CN1200865C - The process of winding elastane packages - Google Patents

Abstract

A method of winding an elastomeric fiber package using a specific profile to apply a decreasing force to the core and the growing package upon contact with a roller after winding has begun, comprising the steps of: A) rotating the tube core in contact with the contact roller (3); B) winding the fiber onto the tube core such that the initial force exerted by the contact roller on the fiber on the tube core is no greater than 98N and the package (1) begins to form; C) reducing the force for the first time to about 25-60% of the initial force during the first 30% of the winding time; D) keeping the force substantially constant until the last 30% of the winding time; and E) reducing the force a second time to a final force of 10-35% of the initial force, wherein the final force is not less than 9.8N and the package weight is at least 4 kg.

Description

The process of winding elastane packages

                      

The present invention relates to a winding process for a package of elastic fibers, and more particularly to a process for winding a package using contact rollers to apply varying pressure during winding.

Background technique

Elastane-based products have been widely used in many fields, such as industrial materials, cloth, and disposable personal hygiene products (such as diapers). Elastic fibers have been woven and knitted into fabrics, stitch bonded into nonwovens, and directly bonded to pure materials such as nonwovens and films. The elastic fiber is initially supplied wound on a tube core. Such wound fibers and associated dies are referred to as "packages". In use, the elastic fiber is unwound sequentially or in parallel from the package, either passively (e.g., by "end take"), or actively (e.g., by "roll take"), and fed downstream process.

However, certain problems have arisen and to date spandex packages have sometimes had poor package shape. Such packages are wound with increasing force on the core and package by contact rollers. This poor package shape can easily cause elastic fibers to fall off the package (for example, due to friction with shipping material or other elastic fiber packages), so that the elastic fibers that are not unwound become entangled with the released elastic fibers together, resulting in fiber breakage. Such fractures can also occur as a direct result of friction. Accordingly, the economics of unwinding fibers without such packages is poor and an improved process for winding packages of elastic fibers is desired.

Contents of the invention

A method for winding elastic fibers producing a bending force distribution comprising the steps of:

(A) rotating the tube core in contact with the contact roller;

(B) winding the fiber onto the core such that the contact roller exerts an initial force of no greater than 98 N on the fiber on the core and the package begins to form;

(C) first taper the force to about 25-60% of the initial force during the first 30% of the winding time;

(D) maintaining the force substantially constant until the last 30% of the winding time; and

(E) The force is reduced a second time to a final force not less than 10-35% of the initial force, wherein the final force is not less than 9.8N and the package weight is at least 4kg.

Description of drawings

Figure 1 is a schematic side view illustrating an elastic fiber package obtained by the process of the present invention;

Figure 2 is a graph of the force exerted by contact rollers on the core and package versus the package diameter from the beginning of winding to the end of winding in the process of the invention, which is an example of the bending force distribution;

Figure 3 shows a cross-sectional view of an elastic fiber package produced by conventional winding;

Figure 4 illustrates an example of a no-bend force distribution used in a conventional winding process.

Figure 5 schematically illustrates an example of an apparatus that may be used in the process to vary the force exerted by the contact rollers on the spandex package.

Detailed ways

It has now been found that it is possible to produce elastic fiber packages, especially large packages, with good unwinding characteristics and good package shape by winding the package with bending force distribution.

"Elastane" refers to a filament which has an elongation at break greater than 100%, independent of any crimping, and which returns quickly and forcibly to its substantially original length after elongation and unwinding. Such fibers include rubber fibers, spandex or elastane, polyetherester fibers, polyetheramide fibers, certain polypropylenes and elastane polyesters. "Spandex" and "elastane" refer to fibers manufactured in which the fiber-forming substance is a long-chain synthetic elastomer comprising at least 85% by weight segmented polyurethane. "Bending force distribution" means a graph of the package diameter versus the force exerted by the contact rollers on the die and the wound package, relative to a fixed straight line, depending on the point of view of the curve. to convex and vice versa.

Synthetic elastic fibers, such as elastane, polyetheramide fibers, and polyetherester fibers, can be prepared from polyethylene glycols; copolyethylene glycols can also be used. In the case of elastic fibers, the polyethylene glycol may be (co)polyether glycol, (co)polyester glycol and/or (co)polycarbonate glycol. Polyethylene glycol is generally reacted with a diisocyanate in the presence of at least one diamine, alkanolamine and/or diol to form a polymer. In the case of polyetheresters, polyether glycol is reacted with a diacid in the presence of at least one low molecular weight diol to form a polymer. Polyetheramides can be prepared using polyetherdiamines, diacids and low molecular weight diamines. Monofunctional chain terminators such as ethanol and amines can be used to control the molecular weight of the polymer.

Depending on the type of polymer to be produced, solution or melt polymerization can be used. Thus, depending on the type of polymer, dry, wet or melt spinning can be used to make fibers. Additives and stabilizers may be added to the fibers as long as they do not adversely affect the process of the present invention.

After the fiber has been spun, the fiber is reciprocated transversely, typically in its direction of travel, by a traversing device and wound onto a tube core. The tube core is conventionally mounted on the spindle assembly and the fiber is wound onto the tube core by means of contact rollers. It is possible to drive the spindle assembly without driving the contact rollers (free rotation). The other is that the contact roller can be driven without driving the spindle assembly, which requires a rotational drive to rotate the spindle assembly.

In the process of the invention, the forces exerted by the contact rollers on the tube core (and, after the start of winding, on the growing package) are reduced according to a specific distribution during winding. The reduction in force described here is with reference to the force used at the beginning of winding ("initial force"). The maximum initial force can be 98N (10kg) and the minimum force can be 9.8N (1kg). During the first 30%, preferably 10% of the winding time first taper the force down to about 25-60% of the initial force. The contact roller force then remains substantially constant until the last 30%, preferably about 20% of the winding time, when the force is reduced a second time to not less than about 10% of the initial force, preferably about 10- 35%. The winding time corresponds approximately to the package diameter, and the contact roll force is plotted against the package diameter to obtain the bending force distribution as illustrated in FIG. 2 .

The method of the present invention provides a package of elastic fibers having a substantially uniform winding width, thereby providing excellent unwinding and shape retention characteristics. That is, the present invention produces a package as shown in FIG. 1 which has a small deviation δω between the maximum _value δmax and the _minimum value _δmin of the wound package width. A small deviation S _ω indicates that the sidewalls are essentially as desired flat and perpendicular to the axis of the die; such a package has good unwinding characteristics.

The process of the present invention is very useful for packages of spandex weighing 3 kg or more and even exceeding 4 kg.

Any suitable method may be used in this invention, such as a device to control and vary the force exerted by the contact rollers on the package. For example, it is possible to use a device as illustrated in Figure 5, in which a cylinder 5 of compressed air is operated according to a signal from a control unit (not shown) to adjust the weight of an arm 4 supporting a contact roller 3 that When winding the elastic fiber 2, it is in contact with the tube core and the package 1 to rotate. Thus the contact roller force decreases when the cylinder extends, and increases when the cylinder retracts. Air cylinders can also be replaced by hydraulic cylinders. Other geometries can also be used in order to obtain the bending force distribution of the present invention.

Example 1

560 denier (622 dtex) ^Lycra® Spandex (type 127, registered trademark of EI du Pont de Nemours and Campany (DuPont)) was dry spun by conventional equipment and wound onto a 175 mm long tube core so as to reach The loading weight is 4.5kg. No finishing was applied to the fibers. During the winding process, the force exerted by the contact roller on the package is according to the bending force distribution shown in Figure 2. The diameter of the package (mm) is plotted on the abscissa and the force exerted by the contact roller on the package (kg ) plotted on the ordinate. As shown in Figure 2. The total package diameter is approximately 282 mm. It was about 9mm (5% of the total diameter, and about 5% of the total winding time) at the first reduction of contact roller force at the beginning of winding, and about 9mm at the second reduction of force at the end of winding. 46mm (24% of the total diameter, and about 24% of the total winding time). The force decreased from about 55.86 N (5.7 kg) at the beginning of the winding to about 28.42 N (2.9 kg) in the middle of the winding, or about 50% of the initial force. The contact roller force remained essentially constant until the end of winding, at which point the force was further reduced to about 31% of the initial force. In other words, about 17.64 (1.8kg). As shown in Table 1, the winding width difference was small and the product had excellent sidewall shape and unwinding characteristics.

Comparative example 1

The spandex was spun and wound exactly as in Example 1 except that the force exerted by the contact roller on the package was increased as in conventional winding, as shown in FIG. 4 . As listed in Table 1, the resulting package had a winding width greater than that of the package of Example 1, indicating poor unwinding characteristics, and had S-shaped (substantially convex) sidewalls as shown in Figure 3. Show.

Table 1 Example 1 Comparative Example 1 The shape of the curve of the force exerted on the package by the contact roller Bending force distribution, as shown in Figure 2 linear, as shown in Figure 4 Winding width difference δ _ω (mm) 16 30 side wall shape smooth curve S type, with large convex drum Unwind feature good Difference

Claims (3)

1. A process for winding elastic fibers (2), comprising the following steps: (A) rotating the tube core contacted with the contact roller (3); (B) winding the fiber onto the core such that the initial force exerted by the contact roller on the fiber on the core is no greater than 98 N and the package (1) begins to form; (C) reducing the force for the first time to 25-60% of the initial force during the first 30% of the winding time; (D) keeping the force substantially constant until the last 30% of the winding time; and (E) The force is reduced a second time to a final force of 10-35% of the initial force, wherein the final force is not less than 9.8 N and the package weight is at least 4 kg. 2. The process of claim 1, wherein the force is reduced a first time during the first 10% of the winding time and a second reduction in the force is during the last 20% of the winding time. 3. The process of claim 1 or 2, wherein the fibers are selected from the group consisting of spandex and polyetherester fibers.

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