Low-viscosity crosslinkers containing alkoxysilane groups

A composition, comprising:

• at least one crosslinker of formula (I) or a mixture comprising at least two of the crosslinkers of formula (I)
• wherein R1 and R2 are each independently selected from the group consisting of H, —(CH2)rR4, with r=0 to 12, —OR5, and —NHR5,
• w r R a d R5 ar ac d p d tly s l ct d from t group co s st g of H, a alkyl group optionally containing a heteroatom, and having 1 to 18 carbon atoms, a cycloalkyl group optionally containing a heteroatom, and having 3 to 18 carbon atoms, an alkylaryl group optionally containing a heteroatom, and having 6 to 18 carbon atoms, a bivalent alkylene group having 1 to 10 carbon atoms, an alkylene oxide group having at least 4 carbon atoms, a polyether group, a polyhydroxy-functional group having 1 to 18 carbon atoms, a heteroaromatic group containing —O— and/or —N— and having 5 to 18 carbon atoms and an —O— or —NH-polyether group containing one or more different polyglycol units (CH2CH2O)pR″, wherein p is 4 to 20 and R″ is an alkyl radical having 1 to 18 carbon atoms or H, and
• wherein each G1 is a group of formula (IIa)
• —(C═O)—NH—R—Si(OR∝)3 (IIa),
• wherein R in formula (IIa) is independently an aliphatic (cyclo)alkylene radical having 1 to 10 carbon atoms, and R′ in formula (IIa) in each case independently represents a linear, branched or cyclic alkyl radical having 1 to 10 carbon atoms.

A process for preparing a composition comprising a crosslinker of formula (I) or a mixture comprising at least two of the crosslinkers of formula (I), said process comprising:

• (i) reacting
• at least one isocyanatoalkylalkoxysilane of formula (II) or a mixture of at least two of the isocyanatoalkylalkoxysilanes of formula (II),
• (R′O)3Si—R—N═C═O (II),
• wherein R is in each case independently an aliphatic (cyclo)alkylene radical having 1 to 10 carbon atoms, and R′ in each case independently represents a linear, branched or cyclic alkyl radical having 1 to 10 carbon atoms,
• with an organofunctional C—H-acidic compound of formula (III) having at least two acidic hydrogen atoms,
• wherein R1 and R2 are each independently selected from the group consisting of H, —(CH2)rR4, with r=0 to 12, —OR5 and —NHR5, wherein R4 and R5 are each independently selected from the group consisting of H, an alkyl group optionally containing a heteroatom, and having 1 to 18 carbon atoms, a cycloalkyl group optionally containing a heteroatom, and having 3 to 18 carbon atoms, an alkylaryl group optionally containing a heteroatom, and having 6 to 18 carbon atoms, a bivalent alkylene group having 1 to 10 carbon atoms, an alkylene oxide group having at least 4 carbon atoms, a polyether group, a polyhydroxy-functional group having 1 to 18 carbon atoms, a heteroaromatic group containing —O— and/or —N— and having 5 to 18 carbon atoms and an —O— or —NH-polyether group containing one or more different polyglycol units (CH2CH2O)pR″, wherein p is 4 to 20 and R″ is an alkyl radical having 1 to 18 carbon atoms or H.