), enzymes, microorganisms, water-soluble polymers, modified cellulose acetates, water-dispersible additives, nitrogen-containing compounds, hydroxy-functional compounds, oxygen-containing heterocyclic compounds, sulfur-containing heterocyclic compounds, anhydrides, monoepoxides, and combinations thereof. In some cases, the fibers described herein can include not greater than about 0.5 wt%, or not greater than 0.4 wt%, or not greater than 0.3 wt%, or not greater than 0.25 wt%, or not greater than 0.1 wt%, or not greater than 0.075 wt%, or not greater than 0.05 wt%, or not greater than 0.025 wt%, or not greater than 0.01 wt%, or not greater than 0.0075 wt%, or not greater than 0.005 wt%, or not greater than 0.0025 wt%, or not greater than 0.001 wt% of these types of additives, or the CA staple fibers can not include any of these types of additives.

The following examples are presented to illustrate the present invention and to enable any person skilled in the art to make and use the invention. It should be understood, however, that the invention is not limited to the specific conditions or details described in these examples. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art.

Examples of the invention

Example 1

The feasibility of successfully making 100% cellulose acetate spun yarns from low denier, high CPI, round CA staple fibers was investigated. The success of the test for making sliver and spun yarn from 100% CA staple fiber is predictive of the effect of this fiber in blended sliver.

A CA staple tow having 1.8 denier fibers, 17CPI, and a circular cross-section was produced and coated with a Pulcra Stantex 2098 finish in an amount of 0.5% FOY. A100 pound sample of tow was collected and cut into 38mm drawn staple lengths with 0.5% FOY PM lubricant (PM 30419) commercially available from Eastman added prior to cutting. During the experiment, the yarn spinning conditions were maintained at-55% humidity. The staple fibers are carded, drawn, roving and ring spun.

For initial proof of concept, staple fibers were successfully spun into six 2 pound packages of 20 singles yarns (250 denier) at 4.2 twist. However, this resulting yarn had a low tenacity of 0.7 g/denier and a low elongation of about 11%, as measured according to ASTM D-2256. The low tenacity and elongation values are a reflection of the low cohesion between the staple fibers, which makes them easily slide past each other when drawing the yarn. In addition, a higher multiple twist of 4.2 (typical twist multiples for knit yarns are 3.5 to 3.9) must be used to overcome the low cohesion between fibers, since the initial target 30 singles (150 denier) with 3.5 twist multiples are too weak to be successfully spun into a yarn.

Example 2

In this example, the effect of CPI, shape and finish on the combing and spinning performance of staple fibers was evaluated. The variables studied were 8, 12 and 18CPI, while the fiber shapes studied were round and trilobal, the two secondary spin finishes compared were PM 30149 and Pulcra Tow (E8-0.5%), and Stantex H1385 available from Pulcra, as summarized in table 1. After extrusion, before crimping, a primary spin finish is applied to the fibers and a secondary spin finish is applied to the tow band prior to cutting. The amounts of primary finish and secondary finish are listed in table 1. The staple fibers had a cut length of 38mm and a denier of 1.8.

TABLE 1

The samples were all subjected to a carding operation, however, only samples 3 and 6 were successfully converted to carded sliver, drawn and converted to roving, and finally spun into yarn.

Samples 3 and 4 have the same CPI and finish. Samples 5 and 6 also had the same CPI and finish. However, only circular samples 3 and 6 could be successfully spun into yarns. Surprisingly, none of the samples with trilobal cross-section could be successfully combed into a viable sliver, as determined by the inability to produce a carded sliver with sufficient cohesion and static properties.

Example 3

This example demonstrates successful yarn spinning using the CA staple fibers of the invention alone and blended with other fibrous materials.

The CA staple fibers and all other synthetic staple fibers had a denier of about 1.5 and were cut to a staple length of 38 mm. For cotton, upland cotton was used. The synthetic fibers were intimately blended while acetate/cotton blending was performed on a draw frame.

For 100% acetate spun yarn, a round 1.65DPF bright tow (no TiO2), 16CPI tow band was made with 0.7% AY23 as the main spin finish. The fibers from the tow band were used to make the samples listed in table 2 to produce 29/1 spun yarns. Tow samples were cut with a target of 1.5% using AY23 or Lurol 7414K as a second spin finish. The cut length of the staple was 38 mm. The coefficient of rupture was determined as a function of hank strength and yarn count from the product of the count strength according to ASTM D1576.

ASTM 1576 measures the breaking strength of a yarn in hank form, which translates into hank breaking coefficient (the product of the count strength) in terms of yarn count, while ASTM2256 provides breaking strength and elongation using the single strand method. The skein method can be used for spun yarns because it provides an average of the strands in the skein, overcoming the non-uniformity inherent in spun yarns. ASTM 1576 is rarely, if ever, used for filament yarns because the uniformity of filament yarns makes it possible to economically obtain reliable results by a single strand process (ASTM 2256).

For 100% spun yarn containing cellulose acetate, the hank breakage factor (the product of the count strength) should be equal to or greater than 1100.

TABLE 2

¹The breaking coefficient is measured on skeins and is not generally used for filament yarns, but is used for illustration purposes to show the difference in relative strength of the filaments versus 150 denier filament acetate (considered as weak yarns). The relative strength of the 100% synthetic yarn is in accordance with the range expected by industry standards.

Both samples of CA staple fibers were made into sliver and successfully spun into yarn. Both samples were made into sliver. A sample of CA staple fibers containing a Lurol 7414K finish was used as CA staple fibers blended with other fibrous materials.

Synthetic blended yarns (acetate/nylon, and acetate/polyester) were made by intimately blending 50/50 weight ratios of the two fibers (by weight) in a hopper before a fine opener. No problems were found during carding, drawing, roving or spinning. Since the specific density affects the sliver weight, the specific density needs to be considered and needs to be adjusted to reach the target sliver weight. The final yarn target was 29/1 based on the best balance obtained using the Lurol acetate 7414K sample as a matching standard. To achieve an acceptable breaking coefficient of 29/1 (1181), a twist multiplier of 3.8 was used based on the results of the twist curve, with the strength of the twist multiplier optimized to balance activity (knittability and hand in the final fabric) with strength. All yarn properties were determined according to ASTM 2256. Table 3 summarizes the yarn properties.

TABLE 3

Example 4

This example evaluates the effectiveness of various finishes on F/F CODF and F/M CODF and the build-up of static electricity on continuous filaments that would have similar values when cut into staple fibers.

Uncrimped CA continuous fibers were produced on a pilot scale single strand box and wound on bobbins. The yarn had a total denier of 1600g/9000m and a dpf of 1.80. The amount of finish is listed in table 4 below, and the finish is applied at a 2% emulsion level. With no other finish lubricants applied, other than the finishes described in table 4, the yarn package was conditioned at 70 ° F ± 2 ° F and 65% ± 4% relative humidity for 24 hours prior to testing. The F/M CODF was measured on an electronically driven constant tension transmitter (CTT-E) instrument set up according to FIG. 2 under an input tension of 100M/min and 10 grams according to ASTM D3108/D3108M-13, in the procedure of ASTM D3412/3412M-13. The F/F CODF was measured according to ASTM D3412/3412M-13, except that it was possible to use only 1 twist instead of 3 twists due to the strength of the fiber, and it was done at 20M/min instead of 0.2M/min due to equipment limitations. In the ASTM procedure, the yarn was tested on CTT-E set up according to fig. 1 and had an input tension of 10 grams.

Static electricity was measured as follows: for each package, a 2 foot section of yarn was secured at one end, and the fiber was then rubbed back and forth three times along the full length with a pencil and the resulting electric field was measured using a Simco electrostatic analyser model FMX-003. The measurements were performed under ambient conditions.

TABLE 4

Lurol 6511 has the lowest CODF and the lowest electrostatic charge for F/M and F/F-approximately zero. Lurol 7414K has a downward trend for both F/M and F/F, but F/F is steeper. Other lubricants were generally flat and comparable to each other, although Stantex 2098 did show a slight downward trend. With the exception of Lurol 6511, all spin finishes were not statistically significantly different from each other in controlling static.

As used herein, the term "comprising" is an open transition term used to transition from a subject recited before the term to one or more elements recited after the term, wherein the element or elements listed after the transition term are not necessarily the only elements that make up the subject.

As used herein, the term "comprising" has the same open-ended meaning as "comprising".

As used herein, the term "having" has the same open-ended meaning as "comprising".

The terms "a", "an", "the" and "the" as used herein mean one or more.

As used herein, the term "and/or," when used in a list of two or more items, means that any one of the listed items can be employed alone, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B and/or C, the composition may contain a alone a; b alone; c alone; a combination of A and B; a combination of A and C; b and C in combination; or a combination of A, B and C.

The preferred forms of the invention described above are to be used as illustration only, and should not be used in a limiting sense to interpret the scope of the invention.

Claims

1. A carded sliver comprising cellulose acetate staple fibers (CA staple fibers) having a circular shape, a denier of less than 3.0, a crimp frequency per inch (CPI) of 5 to 30, and wherein the sliver has a fiber-to-fiber cohesion energy of at least 10,000 joules.

2. A carded sliver according to claim 1, wherein the CA staple fibers have an uncrimped fiber-to-fiber dynamic coefficient of friction (F/F CODF) of friction of between 0.11 and less than 0.2, measured at a rate of 20M/min at one twist and at an input tension of 10 grams on the filaments used to make the CA staple fibers according to ASTM D3412/3412M-13.

3. The carded sliver of any one of claims 1-2, wherein the CA staple fibers have an electrostatic charge of less than 1.0kV at 65% relative humidity, measured using an electrostatic analyzer rubbed three times back and forth over a two foot sample length of filament used to make the CA staple fibers.

4. A carded sliver according to any one of claims 1-3, wherein the sliver has a coefficient of variation (CVm) of not more than 4.5% or not more than 4%.

5. The carded sliver of any one of claims 1-4, wherein the sliver has a short fiber content of not greater than 15% (less than 1/2 inches) as determined by a Keishokki fiber length distribution tester.

6. A carded sliver according to any of claims 1-5, wherein at least 10 wt% and at most 55% of the staple fibers in the sliver are CA staple fibers, and wherein the CA staple fibers are coated with a finish.

7. The carded sliver of any one of claims 1-6, wherein the CA staple fibers have a denier of 0.5 to 1.9, a CPI of 8 to 19, and wherein the cellulose acetate used to make the fibers has a degree of acetyl substitution of at least 2.2.

8. Carded sliver according to any one of claims 1-7, wherein the CA staple fibers have a CPI to DPF ratio of 6:1 to 14: 1.

9. A carded sliver according to any one of claims 1-8, wherein at least 90% of the CA staple fibers have a form factor of 1.0 to 1.5.

10. A carded sliver according to any one of claims 1-9, wherein at least 90 wt% of the CA staple fibers have a cut length of 10 to 150 mm.

11. A carded sliver according to any one of claims 1-10, wherein the CA staple fibers are coated with a finish in an amount of less than 2.0 wt% FOY on a dry weight basis.

12. A carded sliver according to any one of claims 1-11, wherein the CA staple fibers have a tenacity of at least 0.9 grams-force/denier, measured according to ASTM D3822, or are made from filaments having a tenacity of at least 0.9 grams-force/denier, measured according to ASTM D3822.

13. A carded sliver according to any one of claims 1-12, wherein the CA staple fibers have an elongation at break of at least 15% measured according to ASTM D3822 or wherein the sliver is obtained from staple fibers made from filaments having an elongation at break of at least 15% measured according to ASTM D3822.

14. A carded sliver according to any one of claims 1-13 having a fiber-to-fiber cohesive energy of at least 15,000 joules, or at least 20,000 joules.

15. A spun yarn obtained from one or more drawn carded sliver(s) comprising at least one of cellulose acetate staple fibers (CA staple fibers) having a circular shape, a denier less than 3.0, a crimp frequency per inch (CPI) of 5 to 30, wherein the at least one sliver has a fiber-to-fiber cohesion energy of at least 10,000 joules.

16. The spun yarn of claim 15 wherein the CA staple fiber has an uncrimped fiber-to-fiber dynamic coefficient of friction (F/F CODF) of between 0.11 and less than 0.2 and the CA staple fiber has an electrostatic charge of less than 1.0kV at 65% relative humidity measured at one twist, a rate of 20M/min, and at an input tension of 10 grams on a filament used to make the CA staple fiber, the electrostatic charge measured by rubbing back and forth three times over a two foot sample length of filament.

17. The spun yarn of any of claims 15-16 wherein the yarn contains 10 to 70 wt% CA staple fibers.

18. The spun yarn of any of claims 15-17, wherein the yarn has at least one of the following characteristics: (i) a breaking force of at least 150g-N, as measured according to ASTM D2256 on a sample containing 100% of said CA staple fibers, (ii) a tenacity of at least 0.85 gF/denier, as measured according to ASTM D2256 on a sample containing 100% of said CA staple fibers, or (iii) an elongation at break of at least 13%, as measured according to ASTM D2256 on a sample containing 100% of said CA staple fibers.

19. The spun yarn of any of claims 15-18 having a total denier of less than 300 and a twist per inch of less than 4.

20. A textile fabric obtained from spun yarn, the yarn being obtained from carded sliver comprising CA staple fibers (CA staple fibers) containing an amount of a spin finish, and wherein the textile fabric contains no spin finish, or contains an amount of spin finish less than said amount on said CA staple fibers, said staple CA staple fibers having a round shape, a denier of less than 3.0, a crimp frequency per inch (CPI) of 5 to 30, wherein the one or more carded slivers have a fiber-to-fiber cohesive energy of at least 10,000 joules.

21. The woven fabric of claim 21, wherein the CA staple fibers have a untwisted fiber-to-fiber dynamic coefficient of friction (F/F CODF) of between 0.1 and less than 0.2 and an electrostatic charge of less than 1.0 at 65% relative humidity measured at one twist, a rate of 20M/min, and at an input tension of 10 grams on a filament used to make the CA staple fibers, the electrostatic charge measured by rubbing back and forth three times over a two foot sample length of filament.

22. A carded sliver comprising cellulose acetate staple fibers (CA staple fibers) having a circular shape, a denier of less than 3.0, a crimp frequency per inch (CPI) of 5 to 30, and wherein the sliver is obtained from CA staple fibers having a scorop value of at least 0.2 and not more than 1.

23. A carded sliver according to claim 22, wherein the friction of the CA fibers has a fiber-to-fiber fluff pad friction coefficient as follows: at least 0.20 and not more than 1, or at least 0.30 and not more than 0.8, or at least 0.35 and not more than 0.65.

24. A carded sliver according to any one of claims 22-23, wherein the friction of the CA fibers has a fiber-to-metal staple fiber mat friction coefficient of at least 0.10 and not more than 0.4.

25. A carded sliver according to any one of claims 22-24, wherein the CA staple fibers have an electrostatic charge of less than 1.0kV at 65% relative humidity, measured using an electrostatic analyser rubbing three times back and forth over a two foot sample length of filament used to make the CA staple fibers.

26. The carded sliver of any one of claims 22-25, wherein the CA staple fibers have an uncrimped fiber-to-fiber dynamic coefficient of friction (F/F CODF) of between 0.11 and less than 0.2, measured at a speed of 20M/min at one twist and at an input tension of 10 grams on the filaments used to make the CA staple fibers according to ASTM D3412/3412M-13.

27. A carding wire of any of claims 22-26, wherein the wire has a coefficient of variation (CVm) of not more than 4.5% or not more than 4%.

28. A carded sliver of any one of claims 22-27, wherein the sliver has a short fiber content of not greater than 15% (less than 1/2 inches) as determined by a Keisokki fiber length distribution tester.

29. A carded sliver according to any of claims 22-28, wherein at least 10 wt% and at most 55% of the staple fibers in the sliver are CA staple fibers, and wherein the CA staple fibers are coated with a finish.

30. A carded sliver of any of claims 22-29 wherein the CA staple fibers have a denier of 0.5 to 1.9, a CPI of 8 to 19, and wherein the cellulose acetate used to make the fibers has a degree of acetyl substitution of at least 2.2.

31. A carded sliver according to any of claims 22-30, wherein the CA staple fibers have a CPI to DPF ratio of 6:1 to 14: 1.

32. A carded sliver according to any of claims 22-31, wherein at least 90% of the CA staple fibers have a form factor of 1.0 to 1.5.

33. A carded sliver according to any of claims 22-32, wherein at least 90 wt% of the CA staple fibers have a cut length of 10mm to 150 mm.

34. A carded sliver according to any of claims 22-33, wherein the CA staple fibers are coated with a finish in an amount of less than 2.0 wt% FOY on a dry weight basis.

35. A carded sliver according to any of claims 22-34, wherein the CA staple fibers have a tenacity of at least 0.9 grams-force/denier, measured according to ASTM D3822, or are made from filaments having a tenacity of at least 0.9 grams-force/denier, measured according to ASTM D3822.

36. A carded sliver according to any of claims 22-35, wherein the CA staple fibers have an elongation at break of at least 15% measured according to ASTM D3822, or wherein the sliver is obtained from staple fibers made from filaments having an elongation at break of at least 15% measured according to ASTM D3822.

37. A carded sliver according to any one of claims 22-36 having a fiber-to-fiber cohesive energy of at least 15,000 joules, or at least 20,000 joules.

38. A spun yarn obtained from one or more drawn carded sliver(s) comprising at least one of cellulose acetate staple fibers (CA staple fibers) having a circular shape, a denier less than 3.0, a crimp frequency per inch (CPI) of 5 to 30, wherein the sliver is obtained from CA staple fibers having a scroop value of at least 0.2 and not more than 1.

39. The spun yarn of claim 38 wherein the yarn has at least one of the following characteristics: (i) a breaking force of at least 150g-N, as measured according to ASTM D2256 on a sample containing 100% of said CA staple fibers, or (ii) a tenacity of at least 0.85 gF/denier, as measured according to ASTM D2256 on a sample containing 100% of said CA staple fibers, or (iii) an elongation at break, as measured according to ASTM D2256 on a sample containing 100% of said CA staple fibers, of at least 13%.

40. The spun yarn of any of claims 38-39 having a total denier of less than 300 and a twist per inch of less than 4.

41. A textile fabric obtained from spun yarn, the yarn being obtained from carded sliver comprising CA staple fibers (CA staple fibers) containing an amount of a spin finish, and wherein the textile fabric contains no spin finish, or contains an amount of spin finish less than the amount on the CA staple fibers, the staple CA staple fibers having a circular shape, a denier of less than 3.0, a crimp frequency per inch (CPI) of 5 to 30, wherein the one or more carded slivers are made from CA staple fibers having a scroop value of at least 0.2 and not more than 1.

42. The woven fabric of claim 41, wherein the CA staple fibers have a coefficient of untwisted fiber-to-fiber dynamic friction (F/F CODF) of from 0.1 to less than 0.2, measured at a rate of 20M/min at one twist and at an input tension of 10 grams on the filaments used to make the CA staple fibers according to ASTM D3412/3412M-13.