Catalyst containing amidine groups

Abstract

The use of an amidine of formula (I) and/or a conversion product thereof as a catalyst for the crosslinking of a composition based on silane group-containing polymers. The amidine of formula (I) and the conversion products thereof are essentially odorless at room temperature and non-volatile and accelerate the crosslinking of the composition very well without impairing the storage stability of the composition, and are very compatible in the composition. As a result, the compositions do not have a tendency to separate, migrate or evaporate the catalyst.

Claims

1. A method of catalyzing hydrolysis or condensation or both of a polymer containing silane groups, comprising contacting a catalyst with the polymer containing silane groups, wherein: the catalyst comprises at least one amidine of the formula (I)
Y-A-Z(I) where A is a divalent hydrocarbyl radical which has 2 to 30 carbon atoms and optionally contains unsaturated components and optionally ether oxygen or secondary or tertiary amine nitrogen, Y is NR.sup.8R.sup.9 where R.sup.8 and R.sup.9 are independently an alkyl radical having 1 to 8 carbon atoms, or together are an optionally substituted alkylene radical having 4 to 10 carbon atoms, and Z is an amidine group bonded via a nitrogen atom, where Y and Z are separated from one another by at least two carbon atoms, and/or at least one reaction product of at least one amidine of the formula (I) with at least one functional compound, wherein A is not a polyoxyalkylene radical and wherein the amidine of the formula (I) does not contain any nitrogen atom which is directly bonded to an aromatic ring or is part of a heteroaromatic ring system.

2. The method as claimed in claim 1, wherein Z is ##STR00026## where R.sup.0 is a hydrogen radical or is an alkyl or cycloalkyl or aralkyl radical having 1 to 8 carbon atoms, R.sup.1 is a hydrogen radical or is an alkyl or cycloalkyl or aralkyl radical having 1 to 8 carbon atoms or together with R.sup.2 is R.sup.4, R.sup.2 is a hydrogen radical or is an alkyl, cycloalkyl or aralkyl radical which has 1 to 18 carbon atoms and optionally contains heteroatoms, or together with R.sup.1 is R.sup.4, R.sup.3 is a hydrogen radical or is an alkyl or cycloalkyl or aralkyl radical having 1 to 12 carbon atoms, and R.sup.4 is 1,2-ethylene or 1,2-propylene or 1,3-propylene or 1,3-butylene or 1,3-pentylene, where R.sup.0 and R.sup.2 together may also be an alkylene radical which has 3 to 6 carbon atoms and may optionally contain ether oxygen or tertiary amine nitrogen, and R.sup.2 and R.sup.3 together may also be an alkylene radical having 3 to 6 carbon atoms.

3. The method as claimed in claim 2, wherein Z is ##STR00027##

4. The method as claimed in claim 1, wherein A is selected from the group consisting of 1,2-ethylene, 1,3-propylene, 1,2-propylene, 1,3-pentylene, 1,1-dimethyl-1,2-ethylene, 1,5-pentylene, 2-methyl-1,5-pentylene, 1,6-hexylene, 2,2(4),4-trimethyl-1,6-hexamethylene, 1,8-octylene, 1,10-decylene, 1,12-dodecylene, (1,5,5-trimethylcyclohexan-1 -yl)methane-1,3, 1,3-cyclohexylenebis(methylene), 1,4-cyclohexylenebis(methylene), 1,3-phenylenebis(methylene), 2- and/or 4-methyl-1,3-cyclohexylene, N-methyl-4-aza-1,7-heptylene, N-ethyl-4-aza-1,7-heptylene, 3-aza-1,5-pentylene, 4- aza-1,7-heptylene, 3 -aza-1,6-hexylene, 7-aza-1,13-tridecylene, 3 -oxa-1,5-pentylene, 3,6-dioxa-1,8-octylene and 4,7-dioxa-1,10-decylene.

5. The method as claimed in claim 1, wherein the functional compound has at least one reactive group selected from epoxide, aziridine, carbonate, carboxylic anhydride, carboxylic acid, carboxylic ester, lactone, carbonyl chloride, ketone, aldehyde, 1,3-diketone, 1,3-keto ester, 1,3-keto amide, cyanate, thiocyanate, isocyanate, isothiocyanate, (meth)acrylate, (meth)acrylamide, (meth)acrylonitrile, maleate, maleamide, maleimide, fumarate, fumaramide, itaconate, itaconamide, crotonate and crotonamide.

6. The method as claimed in claim 1, wherein the polymer containing silane groups is selected from the group consisting of polyorganosiloxanes having terminal silane groups and organic polymers containing silane groups.

7. A composition comprising at least one amidine of the formula (I) and/or at least one reaction product as described in claim 1 and at least one polymer containing silane groups.

8. The composition as claimed in claim 7, wherein the polymer containing silane groups is a polyorganosiloxane having terminal silane groups.

9. The composition as claimed in claim 7, wherein the polymer containing silane groups is an organic polymer containing silane groups.

10. The composition as claimed in claim 7, wherein it is an adhesive or a sealant or a coating.

Description

EXAMPLES

(1) Adduced hereinafter are working examples which are intended to elucidate the invention described in detail. It will be appreciated that the invention is not restricted to these described working examples.

(2) Standard climatic conditions refer to a temperature of 231 C. and a relative air humidity of 505%.

(3) EEW stands for epoxy equivalent weight.

(4) .sup.1H NMR spectra were measured on a spectrometer of the Bruker Ascend 400 type at 400.14 MHz; the chemical shifts are reported in ppm relative to tetramethylsilane (TMS). Coupling constants J are reported in Hz. No distinction was made between true coupling and pseudo-coupling patterns.

(5) Infrared spectra (FT-IR) were measured on a Nicolet iS5 FT-IR instrument from Thermo Scientific equipped with a horizontal ATR measurement unit with a diamond crystal. Liquid samples were applied undiluted as films; solid samples were dissolved in CH.sub.2Cl.sub.2. The absorption bands are reported in wavenumbers (cm.sup.1) (measurement window: 4000-650 cm.sup.1).

(6) Gas chromatograms (GC) were measured within the temperature range of 60 to 320 C. with a heating rate of 15 C./min and a run time of 10 min at 320 C.

(7) The injector temperature was 250 C. A Zebron ZB-5 column was used (L=30 m, ID=0.25 mm, dj=0.5 m) with a gas flow rate of 1.5 ml/min. Detection was effected by means of flame ionization (FID), with evaluation of the signals via the area percent method.

(8) The skin time (ST) was determined by applying a few grams of the composition to cardboard in a layer thickness of about 2 mm and measuring, under standard climatic conditions, the time until, when the surface of the composition was gently tapped by means of an LDPE pipette, no residues remained any longer on the pipette for the first time.

(9) The characteristics of the surface were tested by touch.

(10) The mechanical properties of tensile strength, elongation at break and modulus of elasticity (at 0-5% and at 0-50% elongation) were measured in accordance with DIN EN 53504 at a pulling speed of 200 mm/min.

(11) Viscosities were measured on a thermostated Rheotec RC30 cone-plate viscometer (cone diameter 50 mm, cone angle 1, cone tip-plate distance 0.05 mm, shear rate 10 s.sup.1).

(12) Reagent Used for Introduction of Amidine Groups:

(13) trimethyl orthoacetate (Sigma-Aldrich)

(14) Functional Compounds Used:

(15) diethyl adipate (Sigma-Aldrich)

(16) tert-butyl acrylate (Sigma-Aldrich)

(17) tetrahydrofurfuryl methacrylate (Sigma-Aldrich)

(18) ethyl acrylate (Sigma-Aldrich)

(19) trimethylolpropane triacrylate (Sigma-Aldrich)

(20) Preparation of Amidines of the Formula (I):

Amidine A1: 1-(2-hydroxyethyl)-2-methyl-1,4,5,6-tetrahydropyrimidine

(21) In a round-bottom flask, 11.91 g of N-(3-aminopropyl)-2-aminoethanol, 15.94 g of trimethyl orthoacetate and 0.32 g of lanthanum(III) trifluoromethanesulfonate were heated to 120 C. while stirring for 24 hours. Thereafter, the reaction mixture was freed of the volatile constituents under reduced pressure and the residue was distilled under reduced pressure. This gave 14.44 g of a colorless low-odor oil having a boiling temperature of 130 to 135 C. at 0.1 mbar, which, according to the GC spectrum, contained a content of 98% of amidine A1 and, when left to stand at room temperature, crystallized to give a white solid.

(22) .sup.1H NMR (CDCl.sub.3): 1.83 (quint., 2 H, J=5.6, NCH.sub.2CH.sub.2CH.sub.2N), 2.02 (s, 3 H, CH.sub.3), 3.24 (t, 2 H, J=5.8, NCH.sub.2CH.sub.2OH), 3.31 (m, 4 H, NCH.sub.2CH.sub.2CH.sub.2N), 3.69 (t, 2 H, J=5.7, NCH.sub.2CH.sub.2OH).

(23) FT-IR: 3214, 3177, 2996, 2925, 2843, 1630, 1542, 1475, 1438, 1380, 1360, 1322, 1294, 1273, 1204, 1191, 1139, 1114, 1095, 1035, 1009, 977, 915, 875, 839, 731.

Amidine A2: 1-(3-aminopropyl)-2-methyl-1,4,5,6-tetrahydropyrimidine

(24) In a round-bottom flask, 62.97 g of trimethyl orthoacetate, 62.12 g of bis(3-aminopropyl)amine (Baxxodur EC 110, from BASF) and 2.80 g of lanthanum(III) trifluoromethanesulfonate were mixed and the mixture was heated under reflux to 120 C. while stirring for 3 days. Thereafter, the reaction mixture was freed of the volatile constituents under reduced pressure and the residue was distilled under reduced pressure. This gave 26.65 g of a colorless oil having a boiling temperature of 85-88 C. at 0.1 mbar, which, according to GC spectrum, contained a content of 87% of amidine A2.

(25) .sup.1H NMR (CDCl.sub.3) (signals from amidine A2 only): 1.05 (s, 2 H, NH.sub.2), 1.57-1.70 (m, 2 H, CH.sub.2CH.sub.2NH.sub.2), 1.74-1.86 (m, 2 H, CNCH.sub.2CH.sub.2), 1.97 (s, 3 H, CH.sub.3), 2.60-2.80 (m, 2 H, CH.sub.2CH.sub.2NH.sub.2), 3.10-3.24 and 3.25-3.34 (2Hm, 22 H, CH.sub.2N).

(26) FT-IR: 3260, 2924, 2748, 1611, 1482, 1433, 1375, 1353, 1317, 1289, 1211, 1149, 1126, 1099, 1085, 1031, 1014, 942, 879, 821, 752, 735, 692.

Amidine A3: 1-(3-dimethylaminopropyl)-2-methyl-1,4,5,6-tetrahydropyrimidine

(27) To an initial charge of 131.63 g of ethyl acetoacetate in 50 ml of toluene in a round-bottom flask were gradually added dropwise, while stirring and cooling, 161.09 g of N.sup.1-((3-dimethylamino)propyl)-1,3-diaminopropane (from BASF), in the course of which the temperature was kept at 20 to 30 C. Thereafter, the azeotrope of toluene and water was removed from the reaction mixture by means of distillation at 40 C. and 10 mbar and then the remaining toluene and ethyl acetate were removed by means of distillation under standard pressure and the residue was distilled under reduced pressure. This gave 168.74 g of a yellowish oil having a boiling temperature of 95-105 C. at 0.6 mbar.

(28) .sup.1H NMR (CDCl.sub.3) (signals from amidine A3 only): 1.6-1.7 (m, 2 H, NCH.sub.2CH.sub.2CH.sub.2N(CH.sub.3).sub.2), 1.75-1.85 (m, 2 H, CNCH.sub.2CH.sub.2), 2.00 (s, 3 H, NC CH.sub.3), 2.19 (s, 6 H, N(CH.sub.3).sub.2), 2.18-2.26 (m, 2 H, CH.sub.2N(CH.sub.3).sub.2), 3.11-3.20 (m, 4 H, NCH.sub.2), 3.26-3.35 (t, 2 H, J=5.7, NCH.sub.2).

(29) FT-IR: 3233, 2937, 2854, 2814, 2763, 1615, 1459, 1419, 1375, 1351, 1317, 1294, 1260, 1230, 1208, 1152, 1118, 1097, 1085, 1040, 1013, 969, 940, 887, 871, 841, 763, 731.

(30) Preparation of Reaction Products:

Amidine U1: Reaction Product Comprising 2-(2-methyl-1,4,5,6-tetrahydropyrimidin-1-yl)ethyl ethyl adipate

(31) In a round-bottom flask, 3.22 g of the amidine A1 prepared above were mixed with 4.62 g of diethyl adipate, the mixture was heated to 100 C. and ethanol was distilled off at 100 mbar for 5 hours. Then the reaction mixture was concentrated fully on a rotary evaporator at 120 C. and 10 mbar. This gave 5.81 g of an orange, low-odor oil.

(32) .sup.1H NMR (CDCl.sub.3): 1.25 (t, 3 H, J=7.2, OCH.sub.2CH.sub.3), 1.62-1.69 (m, 4 H, CH.sub.2CH.sub.2C(O)O), 1.75-1.85 (m, 2 H, CNCH.sub.2CH.sub.2), 1.98 (s, 3 H, NCCH.sub.3), 2.28-2.37 (m, 4 H, CH.sub.2C(O)O), 3.20-3.37 (m, 4 H, CH.sub.2N), 3.41 (t, 2 H, J=5.8, NCH.sub.2CH.sub.2O), 4.12 (q, 2 H, J=7.2, OCH.sub.2CH.sub.3), 4.14-4.20 (m, 2 H, J=5.8, NCH.sub.2CH.sub.2O).

(33) FT-IR: 2629, 2852, 1730, 1316, 1482, 1421, 1376, 1317, 1242, 1209, 1170, 1140, 1087, 1075, 1030, 1012, 941, 882, 856, 752.

Amidine U2: Reaction product comprising tert-butyl 3-(3-(2-methyl-1,4,5,6-tetrahydropyrimidin-1-yl)propylamino)propionate

(34) In a round-bottom flask, 2.05 g of the amidine A2 prepared above were mixed with 1.74 g of tert-butyl acrylate and the mixture was heated to 100 C. while stirring until, after 3 hours, no tert-butyl acrylate was detectable any longer by means of gas chromatography. Thereafter, the reaction mixture was freed of the volatile constituents under reduced pressure. This gave 3.76 g of a colorless, low-odor oil.

(35) .sup.1H NMR (CDCl.sub.3): 1.44 (s, 9 H, tert-BuO), 1.61-1.73 (m, 2 H, CH.sub.2CH.sub.2NH), 1.77-1.86 (m, 2 H, CNCH.sub.2CH.sub.2), 1.98 (s, 3 H, NCCH.sub.3), 2.41 (t, 2 H, J=6.4, CH.sub.2C(O)O), 2.57-2.64 and 2.78-2.86 (2m, 22 H, CH.sub.2NHCH.sub.2), 3.12-3.24 (m, 4 H, CH.sub.2N), 3.27-3.33 (m, 2 H, CH.sub.2N).

(36) FT-IR: 3255, 2974, 2926, 2846, 1723, 1616, 1480, 1456, 1420, 1391, 1366, 1317, 1290, 1248, 1228, 1154, 1039, 1014, 942, 879, 846, 754.

Amidine U3: Reaction product comprising tetrahydrofurfuryl 3-(3-(2-methyl-1,4,5,6-tetrahydropyrimidin-1-yl)propylamino)-2-methylpropionate

(37) In a round-bottom flask, 2.22 g of the amidine A2 prepared above were mixed with 2.60 g of tetrahydrofurfuryl methacrylate and the mixture was heated to 100 C. while stirring until, after 3 hours, no tetrahydrofurfuryl methacrylate was detectable any longer by means of gas chromatography. Thereafter, the reaction mixture was freed of the volatile constituents under reduced pressure. This gave 4.65 g of a yellow, low-odor oil.

(38) .sup.1H NMR (CDCl.sub.3): 1.17 (s, 3 H, CH.sub.3CHC(O)O), 1.56-1.71 (m, 4 H, CH.sub.2CH.sub.2NH and CH.sub.2-THF), 1.75-1.85 (m, 2 H, NCH.sub.2CH.sub.2CH.sub.2N), 1.85-1.93 (m, 1 H, CHC(O)O)), 1.97 (s, 5 H, NCCH.sub.3 and THF), 2.5-2.9 (m, 4 H, CH.sub.2NHCH.sub.2), 3.10-3.25 (m, 4 H, CH.sub.2N), 3.27-3.33 (m, 2 H, CH.sub.2N), 3.78 (q, 1 H, J=7.1, THF), 3.87 (q, 1H, J=7.3, THF), 3.99-4.20 (m, 3H, THF).

(39) FT-IR: 3265, 2928, 2851, 1730, 1614, 1459, 1422, 1376, 1353, 1318, 1291, 1208, 1175, 1130, 1083, 1018, 994, 920, 879, 816, 756.

Amidine U4: Reaction Product Comprising ethyl 3-(3-(2-methyl-1,4,5,6-tetrahydropyrimidin-1-yl)propylamino)propionate

(40) In a round-bottom flask, 2.75 g of the amidine A2 prepared above were mixed with 1.70 g of ethyl acrylate and the mixture was heated to 100 C. while stirring until, after 4 hours, no ethyl acrylate was detectable any longer by means of gas chromatography. This gave a yellow, low-odor oil.

(41) FT-IR: 3159, 2930, 2849, 1730, 1612, 1455, 1429, 1378, 1357, 1319, 1293, 1255, 1206, 1177, 1128, 1046, 1032, 986, 946, 882, 833, 741, 696.

Amidine U5: Reaction product comprising trimethylolpropane tris(7-(2-methyl-1,4,5,6-tetrahydropyrimidin-1-yl)-4-azaheptanoate)

(42) In a round-bottom flask, 3.76 g of the amidine A2 prepared above were mixed with 2.33 g of trimethylolpropane triacrylate and the mixture was heated to 50 C. while stirring until, after 1.5 hours, no trimethylolpropane triacrylate was detectable any longer by means of gas chromatography. This gave a yellow, low-odor oil.

(43) FT-IR: 2926, 2849, 1732, 1661, 1610, 1429, 1377, 1357, 1318, 1292, 1252, 1209, 1173, 1125, 1087, 1045, 1031, 947, 883, 837, 776, 740, 697.

(44) Preparation of a Polyether Containing Silane Groups:

(45) Polymer STP-1:

(46) With exclusion of moisture, 1000 g of Acclaim 12200 polyol (polyoxypropylenediol having a low level of unsaturation, from Bayer; OH number 11.0 mg KOH/g), 43.6 g of isophorone diisocyanate (IPDI; Vestanat IPDI, from Evonik), 126.4 g of diisodecyl phthalate (DIDP) and 0.1 g of bismuth tris(neodecanoate) (10% by weight in DIDP) were heated up to 90 C. while stirring constantly and left at this temperature until the content of free isocyanate groups determined by titrimetry had reached a stable value of 0.63% by weight. Subsequently, 63.0 g of diethyl N-(3-trimethoxysilylpropyl)aminosuccinate (adduct formed from 3-aminopropyltrimethoxysilane and diethyl maleate; prepared according to the details in U.S. Pat. No. 5,364,955) were mixed in and the mixture was stirred at 90 C. until it was no longer possible to detect any free isocyanate by means of FT-IR spectroscopy. The polyether containing trimethoxysilane groups thus obtained, having a silane equivalent weight of about 6880 g/eq (calculated from the amounts used), was cooled down to room temperature and stored with exclusion of moisture.

(47) Commercial Catalysts Used and Abbreviations Therefor:

(48) DBU 1,8-diazabicyclo[5.4.0]undec-7-ene (Lupragen N 700, from BASF)

(49) TMG 1,1,3,3-tetramethylguanidine (from Sigma-Aldrich)

(50) IBAY bis(ethylacetoacetato)diisobutoxytitanium(IV) (Tyzor IBAY, from Dorf Ketal)

(51) Compositions Based on Polymers Containing Silane Groups:

(52) Comparative examples are identified in tables 1 and 2 by (Ref).

(53) Compositions Z1 to Z8:

(54) A composition composed of 96.5 g of polymer STP-1, 0.5 g of vinyltrimethoxysilane and 3.0 g of 3-aminopropyltrimethoxysilane was mixed with various catalysts in the amounts specified according to table 1, and the mixture was tested for viscosity and skin time (ST) under standard climatic conditions, before and after storage. The skin time serves as a measure of the activity of the catalyst in relation to the crosslinking reaction of the silane groups, i.e. of the crosslinking rate; the change in viscosity and the skin time after storage are a measure of storage stability. In addition, the mixture applied, after 24 hours under standard climatic conditions, was tested as to whether the surface was dry as desired or whether a greasy film had formed, which is a sign of the exudation of the catalyst owing to poor compatibility with the cured polymer, and/or whether the surface was tacky, which is a sign of incomplete curing. In addition, the mixture was used to produce a film of thickness 2 mm, which was left to cure under standard climatic conditions for 7 days and tested for mechanical properties. The results are shown in tables 1 and 2. Comp. stands for composition.

(55) TABLE-US-00001 TABLE 1 Viscosity [Pa .Math. s] ST Comp. Catalyst Amount Concentration.sup.1 fresh stored.sup.2 increase fresh stored.sup.2 Z1 Amidine A1 0.26 g 1.90 22.2 25.0 13% 79 62 Z2 Amidine A2 0.29 g 1.90 21.2 26.1 23% 28 26 Z3 Amidine A3 0.34 g 1.90 21.3 22.2 4% 31 32 Z4 Amidine U1 0.55 g 1.90 21.9 29.8 36% 26 32 Z5 Amidine U2 0.52 g 1.90 20.3 24.8 22% 20 28 Z6 Amidine U3 0.60 g 1.90 22.1 25.3 15% 20 27 Z7 Amidine U4 0.52 g 1.90 28.9 33.7 17% 20 25 Z8 Amidine U5 0.48 g 1.90 30.4 36.8 21% 32 36 Z9 (Ref) DBU 0.28 g 1.90 27.2 36.9 36% 25 29 Z10 (Ref) TMG 0.21 g 1.90 22.3 24.6 10% 65 75 .sup.1mmol of amidine or guanidine groups per 100 g of polyether containing silane groups. .sup.2for 7 days at 60 C. in a closed container.

(56) TABLE-US-00002 TABLE 2 Surface Tensile Elongation Modulus of elasticity Comp. after 24 h strength at break 0-5% 0-50% Z1 dry 0.75 MPa 99% 0.99 MPa 0.77 MPa Z2 almost dry 0.69 MPa 102% 1.16 MPa 0.77 MPa Z3 almost dry 0.62 MPa 78% 1.22 MPa 0.84 MPa Z4 dry 0.73 MPa 109% 1.20 MPa 0.79 MPa Z5 dry 0.71 MPa 103% 1.17 MPa 0.80 MPa Z6 almost dry 0.69 MPa 99% 1.25 MPa 0.80 MPa Z7 almost dry 0.74 MPa 111% 1.21 MPa 0.81 MPa Z8 dry 0.79 MPa 127% 1.17 MPa 0.79 MPa Z9 greasy 0.58 MPa 72% 1.16 MPa 0.77 MPa (Ref) Z10 tacky 0.62 MPa 90% 1.19 MPa 0.75 MPa (Ref)