Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
  • D01D5/00—Formation of filaments, threads, or the like
  • D01D5/42—Formation of filaments, threads, or the like by cutting films into narrow ribbons or filaments or by fibrillation of films or filaments
  • D01D5/423—Formation of filaments, threads, or the like by cutting films into narrow ribbons or filaments or by fibrillation of films or filaments by fibrillation of films or filaments
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
  • D01D5/00—Formation of filaments, threads, or the like
  • D01D5/42—Formation of filaments, threads, or the like by cutting films into narrow ribbons or filaments or by fibrillation of films or filaments

Definitions

• This invention relates to the improved manufacture of fibrillated material webs, and particularly to pinned rollers suitable for making fibrillated film from polyolefin base resins for filter material. More particularly, this invention relates to an improvement on the methods and apparatus of U.S. patent 3,880,173, the disclosure of which is hereby incorporated by reference.
• patent 3,880,173 and corresponding U.K. Patent 1,442,593 refer to obtaining fibrillated polyolefin film materials for filter materials as an alternative to cellulose acetate filter materials, specifically, but not exclusively, for filtering tobacco smoke of smoking articles.
• the polyolefin materials described include polypropylene, polyethylene, or a mixture thereof, or a copolymer of propylene and ethylene, and optionally may include finely divided whitener such as titanium dioxide to facilitate the production of narrow fibrous strands.
• the polyolefin stock materials are heated, mixed, and extruded into a thin film.
• the film is blown to form thinner films which are flattened, slit lengthwise, and superimposed to form multiple thin film layers of about 10-15 ⁇ thick.
• the multiple layers are passed through an oven at elevated temperatures while being stretched over differential speed rollers to orient the molecular structure of the films in the longitudinal direction.
• the oriented film is then passed over a rotating roller having a plurality of pins projecting therefrom.
• the pinned roller rotates at a surface speed that is faster than the linear speed of the web.
• the pins projecting from the roller thus contact and fracture the relatively slower moving superimposed layers, thereby producing an interconnected web of fibers having free ends that is the fibrillated material.
• the fibrillated material is then passed into a stuffer box crimper device in a conventional manner to create crimps in the fibrillated film, thus forming a polyolefin tow.
• the crimps include primary crimps, the creation of a wavy configuration in the fibers caused by rapid deceleration of the advancing fibers, and a secondary crimp, corresponding to a wrinkling effect when the fibers collapse and fold in on themselves.
• the secondary crimp is typically removed from the polyolefin tow, for example, by tension, and the tow is formed into a bloomed flocculent mass which is then formed into a filter rod by using a conventional filter rod making machine.
• a binder agent e.g., vinyl acetate, may be included in the tow for forming filter rods in a known manner.
• One problem with the known fibrillated polyolefin materials is that, although they may have filtering characteristics comparable to cellulose acetate filters, they do not have the low mass that is required to provide a cost advantage. Another problem is that known tows do not have a consistent, quality fibrous network that allows for use in a filter tow material where relatively short lengths of tow are used. Another problem is that the known apparatus for producing the fibrillated network consumes a substantial amount of power and generates a substantial amount of noise to create the interconnected fiber network.
• a filter for smoking articles comprising a fibrillated polyolefin material that provides the advantages and benefits associated with conventional cellulose acetate filter materials used in smoking articles, and particularly, tobacco-containing cigarettes.
• an improved roller having pins projecting from the surface (“pinned roller”) and a method of using such pinned rollers for impacting advancing oriented polyolefin film materials to fracture the film into a network of fibrillated strands.
• the invention concerns rollers having a plurality of substantially uniformly dimensioned pins distributed around the roller surface in a defined pattern, which pins project from the roller surface at an angle within a range of angles relative to a tangent, and a method of using such pinned rollers to impact the advancing film in an advantageous manner to result in a fibrillated material having substantially
• a pinned roller having pins projecting from the surface in particular patterns spaced about the pin surface, at an angle in a range of from about 40 to about 75 degrees relative to the tangent of the roller directed opposite to the rotation of the roller, and at a pin density of from about 15 to about 100 pins per inch, the pins being from about 0.2 to about 0.8 mm in diameter.
• the pin patterns of the present invention include a plurality of rows of pins, where each row has pins arranged in a space-staggered relationship, i.e., staggered along a pair of parallel lines
• the double rows of pins are preferably equidistantly spaced about the circumference of the roller surface to present a consistent pattern.
• the density of pins in each row is from about 25 to about 34 pins per inch (ppi), staggered across the two lines, more preferably about 25 ppi.
• the rows of pins extend across the roller surface on lines inclined to lines parallel to the roller axis with immediately adjacent rows being oppositely inclined.
• the rows may extend on lines parallel to the axis of the roller, but having a sinusoidal pattern, as contrasted with a linear pattern, with immediately adjacent, spaced apart, sinusoidal rows being either arranged in phase or out of phase across the roll, the waveforms having a wavelength of from, about 15 to about 40 mm and an amplitude of from about 2.0 to about 6.0 mm.
• the advantageous pin patterns provide surprisingly improved fibrillated materials when the oriented, unfibrillated film is placed in contact with the pinned roller for an arc of from about 20 degrees to about 45 degrees, and where the relative linear speeds of the roller surface and the advancing film, known as the fibrillation ratio, is in a range of from about 1.6:1 to about 3.4:1, the fibrillation ratio being defined by the following expression:
• Tow Yields for fibrillated polyolefin materials made by the present invention that are formed into filter lengths using conventional filter rod making equipment such as that used for forming cellulose acetate tow into filter materials. Tow Yields are obtained from the following expression:
• Tow Yield Net Weight of Fiber x 100%.
• the Net Weight is measured in units of milligrams for a given length of filter rod.
• the pressure drop is measured in millimeters of Water Gauge at an airflow of 1,050 ml per minute through the net weight of rod.
• Higher Tow Yields correspond to more randomly dispersed free ends, and better filtration capacity for the fibrous strand network per net weight, and hence more efficient use of the polyolefin materials.
• Fig. 1 is an elevated perspective view of a pinned roller of the present invention
• Fig. 2 is a front partial view the roller of Fig. 1;
• Fig. 3 is an enlarged side sectional view taken along line 3-3 of Fig. 2;
• Fig. 4 is a front view of a second embodiment of the roller of the present invention.
• Fig. 5 is a front partial view of a third embodiment of the roller of the present invention.
• Fig. 6 is a schematic illustration of a roller of the present invention contacting a polyolefin film in accordance with the present invention. Detailed Description of the Invention
• illustrative embodiments of this invention include pinned roller 10 adapted for contacting an advancing film of unfibrillated material 20 over an arc length of the roller surface 12, impacting film 20 thereby fracturing the material to form fibrillated film 22.
• roller 10 is about 190 mm in diameter and about 115 mm long. Approximately 100 mm of the surface width, a width sufficient to contact the entire width of the advancing film of about 50 to 90 mm, contains pins 16. Pins 16 are spaced in staggered relationships in rows 14 of parallel pairs of lines 15a and 15b extending across the face of roller 10 on a line inclined to the axis of roller 10, arranged so that immediately adjacent rows are oppositely inclined, presenting a chevron configuration.
• Fig. 1 only rows 14 are shown to represent pins 16 being distributed in staggered relationship along two parallel lines 15.
• the pattern repeats itself around the surface of roller 10, and, for a roller about 190mm in diameter, there are preferably about 90 double rows equally spaced apart, for a total of 180 lines of pins 16.
• the centers of the two parallel lines 15a and 15b, corresponding to the two parallel lines of pin 16, are spaced apart a distance of about 0.05 inches (1.27mm).
• distance between the oppositely inclined rows 17 and 18 is about 0.1 inches (2.54 mm) at the ends closest together and about .375 inches (9.53mm) at the ends that are further apart.
• the chevron pattern is such that the point of intersection of the oppositely inclined rows would occur off roller surface 12, forming an angle of about 4.0 degrees.
• the centers of the parallel lines 15 are indicated by solid lines, and individual pins 16 are represented by perpendicular dashes.
• the pin density is about 25 pins per inch, distributed in a staggered relationship between the two parallel lines.
• a pin pattern is shown.
• the rows 14 of pins 16 are arranged in a sinusoidal pattern across a line parallel to the axis of roller 12, with immediately adjacent rows of pins also being in a sinusoidal pattern in phase.
• a frequency of about 1.12 inches (28.45 mm) and an amplitude of 0.125 inches (3.175 mm) are used.
• the distance between the parallel sinusoidal line centers 15a and 15b is about .05 inches (1.27 mm), and the row pin density is about 25 pins per inch.
• the distance between adjacent rows 14a and 14b is about 6.63 mm measured from corresponding zero amplitude to zero amplitude locations around the circumferential surface of the rolls.
• FIG. 5 an second alternate embodiment of a sinusoidal pin pattern is shown.
• the immediately adjacent parallel rows 14 of pins 16 are arranged 180° out of phase, having a frequency of about 1.12 inches (28.45 mm) and an amplitude of 0.125 inches (3.175 mm).
• the distance between the parallel sinusoidal line centers 15a and 15b in each pair of staggered rows 14 of pins 16 is about .05 inches (1.27 mm), and the pin density is about 25 pins per inch.
• immediately adjacent rows 14a and 14b is about 6.63 mm measured from corresponding zero amplitude to zero amplitude locations around the circumferential surface of the rolls.
• pins 16 protrude from surface 12 at an angle of approximately 60° relative to the tangent to roller 10 in the opposite direction to that of the rotation of the roller, as designated by angle A.
• the length of projection of pins 16 is approximately 1.0 mm measured perpendicular to a tangent to the roll surface to the pin tip and the pins have a diameter of approximately 0.483mm.
• roller 10 is adapted for inclusion in conventional apparatus for fibrillating advancing films of oriented material.
• Unfibrillated and oriented film 20 is advanced at a selected rate of speed, for example, a rate in a range from about 120 to about 250 meters per minute. Roller 10 is rotated in the same direction as film 20, but at a faster rate so that pins 16 rake along film 20., thereby causing pins 16 to fracture film 20 to form fibrillated film 22.
• Preferred fibrillation ratios are in the range of from about 1.2 to about 2.8, more preferably about 1.8 to about 2.2.
• Film 20 is in contact with roller 10 only for a selected arc length that is controlled to be within a range of from about 20 to.about 45 degrees, preferably about 37 degrees.
• Guide roller 24 may be used to control the amount of arc length of contact and the tension of film 20.
• Film 20 is to held against roller 10 with enough tension so that it will not ride on top of pins 16, and at least some portions of the film will contact surface 12 of roller 10 as the fibrous network is created. Typical amounts of tension necessary to accomplish this are in a range from about 800 to about 1000 pounds (350 to about 450 kgf).
• the polyolefin films were prepared from following blend:
• melt index 1.8 230° C, 2.16 Kgf
• melt index 1.0 (190°C, 2.16 Kgf);
• masterbatch containing 25% titanium dioxide (rutile grade, fine crystel structure, micronized grade).
• the processing parameters for advancing the film, contacting the film with the pinned roller, the pinned roller characteristics, and the results of the evaluation of the fibrillated material after it has been crimped are set forth in Table I.
• the pinned roller used had a diameter of 190mm at the roller surface, and the angle of rake of the pins was 60 degrees (relative to the tangent).
• the fibrillated material was then formed into a filter rod using conventional filter rod forming apparatus, for example, model KDF-2 manufactured by Hauni Maschinene Korber & Co., Hamburg, Germany, wherein the tow is formed into a bloomed flocculent mass having the identified crimp characteristics, and processed by the filter making apparatus into a filter rod having a circumference of 24.55mm and a length of 66mm.
• filter rod forming apparatus for example, model KDF-2 manufactured by Hauni Werke Korber & Co., Hamburg, Germany
• the results of the evaluation of the filter material constructed from the fibrillated material of the examples are set forth in Table II.
• the low yield and high yield values respectively correspond to the minimum point and the maximum point on the capability curve, which curve compares relative pressure drop for changes in the net weight of tow material in a uniformly dimensioned filter rod. All of these examples provided a tow yield that reflected a significant improvement over the fibrillated polyolefin filter rods obtained by prior known methods and apparatus and over conventional cellulose acetate filters which prior known materials have yields of from about 35% to about 72% for cellulose acetate.
• Example 2 was more uniform and of a constant nature than the drive current for the roller having
• Example 1 This indicates a more uniform fibrillation may be achieved by using sinusoidally pinned fibrillating rolls. Examination of the fibrillated tow band produced by Examples 1 and 2 along their longitudinal axes revealed fewer unfibrillated strips, i.e., areas where pin penetration of the films had not occured, in Example 2 as compared to Example 1. This confirms the improved fibrillation.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Textile Engineering (AREA)
• Cigarettes, Filters, And Manufacturing Of Filters (AREA)
• Treatment Of Fiber Materials (AREA)
• Paper (AREA)
• Preliminary Treatment Of Fibers (AREA)
• Shaping Of Tube Ends By Bending Or Straightening (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Nonwoven Fabrics (AREA)

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Applications Claiming Priority (2)

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Citations (6)

• 1989
  • 1989-08-07 ZA ZA896002A patent/ZA896002B/xx unknown
  • 1989-08-07 ZW ZW91/89A patent/ZW9189A1/xx unknown
  • 1989-08-08 JP JP1508988A patent/JPH04500100A/ja active Pending
  • 1989-08-08 WO PCT/GB1989/000905 patent/WO1990001574A1/en active Application Filing
  • 1989-08-08 AU AU40781/89A patent/AU4078189A/en not_active Abandoned
  • 1989-08-08 EP EP89308042A patent/EP0358334A1/en not_active Withdrawn
  • 1989-08-08 DD DD89331586A patent/DD298595A5/de not_active IP Right Cessation
  • 1989-08-08 HU HU895180A patent/HUT59448A/hu unknown
  • 1989-08-08 BR BR898907600A patent/BR8907600A/pt unknown
  • 1989-08-08 KR KR1019900700736A patent/KR900702091A/ko not_active Application Discontinuation
  • 1989-08-09 YU YU01575/89A patent/YU157589A/xx unknown
  • 1989-08-09 CN CN89105538A patent/CN1040734A/zh active Pending
  • 1989-08-09 CS CS894739A patent/CS473989A3/cs unknown

Patent Citations (6)

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