Method for preparing a mixed silane-terminated polymer

1. A process for preparing a mixed silane-terminated polymer by reacting a polyol component A) with a diisocyanate component B) comprising isophorone diisocyanate, with at least one isocyanatosilane C) and with an aminosilane E), in which a urethanization reaction is carried out in the presence of at least one catalyst D) which is free of organically bonded tin,

wherein the process is conducted so that

first, some of the hydroxyl groups of the polyol component A) are reacted with the diisocyanate component B) and, after reaching a predetermined NCO content, in a second step the aminosilane is added and reacted with free NCO groups of an OH- and NCO-functional prepolymer obtained in the first step, wherein the aminosilane is added in such an amount that no free NCO groups are detectable in a reaction mixture any longer, and still-free hydroxyl groups of a reaction product are then finally reacted with the isocyanatosilane C),

wherein the catalyst D) comprises:

an organometallic compound of magnesium, zinc, gallium, scandium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, yttrium or lutetium, an organometallic compound being understood to be a compound which has at least one ligand bonded to the above mentioned metals via an oxygen atom, and the ligands being selected from the group consisting of alkoxy group, sulfonate group, carboxylate group, dialkylphosphate group, dialkylpyrophosphate group and β-diketonate group, where all ligands may be identical or different from each other,

or mixtures of the above mentioned compounds.

2. The process as claimed in claim 1 ,

wherein the catalyst D) comprises:

a beta-diketonate compound of magnesium, zinc, gallium, scandium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, yttrium or lutetium,

a zinc carboxylate,

or mixtures of the above mentioned compounds.

3. A process for preparing a mixed silane-terminated polymer by reacting a polyol component A) with a diisocyanate component B) comprising isophorone diisocyanate, with at least one isocyanatosilane C) and with an aminosilane E), in which the urethanization reaction is carried out in the presence of at least one catalyst D) which is free of organically bonded tin,

wherein the process is conducted so that

i) the hydroxyl groups of the polyol component A) are reacted simultaneously with the diisocyanate component B) and at least one isocyanatosilane C) in the presence of a catalyst D) and in a second reaction step, free NCO groups of a reaction product are then reacted with an aminosilane E),

or

ii) the isocyanatosilane C) is reacted with some of the hydroxyl groups of the polyol component A) and in a second step still-free hydroxyl groups of the polymer are then reacted with the diisocyanate component B) and then, an aminosilane E) is added and reacted with free NCO groups of the prepolymer obtained, wherein the aminosilane is added in such an amount that no free NCO groups are detectable in a reaction mixture any longer,

wherein the catalyst D) consists of:

an organometallic compound consisting of gallium, scandium, lanthanum, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, yttrium or lutetium, an organometallic compound being understood to be a compound which has at least one ligand bonded to the above mentioned metals via an oxygen atom, and the ligands being selected from the group consisting of alkoxy group, sulfonate group, carboxylate group, dialkylphosphate group, dialkylpyrophosphate group and β-diketonate group, where all ligands may be identical or different from each other,

or mixtures of the above mentioned compounds,

wherein the sole use of ytterbium(III) acetylacetonate as catalyst D) is excluded.

4. The process as claimed in claim 3 , wherein the catalyst D) consists of:

a beta-diketonate compound of magnesium, zinc, gallium, scandium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, yttrium or lutetium,

a zinc carboxylate,

or mixtures of the above mentioned compounds,

wherein the sole use of ytterbium(III) acetylacetonate as catalyst D) is excluded.

5. The process as claimed in claim 3 , wherein the polyol component A) is a polyether polyol having a number-average molecular weight in a range from 3000 to 24 000 g/mol.

6. The process as claimed in claim 3 , wherein the polyol component A) is a polyether polyol based on polypropylene oxide.

7. The process as claimed in claim 3 , wherein the isocyanate component B) contains exclusively isophorone diisocyanate.

8. The process as claimed in claim 3 , wherein the isocyanatosilane C) is a compound of the formula (II)

in which

R 1 , R 2 and R 3 independently of one another are identical or different saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic radicals which have up to 18 carbon atoms and may optionally contain up to 3 heteroatoms from the group of oxygen, sulfur, nitrogen, and

X is a linear or branched organic radical having up to 6 carbon atoms.

9. The process as claimed in claim 3 , wherein the isocyanatosilane C) used is 3-isocyanatopropyltrimethoxysilane.

10. The process as claimed in claim 3 , wherein the aminosilane E) is a compound of the formula (VIII)

in which R 1 , R 2 , and R 3 independently of one another are identical or different saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic radicals which have up to 18 carbon atoms and may optionally contain up to 3 heteroatoms from the group of oxygen, sulfur, nitrogen, and

X is a linear or branched organic radical having up to 6 carbon atoms

and

R 10 is hydrogen, a saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or an optionally substituted aromatic or araliphatic radical having up to 18 carbon atoms or a radical of the formula

in which R 1 , R 2 , R 3 and X have the definition given above.

11. The process as claimed in claim 3 , wherein the aminosilane E) is a compound of the formula (IX)

in which

R 1 , R 2 and R 3 independently of one another are identical or different saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic radicals which have up to 18 carbon atoms and may optionally contain up to 3 heteroatoms from the group of oxygen, sulfur, nitrogen, and

X is a linear or branched organic radical having at least 2 carbon atoms and

R 11 and R 12 independently of one another are saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or aromatic organic radicals which have 1 to 18 carbon atoms, are substituted or unsubstituted and/or have heteroatoms in the chain.

12. The process as claimed in claim 3 , wherein the amount of aminosilane E) is chosen such that there are 0.9 to 1.2 amino groups for each isocyanate group of an isocyanate- and silane-functional polymer formed in the process.

13. The process as claimed in claim 3 , wherein the molar amount of the isocyanatosilane C) used is in the range from 1 to 50 mol %, preferably in the range from 5 to 28 mol %, particularly preferably in the range from 10 to 28 mol %, very particularly preferably in the range from 10 to 25 mol %, and the molar amount of the diisocyanate B) used is accordingly in the range from 50 to 99 mol %, preferably in the range from 72 to 95 mol %, particularly preferably in the range from 72 to 90 mol %, very particularly preferably in the range from 75 to 90 mol %, based on the number of hydroxyl groups of polyol A).