Heat-crosslinkable adhesive composition

A heat-crosslinkable adhesive composition, comprising:

• from 20% to 84% by weight of a composition (A) comprising:
• from 75% to 100% by weight of at least one polyurethane comprising two end groups of alkoxysilane type which are hydrolyzable and having the following formula (I):
• wherein:
• R1 represents a divalent hydrocarbon radical comprising from 5 to 15 carbon atoms which can be aromatic or aliphatic and linear, branched or cyclic;
• Ral represents a divalent hydrocarbon radical resulting from a saturated diol, by replacement of each of the two hydroxyl groups by a free valency, said diol having a hydroxyl number IOH of greater than 220 mg KOH/g;
• Rac represents a divalent hydrocarbon radical resulting from a saturated dicarboxylic acid, by replacement of each of the two carboxyl —COOH groups by a free valency, said acid having an acid number IA of greater than 200 mg KOH/g;
• n is a number such that the polyester diol of formula (III):
• has a hydroxyl number IOH of between 4 and 24 mg KOH/g;
• R3 represents a linear divalent alkylene radical comprising from 1 to 3 carbon atoms;
• R4 and R5, which are identical or different, each represent a linear or branched alkyl radical of 1 to 4 carbon atoms, with the possibility, when there are several R4 (or R5) radicals, that the latter are identical or different;
• m is an integer such that the number-average molar mass of the polymer of formula (I) is between 400 g/mol and 50 000 g/mol;
• p is an integer equal to 0, 1 or 2;
• from 0% to 25% by weight of at least one polyurethane comprising one end group of alkoxysilane type which is hydrolyzable and having the following formula (II):
• wherein:
• n1 and m1 are each integers such that the number-average molar mass of the polyurethane of formula (II) is between 400 g/mol and 50 000 g/mol;
• Rac and Ral are as defined above;
• and
• R represents a monovalent hydrocarbon radical resulting from a monol, by replacement of the hydroxyl group by a free valency;
• said composition (A) being obtained by a process which comprises a stage of preparation of a composition (A-1) comprising an amorphous polyester diol of abovementioned formula (III) or a mixture of amorphous polyester diols of abovementioned formula (III), by reacting, by a polycondensation reaction:
• (i) a composition (A-1-1) comprising at least one saturated dicarboxylic acid, said composition (A-1-1) having an acid number IA of greater than 200 mg KOH/g;
• and
• (ii) a composition (A-1-2) comprising at least one saturated diol, said composition (A-1-2) having a hydroxyl number IOH of greater than 220 mg KOH/g;
• and
• (iii) optionally a composition (A-1-3) comprising at least one monol;
• provided that at least one saturated dicarboxylic acid of the composition (A-1-1) or at least one saturated diol of the composition (A-1-2) is branched;
• the composition (A-1) having a hydroxyl number IOH of between 4 and 24 mg KOH/g;
• from 15% to 79% by weight of a compatible tackifying resin (B), with a number-average molar mass of between 200 g/mol and 50 000 g/mol;
• and
• from 0.01% to 5% by weight, of a crosslinking catalyst (C).