Alkoxysilane-terminated prepolymer based on polyether carbonate polyols, for spray foams

Abstract

The present invention relates to an alkoxysilane-terminated prepolymer, characterized in that it is obtainable by reaction of at least A) a polyol, B) a compound having two or more isocyanate groups, and C) an alkoxysilane having at least an isocyanate group and/or an isocyanate-reactive group, wherein the polyol A) comprises at least a polyethercarbonatepolyol obtainable by addition of carbon dioxide and alkylene oxides onto H-functional starter molecules. The present invention further relates to a process for preparing the alkoxysilane-terminated prepolymer of the present invention and also to a composition and a multicomponent system comprising an alkoxysilane-terminated prepolymer of the present invention. The present invention further relates to a shaped article obtainable by polymerizing the alkoxysilane-terminated prepolymer of the present invention, by polymerizing a composition of the present invention or by polymerizing a multicomponent system of the present invention. The present invention further relates to a pressurized can containing an alkoxysilane-terminated prepolymer of the present invention, a composition of the present invention or a multicomponent system of the present invention.

Claims

1. An alkoxysilane-terminated prepolymer, obtained by reacting at least A) a polyol, B) a compound having two or more isocyanate groups, and C) an alkoxysilane having at least an isocyanate group or an isocyanate-reactive group, wherein the polyol A) comprises at least a polyethercarbonatepolyol obtained by addition of carbon dioxide and alkylene oxides onto H-functional starter molecules.

2. The alkoxysilane-terminated prepolymer according to claim 1, wherein the polyethercarbonatepolyol has a number-average molecular weight M.sub.n of 500 and 6000 g/mol.

3. The alkoxysilane-terminated prepolymer according to claim 1, wherein the polyethercarbonatepolyol has a content of carbonate groups, reckoned as CO.sub.2, of 3 and 35 wt. %.

4. The alkoxysilane-terminated prepolymer according to claim 1, wherein the polyethercarbonatepolyol is obtained by addition of carbon dioxide and alkylene oxides onto H-functional starter molecules while using multimetal cyanide catalysts.

5. The alkoxysilane-terminated prepolymer according to claim 1, wherein the polyethercarbonatepolyol has 2 and 4 OH groups.

6. The alkoxysilane-terminated prepolymer according to claim 1, wherein the proportion of component A) which is attributable to the polyethercarbonatepolyol is 50 and 100 wt. %.

7. The alkoxysilane-terminated prepolymer according to claim 1, wherein the alkoxysilane of component C) is an -alkoxysilane.

8. The alkoxysilane-terminated prepolymer according to claim 1, wherein component B) is an aliphatic and/or cycloaliphatic compound.

9. The alkoxysilane-terminated prepolymer according to claim 1, wherein the alkoxysilane-terminated prepolymer is obtained by reaction of at least the alkoxysilane C), comprising isocyanate-reactive groups, with an NCO-terminated polyurethane prepolymer, wherein the NCO-terminated polyurethane prepolymer is obtained by reaction of at least the isocyanate-functional compound B) with the polyol A).

10. A process for preparing the alkoxysilane-terminated prepolymer according to claim 1 comprising the steps of: reacting the polyol A) with the compound B) to form an NCO- or OH-terminated polyurethane prepolymer, and reacting the NCO- or OH-terminated polyurethane prepolymer with the alkoxysilane C) to form the alkoxysilane-terminated prepolymer.

11. A composition comprising at least an alkoxysilane-terminated prepolymer i) according to claim 1 and at least one further component.

12. The composition according to claim 11, wherein the further component is 1 and 70 wt. % of an alkoxysilane-terminated prepolymer other than i), which comprises a polyetherpolyol and/or a polyesterpolyol having a number-average molecular weight M.sub.n of 500 and 7000 g/mol as polyol component A).

13. The alkoxysilane-terminated prepolymer according to claim 1, wherein the polyethercarbonatepolyol has a content of carbonate groups, reckoned as CO.sub.2, of 10 and 28 wt. %.

14. The alkoxysilane-terminated prepolymer according to claim 13, wherein the polyethercarbonatepolyol has a number-average molecular weight M.sub.n of 1000 and 3000 g/mol, wherein the polyethercarbonatepolyol has 2 OH groups, wherein the alkoxysilane of component C) is an -alkoxysilane and wherein component B) is an aliphatic and/or cycloaliphatic compound.

Description

EXAMPLES

(1) General:

(2) Any amounts, proportions and percentages hereinbelow are based, unless otherwise stated, on the weight and the overall amount, i.e. the overall weight, of the compositions.

(3) Unless stated otherwise, analytical measurements all relate to measurements at temperature of 23 C.

(4) Methods:

(5) The proportion of incorporated CO.sub.2 in the polyethercarbonatepolyols was determined using .sup.1H NMR (from Bruker, DPX 400, 400 MHz; pulse program zg30, wait time d1: 5 s, 100 scans). Each sample was dissolved in deuterated chloroform. Dimethyl terephthalate was added to the deuterated solvent as an internal standard at a rate of 2 mg per 2 g of CDCl.sub.3. The relevant resonances in .sup.1H NMR (based on CHCl.sub.3=7.24 ppm) are as follows:

(6) carbonate resulting from carbon dioxide incorporated in the polyethercarbonatepolyol (resonances at 5.2 to 4.8 ppm), unconverted PO resonance at 2.4 ppm, polyetherpolyol (i.e. without incorporated carbon dioxide) resonances at 1.2 to 1.0 ppm.

(7) The molar fractions of carbonate incorporated in the polymer, of polyetherpolyol fractions and of unconverted PO is determined by integration of the corresponding signals.

(8) Number-average molecular weight M.sub.n is determined as follows: First the polyol is admixed with acetic anhydride and pyridine. After the reaction has taken place, the OH number is experimentally determined in accordance with German standard specification DIN 53240-1 by subsequent back-titration of the resulting acetic acid with standard alcoholic potassium hydroxide solution. OH number is reported in mg of KOH per gram of polyol. Number-average molecular weight M.sub.n is calculated from the OH number using the formula number-average molecular weight M.sub.n=561000OH functionality/OH number.

(9) NCO contents, unless expressly mentioned otherwise, were determined volumetrically in accordance with DIN-EN ISO 11909.

(10) The check for free NCO groups was carried out using IR spectroscopy (band at 2260 cm.sup.1).

(11) Reported viscosities were determined using rotary viscometry in accordance with German standard specification DIN 53019 at 23 C. with a rotary viscometer at a rotary frequency of 18 s.sup.1 from Anton Paar Germany GmbH, Ostfildern, DE.

(12) The maximum soluble blowing gas quantity was determined at 20 C. in test glasses for optical checks of aerosols from Parnasol Willi Mder AG, CH. The maximum soluble blowing gas quantity relates to the weight ratio of blowing gas to the substance/mixture to be investigated, and was reached as soon as the blowing gas just failed to form a second phase on a permanent basis (>1 h).

(13) Since viscosity measurement under blowing gas conditions is technically not feasible, viscosities of STP/blowing gas solutions are estimated on the basis of the flow rate at a 5% gradient in test glasses by comparison with reference solutions of previously determined viscosity (aqueous solutions of different concentrations of Walocel CRT 30 G).

(14) The mixtures were foamed up using a 2K spraying apparatus which was filled as described in WO 2012/022686 and WO 2012/022685.

Employed Substances and Abbreviations

(15) HDI: hexamethylene 1,6-diisocyanate Geniosil XL 926: [(cyclohexylamino)methyl]triethoxysilane (Wacker Chemie AG, Munich, DE) Walocel CRT 30 G: carboxymethylcellulose, sodium salt (Dow Deutschland Anlagengesellschaft mbH, Schwalbach, DE) P/B 2.7: mixture of propane and isobutane to give a gas pressure of 2.7 bar at 20 C. Polyethercarbonatepolyol 1: polyethercarbonatediol based on propylene oxide and CO.sub.2, with an OH number of 58 mg KOH/g (M.sub.n=1931 g/mol) and an incorporated CO.sub.2 content of 15.1 wt % and an OH functionality of 2. Polyethercarbonatepolyol 2: polyethercarbonatediol based on propylene oxide and CO.sub.2, with an OH number of 55.5 mg KOH/g (M.sub.n=2018 g/mol) and an incorporated CO.sub.2 content of 18.2 wt % and an OH functionality of 2.

(16) The examples which follow demonstrate the preparation of silane-terminated prepolymers and their use.

Example 1: Preparissg Prenolymer P1

(17) A mixture of 800 g of polyethercarbonatepolyol 1 and 1.89 g of dibutyl phosphate was admixed at 60-65 C. with 1044.56 g of hexamethylene diisocyanate (HDI) added dropwise in the course of 15 mm. Thereafter, the mixture was stirred at 80 C. for 1.5 hours. The NCO content of this mixture was 25.9%.

(18) Excess HDI was removed by thin-film distillation at 140 C. and 0.15 mbar to obtain a prepolymer having an NCO content of 3.74%.

Example 2: Preparing Prepolymer P2

(19) A mixture of 251.41 g of hexamethylene diisocyanate and 0.45 g of dibutyl phosphate was admixed at 58-62 C. with 213.63 g of polyethercarbonatepolyol 2 added dropwise in the course of 45 min. Thereafter, the mixture was stirred at 80-82 C. for 1 hour. The NCO content of this mixture was 24.9%.

(20) Excess HDI was removed by thin-film distillation at 120 C. and 0.03 mbar to obtain a prepolymer having an NCO content of 3.51%.

Example 3: Preparation of Prepolymer P3

(21) A mixture of 1032 g of a polyalkylene oxide having a molar mass of 4000 g/mol started on 1,2-propylene glycol, and having an ethylene oxide weight fraction of 13% and a propylene oxide weight fraction of 86%, dried beforehand at 80 C. at a pressure of 0.1 mbar for 1 h, and 1.8 g of benzoyl chloride was added dropwise in the course of 30 minutes at 80 C. with 650 g of HDI, and subsequently stirred for 4 h. Excess HDI was removed by thin-film distillation at 130 C. and 0.03 mbar to obtain a prepolymer having an NCO content of 1.82%.

Example 4: Preparation of Prepolymer P4

(22) A mixture of 246.7 g of a polyalkylene oxide having a molar mass of 4000 g/mol started on 1,2-propylene glycol, and having an ethylene oxide weight fraction of 30% and a propylene oxide weight fraction of 70%, dried beforehand at 80 C. at a pressure of 0.1 mbar for 1 h, and 0.43 g of benzoyl chloride was added dropwise in the course of 20 minutes at 80 C. with 155.2 g of HDI, and subsequently stirred for 3 h at 80 C. Excess HDI was removed by thin-film distillation at 140 C. and 0.03 mbar to obtain a prepolymer having an NCO content of 1.88%.

Example 5: Preparation of Prepolymer P5

(23) Desmophen C 2200 (polycarbonatediol formed from dimethyl carbonate and 1,6-hexanediol, M.sub.n=2000 g/mol), previously dewatered at 100 C. and a pressure of 0.2 mbar for 1 h, and gradually melted at 60 C. was added to 500.0 g of hexamethylene diisocyanate and 0.90 g of isophthaloyl dichloride. This was followed by stirring at 60 C. for one hour, the NCO value of the reaction mixture was 26.4%. Excess HDI was distilled off at a temperature of 140 C.-150 C. in a kugelrohr distillation apparatus. The residue which remained (residual NCO value 3.7%), consisting of the desired prepolymer, solidified at room temperature.

Example 6: Preparation of Silane-Terminated Prepolymer STP1 (Inventive)

(24) 150 g of prepolymer P1 were admixed at 30 C. with 36.41 g of Geniosil XL 926 in the course of 15 min. The reaction was slightly exothermic, the temperature rose to a maximum of 47 C. Following a further 2 hours of stirring at 30-40 C., complete conversion into the silane-terminated prepolymer (STP) was evidenced by IR spectroscopy.

Example 7: Preparation of Silane-Terminated Prepolymer STP2 (Inventive)

(25) 100 g of prepolymer P2 were admixed at 40-50 C. with 23.0 g of Geniosil XL 926 in the course of 15 min. The reaction was slightly exothermic, the temperature rose to a maximum of 50 C. Following a further hour of stirring at 40-50 C., complete conversion into the silane-terminated prepolymer (STP) was evidenced by IR spectroscopy.

Example 8: Preparation of Silane-Terminated Prepolymer STP3 (Inventive)

(26) A mixture of 50 g of prepolymer P2 and 50 g of prepolymer P3 was admixed at 40-50 C. with 18.24 g of Geniosil XL 926 in the course of 15 mm. The reaction was slightly exothermic, the temperature rose to a maximum of 50 C. Following a further one hour of stirring at 40-50 C., complete conversion into the silane-terminated prepolymer (STP) was evidenced by IR spectroscopy.

Example 9: Preparation of Silane-Terminated Prepolymer STP4 (Inventive)

(27) 90 g of prepolymer P1 and 10 g of prepolymer P3 were admixed at 30 C. with 22.96 g of Geniosil XL 926 in the course of 15 min. Following a further one hour of stirring at 30-40 C., complete conversion into the silane-terminated prepolymer (STP) was evidenced by IR spectroscopy.

Example 10: Preparation of Silane-Terminated Prepolymer STP5 (Inventive)

(28) 90 g of prepolymer P1, 10 g of prepolymer P3 and 10.67 g of prepolymer P4 were admixed at 30 C. with 23.81 g of Geniosil XL 926 in the course of 15 min. Following a further one hour of stirring at 30-40 C., complete conversion into the silane-terminated prepolymer (STP) was evidenced by IR spectroscopy.

Example 11: Preparation of Silane-Terminated Prepolymer STP6 (Inventive)

(29) 8.0 g of prepolymer P5 were weighed at 40-50 C., as a viscose liquid, in a small glass tube and admixed with 2.0 g of Geniosil XL 926. The reaction was slightly exothermic, and after the reaction had ended a very pronounced increase in the viscosity was noted. The silane-terminated prepolymer obtained turned solid on cooling down to RT.

(30) Blowing gas compatibility was investigated in test glasses for optical checks of aerosols from Pamasol Willi Mder AG, CH. About 500 mg of this silane-terminated prepolymer STP6 were introduced into the small tube and admixed under superatmospheric pressure with the blowing gases isobutane/propane and dimethyl ether. Neither blowing gas had sufficient solubility for the prepolymer. A spray test to produce a new foam based on Desmophen C 2200 as described in the other examples is accordingly impossible.

Example 12: Foaming of STP1 (Inventive Use)

(31) 12.4 g of STP1 were dissolved in 3.3 g of P/B 2.7. A phosphate buffer was used as second component. To prepare it, 9.078 g of KH.sub.2PO.sub.4 were dissolved in 1 L of water, while 11.876 g of Na.sub.2HPO.sub.4 were dissolved in 1 L of water to prepare the second solution. 150 mL of the Na.sub.2HPO.sub.4 solution were made up to 1000 mL with the KH.sub.2PO.sub.4 solution. The pH of this phosphate buffer was 6.1, the buffer concentration of this solution was 0.069 mol/l. This buffer solution was adjusted with Walocel CRT 30 G to a viscosity of about 500 mPas.

(32) The two components were separately introduced into their own chamber in a 2K spraying apparatus operated using compressed air, the chambers in the spraying apparatus being in a volume ratio of 2.5 (STP) to 1 (buffer solution) relative to each other. Synchronous discharge of the two components in this volume ratio is ensured by the design, and proceeded via a static mixer where the commixing took place. A completely cured foam was obtained after 20 minutes.

Example 13: Foaming of STP1 (Inventive Use)

(33) 12.1 g of STP1 were dissolved in 3.2 g of P/B 2.7. The second component was a mixture of a succinic acid buffer and glycerol. It was prepared by making up 23.62 g of succinic acid to 1000 mL with water, 25 mL of this solution were mixed with 25 mL of 0.1 M aqueous sodium hydroxide solution and made up to 1000 mL with water and adjusted with Walocel CRT 30 G to a viscosity of about 500 mPas. The pH of this buffer was 4.0, the concentration of the buffer was 0.05 mol/l. 60 mL of this buffer solution were mixed with 40 mL of the glycerol solution.

(34) The two components were separately introduced into their own chamber in a 2K spraying apparatus operated using compressed air, the chambers in the spraying apparatus being in a volume ratio of 2.5 (STP) to 1 (buffer solution) relative to each other. Synchronous discharge of the two components in this volume ratio is ensured by the design, and proceeded via a static mixer where the commixing took place. A completely cured foam was obtained after 40 seconds.

Example 14: Foaming of STP4 (Inventive Use)

(35) 11.7 g of STP4 were dissolved in 3.1 g of P/B 2.7. A phosphate buffer was used as second component. To prepare it, 9.078 g of KH.sub.2PO.sub.4 were dissolved in 1 L of water, while 11.876 g of Na.sub.2HPO.sub.4 were dissolved in 1 L of water to prepare the second solution. 150 mL of the Na.sub.2HPO.sub.4 solution were made up to 1000 mL with the KH.sub.2PO.sub.4 solution. The pH of this phosphate buffer was 6.1, the buffer concentration of this solution was 0.069 mol/l. This buffer solution was adjusted with Walocel CRT 30 G to a viscosity of about 500 mPas.

(36) The two components were separately introduced into their own chamber in a 2K spraying apparatus operated using compressed air, the chambers in the spraying apparatus being in a volume ratio of 2.5 (STP) to 1 (buffer solution) relative to each other. Synchronous discharge of the two components in this volume ratio is ensured by the design, and proceeded via a static mixer where the commixing took place. A completely cured foam was obtained after 2 minutes.

Example 15: Foaming of STP5 (Inventive Use)

(37) 12.3 g of STP5 were dissolved in 2.5 g of P/B 2.7. A phosphate buffer was used as second component. To prepare it, 9.078 g of KH.sub.2PO.sub.4 were dissolved in 1 L of water, while 11.876 g of Na.sub.2HPO.sub.4 were dissolved in 1 L of water to prepare the second solution. 150 mL of the Na.sub.2HPO.sub.4 solution were made up to 1000 mL with the KH.sub.2PO.sub.4 solution. The pH of this phosphate buffer was 6.1, the buffer concentration of this solution was 0.066 mol/l. This buffer solution was adjusted with Walocel CRT 30 G to a viscosity of about 500 mPas.

(38) The two components were separately introduced into their own chamber in a 2K spraying apparatus operated using compressed air, the chambers in the spraying apparatus being in a volume ratio of 2.5 (STP) to 1 (buffer solution) relative to each other. Synchronous discharge of the two components in this volume ratio is ensured by the design, and proceeded via a static mixer where the commixing took place. A completely cured foam was obtained after 2 minutes.

Example 16: Foaming STP2 (Inventive Use)

(39) 12.1 g of STP2 were dissolved in 3.2 g of P/B 2.7. The second component was a mixture of a succinic acid buffer and glycerol. It was prepared by making up 1.18 g of succinic acid to 60 g with water and with 40 g of 0.1 M NaOH. The resulting buffer solution was adjusted with Walocel CRT 30 G to a viscosity of about 500 mPas. The pH of this buffer solution was 4.0, the concentration of the buffer mixture was 0.1 mol/1.50 mL of this buffer solution were mixed with 50 mL of glycerol.

(40) The two components were separately introduced into their own chamber in a 2K spraying apparatus operated using compressed air, the chambers in the spraying apparatus being in a volume ratio of 2.5 (STP) to 1 (buffer solution) relative to each other. Synchronous discharge of the two components in this volume ratio is ensured by the design, and proceeded via a static mixer where the commixing took place. A completely cured foam was obtained after 1.5 minutes.

Example 17: Foaming of STP3 (Inventive Use)

(41) 11.9 g of STP3 were dissolved in 3.4 g of P/B 2.7. The second component was a mixture of a succinic acid buffer and glycerol. It was prepared by dissolving 1.18 g of succinic acid in 60 g of water and mixed with 40 g 0.1 M NaOH. The pH of this buffer solution was 4.0, the concentration of the buffer mixture was 0.1 mol/l. The buffer solution obtained was adjusted with Walocel CRT 30 G to a viscosity of about 500 mPas. 50 mL of this buffer solution were mixed with 50 mL of glycerol.

(42) The two components were separately introduced into their own chamber in a 2K spraying apparatus operated using compressed air, the chambers in the spraying apparatus being in a volume ratio of 2.5 (STP) to 1 (buffer solution) relative to each other. Synchronous discharge of the two components in this volume ratio is ensured by the design, and proceeded via a static mixer where the commixing took place. A completely cured foam was obtained after 1.5 minutes.

Example 18: Foaming of STP3 (Inventive Use)

(43) 12.0 g of STP2 were dissolved in 3.4 g of P/B 2.7. A phosphate buffer was used as second component. To prepare it, 9.078 g of KH.sub.2PO.sub.4 were dissolved in 1 L of water, while 11.876 g of Na.sub.2HPO.sub.4 were dissolved in 1 L of water to prepare the second solution. 150 mL of the Na.sub.2HPO.sub.4 solution were made up to 1000 mL with the KH.sub.2PO.sub.4 solution. The pH of this phosphate buffer was 6.1, the buffer concentration of this solution was 0.069 mol/l. This buffer solution was adjusted with Walocel CRT 30 G to a viscosity of about 500 mPas.

(44) The two components were separately introduced into their own chamber in a 2K spraying apparatus operated using compressed air, the chambers in the spraying apparatus being in a volume ratio of 2.5 (STP) to 1 (buffer solution) relative to each other. Synchronous discharge of the two components in this volume ratio is ensured by the design, and proceeded via a static mixer where the commixing took place. A completely cured foam was obtained after 2.5 minutes.