Isocyanate-functional cyclic carbonates

Abstract

The invention relates to a process for preparing compounds containing isocyanate groups and cyclic carbonate structures, by reacting at least A) a monomeric diisocyanate with aliphatically, cycloaliphatically, araliphatically and/or aromatically bonded isocyanate groups with B) a hydroxy-functional cyclic carbonate, characterized in that component A) is reacted with component B) in an equivalents ratio of isocyanate groups to hydroxyl groups of at least 8:1. The invention further relates to the products obtainable by the process according to the invention, and to a composition comprising compounds containing isocyanate groups and cyclic carbonate structures. The invention additionally relates to the use of the products obtainable by the process according to the invention and of the composition as a starting component in the preparation of polyurethanes containing cyclic carbonate structures, crosslinkable binders, and also raw materials for coatings, sealants or adhesives.

Claims

1. A composition comprising a) a compound of the general formula (III) containing an isocyanate group and a cyclic carbonate structure, ##STR00004## b) a compound of the general formula (IV) containing cyclic carbonate structures, ##STR00005## and c) a monomeric diisocyanate having aliphatically, cycloaliphatically, araliphatically and/or aromatically bonded isocyanate groups, where, in the formulae (III) and (IV), 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, wherein, based in each case on the total amount of components a) and b), component a) makes up a proportion of 88% by weight, and component b) a proportion of 12% by weight, and component c) is present to an extent of 1% by weight, in the overall composition.

2. The composition as claimed in claim 1, wherein component b) makes up a proportion of 0.5% to 12% by weight, based on the total amount of components a) and b).

3. A method comprising utilizing the composition as claimed in claim 1 as a starting component in the production of polyurethanes containing cyclic carbonate structures or as a starting component in the production of crosslinkable binders or as a starting component in the production of crosslinkable raw materials for varnishes, sealants or adhesives.

4. A polyurethane containing cyclic carbonate structures, prepared using the composition containing isocyanate groups and cyclic carbonate structures as claimed in claim 1.

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 were determined by titrimetric means to DIN EN ISO 11909.

(4) OH numbers were determined by titrimetric means to DIN 53240-2: 2007-11.

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

(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) at room temperature, 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, which were determined with software support, 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 to ANSI/ASTM D 3451-76 with the aid of a Kofler hot bench from Wagner & Munz GmbH (DE).

Example 1

Inventive

(9) 1344 g (8 mol) of hexamethylene diisocyanate (HDI) were initially charged under dry nitrogen at a temperature of 100 C., 118 g (1 mol) of glycerol carbonate was added within 30 minutes and the mixture was stirred for a further 5 hours until an NCO content of 43.1%, 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.

(10) The product had the following characteristic data:

(11) NCO content: 14.0%

(12) Monomeric HDI: 0.18%

(13) Melting range: 28-30 C.

(14) Proportion of bis adduct: 4.6%

Example 2

Inventive

(15) By the process described in example 1, 1008 g (6 mol) of HDI were reacted with 118 g (1 mol) of glycerol carbonate. On attainment of an NCO content of 41.0%, 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.

(16) The product had the following characteristic data:

(17) NCO content: 14.0%

(18) Monomeric HDI: 0.18%

(19) Melting range: 28-30 C.

(20) Proportion of bis adduct: 6.1%

Example 3

Inventive

(21) By the process described in example 1, 1680 g (10 mol) of HDI were reacted with 118 g (1 mol) of glycerol carbonate. On attainment of an NCO content of 44.4%, 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) NCO content: 14.1%

(24) Monomeric HDI: 0.19%

(25) Melting range: 28-30 C.

(26) Proportion of bis adduct: 3.8%

Example 4

Inventive

(27) By the process described in example 1, 1680 g (10 mol) of HDI were reacted with 59 g (0.5 mol) of glycerol carbonate. On attainment of an NCO content of 45.9%, 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.

(28) The product had the following characteristic data:

(29) NCO content: 14.4%

(30) Monomeric HDI: 0.09%

(31) Melting range: 29-31 C.

(32) Proportion of bis adduct: 1.9%

Example 5

Inventive

(33) By the process described in example 1, 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.

(34) The product had the following characteristic data:

(35) NCO content: 13.4%

(36) Monomeric HDI: 0.11%

(37) Melting range: 27-30 C.

(38) Proportion of bis adduct: 9.1%

Example 6

Inventive

(39) By the process described in example 1, 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.

(40) NCO content:

(41) Monomeric IPDI: 0.21%

(42) Proportion of bis adduct: 4.5%

Example 7

Inventive

(43) By the process described in example 1, 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.

(44) NCO content: 10.3%

(45) Monomeric H.sub.12-MDI: 0.28%

(46) Proportion of bis adduct: 4.6%

Example 8

Inventive

(47) By the process described in example 1, 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 as described in example 1, and a clear, colorless isocyanate-functional cyclic carbonate was obtained with the following characteristic data:

(48) NCO content: 12.1%

(49) Monomeric HDI: 0.17%

(50) Viscosity (23 C.): 77 000 mPas

(51) Proportion of bis adduct: 5.1%

Example 9

Inventive

(52) 118 g (1 mol) of glycerol carbonate and 114 g (1 mol) of -caprolactone were mixed at room temperature under dry nitrogen, 0.02 g of ortho-phosphoric acid was added and then the mixture was heated to 160 C. for 5 h. After cooling to room temperature, a colorless polyester alcohol having terminal cyclic carbonate structures was present with the following characteristic data:

(53) OH number: 244 mg KOH/g

(54) Free -caprolactone: 0.15%

(55) Viscosity (23 C.): 2950 mPas

(56) Mean molecular weight (calc. from OH number); 230

(57) 230 g (1.0 mol) of this glycerol carbonate/-caprolactone adduct were reacted with 1344 g (8 mol) of HDI by the process described in example 1. On attainment of an NCO content of 40.0%, 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 having ester groups was obtained with the following characteristic data:

(58) NCO content: 9.8%

(59) Monomeric HDI: 0.19%

(60) Viscosity (23 C.): 3100 mPas

(61) Proportion of bis adduct: 5.3%

Example 10

Comparative

(62) By the process described in example 1, 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.

(63) The product had the following characteristic data:

(64) NCO content: 12.7%

(65) Monomeric HDI: 0.19%

(66) Proportion of bis adduct: 13.5%

Example 11

Use, Inventive

(67) 270 g (0.9 mol) of the isocyanate-functional cyclic carbonate from example 1 were initially charged under dry nitrogen in 207 g of 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% clear solution of a polyurethane bearing terminal cyclocarbonate groups that was present had a viscosity of 5540 mPas at 23 C.

Example 12

Comparative

(68) To 1680 g (10 mol) of HDI at a temperature of 80 C. under dry nitrogen were added 134 g (1 mol) of TMP within one hour, and the mixture was stirred for one further hour until an NCO content of 39.4%, corresponding to full urethanization, had been attained. Subsequently, the unconverted monomeric HDI was removed on a thin-layer evaporator at a temperature of 130 C. and a pressure of 0.1 mbar. This gave a colorless clear polyisocyanate having an NCO content of 16.7%, a content of monomeric HDI of 0.21% and a viscosity (23 C.) of 480 000 mPas.

(69) 251 g (1.0 eq) of this high-viscosity polyisocyanate were dissolved in 246 g of tetramethoxyethane under dry nitrogen, then 118 g (1.0 mol) of glycerol carbonate were added at a temperature of 80 C. and the mixture was stirred for a further 5 hours until the isocyanate band in the IR spectrum disappeared completely. The 60% solution of a polyurethane bearing terminal cyclocarbonate groups that was present had a viscosity of 12 360 mPas at 23 C.

(70) Compared to the reaction product of an inventive isocyanate-functional cyclic carbonate with TMP obtained according to example 11, the reaction product of a hydroxy-functional cyclic carbonate with a low-monomer isocyanate prepolymer based on TMP prepared according to example 12 exhibits a much lower viscosity, even though the two polyurethanes are based on the same starting components.

Example 13

Use, Inventive

(71) 282 g (0.9 mol) of the isocyanate-functional cyclic carbonate from example 5 were initially charged under dry nitrogen in 215 g of 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% clear solution of a polyurethane bearing terminal cyclocarbonate groups that was present had a viscosity of 5220 mPas at 23 C.

Example 14

Use, Comparative

(72) 298 g (0.9 mol) of the noninventive isocyanate-functional cyclic carbonate from example 10 were initially charged under dry nitrogen in 225 g of 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 one day.

(73) Comparison with the reaction product of the inventive isocyanate-functional cyclic carbonate from example 1) with TMP, obtained as a clear solution according to example 13), shows that the isocyanate-functional cyclic carbonate from example 10), 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.