Catalyst having a polysiloxane structural unit for hardenable compositions

Abstract

A conversion product which has at least one aliphatic amidine or guanidine group and at least one polysiloxane radical, and the use of the conversion product as a catalyst for cross-linking hardenable compositions, in particular based on polymers containing silane groups. The conversion product is largely odor-free, non-volatile, and of low toxicity. The conversion product accelerates the cross-linking of such compositions surprisingly well, does not impair the stability of such compositions in storage, and is very highly compatible, which means that such compositions do not tend toward separation or migration or evaporation of the catalyst.

Claims

1. A composition comprising: at least one polymer containing silane groups, and at least one reaction product and/or at least one compound of the formula (I),
[Q-L.sub.(q-r)PL-Q-Y].sub.r(I) wherein the at least one reaction product is obtained from a reaction of: at least one amidine of the formula HZ or HX-A-Z1, or at least one guanidine of the formula HX-A-Z1, with at least one polysiloxane of the formula (II),
PL-Q].sub.q(II) where: q is 1 or 2 and r is 1 or 2, with (q-r) being 0 or 1, P is a q-valent polysiloxane radical having 3 to 100 silicon atoms, L is an alkylene radical which is bonded to a silicon atom of P and has 1 to 12 carbon atoms, Q is a reactive group selected from glycidoxy, N-aziridinyl, 1,3-keto ester, 1,3-keto amide, (meth)acrylate, and (meth)acrylamide, Q is a divalent connecting unit formed from the reaction of a reactive Q group with HY, Y is Z or is X-A-Z1, Z is an aliphatic amidine group bonded via a nitrogen atom, Z1 is an aliphatic amidine or guanidine group via a nitrogen atom, 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, where at least 2 of the 2 to 30 carbon atoms are resent in a chain of A that links X and Z1, and X is S or NR.sup.7, where R.sup.7 is a hydrogen radical or is an alkyl or cycloalkyl or aralkyl radical which has 1 to 8 carbon atoms and optionally contains a tertiary amino group or an amidine or guanidine group, where A together with R.sup.7 may also be a trivalent hydrocarbyl radical which has 5 to 10 carbon atoms and optionally contains a tertiary amine nitrogen.

2. The composition as claimed in claim 1, wherein the composition is an adhesive or a sealant or a coating.

3. The composition as claimed in claim 1, wherein P is a divalent polysiloxane radical of the formula (IVa) ##STR00038## where: R.sup.10 is independently a monovalent hydrocarbyl radical having 1 to 12 carbon atoms, and n is an integer from 1 to 48.

4. The composition as claimed in claim 1, wherein the amidine of the formula HZ or HX-A-Z1 or the guanidine of the formula HX-A-Z1 is an amidine of the formula (IIIa) ##STR00039## where R.sup.3 is a hydrogen radical or methyl radical.

5. The composition as claimed in claim 1, wherein the amidine of the formula HZ or HX-A-Z1 or the guanidine of the formula HX-A-Z1 is an amidine of the formula (IIIb) ##STR00040## where R.sup.3 is a hydrogen radical or methyl radical.

6. The composition as claimed in claim 1, wherein the amidine of the formula HZ or HX-A-Z1 or the guanidine of the formula HX-A-Z1 is a guanidine of the formula (IIIc) ##STR00041## where R.sup.2 and R.sup.5 are each independently an alkyl, cycloalkyl or aralkyl radical which has 1 to 12 carbon atoms and optionally contains an ether oxygen or tertiary amine nitrogen.

7. The composition as claimed in claim 1, wherein Q is selected from the group consisting of: ##STR00042## where: E.sup.1 is a hydrogen radical or methyl radical, E.sup.2 is a hydrogen radical or methyl radical, and W is O or NR.sup.14 where R.sup.14 is a hydrogen radical or is a monovalent hydrocarbyl radical having 1 to 8 carbon atoms.

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) MW stands for molecular weight.

(4) AcEW stands for acrylate equivalent weight.

(5) MAcEW stands for methacrylate equivalent weight.

(6) EEW stands for epoxy equivalent weight.

(7) 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).

(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, there were for the first time no residues remaining any longer on the pipette.

(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) Polysiloxanes of the Formula (II) Used:

(12) TABLE-US-00001 Silmer Acryloyloxy-functional polysiloxane, MW 1100 g/mol, ACR Di-10 AcEW 550 g/mol, from Siltech Silmer Acryloyloxy-functional polysiloxane, MW 1400 g/mol, ACR D2 AcEW 560 g/mol, from Siltech Tegomer Difunctional polysiloxane with acryloyloxyorgano end V-Si 2250 groups, AcEW about 1000 g/mol, from Evonik X-22-164 Difunctional polysiloxane with methacryloyloxy end groups, AcEW 190 g/mol, from Shin-Etsu X-22-164AS Difunctional polysiloxane with methacryloyloxy end groups, AcEW 450 g/mol, from Shin-Etsu Tegomer Epoxy-functional polydimethylsiloxane, MW about E-Si 2330 2400 g/mol, EEW about 1200 g/mol, from Evonik Silmer Difunctional polysiloxane with epoxy end groups, MW EP Di-25 2050 g/mol, EEW 1025 g/mol, from Siltech

Preparation of Amidine or Guanidine of the Formula HZ or HX-A-Z

Amidine A1: 2-Methyl-1,4,5,6-tetrahydropyrimidine

(13) In a round-bottom flask, 7.58 g of propane-1,3-diamine, 16.37 g of trimethyl orthoacetate and 0.60 g of lanthanum(III) trifluoromethanesulfonate were mixed and the mixture was heated to 100 C. while stirring for 24 hours. Thereafter, the reaction mixture was freed of the volatile constituents under reduced pressure. This gave 5.97 g of a white solid.

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

Guanidine G1: Reaction Product Comprising 1-(3-aminopropyl)-2,3-dicyclohexylguanidine

(15) In a round-bottom flask, 2.50 g of 1,3-diaminopropane and 6.89 g of N,N-dicyclohexylcarbodiimide were mixed and the mixture was heated to 120 C. while stirring. At regular intervals, the reaction mixture was analyzed by means of FT-IR spectroscopy. After 1 hour, the carbodiimide band at about 2120 cm.sup.1 had disappeared completely. Thereafter, the reaction mixture was freed of the volatile constituents under reduced pressure. This gave 9.36 g of a pale yellow oil of low odor.

(16) FT-IR: 3371 (NH), 2921, 2849, 1627 (CN), 1502, 1447, 1324, 1238, 1147, 1111, 888, 713.

Preparation of Reaction Products of the Invention

(17) Catalyst U1:

(18) In a round-bottom flask, a solution of 2.14 g of amidine A1 in 7 mL of tetrahydrofuran was mixed with 11.43 g of Silmer ACR Di-10 and stirred at 40 C. for 40 min. Thereafter, the reaction mixture was freed of the volatile constituents under reduced pressure. This gave an odorless yellowish oil.

(19) FT-IR: 3216, 2960, 1736, 1622 (CN), 1558, 1415, 1384, 1318, 1257, 1172, 1257, 1210, 1172, 1013, 926, 862, 790, 702.

(20) Catalyst U2:

(21) In a round-bottom flask, a solution of 1.60 g of amidine A1 in 5 mL of tetrahydrofuran was mixed with 4.44 g of Silmer ACR D2 and stirred at 40 C. for 60 min. Thereafter, the reaction mixture was freed of the volatile constituents under reduced pressure. This gave an odorless brownish oil.

(22) FT-IR: 3175, 2958, 2930, 2852, 1735, 1620 (CN), 1551, 1484, 1427, 1361, 1318, 1257, 1173, 1012, 943, 841, 793, 754, 687.

(23) Catalyst U3:

(24) In a round-bottom flask, a solution of 2.04 g of amidine A1 in 5 mL of tetrahydrofuran was mixed with 20.02 g of Tegomer V-Si 2250 and stirred at 40 C. for 2 h. Thereafter, the reaction mixture was freed of the volatile constituents under reduced pressure. This gave an odorless brownish oil.

(25) FT-IR: 2961, 2904, 2862, 1735, 1618 (CN), 1430, 1413, 1383, 1361, 1318, 1258, 1217, 1179, 1080, 1012, 863, 789, 701, 686.

(26) Catalyst U4:

(27) In a round-bottom flask, 2.25 g of amidine A1 were mixed with 27.22 g of Tegomer E-Si 2330 and stirred at 90 C. for 3 h. This gave an odorless yellowish oil.

(28) FT-IR: 2961, 2905, 2858, 1616 (CN), 1413, 1318, 1258, 1011, 863, 792, 700.

(29) Catalyst U5:

(30) In a round-bottom flask, 1.97 g of amidine A1 were mixed with 23.82 g of Silmer EP Di-25 and stirred at 90 C. for 3 h. This gave an odorless yellowish oil.

(31) FT-IR: 2961, 2904, 2863, 1616 (CN), 1413, 1318, 1258, 1074, 1011, 863, 792, 699.

(32) Catalyst U6:

(33) In a round-bottom flask, a solution of 1.46 g of guanidine G1 in 4 mL of tetrahydrofuran was mixed with 2.80 g of Silmer ACR Di-10 and stirred at 25 C. for 2 h. Thereafter, the reaction mixture was freed of the volatile constituents under reduced pressure. This gave an odorless orange oil.

(34) FT-IR: 2960, 2926, 2852, 1733, 1633 (CN), 1508, 1449, 1411, 1359, 1258, 1183, 1067, 1015, 861, 792, 702.

(35) Catalyst U7:

(36) In a round-bottom flask, a solution of 1.60 g of guanidine G1 in 5 mL of tetrahydrofuran was mixed with 1.55 g of Silmer ACR Di-10 and stirred at 40 C. for 1 h. Thereafter, the reaction mixture was freed of the volatile constituents under reduced pressure. This gave an odorless brownish oil.

(37) FT-IR: 3270, 2925, 2851, 1732, 1631 (CN), 1504, 1449, 1360, 1345, 1258, 1147, 1066, 1016, 888, 842, 796, 754, 702.

(38) Catalyst U8:

(39) In a round-bottom flask, a solution of 2.05 g of guanidine G1 in 4 mL of tetrahydrofuran was mixed with 7.34 g of Tegomer V-Si 2250 and stirred at 40 C. for 3 h. Thereafter, the reaction mixture was freed of the volatile constituents under reduced pressure. This gave an odorless brownish oil.

(40) FT-IR: 3373, 2961, 2929, 2854, 1737, 1633 (CN), 1519, 1449, 1411, 1364, 1258, 1184, 1367, 1013, 910, 863, 792, 703, 686.

(41) Catalyst U9:

(42) In a round-bottom flask, 1.66 g of guanidine G1 were mixed with 1.03 g of X-22-164 and stirred at 100 C. for 20 h. This gave an odorless, pale green, vitreous solid.

(43) FT-IR: 3291, 2923, 2851, 1750, 1633 (CN), 1505, 1449, 1375, 1321 1258, 1159, 1051, 978, 937, 889, 839, 794, 709.

(44) Catalyst U10: In a round-bottom flask, 3.41 g of guanidine G1 were mixed with 5.86 g of X-22-164AS and stirred at 100 C. for 48 h. This gave an odorless pale green oil.

(45) FT-IR: 3270, 2926, 2852, 1725, 1627 (CN), 1568, 1449, 1366, 1317, 1257, 1150, 1018, 889, 783, 703.

(46) Catalyst U11:

(47) In a round-bottom flask, 1.42 g of guanidine G1 were mixed with 6.06 g of Silmer EP Di-25 and stirred at 90 C. for 5 h. This gave an odorless, slightly cloudy, whitish oil.

(48) FT-IR: 2961, 2928, 2853, 1633 (CN), 1449, 1412, 1361, 1258, 1077, 1013, 863, 789, 704, 686.

Preparation of Polyethers Containing Silane Groups

(49) Polymer STP-1:

(50) 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.

(51) Commercial Catalysts Used:

(52) TABLE-US-00002 Cat.41 Reaction product of tetraethyl silicate with bis(acetyloxy)dibutylstannane, tin content about 23.8% by weight (Catalyst 41, from Wacker) DBU 1,8-diazabicyclo[5.4.0]undec-7-ene (Lupragen N 700, from BASF) TMG 1,1,3,3-tetramethylguanidine (from Sigma-Aldrich) IBAY bis(ethylacetoacetato)diisobutoxytitanium(IV) (Tyzor IBAY, from Dorf Ketal)

(53) Compositions Based on Polymers Containing Silane Groups:

(54) Comparative examples in tables 1 to 4 are indicated by (Ref).

(55) Compositions Z1 to Z13

(56) In a round-bottom flask, 71.1 g of an OH-terminated linear polydimethylsiloxane having a viscosity of about 50000 mPas at 23 C. (Wacker Silicone Rubber Polymer FD 50, from Wacker) were blended with 2.6 g of vinyltris(methylethylketoximo)silane and stirred under reduced pressure for 15 minutes. 26.3 g of trimethylsilyl-terminated polydimethylsiloxane (Wacker AK 100 silicone oil, from Wacker) were stirred into the polydimethylsiloxane having vinylbis(methylethylketoximo)silyl end groups that was obtained in this way. This mixture was blended with various catalysts according to table 1 below 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 cured under standard climatic conditions for 7 days and tested for mechanical properties.

(57) The results are shown in tables 1 and 2.

(58) In addition, each mixture was applied to a white PVC substrate in the form of a bead and cured under standard climatic conditions. Thereafter, the substrate was heated to 80 C. in an oven for 1 hour. Thereafter, in the case of reference compositions Z11 and Z12, brownish discoloration was apparent on the PVC substrate alongside and beneath the cured bead, whereas no discoloration occurred in the case of the other compositions.

(59) TABLE-US-00003 TABLE 1 Viscosity [Pa .Math. s] ST Composition Catalyst Amount Concentration.sup.1 fresh stored.sup.2 fresh stored.sup.2 Z1 U1 0.22 g 0.5 11.8 11.9 22 20 Z2 U2 0.30 g 1.0 14.7 12.9 20 17 Z3 U3 0.38 g 0.5 12.1 12.5 35 30 Z4 U4 0.46 g 0.5 15.0 11.0 30 30 Z5 U6 0.29 g 0.5 12.9 11.6 26 22 Z6 U7 0.39 g 1.0 14.8 14.3 29 31 Z7 U8 0.46 g 0.5 11.6 11.8 42 47 Z8 U10 0.27 g 0.5 14.7 12.9 26 20 Z9 U11 0.53 g 0.5 15.4 13.7 30 27 Z10 (ref.) Cat.41 0.33 g 0.9 11.7 48.1 27 32 Z11 (ref.) DBU 0.04 g 0.4 18.2 15.9 10 12 Z12 (ref.) TMG 0.03 g 0.4 17.4 16.5 23 27 Z13 (ref.) IBAY 0.13 g 0.4 19.7 19.9 27 47 .sup.1mmol of amidine or guanidine groups or metal atoms per 100 g of ketoximato polydimethylsiloxane polymer. .sup.2for 7 days at 70 C. in a closed container.

(60) TABLE-US-00004 TABLE 2 Modulus of elasticity Surface Tensile Elongation at 0-50% Composition after 24 h strength break elongation Z1 dry 0.25 MPa 278% 0.14 MPa Z2 dry 0.22 MPa 260% 0.14 MPa Z3 dry n.d. n.d. n.d. Z4 dry 0.25 MPa 307% 0.13 MPa Z5 dry n.d. n.d. n.d. Z6 dry n.d. n.d. n.d. Z7 dry 0.19 MPa 142% 0.12 MPa Z8 dry 0.23 MPa 196% 0.14 MPa Z9 dry 0.19 MPa 213% 0.14 MPa Z10 (ref.) dry 0.24 MPa 256% 0.15 MPa Z11 (ref.) dry 0.22 MPa 135% 0.13 MPa Z12 (ref.) dry 0.15 MPa 86% 0.16 MPa Z13 (ref.) dry 0.25 MPa 116% 0.18 MPa n.d. stands for not determined

(61) Compositions Z14 to Z23:

(62) A composition composed of 96.5 g of polymer STP-1, 0.5 g of vinyltrimethoxysilane and 3.0 g of 3-aminopropyltrimethoxysilane was blended with various catalysts in the amount specified according to table 3, and tested as described for composition Z1 for viscosity, skin time (ST), surface characteristics and mechanical properties.

(63) The results are shown in tables 3 and 4.

(64) In addition, each mixture was applied to a white PVC substrate in the form of a bead and cured under standard climatic conditions. Thereafter, the substrate was heated to 80 C. in an oven for 1 hour. Thereafter, in the case of reference compositions Z22 and Z23, brownish discoloration was apparent on the PVC substrate alongside and beneath the cured bead, whereas no discoloration occurred in the case of the other compositions.

(65) TABLE-US-00005 TABLE 3 Viscosity [Pa .Math. s] ST Composition Catalyst Amount Concentration.sup.1 fresh stored.sup.2 fresh stored.sup.2 Z14 U1 1.14 g 1.9 29.2 38.1 22 20 Z15 U3 1.95 g 1.9 29.7 44.8 45 18 Z16 U4 2.36 g 1.9 27.0 49.3 35 31 Z17 U5 2.36 g 1.9 27.8 51.0 30 30 Z18 U6 1.50 g 1.9 29.9 45.2 13 7 Z19 U8 2.36 g 1.9 28.7 45.3 36 31 Z20 U9.sup.3 0.83 g 1.9 20.7 39.5 13 14 Z21 U10 1.40 g 1.9 41.0 53.6 13 12 Z22 (ref.) DBU 0.28 g 1.9 27.2 36.9 25 29 Z23 (ref.) TMG 0.21 g 1.9 22.3 24.6 65 75 .sup.1mmol of amidine or guanidine groups per 100 g of polyether containing silane groups. .sup.2for 7 days at 70 C. in a closed container. .sup.3as a solution (25% by wt.) in N-ethylpyrrolidone.

(66) TABLE-US-00006 TABLE 4 Surface Tensile Elongation Modulus of elasticity Composition after 24 h strength at break 0-5% 0-50% Z14 dry 0.67 MPa 101% 1.27 MPa 0.83 MPa Z15 dry 0.75 MPa 124% 1.23 MPa 0.82 MPa Z16 dry 0.82 MPa 130% 1.14 MPa 0.83 MPa Z17 dry 0.85 MPa 142% 1.25 MPa 0.82 MPa Z18 dry 0.71 MPa 113% 1.09 MPa 0.82 MPa Z19 dry 0.81 MPa 141% 1.21 MPa 0.84 MPa Z20 dry 0.70 MPa 103% 1.28 MPa 0.83 MPa Z21 dry 0.78 MPa 118% 1.12 MPa 0.85 MPa Z22 (ref.) greasy 0.58 MPa 72% 1.16 MPa 0.77 MPa Z23 (ref.) tacky 0.62 MPa 90% 1.19 MPa 0.75 MPa