SPUNBOND NONWOVEN FABRIC WITH IMPROVED OPENING QUALITY AND NO HAZARDOUS RESIDUE, MANUFACTURING METHOD THEREOF AND MANUFACTURING APPARATUS THEREOF

Abstract

The present invention relates to a spunbond nonwoven fabric with improved opening quality and no hazardous residue, a manufacturing method thereof, and a manufacturing apparatus thereof. The method for manufacturing a spunbond nonwoven fabric according to the present invention includes a step of allowing the continuous filament bundle to collide with a metal member containing bismuth (Bi) or a bismuth alloy to obtain filaments opened by frictional charging.

Claims

1. A method for manufacturing a spunbond nonwoven fabric, the method comprising the steps of: melt-spinning a thermoplastic resin to obtain a continuous filament bundle; allowing the continuous filament bundle to collide with a metal member containing bismuth (Bi) or a bismuth alloy to obtain filaments opened by frictional charging; and converging the opened filaments on a continuous conveyor net to form a fiber web.

2. The method for manufacturing a spunbond nonwoven fabric according to claim 1, wherein the bismuth alloy contains 10% by weight or more of bismuth based on the weight of the bismuth alloy.

3. The method for manufacturing a spunbond nonwoven fabric according to claim 1, wherein the bismuth alloy comprises at least one metal selected from the group consisting of copper (Cu), zinc (Zn), tin (Sn), aluminum (Al), molybdenum (Mo), and titanium (Ti).

4. The method for manufacturing a spunbond nonwoven fabric according to claim 1, wherein the continuous filament bundle collides with the metal member at a linear velocity of 4000 m/min to 6000 m/min and a mass flow rate of 2.0 kg/h to 8.0 kg/h per nozzle that jets the continuous filament bundle.

5. The method for manufacturing a spunbond nonwoven fabric according to claim 1, wherein the opened filaments have a charge generation amount by the frictional charging (a value measured by a Faraday cage method) of −3500 nC/s to −500 nC/s.

6. The method for manufacturing a spunbond nonwoven fabric according to claim 1, wherein the opened filaments are converged on the continuous conveyor net with an opening width of 500 mm or more under conditions where the rotation angle range of the nozzle for jetting the filament bundle is −15±5° to +15±5° and the reciprocating speed of the nozzle is 3 counters/s to 12 counters/s (wherein the opening width means the maximum width based on the moving direction of the opened filaments converged on the continuous conveyor net).

7. The method for manufacturing a spunbond nonwoven fabric according to claim 1, wherein the thermoplastic resin has a melting point of 200° C. or more, and the thermoplastic resin is at least one resin selected from the group consisting of polyester, polyamide, polyolefin, and polyphenylene sulfide.

8. The method for manufacturing a spunbond nonwoven fabric according to claim 1, wherein the thermoplastic resin is at least one resin selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polycyclohexane terephthalate, polyethylene naphthalate, nylon, polyethylene, polypropylene, polybutylene, and polyphenylene sulfide.

9. An apparatus for manufacturing a spunbond nonwoven fabric, the apparatus comprising: a plurality of nozzle units configured and arranged so as to discharge a continuous filament bundle; a collision unit that is adjacent to each of the nozzle units at a position for colliding with the continuous filament bundle jetted by the nozzle units; and a continuous conveyor net that collects and conveys filaments opened by frictional charging with the collision unit, wherein the collision unit comprises a collision surface that is a metal member containing bismuth (Bi) or a bismuth alloy.

10. The apparatus for manufacturing a spunbond nonwoven fabric according to claim 9, wherein the bismuth alloy contains 10% by weight or more of bismuth based on the weight of the bismuth alloy.

11. The apparatus for manufacturing a spunbond nonwoven fabric according to claim 9, wherein the bismuth alloy comprises at least one metal selected from the group consisting of copper (Cu), zinc (Zn), tin (Sn), aluminum (Al), molybdenum (Mo), and titanium (Ti).

12. The apparatus for manufacturing a spunbond nonwoven fabric according to claim 9, wherein the nozzle unit comprises a jet nozzle that discharges the continuous filament bundle, and the jet nozzle is connected to a step motor shaft and is controlled at a nozzle rotation angle ranging from −15±5° to +15±5° and a nozzle reciprocating speed of 3 counters/s to 12 counters/s.

13. A spunbond nonwoven fabric which is obtained by the method according to claim 1, comprises a fiber web containing thermoplastic resin filaments, and has a residual amount of bismuth (Bi) of 0.01 ppmw to 10.0 ppmw.

14. The spunbond nonwoven fabric according to claim 13, wherein the spunbond nonwoven fabric has a residual amount of lead (Pb) of 0.1 ppmw or less.

15. The spunbond nonwoven fabric according to claim 13, wherein the spunbond nonwoven fabric has a quality index (Q) of 350 or less, which is defined by the following Equation 1:
Quality index (Q)=SD/OD  [Equation 1] and in the above Equation 1, OD is the optical density of the spunbond nonwoven fabric measured using a formation tester, and SD is the standard deviation of OD (optical density).

16. The spunbond nonwoven fabric according to claim 13, wherein the thermoplastic resin has a melting point of 200° C. or more, and the thermoplastic resin is at least one resin selected from the group consisting of polyester, polyamide, polyolefin, and polyphenylene sulfide.

17. The spunbond nonwoven fabric according to claim 13 wherein the thermoplastic resin is at least one resin selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polycyclohexane terephthalate, polyethylene naphthalate, nylon, polyethylene, polypropylene, polybutylene, and polyphenylene sulfide.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0123] FIG. 1 schematically shows an apparatus for manufacturing a spunbond nonwoven fabric according to one embodiment of the present invention.

[0124]

TABLE-US-00001 [Description of Reference Numerals] 10: nozzle unit 11: filament bundle 20: collision unit 22: opened filaments 30: conveyor net 33: fiber web

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0125] Hereinafter, preferred examples are provided for better understanding. However, these examples are for illustrative purposes only, and the invention is not intended to be limited by these examples.

Example 1

[0126] A spunbond nonwoven fabric was manufactured using the apparatus according to FIG. 1.

[0127] First, polyethylene terephthalate resin having an intrinsic viscosity (IV) of 0.665 dl/g and a melting point (Tm) of 254° C. was allowed to melt at 284° C., and discharged continuously. The filament bundle obtained by the discharge was discharged through an EDJ (electric distribution jet) nozzle, while being drawn at a speed of 5000 m/min using compressed air and an ejector in the cylindrical pipe of the nozzle unit. The EDJ nozzle was connected to a step motor shaft, and controlled at a nozzle rotation angle ranging from −15±5° to +15±5° and a nozzle reciprocating speed of 10 counters/sec.

[0128] The discharged filament bundle collided at the above speed with the collision unit located at a predetermined angle adjacent to the nozzle unit. A metal member (a metal plate having a thickness of 2.0±0.15 mm) made of bismuth (Bi) was used as the collision surface of the collision unit. At this time, the mass flow rate of the filament colliding with the metal member was 5.0 kg/h per nozzle for jetting the continuous filament bundle, and the linear velocity of the filament was controlled at 5000 m/min.

[0129] The filaments, which have become negatively charged due to frictional charging with the collision unit, fall downward where the conveyor net was located while being opened by the Coulomb repulsive-force between filaments. Negatively charged filaments were seated by electrostatic force on the grounded continuous conveyor net to form a fiber web.

[0130] The fiber web was passed between calender rollers maintained at 130° C. and 35 N/mm to have an appropriate thickness. Then, hot air was applied to the fiber web and was thermally bonded to obtain a spunbond nonwoven fabric (thickness: 0.27±0.03 mm, weight: 60±2.0 g/m.sup.2).

Example 2

[0131] A spunbond nonwoven fabric was obtained in the same manner as in Example 1, except that a metal member made of a bismuth/copper alloy (50 wt. % of Bi, 50 wt. % of Cu) was applied to the collision surface of the collision unit instead of a bismuth metal member.

Comparative Example 1

[0132] A spunbond nonwoven fabric was obtained in the same manner as in Example 1, except that a metal member made of lead (Pb) was applied to the collision surface of the collision unit instead of a bismuth metal member.

Comparative Example 2

[0133] A spunbond nonwoven fabric was obtained in the same manner as in Example 1, except that a metal member made of copper (Cu) was applied to the collision surface of the collision unit instead of a bismuth metal member.

Comparative Example 3

[0134] A spunbond nonwoven fabric was obtained in the same manner as in Example 1, except that a metal member made of tin (Sn) was applied to the collision surface of the collision unit instead of a bismuth metal member.

Comparative Example 4

[0135] A spunbond nonwoven fabric was obtained in the same manner as in Example 1, except that a metal member made of aluminum (Al) was applied to the collision surface of the collision unit instead of a bismuth metal member.

Comparative Example 5

[0136] A spunbond nonwoven fabric was obtained in the same manner as in Example 1, except that a metal member made of zinc (Zn) was applied to the collision surface of the collision unit instead of a bismuth metal member.

Comparative Example 6

[0137] A spunbond nonwoven fabric was obtained in the same manner as in Example 1, except that a metal member made of molybdenum (Mo) was applied to the collision surface of the collision unit instead of a bismuth metal member.

Comparative Example 7

[0138] A spunbond nonwoven fabric was obtained in the same manner as in Example 1, except that a metal member made of titanium (Ti) was applied to the collision surface of the collision unit instead of a bismuth metal member.

Test Example

[0139] (1) Charge Generation Amount (nC/s)

[0140] Using the Faraday cage method, the amount of electrostatic discharge per unit time of the opened filaments was measured.

[0141] Faraday cages are divided into an inner cage and an outer cage. The insulated inner cage was installed so that the filaments 22 opened by colliding with the metal member is confined. The grounded outer cage was installed so as to surround the entire surface of the inner cage. A digital coulomb meter (NK-1002, KASUGA DENKI, Inc.) was brought into contact with the inner cage. A time for which the difference in the amount of charge between the inner cage and the outer cage reached −9000 nC was measured with the digital coulomb meter and normalized by time, thereby obtaining the amount of electrostatic discharge possessed by the opened filaments.

[0142] (2) Opening Width (Mm)

[0143] The opening width formed by the filaments opened by frictional charging with the collision unit was measured. Herein, the opening width means the maximum width based on the moving direction of the opened filaments converged on the continuous conveyor net. The opening width was based on a value indicated by opened filaments obtained from one nozzle unit and a corresponding collision unit. The opening width was expressed as an average value after 10 measurements under the conditions where the rotation angle range of the EDJ nozzle was −15±5° to +15±5° and the reciprocating speed of the EDJ nozzle was counters/s.

[0144] (3) Quality Index (Q)

[0145] Using a formation tester (FMT-III, Manufactured by NOMURA SHOJI CO.), the optical density (OD) and the standard deviation of the optical density were measured through the transmittance of the light from the light source per unit area of the spunbond nonwoven fabric and the distribution of the transmittance (SD). The quality index was calculated according to the following Equation 1.

[0146] The formation tester (FMT-III) is an image analysis type quality analyzer using a two-dimensional CCD camera. The nonwoven sample was placed on a stage illuminated from below. The CCD camera captured an image of 320×230 pixels, and the light intensity was measured by each pixel. A PC connected to a CCD camera converted the light intensity into transmittance (%) and optical density (OD).

[0147] (4) Use Period of Metal Members (Days)

[0148] In the manufacturing process of the spunbond nonwoven fabric, the time point at which perforation in the thickness direction occurs in the metal member (metal plate having a thickness of 2.0±0.15 mm) contained in the collision unit or the time point at which operability deteriorates by the occurrence of unevenness due to wear was measured. At this time, the mass flow rate of the filament colliding with the metal member was 5.0 kg/h per nozzle for jetting the continuous filament bundle, and the linear velocity of the filaments was controlled in the range of 5000 m/min.

[0149] (5) Amount of Inorganic Residue (Ppmw)

[0150] The amount of inorganic residues in the spunbond nonwoven fabric was measured using inductively coupled plasma (ICP). Specimens of spunbond nonwoven fabrics were pretreated with an aqueous solution from which particles and organic material were removed by acid decomposition. The amount of inorganic residues in the specimen was primarily measured using inductively coupled plasma-atomic emission spectroscopy (ICP-AES). When inorganic residues were not detected, re-measurement was performed by increasing the resolution using inductively coupled plasma-mass spectroscopy (ICP-MS).

TABLE-US-00002 TABLE 1 Charge Amount of Material generation Opening Quilityh Use inorganic of metal amount width index period residue member (nC/s) (mm) (Q) (days) (ppmw) Availability Example 1 Bi −3350 610 278 7.3 1.13 ⊚ Example 2 Bi—Cu −1828 530 297 16.5 Bi 0.17, ◯ Cu 0.09 Comparative Pb −2543 540 284 3.8 7.51 Heavy metal Example 1 detected Comparative Cu −925 330 432 41.2 0.57 Defective Example 2 quality Comparative Sn +163 210 603 15.5 0.14 Defective Example 3 opening Comparative Al +179 370 594 — Not Defective Example 4 detected opening Comparative Zn +275 350 681 — Not Defective Example 5 detected opening Comparative Mo +1,440 390 725 — Not Defective Example 6 detected opening Comparative Ti +132 330 656 — Not Defective Example 7 detected opening

[0151] Referring to Table 1, Comparative Example 1 was excellent in quality index and opening width, but residual lead was detected in the nonwoven fabric, making it unsuitable for use as a household chemical material.

[0152] Examples had the quality index and opening width in the same level as those of Comparative Example 1, but no hazardous residues were detected in the nonwoven fabric. Further, it was confirmed that the metal member applied to the examples had a use period of about twice or more compared to Comparative Example 1, and thus the operation capacity was significantly improved.

[0153] It was confirmed that in Comparative Examples 2 and 3, the amount of inorganic residues of the nonwoven fabric was low, but the quality index and opening width were inferior, and that in Comparative Examples 4 to 7, no inorganic residues were detected in the nonwoven fabric, but the opening of the filaments was defective.