JPH0791709B2 - Ultra-soft multifilament yarn and method for manufacturing same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an ultra-soft multifilament yarn having extremely high softness and a unique handle, the ultra-soft multifilament yarn produced by this method, and an ultra-soft fabric comprising this multifilament yarn.

BACKGROUND ART Synthetic fibers generally have a glass transition temperature (also called the second-order transition temperature), below which the polymer molecules are frozen and molecular movement is difficult. Therefore, when drawing these fibers, the drawing temperature is generally set to a temperature above the glass transition temperature to facilitate the movement of the polymer molecules. When the synthetic fibers are forcibly drawn at a temperature below the glass transition temperature in which the polymer molecules are frozen, the polymer molecules do not orient, and as a result, filaments with a unique feel that is completely different from conventional drawn yarns are obtained (however, when the polymer molecules are forcibly drawn in a frozen state using conventional methods, drawing irregularities inevitably occur, making it impossible to obtain a uniform appearance). That is, drawing synthetic fibers at a low temperature below the glass transition temperature was not reported in JP-B-83-1983.
This is the same as the manufacturing method of so-called Thick & Thin yarns as shown in JP 44762 A, and therefore it is impossible to obtain a unique feel without generating uneven drawing. Furthermore, since such drawing below the glass transition point forcibly stretches polymer molecules in a frozen state, the energy required for this is extremely large, which causes many problems such as the filaments slipping on the roller surface and, further, fuzzing and the occurrence of wrapping, resulting in a problem of low productivity of drawn filament yarns.

DISCLOSURE OF THE INVENTION The present invention provides a method for producing an ultra-soft multifilament yarn having extremely high flexibility and a unique feel while the polymer molecules are in a frozen state, without changing the cross-sectional shape of the multifilament or imparting crimp thereto, thereby providing an ultra-soft multifilament yarn consisting of uniformly drawn multifilaments and having uniform appearance and performance, and an ultra-soft multifilament yarn fabric obtained therefrom.

The method for producing ultra-soft multifilament yarns of the present invention is directed to producing low-stretch multifilament yarns, both of which are essentially made of polyethylene terephthalate and have a degree of orientation (Δn) of 0.03 or more, and low-stretch multifilament yarns having a degree of orientation (Δn) of 0.02 or less.
and the difference in stretchability between the low extensibility multifilament and the low extensibility multifilament is at least 70 in natural stretch ratio (expressed as elongation).
% high extensibility multifilament yarns are paralleled together, the paralleled composite yarns are subjected to a false twisting process including a simultaneous drawing and twisting operation and an untwisting operation at a temperature below the glass transition point of the polyethylene terephthalate, the high extensibility multifilament is uniformly drawn in a state where it is wound around the low extensibility multifilament by the simultaneous drawing and twisting operation, and in any step after the untwisting operation, the composite yarn is heat-treated at a temperature of 130°C or higher.

BRIEF DESCRIPTION OF THE DRAWINGS Figures 1(a), 1(b) and 1(c) are side views for explaining a conventional drawing process of synthetic fibers, where Figure 1(a) shows a side view of undrawn synthetic fibers, and Figure 1(b) shows a side view of undrawn synthetic fibers.
2(a), (b) and (c) are side views illustrating the false twisting and drawing process of the present invention for a paired yarn made of two types of synthetic fibers having different drawability, where FIG. 2(a) is a side view of the paired yarn made of two types of synthetic fibers, FIG. 2(b) is a side view showing the shape of the paired yarn shown in FIG. 2(a) at the beginning of the false twisting and drawing process when the present invention is applied to the paired yarn, and FIG. 2(c) is a side view showing the shape of the yarn formed by false twisting in the false twisting and drawing process, FIG. 3 is an explanatory diagram of one embodiment of an apparatus used to carry out the present invention, FIG. 4(a) is an explanatory side view of a conventional false twist textured multifilament yarn, and FIG. 4(b) is an explanatory side view of a multifilament yarn according to the present invention.

Best Mode for Carrying Out the Invention The present invention will now be described in detail with reference to specific examples.

Figure 1(a) is a side view of an undrawn synthetic fiber. When this undrawn filament is heated above its glass transition temperature to thaw the constituent polymer molecules and then pulled by conventional methods, the filament is uniformly drawn, as shown in Figure 1(b). However, when this filament is pulled at a temperature below its glass transition temperature, the constituent polymer molecules remain frozen and are forcibly stretched, so the filament is not drawn uniformly and smoothly. Instead, it is drawn unevenly, as shown in Figure 1(c), resulting in a filament of non-uniform thickness. The "glass transition temperature" referred to here is measured by dilatometry, and for polyethylene terephthalate, it is in the range of 79-81°C.

In contrast, Figure 2 is an explanatory diagram showing the state of false twisting and drawing by the method of the present invention. As shown in Figure 2(a), an undrawn (highly extensible) filament 1 and an attached filament 2 which is highly oriented and therefore difficult to stretch (lowly extensible) are aligned, and when they are drawn while twisting as shown in Figure 2(b), the undrawn filament 1 is easy to stretch but the attached filament 2 is difficult to stretch. As a result, the highly extensible undrawn filament 1 is drawn in a state where it is wound around the low extensible attached filament 2 as shown in Figure 2(c). As a result, the highly extensible undrawn filament 1
is longer than the low extensibility filament 2 by the length required for winding, and is uniformly stretched.

That is, when a filament is stretched by pulling both ends as shown in Figure 1(c), the filament is difficult to stretch, especially when the molecules are frozen below the glass transition point (secondary transition point), so when it is forcibly stretched, the easy-to-stretch portions of the filament stretch easily, while the difficult-to-stretch portions do not stretch very much, resulting in uneven thickness in the resulting stretched filament. However, when the high-stretch unstretched filament 1 is twisted together with the low-stretch attached filament 2 as described above and stretched in the process of winding it, each portion of the unstretched filament is stretched little by little, so the local stretching that occurs when both ends of the filament are held and the middle part is pulled equally does not occur,
Each part of the filament is uniformly and equally elongated, resulting in a composite yarn as shown in Figure 2(c). Thus, in the method of the present invention, the filaments can be uniformly elongated by false twisting and drawing below the glass transition temperature. Furthermore, it is possible to uniformly elongate the filaments even at low drawing ratios, which tend to cause localized elongation.

However, with only this false twisting, when the high extensible filament 1 is twisted and wound around, it cannot be stretched beyond the extent to which it naturally stretches, so the upper limit of the stretching ratio is determined by itself. However, what should be noted here is that when the high extensible undrawn filament 1 is wound and drawn while the low extensible attached filament 2 is stretched, the high extensible undrawn filament 1 is stretched by the amount of elongation caused by the winding, and the low extensible attached filament 2 is stretched.
Even in this case, the fact that the highly extensible undrawn filaments 1 are elongated very uniformly is important. This phenomenon is due to the fact that the highly extensible undrawn filaments 1
It is presumed that the high-stretch undrawn filament 1 is tightly wrapped around the low-stretch attached filament 2 and stretches while being constrained to this shape. Therefore, by controlling the amount of stretch of the low-stretch attached filament 2, it is possible to adjust the stretch rate of the high-stretch undrawn filament 1 to a certain extent. Furthermore, if the high-stretch undrawn filament 1 and the low-stretch attached filament 2 are entangled in advance and the twisting operation described above is applied to this entangled yarn, the restraint relationship between the two becomes even tighter, and the uniformity of the resulting false-twist textured yarn is further improved. The number of entangled filaments in this case is 40 to 100.
100 pieces/m is preferable.

FIG. 3 shows an example of an apparatus for carrying out the method of the present invention. For example, polyester undrawn yarn 11 (highly drawable)
The yarn 21 is aligned with a low-stretchability polyester intermediate oriented filament 12 (low extensibility), which is less extensible (highly oriented), and the aligned yarn 21 is supplied to the processing device by a pair of supply rollers 13.
21 are intertwined with each other by the air nozzle 14, and then passed through the intermediate roller
The yarn passes through 15 and is sent to a false twisting device 16 where it is twisted.
As a result, in the first half of the false twist device 16, the undrawn filament 11 is stretched by wrapping around the add-on filament 12, and then in the second half of the false twist device 16, the untwisted filament 11 is unwound and released. In the composite yarn thus obtained, the two filaments 11 and 12, while still entangled, pass through the delivery roller 17, are heat-set by the heater 18, and are then taken up by the take-up roller 19 onto the winder 20. When the resulting textured yarn is woven and dyed, it is found that, because the polymer molecules are stretched while frozen, it has an extremely soft, marshmallow-like special handle, and is completely free of thickness variations or dye variations, making it a versatile fabric that is completely different from conventional synthetic fiber fabrics.

In the present invention, in order to obtain such a texture, it is important that the constituent polymer molecules are in a frozen state when the highly extensible undrawn filaments 11 are stretched in the false twisting process.
It is necessary to carry out the false twisting process at a temperature below the glass transition temperature (secondary transition temperature) of the synthetic fiber. To achieve this, it is not permitted to heat the synthetic fiber to the so-called thermoplastic temperature of 160°C to 240°C, which is the high temperature, and it is necessary to carry out the twisting, heat setting, and untwisting at a temperature below the glass transition temperature (a heat treatment time of 0.6 seconds or less). Generally, the best results are obtained by carrying out the false twisting process at room temperature without heating, as in the above example.

Furthermore, although it is not essential to previously entangle the supplied high-stretch undrawn filaments 11 and low-stretch add filaments 12 as described above, entangling them allows the high-stretch undrawn filaments 11 to be stretched more uniformly as described above, and also has the effect of preventing the textured yarn from opening up into pieces after false-twisting and untwisting. This effect of preventing opening can sometimes be obtained by carrying out an entanglement treatment after false-twisting and untwisting, but generally, entanglement before false-twisting provides a greater effect of preventing opening.

Furthermore, when the amount of elongation of the highly extensible undrawn filament 11 is small, it is preferable to also elongate the low extensible attached filament 12 as described above, and add this amount of elongation.
To explain this with reference to FIG. 3, it is preferable to set the speed relationship between the roller 15 and the roller 17 so that the applied filament 12 can be stretched, thereby performing so-called draw twisting.
Even in this way, the undrawn filaments 11 are uniformly stretched without becoming uneven yarns, as described above. In particular, when false twisting is performed using a friction false twisting device, it is preferable to perform false twisting while stretching, since the filament yarn slips on the friction surface. Also, when using a spindle false twisting device, it is not necessarily necessary to perform stretch false twisting. However, friction false twisting generally prevents filament stagnation and allows the filament to run more smoothly.

In addition, when the filaments are twisted in the false twisting process, in order to stretch only the highly extensible undrawn filaments 11 in a spiral shape, the low extensible attached filaments 12
However, it is necessary that the filament is less stretchable than the highly stretchable unstretched filament 11.
The low-stretch filaments 12 are moderately or highly oriented filaments having a degree of orientation (birefringence index Δn) of 0.03 or more.
The natural stretch ratio (expressed as elongation %) is set to be 70% or more smaller than that of the highly extensible undrawn filament 11 .

The method of the present invention involves forcibly drawing frozen polymer molecules, thereby producing a unique super-soft feel in the textured yarn. However, the more poorly the polymer molecules in the highly stretchable undrawn filaments 11 are aligned in the fiber axis direction before drawing, i.e., the lower the degree of orientation, the more difficult it becomes to draw the highly stretchable undrawn filaments 11, and the more unique the texture of the textured yarn obtained becomes. Therefore, the degree of orientation of the highly stretchable undrawn filaments 11 depends on their birefringence (Δ
When expressed as n), it is 0.02 or less, and it is preferable that it is 0.01 or less, so that there is almost no orientation.

As described above, the filaments forcibly drawn at low temperatures by the method of the present invention generally have large internal strains and a high shrinkage rate in boiling water, so that before use, they must be heat-treated to reduce the shrinkage rate.
In the illustrated apparatus, the heater 18 is used for this purpose, and its heating temperature is 130° C. or higher, preferably 160° C. or higher, and at this temperature, the temperature is at least 0.1
It is preferable to heat the yarn after the false twisting process for at least 10 seconds. If the heating is carried out continuously following the drawing step, the resulting textured yarn can be used in any field, which is preferable, but depending on the application, the textured yarn may be made into a fabric such as a woven fabric and then subjected to the shrinkage reduction treatment.

In the present invention, the blending ratio of the highly extensible undrawn filaments 11 and the low extensible attached filaments 12 may be set as follows: That is, the unique feel of the textured yarn according to the present invention is due to the fact that the polymer molecules are elongated in a frozen state (i.e., the highly extensible undrawn filaments 11),
In other words, since this is achieved by low-oriented filaments (=filaments with a large natural draw ratio), it is generally preferable that the proportion of the highly stretchable undrawn filaments 11 used in the textured yarn is at least half of the total weight of the textured yarn. However, when using filaments with a specific orientation that is particularly difficult to stretch, it is possible to prioritize the stretchability of the textured yarn even if it reduces the feel of the resulting textured yarn to some extent. Even in this case, the highly stretchable undrawn filaments
The content of 11 should be at least 30%.

On the other hand, if the proportion of low-oriented filaments becomes too high, the low-stretch attached filaments 12 (highly oriented filaments) will become excessively thin, making it difficult to wind the highly stretchable unstretched filaments 11 around them in a spiral shape, resulting in yarn breakage and other problems. Therefore, it is preferable to keep the proportion of the highly stretchable (low-orientation) filaments 11 at most 80%.

Furthermore, in the case of the method of the present invention, the number of twists imparted in the false twisting step is not intended to form false twist crimps, and therefore the effects of the method of the present invention can be obtained even if the number of twists is not necessarily the same as that used in conventional false twisting. Although effective crimping cannot be achieved with a low twist number, in the present invention, the yarn is cold-drawn according to the twist number, and an effect corresponding to this drawing is achieved. However, unless the filament is particularly difficult to twist, it is preferable to use as large a false twist number as possible, i.e., the false twist number at which the yarn is likely to break: However, false twisting at a higher number of twists as far as stable processing is possible will allow the highly extensible (low orientation) filaments to be sufficiently elongated, resulting in a higher effect. When false twisting is performed by the friction false twist method, it is difficult to measure the number of twists, but it is preferable to control the D/Y to a value of about 1.3 to 2.8.

where De = total denier of the false-twisted and drawn filament yarn D/Y = false-twist disc surface speed / yarn speed during false-twist processing

The ultra-soft multifilament yarn of the present invention obtained by the above-mentioned method of the present invention is composed of two types of polyethylene terephthalate multifilaments with different elongations, and the multifilament (Fe) with the highest elongation of these filaments has an elongation of 60% or more, preferably 80 to 150%, and has the following properties (A) to (D).

(A) The crystallinity (χρ) measured by the density method is 10%
~30%, preferably 15%-25%.

(B) The degree of orientation (Δna) of the amorphous portion is 0.035 to 0.10, preferably 0.045 to 0.10.

(C) The density (ρa) of the amorphous portion is 1.31 to 1.36 g/cm ² , preferably 1.33 to 1.35 g/cm ³ .

(D) Young's modulus (YM) is 200 to 700 kg/mm ³ , preferably 25
Must be 0 to 450 kg/ ^mm² .

The significance of the above requirements (A) to (D) is as follows.

Requirement (A) Conventional drawn yarns are densely packed with large crystals, but in contrast, the multifilament yarn of the present invention has crystals scattered among the amorphous chains while leaving many amorphous parts, and in this sense, a crystallinity of 15 to 30% is appropriate.

Requirement (B) Requirement (B) is an important feature of the multifilament yarn of the present invention. That is, the amorphous orientation degree of 0.035 to 0.10 is higher than that of conventional heat-treated POY, but lower than that of ordinary drawn yarn. In other words, the crystallinity (requirement (A)) of the flat multifilament yarn of the present invention is higher than that of conventional heat-treated POY.
Although the degree of orientation of the amorphous portion (requirement (B)) overlaps with that of Y yarn, it is different from that of conventional drawn yarn or heat-treated POY, and this characteristic improves the performance of the flat multifilament yarn of the present invention.
In the flat multifilament yarn (Y), the degree of crystal orientation (fc) cannot be measured, and therefore it is impossible to calculate the degree of amorphous orientation. However, in the high elongation multifilaments in the flat multifilament yarn of the present invention, the fc can be measured to be within the range of 80 to 90%, and therefore the degree of amorphous orientation can be calculated.

Requirement (C): In requirement (C), the amorphous density (ρa) is 1.31 to 1.36
A density (ρa) of 1.31 g/cm ³ means that the content of amorphous chains in the high elongation multifilament is high. If this density (ρa) is less than 1.31 g/cm ³ , the performance of the resulting flat multifilament yarn will be unsatisfactory, and if the density (ρa) exceeds 1.36, the feel of the resulting flat multifilament yarn will be hard, which is undesirable.

Requirement (D) The high elongation multifilament (Fe) that satisfies the above requirements (A), (B), and (C) has a relatively low Young's modulus of 200 to 700 kg/ ^mm2 , and as a result, even if a high elongation multifilament (Fe) of 1 denier or more, particularly 2 denier or more, is used, a textured yarn having a sufficiently soft feel can be obtained. For this reason, the following method, which has been used to obtain a soft flat multifilament yarn,
There is no need to use ultra-fine multifilaments of 0.9 denier or less.

The high elongation multifilament (Fe) satisfying the above requirements (A) to (D) can be heated at a temperature higher than the boiling water relaxation temperature, e.g., after the boiling water relaxation treatment.
It exhibits self-extension at temperatures above 120°C.

The high elongation multifilament (Fe) is substantially made of polyethylene terephthalate.

Although the ultra-soft multifilament yarn of the present invention is obtained through false twisting, it is not heat-set during the false twisting process, and therefore does not form false-twist crimps or cause deformation in the cross-sectional shape of the filaments. Therefore, the ultra-soft multifilament yarn of the present invention has substantially no torque, and its constituent multifilaments are in a uncrimped (flat) state.

In the false twisting step of the method of the present invention, the heating temperature applied to the false twisted multifilament yarn is lower than the glass transition temperature of the multifilament, so the cross-sectional shape of the multifilament is not deformed and no crimping occurs due to untwisting.

That is, the ultra-soft multifilament yarn of the present invention is formed from a highly extensible multifilament 11 and a less extensible spread filament 12 in the manufacturing process shown in Figure 3, and the resulting multifilament yarn contains two or more types of multifilaments with different heat shrinkage properties. Therefore, the multifilament yarn of the present invention has latent differential shrinkage properties.

In order to improve such potential differential shrinkage, the multifilament yarn of the present invention preferably contains the high elongation multifilament (Fe) having an elongation of 60% or more and the low elongation multifilament (Fc) having an elongation of 50% or less.
c) shrinks at temperatures below 180°C.

The low elongation multifilament (Fc) also consists essentially of polyethylene terephthalate.

The multifilament yarn of the present invention is made up of high elongation multifilaments (Fe) and low elongation multifilaments (Fc).
It is preferable that the high elongation multifilaments (Fe) and the low elongation multifilaments (Fc) are mixed and entangled with each other to form an integrated yarn. The degree of entanglement is preferably in the range of 30 to 80 entanglements/m. The blending weight ratio of the high elongation multifilaments (Fe) and the low elongation multifilaments (Fc) is generally Fe:Fc=3:7.
The single fiber thickness of the high elongation multifilament (Fe) is preferably 1 to 8 denier, and the single fiber thickness of the low elongation multifilament (Fc) is preferably 1.5 to 6 denier.
The ratio of denier (single fiber thickness) of high elongation multifilament (Fe) to low elongation multifilament (Fc) is 0.
It is preferably 7:1 to 1.5:1.

The high elongation multifilament (Fe) may have a circular cross-sectional shape, or may have a non-circular cross-sectional shape such as a triangular shape.

In order to fully develop the potential differential shrinkage characteristics of the multifilament yarn of the present invention in the relaxation step and improve its bulkiness, the multifilament yarn as a whole has a boiling water shrinkage (BWS) of 1.5 to 15%, the high elongation multifilament (Fe) has a boiling water shrinkage of 2 to 6%, and the low elongation multifilament (Fc) has a boiling water shrinkage of 2 to 10%.
It is preferable that the boiling water shrinkage rate is 100% or less.

The multifilament yarn of the present invention can be used to produce an ultra-soft multifilament yarn fabric. Such an ultra-soft fabric can be obtained by weaving or knitting the multifilament yarn of the present invention, and then subjecting the gray fabric to conventional scouring, dyeing, and finishing processes as necessary. The ultra-soft fabric of the present invention has the following properties (a) to (d): (a) a crystallinity (χc) measured by X-ray analysis of 45% or less, preferably 40% or less; (b) a crystalline orientation (fc) of 85% or less, preferably 80% or less; (c) an amorphous density (ρa) of 1.335 g/ ^cm3 or more, preferably 1.345 g/ ^cm3 , with a difference from the density (ρ) of the entire filaments of 0.05 g/ ^cm3 or less; and (d) an amorphous orientation (Δna) of 0.05 or more, preferably 0.
06 or more, and other low elongation multifilaments (Fc').

The high-elongation multifilament (Fe′) has a crystal size in the [010] plane of 45 angstroms or less,
It is also preferable that the crystal size on the [100] plane is 45 angstroms or less.

The single fiber thickness of the high elongation multifilament (Fe') is preferably 1 to 3 deniers.

It was found that the high elongation multifilament (Fe') exhibited a unique behavior of self-extension by dry heat treatment at 120°C or higher. However, the other low elongation multifilament (Fc') further contracted by dry heat treatment at 120°C or higher.
The ultra-soft fabric of the present invention can be made into an ultra-soft bulky fabric by utilizing the different heat shrinkage/elongation behavior of the multifilament yarns (Fe) and (c') of the present invention, which contain high elongation multifilaments (Fe) and low elongation multifilaments (Fc).
The fabric (grey fabric) is subjected to a boiling water relaxation treatment to shrink both filaments (Fe) and (Fc), and then the fabric is subjected to a dry heat treatment at a temperature of 120°C or higher to self-extend the high elongation multifilament (Fe') and shrink the low elongation multifilament (Fc'),
The difference in fiber length (thread length difference) between the two multifilaments is increased. As a result, the difference in fiber length between the high-elongation multifilament (Fe') and the low-elongation multifilament (Fc') is 3 to 10 times the length of the low-elongation multifilament (Fc').
%, and more preferably 5 to 10%. In contrast, the fiber length difference between different multifilaments in conventional differential shrinkage composite multifilament yarns is at most 3%.

The steps of the method of the present invention appear to be similar at first glance to the steps of the method for producing so-called false twisted two-layer structure textured yarns as found in Japanese Patent Publication Nos. 61-19733 and 56-25529, but the effects and the structure of the textured yarns produced thereby are completely different.

That is, in the case of conventional false twisted two-layer structure textured yarn, one multifilament is wound around another multifilament in the false twisting process, and this is heated to a high temperature,
This twisted shape reorients and crystallizes the polymer molecules of the multifilaments, so both multifilaments are heat-set in the false-twisted, wound shape. Therefore, even when this composite is untwisted, the wound and twisted shapes of the wound filaments remain, resulting in a "wrapped" two-layer textured yarn as shown in Figure 4(a). Such conventional false-twisted, two-layer textured yarns are characterized by having a spun-yarn-like feel. In contrast, in the method of the present invention, even if a high-extensibility multifilament is wound around a low-extensibility multifilament by false twisting, the yarn is not heat-set in this state, so the wound and twisted shapes do not remain at all, and the resulting textured yarn has straight filaments as shown in Figure 4(b).
The textured yarn does not have a spun-yarn-like structure (it has no crimp). That is, the filaments in the textured yarn are straight, and therefore a multifilament yarn with substantially no crimp is formed. In the method of the present invention, by false-twisting a highly extensible multifilament yarn while forcibly stretching it at a low temperature, the resulting textured yarn is a multifilament yarn with an extremely soft touch and a unique feel, which is completely different from conventional false-twisted draw-textured yarns.

In addition, when the filaments are forcibly drawn at a temperature below the glass transition temperature of the filaments, for example, at room temperature, the polymer molecules are in a frozen state, so the drawing tension becomes very large, especially at a spinning speed of 20
For filaments in which the polymer molecules are hardly oriented, such as undrawn yarns produced at a speed of 00 m/min or less, the force required for drawing is extremely large. Therefore, low-temperature drawing by such conventional methods can cause draw laps, yarn breakage, fluffing, or slippage, making it extremely difficult to carry out the drawing process smoothly. However, when the filaments are drawn using a twisting force, as in the method of the present invention, the drawing is carried out smoothly. This drawing force is mainly the twisting force (twisting force).
Therefore, as in the case of using a stretching machine,
There is no need for equipment for winding the yarn around a roller multiple times.In other words, the method of the present invention has the advantage that it can be easily drawn without any production problems using a simple one-nip roller device such as a false twisting machine.

Furthermore, the flat multifilament yarn of the present invention has an extremely soft and unique feel that has never been achieved with conventional synthetic fiber yarns. In particular, although polyester fibers having a relatively high modulus and therefore a stiff feel and a strong stiffness are used in the present invention, the characteristic stiffness of conventional polyester fibers is eliminated, and a filament yarn with an extremely soft and unique feel and an extremely soft and warm touch can be obtained. Such multifilament yarn of the present invention can be used in a wide range of applications, such as innerwear such as lingerie that comes into direct contact with the skin, and baby clothing, and its advantages are enormous.

Furthermore, the inherently hard texture of the polyethylene terephthalate fiber used as the filament material in the present invention is significantly improved by the method of the present invention, resulting in an extremely soft and unique texture. Furthermore, since polyethylene terephthalate has a relatively high glass transition temperature, the effect of low-temperature freezing and drawing in the method of the present invention can be more significantly exerted, thereby clearly demonstrating the effects of the present invention.

EXAMPLES The present invention is further illustrated by the following examples.

In the examples, the following measurements were carried out.

X-ray crystallinity (χc) The X-ray diffraction intensity curve of the test sample was measured using an X-ray generator (RAD-III A) manufactured by Rigaku Corporation in combination with a counter PSPC system. The measurement conditions were 35 kv x 10 mA, CuKα radiation N
An i filter was used, with a divergent slit of 1mm diameter.

The sample was rotated in a plane perpendicular to the X-ray beam, and the total scattering intensity curve was measured (in the case of polyethylene terephthalate filaments, measurements were made at 2θ = 10° to 40°). Similarly, the scattering intensity curve of an amorphous sample was measured, and the crystallinity χc was calculated using the following equation.

Crystal orientation degree (fc) by X-ray method (10) Calculated from the half-value width H° of the intensity curve in the azimuth angle direction using the following formula.

Note: Diffraction on the (100) plane does not result in spots converging on the equator, but may be separated above and below the equator line. For this reason, diffraction on the (10) plane was used.

Birefringence (Δn) was measured using a polarizing microscope by the Cénarmot method.

Density (ρ) Using a density gradient column, in n-heptane/carbon tetrachloride,
Measurements were taken at 25°C.

Crystallinity by density method (χρ) χρ was calculated using the following formula:

The degree of orientation of the amorphous part Δna Δna was calculated by the following formula.

Δna = (Δn - 0.212fc χρ) / (1 - χρ) Amorphous part density ρa ρa was calculated using the following formula:

ρa = (1 - χc) / (1/ρ - χc/ρc), where ρc = 1.455 g/cm ³ .

X-ray crystal size The crystal size is shown below using the (100) and (010) plane reflections.
It was calculated using Scherrer's formula.

L _hkl = Kλ/ _βcosθhkl , where L _hkl is the crystal size perpendicular to the (hkl) plane. β is the half-width of the reflection profile, which was calculated from β = _βM - _βE , where _βM is the measured value and _βE is the instrument constant. K is a constant of 0.94, θ is the Bragg angle, and λ is the wavelength of the X-rays, 1.5418Å.
is.

Boiling Water Shrinkage (BWS) and Dry Heat Shrinkage (HS) of Multifilament Yarn A skein of approximately 3000 denier was prepared, and a load of 0.1 g/de was applied to it, and the original length l ₀ (cm) was read. The load of the skein was changed to 2 mg/de, and it was heat-treated in boiling water for 30 minutes, dried at room temperature, and then the load was changed to 0.1 g/de, and the length l ₁ (cm) was read. Next, the load was changed again to 2 mg/de, and it was dried at 180
After heat treatment in heated air at 0.degree. C. for 1 minute, the specimen was taken out, the load was changed to 0.1 g/de, and the length _l.sup.2 (cm) was read.

Self-stretching rate = BWS (%) - HS (%) The flexibility of the fabric was evaluated by bending stiffness (BS), and the resilience of the fabric was evaluated by bending resilience (BR). The measurement method was JIS L
1096, 6.20.3.C (bending resistance loop compression method) was used.

The anti-pilling property was measured and evaluated using an ICI type testing machine as specified in JIS L 1076, Section 4.1, in accordance with Method A (method using an ICI type testing machine) as specified in Section 6.1 of the same test method.

The abrasion resistance was measured by the method specified in JIS L 1096, A-3 method (crease method), using #600 abrasive paper.

Example 1 Birefringence: 0.009, natural stretch ratio: 152% (stretching ratio: 2.
52 times), elongation: 342%, glass transition temperature: 80°C, fineness: 90de,
Number of filaments: 24, cross-sectional shape: circular polyethylene terephthalate low-oriented unstretched yarn, birefringence: 0.043, natural stretch ratio: 45% (1.45 times), elongation: 140%, glass transition temperature: 80°C, fineness: 78de, number of filaments: 36,
The cross-sectional shape was a circular polyethylene terephthalate highly oriented undrawn yarn, and the yarn was drawn together in a blending ratio of 54:46. This was then fed to an air entangling nozzle under the conditions of an overfeed of 1.0% and an air pressure ^of 4 kg/cm² to entangle the filaments. Next, the yarn was placed in a three-axis friction false twisting device rotating at a surface speed of 630 m/min, with a speed of 350 m/min, an elongation of 55%, a false twist tension of 32 g, and
Untwisting tension: 27g of stretch twisting was applied at room temperature (25°C) (D/Y =
1.8), twist the intertwined multifilament yarn and then untwist it, then overfeed it at 0% and 230
Heat it through a ℃ heater (heat treatment time 0.2 seconds),
The heat shrinkage of each filament was reduced, and the resulting textured yarn was wound on a winder to obtain a 106 denier/60 filament textured yarn. Microscopic observation of this yarn revealed no deformation in the cross-sectional shape of each filament. Furthermore, the yarn itself was non-torqued, and substantially no crimp was observed in the filaments, showing the same appearance as the original mixed multifilament yarn.

In the above processing, when only drawing was carried out without using the false twisting device, the required drawing tension was 120 g.

The properties of the resulting multifilament yarn are shown in Table 1.

In addition, the high elongation multifilament component (Fe) derived from the low-oriented undrawn yarn in the obtained multifilament yarn
The fiber structure and properties of the low elongation multifilament component (Fc) derived from the highly oriented undrawn yarn are shown in Table 2.

This textured yarn was used to prepare a dyed fabric under the following weaving conditions (weave: twill) and alkali treatment and dyeing conditions.

The properties of the resulting fabric are shown in Table 4.

In addition, when the alkali weight reduction treatment was not performed, the fiber structure and properties of the high-elongation multifilament component (Fe') derived from the low-oriented undrawn yarns constituting the woven fabric and the low-elongation multifilament component (Fc') derived from the highly oriented undrawn yarns were as shown in Table 5.

Example 2 Birefringence: 0.008, natural stretch ratio: 174% (2.74 in terms of stretch ratio)
times), elongation: 408%, glass transition temperature: 80°C, fineness: 150de,
Number of filaments: 20 polyethylene terephthalate low-oriented unstretched yarn, orientation degree: 0.048, natural stretch ratio: 45% (1.45 times), elongation: 128%, glass transition temperature: 80°C,
The yarn was mixed with polyethylene terephthalate highly oriented undrawn yarn having a fineness of 115 de and a number of filaments of 15 in a blending ratio of 67:43, and then overfed at 1.0% and compressed air pressure of 4.0 kg/cm ^{2 .}
The entangled yarn was then fed to an air entanglement nozzle at a speed of 400 m/min, and the filaments were entangled with each other.
The yarn was passed through a 50% elongation rate (false-twist tension: 47 g, untwist tension: 44 g) to give it a draw-twisting process (D/Y = 2.0) at room temperature (30°C), twisted once, and then untwisted.The yarn was then passed through a heater at 245°C (heat treatment time: 0.2 seconds) with an overfeed rate of 0.2% to reduce the thermal shrinkage of each filament, and then taken up on a winder to give a 176 denier/35 filament yarn.
When this yarn was observed under a microscope, no deformation was observed in the cross section of each filament. Furthermore, the yarn itself was non-torque and had no crimp, and had the same appearance as a normal mixed-fiber flat yarn.

In the above processing, when only drawing was performed without using the false twisting device, the required drawing tension was 155 g.

The properties of the resulting textured yarn are shown in Table 6.

In addition, the fiber structure and properties of the high elongation multifilament component (Fe) derived from the low oriented undrawn filaments in this multifilament yarn and the low elongation multifilament component (Fc) derived from the high oriented undrawn filaments are as follows:
It was as shown in the table.

This multifilament yarn was used to prepare a dyed fabric under the following weaving conditions (weave: twill), alkali weight reduction treatment and dyeing conditions.

The properties of the resulting fabric are shown in Table 9.

Therefore, the multifilament yarn of the present invention is a monofilament
When the de is large, it gives a soft fabric with excellent resilience, eliminating the need for alkali weight reduction processing. Furthermore, as an additional feature of this yarn, as is clear from Table 4 and this table, it has remarkably improved anti-pilling properties and abrasion resistance.

In addition, the fiber structure and properties of the high-elongation multifilament component (Fe′) derived from the low-oriented undrawn yarn that constitutes the woven fabric are
The results were as shown in Table 10.

The method of the present invention can produce ultra-soft multifilament yarns having an extremely soft and unique feel with simple operation and extremely high efficiency using a false twisting device. Furthermore, the ultra-soft multifilament yarns of the present invention and fabrics made therefrom have a unique feel and excellent physical characteristics, and can be widely used for innerwear such as lingerie, baby clothes, and highly resilient soft clothes for men and women (e.g., suits).

Claims (34)

[Claims] [Claim 1] A method for producing an ultra-soft multifilament yarn, comprising: plying together a low-extensibility multifilament yarn, both of which are made essentially of polyethylene terephthalate and have a degree of orientation (Δn) of 0.03 or more, and a high-extensibility multifilament yarn, both of which have a degree of orientation (Δn) of 0.02 or less and whose difference in extensibility from the low-extensibility multifilament is at least 70% in terms of natural draw ratio (expressed as elongation); subjecting this plyed composite yarn to a false twisting process including a simultaneous drawing and twisting operation and an untwisting operation at a temperature below the glass transition point of the polyethylene terephthalate; uniformly drawing the high-extensibility multifilament while it is wound around the low-extensibility multifilament by the simultaneous drawing and twisting operation; and heat-treating the composite yarn at a temperature of 130°C or more in any step after the untwisting operation. 2. The method of claim 1, wherein the parallel composite yarn is subjected to an air entanglement treatment before the false twisting.
The method described in section. 3. The method according to claim 2, wherein the number of entangled filaments in the entangled yarn obtained in the air entanglement treatment is 40 to 100 per meter. 4. The method of claim 1, wherein said false twisting step is carried out using a friction false twisting tool. 5. The method according to claim 1, wherein said heat treatment step is carried out subsequent to said false twisting step, and the heat treatment temperature is 160° C. or higher. [Claim 6] An ultra-soft multifilament yarn produced by the method of any one of claims 1 to 5, comprising a high-elongation polyester multifilament (Fe) and a low-elongation polyester multifilament (Fc) having different elongations, wherein the high-elongation multifilament (Fe) has an elongation of 60% or more and does not change in cross-sectional shape, and further has the following properties (A) to (D): (A) crystallinity (χρ) by density method: 10% to 30% (B) orientation degree (Δna) of amorphous portion: 0.035 to 0.10 (C) density of amorphous portion (ρa): 1.31 to 1.36 g/cm ³ (D) Young's modulus (YM): 200 to 700 kg/mm ² . 7. The multifilament yarn according to claim 6, wherein the crystallinity (χ) of said high elongation multifilament (Fe) is 15 to 25%. 8. The Young's modulus (YM) of said high elongation multifilament (Fe) is 250 to 450 kg/mm ² according to claim 6.
The multifilament yarn according to paragraph 1. 9. The multifilament yarn according to claim 6, wherein the degree of orientation of the amorphous portion (Δna) of said high elongation multifilament (Fe) is 0.045 to 0.10. 10. The multifilament yarn according to claim 6, wherein the amorphous density (ρa) of said high elongation multifilament (Fe) is 1.33 to 1.35 g/cm ³ . 11. The high elongation multifilament (Fe)
7. The multifilament yarn according to claim 6, which, after being subjected to a boiling water relaxation treatment, has self-extensibility at a temperature higher than the boiling water relaxation temperature. 12. The method of claim 6, wherein the high elongation multifilament (Fe) has a single fiber thickness of 1 to 8 denier.
The multifilament yarn according to paragraph 1. 13. The high elongation multifilament (Fe)
7. The multifilament yarn of claim 6, having an elongation of 80 to 150%. 14. The multifilament yarn of claim 6, wherein said multifilament yarn is substantially torque-free. 15. The multifilament yarn of claim 6, wherein all of said multifilaments are substantially crimp-free. 16. The multifilament yarn according to claim 6, wherein said high elongation multifilaments (Fe) have a non-circular cross section. 17. The method of claim 6, wherein the boiling water shrinkage (BWS) of the high elongation multifilament (Fe) is 2 to 6%.
The multifilament yarn according to paragraph 1. 18. The low elongation multifilament (Fc)
7. The multifilament yarn of claim 6, having an elongation of 50% or less. 19. The low elongation multifilament (Fc)
19. The multifilament yarn of claim 18, which shrinks at a temperature of 180°C or less. 20. The low shrinkage multifilament (Fc).
19. The multifilament yarn of claim 18, having a boiling water shrinkage of 2 to 10%. 21. A multifilament yarn according to claim 6, wherein the high elongation and low elongation multifilaments (Fe) and (Fc) are entangled at an entanglement number of 30 to 80 entanglements/m. 22. The high elongation multifilament (Fe) and the low elongation multifilament (Fc) are mixed in a weight ratio of 3:7.
7. The multifilament yarn of claim 6, wherein the yarn weight ratio is in the range of 8:2. 23. The low elongation multifilament (Fc) according to claim 18, wherein the single fiber thickness is 1.5 to 6 denier.
The multifilament yarn according to paragraph 1. 24. The high elongation multifilament (Fe)
7. The multifilament yarn according to claim 6, wherein the denier ratio of the low elongation multifilament (Fc) to the low elongation multifilament (Fc) is 0.7:1 to 1.5:1. 25. The multifilament yarn of claim 6, having an overall boiling water shrinkage of 1.5 to 15%. 26. A multifilament yarn comprising the multifilament yarn of claim 6, having the following characteristics (a) to (c):
(d) An ultra-soft multifilament yarn fabric comprising a high-elongation multifilament (Fe') having: (a) a crystallinity (χc) of 45% or less as measured by X-ray method; (b) a crystalline orientation (fc) of 85% or less; (c) an amorphous portion density (ρa) of ^1.335 g/ ^cm3 or more, the difference from the density of the entire filament being 0.05 g/cm3 or more; and (d) an amorphous portion orientation (Δna) of 0.05 or more. 27. The high elongation multifilament (Fe')
The degree of crystallinity (χc) of claim 26 is 40% or less.
The fabric described in paragraph . 28. The high elongation multifilament (Fe')
The fabric of claim 26, having a degree of crystal orientation of 80% or less. 29. The high elongation multifilament (Fe')
The fabric according to claim 26, wherein the density (ρa) of the amorphous part is 1.345 g/cm ³ or more. 30. The high elongation multifilament (Fe')
The fabric according to claim 26, wherein the degree of orientation of the amorphous portion (Δna) is 0.06 or more. 31. The high elongation multifilament (Fe')
27. The fabric of claim 26, wherein the crystal size of the [010] plane is 45 angstroms or less, and the crystal size of the [100] plane is also 45 angstroms or less. 32. The high elongation multifilament (Fe')
The single fiber thickness of claim 26 is 1 to 3 denier.
The fabric described in paragraph . 33. The high elongation multifilament (Fe')
The difference in fiber length between the low elongation multifilament (Fc') and the low elongation multifilament (Fc') is
The fabric according to claim 26, wherein the low elongation multifilament (Fc') has a length of 3 to 10% based on the length. [Claim 34] A fabric described in any one of claims 26 to 33, wherein the fabric has been subjected to a relaxation treatment in hot water at a temperature of 80°C or higher, and then to a dry heat treatment at a temperature of 120°C or higher, thereby bulking the fabric.