GB2127273A - Making ventilated cigarette filters - Google Patents

Abstract

The invention concerns a smoking- article ventilated filter element, comprising a plug of fibrous filtration material wrapped in a wrapper of which at least a portion extending to an end of said element has been removed by the action of heat on moving said element and a heated means relatively to and in contact with each other. The removal of wrapper may expose filtration material underlying said wrapper or a further intermediate wrapper, if present. The first named wrapper may be of a material of a thermoplastic character or comprising a proportion of thermoplastic fibres. The ventilated filter may thus be provided with at least one groove extending parallel to the axis of the element or helically disposed and the tipping wrapper may be provided with a ring of spaced ventilation perforations disposed to communicate with said grooves at an upstream region thereof. The channel means may be extended from an annular groove. If there is a further intermediate wrapper, at least a portion thereof may have been removed by the action of heat. The further wrapper may be of substantially zero air permeability. Two said channel means may follow helical intersecting paths with intermediate portions of wrapper material bonded to underlying filtration material. <IMAGE>

Description

SPECIFICATION Improvements relating to smoking article filters This invention relates to ventilated filter-tipped cigarettes.

It is known to provide cigarettes with filters comprising smoke-filtration means, commonly in the form of a plug of fibrous filtration material, and ventilation-channel means extending to the mouth end of the filter, the outer wrapper enwrapping the filter being such as to permit ingress of air into the channel means. When a cigarette provided with such a filter is smoked, air wholly or substantially unmixed with tobacco smoke enters the smoker's mouth from the channel means together with tobacco smoke from the filtration means. It has been found that the segregation of air and smoke in this manner enhances the smoking characteristics of the cigarette.

A segregated ventilation filter is described in United Kingdom Patent Specification No.

2,090,117A. The filter there described comprises a filter plug enwrapped in a first plugwrap which is overlain by a second plugwrap. The second plugwrap is modified by cutting or crimping prior to its being wrapped about the first plugwrap. The form of the modification to the second plugwrap is such that when a tipping wrapper is enwrapped about the second plugwrap, ventilation-air channels, extending to and opening at the mouth end of the filter, are defined. Perforation holes are provided in the tipping wrapper to permit ventilation air to enter the channels.

The present invention provides a filter element comprising fibrous filtration material wrapped in a wrapper of which a portion or portions extending to an end of said element have been removed by moving said element and heated forming means relatively of each other and in contact with each other.

The present invention also provides a smoking article, a cigarettes for example, comprising a rod of smoking material, a filter element and a tipping wrapper serving to interattach said rod and said filter element, said filter element comprising fibrous filtration material wrapped in a wrapper of which at least a portion extending to the mouth end of said element has been removed by moving said element and heated forming means relatively of each other and in contact with each other, the removal of said portion or portions of said wrapper providing a ventilation-air distribution channel or channels bounded by said tipping wrapper and opening at said mouth end of said element, and said tipping wrapper permitting the ingress of ventilation air into said channel or channels upstream of said mouth end.

The removal of the portion or portions of the filter wrapper exposes either the underlying filtration material or a further wrapper intermediate the filtration material and the wrapper from which a said portion has been removed. The filter wrapper, or the outer wrapper when a further, intermediate wrapper is provided may be of conventional paper plugwrap material or it may be of a material of a thermoplastic character by having incorporated in it a proportion of thermoplastic fibres or by being a thermoplastic film material. Similarly, when an intermediate wrapper is provided, it may be of conventional paper plugwrap material or it may be of a material of a thermoplastic character. Suitable materials for thermoplastic fibres and thermoplastic film includes cellulose acetate, polyethylene, polypropylene and cellophane.

Conveniently, in order to effect removal of wrapper portions a filter rod, of a length a multiple of a unit filter element, and heated forming means are moved relatively of each other in an arcuate path, although a straight path of relative movementwould also be appropriate.

In order that the invention may be clearly understood and readily carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawing, in which Figure 1 shows parts of a filter tipped cigarette, a tipping wrapper and part of a tobacco rod thereof being shown in axial section, Figure 2 shows a filter element which could be substituted for the filter element of the cigarette of Figure 1, and Figure 3 shows a mouth-end view of the filter element of Figure 2.

The filter tipped cigarette of Filter 1 comprises a cigarette rod 1, of tobacco filler 2 wrapped in a cigarette paper wrapper 3, a filter element 10, of fibrous cellulose acetate filtration material wrapped in paper plugwrap 11, and a paper tipping wrapper 4 serving to interattach the cigarette rod 1 and the filter element 10.

Prior to being incorporated in the cigarette of Figure 1 the filter element 10 formed part of a filter rod of a length equivalent to for example, six unit elements. The rod was rolled in contact with a heated former (not shown) of such configuration as to effect removal, by the action of heat, or by burning, of a number of grooves 14 equiangularly spaced about the element 10. Each of the grooves 14 extends parallel to the axis of the element 10 from an upstream location of the element to the mouth end of the element.

The tipping wrapper 4 is provided with a ring of ventilation perforations 5, the ring being so located along the element 10 and the perforations 5 being of such a size and spacing that at least one of the perforations 5 communicates with each of the grooves 14 at an upstream end region thereof. The grooves 14, together with the tipping wrapper 4 and the cellulose acetate filtration material exposed within the area of each groove 14, and designated 7, define ventilation-air distribution channels 6. Thus during smoking of the cigarette, ventilation air may enter the channel 6 through the perforations 5 and flow to the smoker's mouth therealong.

A form of filter element 15 alternative to the element 10 of Figure 1 is shown in Figures 2 and 3.

The filter element 15 comprises a thermoplastic film wrapper 8, fibrous filtration material 19, and a further wrapper 9 intermediate the wrapper 8 and the filtration material 19. A six times unit length filter rod from which the element 15 was cut was rolled in contact with a heated former of such configuration as to remove portions from the wrapper 8 to provide an annular groove 16 and extending therefrom two series of grooves 17, 18 which follow helical paths of opposite hand and extend to and open at the mouth end of the element 15, i.e. the righthand end viewing Figure 2. The grooves 16-18 are not so deep as to extend through the wrapper 9.

When the filter element 15 is attached to a cigarette rod by tipping having ventilation perforations in communication with the annular groove 16, ventilation air can flow from the groove 16 into the grooves 17, 18 and therefrom into the smoker's mouth.

The wrapper 9 may be of conventional paper plugwrap material but is suitably of a paper containing thermoplastic fibres or is a thermoplastic film material. The wrapper 9 may be of low or substantially zero air permeability.

An apparatus of a type which could be utilised for heat removal of portions of plugwrap is described and shown in United Kingdom Patent Specification No. 1,507,765.

Although the formation of the grooves 17, 18 by the thermal removal of thermoplastic film plugwrap results in the production of small isolated triangular and diamond shaped portions of the remaining plugwrap, these portions are firmiy secured to the underlying body of filtration material because the margins of these portions become thermally bonded to the filtration material during the thermal formation of the grooves 17, 18.

Claims (12)

1. A smoking-article ventilated filter element, comprising a plug of fibrous filtration material wrapped in a wrapper of which a portion or portions extending to an end of said element has or have been removed by the action of heat on moving said element and a heated means relatively to and in contact with each other.

2. A filter element according to claim 1, wherein the said removal of wrapper exposes filtration material underlying said wrapper.

3. A filter element according to claim 1 or 2, wherein there is a further wrapper intermediate said filtration material and first-named wrapper, removal of said first-named wrapper leaving exposed said further wrapper.

4. A filter element according to claim 1, wherein the said wrapper is of a material of a thermoplastic character.

5. A filter element according to claim 1, wherein said wrapper comprises a proportion of thermoplastic fibres.

6. A smoking article comprising a rod of smoking-material, a filter-plug element and a tipping wrapper serving to interattach said rod and plug element, which element comprises fibrous filtration material wrapped in a wrapper of which at least a portion extending to the mouth end of said element has been removed by the action of heat on moving said element and a heated means relatively to and in contact with each other said wrapper removal providing ventilation air-distribution channel means bounded by said tipping wrapper and opening at said mouth end, and said tipping wrapper permitting ingress of ventilation air into said channel means upstream of said mouth end.

7. A smoking article according to claim 6, wherein said channel means are constituted by grooves extending parallel to the axis of the element and the tipping wrapper is provided with a ring of spaced ventilation perforations disposed to communicate with said grooves at an upstream region thereof.

8. A smoking article according to claim 6, wherein said channel means are constituted by at least one groove which follows a helical path and extends to and opens at the mouth of said element.

9. A smoking article according to claim 6 and further provided with an annular groove from which the said channel means extend.

10. A smoking article according to claim 6, wherein the filter-plug element comprises a further wrapper intermediate the filtration material and the wrapper from which at least a portion is removed by the action of heat, the furtherwrapping being of substantially zero air permeability.

11. A smoking article comprising a rod of smoking material, a filter-plug element and a tipping wrapper serving to interattach said rod and plug element, which element comprises fibrous filtration material wrapped in a wrapper of which at least a portion extending to the mouth end of said element has been removed to a depth not exceeding the thickness of the wrapper, whereby two channel means are formed which follow helical intersecting paths with intermediate portions of wrapper material bonded to underlying filtration material.

12. A smoking-article ventilated filter element substantially as hereinbefore described with reference to Figure 1 or Figures 2 and 3 of the accompanying drawing.