GB2185175A - Smoking articles and wrappers and ink for their production - Google Patents

Abstract

Smoking article wrappers carrying dried deposits of an alkaloid such as nicotine or, preferably one of its salts and also, of a water-soluble alkali are disclosed. After manufacture and on exposure to moisture in the atmosphere the alkali causes the alkaloid to migrate from the smoking article wrapper to the smoking material within it, thus increasing its alkaloid content. Compositions comprising particulate alkaloid, or salt thereof, and particulate water- soluble alkali in a non-aqueous carrier, which may be used to make the wrappers, are also disclosed.

Description

SPECIFICATION Smoking Rods and Wrappers and Ink for their Production The present invention relates to smoking rods and their production, in particular to smoking rods having added nicotine.

It is known to add nicotine to smoking products to enhance the sensation due to nicotine, particularly in low tar cigarettes, or to introduce nicotine into smoking products that are free of nicotine. In GB 1111007 nicotine is added to cigarette paper by spraying with an aqueous solution of free base nicotine or of a salt of nicotine. In that specification it is pointed out that nicotine is rapidly lost to the atmosphere if the nicotine is added from an aqueous composition as the free base. This loss is said to be due to the interaction of chalk in the paper with the added nicotine.

In GB 2007078 and GB 2094611 smoking rod wrappers are printed with aqueous inks that contain for instance a stable nicotine salt. In EP 103969 a smoking rod wrapper is printed with aqueous ink containing a solution of a water soluble salt of nicotine and polymeric acid.

The problem with all the known systems for printing onto wrappers is that it is undesirable for the wrappers of the product that is retailed to carry nicotine deposits, for example because the inks tend to show through to the opposite surface of the thin paper used as a wrapper and the yellowing on aging of nicotine on the wrapper is unsightly. Printing techniques do, however, enable the position of the nicotine in the cigarette to be controlled and thus for the profile of nicotine delivery to the smoker to be controlled.

It is known also to form nicotine pectinate into a sheet and to mix shredded sheet material with tobacco used as filler for smoking rods. It is also known to spray synthetic nicotine onto tobacco used as a filler for smoking rods. It is however difficult to control the dose of nicotine to the smoking rods in these techniques and it is impossible to impart profiling of the nicotine within the cigarette.

According to one aspect of the present invention a smoking rod wrapper carries dried deposits of an alkaloid or a salt thereof and carries also water-soluble alkali.

We have found that surprisingly the alkaloid remains on the new wrappers provided they are protected from contact from excessive moisture. When the wrappers come into contact with moisture, the alkali solution formed on dissolution of the alkali in water, reacts with the alkaloid or salt allowing the alkaloid to be released from the wrapper.

We have found that in smoking rods formed from any wrapper printed with nicotine or a derivative the nicotine moves towards a state of dynamic equilibrium between acid on the wrapper, generally the acid of a nicotine salt deposited on the wrapper, and acids in the tobacco filler. In conventional products there is always a large amount of nicotine retained on the wrapper.

In the present invention the alkali neutralises acids on the wrapper, thus making them unavailable for interaction with the alkaloid, so that substantially all the alkaloid is transferred to the filler on exposure of the wrapper to moisture.

Thus, according to a second aspect of the invention, a method of increasing the loading of alkaloid in the filler of a smoking rod comprises forming a rod comprising a new wrapper as described above and causing the alkaloid to transfer from the wrapper to the filler by exposure of the wrapper to moisture. Filler conventionally used in smoking rods comprise a significant amount of moisture, for example between 10 and 25% and this amount is generally sufficient for driving this transfer. Preferably, therefore, the moisture is entirely derived from the tobacco which is the filler for the smoking rod. Preferably at least 90% of the added alkaloid is transferred to the filler after 5 days from the first exposure to moisture.

The new products may be made by depositing either or both the alkaloid or salt and the alkali from aqueous compositions, provided that alkaloid or salt, alkali and water are not present simultaneously during the process. Thus conventional water-based inks containing nicotine salts may be used, provided that the printed product is dried before application of alkali. Usually at least one of the alkaloid or salt and alkali are applied from non-aqueous compositions.

According to a third aspect of the invention a method of producing a new wrapper comprises depositing the alkaloid or salt from a composition comprising a substantially non-aqueous liquid vehicle in which the alkaloid or salt is insoluble.

A non-aqueous alkaloid composition may be deposited onto wrapper already carrying alkali, for instance that has been added to the paper used for the wrapper during its manufacture, or that has been applied to the paper in a subsequent coating or other step. Preferably, however, the method comprises depositing the alkali from a composition comprising a substantially non-aqueous liquid vehicle in which the alkali is insoluble. It is found most suitable to deposit both the alkaloid or salt and the alkali from the same composition.

The composition or compositions may be applied to the wrapper by any known process, for instance by dipping the wrapper material in the compositions, spraying or, most preferably, by printing.

According to a fourth aspect of the invention an ink composition comprises particulate alkaloid or a salt thereof, particulate water soluble alkali and a non-aqueous liquid vehicle that is a non-solvent for both the alkaloid or salt and the alkali.

In the invention the alkaloid may be any alkaloid having the physiological effects associated with the smoking products and is thus generally a derivative or an analogue of nicotine, such as nornicotine or anabasine, and is most preferably nicotine itself.

We have found that in the invention, on contact of moisture with the alkaloid and alkali, alkaloid is transferred from the wrapper to the tobacco filler. Our experiments have shown that alkaloid is transferred from the wrapper to filler adjacent to the wrapper. Thus we have found that, after storing smoking rods manufactured from the new printed wrappers for several days, alkaloid is transferred off the wrapper, to leave the wrapper having little or no more detectable alkaloid than in smoking rods manufactured from unprinted wrappers. The loss of alkaloid from the wrapper may be accounted for by a gain in the total alkaloid content in the smoking rod filler. If for instance the wrapper at one end only of the smoking rod is printed, then the increase in alkaloid content of the filler occurs at that end and not to any detectable extent at the other end.It is thus possible to profile the alkaloid applied to the wrapper and to retain the profile in the filler.

The compositions are most suitably applied to the wrappers by printing. By such techniques profiling of the alkaloid may be conveniently achieved. The intended effect of profiling in a smoking rod is the achievement of a flattened profile of the rate of delivery of nicotine or other alkaloid to the smoker the whole smoking rod.

The use of non-aqueous compositions comprising liquid vehicles in which neither the alkali nor the alkaloid are soluble, is preferred since it enables a single composition containing both components to be used. Wrappers for smoking rods are generally formed from paper, and the use of solvent based compositions avoids the use of water on paper. Aqueous inks render the paper liable to tearing during processing when the inks are wet and tend to leave the paper wrinkled after the drying step. The use of non-aqueous systems avoids or minimises these problems. The solvents used are generally more volatile than water, so that the drying time is reduced. Suitable solvents are alcohols and esters, most preferably ethanol.

The inks used in the invention generally comprise the alkaloid and/or alkali components in particulate form, for instance comprising particles of greater than 5 microns in diameter. The particles are preferably less than 100 microns, most preferably 90% have sizes in the range 10 to 50 microns. It is found that the use of such compositions reduces the strike through of composition through the smoking rod wrapper so that the physical appearance of the smoking rod itself is not damaged. Such compositions also allow a high solids content to be achieved whilst retaining the desired viscosity.

The alkaloid, as stated above, is preferably nicotine. It may be in the form of free base nicotine, thus it may be pure synthetic or natural nicotine, ground tobacco or a combination of both. Preferably however it is in the form of a salt, for instance of a type conventionally used for additive printing onto smoking rod wrappers, generally the salt of an organic acid, for instance a polybasic acid such as citric or, preferably, tartaric acid. Alternatively the acid may be a polymeric acid, such as alginic pectic or other polysaccharide acids, optionally modified to increase their acid content, such salts being disclosed in EP103969.

The alkali is present on the paper in an amount such that free base alkaloid is formed. Thus the amount is generally such that the pH of the solution that is formed on contact with moisture is above 6, preferably above 7 and sometimes more than 8. Generally the pH is less than 9 and preferably less than 8, since high pH's tend to damage the appearance of the smoking rod wrapper. The pH of the solution on the wrapper may be estimated by depositing wrapper into water and allowing the components to dissolve into water.

We have found it convenient to measure the pH of the solution formed when 20 wrappers each having 16 mg print solids are dispersed in 100 ml water.

The alkali must be water-soluble. Thus chalk, as disclosed in GB 1111007, and other forms of calcium carbonate are insoluble and unsuitable for use in the invention. Preferably the solubility of the alkali in water is at least 50 gll at 20"C. The alkali is often a stronger base than the alkaloid so that the reaction equilibrium in a reversible reaction favours formation of the free base alkaloid. Where the reaction with the alkali is irreversible, for instance, involving the release of carbon dioxide, than the alkali may be a weaker base than the alkaloid. The alkali should be stable on the paper during storage. Suitable alkalis are for instance hydroxides of alkali metals or alkaline earth metals and the carbonates, hydrogencarbonates, phosphates and hydrogen phosphates of alkali metals.We have found a convenient alkali to be potassium carbonate.

When the alkaloid is present in the form of a salt then, in order to reduce the amount of nicotine or other alkaloid left on the paper, the amount of alkali should be sufficient or in excess of the amount sufficient to react with all the acid from which the salt is formed. Thus it is preferred that the alkali and alkaloid salt are present in stoichiometric amounts or that the alkali is present in excess of the stoichiometric amount.

It is generally desirable to include a binder in the inks according to the invention. It is found that the transfer of alkaloid to filler is improved by including a hygroscopic binder since this increases the rate at which moisture is taken up by the wrapper in the smoking rods. Suitable hygroscopic binders for use in these non-aqueous liquid compositions are for instance hydroxypropylcellulose, hydroxyethylcellulose carboxymethylcellulose, sodium alginate and sodium pectinate. The binder is generally present in an amount of 2 to 20% by weight of the ink.

The total loading of alkaloid onto the smoking rod wrapper is suitably in the range of 0.5 to 4 mg, preferably in the range 1 to 2 mg. We have found that increasing the overall alkalinity of the smoking rod increases the perception by the smoker of nicotine and thus may reduce the total amount of nicotine required in a smoking rod, which is desirable for reasons of health.

The inks are printed using conventional processes, such as gravure or screen printing and are preferably applied as discrete deposits on the smoking rod wrapper. The frequency and size of the deposits is chosen according to a desired loading of alkaloid. Generally the density is such that the amount of nicotine printed on to a conventional smoking rod wrapper from 50 to 75 mm long is from 1 to 2, preferably about 1.6, mg and preferably substantially all of this is printed on the half of the wrapper distant from the filter or mouth end of the smoking rod. For instance the distribution may be approximately as shown in Figure 3 of GB 2,094,611. Each printed deposit is generally circular or square and may have a maximum transverse dimension typically of 0.25 to 3, generally 0.5 to 1.5 mm.

The following is an example of the invention.

EXAMPLE 1 800C cigarette paper was profile printed at the lighting end of the cigarette rod (top half) with potassium carbonatelnicotine tartrate at 3 mole ratios to determine the optimum acid to carbonate ratio to allow complete migration of nicotine from wrapper to filler.

(a)1:1 (b) 1:1.5 (c) 1:2 mole ratios, inorganic to tartaric acid.

The inks containing the components as in a), b) and c) had a solids content of 35% (by weight) and used ethanol as the liquid vehicle and contained 15% (based on dry solids) of a binder consisting of hydroxypropylcellulose. The particles of potassium carbonate and nicotine tartrate had an average size of 30 microns.

Samples (a) and (b) were prepared by printing the wrapper using a flat screen, to give a free base nicotine loading of 3.5 mgs/cigarette. These wrappers were used to produce hand rolled cigarettes containing blend 40 tobacco.

Sample (c) was printed to give a free base nicotine loading of 1.6 mg/cig. These wrappers were used to manufacture machine made cigarettes using tobacco having a moisture content of 14.5%.

The cigarettes were stored at 58% RH and the nicotine content (as weight of free base) of the wrapper and filler, for both printed and unprinted sections ofthe cigarettes, determined daily, by Gas Chromatography using a flame ionisation detector (FID).

The results are shown numerically in Table 1 and plotted graphically in Fig. 1 where the percentage of added nicotine remaining on the wrapper is plotted as a function of time.

TABLE 1 Time a) b) c) days i ii iii iv i ii iii iv i ii iii iv 0 3.5 8.3 11.8 8.2 3.5 8.3 11.8 8.3 1.7 8.3 10.0 8.3 1 1.3 10.6 11.9 8.2 2.2 10.3 12.5 8.2 2 1.2 11.3 12.5 8.3 1.4 11.3 12.7 8.1 3 0.5 13.1 13.6 8.0 0.8 12.6 13.4 7.9 0.6 9.1 9.7 8.1 4 0.2 12.5 12.7 8.1 0.5 12.8 13.3 8.2 0.5 9.4 9.9 8.2 5 0 12.6 12.6 8.2 0.3 12.9 13.2 8.2 0.4 9.3 9.7 8.2 6 0 12.5 12.6 8.2 0 13.0 13.0 8.2 0.3 9.3 9.6 8.2 7 0 12.6 12.6 8.2 0.2 9.5 9.7 8.2 8 0.2 9.6 9.8 8.1 i) Nicotine on printed wrapper mg/cigarette ii) Nicotine on tobacco from top half cigarette mg.

iii) Total nicotine on top half cigarette (i+ii) mg.

iv) Nicotine on tobacco from bottom half cigarette mg.

The results show that the nicotine lost from the printed wrapper can be accounted for by nicotine gained by filler tobacco and that the integrity of the nicotine profile remains intact, since the nicotine is transferred to the top half only of the cigarette. The results also show that a mole ratio of 1:1.5 carbonate to tartaric acid is sufficient to allow complete migration of printed nicotine from wrapper to filler.

EXAMPLE 2 To accurately determine the level of nicotine remaining on the cigarette wrapper after seven days, samples (b) and (c) from Example 1 were analysed for nicotine content using a gas chromatograph fitted with the more sensitive nitrogen specific detector. The nicotine content of control cigarettes of the type used in each of b and c (made with unprinted wrappers) was determined for comparison. The results are shown in Table 2.

TABLE 2 Sample Time days Nicotine mg/cig c) 0 1671 c) 7 121 control c 7 35 b) 7 22 control b 7 29 The results show that sample b) had no more detectable nicotine on the wrapper after seven days storage than an unprinted wrapper after the same period of time. Sample c) had slightly more nicotine than the controls.

EXAMPLE 3 A further sample was printed, using the process used for sample c) in Example 1 with the potassium carbonate and tartaric acid at a mole ratio of 1:1.5 and a nicotine loading of 1.6 measured as free base and cigarettes factory made to a standard specification.

These cigarettes were then analysed for puff by puff 1A parameters using the combined water/nicotine GC method along with an unprinted control cigarette made to the same specification.

The results obtained are shown in Table 3 are based on four determinations. Table 3 shows the nicotine and PMWNF per puff against puff number for the two types of cigarette. The total nicotine delivery for the test cigarette was 1.251 mg and for the control was 1.112 mg. The total wet tar delivery for the test cigarette was 11.3 mg and for the control was 11.5 mg. The total PMWNF delivery (particulate matter, water and nicotine fee, i.e. dry tar) for the test cigarette was 8.7 mg and for the control was 9.0 mg. The total CO delivery for the test cigarette was 10.7 mg and for the control was 10.0 mg. The total puff number for the test cigarette was 10.36 and for the control was 10.89.

TABLE 3 Test cigarette Control Nicotine PMWNF Nicotine PMWNF Puff No. pg pg pg pg 1 53 478 40 430 2 78 545 62 580 3 95 601 74 577 4 107 677 82 654 5 119 801 93 710 6 124 846 102 788 7 134 966 112 891 8 148 1049 121 996 9 161 1097 136 1074 10 178* 1234* 150 1200 11 54+ 392+ 141" 1186t * 0.98 puffs + 0.38 puffs o 0.89 puffs The results show that for products with matched tar deliveries the test cigarette delivers marginally increased nicotine in all puffs, but does not change the overall puff-by-puff profile of nicotine delivery.

It is pointed out that the profile could be flattened, that is the rate of nicotine delivery over the whole cigarette could be adjusted to remain constant, by modifying the pattern of printing.

Claims (18)

1. A smoking rod wrapper carrying dried deposits of an alkaloid or salt thereof and of a water soluble alkali.

2. A smoking rod wrapper according to claim 1 in which the alkaloid is nicotine.

3. A smoking rod wrapper according to claim 1 carrying dried deposits of an alkaloid salt selected from salts of organic acids, preferably polybasic acids and polymeric acids, more preferably citric acid, tartaric acid, alginic acid, pectic acid and other polysaccharide acids, optionally modified to increase the acid content.

4. A smoking rod wrapper according to any preceding claim in which the alkali is a stronger base than the alkaloid, preferably selected from hydroxides of alkali metals and alkaline earth metals and carbonates, hydrogen carbonates, phosphates and hydrogen phosphates or alkali metals, most preferably potassium carbonate.

5. A smoking rod wrapper according to any preceding claim in which the alkaloid is present as a salt and the alkali is present in at least a stoichiometric amount with respect to the acid from which the salt is formed.

6. A method of increasing the loading of alkaloid in the filler of a smoking rod which comprises forming a rod comprising a wrapper as claimed in any preceding claim and causing the alkaloid to transfer from the wrapper to the filler by exposure of the wrapper to moisture.

7. A method according to claim 6 in which the moisture is derived entirely from the filler forming the smoking rod.

8. A method according to claim 6 or claim 7 in which at least 90% of the added alkaloid is transferred to the filler after 5 days from the first exposure to moisture.

9. A method of producing a wrapper according to any one of claims 1 to 5 in which the alkaloid or salt is deposited from a composition comprising a substantially non-aqueous liquid vehicle in which the alkaloid or salt is insoluble.

10. A method according to claim 9 in which the composition comprises particles of the alkaloid or salt which are substantially all greater than 5 microns in diameter, preferably substantially all having diameters less than 100 microns, most preferably at least 90% of the particles having sizes in the range 10 to 50 microns.

11. A method according to claim 9 or claim 10 in which the composition comprises a binder, preferably a hydroscopic binder, most preferably selected from hydroxypropylcellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium alginate and sodium pectinate.

12. A method for producing a wrapper according to any of claims 1 to 5 in which the alkali is added from a composition comprising a substantially non-aqueous liquid vehicle in which the alkali is insoluble.

13. A method according to any of claims 9 to 11 in which the composition also contains alkali and the liquid vehicle is a non-solvent for the alkali.

14. A method according to any of claims 9 to 13 in which the liquid vehicle comprises ethanol.

15. A method according to any of claims 9 to 14 in which the composition is printed onto the wrapper.

16. An ink composition comprising particulate alkaloid or salts thereof, particulate water-soluble alkali and a non-aqueous liquid vehicle that is a non-solvent for both the alkaloid or salt and the alkali.

17. An ink which is a composition as defined in any of claims 10, 11 and 13.

18. An ink according to claim 16 or claim 17 in which the alkaloid is as defined in claim 2, or the alkaloid is a salt as defined in claim 3, and/orthe alkali is as defined in claim 4 and/or is presently an amount as defined in claim 5.