US 3354013 A
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Description (OCR text may contain errors)
NOV. 21, 1967 R, 1 ET AL 3,354,013
METHOD AND APPARATUS FOR APPLYING FARTICULATE ADDITIVES TO CONTINUOUS FILAMENT TOW Filed Nov. 26, 1963 2.Sheets-Sheet 1 ROBERT LOWELL TERRELL JOEL BARTLETT STEVE/V8 INVENTOR.
ATTORNEYS NOV. 21, 19 67 L, TERRELL ET AL 3,354,013
METHOD ANDAPPARATUS FOR APPLYING PARTICULATE ADDITIVES TO CONTINUOUS FILAMENT TOW Filed Nov. 26, 1963 2 Sheets-Sheet 2 TAR REMOVAL- Robert Lowell Terrell Joel Bartlett Stevens INVENTORS r1", WM aemum' ATTORNEYS United States Patent 3,354,013 METHOD AND APPARATUS FOR APPLYING PAR- TICULATE ADDITIVES TO CONTINUOUS FILA- MENT TOW Robert L. Terrell and Joel B. Stevens, Kingsport, Tenn., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Nov. 26, 1963, Ser. No. 326,095 6 Claims. (Cl. 156-152) This invention relates to a method and apparatus for applying particulate additives to continuous filament tow.
More particularly, it relates to a system for applying par-- a volatile organic vehicle or plasticizer for the filaments,
blowing onto the filaments in particulate form, introducing the additive by means of a latex emulsion and spraying as a powder onto filaments wet with an adhesive or plasticizer. In US. 2,881,770 Touey also refers to a method of applying powder to fibers electrostatically, that is, by inducing a charge on the fibers by friction or other suitable means and then running the fibers through a chamber containing a highly concentrated dust. Although these methods have proved highly successful, several problems related to the application of particulate matter to continuous filament tow have thus far remained unsolved. For instance, no one has heretofore shown how to effectively eliminate undesirable dust or how to apply the additive satisfactorily in a substantially uniform manner. Also, there has remained some room for improvement with respect to devising a less elaborate and costly apparatus for particulate treatment of the tow. Therefore, provision of a method and apparatus for applying particulate additives to continuous filament tow in a substantially uniform manner and with accumulation of a minimum amount of lint and dust represents a highly desirable result. After extended investigation, we have devised such a system.
. One object of this invention is to provide an improved method and apparatus for applying particulate additives to continuous filament tow. Another object is to provide a system of adding particulate matter to continuous filament tow in a substantially uniform manner such that .filter elements manufactured therefrom will have improved =efliciency in removing undesirable materials from the tobacco smoke of cigarettes and the like whereon such elements are used. A further-object is to provide a simplified system of improved economy for applying additives in the form of small particles to continuous filament tow,
as exemplified by cellulose ester tows, useful in the production of tobacco smoke filters and the like. Other objects will appear hereinafter.
In its broader aspects our invention involves introducing a gaseous stream upwardly into the additive to thereby form a fluidized bed and reduce the effective bulk density thereof while simultaneously conducting a band of continuous filament tow through said bed. Additives which may be applied to the tow from such a mass by the introduction of motivating gas such as air, carbon dioxide, nitrogen or the like include activated carbon, silica, activated alumina, molecular sieves, calcium carbonate, rice starch, corn starch, wheat flour, powdered sugar and the like. Preferred in order of preference are activated carbon, corn starch and calcium carbonate. The porous bottom of the particle mass may comprise a diffuser plate. This may consist of a material in which the minute orifices are irregularly scattered as in pressed cane board or the like such as used in the construction of homes. The rate of addition of additive to the diffused mass of particulate matter may be varied so as to maintain a constant level dependent upon the amount of additive deposited on the tow as it passes through at the desired rate. A screw feeder may be used for this purpose. The tow may be passed appropriately over and under rolls located just above the mass while the additive is .being applied thereto. The mass of additive particles is preferably located within an enclosed structure such as a chamber.
For a further understanding of the invention, reference will now be made to the drawing, which forms a part of this specification.
In the drawing:
FIG. 1 is a schematic representation depicting the tow treating apparatus arrangement of this invention.
FIG. 2 is a graph showing the increased tar removal found for filter rods prepared from tow to which additive is applied according to this invention.
In FIG. 1, tow 10 is moved from a bale or other suitable source 12 and passed by Way of banding jet 14 around guide 16 prior to passing between pretension rolls 18. The tow next passes between blooming rolls 20 and 22, one of which may be configured, as with squarenotched parallel longitudinal grooves. The blooming step is more specifically described in Ser. No. 259,852, filed Feb. 20, 1963, of our coworker Fritz now Patent No. 3,255,506. After being bloomed, the tow may pass through a second banding jet 24.
Bonding agent is applied to the tow as it passes between plasticizer applicator rolls 28 and 30 prior to entering the particulate mass of fluidized bed 32. The mass of particulate matter of :bed 32 is preferably contained in an enclosed structure 34. The proper additive level may be maintained by introducing the particles through conduit 36 such as, for example, by feed screw 38. The particulate substance is applied to both sides of the tow by passing the tow around rolls 39, 40 and 42, after which the tow is removed from the bed 32 and may then be delivered by passing between the nip of delivery rolls 46 and 48 to garniture or other suitable filter forming means 50.
The additive chamber 34 may be provided with an exhaust channel 54. Inert gas is introduced by a conduit 56 below the bottom of the particulate mass of bed 32 through an appropriate porous substance such as a diffuser plate 58in such a way as to stir it up evenly for application substantially uniformly to both sides of the tow passing through the mass 34. The particulate mass of bed 32 may be enclosed in a chamber 32 to help maintain cleanliness and control oxygen content of the atmosphere over the tow and additive.
The amount of additive picked up by the tow is around of bed 32.
20% to 150% based on the Weight of the tow. The amount of additive applied may be varied by changing the density of the particulate mass, the length of tow travelled therethrough, the average particle size, the tow speed, the tow filament size or the bonding agent content of the tow. A bonding agent may be used on the tow to improve the uniformity of additive pick-up. Use of bonding agent may also be of some help in minimizing subsequent loss of additive and increasing the firmness of filter elements formed in graniture 58. Scraper bars (not shown) may be used to increase the uniformity of additive distribution on the tow after it emerges from the particulate mass -In' FIG. 2 the pressure drop in inches of water for 102 X 24.8 mm. filter elements to which additive has been applied isplotted against the percent tar removal. All samples contained 5 denier per filament (d./f.), 60,000 total denier (t.d.) tow. It is readily apparent that at all pressure drop levels the percent tar removal was greater for the filter elements to which additives were applied by the gas-propelled particle system of this invention than for the prior art system, which in this instance was a dust booth which applied rice starch. Near the graph line for additive applied according to this invention the various sample values are shown as dotted circles, solid circles, squares and triangles. The dotted circles represent samples using 100% corn starch, the solid circles a 50/ 50 corn starch/calcium carbonate mixture, the squares 65/35 corn starch/calcium carbonate, and the triangles 75/25 corn starch/ calcium carbonate.
The following examples are illustrative of our invention.
Example I A5 d./f., 60,000 t.d. cellulose acetate tow was bloomed using the apparatus arrangement of FIG. 1 and passed through a mass of activated carbon to which air was supplied from the bottom through a heterogeneously perforated plate. No bonding agent was applied to the tow. The activated carbon was 30 x 140 mesh in particle size and was made from coconut shell. Filter rods were made which were composed of 0.835 gram cellulose acetate and 0.450 gram activated carbon and were 102 mm. in length and 24.8 mm. in circumference. A 1-7-mm. portion of this filter rod was afi'ixed to a 68-mm. cigarette and smoked on an automatic smoking machine which produced a 35 ml. puff of 2 seconds duration at the rate of 1 putt per minute. The smoke which passed through the filters was collected and analyzed for its acetaldehyde and isoprene content. This filter removed 92% of the acetaldehyde and 98% of the isoprene emitted by the cigarette during the third pufi.
Example 11 A 5 d./f., 60,000 t.d. cellulose acetate tow was bloomed using the apparatus arrangement of FIG. 1, and 0.040
circumference was made which contained 0.804 gram cellulose acetate tow and'0.368 gram activated carbon. Removal efiiciency' measured as in Example I of a 17 mm. tip from this filter was 90% for acetaldehyde and 96% Example 111 A 5 d./f., 50,000 t.d. cellulose acetate tow was bloomed using the apparatus arrangement of FIG. 1, bonding agent being applied, and the tow passed through a diffused mass containing a mixture of 75% rice starch and 25% corn starch. Inert gas was continuously introduced upwardly through pressed cane board, which served as the lower boundary of the particulate mass. A filter rod made from the tow thus treated contained 76.2% cellulose acetate by weight, 16.3% .starch, and 7.5% triacetin. Tar removal i v .(7) a pair of delivery rolls etficiency was 50% at a rod pressure of 14 inches of water.-
Example IV 5 d./i. Percent Tar Removal Additive Pressure Dust This No Drop Booth Invention Additive Do. 11.3 37 39 28 50/50 Staroh/CACO3. 11.9 54 30 65/35 Starch/GACO3 13.0 54 33 75/25 Starch/CAOOQ. 13.2 52 33 From the foregoing description and examples it is believed apparent that we have provided a method and apparatus whereby particulate additive may be distributed substantially uniformly over continuous filament tow by passing a gaseous medium upwardly through a mass of the additive, the gaseous medium being introduced to the mass through a heterogeneously porous surface over substantially its entire surface. By our system the effect of bulk density of the additive is reduced and the tow is enabled to pass through the treatment zone with a minimum of resistance.
Although the invention has been described in considerable detail with reference to certain preferred embodiments thereof, it will be understood that variations and modifications can be effectedwithout departing from the spirit and scope of the invention as described hereinabove and as defined in the appended claims.
We claim: Y
1. Apparatus for applying particulate additives to tow comprising an enclosed chamber, means for introducing particulate additive to said chamber and maintaining same as a mass in the lower portion of said chamber, means for introducing gas to the bottom of said-chamber, a diffuser plate positioned parallel to the bottom of said chamber somewhat above said bottom, a plurality of rolls located in the mass portion of said chamber and'adapted for movement of a band of tow therearound, and a pair of delivery rolls located in the upper portion of said chamber adapted to remove tow from the mass port-ion of said chamber and for conducting same from said chamber to collecting means.
2. Apparatus arrangement for production of tobacco smoke filter elements comprising in cooperative association:
(1) tow bale source of tow,
(2) fluid jet banding means,
(3) a pair of pretension rolls adapted to apply tension to the tow prior to blooming,
(4) a pair of blooming rolls, one of said rolls being configured with a plurality of square slots running in a parallel pattern around the circumference of said roll and being of substantially equal size, said pair of rolls being adapted for passing tow therethrough and blooming same, I
(5) a pair of delivery rolls with means for applying bonding agent to thesurface of each, said rolls being adapted to apply bonding agent to both surfaces of the tow from the surfaces by passage through the nip formed therebetween, V
(6) an enclosed chamber adapted for passage of tow therethrough and having positioned therein a diffuser plate of heterogeneous porosity positioned slightly above the bottom thereof, said plate being adapted for introduction of gas upwardly therethrough,
located in said chamber forremoval 9r tow from said chamber, and' (8) in juxtaposition with said chamber filter element forming means.
3. A process for the application of additives to filamentary material which comprises feeding the material from a source of supply, applying a bonding agent to said material, retaining the additive in an enclosed chamber, forming a fluidized bed by passing a gaseous medium upwardly into the chamber through said additive, and circuitously passing said filamentary material through said bed so that a substantially uniform amount of additive becomes adhered to the material.
4. The process according to claim 3 wherein the said filamentary material is in tow form and is banded and bloomed prior to the addition of the bonding agent thereto.
5. The process according to claim 3 wherein the bed is maintained at a substantially constant level and density by the addition of particulate additive thereto.
6. The process according to claim 4 wherein the said tow is subsequently fed to a filter forming device.
References Cited UNITED STATES PATENTS 15 EARL M. BERGERT, Primary Examiner.
M. L. KATZ, Assistant Examiner.