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CN-122013332-A - Improved spunbond system and process

CN122013332ACN 122013332 ACN122013332 ACN 122013332ACN-122013332-A

Abstract

An improved spunbond system and process for providing a plurality of fibers from a spinneret, subjecting the fibers to quenching air, attenuating the fibers by a closed draw unit, reducing the velocity of the plurality of fibers in a diffuser spaced from an outlet of the closed draw unit in the direction of travel of the fibers, the diffuser having opposed diverging sidewalls, and subjecting the fibers to an applied electrostatic charge prior to the fibers entering the diffuser, wherein the electrostatic charge is applied by one or more electrostatic charging units.

Inventors

  • B.D. Heines
  • LENNON ERIC EDWARD

Assignees

  • 金伯利-克拉克环球有限公司

Dates

Publication Date
20260512
Application Date
20210305
Priority Date
20200305

Claims (20)

  1. 1. A method of making a nonwoven web, the method comprising: Providing a plurality of fibers from a spinneret; Subjecting the fibers to quenching air; Attenuating the fibers by a closed draw unit using only air from the quench air; reducing the velocity of the plurality of fibers in a diffuser spaced apart from the outlet of the closed draw unit in the direction of travel of the fibers, the diffuser having opposed diverging sidewalls, and Subjecting the fibers to an applied electrostatic charge in the closed draw unit prior to the fibers entering the diffuser, wherein the electrostatic charge is applied by one or more electrostatic charging units, Wherein the enclosed tension unit has a longitudinal width in the channel at a location adjacent the electrostatic charging unit of between 0.6 inches and 2.5 inches.
  2. 2. The method of claim 1, comprising collecting the fibers into a web on a forming surface.
  3. 3. The method of claim 1, wherein the one or more electrostatic charging units are positioned proximate a lower half of the enclosed stretch unit.
  4. 4. The method of claim 1, wherein the one or more electrostatic charging units are positioned proximate an upper half of the enclosed stretch unit.
  5. 5. The method of claim 1, wherein each of the one or more electrostatic charging units generates a voltage between 10 kilovolts and 25 kilovolts.
  6. 6. The method of claim 5, wherein each of the one or more electrostatic charging units generates a voltage between 16 kilovolts and 18 kilovolts.
  7. 7. The method of claim 6, wherein each of the one or more electrostatic charging units generates a current between 0.2 milliamp and 0.8 milliamp.
  8. 8. The method of claim 7, wherein each of the one or more electrostatic charging units generates a current between 0.2 milliamp and 0.6 milliamp.
  9. 9. The method of claim 8, wherein each of the one or more electrostatic charging units generates a current of about 0.4 milliamps.
  10. 10. The method of claim 9 comprising collecting the fibers into a web on a forming surface, wherein the web has a basis weight coefficient of variation between 3% and 3.5%.
  11. 11. The method of claim 10, wherein the plurality of fibers from the spinneret have a density in the MD of 100 to 350 openings per inch in a region orthogonal to the direction of travel of the fibers.
  12. 12. The method of claim 11, wherein the speed of the plurality of fibers in the closed draw unit is between 8000 and 14000 feet per minute.
  13. 13. The method of claim 11, wherein in the machine direction the closed draw unit has a width of between 0.6 inches and 2.5 inches where the static charge is applied to the plurality of fibers in the closed draw unit.
  14. 14. The method of claim 1, wherein the electrostatic charge is applied by two or more oppositely directed electrostatic charging units.
  15. 15. A system, the system comprising: A spinneret configured to provide a curtain of fibers; A closed draw machine configured to pneumatically attenuate the fiber curtain using only air from the quench air; An electrostatic charging unit located at a charging location along the closed draw machine and configured to apply an electrostatic charge to the fibers at the charging location, wherein the fiber curtain has a first width defining a width of the fiber curtain in a longitudinal direction at a first location along the closed draw machine and a second width greater than the first width, defining a width of the fiber curtain in the longitudinal direction at the charging location, wherein the first location is closer to the spinneret than the charging location; A diffuser having a set of opposed diverging walls and configured to receive the fiber curtain from the closed draw machine and reduce the speed of the fiber curtain, and A forming surface configured to move in the longitudinal direction and collect the curtain of fibers exiting the diffuser; wherein the enclosed tension unit has a longitudinal width in the channel at a location adjacent the electrostatic charging unit of between 0.6 inches and 2.5 inches.
  16. 16. The system of claim 15, wherein each of the one or more electrostatic charging units generates a voltage between 10 kilovolts and 25 kilovolts.
  17. 17. The system of claim 16, wherein each of the one or more electrostatic charging units generates a voltage between 16 kv and 18 kv.
  18. 18. The system of claim 17, wherein each of the one or more electrostatic charging units generates a current between 0.2 milliamp and 0.8 milliamp.
  19. 19. The system of claim 18, wherein each of the one or more electrostatic charging units generates a current between 0.2 milliamp and 0.6 milliamp.
  20. 20. The system of claim 19, wherein each of the one or more electrostatic charging units generates a current of about 0.4 milliamps.

Description

Improved spunbond system and process The application is a divisional application with the application number 2021800170994, the application date 2021, 3 and 5 and the name of 'improved spunbonding system and process'. The present application claims priority and benefit from U.S. patent application Ser. No. 62/985712, entitled "Improved Spunbond SYSTEM AND Process," filed 3/5/2020, the entire contents of which are incorporated herein by reference. Technical Field The present invention relates to a method for forming a nonwoven web and an apparatus for forming such a web. Background Many personal care products, medical care garments and products, protective apparel, mortuary and veterinary products in use today are composed partially or wholly of nonwoven web materials. Examples of such products include, but are not limited to, consumer and professional medical and health care products such as surgical drapes, gowns and bandages, protective gowns, e.g., protective coveralls and laboratory gowns, and infant, child and adult personal care absorbent products such as diapers, training pants, swimwear, incontinence garments and pads, sanitary napkins, wipes, and the like. Nonwoven web materials are also widely used as filter media for liquid and gas or air filtration applications because they can form filter screens of fine fibers having a low average pore size suitable for capturing particulate matter while still having a low pressure drop across the screen. Nonwoven web materials have a physical structure of individual fibers or filaments that are interwoven in a generally random manner, rather than in a regular, identifiable manner as in knitted or woven fabrics. The fibers may be continuous or discontinuous and are typically made from thermoplastic polymer or copolymer resins from the general classes of polyolefins, polyesters and polyamides, as well as many other polymers. Blends of polymers or combination multicomponent fibers may also be employed. Nonwoven fibrous webs formed by melt extrusion processes such as spunbonding and meltblowing, and nonwoven fibrous webs formed by dry-laid processes such as carding of staple fibers or air-laid. Melt extrusion processes for spinning continuous filaments or fibers (such as spunbond fibers) and for spinning microfibers (such as meltblown fibers) and related processes for forming nonwoven webs or fabrics therefrom are well known in the art. Typically, fibrous nonwoven webs, such as spunbond nonwoven webs, are formed using fiber extrusion equipment (such as spinnerets) and fiber attenuation equipment oriented in the cross-machine direction or "CD". That is, the apparatus is oriented at a 90 degree angle relative to the web production direction. The direction of nonwoven web production is referred to as the "machine direction" or "MD". Although the fibers are laid down on the forming surface in a generally random manner, the resulting nonwoven web has an overall average fiber directionality as the fibers leave the CD oriented spinneret and attenuator and are deposited on the MD moving forming surface, with more fibers oriented in the MD than in the CD. It is well known that properties such as material tensile strength, extensibility, and material barrier properties are a function of material uniformity and directionality of fibers or filaments in the web. Thus, fine control of material uniformity and fiber directionality in nonwoven webs is highly desirable. Disclosure of Invention In general, one aspect of the subject matter described in this specification can be embodied in methods that include providing a plurality of fibers from a spinneret, subjecting the fibers to quenching air, attenuating the fibers by a closed draw unit, reducing the speed of the plurality of fibers in a diffuser spaced apart from an outlet of the closed draw unit in a direction of travel of the fibers, the diffuser having opposed diverging sidewalls, and subjecting the fibers to an applied electrostatic charge prior to the fibers entering the diffuser, wherein the electrostatic charge is applied by one or more electrostatic charging units. Other embodiments of this aspect include corresponding systems and devices. Another aspect of the subject matter described in this specification can be embodied in a system that includes a spinneret configured to provide a curtain of fibers, a closed-type stretcher configured to pneumatically attenuate the curtain of fibers, an electrostatic charging device located at a charging location along the closed-type stretcher and configured to apply an electrostatic charge to the curtain of fibers at the charging location, wherein the curtain of fibers has a first width that defines the curtain of fibers in a longitudinal direction at a first location along the closed-type stretcher and has a second width that is greater than the first width, and a width of the curtain of fibers in the longitudinal direction at the charging location, wherein the first location is