Substance delivery device

DETAILED DESCRIPTION In a first aspect, the pre nt invention provides a substance delivery device comprising a combustible paperboard strip and at least one of a substance toxic to insects and a perfume.
The term paperboard refers to fibrous structures which are made by felting fibres from a fluid suspension.
The felting process results in the fibres becoming enmeshed with each other so providing a continuous matrix.
The presence of enmeshed fibres such as result from a felting process can be detected by visual inspection of the product, optionally using magnifying apparatus such as a microscope.
The resulting paperboard is more flexible (and so less brittle) than known resin-bound boards.
A delivery device manufactured from such a paperboard is less likely to be damaged during packing, transit or subsequent handling than devices made by processes involving compression of fibres with a resin binder.
Known resin-bound delivery devices also tend to "dust" in that small particles tend to break from the coil during handling.
This leaves a fine powder on the hands of the user and on any other surfaces with which the coil has been in contact.
A significant mass of the coil can also be lost during transit through dusting leading to a reduction in the performance of the coil.
The delivery device of the invention has the advantage that it has a reduced tendency to form "dust".
The delivery device of the invention can also be significantly lighter than known devices in which cellulose fibres are bound together by a resin, while still burning for the same amount of time.
This can reduce distribution costs.
The use of a paperboard material in the delivery device of the invention means that the device can be produced in a wide range of colours by selection of a material on which images can be formed, for example using inks, for example by printing or other techniques.
Known devices made from materials other than paperboard tend only to be produced in a limited range of colours, typically green or black, in some cases because of difficulties associated with printing on resin materials