Alkoxysilane terminated prepolymers
Alkoxysilyl-terminated preopolymers prepared by reacting an alkoxysilane with a prepolymer prepared by reacting a di- or polyisocyanate with both a low molecular weight diol or polyol and a high molecular weight polyol, the respective polyol components present within a specific ratio range, and giving rise to an increased content of urethane groups, and an inhomogenous distribution thereof exhibit high tensile strength and elongation, even without the use of fillers.
1 .- 11 . (canceled)
12 . A room temperature-curing composition (M) which is not solid in the uncrosslinked state, comprising prepolymer(s) (A) having end groups of the formula [1]
−SiR 1 a (OR 2 ) 3-a [1]
where
R 1 is an optionally halogen-substituted alkyl, cycloalkyl, alkenyl or aryl radical having up to 10 carbon atoms,
R 2 is an alkyl radical having 1-6 carbon atoms or an ω-oxaalkyl-alkyl radical having in all 2-10 carbon atoms, and
a is a number from 0 to 2,
the prepolymers (A) prepared by reacting the components
1) at least one polyol (Al) having an average molecular weight Mn of 1000 to 25,000,
2) at least one low molecular weight diol (A2) having at least two hydroxyl groups per molecule and a molecular weight of 62 to 300,
3) at least one di- or polyisocyanate (A3), and
4) at least one alkoxysilane (A4) possessing an isocyanate group or an isocyanate-reactive group,
the low molecular weight alcohol (A2) component and the polyol (A1) component being used in a molar ratio of 0.3:1 to 7:1, and
the stoichiometry and reaction conditions being selected such that more than 80% of the chain ends of the prepolymers (A) are terminated with alkoxysilyl groups.
13 . The prepolymer (A) of claim 12 , which is isocyanate-free.
14 . The prepolymer (A) of claim 12 , in which the alkoxysilane-terminated polymer (A) possesses end groups of the general formula [2]
-A-CH 2 —SiR 1 a (OR 2 ) 3-a [2]
where
A is a divalent linking group selected from the group consisting of —O—, —S—, —(R 3 )N—, —O—CO—N(R 3 )—, —N(R 3 )—CO—O—, —NH—CO—NH—, —N(R 4 )—CO—NH—, —NH—CO—N(R 4 )—, and —N(R 4 )—CO—N(R 4 )—,
R 3 is hydrogen, an optionally halogen-substituted cyclic, linear or branched C 1 to C 18 alkyl radical or alkenyl radical or a C 6 to C 18 aryl radical,
R 4 is an optionally halogen-substituted cyclic, linear or branched C 1 to C 18 alkyl radical or alkenyl radical or a C 6 to C 18 aryl radical.
15 . The prepolymer (A) of claim 12 in which the polyols (A1) are hydroxyl-functional polymers selected from the group consisting of polyesters, polyacrylates, polymethacrylates, polycarbonates, polystyrenes, polysiloxanes, polyamides, polyvinyl esters, polyvinyl hydroxides and polyolefins.
16 . The prepolymer (A) of claim 12 , in which the low molecular weight alcohols (A2) are selected from the group consisting of 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, pentanediols and hexanediols, ethylene glycol and propylene glycol.
17 . The prepolymer (A) of claim 12 , in which the di- or polyisocyanates (A3) are selected from the group consisting of diisocyanatodiphenylmethane, tolylene diisocyanate, diisocyanatonaphthalene, isophorone diisocyanate, perhydrogenated MDI, hexamethylene diisocyanate, polymeric MDI, triphenylmethane triisocyanate, isocyanurate triisocyanates and biuret triisocyanates.
18 . The prepolymer of claim 12 , in which the alkoxysilanes (A4) are selected from silanes of the formulae [4] and [5]
where
B 1 is an OH, SH or NH 2 group or a group HR 4 N wherein
R 4 is an optionally halogen-substituted cyclic, linear or branched C 1 to C 18 alkyl radical or alkenyl radical or a C 6 to C 18 aryl radical.
19 . A moisture curable composition (M) comprising a prepolymer of claim 12 .
20 . The composition (M) of claim 19 , further comprising at least one filler (E) selected from the group consisting of calcium carbonate, silica, and carbon black.
21 . The composition (M) of claim 19 , which is devoid of fillers (E).
22 . The composition (M) of claim 12 , containing 0-20% by volume of an organic solvent (F).
23 . The composition of claim 12 , further comprising at least one alkoxysilane of the formula
wherein B 2 is selected from the group consisting of R 4 O—CO—NH, R 4 R 3 N—CO—NH, OH, OR 4 , SH, SR 4 , NH 2 , NHR 4 , or N(R 4 ) 2 .
24 . The composition of claim 12 , wherein the molar ratio of low molecular weight polyol (A2) to polyol (A1) is from 0.7:1 to 3:1.
25 . The composition of claim 12 which is substantially free of water.
26 . The composition of claim 19 , further comprising at least one alkoxysilane of the formula
wherein B 2 is selected from the group consisting of R 4 O—CO—NH, R 4 R 3 N—CO—NH, OH, OR 4 , SH, SR 4 , NH 2 , NHR 4 , or N(R 4 ) 2 .
27 . The composition of claim 19 , wherein the molar ratio of low molecular weight polyol (A2) to polyol (A1) is from 0.7:1 to 3:1.
28 . The composition of claim 19 which is substantially free of water.