GB2285908A

GB2285908A - Filter material

Info

Publication number: GB2285908A
Application number: GB9401379A
Authority: GB
Inventors: Brian Adams; Brian Fitzsimons
Original assignee: Gallaher Ltd
Current assignee: Gallaher Ltd
Priority date: 1994-01-25
Filing date: 1994-01-25
Publication date: 1995-08-02
Also published as: GB9401379D0

Abstract

A filter material for a smoking product, the material comprising fibres of a physiologically harmless, synthetic polymer containing only the elements C and H or C,H and O, bonded together by a plasticiser.

Description

FILTER FOR SMOKING PRODUCT Typical smoking products, such as cigarettes and cigarillos are provided at the buccal end with a filter element cut from a cylindrical filter rod which has been formed by bundling and wrapping a cellulose acetate tow, or crimping and wrapping a cellulose paper web. Cellulose acetate is more commonly used because, although paper costs are currently less then 60% of cellulose acetate costs, paper filters have a poor end appearance and cannot be made with an acceptable hardness at typical filter efficiencies of 40-50%. These problems have limited the use of paper filters despite their low cost relative to conventional cellulose acetate filters.

In accordance with the present invention, a filter material for a smoking product comprises fibres of cellulose and fibres of a physiologically harmless, synthetic polymer containing only the elements C and H or C,H and 0, such as cellulose acetate, bonded together by a plasticiser, such as triacetin (glycerol triacetate). The synthetic polymer preferably includes no aromatic structures.

This material, in which the plasticiser causes the synthetic polymer to bond to itself and to the cellulose can provide a cheaper filter element with hardness characteristics superior to either paper or acetate alone, and with good end appearance.

The material may be produced by adding the plasticiser to bloomed cellulose acetate in a spray chamber before being united with a cellulose paper web which has passed through a crimping unit, and thereafter passing the combination through a cylindrical filter rod bundling and wrapping unit. Alternatively, a web composed of a mixture of cellulose and cellulose acetate fibres, together with a plasticiser, is fed to the filter rod making unit.

The cellulose may form between 50 and 95%, preferably substantially 75%, of the mixture of cellulose and cellulose acetate, by weight. The plasticiser may be applied in a quantity of between 8 and 12%, preferably substantially 10%, by weight of the cellulose and cellulose acetate components.

In one example, a 36 gsm cellulose paper web, 125 mm wide, was fed through a crimping unit with a 6.4 dpf (denier per filament)/17 td (total denier) acetate tow.

The mixture was plasticised with 10% weight for weight glycerol triacetate giving a 24.65 mm circumference filter rod with a hardness of 91%. The following table shows comparable parameters for a filter element cut from the above rod, with cellulose paper and cellulose acetate filter elements of the same dimensions, and matched hardness.

Parameter Acetate Payer PaPer Acetate % Hardness 91 91 91 Pressure Drop mmH20 47 78 70 % Filter Efficiency 48 63 48 Weight mg 96 (Paper) 194 133 30 (Acetate) The cost of paper is approximately 40% that of acetate, therefore the cost ratios (weight x relative cost) are Acetate Paper 30 x 1.0 + 96 x 0.4 = 68 Paper 194 x 0.4 = 78 Acetate 133 x 1.0 = 133

Claims

CLAIMS 1. A filter material for a smoking product, the material comprising fibres of cellulose and fibres of a physiologically harmless, synthetic polymer containing only the elements C and H or C,H and 0, bonded together by a plasticiser.
2. A filter material according to claim 1, wherein the synthetic polymer is cellulose acetate.
3. A filter material according to claim 1 or claim 2, in which the plasticiser is triacetin.
4. A filter material according to any one of the preceding claims, in which the cellulose forms between 50 and 95% of the mixture of cellulose and cellulose acetate, by weight.
5. A filter material according to claim 4, in which the cellulose forms substantially 75% of the mixture of cellulose and cellulose acetate, by weight.
6. A filter material according to claim 4 or claim 5, in which the plasticiser is applied in a quantity of between 8 and 12% by weight of the cellulose and cellulose acetate components.
7. A filter material according to claim 6, wherein the plasticiser is applied in a quantity of substantially 10% by weight of the cellulose and cellulose acetate components.
8. A filter material, substantially as described.
9. A method of making a filter material according to any one of the preceding claims, the method comprising adding the plasticiser to bloomed cellulose acetate in a spray chamber before being united with a cellulose paper web which has passed through a crimping unit, and thereafter passing the combination through a cylindrical filter rod bundling and wrapping unit.
10. A method of making a filter material according to any one of claims 1 to 8, wherein a web composed of a mixture of cellulose and cellulose acetate fibres, together with a plasticiser, is fed to a filter rod making unit.