U.S. patent application number 12/521362 was filed with the patent office on 2011-01-06 for process for producing cellulose multi-filament with lower coefficient of variation of section diameter.
Invention is credited to Jae Shin Choi, Byoung Min Lee, Tae Jung Lee.
Application Number | 20110003148 12/521362 |
Document ID | / |
Family ID | 39572509 |
Filed Date | 2011-01-06 |
United States Patent
Application |
20110003148 |
Kind Code |
A1 |
Lee; Tae Jung ; et
al. |
January 6, 2011 |
PROCESS FOR PRODUCING CELLULOSE MULTI-FILAMENT WITH LOWER
COEFFICIENT OF VARIATION OF SECTION DIAMETER
Abstract
The present invention relates to a cellulose fiber having a
highly homogeneous section, particularly to a cellulose fiber with
lower Coefficient of Variation of section diameter (CV(%)).
Specifically, the present invention relates to a cellulose fiber
wherein Coefficient of Variation of section diameter (CV(%)) of a
mono-filament constituting a multi-filament prepared by dissolving
a cellulose powder in liquid N-methylmorpholine N-oxide
(hereinafter referred to "NMMO") is below 2.5. According to the
present invention, a lyocell multi-filament is produced comprising
the steps of (i) preparing a spinning solution by homogeneously
dispersing, swelling and dissolving cellulose powder in a NMMO
solution; (ii) spinning the spinning solution into an air gap
through a spinning nozzle; and (iii) coagulating the extruded-spun
spinning solution in a coagulation bath. In particular, the
coagulating step is adjusted by means of a coagulation coefficient
in the range of 0.8 to 1.3 and the coagulation coefficient is
expressed as T.sub.D/T.sub.C, T.sub.D=T.sub.D+T.sub.A 90 and
T.sub.D T.sub.A and T.sub.c mean the temperature of a spinning
solution, the temperature of cooling air applied in an air gap and
the temperature of a coagulation bath, respectively.
Inventors: |
Lee; Tae Jung; (Kyonggi-do,
KR) ; Choi; Jae Shin; (Kyonggi-do, KR) ; Lee;
Byoung Min; (Kyonggi-do, KR) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Family ID: |
39572509 |
Appl. No.: |
12/521362 |
Filed: |
December 10, 2007 |
PCT Filed: |
December 10, 2007 |
PCT NO: |
PCT/KR2007/006410 |
371 Date: |
June 26, 2009 |
Current U.S.
Class: |
428/364 ;
264/172.11 |
Current CPC
Class: |
Y10T 428/2913 20150115;
D01F 2/00 20130101 |
Class at
Publication: |
428/364 ;
264/172.11 |
International
Class: |
D02G 3/48 20060101
D02G003/48; D01D 5/38 20060101 D01D005/38 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2006 |
KR |
10-2006-0136132 |
Claims
1. A process for producing a lyocell multi-filament in which the
process includes preparing a spinning solution by homogenously
dispersing, swelling and dissolving cellulose powder in a NMMO
solution; spinning the spinning solution into an air gap through a
spinning nozzle; and coagulating the extruded-spun spinning
solution in a coagulation bath, characterized in that the
coagulating is adjusted by means of a coagulation coefficient in
the range of 0.8 to 1.3 and the coagulation coefficient is
expressed as shown below, coagulation coefficient=T.sub.D/T.sub.c,
T.sub.D=T.sub.D+T.sub.A-90; and T.sub.D, T.sub.A and T.sub.c mean
the temperature of a spinning solution, the temperature of cooling
air applied in an air gap and the temperature of a coagulation
bath, respectively.
2. The process of producing a lyocell multi-filament according to
claim 1, wherein the coagulation coefficient is 1.
3. The process of producing a lyocell multi-filament according to
claim 1, wherein the temperature of the coagulation bath to 15 to
25.degree. C.
4. The process of producing a lyocell multi-filament according to
claim 1, wherein the fineness of lyocell multi-filament is 800 to
3300 denier.
5. The process of producing a lyocell multi-filament according to
claim 1, wherein T.sub.D, T.sub.A, T.sub.D and T.sub.c are 100 to
110.degree. C., 5 to 15.degree. C., 15 to 35.degree. C. and 15 to
35.degree. C., respectively.
6. A lyocell multi-filament for use of tire dip cord produced
according to claim 1 and with following physical properties: 800 to
3300 denier in entire fineness; 0.5 to 2.0 denier in each
monofilament fineness; 6.4 to 8.3 g/d in tenacity of the
multi-filament, 5.7 to 7.1% in breaking elongation, and less than
2.5% in Coefficient of Variation of section diameter (CV(%))
Description
TECHNICAL FIELD
[0001] The present invention relates to a cellulose fiber having a
highly homogeneous section, particularly to a cellulose fiber with
lower Coefficient of Variation of section diameter (CV(%)).
Specifically, the present invention relates to a cellulose fiber
wherein Coefficient of Variation of section diameter (CV(%)) of a
mono-filament constituting a multi-filament prepared by dissolving
a cellulose powder in liquid N-methylmorpholine N-oxide
(hereinafter referred to "NMMO") is below 2.5.
BACKGROUND ART
[0002] A lyocell fiber is made from a spinning solution wherein
cellulose is dissolved in NMMO and it has an advantage of having
high hygroscopicity, dry and wet strength and modulus. Moreover,
unlike viscose rayon, lyocell is recognized as an
environmentally-friendly fiber which does not pollute the
environment with harmful substances. Such a lyocell fiber, as an
alternative of rayon, may be used as a tire-cord and for this
purpose, the homogeneity of a section diameter of a mono-filament
constituting a multi-filament is necessary to accomplish high
strength as a tire-cord material. The homogeneity may be expressed
as Coefficient of Variation of section diameter (CV(%)).
[0003] International Publication No. WO 2001/86043 discloses
lyocell fibers having 6.5% or more in Coefficient of Variation of
section diameter (CV(%)). The invention disclosed in WO 2001/86043,
however, has an object of increasing Coefficient of Variation of
section diameter (CV(%)) and it is not suitable for using as
industrial materials, particularly, for tire-cord because it has
0.7 to 5.0 g/d in strength as shown in examples.
[0004] Referring to other prior invention, U.S. Pat. No. 6,773,648
discloses a lyocell fiber having 6 to 17% in Coefficient of
Variation of section diameter (CV(%)) along fiber and 10 to 22% in
Coefficient of Variation of section diameter (CV(%)) between
fibers. Those of Coefficient of Variation of section diameter along
fiber and between fibers as well, however, are not suitable for
using as a lyocell fiber for tire-cord.
DISCLOSURE OF INVENTION
Technical Problem
[0005] The present invention suggests a method for improving
Coefficient of Variation of section diameter by adjusting the
temperatures of an air gap and a coagulation bath during the
process in order that Coefficient of Variation of section diameter
(CV(%)) of a mono-filament constituting a multi-filament is lowered
below 2.5.
Technical Solution
[0006] It is an object of the present invention to provide a
lyocell fiber for using as a high-strength dip cord for tire-cord
by adjusting the temperatures of cooling air in the air gap and the
coagulation bath and adjusting Coefficient of Variation of section
diameter (CV(%)) of mono-filament constituting a multi-filament to
below 2.5.
ADVANTAGEOUS EFFECTS
[0007] The lyocell fiber according to the present invention may
have suitable properties for using as a dip cord for tire cord.
According to the present invention, the Coefficient of Variation of
section diameter (CV(%)) may be controlled in the desired range by
adjusting coagulation coefficient. Hence, the present invention has
an advantage of producing a lyocell multi-filament for using as a
dip cord for tire-cord.
BEST MODE FOR CARRYING OUT THE INVENTION
[0008] Though processes for producing a lyocell fiber have been
disclosed in many prior arts, a lyocell fiber having different
properties according to each condition of process may be produced.
Particularly, the spinning pressure in a spinning nozzle, the
diameter and the number of orifice, the spinning speed, the
temperature and the air velocity of cooling air in an air gap, and
the temperature, the concentration of a coagulation bath are the
main factors which determine the properties of a lyocell fiber. The
lyocell fiber produced according to the present invention is
prepared by controlling conditions of process and thereby having
suitable properties for tire-cord.
[0009] The properties of the lyocell fiber produced according to
the preset invention are influenced not by the above-described
factors or others independently, but by the correlation between the
factors. The present invention is characterized in that such
factors are controlled to have the correlation.
[0010] The factors which determine the homogeneity of the produced
lyocell fiber may be divided into a cooling condition in an air gap
and a coagulating condition. Therefore, the condition factors may
be expressed as a coagulation coefficient as a result of a
mathematical function of the temperature of the cooling air in the
air gap and the temperature of the coagulation bath, as shown
below.
Coagulation Coefficient=T.sub.D/T.sub.c=0.8 to 1.3
(T.sub.D=T.sub.D+T.sub.A-90)
[0011] T.sub.D means the temperature of a spinning solution,
T.sub.A means the temperature of cooling air applied in an air gap
and T.sub.c means the temperature of a coagulation bath.
[0012] In the process of producing a lyocell fiber according to the
present invention, the coagulation coefficient is adjusted to 0.8
to 1.3. Through the adjustment of the coagulation coefficient, the
spinning solution is cooled and the temperature of the spinning
solution and the temperature of the coagulation bath are adjusted
within a similar temperature range, and then the NMMO contained in
the spinning solution is fed into the coagulation bath and spreads
slowly therein. In doing so, the homogeneity of a mono-filament may
be improved by the lower spreading rate. In order to lower the
spreading rate, coagulation coefficient is adjusted in the range of
0.8 to 1.3. Hereinafter, the process for producing a lyocell fiber
with lower Coefficient of Variation of section diameter (CV(%))
will be described in detail.
[0013] As a raw material of producing a lyocell fiber, a softwood
pulp having 800 to 1200 in degree of polymerization and 93% or more
in the contents of .alpha.-cellulose is pulverized with a crusher
into powder with 500 .mu.m in average diameter. An NMMO solution
having 10 to 20 wt % in the contents of water is prepared. The pulp
powder and the NMMO solution are fed into an extruder at the same
time. And then the cellulose powder is evenly dispersed, swollen
and dissolved in the NMMO solution within the extruder maintained
at the temperature of 90 to 110.degree. C., and then transferred to
the spinning nozzle through the spinning line at the temperature of
90 to 110.degree. C. and thereby the spinning solution is prepared.
The spinning solution is spun through the spinning nozzle into a
filament yarn.
[0014] In the process of producing a lyocell fiber according to the
present invention, the diameter of the spinning nozzle may be 80 to
130 mm. After the diameter of the spinning nozzle is determined,
the number of orifice and the ratio of the length to the diameter
(L/D ratio) of orifice may be determined. The number of orifice may
be 800 to 1200, the diameter of the orifice may be 800 to 2000
.mu.m, and the L/D ratio of the orifice may be 2 to 5. The spinning
solution is extruded-spun into an air gap. The spinning solution is
cooled and solidified in order to draw the spinning solution in the
air gap, wherein the air is blown at lower temperature in the range
of 0 to 25.degree. C.
[0015] The solution after being cooled and solidified in the air
gap is coagulated into a filament yarn in a coagulating solution at
a certain concentration and temperature. The lyocell fiber
according to the present invention is controlled to have a
pre-determined coagulation coefficient in the process of
coagulating and thereby the lyocell fiber may have desired
properties.
[0016] The condition factors may be expressed as a coagulation
coefficient as a result of a mathematical function of the
temperature of cooling air and the temperature of a coagulation
bath, as shown below.
Coagulation
Coefficient=T.sub.D/T.sub.c,T.sub.D=T.sub.D+T.sub.A-90
[0017] T.sub.D means the temperature of a spinning solution,
T.sub.A means the temperature of cooling air applied in an air gap
and T.sub.c means the temperature of a coagulation bath. In the
process of producing a lyocell fiber according to the present
invention, the coagulation coefficient may be 0.8 to 1.3.
[0018] In order to adjust the coagulation coefficient, the
concentration of the coagulation bath is adjusted in order that the
concentration of NMMO is adjusted in the range of 5 to 20 wt %. In
the range of 0.8 to 1.3 of coagulation coefficient, the temperature
of the spinning solution and that of the coagulation bath become
almost similar and the spreading rate of the NMMO contained in the
spinning solution into the coagulation bath goes down as low as it
can be. As a result, the homogeneous coagulation may be
accomplished. Therefore, the section of a mono-filament
constituting the multi-filament becomes very homogeneous and high
strength is accomplished.
[0019] From the lyocell fiber produced according to the
above-mentioned process, a greige cord is prepared and then a dip
cord is prepared. The greige cord is prepared by twisting a certain
number of ply twist yarn and cable twist yarn to two ply of lyocell
fibers. Preferably, the twisting may be carried out at 300/300 TPM
to 500/500 TPM for cable twist/ply twist and the number of ply
twist yarn and cable twist yarn is not necessarily the same. The
greige cord by twisting ply twist yarn and cable twist yarn is then
dipped to a dipping solution. A dip cord for tire is prepared after
a resin layer is attached to the greige cord.
[0020] The lyocell fiber for tire-cord according to the present
invention has 800 to 3300 in denier of the entire fineness and 0.5
to 2.0 in denier of each monofilament fineness. The lyocell fiber
produced by adjusting 0.8 to 1.3 in coagulation coefficient
according to the present invention is characterized with following
physical properties:
[0021] (1) 6.4 to 8.3 g/d in tenacity of the multi-filament,
[0022] (2) 5.7 to 7.1% in breaking elongation, and
[0023] (3) less than 2.5% in Coefficient of Variation of section
diameter (CV(%))
[0024] The dip cord prepared according to the present invention is
characterized with following physical properties:
[0025] (1) 4 to 6 g/d in tenacity,
[0026] (2) 5 to 10% in breaking elongation, and
[0027] (3) 70 to 100% in fatigue resistance
MODE FOR THE INVENTION
[0028] Hereinafter, the present invention will be described in
detail with examples and comparative examples. These examples are
provided only for the illustrative purpose, and it should not be
construed that the scope of the invention is limited thereto.
[0029] According to the examples and comparative examples, the
physical properties of the lyocell multi-filament are evaluated as
following.
[0030] Tenacity (g/d) and Breaking Elongation (%)
[0031] The above-mentioned values were measured immediately after
dried with a heat dryer for 2 hours at temperature of 107.degree.
C. The measurement was performed with a low-speed elongating
tensile strength tester from Instrong LTD., USA and the conditions
of measurement are as following:
[0032] 80 Tpm (80 turns twist/m); 250 mm in length of sample; 300
m/min at speed.
[0033] Coefficient of Variation of Section Diameter (CV(%))
[0034] The above-mentioned value is calculated after each size of
multi-filament and mono-filament is obtained by using a microscope.
Coefficient of Variation of section diameter (CV(%)) is to
determine the degree of relative dispersion and is calculated by
dividing the standard deviation with the average value.
[0035] The physical properties of various lyocell fibers produced
according to coagulation coefficient are shown in Table 1.
[0036] Fatigue Resistance (%)
[0037] Samples were subjected a fatigue test using a Goodrich disc
fatigue tester which is conventionally used for the fatigue test of
tire cords. Then, they were measured for residual strength, and
fatigue resistances were compared. The fatigue test was conducted
under the following conditions: 120.degree. C., 2500 rpm, and 10%
and 18% compression. After the fatigue test, the samples were
dipped in tetrachloroethylene solution for 24 hours to swell
rubber, and then, a cord was separated from the rubber and measured
for residual strength. This residual strength was measured using a
conventional tensile strength tester by the above-described
measurement method (a), after drying at 107.degree. C. for 2
hours.
EXAMPLES
Example 1
[0038] A cellulose solution with 11.5 wt % in concentration was
prepared by using a mixture of pulp powder with 1200 in degree of
polymerization (containing 97% in contents of .alpha.-cellulose),
NMMO.1H.sub.2O and 0.01 wt % propyl gallate. A spinning nozzle that
is 100 mm in diameter and has 1000 orifices with 150 .mu.m in
diameter was used to extrude the cellulose solution. In this case,
the ratio of length to diameter (L/D) of each orifice was 4 in the
spinning nozzle. The solution extruded from the spinning nozzle
(head temperature at 100.degree. C.) was exposed to a cooling air
at 5.degree. C. and 5 msec with 50 mm air gap and then the solution
is spun wherein the amount of the extruded solution and the
spinning speed were adjusted in order that the final filament
fineness is 1000 denier. In this case, the temperature of
coagulating solution was 15.degree. C. in order that the
coagulation coefficient is 1. The concentration of a coagulation
bath was adjusted to 80% in water and 20% in NMMO, and then
water-washed, dried and wound in order to obtain a filament yarn.
Physical properties of the obtained filament are described in Table
1.
Example 2 and 3
[0039] A lyocell multi-filament was prepared by the same process as
example 1, only except for changing the temperature of the cooling
air in the air gap to 10.degree. C. (for example 2) and 15.degree.
C. (for example 3), and the temperature of the coagulation bath to
20.degree. C. (for example 2) and 25.degree. C. (for example 3) in
order that the coagulation coefficient is 1. Physical properties of
the obtained filament are described in Table 1.
Example 4 to 6
[0040] A lyocell multi-filament was prepared by the same process as
example 1, only except for changing the amount of the extruded
solution and the spinning speed in order that the final filament
fineness is 1500 denier. In this case, the temperature of the
coagulating solution is adjusted in order that the coagulation
coefficient is 1. Physical properties of the obtained filament are
described in Table 1.
TABLE-US-00001 TABLE 1 breaking coagulation elongation fineness
T.sub.D T.sub.A T.sub.D' T.sub.c coefficient Tenacity (g/d) (%) CV
(%) Ex. 1 1000 d 100 5 15 15 1 7.3 6.8 0.7 Ex. 2 1000 d 100 10 20
20 1 7.8 7.1 0.9 Ex. 3 1000 d 100 15 25 25 1 8.3 5.9 1.4 Ex. 4 1500
d 110 5 25 25 1 7.0 5.7 2.1 Ex. 5 1500 d 110 10 30 30 1 7.4 6.6 1.7
Ex. 6 1500 d 110 15 35 35 1 6.4 6.1 1.8
COMPARATIVE EXAMPLES
Comparative Example 1 and 2
[0041] A lyocell multi-filament was prepared by the same process as
example 1, only except for changing the temperature of the
coagulation bath to 20.degree. C. (for comp. ex. 1) and 15.degree.
C. (for comp. ex. 2) in order that the coagulation coefficient is
0.75 (for comp. ex. 1) and 1.33 (for comp. ex. 2). Physical
properties of the obtained filament are described in Table 2.
Comparative Example 3 and 4
[0042] A lyocell multi-filament was prepared by the same process as
example 3 and 4, only except for changing the temperature of the
coagulation bath to 10.degree. C. (for comp. ex. 3) and 15.degree.
C. (for comp. ex. 4) in order that the coagulation coefficient is
2.5 (for comp. ex. 3) and 2.0 (for comp. ex. 4). Physical
properties of the obtained filament are described in Table 2.
TABLE-US-00002 TABLE 2 coagulation Tenacity breaking elongation
fineness T.sub.D T.sub.A T.sub.D' T.sub.c coefficient (g/d) (%) CV
(%) Comp. Ex. 1 1000 d 100 5 15 20 0.75 6.3 5.8 2.7 Comp. Ex. 2
1000 d 100 10 20 15 1.33 6.2 6.1 2.9 Comp. Ex. 3 1500 d 110 5 25 10
2.5 6.0 5.7 3.1 Comp. Ex. 4 1500 d 110 10 30 5 2.0 5.4 5.6 2.7
[0043] Referring to Table 1, if the coagulation coefficient is
adjusted to 1, the Coefficient of Variation of section diameter
(CV(%)) decreases. Meanwhile, the coagulation coefficient is more
or less than 1, the Coefficient of Variation of section diameter
(CV(%)) is 2.7 and 2.9 in each comparative example, meaning that
non-homogeneity of the size of mono-filament is increased as shown
in Table 2. At the same time, the tenacity of multi-filament is
reduced and the Coefficient of Variation of section diameter
(CV(%)) is also increased, meaning that the homogeneity of the
mono-filament is reduced. Examples 1 to 6 show the result of the
Coefficient of Variation of section diameter (CV(%)) of lyocell
multi-filament obtained by adjusting coagulation coefficient to 1.
In reality, if the coagulation coefficient is adjusted to 0.8 to 1,
a lyocell multi-filament with 2.5 or less in Coefficient of
Variation of section diameter may be prepared.
INDUSTRIAL APPLICABILITY
[0044] The lyocell fiber according to the present invention may
have suitable properties for using as a dip cord for tire cord. The
Coefficient of Variation of section diameter (CV(%)) of the lyocell
fiber is an important factor to determine the fatigue resistance of
tire-cord. According to the present invention, the Coefficient of
Variation of section diameter (CV(%)) may be controlled in the
desired range by adjusting coagulation coefficient. Hence, the
present invention has an advantage of producing a lyocell
multi-filament for using as a dip cord for tire-cord.
* * * * *