GB2193075A

GB2193075A - Improvements relating to the making of filter rod

Info

Publication number: GB2193075A
Application number: GB08717242A
Authority: GB
Inventors: James William Percy Phelpstead
Original assignee: British American Tobacco Co Ltd
Current assignee: British American Tobacco Investments Ltd
Priority date: 1986-07-22
Filing date: 1987-07-21
Publication date: 1988-02-03
Also published as: GB8617865D0; GB8717242D0

Abstract

In a method and apparatus for making filter rod of an acceptable degree of hardness which comprises less fibrous filter tow per unit length than a rod of equivalent hardness made conventionally, filter tow treated with fast setting hardener is supplied to a first garniture unit where it is brought to a first cross- sectional size and the resultant self sustaining rod is fed to a second garniture unit in which the rod is reduced permanently to a second cross-sectional size. <IMAGE>

Description

SPECIFICATION Improvements relating to the making of filter rod The subject invention relates to the making of filter rod.

The most widely established method of manufacture of filter rod for use in the making of filter tipped cigarettes comprises the continuous feeding of plasticiser treated cellulose acetate tow and a web of wrapper paper to a garniture unit of a rod making machine. A driven endless band extends through the garniture unit and serves to convey the tow and wrapper paper through the garniture unit, wherein the wrapper paper is wrapped about the tow and lap seamed. Downstream of the garniture unit the resultant continuous rod is cut into lengths a multiple of a unit filter element. The filter rod lengths are stored for a period of time sufficient for the plasticiser to have completely cured and for the rods to have thereby assumed the desired degree of hardness.

Determinants of filter rod hardness are the amount and type of plasticiser or other hardener used and the amount of fibrous tow present in unit length of the rod.

It is an object of the present invention to provide a method of making filter rod which method yields rod of an acceptable degree of hardness but which rod comprises less fibrous filter tow per unit length of the rod than does rod of equivalent hardness made in accordance with methods used heretofore.

The present invention provides a method of making filter rod, wherein filter tow of continuous, longitudinal filaments is treated with a hardener and fed continuously to a first garniture unit, the tow is brought, within a continuous, driven garniture band extending through said first garniture unit, to a first cross-sectional size, and the resultant self-sustaining rod from said first garniture unit is fed to a second garniture unit provided with a continuous, driven garniture band, wherein the rod is reduced permanently to a second cross-sectional size less than said first cross-sectional size.

The resultant self-sustaining rod from the first garniture unit is preferably fed together with a continuous web of wrapping material to the second garniture unit. The rod emanating from the second garniture unit at the second cross-sectional size is preferably wrapped in the wrapping material and the wrapping material is lap seamed. Suitably the continuous web of wrapping material is a plugwrap material.

The hardener with which the tow is treated before entry to the first garniture unit is suitably of a fast setting type.

f the tow is of cellulose acetate, a succinic ester such as disclosed in United Kingdom patent Specification No. 1 457 694 may be used. In order to increase the rate of setting of the hardener within the first garniture unit, the first garniture unit may incorporate heating means. Electrical or microwave heating means may be provided. Alternatively, the heating means may be operable to supply a hot fluid, air or steam for example, to the garniture passage for direct contact with the hardener treated tow. In the latter case it will, of course, be a requirement that the garniture band is pervious to the fluid.

The hardener must be substantially fully set within the first garniture means, the rod emerging therefrom thus comprising a selfsustaining, three dimensional structure of filaments bonded to each other at points of contact therebetween. The rod is also resilient, whereby, when the cross-sectional size thereof is reduced in the second garniture unit, there results an outwardly radial force, which force is contained by the lap seamed wrapping material. Thus for a given final rod hardness value it is possible in accordance with the present invention to feed to the first garniture unit a tow of less weight per unit length than would be the case for the widely established rod making method in which hardener treated tow is fed through only one garniture unit and is therein wrapped in wrapping material prior to hardening.

The present invention also provides filter rod making apparatus comprising a first garniture unit and a second garniture unit adapted to receive continuous rod from said first garniture unit, said second garniture unit being operable to reduce the cross-section of the rod received from said first garniture unit.

Preferably the first garniture unit comprises heating means operable to heat hardener treated tow during the passage thereof through the first garniture unit. When the first garniture unit comprises such heating means, there may also be provided cooling means operable to supply cooling fluid, air for example, to the rod downstream of the heating means.

Said apparatus may further preferably comprise feed means operable to feed a continuous web of filter rod wrapping material to the second garniture unit and to wrap and lap seam the material about the rod.

Suitably the first and second garniture units are disposed with the rod forming passages thereof in coaxial relationship. Rod support means is advantageously disposed between the first and second units.

As used herein, the term "hardener" not only includes a liquid agent sprayed or brushed onto the tow, but includes also a thermoplastic material co-extruded with the filaments of the tow. In the latter case the thermoplastic material is softened under the action of heating means of the first garniture means, whereby the filaments are bonded to each other at points of contact therebetween.

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 diagrammatic drawing hereof which shows in side elevation a filter rod making machine.

The filter rod making machine comprises a first garniture unit 1 and, to the outlet side of unit 1, a second garniture unit 2, the rod forming passages of the two units being coaxially aligned.

The garniture unit 1 is of generally conventional construction, although it is dimensioned to produce rod of a diameter larger than that required finally. An upper run of an endless garniture band 3 of appropriate width extends through -the garniture unit 1, the band 3 being trained about idler rollers 4-6 and about a drive roller 7 which is drivable in an anticlockwise direction by drive means (not shown). The garniture unit 1 comprises at the inlet end thereof a condenser- horn 8. The unit 1 further comprises an electric heater, which heater is designated by reference numeral 9.

It may be observed that no wrapper web feed means is associated with the garniture unit 1.

The garniture unit 2 is of conventional construction- and is dimensioned for the production of rod of the finally required diameter.

At its inlet end the unit 2 comprises a condenser horn 10. An upper run of an endless garniture band 11 extends through the garniture unit 2, the band 11 being trained about idler rollers 12-14 and about a drive roller 15 which is derivable in an anti-clockwise direction by drive means (not shown). As the unit 2 is dimensioned for the production of rod of a diameter less than that for which the unit 1 is dimensioned, the width of the garniture band 11 is less than that of the garniture band 3.

In conventional manner a-bobbin 16 of plugwrap is mountable at a location beneath the inlet end of the- garniture unit 2, whereby a continuous web 17 of the plugwrap may be fed to the horn 10.

Reference numeral 18 designates an adhesive applicator which is operable to apply a film of lap seam adhesive at a margin of the web 17 of plugwrap.

Disposed intermediate the first and second garniture units 1, 2 is a rod support bed 19.

In operation of the filter rod-making machine, filter tow, designated 20, comprising continuous, crimped fibres, cellulose acetate fibres, for example, is fed by conventional tow feed means (not shown) to the garniture unit 1. Upstream of the unit 1 the tow 20 passing to the unit 5 is sprayed with a liquid form hardener, diethyl succinate for example, from a spray device 21. The tow 20 is conveyed through the garniture unit 1 by the band 3 and- is within the unit 1 brought to a rod form of a predetermined, first diameter. The heater 8 heats the hardener and produces substantial setting thereof in the dimensionally self-sustaining rod, designated 22, which emerges from the unit 1.

The rod 22 in its travel from the outlet of the garniture unit 1 to the inlet end of the garniture unit 2 is supported by the rod support bed 19.

The rod 22 and the web 17 of plugwrap are conveyed through garniture unit 2 by the endless band 11. Within the unit 2 the rod 22 is brought down to a predetermined, second diameter and is wrapped in the web 17 of plugwrap, the web 17 being lap seamed. The wrapped, continuous rod which emerges from the unit 2 is designated by reference numeral 23. The rod 23 is cut by a cutter blade 24 to provide lengths 25 a multiple of a unit filter element.

According to a further method of making filter rod, a filter rod making machine comprising two garniture units arranged similarly to those of the above described machine is used, although in the further method there is fed continuously to the first garniture unit, together with the hardener treated tow, a web of heat shrink wrapping material. In the first garniture unit the hardener is set, the setting process being conveniently promoted by means of microwave heating means operable to heat the interior of the wrapped rod without causing shrinkage of the heat shrink wrapping. The first garniture means is also provided with an adhesive applicator for the purpose of forming a lap seam in the wrapping material web, the adhesive used suitably being a solvent for the wrapping material.

There thus emerges from the first garniture a wrapped rod comprising a self-sustaining and resilient structure of bonded filaments. The second garniture unit comprises heating means operable to heat the wrapper such that the wrapper shrinks and thereby reduces the diameter of the rod. Suitably, the material of the wrapper is shrunk to the full extent of the thermal shrinkage of the material. No further wrapping material web needs to be fed to the second garniture unit.

Claims

1. A method of making filter rod, wherein filter tow of continuous, longitudinal filaments is treated with a hardener and fed continuously to a first garniture unit, the tow is brought, within a continuous, driven garniture band extending through said first garniture unit, to a first cross-sectional size, and the resultant self-sustaining rod from said first garniture unit is fed to a second garniture unit provided with a continuous, driven garniture band, wherein the rod is reduced permanently to a second cross-sectional size less than said first cross-sectional size.

2. A method according to Claim 1, wherein the self-sustaining rod from said first garniture unit is fed to said second garniture unit together with a continuous web of wrapping material.

3. A method according to Claim 2, wherein rod at said second cross-sectional size is wrapped in said wrapping material and said material is lap seamed.

4. A method according to Claim 1, wherein there is fed continuously to said first garniture unit, together with the hardener treated tow, a web of heat shrink material.

5. A method according to Claim 4, wherein said hardener is set without causing shrinkage of said heat shrink material.

6. A method according to Claim 5, wherein said second garniture unit comprises heating means operable to shrink said heat shrink material.

7. A method according to any one of the preceding claims, wherein said hardener is a fast setting one.

8. A method according to any one of the preceding claims, wherein said filter tow comprises cellulose acetate.

9. A method according to Claim 8, wherein said hardener is a succinic ester.

10. A method according to any one of the preceding claims, wherein said filter tow is heated at said first garniture means.

11. A filter rod making apparatus comprising a first garniture unit and a second garniture unit adapted to receive continuous rod from said first garniture unit, said second garniture unit being operable to reduce the crosssection of the rod received from said first garniture unit.

12. Apparatus according to Claim 11, wherein said first garniture unit comprises heating means operable to heat hardener treated tow during the passage thereof through said first garniture unit.

13. Apparatus according to Claim 12, wherein said heating means is electrical heating means.

14. Apparatus according to Claim 12, wherein said heating means is microwave heating means.

15. Apparatus according to Claim 12, wherein said heating means is operable to provide hot fluid to the garniture passage for direct contact with the hardener treated tow.

16. Apparatus according to any one of Claims 12 to 15, wherein downstream of said first garniture unit cooling means is provided.

17. Apparatus according to any one of Claims 12 to 16, wherein said first and second garniture units are disposed with the rod forming passages thereof in coaxial relationship.

18. Apparatus according to any one of Claims 11 to 17, wherein said apparatus further comprises feed means operable to feed a continuous web of filter rod wrapping material to said second garniture unit and to wrap and lap seam said material about said rod.

19. Filter rod produced according to the method of any one of Claims 1 to 10.

20. Filter rod produced according to Claim 19, wherein said rod comprises less fibrous filter tow per unit length of the rod than a conventional rod of equivalent hardness.

21. Filter rod making apparatus substantially as hereinabove described with reference to the drawing hereof.