EP0531075A1

EP0531075A1 - Packaging smoking materials

Info

Publication number: EP0531075A1
Application number: EP92307891A
Authority: EP
Inventors: Christopher George Drewett; John Kenneth Waldron; Brian Chester Chard; Stephen William Purkis; Colin Arthur Hill
Original assignee: Imperial Tobacco Company of Great Britain and Ireland Ltd; Imperial Tobacco Ltd Great Britain
Current assignee: Imperial Tobacco Company of Great Britain and Ireland Ltd; Imperial Tobacco Group Ltd
Priority date: 1991-08-31
Filing date: 1992-08-28
Publication date: 1993-03-10
Also published as: CA2077090A1

Abstract

There is provided a pouch 10 containing tobacco 11 and a moisturising element 13 containing a measured quantity of water in a fibrous pad. This element is sealed from the tobacco 11 by a vapour permeable liquid barrier 14 comprising a vapour permeable outer layer 15 and an inner, degradable liquid barrier 16. After a predetermined period of time the barrier 16 starts to degrade or dissolve thus allowing the moisture in the element 13 to pass into the tobacco 11 as a vapour through the vapour permeable layer 15.

Description

This invention relates to packaging arrangements for smoking materials, particularly tobacco for pipe and hand-rolling consumption but also has application in other packaged tobacco products such as cigars.
Such tobacco is usually sold in generally air-tight, fixed weight packages and normally includes a number of volatile components such as water, flavouring materials and some preservatives. The water provides beneficial tactile properties which assists the consumer in end use, for example the hand-rolling of cigarettes, and influences smoking quality.
Currently, hand-rolling tobacco is packaged and sold at high moisture content compared to the tobacco in manufactured cigarettes in order to satisfy the consumer's requirements. This moisture content is generally greater than about 18% which results in a distinct disadvantage for the tobacco producer because, at such high values, tobacco becomes susceptible to mould cultures and requires precautions during manufacture. These precautions include the use of preservatives to inhibit mould growth and strict rotation of tobacco stock. The shelf life of the product may nevertheless be reduced.
Susceptibility to mould growth decreases rapidly below 18% moisture content.
The prior art discloses humidification and humidistat devices for inclusion in the package or as an integral part of the packaging associated with tobacco and food products, for example, US 1 871 419 discloses a humidifying sheet using a hydrated salt, a fibrous substrate and a vapour permeable membrane. US 2 452 957 discloses a vapour permeable membrane of regenerated cellulose film enclosing an efflorescent salt and GB 1 369 992 discloses a humidistat comprising a pad containing a buffer solution enclosed in an envelope of vapour permeable thermo-plastic material. US 3 801 011 discloses water containing microcapsules with vapour-transmitting walls.
More recently US 4 997 082 and US 5 037 459 have disclosed improvements to humidistat systems but, as far as is known to the applicants, the prior art has not recognised the benefits of a delayed action, self actuating humidistat or humidification system which is used to add water and, if desired, other volatile materials to tobacco or tobacco products after packing.
According to the present invention there is provided an arrangement comprising a generally air tight package and a smoking material/product contained therein, said arrangement incorporating self-actuating moisturising means adapted to release moisturising fluid thereby to increase the moisture content of the smoking material/product after a substantially predetermined period of time subsequent to packing.
Preferably the moisturising means comprises a liquid impermeable reactive membrane which encloses a pad containing the fluid contents of the moisturising means. In some arrangements the membrane decomposes or dissolves over said predetermined period thereby to become permeable and to release the moisturising fluid to the package.
Ideally there is also provided a vapour permeable, liquid barrier which permits transfer of moisturising fluid in the vapour phase only to the package contents. This is because it is desirable to prevent localised concentrations of liquid phase reaching or "wicking" into the tobacco or packaging material.
In some chosen arrangements the liquid barrier and the reactive membrane are formed as a coated film or laminate with the impermeable reactive membrane in contact with the moisturising fluid and with the liquid barrier in contact with the package contents. A further feature is that the moisturising means comprises a plurality of moisturising elements and each element is adapted to release moisture after different periods of time. This allows reconditioning of the tobacco over an extended period of time. Preferably said moisturising fluid comprises water and said fluid also comprises other volatile materials including flavourants and/or preservatives and/or additives.
In other arrangements the moisturising fluid comprises a saturated salt solution. In one embodiment the salt solution is of sodium chloride adapted to achieve an equilibrium relative humidity of a predetermined value in the packaged environment. Preferably the relative humidity is about 75%, this relative humidity being compatible with the tobacco moisture that is preferred by the consumer for handrolling use. In further embodiments the self actuating moisturising means comprises hygroscopic material separated from the smoking material/product by a vapour permeable liquid barrier the hygroscopic material in turn being separated from a moisture source by a further vapour permeable liquid barrier. Conveniently the hygroscopic material is a polyol such as glycerol.
Embodiments of the invention will now be described in more detail by reference to the accompanying diagrammatic drawings in which:

Figure 1 shows a partially cut-away perspective view of a tobacco pouch according to the present invention,
Figure 2 shows a cross-section through the tobacco pouch shown in figure 1,
Figure 3 shows an exploded perspective of an alternative arrangement for the containment of moisturising liquid,
Figure 4 shows a sectional view through a further arrangement according to the present invention, and
Figure 5 shows a sectional view through a still further arrangement.

Referring to figures 1 and 2, there is shown a tobacco pouch 10 containing tobacco 11. The pouch 10 has a conventional closure flap 12 and incorporates a moisturising element 13 comprising a fibrous absorbent pad containing a measured quantity of water. There is the possibility of also including other volatile additives/flavours and buffering compounds (eg glycerol) according to particular requirements. The moisturising element 13 is located adjacent to and sealed against an inner surface of the pouch 10 by means of a vapour permeable liquid barrier 14 which lies adjacent to the tobacco 11. The liquid barrier 14 comprises a laminated or coated film material which has an outer, vapour permeable surface 15 in contact with the tobacco which surface 15 is a permanent liquid barrier and an inner, degradable liquid barrier 16 in contact with the moisturising pad, which barrier 16 after a time becomes liquid permeable. The vapour permeable surface 15 is for example a regenerated cellulose film which may be coated or partially coated with the liquid barrier 16 as a lacquer or laminate. The material of the barrier 16 is chosen to react with the liquid contents of the element 13 such that its liquid barrier properties diminish during storage whereby after a predetermined period the barrier 16 becomes liquid permeable. The moisturising liquid is then released as a vapour through the vapour permeable surface 15 to the contents 11 of the pouch.
In the figure 3 arrangement there is a fibrous pad 17 and a single or multiplicity of liquid containers 18 such as sachets constructed of a degradable liquid impermeable film. There is a vapour permeable liquid barrier 19 enclosing these components and sealing them from the tobacco material 11. It will be appreciated that the containers 18 could even be designed so as to degrade at different times or to contain different volatiles for release at different times.
In an alternative embodiment shown in figure 4 the pad 13 containing a measured quantity of chosen fluids is sealingly enclosed adjacent the pouch 10 by a laminated membrane 20 having inner and outer layers 21, 22 of vapour permeable material such as cellulose film which layers 21, 22 are laminated with a layer in between. These layers 21, 22 may also include agents for modifying the permeability to water vapour, e.g. a nitrocellulose coating. The middle layer essentially comprisesa polyol e.g. glycerol, such that at low moisture content it is hygroscopic yet at higher moisture content the vapour pressure of water above the polyol/water system is sufficient to enable a high rate of transfer of moisture to the tobacco article. This inner matrix acts initially as an absorber of water from the pad 13 and after an interval, dependent upon the composition, acts as an emitter of water. The overall driving force being the reservoir of water, the uptake by the tobacco article being quasi-exponential. It will, of course, be apparent that the timing of the release of moisture to the tobacco can be varied by careful choice of the absorbent hygroscopic layer and the permeability of the layers 21, 22.
The amount of water contained by the device must be chosen to suit the end product application such that the desired moisture content of the tobacco can be achieved. By way of example, hand-rolling tobaccos tend to achieve the desired moisture content at about 75% Relative Humidity leading to a moisture content of about 25-30% in the tobacco. 3g of water is required to raise 25g of hand rolling tobacco from 18% moisture to 27%.
Another example of a suitable construction is a sandwich comprising two outer cellulose films enclosing a fibrous cellulose pad containing glycerol.
In figure 5 there is shown an arrangement very similar to that shown in figure 4. The difference is that the barrier layer is not formed as a laminated structure with the cellulose layers 21, 22. In figure 5 the polyol is held in a fibrous cellulose pad 25 which is retained between the two layers 21, 22. The operation is, however, the same as that of the figure 4 arrangement.
The above refers to packaging and moisture addition to tobacco but it will be appreciated that other tobacco products and smoking materials including substitutes cigars and cigarettes could be used.
The tobacco can thus be packed at a lower moisture than is desired for use so that mould growth is reduced between packaging and consumption. The resistance to mould and control over moisturising provides increased shelf-life.

Claims

1) An arrangement comprising a generally air tight package and a smoking material/product contained therein, said arrangement incorporating a self-actuating moisturising means adapted to release moisturising fluid thereby to increase the moisture content of the smoking material/product after a substantially predetermined period of time subsequent to packing.

2) An arrangement as claimed in claim 1 wherein the moisturising means comprises a liquid impermeable reactive membrane which encloses a pad containing the fluid contents of the moisturising means.

3) An arrangement as claimed in claim 2 wherein the membrane decomposes or dissolves over said predetermined period thereby to become permeable and to release the moisturising fluid to the package.

4) An arrangement as claimed in claim 3 wherein there is also provided a vapour permeable, liquid barrier which permits transfer of moisturising fluid in the vapour phase only to the package contents.

5) An arrangement as claimed in claim 4 wherein the liquid barrier and the reactive membrane are formed as a coated film or laminate with the impermeable reactive membrane in contact with the moisturising fluid and with the liquid barrier in contact with the package contents.

6) An arrangement as claimed in any one of claims 1 to 5 wherein the moisturising means comprises a plurality of moisturising elements.

7) An arrangement as claimed in claim 6 wherein each element is adapted to release moisture after different periods of time.

8) An arrangement as claimed in any one of claims 1 to 7 wherein said moisturising fluid comprises water.

9) An arrangement as claimed in claim 7 or claim 8 wherein said fluid also comprises other volatile materials including flavourants and/or preservatives and/or additives.

10) An arrangement as claimed in any one of claims 1 to 7 wherein the moisturising fluid comprises a saturated salt solution.

11) An arrangement as claimed in claim 10 wherein the salt solution is of sodium chloride adapted to achieve an equilibrium relative humidity of a predetermined value in the packaged environment.

12) An arrangement as claimed in claim 11 wherein the relative humidity is about 75%.

13) An arrangement as claimed in claim 1 wherein the self actuating means comprises hygroscopic material separated from the smoking material/product by a vapour permeable liquid barrier, the hygroscopic material in turn being separated from the moisture source by a further vapour permeable liquid barrier.

14) An arrangement as claimed in claim 13 wherein the hygroscopic material is a polyol such as glycerol.

15) An arrangement as claimed in any one of claims 1 to 14 wherein the smoking material/product comprises tobacco or cigars or cigarettes.