PROCESS FOR THE PREPARATION OF ALICYCLIC POLYISOCYANATE

Abstract

The present invention relates to a polyisocyanate (P) of general formula (I), the method for preparing polysisocyanate (P) of general formula (I) and the use of polyisocyanate (P) of general formula (I) as crosslinking reagent in clearcoats. The method for preparing polyisocyanate (P) of general formula (I) comprises the reaction of a reaction mixture (RM), which comprises at least one cyclic isocyanate of general formula (IIIa), (IIIb), (IIIc), (IIId), (IIIe) and/or (IIIf) and at least one alcohol having at least two hydroxyl groups, to obtain polyisocyanate (P) of general formula (I).

Claims

1: A polyisocyanate of formula (I): ##STR00008## where k, m, n are each independently 0, 1, 2 or 3, wherein a sum total of k, m and n is at least 2 and at most 6; and L is a linear or branched organic radical having at most 14 carbon atoms, which optionally comprises at least one nitrogen atom and/or at least one oxygen atom, R.sup.a, R.sup.b, R.sup.c are each independently selected from the group consisting of radicals of formulae (IIa), (IIb), (IIc), (IId), (IIe) and/or (IIf): ##STR00009## where o is 0 to 10, and R.sup.1, R.sup.1, R.sup.2, R.sup.2, R.sup.3, R.sup.3, R.sup.4, R.sup.4 are each independently selected from the group consisting of H, OR.sup.5 and unsubstituted or at least monosubstituted C.sub.1-C.sub.10-alkyl, C.sub.5-C.sub.12-cycloalkyl, C.sub.2-C.sub.10-alkenyl and C.sub.6-C.sub.14-aryl, where R.sup.5 is C.sub.1-C.sub.10-alkyl.

2: The polyisocyanate according to claim 1, wherein L is a linear or branched aliphatic, cycloaliphatic or aromatic radical having at most 14 carbon atoms, which optionally comprises at least one nitrogen atom and/or at least one oxygen atom, and R.sup.a, R.sup.b, R.sup.c are each independently selected from the group consisting of the radicals of formulae (IIa), (IIb), (IIc), (IId), (IIe) and/or (IIf), where o is 0, 2 or 3, and R.sup.1, R.sup.1, R.sup.2, R.sup.2, R.sup.3, R.sup.3, R.sup.4, R.sup.4 are each independently selected from the group consisting of H and C.sub.1-C.sub.10-alkyl.

3: The polyisocyanate according to claim 1, wherein L is a linear or branched aliphatic or cycloaliphatic radical having at most 14 carbon atoms, which optionally comprises at least one nitrogen atom and/or at least one oxygen atom, R.sup.a, R.sup.b, R.sup.c are each independently selected from the group consisting of the radicals of formulae (IIa), (IIb) and/or (IIc), where R.sup.1, R.sup.1, R.sup.2, R.sup.2, R.sup.3, R.sup.3, R.sup.4, R.sup.4 are each independently selected from the group consisting of H, methyl, ethyl and propyl.

4: The polyisocyanate according to claim 1, wherein k is 2 or 3, and m, n are 0, and L is a linear or branched aliphatic radical having at most 10 carbon atoms, which optionally comprises at least one nitrogen atom and/or at least one oxygen atom, R.sup.a is selected from the group consisting of the radicals of formulae (IIa), (IIb) and/or (IIc): ##STR00010## where R.sup.1, R.sup.1, R.sup.2, R.sup.2, R.sup.3, R.sup.3, R.sup.4, R.sup.4 are each independently selected from the group consisting of H, methyl and ethyl, wherein at least one radical of R.sup.1, R.sup.1, R.sup.2, R.sup.2, R.sup.3, R.sup.3, R.sup.4 or R.sup.4 is methyl or ethyl.

5: The polyisocyanate according to claim 1, wherein k is 3, and m, n are 0, and L is a linear or branched aliphatic radical having at most 6 carbon atoms, which optionally comprises at least one oxygen atom, R.sup.a is a radical of the formula (IIb): ##STR00011## where R.sup.1, R.sup.1, R.sup.2, R.sup.2, R.sup.3, R.sup.3, R.sup.4, R.sup.4 are each independently selected from the group consisting of H, methyl and ethyl, wherein at least one radical and at most 3 radicals of R.sup.1, R.sup.1, R.sup.2, R.sup.2, R.sup.3, R.sup.3, R.sup.4 or R.sup.4 are methyl or ethyl.

6: A polyisocyanate of formula (IV): ##STR00012## where R.sup.1, R.sup.1, R.sup.2, R.sup.2 are each independently selected from the group consisting of H and methyl, wherein at least one radical and at most two radicals of R.sup.1, R.sup.1, R.sup.2 or R.sup.2 are methyl, and R.sup.3, R.sup.3, R.sup.4 and R.sup.4 are H.

7: A method for preparing the polyisocyanate according to claim 1, the method comprising reacting a reaction mixture comprising components (a) and (b): (a) at least one cyclic isocyanate of formulae (IIIa), (IIIb), (IIIc), (IIId), (IIIe) and/or (IIIf): ##STR00013## where o is 0 to 10, and R.sup.1, R.sup.1, R.sup.2, R.sup.2, R.sup.3, R.sup.3, R.sup.4, R.sup.4 are each independently selected from the group consisting of H, OR.sup.5 and unsubstituted or at least monosubstituted C.sub.1-C.sub.10-alkyl, C.sub.5-C.sub.12-cycloalkyl, C.sub.2-C.sub.10-alkenyl and C.sub.6-C.sub.14-aryl, where R.sup.5 is C.sub.1-C.sub.10-alkyl, and (b) at least one alcohol having at least two hydroxyl groups, to obtain a composition (C) comprising the polyisocyanate.

8: The method according to claim 7, wherein the component (a) is selected from the group consisting of 1,3-diisocyanatocyclohexane, 1,3-diisocyanato-2-methylcyclohexane, 1,3-diisocyanato-4-methylcyclohexane, 1,3-diisocyanato-5-methylcyclohexane, 1,3-diisocyanato-2-isopropylcyclohexane, 1,3-diisocyanato-4-isopropylcylohexane, 3-diisocyanato-5-isopropylcyclohexane, 1,3-diisocyanato-2,4-dimethylcyclohexane, 1,3-diisocyanato-2,4-diethylcyclohexane, 1,3-diisocyanato-2,4-diethyl-6-methylcyclohexane, 1,3-diisocyanato-2-methyl-4,5-diethylcyclohexane, 1,3-diisocyanato-2,4,6-triisopropylcyclohexane, and 1,3-diisocyanato-2,4,6-tributylcyclohexane.

9: The method according to claim 7, wherein the component (b) is selected from the group consisting of ethylene glycol, 1,1-dimethylethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, 2-ethyl-1,4-butanediol, 1,5-pentanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 2,4-diethyloctane-1,3-diol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, tripropylene glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, glycerol, cyclohexane-1,2-diol, cyclohexane-1,3-diol, cyclohexane-1,4-diol, 1,1-bis(hydroxymethyl)cyclohexane, 1,2-bis(hydroxymethyl)cyclohexane, 1,3-bis(hydroxymethyl)cyclohexane, 1,4-bis(hydroxymethyl)cyclohexane, 2,2-bis(4-hydroxycyclohexyl)propane, erythritol, threitol, xylitol, adonitol (ribitol), arabitol (lyxitol), sorbitol, mannitol, dulcitol (galactitol), maltitol, isomalt, diglycerol, dimethylolpropane, dipentaerythritol, ribose, arabinose, glucose, mannose, galactose, fructose, pyrocatechol, catechol, hydroquinone, pyrogallol, hydroxyhydroquinone, phloroglucinol, neopentyl glycol hydroxypivalate, triethanolamine, tripropanolamine, 1,3,5-tris(2-hydroxyethyl)cyanuric acid, a polytetrahydrofuran having a molecular weight between 162 and 4500 g/mol, a poly-1,3-propanediol or a polypropylene glycol having a molecular weight between 134 and 2000 g/mol, and a polyethylene glycol having a molecular weight between 238 and 2000 g/mol.

10: The method according to claim 7, wherein the component (b) comprises at least two alcohols, at least one alcohol comprises two hydroxyl groups, and at least one alcohol comprises three hydroxyl groups.

11: The method according to claim 7, wherein the reaction mixture comprises 70 to 99% by weight of the component (a) and 1 to 30% by weight of the component (b), based on a total weight of components (a) and (b) in the reaction mixture.

12: The method according to claim 7, wherein i) the reaction mixture is reacted at a temperature in the range from 20 C. to 90 C., and/or ii) the reaction mixture is reacted in the absence of a catalyst.

13: The method according to claim 7, further comprising: terminating the reaction of the reaction mixture by adding at least one component (c), after at least a portion of the components (a) and (b) has been reacted.

14: The method according to claim 7, further comprising terminating the reaction after at least one of the components (a) or (b) has been fully reacted, and/or separating unreacted amounts of the component (a) and/or (b) from the composition (C).

15: A method for crosslinking in a clearcoat, the method comprising: Introducing the polyisocyanate according to claim 1 as a crosslinking reagent into the clearcoat.

16: The method according to claim 13, wherein the at least one component (c) is selected from the group consisting of toluenesulfonic acid, toluolsulfonyl chloride, benzoyl chloride, benzyl chloride, dibutyl prosphite, cibutyl phosphate, and di-12-ethylhexyl phosphate.

Description

EXAMPLES

[0171] The at least one cyclic isocyanate (a) (component (a)) used in the following working examples is MCDI (a mixture of 1,3-diisocyanato-4-methylcyclohexane and 1,3-diisocyanato-2-methylcyclohexane). The alcohol comprising two hydroxyl groups used in the following examples is diethylene glycol. The alcohol comprising at least three hydroxyl groups used in the following examples is trimethylolpropane.

[0172] The content of NCO groups in polyisocyanates is determined by the methods described hereinafter:

[0173] 0.5 g of a polyisocyanate-containing mixture is precisely weighed and dissolved in 100 ml of N-methylpyrrolidone. To this solution are added 10 ml of a 1N solution of n-dibutylamine in xylene. The mixture thus obtained is left to stand at room temperature for 15 minutes, whereupon the polyisocyanate and n-dibutylamine react with each other. After reaction is complete, the mixture formed is back-titrated with 1N hydrochloric acid in order to determine the total volume of hydrochloric acid that is necessary to neutralize unreacted n-dibutylamine in the mixture.

[0174] The polyisocyanates obtained by the method according to the invention are characterized by means of gel permeation chromatography (GPC).

[0175] Instrument description of the GPC system: [0176] Injector: Autosampler WATERS 717 Plus [0177] Eluent: Tetrahydrofuran (flow rate: 0.5 ml/min) [0178] Pump: WATERS Model 515 (double piston pump) [0179] Detector 1: UV detector WATERS 2489 (wavelength: 254 nm) [0180] Detector 2: Differential refractometer WATERS 2414 (measurement temperature: 35 C.) [0181] Column attachment: PL gel columns (6007.5 mm), 4 columns connected in series [0182] Column packing: crosslinked polystyrene-divinylbenzene matrix, particle size 5 m [0183] Pore width: 150 [0184] 3100 [0185] Calibration: Basonat HI 100, molar mass range 2200-168 g/mol [0186] Software: PSS WinGPC Unity NT

Comparative Example 1

[0187] 500 g of isophorone diisocyanate (IPDI), 44 g of trimethylolpropane and 14.16 g of diethylene glycol are initially charged in a 1 l three-necked flask with thermometer (linked to an oil bath with adjustable temperature), stirrer, reflux condenser and nitrogen inlet and heated to 80 C. while stirring. The alteration of the NCO content during the reaction of the starting materials is determined by titration as detailed above. The reaction is terminated by adding 300 ppm of a mixture of benzyl chloride and bis(2-ethylhexyl) phosphate (50/50% by weight), after the NCO content has reached the theoretical value for the complete reaction of the isophorone diisocyanate with trimethylolpropane and diethylene glycol. The colorless composition thus obtained is purified by thin-film distillation at 3 mbar and 175 C. in order to remove unreacted isophorone diisocyanate.

[0188] 240.1 g of this composition are dissolved in 102.9 g of butyl acetate. The resulting yellowish solution (70% by weight in butyl acetate) has an NCO content of 8.6% and a viscosity of 1810 mPa-s.

Working Example 1

[0189] 500 g of MCDI, 44 g of trimethylolpropane and 14.16 g of diethylene glycol are initially charged in a 1 l three-necked flask with thermometer (linked to an oil bath with adjustable temperature), stirrer, reflux condenser and nitrogen inlet and heated to 80 C. while stirring. The alteration of the NCO content during the reaction of the starting materials is determined by titration as detailed above. The reaction is terminated by adding 300 ppm of a mixture of benzyl chloride and bis(2-ethylhexyl) phosphate (50/50% by weight), after the NCO content has reached the theoretical value for the complete reaction of the MCDI with trimethylolpropane and diethylene glycol. The colorless composition thus obtained is purified by thin-film distillation at 3 mbar and 175 C. in order to remove unreacted isophorone diisocyanate.

[0190] 251.1 g of this composition are dissolved in 107.6 g of butyl acetate. The resulting yellowish solution (70% by weight in butyl acetate) has an NCO content of 10.6% and a viscosity of 2000 mPa.Math.s.