Polyorganosiloxane having heteroatom-containing silyl group

Abstract

The invention relates to polyorganosiloxanes with special silicon-containing groups of the general formula (1) as defined herein, a method for preparing said polyorganosiloxanes, and curable compositions comprising at least one said polyorganosiloxane, at least one adhesion promoter, and at least one curing catalyst. The invention also relates to adhesive, sealant, or coating materials comprising the curable composition and the use of the curable composition.

Claims

1. A polyorganosiloxane containing at least one silyl group of the general formula (1)
(CH.sub.2).sub.2Si(R.sup.1).sub.n(R).sub.m(1), wherein each R.sup.1 is independently selected from a hydrolysable group selected from alkoxy, carboxy, oxime, amino, amido, lactato, alkenoxy, and acetoxy groups, each R is independently of a group of the general formula (2) having at least one heteroatom X bridged to a silicon atom of the general formula (1) via a sp.sup.2-hybridized quaternary carbon atom: ##STR00010## wherein X is a divalent or polyvalent heteroatom; each R.sup.5 is independently selected from oxygen, hydrogen, or a linear or branched, substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms which may contain at least one heteroatom; R.sup.2 and R.sup.3 are, independently from one another, selected from hydrogen or a linear or branched, substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms which may contain at least one heteroatom, or R.sup.2 and R.sup.3 may form a cyclic structure; and q is an integer selected from 0 to 3; and n is 1 or 2 and m is 1 or 2, wherein the sum of n and m is 3.

2. The polyorganosiloxane according to claim 1, wherein each R in the general formula (1) independently has the structure of the general formula (2-A): ##STR00011## wherein R.sup.5, X, and q are as defined for the general formula (2) above; and R.sup.6, R.sup.7 and R.sup.8 are, independently from one another, selected from hydrogen, a hydroxy group, or a linear or branched, substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms which may contain at least one heteroatom.

3. The polyorganosiloxane according to claim 1, wherein the polyorganosiloxane contains at least two silyl groups of the general formula (1).

4. The polyorganosiloxane according to claim 1, wherein the polyorganosiloxane contains at least two terminal silyl groups of the general formula (1).

5. The polyorganosiloxane according to claim 1, wherein each R.sup.1 is independently selected from a C.sub.1-C.sub.8 alkoxy group.

6. The polyorganosiloxane according to claim 1, wherein X is selected from O or S.

7. The polyorganosiloxane according to claim 1, wherein n is 2 and m is 1.

8. A method for preparing a polyorganosiloxane containing at least one silyl group of the general formula (1)
(CH.sub.2).sub.2Si(R.sup.1).sub.n(R).sub.m(1), comprising: providing at least one polyorganosiloxane having at least one SiH group; providing at least one silane compound of the general formula (3) having at least one heteroatom X bridged to a silicon atom via a sp.sup.2-hybridized quaternary carbon atom in the presence of a hydrosilylation catalyst, ##STR00012## wherein each R.sup.1 is independently selected from a hydrolysable group selected from alkoxy, carboxy, oxime, amino, amido, lactato, alkenoxy, and acetoxy groups; each R.sup.2 and R.sup.3 is, independently from one another, selected from hydrogen or a linear or branched, substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms which may contain at least one heteroatom, or R.sup.2 and R.sup.3 may form a cyclic structure; R.sup.4 is vinyl group; each R.sup.5 is independently selected from oxygen, hydrogen, or a linear or branched, substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms which may contain at least one heteroatom; q is an integer selected from 0 to 3; and n is 1 or 2 and m is 1 or 2, wherein the sum of n and m is 3, k is 1; and reacting the at least one polyorganosiloxane having at least one SiH group with the at least one silane compound of the general formula (3) to prepare the polyorganosiloxane.

9. The method according to claim 8, wherein said at least one silane compound has the structure of the general formula (3-A): ##STR00013## wherein each R.sup.6, R.sup.7 and R.sup.8 is, independently from one another, selected from hydrogen, a hydroxy group, or a linear or branched, substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms which may contain at least one heteroatom; and X is a divalent or polyvalent heteroatom.

10. A curable composition comprising: (A) at least one polyorganosiloxane according to claim 1; (B) at least one adhesion promoter; and (C) at least one curing catalyst.

11. The curable composition according to claim 10, wherein the adhesion promoter comprises at least one compound selected from (i) aminosilanes, or (ii) oligomers obtained from the condensation of aminosilanes, or mixtures thereof.

12. The curable composition according to claim 10, wherein the composition comprises: 10 to 95% by weight of the (A) at least one polyorganosiloxane; 0.01 to 5% by weight of the (B) at least one adhesion promoter; 0.05 to 2% by weight of the (C) at least one curing catalyst; and, optionally, at least one or more auxiliary substance(s), wherein the proportions by weight add up to 100 wt. % and the proportions by weight are based on the total weight of the curable composition.

13. The curable composition according to claim 10, wherein the curing catalyst comprises an organotin compound.

14. An adhesive, sealant, or coating material comprising the curable composition according to claim 10.

15. (canceled)

16. The curable composition according to claim 10, wherein the (i) aminosilanes are oligomerized together with alkyl-, alkenyl- or aryl-alkoxysilanes; and/or the (ii) oligomers obtained from the condensation of aminosilanes are oligomerized together with alkyl-, alkenyl- or aryl-alkoxysilanes.

17. The polyorganosiloxane according to claim 1, wherein each R.sup.1 is independently selected from a methoxy or ethoxy group.

Description

EXAMPLES

Example 1: Preparation of Thionylvinyldiethoxysilane

[0169] ##STR00009##

[0170] A three-neck round-bottom flask equipped with cooling condenser, dropping funnel, magnetic stir bar and a stopper is charged with magnesium chips (150 mmol, 1.5 eq, 3.6465 g) and flame-dried under reduced pressure. A crystal of iodine is added and sublimed by heating, etching the surface of the magnesium. Tetrahydrofuran (150 ml), followed by a vinyltriethoxysilane (R is vinyl and R.sup.1s are ethoxy), is added to the flask (150 mmol, 1.5 eq). The stopper is swapped for a thermometer. To the dropping funnel 2-bromothiophene (100 mmol, 1 eq) is added. While stirring, 10 vol % 2-bromothiophene is added to the flask in one portion. An increase in temperature is observed. Dropping is continued while maintaining a temperature between 40 C. and 50 C. After the addition heating to 60 C. is turned on for 2 h. The tetrahydrofuran is distilled off, leaving a wet grey solid. Hexane (150 ml) is added to the flask and the solid is suspended, turning the color from grey to white. The solids are filtered, and hexane is distilled off yielding a crude product. Clean product is obtained by the means of vacuum distillation at 1.010.sup.3 mbar.

Example 2: Preparation of Polyorganosiloxane Containing Thionyldiethoxysilyl Groups

[0171] 1 eq mol ,-dihydrogen-terminated polydimethylsiloxane (Mw: 86,500) (153.8 g), 4 eq mol thionylvinyldiethoxysilane (1.62 g) prepared according to Example 1 and 0.015 wt % of Karstedt's catalyst 540 were stirred at 80 C. for 5 hours.

Example 3: Preparation of Polyorganosiloxane Containing Triethoxysilyl Groups (Comparative Example)

[0172] A mixture of 100 g ,-dihydroxy-terminated polydimethylsiloxane (Mw: 107,000), 6.3 g vinyltriethoxysilane (VTEO) and 0.33 g K Kat 670 (zinc complex catalyst from King) was stirred for 1 min with 2200 rpm at RT.

Example 4

[0173] The Formulations A and B were prepared by mixing the raw materials listed in Table 1 and their skin overtime was measured.

TABLE-US-00001 TABLE 1 Components (amount in g) Formulation A Formulation B Polymer obtained in Example 2 34.5 Polymer obtained in Example 3 34.5 N-(2-aminoethyl)-3- 0.35 0.35 aminopropyltrimethoxysilane dioctyltin dilaurate 0.11 0.11 SOT (min) 35 70

[0174] Determination of Skin-over time (SOT): Skin-overtime (SOT) is defined as the time required for the material to form a non-tacky surface film. The determination of the skin over time was carried out according to DIN 50014 under standard climate conditions (23+/200, relative humidity 50+/5%). The temperature of the sealant must be 23+/200, with the sealant stored for at least 24 h beforehand in the laboratory. The formulation was applied to a sheet of paper and spread out with a putty knife to form a skin (thickness about 2 mm, width about 7 cm). The stopwatch was started immediately. At intervals, the surface was touched lightly with the fingertip and the finger was pulled away, with sufficient pressure on the surface that an impression remains on the surface when the skin formation time was reached. The skin-over time was reached when sealing compound no longer adheres to the fingertip. The skin-over time (SOT) is expressed in minutes.

Example 5

[0175] The Formulations C to E were prepared by mixing the raw materials listed in Table 2 and their curing performance, mechanical properties, and adhesion performance were measured.

TABLE-US-00002 TABLE 2 Components (amount in wt %) Formulation C Formulation D Formulation E Polymer obtained in Example 2 67.0 Polymer obtained in Example 3 67.0 67.0 Plasticizer (Polydimethylsiloxane 21.8 21.8 21.8 with a viscosity of 1,000 cST) Hydrophobic fumed silica (Aerosil R 104) 10.0 10.0 10.0 aminopropyltriethoxysilane 1.0 1.0 vinyltriethoxysilane 1.0 dioctyltin dilaurate 0.2 0.2 0.2 Shore A 1 day 4 nm nm Shore A 7 days 24 nm nm Cure through mm/24 h 4.8 nm nm SOT [Min] 50 120 120 Elongation at break [%] 360 nm nm Modulus at 100% elongation [N/mm.sup.2] 0.43 nm nm Tensile strength at break [N/mm.sup.2] 1.37 nm nm Peel test in 7 days PVC CF nm nm Peel test in 7 days Alu anodized CF nm nm Peel test in 7 days copper CF nm nm Peel test in 7 days stainless steel CF nm nm nm means not measurable. The performances test for formulations D and E (comparative examples) could not be carried out as no curing was observed. CF means cohesion failure.

[0176] Determination of Skin-over time (SOT): Skin-over time (SOT) was measured as described above.

[0177] Measurement of Shore A hardness: Shore A hardness was measured according to ISO 868.

[0178] Determination of the depth of cure (DOC): A strip of the material with a height of 10 mm (+/1 mm) and width of 20 mm (+/2 mm) was applied over a plastic foil (PP) using a Teflon spatula. After storing the sample for 24 hours at normal conditions (23+/2 C., relative humidity 50+/5%), a section of the strip was cut off and the thickness of the cured layer was measured with a caliper. The depth of cure after 24 hours is expressed in millimeters.

[0179] Assessment of the mechanical properties (tensile test): The Tensile test determines the breaking force, elongation at break and yield stress value (e-module), according to DIN 53504. The tests took place using S3 specimen at normal conditions (23+/2 C., relative humidity 50+/5%). The measurement was carried out after 7 days of curing. Procedure: the prepolymer mixture (formulation) was spread on an even surface forming a film with a thickness of 2 mm. The film was allowed to cure under normal conditions (see above) for seven days, and then the dumbbell specimen was punched out. Three specimens were used for each determination. The test was carried out under normal conditions. The test specimens have to be at the same temperature at which the measurement will take place. Before the measurement, the thickness of the test specimens is determined at least at three different positions, at the middle and at the extremes, with a caliper. The mean value is introduced in the measuring software. The test specimens are clamped into the tensile tester so that the longitudinal axis coincides with the mechanical axis of the tensile tester and comprises the largest possible surface of the rod heads, without clamping the middle bar. Then the dumbbell is stretched to <0.1 MPa with a rate of 50 mm/min. Then, the force-elongation curve is recorded with a line speed of 50 mm/min. Evaluation: The following values are determined: breaking force in [N/mm.sup.2] elongation at break in [%] and modulus at 100% elongation in [N/mm.sup.2].

[0180] Peel test: If possible and needed, substrate (test panel) was cleaned prior to application using a suitable solvent. A strip of the material with a height of 10 mm (+/1 mm) and width of 20 mm (+/2 mm) was applied over the substrate using a Teflon spatula/cartridge and cartridge gun. The sample was stored for 7 days at normal conditions (23+/2 C., relative humidity 50+/5%). The cured material was cut back for at least 15 mm with a shape blade and the bead pulled by hand.