Curing agent based on isophorone diisocyanate oligomers

Abstract

The invention relates to a curing agent based on isophorone diisocyanate oligomers, comprising 25 to 70 wt.% isophorone diisocyanate oligomers, optionally in the form of reaction products with at least one polyol, 25 to 75 wt.% dimethacrylates of formula (I), and 0 to 30 wt.% further substances. The curing agent is preferably used for curing polyurethane or polyurea coatings. It allows for light-stable coatings with low viscosity, rapid curing, high strength alongside high ductility and excellent weathering resistance.

Description

[0001] HARDENER BASED ON ISOPHORON DIISOCYANATE OLIGOMERS

[0002] Technical field

[0003] The invention relates to a hardener based on isophorone diisocyanate oligomers and its use for polyurethane or polyurea coatings.

[0004] State of the art

[0005] Isophorone diisocyanate (IPDI) is a commercial, room-temperature liquid aliphatic diisocyanate widely used as a hardener in the polyurethane industry. It enables the production of products with long working times, high final strength, high glass transition temperatures, and high weather and UV stability. To obtain products without hazard labeling, the free IPDI content must not exceed 0.1% by weight. Oligomeric forms of IPDI also exist, particularly trimers containing isocyanurate groups. Products with such IPDI oligomers instead of monomeric IPDI do not require hazard labeling. However, IPDI oligomers are solid at room temperature, which presents some challenges in their use. While the use of organic solvents to dissolve the solid oligomers is common, it causes undesirable VOC emissions. Another option is to dissolve IPDI oligomers in an isocyanate-containing polymer.However, a preparation obtained in this way is highly viscous and therefore not suitable for coatings that are to be applied in a thin layer or by means of a spraying process.

[0006] WO 2021 / 123107 describes polyurea coatings with room-temperature liquid derivatives of diphenylmethane diisocyanate (MDI) as a hardener. Such coatings based on aromatic diisocyanates exhibit limited light stability and are unsuitable for many applications. US 2008 / 0229976 describes polyurea coatings with oligomers of 1,6-hexane diisocyanate (HDI) as a hardener. While HDI oligomers are room-temperature liquid and can therefore be used without organic solvents, the achievable storage stability, strength, and glass transition temperatures are limited, and the weather resistance of such coatings could be improved. US 2013 / 0337072 describes core-shell particles with controlled release of the antibiotic content. Example 1 describes the preparation of a hydrophobic solution from 3-iodo-2-propynyl butylcarbamate, methyl methacrylate, ethylene glycol dimethacrylate, IPDI oligomer and dilauroyl peroxide.Such a solution is not suitable for curing polyurethane or polyurea coatings.

[0007] Description of the invention

[0008] The object of the present invention is therefore to provide a hardener based on isophorone diisocyanate oligomers which overcomes the disadvantages of the prior art with regard to VOC emissions and high viscosity and enables the use of IPDI oligomers in liquid form at room temperature for curing polyurethane or polyurea coatings.

[0009] Surprisingly, this problem is solved by the hardener described in claim 1, comprising isophorone diisocyanate oligomers and dimethacrylates of formula (I). The dimethacrylates of formula (I) are very low-viscosity and are able to readily dissolve a surprisingly high amount of IPDI oligomer. The hardener according to the invention exhibits a surprisingly low viscosity and very good storage stability. When used for curing polyurethane or polyurea coatings, the dimethacrylates largely remain in the cured coating by being converted to higher molecular weight compounds through autoxidation or reaction with amine groups. This results in no undesirable emissions.

[0010] The hardener according to claim 1 enables light-stable polyurethane or polyurea coatings with very good storage stability, low odor, low viscosity, fast curing, high strength with high elongation, high glass transition temperature, and excellent weather resistance. Such coatings can be readily applied as a spray coating or in a thin layer as a self-leveling coating and are particularly suitable as a topcoat.

[0011] Further aspects of the invention are the subject of further independent claims. Particularly preferred embodiments of the invention are the subject of dependent claims. Ways of carrying out the invention

[0012] The invention relates to a hardener based on isophorone diisocyanate oligomers, comprising the entire hardener.

[0013] - 25 to 70 wt% isophorone diisocyanate oligomers, optionally in the form of reaction products with at least one polyol,

[0014] - 25 to 75 wt% dimethacrylates of formula (I),

[0015]

[0016] where A represents a divalent alkylene residue with 2 to 12 carbon atoms or a polyether residue with 4 to 14 carbon atoms, and

[0017] - 0 to 30% by weight of other substances.

[0018] Substances in which two, three or four, especially three, isophorone diisocyanate molecules are linked to form a polyisocyanate are called "isophorone diisocyanate oligomers", as is particularly the case with allophanates, isocyanurates, uretdiones or iminooxadiazinde ions.

[0019] Substance names beginning with "Poly", such as polyamine, polyol or polyisocyanate, denote substances that contain two or more of the functional groups appearing in their name per molecule.

[0020] An amine group bonded to a single organic residue and bearing two hydrogen atoms is called "primary", an amine group bonded to two organic residues, which may also be part of a ring together, and bearing one hydrogen atom is called "secondary", and an amine group bonded to three organic residues, which may also be part of one or more rings in pairs or groups of three, and bearing no hydrogen atom is called "tertiary".

[0021] The "NCO content" refers to the percentage of isocyanate groups by weight. "Organic solvents" are low-viscosity organic liquids that do not polymerize during the curing of polyurethane or polyurea coatings and are not incorporated into the cured coating. A composition is considered "storage-stable" if it can be stored at room temperature in a suitable container for an extended period, typically at least three months up to six months or more, without its application or performance characteristics changing to a degree relevant to its use.

[0022] The term "molecular weight" refers to the molar mass (in grams per mole) of a molecule. The "mean molecular weight" is the number-average molecular weight (M) of the molecules. n) a polydisperse mixture of oligomeric or polymeric molecules. It is determined by gel permeation chromatography (GPC) against polystyrene as a standard.

[0023] The term "processing time" refers to the time span between mixing the components of a curable composition and the gelling of the mixed composition.

[0024] A temperature of 23 °C is referred to as "room temperature".

[0025] All industry standards and norms mentioned in the document refer to the versions valid at the time of the initial application.

[0026] Weight percent (wt%) denotes the mass fraction of a component of a composition or molecule, relative to the entire composition or molecule, unless otherwise specified. The terms "mass" and "weight" are used synonymously in this document.

[0027] Isophorone diisocyanate oligomers preferably contain isocyanurate groups. They may also contain uretdione and / or iminooxadiazindione groups. Such IPDI oligomers are commercially available in solid form as granules, for example as Vestanat® T 1890 / 100 (from Evonik).

[0028] IPDI oligomers are also available in liquid form dissolved in an organic solvent, but the use of such grades is undesirable within the scope of this invention because they introduce significant amounts of organic solvents, which cause undesirable VOC emissions when polyurethane or polyurea coatings formulated with them are used. The preferred dimethacrylate is that of formula (I) selected from the list consisting of 1,2-ethanediol dimethacrylate, 1,2-propanediol dimethacrylate, 1,3-propanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol dimethacrylate, neopentylglycol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,8-octanediol dimethacrylate, 1,10-decanediol dimethacrylate, 1 ,12-dodecanediol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, tripropylene glycol dimethacrylate and tetrapropylene glycol dimethacrylate.

[0029] The residue A in formula (I) preferably represents a divalent alkylene residue with 2 to 6 C atoms or a polyether residue with 4 to 6 C atoms.

[0030] The dimethacrylate of formula (I) is particularly preferred, thus selected from the list consisting of 1,2-ethanediol dimethacrylate, 1,2-propanediol dimethacrylate, 1,3-propanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate and dipropylene glycol dimethacrylate.

[0031] Of these, 1,2-ethanediol dimethacrylate, 1,4-butanediol dimethacrylate or triethylene glycol dimethacrylate are particularly preferred.

[0032] IPDI oligomers can be easily and quickly dissolved with 1,2-ethanediol dimethacrylate or 1,4-butanediol dimethacrylate, resulting in hardeners with particularly low viscosity.

[0033] Triethylene glycol dimethacrylate is particularly easy and quick to dissolve IPDI oligomers, resulting in hardeners with very low viscosity.

[0034] Preferably, the NCO content, based on the total hardener, is in the range of 4.3 to 12.1 wt%, particularly 5 to 11 wt%. The NCO content is determined, in particular, by reacting the isocyanate groups with an excess of dibutylamine and back-titrating the unreacted dibutylamine with aqueous hydrochloric acid. Preferably, the hardener has a viscosity at 23 °C of 0.1 to 10 Pa·s, more preferably 0.2 to 5 Pa·s, determined by a cone-plate rotational viscometer with a shear rate of 50 s⁻¹. _1 .

[0035] In a preferred embodiment of the invention, the hardener contains isophorone diisocyanate oligomers proportionally in the form of reaction products with at least one polyol, preferably with at least one diol having an OH number of 28 to 280 mg KOH / g, in particular 56 to 180 mg KOH / g.

[0036] The reaction was preferably carried out in the presence of the dimethacrylate of formula (I) in which the IPDI oligomers are dissolved.

[0037] The reaction preferably took place in a molar NCO / OH ratio of at least 5 / 1, preferably in a molar NCO / OH ratio of 5 / 1 to 25 / 1, in particular 6 / 1 to 20 / 1.

[0038] The reaction preferably took place at a temperature of 20 to 140 °C, in particular 40 to 120 °C, optionally in the presence of a suitable catalyst.

[0039] Such a hardener contains reaction products of IPDI oligomers with diols, unreacted IPDI oligomers, and dimethacrylates of formula (I). Typical reaction products have formula (II), where P represents the residue of the diol after removal of the two OH groups and D represents the residue of isophorone diisocyanate after removal of the two NCO groups.

[0040]

[0041] A hardener containing such reaction products of formula (II) enables polyurethane or polyurea coatings with particularly high elasticity. The diol selected from the list consisting of polyether diols, polyester diols and polycarbonate diols is preferred.

[0042] Particularly preferred are polyetherdiols, especially those with repeating units selected from oxy-1,2-propylene, oxy-1,3-propylene, oxy-1,4-butylene, oxy-1,2-butylene, and oxyphenylethylene. Additionally, oxyethylene units may be present, in particular a maximum of 25 wt% oxyethylene units based on the total weight of the polyetherdiol.

[0043] Preferred are poly(oxy-1,2-propylene)diols, ethylene oxide-terminated poly(oxy-1,2-propylene)diols, poly(oxy-1,3-propylene)diols or poly(oxy-1,4-butylene)diols.

[0044] Poly(oxy-1,2-propylene)diols are most preferred.

[0045] Polyester diols are particularly preferred, especially liquid reaction products at room temperature of dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, cortic acid, azelaic acid, sebacic acid or dodecanedicarboxylic acid, with alcohols such as 1,2-ethanediol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol or isosorbide.

[0046] Preferably, the hardener contains, in relation to the total hardener

[0047] - 40 to 65 wt% isophorone diisocyanate oligomers, optionally in the form of reaction products with at least one diol having an OH number of 28 to 280 mg KOH / g, preferably 56 to 180 mg KOH / g,

[0048] - 30 to 60 wt%, in particular 40 to 55 wt%, dimethacrylates of formula (I), and

[0049] - 0 to 20 wt%, preferably 0 to 10 wt%, in particular 0 to 5 wt%, other substances

[0050] Other suitable substances include, in particular, other polyisocyanates, dyes, fillers, pigments, plasticizers, or additives such as wetting agents, leveling agents, defoamers, or deaerators. A suitable polyisocyanate is, in particular, an oligomer of 1,6-hexane diisocyanate, especially an isocyanurate.

[0051] Particularly suitable as fillers, pigments or plasticizers are the following listed as possible components of polyurethane or polyurea coatings.

[0052] Preferably, the hardener contains no or only a very low content of organic solvents with a boiling point at normal pressure of less than 250 °C. Preferably, the hardener contains less than 1% by weight, more preferably less than 0.5% by weight, and particularly less than 0.1% by weight, of such organic solvents. This enables polyurethane or polyurea coatings with very low emissions.

[0053] Such undesirable solvents in significant quantities include, in particular, acetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, cyclohexanone, butyl acetate, methoxypropyl acetate, dibutyl ether, toluene, xylene, ethanol, naphtha, white spirit, or petroleum ether.

[0054] Another aspect of the invention is a method for producing the described hardener, comprising the steps

[0055] (i) Presenting the dimethacrylate of formula (I),

[0056] (ii) Addition of the isophorone diisocyanate oligomers,

[0057] (iii) Stir the mixture until the isophorone diisocyanate oligomers are completely dissolved,

[0058] (iv) If necessary, add at least one polyol and allow to react until all OH groups have reacted.

[0059] Steps (ii) and (iii) can be carried out at ambient temperature or at elevated temperature, in particular at a temperature of 15 to 100 °C, preferably at 20 to 90 °C, and particularly at 40 to 80 °C.

[0060] If step (iv) is carried out, it can be performed directly after step (iii), or the hardener obtained from step (iii) can be stored in a moisture-proof sealed container until step (iv) is carried out. Preferably, step (iv) is carried out at a temperature of 20 to 120 °C, particularly 40 to 100 °C, optionally in the presence of a suitable catalyst. Preferably, an amount of polyol is added in step (iv) such that the molar NCO / OH ratio is at least 5:1, particularly 5:1 to 25:1, preferably 6:1 to 20:1. This ensures that a significant portion of the IPDI oligomers remains unreacted, and the hardener obtained ultimately has a low, easily manageable viscosity.

[0061] The hardener obtained is stored in a moisture-proof sealed container until use.

[0062] The resulting hardener is shelf-stable. It can be stored at room temperature for several months, up to six months or more, without losing its usability.

[0063] The hardener is low-viscosity and contains aliphatic isocyanate groups. This makes it particularly suitable for curing compositions containing reactive groups that are reactive with isocyanate groups. In particular, the hardener is suitable for curing polyurethane or polyurea coatings.

[0064] Another object of the invention is the use of the described hardener for curing a composition containing reactive groups selected from hydroxyl groups, primary amine groups, secondary amine groups, aldimine groups, ketimine groups and oxazolidine groups.

[0065] In the case of aldimine groups, ketimine groups or oxazolidine groups, additional moisture is required for curing.

[0066] The ratio of the number of isocyanate groups to the sum of the number of hydroxyl groups, primary amine groups, secondary amine groups, aldimine groups, ketimine groups, and oxazolidine groups is preferably in the range of 0.5 to 1.5, particularly 0.8 to 1.3. The hardener is preferably used for curing a composition containing primary or secondary amine groups. The ratio between the number of isocyanate groups and the number of primary or secondary amine groups is preferably below 1. This allows amine groups not reacted by isocyanate groups to react with methacrylate groups, thereby incorporating at least some of the dimethacrylates present into the cured polymer.

[0067] Preferably, the composition contains a catalyst for the autoxidation of methacrylates, in particular a copper, iron, or zinc catalyst. This prevents the release of dimethacrylate of formula (I) from the cured composition.

[0068] A further object of the invention is a curable coating comprising - a first component containing at least one polyol and / or at least one polyamine with at least two primary or secondary amine groups, and

[0069] - a second component containing or consisting of the described hardener.

[0070] Suitable as polyols are in particular

[0071] - Polyether polyols, in particular polyoxyalkylene diols and / or polyoxyalkylene triols, especially polymerization products of ethylene oxide or 1,2-propylene oxide or 1,2- or 2,3-butylene oxide or oxetane or tetrahydrofuran or mixtures thereof, polymerized using a starter molecule with two or more active hydrogen atoms, as well as polyether polyols with styrene-acrylonitrile (SAN) particles or polyurea or polyhydrazodicarbonamide (PHD) particles dispersed therein. Preferred polyether polyols are polyoxypropylene diols, polyoxypropylene triols, or ethylene oxide-terminated polyoxypropylene diols or triols, which, after completion of the polypropoxylation reaction with ethylene oxide, have been further alkoxylated and thereby ultimately exhibit primary hydroxyl groups. Preferred polyether polyols have a degree of unsaturation of less than 0.02 meq / g, in particular less than 0.01 meq / g.

[0072] - Polyester polyols, in particular from the polycondensation of hydroxycarboxylic acids, from lactones such as s-caprolactone with di- or trihydric alcohols as starters, or in particular from the esterification of di- or trihydric alcohols with organic dicarboxylic acids.

[0073] - Polycarbonate polyols, especially from the reaction of di- or trihydric alcohols with dialkyl carbonates, diaryl carbonates or phosgene.

[0074] - Polyether polyester polyols

[0075] - Polyacrylate or polymethacrylate polyols,

[0076] - Polyhydroxy functional fats and oils, for example natural fats and oils, in particular castor oil or derivatives of castor oil, or

[0077] - Polyhydrocarbon polyols, especially polybutadiene polyols.

[0078] Particularly preferred are polyoxypropylene diols or triols or ethylene oxide-terminated polyoxypropylene diols or triols.

[0079] Polyols with an OH number of 28 to 550 mg KOH / g are preferred.

[0080] Also suitable as polyols are so-called chain extenders, such as in particular 1,2-ethanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,7-heptanediol, 1,8-octanediol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, or triethylene glycol. Such chain extenders are preferably present in combination with at least one of the aforementioned polymeric polyols.

[0081] Preferably, the first component contains at least one polyamine with at least two primary or secondary amine groups.

[0082] Suitable polyamines include, in particular,

[0083] - Aromatic diamines, such as in particular 1,3-phenylenediamine, 1,4-phenylenediamine, 2,4(6)-toluenediamine, 3,5-diethyl-2,4(6)-toluenediamine (DETDA), 3,5-dimethylthio-2,4(6)-toluenediamine, 4,4'-diaminodiphenylmethane (MDA), 3,3',5,5'-tetraethyl-4,4'-diaminodiphenylmethane, or aromatic diamines with secondary amine groups, for example available under the trade name Unilink® (from Palmer Holland), in particular N,N'-bis(2-butyl)-1,4-phenylenediamine or N,N'-bis(2-butyl)-4,4'-diaminodiphenylmethane,

[0084] - Bisam inobenzoate of poly(oxy-1,4-butylene)diols, for example available under the trade name Versalink® P (from Evonik),

[0085] - Polyaspartates, for example available under the trade name Desmophen® NH (from Covestro),

[0086] - Polyether diamines or triamines, for example available under the trade name Jeffamine® D or T (from Huntsman), especially medium molecular weight polyoxypropylenediamines Mn from 200 to 4,000 g / mol or medium molecular weight polyoxypropylenetriamines M n from 300 to 5,000 g / mol, - polyether diamines or triamines with secondary amine groups, for example available under the trade name Jeffamine® SD or ST (from Huntsman), - polyaminoamides, especially from the condensation of dimer fatty acids with polyamines, for example available under trade names such as Versamid® (from Huntsman) or Merginamid® (from Worlee),

[0087] - Dimer fatty acid-based amines, for example available under the trade name Priamine® (from Cargill), as well as

[0088] - commercially available diamines with aliphatically bonded amine groups, such as in particular N,N'-bis(2-propyl)isophoronediamine, N,N'-dibenzyl-1,2-ethanediamine, N-benzyl-1,2-ethanediamine, N-methyl-1,3-propanediamine, isophoronediamine, 1,5-pentanediamine, 1,6-hexanediamine, 2,2(4),4-trimethyl-1,6-hexanediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 2(4)-methyl-1,3-diaminocyclohexane, bis(4-aminocyclohexyl)methane, Bis(4-amino-3-methyl-cyclohexyl)methane or 1,3-bis(aminomethyl)benzene.

[0089] In addition to at least one polyamine with at least two primary or secondary amine groups, the first component may contain at least one aldimine or ketimine or oxazolidine, in particular at least one aldimine. Such a coating has a longer processing time. Suitable aldimines are derived in particular from isophorone diamine, 1,5-pentanediamine, 1,6-hexanediamine, 2,2(4),4-trimethyl-1,6-hexanediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 2(4)-methyl-1,3-diaminocyclohexane, bis(4-aminocyclohexyl)methane or 1,3-bis(aminomethyl)benzene, and aldehydes such as, in particular, isobutyraldehyde, pivalaldehyde, 2-methylbutanal, 2-ethylbutanal, 2-methylpentanal, 2-ethylhexanal, octanal, nonanal. Decanal, undecanal, 2-methyl-undecanal, dodecanal, 2-phenyl-propanal, cyclopentanecarboxaldehyde, cyclohexanecarboxaldehyde, benzaldehyde or a substituted benzaldehyde.

[0090] Particularly preferred is N,N'-diisobutylideneisophoronediamine, commercially available as Vestamin® A-139 (from Evonik), or N,N'-dibenzylidenepolyoxypropylenediamine with medium molecular weight M n from 400 to 600 g / mol, commercially available as Aldirez® BH (by Incorez).

[0091] Coatings are also possible which contain in the first component a combination of at least one of the aforementioned polyols and at least one polyamine and / or at least one aldimine, wherein the polyamines or aldimines already mentioned are preferred.

[0092] Preferably, the first component contains at least one copper, iron, or zinc catalyst. Such a catalyst catalyzes the autoxidation of methacrylates. This prevents the release of dimethacrylates of formula (I) from the cured coating.

[0093] Preferably, the curable coating contains at least one further component selected from the list consisting of catalysts, fillers, pigments, adhesion promoters, stabilizers, defoamers and wetting agents.

[0094] Suitable catalysts are, in particular, catalysts for the reaction of hydroxyl groups with isocyanate groups, especially an organotin(IV) compound such as, in particular, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dichloride, dibutyltin diacetylacetonate, dimethyltin dilaurate, dioctyltin diacetate, dioctyltin dilaurate, or dioctyltin diacetylacetonate; compounds of iron(III), bismuth(III), or zirconium(IV), in particular complex compounds; or nitrogen-containing compounds such as, in particular, 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), or 1,5-diazabicyclo[4.3.0]non-5-ene (DBN). Preferably, such catalysts are a component of a first component containing polyols.

[0095] Suitable catalysts are further catalysts for the hydrolysis of aldimine groups, in particular organic acids, especially an aromatic carboxylic acid such as 2-nitrobenzoic acid or salicylic acid. Preferably, such catalysts are a component of a first component containing aldimines.

[0096] Suitable fillers include, in particular, ground or precipitated calcium carbonates, optionally coated with fatty acids, especially stearates; barites (barytes); quartz flours; quartz sands; dolomites; wollastonites; kaolins; calcined kaolins; silica; silicic kaolinites; calcined silicic kaolinites; layered silicates such as mica or talc; zeolites; aluminum hydroxides; magnesium hydroxides; highly dispersed silicas from pyrolysis processes; industrially produced carbon black; graphite; ground fillers from agricultural sources, such as olive kernel flour or nutshell flour; metal powders, for example, of aluminum, copper, iron, silver, or steel; PVC powders; or hollow spheres. Calcium carbonates, barites, quartz flours, quartz sands, kaolins, or aluminum hydroxides are particularly preferred.

[0097] Suitable pigments include titanium dioxide, chromium oxide, iron oxides, and organic pigments. Pigments can be used as a paste-like preparation, also called color paste, particularly as a dispersion in a dimethacrylate.

[0098] Suitable adhesion promoters are in particular titanates or organoalkoxysilanes such as epoxysilanes, especially 3-glycidoxypropyltrimethoxysilane or 3-glycidoxypropyltriethoxysilane, aminosilanes, iminosilanes, mercaptosilanes, vinylsilanes, (meth)acrylosilanes, carbamatosilanes, alkylsilanes, S-(alkylcarbonyl)mer-captosilanes or oligomeric forms of these silanes.

[0099] Suitable stabilizers are in particular stabilizers against oxidation, heat, light or UV radiation.

[0100] The curable coating may contain other components commonly used in polyurethane coatings, in particular

[0101] - Desiccants, in particular molecular sieves, calcium oxide, mono-oxazolidines such as Incozol®2 (from Incorez), orthoesters or alkoxysilanes;

[0102] - Plasticizers, in particular phthalates, especially diisononyl phthalate (DINP), diisodecyl phthalate (DIDP) or di(2-propylheptyl) phthalate (DPHP), hydrogenated phthalates, in particular diisononyl-1,2-cyclohexanedicarboxylate (DINCH), terephthalates, hydrogenated terephthalates, isophthalates, trimellitates, adipates, in particular dioctyl adipate (DOA), azelates, sebacates, benzoates, glycol ethers, glycol esters, plasticizers with a polyether structure, in particular polypropylene oxide monols, diols or triols with blocked hydroxyl groups, in particular in the form of acetate groups, or organic sulfonates or phosphates, in particular diphenylcresyl phosphate (DPK) or tris-2-ethylhexyl phosphate (TOF), polybutenes, polyisobutenes or plasticizers derived from natural fats or oils, in particular rapeseed oil methyl esters,

[0103] - Rheology modifiers, in particular urea compounds, layered silicates such as bentonites, derivatives of castor oil, hydrogenated castor oil, polyamides, polyurethanes, pyrogenic silicas or hydrophobically modified polyoxyethylenes, - Fibers, in particular glass fibers, carbon fibers, metal fibers, ceramic fibers, hemp fibers, cellulose fibers or plastic fibers such as polyamide fibers or polyethylene fibers,

[0104] - Nanofillers or nanofibers such as graphene or carbon nanotubes,

[0105] - flame-retardant substances, in particular the fillers already mentioned: aluminium hydroxide or magnesium hydroxide, or organic phosphoric acid esters or ammonium polyphosphates,

[0106] as well as other substances commonly used in curable coatings. It may be useful to dry certain substances chemically or physically before use.

[0107] The other components mentioned may be present in the first and / or the second component. Components reactive with isocyanate groups are preferentially found in the first component.

[0108] The first and second components of the curable coating are manufactured separately. The ingredients of each component are mixed together to create a macroscopically homogeneous liquid or paste. The first and second components are stored in separate containers and are each stable on their own.

[0109] For the application and curing of the curable coating, the two components are mixed together.

[0110] The mixing ratio is selected such that the ratio of the number of isocyanate groups to the sum of the number of hydroxyl groups, primary amine groups, secondary amine groups, aldimine groups, ketimine groups, and oxazolidine groups is within the preferred range. In parts by weight, the mixing ratio between the first and second components is preferably in the range of 10:1 to 1:10, and particularly 5:1 to 1:2.

[0111] The components are mixed using a suitable method, in particular by means of a commercially available agitator or in a multi-component dosing and mixing system.

[0112] Mixing preferably takes place at ambient temperature or elevated temperature, in particular at a temperature of 15 to 80 °C.

[0113] Upon mixing the components, the curable coating begins to harden due to the onset of a chemical reaction. Existing hydroxyl groups and primary and secondary amine groups react with existing isocyanate groups. Aldimine, ketimine, or oxazolidine groups also react with isocyanate groups upon contact with moisture, undergoing hydrolysis. Any remaining isocyanate groups then react with moisture. Finally, any remaining primary or secondary amine groups can react with methacrylate groups.

[0114] The curing preferably takes place at ambient temperature, preferably at a temperature in the range of 5 to 50°C, in particular 10 to 40°C.

[0115] Another object of the invention is the cured coating obtained from the curable coating after mixing the components, applying the mixed liquid composition to at least one substrate and subsequent curing.

[0116] Preferably, the cured coating has a tensile strength of at least 3 MPa, preferably at least 6 MPa.

[0117] Preferably, the cured coating has an elongation at break of at least 5%, preferably at least 20%, and in particular at least 50%.

[0118] The tensile strength and elongation at break are determined according to DIN 53504 on films cured for 7 days in standard climate with a layer thickness of 2 mm using test specimens of type S2.

[0119] The application of the mixed coating can be carried out in various ways, depending on the processing time. The processing time depends in particular on the reactive groups and catalysts present, as well as the prevailing temperature.

[0120] Coatings with primary, aliphatic amine groups exhibit a very short processing time. The presence of aldimines allows for a slightly longer processing time. Coatings with predominantly polyols exhibit a significantly longer processing time.

[0121] Coatings with a processing time of a few seconds to a few minutes are advantageously applied using a spray gun. Coatings with a processing time of approximately 15 minutes or more can be mixed in a mixer and applied manually, particularly using a roller or squeegee, or from two-component cartridges with an attached static mixer, or also using a spray gun.

[0122] Suitable substrates onto which the coating is applied include in particular

[0123] - Concrete, mortar, cement screed, fiber cement, brick, tile, gypsum or natural stones such as granite or marble,

[0124] - Repair or leveling compounds based on PCC (polymer-modified cement mortar) or ECC (epoxy resin-modified cement mortar),

[0125] - Metals or alloys such as aluminium, iron, steel, copper, other non-ferrous metals, including surface-treated metals or alloys such as galvanised or chrome-plated metals,

[0126] - Asphalt or bitumen,

[0127] - Plastics such as rigid and flexible PVC, polycarbonate, polystyrene, polyester, polyamide, PMMA, ABS, SAN, epoxy resins, phenolic resins, PUR, POM, TPO, PE, PP, EPM or EPDM, either untreated or surface-treated, for example by plasma, corona or flames,

[0128] - fiber-reinforced plastics, such as carbon fiber reinforced plastics (CFRP), glass fiber reinforced plastics (GFRP), natural fiber reinforced plastics (NFRP) and sheet moulding compounds (SMC),

[0129] - Wood, bonded with resins, for example phenolic, melamine or epoxy resins, wood-based materials, resin-textile composites or other so-called polymer composites,

[0130] - Insulating materials, in particular foams, especially made of EPS, XPS, PUR, PIR, aerogel or foamed glass (Foamglas), or fibers made of rock wool or glass wool,

[0131] - coated or painted substrates, in particular painted tiles, painted concrete, powder-coated metals or alloys or painted sheet metal,

[0132] - Coatings, paints or varnishes,

[0133] - Glass or glass-ceramic, leather, textiles or paper.

[0134] The substrates are preferably free of oil, grease, or dust. They may be pretreated if necessary, in particular by physical and / or chemical cleaning processes or the application of an activator or primer.

[0135] Preferably, the coating is applied in a layer thickness of 0.1 to 8 mm, preferably 0.2 to 4 mm.

[0136] The curable coating is preferably used as an elastic to tough-elastic protective coating, in particular for protection against the penetration of moisture, water or other liquids or chemicals, as protection against mechanical stress, and as protection of metals or plastics against corrosion or damage caused by UV radiation.

[0137] The coating is preferably used as a roof coating, bridge coating, balcony or terrace coating, for sealing structures, especially foundations, as a floor coating in parking garages, garages, basements, warehouses or industrial halls, in the food industry, in kitchens or hospitals, as a protective coating in drinking water systems, swimming pools, sewage treatment plants, pipelines, in mining, for marine structures, as a coating for corrosion and wear protection of vehicles such as automobiles, trains or ships, or rotor blades of wind turbines, as well as a protective coating for plastics of all kinds.

[0138] Examples

[0139] The following are exemplary embodiments intended to further illustrate the described invention. Of course, the invention is not limited to these described embodiments.

[0140] A temperature of 23+1 °C and a relative humidity of 50+5% are defined as "standard climate" ("NC"). Unless otherwise stated, the chemicals used were supplied by Sigma-Aldrich Chemie GmbH.

[0141] Viscosities were measured at a temperature of 23 °C using a cone-plate rotational viscometer (Anton Paar M302) with a shear rate of 50 s⁻¹. -1 .

[0142] Substances used and abbreviations:

[0143] IPDI oligomer containing isophorone diisocyanate oligomers with isocyanurate groups, NCO content 17.3 wt.%, Vestanat® T 1890 / 100 from Evonik

[0144] ED-DMA 1,2-ethanediol dimethacrylate, Sartomer® SR 206, from Arkema BD-DMA 1,4-butanediol dimethacrylate, Sartomer® SR 214, from Arkema TEG-DMA triethylene glycol dimethacrylate, Sartomer® SR 205 H, from Arkema

[0145] HD-DMA 1,6-Hexanediol dimethacrylate, Sartomer® SR 239 EU, from Arkema

[0146] DD-DMA 1,10-Decanediol dimethacrylate, Sartomer® SR 261, from Arkema PEG(200)-DMA dimethacrylate of polyethylene glycol with M n approx. 200 g / mol,

[0147] Sartomer® SR 210 HH, from Arkema

[0148] PEG(600)-DMA dimethacrylate of polyethylene glycol with M n approx. 600 g / mol,

[0149] Sartomer® SR 252, by Arkema

[0150] TMP-TMA 1 , 1 , 1 -Trimethylolpropane trimethacrylate, Sartomer® SR 350 D, from Arkema

[0151] Polyol-1 PolyTHF 1000, OH number 112 mg KOH / g, Terathane® 1000

[0152] PTMEG, from Invista

[0153] Polyol-2 saturated polyester diol, OH number 112 mg KOH / g, Oxyester® T 1136, from Evonik

[0154] Production of hardeners:

[0155] Hardness H1 to H14:

[0156] For each hardener, the methacrylate specified in Tables 1 and 2 was placed in a round-bottom flask in the specified quantity (in parts by weight) under a nitrogen atmosphere, mixed with the IPDI oligomer in the specified quantity (in parts by weight), stirred vigorously at 60 °C using a magnetic stirrer, and the time until the IPDI oligomer was completely dissolved was measured. The resulting hardener was then cooled to room temperature and stored in a sealed container in the absence of moisture.

[0157] Tables 1 and 2 list the time required for the IPDI oligomer to dissolve completely under the heading "Dissolution Behavior." The dissolution behavior is further evaluated using the following scale:

[0158] Very good: complete dissolution of the IPDI oligomer within 3 hours.

[0159] Good: complete dissolution of the IPDI oligomer within 5 h

[0160] OK: complete dissolution of the IPDI oligomer within 10 h. Bad: incomplete dissolution of the IPDI oligomer within 10 h. The viscosity of the hardeners was determined at 23 °C after 24 h storage in a sealed container at room temperature.

[0161] The NCO content of the hardener was determined titrimetrically after 24 hours of storage in a sealed container at room temperature.

[0162] The results are shown in Tables 1 and 2.

[0163] The hardeners H13 (Ref.) and H14 (Ref.) designated with "(Ref.)" are non-inventive comparative examples with methacrylates which do not correspond to formula (I).

[0164]

[0165] Table 1: Composition and properties of hardeners H1 to H7.

[0166] > >

[0167]

[0168] Table 2: Composition and properties of hardeners H8 to H14.

[0169] "nm" stands for "not measurable" (not fully solved)

[0170] Tables 1 and 2 show that ED-DMA and BD-DMA (hardeners H1 to H6) exhibited good dissolution properties and yielded particularly low-viscosity hardeners, with the viscosity depending on the amount of dissolved IPDI oligomer. Furthermore, it is evident that TEG-DMA (hardeners H7 to H9) showed very good dissolution properties and produced somewhat higher-viscosity hardeners, which were still manageable. It is also evident that HD-DMA, DD-DMA, and PEG(200)-DMA were still usable with regard to their dissolution properties (hardeners H10 to H12), with the viscosity of the hardeners being within a usable range with HD-DMA, somewhat higher with DD-DMA, and quite high with PEG(200)-DMA. PEG(600)-DMA and TMP-TMA, which are both not dimeth acrylates of formula (I), showed poor solubility, as complete dissolution of the IPDI oligomer did not occur within 12 hours at 60 °C (hardeners H13 (Ref.) and H14 (Ref.)).

[0171]

[0172] with

[0173]

[0174] Hardener H15 to H17:

[0175] The ingredients listed in Table 3 were mixed in the specified amounts (in parts by weight) under a nitrogen atmosphere and reacted at 80 °C until the titrimetrically determined NCO content was stable. The reaction product was then cooled and stored in the absence of atmospheric moisture.

[0176] The appearance of the hardener obtained was assessed visually. A hardener without cloudiness, streaks, or visible inhomogeneities was described as "clear." The viscosity of the hardener was determined at 23 °C after 24 hours of storage in a sealed container at room temperature.

[0177] The NCO content of the hardener was determined titrimetrically after 24 hours of storage in a sealed container at room temperature.

[0178] The properties of hardeners H15 to H17 are given in Table 3.

[0179]

[0180] Table 3: Composition and properties of hardeners H15 to H17.

[0181] Production of curable coatings:

[0182] Composition Z1 (sprayed polyurea coating):

[0183] A first component was produced by mixing the following ingredients in the specified amounts in parts by weight (Wt) in a dissolver under vacuum and exclusion of atmospheric humidity, and storing them in a moisture-proof package for 14 days:

[0184] 20.0 GT Dimer fatty acid based diamine (Priamine® 1075, amine eguivalent weight 274 g / eg, from Cargill),

[0185] 25.0 GT Poly(oxy-1,2-propylene)diamine (Jeffamine® D-2000, amine equivalent weight 1028 g / eg, from Huntsman,

[0186] 5.3 GT N,N'-Diisobutylidenisophoronediamine (Vestamin® A 139, aldimine eguivalent weight 140 g / eg, from Evonik)

[0187] 30.9 GT Aluminum Trihydroxide Powder (ATH)

[0188] 10.0 GT Pigment Paste

[0189] 4.0 GT PTFE Powder

[0190] 3.6 GT Additives (UV stabilizers, wetting agents, rheology additive, defoamer) 1.0 GT Epoxysilane

[0191] 0.2 GT Dibutyltin diacetate

[0192] The viscosity of the first component at 23 °C was 0.83 Pa s. The density of the first component was 1.2 g / ml. The previously prepared hardener H15 was used as the second component, with a density of 1.08 g / ml, a viscosity of 0.9 Pa and an NCO content of 7.5 wt.%.

[0193] For application, both components were heated to a temperature of 70 °C, mixed in a 1:1 volume ratio using a spraying apparatus, and applied to a flat floor surface in a layer thickness of 2 mm. Application was carried out using a GAMA Evolution VR high-pressure metering machine with a counter-current injection mixing chamber and a rotary nozzle. The discharge rate was 95 g / s, the pressure during spraying was approximately 185 to 190 bar, and the ambient conditions were 20 °C and 50% relative humidity.

[0194] The polyurea coating proved to be very easy to work with. The mixed coating could be applied without hardening in the spray nozzle and without "burr formation" (the build-up of a hardened layer at the spray nozzle). The applied coating cured sufficiently within a few minutes to be walkable. The resulting cured coating exhibited a homogeneous, even, only slightly uneven surface without patterns, streaks, waves, craters, or bubbles.

[0195] To determine the mechanical properties, the coating was applied to a polyethylene film in a layer thickness of 2 mm and removed after curing. After storage for 7 days under standard climatic conditions, the tensile strength was 20 MPa and the elongation at break was 5%, determined on punched-out test specimens of type S2 according to DIN 53504.

[0196] The Shore D hardness was 64, determined according to ISO 7619-1 on injected test specimens with a layer thickness of 5 mm after a storage period of 7 days in standard climate.

[0197] The Taber abrasion value was 600 mg weight loss, determined using a Taber 5151 abrasion device, CS10 abrasion wheels at a 1 kg weight load and 500 cycles, on an aluminum sheet (100 mm x 100 mm) coated with a 2 mm layer thickness after a storage period of 7 days under standard climatic conditions. Compositions Z2 to Z4: (hand-applied polyurea coatings)

[0198] The first component used was Sikafloor® TC 681 Component A (from Sika). Sikafloor® TC 681 is a two-component, fast-curing polyaspartic sealant for parking deck coatings. Component A is based on a diamine with two secondary amine groups (Desmophen® NH 1420 from Covestro) and contains fillers and pigments. The amine equivalent weight of Component A is 975 g / eq, and its density is 1.74 g / cm³. 3

[0199] As a second component, the previously prepared hardener H7 or H8 was used, as specified in Table 4, along with Sikafloor® TC 681 Component B (from Sika) as a reference. Sikafloor® TC 681 Component B is based on a trimer of 1,6-hexane diisocyanate partially reacted with monol and contains xylene.

[0200] The two components were dosed in the mixing ratio specified in Table 4 and thoroughly mixed by hand using a spatula until a homogeneous-looking liquid was obtained. This was then immediately tested as follows:

[0201] The viscosity of the mixture was determined 5 minutes after the end of mixing at 23 °C. The odor was assessed by smelling the freshly mixed mixture from a distance of 30 cm.

[0202] The processing time was determined by regularly stirring a freshly mixed quantity of 25 g in an open container with a spatula until the mixture gelled.

[0203] The time until the coating became tack-free was determined by regularly touching a freshly applied 2 mm thick coating after it had gelled, until the surface of the coating was no longer tacky. Whether the tack-free coating felt hard or soft to the touch at this point is indicated in parentheses.

[0204] The Shore D hardness was determined on test specimens with a layer thickness of 5 mm after a storage time of 1 day or 7 days in standard climate according to ISO 7619-1. The tensile strength and elongation at break were determined on stamped test specimens of type S2 with a thickness of 2 mm after curing for 7 days in standard climate according to DIN 53504.

[0205]

[0206] Table 4: Composition and properties of compositions Z2 to Z4.

[0207] Composition Z5: (hand-applied polyurethane coating) The first component used was Sikafloor® 3000 Component A (from Sika). Sikafloor® 3000 is a two-component, highly elastic polyurethane coating for floors. Component A is based on polyether polyols and castor oil and contains fillers and pigments.

[0208] The previously prepared hardener H2 was used as the second component. The two components were dosed in the mixing ratio specified in Table 5 and thoroughly mixed by hand using a spatula until a homogeneous-looking liquid was obtained, and then immediately tested as follows:

[0209] The odor, processing time, and time until tackiness was determined as described for composition Z2.

[0210] The Shore A hardness was determined on test specimens with a layer thickness of 5 mm after a storage time of 14 days in standard climate according to ISO 7619-1.

[0211] The tensile strength and elongation at break were determined on stamped test specimens of type S2 with a thickness of 2 mm after curing for 14 days in standard climate according to DIN 53504.

[0212]

[0213] Table 5: Composition and properties of composition Z5.

Claims

Patent claims:

1. Hardener based on isophorone diisocyanate oligomers, encompassing the entire hardener - 25 to 70 wt% isophorone diisocyanate oligomers, optionally in the form of reaction products with at least one polyol, - 25 to 75 wt% dimethacrylates of formula (I), where A represents a divalent alkylene residue with 2 to 12 carbon atoms or a polyether residue with 4 to 14 carbon atoms, and - 0 to 30% by weight of other substances.

2. Hardener according to claim 1, characterized in that the isophorone diisocyanate oligomers contain isocyanurate groups.

3. Hardener according to one of claims 1 or 2, characterized in that the dimethacrylate of formula (I) is selected from the list consisting of 1,2-ethanediol dimethacrylate, 1,2-propanediol dimethacrylate, 1,3-propanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,8-octanediol dimethacrylate, 1,10-decanediol dimethacrylate, 1,12-dodecanediol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, tripropylene glycol dimethacrylate methacrylate and tetrapropylene glycol dimethacrylate.

4. Hardener according to any one of claims 1 to 3, characterized in that the NCO content, based on the total hardener, is in the range of 4.3 to 12.1 wt%, in particular 5 to 11 wt%.

5. Hardener according to any one of claims 1 to 4, characterized in that the isophorone diisocyanate oligomers are contained proportionally in the form of reaction products with at least one diol having an OH number of 28 to 280 mg KOH / g.

6. Hardener according to claim 5, characterized in that the diol is selected from the list consisting of polyether diols, polyester diols and polycarbonate diols.

7. Hardener according to one of claims 1 to 6, characterized in that, with respect to the entire hardener - 40 to 65 wt% isophorone diisocyanate oligomers, optionally in the form of reaction products with at least one diol having an OH number of 28 to 280 mg KOH / g, - 30 to 60 wt%, in particular 40 to 55 wt%, dimethacrylates of formula (I), and - 0 to 20 wt%, preferably 0 to 10 wt%, in particular 0 to 5 wt%, other substances are included.

8. Hardener according to any one of claims 1 to 7, characterized in that, based on the total hardener, less than 1 wt% organic solvents with a boiling point at normal pressure of less than 250 °C are contained.

9. Method for producing the hardener according to any one of claims 1 to 8, comprising the steps (i) Presenting the dimethacrylate of formula (I), (ii) Addition of the isophorone diisocyanate oligomers, (iii) Stir the mixture until the isophorone diisocyanate oligomers are completely dissolved, (iv) optionally adding at least one polyol and allowing to react until all OH groups have reacted.

10. Use of the hardener according to any one of claims 1 to 8 for curing a composition containing reactive groups selected from hydroxyl groups, primary amine groups, secondary amine groups, aldimine groups, ketimine groups and oxazolidine groups.

11. Curable coating including - a first component containing at least one polyol and / or at least one polyamine with at least two primary or secondary amine groups, and - a second component comprising or consisting of the hardener according to any one of claims 1 to 8.

12. Curable coating according to claim 11, characterized in that the first component contains at least one polyamine with at least two primary or secondary amine groups.

13. Curable coating according to one of claims 11 to 12, characterized in that the first component contains at least one copper, iron or zinc catalyst.

14. Curable coating according to one of claims 11 to 13, characterized in that it contains at least one further component selected from the list consisting of catalysts, fillers, pigments, adhesion promoters, stabilizers, defoamers and wetting agents.

15. Cured coating obtained from the curable coating according to one of claims 11 to 14 after mixing the components, applying the mixed liquid composition to at least one substrate and subsequent curing.

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