Silanes and curable compositions comprising said silanes

Abstract

The invention relates to silane compounds having the general formula (I): SiR.sup.1.sub.n(R.sup.2).sub.4-n (I), as defined herein, to a method for preparing the silane compounds and use thereof as crosslinker or as adhesion promoter and to a curable composition comprising a reaction product of the at least one silane compound, at least one polyorganosiloxane, and at least one catalyst, and use thereof.

Claims

1. A silane compound having the general formula (I)
SiR.sup.1.sub.n(R.sup.2).sub.4-n(I) wherein each R.sup.1 is same or different and is, independently of one another, selected from radicals having the general formula (II)
OCH(CH.sub.2COOR.sup.3)COXR.sup.3(II) wherein X is O or N, and each R.sup.3 is same or different and is, independently of one another, selected from the group consisting of substituted or unsubstituted, linear or branched alkyl radicals having from 1 to 22 carbon atoms, aryl radicals having from 6 to 16 carbon atoms, and cycloalkyl radicals having from 5 to 27 carbon atoms, where R.sup.3 may contain at least one heteroatom selected from O, N, Sand/or Si; each R.sup.2 is same or different and is, independently of one another, selected from the group consisting of a hydrogen atom, a hydroxyl group, substituted or unsubstituted monovalent hydrocarbon radicals having from 1 to 18 carbon atoms, and alkoxy radicals having from 1 to 8 carbon atoms; and n is 2, 3, or 4.

2. The silane compound according to claim 1, wherein R.sup.3 is selected from the group consisting of linear or branched alkyl radicals having from 1 to 22 carbon atoms and cycloalkyl radicals having from 5 to 27 carbon atoms.

3. The silane compound according to claim 1, wherein R.sup.3 is selected from the group consisting of a methyl, ethyl, propyl, and n-butyl radical.

4. The silane compound according to claim 1, wherein n is 3 or 4.

5. A method for preparing the silane compound having the general formula (I) according to claim 1, comprising: providing a silane having the general formula (III)
SiR.sup.4.sub.n(R.sup.2).sub.4-n(III); providing a compound having the general formula of
HOCH(CH.sub.2COOR.sup.3)COXR.sup.3; reacting the silane with n equivalents of the compound in an alcoholysis reaction in solvent and using at least one tertiary amine at room temperature, wherein each R.sup.4 is same or different and is, independently of one another, selected from the group consisting of alkoxy radicals having from 1 to 4 carbon atoms and Cl; R.sup.2 and n are the same as defined for the general formula (I) in claim 1; and R.sup.3 and X are the same as defined for the general formula (II) in claim 1.

6. The method according to claim 5, wherein the solvent is selected from the group consisting of diethyl ether, tetrahydrofuran, benzene, toluene, dichloromethane, chloroform, acetone, acetonitrile, 1,2-dichloroethane, 1,2-dimethoxy-ethane, N,N-dimethylformamide, 1,4-dioxane, dimethyl sulfoxide and combinations thereof.

7. The method according to claim 5, wherein the tertiary amine is selected from the group consisting of triethylamine, tri(n-propyl)amine, tri(i-propyl)amine, tri(n-butyl)amine, tri(tert-butyl)amine, 1-methylimidazole, pyridine, quinuclidine, 4-dimethylaminopyridine, 2,6-lutidine, 3,5-lutidine, N,N-dimethylaniline, 1,4-dimethylpiperazine, 1,3,5-trimethylhexahydro-1,3,5-triazine, N,N,N,N-tetramethyldiaminomethane and combinations thereof.

8. A crosslinker for a curable silicone composition comprising at least one silane compound having the general formula (I) according to claim 1.

9. An adhesion promoter for adhesives or sealants comprising at least one silane compound having the general formula (I) according to claim 1.

10. A curable composition comprising (A) at least one reaction product of: a) at least one polyorganosiloxane having at least one hydroxyl group, vinyl group, or hydrogen atom bound to a silicone atom; b) at least one silane compound having the general formula (I) according to claim 1; and c) at least one catalyst.

11. The curable composition according to claim 10, wherein (A) is the reaction product of a), b), c) and further d) at least one aminosilane.

12. The curable composition according to claim 10, wherein the polyorganosiloxane is a polydiorganosiloxane which has at least one, terminal hydroxyl group.

13. The curable composition according to claim 10, wherein the polyorganosiloxane is a polydiorganosiloxane which has at least two, terminal hydroxyl groups.

14. The curable composition according to claim 10, wherein the polyorganosiloxane is ,-dihydroxyl-terminated polyorganosiloxanes having the general formula (IV) ##STR00009## wherein R.sup.5 and R.sup.6 are same or different and are, independently of one another, selected from the group consisting of substituted or unsubstituted cyclic, linear or branched alkyl or alkenyl radicals having from 1 to 18 carbon atoms or aryl radicals having from 6 to 18 carbon atoms; and m is 10 to 10000.

15. The curable composition according to claim 10, further comprising (B) at least one curing catalyst.

16. An adhesive, sealant, spray foam and/or coating comprising the composition according to claim 10.

Description

EXAMPLE 1

Synthesis of Vinyl-Tri(Diethyl Malate)Silane (Formula 1)

(1) ##STR00006##

(2) In a 250 mL three-necked flask, vinyltrichlorosilane (3.23 g, 20 mmol) was added dropwise to the mixture of diethyl malate (11.41 g, 60 mmol), triethylamine (6.07 g, 60 mmol) in toluene (150 mL) under an atmosphere of argon at room temperature. After completion of the addition, the mixture was stirred overnight at room temperature, filtered and washed with toluene. The combined filtrates were distilled under vacuum to remove toluene and excess triethylamine. The product was afforded as a light yellow oil (11.6 g, yield: 93%).

EXAMPLE 2

Synthesis of Methyl-Tri(Diethyl Malate)Silane (Formula 3)

(3) ##STR00007##

(4) In a 250 mL three-necked flask, methyltrichlorosilane (2.99 g, 20 mmol) was added dropwise to the mixture of diethyl malate (11.41 g, 60 mmol), triethylamine (6.07 g, 60 mmol) in toluene (120 mL) under an atmosphere of argon at room temperature. After completion of the addition, the mixture was stirred overnight at room temperature, filtered and washed with toluene. The combined filtrates were distilled under vacuum to remove toluene and excess triethylamine. The product was afforded as a light yellow oil (10.9 g, yield: 89%).

EXAMPLE 3

Synthesis of Phenyl-Tri(Diethyl Malate)Silane (Formula 5)

(5) ##STR00008##

(6) In a 250 mL three-necked flask, phenyltrichlorosilane (4.23 g, 20 mmol) was added dropwise to the mixture of diethyl malate (11.41 g, 60 mmol), triethylamine (6.07 g, 60 mmol) in toluene (120 mL) under an atmosphere of argon at room temperature. After completion of the addition, the mixture was stirred overnight at room temperature, filtered and washed with toluene. The combined filtrates were distilled under vacuum to remove toluene and excess triethylamine. The product was afforded as a light yellow oil (11.9 g, yield: 89%).

EXAMPLES 4 TO 6 (E4 TO E6)

Preparation of Curable Compositions

(7) Curable compositions were prepared according to the following formulation: 5 g of ,-dihydroxyl-terminated polydimethylsiloxane with viscosity 20000 mPa.Math.s, 0.01 g of n-butyllithium (1.5M solutions in hexanes) and 0.02 g of dioctyltin dilaurate. In each case, 0.5 g of phenyl-tri(diethyl malate)silane, methyl-tri(diethyl malate)silane and vinyl-tri(diethyl malate)silane were added as crosslinkers for Examples 4, 5 and 6, respectively.

COMPARATIVE EXAMPLE 1 (C1)

(8) A curable composition was prepared with 5 g of ,-dihydroxyl-terminated polydimethylsiloxane with viscosity 20000 mPa.Math.s, 0.5 g of vinyltriethyllactatosilane, 0.1 g of n-butyllithium (1.5M solutions in hexanes) and 0.02 g of dioctyltin dilaurate.

(9) After exposure to air, the crosslinking properties including skin over time (SOT) and tack free time (TFT) were determined. The results are shown in Table 1.

(10) Test Method for Determining SOT and TFT

(11) SOT: The aforementioned compositions were homogenized and applied in a frame (501302 mm). Each mixture was evenly distributed so that the frame can be completely filled. A thin polymer film was thereby obtained. The time to form a skin (skin-over time/SOT) was determined for these compositions using a tool which has a rounded spatula at the tip (1505 mm). The tip of the spatula was gently contacted with the surface of the polymer film every 1 to 5 minutes and removed carefully. The SOT was measured once no more residue of the formulation remains on the spatula when removing it from the surface of the polymer film. Then, the resulting string must be removed from the spatula without residue. The polymer film returned to its original shape. In examining the SOT a different part of the surface of the polymer film must be used every time. The test was performed at room temperature.

(12) TFT: To determine surface tackiness from an adhesive sealing material, the aforementioned compositions were homogenized and applied in a frame (501302 mm) in the same way as the SOT Determination. After 60 minutes, the tackiness of the surface was evaluated using a tool which has a rounded spatula at the tip (1505 mm) by careful contact with the surface of the polymer film, TFT of <60 min indicates not tacky and of >60 min indicates tacky (including slightly tacky).

(13) TABLE-US-00001 TABLE 1 skin over time (min) tack free time (min) E4 33 >60 E5 32 <60 E6 10 <60 C1 35 <60

EXAMPLES 7 TO 9 (E7 TO E9)

(14) Curable compositions were prepared according to the following formulation: 5 g of ,-dihydroxyl-terminated polydimethylsiloxane with viscosity 20000 mPa.Math.s, 0.04 g of (3-aminopropyl)-trimethoxysilane, and 0.02 g dioctyltin dilaurate.

(15) In each case, 0.5 g of phenyl-tri(diethyl malate)silane, methyl-tri(diethyl malate)silane and vinyl-tri(diethyl malate)silane were added as crosslinkers for Examples 7, 8 and 9, respectively.

COMPARATIVE EXAMPLES 2 TO 5 (C2 TO C5)

(16) Comparative Example 2 (Alkoxy silicone): A curable composition was prepared according to the following formulation: 5 g of ,-dihydroxyl-terminated polydimethylsiloxane with viscosity 20000 mPa.Math.s, 0.5 g of vinyltrimethoxysilane, 0.01 g of buthyllithium (1.6M in hexanes), and 0.02 g of dioctyltin carboxylate.

(17) Comparative Example 3 (Acetoxy silicone): A curable composition was prepared according to the following formulation: 5 g of ,-dihydroxyl-terminated polydimethylsiloxane with viscosity 20000 mPa.Math.s, 0.5 g of ethyltriacetoxysilane, and 0.02 g of dioctyltin dilaurate.

(18) Comparative Example 4 (Lactate silicone): A curable composition was prepared according to the following formulation: 5 g of ,-dihydroxyl-terminated polydimethylsiloxane with viscosity 20000 mPa.Math.s, 0.04 g of (3-aminopropyl)-triethoxysilane, 0.5 g of vinyltriethyllactatosilane, and 0.02 g of dioctyltin dilaurate.

(19) Comparative Example 5 (Oxime silicone): A curable composition was prepared according to the following formulation: 5 g of ,-dihydroxyl-terminated polydimethylsiloxane with viscosity 80000 mPa.Math.s, 0.18 g of a mixture of propan-2-one-O,O(methoxyvinylsilandiyl)dioxime; propan-2-one-O-(dimethoxyvinylsilyl)oxime; propan-2-one-O,O,O-(vinylsilantriyl)trioxime, 0.09 g of vinyltris(methylethylketoxime)silane, 0.27 g of a mixture of propan-2-one-O,O(methoxyvinylsilandiyl)dioxime; propan-2-one-O-(dimethoxyvinylsilyl)oxime; propan-2-one-O,O,O-(vinylsilantriyl)trioxime, with vinyltris(methylethylketoxime)silane with 0.01 g of dimethyltin dineodecanoate.

(20) After exposure to air, the crosslinking properties including skin over time was determined according to the above-described methods. All measurements were carried out at room temperature. The results are shown in Table 2.

(21) TABLE-US-00002 TABLE 2 Skin over time (min) E7 60 E8 >120 E9 <5 C2 15 C3 15 C4 >120 C5 15