United States Patent [19]
`Selke
`
`[541 METHOD OF PRODUCING A
`RECONSTITUTED TOBACCO PRODUCT
`
`[75]
`
`Inventor: William A. Selke, Stockbridge,
`Mass.
`
`[73] Assignee: Kimberly-Clark Corporation,
`Neenah. Wis.
`
`[22] Filed:
`
`May 21, 1973
`
`[21] Appl. No.: 362,148
`
`[52] U.S.C! ............. 131/140C, 131/143, 131/17 A
`Int, CI ......................... A24b 3/14, A24b 15/08
`[51]
`[58] Field of Search ............. 131/2, 15, 17, 140-144
`
`[56]
`
`2,576,021
`3,020,179
`3,121,433
`
`References Cited
`UNITED STATES PATENTS
`11/1951 Koree ..................................... 131/2
`2/1962 Hess ................................ 131/140 C
`Plunkett et al .................. 131/140 C
`2/1964
`
`[11] 3,860,012
`[4S] Jan. 14, 1974
`
`3.145.717 8/1964 Osborne et al .................. 131/143 C
`
`FOREIGN PATENTS OR APPLICATIONS
`
`1,171,878
`1,230,576
`
`11/1969 Great Britain .................. 131/140 C
`5/1971 Great Britain .................. 131/’140 C
`
`Primary Examiner--Melvin D. Rein
`Attorney, Agent, or Firm--Breitenfeld & Levine
`
`ABSTRACT
`
`[ 57 ]
`Modified tobacco fibers, having reduced bonding abil-
`ity, are produced by cooking tobacco stalk material
`and then soaking the resulting fibers in a caustic solu-
`tion. A combination of tobacco lamina and mid-rib is
`extracted; the fibers remaining after extraction are
`mixed with the modified fibers and the mixture
`formed into a sheet which is impregnated with the ex-
`tract material.
`
`9 Claims, No Drawings
`
`R.J. Reynolds Vapor
`IPR2017-01117
`R.J. Reynolds Vapor v. Fontem
`Exhibit 1017-00001
`
`

`

`3,860,012
`
`METHOD OF PRODUCING A RECONSTITUTED
`TOBACCO PRODUCT
`This invention relates generally to tobacco products,
`and to smokable articles made therefrom. It has partic-
`ular reference to improved reconstituted tobacco
`sheets and to methods of making them.
`A general object of the invention is to provide a re-
`constituted tobacco product; composed exclusively of
`tobacco, the pyrolysis of which engenders a reduced
`proportion of tarry substances in the products of com-
`bustion than is produced by tobacco made without
`non-tobacco additives and without the modification of
`this invention.
`The invention is based on the fact that in a smokable
`article the mildness and flavor of the tobacco, and the
`products of combustion, are affected in large part by
`the immediate environment in which the minute parti-
`cles of combustible tobacco ingredients undergo pyrol-
`ysis. In British Pat. No. 1,I 71,878 it is pointed out that
`pyrolysis in a less confined environment than that in
`which smoking tobacco is usually burned is conducive
`to an improvement in taste and mildness, and engen-
`ders products of combustion having a dimished propor-
`tion of tars.
`Reconstituted tobacco, and the procedures involved
`in making it, are admirably suited to the practice of the
`invention. As is known, one of the procedures involves
`essentially a treatment of natural tobacco to separate
`soluble extractibles from fibers, the conversion of the
`fibers by papermaking techniques into a paper-like fi-
`brous web, and the incorporation in the web of the ex-
`tract to restore the soluble tobacco ingredients. The
`present invention relates to the manufacture of the fi-
`brous web in such a way that the combustible ingedi-
`ents of the finished product, when ignited, undergo py-
`rolysis in a combustion environment beneficially differ-
`ent from that which is usually present. More particu-
`larly, the web is caused to embody a uniformly distrib-
`uted greater void fraction, as hereinafter defined.
`The type of web structure which achieves the inven-
`tion’s objective is one in which there are multitudinous
`small labyrinthine passages and voids uniformly distrib-
`uted throughout the sheet, in contrast to the conditions
`present tn conventional relatively dense but porous
`webs. A web embodying the features of the present in-
`vention is one in which the fibers are bonded together
`in the Ioosest possible way commensurate with the
`maintained existence of a self-sustaining web. The de-
`sired result is brought about by a minimization of the
`degree of bonding of the fibers of which it is composed.
`The term "void fraction" as used herein and in the
`claims is intended to signify the volume, per unit vol-
`ume of tobacco sheet, occ pied by the labyrinthine pas-
`sages and voids referred to. In other words, it is the
`ratio of void volume to total volume. It is determined
`by first measuring the "apparent" or "superficial" spe-
`cific volume (Vt) of the tobacco sheet, then measuring
`the specific volume of only the solid substance of the
`sheet (Vs). The void fraction is equal to
`( v, -
`The superficial specific volume can be found by mea-
`surlng the volume of mercury displaced by a segment
`of fibrous web of known weight, mercury being chosen
`since its high surface tension prevents it from penetrat-
`in~ into the pores and intestices of the web. The second
`specific volume can be calculated from the weight of
`
`the same segment of web in air and the known densities
`of the substances comprising it.
`A number of techniques are disclosed in the above-
`identified British patent for increasing the void fraction
`5 of the fribrous web. However, these techniques, while
`useful, either involve adding non-tobacco material to
`the slurry from which the web is made or arc limited in
`the extent to which they are effective.
`The present invention, on the other hand, provides a
`10 highly effective way of increasing the void fraction of
`the web without using any non-tobacco additives, More
`partiularly, with this invention the void fraction is in-
`creased by adding to the web-making slurry tobacco
`fibers of special character derived from the main stalk
`15 of the tobacco plant.
`According to the invention, tobacco stalks are first
`cooked to individualize the stalk fibers. It is believed
`that the cooking dissolves the lignin in the stalk, thus
`freeing the fibers from each other. Thereafter. the
`20 cooked fibers are treated with a concentrated caustic
`
`25
`
`solution, i.e., a solution of sodium hydroxide (NaOH)
`or potassium hydroxide (KOH). This second step,
`which is carried out at room temperature (about 23°C~,
`removes hemicelluloses, thus reducing the conform-
`ability of the fiber, and changes the fiber surface,
`thereby reducing the bonding ability of the tobacco
`stalk fibers. The treated fibers are then added to the
`suspension of fibers used to make a reconstituted to-
`30 bacco sheet. The resulting sheet has an increased void
`fraction, as compared to an otherwise identical sheet
`not containing the modified fibers of this invention, and
`as a result less tar is produced when a smokable article
`made from the sheet burns.
`35 The idea of cooking tobacco main stalks in a caustic
`soda (NaOH) solution, and using the resulting fibers in
`making wrappers for cigars is described in British Pat.
`No. 1,230,576. However, these fibers retain their high
`bonding ability unless subjected to the second, or alka-
`40 line treatment, step described above.
`It has been found that a reconstituted tobacco sheet
`containing the modified fibers of this invention retains
`its void fraction even if highly compressed when wet.
`Toleration of pressing makes the sheet less delicate for
`45 processing and yields additional latitude during the pa-
`permaking process.
`Illustrative of the features of the invention, and the
`desirable quality of the tobacco product which results,
`are the following examples:
`
`50
`
`EXAMPLE I
`Stalks of bright leaf tobacco were broken up into
`lengths from 4 to 6 inches and cooked for three hours
`at 170°C in a solution containing 60 grams per liter of
`55 sodium hydroxide and 6 grams per liter of sodium sul-
`
`fide.
`Half of the resulting fiber was washed and put aside
`for use in sheet-making and the other half was sub-
`60 jected to further treatments, described below.
`
`EXAMPLE II
`
`65
`
`The fiber from Example I was soaked at room tem-
`perature for 20 minutes in a solution of 20 percent so-
`dium hydroxide. After that period, the caustic solution
`was poured off and the fiber washed repeatedly with
`water. The moisture was determined on an aliquot pro-
`portion and from the weight before and after it was de-
`
`Exhibit 1017-00002
`
`

`

`3,860,012
`
`3
`termined that 29.7 percent of the fiber weight had been
`lost by this extraction.
`
`EXAMPLE III
`
`In order to demonstrate the effect of the extractive 5
`process of Example 1I on the bonding proclivity of the
`tobacco fiber, two laboratory handsheets were made,
`according to known papermaking techniques, of the
`fiber after separately beating samples of the fiber from
`Examples I and II in a Waring blender at a low speed 10
`for 5 minutes. The sheet weight in each case was 54
`grams per square meter. Tensile strengths of these
`sheets were as follows:
`
`4
`trated extract, running it through a ringer and drying it
`This process was continued until the basis weight of the
`sheets reached 100 grams per square meter. These
`sheets were dried and the void fraction determined.
`The tobacco sheets were then shredded and the to-
`bacco used to make cigarettes with a Hauni-Baby labo-
`ratory cigarette machine. The cigarette paper used was
`Schweitzer type 556. The delivery of particulate matter
`of these cigarettes was determined, using the method of
`the United States Federal Trade Commission. The re-
`sults are reported as dry particulate matter, including
`nicotine.
`
`Particulute
`Void Delivery In
`Fraction Milligrams
`
`41
`46
`58
`
`61
`
`66
`
`21.6
`19.2
`14. I
`
`12,7
`
`I 1.2
`
`1850 grams perinch 15
`87 grams per inch
`
`Sample
`
`Treated Fiber Additive
`
`I
`2.
`3.
`
`20
`
`None
`20% fiber from Example I
`10% treated fiber from
`Example I 1
`20% treated fiber from
`Example I I
`40% treated fiber from
`Example 11
`
`Sheet made only of fiber from Example l
`Sheet made only of fiber from Example l I
`(Causted Treated Fiber~
`
`EXAMPLE IV
`
`Using more fiber of the sort prepared in Example I,
`a series of treatments as described in Example II, were
`made with caustic soda solutions. However, solutions
`having different concentrations were used. These con-
`centrations, and the tensile strengths of resulting hand-
`sheets are shown below:
`
`Concentrations
`
`Tensde Strengths
`
`a. 10%Caustic Solution
`b. 15%Caustic Solution
`c. 20% Caustic Solution
`d. 25% Caustic Solution
`
`503 gm/in
`98 gm/in
`87 gm/in
`66 gm/in
`
`It is apparent that the caustic treatment of the fiber
`has somewhat reduced effectiveness with concentra-
`tions as low as I 0 percent. Concentrations higher than
`20 percent are effective, but are unneccessary and ex-
`travagant. Therefore, the preferred range of caustic
`concentration is 15 to 20 percent.
`
`The sheet made with 40 percent of treated fiber was
`25 extremely fragile and could not be handled easily.
`None of the other sheets presented this difficulty.
`In the examples above, the first step or" the prepara-
`tion of the modified tobacco stalk fiber was by means
`of the so-called kraft process, i.e., cooking of the plant
`30 material in a strong caustic solution. Alternatively, this
`first step can be accomplished using a slightly alkaline
`solution of sodium sulfite. When this variation is em-
`ployed, the second step, the treatment with caustic at
`room temperature, has an even more pronounced ef-
`35 feet than it does if the fibers are first prepared with the
`strongly basic cook. The following example illustrates
`this point.
`
`EXAMPLE V
`
`EXAMPLE VI.
`
`In this example, reconstituted tobacco sheets were 40
`made, according to the extraction process, with and
`without the addition of varying amounts of the treated
`stalk fiber.
`The basic reconstituted tobacco was made up of a
`mixture of 50 percent of fine tobacco fragments left 45
`over from the manufacture of cigarettes of so-called
`American blend, 40 percent of midribs of flue-cured
`tobacco, and 10 percent of midribs of burley tobacco.
`The midribs were cut up dry in a Waring blender and
`mixed with the fines. The mixture was steeped in boil- 50
`ing water and the soluble extract removed in a small
`home-type wine press. The mixture was steeped a see-
`ond time and that liquid pressed out. The extract was
`¯ concentrated by evaporation to 34 percent solids.
`The tobacco fiber material left after extraction of the 55
`solubles was put in a laboratory Valley beater and
`beaten until, by visual observation, there were no large
`lumps of midrib apparent in the stock. Portions of this
`stock were mixed briefly with more water in a Waring
`blender and formed into handsheets in a Noble and 60
`Wood laboratory mold. Other sheets were made in
`which treated tobacco stalk fiber from Example II was
`added in varying amounts, it being mixed into the stock
`in the Waring blender prior to sheet formation.
`After drying, these sheets were impregnated with the
`concentrated tobacco extract. This impregnation was
`done by repeatedly immersing the sheet in the (cid:128)oncen-
`
`65
`
`Lengths of tobacco stalk were cooked in a manner
`similar to that used in Example I, but the solution used
`contained 25 grams per liter of sodium hydroxide and
`15 grams per liter of sodium sulfite. This cook was for
`3 hours at 160°C. The cooked fiber, after washing, was
`divided. A portion of it, designated (A) was put aside
`in that condition, and the rest of it, designated (B), was
`treated for one-half hour with a solution of 20 percent
`sodium hydroxide and then washed.
`Handsheets of reconstituted tobacco were made as in
`Example V, except that the modified fibers used were
`in one case 20 percent of the fiber (A) above and in the
`other case 20 percent of the fiber (B). The sheets were
`impregnated, the void fraction determined on portions
`of them, and cigarettes made and smoked to determine
`the delivery of dry particulate matter. Results were as
`follows:
`
`Additive
`
`20% Fiber A
`20% Fiber !~
`
`Particultlte
`Void Delivery in
`Fraction Milligrams ¯
`
`52
`59
`
`20.4
`15.7
`
`In the previous examples, the second step of the fi-
`ber-modifying process employs sodium hydroxide.
`However, as indicated by the following example, potas-
`sium hydroxide can be used in the alternative:
`
`Exhibit 1017-00003
`
`

`

`3,860,012
`
`6
`b. thereafter soaking the cooked stalk fibers in a con-
`centrated caustic solution to produce modified fi-
`bers which do not bond to each other or to other
`fibrous material as readily as do fibers not so modi-
`fied.
`c. separating other natural tobacco material into fi-
`brous material and extract material,
`d. mixing the modified fibers with the fibrous mate-
`rial and forming the mixture by papermaking tech-
`niques into a paper-like web, and
`e. impregnating the web with the extract material.
`2. A method as defined in claim 1 wherein the caustic
`solution is at room temperature.
`
`10
`
`EXAMPLE VIII
`
`Stalks of burley tobacco were broken up and cooked
`in the manner of Example I. A mass of the resulting
`fiber was placed in a beaker and the beaker then filled
`with a solution of 20 percent potassium hydroxide. This
`was stirred briefly and then let stand for 30 minutes.
`After that period, the caustic solution was poured off
`and the fiber washed repeatedly with water. Reconsti-
`tuted tobacco sheets were prepared in a handsheet
`mold using 20 percent of this treated fiber. The sheet
`was subsequently impregnated with concentrated to-
`bacco extract and the void fraction determined at 63
`percent. Cigarettes were made and tested, the delivery
`being 13.2 mg of dry particulate matter. This compares
`favorably with Sample 4 of Example V.
`Therefore, in this specification and the claims which
`follow, the term "caustic"is intended to identify either
`NaOH or KOH.
`Thus, it will be seen that the present invention affords
`a practicable means for reducing the tars produced by
`burning reconstituted tobacco without adding any non-
`tobacco material to the product, but instead by using
`specially treated tobacco fiber.
`The invention has been shown and described in pre-
`ferred form only, and by way of example, and many
`variations may be made in the invention which will still
`be comprised within its spirit. It is understood, there-
`fore, that the invention is not limited to any specific
`form or embodiment except insofar as such limitations
`are included in the appended claims.
`What is claimed is:
`1. A method of making a reconstituted tobacco prod-
`uct for use in a smokable article, comprising the steps
`of:
`a. Cooking natural tobacco stalk material at an ele-
`vated temperature to individualize the stalk fibers,
`
`15
`
`3. A method as defined in claim 1 wherein the caustic
`solution is sodium hydroxide or potassium hydroxide.
`4. A method as defined in claim 1 wherein the caustic
`solution is 10 percent to 25 percent caustic.
`5. A method as defined in claim 1 wherein the caustic
`2O solution is 15 to 20 percent caustic.
`6. A method as defined in claim 1 wherein the to-
`bacco stalk material is cooked in a solution containing
`sodium hydroxide.
`
`25 7. A method as defined in claim 1 wherein the to-
`bacco stalk material is cooked in a solution containing
`sodium sulfite.
`8. A method as defined in claim I wherein the
`amount of modified fibers in the mixture was between
`30 10 and 40 percent of the amount of combined modified
`fibers and other fibrous material.
`9. A method as defined in claim 1 wherein the
`amount of modified fibers in the mixture was between
`10 and 20 percent of the amount of combined modified
`35 fibers and other fibrous material.
`
`40
`
`45
`
`5O
`
`55
`
`6O
`
`65
`
`Exhibit 1017-00004
`
`