JPS648730B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a melt-spun synthetic yarn and a method for producing the same. More particularly, the present invention relates to yarns that have a combination of high bulk and wool-like feel.

It is already known that filaments of different shrinkage rates can be combined into a single thread and then shrunk, whereby the longer filaments protrude as loops from the thread, thereby producing a thread that is more or less bulky. There is. This can be done by spinning filaments from different polymers, as described in U.S. Pat. No. 3,444,681, or by cutting different filaments from a common polymer, as typically shown in some patent specifications. It can be carried out by spinning a filament of an area. Such known yarns usually do not have high bulk, and fabrics made from them usually do not give a feel similar to wool. It initially feels hard when touched lightly, and becomes soft when pressed hard.

These and other drawbacks of the prior art are obviated by the present invention which provides a new and useful method and improved yarn product.

According to a first main aspect of the present invention, there is provided a method for producing a self-crimping yarn comprising filaments of a first type and a second type, the method comprising: (a) producing first and second individual streams of molten polymer of fiber-forming molecular weight each moving at different velocities, converging the individual streams in parallel to form a combined stream, and forming the combined stream. spinning said first type of filament having a denier periodic variation and non-circular cross-sectional shape by cooling to form a bonded filament; (b) spinning said bonded filament at a predetermined common winding speed; by extruding a third stream of molten polymer of fiber-forming molecular weight through an orifice selected to provide a filament having a shrinkage lower than the filament and cooling this third stream into a filament. (c) removing the respective filaments from the streams at a common winding speed greater than 2200 m/min; and (d) combining the filaments into yarn. It is made up of

According to another aspect, each stream consists of polyester polymer.

According to other points of view, the winding speed is 20%
It is selected to have the following shrinkage ratio:

According to other points of view, the winding speed is 8%
It is selected to have the following shrinkage ratio:

According to another main aspect of the invention, there is provided a multifilament yarn comprising filaments of a first type and a second type, each filament of the first type having a non-circular cross-sectional shape; and has a denier period variation of more than ±15% of the average value and has a potential crimp, and each of the second type filaments has a shrinkage rate lower than that of the first type filaments. rate.

According to another aspect, each of the second type of filaments has a denier that is greater than the average denier of the first type of filaments.

According to another main aspect of the invention, there is provided a multifilament yarn comprising filaments of a first type and a second type, each filament of the first type having a non-circular cross-sectional shape. It also has a denier period variation of ±15% or more of the average value, has developed crimp, and has a second
Each filament of the type is longer than the filament of the first type so that the filament of the second type projects from the thread as a loop.

According to another aspect, each filament of the second type has a denier that is greater than the average denier of the filaments of the first type.

These and other aspects of the invention are set forth in part hereinafter and in part in the following detailed description with reference to the accompanying drawings.

In the accompanying drawings, FIG. 1 is a vertical cross-sectional view of a spinneret orifice for producing a first type of filament. FIG. 2 is a bottom view of the orifice of FIG. 1, viewed from below. FIG. 3 is a graph showing the relationship between shrinkage and spinning speed (winding speed) to explain the principle on which the present invention is based. FIG. 4 shows a first embodiment according to one embodiment of the present invention.
FIG. 2 is a cross-sectional view of a filament of the type. FIG. 5 is a side view of a first type of melt stream exiting the spinneret of FIG. 1 in accordance with one embodiment of the present invention. FIG. 6 is a graph illustrating denier variation along the axis of a representative first type filament according to one embodiment of the present invention, and FIG.
FIG. 5 is a graph illustrating the distribution of variations illustrated in FIG. 5 for an exemplary first type filament multi-orifice spinneret according to one embodiment of the present invention.

FIG. 8 is a schematic diagram showing a process for manufacturing a self-crimping yarn comprising a first type of filament and a second type of filament according to the present invention, and an apparatus therefor.

Although polyester polymers are used to specifically illustrate the invention, it is to be understood that embodiments of the invention are generally applicable to the family of melt-spun polymers. As used herein, "polyester" refers to fiber-forming polymers of which at least 85% by weight can be prepared by reaction of dihydric alcohols and terephthalic acid. Polyesters are typically made by direct esterification of ethylene glycol and terephthalic acid or by transesterification between ethylene glycol and dimethyl terephthalate.

Figures 1 and 2 illustrate preferred embodiments of spinneret designs that can be used to obtain filaments of the first type of the invention. The spinneret has a large borehole 20 formed in the upper surface 21 of the spinneret plate 22. A small borehole 24 is formed at the bottom of the large borehole 20 and to one side thereof. A large capillary 26 extends from the bottom of the large bore and from the opposite side of the small bore, connecting the lower surface of the plate 22 and the bottom of the large bore 20. Small capillary 30 bottom and surface 28 of borehole 24
are connected. Capillaries 26 and 30
are each inclined by 4° from the vertical and thus have an angle of 8°. Bored hole 20 has a diameter of 0.113 inches (2.87 mm), while bored hole 24
has a diameter of 0.052 inches (1.32 mm).
Capillary 26 has a diameter of 0.016 inches (0.406 mm) and a length of 0.146 inches (3.71 mm), while capillary 30 has a diameter of 0.009 inches (0.229 mm).
mm) diameter and 0.032 inch (0.813 mm) length. Land 32 separates capillaries 26 and 30 at surface 28. This land has a width of 0.0043 inches (0.109 mm). Plate 22 has a thickness of 0.554 inches (14.07 mm). Capillaries 26 and 30, together with boreholes 20 and 24, constitute coupling orifices for spinning various new and useful filaments according to the present invention.

FIG. 3 is a graph showing how polyester filament shrinkage varies with spinning speed (take-up speed) for two exemplary jet draws. The dotted curve is 0.063 inches (1.6
34 such filaments were simultaneously spun using a spinneret capillary with a diameter of 150
When producing denier textured yarn, the shrinkage rate ranges from approximately 65% at 3400ypm (approximately 3100m/min) to approximately 5% at 5000ypm (approximately 4500m/min).
This shows that the value decreases. The solid curve is
Thirty-four such filaments were similarly spun simultaneously using a spinneret capillary having a diameter of 0.015 inch (0.38 mm) to produce a 150 denier textured yarn with false twist and draw texture processing. In this case, it is shown that the shrinkage rate decreases rapidly at higher speeds. Employing different capillary diameters creates a family of curves in the middle, to the left, and to the right of the curves shown. These curves can also be shifted by varying the polymer throughput for a given capillary diameter.
In other words, the curve can be shifted by changing the jet elongation, which is the ratio of the yarn speed immediately after solidification to the average speed of the molten polymer in the capillary. That is, it is possible to provide a bonding orifice for spinning monopolymer composite filaments in which one side of the filament has a much higher shrinkage than the other side. This can be done by choosing the individual capillaries to give different jet draws and also by choosing the individual capillaries to give different jet draws, and also by choosing the individual capillaries to provide a different jet draw, so that the individual cooled filaments from one of the individual streams are less likely to be affected than the individual cooled filaments from the other individual stream. This is done by choosing to have a higher shrinkage rate by at least 10%.
Under the spinning conditions shown in Figure 3, at a spinning speed of 5000 yards/min (approximately 4500 m/min),
The individual streams have shrinkage rates that differ by approximately 25%.
Combining these melt streams in a parallel structure provides highly crimpable filaments in their as-spun form without stretching of the yarn to develop crimp. Such bonding can be carried out using a spinneret design similar to that disclosed in FIG.
The two streams may be combined at or just before the two streams emerge from 8. In each case, embodiments of the invention combine the two streams substantially coincident with the plane of the spinneret.

Advantageously, the spinneret is designed such that one of the individual streams has a velocity in the capillary of 2.0 to 7 times (preferably 3.5 to 5.5 times) the flow velocity of the other in the capillary. Other advantages, particularly in terms of crimp degree and spinning stability, arise when the faster of the two streams has a smaller cross-sectional area than the slower of the two streams. can get. Productivity increases when the spinneret speed is chosen such that the bonded filaments have a shrinkage of 30% or less, and is maximized when the shrinkage is 10% or less.

Another aspect of the invention applicable to melt-spun polymers is that the invention can be accomplished using a spinneret where the two streams meet outside the spinneret.

By way of example, a molten polyester polymer of conventional textile molecular weight is metered at a temperature of 290 DEG C. through a spinneret having, in particular, the 34 bonding orifices mentioned above. An average of 4 per filament at a spinning speed (winding speed) of 5200 yards/minute
The amount of polymer handled is adjusted to produce denier filaments. The melt stream is normally cooled into the filament by laterally directed cooling air.

Under these spinning conditions, a remarkable phenomenon as shown in FIG. 5 occurs. Due to the geometry of the spinneret body, the polymer exiting from the smaller capillary 30 has a greater velocity than that exiting through the larger capillary. The velocity and moment of the set of streams exiting each coupling orifice, and the angle at which the streams converge outside the spinneret, are such that the slower stream 34 is substantially smaller after the point where the sets of streams first contact and combine. The smaller and faster streams 36 form loops winding back and forth between successive points 38 at which point each smaller and faster stream 36 meets its associated larger stream. do. This effect can be easily observed using a stroboscopic beam directed into the stream just below the spinneret face 28. As the melt stream accelerates away from the spinneret, the slower stream tapers between the contact points 38 and the faster stream loop straightens until the faster stream continuously contacts the slower stream. It becomes like this. The slower flow is narrower in the middle of the point of contact than at the first point of contact. The resulting binding thread has a larger cross-sectional area at the point of first contact than at the intermediate portion of these points. The resulting combined flow is then passed through the filament 40 by lateral cooling air.
It is further thinned somewhat before it solidifies.

Each of the solidifying filaments 40 has a non-circular cross-section that varies repeatedly along its length, and after heating under low tension this is more pronounced in large cross-sectional areas than in small cross-sectional areas. S and Z twists of various pitches with looser coils
It has a twisted helix coil section. As shown qualitatively in FIG. 6, when using the spinning conditions described above, the filament cross-sectional area varies repeatedly at a frequency of approximately once per meter. However, this can be varied by changing the spinning conditions and the construction of the spinneret passages.

Due to small differences between the coupling orifices, temperature gradients in the spinneret, and other deviations that result even from exactly the same treatment for each pair of streams, multi-orifice spinnerets have a Creates a difference in frequency between thick and thin. An example of this is shown qualitatively in Figure 7, which shows that multiple orifices produce somewhat different taper frequencies when stroboscopically measuring the combined flow just below the spinneret face. This shows that this will occur. In the resulting multifilament yarn, the filaments have a non-circular cross section that varies by more than ±10% along the filament length and helical crimps with alternating S and Z twists. The variations in cross-sectional area are out of phase from filament to filament, and the helical crimps are out of phase from filament to filament.

For certain effects, it is advantageous for the filament to repeatedly vary in its cross-sectional area by more than ±25% (preferably more than ±30%) along its length. This effect is due to the fact that the thread is at least 2.5
Uster unevenness in %U
This is particularly emphasized if you have the following. Worcester measurements are carried out using a Worcester Inhomogeneity Tester Model C with integrator ITG-101 for this instrument. The speed of the thread is 182.8 m/min (200 m/min
yards/minute), the actuation selector is set to normal, and the sensitivity selector is set to 12.5%. %U is read from the integrator after running the sample for 5 minutes.

Shrinkage is measured by the method disclosed below. Generally, the initial length L ₀ of the sample yarn is measured while the yarn is under a tension of 0.1 g/denier. The yarn is then tensioned to 0.0025 g/denier and placed in a 120°C oven for 5 minutes. The thread is then removed from the oven, put under tension again at 0.1 g/denier and its length L ₂ is measured. The % shrinkage is equal to L ₀ −L ₂ /L ₀ ×100.

The second type of filament can be spun at a constant common take-up speed from a spinneret orifice selected such that the first type of filament has a greater shrinkage than the second type.

The multifilament yarn of the present invention, consisting of filaments of the first and second types, can be manufactured using the process and apparatus shown schematically in FIG.

As an example, a typical molecular weight molten polyethylene terephthalate polymer for yarns for woven and knitted garments is deposited into two spinnerets, one with the 34 bonding orifices described above, and the other with 0.009 inch (0.009 inch). It has 34 circular orifices with a diameter of 0.229 mm). The extrusion rate is
Each group of 34 filaments
It is chosen to have a denier value of 77 at a winding or spinning speed of 5600 ypm. The 68 molten streams are cooled into filaments by a transversely directed air stream, and the 68 filaments are converged into a bundle of threads.
It is then wound onto a bobbin as a thread having a denier of 154 at 5600 ypm.

The yarn is heated to 150° C. under low tension to develop latent crimp in the first type of filament and create a difference in shrinkage rate between these two types of filament. These filaments of the first type, wound separately, have a shrinkage of 10.6%, while the filaments of the second type, collected separately, have a shrinkage of 4.5%. The combined yarn has a shrinkage rate of 6.3%. Each filament of the first type has a denier periodic variation of about 1 denier to about 4 denier, while the filaments of the second type protrude from the yarn bundle as relatively large loops.

In order to bring out the wool-like feel even more, the second
The denier/filament value of filaments of the type can be increased. A range of about 5 to 9 dpf is particularly suitable.

[Brief explanation of drawings]

In the accompanying drawings, FIG. 1 is a vertical cross-sectional view of a spinneret orifice for producing filaments of a first type, FIG. 2 is a bottom view of the orifice of FIG. 1 as seen from below, and FIG. 3 is a graph showing the relationship between shrinkage and spinning speed to explain the principles on which the invention is based; FIG. 4 is a cross-sectional view of a first type of filament according to one embodiment of the invention; FIG. 5 is a side view of the melt stream exiting the spinneret of FIG. 1 according to one embodiment of the present invention, and FIG. 6 is a side view of a representative first type of filament according to one embodiment of the present invention. 7 is a graph illustrating the variation of denier along the axis, and FIG. 7 is a graph illustrating the variation of denier along the axis as illustrated in FIG. 3 is a graph illustrating the distribution of fluctuations. FIG. 8 is a schematic diagram illustrating a process and apparatus for producing a self-crimping yarn comprising a first type of filament and a second type of filament according to the present invention.

Claims (1)

[Scope of Claims] 1. In producing a self-crimping yarn consisting of filaments of first and second types, (a) first and second types of molten polymers of fiber-forming molecular weight moving at different speeds; generating a second individual flow, converging the individual flows in parallel to form a combined flow, and cooling the combined flow to form a combined non-circular cross-section filament having a denier periodic variation. (b) spinning a bonded non-circular cross-sectional shape filament having a denier periodic variation of said first type by forming a denier periodic variation of said first type; said second stream by extruding a third stream of molten polymer of fiber-forming molecular weight through an orifice selected to provide a filament having a shrinkage rate and cooling said third stream into a filament. (c) removing said filaments from said streams at said common winding speed greater than 2200 m/min; and (d) combining said filaments into a yarn. A method characterized by: 2. The method of claim 1, wherein each of said streams is a stream of polyester polymer. 3. Method according to claim 2, characterized in that the winding speed is chosen such that the yarn has a shrinkage of less than 20%. 4. Method according to claim 3, characterized in that the winding speed is chosen such that the yarn has a shrinkage of 8% or less. 5 The winding speed is 4572 to 5486 m/min (5000 to
6000 yards/min) and each filament of the first type is polyester. 6 (a) The filament of the first type has a non-circular cross-sectional shape in which two streams of molten polymer are combined and has a denier cyclic variation of more than ±15% of the average value and has a potential and (b) the second type of filament has a shrinkage rate lower than the shrinkage rate of the first type of filament. A multifilament yarn consisting of filaments of one type and a second type. 7 The second type of filament is the first type of filament.
Yarn according to claim 6, characterized in that it has a denier greater than the average denier of filaments of the type. 8. Yarn according to claim 6, characterized in that the filament of the first type is polyester. 9 (a) the filament of the first type has a non-circular cross-sectional shape in which two streams of molten polymer are combined and has a denier periodic variation of ±15% or more of the average value and is developed; (b) the second type of filament is longer than the first type of filament such that the second type of filament projects from the yarn in a loop; A multifilament yarn comprising filaments of a first type and a second type. 10. Yarn according to claim 9, characterized in that the filaments of the second type have a greater denier than the average denier of the filaments of the first type. 11. Yarn according to claim 9, characterized in that the filament of the first type is polyester.