U.S. patent application number 16/616078 was filed with the patent office on 2020-06-04 for polyester fiber, preparation method therefor, and molded article formed therefrom.
The applicant listed for this patent is SK CHEMICALS CO., LTD.. Invention is credited to Sung-Gi KIM, Boo-youn LEE, Yoo Jin LEE.
Application Number | 20200173060 16/616078 |
Document ID | / |
Family ID | 64454811 |
Filed Date | 2020-06-04 |
![](/patent/app/20200173060/US20200173060A1-20200604-M00001.png)
United States Patent
Application |
20200173060 |
Kind Code |
A1 |
LEE; Boo-youn ; et
al. |
June 4, 2020 |
POLYESTER FIBER, PREPARATION METHOD THEREFOR, AND MOLDED ARTICLE
FORMED THEREFROM
Abstract
The present invention relates to a polyester fiber, a
preparation method thereof and a molded article prepared therefrom.
The polyester fiber comprises a diol moiety derived from isosorbide
in a specific amount and is formed into a polyester resin having a
specific oligomer content, thereby providing a molded article
having excellent saline water resistance, chemical resistance,
light resistance and good knot strength, and capable of maintaining
high transparency.
Inventors: |
LEE; Boo-youn; (Gyeonggi-do,
KR) ; KIM; Sung-Gi; (Gyeonggi-do, KR) ; LEE;
Yoo Jin; (Gyeonggi-do, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SK CHEMICALS CO., LTD. |
Gyeonggi-do |
|
KR |
|
|
Family ID: |
64454811 |
Appl. No.: |
16/616078 |
Filed: |
June 1, 2018 |
PCT Filed: |
June 1, 2018 |
PCT NO: |
PCT/KR2018/006322 |
371 Date: |
November 22, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D01F 6/62 20130101; C08G
63/863 20130101; D01F 1/10 20130101; D01F 1/09 20130101; C08G
63/183 20130101; C08K 3/32 20130101; D01F 1/106 20130101; B33Y
70/00 20141201; C08K 3/24 20130101; C08K 2003/329 20130101; D01D
5/098 20130101; C08K 3/04 20130101; D01F 6/84 20130101 |
International
Class: |
D01F 6/62 20060101
D01F006/62; C08G 63/86 20060101 C08G063/86; C08G 63/183 20060101
C08G063/183; C08K 3/32 20060101 C08K003/32; C08K 3/24 20060101
C08K003/24; C08K 3/04 20060101 C08K003/04; D01D 5/098 20060101
D01D005/098; D01F 1/09 20060101 D01F001/09; D01F 1/10 20060101
D01F001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 2, 2017 |
KR |
10-2017-0069239 |
Claims
1. A polyester fiber formed from a polyester resin polymerized with
a dicarboxylic acid including terephthalic acid or a derivative
thereof and a diol including isosorbide, thereby having an
alternating structure of an acid moiety derived from the
dicarboxylic acid or a derivative thereof and a diol moiety derived
from the diol, wherein the polyester resin includes 1 to 20 mol %
of a diol moiety derived from isosorbide and 2 to 5 mol % of a diol
moiety derived from diethylene glycol based on the total diol
moieties derived from the diol, and wherein the polyester resin has
an oligomer content of 1.3% by weight or less, and a haze of less
than 3% as measured according to ASTM D1003-97 for a specimen
having a thickness of 6 mm obtained from the polyester resin.
2. The polyester fiber of claim 1, wherein the haze is less than 2%
as measured according to ASTM D1003-97 for a specimen having a
thickness of 6 mm obtained from the polyester resin.
3. The polyester fiber of claim 1, wherein the polyester resin has
a number average molecular weight of 12,000 to 50,000 g/mol.
4. The polyester fiber of claim 1, wherein the polyester resin has
a weight average molecular weight of 45,000 to 225,000 g/mol.
5. The polyester fiber of claim 1, wherein the polyester resin has
a molecular weight distribution of 2.5 to 4.5.
6. The polyester fiber of claim 1, wherein the polyester resin
includes 5 to 12 mol % of a diol moiety derived from isosorbide and
2 to 5 mol % of a diol moiety derived from diethylene glycol, and a
diol moiety derived from residual aliphatic diols based on the
total diol moieties.
7. The polyester fiber of claim 1, wherein the polyester resin
resin contains 1 ppm to 300 ppm of a polycondensation catalyst, 10
ppm to 5000 ppm of a phosphorus-based stabilizer or 1 ppm to 300
ppm of a cobalt-based decoloring agent based on the central metal
atom.
8. The polyester fiber of claim 1, wherein the polyester resin has
a glass transition temperature of 82.degree. C. to 105.degree.
C.
9. The polyester fiber of claim 1, wherein the polyester fiber has
a density of 1.3 g/m.sup.3 to 1.4 g/m.sup.3 measured at 23.degree.
C.
10. The polyester fiber of claim 1, wherein the elongation is 14%
or more.
11. The polyester fiber of claim 1, wherein the tensile strength is
3.0 g/d or more.
12. The polyester fiber of claim 1, wherein the knot strength is
2.0 g/d or more.
13. The polyester fiber of claim 1, wherein the knot strength
retention rate is 40% or more, which is a percentage of the knot
strength to the tensile strength.
14. The polyester fiber of claim 1, further comprising at least one
additive selected from the group consisting of carbon black, a UV
screening agent, an antistatic agent, an impact modifier, an
antioxidant, and fine particles.
15. A method for preparing a polyester fiber comprising the steps
of: (a) carrying out an esterification reaction or a
transesterification reaction of a dicarboxylic acid or a derivative
thereof including terephthalic acid or a derivative thereof and a
diol comprising 1 mol to 25 mol of isosorbide and 65 mol to 200 mol
of ethylene glycol based on 100 mol of the total dicarboxylic acid
or a derivative thereof; (b) subjecting the esterification or
transesterification reaction product to a polycondensation reaction
to prepare a polyester resin polymerized with a dicarboxylic acid
including terephthalic acid or a derivative thereof and a diol
including isosorbide, thereby having an alternating structure of an
acid moiety derived from the dicarboxylic acid or a derivative
thereof and a diol moiety derived from the diol, wherein the
polyester resin includes 1 to 20 mol % of a diol moiety derived
from isosorbide and 2 to 5 mol % of a diol moiety derived from
diethylene glycol based on the total diol moieties derived from the
diol; (c) melt-spinning the polyester resin obtained in step (b) at
240.degree. C. to 310.degree. C.; and (d) drawing the melt-spun
undrawn fiber obtained in step (c) at a temperature equal to or
higher than the glass transition temperature of the polyester
resin, wherein in step (b), the polycondensation is carried out so
that an intrinsic viscosity, which is measured at 35.degree. C.
after dissolving the product obtained by the polycondensation
reaction in orthochlorophenol at a concentration of 1.2 g/dl at
150.degree. C. for 15 minutes, reaches 0.45 dl/g to 0.75 dl/g.
16. The method of preparing a polyester fiber of claim 15, wherein,
in step (a), the dicarboxylic acid or derivative thereof is a
dicarboxylic acid, and the initial mixing molar ratio of the
dicarboxylic acid to the diol is adjusted to 1:101 to 1.05, or the
dicarboxylic acid or derivative thereof is a dicarboxylic acid
alkyl ester or a dicarboxylic acid derivative of a dicarboxylic
acid anhydride, and the initial mixing molar ratio of the
dicarboxylic acid derivative to the diol is adjusted to 1:2.0 to
1:2.1.
17. The method of preparing a polyester fiber of claim 15, further
comprising removing unreacted materials including isosorbide by
allowing the product obtained by the esterification reaction or the
transesterification reaction to stand under a reduced pressure
condition of 400 to 1 mmHg for 0.2 to 3 hours, before the (b)
polycondensation reaction.
18. The method of preparing a polyester fiber of claim 15, wherein
the undrawn fiber is drawn at a draw ratio of 3 times or more in
step (d).
19. The method of preparing a polyester fiber of claim 15, wherein
the step (d) is carried out at a temperature of 80.degree. C. to
220.degree. C.
20. The method of preparing a polyester fiber of claim 15, further
comprising, after step (b) and before step (c), (b0-1) a step of
crystallizing the polymer prepared by polycondensation reaction;
and (b0-2) a step of subjecting the crystallized polymer to a solid
phase polymerization such that the intrinsic viscosity, which is
measured at 35.degree. C. after dissolving the polymer in
orthochlorophenol at a concentration of 1.2 g/dl at 150.degree. C.
for 15 minutes, is higher than the intrinsic viscosity of the resin
obtained in step (b) by 0.05 to 0.40 dl/g.
21. A molded article prepared from the polyester fiber according to
claim 1.
22. The molded article of claim 21, wherein the molded article is a
fishing gut, a fishing net, a pelt, a rope, a gut for racket, a
carpet, a rug, a mat, clothes.
23. The molded article of claim 21, wherein the polyester fiber
takes the form of a polyester filament fiber having a diameter of 4
mm or less, and the molded article is a resin molded product for a
3D printer.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
Technical Field
[0001] This application claims the benefit of priority from Korean
Patent Application No. 10-2017-0069239 filed on Jun. 2, 2017 with
the Korean Intellectual Property Office, the disclosure of which is
incorporated herein by reference in its entirety.
[0002] The present invention relates to a polyester fiber, a
preparation method thereof and a molded article prepared from the
polyester fiber.
Background
[0003] Polyamide, polyester, polyethylene, polyaramid, and the like
have been widely used as typical synthetic fiber materials.
[0004] Polyamide fibers composed of polyamide resins such as nylon
6, nylon 66 and nylon 6/66 are flexible and strong, and thus have
been used for fishing guts and fishing nets. However, the polyamide
fibers composed of nylon 6, nylon 66 and nylon 6/66 have a specific
gravity of 1.14, which is similar to the specific gravity of
seawater. Thus, there are problems that fishing guts, fishing nets
or the like made of polyamide fibers do not naturally sink in the
sea, and that the tensile strength, knot strength or the like are
deteriorated when they are brought into contact with seawater for a
long time. Further, it is required to use expensive additives in
order to ensure high transparency.
[0005] Meanwhile, PET (polyethylene terephthalate) represented by a
polyester resin has a low price, excellent physical properties and
a high specific gravity of 1.33. However, it has high crystallinity
and thus requires a high temperature during processing, and there
is a problem that transparency of a molded article such as a
fishing gut with a thickness higher than a certain level cannot be
secured. In addition, for applications such as pelt for paper
machines, a certain level or more of resistance to alkaline
chemicals is required, but PET has the disadvantage in that its
strength is decreased with time when exposed to alkaline chemical
and thus has a short replacement cycle.
[0006] Meanwhile, generally, as methods for preparing a molded
article in which a specific color has been imparted to a fiber,
there are two methods, namely, one method of dyeing a typical
polyester fiber and then weaving it, and another method of dyeing
after weaving. Since these two methods have different degrees of
adsorption during dyeing process, there is a problem that dyeing of
the final product is not uniformly performed.
[0007] Accordingly, the fibers used for fishing guts and fishing
nets are required to have a fast settling speed, high resistance to
seawater, high knot strength, high transparency or the like. In
addition, in order to provide a pelt for paper machines, it is
necessary to develop a material which is highly stable to alkali
and thus can increase the replacement cycle. Therefore, there is a
need to further study fibers which can increase settling speed, has
excellent saline water resistance, chemical resistance and
dyeability and exhibits a feature of high knot strength retention
rate.
Technical Problem
[0008] The present invention provides a polyester fiber and a
method for preparing the same.
[0009] The present invention also provides a molded article
prepared from the polyester fiber.
Technical Solution
[0010] In order to achieve the objects above, according to one
embodiment of the present invention, there is provided a polyester
fiber formed from a polyester resin polymerized with a dicarboxylic
acid including terephthalic acid or a derivative thereof and a diol
including isosorbide, thereby having an alternating structure of an
acid moiety derived from the dicarboxylic acid or a derivative
thereof and a diol moiety derived from the diol, wherein the
polyester resin includes 1 to 20 mol % of a diol moiety derived
from isosorbide and 2 to 5 mol % of a diol moiety derived from
diethylene glycol based on the total diol moieties derived from the
diol, and wherein the polyester resin has an oligomer content of
1.3% by weight or less, and a haze of less than 3% as measured
according to ASTM D1003-97 for a specimen having a thickness of 6
mm obtained from the polyester resin.
[0011] According to another embodiment of the present invention,
there is provided a method for preparing the polyester fiber and a
molded article prepared from the polyester fiber.
ADVANTAGEOUS EFFECTS
[0012] The polyester fiber according to one embodiment of the
present invention has a low oligomer content and is prepared into a
specimen having a thickness of 6 mm, which is ultimately formed
into a polyester resin exhibiting a haze of less than 3%, thereby
providing a molded article having excellent saline water
resistance, chemical resistance, light resistance and good knot
strength and capable of maintaining high transparency. Therefore,
the use of the polyester fiber can provide a molded article
suitable for various uses such as fishing guts, fishing nets, pelt
for paper machines, ropes, gut for rackets, carpets, rugs, mats,
clothes, and 3D printers, etc.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0013] Hereinafter, a polyester fiber, a preparation method
thereof, and a molded article prepared therefrom according to
specific embodiments of the invention will be described.
[0014] Unless otherwise specified, the terminology used herein is
for the purpose of describing particular embodiments only and is
not intended to limit the scope of the invention. Further, the
singular forms "a," "an" and "the" are intended to include the
plural forms as well, unless the context clearly indicates
otherwise. In addition, it will be further understood that the
meaning of the terms "comprise", "include" as used herein is
intended to specify the presence of stated features, ranges,
integers, steps, operations, elements and/or components, but does
not preclude the presence or addition of other features, ranges,
integers, steps, operations, elements and/or components.
[0015] Further, as used herein, fibers refer to including both a
filament which is a long fiber, and a staple which is a short
fiber.
[0016] According to one embodiment of the present invention, there
is provided a polyester fiber formed from a polyester resin
polymerized with a dicarboxylic acid including terephthalic acid or
a derivative thereof and a diol including isosorbide, thereby
having an alternating structure of an acid moiety derived from the
dicarboxylic acid or a derivative thereof and a diol moiety derived
from the diol, wherein the polyester resin includes 1 to 20 mol %
of a diol moiety derived from isosorbide and 2 to 5 mol % of a diol
moiety derived from diethylene glycol based on the total diol
moieties derived from the diol, and [0017] wherein the polyester
resin has an oligomer content of 1.3% by weight or less, and a haze
of less than 3% as measured according to ASTM D1003-97 for a
specimen having a thickness of 6 mm obtained from the polyester
resin.
[0018] The present inventors have conducted extensive and intensive
studies to develop synthetic fibers for providing fishing guts and
fishing nets requiring a high specific gravity and saline water
resistance, and pelt for paper machines requiring alkali
resistance, and as a result, they found that it is possible to
adjust the physical properties of undrawn fiber and ultimately
provide a molded article having desired physical properties,
thereby completing the present invention.
[0019] Specifically, the inventors have found that when a polyester
fiber is formed from a polyester resin having a specific content of
isosorbide introduced therein and having a low oligomer content, it
is possible to provide a molded article which exhibits a high
specific gravity and excellent mechanical properties, and also has
excellent saline water resistance, chemical resistance (alkali
resistance), light resistance, dyeing properties and high
transparency.
[0020] In the case of PET which is represented by a polyester
resin, the regularity of the polymer chain is high and a haze is
easily generated due to a fast crystallization rate, and thus its
use in applications requiring high transparency has been limited.
In particular, when a conventional polyester resin is formed to
have a large thickness, a haze is easily generated, and thus, its
use in applications requiring high transparency has been
limited.
[0021] In order to solve these problems, a method of introducing
isosorbide into the backbone of conventional polymers has been
introduced. However, residues derived from isosorbide deteriorated
the regularity of the polymer chain, which in turn deteriorated the
crystallization rate of the resin. In order to ensure sufficient
transparency, the polyester resin should contain a large amount of
diol moieties derived from isosorbide, but this caused a problem
that the polyester resin could not function as a crystalline resin
due to the large amount of diol moieties derived from isosorbide.
In addition, non-crystalline resins have low regularity of the
molecular structure and so cannot be formed by drawing. Due to
these problems, there was a limitation on the content of isosorbide
that can be introduced into the polymer backbone.
[0022] Regardless of these limitations, the polyester fiber
according to one embodiment of the present invention can be formed
from a polyester resin including a diol moiety derived from
isosorbide in an amount of 1 to 20 mol %, 3 to 20 mol %, 3 to 18
mol %, 5 to 20 mol %, 5 to 15 mol %, 9 to 20 mol %, 9 to 15 mol %,
or 6 to 12 mol % based on the total diol moieties, thereby
enhancing saline water resistance, chemical resistance, light
resistance and dyeability and exhibiting excellent mechanical
properties as well as excellent transparency.
[0023] More specifically, the polyester fiber according to one
embodiment of the present invention may be formed from a polyester
resin having a haze of less than 3%, less than 2.5%, less than 2%,
less than 1.5%, or less than 1.0% as measured according to ASTM
D1003-97 when prepared with a specimen having a thickness of 6 mm.
The polyester fiber according to one embodiment of the present
invention may be formed from a polyester resin in which no haze is
observed when prepared with a specimen having a thickness of 6 mm.
Thus, the lower limit of the haze may be 0%.
[0024] In addition, the polyester resin forming the polyester fiber
may have an intrinsic viscosity of 0.45 to 1.5 dl/g, 0.50 to 1.2
dl/g, 0.60 to 1.0 dl/g or 0.65 to 0.98 dl/g as measured at
35.degree. C. after dissolving it in orthochlorophenol at a
concentration of 1.2 g/dl at 150.degree. C. for 15 minutes. If the
intrinsic viscosity is less than the above range, defective
appearance may occur during molding, sufficient mechanical strength
may not be secured, and it may be difficult to exhibit a desired
physical property by high drawing. Further, if the intrinsic
viscosity exceeds the above range, the pressure of an extruder
rises due to an increase in the viscosity of the melt during
molding, and the spinning step may not be performed smoothly. In
addition, if the temperature of the extruder is raised in order to
address the rise in pressure, the physical properties may be
deteriorated due to heat distortion, and the drawing tension may
increase during the drawing step, which may cause a problem in the
process.
[0025] Meanwhile, the polyester fiber may further comprise at least
one additive selected from the group consisting of carbon black, a
UV screening agent, an antistatic agent, an impact modifier, an
antioxidant, and fine particles. The method of adding the additives
is not particularly limited. For example, a method such as adding
the additives at the time of preparing the polyester resin, or
preparing a high-concentration master batch of the additive,
followed by dilution and mixing, etc. can be used.
[0026] Hereinafter, a method for preparing such polyester fiber
will be described in detail.
[0027] The polyester fiber may be prepared by the method comprising
the steps of: [0028] (a) carrying out an esterification or a
transesterification reaction of a dicarboxylic acid or a derivative
thereof including terephthalic acid or a derivative thereof and a
diol including 1 mol to 25 mol of isosorbide and 65 mol to 200 mol
of ethylene glycol based on 100 mol of the total dicarboxylic acid
or a derivative thereof; [0029] (b) subjecting the esterification
reaction or transesterification reaction product to a
polycondensation reaction to prepare a polyester resin polymerized
with a dicarboxylic acid including terephthalic acid or a
derivative thereof and a diol including isosorbide, thereby having
an alternating structure of an acid moiety derived from the
dicarboxylic acid or a derivative thereof and a diol moiety derived
from the diol; [0030] (c) melt-spinning the polyester resin
obtained in step (b) at 240.degree. C. to 310.degree. C.; and
[0031] (d) drawing the melt-spun undrawn fiber obtained in step (c)
at a temperature equal to or higher than the glass transition
temperature of the polyester resin.
[0032] In step (b) of the preparation method, the polycondensation
reaction can be carried out so that an intrinsic viscosity, which
is measured at 35.degree. C. after dissolving the polycondensation
reaction product in orthochlorophenol at a concentration of 1.2
g/dl at 150.degree. C. for 15 minutes, reaches 0.45 dl/g to 0.75
dl/g, and the subsequent steps thereof may be carried out.
[0033] Further, in the step (c), the polyester resin can be
melt-spun at a relatively low temperature to minimize the thermal
decomposition of the polymer and maintain the long chain structure
of the polymer. Specifically, the step (c) may be carried out at a
temperature of 240.degree. C. to 310.degree. C. or 250.degree. C.
to 300.degree. C. When the melt spinning temperature is lower than
240.degree. C., there is a problem that the polymer is not melted,
and when the temperature is higher than 310.degree. C., the thermal
decomposition of the polymer increases and so the fiber easily
breaks during molding of the fiber, and thus the desired physical
properties may not be expressed, and the surface damage of a raw
fiber may lead to deterioration of the overall physical
properties.
[0034] The melt-spun undrawn fiber obtained in step (c) may be
cooled to a temperature equal to or lower than the glass transition
temperature of the polyester resin used. Thereafter, the undrawn
fiber may be drawn at a temperature equal to or higher than the
glass transition temperature of the polyester resin. Specifically,
the drawing step of the undrawn fiber may be carried out at a
temperature of 80.degree. C. to 220.degree. C. or 90.degree. C. to
210.degree. C. In the step (c), the undrawn fiber may be drawn at a
high magnification. Specifically, the undrawn fiber may be drawn at
a draw ratio of 3 times or more or 4 times or more.
[0035] In the method for preparing the polyester fiber, the
polyester resin may be prepared through the esterification reaction
(a) or transesterification; and the polycondensation reaction
(b).
[0036] Herein, the polyester resin may be prepared in a batch
process, a semi-continuous process or a continuous process, and the
esterification reaction or transesterification reaction and the
polycondensation reaction are preferably carried out under an inert
gas atmosphere, the mixing of the polyester resin with other
additives may be simple mixing or mixing by extrusion.
[0037] In addition, if necessary, a solid phase polymerization
reaction may proceed in succession. Specifically, the method for
preparing the polyester resin according to one embodiment of the
present invention may further include, after step (b) and before
step (c), (b0-1) a step of crystallizing the polymer prepared by
polycondensation reaction (melt polymerization); and (b0-2) a step
of subjecting the crystallized polymer to a solid phase
polymerization such that the intrinsic viscosity, which is measured
at 35.degree. C. after dissolving the polymer in orthochlorophenol
at a concentration of 1.2 g/dl at 150.degree. C. for 15 minutes,
reaches a value of 0.05 to 0.40 dl/g higher than the intrinsic
viscosity of the resin obtained in step (b).
[0038] As used herein, the term "dicarboxylic acid or a derivative
thereof" means at least one compound selected from dicarboxylic
acid and a derivative of dicarboxylic acid. The term "derivative of
dicarboxylic acid" means an alkyl ester of dicarboxylic acid (lower
alkyl ester having 1 to 4 carbon atoms such as monomethyl,
monoethyl, dimethyl, diethyl or dibutyl ester, etc.) or an
anhydride of dicarboxylic acid. Thus, for example, terephthalic
acid or a derivative thereof is collectively referred to as
terephthalic acid; monoalkyl or dialkyl terephthalate; and
compounds of forming a terephthaloyl moiety by reaction with diols,
such as terephthalic acid anhydride.
[0039] As the (i) dicarboxylic acid or derivatives thereof,
terephthalic acid or a derivative thereof is mainly used.
Specifically, terephthalic acid or a derivative thereof may be used
alone as the (i) dicarboxylic acid or derivatives thereof. Further,
the (i) dicarboxylic acid or derivatives thereof may be used in the
form of a mixture of terephthalic acid or a derivative thereof; and
at least one selected from the group consisting of an aromatic
dicarboxylic acid having 8 to 14 carbon atoms or a derivative
thereof and an aliphatic dicarboxylic acid having 4 to 12 carbon
atoms or a derivative thereof, which is a dicarboxylic acid or a
derivative thereof other than the terephthalic acid or a derivative
thereof. The aromatic dicarboxylic acid having 8 to 14 carbon atoms
or a derivative thereof may include an aromatic dicarboxylic acid
or a derivative thereof commonly used in the preparation of
polyester resins, for example, naphthalene dicarboxylic acid such
as isophthalic acid, dimethyl isophthalate, phthalic acid, dimethyl
phthalate, phthalic anhydride, 2,6-naphthalene dicarboxylic acid or
the like, dialkyl naphthalene dicarboxylate such as dimethyl
2,6-naphthalene dicarboxylate, or the like, diphenyldicarboxylic
acid, and the like. The aliphatic dicarboxylic acid having 4 to 12
carbon atoms or a derivative thereof may include a linear, branched
or cyclic aliphatic dicarboxylic acid or a derivative thereof
conventionally used in the preparation of polyester resins, for
example, cyclohexanedicarboxylic acid such as
1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid,
or the like, cyclohexanedicarboxylate such as dimethyl
1,4-cyclohexanedicarboxylate, dimethyl 1,3-cyclohexanedicarboxylate
or the like, sebacic acid, succinic acid, isodecyl succinic acid,
maleic acid, maleic anhydride, fumaric acid, adipic acid, glutaric
acid, azelaic acid, and the like.
[0040] The (i) dicarboxylic acid or a derivative thereof may
include terephthalic acid or a derivative thereof in an amount of
50 mol % or more, 60 mol % or more, 70 mol % or more, 80 mol % or
more, or 90 mol % or more based on the total (i) dicarboxylic acids
or derivatives thereof. The (i) dicarboxylic acid or a derivative
thereof may include a dicarboxylic acid or a derivative thereof
other than terephthalic acid or a derivative thereof in an amount
of 0 to 50 mol %, greater than 0 mol % and 50 mol % or less, or 0.1
to 40 mol % based on the total (i) dicarboxylic acids or
derivatives thereof. Within such a content range, the polyester
resin realizing appropriate physical properties can be
prepared.
[0041] Meanwhile, the isosorbide (1,4:3,6-dianhydroglucitol) is
used such that the diel moiety derived from isosorbide is 1 to 20
mol % or 6 to 12 mol based on the total diol moieties derived from
the diol of the polyester resin prepared.
[0042] A part of isosorbide may be volatilized or not reacted
during the synthesis of the polyester resin. Therefore, in order to
introduce the above-mentioned content of isosorbide into the
polyester resin, the isosorbide may be used in an amount of 1 mol
to 25 mol, or 6.5 mol to 25 mol based on 100 mol of the total
dicarboxylic acids or derivatives thereof.
[0043] If the content of isosorbide exceeds the above range, a
yellowing phenomenon may generate, and crystallinity may be
significantly reduced, which may be disadvantageous for the drawing
step. If the content is less than the above range, sufficient
saline water resistance, chemical resistance and mechanical
strength may not be exhibited, and a haze may generate. However,
when the content of isosorbide is adjusted within the
above-mentioned range to prepare into a specimen having a thickness
of 6 mm, the polyester resin exhibiting high transparency can be
provided, and thereby a polyester fiber having excellent saline
water resistance, chemical resistance, light resistance and
transparency can be provided.
[0044] The content of the diol moiety derived from diethylene
glycol introduced into the polyester resin is not directly
proportional to the content of ethylene glycol used for the
preparation of the polyester resin. However, ethylene glycol may be
used in an amount of 65 mol to 200 mol or 80 mol to 200 mol based
on 100 mol of the total dicarboxylic acids or derivatives thereof
so that the diol moiety derived from diethylene glycol is 2 to 5
mol % based on the total diol moieties derived from the diol of the
polyester resin.
[0045] If the content of the diol moiety derived from diethylene
glycol introduced into the polyester resin exceeds the above range,
it may not exhibit sufficient heat resistance, and if the content
is less than the above range, a haze may generate. In contrast, if
the content of the diol moiety derived from diethylene glycol is
less than the above range, the mechanical properties may not be
sufficient.
[0046] The polyester resin may include the diol moieties derived
from isosorbide and diethylene glycol as described above and diol
moieties derived from residual aliphatic diols based on the total
diol moieties. The aliphatic diol may be an aliphatic diol having 2
to 12 carbon atoms. Specific examples of the aliphatic diol include
a linear, branched or cyclic aliphatic diol such as triethylene
glycol, propanediol (1,2-propanediol, 1,3-propanediol or the like),
1,4-butanediol, pentanediol, hexanediol (1,6-hexanediol, or the
like), neopentyl glycol (2,2-dimethyl-1,3-propanediol),
1,2-cyclohexanediol, 1,4-cyclohexanediol,
1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol,
1,4-cyclohexanedimethanol, tetramethylcyclobutanediol or the like.
As the diol, the above-listed diols other than the isosorbide can
be included alone or in combination of two or more thereof. For
example, ethylene glycol, 1,4-cyclohexanedimethanol, or the like
may be added alone or in combination of two or more thereof to the
isosorbide. In the diol, the diol other than isosorbide may be
ethylene glycol, and the content of diol used for improving the
physical properties in addition to isosorbide and ethylene glycol
may be adjusted, for example, to 0 to 50 mol % or 0.1 to 30 mol %,
based on the total diols.
[0047] Meanwhile, in order to prepare the polyester resin, the
dicarboxylic acid or a derivative thereof and (ii) the diol may be
added to a reactor so that the molar ratio between the dicarboxylic
acid or a derivative thereof and the diol is 1.01 or more. In
addition, the diol may be supplied to the reactor at one time
before the polymerization reaction or may be added during the
polymerization reaction several times, if necessary.
[0048] According to a more specific embodiment, the polyester resin
satisfying a specific molecular weight distribution may be prepared
by adjusting the initial input amount of the dicarboxylic acid or a
derivative thereof and the diol in the initial stage of a reaction.
Thereby, the polyester fiber of one embodiment and the polyester
resin contained therein can be more effectively obtained.
[0049] In one example, when a dicarboxylic acid is used as the
dicarboxylic acid or a derivative thereof, the initial mixing molar
ratio between the dicarboxylic acid or a derivative thereof and the
diol may be adjusted to 1:1.01 to 1.05, and when a derivative such
as a dicarboxylic acid alkyl ester or a dicarboxylic acid anhydride
is used as the dicarboxylic acid or a derivative thereof, the
initial mixing molar ratio between the dicarboxylic acid or a
derivative and the diol may be adjusted to 1:2.0 to 1:2.1.
[0050] The initial mixing molar ratio may refer to a mixing molar
ratio at the start of the polymerization reaction in the reactor,
and a dicarboxylic acid or a derivative and/or a diol may be
further added during the reaction if necessary.
[0051] Meanwhile, a catalyst may be used in the (a) esterification
reaction or transesterification reaction. Examples of the catalyst
include a methylate of sodium and magnesium; an acetate, a borate,
a fatty acid salt, a carbonate, and an alkoxy salt of Zn, Cd, Mn,
Co, Ca, Ba, Ti or the like; metal Mg; an oxide of Pb, Zn, Sb, Ge,
or the like.
[0052] The (a) esterification reaction or the transesterification
reaction may be carried out as a batch process, a semi-continuous
process or a continuous process, and each raw material may be added
separately, but it may be preferably added in the form of a slurry
in which the dicarboxylic acid or a derivative thereof is mixed to
the diol.
[0053] A polycondensation catalyst, a stabilizer, a coloring agent,
a crystallizing agent, an antioxidant, a branching agent and the
like may be added to the slurry before the start of the (a)
esterification reaction or the transesterification reaction, or to
the product after the completion of the reaction.
[0054] However, the timing of adding the above-described additives
is not limited thereto, and they may be added at any time point
during the preparation of the polyester resin. As the
polycondensation catalyst, at least one of conventional
titanium-based catalyst, germanium-based catalyst, antimony-based
catalyst, aluminum-based catalyst, tin-based catalyst, or the like
may be appropriately selected and used. Examples of the useful
titanium-based catalyst include tetraethyl titanate,
acetyltripropyl titanate, tetrapropyl titanate, tetrabutyl
titanate, polybutyl titanate, 2-ethylhexyl titanate, octylene
glycol titanate, lactate titanate, triethanolamine titanate,
acetylacetonate titanate, ethyl acetoacetic ester titanate,
isostearyl titanate, titanium dioxide, titanium dioxide/silicon
dioxide copolymer, titanium dioxide/zirconium dioxide copolymer or
the like. Further, examples of the useful germanium-based catalyst
include germanium dioxide and a copolymer thereof. The added amount
of the polycondensation catalyst may be adjusted in the range of 1
ppm to 300 ppm relative to the weight of the final polymer
(polyester resin) based on the central metal atom.
[0055] As the stabilizer, generally, a phosphor-based stabilizer
such as phosphoric acid, trimethyl phosphate, triethyl phosphate,
or the like may be used, and the added amount thereof may be in the
range of 10 ppm to 5000 ppm relative to the weight of the final
polymer (polyester resin) based on the phosphorus atom. If the
added amount of the stabilizer is less than 10 ppm, the polyester
resin may not be sufficiently stabilized and the color of the
polyester resin may become yellow. If the added amount exceeds 5000
ppm, a desired polymer having a high degree of polymerization may
not be obtained. Examples of the coloring agent added for improving
the color of the polymer include a cobalt-based decoloring agent
such as cobalt acetate, cobalt propionate or the like, and the
added amount thereof is 1 to 300 ppm relative to the weight of the
final polymer (polyester resin) based on the cobalt atom. If
necessary, as an organic coloring agent, an anthraquionone-based
compound, a perinone-based compound, an azo-based compound, a
methine-based compound and the like may be used. Commercially
available products include a toner such as Polysynthrene Blue RLS
manufactured by Clarient or Solvaperm Red BB manufactured by
Clarient. The added amount of the organic coloring agent may be
adjusted in the range of 0 to 50 ppm relative to the weight of the
final polymer. If the coloring agent is used in an amount outside
the above range, the yellow color of the polyester resin may not be
sufficiently concealed or the physical properties may be
deteriorated.
[0056] Examples of the crystallizing agent include a crystal
nucleating agent, a UV absorber, a polyolefin-based resin, a
polyamide resin or the like. Examples of the antioxidant include a
hindered phenol-based antioxidant, a phosphite-based antioxidant, a
thioether-based antioxidant, or a mixture thereof. As the branching
agent, for example, trimellitic anhydride, trimethylol propane,
trimellitic acid or a mixture thereof may be used as a conventional
branching agent having three or more functional groups.
[0057] The (a) esterification reaction or the transesterification
reaction may be carried out at a temperature of 150 to 300.degree.
C. or 200 to 270.degree. C. under a pressure condition of 0 to 10.0
kgf/cm.sup.2 (0 to 7355.6 mmHg), 0 to 5.0 kgf/cm.sup.2 (0 to 3677.8
mmHg) or 0.1 to 3.0 kgf/cm.sup.2 (73.6 to 2206.7 mmHg). Here, the
pressure stated in the outside of the parenthesis refers to a gauge
pressure (expressed in kgf/cm.sup.2); and the pressure stated in
the parenthesis refers to an absolute pressure (expressed in
mmHg).
[0058] If the reaction temperature and pressure deviate from the
above range, the physical properties of the polyester resin may be
deteriorated. The reaction time (average retention time) is usually
1 to 24 hours or 2 to 8 hours, and may vary depending on the
reaction temperature, the pressure, and the molar ratio of the
dicarboxylic acid or a derivative thereof to the diol used.
[0059] The product obtained by the esterification reaction or the
transesterification reaction may be prepared into a polyester resin
having a higher degree of polymerization by polycondensation
reaction. Generally, the polycondensation reaction is carried out
at a temperature of 150 to 300.degree. C., 200 to 290.degree. C. or
250 to 290.degree. C. under a reduced pressure of 0.01 to 400 mmHg,
0.05 to 100 mmHg or 0.1 to 10 mmHg. Herein, the pressure refers to
the range of absolute pressures. The reduced pressure of 0.01 mmHg
to 400 mmHg is used to remove glycol as a by-product of the
polycondensation reaction, and isosorbide as an unreacted material,
etc. Thus, if the reduced pressure condition deviates from the
above range, the by-products and unreacted materials may not be
sufficiently removed. Moreover, if the temperature of the
polycondensation reaction deviates from the above range, the
physical properties of the polyester resin may be deteriorated. The
polycondensation reaction is carried out for a period of time
required to reach a desirable intrinsic viscosity, for example, it
may be carried out for an average retention time of 1 hours to 24
hours.
[0060] For the purpose of reducing the amount of unreacted
materials such as isosorbide remaining in the polyester resin, it
is possible to intentionally increase the vacuum reaction at the
last stage of the esterification reaction or transesterification
reaction or at the initial stage of the polycondensation reaction,
that is, at a state in which the viscosity of the resin is not
sufficiently high, thereby discharging the unreacted raw materials
out of the system. When the viscosity of the resin is increased, it
may be difficult for raw materials remaining in the reactor to
escape out of the system. In one example, before the
polycondensation reaction, the reaction product obtained by the
esterification reaction or the transesterification reaction is
allowed to stand at a reduced pressure condition of about 400 to 1
mmHg or about 200 to 3 mmHg for 0.2 to 3 hours to effectively
remove unreacted materials such as isosorbide remaining in the
polyester resin. Herein, the temperature of the product may be
controlled to a temperature equal to the temperature of the
esterification reaction or transesterification reaction and of the
polycondensation reaction, or to a temperature therebetween.
[0061] As the process of flowing out the unreacted raw materials
through the control of the vacuum reaction is further added, the
amount of unreacted materials such as isosorbide remaining in the
polyester resin can be reduced, and consequently, the polyester
fiber satisfying the physical properties of one embodiment and the
polyester resin included therein can be more effectively
obtained.
[0062] Meanwhile, as already described above, the intrinsic
viscosity of the polymer after the polycondensation reaction is
appropriately in the range of 0.45 dl/g to 0.75 dl/g.
[0063] In particular, if the crystallization step (b0-1) and the
solid phase polymerization step (b0-2) described above are
employed, the intrinsic viscosity of the polymer after the
polycondensation reaction can be adjusted to 0.45 to 0.75 dl/g,
0.45 to 0.70 dl/g or 0.50 to 0.70 dl/g. If the intrinsic viscosity
after the polycondensation reaction is less than 0.45 dl/g, the
reaction speed in the solid phase polymerization reaction is
significantly reduced, and a polyester resin having a very high
molecular weight distribution is obtained. If the intrinsic
viscosity exceeds 0.75 dl/g, as the viscosity of the melt increases
during the melt polymerization, the possibility of discoloration of
the polymer is increased due to the shear stress between the
stirrer and the reactor, and side reaction materials such as
acetaldehyde are also increased. Meanwhile, when the
polycondensation reaction is carried out so as to have a high
intrinsic viscosity, which is then introduced into the solid phase
polymerization stage, a polyester resin having a uniform molecular
weight distribution can be obtained, thereby further improving the
chemical resistance and transparency.
[0064] Meanwhile, if the crystallization step (b0-1) and the solid
phase polymerization step (b0-2) described above are not employed,
the intrinsic viscosity of the polymer after the polycondensation
reaction may be adjusted to 0.65 to 0.75 dl/g. If the intrinsic
viscosity is less than 0.65 dl/g, the crystallization rate
increases due to the low molecular weight polymer, and so it may be
difficult to provide a polyester resin having excellent heat
resistance and transparency. If the intrinsic viscosity exceeds
0.75 dl/g, as the viscosity of the melt increases during the melt
polymerization, the possibility of discoloration of the polymer is
increased due to the shear stress between the stirrer and the
reactor, and side reaction materials such as acetaldehyde are also
increased.
[0065] A polyester resin capable of forming the polyester fiber
according to one embodiment can be produced through the steps (a)
and (b). If necessary, the crystallization step (b0-1) and the
solid phase polymerization step (b0-2) may be further carried out
after the (b) polycondensation reaction to provide a polyester
resin having a higher degree of polymerization.
[0066] Specifically, in the crystallization step (b0-1), the
polymer obtained by the polycondensation reaction (b) is discharged
out of the reactor to be granulated. As the granulation method, a
strand cutting method of extruding into a strand type, solidifying
in a cooling liquid and then cutting with a cutter, or an
underwater cutting method of immersing a die hole in a cooling
liquid, directly extruding in a cooling liquid and then cutting
with a cutter can be used. Generally, in the strand cutting method,
the cooling liquid is maintained at a low temperature to enable the
solidification of the strand, thereby preventing cutting problems.
In the underwater cutting method, it is preferred that the
temperature of the cooling liquid is maintained in accordance with
the polymer so that the shape of the polymer becomes uniform.
However, in the case of a crystalline polymer, the temperature of
the cooling liquid may be intentionally maintained at a high level
in order to induce crystallization during discharge.
[0067] Meanwhile, it is also possible to additionally wash the
granulated polymer with water. The temperature of water during
washing is preferably equal to or lower by about 5 to 20.degree. C.
than the glass transition temperature of the polymer, and fusion
may occur at a higher temperature, which is not preferable. In the
case of polymer particles that induce the crystallization during
discharge, fusion does not occur at a temperature higher than the
glass transition temperature, and thus, the temperature of water
may be set according to the degree of crystallization. Through
washing of the granulated polymer, the raw materials dissolved in
water among the unreacted raw materials can be removed. As the
particle size decreases, the surface area relative to the weight of
the particles increases, and thus, a smaller particle size is
preferred. In order to achieve such purpose, the particles may be
prepared to have an average weight of about 14 mg or less.
[0068] The granulated polymer undergoes the crystallization step to
prevent fusion during the solid phase polymerization. The
crystallization may be carried out under the atmosphere, inert gas,
water vapor, vapor-containing inert gas atmosphere or in a solution
at 110.degree. C. to 180.degree. C. or 120.degree. C. to
180.degree. C. If the temperature is low, the rate at which the
crystals of the particles are formed is too slow. If the
temperature is high, the particles are melted at a faster rate than
the rate at which the crystals are formed, making the particles to
stick together, thereby causing fusion to occur. Since the heat
resistance of the particles increases as the particles are
crystallized, it is also possible to carry out the crystallization
by dividing it into several steps and raising the temperature
stepwise.
[0069] The solid phase polymerization reaction may be carried out
under an inert gas atmosphere such as nitrogen, carbon dioxide,
argon or the like, or under a reduced pressure condition of 400 to
0.01 mmHg at a temperature of 180.degree. C. to 220.degree. C. for
an average retention time of 1 hour or more, preferably 10 hours or
more. This solid phase polymerization further increases the
molecular weight, and the raw materials, which remain unreacted in
the melting reaction, and cyclic oligomers, acetaldehydes and the
like generated during the reaction may be removed.
[0070] In order to provide the polyester resin according to one
embodiment, the solid phase polymerization may be carried out until
the intrinsic viscosity reaches a value of 0.05 dl/g to 0.40 dl/g
higher than the intrinsic viscosity of the resin obtained in the
polycondensation reaction step (b). If the difference between the
intrinsic viscosity of the resin after the solid phase
polymerization reaction and the intrinsic viscosity of the resin
before the solid phase polymerization is less than 0.05 dl/g, a
sufficient degree of polymerization improving effect cannot be
obtained. If the difference between the intrinsic viscosity of the
resin after the solid phase polymerization and the intrinsic
viscosity of the resin before the solid phase polymerization
exceeds 0.40 dl/g, the molecular weight distribution becomes wide
and so a sufficient heat resistance cannot be exhibited, and
further the content of the oligomer is relatively increased and so
the possibility of generation of a haze is increased.
[0071] The solid phase polymerization is carried out in such a
manner that the intrinsic viscosity of the resin is 0.05 to 0.40
dl/g higher than the intrinsic viscosity of the resin before the
solid phase polymerization and until the intrinsic viscosity
reaches a value of 0.70 dl/g or more, 0.70 to 1.0 dl/g, or 0.70 to
0.98 dl/g. When the solid phase polymerization is continued until
it reaches the intrinsic viscosity within such range, the molecular
weight distribution of the polymer becomes narrower, thereby
decreasing the crystallization rate during molding. Accordingly,
the heat resistance and the degree of crystallinity can be improved
without deteriorating the transparency. If the intrinsic viscosity
of the resin after the solid phase polymerization reaction is less
than the above range, it may be difficult to provide a polyester
fiber having excellent transparency due to an increase in the
crystallization rate by the oligomers having a low molecular
weight.
[0072] The polyester resin prepared by the above method has an
alternating structure of an acid moiety derived from a dicarboxylic
acid or a derivative thereof and a diol moiety derived from a diol.
In the specification, the acid moiety and the diol moiety refer to
a residue remaining after the dicarboxylic acid or a derivative
thereof and the diol are polymerized and hydrogen, hydroxyl or
alkoxy groups are removed therefrom.
[0073] In particular, the polyester resin is prepared according to
the method described above and has features that a diol moiety
derived from isosorbide is 1 to 20 mol % and a diol moiety derived
from diethylene glycol is 2 to 5 mol %, based on the total diol
moieties derived from the diol, an oligomer content of the
polyester resin is 1.3% by weight or less, and a haze is less than
3% as measured according to ASTM D1003-97 for a specimen having a
thickness of 6 mm obtained from the polyester resin. Accordingly,
the polyester fiber formed from the polyester resin can exhibit
excellent saline water resistance, chemical resistance, light
resistance and dyeability and can exhibit improved mechanical
strength and transparency as described above.
[0074] The polyester resin mainly has an alternating structure of
an acid moiety derived from a dicarboxylic acid or a derivative
thereof and a diol moiety derived from a diol, but it may include a
structure in which the diols react with other diols due to side
reactions and so diol moieties derived from the diol are connected
to each other. However, according to the method described above,
such side reactions can be remarkably reduced. In an example, the
residue derived from diethylene glycol may be contained in an
amount described above based on the residue derived from the total
diols in the polyester resin. The polyester resin contains the
residues derived from diethylene glycol within such a range and
thus may exhibit a sufficient glass transition temperature.
[0075] The polyester resin forming the polyester fiber may have a
number average molecular weight (Mn) of about 12,000 to 50,000
g/mol or about 15,000 to 40,000 g/mol. The polyester resin may have
a weight average molecular weight (Mw) of 45,000 to 250,000 g/mol
or 50,000 to 225,000 g/mol. Further, the molecular weight
distribution (PDI) of the polyester resin may be in the range of
2.5 to 4.5 or 2.8 to 4.0.
[0076] If the weight average molecular weight is less than the
above range, the mechanical properties, for example, tensile
strength, knot strength or the like may be deteriorated. If the
weight average molecular weight exceeds the above range,
processability may deteriorate as the melting point increases, and
the spinning step may not perform smoothly due to an increase in
pressure during spinning.
[0077] The polyester resin may have a glass transition temperature
(Tg) of 82.degree. C. to 105.degree. C. Within such a range,
various physical properties of the polyester resin can be favorably
exhibited without a yellowing phenomenon.
[0078] The polyester resin may or may not have a crystallization
temperature (Tc) and a melting point (Tm) in accordance with a
differential scanning calorimetry (DSC) measurement condition. The
polyester resin having a glass transition temperature (Tg) ranging
from 82.degree. C. to 90.degree. C. may have a crystallization
temperature (Tc) of 120.degree. C. to 200.degree. C. or 130.degree.
C. to 190.degree. C. In the polyester resin having a glass
transition temperature (Tg) of 90.degree. C. to 105.degree. C. or
92.degree. C. to 105.degree. C., the crystallization temperature
(Tc) is not measured, or it may be in the range of about
130.degree. C. to 190.degree. C. or 140.degree. C. to 180.degree.
C. Within the range, the polyester resin has an appropriate
crystallization rate and thus can enable the solid phase
polymerization reaction and exhibit high transparency after
molding.
[0079] The polyester fiber according to one embodiment of the
present invention may be formed from the polyester resin described
above and may have a density of 1.3 to 1.4 g/m.sup.3 as measured at
23.degree. C. Accordingly, the polyester fiber may exhibit a
specific gravity of about 1.3 or more, which is higher than that of
seawater, and thus, fishing guts or fishing nets prepared therefrom
can naturally sink in the water, thereby satisfying the needs of
the industry.
[0080] The polyester fiber may exhibit a tensile strength of 3.0
g/d or more, 3.0 to 5.0 g/d, or 3.2 to 4.5 g/d. In addition, the
polyester fiber may exhibit an elongation of 14% or more, 14% to
50%, or 15% to 50%. Accordingly, a molded article prepared from the
polyester fiber can exhibit sufficient toughness and appropriate
modulus.
[0081] The polyester fiber may have a knot strength of 2.0 g/d or
more, 2.0 to 4.0 g/d, or 2.1 to 4.0 g/d, as measured by an over
hand knot method. The polyester fiber may have a knot strength
retention rate of 40% or more, 40% to 80%, 50% to 80%, 60% to 80%,
65% to 80% 65% to 75% or 68% to 75%, which is calculated as a
percentage of the knot strength relative to the tensile
strength.
[0082] As described above, the polyester fiber according to one
embodiment of the present invention exhibits excellent saline water
resistance, chemical resistance, light resistance and dyeability,
and has improved mechanical strength and transparency and thus can
be utilized in various fields. In particular, it is expected to be
useful for applications in fishing guts and fishing nets requiring
a high specific gravity and high saline water resistance and in
pelt for paper machines requiring high chemical resistance (alkali
resistance). In addition, the polyester fiber is expected to be
useful for application in ropes, gut for rackets, carpets, rugs,
mats and clothes due to the excellent properties described above.
Moreover, the polyester fiber takes the form of a polyester
filament fiber having a diameter of 4 mm or less and thus is
expected to be useful for application in 3D printers.
[0083] Meanwhile, according to anther embodiment of the present
invention, there is provided a molded article prepared from the
polyester fiber. The molded article may be a molded product for
fishing guts, fishing nets, pelt, ropes, gut for rackets, carpets,
rugs, mats, clothes or 3D printers, etc.
[0084] Hereinafter, the action and effect of the present invention
will be described by way of specific Examples. However, these
Examples are given for illustrative purposes only, and they are not
intended to limit the scope of the invention in any manner.
[0085] The following physical properties were measured according to
the methods below.
[0086] (1) Intrinsic viscosity (IV): The intrinsic viscosity of the
specimen was measured using a Ubbelohde viscometer after dissolving
the specimen in orthochlorophenol (OCP) at a concentration of 1.2
g/dl at 150.degree. C. for 15 minutes. Specifically, the
temperature of the viscometer was maintained at 35.degree. C. and
the time (efflux time) to required for a solvent to pass between
the specific internal sections of the viscometer and the time t
required for a solution to pass therebetween were determined.
Thereafter, the value of to and the value of t were substituted
into Equation 1 to calculate a specific viscosity, and the
calculated specific viscosity value was substituted into Equation 2
to calculate an intrinsic viscosity.
.eta. sp = t - t 0 t 0 [ Equation 1 ] [ .eta. ] = 1 + 4 A .eta. sp
- 1 2 Ac [ Equation 2 ] ##EQU00001##
in Equation 2, A represents the Huggins constant, which was 0.247,
and c represents a concentration value, which was 1.2 g/dl.
[0087] (2) Glass transition temperature (Tg): The Tg of the
polyester resins prepared in Examples and Comparative Examples was
measured by DSC (differential scanning calorimetry). DSC 1 model
manufactured by Mettler Toledo was used as the measuring device.
Specifically, the polyester resin sample used for the analysis was
dried for 5 to 10 hours under a nitrogen atmosphere at 120.degree.
C. using a dehumidifying dryer (model name: D2T manufactured by
Moretto). Thus, the Tg was measured in a state in which the amount
of water remaining in the sample was less than 500 ppm. About 6 to
10 mg of the dried sample was taken and filled into an aluminum
pan. Then, the sample was heated from room temperature to
280.degree. C. at a rate of 10.degree. C./min (first scan) and
annealed at 280.degree. C. for 3 minutes. After the sample was
rapidly cooled to room temperature, the sample was again heated
from room temperature to 280.degree. C. at a rate of 10.degree.
C./min to obtain a DSC curve (second scan). Then, the Tg value in
the DSC second scan was analyzed through the glass transition
function in the DSC menu of the related program (STARe
[0088] Software) provided by Mettler Toledo. Herein, the Tg is
defined as the temperature at which the maximum slope of the curve
appears at the point where the DSC curve obtained during the second
scan changes to a stair shape for the first time during the
temperature rising process. The temperature range of the scan was
set from -20.degree. C..about.15.degree. C. to 15.degree.
C..about.20.degree. C. of the midpoint calculated from the
program.
[0089] (3) Thickness of Fiber
[0090] The long and short diameters of the polyester fibers and
nylon 6 fibers prepared in Examples and Comparative Examples were
measured using an optical microscope and expressed as an average
value.
[0091] (4) Oligomer Content
[0092] 0.3 g of the sample of the polyester fibers and nylon 6
fibers prepared in Examples and Comparative Examples was each
dissolved in 15 mL of o-chlorophenol at 150.degree. C. for 15
minutes, and then 9 mL of chloroform was added thereto at room
temperature. GPC was a product of Tosoh, and the molecular weight
of the sample was measured using an RI detector. The oligomer
content was measured by determining the area of molecular weight of
1000 or less in the total area.
[0093] (5) Density (Measured at 23.degree. C.)
[0094] The density of the polyester fibers and nylon 6 fibers
prepared in Examples and Comparative Examples were measured at
23.degree. C. using a gradient density column. Two solutions having
different densities were sequentially mixed and put into a
graduated glass tube so that a certain range of densities could be
measured, and then glass beads, the density of which was confirmed
after preparation, were floated to prepare a calibration curve. The
measured specimens were submerged in the gradient density column,
and the height of the glass beads floated was measured, then the
density was calculated proportionally based on the calibration
curve.
[0095] (6) Elongation
[0096] The elongation of the polyester fibers and nylon 6 fibers
prepared in Examples and Comparative Examples were measured at a
rate of 200 mm/min using the UTM universal testing machine model
Z011 manufactured by Zwick/Roell when the specimen was cut.
[0097] (7) Tensile Strength
[0098] The tensile strength of the polyester fibers and nylon 6
fibers prepared in Examples and Comparative Examples were
determined at a rate of 200 mm/min using the UTM universal testing
machine model Z011 manufactured by Zwick/Roell by dividing cutting
force(kgf) by fineness.
[0099] (8) Knot Strength
[0100] The strength at break of the polyester fibers and nylon 6
fibers prepared in Examples and Comparative Examples was measured
in the same manner as in the tensile strength after making a knot
at the center of the fiber.
[0101] (9) Knot Strength Retention Rate
[0102] The knot strength retention rate was evaluated as a
percentage of the knot strength relative to the tensile
strength.
[0103] Knot strength retention rate (%) =knot strength/tensile
strength*100
[0104] (10) Saline Water Resistance
[0105] The polyester fibers and nylon 6 fibers prepared in Examples
and Comparative Examples were each placed in a 10% NaCl solution
and immersed at room temperature for 120 hours, and then the force
was measured using the UTM Instron. The saline water resistance was
evaluated by the ratio of the post-immersion force to the
pre-immersion force (initial force) (post-immersion force/initial
force*100).
[0106] (11) Chemical Resistance
[0107] The polyester fibers and nylon 6 fibers prepared in Examples
and Comparative Examples were each placed in a 20% NaOH solution or
a 20% KOH solution and immersed at room temperature for 120 hours,
and then the force was measured using the UTM Instron. The chemical
resistance against NaOH and the chemical resistance against KOH
were evaluated by the ratio of the post-immersion force to the
pre-immersion force (initial force) (post-immersion force/initial
force*100).
[0108] (12) Light Resistance
[0109] The polyester fibers and nylon 6 fibers prepared in Examples
and Comparative Examples were each exposed to UV rays (340 nm, 0.55
W/m.sup.2) for 50 hours at 50.degree. C., and then the force was
measured using the UTM Instron. The light resistance was evaluated
by the ratio of post-exposure force to pre-exposure force (initial
force) (post-exposure force/initial force*100)
[0110] (13) Haze
[0111] Specimens having the same thickness as the fibers of
Examples and Comparative Examples were prepared using the polyester
resins and nylon 6 resins prepared in Examples and Comparative
Examples, and the haze of the specimens was measured using a
CM-3600A measuring device (Minolta) according to ASTM D1003-97 test
method.
[0112] (14) Absorption Rate
[0113] 10 g of fiber was collected from each of the polyester
fibers and nylon 6 fibers prepared in Examples and Comparative
Examples, immersed in distilled water for 24 hours, allowed to
stand at room temperature, and dried in an oven at 105.degree. C.
to 110.degree. C. until there was no change in weight. The
absorption rate was calculated by Equation below by measuring the
weight of the fiber (fiber prior to drying) allowed to stand at
room temperature for 24 hours and the weight of the dried
fibers.
[0114] Absorption rate (%)=(Weight of fiber before drying-weight of
dried fiber)/weight of dried fiber*100
Example 1
Preparation of Polyester Resin and Polyester Fiber
[0115] 3284 g (19.7 mol) of terephthalic acid, 1067 g (17.2 mol) of
ethylene glycol, 347 g (2.3 mol) of isosorbide, and 42 g (0.4 mol)
of diethylene glycol were added to a 10 L reactor equipped with a
column and a water-cooled condenser. 1.0 g of GeO.sub.2 as a
catalyst, 1.46 g of phosphoric acid as a stabilizer and 0.7 g of
cobalt acetate as a coloring agent were used. Then, nitrogen was
injected into the reactor to create a pressurized state in which
the pressure of the reactor was higher than the atmospheric
pressure by 1.0 kgf/cm.sup.2 (absolute pressure: 1495.6 mmHg).
[0116] Then, the temperature of the reactor was raised to
220.degree. C. for 90 minutes, maintained at 220.degree. C. for 2
hours, and then raised to 260.degree. C. for 2 hours. Thereafter,
the mixture in the reactor was observed with the naked eye, and the
esterification reaction was carried out while maintaining the
temperature of the reactor at 260.degree. C. until the mixture
became transparent. During this process, 650 g of by-products were
discharged through the column and the condenser.
[0117] When the esterification reaction was completed, the pressure
in the reactor was reduced to normal pressure by discharging
nitrogen in the pressurized reactor to the outside. Then, the
mixture in the reactor was transferred to a 7 L reactor capable of
performing a vacuum reaction.
[0118] The pressure of the reactor was reduced to 5 Torr (absolute
pressure: 5 mmHg) at normal pressure for 30 minutes, and
simultaneously the temperature of the reactor was raised to
280.degree. C. for 1 hour, and the polycondensation reaction was
carried out while maintaining the pressure of the reactor at 1 Torr
(absolute pressure: 1 mmHg) or less. The polycondensation reaction
was carried out until the intrinsic viscosity (IV) of the mixture
(melt) in the reactor reached 0.61 dl/g. When the intrinsic
viscosity of the mixture in the reactor reached a desired level,
the mixture was discharged to the outside of the reactor and
stranded, then it was solidified with a cooling liquid and
granulated so that the average weight was 12 to 14 mg.
[0119] The particles were allowed to stand at 150.degree. C. for 1
hour and subjected to crystallization, and then added to a 20 L
solid phase polymerization reactor. Thereafter, nitrogen was flowed
into the reactor at a rate of 50 L/min. At this time, the
temperature of the reactor was raised from room temperature to
140.degree. C. at a rate of 40.degree. C./hour, maintained at
140.degree. C. for 3 hours, then raised to 200.degree. C. at a rate
of 40.degree. C./hour and maintained at 200.degree. C. The solid
phase polymerization was carried out until the intrinsic viscosity
(IV) of the particles in the reactor reached 0.98 dl/g.
[0120] The polyester resin thus prepared was melted at about
250.degree. C. to 300.degree. C., then spun and cooled. Then, it
was drawn at a draw ratio of 4 times to prepare a polyester fiber
having a thickness of .PHI. 3.5 mm.
Example 2
Preparation of Polyester Resin and Polyester Fiber
[0121] 3284 g (19.8 mol) of terephthalic acid, 1065 g (18.7 mol) of
ethylene glycol, 231 g (1.6 mol) of isosorbide, and 42 g (0.4 mol)
of diethylene glycol were added to a 10 L reactor equipped with a
column and a water-cooled condenser. 1.0 g of GeO2 as a catalyst,
1.46 g of phosphoric acid as a stabilizer and 0.7 g of cobalt
acetate as a coloring agent were used. Then, nitrogen was injected
into the reactor to create a pressurized state in which the
pressure of the reactor was higher than the atmospheric pressure by
1.0 kgf/cm.sup.2 (absolute pressure: 1495.6 mmHg).
[0122] Then, the temperature of the reactor was raised to
220.degree. C. for 90 minutes, maintained at 220.degree. C. for 2
hours, and then raised to 260.degree. C. for 2 hours. Thereafter,
the mixture in the reactor was observed with the naked eye, and the
esterification reaction was carried out while maintaining the
temperature of the reactor at 260.degree. C. until the mixture
became transparent. During this process, 700 g of by-products were
discharged through the column and the condenser.
[0123] When the esterification reaction was completed, the pressure
in the reactor was reduced to normal pressure by discharging
nitrogen in the pressurized reactor to the outside. Then, the
mixture in the reactor was transferred to a 7 L reactor capable of
performing a vacuum reaction.
[0124] The pressure of the reactor was reduced to 5 Torr (absolute
pressure: 5 mmHg) at normal pressure for 30 minutes, and
simultaneously the temperature of the reactor was raised to
280.degree. C. for 1 hour at the same time, and the
polycondensation reaction was carried out while maintaining the
pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or
less. The polycondensation reaction was carried out until the
intrinsic viscosity (IV) of the mixture (melt) in the reactor
reached 0.6 dl/g. When the intrinsic viscosity of the mixture in
the reactor reached a desired level, the mixture was discharged to
the outside of the reactor and stranded, then it was solidified
with a cooling liquid and granulated so that the average weight was
12 to 14 mg.
[0125] The particles were allowed to stand at 150.degree. C. for 1
hour and subjected to crystallization, and then added to a 20 L
solid phase polymerization reactor. Thereafter, nitrogen was flowed
into the reactor at a rate of 50 L/min. At this time, the
temperature of the reactor was raised from room temperature to
140.degree. C. at a rate of 40.degree. C./hour, maintained at
140.degree. C. for 3 hours, then raised to 200.degree. C. at a rate
of 40.degree. C./hour and maintained at 200.degree. C. The solid
phase polymerization was carried out until the intrinsic viscosity
(IV) of the particles in the reactor reached 0.75 dl/g.
[0126] The polyester resin thus prepared was melted at about
250.degree. C. to 300.degree. C., then spun and cooled. Then, it
was drawn at a draw ratio of 4 times to prepare a polyester fiber
having a thickness of .PHI. 1 0.5 mm.
Example 3
[0127] Preparation of Polyester Resin and Polyester Fiber 3284 g
(19.7 mol) of terephthalic acid, 1067 g (17.2 mol) of ethylene
glycol, 347 g (2.3 mol) of isosorbide, and 63 g (0.6 mol) of
diethylene glycol were added to a 10 L reactor equipped with a
column and a water-cooled condenser. 1.0 g of GeO2 as a catalyst,
1.46 g of phosphoric acid as a stabilizer and 0.7 g of cobalt
acetate as a coloring agent were used. Then, nitrogen was injected
into the reactor to create a pressurized state in which the
pressure of the reactor was higher than the atmospheric pressure by
1.0 kgf/cm.sup.2 (absolute pressure: 1495.6 mmHg).
[0128] Then, the temperature of the reactor was raised to
220.degree. C. for 90 minutes, maintained at 220.degree. C. for 2
hours, and then raised to 260.degree. C. for 2 hours. Thereafter,
the mixture in the reactor was observed with the naked eye, and the
esterification reaction was carried out while maintaining the
temperature of the reactor at 260.degree. C. until the mixture
became transparent. During this process, after confirming that 700
g of by-products were discharged through the column and the
condenser, 221 g (3.5 mol) of ethylene glycol was further added to
the reactor.
[0129] When the esterification reaction was completed, the pressure
in the reactor was reduced to normal pressure by discharging
nitrogen in the pressurized reactor to the outside. Then, the
mixture in the reactor was transferred to a 7 L reactor capable of
performing a vacuum reaction.
[0130] The pressure of the reactor was reduced to 5 Torr (absolute
pressure: 5 mmHg) at normal pressure for 30 minutes, and
simultaneously the temperature of the reactor was raised to
280.degree. C. for 1 hour at the same time, and the
polycondensation reaction was carried out while maintaining the
pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or
less. The polycondensation reaction was carried out until the
intrinsic viscosity (IV) of the mixture (melt) in the reactor
reached 0.55 dl/g. When the intrinsic viscosity of the mixture in
the reactor reached a desired level, the mixture was discharged to
the outside of the reactor and stranded, then it was solidified
with a cooling liquid and granulated so that the average weight was
12 to 14 mg.
[0131] The particles were allowed to stand at 150.degree. C. for 1
hour and subjected to crystallization, and then added to a 20 L
solid phase polymerization reactor. Thereafter, nitrogen was flowed
into the reactor at a rate of 50 L/min. At this time, the
temperature of the reactor was raised from room temperature to
140.degree. C. at a rate of 40.degree. C./hour, maintained at
140.degree. C. for 3 hours, then raised to 200.degree. C. at a rate
of 40.degree. C./hour and maintained at 200.degree. C. The solid
phase polymerization was carried out until the intrinsic viscosity
(IV) of the particles in the reactor reached 0.98 dl/g.
[0132] The polyester resin thus prepared was melted at about
250.degree. C. to 300.degree. C., then spun and cooled. Then, it
was drawn at a draw ratio of 4 times to prepare a polyester fiber
having a thickness of .PHI. 0.5 mm.
Comparative Example 1
Preparation of Polyester Resin and Polyester Fiber
[0133] A polyamide fiber having a thickness of .PHI. 3.5 mm was
prepared in the same manner as in Example 1 except that Nylon
5034MTX1 resin (marketed the company UBE) was used as a polyamide
resin.
Comparative Example 2
Preparation of Polyester Resin and Polyester Fiber
[0134] 2873 g (17.3 mol) of terephthalic acid, 1679 g (27.0 mol) of
ethylene glycol, 329 g (2.3 mol) of isosorbide, and 37 g (0.3 mol)
of diethylene glycol were added to a 10 L reactor equipped with a
column and a water-cooled condenser. 1.0 g of GeO.sub.2 as a
catalyst, 1.46 g of phosphoric acid as a stabilizer and 0.7 g of
cobalt acetate as a coloring agent were used. Then, nitrogen was
injected into the reactor to create a pressurized state in which
the pressure of the reactor was higher than the atmospheric
pressure by 1.0 kgf/cm.sup.2 (absolute pressure: 1495.6 mmHg).
[0135] Then, the temperature of the reactor was raised to
220.degree. C. for 90 minutes, maintained at 220.degree. C. for 2
hours, and then raised to 260.degree. C. for 2 hours. Thereafter,
the mixture in the reactor was observed with the naked eye, and the
esterification reaction was carried out while maintaining the
temperature of the reactor at 260.degree. C. until the mixture
became transparent. During this process, 750 g of by-products were
discharged through the column and the condenser.
[0136] When the esterification reaction was completed, the pressure
in the reactor was reduced to normal pressure by discharging
nitrogen in the pressurized reactor to the outside. Then, the
mixture in the reactor was transferred to a 7 L reactor capable of
performing a vacuum reaction.
[0137] The pressure of the reactor was reduced to 5 Torr (absolute
pressure: 5 mmHg) at normal pressure for 30 minutes, and
simultaneously the temperature of the reactor was raised to
280.degree. C. for 1 hour at the same time, and the
polycondensation reaction was carried out while maintaining the
pressure of the reactor at 1 Torr (absolute pressure: 1 mmHg) or
less. The polycondensation reaction was carried out until the
intrinsic viscosity (IV) of the mixture (melt) in the reactor
reached 0.4 dl/g. When the intrinsic viscosity of the mixture in
the reactor reached a desired level, the mixture was discharged to
the outside of the reactor and stranded, then it was solidified
with a cooling liquid and granulated so that the average weight was
12 to 14 mg.
[0138] The polyester resin thus prepared was melted at about
250.degree. C. to 300.degree. C., then spun and cooled. Then, it
was drawn at a draw ratio of 4 times to prepare a polyester fiber
having a thickness of .PHI. 1.0 mm.
Examples 4 to 6, Comparative Examples 3 and 4
Preparation of Polyester Resin and Polyester Fiber
[0139] First, in Examples 4 to 6 and Comparative Example 3, the
initial input molar ratio of the dicarboxylic acid or a derivative
thereof to the diol was controlled in the same manner as in Example
1, and in Comparative Example 4, the initial input molar ratio of
the dicarboxylic acid or derivative to the diol was controlled in
the same manner as in Comparative Example 2.
[0140] In addition, the polyester resins and polyester fibers were
prepared in the same manner as in Example 1 for rest of the
conditions, except that by controlling the total amount of ethylene
glycol, isosorbide and diethylene glycol, the amount of the diol
moieties derived from isosorbide and diethylene glycol introduced
into the polyester resin was controlled as shown in Table 1 below,
and that the desired intrinsic viscosity for other polycondensation
reactions and solid phase polymerization reactions and fiber
thickness were adjusted as shown in Table 1.
Experimental Example
Evaluation of Polyester Fibers
[0141] The preparation conditions and physical properties of the
polyester resins prepared in Examples 1 to 6 and Comparative
Examples 1 to 4 were evaluated according to the methods described
above, and the results are shown in Table 1.
TABLE-US-00001 TABLE 1 Examples Comparative Examples 1 2 3 4 5 6 1
2 3 4 ISB content 9 5 9 9 15 20 0 9 0 35 [mol %] DEG content 2 2 3
2 3 5 -- 1 -- 5 [mol %] Intrinsic 0.61 0.6 0.55 0.45 0.70 0.65 --
0.40 0.70 0.75 viscosity (poly- condensation) [dl/g] Intrinsic 0.98
0.75 0.98 0.85 0.75 0.70 -- 0.40 1.00 0.75 viscosity solid-state
polymerization [dl/g] Tg 90 82.5 90 90 95 104 20 90 78 130
[.degree. C.] (50% RH) Fiber thickness 3.5 0.5 0.5 1.0 3.5 1.0 3.5
1.0 3.5 0.5 [diameter (.PHI.): mm] Oligomer 0.5 0.7 0.5 0.6 0.7 0.9
6.1 1.4 1.6 0.9 [wt %] Density 1.38 1.38 1.38 1.38 1.38 1.38 1.14
1.38 1.38 1.38 [g/m.sup.3] Elongation 26 45 33 38 19 15 25 10 22 --
[%] Tensile 4.0 4.3 4.5 4.2 3.4 3.2 4.4 1.6 4.1 -- strength [g/d]
Knot strength 2.9 3.0 3.3 3.2 2.3 2.1 1.8 0.3 2.3 -- [g/d] Knot
strength 72 70 73 75 68 65 40 20 55 -- retention rate [%] Saline
water 102 99 100 100 100 105 68 40 99 -- resistance [%] Chemical 90
87 89 90 91 91 81 45 62 -- resistance (NaOH 20%) [%] Chemical 93 88
91 93 92 94 80 57 62 -- resistance (KOH 20%) [%] Light 89 90 89 90
90 90 83 30 55 -- resistance [%] Haze 1.2 0.7 1.1 1.0 0.8 0.7 8.0
0.7 6.5 0.6 [%] Absorption 0.76 0.65 0.76 0.75 0.72 0.70 5.10 0.72
0.70 0.75 rate [%] ISB content: The molar ratio of the residue
derived from isosorbide relative to the residue derived from total
diols included in the polyester resin DEG content: The molar ratio
of the residue derived from diethylene glycol relative to the
residue derived from total diols included in the polyester resin
Tg: Tg of the polyester resin
[0142] Referring to Examples 1 and 5 and Comparative Examples 1 and
3, it is confirmed that the fibers have the same thickness but
exhibit different physical properties. Specifically, it is
confirmed that the nylon 6 fiber of Comparative Example 1 prepared
from the polyamide resin had a high initial tensile strength but
had a low knot strength, a low knot strength retention ratio and a
high absorption rate, and the strength retention ratio was rapidly
deteriorated (poor saline water resistance) when exposed to a
saline water. Further, it is confirmed that the polyester fiber of
Comparative Example 3 prepared from polyethylene terephthalate had
high regularity of the polymer chain, which led to the occurrence
of haze after molding, and was susceptible to alkaline solution
(poor chemical resistance). In contrast, the polyester resins of
Examples 1 and 5 were found to have excellent haze, knot strength
retention rate, saline water resistance, chemical resistance and
light resistance due to a low oligomer content.
[0143] Referring to Example 2 and Comparative Example 4, the final
intrinsic viscosity of the polyester resins and the thickness of
the fibers were the same, but when the content of isosorbide
introduced into the polyester resin exceeded 20 mol % as in
Comparative Example 4, an alignment by drawing did not occur. As a
result, fibers could not be formed at a draw ratio of 3 times or
more from the polyester resin of Comparative Example 4, and the
properties described in Experimental Example could not be
evaluated.
[0144] Referring to Example 4 and Comparative Example 2, even when
isosorbide was introduced in the same amount into the polyester
resins, the final intrinsic viscosity of the polyester resins
varied, since the initial input molar ratio of the diol was outside
the appropriate range, and the content of diethylene glycol was
outside the appropriate range. As a result, it was confirmed that
the mechanical properties of Comparative Example 2 were
insufficient.
[0145] Accordingly, it is confirmed that in order to provide
polyester fibers which exhibits excellent saline water resistance,
chemical resistance, light resistance and a good knot strength and
which can maintain high transparency, the polyester fibers should
be prepared under a specific processing condition, for example, the
initial input/mixing ratio of the diol must be adjusted within an
appropriate range, the content of the diol moiety derived from
isosorbide and the diol moiety derived from diethylene glycol
introduced into the polyester resin must satisfy a specific range,
the oligomer content of the polyester resin should be 1.3% by
weight, and the haze measured according to ASTM D1003-97 for the
specimen having a thickness of 6 mm obtained from the resin should
be less than 3%.
[0146] It is confirmed that the polyester fiber according to the
one embodiment of the present invention exhibits excellent
characteristics described above and thus can be effectively used
for fishing guts, fishing nets, pelt for paper machines, ropes, gut
for rackets, carpets, rugs, mats, clothes, 3D printers, etc.
* * * * *