Cellulose substrate with anti-flame properties and relative production method

A method for sulphation and phosphorylation of a cellulose substrate to impart anti-flame properties to the cellulose substrate comprising the following operations:

• i) provide a cellulose substrate;
• ii) prepare a sulphation and phosphorylation solution, the sulphation and phosphorylation solution comprising water, ammonium sulphamate, urea and at least one compound of formula (I):
• PO(OH)2—R—PO(OH)2 (I)
• wherein
• R represents a linear or branched, substituted or unsubstituted C1-10 alkyl group;
• a N(R1) group;
• a R2N(R3)R4 group;
• R1 represents H, a linear or branched, substituted or unsubstituted C1-5 alkyl group;
• R2 and R4 represent independently a linear or branched, substituted or unsubstituted C1-5 alkyl group;
• R3 represents a linear or branched, substituted or unsubstituted C1-5 alkyl group;
• a R5N(R6)R7 group;
• R5 and R7 represent independently a linear or branched, substituted or unsubstituted C1-5 alkyl group;
• R6 represents a linear or branched, substituted or unsubstituted C1-5 alkyl group;
• a R8N(R9)R10 group;
• R8, R9 and R10 represent independently a linear or branched, substituted or unsubstituted C1-5 alkyl group;
• with the proviso that the number of —PO(OH)2 groups in the general formula (I) is not greater than 5;
• iii) immerse the cellulose substrate in the sulphation and phosphorylation solution;
• iv) extract the cellulose substrate from the sulphation and phosphorylation solution;
• v) maintain the cellulose substrate at a temperature comprised between 110° and 175° C. for a period of time comprised between 1 minute and 3 hours, obtaining at the end a sulphated and phosphorylated cellulose substrate with anti-flame properties.