CA1047241A

CA1047241A - Foam smoking materials

Info

Publication number: CA1047241A
Application number: CA221,636A
Authority: CA
Inventors: Roger W. Hedge
Original assignee: British American Tobacco Co Ltd
Current assignee: British American Tobacco Investments Ltd
Priority date: 1974-03-12
Filing date: 1975-03-06
Publication date: 1979-01-30
Also published as: BE826000A; FI750703A; FI59705B; NL182194B; BE826600A; CH593636A5; NO145676B; ES435499A1; JPS51110100A; DE2509336B2; ZA751294B; NL182194C; IT1046198B; SE426435B; DE2509336C3; FR2263711A1; GB1475315A; DK97775A; FR2263711B1; NO750791L

Abstract

ABSTRACT
A smoking material comprised a binder consisting wholly or in part of a thermo-gelling substituted cellulose having a degree of substitution of at least 1.5 methoxyl groups per anhydroglucose unit, and an inert water-insoluble inorganic diluent such as chalk, which material has a density reduced by the entrainment and dispersion of air therein. The binder may comprise a thermo-gelling methyl cellulose having a degree of substitution of a least 1-5 methoxyl groups per anhydroglucose unit and/or an additionally substituted least 1-5 methoxyl groups per anhydroglucose unit. It may additionally include a thermo-gelling cellulose having a lower degree of substitution or a non-thermo-gelling substituted cellulose.
The invention is also concerned with a method of producing the said smoking material.

Description

This invention concerns improvements relating to non-tobacco loking materials, that is smoking materials which contain no tobacco other than a possible content of tobacco extract. The materials may be used alone as tobacco substitutes, but are prefer-ably used in ad~ixture with tobacco or reconstituted tobacco or other smoking materials, It is an object of this invention to provide advantageous non-tobacco smoking materials of low density, and a method for their production.
In accordance with the invention, a non-tobacco smoking mate-rial comprises a binder consisting wholly or in at least a propor-tion of 10% by weight of thermo-gelling substituted cellulose having a degree of substitution of ~t least 1.5 methoxyl groups per an-hydroglucose unit, and an inert water-insoluble inorganic diluent, which material has had its density reduced by the entrainment and disper~ion of air therein to provide a foam material comprising closed air cells. The use of this particular binder permits the production of a smoking material whose density has been reduced by the entrainment and dispersion of air without recourse to foaming by the use of a surfactant or a blowing agent in the form of a vapour-releasing substance such as bakin~ powder or a dissolved or dispersed volatile solvent such as heptane. The material will not contain chemical residues of surfactant or vapour-releasing sub-stances. Such residues would normally be considered to have an un-~- desirable effect on the smoke properties.
The s~oking material may also comprise a content of caramel and/or tobacco extract. It may further contain a humectant, such as glycerol or sorbitol or other material well known in the art.
` The physical and smoke properties of materials whose density has been reduced by means of entrainment and dispersion of air are different from those of materials whose density has not been so re-.

~04724~
duced and from those of a mere mixture of binder and filler.
By a thermo-gelling substituted cellulose is meant one which forms a thermo-gelling solution in water, that is a solution whose viscosity increases sharply with increasing temperature in a partic-ular temperature range dependant on the substance. The thermo-gelling substituted cellulose employed may be a methyl cellulose and/
or an additionally substituted methyl cellulose having at least the aforesaid degree of substitution. Such methyl cellulose may be used ; in a & ixture either with a methyl cellulose of lower methQxy content or with a non thermo-gelling substituted cellulose such as sodium i; .
carboxymethyl cellulose. The purpose of the invention, namely the production of a non-tobacco smoking material of low density without using blowing agents, cannot be satisfied in such admixtures unless ~ at least one tenth of the binder consists of thermo-gelling methyl ;, cellulose or additionally substituted methyl cellulose of at least the aforesaid methyoxy content. By additionally substituted methyl ,~ cellulose is meant a methyl cellulose containing a proportion of - carboxymethyl or other like substituents. A sufficiently high methoxy content for the said purpose of the invention will generally ~' 20 be a degree of substitution referred to as "high" by manufacturers of such products, this degree of substitution usually being in the range of 1.5 bo 2.4 methoxy units per anhydroglucose unit. Because ,:, of the nature of these products, however, which are intrinsically variable, the exact degree of substitution is not always specified ;,-., by manufacturers.
Also in accordance with the invention, a method of producing such a non-tobacco smoking material comprises mixing a binder con-sisting wholly or in at least a proportion of l~h by weight of thermo-gelling substituted cellulose having a degree of substitution of at least 1.5 methoxyl groups per anhydroglucose unit with an ~ ` -2-10~7241`
inert water-insoluble inorganic diluent and reducing the density c the resulting material by entraining and dispersing air in the mixture to provide a foam material comprising closed air cells.
Suitably, a planetary mixer is used to disperse and dissolve the constituents in water prior to the bringing of the material to a state for suitable use in a smoking mixture. This type of mixer itself whips a proportion of air into the slurry being prepared. However, an acceptably uniform product containing air bubbles, preferably small closed bubbles, in large numbers cannot be so obtained. It......

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1047~41 is necessary and indeed advantageous to utilise a high-shear mixer, for example the E.T. Oakes continuous automatic mixer, which has provision for the introduction of a controlled further quantity of air, over and above such air as may be introduced by the action of the planetary mixer, as well as provision for circulating temperature-controlled hot water through the jacket of the mixer head. Advantageously, the mixture is brought to a temperature in the range of 35 to 60C. The effect of the high shear mixer is principally a reduction in air-bubble size. The maximum bubble size should be less than the thickness, and preferably less than half the thickness, of the sheet material to be produced, so that, substantially, the bubbles do ~ot break the surface ; of the sheet. By the aforesaid method, a uniform foam material with closed cells can be reliably reproduced with-out the use of additional foaming, blowing or like agents and without the necessity for close observance of conditions involved in foaming or blowing with the used of such agents.
The inert inorganic diluent or filler is advantage-ously calcium carbonate (chalk or whiting), but other compounds such as calcium sulphate (gypsum), calcium phosphate, alum-` inium trihydrate, aluminates or the like may be used, provided ` they are insoluble in water.
The composition may comprise also a content of caramel ; or tobacco extract. Caramel may serve as a complete or partial replacement for tobacco extract known as a constituent of ! tobacco substitutes. The composition may further comprise a content of humectant such as glycerol. The composition need contain no other constituents.
Suitable proportions of the constituents by weight are, , l~i'i'241 for example~
~` Binder, 5% to 15%, in which the substituted cellulose ofthe aforesaid high methoxy content should be from 10% to I00% of the binder. Preferably the binder content is from 7% to 13%.
Caramel and/or tobacco extract, 2% to 20%, but preferably 8% to 16%.
Inert inor~anic diluent, 60% to 90%, but preferably 75%
to 85%.
Humectant, 1% to 10%, but preferably 2% to 6%.
If such a composition is used shredded in mixture with , cut tobacco and/or reconstituted tobacco, the proportion of the composition in the mixture may be within the range of , 1% to 99%, but usually in the range of 5% to 75%, by weight.
The following Examples illustrate how the invention may be carried into effect.
Example 1 O.5 parts of B.P. grade glycerol were added to 51 parts of water in the bowl of a Hobart planetary mixer having . 20 a gate-type beater blade, followed by the addition of 1.6 parts of a commercially available sodium carboxymethyl methyl cellulose (Grade C7501, Henkel Chemicals Ltd., having a viscosity 2,300 cps, approximately, in 2% solution in water at 20C according to the method of Brookfield, and an average methoxyl degree of substitution of 1.67, together with a low, unspecified, degree of substitution of sodium carboxymethyl groups per anhydroglucose unit). The mixture was stirred for one hour before the addition of 15.2 parts of commercial whiting (high purity, 90% smaller than BS 200 mesh). The slurry was stirred for a further two hours in the same mixer .".

i ,' ~ ,' 11)~7241 and the resultant slurry was then fed through an Oakes high- -shear continuous automatic mixer with controllable air injection and provision for circulating temperature-controlled hot water through the jacket of the mixer head. The rotor speed of the Oakes mixer and the temperature of the circu-lated water were adjusted so that the aerated slurry was delivered at a temperature of 42C - 48C to a gate coater and was cast as a sheet on an endless stainless steel band passing through a series of drying chambers, as commonly used in the manufacture of tobacco-sheet products, the air temperature ranging from 80C -to 110C with provision for underband steam heating. The minimum rotor speed of the Oakes mixer to give suitable small air bubbles was 250 rpm.
At the maximum air feed rate to the Oakes mixer at which a coherent product could be formed in this Example the sheet produced had a specific gravity of 0. 25, and specific gravities increasing to 0. 75 were produced as the air-injection flow rate was progressively reduced.
' Example 2 The procedure of Example 1 was followed, except that 0.5 parts of glycerol were added to 60 parts of water followed by the addition of 2.75 parts of the sodium carboxymethyl , methyl cellulose (Grade C7501, Henkel Chemicals Ltd.) which, after one hour of mixing, was followed by the simultaneous addition of 2.5 parts of caramel (65% solids) and 19.25 parts ;
of the whiting. Cast sheets were produced, as in Example 1, with specific gravities in the range 0.3 to 0.8.
ExamE~e 3 The procedure of Example 1 was followed, except that O. 5 parts of glycerol were added to 60 parts of water followed .

10'~'72~

by the addition of 0.75 parts of the sodium carboxymethyl ~ethyl cellulose (Grade C7501, Henkel Chemicals Ltd.), and

2 parts of methyl cellulose (Grade M2500, British Celanese Ltd.~ viscosity 2,200 - 2,800 cps in 2% solution in water at 20C by the method of Ostwald, specified as having a medium degree of methoxyl substitution, the average being in the range of 1.5 to 1.9 methoxyl groups per anhydroglucose ; unit). After one hour of mixing, 2.5 parts of caramel (65% solids) and 19.25 parts of the whiting were added.
Sheets were produced, as in Example 1, with specific gravities over the range 0.4 to 0.8.
Example 4 ; The procedure of Example 1 was followed, except that 0.5 parts of glycerol were added to 60 parts of water followed by the addition of 0.75 parts of methyl cellulose , (Grade C2026, Henkel Chemicals Ltd., viscosity 2000 - 3000 cps in 2% solution in water at 20C, specified as having a high degree of methoxyl substitution, with an average of 1.8 methoxyl groups per anhydroglucose unit), and 2 parts of methyl cellulose (Grade M2500, British Celanese Ltd.).
After one hour of mixing 2.5 parts of caramel (65% solids) and 19.25 parts of the whiting were added. Sheets were produced as in Example 1, with specific gravities over the range 0.4 to 0.8.
' Example 5 The procedure of Example 1 was followed, except that 0.5 parts of glycerol were added to 60 parts of water followed by 0.75 parts of sodium carboxymethyl methyl ; cellulose (Grade C7501, Henkel Chemicals Ltd.) and 2 parts of sodium carboxymethyl cellulose (Grade F100, British . , ''~

1~47~1 Celanese Ltd., viscosity 80 - 120 cps in 1% solution in water at 25C by the method of Ostwald, with a degree of substitution of 0.5 to 0.7 carboxymethyl groups per anhydro- -glucose unit). After one hour of mixing, 2.5 parts of caramel (65% solids) and 19.25 parts of the whiting were added. Sheets were produced as in Example 1 with specific gravities over the range 0.4 to 0.8.
Example 6 The procedure of Example 1 was followed, except that 0.5 parts of glycerol were added to 60 parts of water con-taining 1.25 parts (dry weight) of aqueous tobacco extract-ables followed by 0.75 parts of sodium carboxymethyl methyl ; cellulose (Grade C7501, Henkel Chemicals Ltd.) and 2 parts - of sodium carboxymethyl cellulose (Grade F100, British Celanese Ltd.). After one hour of mixing, 1.25 parts of . caramel (65% solids)and 19.25 parts of the whiting were added. Sheets were produced as in Example 1 with specific gravities over the range 0. 5 to 0.9.
; Eixample 7 The procedure of Example 1 was followed, except that ~,~ 0.5 parts of glycerol were added to 60 parts of water followed by 0. 75 parts of sodium carboxymethyl methyl cellu-lose (Grade C7501, Henkel Chemicals Ltd.) and 2 parts of -, sodium carboxymethyl cellulose (Grade F8, British Celanese Ltd., viscosity 5 - 9 cps in 1% solution in water at 25C
by the method of Ostwald, with a degree of substitution of i - 0.5 to 0. 7 carboxymethyl groups per anhydroglucose unit).
After one hour of mixing, 2.5 parts of caramel (65% solids) , and 19.25 parts of the whiting were added. Sheets were produced as in Example 1 with specific gravities over the ., _ .
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range 0.3 to 0.8.
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The procedure of Example 1 was followed except that 0.5 parts of glycerol were added to 60 parts of water followed by 2 parts of sodium carboxymethyl methyl cellu-lose (Grade C7501, Henkel Chemicals Ltd.) and 0.75 parts of sodium carboxymethyl cellulose (Grade F100, British Celanese Ltd.). After one hour of mixing, 2.5 parts of caramel (65% solids) and 19.25 parts of the whiting were added. Sheets were produced as in Example 1 with specific gravities over the range 0. 25 to 0. 7.
Example 9 The procedure of Example 1 was followed, except that 0.5 parts of glycerol were added to 60 parts of water followed by 2 parts of sodium carboxymethyl methyl cellu-lose (Grade C7501, Henkel Chemicals Ltd.) and 0.75 parts of methyl cellulose (Grade M2500, British Celanese Ltd.).
After one hour of mixing, 2.5 parts of caramel ( 65% solids) and 19.25 parts of the whiting were added. Sheets were ` 20 produced as in Example 1 with specific gravities over the range 0.3 to 0.7.
Example 10 - The procedure of Example 1 was followed, except that 0.5 parts of glycerol were added to 60 parts of water followed by 0. 275 parts of sodium carboxymethyl methyl cellulose (Grade C7501, Henkel Chemicals Ltd.) and 2.475 parts of methyl cellulose (Grade M2500, British Celanese Ltd.). After one hour of mixing, 2.5 parts of caramel (65% solids) and 19.25 parts of the whiting were added.
Sheets were produced as in Example 1 with specific gravities .

1047241 ~

over the range 0.4 to 0.8 F~ample 11 The procedure of Example 1 was followed, except that 0.5 parts of glycerol were added to 60 parts of water ;~ followed by 0.35 parts of sodium carboxymethyl methyl cellulose (Grade C7501, Henkel Chemicals Ltd.) and 1.40 parts of methyl cellulose (Grade M2500, British Celanese Ltd.). After one hour of mixing, 2.5 parts of caramel (65% solids) ana 19.25 parts of the whiting were added.
Sheets were produced as in Example 1 with specific gravities over the range 0. 4 to 0.8.
Example 12 The procedure of Exàmple 1 was followed, except that 0.5 parts of glycerol was added to 60 parts of water followed by 0.275 parts of sodium carboxymethyl methyl cellulose (Grade C7501, Henkel Chemicals Ltd.) and 2.475 , ; parts of sodium carboxymethyl cellulose (Grade F100, British Celanese Ltd.). After mixing for one hour, 2.5 parts of caramel (65% solids) and 19.25 parts of the, whiting were added. Sheets were produced as in Example 1 , - .
with specific gravities over the range 0.4 to 0.8.
Example 13 The procedure of Example 1 was followed, except that - the whiting was replaced by the same amount of aluminium trihydrate of similar particle size. Sheets were produced as in Example 1 with specific gravities over the range 0.4 to 0.8.
Example 14 The procedure of Example 3 was followed, except that the whiting was replaced by the same amount of aluminium .~ _g_ , ~ ~
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10472~1 trihydrate of similar particle size. Sheets were produced as in Example 1 with specific gravities over the range 0.4 to 0.8.
h'xample 15 The procedure of Example 1 was followed, except that 1 part of glycerol was added to 60 parts of water followed by 0.6 parts of methyl cellulos (Grade C2026, Henkel Chemicals Ltd.), and 2.4 parts of sodium carboxymethyl ; cellulose (Grade F100, British Celanese Ltd.). After mixing for one hour, 2 parts of caramel (65% solids) and 19 parts of the whiting were added. Sheets were produced as in Example 1 with specific gravities over the range 0.4 to 0.8.
Example 16 The procedure of Example 1 was followed, except that 0.5 parts of glycerol were added to 60 parts of water ~-followed by the addition of 2.75 parts of methyl cellulose (Grade MMPR2, British Celanese Ltd., viscosity 450 - 550 cps in 1.5% solution in 80 : 20 v/v methylene chloride:
methanol at 20C, specified as having a high degree of methoxyl substitution, the average being in the range .
1.5 to 1.9 methoxyl groups per anhydroglucose unit). After mixing for one hour, 2.5 parts of caramel (65% solids) and 19.25 parts of the whiting were added. Sheets were pro-duced as in Example 1, with specific gravities over the range 0.4 to 0.8.
Example 17 The procedure of Example 1 was followed, except that 0.5 parts of glycerol were added to 60 parts of water ; 30 followed by the addition of 2.75 parts of methyl cellulose , ... .

~0~'7241 (Grade M2500, British Celanese Ltd.). After mixing for one hour, 2.5 parts of caramel (65% solids) and 19.25 parts of the whiting were added. Sheets were produced as in Example 1 with specific graviti~s over the range 0.4 to 0.8.
E ample 18 The procedure of Example 1 was followed, except that 0.5 parts of glycerol was added to 80 parts of water followed by the addition of 2.75 parts o~ methyl cellulose (Grade MC4000, Dow Chemical Company, viscosity 3500 -5000 cps in 2% solution in water at 20C according to the method of ~bbelohde, and an average methoxyl degree of substitution of 1.6 to 1.85 methoxyl groups per anhydro-, glucose unit). After mixing for one hour, 2.5 parts of caramel (65% solids) and 19.25 parts of whiting were added.
; Sheets were produced as in Example 1 with specific gravities ; over the range 0.5 to 0.9.
The accompanying diagrammatic drawing illustrates - the combination of apparatus referred to in the Examples:
Water and glycerol, followed by binder and inorganic diluent are mixed in a planetary mixer 1. The mixture is passed to a continuous high-shear mixer 2 with provision indicated at 3 for the controlled introduction of air and means indicated at 4 for the circulation through the mixer ; head of a temperature-control fluid, theatemperature being controlled by a temperature-measuring device 5. The mixer 2 delivers to a gate coater 6 by which the mixture, at the controlled temperature, is applied to a continuously moving steel band 7 on which it is carried through a series of drying chambers 8. The casting and drying apparatus may be of conventional type as used in the known production of reconstituted tobacco-sheet products.
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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A non-tobacco smoking material comprising a binder consisting wholly or in at least a proportion of 10% by weight of thermo-gelling substituted cellulose having a degree of substitution of at least 1.5 methoxyl groups per anhydroglucose unit, and an inert water-insoluble inorganic diluent, which material has had its density reduced by the entrainment and dispersion of air therein to provide a foam material comprising closed air cells.

2. A smoking material according to claim 1, wherein the binder comprises a thermo-gelling methyl cellulose having a degree of substitution of at least 1.5 methoxyl groups per anhydroglucose unit.

3. A smoking material according to claim 1 wherein the binder comprises an additionally substituted methyl cellulose having a degree of substitution of at least 1.5 methoxyl groups per anhydroglucose unit.

4. A smoking material according to claim 2 or 3, wherein the binder comprises, in addition to the said thermo-gelling cellulose having a high degree of substitution, a thermo-gelling cellulose having a lower degree of substitution or a non-thermo-gelling substituted cellulose.

5. A smoking material according to any one of claims 1 to 3 and comprising also a content of caramel and/or tobacco extract.

6. A smoking material according to any one of claims 1 to 3, wherein the binder amounts to 7% to 13% and the diluent to 75%
to 85% by weight of the material.

7. A smoking material according to any one of claims 1 to 3, wherein at least one tenth of the binder is a thermo-gelling substituted cellulose having a degree of substitution of at least 1.5 methoxyl groups per anhydroglucose unit.

8. A smoking material according to any one of claims 1 to 3, with a content of 8% to 16% kg weight of caramel and/or tobacco extract.

9. A method of producing a non-tobacco smoking material which comprises mixing a binder consisting wholly or in at least a proportion of 10% by weight of thermo-gelling substituted cellulose having a degree of substitution of at least 1.5 methoxyl groups per anhydroglucose unit with an inert water-insoluble inorganic diluent and reducing the density of the resulting material by entraining and dispersing air in the mixture to provide a foam material comprising closed air cells.

10. A method according to claim 9, wherein the entrainment and dispersion of the air is effected by high-shear mixing with introduction of a controlled quantity of air.

11. A method according to claim 10, wherein the mixture is brought during the air entrainment and dispersion to a temperature in the range of 35° to 60°C.

12. A method according to claim 9, 10 or 11, wherein the smoking material is produced from the mixture by a drying operation, the entrainment and dispersion of the air being performed prior to the said drying operation.