Flame-retardant treatment of lignocellulosic materials, resulting flame-retarded lignocellulosic materials and uses thereof

A process for preparing a biobased flame-retarded lignocellulosic material from biobased lignocellulosic material, comprising the following steps:

• optionally steam exploding and/or bleaching the biobased lignocellulosic material,
• impregnating the biobased lignocellulosic material, optionally steam-exploded and/or bleached, in or with an aqueous solution consisting of:
• from 0.5% to 7% phytic acid and from 1% to 22% urea, said percentages being expressed by mass relative to the total mass of the aqueous solution, with a balance of the aqueous solution being water,
• optionally drying the impregnated biobased lignocellulosic material until it has a moisture content ranging from 5% to 20%, said percentages being expressed by mass relative to the total mass of the impregnated biobased lignocellulosic material,
• cooking the impregnated and optionally dried biobased lignocellulosic material,
• the biobased flame-retarded lignocellulosic material thus obtained comprising a content of phosphorus originating from phytic acid ranging from 0.1% to 10%, said percentages being expressed by mass relative to the total mass of the biobased flame-retarded lignocellulosic material,
• wherein said biobased flame-retarded lignocellulosic material consists of said biobased lignocellulosic material impregnated in or with the aqueous solution, and said biobased lignocellulosic material has not undergone any chemical treatment other than optionally steam exploding and/or bleaching.