Technical Field
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0002] The present disclosure relates to a lyocell material with controlled whiteness by
hydrogen peroxide treatment and a method of manufacturing same.
Background Art
[0003] In general, cigarette filters include a cellulose acetate tow obtained by extracting
cellulose from wood pulp and acetylating the cellulose.
[0004] Although a photocatalyst (TiO
2) has been added thereto to obtain whiteness of cellulose acetate (CA), it is impossible
to use TiO
2 due to various problems of TiO
2. Because photocatalyst materials capable of replacing TiO
2 have not been developed until now, it is known that a photocatalyst will not be added
to CA.
[0005] In addition, studies have recently been conducted to replace cellulose acetate tows
with eco-friendly materials to protect the natural environment and reduce costs. For
example, the development of tows using lyocell fibers obtained by fiberizing cellulose,
unlike cellulose acetate, is in progress.
[0006] However, it is difficult to realize whiteness (white index of 80 or more and yellow
index of 8 or less) desired by cigarette manufacturers by using tows formed of lyocell
fibers developed to date.
Disclosure
Technical Problem
[0007] Provided are a lyocell material with controlled whiteness by hydrogen peroxide treatment
suitable for a cigarette filter by realizing whiteness equivalent or superior to that
of CA tows treated with a currently used photocatalyst, and a method of manufacturing
the same.
[0008] Provided also are a lyocell material with controlled whiteness by hydrogen peroxide
treatment capable of reducing environmental pollution factors caused by discarded
CA cigarette butts, and a method of manufacturing the same.
Technical Solution
[0009] According to an aspect of the present disclosure, a method of manufacturing a lyocell
material includes: (S1) spinning a lyocell spinning dope including cellulose pulp
and an N-methylmorpholine-N-oxide (NMMO) aqueous solution;
(S2) coagulating the lyocell spinning dope spun in the step (S1) to obtain lyocell
multi-filaments;
(S3) water-washing the obtained lyocell multi-filaments;
(S4) treating the water-washed lyocell multi-filaments with oil and hydrogen peroxide;
(S5) crimping the lyocell multi-filaments treated with oil and hydrogen peroxide in
the step (S4) to obtain a crimped tow; and
(S6) drying the crimped tow,
wherein (S4) includes
a process of treating the water-washed lyocell multi-filaments simultaneously with
oil and hydrogen peroxide in a bath containing a mixed solution of the oil and hydrogen
peroxide with a uniformly maintained concentration, or
a process of treating the water-washed lyocell multi-filaments sequentially in baths
respectively containing a single solution of the hydrogen peroxide, and a single solution
of oil.
[0010] According to an aspect of the present disclosure, a lyocell material includes a crimped
tow formed of lyocell multi-filaments spun from a lyocell spinning dope comprising
cellulose pulp and an N-methylmorpholine-N-oxide (NMMO) aqueous solution, and treated
with oil and bleached with hydrogen peroxide,
wherein the crimped tow includes a lyocell crimped tow including 1000 ppm or less
of hydrogen peroxide and satisfying both a white index of 80 or more and a yellow
index of 8 or less.
[0011] According to an aspect of the present disclosure, a cigarette filter includes the
lyocell material.
[0012] Hereinafter, a lyocell material for a cigarette filter and a method of manufacturing
the same according to embodiments of the present disclosure will be described in detail.
[0013] Before that, technical terms used in the present specification are merely used to
describe particular embodiments, and are not intended to limit the present disclosure,
unless they have clearly different meanings in the context.
[0014] Throughout the specification, an expression used in the singular encompasses the
expression of the plural, unless otherwise indicated.
[0015] As used herein, the term 'include' specifies particular properties, regions, integers,
processes, operations, elements, and/or components and are not intended to preclude
the possibility that one or more other properties, regions, integers, processes, operations,
elements, and/or components thereof may exist or may be added.
[0016] As used herein, the term 'at least one of' or "one or more", when preceding a list
of elements, should be understood to include all possible combinations of the elements.
[0017] Hereinafter, the present disclosure will be described in detail.
Method of Manufacturing Lyocell Material
[0018] According to an embodiment of the present disclosure, a method of manufacturing a
lyocell material includes: (S1) spinning a lyocell spinning dope including cellulose
pulp and an N-methylmorpholine-N-oxide (NMMO) aqueous solution;
(S2) coagulating the lyocell spinning dope spun in the step (S1) to obtain lyocell
multi-filaments;
(S3) water-washing the obtained lyocell multi-filaments;
(S4) treating the water-washed lyocell multi-filaments with oil and hydrogen peroxide;
(S5) crimping the lyocell multi-filaments treated with oil and hydrogen peroxide in
the step (S4) to obtain a crimped tow; and
(S6) drying the crimped tow,
wherein (S4) includes
a process of treating the water-washed lyocell multi-filaments simultaneously with
oil and hydrogen peroxide in a bath containing a mixed solution of the oil and hydrogen
peroxide with a uniformly maintained concentration, or
a process of treating the water-washed lyocell multi-filaments sequentially in separate
baths respectively containing a single solution of hydrogen peroxide and a single
solution of oil.
[0019] In the present disclosure, a lyocell fiber with controlled whiteness by hydrogen
peroxide treatment and a method of manufacturing the same are provided.
[0020] The hydrogen peroxide, as a chemical compound used in a bleaching process of fabrics,
is used to remove pigments and colored impurities in fabrics using oxidation by utilizing
reactive oxygen species.
[0021] In view of these properties, the present disclosure provides a method of realizing
whiteness equivalent or superior to that of currently used CA controlled by adding
a bleaching process using hydrogen peroxide with a concentration in a certain range
to a process of manufacturing a lyocell cigarette filter tow. That is, according to
the present disclosure, whiteness of a tow may be improved in a short time by applying
commonly used hydrogen peroxide to a continuous process of manufacturing a lyocell
cigarette filter tow in a controlled concentration.
[0022] Specifically, the hydrogen peroxide may be used such that a content of hydrogen peroxide
in a solution for treating lyocell multi-filaments is maintained in a concentration
range of 2 wt% to 6 wt% or 3 wt% to 6 wt%.
[0023] In this regard, in the case of using hydrogen peroxide, the concentration should
be controlled in the range of 2 wt% to 6 wt% or 3 wt% to 6 wt% to control a content
of residual hydrogen peroxide in a final tow to be 1000 ppm or less and to improve
whiteness. More specifically, the content of the hydrogen peroxide may be maintained
in the range of 3 wt% to 6 wt% or 4 wt% to 6 wt% to optimize improvement of whiteness.
[0024] As the concentration of the hydrogen peroxide decreases, bleaching reaction of the
lyocell multi-filaments is inactivated making it difficult to realize desired white
index and yellow index. On the contrary, as the concentration of hydrogen peroxide
increases, the content of hydrogen peroxide increases in the multi-filaments to be
out of the optimal range in the final cigarette filter tow, and thus it is difficult
to use the multi-filaments as a cigarette filter material.
[0025] That is, unless the concentration range of hydrogen peroxide of the present disclosure
is satisfied, effects both on improving whiteness and physical properties cannot be
obtained.
[0026] In addition, to realize desired whiteness of the lyocell tow for cigarette filter
in the present disclosure, the filament tow may be treated with hydrogen peroxide
simultaneously during a process of applying oil to the filament tow during the manufacturing
process. Or, optionally, the filament tow may be treated sequentially with a single
solution of hydrogen peroxide and a single solution of oil. In this case, a method
of adding the hydrogen peroxide solution and the oil solution made-up in the concentration
ranges disclosed herein may be used such that the concentrations are uniformly maintained.
More specifically, a white index and a yellow index desired by the industry may be
realized and controlled more effectively by treating the water-washed lyocell multi-filaments
simultaneously with oil and hydrogen peroxide.
[0027] Thus, according to the present disclosure, a cigarette filter tow including a lyocell
with excellent biodegradability may be manufactured, and whiteness desired by cigarette
manufacturers may be realized by adding hydrogen peroxide during a tow manufacturing
process without adding a photocatalyst (TiO
2). Therefore, according to the present disclosure, currently available CA cigarette
butts (filter) may be manufactured by an eco-friendly method compared to conventional
methods.
[0028] Hereinafter, each of the processes of the method of manufacturing a lyocell material
with controlled whiteness by hydrogen peroxide treatment according to the present
disclosure will be described in more detail.
(S1)
[0029] In the present disclosure, the step (S1) is a step of spinning the lyocell spinning
dope including cellulose pulp and an N-methylmorpholine-N-oxide (NMMO) aqueous solution.
In this regard, the lyocell spinning dope may include 8 wt% to 13 wt% of the cellulose
pulp; and 87 wt% to 92 wt% of the N-methylmorpholine-N-oxide aqueous solution, wherein
the cellulose pulp may include 85 to 97 wt% of alpha-cellulose and have a degree of
polymerization (DPw) of 600 to 1700.
[0030] If an amount of the cellulose pulp is less than 8 wt%, it is difficult to realize
fibrous properties, and if the amount of the cellulose pulp exceeds 13 wt%, it may
be difficult to dissolve the cellulose pulp in the aqueous solution. In addition,
if an amount of the N-methylmorpholine-N-oxide aqueous solution is less than 87 wt%,
dissolution viscosity significantly increases which is not desirable, and if the amount
of the aqueous solution exceeds 92 wt%, spinning viscosity significantly decreases,
making it difficult to manufacture uniform fibers in the spinning process.
[0031] In the N-methylmorpholine-N-oxide aqueous solution, a weight ratio of N-methylmorpholine-N-oxide
to water may be from 93:7 to 85:15. If the weight ratio of the N-methylmorpholine-N-oxide
to water exceeds 93:7, dissolution temperature increases causing degradation of cellulose
during dissolution, and if the weight ratio is less than 85:15, solubility of a solvent
decreases, making it difficult to dissolve cellulose.
[0032] The above-described spinning dope is discharged from a spinning nozzle of a flat
or donut-shaped spinneret. In this case, the spinneret serves to discharge the spinning
dope in the form of filaments into a coagulation solution contained in a coagulation
bath through an air gap zone. The process of discharging the spinning dope from the
spinneret may be performed at 100 °C to 120 °C.
(S2)
[0033] In the present disclosure, the step (S2) is a step of coagulating the lyocell spinning
dope spun in the step (S1) above to obtain lyocell multi-filaments, and the coagulating
in the step (S2) may include: primary coagulation performed by air quenching (Q/A)
by coagulating the lyocell spinning dope spun in the step (S1) while supplying cooling
air thereto; and secondary coagulation performed by immersing the primarily coagulated
spun dope in a coagulation solution.
[0034] In the step (S1), after discharging the spinning dope through the flat or donut-shaped
spinneret, the lyocell spinning dope spun in the step (S1) may pass through the air
gap zone in a space between the above-described spinneret and the coagulation bath.
In such an air gap zone, the cooling air may be supplied in a direction from one side
to the opposite side of the spinneret in the case of the flat spinneret, and the cooling
air may be supplied outwards from an air-cooling part located inside the spinneret
in the case of the donut-shaped spinneret and a suction function may also be provided
on the opposite side or the outside. The primary coagulation may be performed by air
quenching in which the cooling air is supplied to the spinning dope.
[0035] In this regard, factors affecting physical properties of the lyocell multi-filaments
obtained in the step (S2) are temperature and air flow rate of cooling air in the
air gap zone, and the coagulation of the step (S2) may be performed by suppling cooling
air at a temperature of 4 °C to 15 °C and with an airflow rate of 50 L/m
3 to 250 L/m
3.
[0036] If the temperature of the cooling air is below 4 °C during the primary coagulation,
a surface temperature of the spinneret decreases to form a non-uniform cross-section
of the lyocell multi-filaments and deteriorate spinning processibility, and if the
temperature is above 15 °C, the primary coagulation by the cooling air does not proceed
sufficiently, resulting in deterioration of spinning processibilty.
[0037] In addition, if the airflow rate of cooling air is less than 50 L/m
3 during the primary coagulation, the primary coagulation by the cooling air does not
proceed sufficiently to deteriorate spinning processibilty, thereby causing breakage
of fibers in the tow, and if the airflow rate exceeds 250 L/m
3, the spinning dope discharged from the spinneret is shaken by the air, resulting
in deterioration of spinning processibility.
[0038] After the primary coagulation by air quenching, secondary coagulation may proceed
by supplying the spun dope to a coagulation bath containing a coagulation solution.
Meanwhile, for appropriate progress of the secondary coagulation, a temperature of
the coagulation solution may be 30 °C or below. This is because the temperature for
the secondary coagulation is maintained at a level not to be excessively higher than
necessary, so that coagulation rate is appropriately maintained. In this regard, the
coagulation solution is not particularly limited because it may be prepared and used
in a composition commonly available in the art to which the present disclosure belongs.
(S3)
[0039] In the present disclosure, the step (S3) is a step of water-washing the lyocell multi-filaments
obtained in the step (S2) described above. More specifically, the lyocell multi-filaments
obtained in the step (S2) were fed into a draw roller and then into a water-washing
bath to be washed with water.
[0040] In the process of washing the filaments with water, a water-washing solution at 0
to 100 °C may be used taking into consideration of recovery and reuse of the solvent
after the water-washing process. Water may be used as the water-washing solution,
and other additives may further be added thereto if required.
(S4)
[0041] In the present disclosure, the step (S4) is a step of treating the water-washed lyocell
multi-filaments with oil and hydrogen peroxide.
[0042] The step (S4) may be a process of treating the lyocell multi-filaments washed with
water in the step (S3) i) by using a mixed solution of the oil and hydrogen peroxide,
or ii) by sequentially using a single solution of hydrogen peroxide and a single solution
of the oil. By the above-described process, whiteness of the treated lyocell fibers
may be controlled to realize a desired level of whiteness.
[0043] That is, the step (S4) is characterized by treating the lyocell multi-filaments washed
with water in the step (S3) simultaneously with oil and hydrogen peroxide in the bath
containing the mixed solution of the oil and hydrogen peroxide with uniformly controlled
concentrations.
[0044] In addition, optionally, the step (S4) may include a process of treating the water-washed
lyocell multi-filaments sequentially in separate baths respectively containing a single
solution of the hydrogen peroxide and a single solution of the oil. In this method,
the concentrations of the single solution of hydrogen peroxide and the single solution
of the oil are uniformly maintained in each baths.
[0045] For the treatment with oil and hydrogen peroxide, a method of immersing the filament
tow in the bath in which oil and hydrogen peroxide are made-up and releasing the filament
tow may be used. Particularly, a method of simultaneously adding hydrogen peroxide
at a constant concentration while the oil is made-up may be used.
[0046] Specifically, in the method, it is important to uniformly control the concentrations
of both oil and hydrogen peroxide such that the oil and hydrogen peroxide are uniformly
applied to the water-washed lyocell multi-filaments.
[0047] Therefore, in the present disclosure, a method of adding the two components made-up
in constant concentrations may be used to uniformly maintain the concentrations of
oil and hydrogen peroxide in the bath.
[0048] Thus, according to an embodiment of the present disclosure, the step (S4) process
of treating the water-washed lyocell multi-filaments with oil and hydrogen peroxide
may include a process of treating the filaments water-washed in the step (S3) simultaneously
with oil and hydrogen peroxide by a method of immersing the filaments in a bath containing
a mixed solution of oil and hydrogen peroxide with controlled concentrations and releasing
the filaments. In this case, a bath containing the mixed solution of oil and hydrogen
peroxide may be prepared and the bath may be connected to the water-washing bath.
Also, a device for providing hydrogen peroxide and oil may be connected to the bath
containing the mixed solution of the hydrogen peroxide and oil to uniformly maintain
concentrations thereof.
[0049] In addition, according to another embodiment of the present disclosure, the step
(S4) process of treating the water-washed lyocell multi-filaments with oil and hydrogen
peroxide may include a process of treating the filaments water-washed in the step
(S3) by a method of sequentially immersing the filaments in the bath containing the
single solution of hydrogen peroxide with a controlled concentration and releasing
the filaments, and then immersing the filaments in the bath containing the single
solution of oil and releasing the filaments. In this case, the bath containing the
single solution of hydrogen peroxide may be connected to the bath containing the single
solution of oil and these baths may be connected to the water-washing bath. In addition,
devices configured to provide hydrogen peroxide and oil may be connected to each of
the baths to uniformly maintain the concentrations thereof.
[0050] Preferably, a higher white index and a lower yellow index may be more effectively
obtained by treating the lyocell multi-filaments washed with water in the step (S3)
simultaneously with oil and hydrogen peroxide using the mixed solution of oil and
hydrogen peroxide with controlled concentrations in the step (S4).
[0051] In this regard, the hydrogen peroxide may be used such that the content of hydrogen
peroxide in the solution for treating the lyocell multi-filaments is maintained in
a concentration of 2 to 6 wt%. In addition, the hydrogen peroxide may be continuously
added to the bath in a state of an aqueous solution to maintain the above-described
concentration. In addition, the bath may be provided with a device configured to maintain
concentrations of oil and hydrogen peroxide. For example, a device for measuring concentrations
of oil and hydrogen peroxide may be provided, and a releasing device for circulating
oil and hydrogen peroxide may be provided to maintain a level and standards of the
mixed solution containing oil and hydrogen peroxide.
[0052] With a hydrogen peroxide concentration of 2 wt% or less, a desired white index cannot
be obtained and hydrogen peroxide cannot uniformly permeate into the multi-filaments
so that bleaching is not completely performed after a post-crimping process. With
a hydrogen peroxide concentration of 6 wt% or more, the white index is not improved
even by an increased content of hydrogen peroxide in the tow and hydrogen peroxide
remains in large quantities after the post-crimping process so that physical properties
may deteriorate.
[0053] The oil may be used such that a concentration of the oil in the solution for treating
the lyocell multi-filaments is maintained in a range of 2 wt% to 8 wt% or 3 wt% to
7 wt% based on the lyocell multi-filaments. By maintaining of the amount of the oil
within the ranges described above, friction generated while the lyocell multi-filaments
are brought into contact with the machine may be reduced and formation of crimps between
fibers may be facilitated during the crimping operation.
[0054] As such, in the case where the concentrations of hydrogen peroxide and oil are not
maintained, it is difficult to uniformly bleaching the lyocell multi-filaments, the
crimping process may not be effectively performed, or physical properties of the lyocell
material may deteriorate, and thus effects on improving whiteness and physical properties
cannot be obtained. Therefore, in the step (S4), it is important to control the concentrations
of hydrogen peroxide and oil as described above.
[0055] By performing the step (S4), whiteness of the lyocell cigarette filter tow may be
improved to a desired level compared to conventional tows, and deterioration in physical
properties after the post process of forming crimps may be prevented.
[0056] In this case, the treatment with oil is performed in a state where the multi-filaments
are completely immersed in the oil, and an amount of oil applied to the multi-filaments
is uniformly maintained by squeezing rollers provided to an entry and release rollers
of an oil treatment device.
[0057] In addition, the treatment with hydrogen peroxide may also be performed in a state
where the lyocell multi-filaments are completely immersed in the bath in the same
manner as in the treatment with oil. Also, after performing the step (S4) process,
the step (S5) (crimping process) may be performed without drying the oil and hydrogen
peroxide.
[0058] In addition, the oil used for application to the filaments, unlike oil used for common
fibers, may be developed exclusively for lyocells. The oil is uniformly made-up because
the oil does not react with hydrogen peroxide.
[0059] According to a preferred embodiment, the oil may provide a lubricating function capable
of uniformly imparting physical properties of the cigarette filter tow, may optimize
processibility of a filter manufacturing process by imparting an appropriate level
of smoothness and cohesion, and may provide hydrophobicity, which delays penetration
of smoker's saliva into the cigarette filter, to reduce a filter hardness decrease
rate for minimizing a phenomenon in which hardness of a filter decreases as a result
of deformation of the filter by smoker's saliva during smoking. In addition, the oil
may be composed of components harmless to a smoker's body even when a certain amount
of the oil remains in the cigarette filter.
[0060] However, the oil serves to decrease friction of the filaments upon contact with a
drying roller and a guide and in the crimping process and also serves to effectively
form crimps on fibers, and the oil is not particularly limited so long as the oil
is commonly available for production of lyocell filaments.
[0061] As a preferred example, the oil may include at least one selected from the group
consisting of a lubricating component, a cohesion component, a smoothness component,
and a hydrophobic component.
(S5)
[0062] The step (S5) is a step of crimping the lyocell multi-filaments treated with oil
and hydrogen peroxide in the step (S4) to obtain the crimped tow.
[0063] Specifically, this is a process of crimping the lyocell multi-filaments treated with
oil and hydrogen peroxide by applying steam and pressure thereto, and a crimped tow
may be obtained in the step (S5).
[0064] The term "crimping" used throughout the specification refers to providing wrinkles
in filaments mainly to provide bulky texture to fibers. In the present disclosure,
the crimping process may be performed by using a stuffer box provided with a press
roller. The press roller may be a nip roller.
[0065] In this regard, a front end of the stuffer box is provided with a steam box for steam
treatment of the filament tow, conditions therefore may be controlled to satisfy a
pressure of steam of 0.1 to 3 kgf/cm
2 supplied to the steam box, a pressure of 1.5 to 4 kgf/cm
2 applied to a press roller, and an upper plate pressure of 0.1 to 3 kgf/cm
2. If the steam pressure is less than 0.1 kgf/cm
2, a modulus of the filaments cannot be lowered to a level appropriate for the process,
failing to easily form crimps, and if an excessive amount of steam exceeding 3.0 kgf/cm
2 is supplied, the modulus of the filaments is minimized but the number of required
crimps is not uniform due to a too high water content.
[0066] In addition, if the pressure applied by the press roller is less than 1.5 kgf/cm
2, the thickness of the fed filament may not be uniform, failing to uniformly form
the crimps in a desired number, and if the pressure exceeds 4 kgf/cm
2, a too strong pressing force drastically decreases an amount of water or oil present
in the tow so that the filament may not easily pass through the stuffer box. In this
case, it is preferable to maintain a gap between the press rollers in a range of 0.01
to 3.0 mm. If the gap between the press rollers is less than 0.01 mm, a pressure applied
to the filament by the roller increases, failing to form crimps or resulting in damage
caused by surface friction of the filaments after formation of crimps, and if the
gap exceeds 3.0 mm, a filament slipping phenomenon may occur between the press rollers,
making it difficult to form uniform crimps.
[0067] In addition, if a pressure of the upper plate vertically moving to provide uniform
crimps after the tow passes through the press roller is less than 0.1 kgf/cm
2, the upper plate cannot be fixed due to an internal pressure of the stuffer box,
and thus the tow stays in the stuffer box for a long time failing to obtain continuity
of the process or a desired number of crimps may not be obtained in the tow because
an optimal stay time cannot be provided. If the pressure of the upper plate exceeds
3.0 kgf/cm
2, the tow cannot be released from the stuffer box resulting in a non-uniform shape
of crimps.
[0068] Tows crimped under the above-described conditions may include and maintain 20 crimps
or more per inch, or 20 to 40 crimps per inch, or 30 to 40 crimps per inch. Accordingly,
because the lyocell crimped tow of the present disclosure is biodegraded and removed
in a short period of time, and thus the lyocell crimped tow is not only eco-friendly
but also more effectively satisfies physical properties required for cigarette filters,
such as suction resistance, filter hardness, and filter removability, thereby maximizing
the effects.
(S6)
[0069] The step (S6) is a step of drying the crimped tow obtained in the step (S5) at a
constant temperature.
[0070] Specifically, the oil and hydrogen peroxide contained in the baths and uniformly
applied to the filament tow immersed therein are picked up as levels capable of providing
the uniform number of crimps in the crimping process.
[0071] Subsequently, by drying the crimped tow using a continuous drying device, a final
lyocell crimped tow containing a uniform amount of hydrogen peroxide may be prepared.
[0072] The process of drying the crimped tow may be performed by using a continuous drying
device at a temperature of 105 to 135 °C for 15 minutes to 45 minutes or at a temperature
of 110 to 130 °C for 20 minutes to 40 minutes. Preferably, the drying of the crimped
tow may be performed at a temperature of 110 to 130 °C for 20 minutes to 40 minutes
to facilitate bleaching reaction contributing to providing products with excellent
whiteness.
[0073] At a drying temperature of 105 °C or below, bleaching reaction does not easily occur
and the tow is not completely dried failing to control a required moisture content.
At a drying temperature of 135 °C or above, whiteness may be lowered due to a yellowing
phenomenon. In addition, if a drying time is 15 minutes or less, bleaching reaction
does not easily occur and there may be an irregularly dried portion. If the drying
time is 45 minutes or more, the tow surface may be damaged due to the excessive drying
time and whiteness may be lowered due to a yellowing phenomenon.
[0074] That is, for efficient bleaching reaction of hydrogen peroxide contained in the tow,
conditions for the continuous drying device may be controlled within the ranges described
above for the multi-filaments treated with oil and hydrogen peroxide.
[0075] In addition, the tow finally manufactured after the drying process may contain 1000
ppm or less of hydrogen peroxide and additional bleaching reaction may occur due to
aging effect in a packed tow. Therefore, the present disclosure may provide a cigarette
filter with excellent whiteness further improved by aging in accordance with packaging
of the tow.
Lyocell Material
[0076] According to another embodiment, provided is a lyocell material including a lyocell
crimped tow formed of lyocell multi-filaments obtained by spinning a lyocell spinning
dope including cellulose pulp and an N-methylmorpholine-N-oxide (NMMO) aqueous solution,
treated with oil, and bleached with hydrogen peroxide, wherein the crimped tow includes
1000 ppm or less of hydrogen peroxide and satisfies a white index of 80 or more and
a yellow index of 8 or less.
[0077] According to the above-described method, whiteness of the tow may be improved by
remaining a certain amount of hydrogen peroxide in the tow by using hydrogen peroxide
with a concentration controlled in a certain range together with oil in the process
of treating the tow with oil, and whiteness may further be improved, particularly,
by the aging effect in accordance with drying and packaging.
[0078] However, although the hydrogen peroxide content is 1000 ppm or less in the crimped
tow, a desired level of whiteness required for cigarette filters cannot be obtained
in the case of using a too low hydrogen peroxide content. Therefore, even in the case
where the hydrogen peroxide content in the crimped tow satisfies 1000 ppm or less,
the content may be higher than a certain level, specifically, a lower limit of 110
ppm.
[0079] Therefore, the crimped tow may be a lyocell tow including hydrogen peroxide in an
amount of 110 ppm or more and 1000 ppm or less and satisfying a white index of 80
to 90 and a yellow index of 1 to 4.5. More specifically, the crimped tow may be a
lyocell crimped tow including hydrogen peroxide in an amount of 400 ppm or more and
980 ppm or less and having excellent whiteness satisfying a white index of 80 to 90
and a yellow index of 1 to 4.
[0080] In addition, the lyocell material according to the present disclosure may realize
a whiteness (white index of 80 or more and a yellow index of 8 or less) desired by
cigarette manufacturers.
[0081] Furthermore, according to the present disclosure, environmental pollution problems
caused by discarded cigarette butts may be reduced by replacing CA cigarette filters.
[0082] In this regard, the concentration of hydrogen peroxide used for bleaching treatment
of the lyocell tow may be from 2 to 6 wt%.
[0083] The lyocell spinning dope may include 8 wt% to 13 wt% of the cellulose pulp; and
87 wt% to 92 wt% of the N-methylmorpholine-N-oxide aqueous solution.
[0084] The cellulose pulp may include 85 to 99 wt% of alpha-cellulose and may have a degree
of polymerization (DPw) of 600 to 1700.
[0085] Meanwhile, according to another embodiment of the present disclosure, a cigarette
filter including the lyocell material with controlled whiteness may be provided.
[0086] The composition of the cigarette filter is not limited except for the lyocell tow
with improved whiteness.
[0087] For example, the cigarette filter may include a cylindrical lyocell tow including
a plurality of lyocell fibers, a plasticizer, a curing agent, and the like.
[0088] The plurality of lyocell fibers are connected to each other by the curing agent to
exhibit a mutually bonded structure in which surfaces of the fibers are in contact
with the curing agent.
[0089] The curing agent may be any known material used to increase hardness of the filter.
For example, the curing agent may include a cellulose derivative, a vinyl derivative,
a vinyl emulsion derivative, a natural polymer including sodium alginate, and a polymer
resin such as starch and a starch derivative.
Advantageous Effects
[0090] According to the present disclosure, by adding a chemical compound (hydrogen peroxide)
for improving whiteness to a process of manufacturing a lyocell cigarette filter tow,
a tow with excellent whiteness in which hydrogen peroxide remains therein in an amount
of 1,000 ppm or less may be provided. In addition, according to the present disclosure,
whiteness may further be improved by the drying process performed by bleaching reaction
under a certain conditions and the aging effect in accordance with a process of packaging
the dried material.
[0091] Therefore, whiteness (white index of 80 or more and a yellow index of 8 or less)
desired by cigarette manufacturers may be realized by adding a bleaching process to
a conventional tow manufacturing process.
[0092] In addition, because the lyocell tow is provided by using an eco-friendly method
according to the present disclosure, environmental pollution factors caused by discarded
cigarette butts may be reduced by replacing conventional CA cigarette filters.
Best Mode
[0093] Hereinafter, the present disclosure will be described in more detail with reference
to the following examples. However, the following examples are merely presented to
exemplify the present disclosure, and the scope of the present disclosure is not limited
thereto.
Example 1
[0094] Cellulose pulp having a degree of polymerization (DPw) of 820 and including 93.9
% of alpha-cellulose was mixed with a NMMO/H
2O mixed solvent (weight ratio of 90/10) including 0.01 wt% of propyl gallate to prepare
a spinning dope for preparing a tow for a cigarette filter with a concentration of
12 wt%. First, the spinning dope was maintained at a spinning temperature of 110 °C
in a spinning nozzle and spun while adjusting a discharge amount and a spinning rate
such that a single fiber fineness of filaments was adjusted to 2.4 De.
[0095] The spinning dope in the form of filaments discharged from the spinning nozzle was
supplied to a coagulation solution contained in a coagulation bath through an air
gap zone. In this case, the spinning dope was primarily coagulated in the air gap
zone using cooling air at a temperature of 8 °C and an airflow rate of 100 L/m
3. A coagulation solution including 75 wt% of water and 25 wt% of NMMO was used at
25 °C. In this case, a concentration of the coagulation solution was continuously
monitored by using a sensor and a refractometer.
[0096] The coagulated filaments were washed by a water-wash solution sprayed by a water-washing
device via a draw roller to remove NMMO remaining in the filaments.
[0097] Subsequently, the water-washed filaments were immersed in a bath containing a mixed
solution of oil and hydrogen peroxide made-up in concentrations of 2 wt% of the oil
and 5 wt% of the hydrogen peroxide. That is, a method of adding oil and hydrogen peroxide
made-up in certain concentrations was used to continuously maintain uniform concentrations
in the bath such that the oil content of 2 wt% and the hydrogen peroxide content of
5 wt% are maintained to uniformly apply oil and hydrogen peroxide to the filaments.
[0098] The oil treatment was performed by immersing the filaments in the bath and releasing
the filaments, and simultaneously hydrogen peroxide treatment was performed.
[0099] Specifically, the filament tow immersed in the bath was treated at a pressure of
2 kgf/cm
2 by using a nip roller provided at the stuffer box of the front end of a Crimp M/C
installed at a release portion of the bath to release the multi-filaments treated
with oil and hydrogen peroxide in the bath. Then, the multi-filaments were fed into
a Crimp M/C and crimped to prepare a lyocell crimped tow. The prepared tow was passed
through a continuous drying device set to a temperature of 120 °C to obtain a dried
tow product (drying treatment time: 25 min).
Example 2
[0100] A lyocell tow for a cigarette filter was prepared in the same manner as in Example
1, except that the concentration of hydrogen peroxide was changed to 3 wt%.
Example 3
[0101] A lyocell tow for a cigarette filter was prepared in the same manner as in Example
1, except that the concentration of hydrogen peroxide was changed to 2 wt%.
Example 4
[0102] A lyocell tow for a cigarette filter was prepared in the same manner as in Example
1, except that the concentration of hydrogen peroxide was changed to 6 wt%.
Example 5
[0103] A lyocell tow for a cigarette filter was prepared in the same manner as in Example
1, except that a method of sequentially immersing the water-washed lyocell multi-filaments
in a bath containing hydrogen peroxide made-up in a concentration of 5 wt% and in
a bath containing oil made-up in a concentration of 2 wt% in the treatment of the
water-washed lyocell multi-filaments with oil and hydrogen peroxide.
[0104] In addition, a method of adding oil and hydrogen peroxide made-up in certain concentrations
was used to continuously maintain uniform concentrations in the baths such that the
oil and hydrogen peroxide are uniformly applied to the filaments. By using the method,
the oil content of 2 wt% and the hydrogen peroxide content of 5 wt% was maintained.
Comparative Example 1
[0105] A lyocell tow for a cigarette filter was prepared in the same manner as in Example
1, except that only 2 wt% of an oil was used without adding hydrogen peroxide.
Comparative Example 2
[0106] A lyocell tow for a cigarette filter was prepared in the same manner as in Example
1, except that the concentration of hydrogen peroxide was changed to 1 wt%.
Comparative Example 3
[0107] A lyocell tow for a cigarette filter was prepared in the same manner as in Example
1, except that the concentration of hydrogen peroxide was changed to 7 wt%.
Comparative Example 4
[0108] A lyocell tow for a cigarette filter was prepared in the same manner as in Example
1, except that the concentration of hydrogen peroxide was changed to 10 wt%.
Comparative Example 5
[0109] A lyocell tow for a cigarette filter was prepared in the same manner as in Example
1, except that the drying treatment conditions were changed to 100 °C and 50 minutes
in the continuous drying device.
Comparative Example 6
[0110] A lyocell tow for a cigarette filter was prepared in the same manner as in Example
1, except that the drying treatment conditions were changed to 100 °C and 10 minutes
in the continuous drying device.
Comparative Example 7
[0111] A lyocell tow for a cigarette filter was prepared in the same manner as in Example
1, except that the drying treatment conditions were changed to 140 °C and 10 minutes
in the continuous drying device.
Comparative Example 8
[0112] A lyocell tow for a cigarette filter was prepared in the same manner as in Example
1, except that the drying treatment conditions were changed to 140 °C and 50 minutes
in the continuous drying device.
[Experimental Example]
[0113] Contents of hydrogen peroxide in the tows and whiteness of the tows of the examples
and comparative examples described above were measured according to the following
method, and the results are shown in Table 1.
Method of Measuring Physical Property
(1) Measurement of Content of Hydrogen Peroxide in Tow
[0114] Volumetric analysis was performed using a potassium permanganate solution (0.1 N)
as a standard solution by applying the principle of redox titration.
[0115] Each of the tows prepared in the examples and comparative examples was allowed to
stand for 24 hours under standard conditions for constant temperature and humidity.
Then, the tow was immersed in ultrapure water in a weight ratio of 10 wt% to perform
sonication for 30 minutes. After sonication, 10 ml of the ultrapure water was collected
and 10 ml of distilled water and 2 ml of concentrated sulfuric acid were added thereto.
Samples for titration prepared as described above were titrated by a Karl Fischer
titrator using a standard solution and amounts of hydrogen peroxide contained in the
tows were calculated by measuring endpoints.
[0116] In Equation 1, 0.0017 is a mass (g) of hydrogen peroxide equivalent to 1 m of the
0.1 N potassium permanganate solution, V is a titer (ml) of the 0.1 N potassium permanganate
solution, F is a normality coefficient factor of the 0.1 N potassium permanganate
solution, D is a dilution ratio of the hydrogen peroxide-containing solution extracted
from the tow (=1), and S is a weight (g) of the sample.
[0117] Here, with regard to D, although the sample is diluted in the case where the concentration
is high, D was 1 in the present disclosure because the extract was used as it is.
(2) Measurement of Whiteness of Tow
[0118] Whiteness was measured by using a CCM device (X-Rite ColorEye 7000A Spectrophotometer).
[0119] 3 strands of each of the tows prepared in the examples and comparative examples were
prepared and fractured at the center in the same manner as in measurement of tensile
strength. For measurement of whiteness, this experiment was repeated three times and
fractured portions were overlapped and agglomerated. Then, the agglomerated sample
was mounted on the CCM device to measure white index and yellow index and results
were drawn.
[Table 1]
|
Hydrogen peroxide concentration % |
Bath Nip Roll pressure (kgf/cm2) |
Contents of hydrogen peroxide in tow (ppm) |
Whiteness |
W.I |
Y.I |
Example 1 |
5 |
2 |
900 |
82.1 |
3.3 |
Example 2 |
3 |
2 |
550 |
80.5 |
3.8 |
Example 3 |
2 |
2 |
400 |
80.1 |
4.0 |
Example 4 |
6 |
2 |
980 |
81.4 |
3.4 |
Example 5 |
5 |
2 |
300 |
80.0 |
4.4 |
Comparative Example 1 |
0 |
2 |
0 |
52.3 |
13.2 |
Comparative Example 2 |
1 |
2 |
100 |
74.0 |
5.3 |
Comparative Example 3 |
7 |
2 |
1350 |
74.7 |
5.7 |
Comparative Example 4 |
10 |
2 |
1500 |
71.8 |
6.8 |
Comparative Example 5 |
5 |
2 |
1200 |
78.2 |
4.6 |
Comparative Example 6 |
5 |
2 |
Partially not dried, not measurable |
Comparative Example 7 |
5 |
2 |
Partially not dried, not measurable |
Comparative Example 8 |
5 |
2 |
650 |
77.3 |
5.1 |
[0120] As a result of measuring physical properties, as shown in Table 1, it was confirmed
that the level of whiteness required for cigarette filters was realized in Examples
1 to 5 compared to the comparative examples and the whiteness may be controlled to
various levels (whiteness (W.I: 80 or more and Y.I: 8 or less). Specifically, according
to Examples 1 to 5, lyocell crimped tows with excellent whiteness including 300 ppm
to 980 ppm of hydrogen peroxide and satisfying both a white index of 80 to 90 and
a yellow index of 1 to 5 may be provided.
[0121] Particularly, in the case of Examples 1 to 4 in which the concentration of hydrogen
peroxide is maintained in the range of 5 to 6 wt%, the lyocell crimped tow satisfied
a W.I of 81.4 to 82.1 and a Y.I of 3.3 to 3.4, and thus a cigarette filter with excellent
whiteness may be provided.
[0122] In addition, in the case of Example 5 in which oil treatment was performed after
treatment with hydrogen peroxide, the lyocell crimped tow satisfied a W.I of 80.0
and a Y.I of 4.4 indicating desired whiteness. In this regard, the whiteness of Example
5 was slightly inferior to those of the examples in which the tows were treated simultaneously
with hydrogen peroxide and oil. It may be inferred that hydrogen peroxide contained
in the tow is instantly detached by oil during the oil treatment process after the
treatment with hydrogen peroxide. However, Example 5, like Examples 1 to 4, satisfied
both the white index and yellow index desired by the industry with the hydrogen peroxide
content of 1000 ppm or less in the tow compared to the comparative examples. Therefore,
the tows of the embodiments of the present disclosure may be used as eco-friendly
materials for cigarette filter more effectively compared to conventional materials.
[0123] On the contrary, in the case of Comparative Example 1, the tow was not treated with
hydrogen peroxide, and it was confirmed that whiteness was inferior to the extent
that results are visually distinguished.
[0124] In addition, although hydrogen peroxide is a factor affecting whiteness of the tows
in Comparative Examples 2 to 4, the amount of hydrogen peroxide used for the treatment
is out of the range of the present disclosure, and thus it was confirmed that distorted
results in which whiteness was increased and decreased according to the residual concentration
were obtained. Particularly, in the case of Comparative Example 2, although the hydrogen
peroxide content in the tow was less than 1000 ppm, the level of whiteness required
for cigarette filters was not satisfied because the content was too low. In addition,
in the case of Comparative Examples 3 and 4, although the hydrogen peroxide contents
in the tows were more than 1000 ppm, whiteness decreased failing to satisfy the level
desired by the industry, showing an uneconomical effect compared to the amount of
hydrogen peroxide used therefor.
[0125] In addition, in the case of Comparative Examples 5 to 8, although the tow was treated
with hydrogen peroxide, the drying conditions are out of the ranges of the present
disclosure, and thus desired whiteness was not able to be obtained due to insufficient
bleaching reaction of hydrogen peroxide.
[0126] Therefore, according to the present disclosure, excellent whiteness desired by the
cigarette manufacturers may be realized by treating the cigarette filter tow with
hydrogen peroxide with a concentration controlled in a certain range. Furthermore,
in the present disclosure, the W.I and the Y.I may be optimized by adjusting temperature
conditions during bleaching reaction in addition to the treatment with hydrogen peroxide.
[0127] In addition, according to the present disclosure, environmental pollution caused
by discarded CA cigarette buts may be reduced by replacing conventional CA cigarette
filters treated with a photocatalyst.