CROSS-LINKABLE SILYL-TERMINATED POLYMER COMPOSITION AND METHOD FOR JOINING SUBSTRATES IMPLEMENTING SAID COMPOSITION

1 . A crosslinkable adhesive composition, characterized in that it comprises:

at least one polymer (A) comprising a hydrolyzable alkoxysilane group;

at least one tackifying resin (B);

at least one pyrogenic silica (C);

at least one crosslinking catalyst (D); and

a silsesquioxane resin (E).

2 . The adhesive composition as claimed in claim 1 , characterized in that the polymer (A) comprises at least one, hydrolyzable group of formula (I):

—Si(R 4 ) p (OR 5 ) 3-p   (I)

wherein:

R 4 represents a linear or branched alkyl radical comprising from 1 to 4 carbon atoms, with the possibility that, when there are several R 4 radicals, these radicals are identical or different;

R 5 represents a linear or branched alkyl radical comprising from 1 to 4 carbon atoms, with the possibility that, when there are several R 5 radicals, these radicals are identical or different, with the possibility that two OR 5 groups can participate in the same ring; and

p is an integer equal to 0, 1 or 2.

3 . The adhesive composition as claimed in claim 1 , characterized in that the pyrogenic silica (C) is hydrophobic.

4 . The adhesive composition as claimed in claim 3 , characterized in that the hydrophobic pyrogenic silica (C) is obtained by treatment of a pyrogenic silica with a polydimethylsiloxane.

5 . The adhesive composition as claimed in claim 1 , characterized in that the pyrogenic silica (C) has a BET specific surface area of at least 10 m 2 /g.

6 . The adhesive composition as claimed in claim 1 , characterized in that the silsesquioxane resin (E) corresponds to the following general formula (V):

in which each of R′ 1 to R′ 8 represents, independently of one another, a group chosen from:

a hydrogen atom,

a radical chosen from the group consisting of a linear or branched C1-C4 alkoxy radical, a linear or branched alkyl radical comprising from 1 to 30 carbon atoms, an alkenyl radical comprising from 2 to 30 carbon atoms, an aromatic radical comprising from 6 to 30 carbon atoms, an allyl radical comprising from 3 to 30 carbon atoms, a cyclic aliphatic radical comprising from 3 to 30 carbon atoms and an acyl radical comprising from 1 to 30 carbon atoms, and

an —OSiR′ 9 R′ 10 group in which R′ 9 and R′ 10 each represents, independently of one another, a hydrogen atom or a radical chosen from the group consisting of linear or branched C1-C4 alkyls, linear or branched C1-C4 alkoxys, C2-C4 alkenyls, a phenyl, a C3-C6 allyl radical, a cyclic C3-C8 aliphatic radical and a C1-C4 acyl radical;

provided:

that at least one radical among the R′ 1 to R′ 8 radicals is a C1-C4 alkoxy radical; and

that at least one radical among the R′ 1 to R′ 8 radicals is a phenyl radical.

7 . The adhesive composition as claimed in claim 1 , characterized in that it comprises:

from 3% to 90% by weight of at least one polymer (A);

from 8% to 80% by weight of at least one tackifying resin (B);

from 1% to 10% by weight of the pyrogenic silica (C);

from 0.01% to 10% by weight of crosslinking catalyst (D); and

from 0.1% to 20% by weight of silsesquioxane resin (E);

these percentages by weight being indicated on the basis of the total weight of said composition.

8 . A semi-structural assembly of two substrates comprising the crosslinkable adhesive composition of claim 1 .

9 . The semi-structural assembly of two substrates as claimed in claim 8 in the fields of electronics, construction, and/or the manufacture of means of transport.

10 . A process for assembling two substrates, comprising:

a step (i) of melting the adhesive composition as defined in claim 1 , by heating at a temperature of between 3° and 130° C., then

a step (ii) of depositing said adhesive composition on a surface of a first substrate, then

a step (iii) comprising:

a step (iii1) of crosslinking said adhesive composition by heating at a temperature ranging from 15° C. to 200° C.; and

a step (iii2) of bringing said surface of a first substrate into contact with a surface of a second substrate.

11 . The process as claimed in claim 10 , characterized in that, in step (ii), the composition is deposited on the surface of the first substrate in the form of a bead.

12 . The process as claimed in claim 10 , characterized in that, in step (ii), the composition is deposited on the surface of the first substrate in the form of a layer having a thickness of between 0.1 mm and 2 cm.

13 . The process as claimed in claim 10 , characterized in that the crosslinking step (iii1) is performed at a temperature ranging from 15° C. to 45° C., and in the presence of ambient humidity.

14 . The process as claimed in claim 10 , characterized in that the crosslinking step (iii1) is performed at a temperature ranging from 90° C. to 160° C. and in the presence of an absolute humidity ranging from 10 to 200 g of water per m 3 of gas.

15 . An assembled product comprising at least two substrates bonded by the adhesive composition as defined in claim 1 .