Polymer compositions based on alkoxysilane-terminated polymers with adjustable cure rate
Condensation curable systems employ ordinarily highly reactive polymers bearing methylene-linked alkoxysilyl groups. By limiting the amounts of activating compounds during the preparation of such polymers, the reactivity is sharply decreased, yet can be increased by addition of suitable catalysts. As a result, the polymers may be easily processed, yet the moisture curing times may be adjusted readily.
1. A polymer composition comprising at least one alkoxysilane-terminated polymer (P) bearing end group(s) (1) of the general formula
-A-CH 2 —SiR 1 a (OR 2 ) 3-a (1)
where
A each independently is a divalent linking group selected from the group consisting of —O—CO—N(R 3 )—, —N(R 3 )—CO—O—, —N(R 3 )—CO—NH—, —NH—CO—N(R 3 )— and —N(R 3 )—CO—N(R 3 ),
R 1 each independently is an unsubstituted or halogen-substituted alkyl, cycloalkyl, alkenyl or aryl radical having 1-10 carbon atoms,
R 2 each independently is an alkyl radical having 1-6 carbon atoms or an ω-oxaalkyl-alkyl radical having in total 2-10 carbon atoms,
R 3 each independently is hydrogen, an unsubstituted or halogen-substituted cyclic, linear or branched C 1 to C 18 alkyl or alkenyl radical or a C 6 to C 18 aryl radical, and
a is an integer from 0 to 2, where
a) the polymer compositions exhibit skin formation times >40 minutes at 23° C. and 50% relatively atmospheric humidity, and
b) the skin formation times of the polymer compositions can be reduced to <20 minutes by the addition of a catalyst (K) at concentrations of up to 3% by weight
wherein the polymer(s) (P) are obtained by reaction employing an aminosilane (A1) of the formula (2)
NH(R 3 )—CH 2 —SiR 1 a (OR 2 ) 3-a (2)
where
R 3 is a C 6 to C 18 aryl radical,
further containing 0.001%-3% by weight of a sterically hindered aliphatic amine.
2. The polymer composition of claim 1 , wherein the sterically hindered aliphatic amine is an N-alkylated morpholine derivative.
3. A polymer composition comprising at least one alkoxysilane-terminated polymer (P) bearing end group(s) (1) of the general formula
-A-CH 2 —SiR 1 a (OR 2 ) 3-a (1)
where
A each independently is a —O—CO—N(R 3 )—, —N(R 3 )—CO—O—, or —N(R 3 )—CO—N(R 4 )— divalent linking group,
R 1 each independently is an unsubstituted or halogen-substituted alkyl, cycloalkyl, alkenyl or aryl radical having 1-10 carbon atoms,
R 2 each independently is an alkyl radical having 1-6 carbon atoms or an ω-oxaalkyl-alkyl radical having in total 2-10 carbon atoms,
R 3 each independently is hydrogen, an unsubstituted or halogen-substituted cyclic, linear or branched C 1 to C 18 alkyl or alkenyl radical or a C 6 to C 18 aryl radical, and
R 4 each independently is a C 6 -C 18 aryl radical,
a is an integer from 0 to 2, where
a) the polymer compositions exhibit skin formation times >40 minutes at 23° C. and 50% relatively atmospheric humidity, and
b) the skin formation times of the polymer compositions can be reduced to <20 minutes by the addition of a catalyst (K) at concentrations of up to 3% by weight
wherein the polymers (P) are obtained by reaction employing an isocyanatosilane (B1) of the formula (5)
OCN—CH 2 —SiR 1 a (OR 2 ) 3-a . (5)
4. A polymer composition comprising at least one alkoxysilane-terminated polymer (P) bearing end group(s) (1) of the general formula
-A-CH 2 —SiR 1 a (OR 2 ) 3-a (1)
where
A each independently is a —O—CO—N(R 3 )—, or —N(R 3 )—CO—O— divalent linking group,
R 1 each independently is an unsubstituted or halogen-substituted alkyl, cycloalkyl, alkenyl or aryl radical having 1-10 carbon atoms,
R 2 each independently is an alkyl radical having 1-6 carbon atoms or an ω-oxaalkyl-alkyl radical having in total 2-10 carbon atoms,
R 3 each independently is hydrogen, an unsubstituted or halogen-substituted cyclic, linear or branched C 1 to C 18 alkyl or alkenyl radical or a C 6 to C 18 aryl radical, and
a is an integer from 0 to 2, where
a) the polymer compositions exhibit skin formation times >40 minutes at 23° C. and 50% relatively atmospheric humidity, and
b) the skin formation times of the polymer compositions can be reduced to <20 minutes by the addition of a catalyst (K) at concentrations of up to 3% by weight.
5. The polymer composition of claim 4 , which contains not more than 100 ppm of activating compounds (AV) selected from the group consisting of sterically unhindered bases, sterically unhindered acids and aromatic amine hydrochlorides, based on the total mass of the polymer compositions.
6. The polymer composition of claim 4 , wherein the catalyst(s) (K) are selected from acids, bases and organometallic compounds.
7. The polymer composition of claim 4 , wherein the catalysts (K) comprise organic amino compounds.
8. The polymer composition of claim 4 , wherein catalyst(s) (K) comprise compounds of the formula (8)
R 7 R 8 N—R 6 —SiR 1 a (OR 2 ) 3-a (8),
where
R 6 each independently is a divalent, branched or unbranched hydrocarbon radical having 1-10 carbon atoms, optionally interrupted by non-adjacent oxygen or by groups N(R 3 ), and
R 7 and R 8 are each independently hydrogen or a branched or unbranched alkyl radical having 1-20 carbon atoms, the alkyl radical optionally substituted by halogen atoms, hydroxyl groups, amino groups, monoalkylamino groups, dialkylamino groups or alkoxy groups.