Binder with cyclic carbonate structures

Abstract

The invention relates to a method for producing polyurethanes containing cyclic carbonate structures by reacting at least A) a composition containing a) one or more compounds of the general formula (I), said compounds containing isocyanate groups and cyclic carbonate structures, and b) <=1 wt. %, based on the total mass of the composition A), of one or more monomer diisocyanates with aliphatically, cycloaliphatically, araliphatically, and/or aromatically bound isocyanate groups of the general formula (II), wherein R represents hydrogen or a saturated or unsaturated, linear or branched, aliphatic group with 1 to 7 carbon atoms, X represents a linear or branched organic group which comprises 1 to 36 carbon atoms and which can contain optionally ether, ester, and/or carbonate groups, n represents 0 or 1, and Y represents a linear or branched, aliphatic or cycloaliphatic group with 4 to 18 carbon atoms or an optionally substituted aromatic or aliphatic group with 6 to 18 carbon atoms, with B) an at least difunctional polyol with a number-average molecular weight Mn of 62 to 22000 g/mol, preferably 90 to 12000 g/mol, while maintaining an equivalent ratio of isocyanate groups to hydroxyl groups of 0.3:1 to 1.2:1. Furthermore, the invention relates to products which can be obtained using the method according to the invention. The invention additionally relates to the use of the products which can be obtained using the method according to the invention as a starting component in the production of crosslinkable binders, such as paints and raw materials for sealants or adhesives.

Claims

1. A process for preparing polyurethanes containing cyclic carbonate structures, comprising reacting at least A) a composition comprising a) a compound of the general formula (I) containing one or more isocyanate groups and cyclic carbonate structures ##STR00004## b) 1% by weight, based on the total mass of the composition A), of one or more monomeric diisocyanate having aliphatically, cycloaliphatically, araliphatically and/or aromatically bonded isocyanate groups of the general formula (II),
OCNYNCO(II) and c) 0.5% to 12% by weight, based on the total mass of components a) and c) of compounds of the general formula (III) ##STR00005## wherein, independently, for each of a), b) and c), R is hydrogen or a saturated or unsaturated, linear or branched, aliphatic radical having 1 to 7 carbon atoms, X is a linear or branched organic radical which has 1 to 36 carbon atoms and which may optionally contain ether, ester and/or carbonate groups, n is 0 or 1 and Y is a linear or branched, aliphatic or cycloaliphatic radical having 4 to 18 carbon atoms or an optionally substituted aromatic or araliphatic radical having 6 to 18 carbon atoms, with B) an at least difunctional polyol having a number-average molecular weight M.sub.n of 62 to 22 000 g/mol, while maintaining a ratio of equivalents of isocyanate groups to hydroxyl groups of 0.3:1 to 1.2:1.

2. The process for preparing polyurethanes containing cyclic carbonate structures as claimed in claim 1, wherein composition A) contains a) 88% by weight of the compound of the general formula (I), b) 1% by weight of one or more monomeric diisocyanate having aliphatically, cycloaliphatically, araliphatically and/or aromatically bonded isocyanate groups of the general formula (II), and c) 12% by weight of the compound of the general formula (III), ##STR00006## where the proportion of each of a) and c) relates to the total mass of the compounds a) and c), and the proportion of b) relates to the total mass of the composition A), and where R is hydrogen or a saturated or unsaturated, linear or branched, aliphatic radical having 1 to 7 carbon atoms, X is a linear or branched organic radical which has 1 to 36 carbon atoms and which may optionally contain ether, ester and/or carbonate groups, n is 0 or 1 and Y is a linear or branched, aliphatic or cycloaliphatic radical having 4 to 18 carbon atoms or an optionally substituted aromatic or araliphatic radical having 6 to 18 carbon atoms.

3. The process as claimed in claim 1, characterized in that, for the formulae (I) and (II) of components a) and b), or for the formulae (I), (II) and (III) of components a), b) and c), Y is a linear or branched, aliphatic or cycloaliphatic radical having 6 to 13 carbon atoms.

4. The process as claimed in claim 1, wherein, for the formula (I) of component a) or the formulae (I) and (III) of components a) and c), R is hydrogen or a saturated linear aliphatic radical having 1 or 2 carbon atoms, X is a linear or branched organic radical which has 1 to 18 carbon atoms and which may optionally contain ether, ester and/or carbonate groups, and n is 0 or 1.

5. The process as claimed in claim 1, wherein, for the formula (I) of component a) or the formulae (I) and (III) of components a) and c), R is hydrogen or a saturated linear aliphatic radical having 1 or 2 carbon atoms, X is a methylene group (CH2-) and n is 0 or 1.

6. The process as claimed in claim 1, wherein the polyol component B) has a mean functionality of 2 to 6.

7. The process as claimed in claim 1, wherein component B) is a polyhydric alcohol, a ether alcohol or an ester alcohols and/or polymeric polyol, said polymeric polyol having a number-average molecular weight M.sub.n of 200 to 22 000 g/mol.

8. The process as claimed in claim 7, wherein component B) is a polyhydric alcohol and/or a ether alcohol or an ester alcohol containing 2 to 14 carbon atoms.

9. The process as claimed in claim 7, wherein component B) is a polyether polyol, a polyester polyol, a polycarbonate polyol and/or a polyacrylate polyol.

10. A polyurethanes containing cyclic carbonate structures, obtained by the process as claimed in claim 1.

11. A method for the production of crosslinkable binders comprising utilizing the polyurethanes containing cyclic carbonate structures as claimed in claim 10 as a starting component.

12. A method for the production of crosslinkable raw materials for varnishes, sealants or adhesives comprising utilizing the polyurethanes containing cyclic carbonate structures as claimed in claim 10 as a starting component.

13. A crosslinkable binder comprising polyurethanes containing cyclic carbonate structures as claimed in claim 10.

14. The process as claimed in claim 1, wherein component B) comprises an at least difunctional polyol having a number-average molecular weight M.sub.n of 90 to 12000 g/mol.

15. The process as claimed in claim 1, wherein component A) contains component c) in an amount of 0.5% to 10% by weight, based on the total mass of components a) and c).

16. The process as claimed in claim 1, wherein the polyol component B) has a mean functionality of 2 to 4.

Description

EXAMPLES

(1) The invention is illustrated in detail hereinafter by examples.

(2) All percentages are based on weight, unless stated otherwise.

(3) The NCO contents are determined by titrimetric means to DIN EN ISO 11909.

(4) OH numbers were determined by titrimetric means to DIN 53240-2: 2007-11, acid numbers to DIN 3682. The OH contents reported were calculated from the OH numbers determined by analysis.

(5) The residual monomer contents were measured to DIN EN ISO 10283 by gas chromatography with an internal standard.

(6) The proportions of bis adduct (formed from two molecules of hydroxy-functional cyclic carbonate and one molecule of diisocyanate) were determined by gel permeation chromatography based on DIN 55672-1 (Gel permeation chromatography (GPC)Part 1: Tetrahydrofuran (THF) as elution solvent), with the alteration that a flow rate of 0.6 ml/min rather than 1.0 ml/min was employed. The proportions of bis adduct in area % taken from the chromatograms were each equated approximately to proportions in % by weight and reported as such, based on the total amount of mono adduct and bis adduct.

(7) All the viscosity measurements were made with a Physica MCR 51 rheometer from Anton Paar Germany GmbH (DE) to DIN EN ISO 3219.

(8) The melting ranges reported were determined with the aid of a Kofler hot bench from Wagner & Munz GmbH (DE).

(9) Starting Compounds

(10) Preparation of the Compositions A)

(11) Composition A1)

(12) 1680 g (10 mol) of hexamethylene diisocyanate (HDI) were initially charged under dry nitrogen at a temperature of 100 C., 118 g (1 mol) of glycerol carbonate were added within 30 minutes and the mixture was stirred for a further 5 hours until an NCO content of 44.4%, corresponding to full urethanization, had been attained. Subsequently, the unconverted monomeric HDI was removed on a thin-film evaporator at a temperature of 140 C. and a pressure of 0.1 mbar. This gave a virtually colorless, clear isocyanate-functional cyclic carbonate which gradually crystallized through at room temperature within one week.

(13) The product had the following characteristic data:

(14) TABLE-US-00001 NCO content: 14.1% Monomeric HDI: 0.19% Melting range: 28-30 C. Proportion of bis adduct: 3.8%
Composition A2)

(15) By the process described for composition A1), 1776 g (8 mol) of isophorone diisocyanate (IPDI) were reacted with 118 g (1 mol) of glycerol carbonate. On attainment of an NCO content of 33.3%, corresponding to full urethanization, the unconverted monomeric IPDI was removed by thin-film distillation at a temperature of 160 C. and a pressure of 0.2 mbar, and an isocyanate-functional cyclic carbonate was obtained in the form of a clear, pale yellow solid resin.

(16) TABLE-US-00002 NCO content: 11.8% Monomeric IPDI: 0.21% Proportion of bis adduct: 4.5%
Composition A3)

(17) By the process described for composition A1), 2096 g (8 mol) of 4,4-diisocyanatodicyclohexylmethane (H.sub.12-MDI) were reacted with 118 g (1 mol) of glycerol carbonate. On attainment of an NCO content of 28.5%, corresponding to full urethanization, the unconverted monomeric H.sub.12-MDI was removed by thin-film distillation at a temperature of 170 C. and a pressure of 0.2 mbar, and an isocyanate-functional cyclic carbonate was obtained in the form of a clear, pale yellow solid resin.

(18) TABLE-US-00003 NCO content: 10.3% Monomeric H12-MDI: 0.28% Proportion of bis adduct: 4.6%
Composition A4)

(19) By the process described for composition A1), 1344 g (8 mol) of HDI were reacted with 160 g (1 mol) of TMP carbonate. On attainment of an NCO content of 41.9%, corresponding to full urethanization, the unconverted monomeric HDI was removed by thin-film distillation at a temperature of 160 C. and a pressure of 0.2 mbar, and a clear, almost colorless isocyanate-functional cyclic carbonate was obtained with the following characteristic data:

(20) TABLE-US-00004 NCO content: 12.1% Monomeric HDI: 0.17% Viscosity (23 C.): 77 000 mPas Proportion of bis adduct: 5.1%
Composition A5)

(21) By the process described for composition A1), 672 g (4 mol) of HDI were reacted with 118 g (1 mol) of glycerol carbonate. On attainment of an NCO content of 37.2%, corresponding to full urethanization, the unconverted monomeric HDI was removed by thin-film distillation as described in example 1, and a clear, virtually colorless isocyanate-functional cyclic carbonate was obtained, which gradually crystallized through at room temperature within one week.

(22) The product had the following characteristic data:

(23) TABLE-US-00005 NCO content: 13.4% Monomeric HDI: 0.11% Melting range: 27-30 C. Proportion of bis adduct: 9.1%
Composition A6) (Comparison)

(24) By the process described for composition A1), 504 g (3 mol) of HDI were reacted with 118 g (1 mol) of glycerol carbonate. On attainment of an NCO content of 33.8%, corresponding to full urethanization, the unconverted monomeric HDI was removed by thin-film distillation as described in example 1, and a clear, virtually colorless isocyanate-functional cyclic carbonate was obtained, which partly crystallized after being cooled to room temperature.

(25) The product had the following characteristic data:

(26) TABLE-US-00006 NCO content: 12.7% Monomeric HDI: 0.19% Proportion of bis adduct: 13.5%
Polyols B
Polyol B1

(27) Polyacrylate polyol dissolved in a concentration of 70% in butyl acetate, prepared from 33.0% hydroxyethyl methacrylate, 24.3% n-butyl acrylate, 38.8% styrene, 0.9% acrylic acid and 3.0% di-tert-butyl peroxide.

(28) TABLE-US-00007 OH number (OH content) 98 mg KOH/g (3.0%) Equivalent weight: 572 g/eq OH Acid number: 7.5 mg KOH/g Viscosity (23 C.): 3500 mPas
Polyol B2)

(29) Solvent-free polyester polyol, prepared from 11.9% adipic acid, 33.7% isophthalic acid, 10.7% trimethylolpropane, 37.7% hexane-1,6-diol and 6.0% phthalic anhydride.

(30) TABLE-US-00008 OH number (OH content) 143 mg KOH/g (4.3%) Equivalent weight: 392 g/eq OH Acid number: 1 mg KOH/g Viscosity (23 C.): 2500 mPas (as 80% solution in butyl acetate)
Polyol B3)

(31) Polyester polyol dissolved in a concentration of 75% in Solvent naphtha 100, prepared from 19.2% adipic acid, 22.3% maleic anhydride, 4.6% trimethylolpropane, 1.7% propane-1,2-diol and 40.2% neopentyl glycol.

(32) TABLE-US-00009 OH number (OH content) 68 mg KOH/g (2.0%) Equivalent weight: 825 g/eq OH Acid number: 3 mg KOH/g Viscosity (23 C.): 3700 mPas

Example 1

Inventive and Comparative

(33) 297.9 g (1.0 eq) of composition A1) were diluted with 524.3 g of butyl acetate, 565.6 g (1.0 eq) of polyol B1) were added at a temperature of 80 C. under dry nitrogen, and then the mixture was stirred at 90 C. for 8 hours until no isocyanate was detectable any longer by IR spectroscopy. After cooling to room temperature, an inventive polyurethane containing cyclic carbonate structures was present in the form of a colorless solution.

(34) TABLE-US-00010 Solids content: 50% Viscosity (23 C.): 1370 mPas Equivalent weight: 1387.8 g/eq of cyclic carbonate

(35) For comparison, 1680 g (10 mol) of hexamethylene diisocyanate (HDI) were admixed with 283 g (0.5 eq) of polyol B1) at a temperature of 80 C. under dry nitrogen within 20 minutes. The temperature was then increased to 100 C. and stirring of the reaction mixture continued until, after 2 hours, an NCO content of 41.7%, corresponding to full urethanization, had been attained. An attempt to remove the unconverted excess monomeric HDI together with the butyl acetate originating from polyol B1) by thin-film distillation was unsuccessful. At a temperature of 140 C. and a pressure of 0.1 mbar, a solid, non-free-flowing resin formed on the evaporator surface.

(36) The comparison shows that it is not possible to use polyol B1) and HDI to prepare a low-monomer isocyanate-functional prepolymer which could be reacted with glycerol carbonate to give a polyurethane containing cyclic carbonate structures similarly to that obtained in accordance with the invention.

Example 2

Inventive

(37) 282 g (0.9 mol) of composition A5) were initially charged under dry nitrogen in 215 g of 1,1,2,2-tetramethoxyethane as solvent at a temperature of 80 C., 40 g (0.3 mol) of trimethylolpropane (TMP) were added in portions within 20 min, and the mixture was stirred for a further 4 hours until the isocyanate band in the IR spectrum disappeared completely. After cooling to room temperature, an inventive polyurethane containing cyclic carbonate structures was present in the form of a colorless solution.

(38) TABLE-US-00011 Solids content: 60% Viscosity (23 C.): 5220 mPas Equivalent weight: 596.7 g/eq of cyclic carbonate

Example 3

Comparative

(39) 298 g (0.9 mol) of the noninventive composition A6) were initially charged under dry nitrogen in 225 g of 1,1,2,2-tetramethoxyethane as solvent at a temperature of 80 C., 40 g (0.3 mol) of trimethylolpropane (TMP) were added in portions within 20 min, and the mixture was stirred for a further 4 hours until the isocyanate band in the IR spectrum disappeared completely. The 60% solution of a polyurethane bearing terminal cyclocarbonate groups that was present turned very cloudy immediately after being cooled down to room temperature and formed a conspicuous sediment within a few days.

(40) The comparison with the reaction product of the inventive composition A5) with TMP, obtained as a clear solution according to example 2), shows that composition A6), which was prepared using a smaller excess of isocyanate groups than the minimum according to the invention, is not crystallization-stable because of an excessively high proportion of bis adduct and hence is unsuitable for preparation of polyurethanes bearing cyclocarbonate groups.

Example 4

Inventive

(41) 355.9 g (1.0 eq) of composition A2) were diluted with 582.3 g of butyl acetate, 565.6 g (1.0 eq) of polyol B1) were added at a temperature of 80 C. under dry nitrogen, and then the mixture was stirred at 100 C. for 20 hours until no isocyanate was detectable any longer by IR spectroscopy. After cooling to room temperature, an inventive polyurethane containing cyclic carbonate structures was present in the form of a virtually colorless solution.

(42) TABLE-US-00012 Solids content: 50% Viscosity (23 C.): 1510 mPas Equivalent weight: 1503.8 g/eq of cyclic carbonate

Example 5

Inventive

(43) 355.9 g (1.0 eq) of composition A2) were diluted with 651.8 g of butyl acetate, 493.3 g (1.0 eq) of an 80% solution of polyol B2) in butyl acetate were added at a temperature of 80 C. under dry nitrogen, and then the mixture was stirred at 100 C. for 20 hours until no isocyanate was detectable any longer by IR spectroscopy. After cooling to room temperature, an inventive polyurethane containing cyclic carbonate structures was present in the form of a virtually colorless solution.

(44) TABLE-US-00013 Solids content: 50% Viscosity (23 C.): 1490 mPas Equivalent weight: 1501.0 g/eq of cyclic carbonate

Example 6

Inventive

(45) 297.9 g (1.0 eq) of composition A1) were diluted with 722.2 g of Solvent naphtha 100, 848.5 g (1.0 eq) of polyol B3) were added at a temperature of 80 C. under dry nitrogen, and then the mixture was stirred at 90 C. for 8 hours until no isocyanate was detectable any longer by IR spectroscopy. After cooling to room temperature, an inventive polyurethane containing cyclic carbonate structures was present in the form of a virtually colorless solution.

(46) TABLE-US-00014 Solids content: 50% Viscosity (23 C.): 1860 mPas Equivalent weight: 1868.6 g/eq of cyclic carbonate

Example 7

Inventive

(47) 355.9 g (1.0 eq) of composition A2) were diluted with 780.2 g of Solvent naphtha 100, 848.5 g (1.0 eq) of polyol 83) were added at a temperature of 80 C. under dry nitrogen, and then the mixture was stirred at 100 C. for 20 hours until no isocyanate was detectable any longer by IR spectroscopy. After cooling to room temperature, an inventive polyurethane containing cyclic carbonate structures was present in the form of a virtually colorless solution.

(48) TABLE-US-00015 Solids content: 50% Viscosity (23 C.): 1980 mPas Equivalent weight: 1984.6 g/eq of cyclic carbonate

Example 8

Inventive

(49) 407.8 g (1.0 eq) of composition A3) were diluted with 634.2 g of butyl acetate, 565.6 g (1.0 eq) of polyol B1) were added at a temperature of 80 C. under dry nitrogen, and then the mixture was stirred at 100 C. for 20 hours until no isocyanate was detectable any longer by IR spectroscopy. After cooling to room temperature, an inventive polyurethane containing cyclic carbonate structures was present in the form of a pale yellow solution.

(50) TABLE-US-00016 Solids content: 50% Viscosity (23 C.): 2540 mPas Equivalent weight: 1607.6 g/eq of cyclic carbonate

Example 9

Inventive

(51) 347.1 g (1.0 eq) of composition A4) were diluted with 573.5 g of butyl acetate, 565.6 g (1.0 eq) of polyol B1) were added at a temperature of 80 C. under dry nitrogen, and then the mixture was stirred at 90 C. for 8 hours until no isocyanate was detectable any longer by IR spectroscopy. After cooling to room temperature, an inventive polyurethane containing cyclic carbonate structures was present in the form of a colorless solution.

(52) TABLE-US-00017 Solids content: 50% Viscosity (23 C.): 1420 mPas Equivalent weight: 1486.2 g/eq of cyclic carbonate

Example 10

Inventive, Self-Crosslinker

(53) 149.0 g (0.5 eq) of composition A1) were diluted with 193.7 g of butyl acetate, 565.6 g (1.0 eq) of polyol B1) were added at a temperature of 80 C. under dry nitrogen, and then the mixture was stirred at 90 C. for 8 hours until no isocyanate was detectable any longer by IR spectroscopy. After cooling to room temperature, an inventive polyurethane that contained cyclic carbonate structures and was simultaneously hydroxy-functional was present in the form of a colorless solution.

(54) TABLE-US-00018 Solids content: 60% Viscosity (23 C.): 2370 mPas Equivalent weight: 1816.6 g/eq of cyclic carbonate Equivalent weight: 1816.6 g/eq OH

Example 11-16

Use, Inventive

(55) The inventive polyurethanes 1), 4), 5) and 7) containing cyclic carbonate structures were used to formulate varnishes together with the amino-functional co-reactants listed in table 1, and each was adjusted to a solids content of 50%. The varnishes were applied to glass panes in a wet film thickness of about 100 m, flashed off at room temperature for 15 minutes and dried at 70 C. or 120 C. for 30 min. In all cases, shiny transparent varnish films were obtained. Table 1 below shows the compositions of the varnish formulations (parts by weight in each case) and properties of the resultant coatings.

(56) TABLE-US-00019 TABLE 1 Example 11 12 13 14 15 16 Polyurethane 82.6 from example 1 Polyurethane 83.6 from example 4 Polyurethane 83.6 88.8 from example 5 Polyurethane 87.2 91.2 from example 7 Jeffamin T 8.7 8.2 8.2 6.4 4.4 403 [1] tetraethylene- 5.6 pentamine [2] butyl acetate 8.7 8.2 8.2 5.6 Solvent 6.4 4.4 Naphtha 100 Crosslinking 120 120 120 70 70 120 temperature ( C.) Appearance of OK OK OK OK OK OK film Layer thickness 50 45 45 50 50 45 (m) Pendulum 47/48 114/129 116/131 112/193 87/100 166/209 hardness (s) after 24/48 h [3] Acetone 1 1-2 2-3 1 2 1-2 resistance [4] [1] Trifunctional polyetheramine (Huntsman Corp., Zaventem, Belgium), equivalent weight: 146.7 g/eq of amine [2] Equivalent weight: 94.7 g/eq of amine (based on primary amino groups) [3] Knig pendulum hardness (DIN 53157) [4] Resistance of the cured varnish film to acetone after a contact time of 1 min. Rating: 0-5 (0 = varnish film unchanged; 1 = visible change; 2 = perceptible softening; 3 = significant softening; 4 = softened through to the substrate; 5 = completely destroyed without any outside influence)

Examples 17

Use, Self-Crosslinker

(57) 100 parts by weight of the inventive polyurethane that contained cyclic carbonate structures and simultaneously hydroxyl groups from example 10) were admixed with 0.5 part by weight of sodium laurate as catalyst, adjusted to a solids content of 50% by addition of 20 parts by weight of butyl acetate and then applied to a glass pane in a wet film thickness of about 100 m. After flashing off at room temperature for 15 minutes, the varnish was baked at 160 C. for 30 min. A shiny transparent varnish film was obtained. The pendulum hardness was 66 s after 24 h; the acetone resistance was 1-2 (rating as in table 1, defined in footnote [4]).