Aqueous crosslinking agent composition

Abstract

The present invention relates to a polyaziridine crosslinking agent composition, characterized in that the composition is an aqueous dispersion in a pH range of 9 to 14 and contains a polyaziridine compound in a dispersed form, wherein the polyaziridine compound has: a. 2 to 6 of the following structural units A, where R1, R2, R3, and R4 are H; m is 1, and R' and R” are according to (1) or (2): R' = H or an aliphatic hydrocarbon group containing 1 to 14 carbon atoms; and R” = an aliphatic hydrocarbon group containing 1 to 4 carbon atoms, CH2-O-(C=O)-R”', or CH2-O-R””, where R”' is an alkyl group containing 4 to 12 carbon atoms and R”” is an alkyl group containing 1 to 14 carbon atoms, (2) R' and R” together form a saturated alicyclic hydrocarbon group containing 5 to 8 carbon atoms; b. one or more linking chains, where each of these linking chains links two of the structural units A in the structural unit A; and c. a molecular weight in the range of 600 daltons to 10,000 daltons.

Description

[0001] The present invention relates to a polyaziridine crosslinking agent composition which can be used for crosslinking carboxylic acid functional polymers dissolved and / or dispersed in an aqueous medium.

[0002] Coatings provide protection, aesthetic qualities, and new functionality to a variety of substrates with great industrial and domestic relevance. In this context, there is a growing demand for coatings with improved resistance (such as stain resistance and solvent resistance), improved mechanical properties, and improved adhesion strength. One or more of these properties can be enhanced by means of crosslinking. Many crosslinking mechanisms for polymer binders have been studied over the years, and for aqueous latex polymer dispersions, the most useful polymer binders include isocyanate crosslinking of hydroxyl functional polymers, carbodiimide crosslinking of carboxylic acid functional polymers, melamine crosslinking, epoxy crosslinking, and aziridine crosslinking of carboxylic acid functional polymers.

[0003] Aqueous binders are usually colloidally stabilized by carboxylic acid groups and the coating properties can be improved by using carbodiimide or aziridine crosslinking agents since the crosslinking agent reacts with the carboxylic acid moiety of the polymer to produce a crosslinked network. Among the state-of-the-art crosslinking agents as described above, aziridine crosslinking agents are the most versatile (the most general) for room temperature curing of carboxylic acid functional polymers.

[0004] Conventional crosslinking methods typically involve using low molecular weight reactive organic molecules, occasionally dissolved in volatile organic solvents to reduce viscosity, thereby facilitating the accurate dosing / mixing of the crosslinking agent into the polymer composition to be crosslinked. Good miscibility of the crosslinking agent with the polymer composition is important for the final properties (poor miscibility tends to result in inefficient crosslinking) and for the efficiency of the material and user convenience. However, using volatile organic solvents to reduce viscosity is undesirable as this will increase the VOC (volatile organic compound) level. In addition, the presence of solvents in the crosslinking agent composition will reduce the formulation freedom of the coating composition formulator and is therefore undesirable. Therefore, it would be beneficial to deliver the polyaziridine crosslinking agent in water. At the same time, it is necessary to maintain the crosslinking agent performance in terms of crosslinking efficiency and storage stability to maintain commercial viability in various polymer resins.

[0005] However, currently available state-of-the-art polyaziridine crosslinkers lack stability in an aqueous environment. For example, CX-100 (trimethylolpropane tris(2-methyl-1-aziridinepropionate); CAS No. 64265-57-2) and XAMA-7 (pentaerythritol tris[3-(1-aziridinyl)propionate]; CAS No. 57116-45-7) provide very efficient reactions with carboxylic acids, but these crosslinkers are unstable in water and thus have a limited shelf life in water. This is described, for example, in US-A-5133997. In addition, these polyaziridines have an unfavorable genotoxic profile.

[0006] It is an object of the present invention to provide polyaziridine crosslinkers which can be delivered and stored in water with a longer shelf life while maintaining sufficient reactivity towards carboxylic acid-functional polymers.

[0007] This object has surprisingly been achieved by providing a polyaziridine crosslinker composition, characterized in that the composition is an aqueous dispersion having a pH in the range of 9 to 14 and comprising a polyaziridine compound in dispersed form, wherein

[0008] the polyaziridine compound has:

[0009] a. 2 to 6 of the following structural units A:

[0010]

[0011] wherein

[0012] R1, R2, R3 and R4 are H,

[0013] m is 1,

[0014] R' and R” are according to (1) or (2):

[0015] (1) R' = H or an aliphatic hydrocarbon group having 1 to 14 carbon atoms; and

[0016] R” = an alkyl group having 1 to 4 carbon atoms, CH2-O-(C=O)-R”' or CH2-O-R””, where R”' is an alkyl group having 4 to 12 carbon atoms and R”” is an alkyl group having 1 to 14 carbon atoms,

[0017] (2) R' and R” together form a saturated alicyclic hydrocarbon group having 5 to 8 carbon atoms;

[0018] b. one or more linking chains, wherein each of these linking chains links two of the structural units A in the structural unit A; and

[0019] c. A molecular weight in the range of 600 to 10,000 Daltons.

[0020] It has surprisingly been found that the aqueous crosslinker compositions of the present invention have an extended storage stability while still having good crosslinking efficiency towards carboxylic acid functional polymers, especially in aqueous dispersions of carboxylic acid functional polymers. The compositions according to the invention show a high efficiency reaction with carboxylic acid groups at room temperature. The aqueous nature of the compositions according to the invention is also easy to use, and their water-containing nature results in good compatibility with aqueous binders and thus good mixing and low fouling during formulation. Further, these compositions generally have a low viscosity, resulting in easy handling and accurate dosing. The combination of extended storage stability in water with more favorable hazard properties enables paint manufacturers and applicators to store and use the crosslinker compositions easily and safely in two-component 2K paint systems, where the binder and the crosslinker are mixed shortly before application.

[0021] US-A-3523750 describes a method for modifying protein substrates such as wool with polyaziridine compounds. US-A-5258481 describes multifunctional water-dispersible crosslinkers which are oligomeric materials containing carbodiimide functional groups and reactive functional groups different from the carbodiimide functional groups. US-A-5241001 discloses polyaziridine compounds obtained by reacting 1-(2-hydroxyethyl)-ethyleneimine with polyisocyanates.

[0022] For all upper and / or lower boundaries of any range given herein, unless otherwise specifically indicated, the boundary values are included in the given range. Thus, when it is said from x to y, it means including x and y as well as all intermediate values.

[0023] In this specification, the term "coating composition" encompasses paints, coatings, varnishes, binder and ink compositions, but is not limited to this list. The term "aliphatic hydrocarbon group" means an optionally (as used herein, "optionally") branched alkyl, alkenyl and alkynyl group. The term "alicyclic hydrocarbon group" means a cycloalkyl and cycloalkenyl group optionally substituted by at least one aliphatic hydrocarbon group. The term "aromatic hydrocarbon group" means a benzene ring optionally substituted by at least one aliphatic hydrocarbon group. These optional aliphatic hydrocarbon group substituents are preferably alkyl groups. Examples of alicyclic hydrocarbon groups having 7 carbon atoms are cycloheptyl and methyl-substituted cyclohexyl. Examples of aromatic hydrocarbon groups having 7 carbon atoms are methyl-substituted phenyl. Examples of aromatic hydrocarbon groups having 8 carbon atoms are dimethylphenyl and ethyl-substituted phenyl.

[0024] The aziridinyl group has the following structural formula:

[0025]

[0026] Polyaziridine compound

[0027] Although the structural units A present in the polyaziridine compound may independently have different R' and / or R", the structural units A present in the polyaziridine compound are preferably identical to each other.

[0028] Preferably, R' = H, and R" = an alkyl group having 1 to 4 carbon atoms, CH2-O-(C=O)-R'", or CH2-O-R"", where R"' is an alkyl group having 3 to 12 carbon atoms, preferably 4 to 12 carbon atoms, such as neopentyl or neodecyl. Most preferably, R"' is a branched C9 alkyl group. R"" is an alkyl group having 1 to 14 carbon atoms, preferably 1 to 12 carbon atoms. Non-limiting examples of R"" are ethyl, butyl, and 2-ethylhexyl.

[0029] The polyaziridine compound contains 2 to 6 structural units A, preferably 2 to 4 structural units A, more preferably 2 or 3 structural units A.

[0030] The polyaziridine compound contains one or more linking chains, where each of these linking chains links two structural units A in the structural unit A. The linking chains present in the polyaziridine compound preferably consist of 4 to 300 atoms, more preferably 5 to 250 atoms, more preferably 6 to 100 atoms, and most preferably 6 to 20 atoms. The atoms of the linking chain are preferably C and optionally N, O, S, and / or P, preferably C and optionally N and / or O. The linking chain is preferably a set of covalently linked atoms, and the set of atoms consists of i) carbon atoms, ii) carbon and nitrogen atoms, or iii) carbon, oxygen, and nitrogen atoms.

[0031] The linking chain is defined as the shortest chain of consecutive atoms that links two structural units A. The following figure shows an example of a polyaziridine compound and the linking chain between two structural units A.

[0032]

[0033] Any two structural units A in the structural units A present in the polyaziridine compound are linked by a linking chain as defined herein. Thus, each structural unit A present in the polyaziridine compound is connected to each other structural unit A by a linking chain as defined herein. In the case where the polyaziridine compound has two structural units A, the polyaziridine compound has one such linking chain that links these two structural units.

[0034] In the case where the polyaziridine compound has three structural units A, the polyaziridine compound has three linking chains, where each of the three linking chains links a structural unit A to another structural unit A, that is, the first structural unit A is linked to the second structural unit A through a linking chain, and both the first and second structural units A are independently linked to the third structural unit A through their respective linking chains.

[0035] The following drawings show examples of polyaziridine compounds having three structural units A and three linking chains, where each of the three linking chains links two structural units A.

[0036]

[0037] A polyaziridine compound having more than two structural units A has a number of linking chains according to the following equation:

[0038] LC = {(AN - 1) × AN} / 2, where LC = the number of linking chains in the polyaziridine compound, and AN = the number of structural units A in the polyaziridine compound. Thus, for example, if there are 5 structural units A in the polyaziridine compound, AN = 5; this means there are {(5 - 1) × 5} / 2 = 10 linking chains.

[0039] The molecular weight of the polyaziridine compound according to the present invention is preferably from 600 daltons to 5000 daltons. The molecular weight of the polyaziridine compound according to the present invention is preferably at most 3800 daltons, more preferably at most 3600 daltons, more preferably at most 3000 daltons, more preferably at most 2300 daltons, and even more preferably at most 1600 daltons. The molecular weight of the polyaziridine compound according to the present invention is preferably at least 700 daltons, more preferably at least 800 daltons, even more preferably at least 840 daltons, and most preferably at least 1000 daltons. As used herein, the molecular weight of the polyaziridine compound is the calculated molecular weight. The calculated molecular weight is obtained by adding up the atomic masses of all the atoms present in the structural formula of the polyaziridine compound. If the polyaziridine compound is present in a composition comprising more than one polyaziridine compound according to the present invention, for example when one or more of the starting materials used to prepare the polyaziridine compound are mixtures, then the molecular weight calculation can be performed for each compound present separately in the composition. As described in the following experimental section, the molecular weight of the polyaziridine compound according to the present invention can be measured using MALDI-TOF mass spectrometry.

[0040] The polyaziridine compound preferably contains one or more linking groups, where each of these linking groups links two structural units A in the structural unit A, and where each of these linking groups consists of at least one functional group selected from the group consisting of: aliphatic hydrocarbon functional groups (preferably containing 1 to 8 carbon atoms), cycloaliphatic hydrocarbon functional groups (preferably containing 4 to 10 carbon atoms), aromatic hydrocarbon functional groups (preferably containing 6 to 12 carbon atoms), isocyanurate functional groups, iminooxadiazindione functional groups, ether functional groups, ester functional groups, amide functional groups, carbonate functional groups, carbamate functional groups, urea functional groups, biuret functional groups, urethane functional groups, allophanate functional groups, and any combination thereof. More preferably, the linking group is an array of consecutive functional groups, where each functional group is selected from the group consisting of: aliphatic hydrocarbon functional groups (preferably containing 1 to 8 carbon atoms), cycloaliphatic hydrocarbon functional groups (preferably containing 4 to 10 carbon atoms), aromatic hydrocarbon functional groups (preferably containing 6 to 12 carbon atoms), isocyanurate functional groups, iminooxadiazindione functional groups, ether functional groups, ester functional groups, amide functional groups, carbonate functional groups, carbamate functional groups, urea functional groups, biuret functional groups, urethane functional groups, allophanate functional groups.

[0041] The term "aliphatic hydrocarbon functional group" refers to optionally branched alkyl, alkenyl, and alkynyl groups. Although the optional side chains of C atoms are part of the linking group, they are not part of the linking chain.

[0042] The term "cycloaliphatic hydrocarbon functional group" refers to cycloalkyl and cycloalkenyl groups optionally substituted by at least one aliphatic hydrocarbon group. Although the optional aliphatic hydrocarbon group substituents are part of the linking group, they are not part of the linking chain. The optional aliphatic hydrocarbon group substituents are preferably alkyl groups.

[0043] The term "aromatic hydrocarbon functional group" refers to a benzene ring optionally substituted by at least one aliphatic hydrocarbon group. Although the optional aliphatic hydrocarbon group substituents are part of the linking group, they are not part of the linking chain. The optional aliphatic hydrocarbon group substituents are preferably alkyl groups.

[0044] The isocyanurate functional group is defined as

[0045] The iminooxadiazindione functional group is defined as

[0046] The biuret functional group is defined as

[0047] The urethane functional group is defined as

[0048] The uredione functional group is defined as

[0049] The following figure shows in bold the linking group of an example of a polyaziridine compound as defined herein. In this example, the linking group connecting two structural units A in structural unit A consists of an array of the following consecutive functional groups: aliphatic hydrocarbon functional group 1 (straight-chain C6H 12 ), isocyanurate 2 (cyclic C3N3O3) functional group, and aliphatic hydrocarbon functional group 3 (straight-chain C6H 12 ).

[0050]

[0051] The following figure shows in bold the linking group of the following example of a polyaziridine compound as defined herein. In this example, the linking group connecting two structural units A consists of an array of the following consecutive functional groups: aliphatic hydrocarbon functional group 1 (straight-chain C6H 12 ), isocyanurate 2 (cyclic C3N3O3), and aliphatic hydrocarbon functional group 3 (straight-chain C6H 12 ).

[0052]

[0053] Any two structural units A in the structural unit A present in the polyaziridine compound as defined herein are preferably connected by a linking group as defined herein. Thus, each structural unit A present in the polyaziridine compound is preferably connected to each other structural unit A using a linking group as defined in the present invention. In the case where the polyaziridine compound has two structural units A, the polyaziridine compound has one such linking group connecting these two structural units. In the case where the polyaziridine compound has three structural units A, the polyaziridine compound has three such linking groups, where each of the three linking groups connects a structural unit A to another structural unit A.

[0054] The following figure shows an example of a polyaziridine compound having three structural units A and three linking groups, where each of the three linking groups connects two structural units A. One linking group consists of an array of the following consecutive functional groups: aliphatic hydrocarbon functional group 1 (straight-chain C6H 12 ) connecting structural units A labeled A1 and A2, isocyanurate 2 (cyclic C3N3O3), and aliphatic hydrocarbon functional group 3 (straight-chain C6H 12 ). For the connection between structural units A labeled A1 and A3, the linking group consists of an array of the following consecutive functional groups: aliphatic hydrocarbon functional group 1 (straight-chain C6H 12) Isocyanurate 2 (cyclic C3N3O3) and aliphatic hydrocarbon functional group 4 (straight-chain C6H 12 ), and for the connection between structural units A labeled as A2 and A3, the linking group consists of an array of the following consecutive functional groups: aliphatic hydrocarbon functional group 3 (straight-chain C6H 12 ), isocyanurate 2 (cyclic C3N3O3) and aliphatic hydrocarbon functional group 4 (straight-chain C6H 12 ).

[0055]

[0056] Preferably, the linking group consists of at least one functional group selected from the group consisting of: aliphatic hydrocarbon functional groups (preferably containing 1 to 8 carbon atoms), cycloaliphatic hydrocarbon functional groups (preferably containing 4 to 10 carbon atoms), aromatic hydrocarbon functional groups (preferably containing 6 to 12 carbon atoms), isocyanurate functional groups, iminooxadiazinedione functional groups, urethane functional groups, urea functional groups, biuret functional groups, and any combination thereof. The linking group preferably contains an isocyanurate functional group, an iminooxadiazinedione functional group, a biuret functional group, a urethane functional group, or a uretdione functional group. More preferably, the linking group contains an isocyanurate functional group or an iminooxadiazinedione functional group. For clarity, the polyaziridine compound can be obtained from the reaction product of one or more suitable compounds B as defined below with a hybrid isocyanurate (such as HDI / IPDI isocyanurate), thereby producing a polyaziridine compound having a linking group consisting of an array of the following consecutive functional groups: straight-chain C6H 12 (i.e., an aliphatic hydrocarbon functional group having 6 carbon atoms), an isocyanurate functional group (cyclic C3N3O3) and

[0057]

[0058] (i.e., a cycloaliphatic hydrocarbon functional group having 9 carbon atoms and an aliphatic hydrocarbon functional group having 1 carbon atom). Even more preferably, the linking group consists of the following functional groups: at least one aliphatic hydrocarbon functional group and / or at least one cycloaliphatic hydrocarbon functional group, and also an isocyanurate functional group or an iminooxadiazinedione functional group.

[0059] On the linking group, one or more substituents may be present as side groups on the linking group, as shown in bold in the following polyaziridine compounds, for example. These side groups are not part of the linking group.

[0060]

[0061] The side groups preferably contain where X, R7, R8, n' and R 10As described below. In one embodiment of the present invention, the polyaziridine compound comprises one or more linking groups, wherein each of these linking groups links two structural units A in the structural unit A, and wherein the linking group consists of: (i) at least two aliphatic hydrocarbon functional groups or at least two alicyclic hydrocarbon functional groups, and (ii) an isocyanurate functional group or an iminooxadiazinedione functional group, and wherein there is a side group on the linking group, and wherein the side group has the following structural formula:

[0062]

[0063] n' is the number of repeating units and is an integer from 1 to 50, preferably from 2 to 30, more preferably from 5 to 20.

[0064] X is O or NH, preferably X is O,

[0065] In each repeating unit, R7 and R8 are independently H or CH3,

[0066] R9 is an aliphatic hydrocarbon group, preferably an aliphatic hydrocarbon group containing 1 to 8 carbon atoms, or preferably an alicyclic hydrocarbon group containing 4 to 10 carbon atoms, and

[0067] R 10 contains at most 20 carbon atoms and is an aliphatic, alicyclic or aromatic hydrocarbon group, or a combination thereof. In a preferred embodiment, R7 and R8 are H. In another more preferred embodiment, one of R7 and R8 is H and the other of R7 and R8 is CH3. R 10 is preferably an aliphatic hydrocarbon group containing 1 to 20 carbon atoms (preferably CH3), an alicyclic hydrocarbon group containing 5 to 20 carbon atoms, or an aromatic hydrocarbon group containing 6 to 20 carbon atoms. The presence of the side group results in a decrease in the viscosity of the polyaziridine compound and thus easier dispersion in an aqueous medium. In this embodiment, the polyaziridine compound preferably contains 2 structural units A. In this embodiment, the linking group preferably consists of an array of the following consecutive functional groups: a first alicyclic hydrocarbon functional group, an isocyanurate functional group or an iminooxadiazinedione functional group, and a second alicyclic hydrocarbon functional group, and R9 is an alicyclic hydrocarbon group, wherein the first alicyclic hydrocarbon functional group and the second alicyclic hydrocarbon functional group are the same as R9, and more preferably, the linking group consists of an array of the following consecutive functional groups: a first aliphatic hydrocarbon functional group, an isocyanurate functional group or an iminooxadiazinedione functional group and a second aliphatic hydrocarbon functional group, and R9 is an aliphatic hydrocarbon functional group, wherein the first aliphatic hydrocarbon functional group and the second aliphatic hydrocarbon functional group are the same as R9.

[0068] In a preferred embodiment of the present invention, the linking group present in the polyaziridine compound as defined herein consists of the following functional groups: (i) at least one aliphatic hydrocarbon functional group and / or at least one cycloaliphatic hydrocarbon functional group; and (ii) optionally at least one aromatic hydrocarbon functional group; and (iii) optionally an isocyanurate functional group or an iminodioxazine dione functional group or a urethane functional group or a uretidione functional group. Preferably, the linking group present in the polyaziridine compound of the present invention consists of the following functional groups: (i) at least one aliphatic hydrocarbon functional group and / or at least one cycloaliphatic hydrocarbon functional group; and (ii) optionally at least one aromatic hydrocarbon functional group; and (iii) optionally an isocyanurate functional group or an iminodioxazine dione functional group. A very suitable way to obtain such polyaziridine compounds is to react a compound B having the following structural formula with a polyisocyanate having aliphatic reactivity:

[0069]

[0070] wherein R1, R2, R3, R4, R' and R” and their preferences are defined as above, and wherein the polyisocyanate has aliphatic reactivity. The term "polyisocyanate having aliphatic reactivity" refers to a compound in which all isocyanate groups are directly bonded to an aliphatic or cycloaliphatic hydrocarbon group, regardless of whether aromatic hydrocarbon groups are also present. The polyisocyanate having aliphatic reactivity can be a mixture of polyisocyanates having aliphatic reactivity. When compared to compounds that are similar but based on polyisocyanates having aromatic reactivity, compounds based on polyisocyanates having aliphatic reactivity have a reduced tendency to yellow over time. The term "polyisocyanate having aromatic reactivity" is intended to mean a compound in which all isocyanate groups are directly bonded to a benzene or naphthalene group, regardless of whether aliphatic or cycloaliphatic groups are also present. Preferred polyisocyanates having aliphatic reactivity are 1,5-pentamethylene diisocyanate PDI, 1,6-hexamethylene diisocyanate HDI, isophorone diisocyanate IPDI, 4,4'-dicyclohexylmethane diisocyanate H12MDI, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, tetramethylxylene diisocyanate TMXDI (all isomers) and higher molecular weight variants such as, for example, their isocyanurates, urethanes or iminooxadiazinediones. In this embodiment, preferably, the linking group consists of an array of the following consecutive functional groups: an aliphatic hydrocarbon functional group, an aromatic hydrocarbon functional group and an aliphatic hydrocarbon functional group (for example, when preparing a polyaziridine compound using TMXDI), or the linking group consists of an array of the following consecutive functional groups: a cycloaliphatic hydrocarbon functional group, an aliphatic hydrocarbon functional group and a cycloaliphatic hydrocarbon functional group (for example, when preparing a polyaziridine compound using H12MDI), or more preferably, the linking group consists of an array of the following consecutive functional groups: an aliphatic hydrocarbon functional group, an isocyanurate functional group or an iminooxadiazinedione functional group and an aliphatic hydrocarbon functional group. Most preferably, in this embodiment, the linking group consists of an array of the following consecutive functional groups: an aliphatic hydrocarbon functional group, an isocyanurate functional group and an aliphatic hydrocarbon functional group (for example, when preparing a polyaziridine compound using the isocyanurate of 1,6-hexamethylene diisocyanate and / or the isocyanurate of 1,5-pentamethylene diisocyanate).

[0071] Preferably, the number of consecutive C atoms and optional O atoms between the N atom of the carbamate group in structural unit A and the next N atom that is either present in the linking chain or is the N atom of a carbamate group of another structural unit A is at most 9, as shown, for example, in the following polyaziridine compound having 2 structural units A.

[0072]

[0073] The polyaziridine compound preferably contains at least 5% by weight, more preferably at least 5.5% by weight, more preferably at least 6% by weight, more preferably at least 9% by weight, more preferably at least 12% by weight and preferably less than 25% by weight, preferably less than 20% by weight of urethane bonds. The aziridine equivalent weight of the polyaziridine compound (the molecular weight of the polyaziridine compound divided by the number of aziridines present in the polyaziridine compound) is preferably at least 200 daltons, more preferably at least 230 daltons and even more preferably at least 260 daltons, and preferably at most 2500 daltons, more preferably at most 1000 daltons and even more preferably at most 500 daltons.

[0074] The polyaziridine compound is preferably obtained by reacting at least a polyisocyanate with compound B having the following structural formula as defined above:

[0075]

[0076] wherein the molar ratio of compound B to the polyisocyanate is from 2 to 6, more preferably from 2 to 4, and most preferably from 2 to 3, and wherein m, R', R'', R1, R2, R3 and R4 are as defined above. The reaction of the polyisocyanate with compound B can be carried out by bringing an equal amount of the polyisocyanate into contact with compound B at a temperature in the range from 0 °C to 110 °C, more suitably from 20 °C to 110 °C, more suitably from 40 °C to 95 °C, even more suitably from 60 °C to 85 °C, in the presence of, for example, a tin catalyst (such as dibutyltin dilaurate) or a bismuth catalyst (such as bismuth neodecanoate). A solvent can be used, such as dimethylformamide DMF, acetone and / or methyl ethyl ketone. The polyisocyanate contains at least 2 isocyanate groups, preferably on average at least 2.5 isocyanate groups, more preferably on average at least 2.8 isocyanate groups. A mixture of polyisocyanates can also be used as starting material. Preferred polyisocyanates are polyisocyanates having aliphatic reactivity. The term "polyisocyanate having aliphatic reactivity" refers to a compound in which all isocyanate groups are directly bonded to an aliphatic or cycloaliphatic hydrocarbon group, regardless of whether aromatic hydrocarbon groups are also present. The polyisocyanate having aliphatic reactivity can be a mixture of polyisocyanates having aliphatic reactivity. Preferred polyisocyanates having aliphatic reactivity are 1,5-pentamethylene diisocyanate PDI, 1,6-hexamethylene diisocyanate HDI, isophorone diisocyanate IPDI, 4,4'-dicyclohexylmethane diisocyanate H12MDI, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, p-tetramethylxylene diisocyanate (p-TMXDI) and its meta-isomer, and higher molecular weight variants, such as their isocyanurates or iminooxadiazinediones or urethanes or uretidiones. More preferred polyisocyanates having aliphatic reactivity are 4,4'-dicyclohexylmethane diisocyanate H12MDI, m-TMXDI, the isocyanurate or iminooxadiazinedione or urethane or uretidione of 1,6-hexamethylene diisocyanate, and the isocyanurate of 1,5-pentamethylene diisocyanate. Suitable HDI-containing iminooxadiazinedione trimers are N3900. Suitable HDI-containing urethanes are XP2860. Suitable HDI-containing uretidiones are N3400. Suitable HDI isocyanurate trimers, for example, can be obtained from Covestro ( N3600), Vencorex (Tolonate TM HDT LV), AsahiKasei (DuranateTM TPA-100), Evonik( HT 2500 / LV) and Tosoh( HXRLV). The methods for preparing compound (B) and derivatives are known in the art. For example, the synthesis of 1-(2-methylaziridin-1-yl)propan-2-ol was described by S. Lesniak, M. Rachwalski, S. Jarzynski, E. Obijalska in Tetrahedron Asymm. 2013, 24, 1336 - 1340. The synthesis of 1-(aziridin-1-yl)propan-2-ol was described by A. Baklien, M. V. Leeding, J. Kolm in Aust. J. Chem. 1968, 21, 1557 - 1570.

[0077] The polyaziridine compounds can also be obtained by reacting at least compound B with a polyisocyanate, a polyol and / or a polyamine as defined above. The polyaziridine compounds can also be obtained by reacting a polyisocyanate as defined above with a polyol and / or a polyamine and reacting the thus obtained compound with compound B. The polyaziridine compounds can also be obtained by reacting compound B with a polyisocyanate and reacting the thus obtained compound with a polyol and / or a polyamine. The polyaziridine compounds can also be obtained by reacting at least compound B with an isocyanate - terminated polyurethane and / or polyurethane - urea. The (isocyanate - terminated) polyurethane (urea) is obtained by reacting at least one polyol and / or polyamine with at least one polyisocyanate. Preferred polyisocyanates are as described above. The polyol is preferably selected from the group consisting of: polyether polyols, polyester polyols, polythioether polyols, polycarbonate polyols, polyacetal polyols, polyvinyl polyols, polysiloxane polyols and any mixtures thereof. More preferably, the polyol is selected from the group consisting of: polyether polyols and any mixtures thereof. Preferred polyether polyols are polytetrahydrofuran, polyethylene oxide, polypropylene oxide or any mixtures thereof. More preferred polyether polyol is poly(propylene glycol). The polyoxyethylene (-O-CH2-CH2) x and polyoxypropylene (-O-CHCH3-CH2-) x or (-O-CH2-CH2-CH2-)x groups and / or polytetrahydrofuran (-O-CH2-CH2-CH2-CH2) xThe amount of the group is preferably at least 6% by weight, more preferably at least 10% by weight, and preferably less than 45% by weight, more preferably less than 40% by weight, and most preferably less than 35% by weight, relative to the polyaziridine compound. x represents the average number of moles of oxyethylene, oxypropylene, or tetrahydrofuran added, and x is preferably an integer from 5 to 20. The polyamine is preferably selected from the group consisting of: polyether polyamines, polyester polyamines, polysulfide polyamines, polycarbonate polyamines, polyacetal polyamines, polyvinyl polyamines, polysiloxane polyamines, and any mixtures thereof. More preferably, the polyamine is selected from the group consisting of: polyether polyamines and any mixtures thereof. Preferred polyether polyamines are D-230, D-400, and D-2000. It is preferred to use a polyol rather than a polyamine. Examples of such polyaziridine compounds are shown below:

[0078]

[0079] Compound B is preferably obtained by reacting at least a non-OH-functional monocyclic epoxide compound with ethyleneimine. The non-OH-functional monocyclic epoxide can be a mixture of different non-OH-functional monocyclic epoxides. Non-limiting examples of non-OH-functional monocyclic epoxides are ethylene oxide, propylene oxide, 2-ethyl ethylene oxide, n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, 4-tert-butylphenyl 2,3-epoxypropyl ether (= tert-butylphenyl glycidyl ether), cresyl glycidyl ether (ortho or para), and glycidyl neodecanoate. The non-OH-functional monocyclic epoxide is preferably selected from the group consisting of: ethylene oxide (CAS No. 75-21-8), propylene oxide (CAS No. 75-56-9), 2-ethyl ethylene oxide (CAS No. 106-88-7), n-butyl glycidyl ether (CAS No. 2426-08-6), 2-ethylhexyl glycidyl ether (CAS No. 2461-15-6), glycidyl neodecanoate (CAS No. 26761-45-5), and any mixtures thereof. More preferably, the non-OH-functional monocyclic epoxide is selected from the group consisting of: propylene oxide (CAS No. 75-56-9), 2-ethyl ethylene oxide (CAS No. 106-88-7), n-butyl glycidyl ether (CAS No. 2426-08-6), 2-ethylhexyl glycidyl ether (CAS No. 2461-15-6), glycidyl neodecanoate (CAS No. 26761-45-5), and any mixtures thereof. Most preferably, the non-OH-functional monocyclic epoxide is selected from the group consisting of: n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, glycidyl neodecanoate, and any mixtures thereof.

[0080] The polyaziridine compound is preferably obtained by a method comprising at least the following steps (i) and (ii):

[0081] (i) reacting aziridine with at least a non - OH functional monocyclic epoxide compound to obtain compound B, and

[0082] (ii) reacting compound B with a polyisocyanate.

[0083] Step (i) can be carried out, for example, by contacting one equivalent of the epoxide compound with one equivalent of aziridine at a temperature in the range from 20 °C to 110 °C, more suitably from 40 °C to 95 °C, even more suitably from 60 °C to 85 °C, at atmospheric pressure. The reaction of the adduct (compound (B)) obtained in step (i) with the polyisocyanate (step (ii)) can be carried out, for example, by contacting an equal amount of the polyisocyanate with the adduct in the presence of, for example, a tin catalyst (such as dibutyltin dilaurate) at a temperature in the range from 20 °C to 110 °C, more suitably from 40 °C to 95 °C, at atmospheric pressure.

[0084] Examples of the preferred polyaziridine compounds present in the cross - linker composition of the present invention are

[0085]

[0086]

[0087] and

[0088]

[0089] In a preferred embodiment of the present invention, the polyaziridine compound present in the aqueous dispersion of the present invention in a dispersed form has

[0090] a. 2 to 6 structural units according to structural formula A

[0091]

[0092] wherein R1, R2, R3, R4, R' and R” and their priorities are as defined above,

[0093] b. one or more linking chains, wherein each of these linking chains links two structural units A in the structural unit A, and wherein the one or more linking chains are preferably as defined above, and

[0094] c. A molecular weight of from 840 to 5000 Daltons, preferably at least 1000 Daltons, and preferably at most 3800 Daltons, more preferably at most 3600 Daltons, more preferably at most 3000 Daltons, more preferably at most 2300 Daltons, even more preferably at most 1600 Daltons.

[0095] It has surprisingly been found that such polyaziridine compounds have reduced genotoxicity compared to the very commonly used trimethylolpropane tris(2-methyl-1-aziridinepropionate). The polyaziridine compounds show only weakly positive induced genotoxicity, or even they do not show genotoxicity, i.e., they show a genotoxicity level comparable to the naturally occurring background. Thus, polyaziridine compounds having reduced genotoxicity compared to trimethylolpropane tris(2-methyl-1-aziridinepropionate) have a more favorable hazard profile than trimethylolpropane tris(2-methyl-1-aziridinepropionate), thereby greatly reducing the safety, health and environmental risks associated with their use, resulting in a reduction or even elimination of the handling and management burden for disposing of polyaziridine compounds having reduced genotoxicity. The polyaziridine compounds preferably contain one or more linking groups, wherein each of the linking groups links two structural units A in the structural unit A, and the linking groups and their preferences are as defined above.

[0096] In this embodiment, the amount of aziridinyl-functional molecules (also referred to as aziridine-functional molecules) having a molecular weight of less than 250 Daltons, more preferably less than 350 Daltons, even more preferably less than 450 Daltons, even more preferably less than 550 Daltons and even more preferably less than 580 Daltons present in the polyaziridine crosslinker composition according to the invention is, relative to the total weight of the polyaziridine crosslinker composition, preferably less than 5% by weight, more preferably less than 4% by weight, more preferably less than 3% by weight, more preferably less than 2% by weight, more preferably less than 1% by weight, more preferably less than 0.5% by weight, more preferably less than 0.1% by weight, most preferably 0% by weight, wherein the molecular weight is determined using LC-MS as described in the following experimental section. Such aziridine-functional molecules can be obtained as by-products during the preparation of the polyaziridine compounds as defined herein.

[0097] The average number of aziridinyl groups per aziridinyl-containing molecule in the composition is preferably at least 1.8, more preferably at least 2, more preferably at least 2.2 and preferably less than 10, more preferably less than 6 and most preferably less than 4. Most preferably, the average number of aziridinyl groups per aziridinyl-containing molecule in the composition is from 2.2 to 3.

[0098] pH of the aqueous dispersion

[0099] The pH of the aqueous dispersion is at least 9. To further extend the storage life of the aqueous dispersion of the present invention, it is beneficial for the pH to be at least 9.5. The pH of the aqueous dispersion is at most 14, preferably at most 13, more preferably at most 12 and even more preferably at most 11.5, because this allows reducing the amount of base present in the aqueous dispersion of the present invention while the storage life of the aqueous dispersion remains long enough. Most preferably, the pH of the aqueous dispersion is in the range of 9.5 to 11.5.

[0100] The aqueous dispersion preferably contains ammonia, secondary amine, tertiary amine, LiOH, NaOH and / or KOH to adjust the pH to the desired value. Preferred amines are ammonia, secondary amine and / or tertiary amine. Examples of such secondary amines are, but not limited to, diisopropylamine, di-sec-butylamine and di-tert-butylamine. More preferred amines are tertiary amines. Examples of such tertiary amines are, but not limited to, N-ethylmorpholine, N-methylpiperidine, N,N-dimethylbutylamine, dimethylisopropylamine, dimethyl-n-propylamine, dimethylethylamine, triethylamine, dimethylbenzylamine, N,N-dimethylethanolamine, 2-(diethylamino)ethanol, N,N-dimethylisopropanolamine, 1-dimethylamino-2-propanol, 3-dimethylamino-1-propanol, 2-(dimethylamino)ethanol, 2-[2-(dimethylamino)ethoxy]ethanol. Preferred tertiary amines are N-ethylmorpholine, N-methylpiperidine, N,N-dimethylbutylamine, dimethylisopropylamine, dimethyl-n-propylamine, dimethylethylamine, triethylamine and / or dimethylbenzylamine. Most preferred is triethylamine.

[0101] The amount of water in the aqueous dispersion is, based on the total weight of the aqueous dispersion, preferably at least 15% by weight, more preferably at least 20% by weight, more preferably at least 30% by weight, even more preferably at least 40% by weight. The amount of water in the aqueous dispersion is, based on the total weight of the aqueous dispersion, preferably at most 95% by weight, more preferably at most 90% by weight, more preferably at most 80% by weight, more preferably at most 70% by weight, more preferably at most 65% by weight, more preferably at most 60% by weight, more preferably at most 55% by weight, even more preferably at most 48% by weight.

[0102] The polyaziridine compound as defined herein is present in the aqueous dispersion in an amount of, based on the total weight of the aqueous dispersion, preferably at least 5% by weight, more preferably at least 10% by weight, more preferably at least 15% by weight, more preferably at least 20% by weight, even more preferably at least 25% by weight, even more preferably at least 30% by weight, even more preferably at least 35% by weight. The polyaziridine compound as defined herein is present in the aqueous dispersion in an amount of, based on the total weight of the aqueous dispersion, preferably at most 70% by weight, preferably at most 65% by weight, more preferably at most 60% by weight, even more preferably at most 55% by weight.

[0103] Preferably at least 70% by weight, more preferably at least 85% by weight and most preferably at least 95% by weight of the polyaziridine compound as defined herein is present in the polyaziridine crosslinker composition in a dispersed form. Accordingly, the polyaziridine crosslinker composition of the present invention comprises particles containing the polyaziridine compound as defined herein. The particles preferably have an average hydrodynamic diameter based on scattering intensity of from 30 nanometers to 650 nanometers, preferably from 50 nm to 500 nanometers, more preferably from 70 nm to 350 nanometers, and even more preferably from 120 nm to 275 nm. The average hydrodynamic diameter of the particles based on scattering intensity can be controlled via a variety of means. For example, during the preparation of the aqueous dispersion of the present invention, the average hydrodynamic diameter of the particles based on scattering intensity can be controlled by using different types of dispersants and / or different amounts of dispersants and / or by applying different shear stresses and / or by applying different temperatures. For example, the average hydrodynamic diameter of the particles based on scattering intensity is inversely proportional to the amount of dispersant used in the preparation of the aqueous dispersion of the present invention; for example, the average hydrodynamic diameter of the particles based on scattering intensity decreases by increasing the amount of dispersant. For example, the average hydrodynamic diameter of the particles based on scattering intensity is inversely proportional to the shear stress applied during the preparation of the aqueous dispersion of the present invention; for example, the average hydrodynamic diameter of the particles based on scattering intensity decreases by increasing the shear stress. Exemplary dispersants include, but are not limited to, ATLAS supplied by Croda TM G-5000, ATLAS TM G-5002L-LQ, Maxemul TM 7101.

[0104] The solids content of the aqueous dispersion is preferably at least 5% by weight, more preferably at least 10% by weight, even more preferably at least 20% by weight, even more preferably at least 30% by weight, and even more preferably at least 35% by weight. The solids content of the aqueous dispersion is preferably at most 70% by weight, preferably at most 65% by weight, and more preferably at most 55% by weight. The solids content of the aqueous dispersion is most preferably in the range of from 35% by weight to 55% by weight.

[0105] The polyaziridine compounds as defined above are generally obtained in the form of a composition, in which, in addition to the polyaziridine compound, there may also be present residual starting materials, by-products and / or solvents used in the preparation of the polyaziridine compound. The composition may contain only one polyaziridine compound as defined above, but may also contain more than one polyaziridine compound as defined above. For example, when a mixture of polyisocyanates is used as the starting material, a mixture of polyaziridine compounds is obtained. The aqueous dispersion of the present invention can be obtained by dispersing the polyaziridine compound in water and adjusting the pH of the aqueous dispersion to a desired value; or by dispersing the polyaziridine compound in a mixture of water and at least one base, the mixture having a pH such as to obtain an aqueous dispersion having the desired pH value; or by adding a mixture of water and base to the polyaziridine compound. Techniques well known in the art can be used to disperse the polyaziridine in water or in a mixture of water and at least one base. Solvents and / or high shear can be utilized to assist in the dispersion of the polyaziridine compound.

[0106] The aqueous dispersion may also contain an organic solvent in an amount of up to 35% by weight, preferably up to 30% by weight, such as up to 25% by weight, such as up to 20% by weight, such as up to 12% by weight, such as up to 10% by weight, such as up to 8% by weight, such as up to 5% by weight, such as up to 4% by weight, such as up to 3% by weight, such as up to 2% by weight, such as up to 1% by weight, such as up to 0.5% by weight, such as up to 0.2% by weight, such as up to 0.1% by weight, based on the total weight of the aqueous dispersion. The organic solvent can optionally be added before, during and / or after the polyaziridine synthesis. The organic solvent can be used to assist in dispersing the polyaziridine compound in water. If desired, the organic solvent can subsequently be removed from the crosslinking agent composition by reduced pressure and / or elevated temperature. Typical organic solvents are diols, ethers, alcohols, cyclic carbonates, pyrrolidones, dimethylformamide, dimethyl sulfoxide, N-formylmorpholine, dimethylacetamide, and ketones. Preferred solvents are diols, ethers, alcohols, cyclic carbonates and ketones.

[0107] Preferably, the dispersion of the polyaziridine compound is carried out in the presence of a dispersant. Accordingly, the aqueous dispersion of the present invention preferably contains a dispersant. In the context of the present invention, a dispersant is a substance that promotes the formation of a dispersion and colloidal stabilization. In the present invention, the dispersant is preferably a substance that is non-covalently attached to the polyaziridine compound, and / or the dispersant is a separate molecular component having surface activity. Examples of substances non-covalently attached to the polyaziridine compound are amphiphilic compounds containing urea and / or urethane, such as HEUR thickeners.

[0108] More preferably, the dispersant is at least one separate surface-active molecular component. Preferred separate surface-active molecular components are:

[0109] (i) A polyaziridine compound as defined above, the polyaziridine compound containing functional groups such as sulfonate, sulfate, phosphate and / or phosphonate functional groups, preferably sulfonate and / or phosphonate groups, more preferably sulfonate groups, and / or

[0110] (ii) A polymer which preferably has a number-average molecular weight of at least 2000 daltons, more preferably at least 2500 daltons, more preferably at least 3000 daltons, more preferably at least 3500 daltons, more preferably at least 4000 daltons, and preferably at most 1000000 daltons, more preferably at most 100000, at most 10000 daltons as measured by MALDI-ToF-MS as described below.

[0111] A more preferred separate surface-active molecular component is a polymer having a number-average molecular weight of at least 2000 daltons, more preferably at least 2500 daltons, more preferably at least 3000 daltons, more preferably at least 3500 daltons, more preferably at least 4000 daltons, and preferably at most 1000000 daltons, more preferably at most 100000, even more preferably at most 10000 daltons as measured by MALDI-ToF-MS as described below. Preferred polymers are polyethers, more preferably polyether copolymers, even more preferably polyether block copolymers, even more preferably poly(alkylene oxide) block copolymers, even more preferably poly(ethylene oxide)-co-poly(propylene oxide) block copolymers. Non-limiting examples of preferred separate surface-active molecular dispersants are Atlas TM G-5000 available from Croda, Maxemul TM 7101 available from Croda and / or P84 available from BASF. The amount of the separate surface-active molecular component is generally in the range of 0.1% to 20% by weight, preferably at least 0.5% by weight, more preferably at least 1% by weight, even more preferably at least 2% by weight, even more preferably at least 3% by weight, based on the total weight of the aqueous dispersion.

[0112] A polyaziridine compound containing a functional group (such as a sulfonate group, a sulfate group, a phosphate group, and / or a phosphonate group), preferably a sulfonate group, as defined under (i), is preferably obtained by reacting a partial isocyanate group of a polyisocyanate used for preparing the polyaziridine compound with a hydroxyl or amine-functional ionic constituent unit (preferably neutralized with an inorganic base). Examples of the hydroxyl or amine-functional ionic constituent unit include 2-(cyclohexylamino)ethanesulfonic acid, 3-(cyclohexylamino)propanesulfonic acid, methyltaurine, taurine, DS-3404. Preferably, a sulfonate salt is used as the hydroxyl or amine-functional ionic constituent unit.

[0113] The crosslinking efficiency of the crosslinking agent can be evaluated by assessing the chemical resistance defined and determined as described below.

[0114] The storage stability of the aqueous dispersion according to the present invention can be evaluated by the following method: storing the aqueous dispersion, particularly at an elevated temperature (such as 50 °C), and evaluating the change in viscosity of the stored aqueous dispersion as defined and measured below, and / or evaluating the change in chemical resistance, particularly ethanol resistance, of the stored aqueous dispersion as defined and measured below.

[0115] The storage stability of the aqueous dispersion of the present invention at 50 °C is preferably at least 2 weeks, more preferably at least 3 weeks, and even more preferably at least 4 weeks. Storage stability at 50 °C for at least x weeks means that after the dispersion has been stored at 50 °C for x weeks, (i) the final viscosity of the dispersion is at most 50 times as high as the starting viscosity, preferably at most 45 times as high as the starting viscosity, more preferably at most 40 times as high as the starting viscosity, more preferably at most 35 times as high as the starting viscosity, more preferably at most 30 times as high as the starting viscosity, more preferably at most 25 times as high as the starting viscosity, more preferably at most 20 times as high as the starting viscosity, more preferably at most 15 times as high as the starting viscosity, more preferably at most 10 times as high as the starting viscosity, and most preferably at most 5 times as high as the starting viscosity, and / or (ii) the chemical resistance of the aqueous dispersion as defined and measured below is reduced by at most 3 points, preferably at most 2 points, and even more preferably at most 1 point. Preferably, storage stability at 50 °C for at least x weeks means that after the dispersion has been stored at 50 °C for x weeks, (i) the final viscosity of the dispersion is at most 50 times as high as the starting viscosity, preferably at most 45 times as high as the starting viscosity, more preferably at most 40 times as high as the starting viscosity, more preferably at most 35 times as high as the starting viscosity, more preferably at most 30 times as high as the starting viscosity, more preferably at most 25 times as high as the starting viscosity, more preferably at most 20 times as high as the starting viscosity, more preferably at most 15 times as high as the starting viscosity, more preferably at most 10 times as high as the starting viscosity, and most preferably at most 5 times as high as the starting viscosity, and (ii) the chemical resistance of the aqueous dispersion as defined and measured below is reduced by at most 3 points, preferably at most 2 points, and even more preferably at most 1 point. The 'starting viscosity' of the aqueous dispersion means the viscosity of the aqueous dispersion determined at the time of its preparation and immediately before the aqueous dispersion is stored at 50 °C (as defined and measured below). The 'end viscosity' of the aqueous dispersion means the viscosity of the aqueous dispersion determined after the aqueous dispersion has been stored at 50 °C for x weeks (as defined and measured below).

[0116] The present invention also relates to a method for preparing a polyaziridine crosslinking agent composition according to the present invention, wherein the method comprises dispersing a polyaziridine compound as defined herein into water to obtain an aqueous dispersion; and adjusting the pH of the aqueous dispersion to a desired value, or preferably wherein the method comprises dispersing a polyaziridine compound as defined herein into a mixture of water and at least one base, the mixture having a pH such as to obtain an aqueous dispersion having a desired pH value.

[0117] In a preferred embodiment of the present invention, the dispersant is a separate surface-active polymer (ii) having a number-average molecular weight of at least 2000 daltons. In this preferred embodiment, the method for preparing a polyaziridine crosslinking agent composition according to the present invention preferably comprises

[0118] A) Optionally but preferably, mix the polyaziridine compound as defined above in an organic solvent.

[0119] B) Mix the polyaziridine compound as defined above or the solution obtained in step A) with the dispersant as described above to obtain a composition comprising the polyaziridine compound and the dispersant.

[0120] C) Mix water and a base or mix an alkaline aqueous medium into the composition comprising the polyaziridine compound and the dispersant to obtain a dispersion.

[0121] D) Optionally but preferably, evaporate the organic solvent from the dispersion to obtain a further dispersion, and optionally mix additional water or an alkaline aqueous medium into the further dispersion to obtain the aqueous dispersion of the present invention.

[0122] Step C) is preferably carried out using a high-shear dispersion device.

[0123] The present invention also relates to the use of the polyaziridine crosslinking agent composition according to the present invention for crosslinking a carboxylic acid-functional polymer dissolved and / or dispersed, preferably dispersed, in water, wherein the amounts of the aziridine groups and the carboxylic acid groups are selected such that the stoichiometric amount (SA) of the aziridine groups based on the carboxylic acid groups is from 0.1 to 2.0, more preferably from 0.2 to 1.5, even more preferably from 0.25 to 0.95, and most preferably from 0.3 to 0.8. The carboxylic acid-functional polymer contains carboxylic acid groups and / or carboxylate groups, and the carboxylic acid groups and / or carboxylate groups preferably do not contain covalent bonds that prevent the chemical reaction of these groups with the aziridine moieties present in the polyaziridine compound. As used herein, the amount of carboxylic acid groups present in the carboxylic acid-functional polymer is the total amount of deprotonated and protonated carboxylic acid groups present in the polymer to be crosslinked (i.e., in the carboxylic acid-functional polymer). Thus, the amount of carboxylic acid groups present in the carboxylic acid-functional polymer is the total amount of carboxylate groups and carboxylic acid groups present in the carboxylic acid-functional polymer. The polymer to be crosslinked preferably contains at least partially base-neutralized carboxylate groups. Preferably, at least a portion of the base in the base is a volatile base. Preferably, at least a portion of the carboxylic acid groups present in the carboxylic acid-functional polymer to be crosslinked undergo deprotonation to obtain carboxylate groups. Deprotonation is achieved by neutralizing the carboxylic acid-functional polymer with a base. Examples of suitable bases are ammonia, secondary amines, tertiary amines, LiOH, NaOH, and / or KOH. Examples of secondary amines and tertiary amines are as described above. The preferred base is a tertiary amine. Preferred tertiary amines are as described above. Most preferably, it is triethylamine.

[0124] To avoid undesired premature crosslinking reactions between the crosslinker and the polymer to be crosslinked during storage of the polyaziridine crosslinker composition, it is known to those skilled in the art that the polyaziridine crosslinker composition is preferably not mixed with the polymer to be crosslinked during storage of the polyaziridine crosslinker composition; the reason being that the crosslinking reaction between the crosslinker and the polymer to be crosslinked may start immediately after mixing the crosslinker and the polymer to be crosslinked. Therefore, it is preferred that the polyaziridine crosslinker composition of the present invention does not contain the polymer to be crosslinked. Accordingly, the present invention also relates to a two-component coating system comprising a first component and a second component, each of the first component and the second component being separate and different from one another, and wherein the first component comprises a carboxylic acid functional polymer dissolved and / or dispersed (preferably dispersed) in an aqueous medium, and the second component comprises the polyaziridine crosslinker composition of the present invention, wherein the first component and the second component are stored separately because the crosslinking reaction between the crosslinker and the polymer to be crosslinked may start immediately after mixing the aqueous composition of the crosslinker and the polymer to be crosslinked. As used herein, a coating composition refers to a composition comprising a polymer to be crosslinked, the polymer being dissolved and / or dispersed (preferably dispersed) in water; and further comprising the polyaziridine crosslinker composition of the present invention.

[0125] The present invention also relates to a coating composition obtained by mixing the first component and the second component of the two-component system immediately prior to application of the coating composition, wherein the coating composition contains an amount of aziridinyl group Q and carboxylic acid groups such that the stoichiometric amount (SA) of aziridinyl group Q on the carboxylic acid groups is preferably from 0.1 to 2.0, more preferably from 0.2 to 1.5, even more preferably from 0.25 to 0.95, and most preferably from 0.3 to 0.8.

[0126] The present invention also relates to a substrate having a coating obtained by: (i) applying the coating composition as described above to a substrate, and (ii) drying the coating composition by evaporating the volatile matter. Drying of the coating composition is preferably carried out at a temperature below 160 °C, preferably at a temperature below 90 °C, more preferably at a temperature below 50 °C and most preferably at ambient temperature. The coating composition according to the present invention can be applied to any kind of substrate, such as wood, leather, concrete, textiles, plastics, vinyl floors, glass, metal, ceramics, paper, wood-plastic composites, glass fiber reinforcements. The thickness of the dry coating on the substrate is preferably from 1 micron to 200 microns, more preferably from 5 microns to 150 microns, and most preferably from 15 microns to 90 microns. In the case where the coating composition is an ink composition, the thickness of the dry ink is preferably from 0.005 microns to 35 microns, more preferably from 0.05 microns to 25 microns, and most preferably from 4 microns to 15 microns.

[0127] Non-limiting examples of crosslinkable carboxylic acid functional polymers are vinyl polymers (such as styrene-acrylic acid), (meth)acrylic acid copolymers, vinyl acetate (co)polymers (such as vinyl acetate-vinyl chloride-ethylene polymers), polyurethanes, condensation polymers (such as polyesters, polyamides, polycarbonates), and hybrids of any of these polymers, wherein at least one of the two polymers has a carboxylic acid functional group.

[0128] The carboxylic acid functional polymer is preferably selected from the group consisting of: polyesters, polycarbonates, polyamides, vinyl polymers, polyacrylates, polymethacrylates, poly(acrylate-copoly-methacrylate), polyurethanes, poly(urethane-copoly-acrylate), poly(urethane-copoly-methacrylate), poly(urethane-copoly-acrylate-copoly-methacrylate), polyureas, and mixtures thereof. In one embodiment of the present invention, the preferred crosslinkable carboxylic acid functional polymers are selected from the group consisting of: vinyl polymers, polyacrylates, polymethacrylates, poly(acrylate-copoly-methacrylate), and mixtures thereof. Preferably, the vinyl polymer means a polymer containing reacted residues of styrene with acrylate and / or methacrylate. In another embodiment, the carboxylic acid functional polymer is selected from the group consisting of: polyurethanes, poly(urethane-copoly-acrylate), poly(urethane-copoly-methacrylate), poly(urethane-copoly-acrylate-copoly-methacrylate), polyureas, and mixtures thereof.

[0129] The acid value of the carboxylic acid functional polymer is preferably from 2 mg KOH / gram of carboxylic acid functional polymer to 135 mg KOH / gram of carboxylic acid functional polymer, more preferably from 3 mg KOH / g of carboxylic acid functional polymer to 70 mg KOH / g of carboxylic acid functional polymer, even more preferably from 10 mg KOH / g of carboxylic acid functional polymer to 50 mg KOH / g of carboxylic acid functional polymer, and even more preferably from 15 mg KOH / g of carboxylic acid functional polymer to 50 mg KOH / g of carboxylic acid functional polymer. In cases where a high crosslink density is desired, the acid value of the carboxylic acid functional polymer is preferably from 50 mg KOH / g of carboxylic acid functional polymer to 200 mg KOH / g of carboxylic acid functional polymer. As used herein, the acid value of the carboxylic acid functional polymer is calculated according to the formula AV = ((total molar amount of carboxylic acid components contained in the carboxylic acid functional polymer / grams of total components contained in the carboxylic acid functional polymer)) * 56.1 * 1000), and is expressed as mg KOH / gram of carboxylic acid functional polymer. Thus, the acid value of the carboxylic acid functional polymer can be controlled by the molar amount of the carboxylic acid component used to prepare the carboxylic acid functional polymer. If the acid value cannot be calculated appropriately, the acid value is determined by ASTM D1639 - 90(1996)e1.

[0130] The number average molecular weight M of the carboxylic acid functional polymer n The ratio to the acid value of the carboxylic acid functional polymer is preferably at least 150, more preferably at least 300, even more preferably at least 600, even more preferably at least 1000, even more preferably at least 5000, and most preferably at least 15000. As used herein, the number average molecular weight M of the carboxylic acid functional polymer n is determined by size exclusion chromatography using NMP - MEK.

[0131] The present invention is further defined by a set of exemplary embodiments set forth below. Unless otherwise stated herein or if clearly technically infeasible to those skilled in the art, any one of the embodiments, aspects, and preferred features or scopes disclosed in this application can be combined in any combination.

[0132] [1] A polyaziridine cross - linker composition, wherein the composition is an aqueous dispersion, the pH range of the aqueous dispersion is from 8 to 14 and contains a polyaziridine compound in dispersed form, wherein

[0133] The polyaziridine compound has:

[0134] a. 2 to 6 of the following structural units A:

[0135]

[0136] wherein

[0137] R1, R2, R3, and R4 are H,

[0138] m is 1,

[0139] R' and R” are according to (1) or (2):

[0140] (1) R' = H or an aliphatic hydrocarbon group having 1 to 14 carbon atoms; and

[0141] R” = an alkyl group having 1 to 4 carbon atoms, CH2-O-(C=O)-R”', or CH2-O-R””, where R”' is an alkyl group having 3 to 12 carbon atoms and R”” is an alkyl group having 1 to 14 carbon atoms,

[0142] (2) R' and R” together form a saturated alicyclic hydrocarbon group having 5 to 8 carbon atoms,

[0143] t is 0,

[0144] R5 is H or CH3,

[0145] X is O and Y is NH;

[0146] b. One or more linking chains, where each of these linking chains links two structural units A in the structural unit A; and

[0147] c. A molecular weight in the range of 500 daltons to 10,000 daltons.

[0148] [2] The polyaziridine crosslinking agent composition according to Embodiment 1, wherein the linking chain is composed of 4 to 300 atoms, more preferably 5 to 250 atoms, and most preferably 6 to 100 atoms, and the linking chain is a set of covalently linked atoms, and the set of atoms is composed of i) carbon atoms, ii) carbon and nitrogen atoms, or iii) carbon, oxygen, and nitrogen atoms.

[0149] [3] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to [2], wherein the polyaziridine compound contains 2 or 3 structural units A.

[0150] [4] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to [3], wherein R' is H and R” = an alkyl group having 1 to 4 carbon atoms, CH2-O-(C=O)-R”', CH2-O-R””, where R”' is an alkyl group having 3 to 12 carbon atoms and R”” is an alkyl group having 1 to 14 carbon atoms.

[0151] [5] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to [4], wherein the polyaziridine compound contains one or more linking groups, and each of these linking groups connects two structural units A in the structural unit A, and the linking group is composed of at least one functional group selected from the group consisting of: aliphatic hydrocarbon functional groups (preferably containing 1 to 8 carbon atoms), alicyclic hydrocarbon functional groups (preferably containing 4 to 10 carbon atoms), aromatic hydrocarbon functional groups (preferably containing 6 to 12 carbon atoms), isocyanurate functional groups, iminodioxazine dione functional groups, ether functional groups, ester functional groups, amide functional groups, carbonate functional groups, urethane functional groups, urea functional groups, biuret functional groups, urethane functional groups, allophanate functional groups, uretidione functional groups, and any combination thereof.

[0152] [6] The polyaziridine crosslinking agent composition according to Embodiment [5], wherein the linking group is composed of at least one aliphatic hydrocarbon functional group and / or at least one alicyclic hydrocarbon functional group and optionally at least one aromatic hydrocarbon functional group and optionally an isocyanurate functional group or an iminodioxazine dione functional group.

[0153] [7] The polyaziridine crosslinking agent composition according to Embodiment [5], wherein the linking group is composed of at least one aliphatic hydrocarbon functional group and / or at least one alicyclic hydrocarbon functional group and an isocyanurate functional group or an iminodioxazine dione functional group.

[0154] [8] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to [4], wherein the polyaziridine compound contains one or more linking groups, and each of these linking groups connects two structural units A in the structural unit A, and the linking group is composed of (i) at least two aliphatic hydrocarbon functional groups and (ii) an isocyanurate functional group or an iminodioxazine dione functional group, and side groups are present on the linking group, and the side group has the following structural formula:

[0155]

[0156] n' is the number of repeating units and is an integer from 1 to 50, preferably from 2 to 30, more preferably from 5 to 20.

[0157] X is O or NH, preferably X is O,

[0158] In each repeating unit, R7 and R8 are independently H or CH3,

[0159] R9 is an aliphatic hydrocarbon group, preferably containing 1 to 8 carbon atoms, and

[0160] R 10Preferably an aliphatic hydrocarbon group having 1 to 20 carbon atoms (preferably CH3), an alicyclic hydrocarbon group having 5 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0161] [9] A polyaziridine crosslinking agent composition, wherein the composition is an aqueous dispersion, the pH range of the aqueous dispersion is from 9 to 14 and contains a polyaziridine compound in dispersed form, wherein the polyaziridine compound has 2 to 6 structural units A as defined in Embodiment [1], wherein R1, R2, R3, R4, R', R", m, t, X and Y are as defined in any one of Embodiments [1] to [7], wherein the polyaziridine compound has a molecular weight of 500 daltons to 10,000 daltons, and wherein the polyaziridine compound further contains one or more linking groups, wherein each of these linking groups connects two structural units A in the structural unit A, and wherein the linking group is composed of at least one functional group selected from the group consisting of: aliphatic hydrocarbon functional groups (preferably containing 1 to 8 carbon atoms), alicyclic hydrocarbon functional groups (preferably containing 4 to 10 carbon atoms), aromatic hydrocarbon functional groups (preferably containing 6 to 12 carbon atoms), isocyanurate functional groups, iminodioxazine dione functional groups, ether functional groups, ester functional groups, amide functional groups, carbonate functional groups, carbamate functional groups, urea functional groups, biuret functional groups, urethane functional groups, allophanate functional groups, and any combination thereof.

[0162]

[10] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to [9], wherein the structural unit A is according to the following structural formula D:

[0163]

[0164]

[11] The polyaziridine crosslinking agent composition according to Embodiment

[10] , wherein the number of consecutive C atoms and optionally O atoms between the N atom of the carbamate group in the structural unit D and the next N atom which is the N atom of the carbamate group in the linking chain or another structural unit D is at most 9.

[0165]

[12] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to

[11] , wherein the polyaziridine compound is obtained by reacting at least a polyisocyanate with a compound B having the following structural formula:

[0166]

[0167] wherein the molar ratio of compound B to the polyisocyanate is from 2 to 6, more preferably from 2 to 4, most preferably from 2 to 3, and wherein m, R', R'', R1, R2, R3, and R4 are as defined in the foregoing embodiments.

[0168]

[13] The polyaziridine crosslinking agent composition according to embodiment

[12] , wherein the polyisocyanate is a polyisocyanate having aliphatic reactivity.

[0169]

[14] The polyaziridine crosslinking agent composition according to embodiment

[12] or

[13] , wherein compound B is obtained by reacting at least a non-OH-functional monocyclic epoxide compound with an aziridine having the following structural formula:

[0170]

[0171] wherein R1, R2, R3, and R4 are as defined in the foregoing embodiments.

[0172]

[15] The polyaziridine crosslinking agent composition according to embodiment

[14] , wherein the non-OH-functional monocyclic epoxide compound is selected from the group consisting of ethylene oxide, propylene oxide, 2-ethyloxirane, n-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, glycidyl neodecanoate, and any mixture thereof.

[0173]

[16] The polyaziridine crosslinking agent composition according to any one of embodiments

[12] to

[15] , wherein the polyaziridine compound is a reaction product of at least compound (B), a polyisocyanate, and an alkoxypoly(propylene glycol) and / or poly(propylene glycol).

[0174]

[17] The polyaziridine crosslinking agent composition according to any one of embodiments [1] to

[16] , wherein the molecular weight of the polyaziridine compound is from 600 daltons to 5000 daltons, more preferably the molecular weight of the polyaziridine compound is at least 800 daltons, even more preferably at least 840 daltons, even more preferably at least 1000 daltons, and preferably at most 3800 daltons, more preferably at most 3600 daltons, more preferably at most 3000 daltons, more preferably at most 1600 daltons, even more preferably at most 2300 daltons, even more preferably at most 1400 daltons.

[0175]

[18] The polyaziridine crosslinker composition according to any one of embodiments [1] to

[17] , wherein the aqueous dispersion comprises, based on the total weight of the aqueous dispersion, an amount less than 5% by weight, more preferably less than 4% by weight, more preferably less than 3% by weight, more preferably less than 2% by weight, more preferably less than 1% by weight, more preferably less than 0.5% by weight, more preferably less than 0.1% by weight and most preferably 0% by weight of aziridine-functional molecules having a molecular weight less than 250 daltons, more preferably less than 350 daltons, even more preferably less than 450 daltons, even more preferably less than 550 daltons and even more preferably less than 580 daltons, wherein the molecular weight is determined using LC-MS as described in the specification.

[0176]

[19] The polyaziridine crosslinker composition according to any one of embodiments [1] to

[18] , wherein the pH of the aqueous dispersion is at least 9.5.

[0177]

[20] The polyaziridine crosslinker composition according to any one of embodiments [1] to

[19] , wherein the pH of the aqueous dispersion is at most 14, more preferably at most 13, even more preferably at most 12, even more preferably at most 11.5.

[0178]

[21] The polyaziridine crosslinker composition according to any one of embodiments [1] to

[20] , wherein the pH of the aqueous dispersion is in the range of 9.5 to 11.5.

[0179]

[22] The polyaziridine crosslinker composition according to any one of embodiments [1] to

[21] , wherein the aqueous dispersion comprises ammonia, secondary amine, tertiary amine, LiOH, NaOH and / or KOH to adjust the pH to a desired value, preferably the aqueous dispersion comprises a tertiary amine selected from: N-ethylmorpholine, N-methylpiperidine, N,N-dimethylbutylamine, dimethylisopropylamine, dimethylpropylamine, dimethylethylamine, triethylamine and / or dimethylbenzylamine, and most preferably comprises triethylamine to adjust the pH to a desired value.

[0180]

[23] The polyaziridine crosslinker composition according to any one of embodiments [1] to

[22] , wherein the amount of water in the aqueous dispersion is at least 15% by weight, preferably at least 20% by weight, more preferably at least 30% by weight, even more preferably at least 40% by weight based on the total weight of the aqueous dispersion.

[0181]

[24] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to

[23] , wherein the amount of water in the aqueous dispersion is at most 95% by weight, preferably at most 90% by weight, more preferably at most 85% by weight, more preferably at most 80% by weight, even more preferably at most 70% by weight, even more preferably at most 60% by weight, based on the total weight of the aqueous dispersion.

[0182]

[25] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to

[24] , wherein the amount of the polyaziridine compound in the aqueous dispersion is at least 5% by weight, preferably at least 10% by weight, more preferably at least 15% by weight, more preferably at least 20% by weight, even more preferably at least 25% by weight, even more preferably at least 30% by weight, even more preferably at least 35% by weight, based on the total weight of the aqueous dispersion.

[0183]

[26] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to

[25] , wherein the amount of the polyaziridine compound in the aqueous dispersion is at most 70% by weight, preferably at most 65% by weight, more preferably at most 60% by weight, even more preferably at most 55% by weight, based on the total weight of the aqueous dispersion.

[0184]

[27] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to

[26] , wherein the aqueous dispersion further contains an organic solvent in an amount of at most 35% by weight, preferably at most 30% by weight, such as at most 25% by weight, such as at most 20% by weight, such as at most 12% by weight, such as at most 10% by weight, such as at most 8% by weight, such as at most 5% by weight, such as at most 4% by weight, such as at most 3% by weight, such as at most 2% by weight, such as at most 1% by weight, such as at most 0.5% by weight, such as at most 0.2% by weight, such as at most 0.1% by weight, based on the total weight of the aqueous dispersion.

[0185]

[28] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to

[27] , wherein the solid content of the aqueous dispersion is at least 5% by weight, preferably at least 10% by weight, even more preferably at least 20% by weight, even more preferably at least 30% by weight, even more preferably at least 35% by weight, and at most 70% by weight, more preferably at most 65% by weight and even more preferably at most 55% by weight.

[0186]

[29] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to

[28] , wherein the particles have an average hydrodynamic diameter based on scattering intensity of 30 nanometers to 650 nanometers, preferably 50 nm to 500 nm, more preferably 70 nm to 350 nm, even more preferably 120 nm to 275 nm.

[0187]

[30] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to

[29] , wherein the aqueous dispersion contains a dispersant.

[0188]

[31] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to

[30] , wherein the aqueous dispersion contains a single surfactant molecule component as a dispersant, and the amount of the single surfactant molecule component is in the range of 0.1% by weight to 20% by weight, preferably at least 0.5% by weight, more preferably at least 1% by weight, even more preferably at least 2% by weight, even more preferably at least 3% by weight, based on the total weight of the aqueous dispersion.

[0189]

[32] The polyaziridine crosslinking agent composition according to Embodiment

[32] , wherein the dispersant is a polymer having a number average molecular weight of at least 2000 daltons, more preferably at least 2500 daltons, more preferably at least 3000 daltons, more preferably at least 3500 daltons, more preferably at least 4000 daltons, and preferably at most 1000000 daltons, more preferably at most 100000 daltons, at most 10000 daltons.

[0190]

[33] The polyaziridine crosslinking agent composition according to any one of Embodiments

[30] to

[32] , wherein the dispersant is a polyether, more preferably a polyether copolymer, even more preferably a polyether block copolymer, even more preferably a poly(alkylene oxide) block copolymer, even more preferably a poly(ethylene oxide)-co-poly(propylene oxide) block copolymer.

[0191]

[34] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to

[33] , wherein the aqueous dispersion has a storage stability of at least 2 weeks, more preferably at least 3 weeks, even more preferably at least 4 weeks at 50 °C.

[0192]

[35] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to

[34] , wherein the polyaziridine crosslinking agent composition is used to crosslink a carboxylic acid functional polymer dissolved and / or dispersed, preferably dispersed, in an aqueous medium, and the carboxylic acid functional polymer contains carboxylic acid groups and / or carboxylate groups.

[0193]

[36] The polyaziridine crosslinking agent composition according to any one of Embodiments [1] to

[35] , wherein the polyaziridine crosslinking agent composition does not contain a polymer to be crosslinked with the polyaziridine crosslinking agent composition.

[0194]

[37] A method for preparing a polyaziridine crosslinking agent composition according to any one of embodiments [1] to

[36] , wherein the method comprises dispersing a polyaziridine compound as defined in any one of the foregoing embodiments in water to obtain an aqueous dispersion and adjusting the pH of the aqueous dispersion to a desired value, or wherein the method comprises dispersing a polyaziridine compound as defined in any one of the foregoing embodiments in a mixture of water and at least one base, the mixture having a pH such that an aqueous dispersion having a desired pH value is obtained.

[0195]

[38] The method according to embodiment

[37] , wherein the method comprises mixing an alkaline aqueous medium into a polyaziridine compound as defined in any one of the foregoing embodiments, wherein the pH of the alkaline aqueous medium is selected to obtain an aqueous dispersion having a desired pH value.

[0196]

[39] The method according to embodiment

[37] , wherein the method comprises

[0197] A) Optionally but preferably mixing a polyaziridine compound as defined in any one of the foregoing embodiments in an organic solvent,

[0198] B) Mixing a polyaziridine compound as defined in any one of the foregoing embodiments or the solution obtained in step A) with a dispersant to obtain a composition comprising a polyaziridine compound and a dispersant,

[0199] C) Mixing water and a base or mixing an alkaline aqueous medium into the composition comprising a polyaziridine compound and a dispersant to obtain a dispersion

[0200] D) Optionally, but preferably, evaporating the organic solvent from the dispersion to obtain a further dispersion, and optionally mixing additional water or an alkaline aqueous medium into the further dispersion to obtain an aqueous dispersion according to any one of embodiments [1] to

[36] .

[0201]

[40] Use of a polyaziridine crosslinking agent composition according to any one of embodiments [1] to

[36] or obtained by a method according to any one of embodiments

[37] to

[39] for crosslinking a carboxylic acid functional polymer dissolved and / or dispersed, preferably dispersed, in an aqueous medium, wherein the amounts of aziridine groups and carboxylic acid groups are selected such that the stoichiometric amount (SA) of aziridine groups relative to carboxylic acid groups is from 0.1 to 2.0, more preferably from 0.2 to 1.5, even more preferably from 0.25 to 0.95, and most preferably from 0.3 to 0.8.

[0202]

[41] A two-component coating system, said two-component coating system comprising a first component and a second component, each of said first component and second component being independent and different from one another, and wherein said first component comprises a carboxylic acid-functional polymer dissolved and / or dispersed, preferably dispersed, in an aqueous medium, and said second component comprises a polyaziridine crosslinker composition as described in any one of embodiments [1] to

[36] or obtained using the method described in any one of embodiments

[37] to

[39] .

[0203]

[42] A substrate having a coating obtained by: (i) applying a coating composition obtained by mixing the first component and the second component of the two-component coating system according to embodiment

[41] to said substrate; and (ii) drying said coating composition by evaporating the volatile matter.

[0204] The present invention will now be illustrated by reference to the following examples. Unless otherwise specified, all parts, percentages and ratios are by weight.

[0205] Particle size measurement

[0206] Using a method derived from the ISO 22412:2017 standard, the mean hydrodynamic diameter of the particles based on the scattering intensity was determined using a Malvern Zetasizer Nano S90 DLS instrument, which was operated under the following settings: as the material, polystyrene latex was defined as having an RI of 1.590 at 25 °C, an absorption rate of 0.10 for demineralized water continuous medium with a viscosity of 0.8812 cP and an RI of 1.332. The measurements were performed in a DTS0012 disposable cuvette obtained from Malvern Instruments (Malvern, Worcestershire, United Kingdom). The measurements were performed at a backscattering angle of 173°, and after a 120-second equilibration, 3 measurements were averaged, consisting of 10 - 15 sub-runs - optimized by the machine itself. The focus of the laser was at a fixed position of 4.65 cm, and the data was analyzed using a general data fitting procedure. Samples were prepared by diluting 0.05 g (1 drop) of the sample dispersion in approximately 5 mL of demineralized water. If the sample still appeared turbid, it was further diluted with distilled water until the sample became almost clear. This method is applicable for determining particle sizes from 2 nm to 3 μm.

[0207] pH measurement

[0208] The pH of the sample was determined according to the ISO 976:2013 standard. The sample was measured at 23 °C using a Metrohm 691 pH meter equipped with a combined glass electrode and a PT-1000 temperature sensor. The pH meter was calibrated using buffer solutions of pH 7.00 and 9.21 before use.

[0209] NCO Determination

[0210] The NCO content of the sample was determined according to the ASTM D2572-19 standard. In this procedure, the sample was reacted with an excess of dibutylamine. Subsequently, the excess dibutylamine was back-titrated with standard 1N hydrochloric acid (HCl). The difference in titration volume between the sample and the blank is a measure of the isocyanate content in terms of solids, according to the following formula: %NCO 固体 = [(Vb - Vm) * N * 4.2] / (A * s / 100), where %NCO 固体 is the isocyanate content in terms of solids, Vb is the volume of HCl used in the blank, Vm is the volume of HCl used in the sample, N is the normality of the HCl solution, A is the weight of the sample in grams, and s is the solids content of the sample in %. The measurements were performed in duplicate using a potentiometric end point on a Metrohm 702SM Titrino titrator (if the difference between the two replicates of the duplicate < 0.1% NCO , the measurement results are accepted).

[0211] AV Determination

[0212] The acid value (AV) of the solid matter of the sample was determined based on the ASTM D1639-90(1996)e1 standard. In this procedure, the sample dissolved in a good solvent was titrated with an alcoholic potassium hydroxide (KOH) solution of known concentration. The difference in titration volume between the sample and the blank is a measure of the solid acid value, according to the following formula: AV = [(Vblank - Vsample) * N KOH * 56.1] / (W * S / 100), where AV is the solid acid value in mg KOH / g of solid matter, Vblank is the volume of the KOH solution used in the blank, Vsample is the volume of the KOH solution used in the sample, N KOH is the normality of the KOH solution, W is the weight of the sample in grams, and S is the solids content of the sample in %. The measurements were performed in duplicate using a potentiometric end point on a Metrohm 702SM Titrino titrator (if the difference between the two replicates of the duplicate < 0.1 mg KOH / g of solid matter, the measurement results are accepted).

[0213] Chemical Resistance

[0214] Chemical resistance test based on DIN 68861-1:2011-01 standard.

[0215] Unless otherwise specified, the chemical resistance test is as follows:

[0216] Compared with the carboxylic acid functional group, the coating composition consists of 0.9 stoichiometric amount (SA) of total carboxylic acid-reactive functional groups (such as aziridine). The coating composition is treated as described in the examples and then cast using a wire bar coater with a wet layer thickness of 100 μm. After casting, the film is dried at 25 °C for 1 hour and then annealed at 50 °C for 16 hours. Subsequently, a piece of absorbent cotton is soaked in ethanol:demineralized water (by weight) at 1:1 and placed on the film for 60 minutes (unless otherwise specified). After removing the absorbent cotton and allowing it to recover overnight, the spots are scored according to the following grades:

[0217] 1 Complete coating degradation

[0218] 2 Structural damage to the coating

[0219] 3 Severe markings on the coating, visible from multiple directions

[0220] 4 Slight markings on the coating, visible from a specific angle

[0221] 5 No markings or gloss changes observed

[0222] Viscosity measurement:

[0223] The apparent viscosity is determined according to ISO 2555:2018. The measurement is performed at 23 °C on a Brookfield DVE-LV viscometer (single cylinder geometry) at 60 rpm. Select the spindle from S62, S63 or S64, and use the smallest numbered spindle (i.e., the largest spindle) that produces a torque reading between 10% and 100%.

[0224] Size exclusion chromatography using NMP-MEK

[0225] The molecular weight distribution was measured using an Alliance separation module (Waters e2695), which includes a pump, an autosampler, a degasser, and an oven. The eluent was 80% N-methylpyrrolidone (NMP) / 20% methyl ethyl ketone (MEK), with 0.01 M lithium bromide added. The injection volume was 150 μl. The flow rate was set at 1.0 ml / min. Three PL Mixed B (Polymer Laboratories) columns with guard columns (5 μm PL) were applied at a temperature of 70 °C. Detection was performed at 50 °C using a differential refractive index detector (Waters 2414). The samples were dissolved in the eluent at a concentration of 5 mg polymer / mL solvent. Solubility was judged with a laser pen after 24 hours of stability at room temperature; if any scattering was visible, the sample was first filtered. Calculations were performed using eight polystyrene standards (Polymer Standards Service) in the range of 160 to 1,737,000 daltons. Calculations were performed using Empower software (Waters) with a third-order calibration curve. The molar mass obtained was the polystyrene equivalent molar mass (daltons).

[0226] T was measured by DSC g Measurement

[0227] The glass transition temperature (T) of the polymer was measured by differential scanning calorimetry (DSC) at a heating rate of 10 °C / min in an N2 atmosphere at a flow rate of 50 mL / min on a TA Instruments Discovery DSC 250 device according to the following method g : Weigh 5 ± 0.5 mg of the sample and place it in the DSC cell at a temperature between 20 °C and 25 °C. Cool the sample to -120 °C and equilibrate at this temperature; after equilibration, heat the sample from -120 °C to 160 °C at a heating rate of 5 °C / min; hold the sample at this temperature for 2 minutes, then cool it to -120 °C at a cooling rate of 20 °C / min; once the sample reaches -120 °C, maintain the temperature for 5 minutes; subsequently, heat the sample from -120 °C to 220 °C at a heating rate of 5 °C / min (Thermogram A). Measure T from this final thermogram (Thermogram A) g , which is the half-width of the step in the DSC signal (DSC thermogram, heat flow vs. temperature) observed for T g . Processing of the DSC signal and determination of T were performed using TRIOS software version 5.0 provided by TA instruments g .

[0228] Analysis of the low molecular weight fraction by LC-MS

[0229] LC system: Agilent 1290 Infinity II; Detector No. 1: Agilent 1290 Infinity II PDA; Detector No. 2: Agilent iFunnel 6550 Q-TOF-MS.

[0230] The LC-MS analysis of the low molecular weight fraction was performed using the following procedure. A methanol solution of approximately 100 mg / kg of the material was prepared gravimetrically and stirred. 0.5 μl of this solution was injected into a UPLC equipped with ESI-TOF-MS detection. The column used was a 100 × 2.1 mm, 1.8 um, Waters HSS T3 C18 operating at 40 °C. The flow rate was 0.5 ml / min. -1 The solvents used were 10 mM NH4CH3COO aqueous solution adjusted to pH 9.0 with NH3 (eluent A), acetonitrile (B), and THF (C). Two binary gradients were applied, one from 80 / 20 A / B to 1 / 99 A / B over 10 minutes and the other from 1 / 99 A / B to 1 / 49 / 50 A / B / C over 5 minutes, after which the starting conditions (80 / 20 A / B) were applied. Assuming that all components have a linear MS response over all response ranges and that the ionization efficiency of all components is equal, the total ion current signal was integrated. In the case of co-elution, the extracted ion chromatogram of that particular species was integrated. The integrated signal of a specific low molecular weight peak was divided by the total integrated sample signal to yield the fraction of that low molecular weight substance.

[0231] MALDI-ToF-MS

[0232] All MALDI-ToF-MS spectra were acquired using a Bruker Ultraflextreme MALDI-ToF mass spectrometer. The instrument was equipped with a Nd:YAG laser emitting at 1064 nm and a collision cell (not used for these samples). Using the reflector, spectra were acquired in positive ion mode using the highest resolution mode providing accurate mass (range 60 - 7000 m / z). Mass calibration was performed using cesium triiodide (range 0.3 - 3.5 kDa) (calibration method: IAV molecular characterization, code MC-MS-05). The laser energy was 20%. The sample was dissolved in THF at approximately 50 mg / mL. The matrix used was: DCTB (trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenylidene]malononitrile), CAS number 300364-84-5. The matrix solution was prepared by dissolving 20 mg in 1 mL of THF.

[0233] Sodium iodide was used as the salt (NaI, CAS number 7681-82-5); 10 mg was dissolved in 1 ml of THF and one drop of MeOH was added. Sample:matrix:salt ratio = 10:200:10 (μl), and after mixing, 0.5 μL was spotted onto a MALDI plate and air-dried. The peaks measured in the MALDI spectrum are the sodium adducts of the polyaziridine compounds, and in the context of this specification, the molecular weight (MW) of the polyaziridine compounds corresponds to MW = observed [M + M 阳离子 – M 阳离子 , where observed [M + M 阳离子 is the MALDI-TOF MS peak and M 阳离子 is the exact mass number of the cation used to prepare the adduct (in this case, M for sodium 阳离子 = 23.0 Da). The polyaziridine compounds can be identified by comparing the MW with the exact molecular mass of the theoretical structure (i.e., the sum of the non-isotopic average atomic masses of its constituent atoms) using a maximum deviation of 0.6 Da.

[0234] Genotoxicity testing

[0235] Genotoxicity was evaluated by determination (Toxys, Leiden, the Netherlands). The ToxTracker determination is a set of several validated green fluorescent protein (GFP)-based mouse embryonic stem (mES) reporter cell lines that can be used to identify the biological activity and potential carcinogenic properties of newly developed compounds in a single test. The method uses a two-step approach.

[0236] In the first step, a dose range finding was performed using wild-type mES cells (strain B4418). Twenty different concentrations of each compound were tested, starting with 10 mM in DMSO as the highest concentration and 19 consecutive 2-fold dilutions.

[0237] Next, genotoxicity was evaluated using specific genes linked to a reporter gene for the detection of DNA damage; the specific genes being the Bscl2 (as elucidated by US9695481B2 and EP2616484B1) and Rtkn (Hendriks et al., Toxicol. Sci. 2015, 150, 190 - 203) biomarkers. Genotoxicity was evaluated at 10%, 25%, and 50% cytotoxicity in the absence and presence of a metabolic system based on rat S9 liver extract (aroclor1254 - induced rats, Moltox, Boone, NC, USA). Independent cell lines were seeded into 96 - well cell culture plates and fresh ES cell medium containing the diluted test substance was added to the cells 24 hours after cell seeding into the 96 - well plates. For each compound tested, five concentrations were tested at 2 - fold dilutions. The highest sample concentration would induce significant cytotoxicity (50 - 70%). In the case of no or low cytotoxicity, 10 mM or the maximum soluble mixture concentration was used as the maximum test concentration. Cytotoxicity was determined by cell counting using a Guava easyCyte 10HT flow cytometer (Millipore) after 24 hours of exposure.

[0238] The GFP reporter gene induction was always compared to vehicle control treatment. For specific compounds, the DMSO concentration in all wells was similar and never exceeded 1%. All compounds were tested in at least three completely independent replicate experiments. All experiments included a positive control treatment with cisplatin (DNA damage). Metabolism was evaluated by addition of S9 liver extract. Cells were exposed to five concentrations of the test compound for 3 hours in the presence of S9 and the required co - factors (RegenSysA + B, Moltox, Boone, NC, USA). After washing, the cells were incubated in fresh ES cell medium for 24 hours. After 24 hours of exposure, the induction of the GFP reporter gene was determined using a Guava easyCyte 10HT flow cytometer (Millipore). GFP expression was determined only in intact single cells. The average GFP fluorescence and cell concentration in each well were measured and used for cytotoxicity assessment. Data were analyzed using ToxPlot software (Toxys, Leiden, the Netherlands). The reported induction levels were at the compound concentrations that induced 10%, 25%, and 50% cytotoxicity after 3 hours of exposure in the presence of S9 rat liver extract and a 24 - hour recovery or alternatively after 24 hours of exposure in the absence of S9 rat liver extract.

[0239] The positive induction level of a biomarker is defined as equal to or higher than 2-fold induction at at least one of 10%, 25%, and 50% cytotoxicity in the absence or presence of a metabolic system of rat S9 liver extract; weak positive induction is defined as higher than 1.5-fold and lower than 2-fold induction (but lower than 2-fold at 10%, 25%, and 50% cytotoxicity) at at least one of 10%, 25%, and 50% cytotoxicity in the absence or presence of a metabolic system of rat S9 liver extract, and negative induction is defined as lower than or equal to 1.5-fold induction at 10%, 25%, and 50% cytotoxicity in the absence or presence of a metabolic system based on rat S9 liver extract.

[0240] Components and abbreviations used:

[0241] Poly(tetrahydrofuran) with an average Mn of 1000 Da was obtained from BASF.

[0242] o-Xylene (CAS No. 95-47-6) was obtained from Sigma-Aldrich.

[0243] TDI (toluene diisocyanate, CAS No. 26471-62-5, T80, an 80 / 20 mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate) was obtained from Covestro.

[0244] 1-(2-Hydroxyethyl)ethylenimine) (CAS No. 1072-52-2) was obtained from Tokyo Chemical Industry Co., Ltd.

[0245] Triton X-100 (CAS No. 9002-93-1) was obtained from Sigma-Aldrich.

[0246] D3403 was obtained from Evonik.

[0247] IPDI (5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane, I, isophorone diisocyanate, CAS No. 4098-71-9) was obtained from Covestro.

[0248] 1-Methoxy-2-propyl acetate (MPA, propylene glycol monomethyl ether acetate, CAS No. 108-65-6) was obtained from Shell Chemicals.

[0249] Dibutyltin dilaurate (CAS No. 77-58-7) was obtained from Sigma-Aldrich.

[0250] 1-Propanol (CAS No. 71-23-8) was obtained from Sigma-Aldrich.

[0251] Tin 2-ethylhexanoate (CAS No. 301-10-0) was obtained from Sigma-Aldrich.

[0252] Atlas TM G-5000 and Maxemul TM 7101 was obtained from Croda.

[0253] Bismuth neodecanoate (CAS No. 34364-26-6) was obtained from TIB chemicals AG (Mannheim, Germany).

[0254] Ethylene imine (CAS No. 151-56-4) was obtained from Menadiona S.L. (Palafolls, Spain).

[0255] N3600 was obtained from Covestro.

[0256] Dimethylformamide (CAS No. 68-12-2) was obtained from Acros Organics (a subsidiary of Thermo Fisher Scientific).

[0257] Di(propylene glycol) dimethyl ether (Proglyde DMM, CAS No. 111109-77-4) was obtained from Dow Inc.

[0258] Trimethylolpropane tris(2-methyl-1-aziridinepropionate), CAS No. 64265-57-2, CX-100 was obtained from DSM.

[0259] Potassium carbonate (CAS No. 584-08-7) was obtained from Alfa Aesar (a subsidiary of Thermo Fisher Scientific).

[0260] n-Butyl glycidyl ether (CAS No. 2426-08-6) was obtained from Alfa Aesar (a subsidiary of Thermo Fisher Scientific).

[0261] Hydrazine (16% aqueous solution, CAS No. 302-01-2) was obtained from Honeywell.

[0262] Dimethylolpropionic acid (DMPA, CAS No. 4767-03-7) was obtained from Perstop Polyols.

[0263] Triethylamine (TEA, CAS No. 121-44-8) was obtained from Arkema.

[0264] Polypropyleneglycol with a number-average molecular weight of 1000 Da and 2000 Da was obtained from BASF.

[0265] 3-Methyl-1-phenyl-2-phospholene-1-oxide (CAS No. 707-61-9) was obtained from Sigma-Aldrich.

[0266] Sodium dodecyl sulfate (30% aqueous solution, CAS No. 73296-89-6) was obtained from BASF.

[0267] Methyl methacrylate (CAS No. 80-62-6) was obtained from Lucite Int.

[0268] n-Butyl acrylate (CAS No. 141-32-2) was obtained from Dow Chemical.

[0269] Methacrylic acid (CAS No. 79-41-4) was obtained from Lucite Int.

[0270] Ammonium persulfate (CAS No. 7727-54-0) was obtained from United Initiators.

[0271] Ammonia (25% aqueous solution, CAS No. 1336-21-6) was obtained from Merck.

[0272] 1-Butanol (CAS No. 71-36-3) was obtained from Sigma-Aldrich.

[0273] Acetone (CAS No. 67-64-1) was obtained from Acros Organics (a subsidiary of Thermo Fisher Scientific).

[0274] Methyl ethyl ketone (CAS No. 78-93-3) was obtained from Sigma-Aldrich.

[0275] Synthesis of P1 of aqueous polyurethane

[0276] Charge a 1 L flask (equipped with a thermometer and overhead stirrer) with 29.9 g of dimethylolpropionic acid, 282.1 g of a polypropylene glycol having a calculated average molecular weight (M) of 2000 Da and an OH value of 56 ± 2 mg KOH / g, 166.5 g of a polypropylene glycol having a calculated average molecular weight (M) of 1000 Da and an OH value of 112 ± 2 mg KOH / g, and 262.8 g of isophorone diisocyanate (the average molecular weight of each polyol in the polyol is calculated from its OH value according to the following equation: M = 2 * 56100 / [OH value in mg KOH / g polypropylene glycol]). Place the reaction mixture under a N2 atmosphere and heat to 50 °C, then add 0.07 g of dibutyltin dilaurate to the reaction mixture. An exothermic reaction was observed; however, appropriate measures were needed to keep the reaction temperature from exceeding 97 °C. Maintain the reaction at 95 °C for one hour. As determined by the method described herein, the resulting polyurethane P1' had an NCO content of 7.00% (theoretically 7.44%) on a solids basis, and an acid value of 16.1 ± 1 mg KOH / g of polyurethane P1'. Cool the polyurethane P1' to 60 °C, add 18.7 g of triethylamine, and stir the resulting mixture for 30 minutes. Subsequently, prepare an aqueous dispersion of polyurethane P1' (the aqueous dispersion of polyurethane P1' is further referred to as P1) as follows: Feed the mixture of polyurethane P1' and triethylamine thus prepared into a mixture of 1100 g of demineralized water, 19.5 g of nonylphenol ethoxylate (9 ethoxylate groups), and 4.0 g of triethylamine at room temperature over a 60-minute period. After the feeding is complete, stir the mixture for an additional 5 minutes, then add 111.2 g of hydrazine (16 wt% aqueous solution) to the mixture. Stir the thus-prepared aqueous dispersion of polyurethane P1' for an additional 1 h to obtain P1.

[0277] Example 1

[0278] Place a round-bottom flask equipped with a condenser under a N2 atmosphere and charge with ethyleneimine (50.0 g), n-butyl glycidyl ether (108.0 g), and K2CO3 (5.00 g) and heat to 40 °C over 30 minutes, after which the mixture is stirred at T = 40 °C for 48 h. After filtration, remove the excess EI under vacuum, then further purify by vacuum distillation to obtain a colorless low-viscosity liquid.

[0279] Charge 17.2 g of the resulting material (1-(aziridin-1-yl)-3-butoxypropan-2-ol) into a reaction flask equipped with a thermometer together with 150 g of dimethylformamide. Stir the mixture under a nitrogen atmosphere with a mechanical overhead stirrer and heat to 50 °C. Then add 20.0 g A solution of 3600 in 75 g of dimethylformamide was added to a feed vessel. Then, 0.02 g of bismuth neodecanoate was added to a reaction flask, and then the solution in the reaction vessel was added dropwise to the reaction flask over 30 minutes while maintaining the reaction temperature constant at 50 °C. After the feeding was complete, the temperature was raised to 80 °C. Samples were taken at regular intervals and the progress of the reaction was monitored using a Bruker Alpha FT-IR spectrometer until no change in the NCO stretch was observed at 2200 - 2300 cm -1 −1. Subsequently, 0.64 g of 1-butanol was added to the mixture, and the reaction was further continued until the above NCO stretch peak completely disappeared. The solvent was evaporated in vacuo to yield a pale yellow highly viscous liquid.

[0280] The calculated molecular weight of the theoretical main component is 1023.69 Da, and the chemical structure is shown below.

[0281]

[0282] The molecular weight was confirmed by Maldi-TOF-MS: calculated [M+Na+] = 1046.69 Da; observed [M+Na+] = 1046.72 Da.

[0283] The following components with a mass below 580 Da were determined and quantified by LC-MS:

[0284]

[0285] is present in the composition at 0.48 wt%, and

[0286]

[0287] is present at less than 0.01 wt%.

[0288] Genotoxicity testing

[0289]

[0290] The genotoxicity test results showed that the crosslinker composition of Example 1 is non-genotoxic.

[0291] Subsequently, 10 g of the viscous liquid obtained in the previous step was mixed with 5 g of acetone and incubated at 50 °C until a homogeneous solution was obtained. 0.03 g of triethylamine (TEA) was added to this solution, and then 2 g of molten Maxemul TM 7101 dispersant was added. Using an IKA T25 Digital with an S 25 N-18G head The mixer stirred the resulting mixture at 2,000 rpm for 5 minutes at room temperature. Then, the stirring was increased to 10,000 rpm, and 10 g of demineralized water adjusted to pH 11 with triethylamine was gradually added to the mixture over 15 minutes. During this addition process, the mixer was continuously moved around the reaction vessel. After the addition was complete, the resulting dispersion was stirred at 5,000 rpm for another 10 minutes, and the pH of the dispersion was set to 11 with TEA.

[0292] The functional properties and stability of the crosslinker dispersion were evaluated using spot tests on the coated surface carried out according to the procedure from the DIN 68861-1 standard, and viscosity measurements using a Brookfield DVE-LV viscometer (spindle S62 at 60 rpm, unless otherwise stated). For these tests, the crosslinker dispersion was stored in an oven at 50 °C for 4 weeks. The viscosity of the crosslinker dispersion was measured weekly. Additionally, 1.0 g of the aged crosslinker dispersion was mixed with 10.5 g of polymer P1 under continuous stirring each week, and the resulting mixture was stirred further for 30 minutes. This coating composition was filtered and applied to a Leneta test card using a 100 μm wire bar coater (Test 1). As a reference, a film was also cast from the same combination lacking the crosslinker dispersion (Test blank). The film was dried at 25 °C for 1 hour and then annealed at 50 °C for 16 hours. Subsequently, a piece of cotton wool was dipped into 1:1 EtOH:demineralized water and placed on the film for 1 hour. After removing the EtOH and allowing to recover for 60 minutes, the following results were obtained (rating 1 indicates complete degradation of the film, 5 indicates no visible damage):

[0293] Performance and stability tests

[0294]

[0295] The performance of the synthesized compound as a crosslinker was evaluated using spot tests on the coated surface with different binder systems.

[0296] The aqueous acrylic binder A1 was synthesized as follows.

[0297] In a 2 L four-necked flask equipped with a thermometer and a top-mounted stirrer, sodium dodecyl sulfate (30% solids in aqueous solution, 18.6 g of solution) and demineralized water (711 g) were charged. The reactor was placed under a N2 atmosphere and heated to 82 °C. A mixture of demineralized water (112 g), sodium dodecyl sulfate (30% solids in water, 37.2 g of solution), methyl methacrylate (209.3 g), n-butyl acrylate (453.56 g), and methacrylic acid (34.88 g) was placed in a large feed funnel and emulsified with the top-mounted stirrer (monomer feed). Ammonium persulfate (1.75 g) was dissolved in demineralized water (89.61 g) and placed in a small feed funnel (initiator feed). Ammonium persulfate (1.75 g) was dissolved in demineralized water (10.5 g), and this solution was added to the reactor phase. Immediately thereafter, 5 vol% of the monomer feed was added to the reactor phase. Then the reaction mixture was exothermed to 85 °C and held at 85 °C for 5 minutes. Then, the remaining monomer feed and initiator feed were fed into the reaction mixture over 90 minutes while maintaining the temperature at 85 °C. After the feeding was completed, the monomer feed funnel was rinsed with demineralized water (18.9 g), and the reaction temperature was maintained at 85 °C for 45 minutes. Subsequently, the mixture was cooled to room temperature, adjusted to pH = 7.2 with ammonia solution (6.25 wt% in demineralized water), and adjusted to 40% solids with additional demineralized water.

[0298] For further spot tests, additional crosslinker dispersions synthesized as described above were stored in an oven at 50 °C for 4 weeks. Weekly, 2.0 g of the aged crosslinker dispersion was mixed with 10.5 g of aqueous acrylic binder A1 with continuous stirring, and the resulting mixture was further stirred for 30 minutes. This coating composition was filtered and applied to a Leneta test card using a 100 μm wire bar coater (Test 1-A1). As a reference, a film was also cast from the same combination lacking the crosslinker dispersion (Blank-A1). The film was dried at 25 °C for 1 hour and then annealed at 50 °C for 16 hours. Subsequently, a piece of cotton wool was dipped into 1:1 EtOH:demineralized water and placed on the film for 1 hour. After removing the EtOH and allowing to recover for 60 minutes, the following results were obtained (a score of 1 indicates complete degradation of the film, and 5 indicates no visible damage):

[0299]

[0300] Comparative example C1

[0301] For Comparative Example 1, crosslinker CX-100 - trimethylolpropane tris(2-methyl-1-aziridinepropionate) was used:

[0302]

[0303] Genotoxicity test

[0304]

[0305] The genotoxicity test results indicate that the crosslinker composition of Example C1 is genotoxic.

[0306] 7.5 grams of this crosslinker was mixed with 3.75 grams of acetone and incubated at 50 °C until a homogeneous solution was obtained. 0.03 grams of triethylamine was added to this solution, and then 0.75 grams of molten Atlas TM G-5000 dispersant. The resulting mixture was stirred at 2,000 rpm for 5 minutes at room temperature using an IKA T25 Digital mixer with an S25 N-18G head. Then, the stirring was increased to 10,000 rpm, and 7.5 grams of demineralized water adjusted to pH 11 with triethylamine (TEA) was gradually added to the mixture over 15 minutes. During this addition process, the mixer was continuously moved around the reaction vessel. After the addition was complete, the resulting mixture was stirred at 5,000 rpm for an additional 10 minutes, and the pH of the mixture was set to 11.

[0307] The functional properties and stability of the crosslinker mixture were evaluated using spot tests on the coated surface carried out using a procedure based on the DIN 68861-1 standard, and viscosity measurements using a Brookfield DVE-LV viscometer (S62 spindle at 60 rpm unless otherwise stated). For these tests, the crosslinker dispersion was stored in an oven at 50 °C for 4 weeks. The viscosity of the crosslinker mixture was measured weekly. In addition, 0.8 grams of the aged crosslinker mixture was mixed with 21 grams of polymer P1 under continuous stirring each week, and the resulting coating composition was further stirred for 30 minutes. This coating composition was filtered and applied to a Leneta test card using a 100 μm wire bar coater (Test C1). As a reference, a film was also cast from the same combination lacking the crosslinker mixture (Test blank). The film was dried at 25 °C for 1 hour and then annealed at 50 °C for 16 hours. Subsequently, a piece of cotton wool was immersed in 1:1 EtOH:demineralized water and placed on the film for 1 hour. After removing the EtOH and allowing to recover for 60 minutes, the following results were obtained (rating 1 indicates complete degradation of the film, 5 indicates no visible damage):

[0308] Performance and stability tests

[0309]

[0310] * The crosslinker mixture gelled during the first week of storage

[0311] Comparative example C2

[0312] As in Example C1, where during the water addition step, 7.5 g of demineralized water adjusted to pH 9 with TEA was used instead of demineralized water adjusted to pH 11, and the resulting mixture was set to pH 9 with TEA.

[0313] Performance and stability tests

[0314]

[0315]

[0316] * The crosslinker mixture gelled during the first week of storage

[0317] Comparative example C3

[0318] As in Example C1, where during the water addition step, 7.5 g of demineralized water adjusted to pH 8 with TEA was used instead of demineralized water adjusted to pH 11, and the resulting mixture was set to pH 8 with TEA.

[0319] Performance and stability tests

[0320]

[0321] * The crosslinker mixture gelled during the first week of storage

[0322] Comparative example C4

[0323] 13.0 g of 1-(2-hydroxyethyl)ethylenimine and 175 g of dimethylformamide were charged into a reaction flask equipped with a thermometer. The mixture was stirred with a mechanical overhead stirrer under a nitrogen atmosphere. Then the mixture was heated to 50 °C, after which 0.03 g of bismuth neodecanoate was charged into the reaction flask. Subsequently, a solution of 30.0 g of Desmodur N 3600 in 87.5 g of dimethylformamide was added over 30 minutes. After the feeding was completed, the reaction temperature was raised to 80 °C. Samples were taken at regular intervals and the reaction progress was monitored using a Bruker Alpha FT-IR spectrometer until no NCO stretch was observed at 2200 - 2300 cm -1 −1. The solvent was removed under vacuum to obtain a clear, colorless, highly viscous liquid. The calculated molecular weight of the theoretical main component was 765.47 Da and the chemical structure is shown below.

[0324]

[0325] Molecular weight was confirmed by Maldi-TOF-MS: calculated [M+Na+] = 788.46 Da; observed [M+Na+] = 788.31 Da.

[0326] Subsequently, 7.5 g of the colorless liquid obtained in the previous step was mixed with 3.8 g of acetone and incubated at 50 °C until a homogeneous solution was obtained. 0.03 g of triethylamine (TEA) was added to the solution, followed by 0.8 g of molten Maxemul TM 7101 dispersant. The resulting mixture was stirred at 2,000 rpm for 5 minutes at room temperature using an IKA T25 Digital mixer with an S 25 N-18G head. Then, the stirring was increased to 10,000 rpm and 7.5 g of demineralized water adjusted to pH 11 with triethylamine was gradually added to the mixture over 15 minutes. During this addition, the mixer was continuously moved around the reaction vessel. After the addition was complete, the resulting dispersion was stirred at 5,000 rpm for an additional 10 minutes and the pH of the dispersion was set to 11 with TEA. Severe coagulation was observed within 4 hours after the end of this preparation based on 1-(2-hydroxyethyl)ethylenimine. Thus, a storage-stable dispersion was not obtained.

[0327] Comparative example C5

[0328] Under a nitrogen atmosphere, at 20 - 25 °C, with stirring, 21.3 g of 1-propanol was added to 78.7 g of isophorone diisocyanate (IPDI) and 0.01 g of tin 2-ethylhexanoate over a 6-hour period. After standing overnight, 196.3 g of IPDI, 74.1 g of Tegomer D3403 and 2.4 g of 3-methyl-1-phenyl-2-phospholene-1-oxide were added. The mixture was heated to 150 °C with stirring. The mixture was maintained at 150 °C until the NCO content was 7.0 wt%. The mixture was cooled to 80 °C and 333 g of 1-methoxy-2-propyl acetate (MPA) was added. A solution of an isocyanate-functional polycarbodiimide with a solids content of 50.6 wt% and an NCO content of 7.0 wt% based on solids was obtained.

[0329] 7.0 g of 1-(2-hydroxyethyl)ethylenimine was added to 100 g of this isocyanate-functional polycarbodiimide. One drop of dibutyltin dilaurate was added. The mixture was heated to 80 °C with stirring. The mixture was kept at 80 °C for 1 h. FTIR showed a small amount of residual isocyanate signal, which disappeared after several days. The solution was further diluted with 8.0 g of MPA to give a yellow solution with a solids content of 50.4 wt%. This aziridine-functional carbodiimide contains 3.2 meq of acid-reactive groups (i.e., aziridine and carbodiimide functionality) per gram of solids.

[0330] The general structure of this carbodiimide is depicted below.

[0331]

[0332] where a, b, and c represent repeating units.

[0333] MALDI-TOF-MS confirmed this general structure, as exemplified below:

[0334]

[0335] The molecular weight was confirmed by Maldi-TOF-MS: calculated [M+Na+] = 2043.34 Da; observed [M+Na+] = 2043.32 Da.

[0336] Genotoxicity test results:

[0337]

[0338] The genotoxicity test results showed that the crosslinker composition of Example C5 was genotoxic.

[0339] Subsequently, 25.0 g of the yellow solution obtained in the previous step was stirred at 500 rpm at room temperature using a three-blade propeller stirrer with a diameter of 50 mm. Then, 25.0 g of demineralized water was gradually added to the mixture within 15 minutes. After the addition was complete, the resulting dispersion was stirred at 500 rpm for another 5 minutes.

[0340] The functional properties and stability of the crosslinker dispersion were evaluated using a spot test on the coated surface with a process based on the DIN 68861-1 standard, and viscosity measurements using a Brookfield DVE-LV viscometer (S62 spindle at 60 rpm unless otherwise stated). For these tests, the crosslinker dispersion was stored in an oven at 50 °C for 4 weeks. The viscosity of the crosslinker dispersion was measured weekly. In addition, 5.1 g of the aged crosslinker dispersion was mixed with 10.5 g of polymer P1 with continuous stirring each week, and the resulting mixture was further stirred for 30 minutes. This coating composition was filtered and applied to a Leneta test card (Test C7) using a 100 μm wire bar coater. As a reference, a film was also cast from the same combination lacking the crosslinker dispersion (test blank). The film was dried at 25 °C for 1 hour and then annealed at 50 °C for 16 hours. Subsequently, a piece of cotton wool was immersed in 1:1 EtOH:demineralized water and placed on the film for 1 hour. After removing the EtOH and allowing to recover for 60 minutes, the following results were obtained (rating 1 indicates complete degradation of the film, 5 indicates no visible damage):

[0341] Performance and stability tests

[0342]

[0343] * The crosslinker mixture coagulated during the first week of storage

[0344] Comparative example C8

[0345] A 1 L round-bottom flask equipped with a thermometer and overhead stirrer was placed under a N2 atmosphere and charged with 196.1 g of polytetrahydrofuran with an average Mn of 1000 Da (pTHF1000) and 200.0 g of o-xylene. The resulting mixture was cooled to -10 °C using ethanol and ice, after which a solution of 68.4 g of toluene diisocyanate (TDI) in 50.0 g of o-xylene was added. The mixture exothermed, causing the mixture to reach -1 °C and then gradually rise to room temperature without additional heating. The reaction was continued to complete conversion (residual NCO of 3.2%), and 200 g of the resulting reaction mixture was transferred under a N2 atmosphere to a 500 mL round-bottom flask equipped with a thermometer and overhead stirrer. Then 14.5 g of 1-(2-hydroxyethyl)vinylimine was added to this mixture over 60 minutes, maintaining room temperature using a water bath. The mixture was then stirred at 25 °C for 1 hour. Then, samples were taken at regular intervals and the reaction progress was monitored using a Bruker Alpha FT-IR spectrometer until at 2200 - 2300 cm -1Observation was made until no NCO stretching was observed. Another o-xylene was used to set the solid content to 49%, resulting in a slightly turbid low-viscosity solution.

[0346] The calculated molecular weight and chemical structure of the theoretical main component are shown below:

[0347]

[0348] The molecular weight was confirmed by Maldi-TOF-MS: calculated [M+Na+] = 1427.91 Da; observed [M+Na+] = 1428.02 Da.

[0349]

[0350] The molecular weight was confirmed by Maldi-TOF-MS: calculated [M+Na+] = 371.17 Da; observed [M+Na+] = 371.21 Da.

[0351] Subsequently, 18.0 g of the low-viscosity solution obtained as described above was mixed with 1.5 g of Triton X-100 and incubated at 50 °C until a homogeneous solution was obtained. The resulting mixture was stirred at 500 rpm for 30 minutes using a three-blade propeller stirrer with a diameter of 50 mm at room temperature. Then, the stirring was increased to 800 rpm, and 15.0 g of demineralized water was gradually added to the mixture over 15 minutes. After the addition was complete, the resulting dispersion was stirred at 500 rpm for an additional 10 minutes.

[0352] The functional properties and stability of the crosslinker dispersion were evaluated using a spot test on the coated surface carried out according to the procedure from the DIN 68861-1 standard, and viscosity measurements using a Brookfield DVE-LV viscometer (S62 spindle at 60 rpm unless otherwise stated). For these tests, the crosslinker dispersion was stored in an oven at 50 °C for 4 weeks. The viscosity of the crosslinker dispersion was measured weekly. In addition, 2.8 g of the aged crosslinker dispersion was mixed with 10.5 g of polymer P1 under continuous stirring each week, and the resulting mixture was further stirred for 30 minutes. The coating composition was filtered and applied to a Leneta test card (test C8) using a 100 μm wire bar coater. As a reference, a film was also cast from the same combination lacking the crosslinker dispersion (test blank). The film was dried at 25 °C for 1 hour and then annealed at 50 °C for 16 hours. Subsequently, a piece of cotton wool was immersed in 1:1 EtOH:demineralized water and placed on the film for 1 hour. After removing the EtOH and allowing to recover for 60 minutes, the following results were obtained (rating 1 indicates complete degradation of the film, 5 indicates no visible damage):

[0353] Performance and Stability Tests

[0354]

[0355] * The crosslinker mixture gelled in the second week of storage

[0356] Reliable particle size measurement results could not be obtained for this sample.

Claims

1. A polyaziridine crosslinking agent composition, characterized in that The polyaziridine crosslinker composition is an aqueous dispersion having a pH in the range of 9 to 14 and contains a polyaziridine compound in dispersed form, wherein the polyaziridine compound has: a. 2 to 6 of the following structural units A: wherein R1, R2, R3, and R4 are H, m is 1, R' = H; and R” = CH2-O-(C=O)-R”' or CH2-O-R””, where R”' is an alkyl group containing 4 to 12 carbon atoms and R”” is an alkyl group containing 1 to 14 carbon atoms; b. one or more linking chains, where each of these linking chains links two of the structural units A in the structural unit A, where the linking chain is the shortest chain of consecutive atoms linking two structural units A, and the linking chain is a set of covalently bonded atoms, the set of atoms consisting of i) carbon atoms, ii) carbon and nitrogen atoms, or iii) carbon, oxygen, and nitrogen atoms; and c. a molecular weight in the range of 600 to 10,000 daltons, where the molecular weight is determined using MALDI-TOF mass spectrometry; d. one or more linking groups, where each of these linking groups links two structural units A, and the linking group consists of at least one functional group selected from aliphatic hydrocarbon functional groups, alicyclic hydrocarbon functional groups, isocyanurate functional groups, iminodiazinedione functional groups, and any combination thereof.

2. The polyaziridine crosslinking agent composition according to claim 1, characterized in that The linking chain consists of 4 to 300 atoms.

3. The polyaziridine crosslinking agent composition according to claim 1 or 2, characterized in that The polyaziridine compound contains 2 or 3 structural units A.

4. The polyaziridine crosslinking agent composition according to claim 1 or 2, characterized in that R' is H and R” = CH2-O-(C=O)-R”' or CH2-O-R””, where R”' is an alkyl group containing 4 to 12 carbon atoms and R”” is an alkyl group containing 1 to 14 carbon atoms.

5. The polyaziridine crosslinking agent composition according to claim 1 or 2, wherein the linking group of the polyaziridine compound is selected from at least one functional group consisting of the group consisting of the following items: Aliphatic hydrocarbon functional groups, isocyanurate functional groups, iminodiazinedione functional groups, and any combination thereof.

6. The polyaziridine crosslinking agent composition according to claim 1 or 2, wherein the polyaziridine compound contains one or more linking groups, wherein each of these linking groups connects two structural units A in the structural unit A, wherein the linking group is composed of (i) at least two aliphatic hydrocarbon functional groups and (ii) an isocyanurate functional group or an iminodioxazine dione functional group, and wherein side groups are present on the linking group, wherein the side groups have the following structural formula: Wherein n' is the number of repeating units and is an integer from 1 to 50; X is O or NH, In each repeating unit, R7 and R8 are independently H or CH3, R9 is an aliphatic hydrocarbon group, and R 10is an aliphatic hydrocarbon group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 5 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms.

7. The polyaziridine crosslinking agent composition according to claim 6, wherein One of R7 and R8 is H, and the other of R7 and R8 is CH3.

8. The polyaziridine crosslinking agent composition according to claim 1 or 2, wherein The number of consecutive C atoms and optionally O atoms between the N atom of the carbamate group in the structural unit A and the next N atom that is either present in the linking chain or is the N atom of the carbamate group of another structural unit A is at most 9.

9. The polyaziridine crosslinking agent composition according to claim 1 or 2, wherein The molecular weight of the polyaziridine compound is 600 to 5,000 daltons.

10. The polyaziridine crosslinking agent composition according to claim 1 or 2, wherein The aqueous dispersion contains, based on the total weight of the aqueous dispersion, less than 5% by weight of aziridine-functional molecules having a molecular weight less than 580 daltons, where the molecular weight is determined using LC-MS.

11. The polyaziridine crosslinking agent composition according to claim 1 or 2, wherein The pH of the aqueous dispersion is at least 9.5 and at most 13.

12. The polyaziridine crosslinking agent composition according to claim 1 or 2, wherein The amount of water in the aqueous dispersion is at least 15% by weight and at most 95% by weight based on the total weight of the aqueous dispersion.

13. The polyaziridine crosslinking agent composition according to claim 1 or 2, wherein The amount of the polyaziridine compound in the aqueous dispersion is at least 5% by weight and at most 70% by weight based on the total weight of the aqueous dispersion.

14. The polyaziridine crosslinking agent composition according to claim 1 or 2, wherein The solids content of the aqueous dispersion is at least 5% by weight and at most 70% by weight.

15. The polyaziridine crosslinking agent composition according to claim 1 or 2, wherein The polyaziridine crosslinker composition comprises particles containing the polyaziridine compound, wherein the particles have an average hydrodynamic diameter based on scattering intensity of 50 nm to 500 nanometers.

16. The polyaziridine crosslinking agent composition according to claim 1 or 2, wherein The aqueous dispersion comprises a dispersant.

17. The polyaziridine crosslinking agent composition according to claim 1 or 2, wherein The aqueous dispersion comprises a separate surfactant molecule component as the dispersant, and the amount of the separate surfactant molecule component ranges from 0.1% by weight to 20% by weight based on the total weight of the aqueous dispersion.

18. The polyaziridine crosslinking agent composition according to claim 17, wherein The dispersant is a polyether having a number average molecular weight of at least 2000 daltons and at most 1000000 daltons as determined by MALDI-ToF mass spectrometry.

19. Use of the polyaziridine crosslinking agent composition according to any one of claims 1 to 18 for crosslinking a carboxylic acid functional polymer dissolved and / or dispersed in an aqueous medium, wherein the carboxylic acid functional polymer contains carboxylic acid groups and carboxylate groups, and the amounts of aziridine groups and carboxylic acid groups and carboxylate groups are selected such that the stoichiometric amount of aziridine groups on the carboxylic acid groups and carboxylate groups is from 0.1 to 2.

0.

20. A two-component coating system, the two-component coating system comprising a first component and a second component, each of the first component and the second component being separate and different from each other, and wherein The first component comprises a carboxylic acid functional polymer dissolved and / or dispersed in an aqueous medium, wherein the carboxylic acid functional polymer contains carboxylic acid groups and / or carboxylate groups, and the second component comprises a polyaziridine crosslinker composition according to any one of claims 1 to 18.

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