LYOCELL MATERIAL FOR CIGARETTE FILTER, AND PREPARATION METHOD THEREFOR

Abstract

This invention relates to a method of manufacturing a lyocell material for a cigarette filter, including (S1) spinning a lyocell spinning dope composed of 8 to 13 wt % of a cellulose pulp and 87 to 92 wt % of an N-methylmorpholine-N-oxide (NMMO) aqueous solution; (S2) coagulating the lyocell spinning dope spun in (S1), thus obtaining a lyocell multifilament; (S3) water-washing the lyocell multifilament obtained in (S2); (S4) oiling the lyocell multifilament water-washed in (S3); and (S5) applying steam and pressure to the lyocell multifilament obtained in (S4), thus obtaining a crimped tow having 30 to 40 crimps per inch.

Claims

1. A method of manufacturing a lyocell material for a cigarette filter, comprising: (S1) spinning a lyocell spinning dope comprising 8 to 13 wt % of a cellulose pulp and 87 to 92 wt % of an N-methylmorpholine-N-oxide (NMMO) aqueous solution; (S2) coagulating the lyocell spinning dope spun in (S1), thus obtaining a lyocell multifilament; (S3) water-washing the lyocell multifilament obtained in (S2); (S4) oiling the lyocell multifilament water-washed in (S3); and (S5) applying steam and pressure to the lyocell multifilament obtained in (S4), thus obtaining a crimped tow having 30 to 40 crimps per inch.

2. The method of claim 1, wherein in the lyocell spinning dope of (S1), the cellulose pulp comprises 85 to 99 wt % of alpha-cellulose and has a degree of polymerization (DPw) of 600 to 1700.

3. The method of claim 1, wherein the coagulating in (S2) comprises primary coagulation using air quenching (Q/A) including supplying cold air to the spinning dope and secondary coagulation including immersing the primarily coagulated spinning dope in a coagulation solution.

4. The method of claim 3, wherein the air quenching is performed by supplying the cold air at a temperature of 4 to 15° C. and a wind velocity of 30 to 120 m/s to the spinning dope, and the coagulation solution has a temperature of 30° C. or less.

5. The method of claim 1, wherein (S5) is performed using a stuffer box.

6. The method of claim 5, wherein the stuffer box is controlled so that a steam pressure is 0.1 to 3 kgf/cm.sup.2, a press roller pressure is 1.5 to 4 kgf/cm.sup.2, and an upper plate pressure is 0.1 to 3 kgf/cm.sup.2.

7. A lyocell material for a cigarette filter, manufactured by spinning a lyocell spinning dope comprising a cellulose pulp and an N-methylmorpholine-N-oxide (NMMO) aqueous solution to produce a lyocell multifilament and applying steam and pressure to the lyocell multifilament to give a crimped tow, wherein the crimped tow has 30 to 40 crimps per inch.

8. The lyocell material of claim 7, wherein the lyocell spinning dope comprises 8 to 13 wt % of a cellulose pulp and 87 to 92 wt % of an N-methylmorpholine-N-oxide aqueous solution.

9. The lyocell material of claim 7, wherein the cellulose pulp comprises 85 to 99 wt % of alpha-cellulose and has a degree of polymerization (DPw) of 600 to 1700.

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

Description

EXAMPLE 1

[0047] A spinning dope having a concentration of 12 wt % for manufacturing a lyocell material was prepared by mixing a cellulose pulp having DPw of 820 and 93.9% of alpha-cellulose with an NMMO/H.sub.2O solvent mixture (at a weight ratio of NMMO/H.sub.2O: 90/10) containing 0.01 wt % of propyl gallate. The spinning dope was spun via the spinning nozzle of a donut-shaped spinneret under the condition that the spinning temperature was maintained at 110° C., while the amount of the spinning dope to be discharged and the spinning rate were adjusted so that the fineness per filament was 3.0 denier.

[0048] Subsequently, the filamentary spinning dope discharged from the spinning nozzle was supplied into a coagulation solution in a coagulation bath through an air gap. As such, the spinning dope was primarily coagulated using cold air at a temperature of 8° C. and a wind velocity of 50 m/s in the air gap. Then, secondary coagulation was carried out using a coagulation solution comprising 85 wt % of water and 15 wt % of NMMO at a temperature of 25° C. As such, the concentration of the coagulation solution was continuously monitored using a sensor and a refractometer.

[0049] Subsequently, the coagulated filaments were drawn in the air layer through a draw roller and then washed with a water-washing solution sprayed using a water-washing device to remove the remaining NMMO, after which the filaments were sufficiently uniformly impregnated with oil and then pressed so that the filaments had an oil content of 0.2%. Subsequently, the oiled filaments were dried at 150.sup.00 using a drying roller, heated while passing through a stuffer box, and then crimped through press rollers in the stuffer box, thereby completing a lyocell crimped tow. Here, steam was supplied at 0.5 kgf/cm.sup.2 and the pressure and interval of the press rollers were 1.5 kgf/cm.sup.2 and 1.5 mm, respectively, and the upper plate pressure was set to 1.0 kgf/cm.sup.2.

EXAMPLE 2

[0050] A lyocell material for a cigarette filter was manufactured in the same manner as in Example 1, with the exception that the crimped tow was obtained using the stuffer box under the condition that steam of 1.0 kgf/cm.sup.2 was supplied, the pressure and interval of the press rollers were 2.0 kgf/cm.sup.2 and 1.2 mm, respectively, and the upper plate pressure was set to 1.5 kgf/cm.sup.2.

EXAMPLE 3

[0051] A lyocell material for a cigarette filter was manufactured in the same manner as in Example 1, with the exception that the crimped tow was obtained using the stuffer box under the condition that steam of 1.5 kgf/cm.sup.2 was supplied, the pressure and interval of the press rollers were 3.0 kgf/cm.sup.2 and 1.0 mm, respectively, and the upper plate pressure was set to 2.0 kgf/cm.sup.2.

COMPARATIVE EXAMPLE 1

[0052] A lyocell material for a cigarette filter was manufactured in the same manner as in Example 1, with the exception that the crimped tow was obtained using the stuffer box under the condition that steam of 0.5 kgf/cm.sup.2 was supplied, the pressure and interval of the press rollers were 2.0 kgf/cm.sup.2 and 2.0 mm, respectively, and the upper plate pressure was not applied.

COMPARATIVE EXAMPLE 2

[0053] A lyocell material for a cigarette filter was manufactured in the same manner as in Example 1, with the exception that the crimped tow was obtained using the stuffer box under the condition that steam of 1.0 kgf/cm.sup.2 was supplied, the pressure and interval of the press rollers were 3.0 kgf/cm.sup.2 and 1.5 mm, respectively, and the upper plate pressure was set to 3.5 kgf/cm.sup.2.

COMPARATIVE EXAMPLE 3

[0054] A lyocell material for a cigarette filter was manufactured in the same manner as in Example 1, with the exception that the crimped tow was obtained using the stuffer box under the condition that steam of 1.5 kgf/cm.sup.2 was supplied, the pressure and interval of the press rollers were 4.0 kgf/cm.sup.2 and 1.0 mm, respectively, and the upper plate pressure was not applied.

COMPARATIVE EXAMPLE 4

[0055] A lyocell material for a cigarette filter was manufactured in the same manner as in Example 1, with the exception that the crimped tow was obtained using the stuffer box under the condition that steam of 2.0 kgf/cm.sup.2 was supplied, the pressure and interval of the press rollers were 5.0 kgf/cm.sup.2 and 3.5 mm, respectively, and the upper plate pressure was set to 1.5 kgf/cm.sup.2.

[0056] <Measurement>

[0057] (1) Measurement of the number of crimps: According to KS K 0326, twenty fiber specimens in which crimps were not damaged were adhered to a prepared glossy paper sheet (with a space distance of 25 mm) using an amyl acetate adhesive comprising 4 to 5% celluloid so that each fiber specimen was extended by (25±5)% relative to the space distance, after which the specimens were allowed to stand to dry the adhesive. The number of crimps in 25 mm was counted when an initial load of 1.96/1000 cN (2 mgf) per 1 D was applied to each specimen using a crimp tester, and the average value thereof was determined to one decimal place.

[0058] (2) Crimp uniformity: According to the above method of measuring the number of crimps, the width of the non-uniform crimp X relative to the width of the tow of the sampled specimen was measured and the grade of crimps was determined based on the criteria shown in Table 1 below.

TABLE-US-00001 TABLE 1 Grade (crimp state) ⊚ ◯ Δ X Width ratio of non- 0 < X ≦ 0.1 0.1 < X ≦ 0.5 0.5 < X ≦ 1 All non- uniform crimp uniform

[0059] (3) Suction Resistance

[0060] Using the tows manufactured in the above Examples and Comparative Examples, filter rods having a uniform diameter were manufactured, and the suction resistance thereof was measured using a suction resistance tester compliant with the KS H ISO 6565 standard.

TABLE-US-00002 TABLE 2 Press No. of Steam roller Plate crimps Suction pressure pressure pressure (crimps/ Crimp resistance (kgf/cm.sup.2) (kgf/cm.sup.2) (kgf/cm.sup.2) inch) state (PD) Ex.1 0.5 1.5 1.0 30 ◯ 340 Ex.2 1.0 2.0 1.5 34 ⊚ 320 Ex.3 1.5 3.0 2.0 38 ◯ 300 C.Ex.1 0.5 2.0 X — X — C.Ex.2 1.0 3.0 3.5 42 Δ 280 C.Ex.3 1.5 4.0 X 20 X 260 C.Ex.4 2.0 5.0 1.5 — X —

[0061] Based on the results of measurement of the properties, as is apparent from Table 2, the crimped tows of Examples 1 to 3 had at least 30 crimps per inch, and the crimp state thereof was generally good. Thus, suction resistance of 300 to 340, required of a regular-type cigarette filter, was satisfied. However, in Comparative Examples 1 to 4, the number of crimps was relatively low compared to the Examples, and the crimp state was poor. In particular, in Comparative Example 2, the upper plate pressure was excessively applied, and thus the retention time of crimps was prolonged, whereby the number of crimps was increased but the crimp state was poor and suction resistance was not uniform.

[0062] Furthermore, the upper plate pressure was not applied in Comparative Examples 1 and 3, and thus crimps were not formed or a small number of crimps was formed, and in Comparative Example 4, in which the press roller pressure was too high, the amount of water or oil present in the tow was drastically decreased and thus the crimps were not normally formed. In the case where the processing of the present invention was performed under conditions falling out of the above processing ranges, a tow having good crimps could not be formed, and thus suction resistance was remarkably decreased, making it unsuitable for use in a fiber for a cigarette filter.