Tearable core, a roll including such a core and a tearable core manufacturing method

A tearable core, adapted for winding a sheet product, comprising a cylindrical body wall defining a longitudinal hole of longitudinal axis XX′, the cylindrical body wall being tearable from an edge, the cylindrical body wall comprising an outer strip and an inner strip, the outer strip being a part of the tearable cylindrical body wall adapted to be in contact with the wound sheet product, the inner strip being another part of the tearable cylindrical body wall facing the longitudinal hole, the outer strip and the inner strip being helically wound on one another and displacedly overlapped in a lateral direction parallel to the longitudinal axis XX′, the outer strip and the inner strip being secured together through their mutually facing surfaces by a first region of attachment,

• wherein the inner and outer strips are made of materials having characteristics such that, either the inner strip is made of cardboard having a water drop less than the water drop of the outer strip, or the outer strip is made of cardboard having a water drop less than the water drop of the inner strip, and
• wherein the cylindrical body wall is built-up as a core tube by securing together the outer strip, a first end part of the outer strip of one turn being superposed and secured to a second end part of the outer strip of an adjacent turn through their mutually facing surfaces by a second region of attachment.