Two-part curable composition

1. A two-part curable composition comprising:

a first part (component A) comprising:

at least 51% by weight, based on the total weight of the first part, of one or more cyanoacrylate monomer(s);

a transition metal complex; and

an antioxidant; and

a second part (component B) comprising:

a per-compound;

at least one Michael acceptor M selected from the group consisting of (meth)acrylic monomers, (meth)acrylic functionalized oligomers, (meth)acrylic functionalized resins, and mixtures thereof;

optionally an acid scavenger AS compound selected from the group consisting of the sterically hindered bases;

wherein:

the composition comprises (in the first part and/or in the second part) at least one compound C comprising a radical -EWG 1 -CH 2 -EWG 2 - wherein EWG 2 and EWG 1 are each, independently of each other, an electron withdrawing group; and

the first part of the composition does not comprise a per-compound.

2. The two-part curable composition according to claim 1 , wherein the cyanoacrylate monomer has the general formula (I):

wherein R is selected from the group consisting of C 1 -C 18 linear or branched alkyl, C 3 -C 20 alkoxyalkyl, trimethylsilylated C 1 -C 3 alkyl, furfuryl, allyl, cyclohexyl, and a group having the following formula: —R i —O—C(O)—C(R j )═CH 2 with R i being an organic moiety, and R j being H or CH 3 .

3. The two-part curable composition according to claim 2 , wherein cyanoacrylate monomer has the formula (I) wherein R has the general formula (II):

wherein R 1 =CH 3 or H, R 2 =C 1 -C 4 linear or branched alkyl, and m ranges from 1 to 3.

4. The two-part curable composition according to claim 1 , wherein the total content of cyanoacrylate monomer(s) in the first part is higher than 60% by weight, based on the total weight of the first part.

5. The two-part curable composition according to claim 1 , wherein the first part of the composition comprises at least 20% by weight of at least one cyanoacrylate monomer comprising a group —X—O—R b wherein X is a linear or branched alkylene radical optionally interrupted with one or several oxygen atom(s), and R b is an alkyl group, based on the total weight of the first part of the composition.

6. The two-part curable composition according to claim 1 , wherein the transition metal in the transition metal complex is copper.

7. The two-part curable composition according to claim 1 , wherein the transition metal complex is selected from copper (II) tetrafluoroborate and copper (I) tetrakis (acetonitrile) tetrafluoroborate.

8. The two-part curable composition according to claim 1 , wherein the antioxidant is selected from the group consisting of: methylenebis(4-methyl-6-tert-butylphenol), hydroxyanisole butyl ether, 4-methyl-2,6-di-tert-butylphenol, hydroquinone monomethyl ether, tert-butylhydroquinone, and mixtures thereof.

9. The two-part curable composition according to claim 1 , wherein the (meth)acrylic monomer is chosen from the group consisting of:

i) a compound of general formula (III):

CH 2 ═CR 3 (CO 2 R 4 )  (III),

wherein R 3 represents methyl or H, and R 4 is a hydrogen atom, a C 1 -C 8 linear or branched alkyl, a C 2 -C 6 linear or branched alkoxyalkyl, a furfuryl or a isobornyl group;

ii) a compound having one of the formulae (IV) to (VI):

wherein R 5 is H or Me, and p is an integer ranging from 1 to 6; or

wherein R 6 is CO 2 R 4 , where R 7 is H or Me;

iii) a compound selected from the group consisting of: butanediol di(meth)acrylate, hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethyleneglycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, neopentylglycol diacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, bisphenol-A-diacrylate, bisphenol-A-dimethacrylate, ethoxylated bisphenol-A-diacrylate, propoxylated bisphenol-A-diacrylate, and mixtures thereof; and

iv) mixtures thereof.

10. The two-part curable composition according to claim 1 , wherein the second part of the composition comprises more than 30% by weight of Michael acceptor M, based on the total weight of the second part.

11. The two-part curable composition according to claim 1 , wherein the Michael acceptor M is the compound C comprising a radical -EWG 1 -CH 2 -EWG 2 - wherein EWG 2 and EWG 1 are each, independently of each other, an electron withdrawing group.

12. The two-part curable composition according to claim 1 , wherein the per-compound is a perester, perborate, persulfate, peracetal, or peroxide.

13. The two-part curable composition according to claim 1 , wherein the first and/or the second part of the composition further contains at least one additive selected from the group consisting of: a thixotropic agent, a thickening agent, a toughening agent, an accelerating agent, an adhesion promoter, a pigment, a colorant, a stabilizing agent, a plasticizer, and mixtures thereof.

14. The two-part curable composition according to claim 1 , wherein the volume ratio first part:second part ranges from 1:1 to 10:1.

15. The two-part curable composition according to claim 1 , wherein EWG 2 and EWG 1 are each, independently of each other, an electron withdrawing group selected from the group consisting of nitrile (CN), carbonyl (COR′), ester (CO 2 R′), nitro (NO 2 ), halogens (F, Cl), trifluoromethyl (CF 3 ), sulfonyl (SO 3 R′), wherein R′ is an alkyl group.

16. The two-part curable composition according to claim 1 , wherein the compound C comprising a radical -EWG 1 -CH 2 -EWG 2 - is chosen from the group consisting of:

a compound having one of the formulae (IV) to (VI):

wherein R 5 is H or Me, and p is an integer ranging from 1 to 6; or

wherein R 6 is CO 2 R 4 , R 4 is a hydrogen atom, a C 1 -C 8 linear or branched alkyl, a C 2 -C 6 linear or branched alkoxyalkyl, a furfuryl or an isobornyl group, and R 7 is H or Me;

homopolymers of the compounds of formulae (IV) to (VI); and

copolymers resulting from the polymerisation of at least one compound of formulae (IV) to (VI) with other (meth)acrylic monomer(s).

17. The two-part curable composition according to claim 1 , selected from the following compositions:

1) a two-part curable composition comprising:

a first part (component A) comprising:

at least 70% by weight, based on the total weight of the first part, of one or more cyanoacrylate monomer(s);

from 0% to 5% of thixotropic agent;

from 0% to 5% of a thickening agent;

from 0.001% to 0.2% of stabilizing agent(s);

from 0.01% to 1% by weight of antioxidant(s);

from 0.001% to 1% by weight of transition metal complex(s);

a second part (component B) comprising:

at least 40% by weight of at least one Michael acceptor M selected from the group consisting of (meth)acrylic monomers, (meth)acrylic functionalized oligomers, (meth)acrylic functionalized resins, and mixtures thereof,

from 0.1% to 20% by weight of per compound(s) based on the total weight of the second part;

from 0% to 5% of thixotropic agent(s);

from 0%-0.05% of an acid scavenger compound AS selected from sterically hindered bases;

wherein the Michael acceptor comprises a radical -EWG 1 -CH 2 -EWG 2 - wherein EWG 2 and EWG 1 are each, independently of each other, an electron withdrawing group, and the first part is deprived of a per-compound;

2) a two-part curable composition comprising:

a first part (component A) comprising:

at least 70% by weight, based on the total weight of the first part, of one or more cyanoacrylate monomer(s);

from 0% to 5% of thixotropic agent;

from 0% to 5% of a thickening agent;

from 0.001% to 0.2% of stabilizing agent(s);

from 0.01% to 1% by weight of antioxidant(s);

from 0.001% to 1% by weight of transition metal complex(es); and

from 1% to 30% by weight of a compound C comprising a radical -EWG 1 -CH 2 -EWG 2 - wherein EWG 2 and EWG 1 are each, independently of each other, an electron withdrawing group; and

wherein the first part is deprived of a per-compound;

a second part (component B) comprising:

at least 40% by weight of at least one Michael acceptor M selected from the group consisting of (meth)acrylic monomers, (meth)acrylic functionalized oligomers, (meth)acrylic functionalized resins, and mixtures thereof,

from 0.1% to 20% by weight of per compound(s) based on the total weight of the second part;

from 0% to 5% of thixotropic agent(s), and

from 0% to 0.05% of an acid scavenger compound AS selected from sterically hindered bases.

18. A syringe or cartridge or dispense head comprising the two-part curable composition of claim 1 .

19. A method for bonding substrates comprising the steps of:

applying the two-part curable composition of claim 1 to at least one of the substrates,

mating together the substrates for a time sufficient to permit an adhesive bond to form between the mated substrates; and

optionally heating the mated substrates to a temperature higher than 100° C.