U.S. patent application number 11/047683 was filed with the patent office on 2006-05-11 for method for producing cellulose fiber.
This patent application is currently assigned to HYOSUNG Corporation. Invention is credited to Soo-Myung Choi, Ik-Hyun Kwon, Tae-Jung Lee.
Application Number | 20060099419 11/047683 |
Document ID | / |
Family ID | 35883446 |
Filed Date | 2006-05-11 |
United States Patent
Application |
20060099419 |
Kind Code |
A1 |
Kwon; Ik-Hyun ; et
al. |
May 11, 2006 |
Method for producing cellulose fiber
Abstract
There is provided with a cellulose fiber suitable for industrial
material which is produced by a process comprising following steps:
producing NMMO solution made in a manner to dissolve 0.1 wt % to 10
wt % of salt and polyvinyl alcohol in concentrated N-Methyl
Morpholine N-oxide (NMMO) in liquid state; producing cellulose
solution in a manner that said NMMO solution is mixed with
cellulose powder and then said cellulose powder is swelled to
produce cellulose solution; obtaining multifilament by solidifying
said cellulose solution reached at a coagulation bath through air
layer after extruded-sprayed with spraying nozzle having orifices
of 500 to 2000; and winding said multifilament for storing after in
turn washing, drying and treating with organic solvent, and the
cellulose fiber according to the present invention is suitable for
industrial materials due to excellent mechanical strength. In
addition, it is possible to obtain cellulose fiber by adding salts
to concentrated NMMO in liquid state, in which micro-fibril is well
oriented in direction of the fiber-axis making cellulose
multifilament have excellent mechanical strength and excellent
stability of morphology with lower shrinkage at high temperature.
Furthermore, the cellulose fiber according to the present invention
has a good fibrillation-resistance and excellent adhesion to rubber
by using polyvinyl alcohol when used for tire-cord.
Inventors: |
Kwon; Ik-Hyun; (Kyonggi-do,
KR) ; Choi; Soo-Myung; (Kyonggi-do, KR) ; Lee;
Tae-Jung; (Kyonggi-do, KR) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
HYOSUNG Corporation
Kyonggi-do
KR
|
Family ID: |
35883446 |
Appl. No.: |
11/047683 |
Filed: |
February 2, 2005 |
Current U.S.
Class: |
428/375 |
Current CPC
Class: |
Y10T 428/2933 20150115;
D01F 2/00 20130101; B82Y 30/00 20130101; C08B 1/003 20130101 |
Class at
Publication: |
428/375 |
International
Class: |
D02G 3/00 20060101
D02G003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 10, 2004 |
KR |
10-2004-0091201 |
Claims
1. Cellulose fibers produced by a method comprising the steps of:
(A) preparing a NMMO solution by dissolving 0.1 wt % to 10 wt % of
salt and polyvinyl alcohol into a concentrated NMMO in liquid
state; (B) preparing a cellulose solution by mixing a cellulose
powder with said NMMO solution, swelling and dissolving the said
cellulose powder; (C) obtaining a multi-filament by spinning said
cellulose solution through a spinning nozzle with 500 to 2000 of
orifices, making said cellulose reach a coagulation bath through a
air layer and then solidifying said cellulose solution; and (D)
winding said multi-filament after water-washing, drying and
finishing oil; wherein said multi-filament has physical properties
as following: (1) 700 to 3000 in total denier of the
multi-filament, (2) 5 to 11 g/d in dried tenacity, (3) 4 to 12% in
elongation, (4) 0.5 to 4.0% in elongation at specific load, (5) 200
to 400 g/d in modulus and (6) -0.5 to 3% in shrinkage.
2. The cellulose fibers according to claim 1, characterized in that
in step (A) the proportion of said salt and polyvinyl alcohol is
90:10 to 10:90 by weight.
3. The cellulose fibers according to claim 1, characterized in that
in step (A) said salt is a bivalent anion such as calcium chloride,
ammonium chloride, calcium carbonate, calcium sulfate, sulfate
magnesium and sulfate zinc.
4. The cellulose fibers according to claim 1, characterized in that
in step (B) an extruder is used for mixing said cellulose powder
with said NMMO solution, swelling and dissolving said cellulose
powder wherein said extruder is a twin-screw extrudes having 8 to
14 of barrels or screw being 24 to 64 in ratio of Length/Diameter
(L/D).
5. The cellulose fibers according to claim 1, characterized in that
the fibrillation index of said cellulose fibers is below 5.
6. The cellulose fibers according to claim 1, characterized in that
in step (A) the degree of polymerization of said polyvinyl alcohol
is 500 to 6000.
7. The cellulose fibers according to claim 1, characterized in that
in step (B) said cellulose powder is mixed with polyethylene,
polyethylene glycol, polymethylmethacrylate and the additives a
agent for dropping viscosity or TiO.sub.2, SiO.sub.2, carbon,
carbon nano-tube, inorganic nano clay.
8. A tire-cord comprising said cellulose fibers according to claim
1.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to cellulose fiber having the
property of excellent adhesion as well as of high strength, high
modulus and low shrinkage, in particular cellulose fiber with
excellent strength and modulus and fibrillation-resistance produced
in a manner that concentrated N-methyl Morpholine N-oxide
(denominated as "NMMO" hereafter) in liquid state is dissolved,
together with salt and polyvinyl alcohol to make a solution, and
then cellulose powder is dissolved into said solution to be swollen
and subsequently the solution with cellulose is sprayed with nozzle
with 500 to 2000 orifices.
[0002] Cellulose has high affinity with other compounds, but
ordinary solvent can not dissolve cellulose owing to crystal
structure formed by inter- or intra-molecular hydrogen bonds,
therefore for dissolution of cellulose special solvent has to be
selected for the structure, and NMMO is used generally for the
purpose. The process for manufacturing cellulose fiber with NMMO
solvent has some advantage that the process may has no detriment to
the environment as all the solvent used in the process may be
recovered for recycling and also fiber and film produced using
cellulose has high mechanical strength, on this account the
cellulose is usually utilized as materials in process for
manufacturing wares and many methods for using cellulose has been
suggested in many literature starting from U.S. Pat. No.
4,142,913.
[0003] U.S. Pat. No. 4,144,080, No. 4,196,282 and No. 4,246,221
suggest a method for producing cellulose fiber, in which cellulose
is swollen into NMMO containing 50 wt % of water, and then water is
extracted using vacuum distillation to produce spinning-solution
which is made into cellulose fiber by extruding.
[0004] In addition, U.S. Pat. No. 4,880,469 describes a method for
enhancing the strength of cellulose filament by adding ammonium
chloride to NMMO solution. According to the method of '469,
cellulose fiber may be obtained by adding ammonium chloride to NMMO
solution with pulp having 5000 degrees of polymerization for
increasing the property of orientation in direction of axis for
micro-fibril, and the resultant has 1.2 Gpa in strength and 5.4% in
shrinkage, but the produced cellulose fiber is not suitable for
industrial use due to the fibrillar stripping phenomenon.
[0005] A solution for the above problem is suggested in Korean
publication no. 1998-700465, and the above invention tells that the
fibrillation-resistance, strength and shrinkage of cellulose fibers
may be enhanced by adjusting the degrees of polymerization,
concentration, the speed of rolling or the tension of filament
without adding salt, but the number of filaments per spinning
nozzle is just 50, thus the resultant of the above method is not
proper for using industrial materials, and also the
fibrillation-resistance is deficient for the fibers of industrial
material.
[0006] Considering the filament for application of the industrial
material is generally made as between 1000 and 2000 denier and the
industrial material consists of hundreds of filament strands, the
cellulose fibers by the above method is not suitable for having
physical and chemical properties required for industrial materials
after twisting and heat treatment with
Resorcinol-Formaldehyde-Latex (RFL) solution. Actually regarding to
spinning of fibers, the adjustment of cooling, drying and washing
condition is difficult on spinning fine denier rather than rough
denier, and so it is not easy to represent physical and chemical
properties above some level and to retain uniformity of each
filament on the whole, and therefore it is difficult to determine
the applicability of fibers as industrial material by checking the
properties of fibers for only 50 strands. And because the spinning
of air layer varies with process stability for adhesion of the
filament discharged from spinning nozzle and the cooling efficiency
depending on increase of the number of filament, a new design that
considers the outer diameter of spinning nozzle, the diameter of
orifice, the length of air layer, the condition for blowing cool
air, the flowing direction of coagulation liquid and the condition
for water-washing and drying depending on spinning speed is
required, and the difference of property results from the
design.
SUMMERY OF THE INVENTION
[0007] The present invention suggests a solution for the problems
of the above inventions, and according to the solution there is
provided with cellulose fibers having higher strength of cellulose
filament as well as stability of morphology due to lower shrinkage
in high temperature by adding concentrated NMMO in liquid
state.
Therefore, it is an object of the present invention to provide
cellulose fibers avoiding effectively fibrillation and having high
adhesion for use of industrial materials by using polyvinyl
alcohol.
[0008] According to a preferred embodiment of the present
invention, a method for producing cellulose fibers comprising the
steps of:
(A) producing NMMO solution by dissolving 0.1 to 10 wt % of salt
and polyvinyl alcohol into concentrated N-Methyl Morpholine N-oxide
(NMMO) in liquid state;
(B) producing cellulose solution by mixing cellulose powder with
said NMMO solution, and then by swelling and dissolving;
(C) yielding multi-filaments by discharging said cellulose solution
into coagulation bath through air layer after spinning through a
nozzle with 500 to 2000 of orifices; and
(D) winding said multi-filaments after water-washing, drying and
finishing oil, and the produced multi-filaments is characterized by
properties as following:
dried strength 5 to 11 g/d; elongation at break 4 to 12%; dried
heat shrinkage -0.5 to 3%; and modulus 200 to 400 g/d.
[0009] In other preferred embodiment, the proportion of salt to
polyvinyl alcohol in (A) may be 90:10 to 10:90.
[0010] In another preferred embodiment, said salt in step (A) may
comprise divalent anions, such as calcium chloride, ammonium
chloride, calcium carbonate, calcium sulfate, sulfate magnesium and
sulfate zinc.
[0011] In a further preferred embodiment, a extruder is used for
mixing said cellulose powder with said NMMO solution, swelling and
dissolving the mixed solution, wherein the extruder may be a
twin-screw extruder having 8 to 14 barrels and being 24 to 64 in
Length/Diameter (L/D) of screw.
[0012] In a still further preferred embodiment, index of
fibrillation of said cellulose fibers preferably is below 5.
[0013] In a still further preferred embodiment, degree of
polymerization of polyvinyl alcohol in step (A) may be 500 to
6000.
[0014] In a still further preferred embodiment, said cellulose
powder in step (B) may be used with other high molecular weight
substance mixed.
[0015] In a still further preferred embodiment, there is provided
with a tire-cord containing said cellulose fibers.
DETAILED DESCRIPTION OF THE INVENTION
[0016] The present invention will be described in detail using
preferred embodiments in the following, not to limit the scope of
the present invention.
[0017] Cellulose used in following examples may be granulized
micro-particles in size of diameter less than 500 .mu.m, and
preferably 300 .mu.m using a crusher with knife bars, such as V-81
Pulp available from Buckeye Cooperate, USA. If the size of particle
above 500 .mu.m, then it is difficult to disperse and swell
uniformly within the extruder. The core of the present invention is
to add salt and polyvinyl alcohol to the concentrated NMMO in
liquid state. In such case, the proportion of salt to polyvinyl
alcohol is 90:10 to 10:90, and preferably 90:10 to 50:50. If the
proportion of the salt to polyvinyl alcohol is above 90 wt %, then
exfoliation of fibril resulting from salt is significant, on the
other hand if below 10 wt %, then enhancement of strength resulting
from salt is slight. And the total weight of salt and polyvinyl
alcohol may be preferably 0.1 to 10 wt % to that of the
concentrated NMMO in liquid state. In such case, if the total
weight of salt and polyvinyl alcohol is below 0.1 wt %, then salt
and polyvinyl alcohol cannot contribute to enhancement of physical
properties such as strength, modulus, shrinkage, on the other hand
if above 10 wt %, then the viscosity of NMMO solution increases to
result in lowering the solubility of cellulose. And also, divalent
salts such as calcium chloride, ammonium chloride, calcium
carbonate, calcium sulfate, sulfate magnesium and sulfate zinc, and
preferably calcium chloride and ammonium chloride may be used to be
added to the concentrated NMMO in liquid state. Polyvinyl alcohol
used in following examples for adding to the concentrated NMMO in
liquid state is in the size of particles less than 500 .mu.m and as
99.9% of degree of substitution, and which is available from Peking
Organic Chemical Company, and the degree of polymerization of
polyvinyl alcohol is 500 to 6000, preferably 1000 to 4000. In such
case, if the degree of polymerization is below 500, then polyvinyl
alcohol may affect slightly the property of cellulose fibers, and
if above 6000, then the solubility of NMMO and cellulose is
lowered. In the meanwhile, NMMO solution with 50 wt % concentration
may be concentrated in known manner resulting in concentrated NMMO
in liquid state with 10 wt % to 20 wt % of moisture contents. If
NMMO solution is to be concentrated below 10 wt % of moisture
contents, then the cost for concentrating is high, on the other if
above 20 wt % of moisture contents, then the solubility is lowered.
The concentrated NMMO in liquid state and cellulose powder into
which salt and polyvinyl alcohol are dissolved is fed continuously
into an extruder sustained at the temperature of 65 to 105.degree.
C., and then NMMO is mixed, swollen and dissolved to produce
uniform cellulose solution. The NMMO solution in which salt and
polyvinyl alcohol are dissolved in small quantity may be fed by a
gear pump or a screw-type feeder into the extruder, and cellulose
powder is preferably supplied in to the extruder by a screw-type
feeder.
[0018] The contents of cellulose powder contained into cellulose
solution which is mixed, swollen and dissolved into the extruder
amounts 5 wt % to 20 wt %, preferably 9 wt % to 14 wt % compared to
the weight of liquid NMMO depending on the degree of
polymerization. In such case, if the content of cellulose powder is
below 5 wt %, the produced cellulose fibers have not the physical
property as industrial material, on the other hand if above 20 wt
%, it is difficult to dissolve cellulose powder with NMMO solution
and thereby the homogenized solution is not easily produced.
[0019] And also the extruder which is used for producing the
swollen and homogenized solution with addition NMMO in step (B) may
preferably be a twin-screw extruder, and the twin-screw extruder
may preferably have 8 to 14 of barrels or screws for which the
value of length/diameter (L/D) is 24 to 64. If the number of
barrels below 8 or the value of L/D is below 24, then the time in
which the cellulose solution passes the barrels is too short to
swell and dissolve the cellulose powder remaining with a large
quantity of the cellulose powder insoluble, on the other hand if
the number of barrels above 14 or the value of L/D is above 64,
then the cost for manufacturing the extruder is too high to be
available commercially and also the screws of the extruder may be
overloaded. The cellulose powder in step (B) may be used with other
high molecular compounds or additives mixed. The high molecular
compounds may be polyethylene, polyethylene glycol,
polymethylmethacrylate and the like, and the additives may be agent
for dropping viscosity or TiO.sub.2, SiO.sub.2, carbon, carbon
nano-tube, inorganic nano clay and the like.
[0020] Describing more specifically the step (C) corresponding to
the spinning process, the spinning solution is spun through the
spinning nozzles including a plurality of orifices spaced each
other in distance of 0.5 to 5.0 mm in which each orifice is 100 to
300 .mu.m in diameter and 200 to 2400 .mu.m in length, and the
value of L/D is 2 to 8, and then the spinning solution reach a
coagulation bath through air layer to produce multi-filaments after
coagulation.
[0021] The type of spinning nozzles may be circular in general, and
the diameter of nozzle may be 50 to 200 mm, preferably 80 to 150
mm. If the diameter of nozzle below 50 mm, then the distance
between the orifices is too short to cool efficiently and thereby
adhesion may happen before the discharged solution is solidified,
on the other hand the diameter of nozzle is too large, then the
peripheral devices such as pack for spinning and nozzle are too big
resulting in disadvantage in view of equipment. And also if the
diameter of nozzle orifice is below 100 .mu.m or above 300 .mu.m,
then the spinnability may be generated as broken filaments. If the
length of nozzle orifice is below 200 .mu.m, then the physical
property is worse because the orientation of solution is poor, on
the other hand if above 2400 .mu.m, then the cost for manufacturing
the nozzle orifice is too high.
[0022] The cellulose according to the present invention is suitable
for industrial materials, and preferably for the filaments of
tire-cord in view of use, and therefore the number of orifices may
be 500 to 2000, preferably 700 to 1500.
[0023] In a preferred embodiment of the present invention, the
spinning nozzle may include orifices as many as mentioned in the
above, in which each orifice is subject to the above mentioned
conditions. If the number of orifices is below 500, the coagulation
and washing processes can not be implemented completely because the
fineness of each filament is too high to discharge NMMO. On the
other hand if the number of orifices is above 2000, then the number
of filaments for spinning in the nozzle is too large to prevent a
filament from folding adjacent filament within air layer, and
thereby the stability of each filament is reduced after spinning,
which cause some problems to be happen in twisting process and heat
treatment with RFL solution for using as tire-cord as well as the
physical properties of filaments to be degenerated.
[0024] When the spinning solution is in course of coagulation in
the coagulation bath after passing the air layer, if the diameter
of filament is too large, then it is difficult to produce fibers
having close and homogenous structure owing to the difference of
rate of coagulation between inner and outer part. Therefore, fibers
spun with a suitable air layer be keeping may be immersed into the
coagulation liquid with more homogenous diameter on spinning the
cellulose solution, if the magnitude of discharge is same. An air
layer having too short length prevents filaments from increasing
the degree of orientation due to increse in the incidence
proportion of pores during solidifying the filaments and removing
the solvent, while one having too long length makes it difficult to
keep the stability of process due to heavy effect of the adhesion
of filaments, ambient temperature and humidity.
[0025] An air layer may be 10 to 200 mm, and preferably 20 to 100
mm. When the filaments pass through the air layer, cooling air is
supplied for avoiding adhesion as coagulation and for increasing
permeation-resistance to the coagulation solution, and a sensor may
be installed for detecting ambient atmosphere between an inlet of a
device for supplying cooling air and filaments to monitor and
adjust temperature and humidity. In general the temperature of
supplied air may be kept in 5 to 30.degree. C. If the temperature
is below 5.degree. C., then the solidification of filaments may be
accelerated and thereby the high speed spinning is difficult and
the expense is too high due to supplying cooling air, on the other
hand if above 30.degree. C., broken filaments may be happen due to
lower cooling effect of the discharging solution. Because the
content of moisture is an important factor to affect the process of
coagulation, the relative humidity within the air layer should be
adjusted between RH10% and RH50%. More specifically, for enhancing
the stability in view of coagulation speed of filaments and melted
adhesion on the surface of the spinning nozzle, RH10% to RH30% of
dried air adjacent the nozzle and RH30% to 50% of wet air adjacent
the solidification solution are suitable. The cooling air may be
preferably blown horizontally to the side of filaments discharged
perpendicularly, and air velocity is advantageously between 0.5 and
10 m/s, and preferably 1 to 7 m/sec for stability. If air velocity
is too low, the cooling air is not superior to the condition of
other ambient atmosphere adjacent to filaments and thereby the
difference of solidification owing to contact of the cooling air on
filaments and severance of filaments may be caused resulting in
difficulty with manufacture, on the other hand if too high, then
the filaments may run the risk of adhesion owing to agitation of
the routine of filaments and the spinnability may be impaired owing
to the hindrance of homogeneous flow.
[0026] The proportion of NMMO solution in the coagulation solution
according to the present invention may be between 5 and 40 wt %. If
the filament passes through the coagulation bath with the spinning
speed above 50 m/min, the solution in the coagulation bath may be
agitated heavily owing to the friction between the filaments and
the solidifying solution. Because the above phenomenon may impair
the stability of process in enhancing the productivity with
excellent physical property by the orientation of elongation and
increase of spinning speed, it is necessary to minimize the above
phenomenon with a design considering the size and shape of the
coagulation bath and the magnitude and flow of solution.
[0027] In step (D) according to the present invention, the produced
filaments are introduced into a washing bath for washing. Because
the remove of solvent and orientation are implemented
simultaneously when the filaments pass the coagulation bath, it is
necessary to keep the temperature and concentration of solution in
bath constant. After passing the bath, the filament should be
washed in the washing bath. The method for washing may be performed
in a known manner.
[0028] After being washed, the filaments are dried and treated
using finishing oil to be wounded. The processes for drying,
finishing oil and winding may be performed in a known manner. The
cellulose with high strength may be produced through the above
processes.
[0029] The multi-filaments in according to the present invention
may be a lyocell multi-filaments having the property such as 700 to
3000 in range of total denier, 7.0 to 25.0 kg in load for breaking.
The multi-filaments may comprise 500 to 2000 of filaments, and the
fineness of each filament is between 0.5 and 4.0 denier. And the
physical property of the multi-filaments is 5.0 to 11.0 g/d in
strength; 4.0 to 12% in elongation; 0.5 to 4.0% in elongation
(elongation at specific load) at 4.5 kg or 6.8 kg of load; 200 to
400 g/d in modulus, 0.0030 to 0.060 in birefringence; -0.5 to 3% in
shrinkage, therefore the multi-filaments of the present invention
may be advantageously used as industrial materials, particularly
tire-cord for vehicles.
[0030] In below the present invention will be described in detail
using examples that doesn't limit the scope of the present
invention, and in the examples the bases for measuring and
estimating physical properties are as followings.
(a) Degree of Polymerization (DPw)
[0031] The intrinsic viscosity [IV] of the dissolved cellulose was
measured using 0.5M cupriethylenedianine hydroxide solution
obtained according to ASTM D539-51T in the range of 0.1 to 0.6 g/dl
of concentration at 25.+-.0.01.degree. C. with Uberod viscometer.
The intrinsic viscosity was calculated from the specific viscosity
using extrapolation method according to the concentration and then
the value obtained in the above was substituted into Mark-Houwink's
equation to obtain the degree of polymerization.
[IV]=0.98*10.sup.-2DP.sub.W.sup.0.9. (b) The Tenacity (g/d),
Elongation (%), Modulus (g/d) and Elongation at Specific Load (%)
of the Multi-Filaments
[0032] The above values were measured immediately after dried with
a heat wind dryer for 2 hours at temperature of 107.degree. C. The
measurement was performed with a low-speed elongating tensile
tester from Instron LTD., USA and the conditions of measurement are
as following:
80 Tpm (80 turns twist/m); 250 mm in gauge length; 300 m/mm at
speed of elongation.
[0033] The modulus may be described as the gradient of load for
elongating up to a certain level, and in a tensile test it means
gradient on a curve of elongation-load.
[0034] An elongation at specific load means elongation at a point
of the curve that the load is 4.5 kg (in case of 1500 denier of
filament) or 6.8 kg (in case of 2000 denier of filament), and it
indicates that less the intermediate elongation is, more large the
modulus is and less deformed the filament is.
(c) Heat Shrinkage (%)
[0035] A sample for measurement remained for 24 hours, at
25.degree. C. of temperature and 65% RH, and then the heat
shrinkage was measured using the ratio of L.sub.1 to L.sub.0
wherein L.sub.1 was obtained by measuring the length of the sample
in 0.05 g of load weight per denier and L.sub.0 was measured the
sample in 0.05 g of load weight per denier after treating for 30
minutes at 150.degree. C. of temperature with a dryer.
The heat shrinkage is calculated as following: Heat shrinkage
(%)=[(L.sub.0-L.sub.1)/L.sub.0]*100. (d) The Estimation of
Fibrillation
[0036] The fibrillation index (F.I.) of cellulose fibers produced
in according to the present invention was estimated as following.
For generating the fibrillation purposely, 50 multi-filaments in 10
mm of length were input into an Erlenmeyer flask (narrow neck)
containing 250 ml of water at 25.degree. C. of temperature and then
10 stainless metal balls with 5 mm of diameter were rotated at 10
rpm for 30 minutes with a magnetic mixer (40 L*10 mm.PHI. of
magnetic bar), and then the fibrillation index (F.I.) was estimated
with an optical microscope after drying.
[0037] The samples of multi-filaments were arranged in according to
the increase of fibrillation.
[0038] The length of base filament was measured from each sample,
the number of fibrils was counted, the length of each fibril was
measured, the length of average fibril was produced, and then each
fiber was allotted a value obtained by multiplying the length of
average fibril by the number of fibrils. A fiber having the highest
value corresponds to the highest fibril-fiber, and therefore the
highest fibril-fiber may be given 10 as fibrillation index and
non-fibril fiber may be given 0 as fibrillation for comparing, and
thereby the reaming each fiber may given a suitable index according
to the degree of fibrillation within 0 to 10. Each sample was given
the corresponding index in the above manner.
(e) The Force of Adhesion
[0039] The adhesion with a rubber was estimated using ASTM D4776-98
method based on H-Test. The cellulose filaments were elongated to
be made into raw cord, and then the produced raw cord was immersed
into RFL solution for use of general cellulose solution, and
consequently was treated with heat to produced as dip-cord, and
then the produced dip-cord was attached to a rubber for H-test
sample, and the force of adhesion was estimated using the H-test
sample.
EXAMPLE 1
[0040] Salt (calcium chloride) and polyvinyl alcohol with 2000 of
average DPw were dissolved in NMMO in which the total contents of
salt (calcium chloride) and polyvinyl alcohol to NMMO was 2 wt %
and the proportion of each salt and polyvinyl alcohol was 90:10,
70:30, 50:50, respectively in each solution.
[0041] The NMMO solution containing the above amount of salt and
poly vinyl alcohol was fed into a twin-screwed extruder having
78.degree. C. of inner temperature at 6900 g/h with a gear pump.
And then cellulose powder being below 200 .mu.m diameter and 5% in
moisture content was produced using cellulose sheet (V-81 from
Buckeye LTD.) with a crusher having 250 .mu.m-micro-filter, and
then the cellulose powder was fed into the extruder with a
screwed-supplying device at 853 g/h, and then was swollen
sufficiently within the extruder using the NMMO solution containing
salt and poly vinyl alcohol in swelling area at 8 to 10 minutes of
retention time, and in the solution section of the extruder the
temperature of each section was kept between 90 and 95.degree. C.,
and then the swollen cellulose powder was dissolved to be made into
a solution for spinning with the screw operated at 200 rpm, and
then the solution was discharged through a nozzle with 1000
orifices with the size of 150 .mu.m in diameter. The cellulose
concentration of the discharged solution was 11 wt %, and the
solution was homogeneous with some no dissolved cellulose power
remaining and the degree of polymerization was 960. The discharged
solution was made into multi-filaments to be wound after
coagulation, water-washing, drying and finishing oil, and the
fineness of the resultant multi-filaments was adjusted as 1500
denier. The summary of Example 1 is shown as Table 1 in the
following. TABLE-US-00001 TABLE 1 Example 1 Comparison 1 1-1 1-2
1-3 1-1 1-2 Content rate of salt:PVA 90:10 70:30 50:50 No use 100:0
Tenacity of filaments (g/d) 9.0 8.5 7.9 7.5 9.1 Elongation at
specific load (%) 0.5 0.6 0.7 10.0 0.5 Elongation at Break (%) 4.5
4.9 5.3 7.0 6.4 Modulus (g/d) 370 335 310 280 372 Heat shrinkage
(%) 0.0 0.0 0.0 0.3 0.0 Fibrillation index 1 1 1 1 1 Force of
adhesion 14.7 14.8 15.2 13.3 13.5
EXAMPLE 2
[0042] Salt (calcium chloride) and polyvinyl alcohol with 2000
degree of polymerization was dissolved in to NMMO solution wherein
the proportion of salt and polyvinyl alcohol is 50:50 by weight and
the total contents of salt and polyvinyl alcohol to the NMMO
solution were 0.5, 3, 5 and 8 wt %. Hereafter cellulose filaments
were produced in similar manner to example 1. The summary of
example 2 is shown as Table 2 in the following. TABLE-US-00002
TABLE 2 Example 2 2-1 2-2 2-3 2-4 Rate of (Salt + PVA) to 0.5 3 5 8
NMMO solution (wt %) Tenacity of filaments (g/d) 7.7 7.9 8.3 6.5
Elongation at specific load (%) 0.7 0.7 0.6 0.7 Elongation at Break
(%) 4.8 4.7 4.5 4.9 Modulus (g/d) 310 310 330 290 Heat shrinkage
(%) 0.0 0.0 0.0 0.0 Fibrillation index 1 1 1 1 Force of adhesion
14.7 15.2 16.1 14.0
EXAMPLE 3
[0043] Compared to example 1, the total contents of salt (calcium
chloride) and polyvinyl alcohol was changed into 2 wt % to the NMMO
solution, the proportion of salt and polyvinyl alcohol was adjusted
as 80:20, and the number of orifices in the nozzle was replaced
with 700, 1000 and 1500, respectively. The fineness of resultant
filaments was adjusted as 1500.
[0044] The summary of example 3 is shown in Table 3 in the
following. TABLE-US-00003 TABLE 3 Example 3 Comparison 2 3-1 3-2
3-3 2-1 2-2 The number of orifices 700 1000 1500 450 2200 Tenacity
of filaments (g/d) 9.0 8.5 7.9 4.5 4.1 Elongation at specific 0.5
0.6 0.7 2.7 3.0 load (%) Elongation at Break (%) 4.5 4.6 4.7 5.5
6.0 Modulus (g/d) 370 335 310 170 178 Heat shrinkage (%) 0.0 0.0
0.0 2.3 2.7 Fibrillation index 1 1 1 7 6 Force of adhesion 14.7
14.8 15.2 11.3 13.0
Comparison 1-1
[0045] In comparison 1-1 multi-filament was produced in similar to
example 1, except using a solution containing no salt and no
polyvinyl alcohol, only NMMO.
Comparison 1-2
[0046] In comparison 1-2 multi-filament was produced in similar to
example 1, except using a solution containing no polyvinyl alcohol
and only salt and NMMO.
Comparison 2-1
[0047] In comparison 2-1, multi-filament was produced in similar to
example 3, except using a nozzle with 450 orifices.
Comparison 2-2
[0048] In comparison 2-2, multi-filament was produced in similar to
example 3, except using a nozzle with 2200 orifices.
[0049] In cellulose fibers according to the present invention the
micro-fibril of cellulose is made to be orientated to the axis of
fibers, and therefore the produced cellulose has excellent
stability of morphology at high temperature as well as high
strength and modulus, so that the cellulose fibers of the present
invention is suitable for use as industrial material, in particular
tire-cord. Furthermore, the present invention provides the
cellulose fibers having excellent fibrillation-resistance and
adhesion with rubber as polyvinyl alcohol is used for preventing
the fibrillation happening frequently in cellulose fiber with high
strength.
[0050] In particular, the present invention can provide cellulose
fibers having 700 to 3000 denier of fineness which is required for
industrial material, and having advantages such as high strength,
high modulus, low shrinkage, fibrillation-resistance and high
adhesion with rubber.
[0051] While embodiments of the present invention have been
described by way of illustration, it will be apparent that this
invention may be carried out with many modifications, variations
and adaptations without departing from its spirit or exceeding the
scope of the claims.
* * * * *