U.S. patent application number 16/320998 was filed with the patent office on 2019-06-13 for polyamide multifilament, and lace knit and stockings using same.
The applicant listed for this patent is Toray Industries, Inc.. Invention is credited to Takahiro Kuribayashi, Kentaro Takagi, Daisuke Yoshioka.
Application Number | 20190174837 16/320998 |
Document ID | / |
Family ID | 61016521 |
Filed Date | 2019-06-13 |
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United States Patent
Application |
20190174837 |
Kind Code |
A1 |
Yoshioka; Daisuke ; et
al. |
June 13, 2019 |
POLYAMIDE MULTIFILAMENT, AND LACE KNIT AND STOCKINGS USING SAME
Abstract
A polyamide multifilament has a tensile strength at 15%
elongation of 4.0 to 6.0 cN/dtex, a strength-elongation product of
10.0 cN/dtex or more, and a yarn unevenness (U %) of 1.2 or less.
The high-strength polyamide multifilament makes it possible to
obtain stockings having high softness, durability, and
transparency, and a lace knit in which patterns have a beautiful
appearance.
Inventors: |
Yoshioka; Daisuke; (Nagoya,
JP) ; Takagi; Kentaro; (Nagoya, JP) ;
Kuribayashi; Takahiro; (Nagoya, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Toray Industries, Inc. |
Tokyo |
|
JP |
|
|
Family ID: |
61016521 |
Appl. No.: |
16/320998 |
Filed: |
July 11, 2017 |
PCT Filed: |
July 11, 2017 |
PCT NO: |
PCT/JP2017/025223 |
371 Date: |
January 25, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D02G 3/02 20130101; D10B
2331/02 20130101; D02G 3/44 20130101; D01F 6/60 20130101; D10B
2501/021 20130101; D04B 21/207 20130101; D02G 3/38 20130101; D04B
21/12 20130101; A41B 11/14 20130101 |
International
Class: |
A41B 11/14 20060101
A41B011/14; D02G 3/02 20060101 D02G003/02; D04B 21/12 20060101
D04B021/12; D02G 3/38 20060101 D02G003/38; D02G 3/44 20060101
D02G003/44; D04B 21/20 20060101 D04B021/20; D01F 6/60 20060101
D01F006/60 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 26, 2016 |
JP |
2016-146049 |
Claims
1.-6. (canceled)
7. A polyamide multifilament having a tensile strength at 15%
elongation of 4.0-6.0 cN/dtex, a strength-elongation product of
10.0 cN/dtex or larger, and a yarn unevenness (U %) of 1.2 or
less.
8. The polyamide multifilament according to claim 7, having a
single-filament fineness of 1.3-3.4 dtex.
9. The polyamide multifilament according to claim 7, having an
elongation of 30-50%.
10. The polyamide multifilament according to claim 7, having a sum
of a content of crystals and a content of rigid amorphous
components of 70-90%.
11. A knitted lace produced using the polyamide multifilament
according to claim 7 as a ground lace yarn.
12. A stocking partly comprising a covered yarn obtained using the
polyamide multifilament according to claim 7 as a covering
yarn.
13. The polyamide multifilament according to claim 8, having an
elongation of 30-50%.
14. The polyamide multifilament according to claim 8, having a sum
of a content of crystals and a content of rigid amorphous
components of 70-90%.
15. The polyamide multifilament according to claim 9, having a sum
of a content of crystals and a content of rigid amorphous
components of 70-90%.
16. A knitted lace produced using the polyamide multifilament
according to claim 8 as a ground lace yarn.
17. A knitted lace produced using the polyamide multifilament
according to claim 9 as a ground lace yarn.
18. A knitted lace produced using the polyamide multifilament
according to claim 10 as a ground lace yarn.
19. A stocking partly comprising a covered yarn obtained using the
polyamide multifilament according to claim 8 as a covering
yarn.
20. A stocking partly comprising a covered yarn obtained using the
polyamide multifilament according to claim 9 as a covering
yarn.
21. A stocking partly comprising a covered yarn obtained using the
polyamide multifilament according to claim 10 as a covering
yarn.
22. A stocking partly comprising a covered yarn obtained using the
polyamide multifilament according to claim 11 as a covering yarn.
Description
TECHNICAL FIELD
[0001] This disclosure relates to a polyamide multifilament, more
particularly, to a polyamide multifilament with which stockings
excellent in terms of softness, durability, and sense of
transparency can be provided and which, when used as a ground lace
yarn, is capable of providing a knitted lace having excellent
durability and having a pattern that looks attractive.
BACKGROUND
[0002] Polyamide fibers and polyester fibers, which are synthetic
fibers, are in extensive use in clothing applications and
industrial applications because of their excellent properties
regarding mechanical and chemical properties. In particular,
polyamide fibers are excellent in terms of the peculiar softness,
high strength, colorability by dyeing, heat resistance,
hygroscopicity and the like, and are hence in extensive use in
general clothing applications including stockings, innerwear, and
sportswear.
[0003] A consumer need regarding laces is patterns which look
attractive. There has hence been a desire for durability on a
conventional level and the sense of transparency of ground lace
yarn. Consumer needs regarding stockings are comfortableness to
wear and the sense of bare skin and there has hence been a desire
for durability on a conventional level, softness, and sense of
transparency. Namely, for replacement by polyamide fibers for
clothing, it has been strongly desired to enhance fineness while
maintaining conventional strength.
[0004] Various techniques to heighten the strength of polyamide
fibers have been proposed to overcome these problems. For example,
JP 2003-129331 A proposes a knitted lace including a high-viscosity
type nylon-6 filament having an elongation of 51-64% and a strength
of 4.2-6.5 cN/dtex.
[0005] WO 2016/76184 proposes a stocking including a polyamide
filament having an elongation of 40-50% and a strength-elongation
product of 9.1 cN/dtex or larger and about 9.8 cN/dtex.
[0006] JP 63-159521 A proposes a tire cord and a belt that each
include polyamide-based fibers having an elongation of about
16-18%, a strength of 9.8 cN/dtex or higher, and a
strength-elongation product of about 11.4-12.2 cN/dtex.
[0007] However, the method described in JP 2003-129331 A, although
capable of obtaining a lace having a pattern that looks attractive,
is disadvantageous in that the fiber modulus and the
strength-elongation product are low and the knitted lace obtained
therefrom has unsatisfactory product strength.
[0008] When the method described in WO 2016/76184 is used to
produce a filament having a fineness suitable for covering yarns
for single-covered elastic yarns, the fiber modulus and the
strength-elongation product are low and the stockings obtained
therefrom have unsatisfactory product strength.
[0009] When the method described in JP 63-159521 A is used in
clothing applications, the modulus of the fibers is so high that
the fibers are poor in high-order process passage capability in
steps of producing a lace or stocking to suffer fiber breakage,
fluffing and the like.
[0010] It could therefore be helpful to provide a high-strength
polyamide multifilament having a large strength-elongation product
and a proper fiber modulus. More particularly, it could be helpful
to provide: a knitted lace having the enhanced sense of
transparency of the ground lace yarn while retaining durability and
that can have a pattern that looks attractive; and a stocking
having excellent sense of transparency and softness, since
excellent high-order process passage capability, excellent product
appearance quality, and a higher fineness can be obtained by using
the polyamide multifilament having a large strength-elongation
product and a proper fiber modulus.
SUMMARY
[0011] We thus provide:
(1) A polyamide multifilament having a tensile strength at 15%
elongation of 4.0-6.0 cN/dtex, a strength-elongation product of
10.0 cN/dtex or larger, and a yarn unevenness (U %) of 1.2 or less.
(2) The polyamide multifilament according to (1), having a
single-filament fineness of 1.3-3.4 dtex. (3) The polyamide
multifilament according to (1) or (2), having an elongation of
30-50%. (4) The polyamide multifilament according to any one of (1)
to (3), having a sum of a content of crystals and a content of
rigid amorphous components of 70-90%. (5) A knitted lace produced
using the polyamide multifilament according to any one of (1) to
(4) as a ground lace yarn. (6) A stocking partly comprising a
covered yarn obtained using the polyamide multifilament according
to any one of (1) to (4) as a covering yarn.
[0012] The polyamide multifilament is a high-strength polyamide
multifilament having a large strength-elongation product and a
proper fiber modulus. Furthermore, since the polyamide
multifilament has excellent high-order process passage capability
and excellent product appearance quality and is capable of
obtaining a higher fineness, a knitted lace having the enhanced
sense of transparency of the ground lace yarn while retaining
durability and that can have a pattern that looks attractive and a
stocking having excellent sense of transparency and softness can be
obtained from the polyamide multifilament.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 shows one example of production devices that can be
advantageously used in a method of producing a polyamide
multifilament.
[0014] FIG. 2 is a diagrammatic sectional model diagram showing a
spinneret and a heating cylinder that can be advantageously used in
a method of producing a polyamide multifilament.
DESCRIPTION OF REFERENCE NUMERALS AND SIGNS
[0015] 1: Spinneret [0016] 2: Gas ejector [0017] 3: Heating
cylinder [0018] 4: Cooler [0019] 5: Oiling device [0020] 6: Fluid
entangling nozzle device [0021] 7: Take-up roller [0022] 8: Drawing
roller [0023] 9: Winding device [0024] L: Length of multilayered
heating cylinder [0025] L1: Single-layer length of multilayered
heating cylinder [0026] LS: Cooling initiation distance [0027] Lg:
Oiling position
DETAILED DESCRIPTION
[0028] Our multifilaments, knits, stockings and methods are
explained in more detail below.
[0029] The polyamide multifilament has a tensile strength at 15%
elongation of 4.0-6.0 cN/dtex, a strength-elongation product of
10.0 cN/dtex or larger, and a yarn unevenness (U %) of 1.2 or
less.
[0030] The polyamide constituting the polyamide multifilament is a
resin including a high-molecular-weight substance in which
hydrocarbon groups are bonded to a main chain via amide bonds. The
polyamide is excellent in terms of spinnability and mechanical
property. The polyamide preferably is one mainly including
polycaproamide (nylon-6) or polyhexamethyleneadipamide (nylon-66).
More preferably is one mainly including polycaproamide (nylon-6)
because of the unsusceptibility to gelation and satisfactory
spinnability thereof. The term "mainly" means that in
polycaproamide, this polyamide contains at least 80% by mole
.epsilon.-caprolactam as constituent units constituting the
polycaproamide, and that in polyhexamethyleneadipamide, this
polyamide contains at least 80% by mole hexamethylenediammonium
adipate as constituent units constituting the
polyhexamethyleneadipamide. More preferably, the content of these
constituent units is 90% by mole or higher. Other components are
not particularly limited, and examples thereof include units of
aminocarboxylic acids, dicarboxylic acids, diamines, and the like
which are monomers constituting polydodecanoamide,
polyhexamethyleneadipamide, polyhexamethyleneazelamide,
polyhexamethylenesebacamide, polyhexamethylenedodecanoamide,
poly-m-xyleneadipamide, polyhexamethyleneterephthalamide,
polyhexamethyleneisophthalamide and the like.
[0031] From the standpoint of effectively producing the desired
effects, it is preferable that the polyamide contains none of
various additives including delustering agents represented by
titanium oxide. However, the polyamide may contain additives, e.g.,
a heat resistance improver so long as the inclusion thereof does
not impair the desired effects. Additives may be incorporated
according to need to result in a content of 0.001-0.1 wt %.
[0032] The polyamide multifilament must have a 15% strength, a
strength-elongation product, and a U % which are in the respective
ranges shown above. The reasons for this is as follows. Increasing
the fineness enhances the sense of transparency of the ground lace
yarn to give a knitted lace having a pattern which looks attractive
or give stockings having excellent sense of transparency and
softness. However, product strength is reduced and durability
becomes poor so that the products do not withstand practical use.
To obtain durability that enables the products to withstand
practical use, it is necessary to heighten the strength-elongation
product. Furthermore, to maintain high-order process passage
capability and product appearance quality, it is necessary to make
the multifilament yarn have proper values of 15% strength and U
%.
[0033] We discovered that to provide a knitted lace excellent in
terms of high-order process passage capability, product appearance
quality, and durability and that has the enhanced sense of
transparency of the ground lace yarn and can have a pattern that
looks attractive and to provide stockings having excellent sense of
transparency and softness, it is essential to regulate the 15%
strength, strength-elongation product, and U % to values within
proper ranges.
[0034] The polyamide multifilament must have a strength-elongation
product of 10.0 cN/dtex or larger. Due to the strength-elongation
product within that range, the stocking and the lace have
durability which enables the stocking and the lace to withstand
practical use. When the strength-elongation product thereof is less
than 10.0 cN/dtex, not only the stocking and the lace have such
poor durability that the stocking and the lace do not withstand
practical use but also the multifilament has impaired high-order
process passage capability and filament breakages occur at a higher
frequency in high-order processing steps. The strength-elongation
product of the polyamide multifilament is more preferably 10.3
cN/dtex or larger. The larger the strength-elongation product, the
more the multifilament is preferred. However, an upper limit
thereof is about 11.0 cN/dtex.
[0035] The polyamide multifilament must have a tensile strength at
15% elongation (hereinafter referred to as "15% strength"), which
is an index to yarn properties, of 4.0-6.0 cN/dtex. The 15%
strength is determined by making a measurement in accordance with
JIS L1013-2010, Tensile Strength and Elongation, drawing a tensile
strength-elongation curve, dividing the tensile strength (cN) at
15% elongation by the fineness, and taking the resultant value as
the 15% strength. The 15% strength is a value which roughly
indicates the fiber modulus. When the 15% strength is high, the
tensile strength-elongation curve has a large inclination, showing
that the fiber modulus is high. Meanwhile, when the 15% strength is
low, the tensile strength-elongation curve has a small inclination,
showing that the fiber modulus is low.
[0036] Since the polyamide multifilament has a 15% strength within
that range, the stocking and the knitted lace not only have
durability that enables the stocking and the knitted lace to
withstand practical use, but also have excellent softness. When the
15% strength thereof is less than 4.0 cN/dtex, the multifilament
has a reduced strength-elongation product and the stocking and the
knitted lace have such poor durability that the stocking and the
knitted lace do not withstand practical use. When the 15% strength
exceeds 6.0 cN/dtex, the multifilament not only has a reduced
elongation to give stockings and knitted laces which are stiff in
feeling and have reduced softness but also has impaired high-order
process passage capability to suffer filament breakages at a higher
frequency in high-order processing steps, resulting in reduced
product appearance quality. The 15% strength thereof is preferably
4.5-5.5 cN/dtex.
[0037] The polyamide multifilament preferably has an elongation of
30-50%. By regulating the elongation thereof to be within that
range, the multifilament is rendered less apt to suffer filament
breakages in high-order processing steps and is made to have
satisfactory high-order process passage capability and product
appearance quality. The multifilament shows excellent high-order
process passage capability especially when used in high-speed
knitting or weaving. When the elongation thereof is 30% or higher,
the multifilament shows satisfactory high-order process passage
capability to be less apt to suffer filament breakages in
high-order processing steps such as stocking production steps (the
step of producing a covered yarn and the step of knitting a
stocking) or knitted-lace production steps (warping step and
weaving step). Furthermore, the stocking and the knitted lace give
a satisfactory soft feeling. When the elongation thereof is 50% or
less, this multifilament has a sufficient strength-elongation
product and the stocking and the knitted lace have durability which
enables the stocking and the knitted lace to withstand practical
use. In addition, the multifilament has improved high-order process
passage capability to be less apt to suffer filament breakages in
high-order processing steps, and has improved product appearance
quality. The elongation thereof is more preferably 35-45%.
[0038] It is preferable that in the polyamide multifilament, the
sum of the content of crystals and the content of rigid amorphous
components is 70-90%. The content of crystals and the content of
rigid amorphous components are values calculated in the following
manners.
[0039] The content of crystals (Xc) is determined by calculating
the difference (.DELTA.Hm-.DELTA.Hc) between the quantity of heat
of fusion and the quantity of heat of cold crystallization
determined by DSC and calculating the content of crystals using
equation (1). In equation (1), .DELTA.Hm0 is the quantity of heat
of fusion of the crystalline polyamide, and the value thereof is
229.76 J/g.
[0040] The content of rigid amorphous components (Xra) is
calculated from the content of crystals (Xc) and the content of
movable amorphous components (Xma) using equation (2). The content
of movable amorphous components (Xma) is calculated from a
difference in specific heat (.DELTA.Cp) between before and after a
glass transition observed on a temperature-heat flux reversible
curve determined by temperature-modulated DSC (TMDSC). As the
.DELTA.Cp is used a specific-heat gap between before and after the
glass transition, the specific-heat gap being calculated from an
extrapolated tangent which touches the temperature-heat flux
reversible curve at around the glass transition. The content of
movable amorphous components (Xma) is calculated using equation
(3). In equation (3), .DELTA.Cp0 is a difference in specific heat
between before and after the Tg of the amorphous polyamide, and the
value thereof is 0.4745 J/g.
[0041] The content of rigid amorphous components was calculated
from average values obtained from two measurements made by
temperature-modulated DSC and DSC.
Content of crystals: Xc
(%)=(.DELTA.Hm-.DELTA.Hc)/.DELTA.Hm0.times.100 (1)
Content of rigid amorphous components: Xra (%)=100-(Xc+Xma) (2)
Content of movable amorphous components: Xma
(%)=.DELTA.Cp/.DELTA.Cp0.times.100 (3)
[0042] The sum of the content of crystals and the content of rigid
amorphous components is a value which roughly indicates the degree
of orientation relaxation of the molecular chains of the polyamide
polymer. When the sum of the content of crystals and the content of
rigid amorphous components is high, this indicates that the
molecular chains have a small strain and the fibers are highly
crystalline. When the sum of the content of crystals and the
content of rigid amorphous components is low, this indicates that
the molecular chains are in a highly entangled state and the fibers
are lowly crystalline. By regulating the sum of the content of
crystals and the content of rigid amorphous components to 90% or
less, the polyamide polymer is made to have a moderate
molecular-chain strain amount and polyamide fibers not having too
high crystallinity are obtained, thereby giving stockings and
knitted laces which are excellent in terms of feeling and softness.
By regulating the sum of the content of crystals and the content of
rigid amorphous components to 70% or higher, the molecular chains
of the polyamide polymer are made to have a moderate strain and,
hence, polyamide fibers having excellent crystallinity are
obtained, thereby giving stockings and knitted laces which have
excellent durability. The sum thereof is more preferably
75-85%.
[0043] The polyamide multifilament must have a U % of 1.2 or less.
By regulating the U % thereof to a value within that range, the
multifilament is made excellent in terms of product appearance
quality. When the U % thereof exceeds 1.2, this multifilament is
poor in product appearance quality to give knitted laces which upon
dyeing come to have appearance failures such as streaks formed by
deep-dyed thick yarns. More preferably, the U % thereof is 1.0 or
less in stocking applications and is 1.0 or less in knitted-lace
applications. The smaller the U %, the more the multifilament is
preferred. However, a lower limit thereof is about 0.4.
[0044] The polyamide multifilament preferably has a total fineness
of 4.0-33.0 dtex from the standpoint of clothing applications. The
total fineness thereof is more preferably 4.0-11.0 dtex in stocking
applications and 20.0-30.0 dtex in lace applications.
[0045] The polyamide multifilament preferably has a single-filament
fineness of 1.3-3.4 dtex. When the single-filament fineness thereof
is in that range, this polyamide multifilament gives stockings and
laces which are excellent in terms of durability and softness. The
single-filament fineness thereof is more preferably 1.6-3.2
dtex.
[0046] The polyamide multifilament preferably has a sulfuric acid
relative viscosity of 2.5-4.0. The sulfuric acid relative viscosity
thereof is more preferably 3.2-3.8. When the sulfuric acid relative
viscosity thereof is 2.5-4.0, this polyamide multifilament gives
stockings and knitted laces having durability that enables the
stockings and knitted laces to withstand practical use.
Furthermore, these products have satisfactory appearance
quality.
[0047] The polyamide multifilament is not particularly limited in
cross-sectional shape thereof. For example, the filaments may have
a circular cross section, a flat cross section, a lens-shaped cross
section, a trifoliate cross section, a multilobar cross section, an
irregular cross section having three to eight protrusions and the
same number of recesses, a hollow cross section, or any of other
known irregular cross sections.
[0048] One example of methods of producing the high-strength
polyamide multifilament is explained in detail. FIG. 1 shows one
example of production devices operated by a direct spinning drawing
method that are advantageously usable in a method of producing a
high-strength polyamide multifilament.
[0049] The polyamide multifilament may be produced in the following
manner. A polyamide resin is melted, and the polyamide polymer is
weighed and transported by a gear pump and finally extruded through
ejection holes formed in a spinneret 1, thereby forming filaments.
The filaments ejected from the spinneret 1 are passed through the
following parts shown in FIG. 1: a gas ejector 2 that ejects steam
to inhibit the spinneret from being fouled with the lapse of time;
a multilayered heating cylinder 3 disposed for gradual cooling to
entirely surround the ejected filaments; and a cooler 4. Thus, the
filaments are cooled to room temperature and solidified.
Thereafter, an oil is applied to the filaments with an oiling
device 5 and the filaments are collected to form a multifilament
that is entangled with a fluid entangling nozzle device 6 and
passed through a take-up roller 7 and a drawing roller 8. During
this passing, the multifilament is drawn in accordance with the
ratio between the peripheral speed of the take-up roller 7 and that
of the drawing roller 8. Furthermore, the yarn is heat-treated with
the heat of the drawing roller 8 and is wound up with a winding
device 9.
[0050] In the production of a polyamide multifilament, it is
preferable that the polyamide resin has a sulfuric acid relative
viscosity of 2.5-4.0. By regulating the sulfuric acid relative
viscosity thereof to a value within that range, a high-strength
polyamide multifilament having a large strength-elongation product
is obtained.
[0051] The melting temperature is preferably higher by
20-95.degree. C. than the melting point of the polyamide.
[0052] In the production of a polyamide multifilament, the heating
cylinder 3 must be disposed over the cooler 4 to entirely surround
the filaments. By disposing the heating cylinder over the cooler 4
and regulating the temperature of the atmosphere within the heating
cylinder to be 100-300.degree. C., the polyamide polymer ejected
from the spinneret 1 can be caused to undergo orientation
relaxation without thermally deteriorating. As a result of the
orientation relaxation due to gradual cooling from the spinneret
surface to the upper surface of the cooler 4, a multifilament
having a high 15% strength and a large strength-elongation product
is obtained. When the heating cylinder is omitted, the orientation
relaxation due to gradual cooling from the spinneret surface to the
upper surface of the cooler 4 is insufficient and it tends to be
difficult to obtain fibers which satisfy both the 15% strength and
the strength-elongation product.
[0053] In the production of a high-strength polyamide
multifilament, the heating cylinder must have a multilayer
configuration. JP 63-159521 A proposes a heating cylinder to keep
the temperature of the atmosphere just under the spinneret at
250-450.degree. C. for the purpose of gradual cooling. Although the
proposed heating cylinder is effective in an industrial
low-fineness region, use thereof for multifilaments for clothing in
a high-fineness region such as our polyamide multifilament, is
disadvantageous in that since the temperature distribution in the
heating cylinder is constant, the thermal convection is prone to be
disordered to affect the solidification of the filaments and this
is a factor that impairs U %. A heating cylinder having a
multilayer configuration is hence disposed and temperatures are set
to decline in stages from the uppermost layer to the lowermost
layer. Thus, thermal convection from the uppermost layer to the
lowermost layer is purposely formed to produce a descending air
flow in the same direction as the flow accompanying the filaments.
As a result, the thermal convection within the heating cylinder is
inhibited from being disordered and filament oscillation is
reduced, thereby obtaining a multifilament having a small value of
U %.
[0054] The length L of the multilayered heating cylinder, although
depending on the fineness of the filaments, is preferably 40-100
mm. It is preferable that the multilayered heating cylinder is
configured of two or more layers, and the single-layer length L1 of
the multilayered heating cylinder is preferably 10-25 mm.
[0055] The atmosphere in the multilayered heating cylinder has
temperatures of 100-300.degree. C., and it is necessary to form a
gentle temperature gradient over the layers. For example, when the
length L of the multilayered heating cylinder is 75 mm and the
single-layer length L1 is 25 mm, it is necessary that the upper
layer have an atmosphere temperature of 250-300.degree. C., the
middle layer have an atmosphere temperature of 200-250.degree. C.,
and the lower layer have an atmosphere temperature of
100-200.degree. C.
[0056] Due to this configuration, an atmosphere-temperature profile
for from the spinneret to the upper surface of the cooler 4 can be
controlled in stages over 100-300.degree. C., thereby yielding a
high-strength polyamide multifilament having satisfactory 15%
strength, strength-elongation product, and U %.
[0057] In the production of a polyamide multifilament, use can be
made of any of methods in which the cooler 4 is a cooler that
ejects cooling/rectifying air A from certain directions, or an
annular cooler which ejects cooling/rectifying air A from the
peripheral side toward the center, or an annular cooler which
ejects cooling/rectifying air from the center side toward the
periphery or the like. The vertical distance LS (hereinafter
referred to as "cooling initiation distance") from the lower
surface of the spinneret to the upper end of the cooling-air
ejection part of the cooler 4 is preferably 159-219 mm from the
standpoints of inhibiting filament oscillation and inhibiting the U
% from increasing, and is more preferably 169-189 mm. With respect
to the velocity of the cooling air ejected from the cooling-air
ejection surface, it is preferable that the velocity thereof is
20.0-40.0 (m/min) in terms of average for the zone ranging from the
upper end to the lower end of the cooling-air ejection part, from
the standpoints of U % and strength-elongation product.
[0058] In the production of a polyamide multifilament, the position
of the oiling device 5, that is, the vertical distance Lg
(hereinafter referred to as "oiling position") from the lower
surface of the spinneret to the position of the oiling nozzle of
the oiling device 5 in FIG. 1, is preferably 800-1,500 (mm), more
preferably 1,000-1,300 (mm), although the distance Lg depends on
the single-filament fineness and the efficiency of the cooling of
the filaments by the cooler. When the distance Lg is 800 (mm) or
longer, the temperature of the filaments declines to a temperature
suitable for the oiling. When the distance Lg is 1,500 mm or less,
the filament oscillation due to the descending air flow is small
and a multifilament having a small value of U % is obtained. In
addition, when the distance Lg is 1,500 mm or less, the distance
from the solidification point to the oiling position is short,
resulting in a diminished accompanying flow and a reduced spinning
tension and hence in reduced spinning orientation. Consequently, a
high-strength multifilament having excellent drawability and is
hence high in strength-elongation product and 15% strength is
obtained. When the distance Lg is 800 (mm) or longer, the bending
of the filaments in the zone ranging from the spinneret to the
oiling guide is appropriate and the filaments are less apt to be
affected by fretting on the guide, thereby inhibiting the
strength-elongation product and the 15% strength from
decreasing.
[0059] In the production of a polyamide multifilament, the spinning
speed is preferably such that the take-up roller 7 is rotated at
1,000-2,000 m/min, which is in a low-speed range. Thus, draft draw
unevenness can be diminished and the filaments can be evenly
cooled, making it possible to obtain a U % as small as 1.2 or less.
When the speed thereof is 2,000 m/min or less, spinning orientation
is inhibited and the gradually cooling effect of the heating
cylinder is heightened, thereby enhancing the strain relaxation of
the molecular chains. As a result, a high-strength multifilament
having a high 15% strength and a large strength-elongation product
is obtained.
[0060] It is preferable that the drawing roller 8 is used as a
heating roller to conduct a heat treatment so that the heat-setting
length is 500-1,200 mm and the heat treatment temperature is
120-180.degree. C. This is because a proper heat treatment makes it
possible to design the heat shrinkage of the multifilament. When
the heat-setting length is 500 mm or larger, the fibers undergo
sufficient crystallization, resulting in an increased 15% strength,
thereby yielding products having excellent durability. When the
heat-setting length is 1,200 mm or less, crystallization in the
fibers is prevented from proceeding excessively and a high-strength
polyamide multifilament having a 15% strength in a proper range and
having excellent process passage capability in high-order
processing steps is obtained, the multifilament giving products
having a soft feeling.
[0061] A polyamide multifilament can be produced by disposing a
heating cylinder over the cooler 4, regulating the atmosphere
within the heating cylinder to have temperatures of 100-300.degree.
C., configuring the heating cylinder as a multilayer type heating
cylinder, thereby forming a temperature gradient in the heating
cylinder and purposely forming a descending air flow in the same
direction as the flow accompanying the filaments, and regulating
the oiling position to 800-1,500 mm from the spinneret surface, the
spinning speed to 1,000-2,000 m/min, and the heat-setting length
after drawing to 500-1,200 mm.
[0062] By employing such conditions for the direct spinning drawing
method, a high-strength polyamide multifilament having a large
strength-elongation product of 10.0 cN/dtex or larger, a 15%
strength of 4.0-6.0 cN/dtex, and a U % of 1.2 or less is
obtained.
[0063] The polyamide multifilament as such may be fed as a ground
yarn to a lace knitting machine to knit a lace fabric by an
ordinary method. The lace fabric may be one of any of ordinary knit
stitches such as an embroidery lace, raschel lace, leaver lace or
the like.
[0064] The polyamide multifilament may be used as the covering yarn
of a covered yarn. The covered yarn may be a single-covered yarn
obtained by single-winding the covering yarn around an elastic
fiber such as an elastic polyurethane fiber or an elastic polyamide
elastomer fiber, as a core yarn or a double-covered yarn obtained
by double-winding the covering yarn around the core yarn.
[0065] The polyamide multifilament may be used in stockings that
partly include the covered yarn. As a knitting machine for knitting
the stockings, an ordinary hosiery machine can be used without
limitations. A knitting machine having two or four yarn feeders may
be used by an ordinary method in which the covered yarn is fed to
knit the stocking.
[0066] With respect to conditions for dyeing after the knitting,
succeeding post-processing, and final setting, these steps may be
conducted by known methods. Usable dyes include acid dyes and
reactive dyes, and the dyeing is not limited in color and the
like.
EXAMPLES
[0067] Our multifilaments, knits, stockings and methods are
explained in more detail below by reference to Examples.
A. Strength, Elongation, Strength-elongation Product, 15%
Strength
[0068] A fiber sample was examined in accordance with JIS
L1013-2010, Tensile Strength and Elongation, to draw a tensile
strength-elongation curve. The test conditions included a
constant-rate extension type tester, a chuck-to-chuck distance of
50 cm, and a stretching speed of 50 cm/min. When the tensile
strength at break was lower than the maximum strength, the maximum
tensile strength and the corresponding elongation were
measured.
[0069] The strength and the strength-elongation product were
determined using the following equations.
Elongation=elongation at break (%)
Strength=[tensile strength at break (cN)]/[fineness (dtex)]
Strength-elongation product={strength (cN/dtex)}.times.{elongation
(%)+100}/100 15% strength=[tensile strength at 15% elongation
(cN)]/[fineness (dtex)]
B. Total Fineness, Single-Filament Fineness
[0070] A fiber sample was set on a sizing reel having a
circumference of 1.125 m, and the sizing reel was rotated to make
500 turns to produce a loop-like hank. The hank was dried in a
hot-air drying oven (105.+-.2.degree. C..times.60 min) and weighed
with a balance. The measured weight was multiplied by an official
moisture regain, and the fineness was calculated from the resultant
value. The official moisture regain was assumed to be 4.5%.
C. Sulfuric Acid Relative Viscosity (.eta.r)
[0071] A polyamide chip sample or fiber sample in an amount of 0.25
g was dissolved in sulfuric acid having a concentration of 98% by
mass so that the sample amount was 1 g per 100 mL of the sulfuric
acid. Using an Ostwald viscometer, the solution was examined for a
flow time (T1) at 25.degree. C. Subsequently, the sulfuric acid
alone having a concentration of 98% by mass was examined for flow
time (T2). The ratio of T1 to T2, i.e., T1/T2, was taken as the
sulfuric acid relative viscosity.
D. Yarn Unevenness (U %)
[0072] Using USTER TESTER IV, manufactured by Zellweger Uster AG, a
fiber sample was examined under the conditions of: sample length,
500 m; test yarn speed V, 100 m/min; twister, type S at 30,000/min;
and 1/2 Inert.
E. Content of Crystals, Content of Rigid Amorphous Components
[0073] Xc was determined by calculating the difference
(.DELTA.Hm-.DELTA.Hc) between the quantity of heat of fusion and
the quantity of heat of cold crystallization that were determined
by DSC, and calculating the Xc using equation (1). In equation (1),
.DELTA.Hm0 is the quantity of heat of fusion of the crystalline
polyamide, and the value thereof is 229.76 J/g.
[0074] The content of rigid amorphous components (Xra) was
calculated from the content of crystals (Xc) and the content of
movable amorphous components (Xma) using equation (2). The content
of movable amorphous components (Xma) was calculated from a
difference in specific heat (.DELTA.Cp) between before and after a
glass transition observed on a temperature-heat flux reversible
curve determined by temperature-modulated DSC (TMDSC). As the
.DELTA.Cp was used a specific-heat gap between before and after the
glass transition, the specific-heat gap being calculated from an
extrapolated tangent which touches the temperature-heat flux
reversible curve at around the glass transition. The content of
movable amorphous components (Xma) was calculated using equation
(3). In equation (3), .DELTA.Cp0 is a difference in specific heat
between before and after the Tg of the amorphous polyamide, and the
value thereof is 0.4745 J/g.
[0075] The content of rigid amorphous components was calculated
from average values obtained from two measurements made by
temperature-modulated DSC and DSC.
Content of crystals: Xc
(%)=(.DELTA.Hm-.DELTA.Hc)/.DELTA.Hm0.times.100 (1)
Content of rigid amorphous components: Xra (%)=100-(Xc+Xma) (2)
Content of movable amorphous components: Xma
(%)=.DELTA.Cp/.DELTA.Cp0.times.100 (3)
[0076] The ordinary DSC and temperature-modulated DSC were
conducted under the following measuring conditions.
(a) Ordinary DSC
[0077] Using Q1000, manufactured by TA Instruments, data processing
was conducted with Universal Analysis 2000. A measurement was made
in a nitrogen stream (50 mL/min) under the conditions of a
temperature range of 0-300.degree. C., a heating rate of 10.degree.
C./min, and a sample weight of about 5 mg (the calorimetric data
were normalized with respect to the weight of the sample that had
undergone the examination).
[0078] Details of the above-described DSC are described in the
following:
Document 1
Wunderlich B., Thermal Analysis of Polymeric Materials, Appendix 1
(The ATHAS Data Bank), Springer (2005)
(b) Temperature-Modulated DSC
[0079] Using Q1000, manufactured by TA Instruments, data processing
was conducted with Universal Analysis 2000. A measurement was made
in a nitrogen stream (50 mL/min) under the conditions of a
temperature range of 0-200.degree. C., a heating rate of 2.degree.
C./min, and a sample weight of about 5 mg (the calorimetric data
were normalized with respect to the weight of the sample that had
undergone the examination).
[0080] This technique is a method in which the temperature is
evenly elevated to examine the sample while repeatedly conducting
heating and cooling with certain period and amplitude. All the DSC
signals (total heat flow) can be separated into ones attributable
to reversible components (reversing heat flow) such as glass
transition and ones attributable to irreversible components
(nonreversing heat flow) such as enthalpy relaxation, curing
reaction, solvent elimination and the like. However, a crystal
shows a melting peak for both reversible components and
irreversible components.
[0081] Details of the temperature-modulated DSC are described in
Document 1 Wunderlich above.
F. Evaluation of Lace
(a) Softness
[0082] A lace product was evaluated for relative softness by
inspectors (five persons) rich in experiences in evaluating
feeling. The grades respectively evaluated by the inspectors were
averaged, and the average was rounded off to the nearest whole
number. Grades 5, 4, 3, and 1-2 on average were indicated by S, A,
B, and C, respectively.
[0083] 5: highly excellent
[0084] 4: slightly excellent
[0085] 3: fair
[0086] 2: slightly poor
[0087] 1: poor
[0088] S and A were regarded as acceptable in terms of
softness.
(b) Durability
[0089] Bursting strength was evaluated in the following manner.
Arbitrarily selected three portions were examined for bursting
strength by the bursting strength test method according to JIS
L1096-2010, Mullen type method (method A), and an average value of
the measured values was evaluated in the following four grades.
[0090] S: 130 kPa or higher
[0091] A: 100 kPa or higher but less than 130 kPa
[0092] B: 90 kPa or higher but less than 100 kPa
[0093] C: less than 90 kPa
[0094] S and A were regarded as acceptable in terms of
durability.
(c) Appearance Quality
[0095] A lace product was evaluated for relative degree of uneven
dyeing by inspectors (five persons). The grades respectively
evaluated by the inspectors were averaged, and the average was
rounded off to the nearest whole number. Grades 5, 4, 3, and 1-2 on
average were indicated by S, A, B, and C, respectively.
[0096] 5: highly excellent
[0097] 4: slightly excellent
[0098] 3: fair
[0099] 2: slightly poor
[0100] 1: poor
[0101] S and A were regarded as acceptable in terms of appearance
quality.
(d) Process Passage Capability
[0102] Suitability for knitting: The number of yarn breakages that
occurred during knitting per roll of lace fabric (80 m) was shown
according to the following criteria.
[0103] S: 0 or more and less than 5 yarn breakages
[0104] A: 5 or more and less than 10 yarn breakages
[0105] B: 10 or more and less than 20 yarn breakages
[0106] C: 20 or more and less than 30 yarn breakages
[0107] S and A were regarded as acceptable in terms of process
passage capability.
G. Evaluation of Stocking
(a) Softness
[0108] A stocking product in the state of being worn by a human leg
form was evaluated for relative softness of the leg portion by
inspectors (five persons) rich in experiences in evaluating
feeling. The grades respectively evaluated by the inspectors were
averaged, and the average was rounded off to the nearest whole
number. Grades 5, 4, 3, and 1-2 on average were indicated by S, A,
B, and C, respectively.
[0109] 5: highly excellent
[0110] 4: slightly excellent
[0111] 3: fair
[0112] 2: slightly poor
[0113] 1: poor
[0114] S and A were regarded as acceptable in terms of
softness.
(b) Durability
[0115] A stocking product was put, with the right side out, on a
human leg form so that the garter part lay in a position 60 cm
apart from the heel toward the thigh. On the back of the thigh of
the leg form, a circular mark according to a measuring frame was
put so that the center of the mark lay in a position 52.5 cm apart
from the heel toward the thigh. In fixing the product to the
measuring frame, the product was fixed so that the circular mark
thus put was positioned properly with respect to the frame. Thus,
the product was examined for bursting strength in the same state as
the state of being worn. The bursting strength was used as an index
to durability.
[0116] Bursting strength was evaluated in the following manner.
Arbitrarily selected three portions were examined for bursting
strength by the bursting strength test method according to JIS
L1096-2010, Mullen type method (method A), and an average value of
the measured values was evaluated in the following four grades.
[0117] S: 117.7 kPa or higher
[0118] A: 98.1 kPa or higher but less than 117.7 kPa
[0119] B: 88.3 kPa or higher but less than 98.1 kPa
[0120] C: less than 88.3 kPa
[0121] S and A were regarded as acceptable in terms of
durability.
(c) Appearance Quality
[0122] A stocking product was evaluated for relative degree of
uneven dyeing by inspectors (five persons). The grades respectively
evaluated by the inspectors were averaged, and the average was
rounded off to the nearest whole number. Grades 5, 4, 3, and 1-2 on
average were indicated by S, A, B, and C, respectively.
[0123] 5: highly excellent
[0124] 4: slightly excellent
[0125] 3: fair
[0126] 2: slightly poor
[0127] 1: poor
[0128] S and A were regarded as acceptable in terms of appearance
quality.
(d) Process Passage Capability
[0129] A hosiery machine was continuously operated for 1 hour at a
rotational speed of 400 rpm to knit stockings, and the number of
machine stops due to yarn breakages during the knitting was
evaluated according to the following criteria.
[0130] S: less than 2 yarn breakages
[0131] A: 2 or more and less than 4 yarn breakages
[0132] B: 4 or more and less than 6 yarn breakages
[0133] C: 6 or more yarn breakages
[0134] S and A were regarded as acceptable in terms of process
passage capability.
Example 1
Production of Polyamide Multifilament
[0135] Nylon-6 chips having a sulfuric acid relative viscosity (Ty)
of 3.3 and a melting point of 225.degree. C., as a polyamide, were
dried in an ordinary method to result in a moisture content of
0.03% by mass or less. The nylon-6 chips thus obtained were melted
at a spinning temperature (melting temperature) of 290.degree. C.
and ejected from a spinneret. The spinneret used had forty-two
holes, which were round and had a diameter of 0.25 mm, and was used
to produce six yarns per spinneret.
[0136] The spinning was conducted using a spinning machine (direct
spinning drawing machine) having the configuration shown in FIG. 1.
As the heating cylinder was used a two-layer heating cylinder
having a heating cylinder length L of 50 mm and single-layer
lengths L1 and L2 of 25 mm each. Temperatures were set so that the
atmosphere in the upper layer of the heating cylinder had a
temperature of 300.degree. C. and the atmosphere in the lower layer
of the heating cylinder had a temperature of 150.degree. C.
[0137] The filaments ejected from the spinneret were gradually
cooled at ambient temperatures of 150-300.degree. C. in the
two-layer heating cylinder and passed through an annular cooler
having a cooling initiation distance LS of 169 mm and supplying
18.degree. C. cool air. Thus, the filaments were cooled to room
temperature and solidified. Thereafter, the filaments were
collected, while being oiled at an oiling position Lg of 1,300 mm,
in terms of distance from the spinneret surface, thereby forming a
multifilament. The multifilament was entangled with a fluid
entangling nozzle device. The multifilament was then passed through
the take-up roller, which had a speed (spinning speed) of 1,500
m/min, and the drawing roller, which had a heat-setting length of
600 mm and had been heated to 155.degree. C., drawn thereby at a
draw ratio of 2.8, and wound up. Thus, a nylon-6 multifilament
having a fineness of 22.0 dtex and including seven filaments was
obtained.
[0138] The nylon-6 multifilament obtained was evaluated, and the
results thereof are shown in Table 1.
Production of Knitted Lace
[0139] Next, the multifilament was warped and set as a back yarn
for a 28-G raschel lace ground yarn to have a runner length of 21.0
cm and also as a front yarn for the ground yarn to have a runner
length of 100.0 cm, and then knitted together with patterning yarns
of 235-330 dtex. The resultant fabric was subjected to scouring,
dyeing, and finish setting, thereby obtaining a knitted lace for
innerwear use. The lace product obtained was evaluated, and the
results thereof are shown in Table 1.
Example 2
[0140] A nylon-6 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that the ejected filaments were
gradually cooled at ambient temperatures of 100-300.degree. C. in
the heating cylinder by setting the temperature of the atmosphere
in the upper layer of the heating cylinder at 300.degree. C. and
the temperature of the atmosphere in the lower layer of the heating
cylinder at 100.degree. C. and that the speed of the take-up roller
was changed to 1,700 m/min and the draw ratio was changed to 2.7.
The results of the evaluation are shown in Table 1.
Example 3
[0141] A nylon-6 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that the ejected filaments were
gradually cooled at ambient temperatures of 200-300.degree. C. in
the heating cylinder by setting the temperature of the atmosphere
in the upper layer of the heating cylinder at 300.degree. C. and
the temperature of the atmosphere in the lower layer of the heating
cylinder at 200.degree. C. and that the draw ratio was changed to
3.0. The results of the evaluation are shown in Table 1.
Example 4
[0142] A nylon-66 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that nylon-66 chips having a
sulfuric acid relative viscosity (qr) of 3.2 and a melting point of
265.degree. C. were used as a polyamide. The results of the
evaluation are shown in Table 1.
Comparative Example 1
[0143] A nylon-6 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that a single-layer heating
cylinder having a length L of 50 mm was used and the temperature of
the atmosphere therein was set at 300.degree. C. and that the draw
ratio was changed to 3.2. The results of the evaluation are shown
in Table 1.
[0144] Because of the use of the single-layer heating cylinder, the
temperature of the atmosphere in the heating cylinder was constant
and the thermal convection within the heating cylinder was
disordered, resulting in an impaired U %. In addition, since the
set temperature of the atmosphere in the heating cylinder was
300.degree. C., which was close to the spinning temperature, the
orientation relaxation due to gradual cooling from the spinneret
surface to the upper surface of the cooler was insufficient,
resulting in too high a 15% strength. Because of this, the knitted
lace was poor in process passage capability, appearance quality,
and softness.
Comparative Example 2
[0145] A nylon-6 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that the ejected filaments were
gradually cooled at ambient temperatures of 100-200.degree. C. in
the heating cylinder by setting the temperature of the atmosphere
in the upper layer of the heating cylinder at 200.degree. C. and
the temperature of the atmosphere in the lower layer of the heating
cylinder at 100.degree. C. and that the speed of the take-up roller
was changed to 1,700 m/min. The results of the evaluation are shown
in Table 1.
[0146] Since the set temperatures of the atmosphere in the heating
cylinder were 100-200.degree. C., which were lower by at least
90.degree. C. than the spinning temperature, the orientation
relaxation due to gradual cooling from the spinneret surface to the
upper surface of the cooler was insufficient, resulting in too
small a strength-elongation product and too low a 15% strength.
Because of this, the knitted lace had poor durability.
Comparative Example 3
[0147] A nylon-6 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that no heating cylinder was
disposed. The results of the evaluation are shown in Table 1.
[0148] Since no heating cylinder had been disposed, the orientation
relaxation due to gradual cooling from the spinneret surface to the
upper surface of the cooler was insufficient, resulting in too
small a strength-elongation product and too low a 15% strength.
Because of this, the knitted lace had poor durability.
TABLE-US-00001 TABLE 1 Compar- Compar- Compar- ative ative ative
Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 1 ple 2 ple 3 ple 4
ple 1 ple 2 ple 3 Polymer polyamide N6 N6 N6 N66 N6 N6 N6 Spinning
Heating cylinder in- in- in- in- in- in- not in- conditions cluded
cluded cluded cluded cluded cluded cluded Temperature of atmosphere
300 300 300 300 300 200 -- in upper layer of heating cylinder
(.degree. C.) Temperature of atmosphere -- -- -- -- 300 -- -- in
middle layer of heating cylinder (.degree. C.) Temperature of
atmosphere 150 100 200 150 300 100 -- in lower layer of heating
cylinder (.degree. C.) Spinning speed (m/min) 1,500 1,700 1,500
1,500 1,500 1,700 1,500 Draw ratio 2.8 2.7 3.0 2.8 3.2 2.8 2.8 Yarn
Total fineness (dtex) 22 22 22 22 22 22 22 properties
Single-filament fineness 3.0 3.0 3.0 3.0 3.0 3.0 3.0 (dtex)
Elongation (%) 42.0 43.0 38.3 41 36.0 39.0 36.0 Strength (cN/dtex)
7.4 7.0 7.6 7.3 7.9 6.7 6.7 Strength-elongation 10.5 10.0 10.5 10.3
10.7 9.3 9.1 product (cN/dtex) U % 0.60 0.40 1.20 0.60 1.60 0.35
0.60 15% strength (cN/dtex) 4.5 4.2 5.0 4.5 6.1 3.4 3.4 Content of
crystals (%) 29 25 30 28 33 19 23 Content of rigid amorphous 55 53
55 53 58 45 50 components (%) Sum of content of crystals 84 78 86
81 91 64 73 and content of rigid amorphous components (%)
Evaluation Softness S S S S C S S of lace Durability S A S S S C C
Appearance quality S S A S C S S Process passage capability S S S S
C S S
Example 5
[0149] A nylon-6 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that the oiling position Lg was
changed to 800 mm and the draw ratio was changed to 3.0. The
results of the evaluation are shown in Table 2.
Example 6
[0150] A nylon-6 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that the oiling position Lg was
changed to 1,500 mm and the draw ratio was changed to 2.7. The
results of the evaluation are shown in Table 2.
Comparative Example 4
[0151] A nylon-6 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that the oiling position Lg was
changed to 600 mm and the draw ratio was changed to 3.2. The
results of the evaluation are shown in Table 2.
[0152] Since the filaments in the state of having a temperature
which was still above room temperature were oiled, the
multifilament had an impaired U %. In addition, the bending of the
filaments in the zone ranging from the spinneret surface to the
oiling guide was large and, hence, the filaments were affected by
fretting on the oiling guide, resulting in too small a
strength-elongation product and too low a 15% strength. Because of
this, the knitted lace was poor in process passage capability,
durability, and appearance quality.
Comparative Example 5
[0153] A nylon-6 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that the oiling position Lg was
changed to 3,000 mm and the draw ratio was changed to 2.7. The
results of the evaluation are shown in Table 2.
[0154] The descending air flow considerably affected the filament
oscillation, resulting in an impaired U %. In addition, the
accompanying flow heightened the spinning tension and hence
enhanced the spinning orientation, resulting in too low a 15%
strength and too small a strength-elongation product. Because of
this, the knitted lace was poor in appearance quality and
durability.
Example 7
[0155] A nylon-6 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that the speed of the take-up
roller (spinning speed) was changed to 1,000 m/min and the draw
ratio was changed to 3.8. The results of the evaluation are shown
in Table 2.
Example 8
[0156] A nylon-6 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that the speed of the take-up
roller (spinning speed) was changed to 2,000 m/min and the draw
ratio was changed to 2.3. The results of the evaluation are shown
in Table 2.
Comparative Example 6
[0157] A nylon-6 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that the speed of the take-up
roller (spinning speed) was changed to 800 m/min and the draw ratio
was changed to 4.5. The results of the evaluation are shown in
Table 2.
[0158] Since the spinning speed was too low, the spinning tension
was reduced to enhance the filament oscillation, resulting in an
impaired U %. In addition, the gradually cooling effect of the
heating cylinder was heightened to cause the strain relaxation of
the polyamide molecular chains to proceed excessively, resulting in
too high a 15% strength. Because of this, the knitted lace was poor
in process passage capability, appearance quality, and
softness.
Comparative Example 7
[0159] A nylon-6 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that the speed of the take-up
roller (spinning speed) was changed to 2,500 m/min and the draw
ratio was changed to 1.9. The results of the evaluation are shown
in Table 2.
[0160] Since the spinning speed was too high, the strain rate was
heightened to increase unevenness in the strain rate, resulting in
enhanced draft draw unevenness and an impaired U %. In addition,
the gradually cooling effect of the heating cylinder was lowered to
render the strain relaxation of the polyamide molecular chains
insufficient, resulting in too low a 15% strength and too small a
strength-elongation product. Because of this, the knitted lace was
poor in appearance quality and durability.
Example 9
[0161] A nylon-6 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that a drawing roller having a
different diameter was used to regulate the heat-setting length to
1,200 mm. The results of the evaluation are shown in Table 2.
Comparative Example 8
[0162] A nylon-6 multifilament having a fineness of 22 dtex and
including seven filaments and a knitted lace were obtained in the
same manner as in Example 1, except that a drawing roller having a
different diameter was used to regulate the heat-setting length to
1,800 mm. The results of the evaluation are shown in Table 2.
[0163] The thermal crystallization of the fibers proceeded
excessively, resulting in too high a 15% strength. Because of this,
the knitted lace was poor in process passage capability and
softness.
TABLE-US-00002 TABLE 2 Compar- Compar- Compar- Compar- Compar-
ative ative ative ative ative Exam- Exam- Exam- Exam- Exam- Exam-
Exam- Exam- Exam- Exam- ple 5 ple 6 ple 7 ple 8 ple 9 ple 4 ple 5
ple 6 ple 7 ple 8 Polymer polyamide N6 N6 N6 N6 N6 N6 N6 N6 N6 N6
Spinning Heating cylinder in- in- in- in- in- in- in- in- in- in-
conditions cluded cluded cluded cluded cluded cluded cluded cluded
cluded cluded Lg: oiling 800 1,500 1,300 1,300 1,300 600 3,000
1,300 1,300 1,300 position (mm) Spinning speed 1,500 1,500 1,000
2,000 1,500 1,500 1,500 800 2,500 1,500 (m/min) Heat-setting 600
600 600 600 1,200 600 600 600 600 1,800 length (mm) Draw ratio 3.0
2.7 3.8 2.3 2.8 3.2 2.7 4.5 1.9 2.8 Yarn Total fineness 22 22 22 22
22 22 22 22 22 22 properties (dtex) Single-filament 3.0 3.0 3.0 3.0
3.0 3.0 3.0 3.0 3.0 3.0 fineness (dtex) Elongation (%) 41 44 41 42
32 39 42 39 43 27 Strength 7.3 7.0 7.3 7.2 7.8 6.9 6.6 7.5 6.5 8.2
(cN/dtex) Strength-elonga- 10.3 10.1 10.3 10.2 10.3 9.6 9.4 10.4
9.3 10.4 tion product (cN/dtex) U % 0.80 1.10 0.80 0.60 0.60 1.30
1.80 1.40 1.50 0.60 15% strength 5.6 4.1 5.6 4.5 5.5 3.9 3.5 6.1
3.6 6.4 (cN/dtex) Content of 32 27 32 29 29 25 23 30 25 30 crystals
(%) Content of 56 53 56 55 55 50 50 55 50 61 rigid amorphous
components (%) Sum of content 88 80 88 84 84 75 73 85 75 91 of
crystals and content of rigid amorphous com- ponents (%) Evaluation
Softness A S A S S S S C S C of lace Durability S A S S S C C S C S
Appearance S A S S S C C C C S quality Process passage A S A S S C
S C S C capability
Example 10
Production of Polyamide Multifilament
[0164] Nylon-6 chips having a sulfuric acid relative viscosity
(.eta.r) of 3.3 and a melting point of 225.degree. C., as a
polyamide, were dried in an ordinary method to result in a moisture
content of 0.03% by mass or less. The nylon-6 chips thus obtained
were melted at a spinning temperature (melting temperature) of
290.degree. C. and ejected from a spinneret. The spinneret used had
thirty holes, which were round and had a diameter of 0.20 mm, and
was used to produce six yarns per spinneret.
[0165] The spinning was conducted using a spinning machine having
the configuration shown in FIG. 1. As the heating cylinder was used
a two-layer heating cylinder having a heating cylinder length L of
50 mm and single-layer lengths L1 and L2 of 25 mm each.
Temperatures were set so that the atmosphere in the upper layer of
the heating cylinder had a temperature of 300.degree. C. and the
atmosphere in the lower layer of the heating cylinder had a
temperature of 150.degree. C.
[0166] The filaments ejected from the spinneret were gradually
cooled at ambient temperatures of 150-300.degree. C. in the
two-layer heating cylinder and passed through an annular cooler
having a cooling initiation distance LS of 169 mm and supplying
18.degree. C. cool air. Thus, the filaments were cooled to room
temperature and solidified. Thereafter, the filaments were
collected, while being oiled at an oiling position Lg of 1,300 mm,
in terms of distance from the spinneret surface, thereby forming a
multifilament. The multifilament was entangled with a fluid
entangling nozzle device. The multifilament was then passed through
the take-up roller, which had a speed (spinning speed) of 1,500
m/min, and the drawing roller, which had a heat-setting length of
600 mm and had been heated to 155.degree. C., drawn thereby at a
draw ratio of 2.6, and wound up. Thus, a nylon-6 multifilament
having a fineness of 8.0 dtex and including five filaments was
obtained.
[0167] The nylon-6 multifilament obtained was evaluated, and the
results thereof are shown in Table 3.
Production of Stocking
[0168] Next, the multifilament was used as a covering yarn for a
covered yarn, and an elastic polyurethane yarn having a fineness of
22 dtex was used as a core yarn. The draft ratio was set at 3.0,
and the core yarn was single-covered with the covering yarn, with
the number of twists being 2,400 t/m (S and Z directions). Thus, a
single-covered elastic yarn (SCY) was produced.
[0169] The SCY obtained was used in knitting with a hosiery
machine. The resultant knitted fabric was subjected to scouring,
dyeing, and 120.degree. C. 30-second final setting to obtain a
pantyhose product. The leg portion of the pantyhose product was
evaluated, and the results thereof are shown in Table 3.
Comparative Example 9
[0170] A nylon-6 multifilament having a fineness of 8 dtex and
including five filaments and a pantyhose product were obtained in
the same manner as in Example 10, except that no heating cylinder
was disposed. The results of the evaluation are shown in Table
3.
[0171] Since no heating cylinder had been disposed, the orientation
relaxation due to gradual cooling from the spinneret surface to the
upper surface of the cooler was insufficient, resulting in too
small a strength-elongation product and too low a 15% strength.
Because of this, the pantyhose product had poor durability.
Comparative Example 10
[0172] A nylon-6 multifilament having a fineness of 8 dtex and
including five filaments and a pantyhose product were obtained in
the same manner as in Example 10, except that no heating cylinder
was disposed and that the speed of the take-up roller (spinning
speed) was changed to 2,500 m/min and the draw ratio was changed to
1.5. The results of the evaluation are shown in Table 3.
[0173] Since the spinning speed was too high, the strain rate was
heightened to increase unevenness in strain rate, resulting in
enhanced draft draw unevenness and an impaired U %. In addition,
since no heating cylinder had been disposed, the strain relaxation
due to gradual cooling from the spinneret surface to the upper
surface of the cooler was insufficient, resulting in too low a 15%
strength and too small a strength-elongation product. Because of
this, the pantyhose product was poor in appearance quality and
durability.
Comparative Example 11
[0174] A nylon-6 multifilament having a fineness of 8 dtex and
including five filaments and a pantyhose product were obtained in
the same manner as in Example 10, except that a single-layer
heating cylinder having a length L of 50 mm was used and the
temperature of the atmosphere therein was set at 300.degree. C. and
that the oiling position Lg was changed to 3,000 mm, the speed of
the take-up roller (spinning speed) was changed to 600 m/min, and
the draw ratio was changed to 4.5. The results of the evaluation
are shown in Table 3.
[0175] Because of the use of the single-layer heating cylinder, the
temperature of the atmosphere in the heating cylinder was constant
and the thermal convection within the heating cylinder was
disordered. Furthermore, due to the low oiling position (long
distance from the spinneret to the oiling) and the low spinning
rate, the filament oscillation was enhanced, resulting in an
impaired U %. Moreover, the low-spinning speed heightened the
gradually cooling effect of the heating cylinder to cause the
strain relaxation of the polyamide molecular chains to proceed
excessively, and the increased heat-setting length caused the
crystallization of the fibers to proceed excessively, resulting in
too high a 15% strength. Because of this, the pantyhose product was
poor in process passage capability, appearance quality, and
softness.
TABLE-US-00003 TABLE 3 Comparative Comparative Comparative Example
10 Example 9 Example 10 Example 11 Polymer polyamide N6 N6 N6 N6
Spinning Heating cylinder included not included not included
included conditions Temperature of atmosphere 300 -- -- 300 in
upper layer of heating cylinder (.degree. C.) Temperature of
atmosphere -- -- -- 300 in middle layer of heating cylinder
(.degree. C.) Temperature of atmosphere 150 -- -- 300 in lower
layer of heating cylinder (.degree. C.) Lg: oiling position (mm)
1,300 1,300 1,300 3,000 Spinning speed (m/min) 1,500 1,500 2,500
600 Heat-setting length (mm) 600 600 600 2,400 Draw ratio 2.6 2.6
1.5 4.5 Yarn Total fineness (dtex) 8 8 8 8 properties
Single-filament fineness 1.6 1.6 1.6 1.6 (dtex) Elongation (%) 44
40 38 28 Strength (cN/dtex) 7.3 6.4 6.1 8.3 Strength-elongation
10.5 9.0 8.4 10.6 product (cN/dtex) U % 0.80 0.80 1.50 1.30 15%
strength (cN/dtex) 4.4 3.8 3.4 6.5 Content of crystals (%) 29 23 20
32 Content of rigid 55 50 40 63 amorphous components (%) Sum of
content of crystals 84 73 60 95 and content of rigid amorphous
components (%) Evaluation Softness S S S C of pantyhose Durability
S C C S Appearance quality S S C B Process passage capability S S S
C
* * * * *