LYOCELL MATERIAL WITH CONTROLLED WHITENESS BY HYDROGEN PEROXIDE TREATMENT AND MANUFACTURING METHOD THEREOF

Abstract

The present disclosure relates to a lyocell material with controlled whiteness by hydrogen peroxide treatment and a manufacturing method thereof, wherein the lyocell material has improved whiteness due to an aging effect through drying and packaging by a predetermined amount of hydrogen peroxide remaining in a tow, and may replace a CA cigarette filter to lower environmental pollution problems caused by discarded cigarette butts, and thus the lyocell material is suitable as a cigarette filter.

Claims

1. A method of manufacturing a lyocell material, the method comprising: (S1) spinning a lyocell spinning dope comprising 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 to obtain a crimped tow; and (S6) drying the crimped tow, wherein the step (S4) comprises 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.

2. The method of claim 1, wherein the hydrogen peroxide in the step (S4) is used to have a concentration maintained in a range of 2 wt % to 6 wt % in the solution for treating the lyocell multi-filaments.

3. The method of claim 1, wherein the oil in the step (S4) is used to have a concentration maintained in a range of 2 wt % to 8 wt % in the solution for treating the lyocell multi-filaments.

4. The method of claim 1, wherein the oil in the step (S4) comprises at least one selected from the group consisting of a lubricating component, a cohesion component, a smoothness component, and a hydrophobic component.

5. The method of claim 1, wherein the drying of the crimped tow in the step (S6) is performed by using a continuous drying device at a temperature of 105? C. to 135? C. for 15 minutes to 45 minutes.

6. The method of claim 1, wherein the coagulating in the step (S2) is performed by supplying cooling air to the spun dope at a temperature of 4? C. to 15? C. and at an airflow rate of 50 L/m.sup.3 to 250 L/m.sup.3.

7. The method of claim 1, wherein the lyocell spinning dope in the step (S1) comprises 8 wt % to 13 wt % of the cellulose pulp and 87 wt % to 92 wt % of the N-methylmorpholine-N-oxide aqueous solution.

8. The method of claim 1, wherein the cellulose pulp comprises 85 wt % to 99 wt % of alpha-cellulose and has a degree of polymerization (DPw) of 600 to 1700.

9. The method of claim 1, wherein the crimped tow is a lyocell crimped tow including hydrogen peroxide in an amount of 1000 ppm or less.

10. A lyocell material comprising: 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 comprises 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.

11. The lyocell material of claim 10, wherein the crimped tow is a lyocell crimped tow including hydrogen peroxide in an amount of 110 ppm or more and 1000 ppm or less and satisfying both a white index of 80 to 90 and a yellow index of 1 to 4.

12. The lyocell material of claim 10, wherein the hydrogen peroxide is used to have a concentration maintained in a range of 2 wt % to 6 wt % in the solution for treating the lyocell multi-filaments during the bleaching.

13. The lyocell material of claim 10, wherein the oil is used to have a concentration maintained in a range of 2 wt % to 8 wt % in the solution for treating the lyocell multi-filaments during the oil treatment.

14. The lyocell material of claim 10, wherein the lyocell spinning dope comprises 8 wt % to 13 wt % of the cellulose pulp and 87 wt % to 92 wt % of the NMMO aqueous solution.

15. The lyocell material of claim 14, wherein the cellulose pulp comprises 85 wt % to 99 wt % of alpha-cellulose and has a degree of polymerization (DPw) of 600 to 1700.

16. A cigarette filter comprising the lyocell material according to claim 10.

Description

BEST MODE

[0110] 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

[0111] Cellulose pulp having a degree of polymerization (DPw) of 820 and including 93.9% of alpha-cellulose was mixed with a NMMO/H.sub.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.

[0112] 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.sup.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.

[0113] 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.

[0114] 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.

[0115] The oil treatment was performed by immersing the filaments in the bath and releasing the filaments, and simultaneously hydrogen peroxide treatment was performed.

[0116] Specifically, the filament tow immersed in the bath was treated at a pressure of 2 kgf/cm.sup.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

[0117] 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

[0118] 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

[0119] 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

[0120] 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.

[0121] 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

[0122] 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

[0123] 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

[0124] 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

[0125] 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

[0126] 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

[0127] 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

[0128] 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

[0129] 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

[0130] 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

[0131] Volumetric analysis was performed using a potassium permanganate solution (0.1 N) as a standard solution by applying the principle of redox titration.

[0132] 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.

H.sub.2O.sub.2(%) in tow=0.0017?V?F?D/S?100[Equation 1]

[0133] 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.

[0134] 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

[0135] Whiteness was measured by using a CCM device (X-Rite ColorEye 7000A Spectrophotometer).

[0136] 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-US-00001 TABLE 1 Hydrogen Contents of peroxide Bath Nip hydrogen concentration Roll pressure peroxide Whiteness % (kgf/cm.sup.2) in tow (ppm) 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 0 2 0 52.3 13.2 Example 1 Comparative 1 2 100 74.0 5.3 Example 2 Comparative 7 2 1350 74.7 5.7 Example 3 Comparative 10 2 1500 71.8 6.8 Example 4 Comparative 5 2 1200 78.2 4.6 Example 5 Comparative 5 2 Partially not dried, not Example 6 measurable Comparative 5 2 Partially not dried, not Example 7 measurable Comparative 5 2 650 77.3 5.1 Example 8

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.