Self-adhesive composition for bonding substrates with low surface energy

1. A self-adhesive article comprising an adhesive layer consisting of a crosslinked adhesive composition comprising:

A) at least one polysilylated polymer having a number-average molar mass (Mn) of at least 20000 g/mol, wherein the at least one polysilylated polymer comprises a polyether and/or polyurethane main chain and at least two hydrolysable silylated end groups, said silylated end groups being attached to the main chain of the polymer by a urethane or ether function (referred to as a connector group),

B) a tackifying resin mixture comprising at least one type (i) and (ii) tackifying resin, wherein each resin has a hydroxyl number less than or equal to 50 and wherein type (i) and type (ii) tackifying resins are defined as follows:

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

ii. resins obtained by a process comprising the polymerization of pure alpha-methyl styrene monomers; and

C) at least one crosslinking catalyst,

D) excluding any monosilylated polymer.

2. The self-adhesive article according to claim 1 , wherein the at least one polysilylated polymer(s) A) correspond(s) to the following formula:

formula (I):

wherein:

B represents a divalent hydrocarbonated radical (for f=2) or trivalent (for f=3) comprising 2 to 66 carbon atoms, linear, branched, cyclic, alicyclic or aromatic, saturated or unsaturated, 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 from 1 to 4 carbon atoms, R 4 which can optionally be engaged in a ring,

n″ is a non-zero integer whereby 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 numbers n″ and f are such that the number-average molecular mass of the at least one polysilylated polymer(s) A) is as defined in claim 1 .

3. The self-adhesive article according to claim 2 , wherein the polysilylated polymer(s) A) is (are) disilylated (f=2).

4. The self-adhesive article according to claim 1 , wherein the at least one polysilylated polymer(s) A) correspond(s) to the following formula:

formula (II):

wherein:

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

R 1 represents a divalent hydrocarbonated radical comprising from 5 to 15 carbon atoms which can be aromatic or aliphatic, 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 from 1 to 4 carbon atoms, R 4 which can optionally be engaged in a ring,

n is a non-zero integer wherein 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 wherein the number-average molecular mass of the polyether block of formula —[OR′ 2 ] n —ranges from 0 to 20000 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

indices m, n, n′ and f are such that the number-average molecular mass of the polysilylated polymer(s) A) is as defined in claim 1 .

5. The self-adhesive article according to claim 4 , wherein m is non-zero.

6. The self-adhesive article according to claim 1 , wherein the at least one polysilylated polymer(s) A) is a mixture of polysilylated polymer(s) comprising at least one polysilylated polymer corresponding to the formula (I) or the formula (II) and/or at least one polysilylated polymer corresponding to the formula (I) or the formula (II), wherein formula (I) and formula (II) are defined as follows:

formula (I):

wherein:

B represents a divalent hydrocarbonated radical (for f=2) or trivalent (for f=3) comprising 2 to 66 carbon atoms, linear, branched, cyclic, alicyclic or aromatic, saturated or unsaturated, 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 from 1 to 4 carbon atoms, R 4 which can optionally be engaged in a ring,

n″ is a non-zero integer wherein 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 numbers n″ and f are such that the number-average molecular mass of the polysilylated polymer(s) A) is as defined in claim 1 ; and

formula (II):

wherein:

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

R 1 represents a divalent hydrocarbonated radical comprising from 5 to 15 carbon atoms which can be aromatic or aliphatic, 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 from 1 to 4 carbon atoms, R 4 which can optionally be engaged in a ring,

n is a non-zero integer wherein 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 wherein the number-average molecular mass of the polyether block of formula —[OR′ 2 ] n -ranges from 0 to 20000 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

indices m, n, n′ and f are such that the number-average molecular mass of the polysilylated polymer(s) A) is as defined in claim 1 .

7. The self-adhesive article according to claim 6 , wherein the polysilylated polymer(s) A) is a mixture of polysilylated polymer(s) comprising at least one polysilylated polymer corresponding to the formula (I) or the formula (II), wherein p=0 and/or at least one polysilylated polymer corresponding to the formula (I) or the formula (II), wherein p=1.

8. The adhesive composition as defined in claim 6 , comprising:

A) at least 20% by weight of the at least one polysilylated polymer A) corresponding to one of formulae (I) or (II) or mixture thereof,

B) at least 15% by weight of the tackifying resin mixture,

C) at least 0.2% by weight of the at least one crosslinking catalyst, wherein the % by weight contents are based on the total weight of the adhesive composition, and the sum of the contents of all the ingredients of the adhesive composition are equal to 100%.

9. The composition of claim 8 , wherein:

the content of the polysilylated polymer(s) A) ranges from 20 to 84.8% by weight, of the weight of the adhesive composition,

the content of the tackifying resin mixture B) represents from 15 to 79.8% by weight, of the weight of the adhesive composition, and

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

10. The self-adhesive article according to claim 1 , wherein the number-average molecular mass of the polysilylated polymer(s) A) ranges from 20,000 to 55,000 g/mol.

11. The self-adhesive article according to claim 1 , further comprising a support layer coated with the self-adhesive layer, 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.

12. A product coated at its surface with the self-adhesive article of claim 1 , said surface having a surface energy of less than or equal to 40 mN/m, said surface energy being measured at 23° C., at 50% relative humidity, at atmospheric pressure of 1 bar, in air.

13. A self-adhesive article comprising an adhesive layer consisting of a crosslinked adhesive composition comprising:

E) at least one polysilylated polymer having a number-average molar mass (Mn) of at least 20000 g/mol, wherein the at least one polysilylated polymer comprises a polyether and/or polyurethane main chain and at least two hydrolysable silylated end groups, said silylated end groups being attached to the main chain of the polymer by a urethane or ether function (referred to as a connector group),

F) a tackifying resin mixture comprising at least one type (i) and (ii) tackifying resin, wherein each resin has a hydroxyl number less than or equal to 50 and wherein type (i) and type (ii) tackifying resins are defined as follows:

i. one or more resins selected from the group consisting of PICCO AR-100, PICCO AR-85, NORSOLENE M1090, and PICCO A-10; and

ii. one or more resins selected from the group consisting of NORSOLENE W110 and NOROSLENE W85; and

G) at least one crosslinking catalyst,

H) excluding any monosilylated polymer.

14. A process for coating a substrate using the self-adhesive article according to claim 1 , wherein the substrate has a surface energy measured at 23° C., at 50% relative humidity, at atmospheric pressure of 1 bar, in air, less than or equal to 40 mN/m, the adhesion strength of the self-adhesive article on said substrate measured by peeling at 180° being at least 4N.