Process for the preparation of hydroxyl-functionalized polysiloxanes

Abstract

A method for producing a hydroxyl-functionalized polysiloxane having secondary or tertiary hydroxyl groups, said method comprising the steps of: i) reacting a hydroxyalkyl allyl ether having a secondary or tertiary alcohol group with a siloxane under anhydrous conditions and under transition metal catalysis, said hydroxylalkyl allyl ether conforming to Formula (I) ##STR00001## wherein n is 0, 1, 2, 3, 4 or 5, preferably 0; m is 1, 2, 3, 4 or 5, preferably 1; spacer group A is constituted by a covalent bond or a C.sub.1-C.sub.20 alkylene group; R.sup.1 is hydrogen, a C.sub.1-C.sub.8 alkyl group, a C.sub.3-C.sub.10 cycloalkyl group, a C.sub.6-C.sub.18 aryl group or an aralkyl group; R.sup.a, R.sup.b, R.sup.c, R.sup.d, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 may be the same or different and each is independently selected from hydrogen, a C.sub.1-C.sub.8 alkyl group, a C.sub.6-C.sub.18 aryl group or a C.sub.6-C.sub.18 aralkyl group, with the proviso that at least one of R.sup.3 and R.sup.4 is not hydrogen; and said siloxane conforming to Formula (II) ##STR00002## wherein m is 1, 2, 3, 4 or 5, preferably 1; R.sup.6, R.sup.7, R.sup.8 and R.sup.9 may be the same or different and each represent a C.sub.1-C.sub.8 alkyl group, a C.sub.3-C.sub.10 cycloalkyl group, a C.sub.6-C.sub.18 aryl group or a C.sub.6-C.sub.18 aralkyl group; and ii) in the presence of the reaction product of step i), performing a ring opening polymerization of at least one cyclic siloxane monomer.

Claims

1. A method for producing a hydroxyl-functionalized polysiloxane having secondary or tertiary hydroxyl groups, said method comprising the following steps in the following order: i) providing a hydroxyalkyl alkenyl ether having a secondary or tertiary alcohol group, the hydroxylalkyl alkenyl ether conforming to Formula (I) ##STR00019## wherein n is 0, 1, 2, 3, 4 or 5; m is 1, 2, 3, 4 or 5; A is a covalent bond or a C.sub.1-C.sub.12 alkylene group; R.sup.1 is selected from hydrogen, and a C.sub.1-C.sub.6 alkyl group; R.sup.a, R.sup.b, R.sup.c, R.sup.d, may be the same or different and each is independently selected from hydrogen, a C.sub.1-C.sub.8 alkyl group, a C.sub.6-C.sub.18 aryl group or a C.sub.6-C.sub.18 aralkyl group, R.sup.2, R.sup.3 and R.sup.5 are hydrogen; and R.sup.4 is a phenyl group; ii) providing a siloxane conforming to Formula (II) ##STR00020## wherein m is 1, 2, 3, 4 or 5; R.sup.6, R.sup.7, R.sup.8 and R.sup.9 may be the same or different and each is independently selected from a C.sub.1-C.sub.8 alkyl group, a C.sub.3-C.sub.10 cycloalkyl group, a C.sub.6-C.sub.18 aryl group or a C.sub.6-C.sub.18 aralkyl group; iii) reacting the hydroxyalkyl alkenyl ether having a secondary or tertiary alcohol group with the siloxane under anhydrous conditions and in the presence of a transition metal catalyst of which the transition metal is selected from Groups 8 to 10 of the Periodic Table to form a reaction product; and iv) in the presence of the purified product, performing a ring opening polymerization of at least one cyclic siloxane monomer having the general Formula (III) ##STR00021## wherein n is 3, 4, 5, 6, 7 or 8; R.sup.10 and R.sup.11 may the same or different and each is independently selected from hydrogen, a C.sub.1-C.sub.8 alkyl group, a C.sub.2-C.sub.8 alkenyl group, a C.sub.3-C.sub.10 cycloalkyl group, a C.sub.6-C.sub.18 aryl group or a C.sub.6-C.sub.18 aralkyl group.

2. The method according to claim 1, wherein in Formula (I): A is a covalent bond.

3. The method according to claim 1, wherein in Formula (II) each of R.sup.6, R.sup.7, R.sup.8 and R.sup.9 represents a C.sub.1-C.sub.4 alkyl group or a C.sub.5-C.sub.6 cycloalkyl group.

4. The method according to claim 1, wherein the transition metal catalyst comprises at least one metal selected from the group consisting of ruthenium, rhodium, palladium, osmium, iridium and platinum and further comprises a powdered support selected from the group consisting of alumina, silica and carbon.

5. The method according to claim 1, wherein in Formula (III) each of R.sup.10 and R.sup.11 independently represents a C.sub.1-C.sub.8 alkyl group.

6. The method according to claim 1, wherein the ring opening polymerization of step iv) is performed under acid catalysis and wherein said acid catalyst comprises one or more acids selected from the group consisting of: HCl; HBr; Hl; H.sub.2SO.sub.4; HClO.sub.4; para-toluenesulfonic acid; trifluoroacetic acid; perfluoroalkane sulfonic acids and combinations thereof.

7. A hydroxyl-functionalized polysiloxane obtained by the process according to claim 1.

8. The hydroxyl-functionalized polysiloxane obtained by the process according to claim 1 and having at least one of: a number average molecular weight (Mn) of from 5,000 to 100,000 g/mol; and a polydispersity index in the range from 1.0 to 2.5.

9. A composition comprising the hydroxyl-functionalized polysiloxane obtained by the process according to claim 1; and at least one compound having at least one hydroxyl group-reactive functionality.

10. A curable composition comprising the hydroxyl-functionalized polysiloxane according to claim 7 as a reactive component and further comprising at least one compound having at least one hydroxyl group-reactive functionality.

11. A silylated polymer that is the reaction product of a mixture comprising: a hydroxyl-functionalized polysiloxane having secondary or tertiary hydroxyl groups, that is the reaction product of a method comprising the steps of: i) providing a hydroxyalkyl alkenyl ether having a secondary or tertiary alcohol group, the hydroxylalkyl alkenyl ether conforming to Formula (I) ##STR00022## wherein n is 0, 1, 2, 3, 4 or 5; m is 1, 2, 3, 4 or 5; A denotes a spacer group which is constituted by a covalent bond or a C.sub.1-C.sub.20 alkylene group; R.sup.1 is selected from hydrogen, a C.sub.1-C.sub.8 alkyl group, a C.sub.3-C.sub.10 cycloalkyl group, a C.sub.6-C.sub.18 aryl group or a C.sub.6-C.sub.18 aralkyl group; R.sup.a, R.sup.b, R.sup.c, R.sup.d, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 may be the same or different and each is independently selected from hydrogen, a C.sub.1-C.sub.8 alkyl group, a C.sub.6-C.sub.18 aryl group or a C.sub.6-C.sub.18 aralkyl group, with the proviso that at least one of R.sup.3 and R.sup.4 is not hydrogen; ii) providing a siloxane conforming to Formula (II) ##STR00023## wherein m is 1, 2, 3, 4 or 5; R.sup.6, R.sup.7, R.sup.8 and R.sup.9 may be the same or different and each is independently selected from a C.sub.1-C.sub.8 alkyl group, a C.sub.3-C.sub.10 cycloalkyl group, a C.sub.6-C.sub.18 aryl group or a C.sub.6-C.sub.18 aralkyl group; iii) reacting the hydroxyalkyl alkenyl ether having a secondary or tertiary alcohol group with the siloxane under anhydrous conditions and in the presence of a transition metal catalyst of which the transition metal is selected from Groups 8 to 10 of the Periodic Table to provide a reaction product; and iv) in the presence of the reaction product of step iii), performing a ring opening polymerization of at least one cyclic siloxane monomer having the general Formula (III) ##STR00024## wherein n is 3, 4, 5, 6, 7 or 8; R.sup.10 and R.sup.11 may the same or different and each is independently selected from hydrogen, a C.sub.1-C.sub.8 alkyl group, a C.sub.2-C.sub.8 alkenyl group, a C.sub.3-C.sub.10 cycloalkyl group, a C.sub.6-C.sub.18 aryl group or a C.sub.6-C.sub.18 aralkyl group; and at least one isocyanatosilane of Formula (VI):
OCN—B—Si—(X).sub.m(R.sup.12).sub.3-m   (VI) wherein: m is 0, 1 or 2; each R.sup.12 is independently selected from a hydroxyl group, a C.sub.1-C.sub.10 alkoxy group, a C.sub.1-C.sub.10 acyloxy group, or —OCH(R.sup.13)COOR.sup.14, wherein R.sup.13 is selected from hydrogen or a C.sub.1-C.sub.4 alkyl group; and R.sup.14 is selected from a C.sub.1-C.sub.8 alkyl group; each X is independently selected from a C.sub.1-C.sub.8 alkyl group which can optionally be interrupted by at least one heteroatom; and B is selected from a C.sub.1-C.sub.20 alkylene group.

12. A silylated polymer that is the reaction product of: an NCO-terminated prepolymer that is the reaction product of a hydroxyl-functionalized polysiloxane having secondary or tertiary hydroxyl groups, that is the reaction product of a method comprising the steps of: i) providing a hydroxyalkyl alkenyl ether having a secondary or tertiary alcohol group, the hydroxylalkyl alkenyl ether conforming to Formula (I) ##STR00025## wherein n is 0, 1, 2, 3, 4 or 5; m is 1, 2, 3, 4 or 5; A denotes a spacer group which is constituted by a covalent bond or a C.sub.1-C.sub.20 alkylene group; R.sup.1 is selected from hydrogen, a C.sub.1-C.sub.8 alkyl group, a C.sub.3-C.sub.10 cycloalkyl group, a C.sub.6-C.sub.18 aryl group or a C.sub.6-C.sub.18 aralkyl group; R.sup.a, R.sup.b, R.sup.c, R.sup.d, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 may be the same or different and each is independently selected from hydrogen, a C.sub.1-C.sub.8 alkyl group, a C.sub.6-C.sub.18 aryl group or a C.sub.6-C.sub.18 aralkyl group, with the proviso that at least one of R.sup.3 and R.sup.4 is not hydrogen; ii) providing a siloxane conforming to Formula (II) ##STR00026## wherein m is 1, 2, 3, 4 or 5; R.sup.6, R.sup.7, R.sup.8 and R.sup.9 may be the same or different and each is independently selected from a C.sub.1-C.sub.8 alkyl group, a C.sub.3-C.sub.10 cycloalkyl group, a C.sub.6-C.sub.18 aryl group or a C.sub.6-C.sub.18 aralkyl group; iii) reacting the hydroxyalkyl alkenyl ether having a secondary or tertiary alcohol group with the siloxane under anhydrous conditions and in the presence of a transition metal catalyst of which the transition metal is selected from Groups 8 to 10 of the Periodic Table to provide a reaction product; and iv) in the presence of the reaction product of step iii), performing a ring opening polymerization of at least one cyclic siloxane monomer having the general Formula (III) ##STR00027## wherein n is 3, 4, 5, 6, 7 or 8; R.sup.10 and R.sup.11 may the same or different and each is independently selected from hydrogen, a C.sub.1-C.sub.8 alkyl group, a C.sub.2-C.sub.8 alkenyl group, a C.sub.3-C.sub.10 cycloalkyl group, a C.sub.6-C.sub.18 aryl group or a C.sub.6-C.sub.18 aralkyl group; with at least one polyisocyanate, wherein there is a stoichiometric excess of the NCO groups of the polyisocyanate with respect to the OH groups of the hydroxyl-functionalized polysiloxane; and at least one silane having at least one NCO group-reactive functionality.

13. A curable composition comprising the silylated polymer as defined in claim 12.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 appended hereto illustrates a reaction scheme in accordance with this illustrative embodiment of the present invention.

COMPOSITIONS AND APPLICATIONS OF THE HYDROXYL-FUNCTIONALIZED POLYSILOXANES

(2) It is anticipated that the hydroxyl-functionalized polysiloxanes of the present invention per se may find utility as a curable, crosslinkable or otherwise reactive component of a coating composition, a sealant composition or an adhesive composition, such as a pressure sensitive adhesive composition. Said compositions may comprise, in addition to the hydroxyl-functionalized polysiloxanes, at least one compound having at least one hydroxyl group-reactive functionality, preferably selected from isocyanate groups, cyano groups, melamine groups, epoxy groups, acrylate groups, methacrylate groups, ester groups, carbonate groups, cyclocarbonate groups, carboxylic acid groups or anhydride groups, more preferably isocyanate groups, may be mentioned as illustrative further components of the compositions.

(3) The present invention also provides a silylated polymer based on the hydroxyl-functionalized polysiloxane.

(4) In a preferred embodiment of the present invention, the silylated polymer may be obtained by reacting (i.e., end-capping) the hydroxyl-functionalized polysiloxanes with isocyanatosilane and for the inclusion of said silylated polymer in a curable composition, such as a curable coating, sealant or adhesive composition. Commonly, to form a silylated prepolymer, the hydroxyl-functionalized polysiloxanes may be reacted with at least one isocyanatosilane of Formula (VI):
OCN—B—Si—(X).sub.m(R.sup.12).sub.3-m  (VI)
wherein m is 0, 1 or 2, preferably 0 or 1; each R.sup.12 is independently selected from a hydroxyl group, a C.sub.1-C.sub.10 alkoxy group, a C.sub.1-C.sub.10 acyloxy group, or —OCH(R.sup.13)COOR.sup.14, wherein R.sup.13 is selected from hydrogen or a C.sub.1-C.sub.4 alkyl group; and R.sup.14 is selected from a C.sub.1-C.sub.8 alkyl group; each X is independently selected from a C.sub.1-C.sub.8 alkyl group which can optionally be interrupted by at least one heteroatom; and B is selected from a C.sub.1-C.sub.20 alkylene group. Preferably each R.sup.12 is independently selected from a C.sub.1-C.sub.4 alkoxy or acyloxy group and, more preferably, each R.sup.12 is independently selected from a methoxy or ethoxy group.

(5) As an exemplary, but non-limiting, list of compounds meeting Formula (VI), the following may be mentioned: 3-isocyanatopropyltrimethoxysilane, 2-isocyanatoisopropyltrimethoxysilane, 4-isocyanato-n-butyltrimethoxysilane, 2-isocyanato-1,1-dimethylethyltrimethoxysilane, 1-isocyanato-methyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 2-isocyanato-2-methylethyl-triethoxysilane, 4-isocyanatobutyltriethoxy-silane, 2-isocyanato-1,1-dimethylethyl-triethoxysilane, 1-isocyanatomethyltriethoxysilane, 3-isocyanatopropylmethyldimethoxysilane, 3-isocyanatopropyld imethylmethoxysilane, 3-isocyanatopropylphenylmethylmethoxysilane, 1-isocyanatomethylmethyldimethoxysilane, 3-isocyanatopropylethyldiethoxysilane, 3-isocyanatopropylmethyldiethoxysilane and 1-isocyanatomethylmethyldiethoxysilane. These compounds may be reacted with the hydroxyl-functionalized polysiloxanes either alone or in admixture.

(6) The end-capping reaction may be performed under catalysis, with suitable catalysts being well-known to a person of ordinary skill in the art. In principle, any compound that can catalyze the reaction of a hydroxyl group and an isocyanato group to form a urethane bond can be used. And examples thereof include: tin carboxylates such as dibutyltin dilaurate (DBTL), dibutyltin diacetate, dibutyltin diethylhexanoate, dibutyltin dioctoate, dibutyltin dimethylmaleate, dibutyltin diethylmaleate, dibutyltin dibutylmaleate, dibutyltin diiosooctylmaleate, dibutyltin ditridecylmaleate, dibutyltin dibenzylmaleate, dibutyltin maleate, dibutyltin diacetate, tin octaoate, dioctyltin distearate, dioctyltin dilaurate (DOTL), dioctyltin diethylmaleate, dioctyltin diisooctylmaleate, dioctyltin diacetate, and tin naphthenoate; tin alkoxides such as dibutyltin dimethoxide, dibutyltin diphenoxide, and dibutyltin diisoproxide; tin oxides such as dibutyltin oxide and dioctyltin oxide; reaction products between dibutyltin oxides and phthalic acid esters; dibutyltin bisacetylacetonate; titanates such as tetrabutyl titanate and tetrapropyl titanate; organoaluminum compounds such as aluminum trisacetylacetonate, aluminum trisethylacetoacetate, and diisopropoxyaluminum ethylacetoacetate; chelate compounds such as zirconium tetraacetylacetonate and titanium tetraacetylacetonate; lead octanoate; amine compounds or salts thereof with carboxylic acids, such as butylamine, octylamine, laurylamine, dibutylamines, monoethanolamines, diethanolamines, triethanolamine, diethylenetriamine, triethylenetetramine, oleylamines, cyclohexylamine, benzylamine, diethylaminopropylamine, xylylenediamine, triethylenediamine, guanidine, diphenylguanidine, 2,4,6-tris(dimethylaminomethyl)phenol, morpholine, N-methylmorpholine, 2-ethyl-4-methylimidazole and 1,8-diazabicyclo-(5,4,0)-undecene-7 (DBU); aliphatic carboxylate salts or acetylacetonates of potassium, iron, indium, zinc, bismuth, or copper.

(7) In another preferred embodiment, the silylated polymer may be obtained by reacting the hydroxyl-functionalized polysiloxane with at least one polyisocyanate, preferably diisocyanate, with a stoichiometric excess of the NCO groups of the polyisocyanate with respect to the OH groups of the hydroxyl-functionalized polysiloxane to form a NCO-terminated prepolymer; and reacting the NCO-terminated prepolymer with at least one silane having at least one NCO group-reactive functionality. Preferably the silane having at least one NCO group-reactive functionality conforms to Formula (VII):
R.sup.15R.sup.16N—R.sup.17—SiXYZ  (VII)
wherein R.sup.15 and R.sup.16 are independently selected from hydrogen or a C.sub.1-C.sub.8 alkyl group; R.sup.17 is a divalent hydrocarbon residue having 1 to 12 carbon atoms, optionally comprising at least one heteroatom, preferably N or O; and X, Y, Z are independently selected from a hydroxyl group, a C.sub.1-C.sub.8 alkyl group, a C.sub.1-C.sub.8 alkoxy group or a C.sub.1-C.sub.8 acyloxy group, at least one of the substituents X, Y, Z being selected from a C.sub.1-C.sub.8 alkoxy or a C.sub.1-C.sub.8 acyloxy group. The linking group R.sup.17 can, for example, be a linear, branched or cyclic, substituted or unsubstituted alkylene residue. Nitrogen (N) or oxygen (O) may be contained therein as a heteroatom. If X, Y and/or Z are an acyloxy group, this can be e.g., the acetoxy group —OCO—CH.sub.3.

(8) The polyisocyanates suitable for preparing the NCO-terminated prepolymer include ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,4-tetramethoxybutane diisocyanate, 1,6-hexamethylene diisocyanate (HDI), cyclobutane-1,3-diisocyanate, cyclohexane-1,3- and -1,4-diisocyanate, bis(2-isocyanatoethyl)fumarate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 2,4- and 2,6-hexahydrotoluylene diisocyanate, hexahydro-1,3- or -1,4-phenylene diisocyanate, benzidine diisocyanate, naphthalene-1,5-diisocyanate, 1,6-diisocyanato-2,2,4-trimethylhexane, 1,6-diisocyanato-2,4,4-trimethylhexane, xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), 1,3- and 1,4-phenylene diisocyanate, 2,4- or 2,6-toluylene diisocyanate (TDI), 2,4′-diphenylmethane diisocyanate, 2,2′-diphenylmethane diisocyanate, or 4,4′-diphenylmethane diisocyanate (MDI), and the isomeric mixtures thereof. Also suitable are partially or completely hydrogenated cycloalkyl derivatives of MDI, for example completely hydrogenated MDI (H.sub.12-MDI), alkyl-substituted diphenylmethane diisocyanates, for example mono-, di-, tri-, or tetraalkyldiphenylmethane diisocyanate and the partially or completely hydrogenated cycloalkyl derivatives thereof, 4,4′-diisocyanatophenylperfluorethane, phthalic acid-bis-isocyanatoethyl ester, 1 chloromethylphenyl-2,4- or -2,6-diisocyanate, 1-bromomethylphenyl-2,4- or -2,6-diisocyanate, 3,3′-bis-chloromethyl ether-4,4′-diphenyl diisocyanate, sulfur-containing diisocyanates such as those obtainable by reacting 2 moles diisocyanate with 1 mole thiodiglycol or dihydroxydihexyl sulfide, diisocyanates of dimer fatty acids, or mixtures of two or more of the named diisocyanates. The polyisocyanate is preferably IPDI, TDI or MDI.

(9) Other polyisocyanates suitable for use in accordance with the invention are isocyanates with a functionality of three or more obtainable, for example, by oligomerization of diisocyanates, more particularly by oligomerization of the isocyanates mentioned above. Examples of such tri- and higher isocyanates are the triisocyanurates of HDI or IPDI or mixtures thereof or mixed triisocyanurates thereof and polyphenyl methylene polyisocyanate obtainable by phosgenation of aniline/formaldehyde condensates.

(10) According to the invention, there is a stoichiometric excess of NCO groups of the polyisocyanates with respect to OH groups of the hydroxyl-functionalized polysiloxanes. The ratio of the number of OH groups of the hydroxyl-functionalized polysiloxanes to the number of NCO groups of the polyisocyanates is particularly preferably 1:3 to 1:1.1, in particular 1:2.5 to 1:1.5.

(11) A curable composition, such as a coating, sealant or adhesive composition comprising either the hydroxyl-functionalized polysiloxanes or the silylated polymer(s) obtained therefrom will typically further comprise adjuvants and additives that can impart improved properties to these compositions. For instance, the adjuvants and additives may impart one or more of: improved elastic properties; improved elastic recovery; longer enabled processing time; faster curing time; and, lower residual tack. Included among such adjuvants and additives are catalysts, plasticizers, stabilizers, antioxidants, fillers, reactive diluents, drying agents, adhesion promoters and UV stabilizers, fungicides, flame retardants, rheological adjuvants, color pigments or color pastes, and/or optionally also, to a small extent, solvents.

(12) A “plasticizer” for the purposes of this invention is a substance that decreases the viscosity of the composition and thus facilitates its processability. Herein the plasticizer may constitute up to 40 wt. % or up to 20 wt. %, based on the total weight of the composition, and is preferably selected from the group consisting of: polydimethylsiloxanes (PDMS); diurethanes; ethers of monofunctional, linear or branched C4-C16 alcohols, such as Cetiol OE (obtainable from Cognis Deutschland GmbH, Düsseldorf); esters of abietic acid, butyric acid, thiobutyric acid, acetic acid, propionic acid esters and citric acid; esters based on nitrocellulose and polyvinyl acetate; fatty acid esters; dicarboxylic acid esters; esters of OH-group-carrying or epoxidized fatty acids; glycolic acid esters; benzoic acid esters; phosphoric acid esters; sulfonic acid esters; trimellitic acid esters; epoxidized plasticizers; polyether plasticizers, such as end-capped polyethylene or polypropylene glycols; polystyrene; hydrocarbon plasticizers; chlorinated paraffin; and, mixtures thereof. It is noted that, in principle, phthalic acid esters can be used as the plasticizer but these are not preferred due to their toxicological potential. It is preferred that the plasticizer comprises or consists of one or more polydimethylsiloxane (PDMS).

(13) “Stabilizers” for purposes of this invention are to be understood as antioxidants, UV stabilizers or hydrolysis stabilizers. Herein stabilizers may constitute in toto up to 10 wt. % or up to 5 wt. %, based on the total weight of the composition. Standard commercial examples of stabilizers suitable for use herein include sterically hindered phenols and/or thioethers and/or substituted benzotriazoles and/or amines of the hindered amine light stabilizer (HALS) type. It is preferred in the context of the present invention that a UV stabilizer that carries a silyl group—and becomes incorporated into the end product upon crosslinking or curing—be used: the products Lowilite™ 75, Lowilite™ 77 (Great Lakes, USA) are particularly suitable for this purpose. Benzotriazoles, benzophenones, benzoates, cyanoacrylates, acrylates, sterically hindered phenols, phosphorus and/or sulfur can also be added.

(14) The curable compositions may further comprise up to 5 wt. %, for example from 0.01 to 3 wt. %, based on the total weight of the composition, of catalyst. The catalysts that can be used are all known compounds that can catalyze hydrolytic cleavage of the hydrolyzable groups of the silane groupings, as well as the subsequent condensation of the Si—OH group to yield siloxane groupings (crosslinking reaction and adhesion promotion function). Examples of catalysts, which can be used alone or in combination, include: titanates, such as tetrabutyl titanate and tetrapropyl titanate; tin carboxylates such as dibutyltin dilaurate (DBTL), dibutyltin diacetate, dibutyltin diethylhexanoate, dibutyltin dioctoate, dibutyltin dimethylmaleate, dibutyltin diethylmaleate, dibutyltin dibutylmaleate, dibutyltin diiosooctylmaleate, dibutyltin ditridecylmaleate, dibutyltin dibenzylmaleate, dibutyltin maleate, dibutyltin diacetate, tin octaoate, dioctyltin distearate, dioctyltin dilaurate (DOTL), dioctyltin diethylmaleate, dioctyltin diisooctylmaleate, dioctyltin diacetate, and tin naphthenoate; tin alkoxides such as dibutyltin dimethoxide, dibutyltin diphenoxide, and dibutyltin diisoproxide; tin oxides, such as dibutyltin oxide and dioctyltin oxide; reaction products between dibutyltin oxides and phthalic acid esters; dibutyltin bisacetylacetonate; organoaluminum compounds, such as aluminum trisacetylacetonate, aluminum trisethylacetoacetate, and diisopropoxyaluminum ethylacetoacetate; chelate compounds, such as zirconium tetraacetylacetonate and titanium tetraacetylacetonate; lead octanoate; amine compounds or salts thereof with carboxylic acids, such as butylamine, octylamine, laurylamine, dibutylamines, monoethanolamines, diethanolamines, triethanolamine, diethylenetriamine, triethylenetetramine, oleylamines, cyclohexylamine, benzylamine, diethylaminopropylamine, xylylenediamine, triethylenediamine, guanidine, diphenylguanidine, 2,4,6-tris(dimethylaminomethyl)phenol, morpholine, N-methylmorpholine, 2-ethyl-4-methylimidazole and 1,8-diazabicyclo-(5,4,0)-undecene-7 (DBU); a low-molecular-weight polyamide resin obtained from an excess of a polyamine and a polybasic acid; adducts of a polyamine in excess with an epoxy; and, silane adhesion promoters having amino groups, such as 3-aminopropyltrimethoxysilane and N-(β-aminoethyl)aminopropylmethyldimethoxysilane.

(15) As noted, the curable compositions according to the present invention can additionally contain fillers. Suitable here are, for example, chalk, lime powder, precipitated and/or pyrogenic silicic acid, zeolites, bentonites, magnesium carbonate, diatomite, alumina, clay, talc, titanium oxide, iron oxide, zinc oxide, sand, quartz, flint, mica, glass powder, and other ground mineral substances. Organic fillers can also be used, in particular carbon black, graphite, wood fibers, wood flour, sawdust, cellulose, cotton, pulp, cotton, wood chips, chopped straw, chaff, ground walnut shells, and other chopped fibers. Short fibers such as glass fibers, glass filament, polyacrylonitrile, carbon fibers, Kevlar fibers, or polyethylene fibers can also be added. Aluminum powder is likewise suitable as a filler.

(16) The pyrogenic and/or precipitated silicic acids advantageously have a BET surface area from 10 to 90 m.sup.2/g. When they are used, they do not cause any additional increase in the viscosity of the composition according to the present invention, but do contribute to strengthening the cured composition.

(17) It is likewise conceivable to use pyrogenic and/or precipitated silicic acids having a higher BET surface area, advantageously from 100 to 250 m.sup.2/g, in particular from 110 to 170 m.sup.2/g, as a filler: because of the greater BET surface area, the effect of strengthening the cured composition is achieved with a smaller proportion by weight of silicic acid.

(18) Also suitable as fillers are hollow spheres having a mineral shell or a plastic shell. These can be, for example, hollow glass spheres that are obtainable commercially under the trade names Glass Bubbles®. Plastic-based hollow spheres, such as Expancel® or Dualite®, may be used and are described in EP 0 520 426 B1: they are made up of inorganic or organic substances and each have a diameter of 1 mm or less, preferably 500 μm or less.

(19) Fillers which impart thixotropy to the composition may be preferred for many applications: such fillers are also described as rheological adjuvants, e.g. hydrogenated castor oil, fatty acid amides, or swellable plastics such as PVC.

(20) The total amount of fillers present in the compositions of the present invention will preferably be from 1 to 80 wt. %, and more preferably from 5 to 60 wt. %, based on the total weight of the composition. The desired viscosity of the curable composition will typically be determinative of the total amount of filler added and it is submitted that in order to be readily extrudable out of a suitable dispensing apparatus—such as a tube—the curable compositions should possess a viscosity of from 3000 to 150,000, preferably from 40,000 to 80,000 mPas, or even from 50,000 to 60,000 mPas.

(21) Examples of suitable pigments are titanium dioxide, iron oxides, or carbon black.

(22) In order to enhance shelf life even further, it is often advisable to further stabilize the compositions of the present invention with respect to moisture penetration through using drying agents. A need also occasionally exists to lower the viscosity of an adhesive or sealant composition according to the present invention for specific applications, by using reactive diluent(s). The total amount of reactive diluents present will typically be up to 15 wt. %, and preferably from 1 and 5 wt. %, based on the total weight of the composition.

(23) All compounds that are miscible with the adhesive or sealant with a reduction in viscosity, and that possess at least one group that is reactive with the polymeric binder, can be used as reactive diluents. The following substances can be used, for example, as reactive diluents: polyalkylene glycols reacted with isocyanatosilanes (e.g. Synalox 100-50B, Dow); carbamatopropyltrimethoxysilane; alkyltrimethoxysilane, alkyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, and vinyltrimethoxysilane (VTMO Geniosil XL 10, Wacker), vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, octyltrimethoxysilane, tetraethoxysilane, vinyldimethoxymethylsilane (XL12, Wacker), vinyltriethoxysilane (GF56, Wacker), vinyltriacetoxysilane (GF62, Wacker), isooctyltrimethoxysilane (IO Trimethoxy), isooctyltriethoxysilane (IO Triethoxy, Wacker), N-trimethoxysilylmethyl-O-methyl carbamate (XL63, Wacker), N-dimethoxy(methyl)silylmethyl-O-methyl carbamate (XL65, Wacker), hexadecyltrimethoxysilane, 3-octanoylthio-1-propyltriethoxysilane, and partial hydrolysates of the aforementioned compounds.

(24) Also usable as reactive diluents are the following polymers of Kaneka Corp.: MS S203H, MS S303H, MS SAT 010, and MS SAX 350. Silane-modified polymers that are derived, for example, from the reaction of isocyanatosilane with Synalox (Dow) grades can likewise be used.

(25) In the same manner, the silylated or end-capped polymers according to the present invention can be used in a mixture with usual polymers or pre-polymers known per se, optionally with concurrent use of the aforementioned reactive diluents, fillers, and further adjuvants and additives. “Usual polymers or pre-polymers” can be selected in this context from polyesters, polyoxyalkylenes, polyacrylates, polymethacrylates, or mixtures thereof; these can be free of groups reactive with siloxane groups, but optionally can also comprise alkoxysilyl groups or hydroxyl groups.

(26) A plurality of the aforementioned silane-functional reactive diluents have at the same time a drying and/or adhesion-promoting effect in the composition. Also suitable as adhesion promoters, however, are so-called tackifying agents of which examples include: hydrocarbon resins; phenol resins; terpene-phenolic resins; resorcinol resins or derivatives thereof; modified or unmodified rosin acids or rosin esters (abietic acid derivatives); polyamines; polyaminoamides; anhydrides; and, anhydride-containing copolymers. The addition of polyepoxide resins in small quantities can also improve adhesion on many substrates: solid epoxy resins having a molecular weight of over 700, provided in finely ground form, are then preferably used for this. If tackifying agents are used as adhesion promoters, their nature and quantity depend on the adhesive/sealant composition and on the substrate onto which it is applied. Typical tackifying resins (tackifiers) such as, for example, terpene-phenolic resins or resin acid derivatives, may be used in concentrations of from 5 to 20 wt. %; typical adhesion promoters, such as polyamines, polyaminoamides, phenolic resins or resorcinol derivatives may be used in the range from 0.1 to 10 wt. %, based on the total weight of the composition.

(27) Various features and embodiments of the disclosure are described in the following examples, which are intended to be representative and not limiting.

EXAMPLES

Synthesis Example 1: Synthesis of 2-Hydroxy-Propylallylether

(28) Allylic alcohol and propylene oxide were reacted in a ratio of 1.5 to 1. To this end, 1.463 g of sodium were dissolved in 184 g of the alcohol while externally cooling the stirred mixture with ice. The obtained solution was placed in an autoclave, heated to 110° C. and propylene oxide was added at a rate of 1.25 g/min. After complete addition the mixture was allowed to cool to room temperature and stirred overnight. 37% hydrochloric acid was added (6.25 g) to the resultant mixture and stirred for 10 minutes. The raw product was then filtered through Silica/Diatomite. The filtrate was collected and dried over Na.sub.2SO.sub.4 and then filtered again. To obtain the desired product, the mixture was distilled over a packed body column and the product collected at a temperature between 82 and 92° C. and a pressure of from 96 to 105 mbar. The average yield of 2-hydroxy-propylallylether was 60%. The compound contains trace amounts of 2-(allyloxy)propan-1-ol.

Synthesis Example 2: Synthesis of 1,3-(2′-Hydroxypropoxypropyl)-1,1,3,3-tetramethyldisiloxane

(29) 80.6 g of 1,1,3,3-tetramethyldisiloxane were dissolved in 600 mL of dry toluene, externally cooled with crushed ice to 10° C. and 400 mg of 5 wt % platinum on carbon was added. 2-Hydroxy-propylallylether (139.4 g)—as obtained from Synthesis Example 1—was added dropwise over a period of 30 minutes. The temperature of the reaction mixture was raised to 100° C. over a period of 5 hours and held at this temperature for a further 12 hours. The resultant mixture was finally refluxed for two hours. Then 250 mL of heptane and active charcoal were added and the mixture again warmed to reflux for 1.5 hours. After cooling the solution was filtered through Silica/Diatomite and the solvent was stripped off under reduced pressure; the product was finally held at 50 mbar pressure and 90° C. for 12 hours to obtain 181.6 g of the desired product.

Example 1: Synthesis of Polymer 1

(30) 800 g of octamethycylcotetrasiloxane (D.sub.4), 1.51 g of 1,1,3,3-tetramethyl-disiloxane and 400 μl of triflic acid were placed in a 2 litre reactor (SYSTAG FlexyPAT) equipped with an anchor agitator and heated at 90° C. for 2 hours under stirring. The mixture was quenched with 12.8 g of NaHCO.sub.3 and stirred for 30 minutes at 90° C. At 3 bar pressure, the crude product was filtered through a PALL Filter EDF 14-2 with a filter insert Begerow BECO KD5. The residual D.sub.4 was removed in a thin film evaporator at 120° C. and 2 mbar (200 rpm/200 g/h). The polymer obtained was analyzed by GPC analysis and found to have: a number average molecular weight (Mn) of 82413 g/mol; a weight average molecular weight (Mw) of 125264 gmol-1; a peak molecular weight (Mp) of 121511 gmol-1; and, a Polydispersity Index of 1.52.

Example 2: Synthesis of Polymer 2

(31) 800 g of octamethycylcotetrasiloxane (D.sub.4), 5.14 g of 1,3-(2′-Hydroxypropoxypropyl)-1,1,3,3-tetramethyl-disiloxane, as obtained from Synthesis Example 2 above, and 400 μl of triflic acid were placed in a 2 litre reactor (SYSTAG FlexyPAT) equipped with an anchor agitator and heated at 90° C. for 2 hours under stirring. The mixture was quenched with 12.8 g of NaHCO.sub.3 and stirred for 30 minutes at 90° C. At 3 bar pressure, the crude product was filtered through a PALL Filter EDF 14-2 with a filter insert Begerow BECO KD5. The residual D4 was removed in a thin film evaporator at 120° C. and 2 mbar (200 rpm/200 g/h). The polymer obtained was analyzed by GPC analysis and found to have: a number average molecular weight (Mn) of 72932 g/mol; a weight average molecular weight (Mw) of 115717 gmol-1; a peak molecular weight (Mp) of 116142 gmol-1; and, a Polydispersity Index of 1.59.

Example 3: Synthesis of Polymer 3

(32) 500 g of the Si—H terminated Polymer 1 were dissolved in 600 g of dry toluene and placed in 2 litre reactor (SYSTAG FlexyPAT) equipped with an anchor agitator. 0.11 g of 5 wt % Platinum on silica were added and the temperature of the reaction mixture was raised to 40° C. and maintained there for 1 hour before it was raised again to 80° C. and held for an additional 17 hours. Finally, the mixture was refluxed at 120° C. for 2 hours before it was allowed to cool down to room temperature. After cooling, the solution was filtered through a PALL Filter Typ EDF 14-2 with filter insert Begerow BECO KD5 at 3 bar pressure and the solvent was stripped off in a thin film evaporator at 80° C. and 100 mbar. The polymer was analyzed by GPC analysis and found to have: a number average molecular weight (Mn) of 81218 gmol-1; a weight average molecular weight (Mw) of 125078 gmol-1; a peak molecular weight (Mp) of 122191 gmol-1; and, a Polydispersity of 1.54.

Example 4: Synthesis of Polymer 4

(33) 487 g of Polymer 2 were dried in a 500 ml three-neck flask at 80° C. under vacuum. Under a nitrogen atmosphere at 80° C., 0.15 g of dibutyltin dilaurate was added followed by 3.1 g 3-isocyanatopropyltrimethoxysilane (% NCO=19.75). After stirring for two hours at 80° C., the resulting polymer was cooled. After adding 9.75 g Geniosil® XL 10 (vinyltrimethoxysilane, available from Wacker Chemie) to the reactor while stirring and homogenizing for 10-30 minutes at 80° C., the resulting polymer was stored in a moisture-proof glass vessel under a nitrogen atmosphere before being processed further into a curable composition.

Example 5: Synthesis of Polymer 5

(34) 371 g of Polymer 3 were dried in a 500 ml three-neck flask at 80° C. under vacuum. Under a nitrogen atmosphere at 80° C., 0.11 g of dibutyltin dilaurate was added followed by 1.69 g 3-isocyanatopropyltrimethoxysilane (% NCO=19.75). After stirring for two hours at 80° C., the resulting polymer was cooled. After adding 7.41 g Geniosil® XL 10 to the reactor while stirring and homogenizing for 10-30 minutes at 80° C., the resulting polymer was stored in a moisture-proof glass vessel under a nitrogen atmosphere before being processed further into a curable composition.

Example 6: Formulations

(35) Polymer 4 as described above was used to prepare Formulation A. Analogously, Polymer 5 was employed to prepare Formulation B. These two formulations are described in Table 1 herein below.

(36) TABLE-US-00001 TABLE 1 Formulation B - Formulation A Comparative Raw material (Parts by Weight) (Parts by Weight) Polymer 4 39.25 Polymer 5 39.25 Polydimethylsiloxane 11.32 11.32 plasticiser Polyether Polyol as a 0.31 0.31 rheology modifier Chalk (calcium carbonate) 41.30 41.30 Highly dispersed silicic 5.00 5.00 acid specific surface area 150 Vinyltrimethoxysilane 1.34 1.34 Catalyst (nBu).sub.4Ti 1.48 1.48
Adhesion and Mechanical Tests were performed on said formulations.
6.1 Measurement of Skin Over Time

(37) The determination of the skin overtime is carried out under standard climate conditions (23+/−2° C., relative humidity 50+/−5%). The temperature of the formulation must be 23+/−2° C., with the sealant stored for at least 24 hour beforehand in the laboratory. The formulation is applied to a sheet of paper and spread out with a putty knife to form a skin (thickness approximately 2 mm, width approximately 7 cm). A stopwatch is started immediately. At intervals, the surface is touched lightly with the fingertip and the finger is pulled away, with sufficient pressure on the surface that an impression remains on the surface when the skin over time is reached. The skin over time is reached when sealing compound no longer adheres to the fingertip. The skin over time is expressed in minutes.

(38) 6.2 Measurement of Shore A Hardness

(39) The procedure is carried out in accordance with ISO 868.

(40) 6.3 Measurement of Mechanical Properties (Tensile Test)

(41) The breaking strength, elongation at break, and tensile stress values (modulus of elasticity) are determined by the tensile test in accordance with DIN 53504.

(42) Deviation from the norm: Dumbbell test specimens having the following dimensions are used as test pieces: thickness: 2+/−0.2 mm; width of web: 10+/−0.5 mm; length of web: approximately 45 mm; total length: 9 cm. The test is carried out under standard climate conditions (23+/−2° C., 50+/−5% relative humidity). The test is conducted after curing for 7 days.

(43) Procedure: A film of the sealing compound 2 mm thick is spread out. The film is stored for 7 days under standard climate conditions, and the dumbbell test specimens are then punched out. Three dumbbell test specimens are produced for each determination. The test is carried out under standard climate conditions. The test pieces must be acclimatized (i.e. stored) beforehand for at least 20 minutes at the test temperature. Prior to the measurement, the thickness of the test pieces is measured at room temperature with a slide gauge at ≥least 3 locations; for the starting measurement length, preferably the ends and center of the dumbbell test specimens are measured. For elastic materials, it is recommended to take an additional measurement crosswise over the web. The average value is entered into the measurement program. The test pieces are clamped into the tensile testing machine in such a way that the longitudinal axis coincides with the mechanical axis of the tensile testing machine, and the largest possible surface area of the heads of the dumbbell test specimens is included without the web becoming jammed. The dumbbell test specimen is stretched to a pre-tensioning of <0.1 MPa at a feed rate of 50 mm/min. The curve of the change in force versus length is recorded at a feed rate of 50 mm/min.

(44) Evaluation: The following values are taken from the measurement: breaking strength [N/mm.sup.2]; elongation at break [%]; and, modulus of elasticity at 100% elongation [N/mm.sup.2].

(45) Alternatively, the specimens can also be immersed in a medium such as base/acid or oil, for an additional 7 days in order to test the chemical resistance of the formulation.

(46) The results of the measurements are shown in Table 2 herein below.

(47) TABLE-US-00002 TABLE 2 Results of the Mechanical Tests Formulation Formulation B A (Comparative) Skin over time (SOT) (minutes) 7 10 Shore A hardness after 7 days 23 8.5 Elongation at break after 7 days >950% at 23° C., 50% RH (%) Modulus of elasticity 100% after 7 days 0.24 0.1 at 23° C., 50% RH (N/mm.sup.2) Modulus at break after 7 days 0.87 0.38 at 23° C., 50% RH (N/mm.sup.2) Elongation at break after 7 days >600% at 23° C., 50% RH + 7 days 10% NaOH (%) Modulus of elasticity 100% after 7 days 0.26 0.09 at 23° C., 50% RH + 7 days 10% NaOH (N/mm.sup.2) Modulus at break after 7 days 0.71 0.28 at 23° C. 50% RH + 7 days 10% NaOH (N/mm.sup.2) Elongation at break after 7 days >900% at 23° C. 50% RH + 7 days 3% HCl (%) Modulus of elasticity 100% after 7 days 0.26 0.1 at 23° C., 50% RH + 7 days 3% HCl (N/mm.sup.2) Modulus at break after 7 days 1.05 0.38 at 23° C. 50% RH + 7 d 3% HCl (N/mm.sup.2) Elongation at break after 7 days >900% at 23° C., 50% RH + 7 days 0W40 (%) Modulus of elasticity 100% after 7 days 0.22 0.1 at 23° C., 50% RH + 7 days 0W40 (N/mm.sup.2) Modulus at break after 7 days 0.86 0.32 at 23° C., 50% RH + 7 days 0W40 (N/mm.sup.2) Elongation at break after 7 days >800% at 23° C., 50% RH + 7 days BOT355 (%) Modulus of elasticity 100% after 7 days 0.19 0.09 at 23° C., 50% RH + 7 days BOT355 (N/mm.sup.2) Modulus at break after 7 days 0.6 0.3 at 23° C., 50% RH + 7 days BOT355 (N/mm.sup.2) Elongation at break after 7 days >450% At 23° C., 50% RH + 7 days UV ARRAY (%) Modulus of elasticity 100% after 7 days 0.15 0.1 at 23° C., 50% RH + 7 days UV ARRAY (N/mm.sup.2) Modulus at break after 7 days 0.46 0.21 at 23° C., 50% RH + 7 days UV ARRAY (N/mm.sup.2)

(48) From the tests above, it can be clearly seen that Formulation B has not completely cured through: this is clear, in particular, from the SOT and Shore A hardness and from the observation that every modulus measured for Formulation B is at least half the measured value for Formulation A. It is considered that the hydrosilylation of the long chain Polymer 1 cannot be done effectively with the current techniques.

(49) In view of the foregoing description and examples, it will be apparent to those skilled in the art that equivalent modifications thereof can be made without departing from the scope of the claims.