US3477440A - Reconstituted tobacco sheet - Google Patents

Description

Nov. 11, 1969 O. F. LICIS REGONSI'ITUTED TOBACCO SHEET Original Filed Sept. 1, 1966 United States Patent 1 3,477,440 RECONSTITUTED TOBACCO SHEET r OsvaldsyF. Licis,; Richmond, Va., assignor to Philip Morris Incorporated, New York, N.Y., a corporation ofyirginia l v riginal application Sept. 1, 1966, Ser. No. 576,676, now Patent No.3',43 1',915, dated Mar. 11,1969. Divided A and application Mar. 11, 1968, Ser. No. 739,571

Int. Cl. A24b 3/14 "U. Cl. 131- 14 a 2 Claims e i ABSTRACT OF THE DISCLOSURE 1 H t ,Re constituted tobacco shred s having an increased filling power are \made from ,reconstituted tobacco sheet material which has been fed between ,coacting rollers so as .to result in spaced longitudinal bands of uniform thickness with lintervening creped areas, the latter mainfesting disproportionate internal stress valves. Shreds made from the sheet willtend to curl and kink thus increasing the bulk density of the filler.

This is adivision of application Ser'. No. 576,676 filed Sephl, 1966, now'patent No. 3,431,915. I

T *This invention relates to a reconstituted tobacco sheet which, when shredded for use as a cigarette filler, it has a filling capacity greater than that of ordinary untreated reconstituted tobacco sheet.

Various methods are known by means of which tobacco scraps and similar tobacco residue evolved in the processing of tobacco-products can be utilized in smoking articles. In general, the-scraps and residue are reconstituted 'intoa self-sustaining sheet, the reconstituted sheet thereafter being further processed and used as cigarette filler "or-cigar wrappers. The present invention provides a novel 1; The treatment of there constituted tobacco sheet involves building up therein a pattern of residual differ- ;ential stressesgwhichpz cause the sheet and consequently tobacco shreds .formedtherewith to curl and kink in a fashion akin to that in which natural tobacco leaf becomes curled when it; is steam dried in. conventional tobacco processing methods. Thisinvolves producing an alternating arrangement of compacted and non-compacted bands in the sheet and mechanically inducing therein non-uniform stress-strain characteristics. The reconstitute-d tobacco s heet may be treated :with various forms of apparatus.

However, preferred embodiment ofthe apparatus comprises a pair of rollers one of which is a heated smooth .faced roller, and an endless, thick rubber belt which is .provided on one side with analternating arrangementof .ribs and grooves to giveit a discontinuous transverse surface. The endless belt is fed into the nip of the two rollers, with the belt traversing a course partly around each. The

."tobacco sheet also is fed into the roller nip and against Ithe discontinuous surfaced face of the endless belt so that .o nelface thereof engages the said belt face and the other face of the sheet engages with the smooth surface of the heated roller. The arrangement is such that the endless belt traverses a course partly around each roller with the nip therebetween being at a point where the course of the 3,477,440 Patented Nov. 11, 1 969 "ice sheet engaging face of the endless belt undergoes atransition from a convex travel on the unheated roller to a concave travel on the other or heated rollen-In this manner, the discontinuous sheet engaging face of the endless belt changes from a tensed to a compressed condition. The endless belt material is of such nature as to maintain a strong frictional hold on the tobacco'sheet so that the compressed face of the belt applies a compression to the sheet at longitudinally extending, transversely spaced areas of the sheet, the compression being applied to' the sheet in the direction of its faces and opposite to its direction of travel. Additionally, a compressive force acting perpendicular to the run of the tobacco sheet is maintained along said areas by the tightened condition of the rubber belt thereby preventing any increase in thickness in the treated longitudinal bands or areas of the tobacco sheet although the overall natural length of said bands decreases. The action of the rollers and rubber belt on the tobacco sheet thus is to rearrange the relative positionings of and crowd together the tobacco constituents within the longitudinal bands, with the tobacco portions between said bands becoming creped.

Various other objects, features and advantages of the present invention will be made apparent by the description that follows and the illustrative examples depicted in the drawing.

In the accompanying drawings:

FIGURE 1 is a side elevational view of a preferred embodiment of the apparatus with which reconstituted tobacco sheet may be treated according to the principles of the present invention.

FIGURE 2 is a transverse sectional view through the flexible belt used in the apparatus of FIGURE 1.

FIGURE 3 is a partial longitudinal plan view of a reconstituted tobacco sheet treated with the apparatus of FIGURE 1 in accordance with the present invention showing the alternate arrangement of compacted and non-compacted bands therein which produce non-uniform residual stresses and strains in the tobacco sheet to thereby increase its filling capacity when it is used as a cigarette filler.

FIGURE 4 is similar to FIGURE 3 except that the alternate compacted and non-compacted bands in the tobacco sheet are directed angularly of the longitudinal axis of the sheet as occurs when the ribs and grooves on the endless belt are arranged to extend at an angle to the major axis thereof.

FIGURE 5 is a fragmentary plan view on enlarged scale of a section of treated reconstituted tobacco sheet showing the planar contours produced therein by the method of the present invention.

FIGURE 6 is a sectional view as taken along line VI-VI in FIGURE 5.

The present invention is concerned with reconstituted tobacco sheet, i.e., which is made from tobacco stems and other tobacco residue, the sheet being formed by casting it in a Fourdrinier apparatus in the same general man- ,ner employed in paper making. It is contemplated that the wet sheet of tobacco on leaving the Fourdrinier apparatus, that is, on being removed from the wire forming carrier will be subjected to some drying. This may be carried out by means of suction boxes, Yankee drier .unit, or other conventional drying equipment and is intended to reduce the water content of the wet tobacco sheet to a range of between 12% and 25% by weight but preferably about 15%. The tobacco sheet is then directed into the roller apparatus shown in FIGURE 1. The apparatus comprises a pair of driven rollers 11 and 12, the roller 12 being aheated drum which has a smooth outer surface that will offer low frictional resistance to the movement of the tobacco sheet 10 thereon when the latter is brought into contact with it in the manner to be described later on in the specification. Intermediate the two rollers 11, 12 there passes a continuous belt member 14, the outer surface 16 of which is of a contractible character and to that end, the belt member 14 is preferably made of rubber. The apparatus also includes an additional roller 17 around which the belt member 14 passes with the roller 17 being spaced sufiicient distance from roller drum 12 to provide a straight belt run transfer from the roller drum 12 to roller 17. A guide roller .18 is also provided. The outer surface or face 16 of the belt, i.e., the tobacco sheet engaging face is discontinuous in a transverse direction as shown in FIGURE 2 having extending thereon a plurality of transversely spaced, longitudinally extending ribs 20, with grooves 21 extending between adjacent ribs. In a preferred form of the belt, the width of the ribs 20 should be in a range between of an inch and 1 (one) inch, the preferred width being between A and of an inch. It was found that to achieve an improvement in the filler characteristics of reconstituted tobacco sheet, the application of the compressive forces thereto has to be effected along relatively narrow bands or areas of the sheet. Hence, the use of rib widths in the range above. The grooves 21 should be at least equal to the widths of the ribs although they can be made with a somewhat larger dimension without producing change in the teaching of the invention. The arrangement of the rollers 11 and 12 is such that the face 16 of the belt 14 (which is comprised of the fiat surfaces of the respective ribs and which contacts the tobacco sheet) undergoes a transition from a convex run on the drum 11 to a concave run on heated drum 12, the belt face 16 shortening or contracting as it undergoes this transition. As a consequence, the tobacco sheet 10 feeding intermediate the outer face of the belt 14 and the smooth outer face of heated drum 12 is gripped tightly by the transversely discontinuous belt face and responsive to the contraction of the latter, is subjected to compressive forces exerted parallel to the faces of the tobacco sheet and counter to the direction of the sheet run thereby distorting and flexing the tobacco constituents in the reconstituted sheet along longitudinal directed bands corresponding to the location of the ribs 20 on the belt 14. It should be understood that ithe phenomenon of distorting and flexing the tobacco constituents is in effect a rearrangement of the relative positions of the pectins, hemicelluloses, galacturonic acids and other constituents which comprise reconstituted tobacco, the constituents being pushed or crowded together in a direction opposite to the sheet travel with resulting shortening of the natural length of the sheet. It is believed that little or no actual geometric distortion of the tobacco constituents occurs as reconstituted tobacco sheet constituents rarely have length/width ratios greater than 1:1 and as such are not amenable to physical distortion and changes in geometric configuration in the same manner as fibrous materials, as for example, paper fibers having length/Width ratios in excess of 5:1.

As seen in FIGURE 3, the treated tobacco sheet has an alternating arrangement of compacted bands 40, and non-compacted bands 41 corresponding respectively to the rib-groove arrangement on the belt member 14. During the course of treating the tobacco sheet, the primitive lengths of the compacted band portions 40 are progressively shortened without any increase in the thickness thereof, this being prevented by the action of belt 14 in holding the sheet in tight contact with the roller drum 12 and applying a compressive force normal to the direction of travel of the tobacco sheet. The non-compacted bands 41 on the other hand are not subjected to shortening of their primitive lengths. Instead, they assume a randomly patterned creped condition caused by the shortening of the two compacted band portions 40 adjacent each non-compacted band 41. This condition is shown with greater clarity in FIGURE 5 wherein it will be noted the compacted bands 40h are smooth faced at both sides of 4 the sheet and the non-compacted bands 41b have-an JJH- dulating contour 43 characteristic of creped sheet.

The effect of compacting the tobacco sheet only along longitudinally directed, transversely spaced bands is to mechanically induce stresses and strains in the sheet and impart varying dimensional characteristics thereto. In other words, the reconstituted sheet on being'treated'a's described assumes a non-uniform modulus of elasticity. This will be apparent by referring to FIGURE 6. The compacted bands 40b whichhave been stressed are of flat section. The non-compacted bands 4112 however exhibit the randomly arranged undulating segments 46. Thus when the sheet is shredded along shear planes X-Y:for filler purposes, the shred is comprised of a stressed segment 47 represented by the compacted band portion of the shred and a relatively non-stressed segment 46, The stress differential within the respective segments of each shred causes it to assume a curl or kink. A reconstituted tobacco sheet treated uniformly throughout its width instead of in an alternate banding arrangement will on the other hand, possess a uniform modulus of elasticity and shreds formed therefrom lacking a stress differential will not curl or kink. The difference is of consequence when the respective sheets are used as a cigarette filler as will appear.

When ordinary untreated reconstituted tobacco sheet is shredded for use as a cigarette filler, the shreds produced for the most part lay flat and occupy less space than natural leaf tobacco shreds. Natural tobacco leaf on the other hand, is curly and possesses a stress and strain therein imparted by steam drying during leaf processing so the tobacco shreds kink or twist when the leaf is shredded, thus increasing its bulk density or filling capacity. The reconstituted tobacco sheet treated as described above, i.e., one compacted in alternate bands extending longitudinally of the sheet does not suffer the limitation of laying flat during cutting so that the shreds possess a kink or curl skin to that of natural tobacco leaf giving the filler increased bulk density.

Further understanding of the invention will appear from the following examples.

Example 1 A reconstituted tobacco sheet which was cast in a Fourdrinier apparatus and dried to a water content of about 15% by weight of water was treated as previously described on apparatus as shown in FIGURE 1 and having a rubber belt. The treated sheet was then shredded to serve as cigarette filler.

An untreated reconstituted tobacco sheet also 'was shredded providing a filler with which cigarettes serving as a control were prepared.

During the shredding, the reconstituted tobacco sheet treated according to the present invention had a non-uniformity of shred (a curl or kink) and the curled and intertwined shreds were easily handled when making cigarettes. The untreated reconstituted tobacco sheet made fiat shreds which were more difiicult to handle.

Control and experimental cigarettes were then made from the respective treated and untreated tobacco sheet fillers to provide data on the filling power of each. Since filling power is difficult to define and determine, it was necessary to select variables most likely to give a correlation with filling power. Accordingly, the cigarettes were made at a constant resistance-to-draw (RTD expressed in inches of water). The RTD of both the control and the experimental cigarettes was 2.2-2.6 inches of water. The cigarettes were mm. long and had a circumference of 25.2 mm. The weight of the cigarettes made'from the treated filler was 0.956 grarn/ cigarette. From four ounces of the treated filler, 119 cigarettes were prepared. From four ounces of the control, 117 cigarettes were prepared,

Since the RTD of the cigarettes remained constant and since more cigarettes were made from the four ounces of he test filler, i w s e ident ha the treatment of the re-.

consituted tobacco sheet according to the present invention increased the bulk density of the filler and it was concluded that the treated tobacco sheet has a greater filling power than the untreated control sheet.

Example 2 Control and test cigarettes were prepared as described in Example 1 with the RTD kept constant at 2.2-2.6 inches of water. The cigarettes made were 70 mm. long and had a circumference of 25.2 mm. The test cigarettes were filled with 1.144 grams/cigarette and the control with 1.215 grams/cigarette.

From four ounces of the treated filler, 99 cigarettes were made. Ninety-four (94) control cigarettes were made from the four ounces of untreated filler. Thus, approximately 5% more cigarettes were made with the treated filler than with an equal weight of the untreated filler.

Example 3 In a similar experiment to determine the filling power of test and experimental cigarettes, the cigarettes were kept at a constant weight. The cigarettes differed from those described in Examples 1 and 2 as follows: the cigarettes were made to a constant weight .of 103-107 cigarettes per 14 ounces of filler; they had a length of 65 mm. and a circumference of 25.2 mm. The control cigarettes were made of a blend of predominantly natural leaf filler and shredded filler from an untreated reconstituted tobacco sheet. Comparisons of the filling power of test cigarettes and the control were made by determining their RTD, a measure of bulk density of the cigarettes. The treated cigarettes had an RTD of 3.0; the control had an RTD of 2;9 showing that the treated cigarettes were more tightly packed than was the control. This indicated an increased filling power.

Example 4 Test cigarette filler was prepared as described in Example 1. The control cigarettes had the same filler as the control in Example 3. Test and control cigarettes were made to a constant RTD of 2.0-2.2 inches of water. The cigarettes made were 65 mm. long and had a circumference of 25.2 mm. From 4 ounces of the treated filler, 119 cigarettes were made. From 4 ounces of the blend used as the control, 115 cigarettes were made. The increase in the number of cigarettes prepared from the treated cigarettes indicated that the filling power of the treated filler was greater than that of the blended filler.

It will be understood from the foregoing description that the present invention requires compacting or contracting a reconstituted tobacco sheet in narrow longitudinally directed, transversely spaced bands to achieve an improvement in the filling properties of the sheet when it is used as a cigarette filler. While the compaction of the sheet is carried out in an effective manner with the apparatus of FIGURE 1, it will be apparent that other devices can be employed to produce the same effect. For example, a roller set having a speed differential therebetween and employing a discontinuous surface on one of the rollers could also be used. Moreover, the construction of belt member 14 can be modified to provide it with ribs extending angularly of the longitudinal axis thereof so as to produce a compacted band 40anon-compacted band 41a alternating arrangement pattern such as that shown in FIGURE 4.

The present invention provides an effective manner with which the filling properties of reconstituted tobacco sheet can be improved when it is used as a cigarette filler. It is possible to produce a more dense cigarette from a given weight of treated reconstituted tobacco sheet than is possible when using an equal weight of untreated sheet. Not only is the bulk density of reconstituted tobacco sheet improved when it is treated according to the present invention but better resistance-to-draw qualities, as shown by Example 3, as well as firmer packing of the cigarettes made therewith are achieved.

It will thus be seen that the objects set forth above among those made apparent from the foregoing description, are efiiciently attained, and since certain changes in carrying out the above method and in the constructions set forth, which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A reconstituted tobacco sheet suitable for use in making a shredded filler having a high filling capacity, said sheet being formed with longitudinal parallel bands alternating ones of which have flat faces and possess the same internal stress values, the intervening bands being creped and possessing disproportionate values of internal stress.

2. A reconstituted tobacco sheet suitable for use in making a shredded cigarette filler having a high filling capacity, said sheet having an arrangement of alternately spaced longitudinally extending parallel bands, the stock of said sheet constituting said bands being of generally uniform thickness, the said bands presenting flat surfaces generally parallel to the plane of the sheet on both the upper and lower surfaces thereof, the portions of the sheet between the bands being creped and presenting areas of undulating contour.

References Cited UNITED STATES PATENTS 1,122,747 12/1914 Hammerstein 131-l47 X 3,230,958 1/ 1966 Dearsley 131-8 MELVIN D. REIN, Primary Examiner US. Cl. X.R.

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