PROCESS FOR PREPARING SILYLATED IONIC COPOLYURETHANES WITH IMPROVED ELASTICITY

1 . Process for preparing a composition of ionic silylated copolyurethanes comprising two ureido-alkylene-alkoxysilane end groups, said process comprising successively:

a step (i) of forming a composition of copolyurethanes having —NCO end groups by carrying out a polyaddition reaction between:

a polyisocyanate (A) of formula (iA):

OCN—R 1 —NCO   (iA)

 in which R 1 represents a divalent hydrocarbon radical comprising from 5 to 45 carbon atoms and which may be aromatic or aliphatic, linear, branched or cyclic, and may include at least one heteroatom selected from the group consisting of O, S and N;

a composition (B) of polyols comprising:

at least one polyol (B1) with a number-average molecular mass (Mn) of greater than or equal to 2500 g/mol; and

at least one polyol (B2) with a number-average molecular mass (Mn) of less than 2500 g/mol; and

a carboxylic diol (C) of formula (iC):

in which:

R 0 represents a hydrogen atom or an alkyl radical comprising from 1 to 18 carbon atoms;

x and y, which may be identical or different, are integers ranging from 1 to 8; and

z is an integer ranging from 0 to 8; then

a step (ii) of reacting the composition of copolyurethanes formed in step (i) with an amine (D) of formula (iiD):

N(R)(R′R″)   (iiD)

in which:

R, R′ and R″, which may be identical or different, each represent a saturated, unsaturated or aromatic hydrocarbon radical, optionally comprising a heteroatom selected from the group consisting of N, O and S;

R, R′ and R″ furthermore being such that said tertiary amine (D) is a linear, branched or cyclic amine or polyamine the number-average molar mass Mn of which ranges from 59 to 6000 g/mol and which has a pKa of greater than 8; then

a step (iii) of reacting the composition of copolyurethanes having —NCO end groups formed in step (ii) with an aminosilane (E) derived from a secondary amine, of formula (iiiE):

in which:

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

R 4 represents a linear or branched alkyl radical comprising from 1 to 4 carbon atoms;

R 5 represents a linear or branched alkyl radical comprising from 1 to 4 carbon atoms, an alkylcarbonyl radical comprising from 2 to 8 carbon atoms, or a dialkylimino radical comprising from 3 to 8 carbon atoms; and

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

R 6 represents a phenyl radical, a linear, branched or cyclic alkyl radical comprising from 1 to 6 carbon atoms, or a radical selected from the group consisting of the radicals:

of formula (IIc):

of formula (IId):

of formula (IIe):

 in which R 7 is a linear or branched alkyl radical comprising from 1 to 6 carbon atoms;

of formula (IIf):

—CH 2 —COO − , HN + (R)(R′)(R″)   (IIf); and

of formula (IIg):

—CH 2 —CH 2 —COO − , HN + (R)(R′)(R″)   (IIg)

 in which R, R′ and R″ are as defined above.

2 . The process according to claim 1 , characterized in that the radical R 1 of the polyisocyanate (A) used in step (i) is chosen from:

a) the divalent radical derived from isophorone diisocyanate (IPDI):

b) the divalent radical derived from dicyclohexylmethane 4,4′- and 2,4′-diisocyanate (HMDI):

c) the radical derived from toluene 2,4- and 2,6-diisocyanate (TDI):

d) the radical derived from diphenylmethane 4,4′- and 2,4′-diisocyanate (MDI):

e) the radical derived from m-xylylene diisocyanate (m-XDI):

f) the radical derived from hexamethylene diisocyanate (HDI):

—(CH 2 ) 6 —

g) the divalent group derived from a hexamethylene diisocyanate (HDI) allophanate of formula (iA′):

in which:

i is an integer ranging from 2 to 5;

j is an integer ranging from 1 to 2;

R 11 represents a saturated or unsaturated, cyclic or acyclic, linear or branched hydrocarbon radical comprising from 6 to 14 carbon atoms;

R 12 represents a divalent propylene group;

i, j, R 11 and R 12 being such that the hexamethylene diisocyanate allophanate corresponding to the formula (iA′) comprises a content of isocyanate groups NCO ranging from 12% to 14% by weight, relative to the weight of said allophanate.

3 . The process according to claim 1 , characterized in that the number-average molecular mass Mn of the polyol (B1) included in the composition (B) used in step (i) is within a range extending from 2500 g/mol to 20000 g/mol and/or the number-average molecular mass Mn of the polyol (B2) included in the composition (B) used in step (i) is within a range extending from 200 to 2250 g/mol.

4 . The process according to claim 1 , characterized in that the polyol composition (B) comprises from 10 mol % to 35 mol % of the polyol (B1) and from 65 mol % to 90 mol % of the polyol (B2), said mole percentages being expressed on the basis of the total number of moles of (B1) and (B2) present in the composition (B).

5 . The process according to claim 1 , characterized in that the polyol composition (B) comprises, besides the polyol (B1), two polyols (B2) chosen, respectively, from:

a first polyol (B2-1) having a number-average molecular mass Mn of greater than or equal to 1250 g/mol and less than 2500 g/mol, and

a second polyol (B2-2) with a number-average molecular mass (Mn) ranging from 200 g/mol to 1000 g/mol.

6 . The process according to claim 1 , characterized in that the polyols included in the composition (B) have a hydroxyl functionality equal to 2.

7 . The process according to claim 1 , characterized in that the polyols included in the composition (B) are polyether diols.

8 . The process according to claim 1 , characterized in that the carboxylic diol (C) used in step (i) has the formula (iC) in which:

R 0 represents an alkyl radical comprising from 1 to 4 carbon atoms, preferably a methyl, ethyl or n-propyl radical, even more preferentially a methyl radical;

x and y are identical and equal to 1; and/or

z is equal to 0.

9 . The process according to claim 1 , characterized in that the tertiary amine (D) used in step (ii) is selected from the group consisting of:

a polyethyleneimine,

a polypropyleneimine,

triethylamine,

1,8-diazabicyclo[5.4.0]undec-7-ene (or DBU) having the structural formula:

1,4-diazabicyclo[2.2.2]octane (or DABCO), having the structural formula:

1,5-diazabicyclo[4.3.0]non-5-ene (or DBN), having the structural formula:

N,N-dicyclohexylmethylamine (or DCHMA); and

trihexylamine (or THA).

10 . The process according to claim 1 , characterized in that the aminosilane (E) used in step (iii) has the formula (iiiE) in which:

R 3 represents the methylene or n-propylene radical;

R 4 and R 5 , which may be identical or different, each represent the methyl or ethyl radical;

p is equal to 0; and/or

R 6 represents a linear alkyl radical comprising from 1 to 4 carbon atoms or a radical of formula (IIc) in which R 7 is an alkyl radical comprising from 1 to 3 carbon atoms.

11 . The process according to claim 1 , characterized in that it is carried out in the presence of a plasticizing agent and/or a solvent that is not water.

12 . Composition of ionic silylated copolyurethanes comprising two ureido-alkylene-alkoxysilane end groups, said composition being able to be obtained by means of the preparation process as defined in claim 1 .

13 . Crosslinkable adhesive and/or sealant composition comprising:

at least one composition of ionic silylated copolyurethanes having ureido-alkylene-alkoxysilane end groups as defined in claim 12 , and

at least one filler.

14 . Article comprising the crosslinkable adhesive and/or sealant composition as defined in claim 13 , in a hermetic packaging protected from air.

15 . Process for assembling two substrates, comprising:

coating the crosslinkable adhesive and/or sealant composition as defined in claim 13 , at ambient temperature, in the form of a layer of a thickness between 0.2 and 5 mm, onto at least one of the two substrates to be assembled; then

effectively bringing the two substrates into contact.