GB2075328A

GB2075328A - Tobacco-smoke filter

Info

Publication number: GB2075328A
Application number: GB8111949A
Authority: GB
Original assignee: Filtrona PLC
Current assignee: Essentra PLC
Priority date: 1980-04-21
Filing date: 1981-04-15
Publication date: 1981-11-18
Also published as: GB2075328B; AU6968481A; JPS56164782A; NL8101953A; DE3115904A1; FR2480572A1; CH642240A5; BE888506A

Abstract

A tobacco smoke filter comprising a longitudinally corrugated and/or fibrillated web of paper gathered laterally into, and held in, rod form, the paper being one made on an inclined wire machine from fibres 1 to 25 millimetres in length and having a finished substance before corrugation and/or fibrillation of 12 to 40 grammes per square metre.

Description

SPECIFICATION Inclined wire paper filter The present invention relates to tobacco smoke filters and their production and provides a longitudinally corrugated and/orfibrillated web of paper gathered laterally into, and held in, rod form, the paper being one made on an inclined wire machine from fibres 1 to 25 millimetres in length and having a finished substance before corrugation andlorfibrilla- tion of 12 to 40 grammes per square metre.

The invention also provides a method of producing a tobacco smoke filter which comprises forming a web of paper of finished substance of 12 to 40 grammes per square metre using an inclined wire machine with a fibre stock of consistency from 0.008 to 1% (e.g. about 0.1%) and fibre length of 1 to 25 millimetres, continuously advancing the finished paper longitudinally between co-operating rolls having circumferentially-extending corrugations, and thereafter continuously gathering the longitudinally advancing paper web laterally into rod form and continuously cutting the resulting continuously produced rod transversely into finite lengths.

The said finished paper web is generally advanced longitudinally between co-operating embossing rolls having circumferential corrugations or alternate grooves and ridges which can extend perpendicular to the roll axes or can instead extend helically therearound; this corrugation treatment tends to fibrillate the web longitudinally thereof, and in some cases it is such fibrillation rather than longitudinal corrugation which is evident in the treated web, though frequently both corrugation and fibrillation are readily observable.

It is especially preferred to use in the invention an inclined wire having a knuckle such as to yield a finished paper web having therethrough a multiplicity of preferably uniformly distributed apertures; the design ofthe wire decides the number, size and pattern of the apertures. One such paper, for example, has generally hexagonal apertures at the rate of about 10 cm-l, with the fibre concentrated in the relatively thin walls between apertures and little or no fibre bridging the apertures. Such aperture paper is known as tea-bag paper or diffusion paper, for which uses it is made from stock containing artificial fibre; aperture paper used according to the invention is preferably 100% natural (e.g. wood pulp) fibre.

The mentioned fibre length is preferably 1 to 12, e.g. 2.5 to 6 millimetres, and the finished substance of the web before corrugation is preferably from 15 to 25 grammes per square metre. The fibre of the paper web may be 100% natural fibre (e.g. wood pulp), 100% synthetic fibre, or mixtures of the two, preferably being 100% natural fibre for aperture paper. When the web comprises synthetic fibre, bonding agents may be incorporated to increase the hardness of the finished rod.

Bonding agent may be incorporated in the paper web, or added to it before condensation to rod form, the bonding agent acting (e.g. on heating) to bond the gathered web into a porous but coherent rod which is self-sustaining without a wrapper. In other embodiments, the gathered web may be wrapped continuously in conventional manner as part of the rod forming step, and this may be done even when the gathered web of the finished product is selfsustaining.

Cigarettes provided with filters according to the invention have been found to provide a smoke of excellent taste, and the filters can exhibit a better mix of pressure drop and hardness values than those currently available In the preferred embodiments of the invention using aperture paper, the apertures give a cellular or "expanded polystyrene" effect when the paper is gathered to rod form, and result in higher rod hardness and resilience than for rods of equivalent density made from non-aperture paper, the hardness and resilience being on a par with those of cellulose acetate tow rods of the same density.Filters according to the invention, especially those of aperture paper, can have an excellent end appearance and staining characteristics (as good as or better than those of acetate tow filters which heretofore have been preferred in this respect by the public), even at very low tip pressure drop values. Both the aperture and non-aperture paper varieties have excellent taste characteristics, much better than for prior paper cigarette filters, and the former can be produced to any given specification at up to 30% lower density than the equivalent conventional paperfilter rods. Filters according to the invention can give better retention of tobacco smoke particulate phase than cellulose acetate tow filters of the same pressure drop (PD), as shown in the accompanying graph of % tar retention against tip pressure drop (in mm.Wg) for conventional wrapped acetate tow filter tips (area A) and non-aperture paper filter tips according to the invention (line B), the tips in each case being 20 mm. long by 24.6 mm. circumference.

Filters according to the invention can be wrapped in the standard range of plugwraps and can be ventilated in any conventional manner.

In the following Examples filter rods according to the invention of different pressure drops (PD) are compared with similar conventional rods of wrapped acetate tow and wrapped crepe pauper. The comparisons are standardised to a 90 mm. long x 24.50 mm. circumference rod (i.e. 15 x 24 mm. tip) with 26.5 mm. 27g/m2 plugwrap; the 90 mm. rod is the form in which the filter would typically be supplied to a filter cigarette manufacturer for cutting into 15 mm. individual tips. In each Example the "tip PD" and "Tar Retention" values are those of the 15 mm. tip lengths; all pressure drops are expressed in mm. Wg. (Water gauge).

EXAMPLE 1 Rod size 90x 24.5; PD 185mms. Wg.

COMPARISON INVENTION ACETATE TOW "MyRIA"FILTER Material; wt/m non-aperture 6.4W39 Estron 4091m2 creped porous web, paper 25g/m2 (100% Wood Puip) Acetate Tow Weight gms/10 rods 6.22 6.39 7.80 Filling Densitygms/cc 0.130 0.135 0.166 Hardness % 90.0 91.5 89.5 Tip PD mms.Wg. 33.9 31.0 33.9 Tar retention % 40.0 29.3 47.0 EXAMPLE 2 Rod size 90 x 24.5; PD 235mms!,Wg, COMPARISON INVENThAN ACETA TE TOW "MYRIA"FILTER Material;wt'm2 Aperture web;; 5Y/40 Estron 36g/m2 creped 25g/m paper (100% Wood Pulp) Acetate Tow Weight gms/10 rods 6.79 6.49 8.34 Filling Densitygms/cc 0.144 0.137 0.178 Hardness % 91.5 91.5 90 Tip PD mms.Wg. 43 39 43 Tar retention % 44.0 33.7 51.0 EXAMPLE3 Rod size 90x 24.5; PD 500 mms. Wg.

COMPARISON INVENTION ACETA TE TOW "MYRIA"FILTER Material;wt'm2 Porous web non- 2Y/46 Estron 36g/m2 creped aperture 25g/m2 paper (100%Wood Pulp) Acetate Tow Weight gms/10 rods 8.09 6.92 9.00 Filling Densitygms/cc 0.174 0.174 0.195 Hardness % 93 92 93.5 Tip PD mms.Wg. 91.7 83 91.7 Tar retention % 58.5 49.1 67.0 The Examples show particularly the good perfor mance of the filters according to the invention at low PD, excellent end appearance being exhibited both before and after smoking even at such low PD.

In Example 1 above the acetate tow designation 6.4Y/46 means a 46 x 103 denier tow of 6.4 denier Y-section filaments, the two designations in Exam ples 2 and 3 having corresponding significance.

In each of the Examples the fibre length of the inclined wire paper in the filter according to the invention was 2.5-6 mms., and the paper used was finely corrugated (about 10 corrugations per cm). In general, the fineness of corrugation (and/or fibrillation) in paper used according to the invention can vary widely e.g. from 5 to 30 corrugations and/orfibrillation zones per cm.

Claims

1. Atobacco smokefiltercomprising a longitudinally corrugated and/or fibrillated web of paper gathered laterally into, and held in, rod form, the paper being one made on an inclined wire machine from fibres 1 to 25 millimetres in length and having a finished substance before corrugation and/or fibrillation of 12 to 40 grames per square metre.

2. A filter according to claim 1 wherein the paper is one formed on the inclined wire with a multiplicity of apertures therethrough.

3. A filter according to claim 1 or 2 wherein the fibre length is from 1 to 12 millimetres.

4. A filter according to claim 1,2 or 3 wherein the finished substance of the web before corrugation is from 15 to 25 grammes per square metre.

5. A method of producing a tobacco smoke filter which comprises forming a web of paper of finished substance of 12 to 40 grammes per square metre using an inclined wire machine with a fibre stock of consistency from 0.008 to 1% and fibre length of 1 to 25 millimetres, continuously advancing the finished paper longitudinally between co-operating rolls having circumferentially-extending corrugations, and thereafter continuously gathering the longitudinally advancing paper web laterally into rod form and continuously cutting the resulting continuously produced rod transversely into finite lengths.

6. A method according to claim 5 wherein the paper is formed on the inclined wire with a multiplicity of apertures therethrough.

7. A method according to claim 5 or 6 wherein the consistency of the fibre stock is about 0.1%.