GB1568630A - Smokable tobacco products - Google Patents

Description

(54) SMOKABLE TOBACCO PRODUCTS (71) We, BROWN & WILLIAMSON TOBACCO CORPORATION, of 1600, West Hill Street, Louisville, Kentucky, United States of America, a Corporation organised under the laws of the State of Delaware, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to smokable tobacco products and a process for producing them.

The cost of raw tobacco has increased substantially in recent years to the extent that it has become an increasingly larger percentage of the overall cost of the smokable tobacco products. Efforts better to utilise tobacco raw materials and also to improve the final smokable tobacco product are thus becoming increasingly important.

While it is desirable to provide a smokable tobacco product which may be formed of a lesser quantity of tobacco than utilised in conventional tobacco products, it is also necessary to retain and improve traditional product characteristics such as firmness; end firmness or stability; coal retention; density; pressure drop and number of puffs.

Cigarettes are conventionally formed by threshing raw tobacco and cutting the threshed tobacco to reduce its size for handling by the tobacco product making or forming machine. Tobacco products formed by this traditional method utilising cut tobacco are characterised by cut tobacco particles which are generally planar two dimensional structures each having a small roughly constant width and a variable dimension in length. The major axis of each traditionally cut tobacco particle in the conventional cigarette runs approximately parallel to the length of the cigarette tube. Once a particle obtains a certain length, little benefit in increased firmness in the cigarette is obtained by increasing the length of the particle. Thus, a limit is reached in conventional cigarettes where, for a specified firmness, a particular density or amount of tobacco is necessary.

The present invention provides a novel and improved smokable tobacco product having improved properties. Improvements are based primarily on differences in tobacco particle geometry, size distribution, and orientation in comparison with traditional smokable tobacco products formed from cut tobacco. It has been found that use of small strip tobacco particles as defined hereinafter permits the formation of smokable tobacco products, e.g. cigarettes, at lower then normal weights, i.e. lower density of tobacco, while retaining properties such as firmness, and stability and pressure drop in comparison with conventional smokable tobacco products.

The term "small strip tobacco" as used herein refers to tobacco, including reconstituted tobacco, particles having a mean ratio of area to perimeter squared (A/p2) of at least 0.049. Normally, at least 70% of the particles present in the smokable tobacco product will have an A/p2 ratio of from 0.037 to 0.065. The particles of tobacco of the present invention are irregular pieces having a short dimension not in excess of 0.5 inch, and preferably not in excess of 0.365 inch, and an arithmetic mean size of at least 1.93 mm. The particles may also have a short dimension characterised as a geometric mean size of at least 1.74 mm.

Thus a smokable tobacco product according to the invention comprises a tobacco portion surrounded by a cylindrical wrapper, wherein said tobacco portion consists essentially of irregular tobacco particles having a mean ratio of area to perimeter squared of at least 0.049 and a short dimension not in excess of 0.5 inch and, an arithmetic mean size of at least 1.93 mm, said particles being of a substantially normal particle size distribution. In a smokable tobacco product of such particles, the lattice structure is highly resilient, enabling product formation at lower than normal weights while retaining similar firmness, end stability and burn properties as conventional cigarettes.

Small strip tobacco is utilised as a minor component in cigarettes in the process of our U.K. Patent Application No. (Serial No.

1,568,629) 11,593/77. That process comprises separating small strip tobacco from bulk strip tobacco prior to cutting of the bulk strip tobacco and then reintroducting the small strip tobacco into the process line downstream from the cutting zone, but prior to cigarette formation.

According to a preferred mode of application of the present invention, small strip tobacco may be removed from bulk strip tobacco in a manner similar to that of the aforesaid process. For example, small strip tobacco may be removed by screening the bulk strip tobacco, the tobacco particles passing through the screen and thereby being of predetermined size constituting the small strip tobacco. Contrary to the said process, however, this small strip tobacco is then processed in conventional cigarette forming or making machines to form the novel and improved cigarettes or smokable tobacco products of the present invention in which the tobacco portion consists of small strip tobacco.

One of the principal benefits derived from the formation of an all small strip cigarette or smokable tobacco product is the increased fill value of the small strip particles which results in increased firmness and consequent reduction in tobacco material utilised in forming the product.

This is attributable to the tobacco particle geometry, size distribution, and orientation within the cigarette tube. As noted previously, the tobacco utilised in the all small strip cigarette has a particle size with a short dimension not in excess of 0.5 inch. A substantial majority of the small strip tobacco particles have a shape approximating planar polygons. Also, 70- 80 X" of the particles of small strip tobacco have a shape factor (A/p2) substantially within a range of about 0.037 to about 0.065 wherein A is the area of the particle and P is its perimeter. It is believed that particles of this size and shape exert greater force on the retaining cigarette tube or wrapper than traditional cut tobacco exerts on its tube.

This interaction between the particles is believed to be the cause of the greater end stability and firmness of the products.

Additionally, the orientation of the small strip tobacco particles within the tube provides a lattice which is highly resilient.

That is, in forming the cigarette rod or tube, the small strip particles conform to the curvature of the cigarette rod. Since the small strip particles have major dimensions both parallel to the tube length and concentric with the tube center-line, the lattice thus formed interacts to increase firmness. This is accomplished without decrease in smoking properties, for example pressure drop, end stability and number of puffs. A significent result achieved by forming smokable tobacco products or cigarettes from the all small strip particles in accordance with the present invention is a substantial reduction in the tobacco weight, i.e. of the order of about 20 percent, while still producing a cigarette or smokable tobacco product with normal physical and smoke properties.

It is a primary object of the invention to provide novel and improved smokable tobacco products, particularly such characterised by increased utilisation of tobacco raw materials.

Another object of the invention is to provide tobacco products characterised by particles having a specified geometry, distribution and orientation resulting in improved firmness. Advantageously, such tobacco products may exhibit a significant reduction in tobacco material in comparison with conventional tobacco products, while retaining normal physical and smoke properties.

A preferred embodiment of the invention by way of example will now be described with reference to the accompanying drawing, which is a schematic flow diagram of a process for manufacturing a smokable tobacco product.

Referring to the drawing, a separator 10 includes a screen over which cased or bulk strip tobacco from a source, not shown, is passed, small strip tobacco being removed by passing through the screen. The "overs" or bulk strip tobacco which does not pass through the screen is removed along flow path 12 by a suitable mechanism. The separated small strip tobacco is conveyed along a flow path 14 toward a tobacco product making machine or machines 16.

The equipment at 16 for manufacturing the smokable product may be conventional and further description thereof is not believed necessary. The resulting product, however, is made entirely from the small strip tobacco, which thus comprises the small strip tobacco contained in the bulk strip tobacco after it has been threshed. Small strip tobacco, however, may be formed or generated by various processes, for example by a hammermill, or by classification through elutriation, particle trajectory or sizing screens, to the size, shape and other specifications of the small strip obtained by screening bulk strip tobacco. The drawing illustrates a process for forming cigarettes from any small strip tobacco, preferably such obtained by screening small strip tobacco from bulk strip tobacco.

Alternatively small strip tobacco separated from bulk strip tobacco, or generated by other processes, may be directly supplied to product forming machines to form a final smokable tobacco product.

As previously indicated, it has been found that improved properties of the final smokable tobacco product are obtained by providing tobacco particles of a size having a short dimension not in excess of 0.5 inch.

Preferably, however, small strip particles having a short dimension not in excess of 0.365 inch are separated from the bulk strip tobacco by screening through a 2-1/2 mesh per inch square opening screen with an 83.3 percent open area. Further, it has been found that such improved properties are obtained by providing small strip tobacco comprised of particles having an arithmetic mean size of at least 1.93 mm and a geometric mean size of at least 1.74 mm.

The density of the small strip tobacco is substantially the same as the density of cut tobacco and is at least .6603 gm/cc.

The bulk small strip particle size is given in terms of a specified size of opening in a screen. The size of the particle provided is the significant factor rather than the process or apparatus used to obtain the small strip particles. It has been found that small strip tobacco may be characterised by a particle size distribution curve which is typically substantially symmetrically bell-shaped.

Thus, the particle size distribution of small strip tobacco is, unexpectedly, approximately normal. In comparison, the particle size distribution curve for traditional cut tobacco particles is typically log normal and has significant skewness.

Small strip tobacco is also classified according to its shape. To accomplish this, a form factor (A/P2) has been chosen where A is the area of the substantially planar particle and P is its perimeter. The following Table illustrates a comparison of the form factor (A/P2) distribution for small strip tobacco and traditional cut tobacco in terms of their means, standard deviation, skewness and kurtosis.

TABLE I Small Strip Cut Tobacco Tobacco (30 cpi) Mean (A/P2) 0.049 0.034 Standard Deviation 0.012 0.015 Skewness -0.95 0.08 Kurtosis 4.07 2.35 As evident from Table I and as distinguished from traditional cut tobacco, the small strip tobacco particle shape has a mean form factor (A/P2) of at least 0.049.

Also, from the mean values of (A/P2) given in Table I, the shape of small strip tobacco can be approximated by rectangles with sides a, 0.38a; whereas cut tobacco particles appear as rectangles with sides a, 0.19a.

The standard deviation in Table I demonstrates that most small strip tobacco particles appear as rectangles with sides ranging from a, 0.22a up to a, 0.73a. Most traditional cut tobacco particles, in contrast, appear within a range from a, 0.09a up to a, 0.37a. The skewness value of the small strip shape factor distribution from Table I shows that the (A/P2) values of small strip particles are shifted toward rectangles of sides a, 0.37a and larger. On the other hand, the skewness value for cut tobacco indicates a symmetric distribution of shape factor (A/P2) about the.mean.

From the kurtosis values, the small strip tobacco shape factors and, hence, the shape distribution of the small strip particles are more likely to be found in a narrow range of values; distribution of cut tobacco particles lies over a wide range of values.

As calculated from data given in Table I, at least 70% of cut tobacco particles will have a shape factor (A/P2) within the range of 0.019--0.049, while at least 70% of the small strip tobacco particles will have a shape factor (A/P2) no greater than about 0.065 or no less than about 0.037. It is noted that the shape factor for traditional cut tobacco at the high end of its range has a value of 0.049, which value corresponds identically to the mean shape factor for small strip tobacco given in the Table.

Properties of the smokable tobacco product formed in accordance with the present invention, utilising the processes described above, will now be compared with properties of a current production cigarette.

The small strip samples identified in Table II below were obtained using the process of the drawing. In general, bulk strip tobacco used in commercial manufacturing operations was separated by screening.

Small strip tobacco was removed as the material passed through a 3 mesh (.286" opening) screen. The small strip tobacco was conditioned to 13-14% moisture.

Finally, cigarettes were fabricated from the all small strip tobacco passed through the screen. In fabricating the cigarettes, the density was targeted for the A and B samples at 20% and 10% reductions, respectively, from the density of standard production cigarettes. The C sample represents a cigarette made from all small strip tobacco at substantially the same density as the production cigarette.

The test results are set forth in Table II on the basis of percentage improvement for each sample compared to the production cigarette.

The following definitions are provided to facilitate interpretation of these test results: Tobacco section pressure drop-fhe resistance to air flow in the tobacco rod measured in inches of water pressure loss.

Firmness-the ability of a cigarette to withstand an applied compressive force.

End stability-the measure of a cigarette's resistaiice to form void, loose, or soft ends.

Coal retention probability-the ability of a cigarette to retain its coal for a specified duration of tapping.

TABLE II Physical and Smoke Properties of All Small Strip Cigarettes as Percentage of Improvement Relative to a Production Cigarette Cigarette Code A B C Type Small Strip' Small Strip' Small Strip' Density Change Relative to Density -17.9 -10.8 -2.4 of Standard Production Cigarette Firmness2 03 13.8 30 End Stability 53 75 83 Coal Retention Probability 03 19.6 -7 Tobacco Section Pressure Drop 03 22 94 (in H2O) Puffs 03 10 15 Tar Delivery 03 -10 -9 Nicotine Delivery 5 -8 6 1/ All small strip cigarette made from mesh small strip 2/ Corrected for moisture 3/ No Significant Change From Table II, it can be seen that the sample C made at normal density had improved firmness of 30%, while sample B made at 10% reduced density had improved firmness of 13.8%.Note that sample A having a 20% reduced density had substantially equal firmness with the production standard cigarette.

Improvements of 53%, 75% and 83% in end stability for samples A, B and C relative to the production standard cigarette are shown. The sample B obtained a 19.6% improvement in coal retention probability, while sample A had no significant change in coal retention probability in comparison with the production standard cigarette.

Thus, the coal retention probability decreased as density decreased.

The tobacco section pressure drop also decreased as density decreased and a leveling off effect was obtained at about the density obtained in sample A.

Smoking properties also changed with respect to density changes. The puffs increased virtually linearly with increase in density. Sample A had no significant change in the number of puffs delivered in comparison with the production standard cigarette. With respect to tar, nicotine and CO deliveries, it was noted that the sample A did not change substantially from the production standard cigarette.

A sample was also fabricated at 30% reduced density from production standard cigarette density and was tested for the properties listed in Table II. The properties of this sample were inferior to the production standard cigarette, especially firmness.

Thus, it is believed that the best balance of desirable features may occur at about a 20 to 25% density reduction, when practicing the invention as described herein.

It is believed that the foregoing properties disclosed in Table II enabling density reduction, while retaining physical, chemical and smokable properties comparable to standard cigarettes, are attributable, not only to the small strip tobacco particle size and distribution, but also at least in part to their shape and orientation within the tobacco rod. That is, the small strip tobacco particles have a major dimension extending parallel to the axis of the rod and also a major dimension running concentric with the rod's centerline The natural resiliency of these particles arranged in the foregoing manner provides increased firmness without causing large pressure drops. It has also been found that the pressure drop variance is smaller as compared with the production standard cigarettes although it is elevated slightly.

A smokable tobacco product using small strip tobacco entirely as the tobacco component may be formed from a lesser quantity of tobacco, while retaining physical, chemical and smokable properties similar to those of standard conventional cigarettes. Better utilisation of raw tobacco material can be achieved through the manufacture of cigarettes containing entirely all small strip tobacco.

While the present invention has been described in terms of a smokable tobacco product in which the tobacco portion is formed from small strip tobacco, as previously defined, it is to be appreciated that the smokable tobacco product may contain minor amounts of other additives, such as casings, flavorants, and the like.

WHAT WE CLAIM IS: 1. An improved smokable tobacco product comprised of a tobacco portion surrounded by a cylindrical wrapper, wherein said tobacco portion consists essentially of irregular tobacco particles having a mean ratio of area to perimeter squared of at least 0.049, a short dimension not in excess of 0.5 inch and an arithmetic mean size of at least 1.93 mm, said particles being of a substantially normal particle size distribution.

2. The product of claim 1, wherein at least 70% of said particles have a mean ratio of area to perimeter squared of from 0.037 to 0.065.

3. The product of claim 1 or 2, wherein said tobacco particles have a short dimension not in excess of 0.365 inch.

4. The product of claim 1, 2 or 3, wherein said tobacco particles have a geometric mean size of at least 1.74 mm.

5. A smokable tobacco product substantially as hereinbefore described.

6. A method of producing the smokable tobacco product of any one of claims 1 to 5 substantially as hereinbefore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. large pressure drops. It has also been found that the pressure drop variance is smaller as compared with the production standard cigarettes although it is elevated slightly. A smokable tobacco product using small strip tobacco entirely as the tobacco component may be formed from a lesser quantity of tobacco, while retaining physical, chemical and smokable properties similar to those of standard conventional cigarettes. Better utilisation of raw tobacco material can be achieved through the manufacture of cigarettes containing entirely all small strip tobacco. While the present invention has been described in terms of a smokable tobacco product in which the tobacco portion is formed from small strip tobacco, as previously defined, it is to be appreciated that the smokable tobacco product may contain minor amounts of other additives, such as casings, flavorants, and the like. WHAT WE CLAIM IS:

1. An improved smokable tobacco product comprised of a tobacco portion surrounded by a cylindrical wrapper, wherein said tobacco portion consists essentially of irregular tobacco particles having a mean ratio of area to perimeter squared of at least 0.049, a short dimension not in excess of 0.5 inch and an arithmetic mean size of at least 1.93 mm, said particles being of a substantially normal particle size distribution.

2. The product of claim 1, wherein at least 70% of said particles have a mean ratio of area to perimeter squared of from 0.037 to 0.065.

3. The product of claim 1 or 2, wherein said tobacco particles have a short dimension not in excess of 0.365 inch.

4. The product of claim 1, 2 or 3, wherein said tobacco particles have a geometric mean size of at least 1.74 mm.

5. A smokable tobacco product substantially as hereinbefore described.

6. A method of producing the smokable tobacco product of any one of claims 1 to 5 substantially as hereinbefore described with reference to the accompanying drawing.