Silane-terminated polymer

Abstract

The present invention relates to a process for producing a silane-terminated polymer in the presence of a catalyst mixture, where the catalyst mixture contains a bismuth and a cobalt catalyst, and the content of the cobalt catalyst is at least 2 ppm based on the hydroxy-terminated organic polymer of the formula.

Description

Technical Field

[0001] The present invention relates to a process for producing silane-terminated polymers that can be used in sealants, adhesives, and coating materials and are storage-stable over a long period of time.

Background Art

[0002] Silane-terminated polymers are produced by known methods. Known processes include, for example, the reaction of a polyol, particularly a hydroxyl-terminated polyether, polyurethane, or polyester, and more particularly a hydroxyl-functional polyacrylate, with an (isocyanatoalkyl)alkoxysilane.

[0003] Another method is the reaction of the aforementioned polyol with a di- or polyisocyanate, assuming that the latter is used in excess, and an isocyanate-functional polymer is produced in this first reaction step, and then the isocyanate-functional polymer is reacted with an alkoxysilane having an alkyl-bonded isocyanate-reactive group in a second reaction step.

[0004] The reaction of a hydroxyl-functional polymer with an isocyanate is carried out in the presence of an additional catalyst because only when carried out in the presence of an additional catalyst is it possible to achieve a reaction rate high enough for the economical production of alkoxysilane-terminated polymers in the relevant reaction step.

[0005] For example, the use of a bismuth catalyst as described in EP1535940 provides catalytic activity and thus promotes the reaction of isocyanatosilane with a hydroxyl-terminated polyol. However, even when a relatively large amount of catalyst is used, a long reaction time is required to achieve complete conversion. Furthermore, a large amount of catalyst can cause undesirable side reactions in the synthesis and may reduce the storage stability of the final product.

[0006] US9932437B2 and US8809479B2 disclose a moisture-curable resin composition with a low volatile organic compound content. This is obtained by the reaction of a moisture-curable polymer having a hydrolyzable silyl group with a reactive modifier.

Summary of the Invention

Problems to be Solved by the Invention

[0007] One object of the present invention is to provide a process for producing a silane-terminated polymer that enables rapid but complete conversion.

Means for Solving the Problems

[0008] This object is achieved by the process of the present invention. Preferred embodiments are the subject matter of the dependent claims.

[0009] Surprisingly, it has been found that the process of the present invention can produce a silane-terminated polymer of formula (I) or formula (VI) in a very effective manner.

Chemical Formula

Embodiments for Carrying Out the Invention

[0010] According to the present invention, the silane-terminated polymer of formula (I) is a hydroxy-terminated organic polymer of formula (II):

Chemical Formula

[0011] This reaction is carried out in the presence of a catalyst mixture described below. In the compound of general formula I, A is a polyether main chain, x and y are natural numbers from 1 to 10, and y must be greater than or equal to x, n, n1 and n2 are 1 or 3, p, p1 and p2 are natural numbers from 1 to 5, m is a natural number from 2 to 10, R, R1 and R2 are methyl or ethyl, B is a linear, branched or cyclic organic group that does not contain an isocyanate-reactive group, and m is greater than 1, D is selected from the group consisting of NH, NR3 and S, D1 is a reactive group that reacts with an isocyanate group and is selected from the group consisting of NH2, NHR3 and SH, R3 is a linear, branched or cyclic hydrocarbon group having 1 to 10 carbon atoms and may optionally contain one or more heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen.

[0012] In the process of the present invention, it is possible to use one or two different isocyanates of general formula (III). When using only one isocyanate, R1 and R2 in the silane-terminated polymer of formula (I) or formula (VI) are the same and correspond to R in general formula (III). When using two different isocyanates of general formula (III), R1 corresponds to the R group of the first isocyanate of general formula (III), and R2 corresponds to the R group of the second isocyanate of general formula (III). The same applies to n and p.

[0013] In one embodiment of the present invention, R1 and R2 are the same, and n1 and n2 are the same. Such a polymer can be obtained in a very simple manner in the synthesis by using only one isocyanate of general formula (III).

[0014] In a further embodiment, R1 and R2, or n1 and n2, or R1 and R2, n1 and n2 are different from each other. Such a polymer is obtained by a mixture of a plurality of different isocyanates of general formula (III). By this mixture, the reactivity of the silane-terminated polymer can be controlled. A pure trimethoxysilane-terminated polymer crosslinks quickly, and a pure triethoxysilane-terminated polymer reacts slowly. By changing the mixing ratio, the reactivity can be adjusted individually accordingly.

[0015] The catalyst mixture contains a bismuth catalyst and a cobalt catalyst, where the content of the cobalt catalyst is at least 2 ppm based on the hydroxy-terminated organic polymer of formula (II).

[0016] In the context of the present invention, the catalyst content is reported in ppm. This value is based on the metal present in the catalyst, i.e., mg of metal per kg of hydroxy-terminated organic polymer. The anions of the catalyst are not included in the determination of this content.

[0017] By "complete conversion" in the present invention is meant that at least 95% by mass, preferably 98% by mass of the OH groups in the polymer main chain have reacted with the isocyanate of general formula III or IV.

[0018] In one embodiment, the catalyst mixture does not contain any further catalyst. This means that the catalyst mixture consists of a bismuth catalyst and a cobalt catalyst.

[0019] The content of the bismuth catalyst in the catalyst mixture is preferably at least 10 ppm based on the hydroxy-terminated organic polymer of formula (II). A combination containing at least 2 ppm of cobalt catalyst and at least 10 ppm of bismuth catalyst has been found to result in a very short reaction time. The reaction time is preferably reduced by 50%, more preferably by 65%. The silane-terminated polymer can be produced continuously or batchwise.

[0020] In one embodiment, the silane-terminated polymer has the general formula IA:

Chemical formula

Chemical formula

[0021] The linear silane-terminated polymers of general formula (IB) are more preferably used in sealants and coating materials that require great elasticity, such as bonding compounds, elastic adhesives, surface sealants, or, in the marine field, for example, the gluing of teak wood. After curing, such linear polymers are softer and more elastic, while the branched polymers described below are harder and less elastic due to their high crosslink density.

[0022] In a second embodiment, the silane-terminated polymer relates to a branched polymer of general formula IC:

Chemical formula

[0023] Formula:

Chemical formula

[0024] The expression "their copolymers" means polymers composed of two or more monomer units. In addition to alternating copolymers and graft copolymers, this term particularly includes block polymers consisting of long chains or blocks of each monomer, which can be linked to each other via a linker compound. Such copolymers may, for example, contain an aromatic glycol chain extender having 6 to 16, preferably 6 to 12 total carbon atoms. Examples of suitable glycol chain extenders are benzene glycol and xylene glycol, and xylene glycol is a mixture of 1,4-di(hydroxymethyl)benzene and 1,2-di(hydroxymethyl)benzene. Benzene glycol is preferred, especially bis(β-hydroxyethyl) ether also known as hydroquinone, i.e., 1,4-di(2-hydroxyethoxy)benzene, resorcinol, i.e., 1,3-di(2-hydroxyethyl)benzene also known as bis(β-hydroxyethyl) ether, catechol, i.e., 1,2-di(2-hydroxyethyl)benzene also known as bis(β-hydroxyethyl) ether, and combinations thereof.

[0025] The expression "hydroxy-terminated" means a polymer having a free hydroxyl group at the end of the molecule. y is a natural number from 1 to 10. In a preferred embodiment, y = 1, in which case it corresponds to an α,ω-dihydroxy-terminated organic polymer, i.e., a polymer having two terminal OH groups. When y is greater than 1, the hydroxy-terminated polyol has two or more terminal OH groups. That is, the hydroxy-terminated polyol is a polyol whose OH groups are intended to react with the isocyanate of formula III. In the case of a branched hydroxy-terminated polymer, its OH groups are preferably not directly bonded to the polymer main chain, but rather to the ends of the side chains of the polymer main chain. These can be obtained, for example, by reaction with a polyol. Both linear and branched hydroxy-terminated organic polymers are known to those skilled in the art and are also commercially available.

[0026] Examples of possible hydroxy-terminated polymers having a polyether polymer backbone are Acclaim® 4200, Acclaim® 6300, Acclaim® 8200, Acclaim® 12200 and Acclaim® 18200 (or the corresponding Acclaim® xx00N products) from Covestro AG, PREMINOL S 1004F, PREMINOL S 4013F, PREMINOL S 4318F, PREMINOL S 3011, PREMINOL 5001F, PREMINOL 7001K and PREMINOL 7012 from AGC, Rokopol LDB Delta 12000, Rokopol LDB 18000D, Rokopol LDB 12000D, ROKAmer PPG 4000 and Rokopol LDB8000D from PCC Group, Voranol 3008, Voranol 3010, Voranol 3022J, Voranol 3136, Voranol 4000LM, Voranol 4053 and Voranol 8000LM from DOW.

[0027] Preferably, the hydroxy-terminated organic polymer is a liquid at room temperature. This means that its viscosity at 20 °C is 1 to 10 6 mPa·s. This viscosity is optimal for handling the compositions of the present invention, particularly for the manufacture of sealant preparations.

[0028] The hydroxy-terminated organic polymer preferably has an average molecular weight of 1000 to 50000 g / mol, particularly 2000 to 25000 g / mol, since the handling of the polymer is optimal. Optionally, a plasticizer may be added to improve processability. Suitable plasticizers are known to those skilled in the art. Preferred plasticizers are, for example, phenylalkane sulfonates such as Mesamoll from Lanxess, cyclohexanoate plasticizers such as Elatur DINCD from Evonik, diisononyl 1,2-cyclohexanedicarboxylate such as Hexamoll DINCH from BASF, hydrocarbons such as Shellsol D100 from Shell, and diesters of dicarboxylic acids such as dioctyl sebacate, dioctyl adipate or dioctyl azelate. In this specification, "molecular weight" means the molar mass of the molecule (in grams per mole units). "Average molecular weight" means the number average molecular weight Mn of a polydisperse mixture of oligomer or polymer molecules, which is usually determined by titrating the acid value and the OH value. This is usually determined by titrating the acid value and the OH value. Alternatively, the number average molecular weight can also be determined by analytical methods such as GPC / MALDI. The OH value (hydroxyl value) is a measure of the hydroxyl group content in the polymer and is an amount known to those skilled in the art. The acid value is a measure of the content of acid groups in the polymer and is an amount known to those skilled in the art.

[0029] The hydroxy-terminated organic polymer of formula (II) used according to the present invention may be a commercially available compound, which may optionally be diluted with a plasticizer or a solvent for better handling.

[0030] In a preferred embodiment of the present invention, the reaction is carried out using an isocyanate selected from the group consisting of 3-isocyanatopropyltrimethoxysilane and 3-isocyanatopropyltriethoxysilane or a mixture thereof. As shown in the examples described below, these two silanes can be very effectively converted using the catalyst mixture of the present invention. In the case of the less reactive 3-isocyanatopropyltriethoxysilane, in order to obtain a very fast reaction, the cobalt catalyst content is preferably more than 4 ppm, more preferably more than 5 ppm.

[0031] The cobalt catalyst is preferably selected from the group consisting of cobalt(II) hexafluoroacetylacetonate, cobalt(II) benzoate, cobalt(II) isopropoxide, cobalt(II) acetylacetonate or cobalt(II) 1,4-pentanedionate, cobalt(II) oxalate, cobalt(II) citrate, cobalt(II) hydroxide, cobalt(II) acetate, cobalt(II) stearate, bis(2,2,6,6-tetramethyl-3,5-heptanedionato)cobalt(II), cobalt(II) oleate, cobalt(II) 2-ethylhexanoate (commercially available from Borchers as Octa-Soligen® Cobalt 10), cobalt(II) naphthenate (commercially available from Borchers as 6% Cobalt Nap-All®), cobalt(II) neodecanoate (commercially available from Borchers as Deca Cobalt 10) and cobalt(II) resinate, and cobalt(II) neodecanoate is particularly preferred.

[0032] The bismuth catalyst is preferably selected from the group consisting of bismuth(III) isopropoxide, bismuth(III) tert-pentoxide, bismuth(III) oleate, bismuth(III) 2-ethylhexanoate (commercially available from Borchers as Borchi® Kat 320), bismuth(III) neodecanoate (commercially available from Borchers as Borchi® Kat 315), and bismuth(III) acetylacetonate, and bismuth(III) neodecanoate is particularly preferred.

[0033] The catalyst mixture is preferably added in a total amount of 8 to 500 ppm, more preferably 8 to 100 ppm, and most preferably 10 to 50 ppm.

[0034] The catalyst can be stirred to obtain a mixture before the reaction and added to the reaction mixture or directly mixed into the prepolymer. The catalyst mixture is preferably freshly prepared before use. It has also been found that the catalyst mixture has better solubility when isocyanate is already present in the reactor at the time of addition of the catalyst mixture.

[0035] In the case of a colorless final product, a cobalt catalyst content of 2 to 5 ppm is preferred because discoloration of the product can occur.

[0036] The linear silane-terminated polymers are particularly preferably selected from the group consisting of the following.

[0037]

Chemical formula

[0038] Here, A is the polymer main chain as defined above. It has been found that these linear silane-terminated polymers can be prepared particularly effectively by the catalyst mixture of the present invention.

[0039] The process of the present invention for producing the silane-terminated polymer of formula (VI) is of formula (II): [Chemical formula] The hydroxy-terminated organic polymer is reacted with a polyfunctional isocyanate of formula (IV): Formula (IV): B-(N=C=O) m (IV) and then reacted with an alkoxysilane of formula (V): (RO)3Si-(CH2) p -D (V) This is carried out by reacting.

[0040] Particularly preferred polyfunctional isocyanates of formula (IV) are isocyanates having two or more, preferably 2 to 10, isocyanate groups in the molecule. Suitable for this purpose are known aliphatic, cycloaliphatic, aromatic, oligomeric and polymeric polyfunctional isocyanates that do not contain isocyanate-reactive groups, i.e., in particular, do not have free primary and / or secondary amino groups. One representative of aliphatic polyfunctional isocyanates is, for example, hexamethylene diisocyanate (HDI), and one representative of cycloaliphatic polyfunctional isocyanates is, for example, 1-isocyanato-3-(isocyanatomethyl)-3,5,5-trimethylcyclohexane (IPDI). Representative aromatic polyfunctional isocyanates include 2,4- and 2,6-diisocyanatotoluene and the corresponding technical isomer mixtures (TDI); diphenylmethane diisocyanate, such as diphenylmethane 4,4'-diisocyanate, diphenylmethane 2,4'-diisocyanate, diphenylmethane 2,2'-diisocyanate and the corresponding technical isomer mixtures (MDI). Further, naphthalene-1,5-diisocyanate (NDI) and 4,4',4''-triisocyanatotriphenylmethane are also mentioned. The reaction is preferably carried out at a temperature of 50°C to 150°C, more preferably 60°C to 120°C, and preferably at standard pressure.

[0041] The crosslinkable composition prepared according to the present invention is excellent as a sealing compound for joints such as vertical joints and similar spaces, for example, as a sealing compound in buildings, land vehicles, watercraft and aircraft, or as an adhesive, especially for bonding substrates with different coefficients of thermal expansion, for example, as an adhesive in vehicle construction, facade construction or solar applications, or as a cement compound, for example, as a cement compound in window construction or showcase manufacturing, and also has excellent suitability for the production of protective coatings or elastomeric molded articles and for the insulation of electrical or electronic devices. The composition of the present invention is particularly suitable as a sealing compound for joints with high movement tolerance.

[0042] The normal water content in the air is sufficient for the crosslinking of the composition of the present invention. The crosslinking may be carried out at room temperature, or if desired, at higher or lower temperatures, for example, -5°C to 10°C or 30°C to 50°C. The crosslinking is preferably carried out at standard pressure.

[0043] The silane-terminated polymer of the present invention can also be formulated as a two-component system. In addition to the auxiliary agent, the second component also contains water, which greatly promotes deep curing after mixing with the first component. The corresponding two-component systems are known to those skilled in the art and are described, for example, in EP2009063 or EP2535376, the contents of which are incorporated herein by reference.

[0044] The preparation of the present invention may further contain additional auxiliary agents and additives. These auxiliary agents and additives include, for example, additional silane-terminated polymers, plasticizers, stabilizers, antioxidants, fillers, reactive diluents, desiccants, adhesion promoters and UV stabilizers, rheology aids, color pigments or color pastes, crosslinking catalysts, and / or, in some cases, a small amount of solvent. Such auxiliary agents and additives are known to those skilled in the art.

Examples

[0045] Comparative Examples 1 to 10 and Invention Examples 11 to 20 230 g (11.65 mmol, determined by OH value titration) of Acclaim Polyol 18200N was introduced into a reaction flask and pre-dried at 80 °C and 1 mbar for 30 minutes. The vacuum was broken with nitrogen. Within 2 minutes, 5.09 g (23.3 mmol) of 94% 3-isocyanatopropyltrimethoxysilane was slowly added dropwise with a stirrer speed of 170 rpm. Two minutes after the addition of this isocyanatopropyltrimethoxysilane was completed, the catalyst mixture (see table) dissolved in diisononyl phthalate was added to the reaction mixture. The progress of the reaction was determined by FTIR from the increase in absorption at 1722 cm -1 (product C=O absorption) and the decrease in absorption at 2270 cm -1 (reactant NCO absorption). TMS-NCO: 3-isocyanatopropyltrimethoxysilane

[0046] [Table 1]

[0047] Comparative Examples 21 - 26 and Invention Example 27 - 29 230 g (11.65 mmol, determined by OH value titration) of Acclaim Polyol 18200N was introduced into a reaction flask and pre-dried at 80 °C and 1 mbar for 30 minutes. The vacuum was broken with nitrogen. Within 2 minutes, 6.13 g (23.3 mmol) of 94% 3-isocyanatopropyltriethoxysilane was slowly added dropwise with a stirrer speed of 170 rpm. Two minutes after the addition of this silane was completed, the catalyst mixture (see table) dissolved in diisononyl phthalate was added to the reaction mixture. The progress of the reaction was determined by FTIR from the increase in absorption at 1722 cm -1 (product C=O absorption) and the decrease in absorption at 2270 cm -1 (reactant NCO absorption). TES-NCO: 3-isocyanatopropyltriethoxysilane

[0048] [Table 2]

Claims

1. A process for producing a silane-terminated polymer of formula (I) or formula (VI), comprising: 【Chemical 1】 a hydroxy-terminated organic polymer of formula (II): [Chemical Formula 2] is reacted in the presence of a catalyst mixture with at least one isocyanate of general formula (III): (RO) ３ -Si-(CH ２ ) ｎ -N=C=O (III) or, after reaction with a polyfunctional isocyanate of formula (IV): is reacted with an alkoxysilane of formula (V): B-(N=C=O) ｍ (IV) to produce a product, (RO) ３ Si-(CH ２ ) ｐ -D １ (V) wherein A is a polyether backbone, x and y are natural numbers from 1 to 10, and y must be greater than or equal to x, m is a natural number from 2 to 10, n, n １ and n ２ is 1 or 3, p, p １ and p ２ are natural numbers from 1 to 5, B is a linear, branched or cyclic organic group that does not contain an isocyanate-reactive group, and m is greater than 1, R, R １ and R ２ are methyl or ethyl, the catalyst mixture comprises a bismuth catalyst and a cobalt catalyst, and the content of the cobalt catalyst is at least 2 ppm based on the hydroxy-terminated organic polymer of formula (II). D is selected from the group consisting of NH, NR ３ and S, D １ is a reactive group that reacts with an isocyanate group, and is selected from the group consisting of NH ２ , NHR ３ and SH, R ３ is a linear, branched or cyclic hydrocarbon group having 1 to 10 carbon atoms and may optionally contain one or more heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen.

2. The process according to claim 1, wherein the content of the bismuth catalyst is at least 10 ppm based on the hydroxy-terminated organic polymer of formula (II).

3. The process according to claim 1 or 2, wherein the silane-terminated polymer is a linear polymer of general formula IA:

4. 【Chemical Formula 3】 The process according to any one of claims 1 to 3, wherein the silane-terminated polymer is a linear polymer of general formula IB:

5. The process according to claim 3 or 4, wherein the linear silane-terminated polymer is selected from the group consisting of: 【Chemical Formula 4】 wherein A is a polyether backbone as defined above.

6. The process according to claim 1 or 2, wherein the silane-terminated polymer is a branched polymer of general formula (IC): 【Chemical Formula 5】 wherein x and y each correspond to a natural number from 2 to 10.

7. The process according to claim 6, wherein the silane-terminated polymer of formula (IC) is substantially free of free hydroxyl groups. [Chemical Formula 6]

8. The process according to any one of claims 1 to 7, wherein the reaction is carried out using an isocyanate selected from the group consisting of 3-isocyanatopropyltrimethoxysilane and 3-isocyanatopropyltriethoxysilane.

9. ​ ​ ​ ​ The process according to any one of claims 1 to 8, characterized in that the cobalt catalyst is selected from the group consisting of cobalt(II) hexafluoroacetylacetonate, cobalt(II) benzoate, cobalt(II) isopropoxide, cobalt(II) acetylacetonate, cobalt(II) oxalate, cobalt(II) citrate, cobalt(II) hydroxide, cobalt(II) acetate, cobalt(II) stearate, bis(2,2,6,6-tetramethyl-3,5-heptanedionato)cobalt(II), cobalt(II) oleate, cobalt(II) 2-ethylhexanoate, cobalt(II) naphthenate, cobalt(II) neodecanoate and cobalt(II) resinate.

10. The process according to any one of claims 1 to 9, characterized in that the bismuth catalyst is selected from the group consisting of bismuth(III) isopropoxide, bismuth(III) tert-pentoxide, bismuth(III) oleate, bismuth(III) 2-ethylhexanoate, bismuth(III) neodecanoate and bismuth(III) acetylacetonate.

11. The process according to any one of claims 1 to 10, characterized in that the hydroxy-terminated organic polymer has an average molecular weight of 1000 to 40000 g / mol, in particular 2000 to 25000 g / mol.

12. The process according to any one of claims 1 to 11, characterized in that the content of the cobalt catalyst is 2 to 5 ppm based on the hydroxy-terminated organic polymer of the formula (II).

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