Paper for sanitary or domestic use, such as toilet paper, paper towels or wipes, are in certain cases packaged in the form of rolls on a core.
The core is a cylinder, generally made of cardboard, which is discarded after the paper of the roll has been consumed. The core fulfils several functions:                It serves as support on which the paper sheet is wound during manufacture of the roll. In general, the rolls are manufactured from a very wide master sheet, also called jumbo roll, which is wound around a tube of corresponding length, and the roll obtained is sawn into individual rolls of the desired width;        it keeps the central hole open by withstanding the internal stresses of the roll and preventing the internal turns of the winding from collapsing; and        it keeps the roll in shape by withstanding the crushing forces along its axis or the transverse forces to which the roll is subjected during transportation or during the various handling operations before it is used.        
The core is generally obtained by the helical winding and bonding of one or more flat cardboard strips around a cylindrical former.
Flat cardboard is an inexpensive material, which may be made from recycled fibres. It is also light and its mechanical strength is sufficient for this use.
However, it has the drawback of not being able to be reused or of being rarely utilized in another form after the roll has been consumed and of becoming a waste product.
In the case of toilet paper, it is not recommended to dispose of the standard core by attempting to discharge it with the wastewater as, although composed predominantly of paper making fibres, in particular cellulosic fibres, it disintegrates slowly on contact with water and generally fails to be removed from the toilet bowl, or else it forms a plug and obstructs toilet drain lines before it can be flushed away by the flow.
The Applicant set itself the objective of producing a core for a roll that can be easily discharged with the wastewater of a domestic sanitary facility.
More particularly:                The core must quickly disintegrate on contact with water;        the material must disintegrate in water at a rate sufficient for it to be discharged before forming a plug; the rate at which it disintegrates must be comparable, for the same mass, to that of the tissue paper of which the rolls are generally composed;        the core must have a crush resistance, both in the radial direction and the axial direction, of the same order of magnitude as that of the cardboard that it is intended to replace;        The core must be as easy and as simple to produce as conventional cardboard cores; and        The core must be manufactured with renewable materials; it should have no negative impact in paper recycling processes nor water treatment plants processes as well.        
USPTO Backgrounds
USPTO Backgrounds