(AZIRIDINYL HYDROXY)-FUNCTIONAL ORGANIC COMPOUNDS

Abstract

The invention relates to particular (aziridinyl hydroxy)-functional organic component. The invention further relates to liquid compositions comprising said (aziridinyl hydroxy)-functional organic component. The invention further relates to coating compositions comprising said (aziridinyl hydroxy)-functional organic component. The invention further relates to liquid coating compositions comprising said (aziridinyl hydroxy)-functional organic component. The invention further relates to a kit-of-parts comprising in one of its parts a liquid composition comprising a particular (aziridinyl hydroxy)-functional organic component. The invention further relates to cured forms of said liquid compositions, coating compositions, and liquid coating compositions. The invention further relates to articles comprising the (aziridinyl hydroxy)-functional organic component and/or the liquid compositions and/or the liquid coating compositions and/or their cured forms. The invention further relates to various uses of the (aziridinyl hydroxy)-functional organic component and/or said liquid compositions, and/or said liquid coating compositions, and/or said kit-of-parts and/or said cured forms.

Claims

1. An (aziridinyl hydroxy)-functional organic component (AZ-component) selected from the group consisting of i) to vi): i) (aziridinyl hydroxy)-functional organic compound AZ1 of Formula A1 having only two aziridine rings (AZ1-compound), ii) (aziridinyl hydroxy)-functional organic compound AZ2 of Formula A2 having only three aziridine rings (AZ2-compound), iii) (aziridinyl hydroxy)-functional organic compound AZ3 of Formula A3 having only four aziridine rings (AZ3-compound), iv) (aziridinyl hydroxy)-functional organic compound AZ4 of Formula A4 having only five aziridine rings (AZ4-compound), v) (aziridinyl hydroxy)-functional organic compound AZ5 of Formula A5 having only six aziridine rings (AZ5-compound), and vi) mixtures thereof, ##STR00058## wherein X.sub.1 is a bivalent aliphatic organic radical or a bivalent aromatic organic radical, preferably X.sub.1 is a bivalent aliphatic organic radical; X.sub.2 is a trivalent aliphatic organic radical or a trivalent aromatic organic radical, preferably X.sub.2 is a trivalent aliphatic organic radical; X.sub.3 is a quadrivalent aliphatic organic radical or a quadrivalent aromatic organic radical, preferably X.sub.3 is a quadrivalent aliphatic organic radical; X.sub.4 is a pentavalent aliphatic organic radical or a pentavalent aromatic organic radical, preferably X.sub.4 is a pentavalent aliphatic organic radical; X.sub.5 is a hexavalent aliphatic organic radical or a hexavalent aromatic organic radical, preferably X.sub.5 is a hexavalent aliphatic organic radical; and wherein each of the X.sub.1 to X.sub.5 consists of a collection of atoms covalently connected in a configuration that comprises —preferably consists of—linear and/or branched and/or ring structures, which collection of atoms is selected from the group consisting of i) to x): i) carbon and hydrogen atoms, ii) carbon, hydrogen and oxygen atoms, iii) carbon, hydrogen and nitrogen atoms, iv) carbon, hydrogen and sulphur atoms, v) carbon, hydrogen, oxygen and nitrogen atoms, vi) carbon, hydrogen, nitrogen and sulphur atoms, vii) carbon, hydrogen, oxygen and sulphur atoms, viii) carbon, hydrogen, oxygen, nitrogen and sulphur, atoms, ix) carbon, hydrogen and silicon atoms, and x) carbon, hydrogen, oxygen and silicon atoms and xi) any combination of ix) and/or x) with any one or all of the iii) to viii), and wherein each of the X.sub.1 to X.sub.5 has carbon atoms and hydrogen atoms, and wherein each of the X.sub.1 to X.sub.5 has optionally oxygen atoms and/or nitrogen atoms and/or sulphur atoms and/or silicon atoms, and wherein the X.sub.1, and/or the X.sub.2 and/or the X.sub.3 and/or the X.sub.4 and/or the X.sub.5 may optionally comprise an ionic functional group, wherein Y is a monovalent organic radical selected from the group consisting of: i) monovalent (aziridinyl hydroxyisopropyl) organic radical of Formula B1, ii) monovalent (aziridinyl hydroxycyclohexane) organic radical of Formula B2, and iii) monovalent (aziridinyl hydroxycyclohexane) organic radical of Formula B3, preferably Y is a monovalent (aziridinyl hydroxyisopropyl) organic radical of Formula B1, ##STR00059## and wherein R.sub.1 is selected from the group consisting of hydrogen and methyl; and R.sub.2 is selected from the group consisting of hydrogen, methyl, and C.sub.2-C.sub.5 alkyl; and R.sub.3 is selected from the group consisting of methyl, and C.sub.2-C.sub.4 alkyl; and R.sub.4 is selected from the group consisting of hydrogen, methyl, and C.sub.2-C.sub.4 alkyl; and wherein the Y in each of the compounds A1 to A5 may be the same or different to each other, and wherein each of the single covalent bonds between the Y and each one of the X.sub.1 to X.sub.5 is selected from the group consisting of carbon-carbon single bond, and carbon-oxygen single bond, preferably each of the single covalent bonds between the Y and each one of the X.sub.1 to X.sub.5 is carbon-oxygen single bond, and wherein each of the AZ1- to AZ5-compounds has a molecular weight determined via MALDI-TOF MS according to the description, of at least 600 and at most 10000, preferably at least 600 and at most 8000, more preferably at least 600 and at most 6000, most preferably at least 600 and at most 5000, especially at least 600 and at most 4000, more especially at least 600 and at most 3500, most especially at least 600 and at most 3200, for example at least 600 and at most 3000, for example at least 600 and at most 2500 Da, and wherein the X.sub.1 and the X.sub.2 and the X.sub.3 and the X.sub.4 and the X.sub.5 does not contain one or any combination of the following structural units BP1, BP2, BP3, and BS ##STR00060##

2. The AZ-component according to claim 1, wherein the X.sub.1, and/or the X.sub.2 and/or the X.sub.3 and/or the X.sub.4 and/or the X.sub.5 comprises at least one structural unit or a combination of structural units selected from the group consisting of unit 1, unit 2, unit 3, unit 4, unit 5, unit 6, unit 7, unit 8, unit 9, unit 10, and unit 11, as the units 1 to 11 are depicted below: ##STR00061## ##STR00062## wherein R′ is selected from the group consisting of hydrogen and methyl; and j is an integer ranging from 1 to 5, preferably from 1 to 3; and n is an integer ranging from and including 2 up to and including 50.

3. The AZ-component according to claim 1, wherein the aggregate number of carbon atoms in R.sub.1, and R.sub.2 and R.sub.3 and R.sub.4 is at most 9, preferably at most 4, more preferably at most 2, for example at most 1.

4. The AZ-component according to claim 1, wherein the X.sub.1 is the bivalent aliphatic organic radical of Formula A1a′ ##STR00063## wherein R′ is selected from the group consisting of hydrogen and methyl; and j is an integer ranging from 1 to 5, preferably from 1 to 3; and n is an integer ranging from and including 2 up to and including 50.

5. The AZ-component according to claim 1 wherein each of the X.sub.1 to X.sub.5 contains only single covalent bonds, or both single and double covalent bonds, and wherein the single covalent bonds are selected from the group consisting of carbon-carbon single bond, carbon-hydrogen single bond, carbon-nitrogen single bond, carbon-sulphur single bond, carbon-silicon single bond, silicon-oxygen single bond, nitrogen-hydrogen single bond, sulphur-oxygen single bond, carbon-oxygen single bond wherein the oxygen is bonded to a hydrogen forming a hydroxyl group, silicon-oxygen-silicon single bonds, and wherein the double covalent bonds are selected from the group consisting of carbon-carbon double bond, carbon-nitrogen double bond, sulphur-oxygen double bond, carbon-oxygen double bond wherein the carbon is a member of a ring structure, and carbon-oxygen double bond wherein the carbon is bonded to another two carbons via carbon-carbon single bonds, carbon-oxygen double bond wherein the carbon is bonded to another oxygen via single bond and to a nitrogen via a single bond, carbon-oxygen double bond wherein the carbon is bonded to two nitrogens via carbon-nitrogen single bonds, carbon-oxygen double bond wherein the carbon is bonded to another two oxygens via single bonds; preferably the double covalent bonds are selected from the group consisting of carbon-carbon double bond, carbon-nitrogen double bond, sulphur-oxygen double bond, carbon-oxygen double bond wherein the carbon is a member of a ring structure, and carbon-oxygen double bond wherein the carbon is bonded to another two carbons via carbon-carbon single bonds, carbon-oxygen double bond wherein the carbon is bonded to another oxygen via single bond and to a nitrogen via a single bond, carbon-oxygen double bond wherein the carbon is bonded to two nitrogens via carbon-nitrogen single bonds.

6. The AZ-component according to claim 1, wherein the AZ-component is selected from the group consisting of i) to v): i) (aziridinyl hydroxy)-functional organic compound AZ1 of Formula A1 (AZ1-compound), ii) (aziridinyl hydroxy)-functional organic compound AZ2 of Formula A2 (AZ2-compound), iii) (aziridinyl hydroxy)-functional organic compound AZ3 of Formula A3 (AZ3-compound), iv) (aziridinyl hydroxy)-functional organic compound AZ5 of Formula A5 (AZ5-compound), and vi) mixtures thereof, and wherein the AZ1-compound is selected from the group consisting of compounds having the Formula A1a, and compounds having the Formula A1b, as each of these Formulae A1a-A1d is described below ##STR00064## wherein each of the n in Formula A1a is independently selected, and each of the n in Formula A1a is an integer ranging from and including 2 up to and including 20; and ##STR00065## wherein the R in Formula A1b is a C.sub.3-C.sub.10 saturated hydrocarbylene, and wherein each of the n in Formula A1b is independently selected and each of the n in Formula A1a is an integer ranging from and including 2 up to and including 20; and ##STR00066## wherein each of the n in Formula A1c is independently selected, and each of the n in Formula A1b is an integer ranging from and including 2 up to and including 20; and ##STR00067## wherein the R in Formula A1d is a C.sub.3-C.sub.10 saturated hydrocarbylene, and wherein each of the n in Formula A1d is independently selected, and each of the n in Formula A1b is an integer ranging from and including 2 up to and including 20; and wherein the AZ2-compound is selected from the group consisting of compounds having the Formula A2a, compounds having the Formula A2b, compounds having the Formula A2c, compounds having the Formula A2d, compounds having the Formula A2e, as each of these Formulae A2a-A2e is described below ##STR00068## wherein the n in Formula A2a is an integer ranging from and including 2 up to and including 20; and ##STR00069## wherein each of the n in Formula A2b is independently selected, and each of the n in Formula A2b is an integer ranging from and including 2 up to and including 20; and ##STR00070## wherein each of the n in Formula A2c is independently selected, and each of the n in Formula A2c is an integer ranging from and including 2 up to and including 20; and ##STR00071## and wherein the AZ3-compound is selected from the group consisting of compounds having the Formula A3a ##STR00072## wherein each of the n in Formula A3a is independently selected, and each of the n in Formula A3a is an integer ranging from and including 2 up to and including 20; and wherein the AZ5-compound is selected from the group consisting of compounds having the Formula A5a ##STR00073## wherein each of the n in Formula A5a is independently selected, and each of the n in Formula A5a is an integer ranging from and including 2 up to and including 40.

7. The AZ-component according to claim 1, wherein the AZ-component is selected from the group consisting of AZ1-compound and wherein the AZ1-compound is the compound of the following formula ##STR00074##

8. The AZ-component according to claim 1, wherein the AZ-component is selected from the group consisting of AZ2-compound and wherein the AZ2-compound is the compound of the following formula ##STR00075##

9. The AZ-component according to claim 1, wherein the AZ-component is selected from the group consisting of AZ2-compound and wherein the AZ2-compound is the compound of the following formula ##STR00076##

10. The AZ-component according to claim 1, wherein the AZ-component is selected from the group consisting of AZ2-compound and wherein the AZ2-compound is the compound of the following formula ##STR00077##

11. The AZ component according to claim 1, wherein the AZ-component is selected from the group consisting of AZ1-compound, AZ2-compound and mixtures thereof, and wherein the AZ1-compound is the compound of the following formula, ##STR00078## and wherein the AZ2-compound is selected from the group consisting of compounds of the following formulae, ##STR00079##

12. A liquid composition, comprising: i) a liquid medium which is selected from the group consisting of organic solvents, water and a mixture thereof, in an amount of at most 90, wt % on the total weight of the liquid composition; and ii) an AZ-component according to claim 1; and wherein the total amount of all the components that make up the liquid composition totals 100 wt %.

13. The liquid composition according to the claim 12, wherein the liquid composition has a pH determined according to the ISO 976:2013 and according to the description, of at least 7.5 and at most 14.0, with the proviso that the liquid composition comprises water in an amount of at least 20, preferably at least 25, more preferably at least 30, most preferably at least 35 wt % on the total weight of the liquid composition.

14. The liquid composition according to claim 12, wherein the liquid composition comprises a component T selected from the group consisting of: i) organic compounds having a molecular weight determined via MALDI-TOF MS according to the description, lower than 600 Da and comprising at least one aziridine ring, and ii) mixtures thereof, in an amount determined via liquid chromatography coupled with mass spectroscopy (LC-MS) according to the description, of at most 5, preferably at most 0.5, for example at most 0.1, for example at most 0.05 wt % on the total weight of the AZ-compound.

15. The liquid composition according to claim 12, further comprising: iii) a polymer which has an acid value determined according to the ASTM D1639-90(1996)e1 of at least 5 and at most 300 mg KOH/g and wherein the polymer may optionally comprise ionic functional groups.

16. A kit-of-parts comprising parts A and B which are physically separated from each other, wherein: i) the part A comprises a liquid composition according to claim 12, and ii) the part B comprises a polymer which has an acid value determined according to the ASTM D1639-90(1996)e1 in the range from 5 to 300, preferably from 8 to 200, more preferably from 10 to 150 mg KOH/g and wherein the polymer may optionally comprise ionic functional groups, and wherein the part A does not comprise the polymer of the part B, and the part B does not comprise the liquid composition of the part A.

17. A cured form of an AZ-component according to claim 1, or of a liquid composition.

18. An article comprising: i) an AZ-component according to any one of the claims 1-11, or ii) a liquid composition according to claim 12, and/or iii) a cured form.

19. Any one or any combination of the following: i) an AZ-component according to claim 1; ii) a liquid composition; iii) a kit-of-parts; iv) a cured form; v) an article; for use in coatings, paints, inks, varnishes, lubricants, adhesives, additive manufacturing, 3D-printing, textiles, waxes, fuels, photography, plastics, medical compositions, medical devices.

Description

EXAMPLES

[0181] The invention is explained in more detail with reference to the following non-limiting examples.

[0182] All the Examples shown in this section were carried out in a controlled laboratory environment at standard conditions (as these are defined in the specification), a relative humidity of 50±1% and an airflow of 0.1 m/s, unless otherwise explicitly specified.

1.1 Chemicals, Raw Materials and Other Materials

[0183] Triethylamine (purity 99.7%) was supplied by ARKEMA. Propylene imine (purity ≥99.0%) was supplied by Menadiona. Anhydrous potassium carbonate (K.sub.2CO.sub.3; purity ≥99.0%) was supplied by Alfa Aesar. The trimethylolpropane tris(2-methyl-1-aziridinepropionate) (CAS No. 64265-57-2; see structure in Example 1C) was supplied by DSM (commercial product name ‘crosslinker CX-100’). The DESMODUR® N 3600 is a low viscosity aliphatic polyisocyanate (trimer) based on hexamethylene diisocyanate (HDI) (NCO content: 23.0±0.5% (M105-ISO 11909); viscosity at 23° C.: 1200±300 mPa.Math.s (M014-ISO 3219/A.3); color value (hazen): ≤40 (M017-EN 1557); monomeric HDI: ≤0.25% (M106-ISO 10283); equivalent weight: approx. 183; flash point: approx. 159° C. (DIN 53213/1); density at 20° C.: approx. 1.16 g/ml (DIN EN ISO 2811), supplied by Covestro. The DESMODUR® N 3900 is a low viscosity aliphatic polyisocyanate based on hexamethylene diisocyanate (HDI) (NCO content: 23.0±0.5% (M105-ISO 11909); viscosity at 23° C.: 730±100 mPa.Math.s (M014-ISO 3219/A.3); color value (hazen): ≤40 (M017-EN 1557); monomeric HDI: ≤0.25% (M106-ISO 10283); equivalent weight: approx. 179; flash point: approx. 203° C. (DIN 53213/1); density at 20° C.: approx. 1.15 g/ml (DIN EN ISO 2811), supplied by Covestro. The ERISYS® GE-36 is a triglycidyl ether of propoxylated glycerine (see Scheme 1) (EEW: 620-680 g/eq; viscosity: 200-320 cps at 25° C.; hydrolysable chloride: <0.10%; flash point: >93° C., residual epichlorohydrin: <20 ppm) was supplied by CVC Thermoset Specialties (now HUNTSMAN). The ERISYS® GA-240 (see Scheme 2) is glycidyl amine of m-xylelenediamine (CAS No. 63738-22-7) (epoxy equivalent weight (EEW): 95-110 g/eq; specific gravity at 25° C.: 1.14-1.16 g/ml; flash point: >215° C.; colour (Gardner): max. 5; viscosity at 25° C.: 1600-3000 cP) supplied by CVC Thermoset Specialties (now HUNSTMAN). The Cardolite® NC-514S is a di-functional glycidyl ether epoxy resin (see Scheme 3) [reddish brown liquid; color (Gardner): (ASTM D1544); viscosity at 25° C.: 1000-3000 cP (ASTM D2196); epoxy equivalent weight (EEW): 320-420 (ASTM D1652-97); hydrolysable chlorine (%): 0.5 (ASTM D1726-11); volatile loss (% wt): 0.5 (ASTM D2369-98); density at 25° C.: 1.026 Kg/L (ASTM D1475); flash point: >205° C. (ASTM D93)] was supplied by Cardolite Corporation. The EPPALOY® 9000 is tris hydroxyl phenyl ethane (CAS No. 87093-13-8) (see Scheme 4) [average epoxy functionality: 3.0; epoxy equivalent weight (EEW): 160-180 g/eq; viscosity at 72° C.: 5500-6500 cP; colour (Gardner): max. 2) supplied by CVC Thermoset Specialties (now HUNSTMAN]. The bisphenol A diglycidyl ether (CAS No. 1675-54-3) was supplied from Tokyo Chemical Industry Co., Ltd. The N,N-diglycidyl-4-glycidyloxyaniline (CAS No. 5026-74-4) was supplied by Sigma-Aldrich. Mehtylethylketone was supplied by Sigma-Aldrich. The polypropylene glycol with a calculated number average molecular weight (M.sub.n) of 2000 Da and an OH-value of 56±2 mg KOH/g polypropylene glycol), and the polypropylene glycol with a calculated number average molecular weight (M.sub.n) of 1000 Da and an OH-value of 112±2 mg KOH/g polypropylene glycol, were supplied by DOW. The DOWANOL™ DPM Glycol Ether [dipropylene glycol mono methyl ether; CAS No.: 34590-94-8; boiling point 190° C. at 760 mmHg; density 0.948 g/mL; flash point (closed cup): 75° C.; freezing point: −83° C.; molecular weight: 148.2 Da; specific gravity (25° C.): 0.951; surface tension: 28 dynes/cm; viscosity (25° C.): 3.7 cP; vapor pressure (20° C.): 0.28 mmHg; solubility in water (25° C.): infinite (wt %)] is a (mid- to slow evaporating) organic solvent. Any other chemical that is not explicitly mentioned in this paragraph and used in the Examples section (and unless otherwise stated in the specification) has been supplied by Sigma-Aldrich.

##STR00046##

##STR00047##

##STR00048##

##STR00049##

1.2 Preparation of the Polyurethane a and its Aqueous Dispersion (the Latter is Abbreviated as ‘Polyurethane A-AQD’)

[0184] A one-litre flask (equipped with a thermometer and an overhead stirrer), was charged with 29.9 grams of dimethylol propionic acid, 282.1 grams of a polypropylene glycol with a calculated number average molecular weight (M.sub.n) of 2000 Da and an OH-value of 56±2 mg KOH/g polypropylene glycol), 166.5 grams of a polypropylene glycol with a calculated number average molecular weight (M.sub.n) of 1000 Da and an OH-value of 112±2 mg KOH/g polypropylene glycol, and 262.8 grams of isophorone diisocyanate (the number average molecular weight of each of the polyols is calculated from its OH-value according to the equation: M.sub.n=2*56100/[OH-value in mg KOH/g polypropylene glycol). The reaction mixture was placed under N.sub.2 atmosphere, heated to 50° C. and subsequently, 0.07 g dibutyltin dilaurate were added to the reaction mixture. An exothermic reaction was observed; however, proper care was taken in order for the reaction temperature not to exceed 97° C. The reaction was maintained at 95° C. for an hour. The NCO content of the resultant polyurethane A was 7.00% on solids determined according to the ISO 14896 Method A (year 2009) (theoretically 7.44%), and the acid value of the polyurethane A was 16.1±1 mg KOH/g polyurethane A. The polyurethane A was cooled down to 60° C., and 18.7 grams of triethylamine were added, and the resulting mixture was stirred for 30 minutes. Subsequently, an aqueous dispersion of the polyurethane A (abbreviated as ‘polyurethane A-AQD’) was prepared as follows: the thus prepared mixture of the polyurethane A and triethylamine was fed—at room temperature over a time period of 60 minutes- to a mixture of 1100 grams of demineralized water, 19.5 grams of nonylphenol ethoxylate (9 ethoxylate groups), and 4.0 grams of triethylamine. After the feed was completed, the mixture was stirred for additional 5 minutes, and subsequently, 111.2 grams of hydrazine (16 wt % solution in water) were added to the mixture. The aqueous dispersion of the polyurethane A thus prepared was stirred for an additional 1 h.

1.2 Determination of the Molecular Weight of the AZ1- to AZ5-Compounds and of the Component T (Matrix-Assisted Laser Desorption/Ionization on a Time-of-Flight Mass Spectrometry; MALDI-TOF MS)

[0185] All MALDI-ToF-MS spectra were acquired using a Bruker UltrafleXtreme™ MALDI-ToF mass spectrometer. The instrument is equipped with a Nd:YAG laser emitting at 1064 nm and a collision cell (not used for these samples). Spectra were acquired in the positive-ion mode using the reflectron, using the highest resolution mode providing accurate masses (range 60-7000 m/z). Cesium Tri-iodide (range 0.3-3.5 kDa) was used for mass calibration (calibration method: IAV Molecular Characterization, code MC-MS-05). The laser energy was 20%. The samples were dissolved in THF at approx. 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. Potassium trifluoroacetate (KTFA, CAS Number: 2923-16-2) or alternatively sodium iodide was used as salt (NaI, CAS Number 7681-82-5); 10 mg was dissolved in 1 ml THF with a drop of MeOH added. Ratio sample:matrix:salt=10:200:10 (μL), after mixing, 0.5 μL was spot on MALDI plate and 20 allowed to air-dry. Reported signals are the major peaks within 0.5 Da of the calculated mass of the multi-aziridine compounds which are theoretically present in the composition in the largest amounts. In all cases, the reported peaks are the sodium or potassium adducts of the measured ions. The MALDI-TOF MS signals reported correspond to the major peaks of the sodium or potassium adducts of the measured ions of the theoretical formula of a multi-aziridine compound (the sodium and potassium cations. The theoretical formula of a multi-aziridine compound may be determined via analytical techniques well-known to one skilled in the art of analytical chemistry, e.g. NMR spectroscopy and/or liquid chromatography-mass spectroscopy (LC-MS), and/or liquid chromatography-mass spectroscopy-mass spectroscopy (LC-MS-MS), and/or theoretically from its method of preparation (if reactants and conditions are known); once the theoretical formula of a multi-aziridine compound is determined, then its theoretical molecular weight may also be determined.

[0186] The multi-aziridine compounds are identified by comparing the molecular weight which is defined just below (MW), with the exact molecular mass (i.e. the sum of the non-isotopically averaged atomic masses of its constituent atoms) of a theoretical structure, using a maximum deviation of 0.5 Da. In the context of this specification, the molecular weight (MW) attributed to a multi-aziridine compound is calculated from the following equation:

MW=Obs.[M+M.sub.cation]−[M.sub.cation]

wherein
the M.sub.cation is the exact molar mass of the sodium (22.99 Da), or potassium cation (38.96 Da) (depending on which cation was used in the MALDI-TOF MS method), and the Obs.[M+M.sub.cation] is the MALDI-TOF MS signal (peak) which corresponds to the theoretical formula of the multi-aziridine compound.

1.3 Determination of the Genotoxicity (ToxTracker® Assay)

[0187] The genotoxicity was determined according to the ToxTracker® assay (Toxys, Leiden, the Netherlands) as described below. The ToxTracker® assay can be applied for pure substances or for compositions which are the direct products obtained in the preparation of compounds bearing the aziridine ring.

[0188] The ToxTracker assay is a panel of several 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. This methodology uses a two-step approach.

[0189] In the first step a dose range-finding was performed using wild-type mES cells (strain B4418). 20 different concentrations for each compound was tested, starting at 10 mM in DMSO as the highest concentration and nineteen consecutive 2-fold dilutions. Next, the genotoxicity of samples (inventive and comparative examples) was evaluated using specific genes linked to reporter genes for the detection of DNA damage; i.e. Bscl2 (as elucidated by U.S. Pat. No. 9,695,481B2 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 rat S9 liver extract-based metabolizing systems (aroclor1254-induced rats, Moltox, Boone, N.C., USA). The independent cell lines were seeded in 96-well cell culture plates, 24 h after seeding the cells in the 96-well plates, fresh ES cell medium containing the diluted test substance was added to the cells. For each tested compound, five concentrations are tested in 2-fold dilutions. The highest sample concentration will induce significant cytotoxicity (50-70%). In case of no or low cytotoxicity, 10 mM or the maximum soluble mixture concentration is used as maximum test concentration. Cytotoxicity is determined by cell count after 24 h exposure using a Guava easyCyte 10HT flow cytometer (Millipore). GFP reporter induction is always compared to a vehicle control treatment. DMSO concentration is similar in all wells for a particular compound and never exceeds 1%. All compounds were tested in at least three completely independent repeat experiments. Positive reference treatment with cisplatin (DNA damage) was included in all experiments. Metabolic was evaluated by the addition of S9 liver extract. Cells are exposed to five concentrations of the test compound in the presence of S9 and required co-factors (RegenSysA+B, Moltox, Boone, N.C., USA) for 3 h. After washing, cells are incubated for 24 h in fresh ES cell medium. Induction of the GFP reporters is determined after 24 h exposure using a Guava easyCyte 10HT flow cytometer (Millipore). Only GFP expression in single intact cells is determined. Mean GFP fluorescence and cell concentrations in each well are measured, which is used for cytotoxicity assessment. Data were analyzed using ToxPlot software (Toxys, Leiden, the Netherlands). The induction levels reported are at compound concentrations that induce 10%, 25% and 50% cytotoxicity after 3 h exposure in the presence of S9 rat liver extract and 24 h recovery or alternatively after 24 h exposure when not in the presence of S9 rat liver extract. A positive induction level of the biomarkers is defined as equal to or higher than a 2-fold induction in at least one of 10, 25 and 50% cytotoxicity in the absence or presence of the metabolizing system rat S9 liver extract; a weakly positive induction as higher than 1.5-fold and lower than 2-fold induction in at least one of 10, 25 and 50% cytotoxicity (but lower than 2-fold at 10, 25 and 50% cytotoxicity) in the absence or presence of the metabolizing system rat S9 liver extract and a negative as lower than or equal to a 1.5-fold induction at 10, 25 and 50% cytotoxicity in the absence and presence of rat S9 liver extract-based metabolizing systems. In the context of the specification by ‘non-genotoxic’ (or equally ‘not genotoxic’) is meant that the induction level of the biomarkers Bscl2-GFP and Rtkn-GFP is lower than 2-fold—preferably equal to or lower than 1.9-fold, more preferably equal to or lower than 1.8-fold, for example equal to or lower than 1.7-fold, for example equal to or lower than 1.6-fold for example equal to or lower than 1.5-fold at 10, 25 and 50% cytotoxicity in the absence and presence of rat S9 liver extract-based metabolizing systems (aroclor1254-induced rats, Moltox, Boone, N.C., USA).

1.4 Assessment of the Crosslinking Efficiency

[0190] The crosslinking efficiency of organic compounds bearing aziridine ring(s) in liquid compositions [or equally the crosslinking efficiency of liquid compositions comprising organic compounds bearing aziridine ring(s)] was assessed by determining the chemical resistance of films (cured coatings).

[0191] The chemical resistance of a film (cured coating) was tested based on the DIN 68861-1:2011-01. The film was prepared as follows: 0.43 parts of the composition were mixed with 0.57 parts of DOWANOL™ DPM Glycol Ether and incubated at 80° C. for 10 minutes under regular agitation. Subsequently, an amount of the resulting solution was added under continuous stirring to an amount of the polyurethane A-AQD, and the resulting mixture was stirred for additional 30 minutes to thus produce a liquid composition. These amounts were calculated on the basis that the molar ratio of the mol of aziridine rings present in the organic compound (or a mixture of organic compounds) bearing aziridine ring(s), e.g. AZ-component to the mol of carboxylic acid functional groups present in the polyurethane A was equal to 0.9. This liquid composition was filtered and subsequently applied onto Leneta test cards using a 100 μm wire rod applicator. The film was dried for 16 h at 25° C., then annealed at 50° C. for 1 h and subsequently dried for 24 h at 25° C.

[0192] Cotton wool pads (1×1 cm) were soaked in a solution of ethanol: demineralized water (1:1). They were then placed on the films and covered with Petri dishes for 240 minutes. Afterwards, the pads and the Petri dishes were removed; after 1 h the coatings were visually inspected for damages; the extent of damages was assessed according to the following rating scheme: [0193] 5: no visible changes [0194] 4: hardly noticeable changes in shine or colour [0195] 3: slight changes in shine or colour; the structure of the test surface has not changed [0196] 2: heavy changes noticeable; however, the structure of the test surface has remained more or less undamaged. [0197] 1: heavy changes noticeable; the structure of the test surface has changed. [0198] 0: the tested surface was heavily changed or destroyed.

[0199] In the context of this specification, the above integers 0-5 are mentioned as ‘ranking points’.

[0200] The chemical resistance of a reference film (prepared from only polyurethane A-AQD) was poor (this applies for all examples inventive and comparatives shown in the Examples).

1.5 Determination of the pH

[0201] The pH of a sample was determined according to the ISO 976:2013. Samples were measured at room temperature using a Metrohm 691 pH-meter equipped with a combined glass electrode and a PT-1000 temperature sensor. The pH-meter was calibrated using buffer solutions of pH 7.00 and 9.21 prior to use.

1.6 Determination of the Acid Value

[0202] The acid value of a polymer is determined according to the ASTM D1639-90(1996)e1. According to the procedure, the sample was dissolved in a good solvent, was titrated with alcoholic potassium hydroxide solution of a known concentration (KOH). The difference in titration volume between the sample and a blank is the measure of the acid value on solids, according to the following formula:

AV=[(V.sub.blank−V.sub.sample)*N.sub.KOH*56.1]/(W*S/100)

where
AV is the acid number on solids in mg KOH/g solid material, V.sub.blank is the volume of KOH solution used in the blank, V.sub.sample is the volume of KOH solution used in the sample, N.sub.KOH is the normality of the KOH solution, W is the sample weight in grams and S is the solids content of the sample in %. Measurements are performed in duplicate using a potentiometric endpoint on a Metrohm 702SM Titrino titrator (accepting the measurement if the difference between duplicates is <0.1 mg KOH/g solid material).

1.7 Determination of the NCO Content

[0203] The NCO content of a sample is determined based on the ASTM D2572-19 standard. In the procedure, the sample is reacted with excess n-dibutylamine. The excess of n-dibutylamine is subsequently back-titrated with standard 1N hydrochloric acid (HCl). The difference in titration volume between the sample and a blank is the measure of the isocyanate content on solids, according to the following formula:

% NCO.sub.solids=[(V.sub.b−V.sub.m)*N*4.2]/(A*s/100)

where
% NCO.sub.solids is the isocyanate content on solids, V.sub.b is the volume of HCl used in the blank, V.sub.m 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 solids content of the sample in %. Measurements are performed in duplicate using a potentiometric endpoint on a Metrohm 702SM Titrino titrator (accepting the measurement if the difference between duplicates is <0.1%.sub.NCO).
1.8 Determination of the Amount of Component T [Liquid Chromatography Coupled with Mass Spectroscopy (LC-MS)]

[0204] The amount of component T (as the latter is defined in the specification including the claims; wt % on the total weight of the AZ-compound) was determined via liquid chromatography coupled with mass spectroscopy (LC-MS). Initially, a 0.01 wt % solution of sample in methanol was prepared. Subsequently, 0.5 μL of this solution was injected into an Agilent 1290 Infinity II Ultra High Pressure Liquid Chromatography (UHPLC) system equipped with: a) a High Strength Silica (HSS) technology C18 type T3 column supplied by Waters® [100×2.1 mm (length×diameter); 1.8 micron average particle size of the stationary phase] operating at 40° C., and b) an Agilent 6550 iFunnel QTOF detector [ElectroSpray Ionization-Time-of-Flight Mass Spectrometer (ESI-TOF-MS) detector]. Once the sample was injected, then a gradient of a mobile phase [from 80/20 v/v A/B to 1/99 v/v A/B, wherein A was 10 mM CH.sub.3COO.sup.−NH.sub.4.sup.+ (set to pH 9.0 with NH.sub.3) and B was acetonitrile; A and B making up the mobile phase], at a flow rate of 0.5 mL/min, for 10 min, was used to separate the various ingredients of the sample. Subsequently, a gradient of a mobile phase [from 1/99 v/v A/B to 1/49/50 A/B/C, wherein A was 10 mM CH.sub.3COO.sup.−NH.sub.4.sup.+ (set to pH 9.0 with NH.sub.3), B was acetonitrile and C was tetrahydrofuran (THF); A, B and C making up the mobile phase] at a flow rate of 0.5 mL/min, for 5 min was applied to purge the column. Assuming a linear MS response of all the ingredients of the sample over all response ranges and an equal ionization efficiency for all the ingredients of the sample, the signals of the: [0205] total ion current, and [0206] extracted ion chromatograms of the component T,
were integrated.

[0207] The data acquisition was carried out via the MassHunter Build 10.1.48 software supplied by Agilent, while the data processing was carried out via the Qualitative Analysis Build 10.0.10305.0 software, also supplied by Agilent.

[0208] The amount of component T (wt % on the total weight of the AZ-compound) was determined by dividing the integrals of the extracted ion chromatograms of the component T by the integrals of the total ion current, multiplied by 100.

1.9 Determination of the Amount of Chloride

[0209] The amount of chloride in a liquid composition was determined according to the ASTM D1726-11(2019).

2 Inventive Examples

Example 1

[0210] 100 grams of ERISYS® GE-36, 26.5 grams of propylene imine and 5 grams of potassium carbonate were charged to a reaction flask equipped with a thermometer and a condenser connected to a cryostat (3° C.). The mixture was stirred with a mechanical upper stirrer under a nitrogen atmosphere. The mixture was then heated to 80° C. Samples were taken at regular intervals, and the reaction progress was monitored using a .sup.1H-NMR until no signal (chemical shifts) correlated to the epoxide protons from the multifunctional epoxide was observed. The reaction mixture was diluted with toluene and filtered. The solvent and the excess of propylene imine were removed from the filtrate in vacuo to obtain from the filtrate was removed in vacuo to obtain a clear highly viscous liquid. The theoretical formula of the thus prepared (aziridinyl hydroxy)-functional organic compound is shown below (wherein x+y+z=33), and the theoretical molecular weight was calculated to be 2346.68 Da.

##STR00050##

The molecular weight as defined and determined via MALDI-TOF MS—as this is defined and described in the specification—was 2346.50 Da (=Obs. [M+M.sub.Na+]−[M.sub.Na+]).

[0211] The crosslinking efficiency of the (aziridinyl hydroxy)-functional organic compound obtained above (and its liquid composition) was very good, and given the ToxTracker® assay results on the genotoxicity shown in the table below, this (aziridinyl hydroxy)-functional organic compound was not genotoxic.

TABLE-US-00001 Without S9 rat liver extract With S9 rat liver extract Bscl 2 Rtkn Bscl 2 Rtkn concentration 10 25 50 10 25 50 10 25 50 10 25 50 −fold induction 1.1 1.2 1.2 1.1 1.3 1.1 1.1 1.2 1.1 1.2 1.3 1.1

Example 2

[0212] 75 grams of EPALLOY® 9000 was dissolved in 75 mL of toluene and charged to a reaction flask equipped with a thermometer and a condenser connected to a cryostat (3° C.). Next, 55 grams of propylene imine and 5 grams of potassium carbonate were added to the flask. The mixture was stirred with a mechanical upper stirrer under a nitrogen atmosphere. The mixture was than heated to 80° C. Samples were taken at regular intervals and the reaction progress was monitored using a .sup.1H-NMR until no signal (chemical shifts) correlated to the epoxide protons from the multifunctional epoxide was observed. After 22 hours of reaction, the mixture was filtered. The solvent and excess of propylene imine were removed from the filtrate in vacuo to obtain an off-white solid. The theoretical formula of the thus prepared (aziridinyl hydroxy)-functional organic compound is shown below and the theoretical molecular weight was calculated to be 645.38 Da.

##STR00051##

The molecular weight as defined and determined via MALDI-TOF MS—as this is defined and described in the specification—was 645.37 Da (=Obs. [M+M.sub.Na+]−[M.sub.Na+]).

[0213] The crosslinking efficiency of the (aziridinyl hydroxy)-functional organic compound obtained above (and its liquid composition) was good, and given the ToxTracker® assay results on the genotoxicity shown in the table below, this (aziridinyl hydroxy)-functional organic compound was not genotoxic.

TABLE-US-00002 Without S9 rat liver extract With S9 rat liver extract Bscl 2 Rtkn Bscl 2 Rtkn concentration 10 25 50 10 25 50 10 25 50 10 25 50 −fold induction 1.1 1.4 1.5 1.1 1.3 1.3 1.1 1.3 1.7 1.2 1.5 1.4

Example 3

[0214] 130 grams of DESMODUR® N 3600 was dissolved in 130 grams of toluene, charged to a reaction flask equipped with a thermometer and heated to 50° C. Next, 0.05 grams of triethylamine was added to the flask and over the course of 90 minutes 52 grams of glycidol was slowly added to the reaction mixture, while making sure that the reaction temperature stayed constant between 55-58° C. After stirring for another 60 minutes at this temperature, the mixture was cooled down to room temperature and stirred for 18 hours at room temperature. The solvent was removed in vacuo and the resulting yellowish oil was transferred to a reaction flask equipped with a thermometer and a condenser connected to a cryostat (3° C.). Next, 200 grams of toluene, 150 grams of propylene imine and 5 grams of potassium carbonate were added to the flask. The mixture was stirred with a mechanical upper stirrer under a nitrogen atmosphere. The mixture was than heated to 60° C. Samples were taken at regular intervals and the reaction progress was monitored using a .sup.1H-NMR until no signal (chemical shifts) correlated to the epoxide protons from the multifunctional epoxide was observed. After 18 hours of reaction, the mixture was filtered. The solvent and excess of propylene imine were removed from the filtrate in vacuo to obtain a high viscous liquid. The theoretical formula of the thus prepared (aziridinyl hydroxy)-functional organic compound is shown below and the theoretical molecular weight was calculated to be 897.55 Da.

##STR00052##

The molecular weight as defined and determined via MALDI-TOF MS—as this is defined and described in the specification—was 897.58 Da (=Obs. [M+M.sub.Na+]−[M.sub.Na+]).

[0215] The crosslinking efficiency of the (aziridinyl hydroxy)-functional organic compound obtained above (and its liquid composition) was good, and given the ToxTracker® assay results on the genotoxicity shown in the table below, this (aziridinyl hydroxy)-functional organic compound was not genotoxic.

TABLE-US-00003 Without S9 rat liver extract With S9 rat liver extract Bscl 2 Rtkn Bscl 2 Rtkn concentration 10 25 50 10 25 50 10 25 50 10 25 50 −fold induction 1.1 1.3 1.5 1.2 1.7 1.9 1.2 1.5 1.5 1.1 1.5 1.7

Example 4

[0216] 30.0 grams of Cardolite® NC-514S, 19.2 grams of propylene imine, 30 grams of toluene and 3 grams of potassium carbonate were charged to a reaction flask equipped with a thermometer and a condenser connected to a cryostat (3° C.). The mixture was stirred with a mechanical stirrer under a nitrogen atmosphere. The mixture was than heated to 70° C. Samples were taken at regular intervals and the reaction progress was monitored using a .sup.1H-NMR until no signal (chemical shifts) correlated to the epoxide protons from the multifunctional epoxide was observed. After 20 hours of reaction, the mixture was diluted with toluene and filtered. The solvent and the excess of propylene imine were removed from the filtrate in vacuo to obtain to obtain a high viscous brownish oil. The theoretical formula of the thus prepared (aziridinyl hydroxy)-functional organic compound is shown below and the theoretical molecular weight was calculated to be 622.47 Da.

##STR00053##

The molecular weight as defined and determined via MALDI-TOF MS—as this is defined and described in the specification—was 622.43 Da (=Obs. [M+M.sub.Na+]−[M.sub.Na+]).

[0217] The crosslinking efficiency of the (aziridinyl hydroxy)-functional organic compound obtained above (and its liquid composition) was good, and given the ToxTracker® assay results on the genotoxicity shown in the table below, this (aziridinyl hydroxy)-functional organic compound was not genotoxic.

TABLE-US-00004 Without S9 rat liver extract With S9 rat liver extract Bscl 2 Rtkn Bscl 2 Rtkn concentration 10 25 50 10 25 50 10 25 50 10 25 50 −fold induction 1.2 1.3 1.3 1.2 1.4 1.7 1.3 1.5 1.5 1.6 1.8 1.7

3. Comparative Examples

Example 1C

[0218] The trimethylolpropane tris(2-methyl-1-aziridinepropionate) (commercial product name ‘crosslinker CX-100’) has the following structure:

##STR00054##

The theoretical molecular weight was calculated to be 467.30 Da.

[0219] The crosslinking efficiency of the trimethylolpropane tris(2-methyl-1-aziridinepropionate) (and its liquid composition) was very good and given the ToxTracker® assay results on the genotoxicity shown in the table below, the trimethylolpropane tris(2-methyl-1-aziridinepropionate) was genotoxic.

TABLE-US-00005 Without S9 rat liver extract With S9 rat liver extract Bscl 2 Rtkn Bscl 2 Rtkn concentration 10 25 50 10 25 50 10 25 50 10 25 50 −fold induction 1.2 1.5 2.0 1.4 2.0 3.2 1.7 2.3 2.1 3.0 4.3 3.4

Example 2C

[0220] 75 grams of ERISYS® GA-240, 80 grams of propylene imine and 5 grams of potassium carbonate were charged to a reaction flask equipped with a thermometer and a condenser connected to a cryostat (3° C.). The mixture was stirred with a mechanical upper stirrer under a nitrogen atmosphere. The mixture was than heated to 71° C. Samples were taken at regular intervals and the reaction progress was monitored using a .sup.1H-NMR until no signal (chemical shifts) correlated to the epoxide protons from the multifunctional epoxide was observed. After 22 hours of reaction, the mixture was diluted with toluene and filtered. The solvent and the excess of propylene imine were removed from the filtrate in vacuo to obtain a clear, transparent solid. The theoretical formula of the thus prepare multi-aziridine compound is shown below and the theoretical molecular weight was calculated to be 588.44 Da.

##STR00055##

The molecular weight as defined and determined via MALDI-TOF MS—as this is defined and described in the specification—was 588.48 Da (=Obs. [M+M.sub.Na+]−[M.sub.Na+]).

[0221] The crosslinking efficiency of the multi-aziridine compound obtained above (and its liquid composition) was good, and given the ToxTracker® assay results on the genotoxicity shown in the table below, this multi-aziridine compound was genotoxic.

TABLE-US-00006 Without S9 rat liver extract With S9 rat liver extract Bscl 2 Rtkn Bscl 2 Rtkn concentration 10 25 50 10 25 50 10 25 50 10 25 50 −fold induction 1.3 1.8 2.6 1.6 2.5 3.9 1.3 1.7 2.5 1.8 3.0 5.1

Example 3C

[0222] 24.0 grams of N,N-dilycidyl-4-glycidyloxyaniline, 42.0 grams of propylene imine, 30 grams of toluene and 3 grams of potassium carbonate were charged to a reaction flask equipped with a thermometer and a condenser connected to a cryostat (3° C.). The mixture was stirred with a mechanical stirrer under a nitrogen atmosphere. The mixture was than heated to 70° C. Samples were taken at regular intervals and the reaction progress was monitored using a .sup.1H-NMR until no signal (chemical shifts) correlated to the epoxide protons from the multifunctional epoxide was observed. After 24 hours of reaction, the mixture was diluted with toluene and filtered. The solvent and the excess of propylene imine were removed from the filtrate in vacuo to obtain a highly viscous yellow material. The theoretical formula of the thus prepare multi-aziridine compound is shown below and the theoretical molecular weight was calculated to be 448.30 Da.

##STR00056##

[0223] The molecular weight as defined and determined via MALDI-TOF MS—as this is defined and described in the specification—was 448.29 Da (=Obs. [M+M.sub.Na+]−[M.sub.Na+]).

[0224] This compound was disclosed in U.S. Pat. No. 3,329,674 in cl. 2, II. 29-39.

[0225] The crosslinking efficiency of the multi-aziridine compound obtained above (and its liquid composition) was good, and given the ToxTracker® assay results on the genotoxicity shown in the table below, this multi-aziridine compound was genotoxic.

TABLE-US-00007 Without S9 rat liver extract With S9 rat liver extract Bscl 2 Rtkn Bscl 2 Rtkn concentration 10 25 50 10 25 50 10 25 50 10 25 50 −fold induction 1.1 1.3 1.7 1.7 2.3 3.3 1.2 1.4 2.2 1.8 2.6 5.1

Example 4C

[0226] 299 grams of bisphenol A diglycidyl ether, 250 grams of toluene, 255 grams of propylene imine and 10 grams of potassium carbonate were charged to a reaction flask equipped with a thermometer and a condenser connected to a cryostat (3° C.). The mixture was stirred with a mechanical upper stirrer under a nitrogen atmosphere. The mixture was than heated to 70° C. Samples were taken at regular intervals and the reaction progress was monitored using a .sup.1H-NMR until no signal (chemical shifts) correlated to the epoxide protons from the multifunctional epoxide was observed. After 19 hours of reaction, the mixture was filtered. The solvent and the excess of propylene imine were removed from the filtrate in vacuo to obtain a highly viscous liquid. The theoretical formula of the thus prepare multi-aziridine compound is shown below and the theoretical molecular weight was calculated to be 454.28 Da.

##STR00057##

The molecular weight as defined and determined via MALDI-TOF MS—as this is defined and described in the specification—was 454.26 Da (=Obs. [M+M.sub.Na+]−[M.sub.Na+]).

[0227] The crosslinking efficiency of the multi-aziridine compound obtained above (and its liquid composition) was good, and given the ToxTracker® assay results on the genotoxicity shown in the table below, this multi-aziridine compound was genotoxic.

TABLE-US-00008 Without S9 rat liver extract With S9 rat liver extract Bscl 2 Rtkn Bscl 2 Rtkn concentration 10 25 50 10 25 50 10 25 50 10 25 50 −fold induction 1.1 1.2 1.9 1.0 1.9 2.8 1.1 1.2 2.1 1.1 2.0 3.1

4. Conclusion

[0228] The U.S. Pat. No. 3,329,674 to Thiokol Chemical Corporation disclosed low molecular weight aziridinyl derivatives of polyfunctional epoxides. The molecular weight of these aziridinyl derivatives was well below 600 Da as explained in the specification. The U.S. Pat. No. 3,329,674 did not disclose (aziridinyl hydroxy)-functional organic compounds having a molecular weight of at least 600 and at most 10000 Da. The U.S. Pat. No. 3,329,674 failed to provide for (aziridinyl hydroxy)-functional organic compounds (and its liquid compositions) that would be non-genotoxic and have at least good crosslinking efficiency. Evidence for that is the Example 3C shown in the specification, which was genotoxic.

[0229] Upon comparing the results of the inventive Examples 1 to 4 and those of the comparative Examples 1C to 4C, it is evident that only the AZ-component of the invention (and the liquid compositions of the invention) were not genotoxic and had at least good crosslinking efficiency.