United States Patent 19
`Keritsis et al.
`
`11)
`45
`
`Patent Number:
`Date of Patent:
`
`4,510,950
`Apr. 16, 1985
`
`54)
`
`(75)
`
`73)
`
`Assignee:
`
`21
`22
`(51)
`52)
`
`58
`
`56
`
`FOAMED, EXTRUDED,
`TOBACCO-CONTAINING SMOKING
`ARTICLE AND METHOD OF MAKHNG
`SAME
`Inventors: Gus D. Keritsis; Walter A. Nichols,
`both of Richmond, Va.
`Philip Morris Incorporated, New
`York, N.Y.
`Appl. No.: 457,505
`Fied:
`Dec. 30, 1982
`Int, C. ................................................ A24B 3/14
`U.S. C. .................................... 131/353; 131/358;
`131/369; 13 1/375; 13 1/77; 131/78; 131/79;
`131A364
`Field of Search ................ 131/309, 310, 352-358,
`131/364, 369-375, 77-79
`References Cited
`U.S. PATENT DOCUMENTS
`235,886 12/1880 Lindsley .............................. 131/370
`2,433,877 1/1948 Wells et al. ......................... 131/370
`2,445,338 7/1948 Sowa ................................... 131/370
`2,485,670 10/1949 Sowa et al. ......................... 131/370
`2,592,553 4/1952 Frankenburg et al. ............. 131/370
`2,598,680 6/1952 Frankenburg ...................... 131/370
`3,085,580 4/1963 Muth ................................... 131/370
`3,098,492 7/1963 Wurzburg et al................... 131/370
`3,203,432 8/1965 Green et al. ........................ 31/370
`3,209,763 10/1965 Parmele et al. ..................... 31/370
`3,223,090 2/1965 Strubel et al. ....................... 131/370
`3,353,541 1/1967 Hind et al. .......................... 131/370
`3,364,935 l/1968 Moshy et al. ....................... 131/370
`3,373,751 3/1968 Wallberg............................. 31/370
`3,404,691. 10/1968 Moshy et al. ....................... 131A370
`3,410,279 11/1968 Moshy, et al. ....................... 131/370
`3,528,434 9/1970 Halter et al. ........................ 131/370
`3,529,602 9/1970 Hind et al. .......................... 31/370
`3,820,548 6/1974 Buchmann et al. ................. 131/359
`3,894,544 7/1975 Egri..................................... 131/370
`3,931,824 1/1976 Miano et al. ........................ 131/359
`3,932,081
`M1976 Buchmann et al. ................. 13/370
`4,233,993 1/1980 Miano et al. ........................ 13/357
`4,333,484 6/1982 Keretsis ............................... 131/359
`4,340,072 7/1982 Bolt et al. ............................ 131/370
`4,347,855 9/1982 Lanzillotti et al. ................. 13/370
`
`4,391,285 7/1983 Burnett et al. ...................... 131/370
`FOREIGN PATENT DOCUMENTS
`1167717 4/1964 Fed. Rep. of Germany .
`275420 9/1949 Switzerland .
`282369 11/1927 United Kingdom .
`2064296 6/1981 United Kingdom .
`OTHER PUBLICATIONS
`Defensive Publication T912,011, Harpham et al., Pub
`lished Jul. 24, 1973.
`Primary Examiner-V. Millin
`57
`ABSTRACT
`A substantially cylindrical foamed, extruded, tobacco
`containing smoking article is provided which has prop
`erties substantially equivalent to those of a conventional
`cigarette and which contains from about 5 to about 98
`wt.% of tobacco particles having a particle size of up to
`about 5 mesh, from 0 to about 60 wt.% of a filler having
`a particle size of up to about 350 um mesh, from about
`2 to about 40 wt.% of a cellulosic binder selected from
`the group consisting of hydroxypropyl cellulose, car
`boxymethyl cellulose, and its sodium, potassium and
`ammonium salts, cross-linked carboxymethyl cellulose,
`and its sodium, potassium and ammonium salts, hydrox
`yethyl cellulose, ethyl hydroxyethyl cellulose, hydrox
`ypropyl methyl cellulose, methyl cellulose, ethyl cellu
`lose, and mixtures thereof, and from about 5 to about 20
`wt.% water. The article has a density within the range
`of from about 0.05 to about 1.5 g/cc. The method of
`making such articles comprises the steps of (a) dry
`blending from about 5 to about 98 wt.% of the tobacco
`particles having an OV value of from about 3 to about
`20%, with from 0 to about 60 wt.% of a filler and
`having a particle size of up to about 5 mesh, and from
`about 4 to about 40 wt.% of the cellulosic binder; then
`(b) admixing this dry blend with water to form a wet
`blend containing from about 15 to about 50 wt.% of
`water; then (c) extruding the wet blend under extrusion
`conditions of temperature and pressure such that as the
`wet blend is extruded the moisture in the blend is con
`verted to steam thereby foaming the article.
`
`17 Claims, No Drawings
`
`
`
`Philip Morris Products, S.A.
`Exhibit 1017
`Page 001
`
`

`

`1.
`
`FOAMED, EXTRUDED, TOBACCO-CONTAINING
`SMOKING ARTICLE AND METHOD OF MAKING
`SAME
`
`O
`
`15
`
`25
`
`35
`
`4,510,950
`2
`The method of making the smoking article comprises
`forming an aqueous slurry of the cellulosic material,
`preferably in the form of loose and slightly beaten cellu
`lose fibers, adding from about 5 to 40 percent by weight,
`based on the cellulosic material, of the metal salt; adding
`a foaming or blowing agent to the resulting slurry under
`conditions which do not allow the foaming or blowing
`agent to foam the slurry; and casting or extruding the
`slurry and than drying the cast or extruded slurry under
`such conditions wherein the slurry is foamed during the
`casting or extruding step or during the drying step.
`The organic acid is preferrably selected from the
`group consisting of formic acid, acetic acid, propionic
`acid, butyric acid, valeric acid, methylvaleric acid, iso
`Valeric acid, hexanoic acid, heptanoic acid, octanoic
`acid, benzoic acid, phenylacetic acid, citric acid, malic
`acid, tartaric acid, gluconic acid, and malonic acid and
`its lower alkyl derivatives, and combinations thereof.
`The inorganic acid is selected from the group consisting
`of hydrochloric acid, sulfuric acid, phosphoric acid,
`carbonic acid and combinations thereof.
`The slurry may also include from about 3 to 40 per
`cent by weight of an additive selected from the group
`consisting of pectins and their sodium, potassium, am
`monium, calcium or magnesium salts, alginic acid and
`its sodium, potassium, ammonium, calcium or magne
`sium salts, and combinations thereof.
`The foaming agent is preferably added to the slurry
`while the slurry is under sufficient pressure to prevent
`premature foaming of the slurry. The foaming agent is
`selected from the group consisting of air, steam, inert
`gases, volatile hydrocarbons, and combinations thereof.
`Preferably, the foaming agent is selected from a group
`consisting of ammonium carbonate, ammonium carba
`mate, azides, hydrazides, peroxides, azodicarbonamide,
`and combinations thereof.
`Among the objects of the present invention are the
`following:
`to provide a foamed, extruded, tobacco-containing
`smoking article which exhibits superior combustion
`properties and taste, as compared to those smoking
`articles produced by the aforementioned methods;
`to provide a method of making such foamed, ex
`truded, tobacco-containing smoking articles.
`SUMMARY OF THE INVENTION
`A substantially cylindrical, foamed, extruded, tobac
`co-containing smoking article is provided which has
`properties substantially equivalent to those of a conven
`tional cigarette and which comprises from about 5 to
`about 98 wt.% tobacco particles having a particle size
`of up to about 5 mesh, from 0 to about 60% of a filler
`having a particle size of up to about 350 pum, from about
`5 to about 20 wt.% water, and from about 2 to about 40
`wt.% of a cellulosic binder selected from the group
`consisting of hydroxypropyl cellulose, carboxymethyl
`cellulose, and its sodium, potassium and ammonium
`salts, cross-linked carboxymethyl cellulose, and its so
`dium, potassium and ammonium salts, hydroxyethyl
`cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl
`methyl cellulose, methyl cellulose, ethyl cellulose, and
`mixtures thereof; preferably hydroxypropyl cellulose,
`carboxymethyl cellulose or both. The article has a den
`sity within the range of from about 0.05 to about 1.5
`g/cc, and a preferred diameter within the range of from
`about 2 to about 35 mm.
`The article may also include from about 0.1 to about
`15 wt.% of a polyfunctional acid, preferably citric acid,
`
`BACKGROUND OF THE INVENTION
`The present invention relates to tobacco-containing
`Smoking articles and a method of making same. More
`particularly, the present invention relates to foamed,
`extruded, tobacco-containing smoking articles and to a
`method of making such articles.
`It is known to make non-foamed, extruded, tobacco
`containing smoking articles such as are disclosed in
`commonly assigned, co-pending application Ser. No.
`148,124, filed May 9, 1980. The tobacco-containing
`smoking articles disclosed in that application are articles
`wherein tar delivery during combustion is controlled by
`adjusting the density, porosity, surface area or composi
`tion of the article. The article comprises a coherent
`20
`mass of combustible tobacco-containing material hav
`ing at least one through passage extending from a first
`opening in the surface of the mass to a second opening,
`remote from the first. The coherent mass is of a density
`and porosity such as to substantially occlude gas flow
`through the mass, while also being of a porosity suffi
`cient to support combustion of the mass when ignited.
`A method of making the smoking articles of applica
`tion Ser. No. 148,124 is disclosed in commonly assigned
`U.S. Pat. No. 4,347,855 which issued Sept. 7, 1982.
`30
`According to this method, a combustible tobacco mate
`rial is mixed with one or more other ingredients, includ
`ing a liquid, to provide a tobacco mixture which is then
`shaped under pressure into a discrete coherent mass; at
`least one passage is provided through the mass, and then
`the mass is dried. The mixture composition is selected
`and the shaping pressure and drying are controlled to
`impart to the mass a density and porosity such as to
`substantially occlude gas flow therethrough, and a po
`rosity sufficient to support combustion of the shaped
`40
`mass when it is ignited.
`Formation of the coherent mass is preferably effected
`by extrusion of the tobacco mixture, which, for this
`purpose, preferably contains comminuted tobacco of
`mesh size less than about 30 mesh, and in an amount
`45
`sufficient to provide a solids content in the mixture of
`from about 55 to about 75 weight percent. The burn
`characteristics of the tobacco article produced accord
`ing to this method are improved by further processing
`the dry and coherent mass by re-wetting and subse
`quently re-drying the mass.
`Commonly assigned U.S. Pat. No. 4,333,484, which
`issued June 8, 1982, discloses a modified cellulosic
`smoking material and a method for its preparation. The
`material does not contain tobacco and affords reduced
`55
`particulate matter and puff count while having the fla
`vor and aromatic qualities of natural tobacco. The
`smoking material comprises cellulosic material having
`incorporated therein a metal salt selected from the
`group consisting of calcium salts, magnesium salts, iron
`salts, and aluminum salts of various organic or inorganic
`acids. The cellulosic material is preferably selected
`from the group consisting of carboxymethyl cellulose
`and its salts, cross-linked carboxymethyl cellulose and
`its salts, methyl cellulose, hydroxypropyl methyl cellu
`lose, hydroxypropyl cellulose, ethyl cellulose, ethyl
`hydroxyethyl cellulose, hydroxyethyl cellulose, and
`combinations thereof.
`
`50
`
`60
`
`65
`
`Philip Morris Products, S.A.
`Exhibit 1017
`Page 002
`
`

`

`15
`
`4,510,950
`3
`4
`from about 0.001 to about 1 wt.% of an alcohol selected
`amount within the range of from about 5 to about 98 wt.
`from the group consisting of ethanol, methanol, isopro
`%, preferably from about 25 to about 98 wt.%.
`panol, n-propanol and mixtures thereof, preferably eth
`The cellulosic binder is present in an amount of from
`anol, and may also desirably include from about 0.1 to
`about 2 to about 40 wt.%, preferably from about 2 to
`about 40 wt.% of a cross-linked stiffening agent.
`about 30 wt.%. The cellulosic binder is preferably
`selected from the group consisting of hydroxypropyl
`A method of making such a foamed, extruded, tobac
`co-containing smoking article is also provided and com
`cellulose, carboxymethyl cellulose, and hydroxyethyl
`prises the steps of (a) dry blending from about 5 to about
`cellulose, and mixtures thereof. A mixture of carboxy
`98 wt. 2 of comminuted tobacco particles having a
`methyl cellulose and hydroxypropyl celluose is particu
`particle size of up to about 5 mesh and an OV value of 10
`larly preferred.
`from about 3 to about 20%, with from 0 to about 60 wt.
`A portion of the cellulosic binder may be substituted
`% of a filler having a particle size of up to about 350
`with a compound (hereinafter "the compound') se
`um, and from about 2 to about 40 wt.% of the cellulosic
`lected from the group consisting of pectin and its so
`binder; then (b) admixing this dry blend with water to
`dium, potassium and ammonium salts, guar, starch,
`form a wet blend containing from about 15 to about 50
`hemicellulose, curdlan, a salt of xanthamonas gum,
`wt.% of water; then (c) extruding the wet blend from
`carageenan, oxycellulose, polyvinyl alcohol, vinyl ma
`step (b) under extrusion conditions of temperature and
`leic anhydride polymer, a vinyl maleic acid polymer,
`pressure such that as the wet blend is extruded, the
`and its sodium, potassium, and ammonium salts, micro
`moisture in the wet blend is converted to steam, thereby
`crystalline cellulose, fibrous cellulose, and mixtures
`foaming the article.
`thereof, such that the total amount of the compound
`plus the cellulosic binder falls within the ranges given
`DESCRIPTION OF THE PREFERRED
`for the cellulosic binder.
`EMBODIMENTS
`The smoking article contains from about 5 to about 20
`The foamed, extruded, tobacco-containing smoking
`wt.% water, which is typically measured as oven vola
`25
`articles of the present invention contain, as essential
`tiles (OV). Preferably, the smoking article contains
`ingredients, tobacco particles, water, and a cellulosic
`from about 8 to about 17 wt.% water. This water, or
`binder selected from the group consisting of hydroxy
`moisture content, is selected in conjunction with the
`propyl cellulose, carboxymethyl cellulose, and its so
`other weight ranges of additives in order to achieve the
`dium, potassium and ammonium salts, cross-linked car
`optimum degree of firmness and the optimum burn
`30
`boxymethyl cellulose, and its sodium, potassium and
`properties.
`ammonium salts, hydroxyethyl cellulose, ethyl hydrox
`The smoking articles of the present invention have a
`yethyl cellulose, hydroxypropyl methyl cellulose,
`density within the range of from about 0.05 to about 1.5
`methyl cellulose, ethyl cellulose, and mixtures thereof;
`g/cc, preferably from about 0.10 to about 1.0 g/cc. The
`preferably hydroxypropyl cellulose.
`articles are foamed and thus comprise a porous struc
`35
`As the tobacco particles, comminuted tobacco se
`ture which permits static burning and which also per
`lected from the group consisting of bright, burley, ori
`mits the passage of smoke through the article to the
`ental, and mixtures thereof, comminuted reconstituted
`smoker without the provision of any passages through
`tobacco, comminuted stems, and tobacco dust or fines,
`the article. The density of the article is related to the
`may be employed. The tobacco may have been previ
`porous structure, and articles having densities within
`40
`ously subjected to a stiffening or expansion process to
`these ranges provide the optimum burn rate and trans
`increase its filling power. The smoking article com
`mission of smoke to the smoker.
`prises from about 50 to about 98 wt.% of the tobacco
`The smoking articles may also include from about
`particles.
`0.001 to about 1 wt.% of an alcohol compatible with
`Whatever the source of the tobacco particles, the
`the cellulosic binder, that is, an alcohol in which the
`45
`particles employed in the present invention will have a
`cellulosic binder is soluble, and which is selected from
`particle size of up to about 5 mesh. Preferably, the parti
`the group consisting of ethanol, methanol, isopropanol,
`cle size will be less than 35 mesh, and more preferably
`n-propanol and mixtures thereof. The alcohol present in
`will be less than 50 mesh. When particle sizes greater
`the smoking article is residual and results from a pre
`than 35 mesh are employed, it is desirable and may be
`ferred practice of adding the alcohol during the forma
`50
`necessary to add a polyfunctional acid, such as citric
`tion of the article in order to lower the moisture content
`acid, during formation of the article in order to achieve
`of the extrudate at the die, which provides a firmer,
`the desired appearance and foaming of the extruded
`more easily handled product that requires less drying.
`article. The polyfunctional acid is added in an amount
`The smoking article may also contain from about 0.1
`such that the smoking article contains from about 0.1 to
`to about 40 wt.%, preferably from about 0.5 to about 20
`55
`about 15 wt. % thereof, preferably from about 2 to
`wt.%, of a cross-linked stiffening agent. The stiffening
`about 10 wt.%.
`agent which is added prior to extrusion and then cross
`The article may also include a filler, which is any
`linked during extrusion is selected from the group con
`particulate material having a particle size of up to about
`sisting of alginic acid, pectinic acid, chitosan, water
`350 un and which is compatible with the other compo
`soluble salts thereof, and mixtures thereof.
`60
`nents of the blend. The filler is preferably selected from
`The smoking articles are preferably formed as sub
`the group consisting of calcium carbonate, magnesium
`stantially cylindrical rods having a diameter within the
`carbonate, calcium oxide, magnesium oxide, calcium
`range of from about 2 to about 35 mm, preferably from
`hydroxide, magnesium hydroxide, alumina, hydrated
`about 4 to about 25 mm. These rods are typically made
`alumina, clay, silica and mixtures thereof; preferably
`in conventional cigarette or cigar lengths and may be
`calcium carbonate. When the filler is added, it is added
`wrapped with cigarette paper, a cigar wrapper, or the
`in an amount within the range of from about 5 to about
`like. The articles may be thus marketed as non-filtered
`50 wt.% and the tobacco particles are added in an
`"cigarettes' and as "cigars'. A conventional filter may
`
`65
`
`Philip Morris Products, S.A.
`Exhibit 1017
`Page 003
`
`

`

`10
`
`4,510,950
`5
`6
`be joined to the "cigarette' by tipping paper to form a
`An alcohol selected from the group consisting of
`ethanol, methanol, isopropanol, n-propanol, and mix
`filtered smoking article.
`tures thereof may be added to the mixture in the ex
`Various flavorants, humectants, or both which are
`truder or during the dry blending step, in an amount of
`typically employed in the manufacture of smoking arti
`from about 2 to about 40 wt.%, preferably from about
`cles, may be added prior to extrusion or may be subse
`5 to about 15 wt. %, in order to lower the moisture
`quently added to the foamed, extruded article before it
`is processed into a commercial product.
`content of the extrudate at the die. This lowered mois
`ture content has been found to correlate with a firmer
`The method of the present invention comprises three
`product, which is more easily handled and requires less
`essential steps, which are: (a) dry blending tobacco
`drying.
`particles with the binder and, optionally, the filler; then
`In some instances, it may also be desirable to add a
`(b) admixing this dry blend with water to form a wet
`stiffening agent during the dry blending step to produce
`blend; and (c) extruding the wet blend under extrusion
`a firmer product. The stiffening agent is added in the
`conditions of temperature and pressure such that as the
`dry blending step in an amount within the range of from
`wet blend is extruded the moisture in the blend is con
`about 0.1 to about 40 wt.%, preferably from about 0.5
`15
`verted to steam thereby foaming the article as it exits
`to about 20 wt.%, and is selected from the group con
`the die of the extruder. As a preferred additional step
`sisting of alginic acid, pectinic acid, chitosan, their
`(d), the extruded product of step (c) is sized to a substan
`water soluble salts, and mixtures thereof. Alginic acid is
`tially cylindrical shape having a diameter of from about
`preferred. The stiffening agents cross link in the pres
`2 to about 35 mm.
`ence of heat with each other or with various cross-link
`f 20
`In step (a), tobacco particles having a particle size o
`ing agents well known to those skilled in the art which
`up to about 5 mesh and an OV value of from about 3 to
`are either present in the blend or which may be added
`about 20%, are dry blended with the filler and the
`for this specific purpose. By way of example, both al
`binder. While particle sizes larger than about 35 mesh
`ginic acid and pectinic acid will cross link with chitosan
`can be employed, the use of such particles makes it
`as well as with polyvalent metal ions as calcium, and
`25
`desirable, and in some instances necessary, to employ
`with amides. Chitosan will cross link with polyfunc
`from about 0.1 to about 15 wt.% of a polyfunctional
`tional acids such as citric acid. These stiffening agents
`acid such as citric acid. The polyfunctional acid acts to
`have been found to have the beneficial property of
`soften the tobacco particles, producing a more homoge
`contributing to the subjective character of the smoke
`nous and elastic mixture. The polyfunctional acid may
`and thus may also be considered as flavorants. Al
`30
`also be employed for the same purpose with mixtures
`though it is preferred to add these agents during the dry
`using smaller particle sizes, but is not required. The
`blending step, they may also be added during the wet
`polyfunctional acid is preferably selected from the
`blending step (b) or immediately subsequent thereto.
`group consisting of citric acid, malic acid, tartaric acid,
`Once the cellulosic binder, the filler and the tobacco
`ethylene diamine tetraacetic acid, phosphoric acid, ma
`particles have been dry blended in step (a), which may
`35
`lonic acid and its C1 to C4 alkyl derivatives, and the
`be carried out in any conventional mixing device, the
`sodium, potassium and ammonium salts of said acids. It
`dry blend is then admixed in step (b) with water to form
`is preferred to use particle sizes less than 35 mesh, and
`a wet blend containing from about 15 to about 50 wt.%
`particularly preferred to use particle sizes of less than 50
`of water. Step (b) is carried out in a conventional mixing
`mesh.
`device, such as a horizontal mixing cylinder, and it is
`As the tobacco particles, any of the possible sources
`preferred to employ a low shear mixer. The amount of
`noted in connection with the discussion of the smoking
`water present in the wet blend is critical in that if the
`article may be effectively employed. It is essential that
`water content is reduced to less than about 15 wt.%,
`the tobacco particles have an OV value within the
`shear at the die increases to the point that the surface of
`range of from about 3 to about 20%, preferably from
`the extruded product becomes porous and rough, which
`45
`about 8 to about 17%. Thus when tobacco dust is used
`results in a less than desirable degree of foaming. At
`as the tobacco particle component of the dry blend, it
`water contents in excess of about 50 wt.%, without
`may be necessary to add an amount of water during the
`alteration of temperature, insufficient energy is supplied
`dry blending step sufficient to achieve the required
`to the formulation to generate foam formation as the
`moisture content.
`product exits the die.
`The cellulosic binder is present in the dry blend in an
`Optionally, in step (a), in step (b) or in step (c), a
`amount within the range of from about 2 to about 40 wt.
`foaming agent may be added to the blend. The foaming
`%, preferably from about 4 to about 30 wt.%. The
`agent is preferably selected from the group consisting of
`optimal amount within these ranges will vary with the
`air, nitrogen, carbon dioxide, ammonium carbonate,
`specific cellulosic binder used. For example, when hy
`ammonium carbamate, an azide, a hydrazide, pentane,
`55
`droxypropyl cellulose is used as the only cellulosic
`hexane, heptane, a halogenated fluorocarbon, pyrrole,
`binder, an optimal amount is at least about 8 wt.%.
`acetone, ethanol, a peroxide, and azodicarbonamide.
`When hydroxypropyl cellulose is not included, an opti
`Some of these foaming agents require the addition of an
`mal amount of another cellulosic binder is at least about
`acid.
`15 wt.%. When hydroxypropyl cellulose is used in
`In step (c), the wet blend is fed into an extruder and
`60
`combination with another cellulosic binder, an optimal
`processed as set forth in greater detail below. The wet
`amount of hydroxypropyl cellulose is at least about 2
`blend is extruded under extrusion conditions of temper
`wt.% in combination with at least 2 wt.% of the other
`ature and pressure such that as the wet blend is ex
`cellulose binder(s) for a total amount within the range
`truded, the moisture in the blend is converted to steam,
`of from 4 to about 40 wt.%. A portion of the cellulosic
`thereby foaming the article. Preferred extruders include
`65
`single screw cooking extruders, which are high tem
`binder may be substituted with one of the above com
`pounds, provided that the total amount of cellulosic
`perature/short time extruders that are essentially Archi
`binder and compound is within the above ranges.
`medean pumps and which have heretofore been em
`
`50
`
`Philip Morris Products, S.A.
`Exhibit 1017
`Page 004
`
`

`

`O
`
`15
`
`4,510,950
`7
`8
`ployed in the food industry, hydraulic piston extruders,
`cles. As these particles are transported forward in the
`ran extruders, and extruders employing an extrusion
`feed zone, there is a positive pumping action with some
`chamber consisting of a male auger and a sleeve which
`compression of the material. This compression pushes
`incorporates a female auger, a spacer ring, and a face
`the particles together into a more solid homogeneous
`plate (or die) to shape the foamed product. It is impor
`aSS.
`tant that the tobacco particles, the cellulose binder, and
`As the material advances toward the die and into an
`any preferred additional ingredients be mixed to form a
`additional zone or zones, this compression is continued
`homogeneous mixture prior to introduction into the
`and the material is subjected to mixing and mild shear,
`feeding bin of the extruder.
`resulting in heating of the extrudate until the particles
`The feeding bin is a starting point common to all
`are transformed into a dough-like mass. There is still a
`extruder systems and is typically located near the ex
`positive pumping effect in these zones that is somewhat
`truder with its purpose being to provide a continuous
`less positive than in the feeding zone.
`source of raw ingredients. The feeding bin receives
`As the extrudate advances toward a final Zone before
`material from a conventional mixer/surge system and it
`the die, the extruder barrel becomes completely filled
`typically discharges into a variable speed metering
`with product. Leakage flow and pressure flow are
`/feeding device. A simple gravity bin with a bottom
`greatest within this final zone, resulting in higher vis
`discharge suffices for the ingredients employed in the
`cous shearing, yielding maximum heat generation
`dry blending step (a).
`through friction. Heat is generated due to the friction of
`A variable speed metering/feeding device is typically
`the particles rubbing against one another and due to the
`employed to take the dry blend away from the feeding
`20
`relative motion of the extrudate against screw and head
`bin and to transport it toward the extruder. This vari
`surfaces.
`able speed feeding device is a key link in the output of
`The final die has two major functions. The first of
`the extruder and sets the extrusion rate. Vibratory feed
`these functions is to offer resistance to the forward flow
`ers and variable speed screw feeders are two commonly
`of the product, thereby creating a condition where
`used metering/feeding devices.
`25
`leakage flow and pressure flow may occur. Secondly,
`An intermediary processing device, typically a hori
`the die shapes the final product. The flow resistance of
`zontal mixing cylinder with either a single shaft or twin
`the die is the single greatest factor of the heat treatment
`counter-rotating shafts, is utilized to admix the water
`given to the product because it has the greatest control
`with the dry blend in step (b). Continuous mixing of the
`over the pressure and, therefore, the shear created
`dry blend with the water is accomplished in the cylin
`within the barrel. It is preferred to maintain a pressure
`der, and from this cylinder the wet blend is fed directly
`at the die within the range of from about 50 to about
`into the extruder barrel. While in the barrel, the product
`2500 psig, more preferably about 150 to about 1500 psig.
`is referred to as "extrudate.'
`In the practice of the method of the present inven
`While the feeding bin, variable speed metering/feed
`tion, it is preferred to employ a die having an orifice
`ing device, and mixing cylinder are all of prime impor
`35
`with a diameter within the range of from about 0.5 to
`tance, the extruder itself is the article of the total system
`about 50 mm, more preferably from about 2 to about 35
`which fulfills the ultimate objective of working and
`mm. Particularly preferred is a die orifice having a
`shaping the product.
`diameter within the range of from 3.2 to 3.8 mm.
`The method will be further described with reference
`Typically, foaming of the product occurs immedi
`to a single screw extruder although other types of ex
`40
`truders may be effectively employed.
`ately after extrusion. This foaming is a result of the
`The product is transported through the extruder bar
`moisture or gas within the extrudate changing from a
`super heated liquid or compressed gaseous state to a
`rel by the extruder screw, complemented by the closure
`gaseous state as the extrudate transfers from the high
`around the screw which is referred to as the "head.'
`pressure environment behind the die to the atmospheric
`The extruder head is jacketed, with the jacket being
`45
`environment just outboard of the die openings.
`suitable for either electrical heating or the circulation of
`The foamed product is typically extruded in the
`water, steam or other liquid thermofluid. This jacketing
`permits minor adjustments in the temperature profile of
`shape of a solid rod which is then sized, preferably to a
`substantially cylindrical shape having a diameter of
`the extruder barrel by, for example, controlling the flow
`of the thermo-fluid within the head jacket. The vast
`from about 2 to about 35 mm, more preferably from
`majority of the thermoenergy within the extruder is
`about 4 to about 25 mm, dried by any conventional
`means, and then processed into completed smoking
`created by the conversion of the mechanical energy into
`heat, but the use of jackets can give an added control
`articles by wrapping with cigarette paper or the like,
`and versatility feature.
`cutting to desired lengths, and, optionally, attaching a
`It is preferred to establish and maintain a temperature
`filter.
`55
`gradient which increases along the length of the ex
`The article may be extruded into a tube or chamber
`truder barrel to a maximum at or just before the die
`which communicates with the sizing apparatus and
`within the range of from about 10 to about 300° C.,
`defines the degree to which the article expands upon
`more preferably about 50 to about 250° C. Thermocou
`foaming. The article may then be further expanded after
`ples are typically installed through the head and into the
`the sizing apparatus by exposure to microwaves or heat
`60
`product flow channel and are connected to either tem
`which volatilize the moisture or other foaming agent
`perature indicators or to automatic temperature control
`remaining in the sized article, thereby causing it to ex
`systems for added control.
`pand.
`The extruder barrel may be built in segments or sec
`While the preferred embodiment of the smoking arti
`tions with the individual screws being separated by
`cle has been described in connection with the extrusion
`65
`shear locks, which give each section its own discrete
`of a cylindrical foamed product, other foamed shapes
`processing capability. Wi