HYDROXY SILANE AS AN ADHESION PROMOTER OR CROSS-LINKING AGENT

Abstract

A hydroxy silane of formula (I) used as an adhesion promoter or cross-linking agent for adhesives, sealants or coatings. The invention also relates to an adhesion-promoter composition containing the hydroxy silane of formula (I) and to adhesives, sealants or coatings containing the hydroxy silane of formula (I). The hydroxy silane of formula (I) has a surprisingly long shelf-life and exhibits an excellent action as an adhesion promoter and/or cross-linking agent.

Claims

1. A method of using a hydroxysilane of the formula (I) ##STR00006## as adhesion promoter or crosslinker for adhesives or sealants or coatings, comprising: applying the hydroxysilane to a substrate surface, and subsequently or concurrently applying an adhesive, sealant, or coating to the substrate surface, where either R′ is a radical of the formula (II) and R″ is a hydrogen radical or R′ is a hydrogen radical and R″ is a radical of the formula (II); ##STR00007## R.sup.1 is an aliphatic or cycloaliphatic or arylaliphatic hydrocarbyl radical which has 1 to 18 carbon atoms and optionally has heteroatoms in the form of ether oxygen, ester oxygen, thioether sulfur or secondary or tertiary amine nitrogen, and which optionally has a silane group; R.sup.2 is a linear or branched alkylene or cycloalkylene radical having 1 to 20 carbon atoms, optionally having aromatic components, and optionally having one or more heteroatoms; R.sup.3 is an alkyl radical having 1 to 8 carbon atoms; R.sup.4 is an aliphatic or cycloaliphatic or arylaliphatic hydrocarbyl radical which has 1 to 12 carbon atoms and optionally has one or two ether oxygens; Y is O or is S or NR.sup.0 where R.sup.0 is a hydrogen atom or is an alkyl radical which has a silane group and has 1 to 12 carbon atoms; and n is 0 or 1 or 2.

2. The method as claimed in claim 1, wherein Y is O or is NR.sup.0.

3. The method as claimed in claim 2, wherein Y is O and R.sup.1 is an aliphatic or cycloaliphatic or arylaliphatic hydrocarbyl radical which has 1 to 12 carbon atoms and optionally has one or two ether oxygens.

4. The method as claimed in claim 2, wherein Y is NR.sup.0, R.sup.0 is a hydrogen atom and R.sup.1 is an aliphatic or cycloaliphatic or arylaliphatic hydrocarbyl radical which has 1 to 12 carbon atoms and optionally has one or two ether oxygens or one or two secondary or tertiary amino groups.

5. The method as claimed in claim 1, wherein Y is S or NR.sup.0 and R.sup.1 is an aliphatic hydrocarbyl radical which has 1 to 12 carbon atoms and has a silane group and optionally has a secondary amino group.

6. The method as claimed in claim 1, wherein R.sup.2 is a 1,2-ethylene radical.

7. The method as claimed in claim 1, wherein R.sup.4 is a methyl radical or is an ethyl radical.

8. The method as claimed in claim 1, wherein n is 0 or 1.

9. The method as claimed in claim 1, wherein the adhesive, sealant, or coating comprises at least one curable binder.

10. The method as claimed in claim 1, wherein the hydroxysilane is applied to the substrate surface as a constituent of an adhesion promoter composition to form a pretreated substrate, and then the adhesive, sealant, or coating is applied to the pretreated substrate.

11. The method as claimed in claim 1, wherein the hydroxysilane is a constituent of the adhesive, sealant, or coating.

12. An adhesion promoter composition comprising at least one hydroxysilane of the formula (I) and at least one solvent ##STR00008## where either R′ is a radical of the formula (II) and R″ is a hydrogen radical or R′ is a hydrogen radical and R″ is a radical of the formula (II); ##STR00009## R.sup.1 is an aliphatic or cycloaliphatic or arylaliphatic hydrocarbyl radical which has 1 to 18 carbon atoms and optionally has heteroatoms in the form of ether oxygen, ester oxygen, thioether sulfur or secondary or tertiary amine nitrogen, and which optionally has a silane group; R.sup.2 is a linear or branched alkylene or cycloalkylene radical having 1 to 20 carbon atoms, optionally having aromatic components, and optionally having one or more heteroatoms; R.sup.3 is an alkyl radical having 1 to 8 carbon atoms; R.sup.4 is an aliphatic or cycloaliphatic or arylaliphatic hydrocarbyl radical which has 1 to 12 carbon atoms and optionally has one or two ether oxygens; Y is O or is S or NR.sup.0 where R.sup.0 is a hydrogen atom or is an alkyl radical which has a silane group and has 1 to 12 carbon atoms; and n is 0 or 1 or 2.

13. A composition usable as an adhesive or sealant or coating, comprising at least one hydroxysilane of the formula (I) ##STR00010## where either R′ is a radical of the formula (II) and R″ is a hydrogen radical or R′ is a hydrogen radical and R″ is a radical of the formula (II); ##STR00011## R.sup.1 is an aliphatic or cycloaliphatic or arylaliphatic hydrocarbyl radical which has 1 to 18 carbon atoms and optionally has heteroatoms in the form of ether oxygen, ester oxygen, thioether sulfur or secondary or tertiary amine nitrogen, and which optionally has a silane group; R.sup.2 is a linear or branched alkylene or cycloalkylene radical having 1 to 20 carbon atoms, optionally having aromatic components, and optionally having one or more heteroatoms; R.sup.3 is an alkyl radical having 1 to 8 carbon atoms; R.sup.4 is an aliphatic or cycloaliphatic or arylaliphatic hydrocarbyl radical which has 1 to 12 carbon atoms and optionally has one or two ether oxygens; Y is O or is S or NR.sup.0 where R.sup.0 is a hydrogen atom or is an alkyl radical which has a silane group and has 1 to 12 carbon atoms; and n is 0 or 1 or 2.

14. The composition as claimed in claim 13, wherein it has, after curing, an elongation at break of at least 10%.

15. The composition as claimed in claim 13, wherein it is a coating in the form of a varnish or a seal.

Description

EXAMPLES

[0136] Detailed hereinafter are working examples which are intended to illustrate the invention described in detail. Of course, the invention is not restricted to these described working examples.

[0137] “Standard climatic conditions” are understood to mean a temperature of 23±1° C. and a relative air humidity of 50±5%. “SCC” stands for “standard climatic conditions”.

[0138] .sup.1H NMR spectra were measured in CDCl.sub.3 on a Bruker Ascend 400 spectrometer at 400.14 MHz; the chemical shifts δ are reported in ppm relative to tetramethylsilane (TMS); the coupling constants J are reported in Hz.

[0139] Infrared spectra (FT-IR) were measured as undiluted films on a Nicolet iS5 FT-IR system, equipped with a horizontal ATR measurement unit with a diamond crystal, from Thermo Scientific; the absorption bands are reported in wavenumbers (cm.sup.−1) (measurement window: 4000-650 cm.sup.−1).

[0140] Gas chromatograms (GC) were measured in the temperature range from 60 to 320° C. with a heating rate of 15° C./min and a dwell time of 10 min at 320° C. The injector temperature was 250° C. A Zebron ZB-5 column was used (L=30 m, ID=0.25 mm, dj=0.5 μm) 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.

[0141] 1. Hydroxysilanes:

Hydroxysilane 1

2-Ethoxy-4(5)-(2-triethoxysilylethyl)cyclohexan-1-ol

[0142] In a round-bottom flask, 150.00 g of ethanol and 0.50 g of vinyltriethoxysilane were stirred under a nitrogen atmosphere at 50° C. for 15 min. Subsequently, 180.00 g (624 mmol) of β-(3,4-epoxycyclohexyl)ethyltriethoxysilane (CoatOSil® 1770, from Momentive) and 3.06 g of aluminum(III) isopropoxide were added, and the mixture was stirred at reflux at 100° C. under a nitrogen atmosphere for 16 h. Then the cloudy reaction mixture was cooled down to room temperature and filtered, and excess ethanol was evaporated on a rotary evaporator at 80° C. and 10 mbar. A colorless liquid product was obtained.

[0143] After the preparation, the product had a purity of 92% by weight (determined by means of gas chromatography). After storage with exclusion of moisture at room temperature for 3 months, the purity was unchanged.

[0144] FT-IR: 3444 (O—H), 2973, 2925, 2882, 2735, 1483, 1443, 1389, 1347, 1294, 1263, 1212, 1165, 1100, 1073, 1012, 953, 885, 860, 767, 710, 677.

[0145] .sup.1H NMR: δ 3.81 (m, 6H, Si—O—CH.sub.2—CH.sub.3), 3.68 and 3.56 (2×m, 2×0.5 (OH)C.sup.cyclH), 3.64 and 3.43 (2×m, 2×1H, C.sup.cyclH—O—CH.sub.2—CH.sub.3), 3.27 and 3.13 (2×m, 2×0.5H, C.sup.cyclH—O—CH.sub.2—CH.sub.3), 2.50 (m, 1H, C.sup.cyclH), 1.80, 1.64 and 1.48 (3×m, 6H, C.sup.cycl, H.sub.2) 1.41 (m, 2H, C.sup.cyclH—CH.sub.2—CH.sub.2—Si), 1.22 (m, 12H, Si—O—CH.sub.2—CH.sub.3), 0.61 (m, 2H, C.sup.cyclH—CH.sub.2—CH.sub.2—Si).

[0146] GC: Four peaks at retention times from 12.57 min to 12.82 min with a total of 92 area % were detected, which were assigned to the diastereomers of 2-ethoxy-4-(2-triethoxysilylethyl)cyclohexan-1-ol and 2-ethoxy-5-(2-triethoxysilylethyl)cyclohexan-1-ol and were added up for the purity.

Hydroxysilane 2

2-Methoxy-4(5)-(2-trimethoxysilylethyl)cyclohexan-1-ol

[0147] In a round-bottom flask, 104.35 g of methanol and 0.39 g of vinyltrimethoxysilane were stirred under a nitrogen atmosphere at 50° C. for 15 min. Then 153.74 g (624 mmol) of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (Silquest® A-186, from Momentive) and 3.06 g of aluminum(III) isopropoxide were added and the cloudy mixture was reacted in 60 g portions in the microwave reactor, in each case at 140° C. and a pressure of about 12 bar for 30 min. Subsequently, the combined cloudy reaction mixtures were cooled down to room temperature and filtered, and excess methanol was evaporated on a rotary evaporator at 80° C. and 10 mbar. A colorless liquid product was obtained.

[0148] After the preparation, the product had a purity of 91% by weight (determined by means of gas chromatography). After storage with exclusion of moisture at room temperature for 3 months, the purity was unchanged.

[0149] FT-IR: 3456 (O—H), 2924, 2839, 1454, 1411, 1381, 1349, 1292, 1270, 1190, 1157, 1077, 997, 935, 908, 889, 874, 776, 710, 675.

[0150] .sup.1H NMR: δ 3.73 and 3.61 (2×m, 2×0.5H, (OH)C.sup.cyclH), 3.57 (d, 9H, Si—O—CH.sub.3), 3.37 (d, 3H, C.sup.cyclH—O—CH.sub.3), 3.20 and 3.07 (2×m, 2×0.5H, C.sup.cyclH—O—CH.sub.3), 2.60 (m, 1H, C.sup.cyclH), 1.82, 1.72, 1.63 and 1.46 (4×m, 6H, C.sup.cyclH.sub.2), 1.39 (q, 2H, C.sup.cyclH—CH.sub.2—CH.sub.2—Si), 0.62 (m, 2H, C.sup.cyclH—CH.sub.2—CH.sub.2—Si).

[0151] GC: Two peaks at retention times from 11.57 min to 11.68 min with a total of 91 area % were detected, which were assigned to the diastereomers of 2-methoxy-4-(2-trimethoxysilylethyl)cyclohexan-1-ol and 2-methoxy-5-(2-trimethoxysilylethyl)cyclohexan-1-ol and were added up for the purity.

Hydroxysilane 3

[0152] Mixture comprising 2-(2-methoxyethoxy)ethoxy-4(5)-(2-tris(2-(2-methoxyethoxy)ethoxy)silylethyl)cyclohexan-1-ol, 2-(2-methoxyethoxy)ethoxy-4(5)-(2-ethoxybis(2-(2-methoxyethoxy)ethoxy)silylethyl)cyclohexan-1-ol and 2-(2-methoxyethoxy)ethoxy-4(5)-(2-diethoxy(2-(2-methoxyethoxy)ethoxy)silylethyl)cyclohexan-1-ol

[0153] In a round-bottom flask, 117.04 g of methyldiglycol (2-(2-methoxyethoxy)ethanol), 50.00 g (203 mmol) of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (Silquest® A-186, from Momentive) and 0.50 g of aluminum(III) isopropoxide were stirred under a nitrogen atmosphere at 120° C. for 1 h. Subsequently, at constant temperature, a clear distillate was collected via an uncooled distillation attachment at 400 mbar over 2 h, at 300 mbar over a further 2 h and at 150 mbar over a further 3 h, which was identified as almost pure methanol with traces of methyldiglycol by FT-IR. The reaction mixture was stirred at 140° C. and 50 mbar for 24 hours, until it was no longer possible to collect any more distillate. Finally, the excess methyldiglycol was removed at 120° C. and 0.5 mbar. A colorless liquid product was obtained. FT-IR: 3473 (O—H), 2923, 2874, 2820, 1454, 1411, 1354, 1329, 1292, 1248, 1198, 1086, 1028, 958, 847, 770, 715, 681.

Hydroxysilane 4

2-Hexylamino-4(5)-(2-triethoxysilylethyl)cyclohexan-1-ol

[0154] In a round-bottom flask, 17.37 g of hexylamine and 0.20 g of vinyltriethoxysilane were stirred under a nitrogen atmosphere at 50° C. for 15 min. Subsequently, 45.00 g (156 mmol) of β-(3,4-epoxycyclohexyl)ethyltriethoxysilane (CoatOSil® 1770, from Momentive) and 0.15 g of aluminum(III) acetylacetonate were added, and the mixture was stirred at reflux at 110° C. under a nitrogen atmosphere for 16 h. Then excess hexylamine was removed on a rotary evaporator at 80° C. and 10 mbar for 1 h. A colorless liquid product was obtained.

[0155] After the preparation, the product had a purity of 97.3% by weight (determined by means of gas chromatography). After storage with exclusion of moisture at room temperature for 3 months, the purity was unchanged.

[0156] FT-IR: 3297 (OH), 3152 (NH), 2971, 2924, 2882, 2857, 2735, 1613, 1454, 1410, 1389, 1365, 1294, 1166, 1101, 1075, 954, 906, 880, 767, 674.

[0157] .sup.1H NMR: δ 3.81 (m, 6H, Si—O—CH.sub.2—CH.sub.3), 3.40 and 3.21 (2×m, 2×0.5H, (OH)C.sup.cyclH), 2.73 (m, 1H, (C.sub.6H.sub.13—NH)C.sup.cyclH), 2.46 and 2.38 and 2.24 (m, 2H, (C.sub.5H.sub.11—CH.sub.2NH)C.sup.cycl), 1.95 to 1.25 (m, 17H, 1×(R).sub.3C.sup.cyclH, 3×(R).sub.2C.sup.cyclH.sub.2, CH.sub.3—CH.sub.2—CH.sub.2—CH.sub.2—CH.sub.2—CH.sub.2—NHR, 1×(R).sub.2HC.sup.cycl—CH.sub.2—CH.sub.2—Si), 1.22 (m, 9H, Si—O—CH.sub.2—CH.sub.3), 0.89 (t, 3H, (CH.sub.3—C.sub.4H.sub.8—NH)C.sup.cycl), 0.61 (m, 2H, C.sup.cyclH—CH.sub.2—CH.sub.2—Si). GC: Four peaks at retention times from 15.21 min to 15.73 min with a total of 97.3 area % were detected, which were assigned to the diastereomers of 2-hexylamino-4(5)-(2-triethoxysilylethyl)cyclohexan-1-ol and were added up for the purity. In addition, two peaks at retention times of 11.30 min and 11.34 min with a total of 2.7 area % were detected, which were assigned to the diastereomers of β-(3,4-epoxycyclohexy)ethyltriethoxysilane (reactant).

[0158] 2. Adhesion Promoter Compositions

[0159] Adhesion Promoter Solution HL1 to HL4:

[0160] Four adhesion promoter solutions were prepared, by respectively dissolving 1.0% by weight of hydroxysilane 1 (=adhesion promoter HL1), 1.0% by weight of hydroxysilane 2 (=adhesion promoter HL2), 1.0% by weight of hydroxysilane 3 (=adhesion promoter HL3) and 1.0% by weight of hydroxysilane 4 (=adhesion promoter HL4) in solvent. Absolute ethanol was used for HL1 and HL4, absolute methanol for HL2, and ethyl acetate for HL3. The resultant adhesion promoter solutions HL1 to HL4 were each used as an activator on glass. For this purpose, spacer tape was stuck longitudinally onto the air side of glass plates (float glass; from Rocholl, Schönbrunn, Germany) with dimensions of 10×15 cm, so as to give three glass strips each of 2×13 cm in each case. Each strip was cleaned with acetone and then wiped either once with a hygiene tissue wetted with adhesion promoter solution or once with a hygiene tissue wetted with the respective solvent used (references). After a flash-off time of 2 h under standard climatic conditions, 7.8 g of an MDI polymer, the preparation of which is described below, per strip were applied in a layer thickness of about 3 mm. The glass plates were stored under standard climatic conditions.

[0161] After 4 days under standard climatic conditions, the MDI polymer had cured completely. On the strips that had been treated with the solvents only, the cured MDI polymer could be pulled away from the glass substrate with only little expenditure of force. It did not have good adhesion on the glass. On the strips treated with the adhesion promoter solutions HL1, HL2, HL3 and HL4, it was not possible to pull the cured MDI polymer off the glass substrate. Even after making several cuts transverse to the strip direction down to the glass substrate, with which the polymer was cut away from the glass, and pulling the polymer strip away in a perpendicularly upward direction, it was not possible to remove the MDI polymer from the glass substrate.

[0162] The MDI polymer used was prepared by reacting, with exclusion of moisture, 845 g of Acclaim® 4200 N polyol (polypropylene oxide diol, OH number 28.5 mg KOH/g, from Bayer) and 115 g of 4,4′-methylene diphenyl diisocyanate (MDI; Desmodur® 44 MC L, from Bayer) by known methods at 80° C. to give a polyurethane polymer having a content of free isocyanate groups, determined by titrimetry, of 1.96% by weight. The product was cooled to room temperature and stored with exclusion of moisture.