Silane coupling agents

Abstract

The present invention discloses silylated polyurethanes obtainable by reacting at least one polyols, at least one polyisocyanates, at least one amide-functionalized silanes of the general formula (I) as described herein and their preparation methods, curable compositions comprising the silylated polyurethanes and their use as adhesive, sealant, spray foam and/or coating.

Claims

1. A silylated polyurethane that is the reaction product of a mixture comprising: a) at least one polyol having a number average molecular weight of from 1000 to 50,000 g/mol; b) at least one polyisocyanate, diisocyanate; and c) at least one amide-functionalized silane of the general formula (I) ##STR00008##  wherein  R.sup.1 is hydrogen; R.sup.2 and R.sup.3 are same or different and are, independently from one another, selected from the group consisting of hydrogen and substituted or unsubstituted hydrocarbon residues, alkyl or aryl residues, more alkyl residues, having 1 to 20 carbon atoms, 1 to 8 carbon atoms, most methyl, ethyl, or n-propyl residue; R.sup.4 is selected from linear or branched, substituted or unsubstituted hydrocarbon residues, alkyl residues, having 1 to 20 carbon atoms, 1 to 8 carbon atoms, more ethyl, n-propyl or n-butyl residue; R.sup.6 is selected from the group consisting of hydrogen and linear or branched, substituted or unsubstituted hydrocarbon residues, alkyl or aryl residues, having 1 to 20 carbon atoms, 1 to 8 carbon atoms, more methyl, ethyl or n-propyl residue; and  n is 0, 1, 2 or 3, 3.

2. The silylated polyurethane according to claim 1, wherein the amide-functionalized silane of the general formula (I) is the reaction product of at least one aminosilane having a primary amino group with at least one compound having the general formula (II) ##STR00009## wherein R.sup.5 is a hydrolysable group selected from the group consisting of a hydroxyl group, alkoxy or aryloxy residues having 1 to 20 carbon atoms, alkoxy residues having 1 to 8 carbon atoms, which can be interrupted by at least one heteroatom selected from N, O, and/or S, alkoxide, triflate, tosylate, and halogens; and R.sup.6 is selected from the group consisting of hydrogen and linear or branched, substituted or unsubstituted hydrocarbon residues, alkyl or aryl residues, having 1 to 20 carbon atoms.

3. The silylated polyurethane according to claim 2, wherein the aminosilane having a primary amino group has the general formula (III) ##STR00010## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 and n are the same as defined above.

4. The silylated polyurethane according to claim 1, wherein the at least one polyol comprises a polyether polyol.

5. The silylated polyurethane according to claim 1, wherein n in the general formulae (I) is 3.

6. The silylated polyurethane according to claim 1, wherein R.sup.3 is selected from alkyl residues having 1 to 8 carbon atoms, methyl, ethyl or n-propyl.

7. The silylated polyurethane according to claim 1, wherein the silylated polyurethane is obtained by (a) reacting at least one polyol having a number average molecular weight of from 1000 to 50,000 g/mol with at least one polyisocyanate, diisocyanate, with a stoichiometric excess of the NCO group of the polyisocyanate(s) with respect to the OH group of the polyol(s) to form a NCO-terminated polyurethane prepolymer; and (b) reacting said NCO-terminated polyurethane prepolymer with at least one amide-functionalized silane of the general formula (I) ##STR00011##  wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.6 and n are the same as defined above.

8. The silylated polyurethane according to claim 7, wherein a molar ratio of the NCO group of the polyisocyanate(s) to the OH group of the polyol(s) is from 1.01 to 2.0.

9. The silylated polyurethane according to claim 1, wherein the silylated polyurethane is obtained by (a) reacting at least one polyisocyanate, with at least one amide-functionalized silane of the general formula (I) ##STR00012##  wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.6 and n are the same as defined above, with a stoichiometric excess of the NCO group of the polyisocyanate(s) with respect to the amino group of the silane(s) of the general formula (I); and (b) reacting the reaction product obtained in step (a) with at least one polyol having a number average molecular weight of from 1000 to 50,000 g/mol.

10. The silylated polyurethane according to claim 9, wherein a molar ratio of the NCO group of the polyisocyanate(s) to the amino group of the amide-functionalized silane(s) of the general formula (I) is from 1.1 to 3.0.

11. A method for preparing a silylated polyurethane comprising reacting a mixture including: a) at least one polyol having a number average molecular weight of from 1000 to 50,000 g/mol; b) at least one polyisocyanate, diisocyanate; and c) at least one amide-functionalized silane of the general formula (I) ##STR00013##  wherein R.sup.1 is hydrogen; R.sup.2 and R.sup.3 are same or different and are, independently from one another, selected from the group consisting of hydrogen and substituted or unsubstituted hydrocarbon residues, alkyl or aryl residues, more alkyl residues, having 1 to 20 carbon atoms, 1 to 8 carbon atoms, most methyl, ethyl, or n-propyl residue; R.sup.4 is selected from linear or branched, substituted or unsubstituted hydrocarbon residues, alkyl residues, having 1 to 20 carbon atoms, 1 to 8 carbon atoms, more ethyl, n-propyl or n-butyl residue; R.sup.6 is selected from the group consisting of hydrogen and linear or branched, substituted or unsubstituted hydrocarbon residues, alkyl or aryl residues, having 1 to 20 carbon atoms, 1 to 8 carbon atoms, more methyl, ethyl or n-propyl residue; and n is 0, 1, 2 or 3, 3.

12. A curable composition comprising the silylated polyurethane according to claim 1.

13. The curable composition according to claim 12, further comprising at least one component selected from plasticizer, stabilizer, antioxidant, filler, reactive diluent, drying agent, adhesion promoter, UV stabilizer, rheological agent, solvent and mixtures thereof.

14. An adhesive, sealant, spray foam and/or coating comprising the curable composition according to claim 12.

Description

EXAMPLES

Example 1: Preparation of N-2-propynamide-3-propyltriethoxysilane

(1) In a dry round bottom flask under argon atmosphere 8.948 g (21.7 mmol) of dicyclohexylcarbodiimide (DCC) in 50 wt. % dichloromethane (DCM) was slowly added to a solution of 1.82 g (26.06 mmol) of propiolic acid in 10 ml of DCM and stirred for 30 minutes at 0° C. Afterwards, 4.81 g (21.72 mmol) of (3-aminopropyl)triethoxysilane (AMEO by trade name Geniosil GF 93 from WACKER AG) was added dropwise to the solution and stirred for 90 minutes while temperature was slowly raised from 0° C. to room temperature. After the reaction the precipitated 1,3-dicyclohexylurea was filtered off followed by solvent removal by coevaporation with toluene at room temperature. The product was a yellow viscous liquid of 93% purity.

Example 2: End-Capping of Polypropylene Glycol Using N-2-propynamide-3-propyltriethoxysilane

(2) In a dry round bottom flask under argon atmosphere 10 g of 4200 Acclaim polypropylene glycol (PPG, OH number 28±1.5 mg KOH/g) and 1.166 g (5.25 mmol) of isophorone diisocyanate (IPDI) were mixed and stirred for 1 hour at 70° C. The mixture was afterwards cooled down to room temperature. In the same flask 1.36 g (5 mmol) of N-2-propynamide-3-propyltriethoxysilane (Example 1) and 0.005 g (1 mol %) of triethylamine were added. The reaction mixture was stirred overnight at room temperature. Afterwards IR spectrum was measured to confirm that all NCO groups were reacted. The resulting prepolymer appeared as a yellow viscous liquid with a viscosity of 23.92 Pa.Math.s at 25° C.

Comparative Example 1: End-Capping Method Using (3-aminopropyl)triethoxysilane

(3) In an evacuated round bottom flask under argon atmosphere 10 g of 4200 Acclaim PPG (OH number 14±1.5 mg KOH/g) and 1.166 g (5.25 mmol) of IPDI were mixed and stirred for 1 hour at 70° C. In the same flask 1.105 g (5 mmol) of (3-aminopropyl)triethoxysilane was added. Reaction mixture was stirred overnight at 70° C. Afterwards IR spectrum was measured to confirm that all NCO groups were reacted. Resulting prepolymer appeared as a colorless viscous liquid with a viscosity of 73.08 Pa.Math.s at 25° C.