Silylated sealing composition with improved adhesion on metallic substrates

Moisture curable silylated composition comprising, on the basis of the total weight of said composition:

• from 35 to 65% by weight of a polymer (A) comprising at least 2 alkoxysilyl terminal groups of formula (I):
• wherein
• R1 represents a hydrocarbon-based divalent radical comprising from 5 to 15 carbon atoms which may be aromatic or aliphatic, linear, branched or cyclic,
• R2 represents a linear or branched alkylene divalent radical comprising from 2 to 4 carbon atoms,
• R3 represents a linear or branched alkylene divalent radical comprising from 1 to 6 carbon atoms,
• R4 and R5, which are identical or different, each represent a linear or branched alkyl radical having 1 to 4 carbon atoms, with the possibility, when there are several R4 (or R5) radicals, that these are identical or different,
• R6 represents a hydrogen atom or a radical comprising 1 to 6 carbon atoms which may be aromatic or aliphatic, linear, branched or cyclic, or a radical selected among the radicals:
• of formula (Ia):
• of formula (Ib):
• or
• of formula (Ic):
• wherein R7 is linear or branched alkyl radical comprising from 1 to 6 carbon atoms;
• n is an integer such that the average molecular weight of the polyether block of formula —[OR2]n— is between 300 g/mole and 40000 g/mole,
• m is an integer different from 0 such that the average molecular weight of the polymer (A) is between 500 g/mole and 50000 g/mole, and
• p is an integer equal to 0, 1 or 2;
• from 2.5 to 12% by weight of a polymer (B) comprising at least 2 alkoxysilyl terminal groups of formula (II)
• wherein R2, R4, R5, n and p are such as defined for formula (I);
• and
• from 7.5 to 28% by weight of an alkoxy modified silsesquioxane (C), and
• from about 10 to 20% by weight of a polyether (D) which comprises only one alkoxysilyl terminal group linked to the main polyether chain by a divalent group:—O—CO—NH—(CH2)3— in which —(CH2)3— is directly linked to the Si atom of the alkoxysilyl terminal group.