Non-woven product that contains organic and/or mineral particles and its process for production

A flexible non-woven product that has a density that is less than 1 g/cm3 and that is formed by at least two layers of synthetic fibers or filaments superposed in a Z direction that is perpendicular to a XY plane of said product, having undergone at least one mechanical or hydraulic needling operation, whereby said non-woven product also integrates particulate feedstocks in a form of rigid particles distributed in a monomodal or multimodal manner in the product and is at least partially coated or encapsulated by a binding material that can provide connecting points between the filaments or fibers to one another, physical and mechanical properties of the flexible non-woven product being affected by size and number of the connecting points and the binding material,

• the rigid particles comprising mineral particles, a particle density of the mineral particles being between 1.6 to 4.2 g/cm3,
• the flexible non-woven product being adapted to be a reinforcement for sealing membranes, the flexible non-woven product providing mechanical and heat stability during heat treatments and durability as a sealing membrane reinforcement,
• wherein at least one population or fraction of the rigid particles, called “large particles,” has a size such that either:
• 3×(√{square root over (SMf)})3≦v, or
• 5×(√{square root over (SMf)})3≦v,
• where SMf corresponds to a mean cross-section of the fibers or filaments that form the layers of the non-woven product, and v represents a mean individual volume of the organic or mineral particles, and
• the mean individual volume verifies the following inequality of either:
• v≦50×(√{square root over (SMf)})3, or
• v≦30×(√{square root over (SMf)})3.