Smoke modifying agents and smoking material rods comprising smoke-modifying agents

CROSS-REFERENCE TO PRIOR APPLICATIONS

This divisional application claims priority to U.S. patent application Ser. No. 09/762,738, filed on Feb. 12, 2001, now U.S. Pat. No. 6,475,288, which claims priority to PCT International Application Serial Number PCT/GB99/02602, filed on Aug. 6, 1999, which claims priority to United Kingdom Patent Application Serial Number GB9817605.0, filed on Aug. 14, 1998.

BACKGROUND OF THE INVENTION

The present invention relates to the manufacture of fibriform material comprising a smoke-modifying agent.

GB 2 070 409 discloses a filament comprising smoking-modifying agents. The filament may be formed of or obtained from a fibrous material, such as tobacco, paper, cotton or man-made textile fibres, which material readily carries or can be readily impregnated with smoke-modifying agents. A possible disadvantage of the invention the subject GB 2 070 409 is that the smoke-modifying agents, if volatile, as is menthol for instance, can readily migrate from the filament, resulting in losses of the agent(s). The migration of significant amounts of the smoke-modifying agents from the region of application is highly undesirable and thus for example methods of encapsulation of flavourants have been devised to prevent such migration. Considerable work has been undertaken in respect of the encapsulation of flavourants in beads or microcapsules. However, problems may exist in maintaining such beads or microcapsules in cigarette tobacco rods.

U.S. Pat. No. 5,144,966 discloses a flavourant-release additive in the form of a filament for incorporation in the combustible filler of cigarette products and a method of production of such a filament. The filament disclosed in U.S. Pat. No. 5,144,966 comprises a core matrix and a co-extensive sheath coating, wherein the core matrix comprises a mixture of flavourant compound and a polysaccharide binder, and the sheath coating comprises a non-porous calcium alginate film. Such filaments are produced by a process which comprises 1) extruding an aqueous mixture of flavourant compound and a polysaccharide binder through an inner nozzle to form a gelled core fibre, 2) simultaneously co-extruding an aqueous solution of water-soluble alginate salt through an outer nozzle, coaxial of the inner nozzle, to apply a co-extensive sheath coating on the core fibre, and 3) contacting the thus formed filament with an aqueous calcium compound solution to convert sodium alginate to insoluble calcium alginate in the filament sheath coating, thus to encapsulate the flavourant. This co-extrusion method for forming a type of encapsulated filament is cumbersome when producing large quantities of filaments, which of course would be required if such filaments were to be incorporated into cigarettes at commercial manufacturing speeds.

It is an object of the present invention to provide an improved and commercially practical process for the manufacture of a fibriform material comprising a smoke-modifying agent(s).

SUMMARY OF THE INVENTION

The present invention provides a process for the manufacture of a homogeneous fibriform element comprising a smoke-modifying agent, wherein a mixture comprising a solution of a polysaccharide and a smoke-modifying agent is fed through nozzle means, and a jet of said mixture issuing from said nozzle means is brought into contact with a solution containing multivalent cations thus to effect solidification of said mixture.

The element manufactured by the inventive process is homogeneous in the sense that the polysaccharide and the smoke-modifying agent form together a matrix of constant constitution throughout the element and the term “homogeneous” is to be interpreted accordingly.

As will be appreciated by those skilled in the art, the process of solidification, i.e. the production of the aforesaid matrix, proceeds by way of a chemical reaction between cations of the solution containing multivalent cations and cations of the polysaccharide.

The non-solid mixture may take the form of, for example, a solution, a dispersion or an emulsion.

Advantageously, the mixture is heated to provide an elevated temperature of the mixture of, for example, 45° C. and is fed at an elevated temperature through the nozzle means. Suitably, whilst at an elevated temperature, the mixture is stirred continuously.

Preferably, the jet of the mixture issuing from the nozzle means is fed into a body of the solution containing multivalent cations. More preferably the jet of the mixture issuing from the nozzle means is fed into a stream of the solution. In the latter case, the stream of the solution containing multivalent cations suitably flows in a direction substantially parallel to the direction in which the mixture is fed through and issues from the nozzle means. Advantageously, the stream of the solution containing multivalent cations flows within conduit means. When conduit means are present the nozzle means and conduit means may suitably form an integral unit. Suitably, the mixture issuing from the nozzle means is carried by the solution containing multivalent cations through a portion, at least, of the conduit means. The length of the conduit means through which the mixture is carried is preferably of a length such that solidification of the mixture is complete or substantially complete upon issuance of the mixture from said conduit means at the downstream end thereof. As a person skilled in the art will readily appreciate, the flow rate of the mixture issuing from the nozzle means will affect the residency time of the mixture within the conduit means. It is conceivable too that this residency time may be affected by the flow rate of the cation containing solution.

Alternatively, the solution containing multivalent cations may be sprayed onto the jet of the mixture issuing from the nozzle means.

Suitably, the mixture is forced to and through the nozzle means under the action of a positive displacement pump, for example a progressing cavity pump as manufactured by Robbins and Myers under Model No. B4015. Alternatively, the mixture may be forced to and through the nozzle means under the action of pressurised air. Much by preference the mixture should exit the nozzle means at a substantially constant flow rate. The mixture may be continuously agitated in storage means before being fed to the nozzle means

According to a second aspect thereof, the present invention provides a process for the manufacture of a fibriform element comprising a smoke-modifying agent, wherein a thread is passed through a mixture comprising a solution of a polysaccharide and a smoke-modifying agent whereby said thread is coated with said mixture, the coated thread being brought into contact with a solution containing multivalent cations thus to effect solidification of said mixture on said thread.

Advantageously, the thread is comprised of a fibrous material, for example, tobacco, paper, cotton or a man-made textile.

As will be readily apparent to those skilled in the art, a fibriform element the product of a process according to the second aspect of the present invention is of homogeneous constitution in the sense of the above definition of “homogeneous”, excepting, of course, for the presence in the element of the thread.

In carrying out the process according to either of the above defined aspects of the present invention, as an alternative or in addition to bringing the mixture comprising a solution of a polysaccharide and a smoke-modifying agent into contact with a solution containing multivalent cations, the mixture can be brought into contact with an acidic solution, acetic acid for instance, thus to effect solidification of said mixture.

Suitably, the so-formed solidified fibriform element (formed according to either aspect of the invention) is wound onto a rotating drum. Preferably, the drum, at least at the peripheral region thereof, is comprised of plastics material. Preferably, the fibriform element is wound onto the drum, at least initially, in a single layer. A traverse unit may be used to pitch the fibriform element across the drum as the element is wound onto the drum. If it is deemed necessary, the drum, or a lowermost portion thereof, may be positioned in a bath containing the cation solution, so that as the drum, with the element wound thereupon, rotates, a lowermost portion of each turn of the element is immersed in the cation solution.

Following solidification of the fibriform element, the element may be washed, in for example water.

If there is a requirement to dry the so-formed fibriform element, various methods are available to persons skilled in the art for drying the element. For example, the element wound on the drum may be placed, along with the drum, in an oven at a pre-set temperature for a pre-determined period of time or alternatively air drying means may be used to dry the element on the drum. As another alternative, the element, before being wound onto the drum, may be passed through an annular air knife or a drying tunnel, or multiple combinations thereof. As a person skilled in the art would readily appreciate, combinations of these various methods may also be used.

Conveniently, the fibriform element in a dry, non-adhesive condition, is removed from the above mentioned drum and wound onto a lesser diameter spool for storage, the spool being of an appropriate diameter such that excessive bending of the element is avoided. Alternatively, the element can be cut into lengths, of about 30 cm for example, and stored for subsequent use. According to another alternative, the solidified fibriform element may be stored on the rotatable drum.

Elements manufactured by use of the present invention are preferably not breakable merely by being bent or drawn on longitudinally. Thus, if deemed necessary, plasticisers, glycerol and/or propylene glycol for instance, can be added to the initial mixture in order to increase the flexibility and/or tensile strength of the elements.

The initial mixture may further comprise an emulsifier if such an emulsifier is considered to be a requirement. The emulsifier may be, for example, a modified polysaccharide such as modified starch.

The homogeneous element is such that at least one smoke-modifying agent is encapsulated, in the sense of being held in the element against escape therefrom by, for example, volatilisation at ambient temperatures.

The polysaccharide solution is preferably an aqueous solution. The polysaccharide may suitably be an acid polysaccharide in the form of an alkali metal salt, for example an alginate, particularly sodium alginate. Other suitable polysaccharides which may be contemplated include pectins, gellan gum, carrageenan, agar, gum arabic, xanthan gum and guar gum.

The solution containing multivalent cations may be for example, an aqueous or alcoholic solution. The multivalent cations are ions of the group consisting of calcium, strontium, barium, iron, silver, aluminium, manganese, vanadium, copper and zinc, particularly calcium ions. For instance, a suitable aqueous solution containing multivalent cations is aqueous calcium chloride.

The present invention further provides a fibriform element as manufactured by a process in accordance with the present of invention.

Much by preference, the fibriform element is of a constant cross-sectional shape and size along the length thereof. Suitably, the element is of circular cross-section, in which case the diameter thereof will generally not be more than about 3 mm, preferably not exceeding about 1 mm.

The present invention further provides a smoking article comprising a smoking material rod, within which rod there extends, generally longitudinally of the rod, a fibriform element as manufactured by a process in accordance with the present invention.

Preferably, the fibriform element extends co-extensively of the smoking material rod. More than one fibriform element may extend, within the smoking rod, generally longitudinally thereof, in which case, preferably each of the elements extends within an axial zone of the rod. Advantageously, if a single only element extends within the smoking material rod, the element extends at least substantially coaxially of the rod. An advantage existing as a consequence of the element(s) extending within an axial zone of the smoking material rod is that when a smoking article comprising the smoking material rod is smoked, losses of smoke-modifying agent to sidestream smoke are minimised and thus the transfer efficiency of the smoke-modifying agent to the mainstream smoke is improved.

Suitable smoke-modifying agents may comprise, for example, tobacco dust or flavourant(s), menthol and/or furaneol, for example. In the former case, the tobacco dust may be impregnated with a flavourant.

In order that the present invention may be clearly understood and readily carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

shows apparatus for the manufacture of a fibriform element;

FIG. 2

shows an enlarged longitudinal section of an integral nozzle and conduit unit of the apparatus shown in

FIG. 1

;

FIG. 3

shows apparatus alternative to that of

FIGS. 1 and 2

;

FIG. 4

shows further apparatus, which further apparatus is operable for the continuous manufacture of a fibriform element;

FIG. 5

shows yet further apparatus operable for the continuous manufacture of a plurality of fibriform elements; and

FIG. 6

shows a smoking article, viz. a cigarette, incorporating a fibriform element.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference numbers in respect of common features have been maintained constant in all of the Figures. In

FIG. 1

, apparatus for the manufacture of a fibriform element

2

is generally depicted by reference numeral

1

. A vessel

3

comprises a surrounding heating jacket

4

and stirring means

5

. The vessel

3

is inter-connected by means of a delivery tube

6

to a nozzle and conduit unit

7

, which unit

7

comprises a nozzle

8

and a conduit means

9

, comprising an upstream portion

9

′, as an integral unit. The upstream portion

9

′ of the conduit means

9

extends about the conically shaped nozzle

8

. As is shown in

FIG. 2

, the conduit means

9

extends downstream from the vicinity of the nozzle

8

. Valve means

10

, a pump

11

and a flowmeter

12

are situated in the delivery tube

6

. Idler rollers

13

,

14

and

15

mounted on a traverse unit (not shown) are positioned at an outlet location of the conduit means

9

. The apparatus

1

further comprises a rotatable drum

16

, the direction of rotation of which is indicated by an arrow. A fluid bath

17

is situated beneath the drum

16

and also beneath the outlet location of the conduit means

9

. The fluid bath

17

is connected via a delivery tube

18

to the nozzle means

8

of the nozzle and conduit unit

7

. Sieving means

19

, a pump

20

, valve means

21

and a flowmeter

22

are situated in the delivery tube

18

.

In use of the apparatus

1

an emulsion

23

, of an aqueous sodium alginate solution and a menthol and propylene glycol solution (80% menthol:20% propylene glycol), the ratio of menthol to alginate in the emulsion being 1:1, is maintained at an elevated temperature of about 45° C. in the vessel

3

by means of the heating jacket

4

.

The emulsion

23

in the vessel

3

is continuously agitated by the stirring means

5

, which stirring means

5

takes the form of a rotary impeller. The emulsion

23

is transferred to the nozzle and conduit unit

7

, via the delivery tube

6

, under the action of the pump

11

. The pump

11

is a progressing cavity pump manufactured by Robbins and Myers under Model No. B4015. The flow rate of the emulsion

23

through the delivery tube

6

is indicated by the flowmeter

12

and adjusted by alteration of the rotary speed of the pump

11

. The emulsion

23

is supplied to the nozzle and conduit unit

7

in a continuous manner. As can be appreciated from

FIG. 2

, in the course of its passage from the tube

6

to and through the nozzle and conduit unit

7

, the emulsion

23

passes through the centrally arranged nozzle

8

. Thus a jet

2

′ of the emulsion

23

continuously issues from the exit orifice of the nozzle

8

. The jet

2

′ of emulsion

23

issuing from the nozzle

8

is brought into contact with an aqueous solution of calcium chloride

24

(4-6% by weight). The aqueous solution is delivered via the tube

18

and then flows through the conduit means

9

and around and thus into contact with the jet

2

′. The flow of the aqueous solution

24

aids the propulsion of the jet

2

′ through the conduit means

9

.

The residency time of the emulsion

23

and the surrounding calcium chloride solution

24

in the conduit means

9

is such that the emulsion

23

has undergone a large measure of solidification such that upon exiting the conduit means

9

as fibriform element

2

such that the element

2

is self-sustaining.

A suitable residency time of the emulsion

23

and the surrounding calcium chloride solution

24

in the conduit means

9

may be 2.4 seconds when the following parameters are met: the nozzle

8

is of an exit orifice diameter of 2 mm, the conduit

9

is of a bore diameter of 4 mm, the drum

16

rotates at a surface speed of 37 m/minute, the emulsion

23

flow rate is about 94 ml/minute, the flow rate of the aqueous solution

24

is about 280 ml/minute and the length of the conduit is 1.5 m.

Upon exiting the conduit means

9

the fibriform element

2

is fed about the idler rollers

13

,

14

,

15

, which idler rollers

13

,

14

,

15

, as above mentioned, are mounted on a traverse unit (not shown) and function to maintain the fibriform element

2

at a suitable tension and to position the fibriform element

2

on the rotating drum

16

. That is to say the idler rollers

13

,

14

,

15

and the traverse unit pitch the fibriform element

2

across the rotating drum

16

as the element

2

is wound onto the drum

16

. The drum

16

is preferably a smooth, plastic drum with a diameter of about 700 cm, at least. The fluid bath

17

is positioned such that a lower portion of the rotating drum

16

is immersed in the aqueous solution of calcium chloride

24

in the fluid bath

17

.

The aqueous solution

24

is supplied to the nozzle and conduit unit

7

from the fluid bath

17

via delivery tube

18

under the action of the pump

20

. The aqueous solution

24

passes through valve means

21

, the sieving means

19

and the flowmeter

22

. Aqueous solution

24

exiting conduit

9

is returned, by gravity, to fluid bath

17

.

When the total length of the fibriform element

2

wound onto the drum

16

reaches the maximum capacity of the drum

16

, pumps

11

and

20

are stopped, whereby the fibriform element production process is suspended. Rotation of the drum

16

is maintained until the end point of the solidification process of the element

2

has been reached. The calcium chloride solution

24

in the bath

17

is then exchanged for water, thus to wash the element

2

as the drum

16

rotates. The drum

16

with the element

2

wound thereon may then be transferred to an oven set to provide a temperature of about 40-50° C. in order to dry the element

2

.

Subsequently, the fibriform element

2

may be transferred to a storage spool (not shown). The transfer of the element

2

from the drum

16

to a smaller storage spool is conducted by rotating the drum

16

at a fixed speed as a jockey arm controls the speed of the slave storage spool. A traverse arm pitches the thread on the storage spool.

Storage spools, each with a fibriform element

2

wound thereon, are mounted directly on feed means operable to continuously feed the element to an upper location of the chimney of a conventional cigarette making machine for the manufacture thereof of a smoking article comprising a fibriform element (see FIG.

6

).

FIG. 3

depicts a further apparatus for the manufacture of a fibriform element

2

. The apparatus resembles that depicted in

FIG. 1

, excepting that the fibriform element

2

exiting the conduit

9

is fed into a drum

30

rather than onto a rotative drum

16

. The drum

30

comprises a solid central cylindrical core

31

thus to form a hollow annulus

32

between the peripheral wall of the drum

30

and the peripheral wall of the core

31

. The annulus

32

is closed at the lower end thereof by a wall

30

′, but is open at the upper end thereof. The annulus

32

contains an aqueous solution of calcium chloride

24

.

The conduit

9

comprising a hinge mechanism (depicted as A in

FIG. 3

) is rotated by rotation means

33

, such that the exit orifice of the conduit

9

is rotated around the annulus

32

and the fibriform element

2

exiting the conduit

9

is wound into the annulus

32

such as to be immersed in the solution therein.

A pump

20

and associated equipment, as that described in respect of the fluid bath

17

in

FIG. 1

, is present to deliver aqueous solution

24

from the annulus

32

to the nozzle and conduit unit

7

. As mentioned above in respect of the

FIG. 1

apparatus, the element

2

is washed by replacing the calcium chloride solution

24

with water. The element

2

can then be dried and either fed directly to a cigarette making machine (not shown) or onto a storage spool (not shown).

FIGS. 4 and 5

depict generally first and second apparatus for the continuous manufacture respectively of a single fibriform element

2

and a plurality of fibriform elements

2

, in which manufacture the emulsion

23

and the solution

24

are brought into contact by means of spraying the solution

24

onto a jet of the emulsion

23

. In use of these apparatus a continuously heated and stirred aqueous emulsion

23

, of the same constitution as that hereinabove detailed in respect of the operation of the

FIG. 1

apparatus, is transferred from heated vessel

3

via a delivery tube

33

to either a single nozzle head

8

(as depicted in

FIG. 4

) or to a multiple nozzle head

34

(as depicted in FIG.

5

). Pressurised air is used for this transfer, the pressurised air being supplied from an air source

35

via an air line

36

. A pressure gauge

37

is positioned in the air line

36

. The aqueous emulsion

23

is maintained at a temperature of about 45° C. As shown in

FIG. 4

, the jet/fibriform element

2

is directed to and downwardly through a vertical cylinder

38

. A spray of an aqueous solution of calcium chloride

24

(4-6% by weight) is produced by means of a spray means

39

and is directed onto the jet/fibriform element

2

during the passage thereof through the cylinder

38

. The calcium chloride solution

24

is supplied from a reservoir thereof via a delivery tube

40

using pressurised air supplied from an air source

41

via an air line

42

. A pressure gauge

43

is present in the air line

42

. Droplets of excess calcium chloride solution

24

are removed via an exhaust duct

44

by use of suction, which suction is provided by fan means (not shown) Alternatively, as shown in

FIG. 5

, multiple jets/elements

2

travel down from the nozzle head

34

onto a rotating drum

45

, the speed of rotation of the drum

45

being linked to the flow rate of emulsion

23

to the nozzle head

34

.

Calcium chloride solution

24

is sprayed by means of spray means

39

onto the jets/elements

2

supported on the rotating drum

45

. The calcium chloride solution

24

is supplied from a reservoir thereof via a delivery tube

40

, using pressurised air supplied from an air source

41

via an air line

42

. A pressure gauge

43

is present in the air line

42

. Droplets of excess calcium chloride solution

24

on the drum

45

are collected in a tray (not shown positioned beneath the drum, and suction means (also not shown) is employed to remove excess droplets of the solution which are airborne.

The process as depicted in

FIGS. 4 and 5

, subsequent to the application of the calcium chloride solution

24

, is substantially identical for either a single fibriform element

2

or a plurality of fibriform elements

2

. That is to say, the element(s)

2

is dried using an air knife

46

,

47

and/or a drying tunnel

48

. Both the air knife

46

,

47

and the drying tunnel

48

are arranged such that in operation heated air is passed about the fibriform element(s)

2

. The resulting dried element(s)

2

is wound onto a spool(s)

49

. When, as in

FIG. 5

, a plurality of elements

2

is manufactured, each is wound singularly on a spool

49

. As a person skilled in the art would be aware, the direction of travel of the fibriform element(s)

2

during the manufacture thereof may be altered at any point in the process in order to relieve the fibriform element(s)

2

of excessive gravitational tensile forces and thus prevent breakage of the element(s)

2

.

The process, as depicted in

FIG. 5

, allows for a plurality of fibriform elements

2

to be manufactured using minimal machinery.

In

FIG. 6

, reference numeral

50

designates generally a cigarette comprising a rod of tobacco

51

and a cigarette filter

52

, the cigarette

50

further comprising a fibriform element

2

extending longitudinally and substantially coaxially of the tobacco rod

51

. The fibriform element

2

comprises menthol encapsulated in an alginate matrix.

An advantage of using a fibriform element(s) comprising encapsulated menthol is that thereby an even distribution of menthol along the tobacco rod is readily attained; whereas the even distribution of capsules of encapsulated menthol along the rod can be difficult to achieve.