Self-adhesive composition for the bonding of substrates with low surface energy

1. An adhesive composition comprising:

A1) at least 4% by weight of one or more polysilylated polymers with a number-average molecular mass (Mn) of at least 6000 g/mol, wherein the one or more polysilylated polymers comprise a main polyether and/or polyurethane chain and at least two hydrolysable silylated end groups, said hydrolysable silylated end groups being attached to the main polymer chain by a urethane or ether function (“connecting group”); and

A2) at least 13% by weight of one or more monosilylated polymers with an average molecular weight (Mn) of at least 1000 g/mol, wherein the one or more monosilylated polymers comprise a main polyether and/or polyurethane chain and a hydrolysable silylated end group, said hydrolysable silylated end group being attached to the main polymer chain by a urethane or ether function (“connecting group”); and

B) at least 25% by weight of one or more tackifying resins, wherein each of the one or more tackifying resins comprises a hydroxyl index of less than or equal to 50 and comprise a number-average molecular mass ranging from 100 to 6000 g/mol, and are chosen among:

i. resins obtained by polymerization or copolymerization, optionally by hydrogenation, of mixtures of unsaturated aliphatic and/or aromatic hydrocarbons comprising approximately 5, 9 or 10 carbon atoms derived from petroleum fractions;

ii. resins obtained by a process comprising the polymerization of alpha methyl styrene or copolymerization of alpha methyl styrene with other hydrocarbon monomers;

iii. rosins of natural origin or modified rosins; and mixtures thereof; and

C) at least 0.2% of one or more crosslinking catalysts,

wherein the contents in % by weight are expressed relative to the total weight of the adhesive composition, and the sum of the contents of all the ingredients of the adhesive compositions is 100%.

2. The composition according to claim 1 , wherein the polysilylated polymer A1) or at least one of the polysilylated polymers A1), corresponds to the following formula (I) or (II), or mixtures thereof:

formula (I):

wherein:

B represents a divalent (for f=2) or trivalent (for f=3), linear, branched, cyclic, alicyclic or aromatic, saturated or unsaturated hydrocarbon radical containing from 2 to 66 carbon atoms, optionally comprising one or more heteroatoms;

R 3 represents a linear or branched divalent alkylene radical comprising from 1 to 6 carbon atoms;

R′ 2 represents a linear or branched divalent alkylene radical comprising from 2 to 4 carbon atoms;

R 4 and R 5 , identical or different, each represent a linear or branched alkyl radical comprising 1 to 4 carbon atoms; R 4 can optionally be engaged in a ring;

n″ is a non-zero integer such that the number-average molecular mass of the polyether block of formula —[OR′ 2 ] n″ — ranges from 150 g/mol to 20,000 g/mol;

p is an integer equal to 0 or 1;

f is an integer equal to 2 or 3; and

the n″ and f indexes are such that the number-average molecular mass of the polysilylated polymers A1) is as defined in claim 1 ;

formula (II):

wherein:

B represents a divalent (for f=2) or trivalent (for f=3), linear, branched, cyclic, alicyclic or aromatic, saturated or unsaturated hydrocarbon radical containing from 2 to 66 carbon atoms, optionally comprising one or more heteroatoms;

R 1 represents a divalent hydrocarbon radical comprising from 5 to 15 carbon atoms, which can be aliphatic or aromatic, linear, branched or cyclic;

R 3 represents a linear or branched divalent alkylene radical comprising from 1 to 6 carbon atoms;

R 2 and R′ 2 , identical or different, each represent a linear or branched divalent alkylene radical comprising from 2 to 4 carbon atoms;

R 4 and R 5 , identical or different, each represent a linear or branched alkyl radical comprising 1 to 4 carbon atoms; R 4 can optionally be engaged in a ring;

n is a non-zero integer such that the number-average molecular mass of the polyether block of formula —[OR 2 ] n — ranges from 300 g/mol to 40,000 g/mol;

n′ is a zero or non-zero integer such that the number-average molecular mass of the polyether block of formula —[OR′ 2 ] n′ — ranges from 0 g/mol to 20,000 g/mol;

m is a zero or non-zero integer;

p is an integer equal to 0 or 1;

f is an integer equal to 2 or 3; and

the m, n, n′ and f indexes are such that the number-average molecular mass of the polysilylated polymers A1) is as defined in claim 1 .

3. The composition according to claim 2 , wherein the polysilylated polymer(s) A1) correspond to formula (II), wherein m is not null.

4. The composition according to claim 2 , wherein p=0.

5. The composition according to claim 2 , wherein p=1.

6. The composition according to claim 1 , wherein the monosilylated polymer A2) or at least one of the monosilylated polymers A2), corresponds to the following formula (Ibis) or (IIbis), or mixtures thereof:

formula (Ibis):

wherein:

R 0 represents a divalent hydrocarbon radical comprising from 1 to 60 carbon atoms, which can be aliphatic, aromatic or alkyl aromatic, linear, branched or cyclic;

R 3 represents a linear or branched divalent alkylene radical comprising from 1 to 6 carbon atoms;

R′ 2 represents a linear or branched divalent alkylene radical comprising from 2 to 4 carbon atoms;

R 4 and R 5 , identical or different, each represent a linear or branched alkyl radical comprising 1 to 4 carbon atoms; R 4 can optionally be engaged in a ring;

n′″ is a zero or non-zero integer such that the number-average molecular mass of the polyether block of formula —[OR′ 2 ] n′″ — ranges from 0 g/mol to 20,000 g/mol;

p is an integer equal to 0, 1 or 2; and

R 0 and n′″ are such that the number-average molecular mass of the monosilylated polymers A2) is as defined in claim 1 ;

formula (IIbis):

wherein:

R 0 represents a divalent hydrocarbon radical comprising from 1 to 60 carbon atoms, which can be aliphatic, aromatic or alkyl aromatic, linear, branched or cyclic;

R 1 represents a divalent hydrocarbon radical comprising from 5 to 15 carbon atoms, which can be aliphatic or aromatic, linear, branched or cyclic;

R 3 represents a linear or branched divalent alkylene radical comprising from 1 to 6 carbon atoms;

R 2 and R′ 2 , identical or different, each represent a linear or branched divalent alkylene radical comprising from 2 to 4 carbon atoms;

R 4 and R 5 , identical or different, each represent a linear or branched alkyl radical comprising 1 to 4 carbon atoms; R 4 can optionally be engaged in a ring;

n is an integer such that the number-average molecular mass of the polyether block of formula —[OR 2 ] n — ranges from 300 g/mol to 40,000 g/mol;

n′″ is a zero or non-zero integer such that the number-average molecular mass of the polyether block of formula —[OR′ 2 ] n′″ — ranges from 0 g/mol to 20,000 g/mol;

m is a zero or non-zero integer;

p is an integer equal to 0, 1 or 2; and

R 0 and the m, n, and n′″ indexes are such that the number-average molecular mass of the monosilylated polymers A.2) is as defined in claim 1 .

7. The composition according to claim 6 , wherein the monosilylated polymer(s) A2) correspond to formula (IIbis), wherein m is null.

8. The composition according to claim 1 , wherein the polysilylated polymer(s) A1) is (are) disilylated.

9. The composition according to claim 1 , wherein:

the polysilylated polymer(s) A1) has (have) a number-average molecular mass (Mn) of from 6000 to 55,000 g/mol; and

the monosilylated polymer(s) A2) has (have) a number-average molecular mass of from 1000 to 55,000 g/mol.

10. The composition according to claim 1 , wherein:

the content in polysilylated polymers(s) A1) is from 5 to 59.8% by weight, for the weight of the adhesive composition;

the content in monosilylated polymers(s) A2) is from 15 to 69.8% by weight, for the weight of the adhesive composition;

the content in tackifying resin(s) B) is from 25 to 79.8% by weight, for the weight of the adhesive composition; and

the content in crosslinking catalyst C) ranges from 0.2 to 4% by weight of the weight of the adhesive composition.

11. A self-adhesive article comprising a support layer coated with a self-adhesive layer, said self-adhesive layer consisting of an adhesive composition as defined in claim 1 , in the crosslinked state.

12. The self-adhesive article according to claim 11 , which can be obtained by a process comprising the following steps:

a) packaging of an adhesive composition at a temperature ranging from 20 to 130° C.; then

b) coating a carrier surface with the adhesive composition obtained in step (a); then

c) crosslinking the coated adhesive composition by heating it to a temperature ranging from 20 to 200° C. in a gaseous environment comprising from 10 to 200 mg of water molecules per m 3 of gas; and

d) laminating or transferring the crosslinked adhesive layer onto a support layer or a non-stick release film; wherein said support layer or release film can be the back side of the carrier surface, and wherein the adhesive composition comprises:

A1) at least 4% by weight of one or more polysilylated polymers with a number-average molecular mass (Mn) of at least 6000 g/mol, wherein the one or more polysilylated polymers comprise a main polyether and/or polyurethane chain and at least two hydrolysable silylated end groups, said hydrolysable silylated end groups being attached to the main polymer chain by a urethane or ether function (“connecting group”); and

A2) at least 13% by weight of one or more monosilylated polymers with an average molecular weight (Mn) of at least 1000 g/mol, wherein the one or more monosilylated polymers comprise a main polyether and/or polyurethane chain and a hydrolysable silylated end group, said hydrolysable silylated end group being attached to the main polymer chain by a urethane or ether function (“connecting group”); and

B) at least 25% by weight of one or more tackifying resins, wherein each of the one or more tackifying resins comprises a hydroxyl index of less than or equal to 100; and

C) at least 0.2% of one or more crosslinking catalysts,

wherein the contents in % by weight are expressed relative to the total weight of the adhesive composition, and the sum of the contents of all the ingredients of the adhesive compositions is 100%.

13. The self-adhesive article according to claim 11 , wherein the support layer has an elongation at break of strictly less than 100% and is based on acrylic polymers, polyethylene (PE), oriented, non-oriented or bi-oriented polypropylene (PP), polyimide, polyurethane, polyester or paper.

14. A product to the surface of which has been affixed the self-adhesive article as defined in claim 11 , said surface having a surface energy less than or equal to 40 mN/m, said surface energy being measured at 23° C., 50% relative humidity, atmospheric pressure of 1 bar, in air.