Filter Additive

Abstract

The present invention relates to a method of producing a filter element for inclusion in a smoking article, the method comprising applying an additive to filter material, the additive being solid at room temperature and the method involving heating the additive so that it melts.

Description

[0001]The invention relates to methods for making filter elements and filters for smoking articles, the filter elements and filters comprising an additive material. In particular, the invention relates to methods of incorporating an additive which is solid at room temperature into filter material, the method comprising the step of melting the additive material.[0002]A wide variety of materials have been used as filter materials for tobacco smoke. The most commonly used filter material is cellulose acetate tow. However, whilst cellulose acetate has an excellent capacity to filter tobacco smoke, it has the drawback that it is slower to degrade than other materials and can therefore be disadvantageous environmentally.[0003]Filter materials made from non-woven sheet material and paper are known. Suitable sheet materials include polyvinyl alcohol, reconstituted tobacco, starch, and polylactic acid. These materials are much more readily degradable than cellulose acetate tow, however, they...

AI Technical Summary

Benefits of technology

The patent text explains the use of additives such as triacetin, TEC, and PEG 400 in cellulose acetate filters to give them the necessary hardness for cigarette manufacture and use, and also to improve their ability to remove semi-volatile compounds from tobacco smoke. The additives are in liquid form and are sprayed on to the filter material, where they bind or fuse adjacent fibers together, increasing the hardness of the filter material. However, there is a limit to the amount of additives that can be included, as too much can compromise the filter's filtration properties.

Problems solved by technology

However, whilst cellulose acetate has an excellent capacity to filter tobacco smoke, it has the drawback that it is slower to degrade than other materials and can therefore be disadvantageous environmentally.

These materials are much more readily degradable than cellulose acetate tow, however, they have drawbacks.

The mode of action of the plasticizers does, however, mean that there is an upper limit to the amount that may be incorporated into cellulose acetate tow filter material.

When above about 7% of plasticizer by weight of the filter is included, the plasticizer starts to have a detrimental effect on the cellulose acetate tow, forming holes which compromises its filtration properties.

Whilst inclusion of plasticizers such as triacetin, TEC or PEG 400 in CA filters is relatively common, their inclusion in non-woven sheet and paper filter materials is less attractive.

Firstly, the plasticizers are used in CA filters to bind fibres and the plasticizer would clearly not have this advantageous effect when added to non-woven sheet material or paper (in which the fibres are already bound within the sheet structure).

Secondly, these commonly used plasticizers are liquids and their application to non-woven sheet and paper filter materials will be limited as they will cause these materials to become soggy and to lose their structural integrity.

Paper, the most commonly used sheet filter material, may start to disintegrate when moist, and will therefore have a reduced acceptability to the user.