Polyurethane-based composition

1. A composition comprising:

an —NCO component comprising:

A) at least one polyurethane comprising at least two NCO end groups obtained by a polyaddition reaction:

of at least one asymmetric diisocyanate and

of at least one polyol, and

B) at least one polyisocyanate comprising at least three isocyanate —NCO functional groups selected from the group consisting of biurets, isocyanurates, adducts of diisocyanates and of triols, and their mixtures; and

an —OH component comprising:

at least one polyol P1 having a number-average molecular weight of greater than or equal to 1000 g/mol,

at least two polyols P2 having a number-average molecular weight of less than or equal to 500 g/mol, including at least one polyether triol and at least one polyether diol; and

a total content of filler(s) of greater than or equal to 35% by weight, with respect to the total weight of said —OH component.

2. The composition as claimed in claim 1 , in which:

the total content of polyol(s) P1 ranges from 5% to 30% by weight, with respect to the total weight of the —OH component; and/or

the total content of polyol(s) P2 ranges from 5% to 60% by weight, with respect to the total weight of the —OH component.

3. The composition as claimed in claim 1 , in which the —OH component comprises a total content of filler of greater than or equal to 40% by weight, with respect to the total weight of said —OH component.

4. The composition as claimed in claim 3 , in which the filler is selected from the group consisting of clay, quartz, carbonate fillers, kaolin, gypsum, and their mixtures.

5. The composition as claimed in claim 1 , in which the —OH component comprises:

at least 35% by weight of filler chosen from calcium carbonates; and

from 0% to 70%, by weight of chalk;

the percentages by weight being with respect to the total weight of the —OH component.

6. The composition as claimed in claim 1 , in which the —OH component comprises at least one polyamine comprising at least one primary or secondary amine functional group, said polyamine having a number-average molecular weight ranging from 50 g/mol to 5000 g/mol.

7. The composition as claimed in claim 6 , in which the polyamine is selected from the group consisting of polyetheramines, polyamidoamines, fatty amine dimers or trimers, polyethyleneimines (PEI), polyethyleneimine dendrimers, polypropyleneimines (PPI), polypropyleneimine dendrimers, polyallylamines, poly(propylene-ethylene)imines and their mixtures, said polyamine having an amine number ranging from 20 to 1870 mg KOH/g.

8. The composition as claimed in claim 6 , in which the polyamine corresponds to one of the formulae (I-1), (I-2) or (I-3) below:

wherein:

R 4 is a bond, a linear or branched divalent alkylene radical or a divalent arylene radical comprising from 1 to 18 carbon atoms;

R 5 represents a linear or branched divalent alkylene radical comprising from 2 to 12 carbon atoms,

R 6 represents a linear or branched divalent alkylene radical comprising from 2 to 10 carbon atoms,

X a =O, S, NR 7 in which R 7 represents H or a saturated or unsaturated and linear or branched alkyl group comprising from 1 to 10 carbon atoms;

n 3 is an integer ranging from 0 to 4; and

n 4 is an integer ranging from 0 to 2.

9. The composition as claimed in claim 6 , in which the —OH component comprises a total content of polyamine(s) ranging from 0.1% to 6% by weight, with respect to the total weight of said —OH component.

10. The composition as claimed in claim 1 , in which polyurethane A) comprising at least two NCO end groups is obtained by a polyaddition reaction:

of at least one asymmetric diisocyanate and

of at least one polyol,

said asymmetric diisocyanate monomer(s) is (are) selected from the group consisting:

of isophorone diisocyanate (IPDI);

of toluene diisocyanate (TDI);

of the hydrogenated form of TDI

of 2,4′-diphenylmethane diisocyanate (2,4′-MDI);

of the hydrogenated form of 2,4′-diphenylmethane diisocyanate (2,4′-MDI); and

of their mixtures;

and said polyol is selected from the group consisting of polyether polyols, polyester polyols and their mixtures.

11. The composition as claimed in claim 1 , wherein the amounts of isocyanate monomer(s) and of polyol(s) used in the synthesis of the polyurethane A) are such that the NCO/OH molar ratio, denoted r 1 , ranges from 1.5 to 2.

12. The composition as claimed in claim 1 , in which the —NCO component comprises a total content of polyisocyanate(s) comprising at least three —NCO functional groups B) ranging from 5% to 60% by weight, with respect to the total weight of the —NCO component.

13. The composition as claimed in claim 1 , in which the —NCO component comprises B) at least one polyisocyanate comprising at least three isocyanate NCO functional groups selected from the group of isocyanurates.

14. The composition as claimed in claim 1 , in which the —OH component/—NCO component ratio by volume ranges from 1/3 to 3/1.

15. The composition as claimed in claim 1 , wherein it is an adhesive composition.