U.S. patent application number 10/312260 was filed with the patent office on 2003-07-17 for polyester based thermally adhesive composite short fiber.
Invention is credited to Goda, Hironori, Tashiro, Mikio.
Application Number | 20030134115 10/312260 |
Document ID | / |
Family ID | 18958280 |
Filed Date | 2003-07-17 |
United States Patent
Application |
20030134115 |
Kind Code |
A1 |
Goda, Hironori ; et
al. |
July 17, 2003 |
Polyester based thermally adhesive composite short fiber
Abstract
Polyester-based heat-bonding conjugate staple fibers capable of
giving a high grade fiber structure which has good dimensional
stability and is hardly deformed, even when used under a high
temperature atmosphere, comprises an amorphous polyester having a
glass transition point of 50 to 100.degree. C. and not having a
crystal-melting point as a heat-bonding component and a
polyalkylene terephthalate having a melting point of not less than
220.degree. C. as a fiber-forming component, have characteristics
comprising the number of crimps of 3 to 40 crimps/25 mm, a crimp
percent of 3 to 40% and a web area shrinkage percent of not more
than 20%. Herein, the web area shrinkage percent (%) is represented
by the expression: (A.sub.0-A.sub.1)/A.sub.0.times.100, wherein a
card web nonwoven fabric comprising 100% of the heat-bonding
conjugate staple fibers and having an area of A.sub.0 and a basis
weight of 30 g/m.sup.2 is left in a hot air dryer maintained at
150.degree. C. for two minutes, and the area of the left nonwoven
fabric is A.sub.1.
Inventors: |
Goda, Hironori; (Ehime,
JP) ; Tashiro, Mikio; (Osaka, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
WASHINGTON
DC
20037
US
|
Family ID: |
18958280 |
Appl. No.: |
10/312260 |
Filed: |
December 24, 2002 |
PCT Filed: |
March 20, 2002 |
PCT NO: |
PCT/JP02/02694 |
Current U.S.
Class: |
428/361 ;
428/362; 428/373 |
Current CPC
Class: |
Y10T 428/2907 20150115;
D06M 15/507 20130101; D01F 8/14 20130101; D06M 15/53 20130101; Y10T
428/2909 20150115; Y10T 428/2929 20150115 |
Class at
Publication: |
428/361 ;
428/362; 428/373 |
International
Class: |
D02G 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 4, 2001 |
JP |
2001-105623 |
Claims
1. Polyester-based heat-bonding conjugate staple fibers comprising
an amorphous polyester having a glass transition point of 50 to
100.degree. C. and not having a crystal-melting point as a
heat-bonding component and a polyalkylene terephthalate having a
melting point of not less than 220.degree. C. as a fiber-forming
component, characterized by having the number of crimps of 3 to 40
crimps/25 mm, a crimp percent of 3 to 40%, and a web area shrinkage
percent of not more than 20% defined as described below. <Web
Area Shrinkage Percentage>A card web nonwoven fabric comprising
100% of the heat-bonding conjugate staple fibers and having an area
of A.sub.0 and a basis weight of 30 g/m.sup.2 is left in a hot air
dryer maintained at 150.degree. C. for two minutes, and then the
area A.sub.1 of the nonwoven fabric is measured. The web area
shrinkage percentage is determined by the following expression. Web
area shrinkage percentage
(%)=(A.sub.0-A.sub.1)/A.sub.0.times.100
2. The polyester-based heat-bonding conjugate staple fibers
according to claim 1, wherein a polyether polyester block copolymer
is applied to the surfaces of the fibers in an amount of not less
than 0.03 percent by weight on the basis of the weight of the
fibers.
3. The polyester-based heat-bonding conjugate staple fibers
according to claim 1 or 2, wherein the heat-bonding component is an
amorphous copolyester comprising isophthalic acid component,
terephthalic acid component, ethylene glycol component, and
diethylene glycol component.
4. The polyester-based heat-bonding conjugate staple fibers
according to claim 1 or 2, wherein the fiber-forming component is
polyethylene terephthalate.
5. A method for producing polyester-based heat-bonding conjugate
staple fibers, characterized by melting and conjugationally
extruding an amorphous polyester having a glass transition point of
50 to 100.degree. C. and not having a crystal-melting point and a
polyalkylene terephthalate having a melting point of not less than
220.degree. C., cooling and solidifying the conjugationally
extruded fibers, taking off the fibers at a rate of not more than
1,500 m/minute to form the undrawn conjugate fibers, applying a
polyether polyester block copolymer to the undrawn conjugate fibers
in an amount of not less than 0.03 percent by weight on the basis
of the weight of the fibers, drawing the undrawn conjugate fibers
in a draw ratio of 0.72 to 1.25 times the cold maximum draw ratio
at a temperature of T.sub.1 to (T.sub.2+30.degree. C.), and further
crimping the drawn fibers so as to give the number of crimps of 3
to 40 crimps/25 mm and a crimp percent of 3 to 40%. Herein, T.sub.1
is either higher temperature among the glass transition point of
the amorphous polyester and the glass transition point of the
polyalkylene terephthalate, and T.sub.2 is the glass transition
point of the amorphous polyester.
6. The method for producing the polyester-based heat-bonding
conjugate staple fibers according to claim 5, wherein the drawing
is a two step drawing comprising drawing in a draw ratio of 0.70 to
1.00 time the cold maximum draw ratio at a temperature of T.sub.1
to (T.sub.1+10.degree. C.) and further in a draw ratio of 1.03 to
1.25 at a temperature of (T.sub.1+10.degree. C.) to
(T.sub.2+30.degree. C.).
7. The method for producing the polyester-based heat-bonding
conjugate staple fibers according to claim 5 or 6, wherein a
heating medium used for the drawing is hot water.
8. The method for producing the polyester-based heat-bonding
conjugate staple fibers according to claim 5 or 6, wherein the
polyether polyester block copolymer is a block copolymer comprising
terephthalic acid component and isophthalic acid component and/or
an alkali metal salt sulfoisophthalic acid component in a molar
ratio of 40:60 to 100:0 as the acid component and ethylene glycol
as the glycol component and copolymerized with 20 to 95 percent by
weight of a polyalkylene glycol having a number-average molecular
weight of 600 to 10,000.
Description
TECHNICAL FIELD
[0001] The present invention relates to a polyester-based
heat-bonding conjugate staple fibers suitable for bonding a fiber
structure such as nonwoven fabric or wadding and to a method for
producing the same, in more detail to heat-bonding conjugate staple
fibers capable of giving a fiber structure which can thermally be
bonded at relatively low temperature and has good dimensional
stability and to a method for producing the same.
BACKGROUND ART
[0002] Heretofore, as polyester-based heat-bonding conjugate staple
fibers, conjugate fibers comprising a polyalkylene terephthalate
such as polyethylene terephthalate as a core component and an
amorphous polyester comprising isophthalic acid component,
terephthalic acid component, or the like as an acid constituent and
not having a crystal-melting point as a sheath component have
widely been used, because of being capable of being bonded at
relatively low temperature of 120 to 150.degree. C. to form a fiber
structure without needing a thermal treatment at high
temperature.
[0003] However, the polyester-based heat-bonding conjugate fibers
can form the fiber structure at the relatively low temperature, but
has a problem that the obtained fiber structure has insufficient
dimensional stability and is therefore largely deformed, when used
under a high temperature atmosphere.
[0004] The present inventors have tried drawing treatments and
thermal treatments at high temperature to solve the problem and
improve the dimensional stability of the heat-bonding fibers
themselves, but it has be found that the fibers are cohered each
other at higher temperature than the glass transition point of the
amorphous polyester to make the production of yarns difficult.
[0005] From such the reason, it is the fact that heat-bonding
conjugate fibers containing an amorphous polyester, especially an
amorphous polyester having a glass transition point of 50 to
100.degree. C., as a heat-bonding component and having excellent
dimensional stability have still not been proposed.
DISCLOSURE OF THE INVENTION
[0006] The object of the present invention is to provide
polyester-based heat-bonding conjugate staple fibers capable of
giving a high grade fiber structure, such as nonwoven fabric or
wadding, which can thermally be bonded at relatively low
temperature without needing a thermal treatment at high
temperature, has good dimensional stability and is hardly deformed,
even when used in a high temperature atmosphere, and to provide a
method for producing the same.
[0007] The present inventors have found that it is effective for
the achievement of the above-described object to use an amorphous
polyester having a glass transition point of 50 to 100.degree. C.
as a heat-bonding component and a polyalkylene terephthalate as a
fiber-forming component and select heat-drawing conditions for the
fibers, and has thus completed the present invention.
[0008] Namely, the polyester-based heat-bonding conjugate staple
fibers of the present invention, enabling the achievement of the
above-described object is heat-bonding conjugate staple fibers
comprising an amorphous polyester having glass transition point of
50 to 100.degree. C. and not having a crystal-melting point as a
heat-bonding component and a polyalkylene terephthalate having a
melting point of not less than 220.degree. C. as a fiber-forming
component, characterized by having the number of crimps of 3 to 40
crimps/25 mm, a crimp percent of 3 to 40%, and a web area shrinkage
percent of not more than 20% defined as described below.
[0009] <Web Area Shrinkage Percentage>
[0010] A card web nonwoven fabric comprising 100% of the
heat-bonding conjugate staple fibers and having an area of A.sub.0
and a basis weight of 30 g/m.sup.2 is left in a hot air dryer
maintained at 150.degree. C. for two minutes, and then the area
A.sub.1 of the nonwoven fabric is measured. The web area shrinkage
percentage is determined by the following expression.
Web area shrinkage percentage
(%)=(A.sub.0-A.sub.1)/A.sub.0.times.100
[0011] In addition, a method for producing polyester-based
heat-bonding conjugate staple fibers as the other object of the
present invention, are characterized by melting and conjugationally
extruding an amorphous polyester having a glass transition point of
50 to 100.degree. C. and not having a crystal-melting point and a
polyalkylene terephthalate having a melting point of not less than
220.degree. C., cooling and solidifying the conjugationally
extruded fibers, taking off the fibers at a rate of not more than
1,500 m/minute to form the undrawn conjugate fibers, imparting a
polyether polyester block copolymer to the undrawn conjugate fibers
in an amount of not less than 0.03 percent by weight on the basis
of the weight of the fibers, drawing the undrawn conjugate fibers
in a draw ratio of 0.72 to 1.25 times the cold maximum draw ratio
at a temperature of T.sub.1 to (T.sub.2+30.degree. C.), and further
crimping the drawn fibers so as to give the number of crimps of 3
to 40 crimps/25 mm and a crimp percent of 3 to 40%. Herein, T.sub.1
is either higher temperature among the glass transition point of
the amorphous polyester and the glass transition point of the
polyalkylene terephthalate, and T.sub.2 is the glass transition
point of the amorphous polyester.
BEST MODE FOR CARRYING OUT THE INVENTION
[0012] The fiber-forming component of the polyester-based
heat-bonding conjugate staple fibers of the present invention is a
polyalkylene terephthalate having a melting point of not less than
220.degree. C. When the melting point of the polyester as the
fiber-forming component is less than 220.degree. C., it is not only
difficult to stably produce the conjugate fibers, but the stability
of the conjugate fibers is also deteriorated on a heat-bonding
treatment. The preferable concrete examples of the polyalkylene
terephthalate are polyethylene terephthalate and polybutylene
terephthalate, and may contain one or more copolymerization
components and additives such as a delustering agent, a coloring
matter, and a lubricant in small amounts within ranges not
deteriorating the characteristics, respectively. Especially, the
polyethylene terephthalate is more preferable because of being
inexpensive and generally used.
[0013] On the other hand, the amorphous polyester used as the
heat-bonding component is a polyester having a glass transition
point of 50 to 100.degree. C. and not having a crystal-melting
point. When the glass transition point of said polyester is less
than 50.degree. C., the polyester is not preferable, because the
fibers are easily cohered each other, when drawn by the production
method described later, and because the conjugate fibers having
excellent dimensional stability comprising an area shrinkage
percent of not more than 20% can not be obtained. When the glass
transition point exceeds 100.degree. C., the polyester is also not
preferable, because the thermal bonding property is deteriorated at
low temperature of 120 to 150.degree. C.
[0014] The amorphous polyester includes random or block copolymers
comprising acid components such as terephthalic acid, isophthalic
acid, 2,6-naphthalene dicarboxylic acid, 5-sodium sulfoisophthalic
acid, adipic acid, sebacic acid, azelaic acid, dodecane
dicarboxylic acid, and 1,4-cyclohexane dicarboxylic acid, and diols
such as ethylene glycol, 1,3-propanediol, 1,4-butanediol,
1,5-pentanediol, 1,6-hexanediol, diethylene glycol,
1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol. Especially, an
amorphous copolyester comprising terephthalic acid component,
isophthalic acid component, ethylene glycol component and
diethylene glycol component is preferable from the points of costs
and handleability.
[0015] When the above-described copolyester comprising the
terephthalic acid component, the isophthalic acid component, the
ethylene glycol component and the diethylene glycol component is
used as the heat-bonding component, it is necessary to set the
copolymerization ratio so that the glass transition point of the
copolyester is included within the above-described range. However,
the molar ratio of the terephthalic acid component:the isophthalic
acid component is suitably 50:50 to 80:20, and the molar ratio of
the ethylene glycol component:the diethylene glycol component may
arbitrarily be selected within a range of 0:100 to 100:0.
[0016] When the heat-bonding component occupies all parts or a part
of the surfaces of the fibers (preferably not less than 40%,
especially not less than 60%, of the surfaces of the fibers) in the
polyester-based heat-bonding conjugate staple fibers of the present
invention, the polyester-based heat-bonding conjugate staple fibers
may be produced in any conjugate form selected from a sheath-core
type form, an eccentric sheath-core type form, a side-by-side type
form, a sea-island type form, a split type from, and the like. In
particular, the sheath-core type form, the eccentric sheath-core
type form, and the side-by-side type form are more preferable.
[0017] Next, it is necessary that the number of crimps and the
crimp percent of the polyester-based heat-bonding conjugate staple
fibers of the present invention are 3 to 40 crimps/25 mm and 3 to
40%, respectively. When the staple fibers have the number of crimps
of less than less than 3 crimps/25 mm or a crimp percent of less
than 3%, the fibers are not preferable, because the degree of
entanglement between the staple fibers is insufficient to
deteriorate the card passage of the staple fibers, whereby the high
grade fiber structure is not obtained. On the other hand, when the
staple fibers have the number of crimps of more than 40 crimps/25
mm or a crimp percent of more than 40%, the fibers are also not
preferable, because the degree of entanglement between the staple
fibers is too large to sufficiently card the staple fibers, whereby
a high grade fiber structure is not obtained. The number of crimps
and the crimp percent are more preferably 5 to 30 crimps/25 mm and
5 to 30%, respectively. The form of the crimps includes mechanical
crimps and three-dimensional crimps, and may suitably be selected
and set in response to the use or aim of the staple fibers.
[0018] The length and single fiber fineness of the polyester-based
heat-bonding conjugate staple fibers do not need to be especially
limited, and may suitably be set in response to the use and aim of
the staple fibers.
[0019] In the heat-bonding conjugate staple fibers of the present
invention, it is important that the web area shrinkage percent
defined as described below is not more than 20%. Thereby, said
conjugate staple fibers can be processed in the form of 100% or in
the form of a blend with other fibers to obtain a fiber structure
having excellent dimensional stability even in high temperature
atmosphere. When the shrinkage percent exceeds 20%, the fiber
structure having excellent dimensional stability in a high
temperature atmosphere can not be obtained. The web area shrinkage
percent is more preferably not more than 10%.
[0020] <Web Area Shrinkage Percentage>
[0021] A card web nonwoven fabric comprising 100% of the
heat-bonding conjugate staple fibers and having an area of A.sub.0
and a basis weight of 30 g/m.sup.2 is left in a hot air dryer
maintained at 150.degree. C. for two minutes, and then the area
A.sub.1 of the nonwoven fabric is measured. The web area shrinkage
percentage is determined by the following expression.
Web area shrinkage percentage
(%)=(A.sub.0-A.sub.1)/A.sub.0.times.100
[0022] The above-mentioned polyester-based heat-bonding conjugate
staple fibers of the present invention can efficiently be produced,
for example, by the following method. Namely, the above-mentioned
amorphous polyester and the polyalkylene terephthalate are
conjugated, preferably conjugated in the form of a sheath-core
type, an eccentric sheath-core type, or a side-by-side type, melted
and extruded. The extruded fibers are taken off at a speed of less
than 1,500 m/minute to obtain the undrawn conjugate fibers. Then,
the obtained undrawn conjugate fibers are subjected to the addition
of a polyether polyester block copolymer in an amount of not less
than 0.03 percent by weight on the basis of the weight of said
fibers, drawn in a draw ratio of 0.72 to 1.25 times the cold
maximum draw ratio at a temperature of T.sub.1 to
(T.sub.2+30.degree. C.), and further crimped into the crimped
fibers having the number of crimps of 3 to 40 crimps/25 mm and a
crimp percent of 3 to 40%, and then cut in a desired length, thus
enabling to produce the polyester-based heat-bonding conjugate
staple fibers. Herein, T.sub.1 is either higher temperature among
the glass transition point of the amorphous polyester and the glass
transition point of the polyalkylene terephthalate, and T.sub.2 is
the glass transition point of the amorphous polyester.
[0023] A take-off speed exceeding 1,500 m/minute is not preferable,
because the web area shrinkage percent can not be reduced to not
more than 20%, even when the obtained undrawn conjugate fibers are
drawn in the above-described conditions.
[0024] The first point on the above-described production method is
to add the polyether polyester block copolymer to the surfaces of
the conjugate fibers at a stage before the taken undrawn conjugate
fibers are drawn. Thereby, even when the undrawn conjugate fibers
are drawn at a temperature not less than the glass transition point
T.sub.2 of the amorphous polyester (namely, corresponding to the
softening point of the amorphous copolyester), the polyester-based
heat-bonding conjugate staple fibers having a web area shrinkage
percent of not more than 20% can be obtained without causing
cohesion between the fibers in the drawing process, when the
drawing temperature is not more than T.sub.2+30.degree. C. Further,
the fiber structure having excellent mechanical characteristics can
be obtained, because the heat-bonding property of the conjugate
fibers is not deteriorated so much, even when said polyether
polyester block copolymer is applied to the surfaces of the
conjugate fibers.
[0025] Such the simultaneous achievements of the
cohesion-preventing effect and the heat-bonding
property-maintaining effect are impossible with an anionic
surfactant or its polyoxyalkylene adduct, a cationic surfactant, a
nonionic surfactant, a mineral oil, or the like, which has usually
been used as an oiling agent for producing staple fibers, or even
with a polysiloxane-based treating agent.
[0026] A preferably used polyether polyester block copolymer
includes especially a copolymer comprising terephthalic acid
component and isophthalic acid component and/or an alkali metal
sulfoisophthalic acid component in a molar ratio of 40:60 to 100:0
as a dicarboxylic acid component and ethylene glycol as a glycol
component and copolymerized with 20 to 95 percent by weight of a
polyalkylene glycol having a number-average molecular weight of 600
to 10,000, and the copolymer is especially preferable from the
point of the stability of an aqueous emulsion and the point of an
cohesion generation-preventing effect in a drawing process. An acid
component such as adipic acid, sebacic acid, azelaic acid, dodecane
dicarboxylic acid, or 1,4-cyclohexanedicarboxylic acid and/or a
diol component such as 1,3-propanediol, 1,4-butanediol,
1,5-pentanediol, 1,6-hexanediol, diethylene glycol,
1,4-cyclohexanediol, or 1,4-cyclohexane dimethanol may be
copolymerized in small amounts. Additionally, in order to adjust
the molecular weight, one end of the polyalkylene glycol may be
sealed with an ether bond such as a monomethyl ether, a monoethyl
ether, or a monophenyl ether. The polyalkylene glycol includes
polyethylene glycol, ethylene oxide-propylene oxide copolymer,
polypropylene glycol, and polytetramethylene glycol. The
polyethylene glycol is especially preferable.
[0027] The number-average molecular weight of the polyether
polyester block copolymer is preferable to be in the range of 3,000
to 20,000, because of giving a higher cohesion-preventing
effect.
[0028] The amount of the polyether polyester block copolymer
adhered to the undrawn fibers is necessary to be not less than 0.03
percent by weight on the basis of said undrawn fibers. An amount of
less than 0.03 percent by weight is not preferable, because a
sufficient cohesion-preventing effect is not obtained in the
drawing process described later. On the other hand, the
cohesion-preventing effect reaches the highest limit and does not
increase, even when the adhesion amount is increased. Therefore, an
amount of not more than 0.5 percent by weight, especially a range
of 0.05 to 0.3 percent by weight, is suitable.
[0029] A method for applying the polyether polyester block
copolymer to the surfaces of the undrawn conjugate fibers is
especially not limited, and the polyether polyester block copolymer
may be applied by an arbitrary conventional known method usually in
the form of an aqueous emulsion solution. In order to stabilize
said emulsion solution, not only an emulsifier but also additives
such as an antistatic agent, a lubricant, a rust-preventing agent,
an antifungal agent, and an antibacterial agent may be added.
[0030] Next, the second point on the above-described production
method is a drawing temperature. Although it is undoubtedly
necessary to set the drawing temperature to a temperature of not
less than T.sub.2 (glass transition point of the amorphous
copolyester), it is simultaneously needed for the thermal setting
of the polyalkylene terephthalate of fiber-forming component to set
the drawing temperature to a temperature of not less than the glass
transition point of the polyalkylene terephthalate. Even if the
above-described polyether polyester block copolymer is
preliminarily imparted to the surfaces of the undrawn conjugate
fibers, the target heat-bonding conjugate staple fibers having the
excellent dimensional stability by the present invention may not be
obtained, when the drawing temperature is lower than either one of
the glass transition points of the amorphous copolyester and the
polyalkylene terephthalate. Further, it is also important not to
set the drawing temperature to high temperature exceeding T.sub.2
(glass transition point of the amorphous copolyester)+30.degree. C.
When the drawing temperature exceeds T.sub.2+30.degree. C., the
cohesion of the amorphous copolyester can sufficiently not be
prevented, and the generation of fused fiber bundles and the
deterioration in the stability of a crimper on the addition of
crimps to the fibers by the use of a push type crimper are caused.
Thereby, the drawing temperature exceeding T.sub.2+30.degree. C. is
not preferable.
[0031] When the drawing temperature is included in the
above-described range, the above-described drawing may be one step
drawing or more step drawing, but it is necessary that the total
draw ratio is 0.72 to 1.25 times the cold draw ratio. When the draw
ratio is less than 0.72 time the cold draw ratio, the draw ratio is
not preferable, because the dimensional stability of the produced
fiber structure is deteriorated. When the draw ratio is more than
1.25 times the cold draw ratio, the draw ratio is also not
preferable, because the decrease in the heat-bonding property as
well as the deterioration in the drawing property are caused. The
cold draw ratio of the undrawn fibers is obtained by drawing the
undrawn conjugate fibers collected within five minutes from the
just spun time at a speed 5 cm/second in an initial chuck length of
10 cm in air having a relative humidity of 65% at 25.degree. C.,
and then dividing the distance between the initial chuck length and
the chuck length at a time when the chuck can not be elongated, by
the initial chuck length (10 cm).
[0032] In the present invention, it is effective for the
improvement of the dimensional stability and for the prevention of
the cohesion that the above-described drawing is carried out in a
draw ratio of 0.7 to 1.0 time the cold draw ratio of the undrawn
conjugate fibers at a temperature of T.sub.1 (either higher
temperature among the glass transition point of the amorphous
copolyester and the glass transition point of the polyalkylene
terephthalate) to (T.sub.1+10.degree. C.) and then in a draw ratio
of 1.03 to 1.25 at a temperature of (T.sub.1+10.degree. C.) to
[T.sub.2 (glass transition point of the amorphous
copolyester)+30.degree. C.].
[0033] Additionally, it is especially effective to use hot water as
a drawing heating medium.
[0034] The drawn conjugate fibers are crimped in conditions giving
the number of crimps of 3 to 40 crimps/25 mm and a crimp percent of
3 to 40% by a known conventional method, and then cut in a desired
length. Namely, when the crimping form is a mechanical crimp form,
for example, a stuffing type crimper is used, and the conditions of
the stuffing pressure and temperature may suitably be controlled.
On the other hand, when the crimping form is a three-dimensional
crimp form, the conjugate structures of the conjugate fibers and
cooling conditions at the spinning time may suitably be
selected.
[0035] The obtained polyester-based heat-bonding conjugate staple
fibers of the present invention have good dimensional stability,
and are suitable for fiber structures such as nonwoven fabrics or
wadding. The heat-bonding conjugate staple fibers may singly be
used for the fiber structures such as the nonwoven fabrics, or the
heat-bonding conjugate staple fibers as main fibers may be blended
with other fibers and then used for the fiber structures such as
the nonwoven fabrics.
EXAMPLES
[0036] The present invention will be explained more concretely
hereafter with examples. Therein, evaluation items in Examples
obeyed the following methods.
[0037] (a) Glass Transition Point (Tg), Melting Point (Tm)
[0038] The glass transition point (Tg) and the melting point (Tm)
were measured with a differential scanning calorimeter DSC-7 type
manufactured by Perkin-Elmer Inc. at a temperature-rising rate of
20.degree. C./minute.
[0039] (b) Intrinsic Viscosity ([.eta.]).
[0040] The intrinsic viscosity was measured in ortho-chlorophenol
as a solvent at a temperature of 35.degree. C.
[0041] (c) Number of Crimps, Crimp Percent
[0042] The number of crimps and the crimp percent were measured by
a method described in JIS L 1015 7. 12.
[0043] (d) Fineness
[0044] The fineness was measured by a method described in JIS L
1015 7. 5. 1 A method.
[0045] (e) Fiber Length
[0046] The fiber length was measured by a method described in JIS L
1015 7. 4. 1 C method.
[0047] (f) Oil Pickup
[0048] A value obtained by measuring the weight of residues
extracted from fibers with 30.degree. C. methanol in a bath ratio
of 1:20 for 10 minutes and then dividing the measured weight by a
prescribed fiber weight.
[0049] (g) Web Area Shrinkage Percent and Deformation of Fiber
Structure
[0050] The area shrinkage percent was determined by forming a card
web comprising 100% of the heat-bonding conjugate staple fibers
having a basis weight of 30 g/m.sup.2 and an area A.sub.0 (25
cm.times.25 cm=625 cm.sup.2), leaving the formed card web in a hot
air drier (hot air circulation constant-temperature drier: 41-S4,
manufactured by Satake Kagaku Kikai Kogyo Kabushiki Kaisha)
maintained at 150.degree. C. for two minutes, measuring the area
A.sub.1 of the thermally treated card web and then applying the
area A.sub.1 to the following expression. The card web having an
area shrinkage percent of not more than 20% was accepted.
Area shrinkage percent (%)=(625-A.sub.1)/625.times.100
[0051] (h) Cohesion
[0052] When the cohesion was generated on the drawing of the fibers
to make the production impossible or when a cohered bonding was
confirmed in the card web, the fibers were judged to be defective,
and in other cases, the fibers were judged to be good.
Example 1
[0053] Polyethylene terephthalate having an intrinsic viscosity of
0.64, a Tg of 67.degree. C. and a Tm of 256.degree. C. was used as
a fiber-forming component. An amorphous copolyester copolymerized
from terephthalic acid component and isophthalic acid component in
a molar ratio of 60:40 as an acid component and ethylene glycol and
diethylene glycol in a molar ratio of 95:5 as a diol component, and
having an intrinsic viscosity of 0.56 and a Tg of 64.degree. C. was
used as a heat-bonding component. The pellets of the polymers were
vacuum-dried, fed into a sheath-core type conjugate melt-spinning
device and melt-spun from a spinneret having 450 spinning nozzles
in a conjugate ratio comprising a volume ratio of 50/50 at a
spinning temperature of 290.degree. C. in an extrusion rate of 650
g/minute. The spun fibers were cooled with 30.degree. C. cold air,
subjected to the adhesion of a treating agent comprising the
emulsion of a polyether polyester block copolymer copolymerized
from terephthalic acid component and isophthalic acid component in
a molar ratio of 80/20 as an acid component, ethylene glycol as a
glycol component, and polyethylene glycol having a number-average
molecular weight of 3,000 and having an average molecular weight of
10,000 in a pure content of 0.1 percent by weight on the basis of
the fibers by the use of an oiling roller, and then taken off at a
rate of 900 m/minute to obtain the undrawn sheath-core type
conjugate fibers. The cold maximum draw ratio (hereinafter,
referred to as CDR) of the undrawn fibers was 4.5.
[0054] The undrawn conjugate fibers were bundled to form the tow of
110,000 dtex (100,000 denier). The tow was first drawn in a draw
ratio of 3.5 (0.78 time CDR) in 72.degree. C. hot water, further
drawn in a draw ratio of 1.15 (total draw ratio is 4.0; 0.89 time
CDR) in 80.degree. C. hot water, oiled with a spinning oil
comprising potassium laurylphosphate, naturally cooled to
35.degree. C., crimped with a stuffing type crimper, and then cut
in a fiber length of 51 mm to obtain the heat-bonding conjugate
staple fibers having a single fiber fineness of 4.4 dtex, the
number of crimps of 10 crimps/25 mm and a crimp percent of 15%.
Examples 2 to 10, Comparative Examples 1 to 6
[0055] Heat-bonding conjugate stable fibers having a single fiber
fineness of 4.4 dtex, a fiber length of 51 mm, the number of crimps
of 10 crimps/25 mm, and a crimp percent of 15% were obtained in the
same conditions as in Example 1 except that the heat-bonding
component, the fiber-forming component, the treating agent, the
drawing ratio, and the drawing temperature were changed.
[0056] The fiber constitutions, treating agent kinds, spinning and
drawing conditions, and fiber evaluation results of the Examples
and the Comparative Examples are shown in Tables 1, 2, 3, and 4,
respectively.
1TABLE 1 Conjugate Type F1 F2 F3 F4 F5 F6 # I Acid Component TA 60
60 55 70 75 60 IA 40 40 40 30 25 40 SA -- -- 5 -- -- -- Glycol
Component EQ 95 100 100 62 44 95 DEG 5 -- -- 8 6 5 HMG -- -- -- 30
50 -- Tg .degree. C. 64 69 59 55 40 64 Tm .degree. C. -- -- -- --
-- -- [.eta.] 0.56 0.57 0.55 0.56 0.56 0.56 # II Polymer PET PET
PET PET PET PBT Tg .degree. C. 67 67 67 67 67 25 Tm .degree. C. 256
256 256 256 256 228 [.eta.] 0.64 0.64 0.64 0.64 0.64 0.87 #I:
Heat-bonding component #II: Fiber-forming component TA:
Terephthalic acid IA: Isophthalic acid SA: Sebacic acid EG:
Ethylene glycol DEG: Diethylene glycol HMG: Hexamethylene glycol
PET: Polyethylene terephthalate PBT: Polybutylene terephthalate
[0057]
2TABLE 2 Treating agent O 1 O 2 O 3 O 4 O 5 Polyether polyester
block -- -- copolymer component Acid component TA 80 90 72 IA 20 10
18 SIA -- -- 10 Glycol EG 100 100 100 component Polyalkylene Type
PEG M-PEG PEG glycol 3000 3000 4000 CD 70 80 70 Number-average
10000 9000 11000 molecular weight Other components -- -- -- Phos-
Phos- phate 1 phate 2 TA: Terephthalic acid IA: Isophthalic acid
SIA: 5-Sodium sulfophthalic acid PEG 3000: Polyethylene glycol
having an average molecular weight of 3000 PEG 4000: Polyethylene
glycol having an average molecular weight of 4000 M-PEG 3000:
Polyethylene glycol monophenyl ether having an average molecular
weight of 3000 CD: Copolymerization degree % Phosphate 1: Potassium
lauryl phosphate Phosphate 2: Partial potassium lauryl phosphate
having the average ethylene oxide addition number of five
moles.
[0058]
3 TABLE 3 Drawing Total Second drawing Spinning First step step
ratio Treating Ratio/ Ratio/ Ratio #1 agent CDR #2 CDR #2 CDR (CDR)
Example 1 F1 O 1 4.5 72 0.78 72 1.15 4.00(0.89) Compar- F1 O 1 4.5
65 0.78 60 1.15 4.00(0.89) ative example 1 Compar- F1 O 4 4.5 65
0.78 60 1.15 4.00(0.89) ative example 2 Compar- F1 O 4 4.5 72 0.78
72 1.15 4.00(0.89) ative example 3 Compar- F1 O 5 4.5 72 0.78 72
1.15 4.00(0.89) ative example 4 Example 2 F1 O 1 4.5 72 0.78 80
1.15 4.00(0.89) Example 3 F1 O 1 4.5 72 0.78 85 1.15 4.00(0.89)
Example 4 F1 O 1 4.5 72 0.96 80 1.05 4.54(1.01) Compar- F1 O 1 4.5
72 0.60 72 1.15 3.10(0.69) ative example 5 Example 5 F1 O 2 4.5 72
0.78 72 1.15 4.00(0.89) Example 6 F1 O 3 4.5 72 0.78 72 1.15
4.00(0.89) Example 7 F2 O 1 4.5 72 0.78 72 1.15 4.00(0.89) Example
8 F3 O 1 4.5 72 0.78 72 1.15 4.00(0.89) Example 9 F4 O 1 4.5 72
0.78 72 1.15 4.00(0.89) Compar- F5 O 1 4.5 72 0.78 72 1.15
4.00(0.89) ative example 6 Example F6 O 1 3.8 72 0.78 72 1.15
3.38(0.89) 10 #1: Conjugate type #2: Temperature
[0059]
4 TABLE 4 Fiber Appearance of Web area shrinkage Web grade after
Un-cohesion percent (%) shrinkage Example 1 Good 18.5 Good
Comparative Good 73.9 Defective example 1 Comparative Good 55.3
Defective example 2 Comparative Defective Could not be drawn --
example 3 Comparative Defective Could not be drawn -- example 4
Example 2 Good 8.1 Good Example 3 Good 5.1 Good Example 4 Good 6.8
Good Comparative Defective Could not be drawn -- example 5 Example
5 Good 17.5 Good Example 6 Good 18.1 Good Example 7 Good 18.3 Good
Example 8 Good 16.3 Good Example 9 Good 16.1 Good Comparative
Defective Could not be drawn -- example 6 Example 10 Good 14.8
Good
UTILIZATION IN INDUSTRY
[0060] The polyester-based heat-bonding conjugate staple fibers of
the present invention can provide high-grade fiber structures which
have good dimensional stability and hardly cause deformation, even
when used under high temperature atmospheres, although the fiber
structures can be formed at relative low temperature. In addition,
by the production method of the present invention, the
above-described heat-bonding conjugate staple fibers can extremely
stably and easily be produced without causing cohesion.
* * * * *