Polynitrogen aziridine compound

Abstract

The present invention relates to a polyaziridine compound having: a) at least 2 of the following structural units (A): wherein, R1 is H; R2 and R4 are independently selected from H, a straight-chain group having 1 to 8 carbon atoms and optionally containing one or more heteroatoms, a branched or cyclic group having 3 to 8 carbon atoms and optionally containing one or more heteroatoms, phenyl, benzyl or pyridyl; R3 is selected from a straight-chain group having 1 to 8 carbon atoms and optionally containing one or more heteroatoms, a branched or cyclic group having 3 to 8 carbon atoms and optionally containing one or more heteroatoms, phenyl, benzyl or pyridyl; or R2 and R3 (when R2 is different from H) can be part of the same cyclic group having 3 to 8 carbon atoms; R' and R" are independently H or an aliphatic hydrocarbon group having 1 to 12 carbon atoms; and b) a molecular weight of 600 to 20000 daltons, wherein the molecular weight is determined using MALDI-TOF mass spectrometry according to the description.

Description

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

[0002] Coatings provide protection, aesthetic quality and new functions for a variety of substrates of great industrial and domestic relevance. In this context, there is a growing demand for coatings with improved stain resistance and solvent resistance, improved mechanical properties and improved adhesion strength. One or more of these properties can be enhanced by crosslinking. Many crosslinking mechanisms for polymer binders have been studied over the years, and for aqueous latex polymer dispersions, the most useful ones 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 adhesives are usually colloidal stabilized by carboxylic acid groups and the coating properties can be improved by using carbodiimide or aziridine crosslinkers as they react with the carboxylic acid moiety of the polymer to form a crosslinked network. Among the above state-of-the-art crosslinkers, aziridine crosslinkers are most suitable for room temperature curing of carboxylic acid functional polymers.

[0004] US-A-5133997 describes a coating composition comprising an aqueous dispersion of a linear aliphatic urethane resin, an anionic surfactant and a crosslinker capable of promoting the curing of said resin. Trimethylolpropane tris(2-methyl-1-aziridinepropionate), CAS No. 64265-57-2, a polyfunctional aziridine crosslinker, is used as the crosslinker and is a well-known very active crosslinker for crosslinking carboxylic acid functional polymers. This crosslinker, like other state-of-the-art aziridines such as XAMA-7 (pentaerythritol tris[3-(1-aziridine)propionate]; CAS No. 57116-45-7), has an adverse genotoxicity profile. There is a need in the industry to improve the safety, health and environmental characteristics of adhesives, inks and coatings and the substances used for preparing adhesives, inks and coatings. Genotoxicity describes the property of any type of DNA damage caused by chemical or physical agents, which may not always result in transmissible mutations. Mutagenicity refers to the induction of permanent transmissible DNA changes (such as DNA composition or chromosome structure) which are retained in somatic cell division and passed on to the offspring of germ cells. Genotoxicity should not be confused with mutagenicity. All mutagens are genotoxic, but not all genotoxic substances are mutagenic.

[0005] In addition, traditional crosslinking methods typically involve using low molecular weight reactive organic molecules, occasionally dissolved in volatile organic solvents to reduce viscosity, to facilitate the accurate metering / addition of the crosslinking agent into the polymer composition to be crosslinked. Good miscibility of the crosslinking agent with the polymer composition is important for both the final properties (poor miscibility often leads to inefficient crosslinking) and the efficiency and convenience of the material user. However, the use of volatile organic solvents to reduce viscosity is not desirable as it increases the levels of volatile organic compounds (VOCs). In addition, the presence of solvents in the crosslinking agent composition reduces the formulating freedom of the formulator of the coating composition and is thus undesirable. Therefore, it would be beneficial to provide a polyaziridine crosslinking agent in water. At the same time, in terms of crosslinking efficiency and storage stability, it is necessary to maintain the crosslinking agent performance to maintain commercial viability in various polymer resins.

[0006] The object of the present invention is to provide a compound having at least two aziridine groups, which has reduced genotoxicity compared to trimethylolpropane tris(2-methyl-1-aziridinepropionate) and has good crosslinking efficiency. The compound having at least two aziridine groups is further referred to herein as a polyaziridine compound.

[0007] Surprisingly, it has been found that this object can be achieved by providing a polyaziridine compound having:

[0008] a) at least 2 of the following structural units (A):

[0009]

[0010] wherein,

[0011] R1 is H;

[0012] R2 and R4 are independently selected from H, a straight-chain group having 1 to 8 carbon atoms and optionally containing one or more heteroatoms, a branched or cyclic group having 3 to 8 carbon atoms and optionally containing one or more heteroatoms, phenyl, benzyl or pyridyl;

[0013] R3 is selected from a straight-chain group having 1 to 8 carbon atoms and optionally containing one or more heteroatoms, a branched or cyclic group having 3 to 8 carbon atoms and optionally containing one or more heteroatoms, phenyl, benzyl or pyridyl;

[0014] or R2 and R3 (when R2 is different from H) can be part of the same cyclic group having 3 to 8 carbon atoms;

[0015] R' and R" are independently H or an aliphatic hydrocarbon group having 1 to 12 carbon atoms; and

[0016] b) a molecular weight of 600 - 20,000 Daltons, where the molecular weight is determined by MALDI-TOF mass spectrometry according to the specification; and

[0017] The polyaziridine compound is obtained by reacting at least one polyisocyanate with compound (B), and the compound (B) has the following structural formula:

[0018]

[0019] where n is an integer equal to or greater than 2, Z is an n-valent group or a mixed group of n-valent groups, and D has the following structural formula:

[0020]

[0021] where the molar ratio of the D moiety to the isocyanate moiety on the polyisocyanate is 0.5 to 2.

[0022] Surprisingly, it has been found that compared with trimethylolpropane tris(2-methyl-1-aziridinepropionate), the polyaziridine compounds of the present invention have reduced genotoxicity and at the same time have good crosslinking efficiency. The polyaziridine compounds of the present invention only show weakly positive induced genotoxicity, or even they do not show genotoxicity, that is, they show a genotoxicity level comparable to the naturally occurring background. Preferably, these compounds can also be delivered and stored in water with a longer shelf life while maintaining sufficient reactivity towards carboxylic acid functional polymers.

[0023] Genotoxicity can be measured by an assay (Toxys, Leiden, Netherlands). The assay can be used for pure substances or for compositions that are direct products obtained in the preparation of the polyaziridine compounds of the present invention. Positive induced genotoxicity means that, in the absence or presence of a metabolic system of rat S9 liver extract, the induction levels of the biomarkers Bscl2-GFP and Rtkn-GFP are equal to or higher than 2-fold at at least one of 10%, 25%, and 50% cytotoxicity. Weakly positive induced genotoxicity means that, in the absence or presence of a metabolic system based on rat S9 liver extract (aroclor1254-induced rats, Moltox, Boone, NC, USA), the induction levels of the biomarkers Bscl2-GFP and Rtkn-GFP are higher than 1.5-fold and lower than 2-fold (but lower than 2-fold at 10, 25, and 50% cytotoxicity) at at least one of 10%, 25%, and 50% cytotoxicity. Genotoxicity equivalent to the naturally occurring background means that, in the absence or presence of a metabolic system based on rat S9 liver extract (aroclor1254-induced rats, Moltox, Boone, NC, USA), the induction levels of the biomarkers Bscl2-GFP and Rtkn-GFP are less than or equal to 1.5-fold at 10%, 25%, and 50% cytotoxicity. Substances that show induction levels less than or equal to 1.5-fold 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) are not genotoxic.

[0024] The crosslinking efficiency of the crosslinker can be evaluated by assessing the chemical resistance defined and determined as described below.

[0025] For all upper and / or lower boundaries of any range given herein, unless otherwise specifically indicated, the boundary values are included within the given range. Thus, when it is said from x to y, it means including x and y as well as all intermediate values.

[0026] In this specification, the term "coating composition" includes paints, coatings, varnishes, adhesives, and ink compositions, but is not limited to this listing. A self-crosslinkable coating composition is crosslinkable without the need to mix reactive materials that react with groups on the crosslinkable polymer prior to application, although such external triggers may still be used if desired. The term "aliphatic hydrocarbon group" refers to optionally branched alkyl, alkenyl, and alkynyl groups. The term "alicyclic hydrocarbon group" refers to cycloalkyl and cycloalkenyl groups optionally substituted with at least one aliphatic hydrocarbon group. The term "aromatic hydrocarbon group" refers to a benzene ring optionally substituted with 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.

[0027] Although the structural units (A) present in the polyaziridine compounds of the present invention may independently have different R2, R3, R4, R', and / or R", the structural units (A) present in the polyaziridine compounds are preferably the same as each other.

[0028] The polyaziridine compounds of the present invention are generally obtained in the form of a composition in which, in addition to the polyaziridine compound, there may be remaining starting materials, by-products, and / or solvents used for preparing the polyaziridine compound. This composition may contain only one polyaziridine compound according to the present invention, but may also contain more than one polyaziridine compound according to the present invention. When a mixture of polyisocyanates is used as the starting material, a mixture of polyaziridine compounds can be obtained, for example.

[0029] The polyaziridine compounds according to the present invention preferably include 2 - 50 structural units (A), more preferably include 2 - 10 structural units (A), and even more preferably include 2 - 4 structural units (A).

[0030] R1 is H. Preferably, R2 and R4 are independently selected from H or aliphatic hydrocarbon groups containing 1 to 4 carbon atoms. More preferably, R2 and R4 are independently selected from H or aliphatic hydrocarbon groups containing 1 to 2 carbon atoms.

[0031] Preferably, R3 is an aliphatic hydrocarbon group containing 1 to 4 carbon atoms, more preferably an aliphatic hydrocarbon group containing 1 to 2 carbon atoms.

[0032] In a preferred embodiment of the present invention, R2 is H, R3 is C2H5 and R4 is H. In another and more preferred embodiment of the present invention, R2 is H, R3 is CH3 and R4 is H or CH3. In another even more preferred embodiment of the present invention, R2 is H, R3 is CH3 and R4 is H.

[0033] Preferably, R' and R" are H.

[0034] The polyaziridine compound has a molecular weight of from 600 to 200,000 daltons. Preferably, the polyaziridine compound has a molecular weight of at least 800 daltons, more preferably at least 840 daltons, even more preferably at least 1000 daltons and preferably at most 10,000 daltons, more preferably at most 5000 daltons.

[0035] The polyaziridine compound of the present invention is obtained by reacting at least one polyisocyanate with a compound (B) having the following structural formula:

[0036]

[0037] wherein n is an integer equal to or greater than 2, Z is an n-valent group or a mixture of n-valent groups, and D has the following structural formula:

[0038]

[0039] wherein the molar ratio of the D moiety to the isocyanate moiety is from 0.5 to 2, and wherein R', R", R1, R2, R3 and R4 are as defined above.

[0040] Preferably, Z is an n-valent group composed of a set of atoms covalently linked in a linear or branched configuration, the set of atoms consisting of: i) carbon and hydrogen atoms, ii) carbon, hydrogen and oxygen atoms, iii) carbon, hydrogen and nitrogen atoms, or iv) carbon, hydrogen, oxygen and nitrogen atoms, or wherein Z is a mixture of these n-valent groups.

[0041] Preferably, n is 2 in and

[0042]

[0043] The reaction of the polyisocyanate with compound B can be carried out by bringing a suitable amount of the polyisocyanate into contact with compound B in the presence of, for example, a tin catalyst such as dibutyltin dilaurate or a bismuth catalyst such as bismuth neodecanoate in the temperature range of 0 to 110 °C, more preferably 20 to 110 °C, more preferably 40 °C to 95 °C, and even more preferably 60 to 85 °C. Solvents such as dimethylformamide DMF, acetone, and / or methyl ethyl ketone can be used. The polyisocyanate preferably contains on average 2 isocyanate groups. A mixture of polyisocyanates can also be used as a raw material. Polyisocyanates having aromatic reactivity, such as 4,4'-diphenylmethane-diisocyanate, 2,4-toluene-diisocyanate, and 2,6-toluene-diisocyanate and mixtures thereof, can be used. Preferred polyisocyanates are polyisocyanates having aliphatic reactivity. The term "polyisocyanate having aliphatic reactivity" is intended to mean 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, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, p-tetra-methylxylene diisocyanate (p-TMXDI), and its regioisomers.

[0044] Compound B can be prepared by the reaction of a polyepoxide with aziridine. The reaction is carried out at any temperature from 20 to 110 °C, more preferably from 50 to 95 °C, and most preferably from 70 to 90 °C, and its progress can be monitored by 1 1H-NMR spectroscopy. The condition for the reaction to proceed is that the epoxy group reacts; this is monitored and verified by 1 1H-NMR spectroscopy, in which the characteristics of the epoxy proton 1The H-NMR chemical shift (2.5–3 ppm) disappears. Preferably, the reaction is carried out without a solvent. However, if desired (e.g., to reduce viscosity), one or more solvents such as methanol, ethanol, toluene can be used during or after the reaction. If a solvent is used, the polyepoxide is usually first dissolved in the solvent (or solvent mixture) before adding the aziridine to the reaction mixture. The molar ratio of the aziridine group to the epoxy group of the polyepoxide is at least 1 and at most 8, more preferably at least 1 and at most 4, even more preferably at least 1.1 and at most 3 and most preferably at least 1.2 and at most 2.2. Once the reaction is complete, the residual aziridine is preferably distilled off under reduced pressure at a temperature of 60 to 90 °C, more preferably 65 to 80 °C and, for example, 20 to 50 mbar, preferably 30 to 45 mbar. Preferably, once the reaction is complete, the residual aziridine is distilled off at 70 °C under a reduced pressure of 20 to 50 mbar, more preferably at 70 °C under a reduced pressure of 30 to 45 mbar. Subsequently, the step of further distillation to remove any unreacted aziridine and any other volatiles is carried out at 25 to 40 °C at 2 to 4 mbar until no aziridine is detected by 1 H-NMR spectroscopy. The addition of an additional solvent to the reaction mixture before or during distillation is usually useful to facilitate the removal of the excess aziridine. If desired, a base can be used during the reaction to reduce possible acid sources. Bases include organic bases such as tertiary amines or inorganic bases such as sodium carbonate or potassium carbonate or, for example, calcium hydroxide. The inorganic base can be filtered off after the reaction is complete.

[0045] Non-limiting examples of polyepoxides for the preparation of compound B are bisphenol AP diglycidyl ether, bisphenol AF diglycidyl ether, bisphenol B diglycidyl ether, bisphenol BP diglycidyl ether, bisphenol C diglycidyl ether, bisphenol C2 diglycidyl ether, bisphenol E diglycidyl ether, bisphenol F diglycidyl ether, bisphenol G diglycidyl ether, bisphenol M diglycidyl ether, bisphenol S diglycidyl ether, bisphenol P diglycidyl ether, bisphenol PH diglycidyl ether, bisphenol TMC diglycidyl ether, bisphenol Z diglycidyl ether, dinitrobisphenol A diglycidyl ether, tetrabromobisphenol A diglycidyl ether, bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, neopentyl glycol diglycidyl ether, butanediol diglycidyl ether, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polypropylene glycol diglycidyl ether, poly(ethylene glycol) diglycidyl ether and any mixture thereof.

[0046] Preferred polyepoxides for the preparation of compound B are bisphenol A diglycidyl ether (CAS 1675-54-3), hydrogenated bisphenol A diglycidyl ether (CAS 30583-72-3), neopentyl glycol diglycidyl ether (CAS 17557-23-2), butanediol diglycidyl ether (CAS 2425-79-8), ethylene glycol diglycidyl ether (CAS 2224-15-9), 1,6-hexanediol diglycidyl ether (CAS 16096-31-4), polypropylene glycol diglycidyl ether (CAS 26142-30-3), poly(ethylene glycol) diglycidyl ether (CAS 72207-80-8) and any mixtures thereof.

[0047] Preferred aziridine compounds for the preparation of compound B are propyleneimine and ethyl aziridine. The synthesis of ethyl aziridine is described, for example, in EP0227461B1. The most preferred aziridine compound for the preparation of compound B is propyleneimine.

[0048] Polyaziridine compounds can also be obtained by reacting at least compound B with polyisocyanates and polyols and / or polyamines as defined above. Polyaziridine compounds can also be obtained by reacting polyisocyanates as defined above with polyols and / or polyamines and reacting the compounds thus obtained with compound B. Polyaziridine compounds can also be obtained by reacting compound B with polyisocyanates and reacting the compounds thus obtained with polyols and / or polyamines. Polyaziridine compounds can also be obtained by reacting at least one compound B with isocyanate-terminated polyurethanes and / or polyurethane ureas. (Isocyanate-terminated) polyurethanes (ureas) are obtained by reacting at least one polyol and / or polyamine with at least one polyisocyanate. Preferred polyisocyanates are as described above.

[0049] Preferably, the polyaziridine compounds are terminated with any one of the following: monofunctional alcohols or amines. Non-limiting examples can be ethanol, butanol, isopropanol, propanol, cyclohexanol, n-methylbutylamine, or more preferably adducts of non-OH functional monoepoxides with aziridines according to structure E:

[0050]

[0051] wherein R1 is H,

[0052] R2 and R4 are independently selected from H or aliphatic hydrocarbon groups containing 1 to 4 carbon atoms,

[0053] R3 is an aliphatic hydrocarbon group containing 1 to 4 carbon atoms,

[0054] m is an integer from 1 to 6,

[0055] R' and R" according to (1) or (2):

[0056] (1) R’ = H or an aliphatic hydrocarbon group having 1 to 14 carbon atoms, and

[0057] R” = H, an aliphatic hydrocarbon group having 1 - 14 carbon atoms, an alicyclic hydrocarbon group having 5 - 12 carbon atoms, an aromatic hydrocarbon group having 6 - 12 carbon atoms, CH2 - O - (C = O) - R”’, CH2 - O - R”” or CH2 - (OCR””’HCR””’H) n -OR”””, where R”’ is an aliphatic hydrocarbon group having 1 to 14 carbon atoms, R”” is an aliphatic hydrocarbon group having 1 to 14 carbon atoms or an aromatic hydrocarbon group having 6 to 12 carbon atoms, n is from 1 to 35, R””’ is independently H or an aliphatic hydrocarbon group having 1 to 14 carbon atoms, and R””” is an aliphatic hydrocarbon group having 1 to 4 carbon atoms,

[0058] (2) R’ and R” together form a saturated alicyclic hydrocarbon group having 5 to 8 carbon atoms.

[0059] 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), cresol glycidyl ether (ortho or para), and glycidyl neodecanoate. The non - OH functional monocyclic epoxides are preferably selected from 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 epoxides are selected from 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.

[0060] Alternatively, the polyaziridine compound is capped with a monofunctional isocyanate.

[0061] The polyol is preferably selected from polyether polyols, polyester polyols, polysulfide polyols, polycarbonate polyols, polyacetal polyols, polyvinyl polyols, polysiloxane polyols and any mixtures thereof. More preferably, the polyol is selected from 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 , polyoxypropylene (-O-CHCH3-CH2-) x or (-O-CH2-CH2-CH2-)x group and / or polytetrahydrofuran (-O-CH2-CH2-CH2-CH2) x group in the polyaziridine compound is preferably at least 6% by weight, more preferably at least 10% by weight, preferably less than 45% by weight, more preferably less than 40% by weight and most preferably less than 35% by weight based on the total weight of the polyaziridine compound. x represents the average molar number of addition of oxyethylene, oxypropylene and tetrahydrofuran respectively, and x is preferably an integer from 5 to 20. The polyamine is preferably selected from 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 polyether polyamines and any mixtures thereof. Preferred polyether polyamines are D-230, D-400 and D-2000. Using polyol is superior to using polyamine.

[0062] Optionally, the polyaziridine compound contains ionic groups. For example, these can be introduced using the structural units given in the following non-limiting examples: 3-(cyclohexylamino)-1-propanesulfonic acid (CAPS, CAS No. 1135-40-6), 2-(cyclohexylamino)ethanesulfonic acid (CHES, CAS No. 103-47-9) and taurine (CAS No. 107-35-7).

[0063] Examples of preferred polyaziridine compounds of the present invention are shown below:

[0064]

[0065] The aziridinyl group has the following structural formula:

[0066]

[0067] Another aspect of the present invention is a crosslinker composition which comprises at least one polyaziridine compound as defined above and further comprises at least one additional component, said at least one additional component being, for example, a remaining starting material, a by-product and / or a solvent used for preparing the polyaziridine compound of the present invention. The crosslinker composition may comprise only one polyaziridine compound according to the present invention, but may also comprise more than one polyaziridine compound according to the present invention. After obtaining the polyaziridine compound of the present invention, the polyaziridine compound of the present invention can be separated, and the reaction product does not need to be further purified or the solvent used for preparing the polyaziridine can be removed from the composition obtained from the preparation of the polyaziridine compound of the present invention. With respect to the total amount of the composition, the amount of the polyaziridine compound of the present invention in the crosslinker composition is generally at least 10% by weight, usually at least 15% by weight, and most usually at least 25% by weight. With respect to the total amount of the crosslinker composition, the amount of the polyaziridine compound of the present invention in the crosslinker composition is preferably at least 60% by weight, more preferably at least 80% by weight, and most preferably at least 99% by weight. With respect to the total weight of the crosslinker composition, the amount of aziridinyl-functional molecules having a molecular weight of less than 580 daltons present in the crosslinker composition according to the present invention is less than 5% by weight, preferably less than 2% by weight, more preferably less than 1% by weight, more preferably less than 0.5% by weight, and more preferably less than 0.1% by weight, wherein the molecular weight is determined using LC-MS as described in the experimental section below.

[0068] Another aspect of the present invention is a two-component coating system which comprises a first component and a second component, said second component being different from the first component and being separate from the first component, wherein the first component comprises a carboxylic acid-functional polymer which is dissolved and / or dispersed, preferably dispersed, in an aqueous medium, and wherein the second component comprises a polyaziridine compound as defined above or wherein the second component is a crosslinker composition as defined above, 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 the crosslinker is mixed with the aqueous composition of the polymer to be crosslinked.

[0069] The carboxylic acid functional polymer contains carboxylic acid groups and / or carboxylate groups, and preferably does 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., 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 part of the base is a volatile base. Preferably, at least a part of the carboxylic acid groups present in the carboxylic acid functional polymer to be crosslinked is deprotonated 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 and tertiary amines were described above. The preferred base is a tertiary amine. Preferred tertiary amines are as described above. Most preferred is triethylamine.

[0070] Non-limiting examples of crosslinkable carboxylic acid functional polymers are vinyl polymers such as styrene-acrylics, (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, where at least one of the two polymers has a carboxylic acid functional group. The carboxylic acid functional polymer is preferably selected from polyesters, polycarbonates, polyamides, vinyl polymers, polyacrylates, polymethacrylates, poly(acrylate-co-methacrylate), polyurethanes, poly(urethane-co-acrylate), poly(urethane-co-methacrylate), poly(urethane-co-acrylate-co-methacrylate), polyureas, and mixtures thereof. In one embodiment of the present invention, the preferred crosslinkable carboxylic acid functional polymers are selected from vinyl polymers, polyacrylates, polymethacrylates, poly(acrylate-co-methacrylate), and mixtures thereof. Preferably, the vinyl polymer refers to a polymer containing reaction residues of styrene and acrylate and / or methacrylate. In another embodiment, the carboxylic acid functional polymer is selected from polyurethanes, poly(urethane-co-acrylate), poly(urethane-co-methacrylate), poly(urethane-co-acrylate-co-methacrylate), polyureas, and mixtures thereof. The present invention also relates to a coating composition obtained by mixing the first and second components of a two-component coating system immediately before applying the coating composition, where the coating composition contains aziridine groups Q and carboxylic acid groups, and the amounts of aziridine groups Q and carboxylic acid groups are such that the stoichiometric amount (SA) of aziridine group Q on the carboxylic acid group is preferably from 0.1 to 2.0, more preferably from 0.2 to 1.5, further preferably from 0.25 to 0.95, and most preferably from 0.3 to 0.8. The pH of the coating composition is preferably at least 7.5, more preferably at least 8, more preferably at least 8.5, and even more preferably at least 9.

[0071] Another aspect of the invention is an aqueous dispersion having a pH of from 8 to 14 and comprising particles X containing a polyaziridine compound as defined above. It has surprisingly been found that the aqueous dispersions of the invention have an extended storage stability while still having good crosslinking efficiency in aqueous dispersions of carboxylic acid functional polymers. The aqueous dispersions of the invention show an effective reaction with carboxylic acid groups at room temperature. The aqueous dispersions of the invention are also easy to use, their aqueous nature giving good compatibility with aqueous binders and thus good mixing and low fouling during formulation. In addition, these aqueous dispersions generally have a low viscosity, which makes them easy to handle and accurately meter. The extended storage stability in water, combined with more favorable hazard properties, enables paint manufacturers and applicators to store and use the crosslinker composition easily and safely in a two-component 2K paint system, where the binder and the crosslinker, diluted in an aqueous medium, are only mixed prior to application.

[0072] pH of the aqueous dispersion

[0073] The pH of the aqueous dispersion is at least 8. To further extend the shelf life of the aqueous dispersions of the invention, it is advantageous for the pH to be at least 8.5, preferably at least 9, more preferably at least 9.5. The pH of the aqueous dispersion is at most 14, preferably at most 13, more preferably at most 12, even more preferably at most 11.5, as this allows the amount of base present in the aqueous dispersions of the invention to be reduced while still maintaining a sufficiently long life of the aqueous dispersion. Most preferably, the pH of the aqueous dispersion is in the range from 9.5 to 11.5.

[0074] The aqueous dispersion preferably contains ammonia, secondary amines, tertiary amines, LiOH, NaOH and / or KOH to adjust the pH to the desired value. Preferred amines are ammonia, secondary amines and / or tertiary amines. Examples of such secondary amines are, but are not limited to, diisopropylamine, di-sec-butylamine and di-tert-butylamine. More preferred amines are tertiary amines. Examples of such tertiary amines are, but are 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.

[0075] Based on the total weight of the aqueous dispersion, the amount of water in the aqueous dispersion is 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. Based on the total weight of the aqueous dispersion, the amount of water in the aqueous dispersion is preferably at most 95% by weight, more preferably at most 90% by weight, more preferably at most 85% by weight, more preferably at most 80% by weight, further preferably at most 70% by weight, even more preferably at most 60% by weight.

[0076] Based on the total weight of the aqueous dispersion, the amount of the polyaziridine compound as defined herein present in the aqueous dispersion is 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. Based on the total weight of the aqueous dispersion, the amount of the polyaziridine compound as defined herein present in the aqueous dispersion is 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.

[0077] Preferably at least 50% by weight, more preferably at least 80% by weight, even more preferably at least 95% by weight and most preferably at least 99% by weight of the polyaziridine compound as defined herein is present in the aqueous dispersion in a dispersed form. Accordingly, the aqueous dispersion of the present invention comprises particles of the polyaziridine compound as defined herein. The particles preferably have an average hydrodynamic diameter based on scattering intensity of 30 to 650 nm, more preferably 50 to 500 nm, even more preferably 70 to 350 nm, even more preferably 120 to 275 nm. The average hydrodynamic diameter of the particles based on scattering intensity can be controlled in a variety of ways. For example, the average hydrodynamic diameter of the particles based on scattering intensity can be controlled during the preparation of the aqueous dispersion of the present invention 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 as the shear stress increases. Exemplary dispersants include, but are not limited to, ATLAS TM G-5000, ATLAS TM G-5002L-LQ, Maxemul TM 7101.

[0078] 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, 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, more preferably at most 55% by weight. The solids content of the aqueous dispersion is most preferably in the range of 35 - 55% by weight.

[0079] The polyaziridine compound as defined above is generally obtained in a composition, in which, in addition to the polyaziridine compound, there may be present remaining starting materials, by-products and / or solvents used for preparing 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. When a mixture of polyisocyanates is used as the starting material, a mixture of polyaziridine compounds can be obtained, for example. 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 having a desired pH value to obtain an aqueous dispersion having a 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 used to assist in the dispersion of the polyaziridine compound.

[0080] The aqueous dispersion may further contain an organic solvent, the amount of which is 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. The organic solvent can be optionally added before, during and / or after the synthesis of the polyaziridine. 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, dimethyl sulfoxide, n-formylmorpholine, dimethylacetamide, dimethylformamide and ketones. Preferred solvents are diols, ethers, alcohols, cyclic carbonates and ketones.

[0081] 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 the dispersion and colloidal stabilization. In the present invention, the dispersant is preferably a substance non-covalently linked to the polyaziridine compound and / or the dispersant is a separate molecular component having surface activity. Examples of substances non-covalently linked to the polyaziridine compound are amphiphilic compounds containing carbamate and / or urea, such as HEUR thickeners.

[0082] More preferably, the dispersant is at least one separate molecular component having surface activity. Preferred separate molecular components having surface activity are:

[0083] (i) A polyaziridine compound as defined above, which contains functional groups such as sulfonate, sulfate, phosphate and / or phosphonate functional groups, preferably sulfonate and / or phosphonate groups, more preferably sulfonate groups, and / or

[0084] (ii) 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, preferably at most 1000000 daltons, more preferably at most 100000 daltons, at most 10000 daltons, as measured by MALDI-ToF-MS as described below.

[0085] More preferred separate molecular components having surface activity are polymers having the following molecular weights: 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. 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 molecular component dispersants having surface activity are Atlas TM G-5002L-LQ available from Croda, Maxemul TM 7101 available from Croda and / or P84 available from BASF. Based on the total weight of the aqueous dispersion, the amount of the separate molecular component having surface activity 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.

[0086] The polyaziridine compound as defined in i) contains functional groups such as sulfonate, sulfate, phosphate and / or phosphonate functional groups, preferably contains a sulfonate functional group, and is preferably obtained by reacting partial isocyanate groups of the polyisocyanate used for preparing the polyaziridine compound with a hydroxyl- or amine-functional ionic structural unit (preferably neutralized with an inorganic base). Examples of the hydroxyl- or amine-functional ionic structural unit include 2-(cyclohexylamino)ethanesulfonic acid, 3-(cyclohexylamino)propanesulfonic acid, methyltaurine, taurine, DS-3404. Preferably, a sulfonate is used as the hydroxyl- or amine-functional ionic structural unit.

[0087] The crosslinking efficiency of the crosslinking agent can be evaluated by assessing the chemical resistance defined and determined as described below.

[0088] The storage stability of the aqueous dispersion of the present invention can be tested by storing the aqueous dispersion, especially at an elevated temperature, for example, storing at 50 °C, and evaluating the change in viscosity of the stored aqueous dispersion (defined and determined as described below) and / or evaluating the change in the chemical resistance of the stored aqueous dispersion defined and determined as described below, especially the change in ethanol resistance.

[0089] The aqueous dispersion of the present invention preferably has a storage stability of at least 1 week, preferably at least 2 weeks, more preferably at least 3 weeks, and even more preferably at least 4 weeks at 50°C. Stable storage at 50°C for at least x weeks means that after the dispersion is stored at 50°C for x weeks, (i) the final viscosity of the aqueous dispersion is at most 50 times higher than the initial viscosity, preferably at most 45 times higher than the initial viscosity, more preferably at most 40 times higher than the initial viscosity, more preferably at most 35 times higher than the initial viscosity, more preferably at most 30 times higher than the initial viscosity, more preferably at most 25 times higher than the initial viscosity, more preferably at most 20 times higher than the initial viscosity, more preferably at most 15 times higher than the initial viscosity, more preferably at most 10 times higher than the initial viscosity, and most preferably at most 5 times higher than the initial viscosity, and / or (ii) the chemical resistance of the aqueous dispersion as defined and measured below is reduced by at most 3 points, preferably reduced by at most 2 points, and even more preferably reduced by at most 1 point. Preferably, stable storage at 50°C for at least x weeks means that after the dispersion is stored at 50°C for x weeks, (i) the final viscosity of the aqueous dispersion is at most 50 times higher than the initial viscosity, preferably at most 45 times higher than the initial viscosity, more preferably at most 40 times higher than the initial viscosity, more preferably at most 35 times higher than the initial viscosity, more preferably at most 30 times higher than the initial viscosity, more preferably at most 25 times higher than the initial viscosity, more preferably at most 20 times higher than the initial viscosity, more preferably at most 15 times higher than the initial viscosity, more preferably at most 10 times higher than the initial viscosity, and most preferably at most 5 times higher than the initial viscosity, and (ii) the chemical resistance of the aqueous dispersion as defined and measured below is reduced by at most 3 points, preferably reduced by at most 2 points, and more preferably reduced by at most 1 point.

[0090] The "initial viscosity" of the aqueous dispersion refers to the viscosity of the aqueous dispersion determined at the time of its preparation and before storing the aqueous dispersion at 50°C (defined and measured as described below). The "final viscosity" of the dispersion refers to the viscosity of the aqueous dispersion measured after storing the aqueous dispersion at 50°C for x weeks (defined and measured as described below).

[0091] The aqueous dispersion of the present invention can be obtained by dispersing a polyaziridine compound in water and adjusting the pH of the aqueous dispersion to the desired value or by dispersing the polyaziridine compound in a mixture of water and at least one base, the pH value of the mixture being such that an aqueous dispersion with the desired pH value is obtained. 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 used to assist in the dispersion of the polyaziridine compound.

[0092] The present invention also relates to a method for preparing an aqueous dispersion according to the present invention, wherein the method comprises dispersing the 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 the polyaziridine compound as defined herein into a mixture of water and at least one base, the mixture having a pH value such that an aqueous dispersion having the desired pH value is obtained.

[0093] 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 an aqueous dispersion according to the present invention preferably comprises:

[0094] A) Optionally, but preferably, mixing the polyaziridine compound as defined above in an organic solvent,

[0095] B) Mixing the polyaziridine compound as defined above or the solution obtained in step A) with the above-mentioned dispersant to obtain a composition comprising the polyaziridine compound and the dispersant,

[0096] C) Mixing water and a base or an alkaline aqueous medium into the composition comprising the polyaziridine compound and the dispersant to obtain a dispersion,

[0097] 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 the aqueous dispersion according to the present invention.

[0098] Step C) is preferably carried out using a high-shear dispersion device.

[0099] The present invention further relates to the use of an aqueous dispersion according to the present invention for crosslinking a carboxylic acid functional polymer dissolved and / or dispersed, preferably dispersed, in water, wherein the amounts of aziridinyl and carboxylic acid groups are selected such that the stoichiometric amount (SA) of aziridinyl groups 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, which 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 sum of the deprotonated and protonated carboxylic acid groups present in the polymer to be crosslinked. The polymer to be crosslinked preferably contains at least partially base-neutralized carboxylic acid groups. Preferably, at least part of the base is a volatile base. Preferably, at least a part of the carboxylic acid groups present in the carboxylic acid functional polymer to be crosslinked is deprotonated to obtain carboxylate groups. The 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 and tertiary amines were described above. The preferred base is a tertiary amine. Preferred tertiary amines are as described above. Most preferred is triethylamine.

[0100] The present invention also relates to an aqueous coating composition comprising a polyaziridine compound and a carboxylic acid functional polymer, wherein the composition is an aqueous dispersion having a pH in the range of 8 to 14 and comprises at least two dispersed phases having different compositions, wherein the first dispersed phase comprises particles X, wherein the particles X comprise the polyaziridine compound as defined herein, and the second dispersed phase comprises particles Y, wherein the particles Y comprise a carboxylic acid functional polymer crosslinkable with the polyaziridine compound as defined herein, provided that the particles X do not contain a carboxylic acid functional polymer nor any other compound crosslinkable with the polyaziridine compound as defined herein, and the particles Y do not contain a polyaziridine compound nor any other compound crosslinkable with the carboxylic acid functional groups of the carboxylic acid functional polymer. The coating composition of the present invention may also comprise particles containing a polyaziridine compound and a carboxylic acid functional polymer. Such particles may result from the coagulation of particles X and particles Y.

[0101] The aqueous coating composition of the present invention is preferably a self-crosslinkable coating composition. A self-crosslinkable coating composition is crosslinkable without the addition of a compound that reacts with the groups on the crosslinkable polymer and / or without heating, although such external triggers can still be used if desired. It has surprisingly been found that the aqueous coating composition of the present invention has an extended storage stability while also giving good crosslinking efficiency when the aqueous coating composition dries. The composition according to the present invention exhibits an effective crosslinking reaction at room temperature. The composition of the present invention is also easy to use, providing a single-can solution that is convenient for storage, handling, and application. Thus, the aqueous coating composition according to the present invention can provide a self-crosslinkable composition that can be applied as a one-component coating system without the need to mix reactive materials prior to application as in a two-component coating system. The stability of the coating composition of the present invention and the improved properties of the corresponding dry film, combined with favorable hazard characteristics, result in a high-performance 1K system. Such a 1K system, where crosslinking is only triggered upon coating application, is very easy to use for a range of coating applicators as it reduces the handling of hazardous materials and provides good coating properties.

[0102] The pH of the coating composition is at least 8. To further extend the shelf life of the coating composition of the present invention, the pH is preferably at least 8.5, more preferably at least 9, and even more preferably at least 9.5. The pH of the coating composition is at most 14, preferably at most 13, more preferably at most 12, even more preferably at most 11.5, and even more preferably at most 11, as this allows for a reduction in the amount of base present in the coating composition while maintaining the shelf life of the coating composition for a sufficient length of time. Most preferably, the pH of the coating composition is in the range of 9.5 to 11.5.

[0103] The coating composition 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 alkylamines include but are not limited to diisopropylamine, di-sec-butylamine, and di-tert-butylamine. More preferred amines are tertiary amines. Examples of such tertiary amines include but are 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.

[0104] Based on the total weight of the coating, the amount of water in the coating composition is 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. Based on the total weight of the coating composition, the amount of water in the coating composition is preferably at most 90% by weight, 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.

[0105] Based on the total solids content of the coating composition, the amount of the polyaziridine compound as defined herein present in the coating composition is preferably at least 0.5% by weight, more preferably at least 1% by weight, more preferably at least 1.5% by weight, more preferably at least 2% by weight, even more preferably at least 3% by weight, even more preferably at least 4% by weight, even more preferably at least 5% by weight, even more preferably at least 7% by weight. Based on the total solids content of the coating composition, the amount of the polyaziridine compound as defined herein present in the coating composition is preferably at most 50% by weight, preferably at most 30% by weight, more preferably at most 20% by weight, more preferably at most 15% by weight, even more preferably at most 12% by weight.

[0106] The solids content of the coating composition of the present invention is preferably in the range of 5 to 65% by weight. The solids content of the coating composition of the present invention is more preferably at least 10% by weight, even more preferably at least 20% by weight, even more preferably at least 25% by weight, even more preferably at least 35% by weight, and at most 55% by weight, even more preferably at most 50% by weight and even more preferably at most 45% by weight.

[0107] At least 50% by weight, preferably at least 85% by weight, more preferably at least 95% by weight, even more preferably at least 99% by weight of the polyaziridine compound as defined herein is present in the coating composition in the form of a dispersion. Accordingly, the coating composition of the present invention contains particles X of the polyaziridine compound as defined herein. The particles X preferably have an average hydrodynamic diameter based on scattering intensity of 30 to 500 nm, more preferably 50 to 350 nm, even more preferably 110 to 275 nm. The coating composition further contains particles containing a carboxylic acid functional polymer, which can crosslink with the polyaziridine compound as defined herein. The particles containing a carboxylic acid functional polymer preferably have an average hydrodynamic diameter based on scattering intensity of 30 to 30000 nm, more preferably 40 to 10000 nm, even more preferably 40 to 3000 nm, even more preferably 40 to 500 nm, even more preferably 60 to 260 nm.

[0108] The carboxylic acid functional polymer is preferably as defined above.

[0109] The acid value of the carboxylic acid functional polymer is preferably 2 - 135 mg KOH / g of the carboxylic acid functional polymer, more preferably 3 - 70 mg KOH / g of the carboxylic acid functional polymer, even more preferably 10 - 50 mg KOH / g of the carboxylic acid functional polymer, and even more preferably 15 - 50 mg KOH / g of the carboxylic acid functional polymer. In cases where a high crosslink density is required, the acid value of the carboxylic acid functional polymer is preferably 50 - 200 mg KOH / g of the 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 the carboxylic acid component contained in the carboxylic acid functional polymer divided by the number of grams of the total amount of components contained in the carboxylic acid functional polymer) * 56.1 * 1000) and is expressed as mg KOH / g of the carboxylic acid functional polymer. The acid value of the carboxylic acid functional polymer can thus 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 correctly, the acid value is determined by ASTM D1639 - 90(1996)e1.

[0110] The ratio of the number average molecular weight Mn of the carboxylic acid functional polymer to the acid value of the carboxylic acid functional polymer is preferably at least 150, more preferably at least 300, further 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 n is determined by size exclusion chromatography with NMP - MEK.

[0111] The coating composition comprises at least one carboxylic acid functional polymer. The coating composition may comprise a blend of different carboxylic acid functional polymers. 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 sum of the deprotonated and protonated carboxylic acid groups present in the polymer to be crosslinked. The polymer to be crosslinked preferably comprises at least partially base - neutralized carboxylate groups. Preferably, at least part of the base is a volatile base. Preferably, at least a part of the carboxylic acid groups present in the carboxylic acid functional polymer to be crosslinked is deprotonated to obtain carboxylate groups. The 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 and tertiary amines were described above. The preferred base is a tertiary amine. Preferred tertiary amines are as described above. Most preferred is triethylamine.

[0112] Based on the total weight of the aqueous dispersion, the coating composition of the present invention preferably contains at least 3% by weight, preferably at least 5% by weight, more preferably at least 10% by weight, more preferably at least 20% by weight, even more preferably at least 30% by weight, even more preferably at least 40% by weight, and even more preferably at least 50% by weight of the carboxylic acid functional polymer. Based on the total weight of the aqueous dispersion, the coating composition of the present invention preferably contains at most 60% by weight, preferably at most 55% by weight of the carboxylic acid functional polymer.

[0113] Preferably, the amounts of the aziridinyl group and the carboxylic acid group are selected such that the stoichiometric amount (SA) of the aziridinyl group on the carboxylic acid group 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.

[0114] The coating composition of the present invention can be obtained by (i) dispersing a 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 pH value of the mixture being such that an aqueous dispersion having the desired pH value is obtained, and (ii) mixing the aqueous dispersion obtained in step (i) with an aqueous dispersion of a carboxylic acid functional polymer. 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 used to assist in the dispersion of the polyaziridine compound.

[0115] Alternatively, the polyaziridine compound can be self-dispersing, in which case it can be added directly to the carboxylic acid functional polymer to form discrete particles. The polyaziridine can be made self-dispersing by introducing ionic groups, polar nonionic groups such as polyalkylene oxides, or any combination thereof.

[0116] The coating composition can further contain an organic solvent, the amount of the organic solvent being 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 coating composition. The organic solvent can optionally be added before, during, and / or after the synthesis of the polyaziridine. Organic solvents can be used to assist in the dispersion of 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 glycols, ethers, alcohols, cyclic carbonates, pyrrolidones, dimethyl sulfoxide, n-formylmorpholine, amides, and ketones. Preferred solvents are glycols (including glycol ethers), ethers, alcohols, cyclic carbonates, and ketones.

[0117] Preferably, the dispersion of the polyaziridine compound is carried out in the presence of a dispersant. Accordingly, the coating composition 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 the colloidal stabilization. In the present invention, the dispersant is preferably a substance non-covalently linked to the polyaziridine compound and / or the dispersant is a surfactant-containing separate molecular component. Examples of substances non-covalently linked to the polyaziridine compound are amphiphilic compounds containing carbamate and / or urea, such as HEUR thickeners.

[0118] More preferably, the dispersant is at least one separate surfactant-containing molecular component. Preferred dispersants are as described above.

[0119] The present invention also relates to a method for preparing a coating composition according to the present invention, wherein the method comprises: (i) dispersing the polyaziridine compound as defined above in water to obtain an aqueous dispersion and adjusting the pH of the aqueous dispersion to a desired value, or the method comprises dispersing the polyaziridine compound as defined above in a mixture of water and at least one base, the pH value of the mixture being such that an aqueous dispersion with a desired pH value is obtained; and (ii) mixing the aqueous dispersion obtained in step (i) with an aqueous dispersion of a carboxylic acid functional polymer. Preferably, the method comprises mixing an alkaline aqueous medium into the polyaziridine compound as defined above, thereby selecting the pH of the alkaline aqueous medium to obtain a coating composition with a desired pH value.

[0120] The method for preparing the coating composition of the present invention preferably comprises:

[0121] A) Optionally, but preferably, mixing the polyaziridine compound as defined above in an organic solvent,

[0122] B) Mixing the polyaziridine compound as defined above or the solution obtained in step A) with a dispersant to obtain a composition comprising the polyaziridine compound and the dispersant,

[0123] C) Mixing water and a base or mixing an alkaline aqueous medium into the composition comprising the polyaziridine compound and the dispersant to obtain a dispersion,

[0124] 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 of the polyaziridine compound, and

[0125] E) Mixing the aqueous dispersion of the polyaziridine compound obtained in step D) with an aqueous dispersion of a carboxylic acid functional polymer to obtain the coating composition of the present invention.

[0126] Step C) is preferably carried out using a high-shear dispersion device.

[0127] The present invention also relates to a substrate having a coating, which is obtained by (i) applying the coating composition as described above to the substrate and (ii) drying the coating composition by evaporation of the volatile matter. The drying of the coating composition is preferably carried out at a temperature below 160 °C, more preferably at a temperature below 90 °C, still more preferably at a temperature below 50 °C, and most preferably at ambient temperature. The coating composition of the present invention can be applied to any kind of substrate, such as wood, leather, concrete, textiles, plastics, vinyl flooring, glass, metal, ceramics, paper, wood-plastic composites, glass fiber reinforcements. The thickness of the dry coating on the substrate is preferably 1 - 200 μm, more preferably 5 - 150 μm, and most preferably 15 - 90 μm. In the case where the coating composition is an ink composition, the thickness of the dry ink is preferably 0.005 to 35 μm, more preferably 0.05 to 25 μm, and most preferably 4 to 15 μm.

[0128] The present invention is further defined by a set of exemplary embodiments listed below. Any one of the embodiments, aspects, and preferred features or ranges disclosed in this application can be combined in any combination, unless otherwise stated herein or if it is clearly technically infeasible for a person skilled in the art.

[0129] [1] A polyaziridine compound having:

[0130] a) at least 2 of the following structural units (A):

[0131]

[0132] wherein

[0133] R1 is H;

[0134] R2 and R4 are independently selected from H, a straight-chain group having 1 to 8 carbon atoms and optionally containing one or more heteroatoms, a branched or cyclic group having 3 to 8 carbon atoms and optionally containing one or more heteroatoms, phenyl, benzyl, or pyridyl;

[0135] R3 is selected from a straight-chain group having 1 to 8 carbon atoms and optionally containing one or more heteroatoms, a branched or cyclic group having 3 to 8 carbon atoms and optionally containing one or more heteroatoms, phenyl, benzyl, or pyridyl;

[0136] or R2 and R3 (when R2 is different from H) can be part of the same cyclic group having 3 to 8 carbon atoms;

[0137] R’ and R” are independently H or an aliphatic hydrocarbon group having 1 to 12 carbon atoms; and

[0138] b) a molecular weight of at least 600 Daltons and at most 20,000 Daltons, wherein the molecular weight is determined by MALDI-TOF mass spectrometry according to the specification; and

[0139] The polyaziridine compound is obtained by reacting at least one polyisocyanate with a compound (B) having the following structural formula:

[0140]

[0141] wherein n is an integer equal to or greater than 2, Z is an n-valent group or a mixture of n-valent groups, and D has the following structural formula:

[0142]

[0143] wherein the molar ratio of the D moiety to the isocyanate moiety on the polyisocyanate is 0.5 to 2.

[0144] [2] The polyaziridine compound according to embodiment [1], wherein R2 and R4 are independently selected from H or an aliphatic hydrocarbon group containing 1 to 2 carbon atoms, and R3 is an aliphatic hydrocarbon group containing 1 to 4 carbon atoms.

[0145] [3] The polyaziridine compound according to any one of the preceding embodiments, wherein R2 is H, R3 is CH3 and R4 is H.

[0146] [4] The polyaziridine compound according to any one of the preceding embodiments, wherein R' and R" are H.

[0147] [5] The polyaziridine compound according to any one of the preceding embodiments, wherein the polyaziridine compound contains 2 to 10 structural units (A).

[0148] [6] The polyaziridine compound according to any one of the preceding embodiments, wherein the polyaziridine compound contains 2 to 4 structural units (A).

[0149] [7] The polyaziridine compound according to any one of the preceding embodiments, characterized in that the polyaziridine compound has a molecular weight of 600 to 200,000 Daltons, more preferably the polyaziridine compound has a molecular weight of at least 800 Daltons, even more preferably at least 840 Daltons, even more preferably at least 1000 Daltons, and preferably at most 20,000 Daltons, more preferably at most 10,000 Daltons, more preferably at most 5000 Daltons, wherein the molecular weight is determined by MALDI-TOF mass spectrometry according to the specification.

[0150] [8]The polyaziridine compound according to any one of the foregoing embodiments, wherein the polyaziridine compound is obtained by reacting at least one polyisocyanate with a compound (B) having the following structural formula:

[0151]

[0152] wherein n is equal to or greater than 2, Z is an n-valent group or a mixture of n-valent groups, and D has the following structural formula:

[0153]

[0154] wherein the molar ratio of the D moiety to the isocyanate moiety on the polyisocyanate is from 0.5 to 2, and wherein R’, R”, R1, R2, R3 and R4 are as defined in any of the foregoing embodiments.

[0155] [9]The polyaziridine compound according to embodiment [8], wherein Z is an n-valent group composed of a set of atoms covalently linked in a straight-chain or branched configuration, the composition of the set of atoms being i) carbon and hydrogen atoms, ii) carbon, hydrogen and oxygen atoms, iii) carbon, hydrogen and nitrogen atoms, or iv) carbon, hydrogen, oxygen and nitrogen atoms, or wherein Z is a mixture of these n-valent groups.

[0156]

[10] The polyaziridine compound as described in [8] or [9], wherein the polyisocyanate is a diisocyanate.

[0157]

[11] The polyaziridine compound according to embodiments [8] to

[10] , wherein Z is a divalent group (n = 2) and is of the following formula:

[0158]

[0159]

[12] The polyaziridine compound according to embodiment

[10] or

[11] , wherein the diisocyanate is selected from 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, tetramethylxylene diisocyanate (all isomers) and any mixture thereof.

[0160]

[13] The polyaziridine compound according to any one of embodiments

[13] to

[17] , wherein the compound (B) is obtained by reacting at least one n-functional polyepoxide (wherein n is as defined in any of the compounds of the foregoing embodiments) with an aziridine having the following structural formula:

[0161]

[0162] Wherein R1, R2, R3, and R4 are as defined in any of the foregoing embodiments.

[0163]

[14] The polyaziridine compound according to any one of the foregoing embodiments, wherein the n-functional polyepoxide is a difunctional polyepoxide compound.

[0164]

[15] The polyaziridine compound according to any one of the foregoing embodiments, wherein the n-functional polyepoxide is selected from bisphenol A diglycidyl ether (CAS 1675-54-3), hydrogenated bisphenol A diglycidyl ether (CAS 30583-72-3), neopentyl glycol diglycidyl ether (CAS 17557-23-2), butanediol diglycidyl ether (CAS 2425-79-8), ethylene glycol diglycidyl ether (CAS 2224-15-9), 1,6-hexanediol diglycidyl ether (CAS 16096-31-4), polypropylene glycol diglycidyl ether (CAS 26142-30-3), poly(ethylene glycol) diglycidyl ether (CAS 72207-80-8), and any mixture thereof.

[0165]

[16] A crosslinking agent composition comprising at least one polyaziridine compound according to any one of the foregoing embodiments and further comprising at least one additional component.

[0166]

[17] The crosslinking agent composition according to embodiment

[16] , wherein, relative to the total weight of the crosslinking agent composition, the amount of aziridinyl-functional group molecules having a molecular weight of less than 580 daltons is less than 5% by weight, wherein the molecular weight is determined by LC-MS as described in the specification.

[0167]

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

[16] or

[17] , wherein the crosslinking agent composition is an aqueous dispersion comprising particles of a polyaziridine compound according to any one of embodiments [1] to

[15] .

[0168]

[19] The crosslinking agent composition according to embodiment

[18] , wherein the average hydrodynamic diameter of the particles present in the dispersion based on the scattering intensity is 5 - 700 nanometers, more preferably 10 - 300 nm, even more preferably 15 - 200 nm, and most preferably 15 to 150 nm, wherein the average hydrodynamic diameter based on the scattering intensity is determined as described in the specification.

[0169]

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

[18] to

[19] , wherein the pH of the aqueous dispersion is at least 8.8, more preferably at least 10, and most preferably at least 10.5.

[0170]

[21] A crosslinking agent composition according to any one of embodiments

[18] to

[20] , wherein the pH of the aqueous dispersion is less than 12, preferably less than 11.5.

[0171]

[22] Use of a polyaziridine compound according to any one of embodiments [1] to

[15] or a crosslinking agent composition according to any one of embodiments

[16] to

[21] for crosslinking a carboxylic acid functional polymer dissolved and / or dispersed in an aqueous medium.

[0172]

[23] A two-component 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 and the second component comprises a polyaziridine compound according to any one of Examples [1] to

[15] or a crosslinking agent composition according to any one of Examples

[16] to

[21] .

[0173]

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

[23] to the substrate and (ii) drying the coating composition by evaporation of the volatile matter.

[0174]

[25] An aqueous coating composition comprising dispersed particles containing a polyaziridine compound according to any one of embodiments [1] to

[15] and carboxylic acid functional polymer particles, and having a pH of 8 to 14.

[0175]

[26] The aqueous coating composition according to embodiment

[25] , characterized in that the amounts of aziridine groups and carboxylic acid groups are selected such that the stoichiometric amount (SA) of aziridine groups on the carboxylic acid groups is 0.1 to 2.0, more preferably 0.2 to 1.5, even more preferably 0.25 to 0.95, and most preferably 0.3 to 0.8.

[0176]

[27] The aqueous coating composition according to embodiments

[25] to

[26] , characterized in that the solids content of the coating composition 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 25% by weight, even more preferably at least 35% by weight and at most 55% by weight, more preferably at most 50% by weight and even more preferably at most 45% by weight.

[0177]

[28] The aqueous coating composition according to any one of Examples

[25] to

[27] , characterized in that the carboxylic acid functional polymer is selected from vinyl polymers, polyacrylates, polymethacrylates, poly(acrylate-copoly-methacrylate) and mixtures thereof.

[0178]

[29] The aqueous coating composition according to any one of embodiments

[25] to

[28] , characterized in that the carboxylic acid functional polymer is selected from polyurethanes, poly(urethane - co - acrylate), poly(urethane - co - methacrylate), poly(urethane - co - acrylate - co - methacrylate), polyureas, and mixtures thereof.

[0179]

[30] The aqueous coating composition according to any one of embodiments

[25] to

[29] , characterized in that the acid value of the carboxylic acid functional polymer is 2 to 135 mg KOH / g of the carboxylic acid functional polymer, more preferably 3 - 70 mg KOH / g of the carboxylic acid functional polymer, even more preferably 10 - 50 mg KOH / g of the carboxylic acid functional polymer, and even more preferably 15 - 50 mg KOH / g of the carboxylic acid functional polymer.

[0180]

[31] The aqueous coating composition according to any one of embodiments

[25] to

[30] , characterized in that the aqueous coating composition is self - crosslinkable.

[0181]

[32] The aqueous coating composition according to any one of embodiments

[25] to

[31] , wherein the aqueous coating composition comprises at least two dispersed phases having different compositions, wherein the first dispersed phase comprises particles X, wherein the particles X comprise the polyaziridine compound, and the second dispersed phase comprises particles Y, wherein the particles Y comprise a carboxylic acid functional polymer crosslinkable with the polyaziridine compound, wherein the particles X do not comprise a carboxylic acid functional polymer nor other compounds crosslinkable with the polyaziridine compound, and the particles Y do not comprise the polyaziridine compound, preferably the particles Y do not comprise the polyaziridine compound nor other crosslinking compounds capable of crosslinking the carboxylic acid functional groups of the carboxylic acid functional polymer, more preferably the particles Y do not comprise the polyaziridine compound and have no other crosslinking compounds.

[0182] Particle size measurement

[0183] Using the method from standard ISO 22412:2017, the average hydrodynamic diameter of the particles based on scattering intensity was determined using the Malvern Zetasizer Nano S90 DLS instrument, which was operated under the following settings: as the material, polystyrene latex was defined with an RI of 1.590 and an absorption of 0.10, using softened water as the continuous medium with a viscosity of 0.8812 cP at 25 °C and an RI of 1.332. The measurements were carried out in disposable cuvettes DTS0012 obtained from Malvern Instruments (Malvern, Worcestershire, United Kingdom). The measurements were made at a backscattering angle of 173°, and the average of 3 measurements was taken after a 120 - second equilibration, including 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. The sample was prepared by diluting 0.05 g (1 drop) of the sample dispersion in approximately 5 mL of softened water. If the sample still appeared turbid, it was further diluted with distilled water until it became almost transparent. This method is applicable for the determination of particle sizes from 2 nm to 3 μm.

[0184] pH measurement

[0185] The pH value of the sample was determined according to standard ISO976:2013. The sample was measured at 23 °C using a Metrohm 691 pH - meter equipped with a combination glass electrode and a PT - 1000 temperature sensor. The pH - meter was calibrated using buffer solutions of pH 7.00 and pH 9.21 before use.

[0186] NCO determination

[0187] The NCO content of the sample was determined according to standard ASTM D2572 - 19. In this process, the sample was reacted with an excess of di - n - butylamine. Subsequently, the excess di - n - butylamine was back - titrated with standard 1N hydrochloric acid (HCl). The difference in titration volumes between the sample and the blank was a measure of the isocyanate content on the solid, according to the following formula: %NCO 固体 = [(Vb – Vm)*N*4.2] / (A*s / 100), where %NCO 固体 is the isocyanate content on the solid, 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 sample weight in grams, and s is the solid content of the sample in %. The potentiometric end - point was used on a Metrohm 702SM Titrino titrator and the measurement was repeated twice (if the difference between the two results < 0.1% NCO , the measurement was accepted).

[0188] AV measurement

[0189] The acid value (AV) of the solid matter of the sample was determined according to the standard ASTM D1639-90(1996)e1. In this process, the sample dissolved in a good solvent was titrated with an alcoholic potassium hydroxide solution of known concentration (KOH). The difference in titration volume between the sample and the blank was 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 material, 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 sample weight in grams, and S is the solid content of the sample in %. The measurement was repeated twice using a potentiometric end point on a Metrohm 702SM Titrino titrator (the measurement was accepted if the difference between the two results was < 0.1 mg KOH / g of solid material).

[0190] Chemical resistance

[0191] Chemical resistance test based on standard DIN 68861-1:2011-01

[0192] Unless otherwise stated, the chemical resistance test was as follows:

[0193] Compared to the carboxylic acid functional group, the coating composition consisted of 0.9 stoichiometry (SA) of total carboxylic acid-reactive functional groups (such as aziridine). The coating composition was treated as described in the examples and then cast using a wire bar coater at a wet layer thickness of 100 μm. After casting, the film was dried at 25 °C for 1 hour and then annealed at 50 °C for 16 hours. Subsequently, a piece of absorbent cotton was soaked in 1:1 ethanol:softened water (by weight) and placed on the film for 60 minutes (unless otherwise stated). The absorbent cotton was removed and left overnight, after which the spots were scored according to the following scale:

[0194] 1 The coating was completely degraded;

[0195] 2 The coating structure was damaged;

[0196] 3 Severe markings on the coating, visible from multiple directions;

[0197] 4 Slight markings on the coating, visible from a specific angle;

[0198] 5 No markings or gloss changes were observed.

[0199] Viscosity measurement:

[0200] The apparent viscosity is determined according to ISO 2555:2018. The measurement is carried out at 23 °C on a Brookfield DVE-LV viscometer (single-cylinder geometry) at 60 rpm. Select the rotor from S62, S63 or S64, and use the smallest numbered rotor (i.e., the largest rotor) that produces torque readings of 10% and 100%.

[0201] NMP-MEK size exclusion chromatography

[0202] The molecular weight distribution is measured using an Alliance Separation Module (Waters e2695), which includes a pump, an autosampler, a degasser, and a column oven. The eluent is 80% n-methylpyrrolidone (NMP) / 20% methyl ethyl ketone (MEK) with 0.01 M lithium bromide added. The injection volume is 150 μl. The flow rate is set at 1.0 ml / min. Three PL Mixed B (Polymer Laboratories) columns with guard columns (5 μm PL) are used at a temperature of 70 °C. Detection is carried out at 50 °C using a differential refractive index detector (Waters 2414). The sample is dissolved in the eluent at a concentration of 5 mg of polymer per milliliter of solvent. The solubility is judged with a laser pointer after stabilizing at room temperature for 24 hours; if any scattering is visible, the sample is first filtered. Calculations are performed using 8 polystyrene standards (Polymer Standards Service) ranging from 160 to 1,737,000 daltons. Calculations are performed using Empower software (Waters) with a third-order calibration curve. The resulting molar mass is the polystyrene equivalent molar mass (daltons).

[0203] Measure T by DSC g

[0204] The glass transition temperature (Tg) of the polymer is measured by differential scanning calorimetry (DSC) on a TA Instruments Discovery DSC 250 instrument, in an N2 atmosphere, at a flow rate of 50 mL / min and a heating rate of 10 °C / min, according to the following method: Weigh 5 ± 0.5 mg of the sample and place it in the DSC cell at a temperature of 20 to 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, hold the temperature for 5 minutes; subsequently, heat the sample from -120 °C to 220 °C at a heating rate of 5 °C / min (Thermal imager A). T gMeasured from the last thermogram (Thermogram A), it is the half-width of the step in the DSC signal (DSC thermogram, heat flow vs. temperature) observed for Tg. The DSC signal was processed using TRIOS software package version 5.0 provided by TA Instruments to determine T g 。

[0205] Low molecular weight fraction of LC-MS

[0206] LC system: Agilent 1290 Infinity II; Detector #1: Agilent 1290 Infinity IIPDA; Detector #2: Agilent iFunnel 6550 Q-TOF-MS.

[0207] The following procedure was used for LC-MS analysis of the low molecular weight fraction. A solution of ~100 mg / kg substance was prepared gravimetrically in methanol and stirred. 0.5 μl of this solution was injected into a UPLC equipped with an ESI-TOF-MS detector. The column used was 100 x 2.1 mm, 1.8 um, Waters HSS T3 C18, operated at 40 °C. The flow rate was 0.5 ml.min -1 。The solvents used were 10 mM NH4CH3COO aqueous solution (eluent A) set to pH 9.0 with NH3, acetonitrile (B), and THF (C). Two binary gradients were applied, from 80 / 20 A / B to 1 / 99 A / B in 10 minutes and from 1 / 99 A / B to 1 / 49 / 50 A / B / C in 5 minutes, followed by the starting condition (80 / 20 A / B). Assuming all components have a linear MS response over all response ranges and all components have the same ionization efficiency, the total ion current signal was integrated. In the case of co-elution, the extracted ion chromatogram for that particular species was integrated. The integrated signal of a specific low molecular weight peak was divided by the total integrated sample signal to obtain the fraction of that low molecular weight substance.

[0208] MALDI-ToF-MS

[0209] All MALDI-ToF-MS spectra were obtained using a Bruker Ultraflextreme MALDI-ToF mass spectrometer. The instrument is equipped with a Nd:YAG laser with an emission wavelength of 1064 nm and a collision cell (not used for these samples). Spectra were acquired in positive ion mode using the reflector and 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%. Samples were dissolved in THF at a concentration of 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.

[0210] Sodium iodide was used as the salt (NaI, CAS number 7681-82-5); 10 mg was dissolved in 1 ml of THF and 1 drop of MeOH was added. The sample:matrix:salt ratio = 10:200:10 (μl), and after mixing, 0.5 μL was spotted on the MALDI plate and allowed to air dry. The peaks measured in the MALDI spectrum were the sodium adducts of the polyaziridine compounds, and in the context of this specification, the molecular weight (MW) of the polyaziridine compounds corresponded to MW = observed [M + M 阳离子 – M 阳离子 where observed [M + M 阳离子 was the MALDI-TOFMS peak and M 阳离子 was the accurate mass of the cation used to form the adduct (in this case, M 阳离子 for sodium = 23.0 Da). The polyaziridine compounds could 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), with a maximum deviation of 0.6 Da.

[0211] Genotoxicity testing

[0212] Genotoxicity was evaluated by assay (Toxys, Leiden, Netherlands). The ToxTracker assay is a set of validated green fluorescent protein (GFP)-based mouse embryonic stem (mES) reporter cell lines that can be used to identify the biological reactivity and potential carcinogenic properties of newly developed compounds in a single test. The method uses a two-step approach.

[0213] In the first step, 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 two-fold dilutions.

[0214] Next, the genotoxicity of DNA damage was evaluated using specific genes associated with reporter genes; namely, the Bscl2 (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 in 96-well cell culture plates. After 24 h of cell seeding in the 96-well plates, fresh ES cell medium containing the diluted test article was added to the cells. For each compound tested, five concentrations were tested at two-fold dilutions. The highest sample concentration caused significant cytotoxicity (50 - 70%). In the absence or low cytotoxicity, 10 mM or the maximum soluble mixture concentration was used as the maximum test concentration. Cytotoxicity was determined by cell counting after 24 h of exposure using a Guava easyCyte 10HT flow cytometer (Millipore).

[0215] Induction of the GFP reporter gene was always compared to vehicle control treatment. For a given compound, the DMSO concentration in all wells was similar and never exceeded 1%. All compounds were tested in at least 3 completely independent replicates. All experiments included a positive reference treatment with cisplatin (DNA damage). Metabolism was evaluated by addition of S9 liver extract. In the presence of S9 and the required cofactors (RegenSysA+B, Moltox, Boone, NC, USA), cells were exposed to five concentrations of the test compound for 3 hours. After washing, cells were cultured in fresh ES cell medium for 24 hours. Induction of the GFP reporter gene was determined 24 hours after exposure using a Guava easyCyte 10HT flow cytometer (Millipore). GFP expression was determined only in intact single cells. Mean GFP fluorescence and cell concentration in each well were measured for cytotoxicity assessment. Data were analyzed using ToxPlot software (Toxys Leiden the Netherlands). The reported induction levels were the compound concentrations inducing 10%, 25% and 50% cytotoxicity after 3 hours of exposure and 24 hours of recovery in the presence of S9 rat liver extract, or after 24 hours of exposure in the absence of S9 rat liver.

[0216] Positive induction levels of biomarkers were 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 the metabolic system rat S9 liver extract; weak positive induction was 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 the metabolic system rat S9 liver extract; negative induction was defined as lower than or equal to 1.5-fold induction at at least one of 10%, 25% and 50% cytotoxicity, in the absence and presence of the metabolic system based on rat S9 liver extract.

[0217] Components and abbreviations used:

[0218] Dimethylformamide (CAS No. 68-12-2) was purchased from Acros Organics (a division of Thermo Fisher Scientific).

[0219] Di(propylene glycol) dimethyl ether (Proglyde DMM, CAS No. 111109-77-4) was purchased from Dow Inc.

[0220] Trimethylolpropane tris(2-methyl-1-aziridinepropionate), CAS No. 64265-57-2, CX-100 was purchased from DSM.

[0221] Bisphenol A diglycidyl ether (CAS No. 1675-54-3) was purchased from Tokyo Chemical Industry Co., Ltd.

[0222] Neopentyl glycol diglycidyl ether (CAS No. 17557-23-2) was purchased from Sigma-Aldrich.

[0223] Potassium carbonate (CAS No. 584-08-7) was purchased from Alfa Aesar (a division of Thermo Fisher Scientific).

[0224] 2-Methylaziridine (propyleneimine, CAS No. 75-55-8) was purchased from Menadiona S.L. (Palafolls, Spain).

[0225] 1,3-Bis(2-isocyanatopropan-2-yl)benzene (m-tetramethylxylene diisocyanate, TMXDI, CAS No. 2778-42-9) was purchased from Allnex.

[0226] Bismuth neodecanoate (CAS No. 34364-26-6) was purchased from TIB Chemical AG (Mannheim Germany).

[0227] H12MDI (4,4'-Methylenebis(phenyl isocyanate), W, CAS No. 101-66-8).

[0228] Maxemul TM 7101 was purchased from Croda.

[0229] Methyl ethyl ketone (CAS No. 78-93-3) was purchased from Sigma-Aldrich.

[0230] D-230 (CAS No. 9046-10-0) was purchased from Huntsman

[0231] Oxymer TM M112 was purchased from Perstorp.

[0232] Cyclohexanol (CAS No. 108-93-0) was purchased from Sigma-Aldrich

[0233] Ymer TMN-120, purchased from Perstorp.

[0234] n-Methylbutylamine (CAS No. 110-68-9), purchased from Sigma-Aldrich.

[0235] 3-Cyclohexylamino-1-propanesulfonic acid sodium salt (CAS No. 105140-23-6), purchased from Fluorochem.

[0236] n-Butyl glycidyl ether (CAS No. 2426-08-6), purchased from Alfa Aesar (a division of Thermo Fisher Scientific).

[0237] Atlas TM G-5002L-LQ, purchased from Croda.

[0238] Voranol TM P-400, purchased from Dow Inc.

[0239] Hydrazine (16% aqueous solution, CAS No. 302-01-2), purchased from Honeywell.

[0240] Dimethylolpropionic acid (DMPA, CAS No. 4767-03-7), purchased from Perstop Polyols.

[0241] Triethylamine (TEA, CAS No. 121-44-8), purchased from Arkema.

[0242] Dibutyltin dilaurate (CAS No. 77-58-7), purchased from Sigma-Aldrich.

[0243] Polypropylene glycol, number average molecular weight of 1000 Da and number average molecular weight of 2000 Da, obtained from BASF.

[0244] Sodium lauryl sulfate (30% aqueous solution, CAS No. 73296-89-6), purchased from BASF.

[0245] Acetone (CAS No. 67-64-1), purchased from Acros Organics (a division of Thermo Fisher Scientific).

[0246] Methyl methacrylate (CAS No. 80-62-6), purchased from Lucite Int.

[0247] n-Butyl acrylate (CAS No. 141-32-2), purchased from Dow Chemical.

[0248] Methacrylic acid (CAS No. 79-41-4), purchased from Lucite Int.

[0249] Ammonium persulfate (CAS No. 7727-54-0), purchased from United Initiators.

[0250] Ammonia (25% aqueous solution, CAS No. 1336-21-6), purchased from Merck.

[0251] 1-Butanol (CAS No. 71-36-3), purchased from Sigma-Aldrich.

[0252] Preparation Example 1: Synthesis of aqueous polyurethane polymer P1

[0253] Charge a 1 L flask equipped with a thermometer and overhead stirrer with 29.9 g of dimethylolpropionic acid, 282.1 g of polypropylene glycol with an average Mn of 2000 Da (OH value of 55.5 mg KOH / g polymer), 166.5 g of polypropylene glycol with an average Mn of 1000 Da (OH value of 110 mg KOH / g polymer), and 262.8 g of isophorone diisocyanate. Place the reaction mixture under a N2 atmosphere, heat to 50 °C and add 0.07 g of dibutyltin dilaurate. Allow the mixture to exotherm and hold at 95 °C for 1 hour. The NCO content of the resulting urethane prepolymer is 7.00% (on solids) (theoretical 7.44%). Cool the prepolymer to 60 °C and add TEA (18.7 g) and stir the resulting mixture for 30 minutes. Prepare a dispersion of the resulting prepolymer by adding the entire prepolymer to a mixture of 1100 g of softened water, 19.5 g of nonylphenol ethoxylate 9eo, and 4.0 g of triethylamine over 60 minutes at room temperature. After feeding is complete, stir the mixture for 5 minutes and add hydrazine (16% aqueous solution, 111.2 g). Stir the dispersion for an additional 1 hour.

[0254] Preparation Example 2: Synthesis of aqueous acrylic polymer A1

[0255] Sodium dodecyl sulfate (30% solids in water, 18.6 g solution) and softened water (711 g) were charged into a 2 L four-necked flask equipped with a thermometer and an overhead stirrer. The reactor was placed under a N2 atmosphere and heated to 82 °C. A mixture of softened water (112 g), sodium dodecyl sulfate (30% solids in water, 37.2 g 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 an overhead stirrer (monomer feed). Ammonium persulfate (1.75 g) was dissolved in softened water (89.61 g) and placed in a small feed funnel (initiator feed). Ammonium persulfate (1.75 g) was dissolved in softened water (10.5 g), and this solution was added to the reactor phase. Subsequently, 5 vol% of the monomer feed was immediately added to the reactor phase. Then the reaction mixture exothermed to 85 °C and was 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 complete, the monomer feed funnel was rinsed with softened water (18.9 g), and the reaction temperature was held at 85 °C for 45 minutes. Subsequently, the mixture was cooled to room temperature and adjusted to pH = 7.2 with an ammonia solution (6.25 wt.% in softened water) and further adjusted to 40% solids with additional softened water.

[0256] Example 1

[0257] A 2 L round-bottom flask equipped with a condenser was placed under a N2 atmosphere and charged with toluene (250 g), propylene imine (325 g), bisphenol A-diglycidyl ether (387 g), and K2CO3 (10.0 g) and heated to 70 °C over 30 minutes, then the mixture was stirred at T = 70 °C for 19 hours. After filtration, the excess PI was removed in vacuo and further purified by vacuum distillation to give a white solid.

[0258] A 500 mL round-bottom flask equipped with a thermometer and an overhead stirrer was placed under a N2 atmosphere and charged with the bisphenol A-PI intermediate (42.72 g) prepared as described above, n-butanol (27.86 g), m-tetramethylxylene diisocyanate (91.83 g), and 50.00 g of acetone. The resulting mixture was heated to 60 °C, then bismuth neodecanoate (0.02 g) was added. The mixture was kept at 60 °C using a water bath during the exotherm and then stirred at 60 °C for 2 hours. Samples were taken regularly and the reaction progress was monitored using a Bruker Alpha FT-IR spectrometer until no change in the NCO-stretch was observed at 2200 - 2300 cm -1 No change in the NCO-stretch was observed. Subsequently, 37.59 g of Voranol TMP-400 was added to the reaction mixture. Then the reaction mixture was further reacted until the above NCO-stretching peak completely disappeared, and then 25.00 g of acetone was added to dilute the reaction mixture. Finally, the solvent was evaporated to obtain a highly viscous pale yellow liquid.

[0259] The calculated molecular weights of the theoretical main components are 1090.67 Da (without PPG chain) and 1817.14 Da (one PPG chain, 9 PO units); the chemical structures are shown below.

[0260]

[0261] The molecular weight was confirmed by Maldi-TOF-MS: calculated value [M+Na+] = 1113.16 Da; measured value [M+Na+] = 1113.60 Da.

[0262]

[0263] The molecular weight was confirmed by Maldi-TOF-MS: calculated value [M+Na+] = 1840.13 Da; measured value [M+Na+] = 1840.08 Da.

[0264] The following components with a mass lower than 580 Da were determined and quantified by LC-MS:

[0265]

[0266] The amount present in the composition is less than 0.01% by weight.

[0267] Genotoxicity test

[0268]

[0269] The genotoxicity test results showed that the crosslinking agent composition of Example 1 was non-genotoxic.

[0270] According to the procedure of standard DIN 68861-1:2011-01, the performance of the synthetic compound as a crosslinking agent was evaluated using dot tests on the coated surface. For these tests, a solution of 1.1 parts of the viscous crosslinking agent liquid in 0.3 parts of acetone was added to 10.5 parts of P1 with continuous stirring, and the resulting mixture was further stirred for 30 minutes. After that, the coating composition was filtered and applied to a Leneta test card using a 100 μm wire applicator (Test 1-1). As a reference, a film was also cast from the same composition lacking the crosslinking agent (Blank 1-2). The film was dried at 25 °C for 16 hours, then annealed at 50 °C for 1 hour and further dried at 25 °C for 24 hours. Subsequently, a piece of absorbent cotton was soaked in 1:1 EtOH:softened water and placed on the film for different times. After removing the EtOH and allowing it to recover for 60 minutes, the following results were obtained (1 point indicates complete degradation of the film, and 5 points indicates no visible damage):

[0271]

[0272] Subsequently, 24 g of the yellow liquid obtained as described above was mixed with 6.0 g of methyl ethyl ketone (MEK) and 6.0 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 2.4 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 Ultra- mixer with an S25N-18G head. Then, the stirring was increased to 10,000 rpm, and 24 g of softened 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 another 10 minutes, and the pH of the dispersion was set to 11 with TEA.

[0273] According to the procedure of standard DIN68861-1, the functional properties and stability of the crosslinker dispersion are evaluated using a point test on the coated surface, and viscosity measurements are performed using a Brookfield DVE-LV viscometer (S62 rotor at 60 rpm unless otherwise specified). For these tests, the crosslinker dispersion is stored in an oven at 50 °C for 4 weeks. The viscosity and particle size of the crosslinker dispersion are determined weekly. Additionally, 2.8 g of the aged crosslinker dispersion is mixed with 10.5 g of polymer P1 under continuous stirring each week, and the resulting mixture is further stirred for 30 minutes. The coating composition is filtered and applied to a Leneta test card using a 100 μm wire bar coater (Test 1). As a reference, a film is also cast from the same composition lacking the crosslinker dispersion (Test blank). 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 1:1 EtOH:softened water and placed on the film for 1 hour. After removing the EtOH and allowing it to recover for 60 minutes, the following results are obtained (1 point indicates complete degradation of the film, 5 points indicates no visible damage):

[0274] Performance and stability tests

[0275]

[0276] Example 2

[0277] A 2 L round-bottom flask of the condenser is placed under an N2 atmosphere and charged with toluene (250 g), propyleneimine (330 g), neopentyl-glycol-diglycidyl-ether ether (275 g), and K2CO3 (10.0 g) and heated to 70 °C within 30 minutes, then the mixture is stirred at T = 70 °C for 22 hours. After filtration, the excess PI is removed in vacuo and then further purified by vacuum distillation to obtain a viscous solid.

[0278] A 500 mL round-bottom flask equipped with a thermometer and overhead stirrer is placed under an N2 atmosphere and charged with the NPG-PI intermediate from the first step (32.93 g), n-butanol (14.77 g), Desmodur W (52.29 g), and 25.00 g of acetone. The resulting mixture is heated to 50 °C, then bismuth neodecanoate (0.02 g) is added. The mixture is allowed to exotherm to 60 °C and then stirred for 90 minutes, then another 25.00 g of acetone is added and the reaction is continued for 2 hours. Then, another 25.00 g of acetone and 4.00 g of n-butanol are added and the reaction is continued. Samples are taken regularly and the progress of the reaction is monitored using a BrukerAlphaFT-IR spectrometer, and the reaction is continued until 2200 - 2300 cm -1The NCO-stretching completely disappeared. Finally, the solvent was evaporated to obtain a colorless solid. The calculated molecular weight of the theoretical main component was 1002.73 Da, and the chemical structure is shown below.

[0279]

[0280] The molecular weight was confirmed by Maldi-TOF-MS: calculated value [M+Na+] = 1025.72 Da; measured value [M+Na+] = 1025.67 Da.

[0281] The following components with a mass below 580 Da were determined and quantified by LC-MS:

[0282]

[0283] The amount present in the composition was less than 0.01% by weight.

[0284] Genotoxicity test

[0285]

[0286]

[0287] The genotoxicity test results showed that the crosslinker composition of Example 2 was non-genotoxic.

[0288] According to the procedure of standard DIN 68861-1:2011-01, the performance of the synthetic compound as a crosslinker was evaluated using a spot test on a coated surface. For these tests, a solution of 0.5 parts of the solid crosslinker in 0.3 parts of acetone was added to 10.5 parts of P1 with continuous stirring, and the resulting mixture was further stirred for 30 minutes. After that, the coating composition was filtered and applied to a Leneta test card using a 100 μm wire bar coater (Test 2-1). As a reference, a film was also cast from the same composition lacking the crosslinker (Blank 2-2). The film was dried at 25 °C for 16 hours, then annealed at 50 °C for 1 hour, and then dried at 25 °C for 24 hours. Subsequently, a piece of absorbent cotton was soaked in 1:1 EtOH:softened water and placed on the film for different times. After removing the EtOH and allowing it to recover for 60 minutes, the following results were obtained (1 point indicates complete degradation of the film, and 5 points indicates no visible damage):

[0289]

[0290] For further performance testing, a solution of 1.0 part of solid crosslinker in 0.5 part of acetone was added to 10.5 parts of A1 under continuous stirring, and the resulting mixture was further stirred for 30 minutes. Thereafter, the coating composition was filtered and applied to a Leneta test card using a 100 μm wire bar coater (Test 2-3). As a reference, a film was also cast from the same composition lacking the crosslinker (Blank 2-4). The film was dried at 25 °C for 16 hours, then annealed at 50 °C for 1 hour, and then dried at 25 °C for 24 hours. Subsequently, a piece of absorbent cotton was soaked in 1:1 EtOH:softened water and placed on the film for different times. After removing the EtOH and allowing recovery for 60 minutes, the following results were obtained (1 point indicates complete degradation of the film, 5 points indicates no visible damage):

[0291]

[0292] Example 3

[0293] A 500 mL round-bottom flask equipped with a thermometer and overhead stirrer was placed under a N2 atmosphere and charged with the bisphenol A-PI intermediate (21.25 g) prepared as described in Example 1, Ymer TM N-120 (23.01 g), hexamethylene diisocyanate (31.45 g), and 25.00 g of acetone. The resulting mixture was heated to 60 °C, and then bismuth neodecanoate (0.02 g) was added. The mixture was maintained at 50 °C using a water bath during the exothermic period. After 5 minutes, 18.73 g of cyclohexanol was added to the mixture, and the mixture was again maintained at 50 °C using a water bath, and then stirred at 50 °C for 2 hours. Samples were taken periodically and the reaction progress was monitored using a Bruker Alpha FT-IR spectrometer until no change in the NCO-stretching was observed at 2200 - 2300 cm -1 Subsequently, 5.56 g of Jeffamine D-230 was added to the reaction mixture. Then the reaction mixture was allowed to react further until the above NCO-stretching peak completely disappeared. Then, the mixture was cooled to 40 °C and 170 g of softened water was gradually added to obtain a blue dispersion. Then acetone was removed from the dispersion using a rotary evaporator, and finally the pH of the dispersion was set to 11 using triethylamine.

[0294] The calculated molecular weights of the main components of the theory are 990.64 Da (without Jeffamine D-230 and without Ymer), 1406.93 Da (without Ymer, with 3 PO groups in Jeffamine D-230), 2143.34 Da (without Jeffamine, with 19 EO groups in Ymer), and 2515.61 Da (with 3 PO groups in Jeffamine D-230 and with 18 EO groups in Ymer); the chemical structures are as follows.

[0295]

[0296] The molecular weight was confirmed by Maldi-TOF-MS: calculated value [M+Na+] = 1013.63 Da; measured value [M+Na+] = 1013.68 Da.

[0297]

[0298] The molecular weight was confirmed by Maldi-TOF-MS: calculated value [M+Na+] = 1429.93 Da; measured value [M+Na+] = 1430.01 Da.

[0299]

[0300] The molecular weight was confirmed by Maldi-TOF-MS: calculated value [M+Na+] = 2166.33 Da; measured value [M+Na+] = 2166.47 Da.

[0301]

[0302] The molecular weight was confirmed by Maldi-TOF-MS: calculated value [M+Na+] = 2538.60 Da; measured value [M+Na+] = 2538.76 Da.

[0303] The following components with a mass below 580 Da were determined and quantified by LC-MS:

[0304]

[0305] The amount present in the composition is less than 0.01% by weight.

[0306] Genotoxicity test

[0307]

[0308]

[0309] The genotoxicity test results indicate that the crosslinking agent composition of Example 3 is non-genotoxic.

[0310] According to the procedure of standard DIN 68861-1:2011-01, the performance of the synthetic compound as a crosslinking agent was evaluated using a dot test on the coated surface. For these tests, 2.9 parts of the crosslinking agent dispersion were added to 10.5 parts of P1 with continuous stirring, and the resulting mixture was further stirred for 30 minutes. After that, the coating composition was filtered and applied to a Leneta test card using a 100 μm wire-wound applicator (Test 3-1). As a reference, a film was also cast from the same composition lacking the crosslinking agent (Blank 3-2). The film was dried at 25 °C for 16 hours, then annealed at 50 °C for 1 hour, and then dried at 25 °C for 24 hours. Subsequently, a piece of absorbent cotton was soaked in 1:1 EtOH:softened water and placed on the film for different times. After removing the EtOH and allowing it to recover for 60 minutes, the following results were obtained (1 point indicates complete degradation of the film, and 5 points indicates no visible damage):

[0311]

[0312] For further performance testing, 5.9 parts of the crosslinking agent dispersion were added to 10.5 parts of A1 with continuous stirring, and the resulting mixture was further stirred for 30 minutes. After that, the coating composition was filtered and applied to a Leneta test card using a 100 μm wire-wound applicator (Test 3-3). As a reference, a film was also cast from the same composition lacking the crosslinking agent (Blank 3-4). The film was dried at 25 °C for 16 hours, then annealed at 50 °C for 1 hour, and then dried at 25 °C for 24 hours. Subsequently, a piece of absorbent cotton was soaked in 1:1 EtOH:softened water and placed on the film for different times. After removing the EtOH and allowing it to recover for 60 minutes, the following results were obtained (1 point indicates complete degradation of the film, and 5 points indicates no visible damage):

[0313]

[0314] According to the procedure of standard DIN 68861-1, the functional properties and stability of the crosslinker dispersion were evaluated using dot tests on the coated surface, and viscosity measurements were carried out using a Brookfield DVE-LV viscometer (S62 rotor at 60 rpm unless otherwise stated). For these tests, 100 g of the crosslinker dispersion obtained as described above and diluted with 170 g of softened water was stored in an oven at 50 °C for 4 weeks. The viscosity of the aged diluted crosslinker dispersion was determined weekly. Additionally, 2.9 g of the aged diluted crosslinker dispersion was mixed with 10.5 g of polymer P1 under continuous stirring weekly, and the resulting mixture was further stirred for 30 minutes. The coating composition was filtered and applied to a Leneta test card using a 100 μm wire-wound applicator (Test 3). As a reference, a film was also cast from the same composition 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 absorbent cotton was soaked in 1:1 EtOH:softened 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 (1 point indicates complete degradation of the film, 5 points indicates no visible damage):

[0315] Performance and stability tests

[0316]

[0317] Example 4

[0318] A 500 mL round-bottom flask equipped with a thermometer and overhead stirrer was placed under a N2 atmosphere and charged with the bisphenol A-PI intermediate (15.92 g) prepared as described in Example 1, Ymer TM N-120 (13.37 g), isophorone diisocyanate (31.13 g), Oxymer TM M112 (21.91 g) and 25.00 g of acetone. The resulting mixture was heated to 60 °C and then bismuth neodecanoate (0.02 g) was added. The mixture was maintained at 50 °C using a water bath during the exothermic period. The mixture was stirred at 50 °C for 165 minutes. Samples were taken regularly and the progress of the reaction was monitored using a Bruker Alpha FT-IR spectrometer until at 2200 - 2300 cm -1No change in the NCO-stretching was observed. Subsequently, 9.16 g of n-methylbutylamine was added to the reaction mixture, and the mixture was stirred for an additional 5 minutes, followed by the addition of 8.52 g of 3-cyclohexylamino-1-propanesulfonic acid sodium salt. The reaction mixture was then allowed to react further until the above NCO-stretching peak completely disappeared. Then, 42 g of acetone was added and the mixture was cooled to 40 °C. Subsequently, 180 g of softened water was gradually added to obtain a blue dispersion. The acetone was then removed from the dispersion using a rotary evaporator, and finally the pH of the dispersion was adjusted to 11 using triethylamine.

[0319] The resulting material has the following general structure:

[0320]

[0321] The calculated molecular weights and chemical structures of the theoretical main components are shown below:

[0322]

[0323] The molecular weight was confirmed by Maldi-TOF-MS: calculated value [M+Na+] = 1095.76 Da; measured value [M+Na+] = 1095.79 Da.

[0324]

[0325] The molecular weight was confirmed by Maldi-TOF-MS: calculated value [M+2*Na+] = 1251.74 Da; measured value [M+2*Na+] = 1251.76 Da.

[0326]

[0327] The molecular weight was confirmed by Maldi-TOF-MS: calculated value [M+Na+] = 2258.48 Da; measured value [M+Na+] = 2258.61 Da.

[0328]

[0329] The molecular weight was confirmed by Maldi-TOF-MS: calculated value [M+Na+] = 2408.67 Da; measured value [M+Na+] = 2408.79 Da.

[0330] The following components with a mass below 580 Da were determined and quantified by LC-MS:

[0331]

[0332] The amount present in the composition is less than 0.01 wt%.

[0333] Genotoxicity test

[0334]

[0335] The results of the genotoxicity test showed that the crosslinker composition of Example 4 only had a weakly positive induction of genotoxicity.

[0336] According to the procedure of standard DIN 68861-1:2011-01, the performance of the synthetic compound as a crosslinker was evaluated using a spot test on a coated surface. For these tests, 4.2 parts of the crosslinker dispersion were added to 10.5 parts of P1 under continuous stirring, and the resulting mixture was further stirred for 30 minutes. Thereafter, the coating composition was filtered and applied to a Leneta test card using a 100 μm wire bar coater (Test 4-1). As a reference, a film was also cast from the same composition lacking the crosslinker (Blank 4-2). The film was dried at 25 °C for 16 hours, then annealed at 50 °C for 1 hour, and then dried at 25 °C for 24 hours. Subsequently, a piece of absorbent cotton was soaked in 1:1 EtOH:softened water and placed on the film for different times. After removing the EtOH and allowing recovery for 60 minutes, the following results were obtained (1 point indicates complete degradation of the film, and 5 points indicates no visible damage):

[0337]

[0338] For further performance testing, 8.5 parts of the crosslinker dispersion were added to 10.5 parts of A1 under continuous stirring, and the resulting mixture was further stirred for 30 minutes. Thereafter, the coating composition was filtered and applied to a Leneta test card using a 100 μm wire bar coater (Test 4-3). As a reference, a film was also cast from the same composition lacking the crosslinker (Blank 4-4). The film was dried at 25 °C for 16 hours, then annealed at 50 °C for 1 hour, and then dried at 25 °C for 24 hours. Subsequently, a piece of absorbent cotton was soaked in 1:1 EtOH:softened water and placed on the film for different times. After removing the EtOH and allowing recovery for 60 minutes, the following results were obtained (1 point indicates complete degradation of the film, and 5 points indicates no visible damage):

[0339]

[0340] According to the procedure of standard DIN 68861-1, the functional properties and stability of the crosslinker dispersion were evaluated using a point test on the coated surface, and the viscosity was measured using a Brookfield DVE-LV viscometer (S62 rotor at 60 rpm unless otherwise stated). For these tests, 100 g of the crosslinker dispersion obtained as described above and diluted with 194 g of softened water was stored in an oven at 50 °C for 4 weeks. The viscosity of the aged diluted crosslinker dispersion was determined weekly. In addition, 4.2 g of the aged diluted crosslinker dispersion was mixed with 10.5 g of polymer P1 under continuous stirring every week, and the resulting mixture was further stirred for 30 minutes. The coating composition was filtered and applied to a Leneta test card using a 100 μm wire bar coater (Test 4). As a reference, a film was also cast from the same composition 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 absorbent cotton was soaked in 1:1 EtOH:softened 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 (1 point indicates complete degradation of the film, 5 points indicates no visible damage):

[0341] Performance and stability tests

[0342]

[0343] Example 5

[0344] Synthesize the crosslinker as in Example 1.

[0345] Subsequently, 32 g of the yellow liquid obtained as described above was mixed with 8.0 g of methyl ethyl ketone (MEK) and 8.0 g of acetone and incubated at 50 °C until a homogeneous solution was obtained. 2.4 g of molten Maxemul TM 7101 dispersant was added to this solution. The resulting mixture was stirred at 2000 rpm for 5 minutes at room temperature using an IKA T25 Digital Ultra- mixer with an S25N-18G head. Then, the stirring was increased to 10000 rpm, and 32 g of softened water (adjusted to pH 12.5 using a 15% aqueous potassium hydroxide solution) 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 5000 rpm for another 10 minutes, and the pH of the dispersion was set to 12.5 using a 15% aqueous potassium hydroxide solution.

[0346] According to the procedure of standard DIN68861-1, the functional properties and stability of the crosslinker dispersion were evaluated using spot tests on the coated surface, and viscosity measurements were carried out using a Brookfield DVE-LV viscometer (S62 rotor 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 and particle size of the crosslinker dispersion were determined weekly. Additionally, 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 using a 100 μm wire-wound applicator (test 5). As a reference, a film was also cast from the same composition 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 absorbent cotton was soaked in 1:1 EtOH:softened water and placed on the film for 1 hour. After removing the EtOH and allowing it to recover for 60 minutes, the following results were obtained (1 point indicates complete degradation of the film, and 5 points indicates no visible damage):

[0347] Performance and stability tests

[0348]

[0349] Example 6

[0350] A 500 mL round-bottom flask equipped with a thermometer and overhead stirrer was placed under a N2 atmosphere and charged with the bisphenol A-PI intermediate (17.13 g) prepared as described in Example 1, the 1-butoxy-3-(2-methylaziridin-1-yl)propan-2-ol intermediate (28.24 g) prepared as in WO2020 / 020714A1, Desmodur W (39.55 g), and 25.00 g of acetone. The resulting mixture was heated to 60 °C, and then bismuth neodecanoate (0.02 g) was added. The mixture was maintained at 60 °C using a water bath throughout the exothermic reaction and then stirred at 60 °C for 2 hours. Samples were taken regularly and the progress of the reaction was monitored using a Bruker Alpha FT-IR spectrometer until no change in the NCO-stretching was observed at 2200 - 2300 cm -1 Subsequently, 15.08 g of Voranol TM P-400 was added to the reaction mixture. The reaction mixture was then allowed to react further until the above NCO-stretching peak completely disappeared. Finally, 20.00 g of acetone was added to produce a pale yellow solution. The calculated molecular weights and chemical structures of the theoretical main components are shown below:

[0351]

[0352] The molecular weight was confirmed by Maldi-TOF-MS: calculated value [M+Na+] = 2062.40 Da; measured value [M+Na+] = 2062.39 Da.

[0353]

[0354] The molecular weight was confirmed by Maldi-TOF-MS: calculated value [M+Na+] = 1375.92 Da; measured value [M+Na+] = 1375.86 Da.

[0355]

[0356] The molecular weight was confirmed by Maldi-TOF-MS: calculated value [M+Na+] = 659.47 Da; measured value [M+Na+] = 659.41 Da.

[0357] The following components with a mass below 580 Da were determined and quantified by LC-MS:

[0358]

[0359] are present in the composition in an amount less than 0.01% by weight, and

[0360]

[0361] is present in an amount less than 0.01% by weight.

[0362] Genotoxicity test

[0363]

[0364] The results of the genotoxicity test showed that the crosslinker composition of Example 6 only had a weakly positive induction of genotoxicity.

[0365] According to the procedure of standard DIN 68861-1:2011-01, the performance of the synthetic compound as a crosslinking agent was evaluated using a spot test on the coated surface. For these tests, a solution of 1.3 parts of the viscous crosslinking agent liquid in 0.4 parts of acetone was added to 10.5 parts of P1 with continuous stirring, and the resulting mixture was further stirred for 30 minutes. After that, the coating composition was filtered and applied to a Leneta test card (Test 6-1) using a 100 μm wire applicator. As a reference, a film was also cast from the same composition lacking the crosslinking agent (Blank 6-2). The film was dried at 25 °C for 16 hours, then annealed at 50 °C for 1 hour, and then dried at 25 °C for 24 hours. Subsequently, a piece of absorbent cotton was soaked in 1:1 EtOH:softened water and placed on the film for different times. After removing the EtOH and allowing it to recover for 60 minutes, the following results were obtained (1 point indicates complete degradation of the film, and 5 points indicates no visible damage):

[0366]

[0367] Subsequently, 15 g of the yellow solution obtained in the previous step was mixed with 1.5 g of methyl ethyl ketone (MEK) and incubated at 50 °C until a homogeneous solution was obtained. 0.03 g of triethylamine (TEA) was added to this solution, and then 1.1 g of Atlas TM G-5002L-LQ dispersant. The resulting mixture was stirred at 2000 rpm for 5 minutes at room temperature using an IKA T25 Digital Ultra- mixer with an S25N-18G head. Then, the stirring speed was increased to 10000 rpm, and 10.4 g of softened water (adjusted to pH 11 using 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 5000 rpm for another 10 minutes, and the pH of the dispersion was set to 11 using TEA.

[0368] According to the procedure of standard DIN 68861-1, the functional performance and stability of the crosslinker dispersion are evaluated using dot tests on the coated surface, viscosity measurements, and particle size measurements. For these tests, the crosslinker dispersion is stored in an oven at 50 °C for 4 weeks. The viscosity and particle size of the crosslinker dispersion are determined weekly. In addition, 1.2 g of the aged crosslinker dispersion is mixed with 10.5 g of polymer P1 under continuous stirring each week, and the resulting mixture is further stirred for 30 minutes. The coating composition is filtered and applied to a Leneta test card using a 100 μm wire bar coater (Test 6). As a reference, a film is also cast from the same composition lacking the crosslinker dispersion (Test blank). 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 1:1 EtOH:softened water and placed on the film for 1 hour. After removing the EtOH and allowing to recover for 60 minutes, the following results are obtained (1 point indicates complete degradation of the film, 5 points indicates no visible damage):

[0369] Performance and stability tests

[0370]

Claims

1. A polyaziridine compound, the polyaziridine compound having: a) At least 2 of the following structural units (A): (A) Wherein, R1 is H; R2 and R4 are independently selected from H, a straight-chain group having 1 to 8 carbon atoms and optionally containing one or more heteroatoms, a branched-chain group having 3 to 8 carbon atoms and optionally containing one or more heteroatoms, a cyclic group having 3 to 8 carbon atoms and optionally containing one or more heteroatoms, or benzyl; R3 is selected from a straight-chain group having 1 to 8 carbon atoms and optionally containing one or more heteroatoms, a branched-chain group having 3 to 8 carbon atoms and optionally containing one or more heteroatoms, a cyclic group having 3 to 8 carbon atoms and optionally containing one or more heteroatoms, or benzyl; Or R2 and R3 are part of the same cyclic group having 3 to 8 carbon atoms; R' and R'' are independently H or an aliphatic hydrocarbon group having 1 to 12 carbon atoms; and b) A molecular weight of 600 - 20000 daltons, where the molecular weight is determined using MALDI-TOF mass spectrometry; and The polyaziridine compound is obtained by reacting at least one polyisocyanate with a compound (B), the compound (B) being obtained by reacting at least one n-functional polyepoxide compound with aziridine, the aziridine having the following structural formula: Wherein R1, R2, R3 and R4 are as defined above.

2. The polyaziridine compound according to claim 1, wherein R2 and R4 are independently selected from phenyl or pyridyl.

3. The polyaziridine compound according to claim 1, wherein R3 is selected from phenyl or pyridyl.

4. The polyaziridine compound according to claim 1, wherein R2, R4 and R3 are independently selected from phenyl or pyridyl.

5. The polyaziridine compound according to claim 1, wherein R2 is H, R3 is CH3 and R4 is H.

6. The polyaziridine compound according to any one of claims 1 to 5, wherein R' and R'' are H.

7. The polyaziridine compound according to any one of claims 1 to 5, wherein the polyaziridine compound contains 2 to 10 structural units (A).

8. The polyaziridine compound according to any one of claims 1 to 5, characterized in that, The molecular weight of the polyaziridine compound is at least 800 daltons and at most 10000 daltons.

9. The polyaziridine compound according to any one of claims 1 to 5, wherein the polyisocyanate is a polyisocyanate having aliphatic reactivity, wherein all isocyanate groups are directly attached to an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, whether or not an aromatic hydrocarbon group is also present.

10. The polyaziridine compound according to any one of claims 1 to 5, wherein the polyisocyanate is a diisocyanate.

11. The polyaziridine compound according to claim 10, wherein the diisocyanate is selected from 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, tetramethylxylene diisocyanate, and any mixture thereof.

12. The polyaziridine compound according to any one of claims 1 to 5, wherein, The n-functional polyepoxide is a bifunctional polyepoxide.

13. The polyaziridine compound according to any one of claims 1 to 5, wherein the n-functional polyepoxide is selected from bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, neopentyl glycol diglycidyl ether, butanediol diglycidyl ether, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polypropylene glycol diglycidyl ether, poly(ethylene glycol) diglycidyl ether, and any mixture thereof.

14. A crosslinking agent composition comprising at least one polyaziridine compound according to any one of claims 1 to 13 and further comprising at least one additional component.

15. The crosslinking agent composition according to claim 14, wherein, Based on the total weight of the crosslinking agent composition, the amount of aziridinyl-functional molecules having a molecular weight lower than 580 daltons is less than 5% by weight, wherein the molecular weight is determined by LC-MS.

16. The crosslinking agent composition according to any one of claims 14 to 15, wherein the crosslinking agent composition is an aqueous dispersion comprising particles of the polyaziridine compound.

17. The crosslinking agent composition according to claim 16, wherein the pH of the aqueous dispersion is from 9.5 to 11.

5.

18. A two-component 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 carboxylic acid ester groups, and the second component comprises a polyaziridine compound according to any one of claims 1 to 13 or a crosslinking agent composition according to any one of claims 14 to 17.

19. An aqueous coating composition comprising dispersed particles X of a polyaziridine compound according to any one of claims 1 to 13 and carboxylic acid functional polymer particles Y, wherein, The carboxylic acid-functional polymer contains carboxylic acid groups and / or carboxylic acid radical groups, and wherein the pH range of the aqueous coating composition is from 8 to 14, provided that particle X does not contain a carboxylic acid-functional polymer nor any other compound capable of crosslinking with the polyaziridine compound, and particle Y does not contain a polyaziridine compound nor any other compound capable of crosslinking with the carboxylic acid-functional groups of the carboxylic acid-functional polymer.

20. The aqueous coating composition according to claim 19, wherein The acid value of the carboxylic acid-functional polymer is from 2 to 135 mg KOH / g.

21. The aqueous coating composition according to claim 19 or 20, characterized in that, The aqueous coating composition is self-crosslinkable.

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