SILANE GROUP-CONTAINING BRANCHED POLYMER

Abstract

A branched polymer containing silane groups having an average of at least 2.1 silane groups per molecule, from the reaction of (i) a polymer containing isocyanate groups and having an NCO content ranging from 0.7% to 4% by weight, obtained from the reaction of at least one monomeric diisocyanate with at least one polyether polyol in a molar NCO/OH ratio of at least 1.5/1, (ii) with at least one amino-, mercapto- or hydroxysilane, in a stoichiometric ratio of at least 1 mol of amino-, mercapto- or hydroxysilane per molar equivalent of isocyanate groups. The polymer containing silane groups is storage-stable, liquid at room temperature and easily handled, and permits curable compositions having excellent processability, rapid curing, high strength coupled with good extensibility, and good thermal stability. It is particularly suitable as a constituent of moisture-curable sealants, adhesives or coatings, additionally including a further, in particular linear, polymer containing silane groups.

Claims

1. A branched polymer containing silane groups from the reaction of (i) a polymer containing isocyanate groups and having an NCO content within a range from 0.7% to 4% by weight, obtained from the reaction of at least one monomeric diisocyanate with at least one polyether triol having an average OH functionality within a range from 2.2 to 3 and an OH value within a range from 15 to 58 mg KOH/g in a molar NCO/OH ratio of at least 1.5/1, (ii) with at least one amino-, mercapto- or hydroxysilane, in a stoichiometric ratio of at least 1 mol of amino-, mercapto- or hydroxysilane per molar equivalent of isocyanate groups.

2. The polymer containing silane groups as claimed in claim 1, wherein it has silane groups of formula (I) ##STR00007## where b is 0, 1 or 2, especially 0 or 1, R.sup.1 is an alkyl radical optionally containing ether groups and having 1 to 10 carbon atoms, R.sup.2 is a divalent hydrocarbyl radical having 1 to 12 carbon atoms that optionally has cyclic and/or aromatic moieties and optionally one or more heteroatoms, especially an amido, carbamate or morpholino group, and X is O, S or NR.sup.3 where R.sup.3 is H or a monovalent hydrocarbyl radical having 1 to 20 carbon atoms that optionally has heteroatoms in the form of alkoxysilyl, ether or carboxylic ester groups.

3. The polymer containing silane groups as claimed in claim 1, wherein it has an average of 2.1 to 4 2.1 to 4 silane groups per molecule.

4. The polymer containing silane groups as claimed in claim 1, wherein the monomeric diisocyanate is 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane.

5. The polymer containing silane groups as claimed in claim 1, wherein the monomeric diisocyanate is diphenylmethane 4,4′-diisocyanate.

6. The polymer containing silane groups as claimed in claim 1, wherein the polyether triol, based on all repeat units, contains 80% to 100% by weight of 1,2-propyleneoxy groups and 0% to 20% by weight of 1,2-ethyleneoxy groups.

7. The polymer containing silane groups as claimed in claim 1, wherein the molar NCO/OH ratio in the reaction is within a range from 1.6/1 to 2.5/1.

8. The polymer containing silane groups as claimed in claim 1, wherein the molar NCO/OH ratio in the reaction is at least 3/1 and that after the reaction a major part of the unreacted monomeric diisocyanate is removed by means of a suitable method of separation.

9. A process for preparing a polymer containing silane groups as claimed in claim 1, wherein (a) at least one monomeric diisocyanate is reacted with at least one polyether triol having an average OH functionality within a range from 2.2 to 3 and an OH value within a range from 15 to 58 mg KOH/g in a molar NCO/OH ratio of at least 1.5/1, (b) a major part of the unreacted monomeric diisocyanate is then optionally removed by means of a suitable method of separation, (c) and the resulting polymer containing isocyanate groups is then reacted with at least one amino-, mercapto- or hydroxysilane in a stoichiometric ratio of at least 1 mol of amino-, mercapto- or hydroxysilane per molar equivalent of isocyanate groups.

10. The process as claimed in claim 9, wherein at least one polyether diol is present in step a) in addition to the polyether triol.

11. A reaction product from the process as claimed in claim 9.

12. A curable composition comprising at least one polymer containing silane groups as claimed in claim 1 and at least one further constituent selected from the group consisting of catalysts, crosslinkers, adhesion promoters, desiccants, plasticizers, and fillers.

13. The curable composition as claimed in claim 12, wherein it comprises at least one further, noninventive polymer containing silane groups.

14. The curable composition as claimed in claim 12, wherein it is used as elastic adhesive or elastic sealant or elastic coating.

15. A cured composition obtained from the curable composition as claimed in claim 12 after contact thereof with moisture.

Description

EXAMPLES

[0157] Working examples are presented hereinbelow, the purpose of which is to further elucidate the described invention. The invention is of course not limited to these described working examples.

[0158] “Standard climatic conditions” (“SCC”) refer to a temperature of 23±1° C. and a relative air humidity of 50±5%.

[0159] The chemicals used were unless otherwise stated from Sigma-Aldrich.

[0160] Diisodecyl phthalate was used in the form of Palatinol® 10-P (from BASF).

[0161] Viscosity was measured using a thermostated Rheotec RC30 cone-plate viscometer (cone diameter 25 mm, cone angle 1°, cone tip-plate distance 0.05 mm, shear rate 10 s.sup.−1).

[0162] Monomeric diisocyanate content was determined by HPLC (detection via photodiode array; 0.04 M sodium acetate/acetonitrile as mobile phase) after prior derivatization with N-propyl-4-nitrobenzylamine.

[0163] Preparation of Polymers Containing Isocyanate Groups with Polyether Triol

[0164] Polymer T-1: (NCO/OH=2.1/1)

[0165] 190.0 g of ethylene oxide-terminated polyoxypropylene triol (OH value 28 mg KOH/g, Desmophen® 5031 BT, from Covestro), 27.8 g of diisodecyl phthalate, 22.2 g of IPDI (1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, Vestanat® IPDI, from Evonik), and 0.12 g of dibutyltin dilaurate were reacted by a known method at 90° C. to afford a polymer having an NCO content of 1.75% by weight and a viscosity of 31 Pa.Math.s at 20° C.

[0166] Polymer T-2:

[0167] 780.0 g of ethylene oxide-terminated polyoxypropylene triol (OH value 28 mg KOH/g, Desmophen® 5031 BT, from Covestro) and 220 g of IPDI (1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, Vestanat® IPDI, from Evonik) were reacted in the presence of 0.01 g of dibutyltin dilaurate by a known method at 80° C. to afford a polymer having an NCO content of 6.4% by weight, a viscosity of 4.1 Pa.Math.s at 20° C., and a monomeric IPDI content of about 12% by weight. The volatile constituents, in particular the major part of the monomeric IPDI, were then removed by distillation in a short-path evaporator (jacket temperature 160° C., pressure 0.1 to 0.005 mbar). The polymer thus obtained had an NCO content of 1.9% by weight, a viscosity of 8.2 Pa.Math.s at 20° C., and a monomeric IPDI content of 0.02% by weight.

[0168] Polymer T-3:

[0169] 725.0 g of ethylene oxide-terminated polyoxypropylene triol (OH value 28 mg KOH/g, Desmophen® 5031 BT, from Covestro) and 275 g of diphenylmethane 4,4′-diisocyanate (Desmodur® 44 MC L, from Covestro) were reacted by a known method at 80° C. to afford a polymer having an NCO content of 7.6% by weight, a viscosity of 6.5 Pa.Math.s at 20° C., and a monomeric diphenylmethane 4,4′-diisocyanate content of approx. 20% by weight.

[0170] The volatile constituents, in particular a major part of the monomeric diphenylmethane 4,4′-diisocyanate, were then removed by distillation in a short-path evaporator (jacket temperature 180° C., pressure 0.1 to 0.005 mbar, condensation temperature 47° C.). The polymer thus obtained had an NCO content of 1.7% by weight, a viscosity of 19 Pa.Math.s at 20° C., and a monomeric diphenylmethane 4,4′-diisocyanate content of 0.04% by weight.

[0171] Polymer T-4: (NCO/OH=2.1/1)

[0172] 190.0 g of ethylene oxide-terminated polyoxypropylene triol (OH value 28 mg KOH/g, Desmophen® 5031 BT, from Covestro) and 25.0 g of diphenylmethane 4,4′-diisocyanate (Desmodur® 44 MC L, from Covestro) were reacted by a known method at 80° C. The reaction mixture underwent gelation during the reaction and was consequently unsuitable for further use.

[0173] Preparation of Polymers Containing Isocyanate Groups with Polyether Diol

[0174] Polymer L-1: (NCO/OH=2.1/1)

[0175] 1000.0 g of polyoxypropylene diol (OH value 10 mg KOH/g, Acclaim® 12200N, from Covestro), 122.8 g of diisodecyl phthalate, 41.6 g of IPDI (1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, Vestanat® IPDI, from Evonik), and 0.12 g of dibutyltin dilaurate were reacted by a known method at 90° C. to afford a polymer having an NCO content of 0.63% by weight, a viscosity of 31 Pa.Math.s at 20° C., and a monomeric IPDI content of about 0.5% by weight.

[0176] Silanes of Formula (II) Used: [0177] Silane A-1 Diethyl N-(3-trimethoxysilylpropyl)aminosuccinate (351.5 g/mol), obtained from the reaction of 3-aminopropyltrimethoxysilane and diethyl maleate in a molar ratio of about 1/1

[0178] Preparation of Polymers Containing Silane Groups

[0179] Polymer ST-1: (Inventive, Branched)

[0180] To an initial charge of 240.0 g of polymer T-1, prepared as described above, was added under a nitrogen atmosphere with exclusion of moisture 36.2 g of silane A-1 and the mixture was stirred at 60° C. until isocyanate groups were no longer detectable by FT-IR spectroscopy. The resulting polymer was cooled to room temperature and stored with exclusion of moisture. It contained 10% by weight of plasticizer (diisodecyl phthalate), was clear, and on the day after preparation had a viscosity of 97 Pa.Math.s at 20° C.

[0181] Polymer ST-2: (Inventive, Branched)

[0182] To an initial charge of 221.0 g of polymer T-2, prepared as described above, was added under a nitrogen atmosphere with exclusion of moisture 36.2 g of silane A-1 and the mixture was stirred at 60° C. until isocyanate groups were no longer detectable by FT-IR spectroscopy. The resulting polymer was cooled to room temperature and stored with exclusion of moisture. It was clear and on the day after preparation had a viscosity of 70 Pa.Math.s at 20° C.

[0183] Polymer ST-3: (Inventive, Branched)

[0184] To an initial charge of 247.0 g of polymer T-3, prepared as described above, was added under a nitrogen atmosphere with exclusion of moisture 36.2 g of silane A-1 and the mixture was stirred at 60° C. until isocyanate groups were no longer detectable by FT-IR spectroscopy. The resulting polymer was cooled to room temperature and stored with exclusion of moisture. It was clear and on the day after preparation had a viscosity of 357 Pa.Math.s at 20° C.

[0185] Polymer SL-1: (Noninventive, Linear)

[0186] To an initial charge of 333.3 g of polymer L-1, prepared as described above, was added under a nitrogen atmosphere with exclusion of moisture 18.1 g of silane A-1 and the mixture was stirred at 60° C. until isocyanate groups were no longer detectable by FT-IR spectroscopy. The resulting polymer was cooled to room temperature and stored with exclusion of moisture. It contained 10% by weight of plasticizer (diisodecyl phthalate), was clear, and on the day after preparation had a viscosity of 99 Pa.Math.s at 20° C.

[0187] Polymer SPUR-1: (Comparative, Branched)

[0188] 190.0 g of Desmophen® 5031 BT and 19.5 g of 3-isocyanatopropyltrimethoxysilane were reacted by a known method at 80° C. to afford a polymer containing silane groups. The resulting polymer was cooled to room temperature and stored with exclusion of moisture. It was clear and on the day after preparation had a viscosity of 5 Pa.Math.s at 20° C.

[0189] Moisture-Curing Compositions:

[0190] Compositions Z1 to Z9:

[0191] For each composition, the ingredients specified in Tables 1 to 2 were mixed in the amounts specified (in parts by weight) with exclusion of moisture for one minute at 3000 rpm using a centrifugal mixer (SpeedMixer™ DAC 150, FlackTek Inc.) and stored with exclusion of moisture.

[0192] The compositions were tested as follows:

[0193] As a measure of storage stability, the viscosity was measured after storage with exclusion of moisture in a closed aluminum tube at room temperature after one day (1d RT) and after 7 days in an air-circulation oven at 60° C. (7d 60° C.).

[0194] As a measure of the open time, the skin time (HBZ) was determined. For this purpose, a few grams of the composition were applied to cardboard in a layer thickness of about 2 mm and the period of time under standard climatic conditions after which there were no longer any residues remaining on an LDPE pipette used to gently tap the surface of the composition was determined.

[0195] As a measure of hardness and heat stability, the Shore A hardness was determined in accordance with DIN 53505 on test specimens cured under standard climatic conditions for 7 days (7d SCC), or on test specimens stored under standard climatic conditions for 7 days and then for the specified period at the specified temperature in an air-circulation oven at 80° C., 90° C. or 100° C.

[0196] For the determination of mechanical properties, the composition was applied to a silicone-coated release paper to give a film of thickness 2 mm, which was stored under standard climatic conditions for 14 days, after which a few dumbbells having a length of 75 mm with a bar length of 30 mm and a bar width of 4 mm were punched out of the film and these were tested in accordance with DIN EN 53504 at a strain rate of 200 mm/min to determine the tensile strength (breaking force), elongation at break, and 5% modulus of elasticity (at 0.5-5% elongation).

[0197] The results are reported in Tables 1 to 2.

[0198] Comparative examples are identified by (Ref.).

TABLE-US-00001 TABLE 1 Composition (in parts by weight) and properties of Z1 to Z5. “n.m.” means “not measurable”, because too soft (destroyed) Z1 Z5 Composition (Ref.) Z2 Z3 Z4 (Ref.) Polymer SL-1 50.0 40.0 40.0 40.0 40.0 Polymer ST-1 — 10.0 — — — Polymer ST-2 — — 10.0 — — Polymer ST-3 — — — 10.0 — Polymer SPUR-1 — — — — 10.0 AMMO.sup.1 1.0 1.0 1.0 1.0 1.0 VTMO.sup.2 1.0 1.0 1.0 1.0 1.0 DBU.sup.3 0.1 0.1 0.1 0.1 0.1 DBTDL.sup.4 0.05 0.05 0.05 0.05 0.05 Viscosity @ 1 d RT 66 33 32 76 43 20° C., 7 d 60° C. 52 35 32 78 38 [Pa .Math. s] HBZ 1 d RT 13 27 27 13 13 [min] 7 d 60° C. 20 31 30 40 20 Shore A 7 d SCC 35 37 38 40 39 +7 d 80° C. 33 35 37 39 36 +14 d 80° C. 31 33 34 35 34 +7 d 90° C. 29 30 31 31 26 +14 d 90° C. n.m. 20 20 17 n.m. +7 d 100° C. n.m. 24 21 17 n.m. Tensile strength [MPa] 0.59 0.65 0.63 1.01 0.68 Elongation at break [%] 72 77 63 125 72 MoE 5% [MPa] 1.12 1.20 1.32 1.50 1.30 .sup.13-Aminopropyltrimethoxysilane .sup.2Vinyltrimethoxysilane .sup.31,8-Diazabicyclo[5.4.0]undec-7-ene .sup.4Dibutyltin dilaurate

TABLE-US-00002 TABLE 2 Composition (in parts by weight) and properties of Z6 to Z9. “n.m.” means “not measurable”, because too soft (destroyed) Composition Z6 Z7 Z8 Z9 Polymer ST-1 50.0 — — — Polymer ST-2 — 50.0 — — Polymer ST-3 — — 50.0 45.0 Diisodecyl phthalate — — — 5.0 AMMO.sup.1 1.0 1.0 1.0 1.0 VTMO.sup.2 1.0 1.0 1.0 1.0 DBU.sup.3 0.1 0.1 0.1 0.1 DBTDL.sup.4 0.05 0.05 0.05 0.05 Viscosity @ 1 d RT 46 30 154 55 20° C. 7 d 60° C. 50 32 232 97 [Pa .Math. s] HBZ 1 d RT 22 22 8 13 [min] 7 d 60° C. 26 25 10 12 Shore A 7 d SCC 47 54 57 56 +7 d 80° C. 47 55 57 55 +14 d 80° C. 48 54 57 54 +7 d 90° C. 47 51 57 53 +14 d 90° C. 45 48 57 50 +7 d 100° C. 43 47 51 50 Tensile strength [MPa] 0.60 0.72 0.76 0.66 Elongation at break [%] 36 30 25 24 MoE 5% [MPa] 1.80 2.69 3.27 2.77 .sup.13-Aminopropyltrimethoxysilane .sup.2Vinyltrimethoxysilane .sup.31,8-Diazabicyclo[5.4.0]undec-7-ene .sup.4Dibutyltin dilaurate

[0199] From Tables 1 and 2 it can be seen that the inventive compositions Z2 to Z4 and Z6 to Z9 have good to very good thermal stability, whereas comparative 5 compositions Z1 and Z5 have inadequate thermal stability. After storage at 90° C. for 14 days and at 100° C. for 7 days, the Shore A test specimens thereof have been destroyed to such an extent that measurement was no longer possible.