CA1056588A - Smoking mixtures - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A smoking material in film form comprising a film-forming binder, inorganic filler and a smectite, perticularly a bentonite, which smectite is finely dispersed throughout the material. Fine dispersion is achieved by high energy input during mixing with water, and results in improved ash coherence and greater combustion retardance by the smectite.
The materials are characterised by relatively low air porosity.

Description

~5~:iS8~3 This invantion relates to smo];ing r,ixtures a,,d more particularly to smoking mixtures containing natural or synthetic swelling clays.
Hereinafter we use the term "smectite" to indi-cate a natural or synthetic swelling clay. This usage of the term includes montmorillonite, beidellite, non-tronite, saponite, hectorite and sauconite. Montmorillonite is the principle constituent of bentonite clays which have excep-tionally high watex absorbing and cation exchange properties.
Natural bentonite is a clay mineral consisting e~sentially o montmorillonite, a complex aluminium sili-c-~te. This is naturally associated with cations, chiefly calcium ions but also some sodium ions. Treatment of natural bentonite may alter the relative proportlons of the associated cations or introduce new cations, but the treated products, together with those occuring naturally, are collectively known as bentonites. We may for example refer to calcium bentonites, meaning bentonites in which the associated cations are predominantly but not exclusively calcium, and sodium bentonites, meaning bentonites in which such ions are predominantly but not exclusively sodium.
Smectites in solid form are aggregates of very small particles. In particular, X-ray investigations have revealed that the elementary unit layer of montmorillonite consists of three sheets: An octahedral sheet of hydrar-gillite-brucite included between two tetrahedral sheets of silicon and oxygen. Exchangeable cations occur between silica layers. Accordingly the properties of bentonites and similarly the properties of all smectites are very much influenced by the nature of the associated exchangeable

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cations.
It is known to incorporate smectites, particu-larly bentonites in fabricated smoking materials - for example smoking materials in the form of films or other forms rom which tobacco simulating material can be ob-tained, but hitherto the incorporation has been carried out by slurrying solid smectite and all the other ingre-dients together with water at ambient temperatures and fabricating the slurry, for example into a ilm. By these known techniques the smectite in fabricated smoking materials has not been very finely dispersed, even though some smectites do disperse in water more easily, relative to others, for example sodium bentonites disperse more easily than calcium bentonites.
The degree of disaggregation brought about by agitating a smectite with water increases with the energy input. Under standard conditions of rapid agitation a point is reached where the viscosity reaches a maximum value. Hereinafter the expression "finely dispersed smec-tite" refers to a smectite of such fine dispersion as isproduced by agitating it in water at 15C with an input of 0.04 and preferably 0.08 joules~g/sec until a maximum viscosity is reached.
The invention provides a fabricated smoking mate-rial comprising a film~forming binder, inorganlc filler and a smectite, which smectite is finely dispersed through-- out the smoking material.
Essential ingredients in the smoking materials of the invention are the film forming binder, inorganic filler and smectite but other ingredients may also be in-~05~ 8~1 corporated, especially particulate combustible matter.Further possible ingredients are, for example, humectants e.g. ~lycerol, glycols; glow controlling catalysts e.g.
potassium citrate; colouring matters; flavourants, and nicotine.
As film-forming binders there may be used cel-lulose ethers, for example methyl cellulose and especially carboxymethyl cellulose and its salts. Pectins, starches, mucilage or natural gums are further examples of film-~orming binders which may be used.
If desired the film-forming binder may be used in such proportion as to constitute substantially the whole of the combustible matter of fuel in the smoking material. Preferably however, a non~binding uel, especi-ally a particulate fuel is also used, the main function of the hinder then being to cause all the ingredients to adhere sufficiently well for fabrication of the material.
Particulate fuels which may be used include to-bacco powder; carbohydrates - particularly cellulose; and 20 especially modified carbohydrates, by which we méan carbo- ;
hydrates which have been subjected to a treatment producing modification of a chemical nature.
Desirably the modified carbohydrate which may be used is a thermally degraded carbohydrate t especially thermally degraded cellulose, prepared for example as de-scribed in our United Kingdom Patent No. 1,113,779 by subjecting carbohydrate to a catalysed degradation process at a temperature of 100-250~C until the weight of degraded material is less than 90% of the dry weight of the original carbohydrate.

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The modified carbohydra~e which may be used may also be a solid condensate prepared by acid or base cata-lysed condensation of a compound of the formula:
RlCO CH2.CH2 COR~
(or a precuxsor thereof) wherein Rl and R2, which may be the same or diferent, each represents a hydrogen atom, or an alkyl, hydroxyalkyl or foxmyl group. Such condensates in fabricated form are described and claimed in our United Kingdom Patent No. 1,298,354.
A further example of a modlfied carbohydrate which may be used is oxidised cellulose made for example as de-scribed by Kenyon et al ("Industrial and Engineering Che-mistry", Volume 41, page 2 et seq.).
Smoking materials of the invention containing high proportions, e.g. from 40 to 65% by weight of inor-ganic filler are of especial value. Such high proportions have a beneficial effect in reducing the amount of harm-ful smoke ingredients reaching the smoker. By appropriate choice of the inorganic compounds used, acceptable combus-tion rates may be imparted to smoking mixtures containingfrom 40 to 65% of filler, as is described in our British Patent-No. 1,299,296. In particular the anions in the filler may be citrate, formate, oxalate, tartrate, sili-cate, carbonate, oxide, chloride, sulphate, phosphate or borate. The cations may, in particular, be sodium, potas~
sium, calcium, magnesium, iron or titanium. Preferred fillers are magnesium carbonate, basic magnesium carbonate, calcium borate, sodium borate, sodium chloride, calcium orthophosphate, calcium oxalate, iron sulphate, titanium dioxide, alumina, and especially calcium carbonate.

S~;S~8 Th2 following are typical proportions by weight of the main ingredients of the smoking materials of the invention :
Film forming10 - 50%
Particulate fuel 0 - 30%
Inorganic filler 40 - 65%
Smectite3-10~, especially 3-7 Other ingredients (humectants, flavourants r etc) 0 - 20%
The invention is not however limited to such proportions.
Smoking mlxtures made according to the process of the invention are advantageous compared with correspond-ing mixtures in which smectite is incorporate~ in known manner~ without being finely dispersed.
In particular cigarettes containing the smoking materials of the invention produce a more coherent ash than cigarettes containing the said corresponding mixtures.
This is a discovery of considerable importance in the development of acceptable tobacco substitutes, for the use of high filler proportions, although beneficial on health grounds, leads to the production of flaky non-coherent ash which is no~iceably different from tobacco ash. This ash deficiency is noticeable to the smoker even when the to-bacco substitutes are blended with high proportions of tobacco.
A further advantage of the smoking materials of the invention lies in the increased combustion retardant properties of bentonite when incorporated in dispersed form.
It is therefore possible to avoid or minimise the presence ~os~s~
of other combustion retardants, many of which have unde-sirable ef~ects upon the smoke. In particular magnesium carbonate, a known retardant, gives rise to carbon monoxide.
When an inorganic carbonate particularly calcium or magnesium carbonate is a constituent o~ the inorganic filler it i5 especially desirabl.e for its surface area in the dry state to be not greater than 0.6 sq. m/g and more particularly from 0.2 to 0.3 sq. m/g. In this way the proportion of combustion retardants other than the bento-0 nite itself can still further be minimised.An especially pre~erred ~moking material of the invention, has the ~ollowing final composition:
Film-forming binder 10 - 20%

Particulate fuel, especially thermally degraded cellulose 20 - 3~%

Calcium carbonate of surface area 0.05 to 0.6 sq~ m/g, more parkicularly 0.2 to 0.3 sq. m/g 40 - 50%
Dispersed sodium bentonite3 - 7%
Humectant and any other ingredlents O - 1û%
- A further feature of the invention provides a process fox the manufacture of a smoking material rom ingredients comprising a filler-forming binder, an inorganic filler and a smectite which process comprises mixing said ingredients with water, supplying suficient energy during the mixing operation to cause dispersion of the smectite in the resultant aqueous slurry and fabricating the resultant slurry into a form rom which tobacco-simulating material is obtainable.
In a first embodiment the process of the inven-tion comprises agitating the smectite on water in water ~ttS ~S ~ ~

with such energy input that the viscosity of the slurry is not less than that of a slurry produced by agitating the same smecti-te and water at 15C with an input of 0.0~, pre-ferably 0.08, joules/g/sec until a maximum viscosity is reached, combining the slurry with the remaining ingredients and fabricating the resultant slurry into a form from which tobacco simulating material is obtainable.
In this embodiment af the proces~ the smectite is separately dispersed in water by agitation, preEerably under a sufficiently high energy input to increase the vis-cosity of the slurry up to the value already indicated. Con-veniently the other ingredients of the smoking mixture may be slurried together in conventional manner and combined with the dispersed smectite. After sufficient mixing to produce homogeneity the slurry is then fabricated for example into a filament, tape or sheet. Preferably it is cast into a thin film and dried to form a sheet. Alternatively a thick slurry may be extruded to form a filament, tape or sheet.
As a urther alternative a paper making process may be adopted. The sheet, filament or tape may then be shredded, - or cut, into a tobacco-simulating form.
Smoking materials made according to the above embodiment of the pro~cess have a-more coherent and porous structure than corresponding materials in which the smectite is incorporated, by known techniques. Accordingly films of such materials are characterised by lower air porosity, a parameter which is measurable as described later, in the introduction to the Examples.

.

~(~Sti~l~8 Desirably the air porosity (measured as described later) of a film of smoking material according to the invention O.C5 to 0.2 mm thick should be less than 1000 mlfmin, preferably less than 500 ml/min.
In a second embodiment the process of the in-vention comprises a~itating the smectite together wi-th othex ingredients of the smoking material at a tempera~ure above 50C whereby to disperse the smectite on the slurry, and abricating the resultant slurry into a tobacco simulating form.
Smoking materials made according to the second embodiment of the process exhibit porosities which, though lower than those of corresponding materials made by known techniques, are generally higher than those of correspond-ing materials made by the first embodiment. Nevertheless they are advantageous, like the materials made according to the first embodiment, in that they produce a more cohe-rent ash than the known materials, and in that the combus-tion retardant effect of bentonite, when incorporated in this way, is increased.
The invention is illustrated but not limited by the following examples in which all parts and percentages are by weight.
The commercially available smectites used in the examples were as follows:
Berkonite*- essentially a calcium bentonite, though a sodium carbonate treatment is involved in its production from naturally occurring material.
Aquagel*- a naturally occurring sodium bentonite from U.S.A.

g _ *denotes Trade Mark S~i5~3~

Fulbent 570*- a sodium bentonite prepared by sodi~ car-bonate treatment o~ a natural calcium bentonite.
Berkbent C~*- a sodium bentonite prepared by sodium car-bonate treatment of a natural calci~n bentonite.
_ponite*- a synthetic hectorite product.
Throughout the examples shredded smoking mix-tures, or blends in 50:50 proportion with tobacco shred, were used as filliny for l.l g cigarettes 70 mm l~ng and 25 mm in circumference. The cigarettes were smoked on a standard smoking machine taking 35 ml puffs of 2 seconds duration every minute. Puf~ numbers were estimated, smok-ing each cigarette down to a butt length of 20 mm.
Ash cohesion was estimated by weighing on a microbalance the ash cylinder first falling from the ci-garette on smoking in a draught-free and vibration-free enclusure. The total ash obtained by smoking the complete cigarette was also weighed, and the average ratio of the weight of the first-falling cylinder to the total ash is referred to as the bulk ash cohesion value.
Air porosities were measured on a Bendtsen Mark VI
porosity tester, an instrument by which the observed air-10w through a film can be measured at fixed pressure. Air porosity figures quoted were measured at an air pressure of 75 mm of water using a 5 cm measuring head, and are ex-pressed in ml/min.
The thermally degraded cellulose usèd in several examples was obtained by impregnating cellulose with 7%
ammonium sulphamate solution, compressing so that the cel-lulose retained its own weight of the solution, drying at 165C and then heating at 265C until a loss in weight of *denotes Trade Mark ~05tiS88 25 - 30~ occurred.

Dispersion of the bentonites indicated in Table I
was carried out by agitating 5 parts in 95 parts of water in a recirculating mill (a PUC mill at setting 3) at 45 -50C until constant viscosity was achieved.
Smoking materials were made hy forming the follow-ing ingredients into an aqueous slurry, incorporating the bentonites dispersed as in the previous paragraph casting the slurry on to a`band drier to give a film with a drybasis weight of 48 - 52 g/sq. m and drying and shredding the ilm so obtained. This material was blended in 50:50 proportion with tobacco shred:
Thermally degraded cellulose 26.9 parts Glycerol . 6.0 Calcium carbonate 45.1 "
Ammonium sulphate 2.0 "
Sodium carboxymeth~l cellulose 15.0 Bentonite 5.0 Cigarette tests on the blends, and on comparative blends made by incorporating dry bentonite in the slurries are indicated in Table I, which also includes determinations of air porosity on the films.

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E~MPLES 4 and 5 Dispersion of the bentonites indicated in Table II was carried out by agitating 5 parts in 95 parts of water at 45 - 50C with a low shear turbine impeller (power input 0.007 joules/g/sec. until a maximum viscosity had been achieved.
Smoking mixtures were made by forming the fol-lowing ingredients into an aqueous slurry, incorporating the bentonites dispersed as in the previous paragraph, casting the slurry on to a band drier to give a film with a dry basis weight of 48 - 52 g/sq. m and drying and shred-ding the film so obtained.
This material was blended in 50:50 proportion with tobacco shred:
Thermally degraded cellulose 26.9 parts Glycerol 6.0 ~' Calcium carbonate (marble) 47.1 "
Sodium carboxymethyl cellulose 15.0 "
Bentonite 5,0 "
Cigarette tests on the blends, and air porosity determinations on the films are indicated in Table II.
TABLE II

Bxample Bentonite* Bulk Ash Puff No. Air Poro-_ (dispersed) Cohesion _ sity ml/min 4 Fulbent 570* 61.2 10~2 850 Aquagel* 67.2 9.9 - 75 .
EXAMPLES 6 to 10 In these examples the bentonites indicated in Table III were dispersed in slurries of the other smoking mixture ingredients by stirring at 55 - 65C. The slurries were *denotes Trade Mark ~)5~58~
cast ^n to a band drier to give a fil~ with a dry basis weight Qf 48 - 52 g~sq. cm and the ~ilm dried and shredded.
The composition of these films wàs ~:-Thermally degraded cellulose27 parts Glycerol 6 "
Calcium Carbonate 17 "
Magnesium carbonate 29 "
An~onium sulphate 2 "
Sodium carboxymethyl cellulose15 "
Bentonite 4 "
Two series of films were made:-(a) using coarse calcium and magnesium carbonates having an average surface area of Q.25 m2/g aetermined by the air permeability method described by P.J. Rigden in "Journal of the Society o Chemical Industry" 1943 papers 1 to 4.
(b) using ordinarily available ~inely divided calcium and magnesium carbonates, of average surface areas 0.87 m /g.
50:50 Blends of the shredded films and tobac-co shred were packed into cigarettes and tested as indicated above~ The test results are given in Table III.

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EX~PLE 11 A smoking material was made by slurrying the following ingredients in water at 65C, casting into a film and drying:-Thermally degraded cellulose27 par-ts Glycerol 6 "
Calcium carbonate 15.5 "
Magnesium carbonate 26.5 "
Ammonium sulphate ` 2 Sodium carboxymethyl cellulose 15 "
Berkbent CE* 8 "
For comparison an identically constituted smoking material was made by slurrying at 28C.
Similarly comparative materials were made with-out the Berkbent CE*, the calcium and magnesium carbonate proportions being adjusted to maintain a constant ratio of calcium to magnesium.
Each shredded film was blended with tobacco in 50:50 proportion and cigerettes packed with the blend were tested as indicated above. Test results were given in Table IV.
- TABLE IV
Example Slurry Temp. Puff No. .
_ .. . , 11 60C 12.1 Comparative 28C 11.0 .

Comparative 60C 11.1 No Berkonite CE*

Comparative 28DC 10.6 No Berkonite CE* .

*denotes Trade Mark ~LO~S8i~

.
A smoking material was made by slurrying the following ingredients in water at 60C, casting into a film and drying:-Sodium carboxymethyl cellulose30 parts Glycerol 6 "
Calcium carbonate 28 "
Perlite 28 "
Berkben~ CE* 8 For comparison an identically constituted smoking material was made by slurrying at 28C.
Each shredded film was blended with tobacco in 50:50 proportion and cigarettes packed with the blend were test smoked as indicated above. Test smokings were also made on cigarettes packed with 100% shredded film.
Results are given in Table V.
TABLE V

Example ISlurry Temp. :Puff No. Puff 50;50 blsnd 100%
_ .
.12 60C 10.2Glow-2~ .proofed i Com~arative 28C 9.5, . 7.2 A smoking material was made by slurrying the following ingredients in water at 60C, casting into a film and drying:-Thermally degraded cellulose 27 parts Sodium carboxymethyl cellulose 15 "
Glycerol 6 "
- Calcium carbonate 16 "

Perlite (Celite PFl grade)* 28 Berkbent CE* 8 "
*denotes Trade Mark For comp~xison an identically constitute~ smoking material was mad~ by slurrying at 2~C.
Each shredded ~ilm was blended with tobacco in 50:50 proportion and cigarettes packed wi~h the blend were test smol,ed as indicated above, Test smokings were also made ~n cigarèttes packed with 100% ~hredded film. ~esults are given in Table VI.
TABLE VI
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Example Slurry Temp, Pu~f ~o. Puf ~.
~50:50 blend) 100%
_ . .... _ 13 60C 10,5 8.
~o~r~ti-e 28C 9.3 7.6 A smoking material was made by slurrying ~he following ingre~i~nts in water at 60C, ca~ti~g into a fi~m j and drying:- .
Thermally degraded cellulose 27 parts - Glycerol - 6 parts Calcium Sulphate ~2 parts ~mmonium Sulphate .2 parts 2~ Sodium carboxymethyl cellulose 15 parts Berkbent CE* 8 parts For c~mpa~ison an identically constituted smoking mixture was made by slurrying at 28Co Bach shredded film was blended wi~h tobacco in 50:50 proportion and cigarettes packed with the blend were test smoked as inaicated aboveO Results are given in Table VII, TABLE VII

j Example Slurry temp j Puff No 14 60 C 14r2 Comparative 28C 1307 . *denotes Trade Mark ~s~
EXP~IPLE 15 An aqueous dispersion was made by vigorously agitating 3 parts of Laponite* in 97 parts of water at 45 - 50C until constant viscosity was achieved.
A smoking material was made by forming the following ingredients into an aqueous slurry, incorporat-ing the Laponite* as a dispersion and casting the sIurry onto a band dryer to ~ive a film.
For comparison an identicall~ constltuted smoking mixt~re was made, introducing the Laponite* as a dry powder into the slurry, Each shredded fi~m was blended with tobacco in 50:50 proportion and cigarettes packed with the blend were test smoked as indicated above. Test smokings were ; also made on cigarettes packed with 100% shredded film.
- Results are given in Table VIII.
TABLE VIII

, - ~ . _ . _ . .
Example Puff ~o. Pu~f ~o.
_ (50:50 blend) _ (100%) 20 15 11.9 12.4 Comparative _ 11.5 _9.5 _ *denotes Trade Mark

Claims (15)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for the manufacture of a smoking material from ingredients comprising a combustible film forming binder, inorganic filler and a smectite which process comprises dispersing the smectite separately in water by agitation to produce a slurry having a viscosity not less than that of a slurry made from the same smectite and water by agitation at 15°C with an energy input of 0.04 joules/g/sec until a maximum viscosity is reached, there-after mixing the slurry with the remaining ingredients and fabricating the resultant slurry mixture into a form from which a tobacco-simulating material is obtainable.

2. A process according to Claim 1 wherein the viscosity of the slurry is not less than that of a slurry made from the same smectite and water by agitation at 15°C with an input of 0,08 joules/g/sec until a maximum viscosity is reached.

3. A process according to Claim 1 wherein the combustible film-forming binder is the only combustible ingredient of the smoking material.

4. A process according to Claim 1 wherein the ingredients further comprise a non-binding fuel.

5. A process according to Claim 1 wherein the ingredients further comprise a particulate fuel.

6. A process according to Claim 5 wherein the particulate fuel is a thermally degraded carbohydrate.

7. A process according to Claim 5 wherein the particulate fuel is thermally degraded cellulose.

8. A process according to Claim 1 wherein the film-forming binder is sodium carboxymethylcellulose.

9. A process according to Claim 1 wherein the inorganic filler constitutes 40 to 65% by weight of the ingredient.

10. A process according to Claim 1 wherein the ingredients are constituted by 10-50% by weight of film-forming binder, 0-30%
by weight of particulate fuel, 40-65% by weight of inorganic filler, 3-10% by weight of smectite and 0-10% by weight of humectants and flavourants.

11. A process according to Claim 1 wherein the smectite constitutes 3-7% by weight of the weight of the ingredients.

12. A smoking material manufactured by the process of Claim 1, 2 or 3.

13. A smoking material manufactured by the process of Claim 4, 5 or 6.

14. A smoking material manufactured by the process of Claim 7, 8 or 9.

15. A smoking material manufactured by the process of Claim 10 or 11.