US3238852A - Method and apparatus for making filters - Google Patents

Description

March 8, 1966 Q sc u ETAL 3,238,852

METHOD AND APPARATUS FOR MAKING FILTERS Original Filed Oct. 5, 1954 2 Sheets-Sheet 2 KXXXRX K XXXXXX XXXXXKX INVENTORS: MILTON O. SCHUR JAMES C. RICKARDS A TTORNE! United States Patent 3,238,852 METHOD AND APPARATUS FOR MAKING FILTERS Milton Oscar Schur, Asheville, and James C. Richards, Brevard, N.C., assignors, by mesnc assignments, to Olin Mathieson Chemical Corporation, a corporation of Virginia Original application Oct. 5, I954, Ser. No. 450,355. Divided and this application June 2, 1965, Ser. No. 477,991

Claims. (Cl. 93-1) This application is a division of co-pending application Serial No. 460,355, filed October 5, 1954.

This invention relates generally to smoking devices and more particularly to a method and apparatus for making filters for such devices and to an improved filter for tobacco smoke.

It has been proposed heretofore to provide cigarettes and other smoking devices with a filter for the tobacco smoke. It has also been proposed to manufacture such filters by passing a continuous web of crepe paper or other compressible material into a forming cone which laterally gathers and compresses the web into cylindrical form having draft passages therethrough, for example, as described by Davidson in US. Patent 2,164,702, issued July 4, 1939. Although such a process has many advantages over other methods for making tobacco smoke filters, it has not been entirely suitable, especially in the manufacture of filters having resistance to the fiow of smoke appreciably greater than that of an equal length of the rod of tobacco comprising the cigarette proper, because the gathered and compressed web of material is difficult to enclose within a suitable wrapper at high speed production. It has been found that the compressed web exerts an internal pressure against the wrapper sufliciently high so that consequently it is very difficult to seal the overlapping edges of the wrapper at economic rates of production. As a result, a larger percentage of the product may have poorly sealed Wrappers or may be too variable in circumference. Poorly sealed or oversized rods cannot be utilized successfully in the machine which encloses the filter tip and tobacco within a Wrapper to form a cigarette because of frequent jamming of the machine; and variable circumference of the filter tip gives trouble in the production of uniform filter-tipped cigarettes.

These disadvantages are partially overcome if prior to the formation of the filter rods the paper web is slit in the manner disclosed by Davidson in the aforesaid patent, but the slitting of the paper into ribbons in accordance with the method disclosed by Davidson introduces a number of serious production problems. For instance, it is very difficult, if not impossible, satisfactorily to enclose a plurality of such smooth edged ribbons within a wrapper at high speeds without the occasional breaking of strands between the slitters and forming tube. Further, the slitters require frequent and close attention, for should only one of the numerous cutters required become dull or nicked, the paper may tear and cause serious trouble.

It is an object of this invention to provide an apparatus and method for making filters for smoking devices which are devoid of the foregoing disadvantages. Another object of the invention is to provide an apparatus and method for making a more efficient filter than the heretofore available filter formed from a single continuous web or the filter from a plurality of ribbons of compressible filter material. Still another object of the invention is to provide a more effective filter for cigarettes than heretofore known filters formed from compressible material.

Other objects will become apparent from the follow- Patented Mar. 1966 ing description with reference to the accompanying drawing in which:

FIGURE 1 is a diagrammatical perspective view illustrating an embodiment of this invention;

FIGURES 2 and 3 are illustrations of typical superimposed rolls suitable 'for use in the embodiment of FIG- URE 1;

FIGURE 4 is a fragmentary enlarged view showing the relative position of the web and the contacting surfaces of the rolls of FIGURE 2;

FIGURE 5 is an enlarged view of the surface of one of the rolls in FIGURE 3;

FIGURE 6 is a fragmentary sectional view taken along line CC of FIGURE 5;

FIGURE 7 is a fragmentary view of a web of compressible material stretched laterally to illustrate to best advantage the effect of treating a web of paper with rolls illustrated in FIGURE 2;

FIGURE 8 is an enlarged View of that portion of FIG- URE 1 lying between the lines A-A and BB;

FIGURE 9 is a fragmentary view of a web of compressible material after compression between rolls of the type illustrated in FIGURE 3;

And FIGURE 10 is a partially sectioned perspective view of a cigarete having a filter embodying the present invention.

Generally speaking, the foregoing objects as well as others are accomplished in accordance with this invention by longitudinally feeding a web or strip of compressible material of substantially indefinite length, tearing the web into ragged edged shreds, thereafter laterally gathering and compressing the web into a rod and subdividing the rod into lengths. It is prefered to loosen the fibers of the compressible material by embossing and to thereafter form discontinuous relatively closely spaced longitudinal rents therein throughout the length in order to produce a web most suitable for laterally gathering and compressing into cylindrical form.

It has been found in accordance with this invention that in filter rods of a given draw or resistance to flow of smoke the internal pressure of the gathered and compressed material having the rents therein is much less than when an untorn web of similar material is used and that the torn web can be successfully enclosed Within a suitable wrapper without the serious production difificulties caused by the overlapping edges of the wrapper not being tenaciously bound together when the rod-making machine is run at commercial speeds. Consequently, the filter rods formed in accordance with this invention can be assembled with tobacco within a wrapper to form cigarettes on conventional cigarette making machines with less difficulty and expense than filter rods formed from a single untorn web of compressible material enclosed within a Wrapper having unbound overlapping edges. Moreover, it has been found that less of the compressible material is required to form an effective filter if the web thereof has been torn or pulled apart prior to the gathering and compressing steps. Furthermore, such a filter of increased effectiveness requires less of the compressible material to impose a given resistance to the flow of smoke through the filter than would be required to impose a similar resistance if untorn compressible material was utilized. This is an advantage in the manufacture of filters because it enables the production of filters from less of the compressible material and thus at a reduced cost. The torn web because of the ragged, fuzzy edges of the torn portions does not present the problem involved in Wrapping a plurality of smooth edged ribbons, for there is a tendency for the opposing ragged edges of the shreds to intermesh and to hold the plurality of shreds together into what is essentially a single web.

Referring to FIGURE 1 of the drawing a continuous Web of paper 1 weighing about 21 grams per square meter is passed between pairs of superimposed embossing rolls 2 and 3, and 4 and 5. In this particular embodiment, roll 2 is a positive roll and roll 3 is a negative roll forcing web 1 against the roughened surface of roll 2. Roll 5 is also a positive roll while roll 4 is a smooth surface roll like roll 3 urging web 1 against the roughened surface of roll 5. The resulting embossed web of paper 1 is next passed between soft rubber roll 6 and steel roll 7. In this particular embodiment shown in more detail in FIGURE 2, roll 6 is made from sponge rubber having a Shore hardness from about 17 to about 20. Roll 7 is a steel roll having a plurality of circumferential grooves 8 and ridges 9. As web 1 passes between these rolls, sufiicient pressure is maintained to urge the soft surface of roll 6 into the grooves of roll 7. Web 1 is thus forced into grooves 8 of roll 7 as illustrated in FIGURE 4. Since the paper 1 is pinched in the nip between the ridges 9 and the surface of rubber roll 6, paper 1 can not move laterally. Consequently, paper 1 is stretched laterally and the fibers are pulled apart. It is essential in accordance with this invention that sufficient pressure be applied to rolls 6 and 7 to pull apart the fibers of paper 1 and form rents 10 in paper 1 as illustrated to best advantage in FIGURES 7 and 8. The pressure on rolls 6 and 7 may be such as to form continuous rents 10 or it may be adjusted to form a plurality of discontinuous rents 10 in web 1, but in order to facilitate handling of the web, it is preferred to adjust the apparatus to form discontinuous rents. In this particular embodiment, a fluid pressure of from about 54 to 63 pounds per nip inch provided by compressed air is suflicient to form discontinuous rents in web 1 such as is indicated by the numeral 10,

As illustrated in FIGURE 1, web 1 is moistened by means of a water spray before it is laterally gathered and compressed. This water spray may be applied to the web by any suitable means such as for example, by means of a suitable pump and an atomizer 12. Web 1 is laterally gathered and compressed by means of the forming cone 30 such as utilized on cigarette making machines. Paper wrapper 13 is wound about the gathered and compressed web 1 in cone 30 and the overlapping edges thereof are bound together by applying adhesive to edge 14 of wrapper 13 by means of applicator 15 and thereafter folding edge 14 into contact with the overlapping portion of wrapper 13 by means of cylindrical member 16. The overlapping edges of wrapper 13 are tightly bound together by heated roller 17 which removes liquid and sets the adhesive. The resulting rod 18 is cut into individual lengths by rotary cutter 19.

Superimposed rolls 20 and 21 may be substituted for rolls 6 and 7 in the embodiment shown in FIGURE 1. These rolls are forced together under sufficient pressure to force the teeth 22 of roll 21 through paper 1 to form a plurality of rents 23 therein of the general type illustrated in FIGURE 9. In the embodiment of this type of roll shown in FIGURES 3, 5 and 6, the teeth are frusto-conical shaped but teeth of other shapes having a dull point such that the paper is torn and not out can be utilized. For example, the point of the teeth may be substantially spherical. It is also important that the edges of grooves 8 and ridges 9 of roll 7, illustrated in FIGURES 2 and 4, be rounded off in order to avoid sharp edges. Sharp edges have a tendency to form clean cut paper edges rather than to tear the paper or pull the fibers apart, which is necessary in practicing this invention.

It has been found, as indicated hereinbefore, that the filter made in accordance with this invention is more effective in removing tars and other undesirable constituents from tobacco smoke than a filter formed from similar paper which has not been torn or pulled apart prior to the gathering and compressing step. For example, a filter made in accordance with the foregoing embodiment weighing 715 milligrams which has been embossed and thereafter torn by means of rolls similar to those illustrated as 6 and 7 of FIGURE 2 removed about 43% of the tar from cigarette tobacco smoke. A filter formed from the same type of paper which had been embossed but had not been torn removed only 38% of the tars. This filter weighed 780 milligrams. The paper used for form ing each of these filters weighed 21 grams per square meter, the embossing pressure in each instance was about 63 pounds per nip inch and each filter imposed a resistance to the flow of smoke therethrough equal to a loss in head equivalent to a column of water 1.5 inches high at a smoke fiow of 17% cc. per second.

Filter tips were also formed from paper containing about 16% charcoal in accordance with this invention and compared with filters formed from similar paper which had not been torn prior to formation of the filter. In testing these filters it was found that a rod weight of 845 mil ligrams was sufiicient to impose a resistance to the flow of smoke therethrough equivalent to a loss in head of 1.1 if the paper was torn by means of rolls similar to rolls 6 and 7 of FIGURE 2. On the other hand, 950 milligrams of paper were required to produce a filter having a similar resistance if the paper was not torn. Filters made to these weights were compare for effectiveness and it was found that the lighter weight filter made from paper which had been torn removed 38% of the tars from the tobacco smoke while the heavier filter made from untorn paper removed only 31% of the tars from the tobacco smoke. It is apparent from these results that the filter provided by this invention is more effective than the heretofore availa ble filters and that this filter can be made from less compressible material than is required by filters made from untorn paper.

FIGURE 10 illustrates a cigarette 24 composed of wrapper 25 and, enclosed within wrapper 25, tobacco 26 and filter 27 formed in accordance with this invention. Such a filter, provided with rents 28 which exposed ragged, fuzzy edges to the tortuous passageways extending longitudinally through filter 27, is the type found so effec-' tive in removing tars from the tobacco smoke as evidenced by the results presented hereinbefore.

It is ordinarily important for best results that paper web 1 be conditioned to contain from about 5 to 7% moisture before it is assembled with tobacco to form a cigarette. Tobacco is ordinarily conditioned to contain about 12% moisture before it is used in making cigarettes and it has been found that it is necessary that the moisture content of the filter rods be within the range specified in order to insure that the paper will not absorb moisture from the tobacco and deleteriously affect the smoking quantities of the cigarette. Paper which has been impregnated with particles of charcoal in the amount of say 15% should be conditioned to contain from 7 to 9% moisture in order to insure that it will not absorb moisture from the tobacco in the cigarette. As illustrated in FIGURE 1, a convenient method of applying moisture to web 1 utilizes an atomizing nozzle 12.

It is preferred that the compressible material utilized as a filler for the filter of this invention be soft and absorbent paper of the type disclosed in the copending application of Milton 0. Schur and James C. Rickards, Serial No. 400,072 filed December 23, 1953, of which this application is a continuation-in-part, now United States: Patent 2,999,503. This paper is made from high alpha pulp of at least about alpha cellulose and weighs. from about 7 to about 30 grams per square meter before: creping. The paper is preferably creped. The invention is not limited to paper meeting these specifications, however, as advantageous filters may also be formed on the apparatus and in accordance with the method of this invention from webs or sheets of silk, cellulose butyrate acetate and other suitable fibrous filtering material. It has also been found that filters can be formed in accordance with this invention from paper and other compressible materials containing particles of activated charcoal or other impregnants and that the tearing operation does not deleteriously affect the filtering characteristics of the impregnated paper. Indeed, a filter formed from a web of compressible material having particles of activated charcoal embedded therein and torn as provided by this invention is advantageous over filters formed from similar compressible material which was not torn prior to the gathering and compressing step. The activated charcoal particles should preferably be combined with the paper sheet during its formation and should be composed of particles which will pass through a Tyler screen having about 100 mesh per linear inch and which will not pass through a Tyler screen having about 300 mesh per linear inch. From about 2.5 to about 50% by weight activated charcoal can be utilized to advantage but ordinarily not more than about to about is required. Although particles of charcoal are exposed at the surface of the sheet, tearing in accordance with this invention does not materially decrease the amount of charcoal in the sheet.

The filtering characteristics of a filter are further improved if substantially unfibrillated paper is utilized in forming the labyrinthal structure. As is well known in the paper making art, fibrillation is the first step in the conversion of pulp into paper. The more the cellulose fibers are fibrillated, that is, the longer they are subjected to the action of a beater, the greater the surface area of the fibrils and the tighter will be the interlock between the fibrils when they are formed into a sheet. Paper which has been formed from only moderately fibrillated or unfibrillated cellulose has an open structure which is substantially absorbent and the paper is relatively easily softened, crumpled and torn apart.

Although two types of rolls adapted to tear the web of compressible material in accordance with this invention are illustrated in the drawing, it is to be understood that many other types of rolls can be utilized to form the rents in the web. Indeed, the paper can be torn by any means in so long as the shreds formed therein have a ragged, fuzzy edge, but it has been found that rolls of the type illustrated in FIGURE 2 are particularly well suited for the purpose. The web having discontinuous rents formed by such rolls can be handled on the machine without difliculty and can be easily compressed into a filter rod which can be wrapped without difficulty. It is to be understood that in practice the rents may not form any definite pattern in the web but on the contrary will ordinarily be haphazardly arranged in the web particularly if. the rents are formed by means of a roll of the type illustrated in FIGURE 2. The rents may vary in length or diameter, as the case may be, but as a general rule it is preferred to form a large number of rents of small dimension rather than form a smaller number of rents of larger dimension. Such a practice results in the formation of a torn web which can be more easily handled as a single web than one in which the tears or rents are of great dimension. Although rents 10 of FIGURES 1 and 7 extend longitudinally in the web it is also contemplated to form laterally extending rents in the web. Such rents may be formed by means of suitable rolls or any other means which will tear or pull apart rather than cut the compressible material. Obviously, such rents will not extend to the edge of the web.

Although sponge rubber rolls are readily available and admirably suited for the purpose, rolls of plastics or other soft materials which are easily deformed under pressure may be utilized as roll 6 in the embodiment illustrated in the drawing. Likewise, roll 7 can be made from any one of a variety of materials harder than sponge rubber or other materials used for forming roll 6. This roll might be formed from hard plastics for example, or from rubber, brass, aluminum, or any other metal in which grooves can be formed. Rolls 20 and 21, respectively, may be made from materials similar to those from which rolls 6 and 7, respectively, are formed, but usually both rolls 20 and- 21 will be formed from a suitable metal.

Because the gathered and compressed fibrous filler material provided by this invention exerts less pressure against the walls of the wrapper, many types of adhesive can be utilized to securely bind the overlapping edges of the wrapper. For example, paste prepared from casein or starch and water, or a suitable gum adhesive, may be utilized. Use of this type of torn filler material also permits operation of the forming machine at a greater speed than has heretofore been possible when gathering and compressing an untorn web of compressible material. Moreover, the product has been found to much more uniform in dimensions and in pressure drop.

Although various embodiments of the invention have been described in detail in the foregoing, it is to be understood that such description is solely for the purpose of illustration and that many modifications can be made by those skilled in the art without departing from the scope and spirit of the invention except as limited by the appended claims.

What is claimed is:

1. In the manufacture of a filter rod from a web of fibrous material, the procedure which consists in longitudinally advancing the web, lacerating the web during its advancement to form haphazard mutilation and fiber displacement without destroying the transverse continuity of the web, and converging the lacerated web to form a rod-like bundle.

2. In the manufacture of a filter rod from a web of fibrous material, the procedure which consists in longitudinally advancing the web, lacerating the web during its advancement to form haphazard mutilation and fiber displacement without destroying the transverse continuity of the web, converging the lacerated web to form a rod-like bundle, and enclosing the bundle in a tubular wrapper.

3. In the manufacture of a filter rod from a web of fibrous material, the procedure which consists in longitudinally advancing the web, embossing the web during its advancement, thereafter lacerating the web during its advancement to form haphazard mutilation and fiber displacement without destroying the transverse continuity of the web, and converging the lacerated web to form a rod-like bundle.

4. In the manufacture of a filter rod from a web of fibrous material, the procedure which consists in longitudinally advancing the web, successively embossing the web at each surface thereof during its advancement and subjecting said web to longitudinal grooving with simultaneous stretching between a plurality of areas spaced transversely across the web to form random elongated discontinuous rents therein, and thereafter converging the embossed and grooved web to form a rod-like bundle.

5. In the manufacture of a filter rod from a web of fibrous material, the procedure which consists in longitudinally advancing the web, passing the said web during its advancement between opposed grooving rolls having a plurality of interfitting grooves and ridges, thereby forcing said web into said grooves and stretching said web laterally beyond its elastic limit to form random elongated discontinuous rents therein, and thereafter converging the grooved web to form a rod-like bundle.

6. In an apparatus of the character described, means for feeding a web of paper, mutilating means operative upon the web to displace and disarrange the fibers of the paper, means by which the web is converged into rod-like formation and enclosed in a tubular wrapper, and means between the mutilating means and the wrapper-enclosing means for tensioning the paper to an extent beyond the limits of its elasticity.

7. In an apparatus of the character described, means for feeding a fibrous web, a web-mutilating apparatus through which the web is moved and which lacerates the web to release fibers thereof without destroying the transverse continuity of the web, means for compacting the mutilated web, means for applying a wrapper around the compacted web to form a filter rod, tensioning means in- 7 dependent of the web-feeding means and interposed between the web-feeding means and the wrapper applying means for stretching the compacted web as it approaches the wrapper applying means, and means for severing the filter rod into predetermined lengths.

8. In an apparatus of the character described, means for advancing a fibrous Web, means for embossing said web during its advancement, means by which the web is converged into rod-like formation, and grooving means between the embossing means and the converging means comprising opposed rolls having a plurality of interfitting circumferential grooves and ridges for stretching the Web laterally to an extent beyond the limits of its elasticity.

9. In an apparatus of the character described, means for advancing a fibrous web, means for embossing said web during its advancement, means by which the web is converged into rod-like formation, and grooving means between the embossing means and the converging means, said grooving means comprising a pair of opposed rolls, one having a soft deformable surface and the other having a hard surface provided with a plurality of circumferential grooves and ridges, thereby forcing said web during its advancement into said grooves and simultaneously grooving said Web and stretching it laterally to produce disconnected rents therein.

10. In an apparatus of the character described, means for advancing a fibrous Web, means for embossing said web during its advancement, means by which the web is converged into rod-like formation, and grooving means between the embossing means and the converging means, said embossing means comprising a pair of opposed rolls, one of said rolls having a roughened surface and the other having a smooth surface forcing the web during its advancement against the said roughened roll surface.

No references cited.

FRANK E. BAILEY, Primary Examiner. B. STICKNEY, Examiner.

Disclaimer 3,238,852.-]l[i?t0n Oscar Schur, Asheville, and James Richards, Brevard, N.C. METHOD AND APPARATUS FOR MAKING FILTERS. Patent, dated Mar. 8, 1966. Disclaimer filed Aug 10, 1970, by the assignee, Olin Corporation. Hereby enters this disclaimer to claims 5, 8 and 10 of said patent.

w n-m Gazette January 26', I971]

Claims (1)

1. IN THE MANUFACTURE OF A FILTER ROD FROM A WEB OF FIBROUS MATERIAL, THE PROCEDURE WHICH CONSISTS IN LONGITUDINALLY ADVANCING THE WEB, LACERATING THE WEB DURING ITS ADVANCEMENT TO FORM HAPHAZARD MUTILATION AND FIBER DISPLACEMENT WITHOUT DESTROYING THE TRANSVERSE CONTINUITY OF THE WEB, AND CONVERGING THE LACERATED WEB TO FORM A ROD-LIKE BUNDLE.

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