| 摘要 |
A rod-form body of smoke filtration material, preferably fibrous or filamentary, is wrapped in a fibrous or filamentary plugwrap comprising at least 50% by weight of fibres or filaments of thermoplastics material. The plugwrap may have premeability for air of not less than 10,000 Coresta units. The majority, suitably at least 80% by weight, of the material of the rod-form body is a material other than the said themoplastics material of the plugwrap. Thus the smoke-filtration material may comprise crimped polypropylene tow and the plugwrap be composed substantially wholly of fibrous cellulose acetate or conversely. Portions of such filter rod may be subjected to a hot-shaping process to provide grooved filter elements. |
