Binders containing secondary amine groups, based on cyclic ethers

Abstract

The present invention relates to a process for producing polyaspartic ester compositions by reacting cyclic ethers bearing primary amino and/or primary aminoalkyl groups with fumaric and/or maleic esters, to the polyaspartic ester compositions thus obtainable, and to the use thereof in two-component coating compositions.

Claims

1. A composition A1 comprising one or more polyaspartic esters of the general formula (I) ##STR00012## in which X is an m-valent organic radical obtained by removing the primary amino groups from cyclic ethers, said ethers being monocycles or fused bicycles based on monocyclic ethers and which on at least 2 of a ring carbon atoms bear a group selected from primary amino group and aliphatically attached primary amino group, where R1 and R2 are identical or different organic radicals each having 1 to 18 carbon atoms and m is an integer >1, and optionally one or more polyaspartic esters having a primary amino group of the general formula (II) ##STR00013## in which n is m−1 and X and the radicals R1 and R2 are as defined above, wherein the cyclic ethers from which X is derived and which on at least 2 of the ring carbon atoms bear a group selected from primary amino group and aliphatically attached primary amino group having the compounds of formula V ##STR00014## are monocycles or bicycles according to the following general formulas III and IV: ##STR00015## where Y.sup.1 is Y.sup.1a, Y.sup.1b, Y.sup.1c, Y.sup.1d, Y.sup.1e, Y.sup.1f, Y.sup.1g, Y.sup.1h or, Y.sup.1i: ##STR00016## and Y.sup.2 is Y.sup.2a, Y.sup.2b, Y.sup.2c, Y.sup.2d, Y.sup.2e, or Y.sup.2f: ##STR00017## and Y.sup.3 is Y.sup.3a, Y.sup.3b, Y.sup.3c, Y.sup.3d, Y.sup.3e, or Y.sup.3f: ##STR00018## and R.sup.1, R.sup.2, R.sup.7, R.sup.8, R.sup.13, R.sup.14 are independently: (i) an alkylene group having 1 to 6 carbon atoms, wherein one C-atom of the alkylene group is attached to a NH.sub.2-group; (ii) hydrogen; or (iii) organic radicals, the latter being saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic monovalent radicals having up to 18 carbon atoms, which may optionally contain heteroatoms from the series oxygen, sulfur and nitrogen, and R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.10, R.sup.11, R.sup.12 are independently: (i) a linear or branched alkylene group having 1 to 6 carbon atoms, wherein one C-atom of the alkylene group is attached to a NH.sub.2-group; (ii) a NH.sub.2-group; (iii) a hydrogen; or (iv) organic radicals, the latter being saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic monovalent radicals having up to 18 carbon atoms, which may optionally contain heteroatoms from the series oxygen, sulfur and nitrogen, where in the case of formula III at least 2 of the radicals R.sup.1 to R.sup.8 comprise a NH.sub.2 group, and in the case of formula IV at least one of the radicals R.sup.1 to R.sup.8 comprise a NH.sub.2 group and at least one of the radicals R.sup.10 to R.sup.14 comprise a NH.sub.2 group, and R.sup.9 and R.sup.9′ are independently H or a methyl radical, and R.sup.1′ to R.sup.8′, and R.sup.10′ to R.sup.14′ are independently hydrogen or organic radicals, the latter being saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic monovalent radicals having up to 18 carbon atoms, which may optionally contain heteroatoms from the series oxygen, sulfur and nitrogen.

2. A process for producing compositions A1 comprising one or more polyaspartic esters of the general formula (I) ##STR00019## in which X is an m-valent organic radical obtained by removing the primary amino groups from cyclic ethers, said ethers being monocycles or fused bicycles based on monocyclic ethers and which on at least 2 of a ring carbon atoms bear a group selected from primary amino group and aliphatically attached primary amino group, where R1 and R2 are identical or different organic radicals each having 1 to 18 carbon atoms and m is an integer >1, and optionally one or more polyaspartic esters having a primary amino group of the general formula (II) ##STR00020## in which n is m−1 and X and the radicals R1 and R2 are as defined above, by reacting polyamines of the general formula (V) ##STR00021## in which X and m are as defined above, with compounds of the general formula (VI)
R1OOC—CH═CH—COOR2  (VI) where R1 and R2 are as defined above, wherein the cyclic ethers from which X is derived and which on at least 2 of the ring carbon atoms bear a group selected from primary amino group and aliphatically attached primary amino group having the compounds of formula V, are monocycles or bicycles according to the following general formulas III and IV: ##STR00022## where Y.sup.1 is Y.sup.1a, Y.sup.1b, Y.sup.1c, Y.sup.1d, Y.sup.1e, Y.sup.1f, Y.sup.1g, Y.sup.1h or, Y.sup.1i: ##STR00023## and Y.sup.2 is Y.sup.2a, Y.sup.2b, Y.sup.2c, Y.sup.2d, Y.sup.2e, or Y.sup.2f: ##STR00024## and Y.sup.3 is, ##STR00025## and R.sup.1, R.sup.2, R.sup.7, R.sup.8, R.sup.13, R.sup.14 are independently: (i) an alkylene group having 1 to 6 carbon atoms, wherein one C-atom of the alkylene group is attached to a NH.sub.2-group; (ii) hydrogen; or (iii) organic radicals, the latter being saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic monovalent radicals having up to 18 carbon atoms, which may optionally contain heteroatoms from the series oxygen, sulfur and nitrogen, and R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.10, R.sup.11, R.sup.12 are independently: (i) a linear or branched alkylene group having 1 to 6 carbon atoms, wherein one C-atom of the alkylene group is attached to a NH.sub.2-group; (ii) a NH.sub.2-group; (iii) a hydrogen; or (iv) organic radicals, the latter being saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic monovalent radicals having up to 18 carbon atoms, which may optionally contain heteroatoms from the series oxygen, sulfur and nitrogen, where in the case of formula III at least 2 of the radicals R.sup.1 to R.sup.8 comprise a NH.sub.2 group, and in the case of formula IV at least one of the radicals R.sup.1 to R.sup.8 comprise a NH.sub.2 group and at least one of the radicals R.sup.10 to R.sup.14 comprise a NH.sub.2 group, and R.sup.9 and R.sup.9′ are independently H or a methyl radical, and R.sup.1′ to R.sup.8′, and R.sup.10′ to R.sup.14′ are independently hydrogen or organic radicals, the latter being saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or optionally substituted aromatic or araliphatic monovalent radicals having up to 18 carbon atoms, which may optionally contain heteroatoms from the series oxygen, sulfur and nitrogen.

3. The composition A1 as claimed in claim 1, wherein the alkylene groups having 1 to 6 carbon atoms are CH.sub.2, CH.sub.2—CH.sub.2, CH.sub.2—CH.sub.2—CH.sub.2 or CH.sub.2—CH.sub.2—CH.sub.2—CH.sub.2.

4. The composition A1 as claimed in claim 1, wherein the radicals R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.10, R.sup.11, R.sup.12, R.sup.13, R.sup.14, where they are hydrogen or organic radicals, are independently hydrogen and/or alkyl radicals each having 1 to 8 carbon atoms.

5. The composition A1 as claimed in claim 1, in which X was obtained by removing the primary amino groups from cyclic ethers that are based on starting materials obtained in a biobased manner.

6. The composition A1 as claimed in claim 1 in a mixture with a further polyaspartic ester containing composition different from the composition A1.

7. A coating composition, comprising a) at least one polyaspartic ester-containing composition A1 as claimed in claim 1, b) at least one polyisocyanate component B, c) optionally one or more components C different from A1 and reactive toward isocyanate groups, (d) optionally auxiliaries and additives (component D).

8. A process for coating a substrate that comprises at least the following steps: i) applying a coating composition as claimed in claim 7 to at least part of a substrate to be coated; and ii) curing the coating composition from step i).

9. A substrate coated with a coating obtained in accordance with a process as claimed in claim 8.

10. The process for producing the composition A1 as claimed in claim 2 wherein the alkylene groups having 1 to 6 carbon atoms are CH.sub.2, CH.sub.2—CH.sub.2, CH.sub.2—CH.sub.2—CH.sub.2 or CH.sub.2—CH.sub.2—CH.sub.2—CH.sub.2.

11. The process for producing the composition A1 as claimed in claim 2, wherein the radicals R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.10, R.sup.11, R.sup.12, R.sup.13, R.sup.14, where they are hydrogen or organic radicals, are independently hydrogen and/or alkyl radicals each having 1 to 8 carbon atoms.

12. The process for producing the composition A1 as claimed in claim 2, in which X was obtained by removing the primary amino groups from the cyclic ethers that are based on starting materials obtained in a biobased manner.

13. The coating composition of claim 7, wherein the composition is a two-component coating composition.

14. The composition A1 according to claim 1, wherein in formula III Y.sup.1 is i) Y.sup.1a, wherein R.sup.1 and R.sup.2 are each CH.sub.2—NH.sub.2, and R.sup.1′, R.sup.2′, R.sup.3, and R.sup.3′ are independently organic radicals having up to 18 carbon atoms or H, ii) Y.sup.1b, wherein two of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are CH.sub.2—NH.sub.2, and two of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 and also R.sup.1′ to R.sup.4′ are independently organic radicals having up to 18 carbon atoms or H, or R.sup.3 and R.sup.4 are NH.sub.2, and R.sup.1, R.sup.1′, R.sup.2, R.sup.2′, R.sup.3′, and R.sup.4′ are independently organic radicals having up to 18 carbon atoms or H, iii) Y.sup.1c, wherein two of R.sup.1, R.sup.2, R.sup.3, and R.sup.5 are CH.sub.2—NH.sub.2, and two of R.sup.1, R.sup.2, R.sup.3, and R.sup.5 and also R.sup.1′ to R.sup.5′ and R.sup.4 are independently organic radicals having up to 18 carbon atoms or H, or R.sup.3 and R.sup.4 are NH.sub.2, and R.sup.1, R.sup.2, R.sup.5 and also R.sup.1′ to R.sup.5′ are independently organic radicals having up to 18 carbon atoms or H, or R.sup.3 and R.sup.5 are NH.sub.2, and R.sup.1, R.sup.2, R.sup.4 and also R.sup.1′ to R.sup.5′ are independently organic radicals having up to 18 carbon atoms or H, or R.sup.1 is CH.sub.2—NH.sub.2 and one of R.sup.3, R.sup.4 and R.sup.5 is NH.sub.2, and two of R.sup.3, R.sup.4 and R.sup.5, and also R.sup.1′ to R.sup.5′ and R.sup.2, are independently organic radicals having up to 18 carbon atoms or H, iv) Y.sup.1d, wherein two of R.sup.1, R.sup.2, R.sup.3, and R.sup.6 are CH.sub.2—NH.sub.2, and two of R.sup.1, R.sup.2, R.sup.3, and R.sup.6, and also R.sup.4, R.sup.5, and R.sup.1′ to R.sup.6′ are independently organic radicals having up to 18 carbon atoms or H, or R.sup.3 and R.sup.6 are NH.sub.2, and R.sup.1, R.sup.2, R.sup.4, R.sup.5 and R.sup.1′ to R.sup.6′ are independently organic radicals having up to 18 carbon atoms or H, or R.sup.1 is CH.sub.2—NH.sub.2 and R.sup.3 or R.sup.6 is NH.sub.2, and one of R.sup.3 and R.sup.6, and also R.sup.1′ to R.sup.5′ and R.sup.2 are independently organic radicals having up to 18 carbon atoms or H, v) Y.sup.1e, wherein two of R.sup.1, R.sup.2, and R.sup.7 are CH.sub.2—NH.sub.2, and one of R.sup.1, R.sup.2, and R.sup.7, and also R.sup.1′, R.sup.2′, and R.sup.7′ are independently organic radicals having up to 18 carbon atoms or H, vi) Y.sup.1f, wherein two of R.sup.1, R.sup.2, R.sup.7, and R.sup.8 are CH.sub.2—NH.sub.2, and two of R.sup.1, R.sup.2, R.sup.7, and R.sup.8, and also R.sup.1′, R.sup.2′, R.sup.7′, and R.sup.8′ are independently organic radicals having up to 18 carbon atoms or H, vii) Y.sup.1g, wherein two of R.sup.1, R.sup.2, R.sup.3, and R.sup.7 are CH.sub.2—NH.sub.2, and two of R.sup.1, R.sup.2, R.sup.3, and R.sup.7, and also R.sup.1′, R.sup.2′, R.sup.3′, and R.sup.7′ are independently organic radicals having up to 18 carbon atoms or H, or R.sup.1 is CH.sub.2—NH.sub.2 and R.sup.3 is NH.sub.2, and R.sup.2, R.sup.7, R.sup.1′, R.sup.2′, R.sup.3′, and R.sup.7′ are independently organic radicals having up to 18 carbon atoms or H, viii) Y.sup.1h, wherein two of R.sup.1, R.sup.2, R.sup.3, R.sup.7, and R.sup.8 are CH.sub.2—NH.sub.2, and three of R.sup.1, R.sup.2, R.sup.3, R.sup.7, and R.sup.8, and also R.sup.1′, R.sup.2′, R.sup.3′, R.sup.7,′ and R.sup.8′ are independently organic radicals having up to 18 carbon atoms or H, or R.sup.1 is CH.sub.2—NH.sub.2 and R.sup.3 is NH.sub.2, and R.sup.2, R.sup.7, and R.sup.8 and also R.sup.1′, R.sup.2′, R.sup.3′, R.sup.7′, and R.sup.8′ are independently organic radicals having up to 18 carbon atoms or H, or ix) Y.sup.1i, wherein two of R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.7 are CH.sub.2—NH.sub.2, and three of R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.7, and also R.sup.1′, R.sup.2′, R.sup.3′, R.sup.4′, and R.sup.7′ are independently organic radicals having up to 18 carbon atoms or H, or R.sup.1 is CH.sub.2—NH.sub.2 and R.sup.3 or R.sup.4 is NH.sub.2, and R.sup.3 or R.sup.4, and also R.sup.2, R.sup.7, R.sup.1′, R.sup.2′, R.sup.3′, R.sup.4′, and R.sup.7′, are independently organic radicals having up to 18 carbon atoms or H.

15. The composition A1 according to claim 14, wherein in formula III Y.sup.1 is embodiment ii) or iii): ii) Y1 is Y.sup.1b, R.sup.1 and R.sup.2 are each CH.sub.2—NH.sub.2, and R.sup.3, R.sup.4 and also R.sup.1′ to R.sup.4′ are independently organic radicals having up to 18 carbon atoms or H, or R.sup.3 and R.sup.4 are CH.sub.2—NH.sub.2 or NH.sub.2, and R.sup.1, R.sup.2 and also R.sup.1′ to R.sup.4′ are independently organic radicals having up to 18 carbon atoms or H, or iii) Y1 is Y.sup.1c, R.sup.1 and R.sup.2 are CH.sub.2—NH.sub.2, and R.sup.3, R.sup.4, R.sup.5 and also R.sup.1′ to R.sup.5′ are independently organic radicals having up to 18 carbon atoms or H, or R.sup.3 and R.sup.5 are CH.sub.2—NH.sub.2 or NH.sub.2, and R.sup.1, R.sup.2, R.sup.4 and also R.sup.1′ to R.sup.5′ are independently organic radicals having up to 18 carbon atoms or H.

16. The composition A1 according to claim 14, wherein in formula III Y.sup.1 is embodiment ii) or iii): ii) Y1 is Y.sup.1b, R.sup.1 and R.sup.2 are CH.sub.2—NH.sub.2, and R.sup.3, R.sup.4 and also R.sup.1′ to R.sup.4′ are independently a methyl radical or H, or R.sup.3 and R.sup.4 are CH.sub.2—NH.sub.2 or NH.sub.2, and R.sup.1, R.sup.2 and also R.sup.1′ to R.sup.4′ are independently a methyl radical or H, or iii) Y1 is Y.sup.1c, R.sup.1 and R.sup.2 are CH.sub.2—NH.sub.2, and R.sup.3, R.sup.4, R.sup.5 and also R.sup.1′ to R.sup.5′ are independently a methyl radical or H, or R.sup.3 and R.sup.5 are CH.sub.2—NH.sub.2 or NH.sub.2, and R.sup.1, R.sup.2, R.sup.4 and also R.sup.1′ to R.sup.5′ are independently a methyl radical or H.

17. The composition A1 according to claim 1, wherein the compounds of formula III are oxacyclopentane-2,3-, -2,4-, -2,5- or -3,4-di-methyleneamine or oxacyclohexane-2,3-, -2,4-, -2,5-, -2,6-, -3,4- or -3,5-di-methyleneamine.

18. The composition A1 according to claim 1, wherein in formula IV Y.sup.2 and Y.sup.3 are a) Y.sup.2a and Y.sup.3a, R.sup.2 is CH.sub.2—NH.sub.2 or R.sup.10 is CH.sub.2—NH.sub.2 or NH.sub.2and R.sup.1 is CH.sub.2—NH.sub.2 or R.sup.3 is CH.sub.2—NH.sub.2 or NH.sub.2, and R.sup.2 or R.sup.10, R.sup.1 or R.sup.3, and also R.sup.1′, R.sup.2′, R.sup.3′, and R.sup.10′ are independently methyl, ethyl, propyl, isopropyl, butyl or isobutyl radicals or H, and R.sup.9, R.sup.9′ are independently CH.sub.3 or H, b) Y.sup.2a and Y.sup.3b, R.sup.2 is CH.sub.2—NH.sub.2 or R.sup.10 is CH.sub.2—NH.sub.2 or NH.sub.2 and R.sup.1 is CH.sub.2—NH.sub.2 or R.sup.3 or R.sup.4 is CH.sub.2—NH.sub.2 or NH.sub.2, and R.sup.2 or R.sup.10, at least one of R.sup.1, R.sup.3, and R.sup.4, and also R.sup.1′, R.sup.2′, R.sup.3′, R.sup.4′, and R.sup.10′ are independently methyl, ethyl, propyl, isopropyl, butyl or isobutyl radicals or H, and R.sup.9, R.sup.9′ are independently CH.sub.3 or H, c) Y.sup.2a and Y.sup.3d, R.sup.2 is CH.sub.2—NH.sub.2 or R.sup.10 is CH.sub.2—NH.sub.2 or NH.sub.2 and R.sup.1 or R.sup.7 is CH.sub.2—NH.sub.2, and R.sup.2 or R.sup.10, R.sup.1 or R.sup.7, and also R.sup.1′, R.sup.2′, R.sup.7′, and R.sup.10′ are independently methyl, ethyl, propyl, isopropyl, butyl or isobutyl radicals or H, and R.sup.9, R.sup.9′ are independently CH.sub.3 or H, d) Y.sup.2b and Y.sup.3b, R.sup.2 is CH.sub.2—NH.sub.2 or R.sup.10 or R.sup.11 is CH.sub.2—NH.sub.2 or NH.sub.2 and R.sup.1 is CH.sub.2—NH.sub.2 or R.sup.3 or R.sup.4 is CH.sub.2—NH.sub.2 or NH.sub.2, and at least one of R.sup.2, R.sup.10, and R.sup.11, the at least one of R.sup.1, R.sup.3, and R.sup.7, and also R.sup.1′, R.sup.2′, R.sup.3′, R.sup.4′, R.sup.10′, and R.sup.11′ are independently methyl, ethyl, propyl, isopropyl, butyl or isobutyl radicals or H, and R.sup.9, R.sup.9′ are independently CH.sub.3 or H, e) Y.sup.2d and Y.sup.3d, R.sup.2 or R.sup.13 is CH.sub.2—NH.sub.2 and R.sup.1 or R.sup.7 is CH.sub.2—NH.sub.2, and R.sup.2 or R.sup.13, R.sup.1 or R.sup.7, and also R.sup.1′, R.sup.2′, R.sup.7′, and R.sup.13′ are independently methyl, ethyl, propyl, isopropyl, butyl or isobutyl radicals or H, and R.sup.9, R.sup.9′ are independently CH.sub.3 or H, or f) Y.sup.2b and Y.sup.3d, R.sup.2 is CH.sub.2—NH.sub.2 or R.sup.10 or R.sup.11 is CH.sub.2—NH.sub.2 or NH.sub.2 or R.sup.1 or R.sup.7 is CH.sub.2—NH.sub.2, and at least one of R.sup.2, R.sup.10 and R.sup.11, R.sup.1 or R.sup.7, and also R.sup.1′, R.sup.2′, R.sup.7′, R.sup.10′, and R.sup.11 are independently methyl, ethyl, propyl, isopropyl, butyl or isobutyl radicals or H, and R.sup.9 and R.sup.9′ are independently CH.sub.3 or H.

19. The composition A1 according to claim 18, wherein in formula IV Y.sup.2 and Y.sup.3 are embodiments a), b) or d).

20. The composition A1 according to claim 1, wherein the compound of formula IV is selected from the group consisting of 3R,3aR,6R,6aR-hexahydrofuro[3,2-b]furan-3,6-diamine; 3R,3aR,6S,6aR-hexahydrofuro[3,2-b]furan-3,6-diamine; 3S,3aR,6S,6aR-hexahydrofuro[3,2-b]furan-3,6-diamine; [3R,3aR,6R,6aR-6-(aminomethyl)-hexahydrofuro[3,2-b]furan-3-yl]methanamine; [3R,3aR,6S,6aR-6-(aminomethyl)-hexahydrofuro[3,2-b]furan-3-yl]methanamine; [3S,3aR,6S,6aR-6-(aminomethyl)-hexahydrofuro[3,2-b]furan-3-yl]methanamine; and mixtures thereof.

Description

EXPERIMENTAL PART

(1) Raw Materials and Substrates:

(2) Desmophen NH 1220: an amino-functional co-reactant having an amine value of 240-248 mg KOH/g, a viscosity (25° C.) of ≤100 mPa.Math.s, and a color index (Hazen) of ≤250, manufacturer: Covestro.

(3) Desmophen NH 1420: an amino-functional co-reactant having an amine value of 199-203 mg KOH/g, a viscosity (25° C.) of 900-2000 mPa.Math.s, and a color index (Hazen) of ≤250, manufacturer: Covestro.

(4) Desmodur N 3900: A low-viscosity HDI trimer having approx. 23.5% NCO, a viscosity (25° C.) of approx. 730 mPa.Math.s, and ≤0.25% free HDI, manufacturer: Covestro.

(5) Solvents: Solvesso 100, 1-methoxy-2-propyl acetate (MPA), ethyl acetate (EA), butyl acetate (BA), acetone (Ac), and xylene (Xy), Azelis, Germany.

(6) Tetrahydrofurandimethanamine, Merck, Germany.

(7) 3S,3aR,6S,6aR-Hexahydrofuro[3,2-b]furan-3,6-diamine Merck, Germany.

(8) [3S,3aR,6S,6aR-6-(Aminomethyl)-hexahydrofuro[3,2-b]furan-3-yl]-methanamine Merck, Germany.

(9) Diethyl maleate: Aldrich, Germany.

(10) 3R,3aR,6S,6aR-Hexahydrofuro[3,2-b]furan-3,6-diamine was prepared by the method described in ChemSusChem 2011, 4, 1823-1829.

(11) Methods:

(12) Dimethyl fumarate contents were quantitatively determined using a GC method with internal standard. An Agilent 6890 gas chromatograph with a standard GC capillary (100% polysiloxane phase) and FID detector were used. The injector temperature (split outlet) was 180° C.; helium was used as the carrier gas. The quantitation limit of this method was 300 ppm.

(13) GC-MS analyses were carried out using an Agilent 6890 gas chromatograph and Agilent 5973 mass spectrum detector with standard ionization (electron impact) at 70 eV, a standard GC capillary (100% polysiloxane phase), and split injection at an injector temperature of 250° C. Evaluation of the gas chromatograms was in area-%.

(14) All viscosity measurements were carried out using a Physica MCR 51 rheometer from Anton Paar Germany GmbH (DE) in accordance with DIN EN ISO 3219:1994-10 at 23° C.

(15) Hazen color index values were determined on a Lico 400 colorimeter from Hach Lange GmbH (Germany) in accordance with DIN EN ISO 6271:2016-05

(16) Amine values were determined titrimetrically in accordance with EN ISO 9702:1998 (perchloric acid method) with the exception that the results were expressed as the amine value. The amine value in mg KOH/g was calculated according to the following equation:

(17) $\mathrm{AA}\mathrm{AAA}\mathrm{AAAAA}=\frac{\left(A-A\right)A5.61}{A}$

(18) a=Volume of perchloric acid used in the main test, in milliliters, concentration c=0.1 mol/1 (included in factor 5.61);

(19) b=Volume of perchloric acid used in the blank test, in milliliters, concentration c=0.1 mol/1 (included in factor 5.61);

(20) W=Weight of sample, in grams

(21) The gel time was determined using a Tecam gelation timer from Techne Corp. This method is used to determine the time interval from addition of the curing agent until gelation of the paint, as a measure of the reactivity of the system.

(22) Drying was determined in accordance with DIN EN ISO 9117-5:2012-11 on glass.

(23) Solvent stabilities were determined in accordance with DIN EN ISO 4628-1:2016-07. The solvent stabilities test was carried out using the solvents xylene (also abbreviated hereinafter to “Xy”), methoxypropyl acetate (also abbreviated hereinafter to “MPA”), ethyl acetate (also abbreviated hereinafter to “EA”), and acetone (also abbreviated hereinafter to “Ac”). The contact time was 5 min in each case. The test specimens were made in accordance with the standard cited. The test surface is assessed visually and by scratching, using the following classification: 0=no change apparent; 1=swelling ring, hard surface, only visible change; 2=swelling ring, slight softening; 3=distinct softening (possibly slight blistering); 4=significant softening (possibly severe blistering), can be scratched through to the substrate; 5=coating completely destroyed without outside influence.

(24) König pendulum damping was determined in accordance with DIN EN ISO 1522; 2007-04 on glass plates. The dry film thickness was 45-52 μm for all films.

(25) The cross-cut test was carried out in accordance with DIN EN ISO 2409:2006-13.

(26) The gloss at 20° of the coatings obtained was measured reflectometrically in accordance with DIN EN ISO 2813:2015-02.

(27) Scratching—crockmeter:

(28) The coating material is scratched using a crockmeter in accordance with DIN EN ISO 105-X12:2016-11. The coated substrate is positioned parallel to the direction of the friction finger. At a frequency of one cycle per second, a straight-line rubbing movement is performed on the dry sample 20 times over a distance of 104±3 mm, this comprising 10 sets of back and forth movements at a downward force of 9±0.2 N. The gloss of the specimen is then determined reflectometrically.

(29) Reflow:

(30) The reflow describes the recovery of a scratched coating surface, based on the gloss value, after thermal stress. A coating is scratched by dry scratching (crockmeter). The residual gloss is determined after the scratching cycle. The coating is placed in the oven at 60° C. for 2 h and the gloss is then determined according to the procedure described above. The reflow is reported in percent, i.e. the ratio of residual gloss after heat-treatment to gloss before scratching.

(31) Weathering: CAM 180:

(32) The accelerated weathering studies in the presence of UV radiation were carried out in accordance with SAE J2527. The test plates were checked every 250 h. UV-A test:

(33) The UV-A tests of the coating materials were carried out in accordance with DIN EN ISO 16474-3:2014-03 (cycle 1). The test plates were checked every 250 h. Calculation of the b value and delta E:

(34) The delta E value can be calculated from the L, a, and b values determined in the Lab color space in accordance with DIN ISO/CIE 11664-4:2019-04 using a Dr. Lange Micro Color II.

(35) Syntheses of the Polyaspartic Esters (PAEs) of the Invention

(36) PAE 1:

(37) ##STR00009##

(38) Prepared using tetrahydrofurandimethanamine

(39) PAE 2:

(40) ##STR00010##

(41) Prepared using [3S,3aR,6S,6aR-6-(aminomethyl)-hexahydrofuro[3,2-b]furan-3-yl]-methanamine.

(42) PAEs 3 and 4:

(43) ##STR00011##

(44) Prepared using two isomers: PAE 3: 3S,3aR,6S,6aR-hexahydrofuro[3,2-b]furan-3,6-diamine and PAE 4: 3R,3aR,6S,6aR-hexahydrofuro[3,2-b]furan-3,6-diamine

(45) Polyaspartic Ester PAE 1 (of the Invention)

(46) 340.2 g of tetrahydrofurandimethanamine (rel-((2R,5S)-tetrahydrofuran-2,5-diyl)dimethanamine, cis) was initially charged at 30° C. under dry nitrogen and with stirring. To this was added dropwise 900.0 g of diethyl maleate, ensuring that the temperature did not rise above 60° C. At the end of the addition, the temperature was adjusted to 45° C. and the mixture was stirred at 45° C. for 1 hour. The mixture was then stored at 23° C. for 1 week. A light-colored product was obtained that had the following material data:

(47) TABLE-US-00001 Diethyl fumarate (GC) 1.74% by weight Viscosity 170 mPas Color index 22 APHA Amine value 234 mg KOH/g

(48) Polyaspartic Ester PAE 3 (of the Invention)

(49) 72.08 g of (3S,3aR,6S,6aR)-hexahydrofuro[3,2-b]furan-3,6-diamine was initially charged under dry nitrogen and heated to 90° C. with stirring. To this was added dropwise 172.0 g of diethyl maleate, ensuring that the temperature did not remain at 90° C. At the end of the addition, the temperature was adjusted to 60° C. and the mixture was stirred at 60° C. for 2 hours. The mixture was then stored at 23° C. for 20 weeks. A product was obtained that had the following material data:

(50) TABLE-US-00002 Diethyl fumarate (GC) 4.82% by weight Amine value 240 mg KOH/g Viscosity 1010 mPas

(51) Polyaspartic Ester PAE 2 (of the Invention)

(52) 86.11 g of [(3S,3aR,6S,6aR)-6-(aminomethyl)-hexahydrofuro[3,2-b]furan-3-yl]methanamine was initially charged at 30° C. under dry nitrogen and with stirring. To this was added dropwise 172.0 g of diethyl maleate, ensuring that the temperature did not rise above 60° C. At the end of the addition, the temperature was adjusted to 45° C. and the mixture was stirred at 45° C. for one hour. The mixture was then stored at 23° C. for 4 weeks. A product was obtained that had the following material data:

(53) TABLE-US-00003 Diethyl fumarate (GC) 5.35% by weight Amine value 253 mg KOH/g Viscosity 850 mPas

(54) Polyaspartic Ester PAE 4 (of the Invention)

(55) 72.08 g of (3R,3aR,6S,6aR)-hexahydrofuro[3,2-b]furan-3,6-diamine was initially charged under dry nitrogen and heated to 90° C. with stirring. To this was added dropwise 172.0 g of diethyl maleate, ensuring that the temperature did not rise above 90° C. At the end of the addition, the temperature was adjusted to 60° C. and the mixture was stirred at 60° C. for 2 hours. The mixture was then stored at 23° C. for 8 weeks. A product was obtained that had the following material data:

(56) TABLE-US-00004 Diethyl fumarate (GC) 8.75% by weight Amine value 226 mg KOH/g Viscosity 420 mPas

(57) Preparation of the Coatings:

(58) TABLE-US-00005 TABLE 1 Weights in grams 1 2 (comp.) (comp.) 3 4 5 6 Coating base: PAE 1 100.00 PAE 2 100.00 PAE 3 50.00 PAE 4 100 Desmophen 100.00 35.00 NH 1220 Desmophen 65.00 NH 1420 Curing agent Desmodur N 76.50 68.93 75.18 69.30 36.64 73.28 3900 Total 176.50 168.93 175.18 169.30 86.64 173.28 Ratio (NCO/ 1.0 1.0 1.0 1.0 1.0 1.0 NH) Gel time in 1 min. 11 min 5 min 4 min 162 min 187 min min

(59) Mixing of the coating base with the curing agent and application:

(60) The components A (coating base) and B (curing agent) mentioned above were in each case combined and mixed thoroughly. The mixtures were then applied to the glass plates using an applicator frame (wet layer thickness 90 μm) and dried at room temperature (23° C.). Brilliant, high-gloss coatings with a dry film thickness of 45 to 52 μm were obtained. An overview of the coating properties determined for the coatings is shown in Tables 2 to 4.

(61) TABLE-US-00006 TABLE 2 1 2 Example (comp.) (comp.) 3 4 5 6 Dry film thickness (μm) 50 45 45 52 50 52 Pendulum hardness after 1 day 52 174 194  148 170 136 after 7 days 191  171 200 202 Solvent resistance after 1 day xylene (1/5 min) 2/2 2/2 1/1 1/2 1/1 2/3 MPA (1/5 min) 2/3   2/2-3 1/2 1/1 1/2 2/3 ethyl acetate (1/5 min) 2-3/5   3/5 2/3 2/3 2/4 4/4 acetone (1/5 min) 5/5 5/5 3/4 4/4 3/4 4/5 Solvent resistance after 7 days xylene (1/5 min) 1/1 1/1 1/2 1/1 MPA (1/5 min) 1/2 1/1 2/2 1/1 ethyl acetate (1/5 min) 1/3 2/3 2/5 2/3 acetone (1/5 min) 3/4 3/3 4/5 3/3 Scratch resistance - Crockmeter (dry scratching) Gloss 20° Start 86 84 86 n.d. n.d. After 5 15 13 n.d. n.d. scratching 2 h 60° C. 21 63 40 n.d. n.d. oven Rel. gloss retention 24.4%  75% 46.5% n.d. n.d.

(62) Solvent Resistance:

(63) Measured on clearcoats on glass plate. Assessment: 0-5 (0=film coating unchanged; 5=fully dissolved)

(64) As can be seen from the table, coatings based on the polyaspartic esters of the invention have considerably better solvent resistance and considerably better reflow behavior than coatings based on polyaspartic esters of the prior art.

(65) Weathering Tests:

(66) i) Gloss Development:

(67) TABLE-US-00007 TABLE 3 0 250 500 750 1000 1250 1500 1750 2000 h Gloss development 20° UVA 1 88 93 93 91 89 89 82 87 87 3 89 76 93 90 88 88 88 90 89 2 (comp.) 88 93 94 92 90 88 86 88 90 CAM 180 1 87 88 88 82 87 89 83 86 86 3 85 90 91 88 89 87 89 86 0 2 (comp.) 85 76 68 78 87 0

(68) As can be seen from Table 3, the gloss development of the coatings of the invention is comparable to coatings based on polyaspartic esters of the prior art.

(69) ii) Resistance to Yellowing:

(70) TABLE-US-00008 TABLE 4 0 250 500 750 1000 1250 1500 1750 2000 0 250 500 750 1000 1250 1500 1750 2000 h b value Delta E UVA: 1 −0.9 0.6 1.3 3.2 4.7 5.5 5.6 5.7 6 0 1.8 2.5 4.4 6 6.7 6.9 7 7.4 3 8.9 13.6 13 13.5 12.6 12.6 12.6 12.2 11.3 0 5.4 5 5.4 5.6 6.1 6.2 5.8 5.5 2 −0.4 2.1 1.9 3.3 5.2 6.8 7.8 8.4 9 0 2.6 2.5 3.9 5.8 7.5 8.5 9.1 9.8 CAM 180: 1 −0.4 1.2 2.6 3 3 2.9 2.8 2.8 2.9 0 1.7 3.2 3.6 3.6 3.5 3.4 3.4 3.5 3 4.9 3.3 3.2 3.1 3.3 3.8 3.4 3.2 3.2 0 0.6 0.4 1.2 0.7 0.8 0.8 0.9 2 −0.3 0.9 1.3 2.7 2.7 3.4 2.1 2.6 4.6 0 1.3 1.8 3.2 3.4 4.4 2.6 3.2 5.5

(71) As can be seen from Table 4, the coatings of the invention exhibit considerably better resistance to yellowing than corresponding polyaspartate-based coatings of the prior art.